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Sample records for nuclear neutron skin

  1. Neutron skin thickness and nuclear matter properties

    NASA Astrophysics Data System (ADS)

    Yoshida, S.; Sagawa, H.

    2007-08-01

    Linear correlations are found among the isovector nuclear matter properties in both the Skyrme-Hartree-Fock (SHF) and the relativistic mean-field (RMF) models. In addition, we found a kind of correlation between the isovector nuclear matter properties and the incompressibility in the SHF model. The Skyrme parameters are related analytically to nuclear matter properties with the Thomas—Fermi approximation. By using a linear correlation between the neutron skin thickness and the pressure of the neutron matter in the SHF model, we show that the neutron skin thickness of 208Pb gives crucial information about not only the neutron equation of state but also the isovector nuclear matter properties and the parametrization of Skyrme interaction.

  2. Isoscalar and isovector nuclear matter properties and neutron skin thickness

    NASA Astrophysics Data System (ADS)

    Sagawa, H.; Yoshida, S.

    2007-11-01

    Isoscalar and isovector nuclear matter properties are investigated in the Skyrme Hartree-Fock (SHF) and the relativistic mean field (RMF) models. The Skyrme parameters are related analytically to the isoscalar and the isovector nuclear matter properties of the Hamiltonian density. Linear correlations are found among the isovector nuclear matter properties of the Hamiltonian density in both the SHF and the RMF models. We also discovered that the correlations between the isovector properties and the incompressibility K show a singularity at the critical incompressibility Kc=306 MeV. It is shown that the neutron skin thickness gives crucial information about not only for the neutron EOS but also about the isovector nuclear matter properties and about the parameterization of Skyrme interaction. Charge exchange spin-dipole (SD) excitations are proposed to determine the neutron skin thickness model independently.

  3. Isovector nuclear matter properties and neutron skin thickness

    NASA Astrophysics Data System (ADS)

    Yoshida, Satoshi; Sagawa, Hiroyuki

    2006-04-01

    Correlations among several nuclear matter properties are investigated in the Skyrme Hartree-Fock (SHF) and the relativistic mean field (RMF) models. The Skyrme parameters are related analytically to the isoscalar and isovector nuclear matter properties of the Hamiltonian density. Linear correlations are found among the isovector nuclear matter properties of the Hamiltonian density in both the SHF and the RMF models. We show analytically a singularity at the incompressibility Kc=306 MeV in correlations between the isovector nuclear matter properties and incompressibility with the SHF model, whereas there is no obvious singularity in those correlations with the RMF model. A linear correlation between the neutron skin thickness and the pressure of the neutron matter is given in terms of the ratio between the neutron and nuclear matter densities in the SHF model. We show that the neutron skin thickness gives crucial information about not only the neutron equation of state but also the isovector nuclear matter properties and the parametrization of the Skyrme interaction.

  4. Neutron Skin and Equation of State in Asymmetric Nuclear Matter

    NASA Astrophysics Data System (ADS)

    Yoshida, Satoshi; Sagawa, Hiroyuki

    2005-12-01

    Neutron skin thickness of stable and unstable nuclei are studied by using Skyrme Hartree-Fock (SHF) models and relativistic mean field (RMF) models in relation with the pressure of EOS in neutron matter. We found a clear linear correlation between the neutron skin sizes in heavy nuclei, 132Sn and 208Pb and the pressure of neutron matter in both SHF and RMF, while the correlation is weak in unstable nuclei 32Mg and 44Ar.

  5. Neutron skin thickness and equation of state in asymmetric nuclear matter

    NASA Astrophysics Data System (ADS)

    Yoshida, Satoshi; Sagawa, Hiroyuki

    2004-02-01

    The neutron skin thickness of stable and unstable nuclei is studied in Skyrme Hartree-Fock (SHF) and relativistic mean field (RMF) models to investigate the relation between the pressure and the equation of state in neutron matter. We found a clear linear correlation between the neutron skin thickness in heavy nuclei 132 Sn and 208 Pb and the pressure of neutron matter in both SHF and RMF models, while the correlation is weak in the unstable nuclei 32 Mg and 44 Ar . Relations between the neutron skin thickness and other nuclear matter properties such as the symmetry energy coefficients and the nuclear incompressibility are discussed.

  6. Neutron skin of (208)Pb, nuclear symmetry energy, and the parity radius experiment.

    PubMed

    Roca-Maza, X; Centelles, M; Viñas, X; Warda, M

    2011-06-24

    A precise determination of the neutron skin Δr(np) of a heavy nucleus sets a basic constraint on the nuclear symmetry energy (Δr(np) is the difference of the neutron and proton rms radii of the nucleus). The parity radius experiment (PREX) may achieve it by electroweak parity-violating electron scattering (PVES) on (208)Pb. We investigate PVES in nuclear mean field approach to allow the accurate extraction of Δr(np) of (208)Pb from the parity-violating asymmetry A(PV) probed in the experiment. We demonstrate a high linear correlation between A(PV) and Δr(np) in successful mean field forces as the best means to constrain the neutron skin of (208)Pb from PREX, without assumptions on the neutron density shape. Continuation of the experiment with higher precision in A(PV) is motivated since the present method can support it to constrain the density slope of the nuclear symmetry energy to new accuracy.

  7. Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei

    SciTech Connect

    Chen Liewen; Ko Che Ming; Xu Jun; Li Baoan

    2010-08-15

    Expressing explicitly the parameters of the standard Skyrme interaction in terms of the macroscopic properties of asymmetric nuclear matter, we show in the Skyrme-Hartree-Fock approach that unambiguous correlations exist between observables of finite nuclei and nuclear matter properties. We find that existing data on neutron skin thickness {Delta}r{sub np} of Sn isotopes give an important constraint on the symmetry energy E{sub sym}({rho}{sub 0}) and its density slope L at saturation density {rho}{sub 0}. Combining these constraints with those from recent analyses of isospin diffusion and the double neutron/proton ratio in heavy-ion collisions at intermediate energies leads to a more stringent limit on L approximately independent of E{sub sym}({rho}{sub 0}). The implication of these new constraints on the {Delta}r{sub np} of {sup 208}Pb as well as the core-crust transition density and pressure in neutron stars is discussed.

  8. Nuclear mass formula with a neutron skin degree of freedom and finite-range model for the surface energy

    SciTech Connect

    Moeller, P.; Myers, W.D.

    1984-03-01

    We study the possibility of extending the model used by Moeller and Nix in 1980 to calculate nuclear masses and fission barriers for nuclei throughout the periodic system, to describe compressibility effects and the existence of a neutron skin. 9 references. (WHK)

  9. Asymmetric nuclear matter and neutron skin in an extended relativistic mean-field model

    SciTech Connect

    Agrawal, B. K.

    2010-03-15

    The density dependence of the symmetry energy, instrumental in understanding the behavior of the asymmetric nuclear matter, is investigated within the extended relativistic mean-field (ERMF) model, which includes the contributions from the self- and mixed-interaction terms for the scalar-isoscalar ({sigma}), vector-isoscalar ({omega}), and vector-isovector ({rho}) mesons up to the quartic order. Each of the 26 different parametrizations of the ERMF model employed is compatible with the bulk properties of the finite nuclei. The behavior of the symmetry energy for several parameter sets is found to be consistent with the empirical constraints on them as extracted from the analyses of the isospin diffusion data. The neutron-skin thickness in the {sup 208}Pb nucleus for these parameter sets of the ERMF model lies in the range of {approx}0.20-0.24 fm, which is in harmony with the thickness predicted by the Skyrme Hartree-Fock model. We also investigate the role of various mixed-interaction terms that are crucial for the density dependence of the symmetry energy.

  10. Charge-Exchange Excitation of the Isobaric Analog State and Implication for the Nuclear Symmetry Energy and Neutron Skin

    NASA Astrophysics Data System (ADS)

    Khoa, Dao T.; Loc, Bui Minh; Zegers, R. G. T.

    The charge-exchange (p, n) or (3He,t) reaction can be considered as elastic scattering of proton or 3He by the isovector term of the optical potential that flips the projectile isospin. Therefore, the accurately measured charge-exchange scattering cross section for the isobaric analog states can be a good probe of the isospin dependence of the optical potential, which is determined exclusively within the folding model by the difference between the neutron and proton densities and isospin dependence of the nucleon-nucleon interaction. On the other hand, the same isospin- and density-dependent nucleon-nucleon interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part. As a result, the fine-tuning of the isospin dependence of the effective nucleon-nucleon interaction against the measured (p, n) or (3He,t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. Moreover, given the neutron skin of the target related directly to the neutron-proton difference of the ground-state density, it can be well probed in the analysis of the charge-exchange (3He,t) reactions at medium energies when the two-step processes can be neglected and the t-matrix interaction can be used in the folding calculation.

  11. Neutron density distribution and neutron skin thickness of Pb208

    NASA Astrophysics Data System (ADS)

    Meucci, Andrea; Vorabbi, Matteo; Giusti, Carlotta; Finelli, Paolo

    2014-08-01

    We present and discuss numerical predictions for the neutron density distribution of Pb208 using various nonrelativistic and relativistic mean-field models for the nuclear structure. Our results are compared with the very recent pion photoproduction data from Mainz. The parity-violating asymmetry parameter for elastic electron scattering at the kinematics of the PREX experiment at JLab and the neutron skin thickness are compared with the available data. We consider also the dependence between the neutron skin and the parameters of the expansion of the symmetry energy.

  12. Pygmy resonances and neutron skins

    SciTech Connect

    Piekarewicz, J.

    2011-03-15

    In a study motivated by a recent experiment, the distribution of electric dipole strength in the neutron-rich {sup 68}Ni isotope was computed using a relativistic random-phase approximation with a set of effective interactions that - although well calibrated - predict significantly different values for the neutron-skin thickness in {sup 208}Pb. The emergence of low-energy 'pygmy' strength that exhausts about 5%-8% of the energy-weighted sum rule (EWSR) is clearly identified. In addition to the EWSR, special emphasis is placed on the dipole polarizability. In particular, our results suggest a strong correlation between the dipole polarizability of {sup 68}Ni and the neutron-skin thickness of {sup 208}Pb. Yet we find a correlation just as strong, and an even larger sensitivity, between the neutron-skin thickness of {sup 208}Pb and the fraction of the dipole polarizability exhausted by the pygmy resonance. These findings suggest that dipole polarizability may be used as a proxy for the neutron skin.

  13. Probing the neutron skin thickness in collective modes of excitation

    NASA Astrophysics Data System (ADS)

    Paar, N.; Horvat, A.

    2014-03-01

    Nuclear collective motion provides valuable constraint on the size of neutron-skin thickness and the properties of nuclear matter symmetry energy. By employing relativistic nuclear energy density functional (RNEDF) and covariance analysis related to χ2 fitting of the model parameters, relevant observables are identified for dipole excitations, which strongly correlate with the neutron-skin thickness (rnp), symmetry energy at saturation density (J) and slope of the symmetry energy (L). Using the RNEDF framework and experimental data on pygmy dipole strength (68Ni, 132Sn, 208Pb) and dipole polarizability (208Pb), it is shown how the values of J, and L, and rnp are constrained. The isotopic dependence of moments associated to dipole excitations in 116-136Sn shows that the low-energy dipole strength and polarizability in neutron-rich nuclei display strong sensitivity to the symmetry energy parameter J, more pronounced than in isotopes with moderate neutron-to-proton number ratios.

  14. Neutron skin thickness and neutron star equations of state: a strong relationship

    SciTech Connect

    Menezes, D. P.; Avancini, S. S.; Marinelli, J. R.; Watanabe de Moraes, M. M.; Providencia, C.

    2007-10-26

    A density dependent hadronic model and a common parametrization of the non-linear Walecka model are used to obtain the lead neutron skin thickness through its proton and neutron density profiles. The neutron skin thickness is known to reflect the equation of state properties. A direct correlation between the neutron skin thickness and the slope of the symmetry energy is found.

  15. Target Neutron Skin Effect on Projectile Fragmentation

    NASA Astrophysics Data System (ADS)

    Laforest, R.; Ramakrishnan, E.; Rowland, D. J.; Winchester, E.; Delafield, R.; Guzman, S. J.; Yennello, S.

    1998-04-01

    Several experimental observables have concluded that projectile fragmentation occurs as a two step process, excitation followed by the sequential decay of the quasi-projectile. However, recent measurements [1] have shown that neutron rich fragments are emitted with smaller velocities than what is expected from the decay of the projectile. A direct breakup mechanism for projectile fragmentation was suggested to explain the data. This direct breakup component depends on the number of neutrons at the zone of contact between the target and the projectile. Experimental data from the reactions of ^28Si on ^112,124Sn targets at 50A MeV were used to study the effect of the neutron skin of the target on projectile fragmentation and on energy dissipation in peripheral collisions. The FAUST forward array was used to detect fragments in the angular range between 1.6 to 33.6 degrees. It is composed of 68 high resolution Si-Csi(Tl) telescopes that allows for isotope identification. It is seen that the neutron rich target yields more neutron rich fragments and a lower fragment multiplicity. This confirms the importance of the direct breakup component. Proton kinetic energy spectra were also different for the two targets. This experimental information can shed some light on the isospin dependence of the equation of state. [1] R. Charity et al., Phys. Rev. C52 (1995) 1.

  16. Nuclear Physics of neutron stars

    NASA Astrophysics Data System (ADS)

    Piekarewicz, Jorge

    2015-04-01

    One of the overarching questions posed by the recent community report entitled ``Nuclear Physics: Exploring the Heart of Matter'' asks How Does Subatomic Matter Organize Itself and What Phenomena Emerge? With their enormous dynamic range in both density and neutron-proton asymmetry, neutron stars provide ideal laboratories to answer this critical challenge. Indeed, a neutron star is a gold mine for the study of physical phenomena that cut across a variety of disciplines, from particle physics to general relativity. In this presentation--targeted at non-experts--I will focus on the essential role that nuclear physics plays in constraining the dynamics, structure, and composition of neutron stars. In particular, I will discuss some of the many exotic states of matter that are speculated to exist in a neutron star and the impact of nuclear-physics experiments on elucidating their fascinating nature. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under Award Number DE-FD05-92ER40750.

  17. Diversity of neutron star properties at the fixed neutron-skin thickness of 208Pb

    NASA Astrophysics Data System (ADS)

    Alam, N.; Sulaksono, A.; Agrawal, B. K.

    2015-07-01

    We study the diversities in the properties of the neutron stars arising due to the different choices for the cross coupling between various mesons, which governs the density dependence of the nuclear symmetry energy in the extended relativistic mean-field (RMF) model. For this purpose, we obtain two different families of the extended RMF model corresponding to different nonlinear cross-coupling terms in the isovector part of the effective Lagrangian density. The lowest-order contributions for the δ mesons are also included. The different models within the same family yield wide variation in the value of neutron-skin thickness in the 208Pb nucleus. These models are employed to compute the neutron-star properties such as core-crust transition density, radius and red shift at canonical mass ( 1.4 M⊙) , tidal polarizability parameter, and threshold mass required for the enhanced cooling through the direct Urca process. Most of the neutron-star properties considered are significantly different(10-40%) for the different families of models at a smaller neutron-skin thickness (˜0.15 fm ) in the 208Pb nucleus.

  18. Sensitivity of the electric dipole polarizability to the neutron skin thickness in {sup 208}Pb

    SciTech Connect

    Roca-Maza, X.; Agrawal, B. K.; Colo, G.; Nazarewicz, W.; Paar, N.; Piekarewicz, J.; Reinhard, P.-G.; Vretenar, D.

    2012-10-20

    The static dipole polarizability, {alpha}{sub D}, in {sup 208}Pb has been recently measured with highresolution via proton inelastic scattering at the Research Center for Nuclear Physics (RCNP) [1]. This observable is thought to be intimately connected with the neutron skin thickness, r{sub skin}, of the same nucleus and, more fundamentally, it is believed to be associated with the density dependence of the nuclear symmetry energy. The impact of r{sub skin} on {alpha}{sub D} in {sup 208}Pb is investigated and discussed on the basis of a large and representative set of relativistic and non-relativistic nuclear energy density functionals (EDF) [2].

  19. NEUTRON AND NON-NEUTRON NUCLEAR DATA FOR RADIATION DOSIMETRY

    SciTech Connect

    HOLDEN,N.E.

    1999-09-10

    NEUTRON NUCLEAR DATA THAT IS USED IN REACTOR DOSIMETRY INCLUDE THERMAL NEUTRON CROSS SECTIONS AND NEUTRON RESONANCE INTEGRALS, FISSION SPECTRUM AVERAGED CROSS SECTIONS FOR REACTIONS ON A TARGET NUCLEUS. NON-NEUTRON NUCLEAR DATA USED IN REACTOR DOSIMETRY INCLUDE ISOTOPIC COMPOSITIONS OF TARGET NUCLIDES AND RADIOACTIVE HALF-LIVES, GAMMA-RAY ENERGIES AND INTENSITIES OF REACTION PRODUCT NUCLIDES. ALL OF THESE DATA ARE PERIODICALLY EVALUATED AND RECOMMENDED VALUES ARE PROVIDED IN THE HANDBOOK OF CHEMISTRY AND PHYSICS. THE LATEST RECOMMENDED VALUES ARE DISCUSSED AND THEY ARE CONTRASTED WITH SOME EARLIER NUCLEAR DATA, WHICH WAS PROVIDED WITH NEUTRON DETECTOR FOILS.

  20. Nuclear physics: Four neutrons together momentarily

    NASA Astrophysics Data System (ADS)

    Bertulani, Carlos A.; Zelevinsky, Vladimir

    2016-04-01

    A system of four neutrons known as the tetraneutron is a hypothetical state in nuclear physics. The report of evidence for the fleeting existence of this state has implications for research into neutron stars.

  1. The neutron skin in neutron-rich nuclei at Jefferson Lab

    SciTech Connect

    Dalton, Mark M.

    2013-11-01

    The Jefferson Lab program to measure the symmetry energy of neutron-rich nuclear matter, using precision electroweak methods, is progressing well. The initial measurement by the PREX experiment, leading to a 2-sigma determination of the "neutron skin" in {sup 208}Pb , has been published. Design and preparation for a further, more-precise measurement on {sup 208}Pb is progressing well and there is general acceptance of the great advantage to a further measurement on {sup 48}Ca . The surprising ancillary result that the beam-normal single-spin asymmetry for {sup 208}Pb is consistent with zero is also now in the literature. This paper will discuss the current experimental situation of the program.

  2. The neutron skin in neutron-rich nuclei at Jefferson Lab

    SciTech Connect

    Dalton, Mark M.

    2013-11-07

    The Jefferson Lab program to measure the symmetry energy of neutron-rich nuclear matter, using precision electroweak methods, is progressing well. The initial measurement by the PREX experiment, leading to a 2-sigma determination of the 'neutron skin' in {sup 208}Pb, has been published. Design and preparation for a further, more-precise measurement on {sup 208}Pb is progressing well and there is general acceptance of the great advantage to a further measurement on {sup 48}Ca. The surprising ancillary result that the beam-normal single-spin asymmetry for {sup 208}Pb is consistent with zero is also now in the literature. This paper will discuss the current experimental situation of the program.

  3. The nuclear physics of neutron stars

    SciTech Connect

    Piekarewicz, J.

    2014-05-09

    We explore the unique and fascinating structure of neutron stars. Although neutron stars are of interest in many areas of Physics, our aim is to provide an intellectual bridge between Nuclear Physics and Astrophysics. We argue against the naive perception of a neutron star as a uniform assembly of neutrons packed to enormous densities. Rather, by focusing on the many exotic phases that are speculated to exist in a neutron star, we show how the reality is different and far more interesting.

  4. Radii of neutron drops probed via the neutron skin thickness of nuclei

    NASA Astrophysics Data System (ADS)

    Zhao, P. W.; Gandolfi, S.

    2016-10-01

    Multineutron systems are crucial to understanding the physics of neutron-rich nuclei and neutron stars. Neutron drops, neutrons confined in an external field, are investigated systematically in both nonrelativistic and relativistic density functional theories and with ab initio calculations. We demonstrate a new strong linear correlation, which is universal in the realm of mean-field models, between the rms radii of neutron drops and the neutron skin thickness of 208Pb and 48Ca, i.e., the difference between the neutron and proton rms radii of a nucleus. Due to its high quality, this correlation can be used to deduce the radii of neutron drops from the measured neutron skin thickness in a model-independent way, and the radii obtained for neutron drops can provide a useful constraint for realistic three-neutron forces. We also present a new correlation between the slope L of the symmetry energy and the radii of neutron drops, and provide the first validation of such a correlation by using density-functional models and ab initio calculations. These newly established correlations, together with more precise measurements of the neutron skin thicknesses of 208Pb and 48Ca and/or accurate determinations of L , will have an enduring impact on the understanding of multineutron interactions, neutron-rich nuclei, neutron stars, etc.

  5. Uncertainty analysis of 208Pb neutron skin predictions with chiral interactions

    DOE PAGESBeta

    Sammarruca, Francesca

    2015-09-14

    Here, we report predictions for the neutron skin in 208Pb using chiral two- and three-body interactions at increasing orders of chiral effective field theory and varying resolution scales. Closely related quantities, such as the slope of the symmetry energy, are also discussed. As a result, the sensitivity of the skin to just pure neutron matter pressure when going from order 2 to order 4 of chiral effective theory is singled out in a set of calculations that employ an empirical equation of state for symmetric nuclear matter.

  6. Uncertainty analysis of 208Pb neutron skin predictions with chiral interactions

    SciTech Connect

    Sammarruca, Francesca

    2015-09-14

    Here, we report predictions for the neutron skin in 208Pb using chiral two- and three-body interactions at increasing orders of chiral effective field theory and varying resolution scales. Closely related quantities, such as the slope of the symmetry energy, are also discussed. As a result, the sensitivity of the skin to just pure neutron matter pressure when going from order 2 to order 4 of chiral effective theory is singled out in a set of calculations that employ an empirical equation of state for symmetric nuclear matter.

  7. A Clean Measurement of the Neutron Skin of 208Pb Through Parity Violating Electron Scattering

    SciTech Connect

    Riad Suleiman

    2003-07-01

    The difference between the neutron radius Rn of a heavy nucleus and the proton radius Rp is believed to be on the order of several percent. This qualitative feature of nuclei, which is essentially a neutron skin, has proven to be elusive to pin down experimentally in a rigorous fashion. A new Jefferson Lab experiment will measure the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 208Pb. Since the Z-boson couples mainly to neutrons, this asymmetry provides a measure of the size of Rn that can be interpreted with as much confidence as the traditional electron scattering data. The projected experimental precision corresponds to a 1% determination of Rn, which will have a big impact on nuclear theory and its application to neutron rich matter such as neutron stars.

  8. Review of Non-Neutron and Neutron Nuclear Data, 2004

    SciTech Connect

    Holden, Norman E.

    2005-05-24

    Review articles are in preparation for the 2004 edition of the CRC Handbook of Chemistry and Physics dealing with the evaluation of both non-neutron and neutron nuclear data. Data on the discovery of element 110, Darmstadtium, and element 111 have been officially accepted, while data on element 118 have been withdrawn. Data to be presented include revised values for very short-lived nuclides, long-lived nuclides, and beta-beta decay measurements. There has been a reassessment of the spontaneous fission (sf) half-lives, which distinguishes between sf decay half-lives and cluster decay half-lives, and with cluster-fission decay. New measurements of isotopic abundance values for many elements will be discussed with an emphasis on the minor isotopes of interest for use in neutron activation analysis measurements. Neutron resonance integrals will be discussed emphasizing the differences between the calculated values obtained from the analytical integration over neutron resonances and the measured values in a neutron reactor-spectrum, which does not quite conform to the assumed 1/E neutron energy spectrum. The method used to determine the neutron resonance integral from measurement, using neutron activation analysis, will be discussed.

  9. REVIEW OF NON-NEUTRON AND NEUTRON NUCLEAR DATA, 2004.

    SciTech Connect

    HOLDEN, N.E.

    2004-09-26

    Review articles are in preparation for the 2004 edition of the CRC Handbook of Chemistry and Physics dealing with the evaluation of both non-neutron and neutron nuclear data. Data on the discovery of element 110, Darmstadtium, and element 111 have been officially accepted, while data on element 11 8 have been withdrawn. Data to be presented include revised values for very short-lived nuclides, long-lived nuclides and beta-beta decay measurements. There has been a reassessment of the spontaneous fission (sf) half-lives, which distinguishes between sf decay half-lives and cluster decay half-lives and with cluster-fission decay. New measurements of isotopic abundance values for many elements will be discussed with an emphasis on the minor isotopes of interest for use in neutron activation analysis measurements. Neutron resonance integrals will be discussed emphasizing the differences between the calculated values obtained from the analytical integration over neutron resonances and the measured values in a neutron reactor-spectrum, which does not quite conform to the assumed 1/E neutron energy spectrum. The method used to determine the neutron resonance integral from measurement, using neutron activation analysis, will be discussed.

  10. Neutron absorbing coating for nuclear criticality control

    DOEpatents

    Mizia, Ronald E.; Wright, Richard N.; Swank, William D.; Lister, Tedd E.; Pinhero, Patrick J.

    2007-10-23

    A neutron absorbing coating for use on a substrate, and which provides nuclear criticality control is described and which includes a nickel, chromium, molybdenum, and gadolinium alloy having less than about 5% boron, by weight.

  11. Nuclear and neutron matter studies

    SciTech Connect

    Wiringa, R.B.; Akmal, A.; Pandharipande, V.R.

    1995-08-01

    We are studying nuclear and neutron matter with the new Argonne v{sub 18} NN and Urbana 3N potentials. We use variational wave functions and a diagrammatic cluster expansion with Fermi hypernetted and single-operator chain (FHNC/SOC) integral equations to evaluate the energy expectation value. Initial results show some interesting differences with our previous calculations with the older Argonne v{sub 14} potential. In particular, there are a number of diagrams involving L{center_dot}S and L{sup 2} terms which were small with the older model and were rather crudely estimated or even neglected. It appears that these terms are more important with the new potential and will have to be evaluated more accurately. Work on this subject is in progress. A simple line of attack is to just add additional diagrams at the three-body cluster level. A longer term approach may be to adapt some of the methods for evaluating nucleon clusters used in the few-body and closed shell nuclei described above.

  12. Neutron Skins and Halo Orbits in the sd and pf Shells.

    PubMed

    Bonnard, J; Lenzi, S M; Zuker, A P

    2016-05-27

    The strong dependence of Coulomb energies on nuclear radii makes it possible to extract the latter from calculations of the former. The resulting estimates of neutron skins indicate that two mechanisms are involved. The first one-isovector monopole polarizability-amounts to noting that when a particle is added to a system it drives the radii of neutrons and protons in different directions, tending to equalize the radii of both fluids independently of the neutron excess. This mechanism is well understood and the Duflo-Zuker (small) neutron skin values derived 14 years ago are consistent with recent measures and estimates. The alternative mechanism involves halo orbits whose huge sizes tend to make the neutron skins larger and have a subtle influence on the radial behavior of sd and pf shell nuclei. In particular, they account for the sudden rise in the isotope shifts of nuclei beyond N=28 and the near constancy of radii in the A=40-56 region. This mechanism, detected here for the first time, is not well understood and may well go beyond the Efimov physics usually associated with halo orbits.

  13. Neutron Skins and Halo Orbits in the sd and pf Shells.

    PubMed

    Bonnard, J; Lenzi, S M; Zuker, A P

    2016-05-27

    The strong dependence of Coulomb energies on nuclear radii makes it possible to extract the latter from calculations of the former. The resulting estimates of neutron skins indicate that two mechanisms are involved. The first one-isovector monopole polarizability-amounts to noting that when a particle is added to a system it drives the radii of neutrons and protons in different directions, tending to equalize the radii of both fluids independently of the neutron excess. This mechanism is well understood and the Duflo-Zuker (small) neutron skin values derived 14 years ago are consistent with recent measures and estimates. The alternative mechanism involves halo orbits whose huge sizes tend to make the neutron skins larger and have a subtle influence on the radial behavior of sd and pf shell nuclei. In particular, they account for the sudden rise in the isotope shifts of nuclei beyond N=28 and the near constancy of radii in the A=40-56 region. This mechanism, detected here for the first time, is not well understood and may well go beyond the Efimov physics usually associated with halo orbits. PMID:27284653

  14. Nuclear-spectroscopy problems studied with neutrons

    SciTech Connect

    Raman, S.

    1982-01-01

    Nuclear spectroscopy with neutrons continues to have a major impact on the progress of nuclear science. Neutrons, being uncharged, are particularly useful for the study of low energy reactions. Recent advances in time-of-flight spectroscopy, as well as in the gamma ray spectroscopy following neutron capture, have permitted precision studies of unbound and bound nuclear levels and related phenomena. By going to new energy domains, by using polarized beams and targets, through the invention of new kinds of detectors, and through the general improvement in beam quantity and quality, new features of nuclear structure and reactions have been obtained that are not ony interesting per se but are also grist for old and new theory mills. The above technical advances have opened up new opportunities for further discoveries.

  15. Calculations of the neutron skin and its effect in atomic parity violation

    SciTech Connect

    Brown, B. A.; Derevianko, A.; Flambaum, V. V.

    2009-03-15

    We perform calculations for the neutron skin of nuclei and its contribution to atomic parity nonconservation (PNC) in many isotopes of Cs, Ba, Sm, Dy, Yb, Tl, Pb, Bi, Fr, and Ra. Three problems are addressed: (i) neutron-skin-induced errors to single-isotope PNC, (ii) the possibility of measuring neutron skin using atomic PNC, and (iii) neutron-skin-induced errors for ratios of PNC effects in different isotopes. In the latter case the correlations in the neutron skin values for different isotopes lead to cancellations of the errors; this makes the isotopic ratio method a competitive tool in a search for new physics beyond the standard model.

  16. Density dependent hadronic models and the relation between neutron stars and neutron skin thickness

    SciTech Connect

    Avancini, S. S.; Marinelli, J. R.; Menezes, D. P.; Moraes, M. M. W.; Providencia, C.

    2007-05-15

    In the present work, we investigate the main differences in the lead neutron skin thickness, binding energy, surface energy, and density profiles obtained with two different density dependent hadron models. Our results are calculated within the Thomas-Fermi approximation with two different numerical prescriptions and compared with results obtained with a common parametrization of the nonlinear Walecka model. The neutron skin thickness is a reflex of the equation of state properties. Hence, a direct correlation is found between the neutron skin thickness and the slope of the symmetry energy. We show that within the present approximations, the asymmetry parameter for low momentum transfer polarized electron scattering is not sensitive to the model differences.

  17. Nuclear charge and neutron radii and nuclear matter: Trend analysis in Skyrme density-functional-theory approach

    NASA Astrophysics Data System (ADS)

    Reinhard, P.-G.; Nazarewicz, W.

    2016-05-01

    Background: Radii of charge and neutron distributions are fundamental nuclear properties. They depend on both nuclear interaction parameters related to the equation of state of infinite nuclear matter and on quantal shell effects, which are strongly impacted by the presence of nuclear surface. Purpose: In this work, by studying the correlation of charge and neutron radii, and neutron skin, with nuclear matter parameters, we assess different mechanisms that drive nuclear sizes. Method: We apply nuclear density functional theory using a family of Skyrme functionals obtained by means of optimization protocols, which do not include any radius information. By performing the Monte Carlo sampling of reasonable functionals around the optimal parametrization, we scan all correlations between nuclear matter properties and observables characterizing charge and neutron distributions of spherical closed-shell nuclei 48Ca,208Pb, and 298Fl. Results: By considering the influence of various nuclear matter properties on charge and neutron radii in a multidimensional parameter space of Skyrme functionals, we demonstrate the existence of two strong relationships: (i) between the nuclear charge radii and the saturation density of symmetric nuclear matter ρ0, and (ii) between the neutron skins and the slope of the symmetry energy L . The impact of other nuclear matter properties on nuclear radii is weak or nonexistent. For functionals optimized to experimental binding energies only, proton and neutron radii are found to be weakly correlated due to canceling trends from different nuclear matter characteristics. Conclusion: The existence of only two strong relations connecting nuclear radii with nuclear matter properties has important consequences. First, by requiring that the nuclear functional reproduces the empirical saturation point of symmetric nuclear matter practically fixes the charge (or proton) radii, and vice versa. This explains the recent results of ab initio calculations

  18. 2013 Review of Neutron and Non-Neutron Nuclear Data

    SciTech Connect

    Holden, N. E.

    2014-05-23

    The results of a review and evaluation of neutron and non-neutron nuclear data published in the scientific literature over the past three years since the ISRD-14 Symposium has been performed and the highlights are presented. Included in the data review are the status of new chemical elements, new measurements of the isotopic composition for many chemical elements and the resulting change in the atomic weight values. New half-life measurements for both short-lived and longlived nuclides, some alpha decay and double beta decay measurements for quasistable nuclides are discussed. The latest evaluation of atomic masses has been published. Data from new measurements on the very heavy (trans-meitnerium) elements are discussed and tabulated. Data on various recent neutron cross section and resonance integral measurements are discussed and tabulated.

  19. 2013 Review of Neutron and Non-Neutron Nuclear Data

    NASA Astrophysics Data System (ADS)

    Holden, N. E.

    2016-02-01

    The results of a review and evaluation of neutron and non-neutron nuclear data published in the scientific literature over the past three years since the ISRD-14 Symposium has been performed and the highlights are presented. Included in the data review are the status of new chemical elements, new measurements of the isotopic composition for many chemical elements and the resulting change in the atomic weight values. New half-life measurements for both short-lived and long-lived nuclides, some alpha decay and double beta decay measurements for quasi-stable nuclides are discussed. The latest evaluation of atomic masses has been published. Data from new measurements on the very heavy (trans-meitnerium) elements are discussed and tabulated. Data on various recent neutron cross section and resonance integral measurements are discussed and tabulated.

  20. Neutron spectrometer for fast nuclear reactors

    NASA Astrophysics Data System (ADS)

    Osipenko, M.; Ripani, M.; Ricco, G.; Caiffi, B.; Pompili, F.; Pillon, M.; Angelone, M.; Verona-Rinati, G.; Cardarelli, R.; Mila, G.; Argiro, S.

    2015-11-01

    In this paper we describe the development and first tests of a neutron spectrometer designed for high flux environments, such as the ones found in fast nuclear reactors. The spectrometer is based on the conversion of neutrons impinging on 6Li into α and t whose total energy comprises the initial neutron energy and the reaction Q-value. The 6LiF layer is sandwiched between two CVD diamond detectors, which measure the two reaction products in coincidence. The spectrometer was calibrated at two neutron energies in well known thermal and 3 MeV neutron fluxes. The measured neutron detection efficiency varies from 4.2 ×10-4 to 3.5 ×10-8 for thermal and 3 MeV neutrons, respectively. These values are in agreement with Geant4 simulations and close to simple estimates based on the knowledge of the 6Li(n,α)t cross-section. The energy resolution of the spectrometer was found to be better than 100 keV when using 2.5 or 5 m cables between the detector and the preamplifiers.

  1. Neutron contribution to nuclear DVCS asymmetries

    SciTech Connect

    Vadim Guzey

    2008-01-22

    Using a simple model for nuclear GPDs, we study the role of the neutron contribution to nuclear DVCS observables. As an example, we use the beam-spin asymmetry $A_{LU}^A$ measured in coherent and incoherent DVCS on a wide range of nuclear targets in the HERMES and JLab kinematics. We find that at small values of the momentum transfer $t$, $A_{LU}^A$ is dominated by the coherent-enriched contribution, which enhances $A_{LU}^A$ compared to the free proton asymmetry $A_{LU}^p$, $A_{LU}^A(\\phi)/A_{LU}^p(\\phi)=1.8-2.2$. At large values of $t$, the nuclear asymmetry is dominated by the incoherent contribution and $A_{LU}^A/(\\phi)A_{LU}^p(\\phi)=0.66-0.74$. The deviation of $A_{LU}^A(\\phi)/A_{LU}^p(\\phi)$ from unity at large $t$ is a result of the neutron contribution, which gives a possibility to constain neutron GPDs in incoherent nuclear DVCS. A similar trend is expected for other DVCS asymmetries.

  2. Neutron capture measurements for nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Reifarth, Rene

    2005-04-01

    Almost all of the heavy elements are produced via neutron capture reactions in a multitude of stellar production sites. The predictive power of the underlying stellar models is currently limited because they contain poorly constrained physics components such as convection, rotation or magnetic fields. Neutron captures measurements on heavy radioactive isotopes provide a unique opportunity to largely improve these physics components, and thereby address important questions of nuclear astrophysics. Such species are branch-points in the otherwise uniquely defined path of subsequent n-captures along the s-process path in the valley of stability. These branch points reveal themselves through unmistakable signatures recovered from pre-solar meteoritic grains that originate in individual element producing stars. Measurements on radioactive isotopes for neutron energies in the keV region represent a stringent challenge for further improvements of experimental techniques. This holds true for the neutron sources, the detection systems and the technology to handle radioactive material. Though the activation method or accelerator mass spectroscopy of the reaction products could be applied in a limited number of cases, Experimental facilities like DANCE at LANL, USA and n-TOF at CERN, Switzerland are addressing the need for such measurements on the basis of the more universal method of detecting the prompt capture gamma-rays, which is required for the application of neutron time-of-flight (TOF) techniques. With a strongly optimized neutron facility at the Rare Isotope Accelerator (RIA) isotopes with half-lives down to tens of days could be investigated, while present facilities require half-lives of a few hundred days. Recent neutron capture experiments on radioactive isotopes with relevance for nuclear astrophysics and possibilities for future experimental setups will be discussed during the talk.

  3. 2002 REVIEW OF NEUTRON AND NON NEUTRON NUCLEAR DATA.

    SciTech Connect

    HOLDEN,N.E.

    2002-08-18

    Review articles are in preparation for the 2003 edition of the CRC's Handbook of Chemistry and Physics dealing with both non-neutron and neutron nuclear data. Highlights include: withdrawal of the claim for discovery of element 118; new measurements of isotopic abundances have led to changes for many elements; a new set of recommended standards for calibration of {gamma}-ray energies have been published for many nuclides; new half-life measurements reported for very short lived isotopes, many long-lived nuclides and {beta}{beta} decay measurements for quasi-stable nuclides; a new reassessment of spontaneous fission (sf) half-lives for ground state nuclides, distinguishing half-lives from sf decay and cluster decay half-lives and the new cluster-fission decay; charged particle cross sections, (n,p) and (n,{alpha}) measurements for thermal neutrons incident on light nuclides; new thermal (n,{gamma}) cross sections and neutron resonance integrals measured. Details are presented.

  4. 2010 Review of neutron and non-neutron nuclear data

    SciTech Connect

    Holden, N.E.

    2011-07-01

    The results of a review and evaluation of neutron and non-neutron nuclear data published in the scientific literature over the past three years are presented. The status of new chemical elements is examined. Ten elements have had their atomic weight and uncertainty replaced by interval values of upper and lower bounds. Data on revised values for the isotopic composition of the elements are reviewed and new recommended values are presented for germanium. Radioactive half-lives are reviewed and latest values presented which include measurements on nuclides of interest and very long-lived nuclides such as double beta decay, double electron capture, long-lived alpha decay, and long-lived beta decay. The latest information and the status on the evaluation of atomic masses are discussed. Data from new measurements on the very heavy elements (trans-meitnerium elements) are discussed and tabulated. Data on various recent neutron cross-section and resonance integral measurements are also discussed and the latest measurements are tabulated in both cases. The JENDL-4.0 and ENDF/B-VII.1 nuclear data libraries are discussed. A new initiative on the existence and importance of isotopes is presented. (authors)

  5. 'Tertiary' nuclear burning - Neutron star deflagration?

    NASA Technical Reports Server (NTRS)

    Michel, F. Curtis

    1988-01-01

    A motivation is presented for the idea that dense nuclear matter can burn to a new class of stable particles. One of several possibilities is an 'octet' particle which is the 16 baryon extension of alpha particle, but now composed of a pair of each of the two nucleons, (3Sigma, Delta, and 2Xi). Such 'tertiary' nuclear burning (here 'primary' is H-He and 'secondary' is He-Fe) may lead to neutron star explosions rather than collapse to a black hole, analogous to some Type I supernovae models wherein accreting white dwarfs are pushed over the Chandrasekhar mass limit but explode rather than collapse to form neutron stars. Such explosions could possibly give gamma-ray bursts and power quasars, with efficient particle acceleration in the resultant relativistic shocks. The new stable particles themselves could possibly be the sought-after weakly interacting, massive particles (WIMPs) or 'dark' matter.

  6. Neutron sources in nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Kunz, Rino E.; Denker, A.; Drotleff, H. W.; Grosse, M.; Knee, H.; Kuechler, S.; Seidel, R.; Soine, M.; Hammer, J. W.

    1995-03-01

    The excitations functions of the reactions 9Be((alpha) ,n)12C, 13C((alpha) ,n)16O, 17O((alpha) ,n)20Ne, 18O((alpha) ,n)21Ne, 21Ne((alpha) ,n)24Mg, 22Ne((alpha) ,n)25Mg, 25Mg((alpha) ,n)28Si and 26Mg((alpha) ,n)29Si have been measured at the 4 MV dynamitron accelerator in Stuttgart, Germany in the energy range of astrophysical interest, and from these S-factor- curves have been determined. Advanced techniques, especially with the windowless gastarget facility Rhinoceros have been applied. For neutron detection NE213 scintillation counters and a long counter like 4(pi) -detector have been used. A sensitivity limit in the range of 10-10b to 10-\\11b was reached with these experiments. Using our new experimental results astrophysical reaction rates have been calculated for all reactions except the Mg-reactions. Analytic expressions have been fitted to all reaction rates.

  7. Density dependence of the symmetry energy from neutron skin thickness in finite nuclei

    SciTech Connect

    Vinas, X.; Centelles, M.; Roca-Maza, X.; Warda, M.

    2012-10-20

    The density dependence of the symmetry energy, characterized by the parameter L, is studied using information provided by the neutron skin thickness in finite nuclei. An estimate of L is obtained from experimental data of antiprotonic atoms. We also discuss the ability of parity violating electron scatering to obtain information about the neutron skin thickness in {sup 208}Pb.

  8. Elementary diagrams in nuclear and neutron matter

    SciTech Connect

    Wiringa, R.B.

    1995-08-01

    Variational calculations of nuclear and neutron matter are currently performed using a diagrammatic cluster expansion with the aid of nonlinear integral equations for evaluating expectation values. These are the Fermi hypernetted chain (FHNC) and single-operator chain (SOC) equations, which are a way of doing partial diagram summations to infinite order. A more complete summation can be made by adding elementary diagrams to the procedure. The simplest elementary diagrams appear at the four-body cluster level; there is one such E{sub 4} diagram in Bose systems, but 35 diagrams in Fermi systems, which gives a level of approximation called FHNC/4. We developed a novel technique for evaluating these diagrams, by computing and storing 6 three-point functions, S{sub xyz}(r{sub 12}, r{sub 13}, r{sub 23}), where xyz (= ccd, cce, ddd, dde, dee, or eee) denotes the exchange character at the vertices 1, 2, and 3. All 35 Fermi E{sub 4} diagrams can be constructed from these 6 functions and other two-point functions that are already calculated. The elementary diagrams are known to be important in some systems like liquid {sup 3}He. We expect them to be small in nuclear matter at normal density, but they might become significant at higher densities appropriate for neutron star calculations. This year we programmed the FHNC/4 contributions to the energy and tested them in a number of simple model cases, including liquid {sup 3}He and Bethe`s homework problem. We get reasonable, but not exact agreement with earlier published work. In nuclear and neutron matter with the Argonne v{sub 14} interaction these contributions are indeed small corrections at normal density and grow to only 5-10 MeV/nucleon at 5 times normal density.

  9. Proton-neutron interaction and nuclear structure

    SciTech Connect

    Casten, R.F.

    1986-01-01

    The pervasive role of the proton-neutron interaction in nuclear structure is discussed. Particular emphasis is given to its influence on the onset of collectivity and deformation, on intruder states, and on the evolution of subshell structure. The N/sub p/N/sub n/ scheme is outlined and some applications of it to collective model calculations and to nuclei far off stability are described. The concept of N/sub p/N/sub n/ multiplets is introduced. 32 refs., 20 figs.

  10. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    SciTech Connect

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities, the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.

  11. Neutron radiography of irradiated nuclear fuel at Idaho National Laboratory

    DOE PAGESBeta

    Craft, Aaron E.; Wachs, Daniel M.; Okuniewski, Maria A.; Chichester, David L.; Williams, Walter J.; Papaioannou, Glen C.; Smolinski, Andrew T.

    2015-09-10

    Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This study describes the NRAD and hot cell facilities,more » the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.« less

  12. Impact of nuclear data on fast neutron therapy

    SciTech Connect

    Hartmann Siantar, C.L.; Chandler, W.P.; Rathkopf, J.A.; Resler, D.A.; Cox, L.J.; Chadwick, M.B.; White, R.M.

    1994-05-12

    By combining a new, all-particle Monte Carlo radiation transport code, PEREGRINE, with the Lawrence Livermore National Laboratory (LLNL) nuclear data base, we have studied the importance of various neutron reactions on dose distributions in biological materials. Monte Carlo calculations have been performed for 5--20 MeV neutron pencil beams incident on biologically relevant materials arranged in several simple geometries. Results highlight the importance of nuclear data used for calculating dose distributions resulting from fast neutron therapy.

  13. Development of fast neutron pinhole camera using nuclear emulsion for neutron emission profile measurement in KSTAR

    NASA Astrophysics Data System (ADS)

    Izumi, Y.; Tomita, H.; Nakayama, Y.; Hayashi, S.; Morishima, K.; Isobe, M.; Cheon, M. S.; Ogawa, K.; Nishitani, T.; Naka, T.; Nakano, T.; Nakamura, M.; Iguchi, T.

    2016-11-01

    We have developed a compact fast neutron camera based on a stack of nuclear emulsion plates and a pinhole collimator. The camera was installed at J-port of Korea superconducting tokamak advanced research at National Fusion Research Institute, Republic of Korea. Fast neutron images agreed better with calculated ones based on Monte Carlo neutron simulation using the uniform distribution of Deuterium-Deuterium (DD) neutron source in a torus of 40 cm radius.

  14. Characterization of nuclear material by Neutron Resonance Transmission Analysis

    NASA Astrophysics Data System (ADS)

    Paradela, C.; Alaerts, G.; Becker, B.; Heyse, J.; Kopecky, S.; Moens, A.; Mondelaers, W.; Schillebeeckx, P.; Wynants, R.; Harada, H.; Kitatani, F.; Koizumi, M.; Tsuchiya, H.

    2016-11-01

    The use of Neutron Resonance Transmission Analysis for the characterization of nuclear materials is discussed. The method, which relies on resonance structures in neutron-induced reaction cross sections, can be applied as a non-destructive method to characterise complex nuclear materials such as melted fuel resulting from a severe nuclear accident. Results of a demonstration experiment at the GELINA facility reveal that accurate data can be obtained at a compact facility even in the case of strong overlapping resonances.

  15. Neutron Transport Characteristics of a Nuclear Reactor Based Dynamic Neutron Imaging System

    SciTech Connect

    Khaial, Anas M.; Harvel, Glenn D.; Chang, Jen-Shih

    2006-07-01

    An advanced dynamic neutron imaging system has been constructed in the McMaster Nuclear Reactor (MNR) for nondestructive testing and multi-phase flow studies in energy and environmental applications. A high quality neutron beam is required with a thermal neutron flux greater than 5.0 x 10{sup 6} n/cm{sup 2}-s and a collimation ratio of 120 at image plane to promote high-speed neutron imaging up to 2000 frames per second. Neutron source strength and neutron transport have been experimentally and numerically investigated. Neutron source strength at the beam tube entrance was evaluated experimentally by measuring the thermal and fast neutron fluxes, and simple analytical neutron transport calculations were performed based upon these measured neutron fluxes to predict facility components in accordance with high-speed dynamic neutron imaging and operation safety requirements. Monte-Carlo simulations (using MCNP-4B code) with multiple neutron energy groups have also been used to validate neutron beam parameters and to ensure shielding capabilities of facility shutter and cave walls. Neutron flux distributions at the image plane and the neutron beam characteristics were experimentally measured by irradiating a two-dimensional array of Copper foils and using a real-time neutron radiography system. The neutron image characteristics -- such as neutron flux, image size, beam quality -- measured experimentally and predicted numerically for beam tube, beam shutter and radiography cave are compared and discussed in detail in this paper. The experimental results show that thermal neutron flux at image plane is nearly uniform over an imaging area of 20.0-cm diameter and its magnitude ranges from 8.0 x 10{sup 6} - 1.0 x 10{sup 7} n/cm{sup 2}-sec while the neutron-to-gamma ratio is 6.0 x 10{sup 5} n/cm{sup 2}-{mu}Sv. (authors)

  16. Development of Nuclear Emulsion for Fast Neutron Measurement

    NASA Astrophysics Data System (ADS)

    Machii, Shogo; Kuwabara, Kenichi; Morishima, Kunihiro

    Nuclear emulsion is high sensitive photographic film used for detection of three-dimensional trajectory of charged particles. Energy resolution of nuclear emulsion is 21% (12%) FWHM against neutron energy of 2.8 MeV (4.9 MeV). Nuclear emulsion has high gamma ray rejection power. For now, at least 2×104 gamma rays/cm2, no increase of as a background for neutron measurement when scan using automatic nuclear emulsion read out system HTS. This value suggests that it is applicable even under high gamma ray environment, such as nuclear fusion reactor.

  17. Introducing Nuclear Data Evaluations of Prompt Fission Neutron Spectra

    SciTech Connect

    Neudecker, Denise

    2015-06-17

    Nuclear data evaluations provide recommended data sets for nuclear data applications such as reactor physics, stockpile stewardship or nuclear medicine. The evaluated data are often based on information from multiple experimental data sets and nuclear theory using statistical methods. Therefore, they are collaborative efforts of evaluators, theoreticians, experimentalists, benchmark experts, statisticians and application area scientists. In this talk, an introductions is given to the field of nuclear data evaluation at the specific example of a recent evaluation of the outgoing neutron energy spectrum emitted promptly after fission from 239Pu and induced by neutrons from thermal to 30 MeV.

  18. Composite neutron absorbing coatings for nuclear criticality control

    DOEpatents

    Wright, Richard N.; Swank, W. David; Mizia, Ronald E.

    2005-07-19

    Thermal neutron absorbing composite coating materials and methods of applying such coating materials to spent nuclear fuel storage systems are provided. A composite neutron absorbing coating applied to a substrate surface includes a neutron absorbing layer overlying at least a portion of the substrate surface, and a corrosion resistant top coat layer overlying at least a portion of the neutron absorbing layer. An optional bond coat layer can be formed on the substrate surface prior to forming the neutron absorbing layer. The neutron absorbing layer can include a neutron absorbing material, such as gadolinium oxide or gadolinium phosphate, dispersed in a metal alloy matrix. The coating layers may be formed by a plasma spray process or a high velocity oxygen fuel process.

  19. The proton-neutron symplectic model of nuclear collective motions

    NASA Astrophysics Data System (ADS)

    Ganev, H. G.

    2016-06-01

    The proton-neutron symplectic model of nuclear collective motion is presented. It is shown that it appears as a natural multi-major-shell extension of the generalized proton- neutron SU(3) scheme which includes rotations with intrinsic vortex as well as monopole, quadrupole and dipole giant resonance vibrational degrees of freedom.

  20. Packed rod neutron shield for fast nuclear reactors

    DOEpatents

    Eck, John E.; Kasberg, Alvin H.

    1978-01-01

    A fast neutron nuclear reactor including a core and a plurality of vertically oriented neutron shield assemblies surrounding the core. Each assembly includes closely packed cylindrical rods within a polygonal metallic duct. The shield assemblies are less susceptible to thermal stresses and are less massive than solid shield assemblies, and are cooled by liquid coolant flow through interstices among the rods and duct.

  1. Variance Reduction Factor of Nuclear Data for Integral Neutronics Parameters

    SciTech Connect

    Chiba, G. Tsuji, M.; Narabayashi, T.

    2015-01-15

    We propose a new quantity, a variance reduction factor, to identify nuclear data for which further improvements are required to reduce uncertainties of target integral neutronics parameters. Important energy ranges can be also identified with this variance reduction factor. Variance reduction factors are calculated for several integral neutronics parameters. The usefulness of the variance reduction factors is demonstrated.

  2. Evaluated Neutron Nuclear Data for Reactor Physics Calculations.

    1988-09-15

    Version 00 The data file KEDAK contains the evaluated neutron nuclear data for a number of materials important for the reactor physics, specific physical experiments, burn up calculations, shielding and other applications.

  3. Neutron Transfer Reactions: Surrogates for Neutron Capture for Basic and Applied Nuclear Science

    NASA Astrophysics Data System (ADS)

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, S. D.; Peters, W. A.; Adekola, A.; Allen, J.; Bardayan, D. W.; Becker, J. A.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Erikson, L.; Gaddis, A.; Harlin, C.; Hatarik, R.; Howard, J.; Jandel, M.; Johnson, M. S.; Kapler, R.; Krolas, W.; Liang, F.; Livesay, R. J.; Ma, Z.; Matei, C.; Matthews, C.; Moazen, B.; Nesaraja, C. D.; O'Malley, P.; Patterson, N.; Paulauskas, S. V.; Pelham, T.; Pittman, S. T.; Radford, D.; Rogers, J.; Schmitt, K.; Shapira, D.; Shriner, J. F.; Sissom, D. J.; Smith, M. S.; Swan, T.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, G. L.

    2009-03-01

    Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on 130,132Sn, 134Te and 75As are discussed.

  4. Neutron transfer reactions: Surrogates for neutron capture for basic and applied nuclear science

    SciTech Connect

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, Steven D; Peters, W. A.; Adekola, Aderemi S; Allen, J.; Bardayan, Daniel W; Becker, J.; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Erikson, Luke; Gaddis, A. L.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; Jandel, M.; Johnson, Micah; Kapler, R.; Krolas, W.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Matei, Catalin; Matthews, C.; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Patterson, N. P.; Paulauskas, Stanley; Pelham, T.; Pittman, S. T.; Radford, David C; Rogers, J.; Schmitt, Kyle; Shapira, Dan; ShrinerJr., J. F.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, Gemma L

    2009-04-01

    Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on {sup 130,132}Sn, {sup 134}Te and {sup 75}As are discussed.

  5. Accuracy Improvement of Neutron Nuclear Data on Minor Actinides

    NASA Astrophysics Data System (ADS)

    Harada, Hideo; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kimura, Atsushi; Terada, Kazushi; Nakao, Taro; Nakamura, Shoji; Mizuyama, Kazuhito; Igashira, Masayuki; Katabuchi, Tatsuya; Sano, Tadafumi; Takahashi, Yoshiyuki; Takamiya, Koichi; Pyeon, Cheol Ho; Fukutani, Satoshi; Fujii, Toshiyuki; Hori, Jun-ichi; Yagi, Takahiro; Yashima, Hiroshi

    2015-05-01

    Improvement of accuracy of neutron nuclear data for minor actinides (MAs) and long-lived fission products (LLFPs) is required for developing innovative nuclear system transmuting these nuclei. In order to meet the requirement, the project entitled as "Research and development for Accuracy Improvement of neutron nuclear data on Minor ACtinides (AIMAC)" has been started as one of the "Innovative Nuclear Research and Development Program" in Japan at October 2013. The AIMAC project team is composed of researchers in four different fields: differential nuclear data measurement, integral nuclear data measurement, nuclear chemistry, and nuclear data evaluation. By integrating all of the forefront knowledge and techniques in these fields, the team aims at improving the accuracy of the data. The background and research plan of the AIMAC project are presented.

  6. Microscopic calculations of nuclear and neutron matter, symmetry energy and neutron stars

    DOE PAGESBeta

    Gandolfi, S.

    2015-02-01

    We present Quantum Monte Carlo calculations of the equation of state of neutron matter. The equation of state is directly related to the symmetry energy and determines the mass and radius of neutron stars, providing then a connection between terrestrial experiments and astronomical observations. As a result, we also show preliminary results of the equation of state of nuclear matter.

  7. Los Alamos Using Neutrons to Stop Nuclear Smugglers

    ScienceCinema

    Favalli, Andrea; Swinhoe, Martyn

    2016-07-12

    Los Alamos National Laboratory researchers have successfully demonstrated for the first time that laser-generated neutrons can be enlisted as a useful tool in the War on Terror. The international research team used the short-pulse laser at Los Alamos's TRIDENT facility to generate a neutron beam with novel characteristics that interrogated a closed container to confirm the presence and quantity of nuclear material inside. The successful experiment paves the way for creation of a table-top-sized or truck-mounted neutron generator that could be installed at strategic locations worldwide to thwart smugglers trafficking in nuclear materials.

  8. Los Alamos Using Neutrons to Stop Nuclear Smugglers

    SciTech Connect

    Favalli, Andrea; Swinhoe, Martyn

    2013-06-03

    Los Alamos National Laboratory researchers have successfully demonstrated for the first time that laser-generated neutrons can be enlisted as a useful tool in the War on Terror. The international research team used the short-pulse laser at Los Alamos's TRIDENT facility to generate a neutron beam with novel characteristics that interrogated a closed container to confirm the presence and quantity of nuclear material inside. The successful experiment paves the way for creation of a table-top-sized or truck-mounted neutron generator that could be installed at strategic locations worldwide to thwart smugglers trafficking in nuclear materials.

  9. Los Alamos Neutron Science Center (LANSCE) Nuclear Science Facilities

    SciTech Connect

    Nelson, Ronald Owen; Wender, Steve

    2015-06-19

    The Los Alamos Neutron Science Center (LANSCE) facilities for Nuclear Science consist of a high-energy "white" neutron source (Target 4) with 6 flight paths, three low-energy nuclear science flight paths at the Lujan Center, and a proton reaction area. The neutron beams produced at the Target 4 complement those produced at the Lujan Center because they are of much higher energy and have shorter pulse widths. The neutron sources are driven by the 800-MeV proton beam of the LANSCE linear accelerator. With these facilities, LANSCE is able to deliver neutrons with energies ranging from a milli-electron volt to several hundreds of MeV, as well as proton beams with a wide range of energy, time and intensity characteristics. The facilities, instruments and research programs are described briefly.

  10. Spent nuclear fuel assembly inspection using neutron computed tomography

    NASA Astrophysics Data System (ADS)

    Pope, Chad Lee

    The research presented here focuses on spent nuclear fuel assembly inspection using neutron computed tomography. Experimental measurements involving neutron beam transmission through a spent nuclear fuel assembly serve as benchmark measurements for an MCNP simulation model. Comparison of measured results to simulation results shows good agreement. Generation of tomography images from MCNP tally results was accomplished using adapted versions of built in MATLAB algorithms. Multiple fuel assembly models were examined to provide a broad set of conclusions. Tomography images revealing assembly geometric information including the fuel element lattice structure and missing elements can be obtained using high energy neutrons. A projection difference technique was developed which reveals the substitution of unirradiated fuel elements for irradiated fuel elements, using high energy neutrons. More subtle material differences such as altering the burnup of individual elements can be identified with lower energy neutrons provided the scattered neutron contribution to the image is limited. The research results show that neutron computed tomography can be used to inspect spent nuclear fuel assemblies for the purpose of identifying anomalies such as missing elements or substituted elements. The ability to identify anomalies in spent fuel assemblies can be used to deter diversion of material by increasing the risk of early detection as well as improve reprocessing facility operations by confirming the spent fuel configuration is as expected or allowing segregation if anomalies are detected.

  11. Integrated neutron/gamma-ray portal monitors for nuclear safeguards

    SciTech Connect

    Fehlau, P.E.

    1993-09-01

    Radiation monitoring is one nuclear-safeguards measure used to protect against the theft of special nuclear materials (SNM) by pedestrians departing from SNM access areas. The integrated neutron/gamma-ray portal monitor is an ideal radiation monitor for the task when the SNM is plutonium. It achieves high sensitivity for detecting both bare and shielded plutonium by combining two types of radiation detector. One type is a neutron-chamber detector, comprising a large, hollow, neutron moderator that contains a single thermal-neutron proportional counter. The entrance wall of each chamber is thin to admit slow neutrons from plutonium contained in a moderating shield, while the other walls are thick to moderate fast neutrons from bare or lead-shielded plutonium so that they can be detected. The other type of detector is a plastic scintillator that is primarily for detecting gamma rays from small amounts of unshielded plutonium. The two types of detector are easily integrated by making scintillators part of the thick back wall of each neutron chamber or by inserting them into each chamber void. We compared the influence of the two methods of integration on detecting neutrons and gamma rays, and we examined the effectiveness of other design factors and the methods for signal detection as well.

  12. Ultra Wide Band RFID Neutron Tags for Nuclear Materials Monitoring

    SciTech Connect

    Nekoogar, F; Dowla, F; Wang, T

    2010-01-27

    Recent advancements in the ultra-wide band Radio Frequency Identification (RFID) technology and solid state pillar type neutron detectors have enabled us to move forward in combining both technologies for advanced neutron monitoring. The LLNL RFID tag is totally passive and will operate indefinitely without the need for batteries. The tag is compact, can be directly mounted on metal, and has high performance in dense and cluttered environments. The LLNL coin-sized pillar solid state neutron detector has achieved a thermal neutron detection efficiency of 20% and neutron/gamma discrimination of 1E5. These performance values are comparable to a fieldable {sup 3}He based detector. In this paper we will discuss features about the two technologies and some potential applications for the advanced safeguarding of nuclear materials.

  13. Neutron Capture Gamma-Ray Libraries for Nuclear Applications

    NASA Astrophysics Data System (ADS)

    Sleaford, B. W.; Firestone, R. B.; Summers, N.; Escher, J.; Hurst, A.; Krticka, M.; Basunia, S.; Molnar, G.; Belgya, T.; Revay, Z.; Choi, H. D.

    2011-06-01

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. This can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research Project. EGAF is being used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90% of all the decay energy and is modeled here with the statistical nuclear structure code DICEBOX. This code also provides a consistency check of the level scheme nuclear structure evaluation. The calculated continuum is of sufficient accuracy to include in the ENDF libraries. This analysis also determines new total thermal capture cross sections and provides an improved RIPL database. For higher energy neutron capture there is less experimental data available making benchmarking of the modeling codes more difficult. We are investigating the capture spectra from higher energy neutrons experimentally using surrogate reactions and modeling this with Hauser-Feshbach codes. This can then be used to benchmark CASINO, a version of DICEBOX modified for neutron capture at higher energy. This can be used to simulate spectra from neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modeling of unknown assemblies.

  14. Neutron Capture Gamma-Ray Libraries for Nuclear Applications

    SciTech Connect

    Sleaford, B W; Firestone, R B; Summers, N; Escher, J; Hurst, A; Krticka, M; Basunia, S; Molnar, G; Belgya, T; Revay, Z; Choi, H D

    2010-11-04

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. this can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research project. EGAF is being used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90% of all the decay energy and is modeled here with the statistical nuclear structure code DICEBOX. This code also provides a consistency check of the level scheme nuclear structure evaluation. The calculated continuum is of sufficient accuracy to include in the ENDF libraries. This analysis also determines new total thermal capture cross sections and provides an improved RIPL database. For higher energy neutron capture there is less experimental data available making benchmarking of the modeling codes more difficult. They are investigating the capture spectra from higher energy neutrons experimentally using surrogate reactions and modeling this with Hauser-Feshbach codes. This can then be used to benchmark CASINO, a version of DICEBOX modified for neutron capture at higher energy. This can be used to simulate spectra from neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modeling of unknown assemblies.

  15. Neutron Capture Gamma-Ray Libraries for Nuclear Applications

    SciTech Connect

    Sleaford, B. W.; Summers, N.; Escher, J.; Firestone, R. B.; Basunia, S.; Hurst, A.; Krticka, M.; Molnar, G.; Belgya, T.; Revay, Z.; Choi, H. D.

    2011-06-28

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. This can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research Project. EGAF is being used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90% of all the decay energy and is modeled here with the statistical nuclear structure code DICEBOX. This code also provides a consistency check of the level scheme nuclear structure evaluation. The calculated continuum is of sufficient accuracy to include in the ENDF libraries. This analysis also determines new total thermal capture cross sections and provides an improved RIPL database. For higher energy neutron capture there is less experimental data available making benchmarking of the modeling codes more difficult. We are investigating the capture spectra from higher energy neutrons experimentally using surrogate reactions and modeling this with Hauser-Feshbach codes. This can then be used to benchmark CASINO, a version of DICEBOX modified for neutron capture at higher energy. This can be used to simulate spectra from neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modeling of unknown assemblies.

  16. Analysis constants for database of neutron nuclear data

    NASA Astrophysics Data System (ADS)

    Bedenko, S. V.; Jeremiah, J. Joseph; Knyshev, V. V.; Shamanin, I. V.

    2016-07-01

    At present there is a variety of experimental and calculation nuclear data which are rather entirely presented in the following evaluated nuclear data libraries: ENDF (USA), JEFF (Europe), JENDL (Japan), TENDL (Russian Federation), ROSFOND (Russian Federation). Libraries of nuclear data, used for neutron-physics calculations in programs: Scale (Origen-Arp), MCNP, WIMS, MCU, and others. Nevertheless all existing nuclear data bases, including evaluated ones, contain practically no information about threshold neutron reactions on 232Th nuclei; available values of outputs and cross-sections significantly differ by orders. The work shows necessity of nuclear constants corrections which are used in the calculations of grids and thorium storage systems. The results of numerical experiments lattices and storage systems with thorium.

  17. Beta delayed neutrons for nuclear structure and astrophysics

    NASA Astrophysics Data System (ADS)

    Grzywacz, Robert

    2014-09-01

    Beta-delayed neutron emission (β xn) is a significant or even dominant decay channel for the majority of very neutron-rich nuclei, especially for those on the r-process path. The recent theoretical models predicts that it may play more significant role then previously expected for astrophysics and this realization instigated a renewed experimental interest in this topic as a part of a larger scope of research on beta-decay strength distribution. Because studies of the decay strength directly probe relevant physics on the microscopic level, energy-resolved measurements of the beta-decay strength distribution is a better test of nuclear models than traditionally used experimental observables like half-lives and neutron branching ratios. A new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed to directly address this issue. In its first experimental campaign at the Holifield Radioactive Ion Beam Facility neutron energy spectra in key regions of the nuclear chart were measured: near the shell closures at 78Ni and 132Sn, and for the deformed nuclei near 100Rb. In several cases, unexpectedly intense and concentrated, resonant-like, high-energy neutron structures were observed. These results were interpreted within shell model framework which clearly indicated that these neutron emission is driven by nuclear structure effects and are due to large Gamow-Teller type transition matrix elements. This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552.

  18. Active Interrogation Using Electronic Neutron Generators for Nuclear Safeguards Applications

    SciTech Connect

    Chichester, D. L.; Seabury, E. H.

    2009-03-10

    Active interrogation, a measurement technique which uses a radiation source to probe materials and generate unique signatures useful for characterizing those materials, is a powerful tool for assaying special nuclear material. The most commonly used technique for performing active interrogation is to use an electronic neutron generator as the probe radiation source. Exploiting the unique operating characteristics of these devices, including their monoenergetic neutron emissions and their ability to operate in pulsed modes, presents a number of options for performing prompt and delayed signature analyses using both photon and neutron sensors. A review of literature in this area shows multiple applications of the active neutron interrogation technique for performing nuclear nonproliferation measurements. Some examples include measuring the plutonium content of spent fuel, assaying plutonium residue in spent fuel hull claddings, assaying plutonium in aqueous fuel reprocessing process streams, and assaying nuclear fuel reprocessing facility waste streams to detect and quantify fissile material. This paper discusses the historical use of this technique and examines its context within the scope and challenges of next-generation nuclear fuel cycles and advanced concept nuclear fuel cycle facilities.

  19. Active Interrogation Using Electronic Neutron Generators for Nuclear Safeguards Applications

    SciTech Connect

    David L. Chichester; Edward H. Seabury

    2008-08-01

    Active interrogation, a measurement technique which uses a radiation source to probe materials and generate unique signatures useful for characterizing those materials, is a powerful tool for assaying special nuclear material. The most commonly used technique for performing active interrogation is to use an electronic neutron generator as the probe radiation source. Exploiting the unique operating characteristics of these devices, including their monoenergetic neutron emissions and their ability to operate in pulsed modes, presents a number of options for performing prompt and delayed signature analyses using both photon and neutron sensors. A review of literature in this area shows multiple applications of the active neutron interrogation technique for performing nuclear nonproliferation measurements. Some examples include measuring the plutonium content of spent fuel, assaying plutonium residue in spent fuel hull claddings, assaying plutonium in aqueous fuel reprocessing process streams, and assaying nuclear fuel reprocessing facility waste streams to detect and quantify fissile material. This paper discusses the historical use of this technique and examines its context within the scope and challenges of next-generation nuclear fuel cycles and advanced concept nuclear fuel cycle facilities.

  20. The pygmy quadrupole resonance and neutron-skin modes in 124Sn

    NASA Astrophysics Data System (ADS)

    Spieker, M.; Tsoneva, N.; Derya, V.; Endres, J.; Savran, D.; Harakeh, M. N.; Harissopulos, S.; Herzberg, R.-D.; Lagoyannis, A.; Lenske, H.; Pietralla, N.; Popescu, L.; Scheck, M.; Schlüter, F.; Sonnabend, K.; Stoica, V. I.; Wörtche, H. J.; Zilges, A.

    2016-01-01

    We present an extensive experimental study of the recently predicted pygmy quadrupole resonance (PQR) in Sn isotopes, where complementary probes were used. In this study, (α ,α‧ γ) and (γ ,γ‧) experiments were performed on 124Sn. In both reactions, Jπ =2+ states below an excitation energy of 5 MeV were populated. The E2 strength integrated over the full transition densities could be extracted from the (γ ,γ‧) experiment, while the (α ,α‧ γ) experiment at the chosen kinematics strongly favors the excitation of surface modes because of the strong α-particle absorption in the nuclear interior. The excitation of such modes is in accordance with the quadrupole-type oscillation of the neutron skin predicted by a microscopic approach based on self-consistent density functional theory and the quasiparticle-phonon model (QPM). The newly determined γ-decay branching ratios hint at a non-statistical character of the E2 strength, as it has also been recently pointed out for the case of the pygmy dipole resonance (PDR). This allows us to distinguish between PQR-type and multiphonon excitations and, consequently, supports the recent first experimental indications of a PQR in 124Sn.

  1. Nuclear Material Detection by One-Short-Pulse-Laser-Driven Neutron Source

    SciTech Connect

    Favalli, Andrea; Aymond, F.; Bridgewater, Jon S.; Croft, Stephen; Deppert, O.; Devlin, Matthew James; Falk, Katerina; Fernandez, Juan Carlos; Gautier, Donald Cort; Gonzales, Manuel A.; Goodsell, Alison Victoria; Guler, Nevzat; Hamilton, Christopher Eric; Hegelich, Bjorn Manuel; Henzlova, Daniela; Ianakiev, Kiril Dimitrov; Iliev, Metodi; Johnson, Randall Philip; Jung, Daniel; Kleinschmidt, Annika; Koehler, Katrina Elizabeth; Pomerantz, Ishay; Roth, Markus; Santi, Peter Angelo; Shimada, Tsutomu; Swinhoe, Martyn Thomas; Taddeucci, Terry Nicholas; Wurden, Glen Anthony; Palaniyappan, Sasikumar; McCary, E.

    2015-01-28

    Covered in the PowerPoint presentation are the following areas: Motivation and requirements for active interrogation of nuclear material; laser-driven neutron source; neutron diagnostics; active interrogation of nuclear material; and, conclusions, remarks, and future works.

  2. In vivo skin leptin modulation after 14 MeV neutron irradiation: a molecular and FT-IR spectroscopic study.

    PubMed

    Cestelli Guidi, M; Mirri, C; Fratini, E; Licursi, V; Negri, R; Marcelli, A; Amendola, R

    2012-09-01

    This paper discusses gene expression changes in the skin of mice treated by monoenergetic 14 MeV neutron irradiation and the possibility of monitoring the resultant lipid depletion (cross-validated by functional genomic analysis) as a marker of radiation exposure by high-resolution FT-IR (Fourier transform infrared) imaging spectroscopy. The irradiation was performed at the ENEA Frascati Neutron Generator (FNG), which is specifically dedicated to biological samples. FNG is a linear electrostatic accelerator that produces up to 1.0 × 10(11) 14-MeV neutrons per second via the D-T nuclear reaction. The functional genomic approach was applied to four animals for each experimental condition (unirradiated, 0.2 Gy irradiation, or 1 Gy irradiation) 6 hours or 24 hours after exposure. Coregulation of a subclass of keratin and keratin-associated protein genes that are physically clustered in the mouse genome and functionally related to skin and hair follicle proliferation and differentiation was observed. Most of these genes are transiently upregulated at 6 h after the delivery of the lower dose delivered, and drastically downregulated at 24 h after the delivery of the dose of 1 Gy. In contrast, the gene coding for the leptin protein was consistently upregulated upon irradiation with both doses. Leptin is a key protein that regulates lipid accumulation in tissues, and its absence provokes obesity. The tissue analysis was performed by monitoring the accumulation and the distribution of skin lipids using FT-IR imaging spectroscopy. The overall picture indicates the differential modulation of key genes during epidermis homeostasis that leads to the activation of a self-renewal process at low doses of irradiation.

  3. Hairless is a nuclear receptor corepressor essential for skin function

    PubMed Central

    Thompson, Catherine C.

    2009-01-01

    The activity of nuclear receptors is modulated by numerous coregulatory factors. Corepressors can either mediate the ability of nuclear receptors to repress transcription, or can inhibit transactivation by nuclear receptors. As we learn more about the mechanisms of transcriptional repression, the importance of repression by nuclear receptors in development and disease has become clear. The protein encoded by the mammalian Hairless (Hr) gene was shown to be a corepressor by virtue of its functional similarity to the well-established corepressors N-CoR and SMRT. Mutation of the Hr gene results in congenital hair loss in both mice and men. Investigation of Hairless function both in vitro and in mouse models in vivo has revealed a critical role in maintaining skin and hair by regulating the differentiation of epithelial stem cells, as well as a putative role in regulating gene expression via chromatin remodeling. PMID:20087431

  4. Response of rat skin to boron neutron capture therapy with p-boronophenylalanine or borocaptate sodium.

    PubMed

    Morris, G M; Coderre, J A; Hopewell, J W; Micca, P L; Rezvani, M

    1994-08-01

    The effects of boron neutron capture irradiation employing either BPA or BSH as neutron capture agents has been assessed using the dorsal skin of Fischer 344 rats. Pharmacokinetic studies, using prompt gamma spectrometry, revealed comparable levels of boron-10 (10B) in blood and skin after the intravenous infusion of BSH (100 mg/kg body wt.). The 10B content of blood (12.0 +/- 0.5 micrograms/g) was slightly higher than that of skin (10.0 +/- 0.5 micrograms/g) after oral dosing with BPA. Biphasic skin reactions were observed after irradiation with the thermal neutron beam alone or in combination with BPA or BSH. The time of onset of the first phase of the skin reaction, moist desquamation, was approximately 2 weeks. The time at which the second-wave skin reaction, dermal necrosis, became evident was dose-related and occurred after a latent interval of > or = 24 weeks, well after the acute epithelial reaction had healed. The incidence of both phases of skin damage was also dose-related. The radiation doses required to produce skin damage in 50% of skin sites (ED50 values) were calculated from dose-effect curves and these values were used to determine relative biological effectiveness (RBE) and compound biological effectiveness (CBE) factors for both moist desquamation and dermal necrosis. It was concluded on the basis of these calculations that the microdistribution of the two neutron capture agents had a critical bearing on the overall biological effect after thermal neutron activation. BSH, which was possibly excluded from the cytoplasm of epidermal cells, had a low CBE factor value (0.56 +/- 0.06) while BPA, which may be selectively accumulated in epidermal cells had a very high CBE factor (3.74 +/- 0.7). For the dermal reaction, where vascular endothelial cells represent the likely target cell population, the CBE factor values were comparable, at 0.73 +/- 0.42 and 0.86 +/- 0.08 for BPA ad BSH, respectively.

  5. Impacts of Nuclear Symmetry Energy on Neutron Star Crusts

    NASA Astrophysics Data System (ADS)

    Bao, S. S.; Shen, H.

    2015-11-01

    Using the relativistic mean-field theory, we adopt two different methods, namely, the coexisting phase method and the self-consistent Thomas-Fermi approximation, to study the impacts of nuclear symmetry energy on the properties of neutron star crusts within a wide range of densities. It is found that the nuclear symmetry energy and its density slope play an important role in determining the pasta phases and the crust-core transition.

  6. Detection of special nuclear material by observation of delayed neutrons with a novel fast neutron composite detector

    NASA Astrophysics Data System (ADS)

    Mayer, Michael; Nattress, Jason; Barhoumi Meddeb, Amira; Foster, Albert; Trivelpiece, Cory; Rose, Paul; Erickson, Anna; Ounaies, Zoubeida; Jovanovic, Igor

    2015-10-01

    Detection of shielded special nuclear material is crucial to countering nuclear terrorism and proliferation, but its detection is challenging. By observing the emission of delayed neutrons, which is a unique signature of nuclear fission, the presence of nuclear material can be inferred. We report on the observation of delayed neutrons from natural uranium by using monoenergetic photons and neutrons to induce fission. An interrogating beam of 4.4 MeV and 15.1 MeV gamma-rays and neutrons was produced using the 11B(d,n-γ)12C reaction and used to probe different targets. Neutron detectors with complementary Cherenkov detectors then discriminate material undergoing fission. A Li-doped glass-polymer composite neutron detector was used, which displays excellent n/ γ discrimination even at low energies, to observe delayed neutrons from uranium fission. Delayed neutrons have relatively low energies (~0.5 MeV) compared to prompt neutrons, which makes them difficult to detect using recoil-based detectors. Neutrons were counted and timed after the beam was turned off to observe the characteristic decaying time profile of delayed neutrons. The expected decay of neutron emission rate is in agreement with the common parametrization into six delayed neutron groups.

  7. A neutron-absorbing porcelain enamel for coating nuclear equipment

    SciTech Connect

    Iverson, D.C.

    1988-01-01

    In 1985, nuclear safety analyses showed that under upset conditions, strict administrative controls were necessary to limit access to a new processing vessel for enriched uranium service at the Savannah River Plant (SRP). In order to increase the level of nuclear safety associated with that vessel, the traditional methods of incorporating neutron absorbers (borated stainless steel, boral, cadmium foil, etc.) were reviewed, however, process conditions did not permit their use. A neutron-absorbing porcelain enamel containing large amounts of cadmium and boron was developed as a safe, cost-effective alternative to traditional neutron-absorbing methods. Several pieces of coated process equipment have been installed or are planned for installation at SRP.

  8. Study of nuclear recoils in liquid argon with monoenergetic neutrons

    NASA Astrophysics Data System (ADS)

    Regenfus, C.; Allkofer, Y.; Amsler, C.; Creus, W.; Ferella, A.; Rochet, J.; Walter, M.

    2012-07-01

    In the framework of developments for liquid argon dark matter detectors we assembled a laboratory setup to scatter neutrons on a small liquid argon target. The neutrons are produced mono-energetically (Ekin = 2.45 MeV) by nuclear fusion in a deuterium plasma and are collimated onto a 3" liquid argon cell operating in single-phase mode (zero electric field). Organic liquid scintillators are used to tag scattered neutrons and to provide a time-of-flight measurement. The setup is designed to study light pulse shapes and scintillation yields from nuclear and electronic recoils as well as from alpha particles at working points relevant for dark matter searches. Liquid argon offers the possibility to scrutinise scintillation yields in noble liquids with respect to the population strength of the two fundamental excimer states. Here we present experimental methods and first results from recent data towards such studies.

  9. NNS computing facility manual P-17 Neutron and Nuclear Science

    SciTech Connect

    Hoeberling, M.; Nelson, R.O.

    1993-11-01

    This document describes basic policies and provides information and examples on using the computing resources provided by P-17, the Neutron and Nuclear Science (NNS) group. Information on user accounts, getting help, network access, electronic mail, disk drives, tape drives, printers, batch processing software, XSYS hints, PC networking hints, and Mac networking hints is given.

  10. Density dependence of the nuclear symmetry energy from measurements of neutron radii in nuclei

    SciTech Connect

    Viñas, X.; Centelles, M.; Roca-Maza, X.; Warda, M.

    2014-07-23

    We study the density dependence of the nuclear symmetry energy, characterized by its slope parameter L, by means of the information provided by the neutron radius and the neutron skin thickness in finite nuclei. These quantities are extracted from the analysis of data obtained in antiprotonic atoms, from the parity-violating asymmetry at low-momentum transfer in polarized electron scattering in {sup 208}Pb, and from the electric dipole polarizability obtained via polarized proton inelastic scattering at forward angles in {sup 208}Pb. All these experiments provide different constraints on the slope L of the symmetry energy but the corresponding values have a considerable overlap in a range around 50 MeV ≤ L ≤ 70 MeV, in a reasonable agreement with other estimates that use different observables and methods to extract L.

  11. Density dependence of the nuclear symmetry energy from measurements of neutron radii in nuclei

    NASA Astrophysics Data System (ADS)

    Viñas, X.; Centelles, M.; Roca-Maza, X.; Warda, M.

    2014-07-01

    We study the density dependence of the nuclear symmetry energy, characterized by its slope parameter L, by means of the information provided by the neutron radius and the neutron skin thickness in finite nuclei. These quantities are extracted from the analysis of data obtained in antiprotonic atoms, from the parity-violating asymmetry at low-momentum transfer in polarized electron scattering in 208Pb, and from the electric dipole polarizability obtained via polarized proton inelastic scattering at forward angles in 208Pb. All these experiments provide different constraints on the slope L of the symmetry energy but the corresponding values have a considerable overlap in a range around 50 MeV ≤ L ≤ 70 MeV, in a reasonable agreement with other estimates that use different observables and methods to extract L.

  12. Electron transport through nuclear pasta in magnetized neutron stars

    NASA Astrophysics Data System (ADS)

    Yakovlev, D. G.

    2015-10-01

    We present a simple model for electron transport in a possible layer of exotic nuclear clusters (in the so-called nuclear pasta layer) between the crust and liquid core of a strongly magnetized neutron star. The electron transport there can be strongly anisotropic and gyrotropic. The anisotropy is produced by different electron effective collision frequencies along and across local symmetry axis in domains of exotic ordered nuclear clusters and by complicated effects of the magnetic field. We also calculate averaged kinetic coefficients in case local domains are freely oriented. Possible applications of the obtained results and open problems are outlined.

  13. Molecular Dynamics of Nuclear Pasta in Neutron Stars

    NASA Astrophysics Data System (ADS)

    Briggs, Christian; da Silva Schneider, Andre

    2014-09-01

    During a core collapse supernova, a massive star undergoes rapid contraction followed by a massive explosion on the order of a hundred trillion trillion nuclear bombs in less than a second. While most matter is expelled at high speeds, what remains can form a neutron star. The bulk of a neutron star does not contain separate nuclei but is itself a single nucleus of radius ~10 km. In the crust of a neutron star, density is low enough that some matter exists as distinct nuclei arranged into crystalline lattice dominated by electromagnetic forces. Between the crust and core lies an interesting interface where matter is neither a single nucleus nor separate nuclei. It exists in a frustrated phase; competition between electromagnetic and strong nuclear forces causes exotic shapes to emerge, referred to as nuclear pasta. We use Molecular Dynamics (MD) to simulate nuclear pasta, with densities between nuclear saturation density and approximately one-tenth saturation density. Using MD particle trajectories, we compute the static structure factor S(q) and dynamical response function to describe both electron-pasta and neutrino-pasta scattering. We relate the structure and properties of nuclear pasta phases to features in S(q). Finally, one can integrate over S(q) to determine transport properties such as the electrical and thermal conductivity. This may help provide a better understanding of X-ray observations of neutron stars. During a core collapse supernova, a massive star undergoes rapid contraction followed by a massive explosion on the order of a hundred trillion trillion nuclear bombs in less than a second. While most matter is expelled at high speeds, what remains can form a neutron star. The bulk of a neutron star does not contain separate nuclei but is itself a single nucleus of radius ~10 km. In the crust of a neutron star, density is low enough that some matter exists as distinct nuclei arranged into crystalline lattice dominated by electromagnetic forces

  14. Neutron dose estimation in a zero power nuclear reactor

    NASA Astrophysics Data System (ADS)

    Triviño, S.; Vedelago, J.; Cantargi, F.; Keil, W.; Figueroa, R.; Mattea, F.; Chautemps, A.; Santibañez, M.; Valente, M.

    2016-10-01

    This work presents the characterization and contribution of neutron and gamma components to the absorbed dose in a zero power nuclear reactor. A dosimetric method based on Fricke gel was implemented to evaluate the separation between dose components in the mixed field. The validation of this proposed method was performed by means of direct measurements of neutron flux in different positions using Au and Mg-Ni activation foils. Monte Carlo simulations were conversely performed using the MCNP main code with a dedicated subroutine to incorporate the exact complete geometry of the nuclear reactor facility. Once nuclear fuel elements were defined, the simulations computed the different contributions to the absorbed dose in specific positions inside the core. Thermal/epithermal contributions of absorbed dose were assessed by means of Fricke gel dosimetry using different isotopic compositions aimed at modifying the sensitivity of the dosimeter for specific dose components. Clear distinctions between gamma and neutron capture dose were obtained. Both Monte Carlo simulations and experimental results provided reliable estimations about neutron flux rate as well as dose rate during the reactor operation. Simulations and experimental results are in good agreement in every positions measured and simulated in the core.

  15. Nuclear science research at the WNR and LANSCE neutron sources

    SciTech Connect

    Lisowski, P.W.

    1994-06-01

    The Weapons Neutron Research (WNR) Facility and the Los Alamos Neutron Scattering Center (LANSCE) use 800 MeV proton beam from the Los Alamos Meson Physics Facility (LAMPF) to generate intense bursts of neutrons. Experiments using time-of-flight (TOF) energy determination can cover an energy range from thermal to about 2 MeV at LANSCE and 0.1 to 800 MeV at WNR. At present, three flight paths at LANSCE and six flight paths at WNR are used in basic and applied nuclear science research. In this paper we present a status report on WNR and LANSCE, discuss plans for the future, and describe three experiments recently completed or underway that use the unique features of these sources.

  16. [Dosimetry of fast neutrons in 1W nuclear reactor with plastic nuclear-track detectors].

    PubMed

    Yasubuchi, S; Hoshi, M; Itoh, T; Hisanaga, S; Niwa, T; Miki, R; Kondo, S

    1989-09-01

    A nuclear reactor at Kinki University is operated at the maximum of 1W. It produces fission neutrons as much as gamma-rays. To facilitate its use for neutron radiobiology, fast neutrons inside the reactor were measured with nuclear-track detectors TS 16 N and a pair of ion chambers. The angular dependence of TS 16 N response, an anisotropy of fast neutron fluxes in the reactor and misuse of the kerma factor assumed for radiation protection business are the major causes of discrepancy is measured doses by the two methods. Correction factors for the three causes are proposed. After correction, neutron doses estimated with TS 16 N and chambers agree within 5%. The dose-rate at the reactor's center is about 20 tissue-cGy/h. This is the first in situ dosimetry of fast neutrons in a reactor with track detectors attached to biologic samples. Our routine usage has demonstrated that, if used with caution, TS 16 N elements are handy, reliable monitors for fast neutron dosimetry as they are insensitive to contaminated gamma-rays and small enough to be attached to biologic samples.

  17. A Wide Range Neutron Detector for Space Nuclear Reactor Applications

    SciTech Connect

    Nassif, Eduardo; Sismonda, Miguel; Matatagui, Emilio; Pretorius, Stephan

    2007-01-30

    We propose here a versatile and innovative solution for monitoring and controlling a space-based nuclear reactor that is based on technology already proved in ground based reactors. A Wide Range Neutron Detector (WRND) allows for a reduction in the complexity of space based nuclear instrumentation and control systems. A ground model, predecessor of the proposed system, has been installed and is operating at the OPAL (Open Pool Advanced Light Water Research Reactor) in Australia, providing long term functional data. A space compatible Engineering Qualification Model of the WRND has been developed, manufactured and verified satisfactorily by analysis, and is currently under environmental testing.

  18. Di-Neutron Clustering and Deuteron-like Tensor Correlation in Nuclear Structure Focusing on 11Li

    NASA Astrophysics Data System (ADS)

    Ikeda, Kiyomi; Myo, Takayuki; Kato, Kiyoshi; Toki, Hiroshi

    11Li is a Borromean nucleus, where two out of three objects as 9Li + n and two neutrons independently do not form bound systems. Two neutrons should form a di-neutron cluster in the nuclear field generated by the 9Li core nucleus. We treat di-neutron clustering by solving the two neutron relative wave function precisely by using the bare nucleon-nucleon interaction so that the spatial clustering structure is obtained quantitatively within the whole 11Li nucleus. This di-neutron clustering is an essential dynamics to form the halo structure by making a compact di-neutron cluster, which distributes loosely around the 9Li core. This concept of di-neutron clustering should be clearly distinguished from the BCS pairing correlation, where no consideration of spatial clustering is made. The di-neutron clustering is a new concept and is a general phenomenon in neutron skin and neutron halo nuclei. This quantitative description of di-neutron clustering has made it necessary to consider another important deuteron-like tensor correlation, which is caused by strong tensor interaction in the nucleon-nucleon interaction. The tensor interaction originates from pion exchange and known to provide large attraction to form the 4He nucleus. The unique feature of the tensor correlation is to make highly correlated deuteron-like excitation, which interferes with shell model like structure in a unique way. This dynamical effect removes the magic number effect and makes easy the participation of the s-wave neutrons. Hence, there are pairing and deuteron-like tensor correlations in addition to the mean field structure in 9Li. The combined system of two additional neutrons with the correlated 9Li provides the halo phenomenon, in which the di-neutron clustering develops with the help of large s-wave component caused by the deuteron-like tensor correlation. These two effects, the di-neutron clustering and the deuteron-like tensor correlation, are quite new and essential to provide the halo

  19. Correlation of Neutron Data Taken at Commercial Nuclear Sites

    SciTech Connect

    Rathbun, L. A.; Endres, G. W.R.

    1983-10-01

    In this report, data from neutron measurement and dosimetry studies performed by Pacific Northwest Laboratory, the Environmental Measurements Laboratory, and Rensselaer Polytechnic Institute are examined and compared. The purpose of this data correlation effort is to determine whether useful relationships exist between the actual neutron dose equivalent in a typical commercial nuclear power reactor and various measurement parameters, such as ratios of the response of 9-in. to 3-in. spheres, neutron/gamma ratios, albedo dosimeter response and neutron spectrometer readings. In most neutron radiation fields found in the reactors visited, the response of albedo dosimeters can be brought into reasonable agreement with dose equivalents measured with multispheres, tissue equivalent proportional counters (TEPCs) or remmeters. Because the responses of the remmeters, like the responses of albedo dosimeters, are energy dependent, it is preferable to correct the responses of the albedo dosimeters to agree with dose equivalents measured with either TEPCs or multispheres. If one of these laboratory systems has been used to measure neutron dose equivalents at a specific pressurized water reactor, a calculated average albedo dosimeter correction factor can be used for most locations at that reactor. However, if the measured 9-in. to 3-in. remmeter ratio is greater than 0.20, it is advisable to use a plot of 9-in. to 3-in. remmeter ratios versus albedo dosimeter correction factors to obtain an albedo dosimeter correction factor. Because 9-in. to 3-in. remmeter ratios at boiling water reactors are typically greater than 0.20, the latter approach applies to this type of reactor.

  20. Neutron transport analysis for nuclear reactor design

    DOEpatents

    Vujic, Jasmina L.

    1993-01-01

    Replacing regular mesh-dependent ray tracing modules in a collision/transfer probability (CTP) code with a ray tracing module based upon combinatorial geometry of a modified geometrical module (GMC) provides a general geometry transfer theory code in two dimensions (2D) for analyzing nuclear reactor design and control. The primary modification of the GMC module involves generation of a fixed inner frame and a rotating outer frame, where the inner frame contains all reactor regions of interest, e.g., part of a reactor assembly, an assembly, or several assemblies, and the outer frame, with a set of parallel equidistant rays (lines) attached to it, rotates around the inner frame. The modified GMC module allows for determining for each parallel ray (line), the intersections with zone boundaries, the path length between the intersections, the total number of zones on a track, the zone and medium numbers, and the intersections with the outer surface, which parameters may be used in the CTP code to calculate collision/transfer probability and cross-section values.

  1. Neutron transport analysis for nuclear reactor design

    DOEpatents

    Vujic, J.L.

    1993-11-30

    Replacing regular mesh-dependent ray tracing modules in a collision/transfer probability (CTP) code with a ray tracing module based upon combinatorial geometry of a modified geometrical module (GMC) provides a general geometry transfer theory code in two dimensions (2D) for analyzing nuclear reactor design and control. The primary modification of the GMC module involves generation of a fixed inner frame and a rotating outer frame, where the inner frame contains all reactor regions of interest, e.g., part of a reactor assembly, an assembly, or several assemblies, and the outer frame, with a set of parallel equidistant rays (lines) attached to it, rotates around the inner frame. The modified GMC module allows for determining for each parallel ray (line), the intersections with zone boundaries, the path length between the intersections, the total number of zones on a track, the zone and medium numbers, and the intersections with the outer surface, which parameters may be used in the CTP code to calculate collision/transfer probability and cross-section values. 28 figures.

  2. Finite size effects in neutron star and nuclear matter simulations

    NASA Astrophysics Data System (ADS)

    Giménez Molinelli, P. A.; Dorso, C. O.

    2015-01-01

    In this work we study molecular dynamics simulations of symmetric nuclear and neutron star matter using a semi-classical nucleon interaction model. Our aim is to gain insight on the nature of the so-called "finite size effects", unavoidable in this kind of simulations, and to understand what they actually affect. To do so, we explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. For nuclear matter simulations we show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the "nuclear pasta" phases expected in neutron star matter simulations, but only one structure per cell and shaped by specific artificial aspects of the simulations-for the same physical conditions (i.e. number density and temperature) different cells yield different solutions. The particular shape of the solution at low enough temperature and a given density can be predicted analytically by surface minimization. We also show that even if this behavior is due to the imposition of periodic boundary conditions on finite systems, this does not mean that it vanishes for very large systems, and it is actually independent of the system size. We conclude that, for nuclear matter simulations, the cells' size sets the only characteristic length scale for the inhomogeneities, and the geometry of the periodic cell determines the shape of those inhomogeneities.

  3. Probing the neutron-skin thickness by photon production from reactions induced by intermediate-energy protons

    NASA Astrophysics Data System (ADS)

    Wei, Gao-Feng

    2015-07-01

    The photon from neutron-proton bremsstrahlung in p +Pb reactions is examined as a potential probe of the neutron-skin thickness in different centralities and at different proton incident energies. It is shown that the best choice of reaction environment is about 140 MeV for the incident proton and the 95%-100% centrality for the reaction system since the incident proton mainly interacts with neutrons inside the skin of the target and thus leads to different photon production to a maximal extent. Moreover, considering two main uncertainties from both photon production probability and nucleon-nucleon cross section in the reaction, I propose to use the ratio of photon production from two reactions to measure the neutron-skin thickness because of its cancellation effects on these uncertainties simultaneously, but preserved about 13%-15% sensitivities on the varied neutron-skin thickness from 0.1 to 0.3 fm within the current experimental uncertainty range of the neutron-skin size in 208Pb.

  4. Neutron interrogation system using high gamma ray signature to detect contraband special nuclear materials in cargo

    DOEpatents

    Slaughter, Dennis R.; Pohl, Bertram A.; Dougan, Arden D.; Bernstein, Adam; Prussin, Stanley G.; Norman, Eric B.

    2008-04-15

    A system for inspecting cargo for the presence of special nuclear material. The cargo is irradiated with neutrons. The neutrons produce fission products in the special nuclear material which generate gamma rays. The gamma rays are detecting indicating the presence of the special nuclear material.

  5. Measurement of nuclear fuel pin hydriding utilizing epithermal neutron scattering

    SciTech Connect

    Miller, W.H.; Farkas, D.M.; Lutz, D.R.

    1996-12-31

    The measurement of hydrogen or zirconium hydriding in fuel cladding has long been of interest to the nuclear power industry. The detection of this hydrogen currently requires either destructive analysis (with sensitivities down to 1 {mu}g/g) or nondestructive thermal neutron radiography (with sensitivities on the order of a few weight percent). The detection of hydrogen in metals can also be determined by measuring the slowing down of neutrons as they collide and rapidly lose energy via scattering with hydrogen. This phenomenon is the basis for the {open_quotes}notched neutron spectrum{close_quotes} technique, also referred to as the Hysen method. This technique has been improved with the {open_quotes}modified{close_quotes} notched neutron spectrum technique that has demonstrated detection of hydrogen below 1 {mu}g/g in steel. The technique is nondestructive and can be used on radioactive materials. It is proposed that this technique be applied to the measurement of hydriding in zirconium fuel pins. This paper summarizes a method for such measurements.

  6. Neutron Capture and the Antineutrino Yield from Nuclear Reactors.

    PubMed

    Huber, Patrick; Jaffke, Patrick

    2016-03-25

    We identify a new, flux-dependent correction to the antineutrino spectrum as produced in nuclear reactors. The abundance of certain nuclides, whose decay chains produce antineutrinos above the threshold for inverse beta decay, has a nonlinear dependence on the neutron flux, unlike the vast majority of antineutrino producing nuclides, whose decay rate is directly related to the fission rate. We have identified four of these so-called nonlinear nuclides and determined that they result in an antineutrino excess at low energies below 3.2 MeV, dependent on the reactor thermal neutron flux. We develop an analytic model for the size of the correction and compare it to the results of detailed reactor simulations for various real existing reactors, spanning 3 orders of magnitude in neutron flux. In a typical pressurized water reactor the resulting correction can reach ∼0.9% of the low energy flux which is comparable in size to other, known low-energy corrections from spent nuclear fuel and the nonequilibrium correction. For naval reactors the nonlinear correction may reach the 5% level by the end of cycle. PMID:27058075

  7. Neutron Capture and the Antineutrino Yield from Nuclear Reactors.

    PubMed

    Huber, Patrick; Jaffke, Patrick

    2016-03-25

    We identify a new, flux-dependent correction to the antineutrino spectrum as produced in nuclear reactors. The abundance of certain nuclides, whose decay chains produce antineutrinos above the threshold for inverse beta decay, has a nonlinear dependence on the neutron flux, unlike the vast majority of antineutrino producing nuclides, whose decay rate is directly related to the fission rate. We have identified four of these so-called nonlinear nuclides and determined that they result in an antineutrino excess at low energies below 3.2 MeV, dependent on the reactor thermal neutron flux. We develop an analytic model for the size of the correction and compare it to the results of detailed reactor simulations for various real existing reactors, spanning 3 orders of magnitude in neutron flux. In a typical pressurized water reactor the resulting correction can reach ∼0.9% of the low energy flux which is comparable in size to other, known low-energy corrections from spent nuclear fuel and the nonequilibrium correction. For naval reactors the nonlinear correction may reach the 5% level by the end of cycle.

  8. Neutron Capture and the Antineutrino Yield from Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Huber, Patrick; Jaffke, Patrick

    2016-03-01

    We identify a new, flux-dependent correction to the antineutrino spectrum as produced in nuclear reactors. The abundance of certain nuclides, whose decay chains produce antineutrinos above the threshold for inverse beta decay, has a nonlinear dependence on the neutron flux, unlike the vast majority of antineutrino producing nuclides, whose decay rate is directly related to the fission rate. We have identified four of these so-called nonlinear nuclides and determined that they result in an antineutrino excess at low energies below 3.2 MeV, dependent on the reactor thermal neutron flux. We develop an analytic model for the size of the correction and compare it to the results of detailed reactor simulations for various real existing reactors, spanning 3 orders of magnitude in neutron flux. In a typical pressurized water reactor the resulting correction can reach ˜0.9 % of the low energy flux which is comparable in size to other, known low-energy corrections from spent nuclear fuel and the nonequilibrium correction. For naval reactors the nonlinear correction may reach the 5% level by the end of cycle.

  9. Isospin effects on neutrons as a probe of nuclear dissipation

    SciTech Connect

    Ye, W.

    2009-03-15

    Based on a dynamical Langevin equation coupled with a statistical decay model, we calculate the excess of the precision neutron multiplicity of the heavy nuclei {sup 240}Cf, {sup 246}Cf, {sup 252}Cf, and {sup 240}U over that predicted by the standard statistical model as a function of the postsaddle dissipation strength. We find that with increasing isospin of the system, the sensitivity of the excess to the dissipation strength decreases substantially. Moreover, for {sup 240}U, this excess is no longer sensitive to the nuclear dissipation. These results suggest that, on the experimental side, to accurately obtain information of the postsaddle dissipation strength by measuring the neutron multiplicity evaporated during the fission process of heavy nuclei, it is best to populate those compound systems with low isospin.

  10. Dose-Dependent Onset of Regenerative Program in Neutron Irradiated Mouse Skin

    PubMed Central

    Artibani, Mara; Kobos, Katarzyna; Colautti, Paolo; Negri, Rodolfo; Amendola, Roberto

    2011-01-01

    Background Tissue response to irradiation is not easily recapitulated by cell culture studies. The objective of this investigation was to characterize, the transcriptional response and the onset of regenerative processes in mouse skin irradiated with different doses of fast neutrons. Methodology/Principal Findings To monitor general response to irradiation and individual animal to animal variation, we performed gene and protein expression analysis with both pooled and individual mouse samples. A high-throughput gene expression analysis, by DNA oligonucleotide microarray was done with three months old C57Bl/6 mice irradiated with 0.2 and 1 Gy of mono-energetic 14 MeV neutron compared to sham irradiated controls. The results on 440 irradiation modulated genes, partially validated by quantitative real time RT-PCR, showed a dose-dependent up-regulation of a sub-class of keratin and keratin associated proteins, and members of the S100 family of Ca2+-binding proteins. Immunohistochemistry confirmed mRNA expression data enabled mapping of protein expression. Interestingly, proteins up-regulated in thickening epidermis: keratin 6 and S100A8 showed the most significant up-regulation and the least mouse-to-mouse variation following 0.2 Gy irradiation, in a concerted effort toward skin tissue regeneration. Conversely, mice irradiated at 1 Gy showed most evidence of apoptosis (Caspase-3 and TUNEL staining) and most 8-oxo-G accumulation at 24 h post-irradiation. Moreover, no cell proliferation accompanied 1 Gy exposure as shown by Ki67 immunohistochemistry. Conclusions/Significance The dose-dependent differential gene expression at the tissue level following in vivo exposure to neutron radiation is reminiscent of the onset of re-epithelialization and wound healing and depends on the proportion of cells carrying multiple chromosomal lesions in the entire tissue. Thus, this study presents in vivo evidence of a skin regenerative program exerted independently from DNA repair

  11. Neutron flux characterization of californium-252 Neutron Research Facility at the University of Texas - Pan American by nuclear analytical technique

    NASA Astrophysics Data System (ADS)

    Wahid, Kareem; Sanchez, Patrick; Hannan, Mohammad

    2014-03-01

    In the field of nuclear science, neutron flux is an intrinsic property of nuclear reaction facilities that is the basis for experimental irradiation calculations and analysis. In the Rio Grande Valley (Texas), the UTPA Neutron Research Facility (NRF) is currently the only neutron facility available for experimental research purposes. The facility is comprised of a 20-microgram californium-252 neutron source surrounded by a shielding cascade containing different irradiation cavities. Thermal and fast neutron flux values for the UTPA NRF have yet to be fully investigated and may be of particular interest to biomedical studies in low neutron dose applications. Though a variety of techniques exist for the characterization of neutron flux, neutron activation analysis (NAA) of metal and nonmetal foils is a commonly utilized experimental method because of its detection sensitivity and availability. The aim of our current investigation is to employ foil activation in the determination of neutron flux values for the UTPA NSRF for further research purposes. Neutron spectrum unfolding of the acquired experimental data via specialized software and subsequent comparison for consistency with computational models lends confidence to the results.

  12. Probing nuclear bubble structure via neutron star asteroseismology

    NASA Astrophysics Data System (ADS)

    Sotani, Hajime; Iida, Kei; Oyamatsu, Kazuhiro

    2016-10-01

    We consider torsional oscillations that are trapped in a layer of spherical-hole (bubble) nuclear structure, which is expected to occur in the deepest region of the inner crust of a neutron star. Because this layer intervenes between the phase of slab nuclei and the outer core of uniform nuclear matter, torsional oscillations in the bubble phase can be excited separately from usual crustal torsional oscillations. We find from eigenmode analyses for various models of the equation of state of uniform nuclear matter that the fundamental frequencies of such oscillations are almost independent of the incompressibility of symmetric nuclear matter, but strongly depend on the slope parameter of the nuclear symmetry energy L. Although the frequencies are also sensitive to the entrainment effect, i.e., what portion of nucleons outside bubbles contribute to the oscillations, by having such a portion fixed, we can successfully fit the calculated fundamental frequencies of torsional oscillations in the bubble phase inside a star of specific mass and radius as a function of L. By comparing the resultant fitting formula to the frequencies of quasi-periodic oscillations (QPOs) observed from the soft-gamma repeaters, we find that each of the observed low-frequency QPOs can be identified either as a torsional oscillation in the bubble phase or as a usual crustal oscillation, given generally accepted values of L for all the stellar models considered here.

  13. Characterization of the CRESST detectors by neutron induced nuclear recoils

    NASA Astrophysics Data System (ADS)

    Coppi, C.; Ciemniak, C.; von Feilitzsch, F.; Gütlein, A.; Hagn, H.; Isaila, C.; Jochum, J.; Kimmerle, M.; Lanfranchi, J.-C.; Pfister, S.; Potzel, W.; Rau, W.; Roth, S.; Rottler, K.; Sailer, C.; Scholl, S.; Usherov, I.; Westphal, W.

    CRESST is an experiment for the direct detection of dark matter particles via nuclear recoils. The CRESST detectors, based on CaWO4 scintillating crystals, are able to discriminate γ and β background by simultaneously measuring the light and phonon signals produced by particle interactions. The discrimination of the background is possible because of the different light output (Quenching Factor, QF) for nuclear and electron recoils. In this article a measurement is shown, aimed at the determination of the QFs of the different nuclei (O, Ca, W) of the detector crystal at 40-60 mK using an 11 MeV neutron beam produced at the Maier-Leibnitz-Laboratorium in Garching (MLL).

  14. A High Intensity Multi-Purpose D-D Neutron Generator for Nuclear Engineering Laboratories

    SciTech Connect

    Ka-Ngo Leung; Jasmina L. Vujic; Edward C. Morse; Per F. Peterson

    2005-11-29

    This NEER project involves the design, construction and testing of a low-cost high intensity D-D neutron generator for teaching nuclear engineering students in a laboratory environment without radioisotopes or a nuclear reactor. The neutron generator was designed, fabricated and tested at Lawrence Berkeley National Laboratory (LBNL).

  15. Plutonium Measurements with a Fast-Neutron Multiplicity Counter for Nuclear Safeguards Applications

    SciTech Connect

    Jennifer L. Dolan; Marek Flaska; Alexis Poitrasson-Riviere; Andreas Enqvist; Paolo Peerani; David L. Chichester; Sara A. Pozzi

    2014-11-01

    Measurements were performed at the Joint Research Centre in Ispra, Italy to field test a fast-neutron multiplicity counter developed at the University of Michigan. The measurements allowed the illustration of the system’s photon discrimination abilities, efficiency when measuring neutron multiplicity, ability to characterize 240Pueff mass, and performance relative to a currently deployed neutron coincidence counter. This work is motivated by the need to replace and improve upon 3He neutron detection systems for nuclear safeguards applications.

  16. Radiation effects of boron neutron capture therapy on brain, skin, and eye of rats

    SciTech Connect

    Matalka, K.Z.; Barth, R.F.; Bailey, M.Q.; Wilkie, D.A.; Koestner, A. ); Hopewell, J.W. )

    1994-03-30

    The present study was carried out to evaluate the radiation effects of boron neutron capture therapy (BNCT) on the brain, skin, and eyes of nude rats following systemic administration of boronophenylalanine (BPA) and neutron irradiation to the head. A solution containing 120 mg of [sup 10]B-enriched-L-BPA complexed with fructose was administered IP to nude rats. Boron concentrations were [approximately] 8.4, 9.4, 10.0, and 11.0 [mu]g/g in the brain, blood, skin, and eyes, respectively, at 6 h when the animals were irradiated at the Brookhaven Medical Research Reactor to cause tumor regression in nude rats carrying intracerebral implants of the human melanoma cell line MRA 27. Mild to moderate increases in loose fibrous tissue were observed in the choroid plexus at estimated physical doses to the brain and blood that ranged from 4.3-7.1 Gy and 4.6-7.7 Gy, respectively, and these appeared to be dose and time dependent. Other changes in the choroid plexus included occasional infiltrates of macrophages and polymorphonuclear leukocytes and vacuolation of epithelial cells. Dose-dependent moist desquamation of the skin was observed in all rats, but this had healed by 28 days following irradiation. Cataracts and keratitis developed in the eyes of most animals, and these were dose dependent. The minimal histopathological changes seen in the brain at doses that were sufficient to eradicate intracerebral melanoma indicates that BNCT has the potential to cure a tumor-bearing host without producing the normal brain injury usually associated with conventional external beam radiation therapy. Studies in canines, which currently are in progress, should further define the dose-effect relationships of BNCT on critical neuroanatomic structures within the brain. 42 refs., 4 figs., 3 tabs.

  17. Neutron cross-sections for advanced nuclear systems: the n_TOF project at CERN

    NASA Astrophysics Data System (ADS)

    Barbagallo, M.; Mastromarco, M.; Colonna, N.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Duran, I.; Dressler, R.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Hernández-Prieto, A.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Krtička, M.; Kroll, J.; Lampoudis, C.; Langer, C.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Leong, L. S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P. F.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondalaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Rubbia, C.; Sabaté-Gilarte, M.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.; Žugec, P.

    2014-12-01

    The study of neutron-induced reactions is of high relevance in a wide variety of fields, ranging from stellar nucleosynthesis and fundamental nuclear physics to applications of nuclear technology. In nuclear energy, high accuracy neutron data are needed for the development of Generation IV fast reactors and accelerator driven systems, these last aimed specifically at nuclear waste incineration, as well as for research on innovative fuel cycles. In this context, a high luminosity Neutron Time Of Flight facility, n_TOF, is operating at CERN since more than a decade, with the aim of providing new, high accuracy and high resolution neutron cross-sections. Thanks to the features of the neutron beam, a rich experimental program relevant to nuclear technology has been carried out so far. The program will be further expanded in the near future, thanks in particular to a new high-flux experimental area, now under construction.

  18. Distinction between Proton- and Neutron-Density Distributions of Halo Nuclei at the Nuclear Surface via Reaction Cross Sections

    NASA Astrophysics Data System (ADS)

    Nishimura, Daiki; Fukuda, M.; Takechi, M.; Mihara, M.; Ishikawa, D.; Matsuta, K.; Matsumiya, R.; Kuboki, T.; Suzuki, T.; Yamaguchi, T.; Hachiuma, I.; Namihira, K.; Ohtsubo, T.; Shinbara, Y.; Ohkuma, Y.; Izumikawa, T.; Tanaka, K.; Ozawa, A.; Yasuda, Y.; Moriguchi, T.; Momota, S.; Fukuda, S.; Sato, S.; Kanazawa, M.; Kitagawa, A.

    2009-10-01

    The halo and skin structures at the nuclear surface have attracted much interest for their exotic nature. By utilizing the isospin asymmetry of nucleon-nucleon total cross sections in the intermediate energy region, in principle, the proton- and neutron-density distributions can be determined independently. To demonstrate this isospin asymmetric effect, we have studied σR for the neutron-halo nucleus ^11 Be and the proton-halo nucleus ^8B on proton targets. We measured σR for ^11Be and ^8B on C and proton targets by the transmission method in the intermidiate energy region using HIMAC heavy ion synchrotron at NIRS. The present result for ^11Be is consistent with that the tail of ^11Be density consists of a neutron. On the other hand, the experimental result for ^8B is in agreement with the calculation with a proton tail in ^8B. Thus, the proton and neutron density distributions at the nuclear surface can be distinguished successfully by the σR on C and proton targets.

  19. Nuclear fusion and carbon flashes on neutron stars

    NASA Technical Reports Server (NTRS)

    Taam, R. E.; Picklum, R. E.

    1978-01-01

    This paper reports on detailed calculations of the thermal evolution of the carbon-burning shells in the envelopes of accreting neutron stars for mass-accretion rates of 1 hundred-billionth to 2 billionths of a solar mass per yr and neutron-star masses of 0.56 and 1.41 solar masses. The work of Hansen and Van Horn (1975) is extended to higher densities, and a more detailed treatment of nuclear processing in the hydrogen- and helium-burning regions is included. Results of steady-state calculations are presented, and results of time-dependent computations are examined for accretion rates of 3 ten-billionths and 1 billionth of solar mass per yr. It is found that two evolutionary sequences lead to carbon flashes and that the carbon abundance at the base of the helium shell is a strong function of accretion rate. Upper limits are placed on the accretion rates at which carbon flashes will be important.

  20. The use of neutron scattering in nuclear weapons research

    SciTech Connect

    Juzaitis, R.J.

    1995-10-01

    We had a weapons science breakout session last week. Although it would have been better to hold it closer in time to this workshop, I think that it was very valuable. it may have been less of a {open_quotes}short-sleeve{close_quotes} workshop environment than we would have liked, but as the first time two communities-the weapons community and the neutron scattering community- got together, it was a wonderful opportunity to transfer information during the 24 presentations that were made. This report contains discussions on the fundamental analysis of documentation of the enduring stockpile; LANSCE`s contribution to weapons; spallation is critical to understanding; weapons safety assessments; applied nuclear physics requires cross section information; fission models need refinement; and establishing teams on collaborative projects.

  1. Neutron and nuclear data revised for the 1997/98 handbook of chemistry and physics

    SciTech Connect

    Holden, N.E.

    1997-07-01

    The 1997/98 Handbook of Chemistry and Physics will contain revised nuclear data information dealing with scattering and absorption properties of neutrons. All of these nuclear data were recently reevaluated. The 2,200 meter per second neutron cross sections and the neutron resonance integrals evaluation was performed in conjunction with the 1997 KAPL Wall-Chart of the Nuclides to insure consistency in the recommended values in the Handbook and on the Chart. The 2,200 meters per second neutron cross sections presented in the Handbook correspond to room temperature neutrons, 20.43 C, or a thermal neutron energy of 0.0253 electron volts, (eV). Neutron resonance integrals are defined over the energy range from 0.5 eV up to 0.1 {times} 10{sup 6} eV. They are averaged over a flux spectrum with a 1/E shape. Evaluated experimental data are derived from either a direct measurement or from 1/E spectrum averaged resonance parameter information. Resonance integrals are presented for neutron capture, charged particle or neutron fission reactions. Thermal neutron scattering is used for the investigation of the static and dynamic properties of condensed matter and it requires a knowledge of neutron scattering lengths. The Handbook presents bound atom neutron coherent scattering lengths in units of fentometers. Stellar slow neutron capture processes occur in a thermal neutron spectrum with temperatures approximately 30 keV. 30 keV Maxwellian averaged neutron cross sections for astrophysical applications are a new parameter presented in the 78th edition of the Handbook. No new parameters will be added to the Table of Isotopes` nuclear information but revised values will be provided for parameters of all known nuclides of the 112 chemical elements.

  2. Neutron-skin thickness from the study of the anti-analog giant dipole resonance

    SciTech Connect

    Krasznahorkay, A.; Stuhl, L.; Csatlos, M.; Algora, A.; and others

    2012-10-20

    The {gamma}-decay of the anti-analog of the giant dipole resonance (AGDR) to the isobaric analog state has been measured following the p({sup 124}Sn,n) reaction at a beam energy of 600 MeV/nucleon. The energy of the transition was also calculated with state-of-the-art self-consistent relativistic random-phase approximation (RPA) and turned out to be very sensitive to the neutronskin thickness ({Delta}R{sub pn}). By comparing the theoretical results with the measured one, the {Delta}R{sub pn} value for {sup 124}Sn was deduced to be 0.21 {+-} 0.07 fm, which agrees well with the previous results. The present method offers new possibilities for measuring the neutron-skin thicknesses of very exotic isotopes.

  3. Computer programs for absolute neutron activation analysis on the nuclear data 6620 data acquisition system

    SciTech Connect

    Wade, J.W.; Emery, J.F.

    1982-03-01

    Five computer programs that provide multielement neutron activation analysis are discussed. The software package was designed for use on the Nuclear Data 6620 Data Acquisition System and interacts with existing Nuclear Data Corporation software. The programs were developed to make use of the capabilities of the 6620 system to analyze large numbers of samples and assist in a large sample workload that had begun in the neutron activation analysis facility of the Oak Ridge Research Reactor. Nuclear Data neutron activation software is unable to perform absolute activation analysis and therefore was inefficient and inadequate for our applications.

  4. Development of Measurement Methods for Detection of Special Nuclear Materials using D-D Pulsed Neutron Source

    NASA Astrophysics Data System (ADS)

    Misawa, Tsuyoshi; Takahashi, Yoshiyuki; Yagi, Takahiro; Pyeon, Cheol Ho; Kimura, Masaharu; Masuda, Kai; Ohgaki, Hideaki

    2015-10-01

    For detection of hidden special nuclear materials (SNMs), we have developed an active neutron-based interrogation system combined with a D-D fusion pulsed neutron source and a neutron detection system. In the detection scheme, we have adopted new measurement techniques simultaneously; neutron noise analysis and neutron energy spectrum analysis. The validity of neutron noise analysis method has been experimentally studied in the Kyoto University Critical Assembly (KUCA), and was applied to a cargo container inspection system by simulation.

  5. Determining the nuclear equation of state from neutron-star masses and radii

    NASA Technical Reports Server (NTRS)

    Lindblom, Lee

    1992-01-01

    A method is developed for determining the nuclear equation of state directly from a knowledge of the masses and radii of neutron stars. This analysis assumes only that equilibrium neutron-star matter has the stress-energy tensor of an isotropic fluid with a barotropic equation of state, and that general relativity describes a neutron star's internal gravitational field. We present numerical examples which illustrate how well this method will determine the equation of state when the appropriate observational data become available.

  6. Neutron Radiography and Fission Mapping Measurements of Nuclear Materials with Varying Composition and Shielding

    SciTech Connect

    Mullens, James Allen; McConchie, Seth M; Hausladen, Paul; Mihalczo, John T; Grogan, Brandon R; Sword, Eric D

    2011-01-01

    Neutron radiography and fission mapping measurements were performed on four measurement objects with varying composition and shielding arrangements at the Idaho National Laboratory's Zero Power Physics Reactor (ZPPR) facility. The measurement objects were assembled with ZPPR reactor plate materials comprising plutonium, natural uranium, or highly enriched uranium and were presented as unknowns for characterization. As a part of the characterization, neutron radiography was performed using a deuterium-tritium (D-T) neutron generator as a source of time and directionally tagged 14 MeV neutrons. The neutrons were detected by plastic scintillators placed on the opposite side of the object, using the time-correlation-based data acquisition of the Nuclear Materials Identification System developed at Oak Ridge National Laboratory. Each object was measured at several rotations with respect to the neutron source to obtain a tomographic reconstruction of the object and a limited identification of materials via measurement of the neutron attenuation. Large area liquid scintillators with pulse shape discrimination were used to detect the induced fission neutrons. A fission site map reconstruction was produced by time correlating the induced fission neutrons with each tagged neutron from the D-T neutron generator. This paper describes the experimental configuration, the ZPPR measurement objects used, and the neutron imaging and fission mapping results.

  7. Demonstration of Emitted-Neutron Computed Tomography to Quantify Nuclear Materials

    SciTech Connect

    Hausladen, Paul; Blackston, Matthew A; Newby, Jason

    2011-09-01

    In this document, we report demonstration of emitted-neutron computed tomography using fast fission neutrons to infer the geometry of sources of special nuclear material (SNM). The imaging system employed in the demonstration is based on a newly constructed array of pixelated neutron detectors that are suitable for arrangement in a close-packed imaging array and whose active volume consists of liquid scintillator EJ-309 which allows neutron-gamma discrimination via pulse shape to enable essentially pure fast-neutron imaging. The system is capable of high quality fast-neutron imaging where tomographic reconstruction of slices through an object resolves neutron sources similar in dimension to a fuel pellet, or about 1 cm. During measurements of Pu MOX fuel rodlet arrays in soup cans at the INL ZPPR facility, the position of a partial defect of a single rodlet containing Pu replaced by one containing depleted uranium (DU) was detected.

  8. Constraints on Neutron Density and Temperature Conditions for Astrophysical r-PROCESS from Updated Nuclear Masses

    NASA Astrophysics Data System (ADS)

    Xu, X. D.; Sun, B.; Niu, Z. M.; Li, Z.; Meng, J.

    2013-11-01

    Based on the (n, γ) ⇌ (γ, n) equilibrium, the neutron density and temperature conditions required for the r-process are constrained with updated nuclear masses. It is found that the uncertainty of determined neutron density and temperature ranges can be greatly minimized when mass values tabulated in the latest Atomic Mass Evaluation AME2011-preview are employed.

  9. Neutron measurements in Spanish nuclear power plants with a Bonner sphere spectrometer system.

    PubMed

    Fernández, F; Domingo, C; Amgarou, K; Bouassoule, T; García, M J

    2007-01-01

    Neutron spectrometric measurements with an active Bonner Sphere System (BSS) allowed us to determine the reference dosimeter values in Ascó I and II and Cofrentes (PWR, BWR) Spanish nuclear power plants. Under a request from the Spanish National Nuclear Safety Council, the UAB group was in charge of characterising the neutron fields at several measurement points (a total of 10) inside the containment building of these nuclear installations using an active BSS and a home-made MITOM unfolding code. The measurement results in the three installations confirm the presence of low-energy neutron components in almost all selected points. This developed BSS can be considered as a reference system in neutron radiation protection when defining the corresponding protocols for a correct personal dosimetry in nuclear power plant installations.

  10. The Effect Of Neutron Attenuation On Power Deposition In Nuclear Pumped 3He-Lasers

    NASA Astrophysics Data System (ADS)

    Çetin, Füsun

    2007-04-01

    Nuclear-pumped lasers (NPLs) are driven by the products of nuclear reactions and directly convert the nuclear energy to directed optical energy. Pumping gas lasers by nuclear reaction products has the advantage of depositing large energies per reaction. The need for high laser power output implies high operating pressure. In the case of volumetric excitation by 3He(n, p)3H reactions, however, operation at high pressure (more than a few atm) causes excessive neutron attenuation in the 3He gas. This fact adversely effects on energy deposition and, hence, laser output power and beam quality. Here, spatial and temporal variations of neutron flux inside a closed 3He -filled cylindrical laser tube have been numerically calculated for various tube radii and operating pressures by using a previously reported dynamic model for energy deposition. Calculations are made by using ITU TRIGA Mark II Reactor as the neutron source. The effects of neutron attenuation on power deposition are examined.

  11. Probing neutron rich matter with parity violation

    NASA Astrophysics Data System (ADS)

    Horowitz, Charles

    2016-03-01

    Many compact and energetic astrophysical systems are made of neutron rich matter. In contrast, most terrestrial nuclei involve approximately symmetric nuclear matter with more equal numbers of neutrons and protons. However, heavy nuclei have a surface region that contains many extra neutrons. Precision measurements of this neutron rich skin can determine properties of neutron rich matter. Parity violating electron scattering provides a uniquely clean probe of neutrons, because the weak charge of a neutron is much larger than that of a proton. We describe first results and future plans for the Jefferson Laboratory experiment PREX that measures the thickness of the neutron skin in 208Pb. Another JLAB experiment CREX will measure the neutron radius of 48Ca and test recent microscopic calculations of this neutron rich 48 nucleon system. Finally, we show how measuring parity violation at multiple momentum transfers can determine not just the neutron radius but the full radial structure of the neutron density in 48Ca. A neutron star is eighteen orders of magnitude larger than a nucleus (km vs fm) but both the star and the neutron rich nuclear skin are made of the same neutrons, with the same strong interactions, and the same equation of state. A large pressure pushes neutrons out against surface tension and gives a thick neutron skin. Therefore, PREX will constrain the equation of state of neutron rich matter and improve predictions for the structure of neutron stars. Supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  12. EQUATION OF STATE AND NEUTRON STAR PROPERTIES CONSTRAINED BY NUCLEAR PHYSICS AND OBSERVATION

    SciTech Connect

    Hebeler, K.; Lattimer, J. M.; Pethick, C. J.; Schwenk, A.

    2013-08-10

    Microscopic calculations of neutron matter based on nuclear interactions derived from chiral effective field theory, combined with the recent observation of a 1.97 {+-} 0.04 M{sub Sun} neutron star, constrain the equation of state of neutron-rich matter at sub- and supranuclear densities. We discuss in detail the allowed equations of state and the impact of our results on the structure of neutron stars, the crust-core transition density, and the nuclear symmetry energy. In particular, we show that the predicted range for neutron star radii is robust. For use in astrophysical simulations, we provide detailed numerical tables for a representative set of equations of state consistent with these constraints.

  13. Advanced Neutron Detection Methods: new Tools for Countering Nuclear Terrorism (412th Brookhaven Lecture)

    SciTech Connect

    Vanier, Peter

    2006-02-15

    Acts of terrorism have become almost daily occurrences in the international news. Yet one of the most feared types of terrorism — nuclear terrorism — has not yet happened. One important way of preventing nuclear terrorism is to safeguard nuclear materials, and many people worldwide work continuously to achieve that goal. A second, vital defense is being developed: greatly improved methods of detecting material that a nuclear terrorist would need so that timely discovery of the material could become more probable. Special nuclear materials can emit neutrons, either spontaneously or when excited by a source of high-energy gamma rays, such as an electron accelerator. Traditional neutron detectors can sense these neutrons, but not the direction from which the neutrons come, or their energy. The odds against finding smuggled nuclear materials using conventional detectors are great. However, innovative designs of detectors are producing images that show the locations and even the shapes of man-made neutron sources, which stand out against the uniform background produced by cosmic rays. With the new detectors, finding needles in haystacks — or smuggled nuclear materials in a huge container among thousands of others in a busy port — suddenly becomes possible.

  14. Identifying Nuclear Material via Prompt Photo-Neutron Multiplicity Measurements

    SciTech Connect

    Hausladen, Paul; Mihalczo, John T; Blackburn, Brandon; Watson, Scott; Jones, James L.; Hunt, Alan W

    2009-01-01

    Proof-of-principle measurements are reported demonstrating that multiplicity techniques can be used to identify prompt fission neutrons from photonuclear interrogation under circumstances where the fission neutrons may be accompanied by photodissociated neutrons of an identical energy spectrum, and where the emitted neutrons are naturally bunched in time by the pulsed nature of the interrogating photon beam. The technique shows promise as a method for the detection of highly enriched uranium (HEU) compared to techniques based on delayed neutrons because prompt neutrons are orders of magnitude more abundant, and compared to passive multiplicity techniques because actively induced fission rates are orders of magnitude higher than spontaneous fission rates in HEU. The technique also shows promise in that multiplicity signatures can be used to distinguish HEU from other fissionable material.

  15. Nuclear deposits of immunoglobulins in skin of patients with systemic lupus erythematosus.

    PubMed Central

    Shu, S; Provost, T; Croxdale, M B; Reichlin, M; Beutner, E H

    1977-01-01

    Skin nuclear speckled IgG deposition was noted in seven patients. The patients' clinical courses satisfied at least four of the preliminary criteria of the American Rheumatism Association for the diagnosis of systemic lupus erthematosus (SLE). Examination of approximately 700 additional biopsies from patiets with SLE, connective tissue and various skin diseases as well as normal individuals, failed to demonstrate similar nuclear immunoglobulin deposition. Sera from these seven patients had higher titre, complement fixing anti-nuclear antibodies (ANA) of IgG class which produced a speckled nuclear fluorescent pattern. In addition, the sera of all seven patients demonstrated by gel double diffusion precipitating antibodies against nuclear ribonucleoprotein (RNP) or Sm antigens. PMID:300310

  16. Detection of fast neutrons from shielded nuclear materials using a semiconductor alpha detector.

    PubMed

    Pöllänen, R; Siiskonen, T

    2014-08-01

    The response of a semiconductor alpha detector to fast (>1 MeV) neutrons was investigated by using measurements and simulations. A polyethylene converter was placed in front of the detector to register recoil protons generated by elastic collisions between neutrons and hydrogen nuclei of the converter. The developed prototype equipment was tested with shielded radiation sources. The low background of the detector and insensitivity to high-energy gamma rays above 1 MeV are advantages when the detection of neutron-emitting nuclear materials is of importance. In the case of a (252)Cf neutron spectrum, the intrinsic efficiency of fast neutron detection was determined to be 2.5×10(-4), whereas three-fold greater efficiency was obtained for a (241)AmBe neutron spectrum.

  17. Exploring medium effects on the nuclear force

    SciTech Connect

    F. Sammarruca

    2004-04-18

    This STI product contains a description of results from theoretical studies in nuclear physics. The goal is a systematic investigation of the nuclear force in the nuclear medium. The problems addressed are: density-dependent effective interactions as seen through proton-nucleus reactions, nuclear matter with unequal densities of protons and neutrons, applications to asymmetric nuclei through predictions of neutron radii and neutron skins.

  18. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device

    PubMed Central

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C.; Marino, Stephen A.; Geard, Charles R.; Brenner, David J.; Garty, Guy

    2015-01-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  19. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  20. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields.

  1. Models of neutron star atmospheres enriched with nuclear burning ashes

    NASA Astrophysics Data System (ADS)

    Nättilä, J.; Suleimanov, V. F.; Kajava, J. J. E.; Poutanen, J.

    2015-09-01

    Context. Low-mass X-ray binaries hosting neutron stars (NS) exhibit thermonuclear (type-I) X-ray bursts, which are powered by unstable nuclear burning of helium and/or hydrogen into heavier elements deep in the NS "ocean". In some cases the burning ashes may rise from the burning depths up to the NS photosphere by convection, leading to the appearance of the metal absorption edges in the spectra, which then force the emergent X-ray burst spectra to shift toward lower energies. Aims: These effects may have a substantial impact on the color correction factor fc and the dilution factor w, the parameters of the diluted blackbody model FE ≈ wBE(fcTeff) that is commonly used to describe the emergent spectra from NSs. The aim of this paper is to quantify how much the metal enrichment can change these factors. Methods: We have developed a new NS atmosphere modeling code, which has a few important improvements compared to our previous code required by inclusion of the metals. The opacities and the internal partition functions (used in the ionization fraction calculations) are now taken into account for all atomic species. In addition, the code is now parallelized to counter the increased computational load. Results: We compute a detailed grid of atmosphere models with different exotic chemical compositions that mimic the presence of the burning ashes. From the emerging model spectra we compute the color correction factors fc and the dilution factors w that can then be compared to the observations. We find that the metals may change fc by up to about 40%, which is enough to explain the scatter seen in the blackbody radius measurements. Conclusions: The presented models open up the possibility of determining NS mass and radii more accurately, and may also act as a tool to probe the nuclear burning mechanisms of X-ray bursts. Appendices are available in electronic form at http://www.aanda.orgData of Appendix B is only available at the CDS via anonymous ftp to http

  2. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-03-18

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  3. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1995-10-03

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  4. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-08-05

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  5. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-03-18

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  6. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-08-05

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized. by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  7. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1995-10-03

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  8. Passive Measurement of Organic-Scintillator Neutron Signatures for Nuclear Safeguards Applications

    SciTech Connect

    Jennfier L. Dolan; Eric C. Miller; Alexis C. Kaplan; Andreas Enqvist; Marek Flaska; Alice Tomanin; Paolo Peerani; David L. Chichester; Sara A. Pozzi

    2012-10-01

    At nuclear facilities, domestically and internationally, most measurement systems used for nuclear materials’ control and accountability rely on He-3 detectors. Due to resource shortages, alternatives to He-3 systems are needed. This paper presents preliminary simulation and experimental efforts to develop a fast-neutron-multiplicity counter based on liquid organic scintillators. This mission also provides the opportunity to broaden the capabilities of such safeguards measurement systems to improve current neutron-multiplicity techniques and expand the scope to encompass advanced nuclear fuels.

  9. Neutron detection of the Triga Mark III reactor, using nuclear track methodology

    SciTech Connect

    Espinosa, G. Golzarri, J. I.; Raya-Arredondo, R.; Cruz-Galindo, S.; Sajo-Bohus, L.

    2015-07-23

    Nuclear Track Methodology (NTM), based on the neutron-proton interaction is one often employed alternative for neutron detection. In this paper we apply NTM to determine the Triga Mark III reactor operating power and neutron flux. The facility nuclear core, loaded with 85 Highly Enriched Uranium as fuel with control rods in a demineralized water pool, provide a neutron flux around 2 × 10{sup 12} n cm{sup −2} s{sup −1}, at the irradiation channel TO-2. The neutron field is measured at this channel, using Landauer{sup ®} PADC as neutron detection material, covered by 3 mm Plexiglas{sup ®} as converter. After exposure, plastic detectors were chemically etched to make observable the formed latent tracks induced by proton recoils. The track density was determined by a custom made Digital Image Analysis System. The resulting average nuclear track density shows a direct proportionality response for reactor power in the range 0.1-7 kW. We indicate several advantages of the technique including the possibility to calibrate the neutron flux density measured at low reactor power.

  10. Neutron detection of the Triga Mark III reactor, using nuclear track methodology

    NASA Astrophysics Data System (ADS)

    Espinosa, G.; Golzarri, J. I.; Raya-Arredondo, R.; Cruz-Galindo, S.; Sajo-Bohus, L.

    2015-07-01

    Nuclear Track Methodology (NTM), based on the neutron-proton interaction is one often employed alternative for neutron detection. In this paper we apply NTM to determine the Triga Mark III reactor operating power and neutron flux. The facility nuclear core, loaded with 85 Highly Enriched Uranium as fuel with control rods in a demineralized water pool, provide a neutron flux around 2 × 1012 n cm-2 s-1, at the irradiation channel TO-2. The neutron field is measured at this channel, using Landauer® PADC as neutron detection material, covered by 3 mm Plexiglas® as converter. After exposure, plastic detectors were chemically etched to make observable the formed latent tracks induced by proton recoils. The track density was determined by a custom made Digital Image Analysis System. The resulting average nuclear track density shows a direct proportionality response for reactor power in the range 0.1-7 kW. We indicate several advantages of the technique including the possibility to calibrate the neutron flux density measured at low reactor power.

  11. Spallation neutron production and the current intra-nuclear cascade and transport codes

    NASA Astrophysics Data System (ADS)

    Filges, D.; Goldenbaum, F.; Enke, M.; Galin, J.; Herbach, C.-M.; Hilscher, D.; Jahnke, U.; Letourneau, A.; Lott, B.; Neef, R.-D.; Nünighoff, K.; Paul, N.; Péghaire, A.; Pienkowski, L.; Schaal, H.; Schröder, U.; Sterzenbach, G.; Tietze, A.; Tishchenko, V.; Toke, J.; Wohlmuther, M.

    A recent renascent interest in energetic proton-induced production of neutrons originates largely from the inception of projects for target stations of intense spallation neutron sources, like the planned European Spallation Source (ESS), accelerator-driven nuclear reactors, nuclear waste transmutation, and also from the application for radioactive beams. In the framework of such a neutron production, of major importance is the search for ways for the most efficient conversion of the primary beam energy into neutron production. Although the issue has been quite successfully addressed experimentally by varying the incident proton energy for various target materials and by covering a huge collection of different target geometries --providing an exhaustive matrix of benchmark data-- the ultimate challenge is to increase the predictive power of transport codes currently on the market. To scrutinize these codes, calculations of reaction cross-sections, hadronic interaction lengths, average neutron multiplicities, neutron multiplicity and energy distributions, and the development of hadronic showers are confronted with recent experimental data of the NESSI collaboration. Program packages like HERMES, LCS or MCNPX master the prevision of reaction cross-sections, hadronic interaction lengths, averaged neutron multiplicities and neutron multiplicity distributions in thick and thin targets for a wide spectrum of incident proton energies, geometrical shapes and materials of the target generally within less than 10% deviation, while production cross-section measurements for light charged particles on thin targets point out that appreciable distinctions exist within these models.

  12. APSTNG: Neutron interrogation for detection of nuclear and CW weapons, explosives, and drugs

    SciTech Connect

    Rhodes, E.; Dickerman, C.E.; De Volpi, A.; Peters, C.W.

    1992-07-01

    A recently developed neutron diagnostic probe system has the potential to satisfy a significant number of van-mobile and fixed- portal requirements for nondestructive verification of sealed munitions and detection of contraband explosives and drugs. The probe is based on a unique associated-particle sealed-tube neutron generator (APSTNG) that interrogates the object of interest with a low-intensity beam of 14-MeV neutrons generated from the deuterium-tritium reaction and that detects the alpha-particle associated with each neutron. Gamma-ray spectra of resulting neutron inelastic scattering and fission reactions identify nuclides associated with all major chemicals in chemical warfare agents, explosives, and drugs, as well as many pollutants and fissile and fertile special nuclear material. Flight times determined from determined from detection times of the gamma-rays and alpha-particles yield a separate tomographic image of each identified nuclide. The APSTNG also forms the basis for a compact fast-neutron transmission imaging system that can be used along with or instead of the emission imaging system; a collimator is not required since scattered neutrons are removed by ``electronic collimation`` (detected neutrons not having the proper flight time to be uncollided are discarded). The small and relatively inexpensive APSTNG exhibits high reliability and can be quickly replaced. Proof-of-concept experiments have been performed under laboratory conditions for simulated nuclear and chemical warfare munitions and for explosives and drugs.

  13. APSTNG: Neutron interrogation for detection of nuclear and CW weapons, explosives, and drugs

    SciTech Connect

    Rhodes, E.; Dickerman, C.E.; De Volpi, A. ); Peters, C.W. )

    1992-01-01

    A recently developed neutron diagnostic probe system has the potential to satisfy a significant number of van-mobile and fixed- portal requirements for nondestructive verification of sealed munitions and detection of contraband explosives and drugs. The probe is based on a unique associated-particle sealed-tube neutron generator (APSTNG) that interrogates the object of interest with a low-intensity beam of 14-MeV neutrons generated from the deuterium-tritium reaction and that detects the alpha-particle associated with each neutron. Gamma-ray spectra of resulting neutron inelastic scattering and fission reactions identify nuclides associated with all major chemicals in chemical warfare agents, explosives, and drugs, as well as many pollutants and fissile and fertile special nuclear material. Flight times determined from determined from detection times of the gamma-rays and alpha-particles yield a separate tomographic image of each identified nuclide. The APSTNG also forms the basis for a compact fast-neutron transmission imaging system that can be used along with or instead of the emission imaging system; a collimator is not required since scattered neutrons are removed by electronic collimation'' (detected neutrons not having the proper flight time to be uncollided are discarded). The small and relatively inexpensive APSTNG exhibits high reliability and can be quickly replaced. Proof-of-concept experiments have been performed under laboratory conditions for simulated nuclear and chemical warfare munitions and for explosives and drugs.

  14. Displacement damage induce degradation of COTS array CCDs irradiated by neutron beams from a nuclear reactor

    NASA Astrophysics Data System (ADS)

    Wang, Zujun; Chen, Wei; Xiao, Zhigang; Liu, Minbo; Huang, Shaoyan; He, Baoping; Luo, Tongding

    2015-01-01

    The experiments of displacement damage effects on COTS array charge coupled devices (CCDs) induced by neutron irradiation from a nuclear reactor are presented. The charge transfer inefficiency (CTI), saturation output signal voltage (VS), dynamic range (DR), dark signal, and camera imaging quality versus neutron fluence are investigated. The degradation mechanisms of the CCDs irradiated by reactor neutron beams are also analyzed. The CTI increase due to neutron displacement damage appears to be proportional to displacement damage dose. The experiments show that VS degradation induced by neutron irradiation is much less than that induced by gamma irradiation. The dark images from the CCDs irradiated by neutrons are given to investigate dark signal degradation. The degradation forms and mechanisms of the camera imaging quality are very different between the reactor neutron displacement damage and the gamma total ionization dose damage. The three samples were exposed by 1 MeV neutron-equivalent fluences of 1×1011, 5×1011, and 1×1012 n/cm2, respectively. A sample was exposed by 1 MeV neutron-equivalent fluences up to 2×1013 n/cm2, and the CCD is a functional failure after irradiation.

  15. Measurement of Neutron Emissions from Nuclear Muon Capture

    NASA Astrophysics Data System (ADS)

    Alexander, Damien; AlCap Collaboration

    2015-10-01

    The AlCap collaboration is studying particle emission after muon capture on Al and Ti nuclei. Proton and neutron emission are an important source of accidental activity in the Mu2e and COMET experiments, which will search for charged lepton flavor violation (CLFV) in neutrino-less muon to electron conversion in the field of an atomic nucleus. A recent experiment was completed at the high intensity piE5 beamline at the Paul Scherrer Institute (PSI) focusing on neutron and gamma emissions from Al. AlCap expects to obtain the bound muon lifetime, the low-energy neutron spectrum, and the neutron emission rates per muon capture. The current state of the analysis will be presented. Funded in part by US DoE.

  16. Nuclear and dosimetric features of an isotopic neutron source

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, H. R.; Hernández-Dávila, V. M.; Rivera, T.; Sánchez, A.

    2014-02-01

    A multisphere neutron spectrometer was used to determine the features of a 239PuBe neutron source that is used to operate the ESFM-IPN Subcritical Reactor. To determine the source main features it was located a 100 cm from the spectrometer which was a 6LiI(Eu) scintillator and 2, 3, 5, 8, 10 and 12 in.-diameter polyethylene spheres. Count rates obtained with the spectrometer were unfolded using the NSDUAZ code and neutron spectrum, total fluence, and ambient dose equivalent were determined. A Monte Carlo calculation was carried out to estimate the spectrum and integral features being less than values obtained experimentally due to the presence of 241Pu in the Pu used to fabricate the source. Actual neutron yield and the mass fraction of 241Pu was estimated.

  17. Neutron scattering facility for the calibration of the response to nuclear recoils

    NASA Astrophysics Data System (ADS)

    Jochum, J.; Chambon, B.; Drain, D.; von Feilitzsch, F.; Gascon, J.; Huber, M.; Jagemann, T.; de Jésus, M.; Lachenmaier, T.; Lanfranchi, J.-C.; Martineau, O.; Potzel, W.; Rüdig, A.; Schnagl, J.; Simon, E.; Stark, M.; Stern, M.; Wulandari, H.

    2002-02-01

    A possibility to search for elementary particles as dark matter candidates is to detect elastic scattering with cryogenic detectors. For the interpretation of the data one has to determine the detector response to nuclear recoils, the so-called quenching factors. They can differ for the heat-, for the scintillation- and for the ionization-signal and can be measured by scattering of neutrons. The CRESST- and the EDELWEISS-collaborations have set up a neutron scattering facility for cryogenic detectors at the tandem-accelerator of the Munich `Maier-Leibniz-Labor.' The scattering angle and the time-of-flight of the neutrons are measured by an array of liquid scintillator cells. The pulsed high energy (11 MeV) neutron beam is created by nuclear reaction of a 11B on a H2-gas target. The set-up and the results of first tests are presented. .

  18. Nuclear Astrophysics and Neutron Cross Section Measurements Using the ORELA

    SciTech Connect

    Winters, R. R.

    2000-08-25

    This is the final report for a research program which has been continuously supported by the AEC, ERDA, or USDOE since 1973. The neutron total and capture cross sections for n + {sup 88}Sr have been measured over the neutron energy range 100 eV to 1 MeV. The report briefly summaries our results and the importance of this work for nucleosynthesis and the optical model.

  19. Broad Energy Range Neutron Spectroscopy using a Liquid Scintillator and a Proportional Counter: Application to a Neutron Spectrum Similar to that from an Improvised Nuclear Device

    PubMed Central

    Randers-Pehrson, Gerhard; Marino, Stephen A.; Garty, Guy; Harken, Andrew; Brenner, David J.

    2015-01-01

    A novel neutron irradiation facility at the Radiological Research Accelerator Facility (RARAF) has been developed to mimic the neutron radiation from an Improvised Nuclear Device (IND) at relevant distances (e.g. 1.5 km) from the epicenter. The neutron spectrum of this IND-like neutron irradiator was designed according to estimations of the Hiroshima neutron spectrum at 1.5 km. It is significantly different from a standard reactor fission spectrum, because the spectrum changes as the neutrons are transported through air, and it is dominated by neutron energies from 100 keV up to 9 MeV. To verify such wide energy range neutron spectrum, detailed here is the development of a combined spectroscopy system. Both a liquid scintillator detector and a gas proportional counter were used for the recoil spectra measurements, with the individual response functions estimated from a series of Monte Carlo simulations. These normalized individual response functions were formed into a single response matrix for the unfolding process. Several accelerator-based quasi-monoenergetic neutron source spectra were measured and unfolded to test this spectroscopy system. These reference neutrons were produced from two reactions: T(p,n)3He and D(d,n)3He, generating neutron energies in the range between 0.2 and 8 MeV. The unfolded quasi-monoenergetic neutron spectra indicated that the detection system can provide good neutron spectroscopy results in this energy range. A broad-energy neutron spectrum from the 9Be(d,n) reaction using a 5 MeV deuteron beam, measured at 60 degrees to the incident beam was measured and unfolded with the evaluated response matrix. The unfolded broad neutron spectrum is comparable with published time-of-flight results. Finally, the pair of detectors were used to measure the neutron spectrum generated at the RARAF IND-like neutron facility and a comparison is made to the neutron spectrum of Hiroshima. PMID:26273118

  20. Fast neutron fluence of yonggwang nuclear unit 1 reactor pressure vessel

    SciTech Connect

    Yoo, C.; Km, B.; Chang, K.; Leeand, S.; Park, J.

    2006-07-01

    The Code of Federal Regulations, Title 10, Part 50, Appendix H, requires that the neutron dosimetry be present to monitor the reactor vessel throughout plant life. The Ex-Vessel Neutron Dosimetry System has been installed for Yonggwang Nuclear Unit 1 after complete withdrawal of all six in-vessel surveillance capsules. This system has been installed in the reactor cavity annulus in order to measure the fast neutron spectrum coming out through the reactor pressure vessel. Cycle specific neutron transport calculations were performed to obtain the energy dependent neutron flux throughout the reactor geometry including dosimetry positions. Comparisons between calculations and measurements were performed for the reaction rates of each dosimetry sensors and results show good agreements. (authors)

  1. Bright Flash Neutron Radiography at the McClellan Nuclear Research Reactor

    NASA Astrophysics Data System (ADS)

    Lerche, M.; Tremsin, A. S.; Schillinger, B.

    The University of California, Davis McClellan Nuclear Research Center (MNRC) operates a 2 MW TRIGATM reactor, which is currently the highest power TRIGATM reactor in the United States. The Center was originally build by the US Air Force to detect hidden defects in aircraft structures using neutron radiography; the Center can accommodate samples as large as 10.00 m long, 3.65 m high, and weighing up to 2,270 kg. The MNRC reactor can be pulsed to 350 MW for about 30 ms (FWHM). The combination of a short neutron pulse with a fast microchannel plate based neutron detector enables high-resolution flash neutron radiography to complement conventional neutron radiography

  2. New nuclear safe plutonium ceramic compositions with neutron poisons for plutonium storage

    NASA Astrophysics Data System (ADS)

    Nadykto, B. A.; Timofeeva, L. F.

    2000-07-01

    A complex of works is conducted to study the possibility of reprocessing surplus weapon-grade plutonium to a critical-mass-free composition with neutron poison. Nuclear safe ceramic compositions of PuO2 with four most efficient neutron poisons, Hf, Gd, Li, and B, are fabricated in the laboratory. Various methods for fabrication of the compositions with PuO2 depending on neutron poison element are used and studied: a — by sintering initial component powders; b — by impregnation of a porous skeleton made of neutron poison oxide with plutonium sol-gel; c — by sintering microspheres made of plutonium oxide with neutron poison (B4C), with the microspheres having a coating completely absorbing alpha particles.

  3. Dose estimations of fast neutrons from a nuclear reactor by micronuclear yields in onion seedlings.

    PubMed

    Fujikawa, K; Endo, S; Itoh, T; Yonezawa, Y; Hoshi, M

    1999-12-01

    Irradiations of onion seedlings with fission neutrons from bare, Pb-moderated, and Fe-moderated 252Cf sources induced micronuclei in the root-tip cells at similar rates. The rate per cGy averaged for the three sources, , was 19 times higher than rate induced by 60Co gamma-rays. When neutron doses, Dn, were estimated from frequencies of micronuclei induced in onion seedlings after exposure to neutron-gamma mixed radiation from a 1 W nuclear reactor, using the reciprocal of as conversion factor, resulting Dn values agreed within 10% with doses measured with paired ionizing chambers. This excellent agreement was achieved by the high sensitivity of the onion system to fast neutrons relative to gamma-rays and the high contribution of fast neutrons to the total dose of mixed radiation in the reactor's field.

  4. Deciphering the role of nuclear and cytoplasmic IKKα in skin cancer

    PubMed Central

    Alameda, Josefa P.; Gaspar, Miriam; Ramírez, Ángel; Navarro, Manuel; Page, Angustias; Suárez-Cabrera, Cristian; Fernández, M. Guadalupe; Mérida, Jose R.; Paramio, Jesús M.; García-Fernández, Rosa A.; Fernández-Aceñero, M. Jesús; Casanova, M. Llanos

    2016-01-01

    Nonmelanoma skin cancers (NMSC) are the most common human malignancies. IKKα is an essential protein for skin development and is also involved in the genesis and progression of NMSC, through mechanisms not fully understood. While different studies show that IKKα protects against skin cancer, others indicate that it promotes NMSC. To resolve this controversy we have generated two models of transgenic mice expressing the IKKα protein in the nucleus (N-IKKα mice) or the cytoplasm (C-IKKα mice) of keratinocytes. Chemical skin carcinogenesis experiments show that tumors developed by both types of transgenic mice exhibit histological and molecular characteristics that make them more prone to progression and invasion than those developed by Control mice. However, the mechanisms through which IKKα promotes skin tumors are different depending on its subcellular localization; while IKKα of cytoplasmic localization increases EGFR, MMP-9 and VEGF-A activities in tumors, nuclear IKKα causes tumor progression through regulation of c-Myc, Maspin and Integrin-α6 expression. Additionally, we have found that N-IKKα skin tumors mimic the characteristics associated to aggressive human skin tumors with high risk to metastasize. Our results show that IKKα has different non-overlapping roles in the nucleus or cytoplasm of keratinocytes, and provide new targets for intervention in human NMSC progression. PMID:27121058

  5. Nuclear Data Needs for the Neutronic Design of MYRRHA Fast Spectrum Research Reactor

    NASA Astrophysics Data System (ADS)

    Stankovskiy, A.; Malambu, E.; Van den Eynde, G.; Díez, C. J.

    2014-04-01

    A global sensitivity analysis of effective neutron multiplication factor to the change of nuclear data library has been performed. It revealed that the test version of JEFF-3.2 neutron-induced evaluated data library produces closer results to ENDF/B-VII.1 than JEFF-3.1.2 does. The analysis of contributions of individual evaluations into keff sensitivity resulted in the priority list of nuclides, uncertainties on cross sections and fission neutron multiplicities of which have to be improved by setting up dedicated differential and integral experiments.

  6. Description and evaluation of nuclear masses based on residual proton-neutron interactions

    SciTech Connect

    Fu, G. J.; Lei, Y.; Jiang, H.; Zhao, Y. M.; Sun, B.; Arima, A.

    2011-09-15

    In this paper we study the residual proton-neutron interactions and make use of the systematics of these interactions to describe experimental data of nuclear masses and to predict some of the unknown masses. The odd-even effect staggering of the residual proton-neutron interaction between the last proton and the last neutron is found and argued in terms of pairing interactions. Two local mass relations, which work very accurately for masses of four neighboring nuclei, are discovered. The accuracy of our predicted masses for medium and heavy nuclei is competitive with that of the AME2003 extrapolations, with the virtue of simplicity.

  7. Results on the neutron energy distribution measurements at the RECH-1 Chilean nuclear reactor

    NASA Astrophysics Data System (ADS)

    Aguilera, P.; Molina, F.; Romero-Barrientos, J.

    2016-07-01

    Neutron activations experiments has been perform at the RECH-1 Chilean Nuclear Reactor to measure its neutron flux energy distribution. Samples of pure elements was activated to obtain the saturation activities for each reaction. Using - ray spectroscopy we identify and measure the activity of the reaction product nuclei, obtaining the saturation activities of 20 reactions. GEANT4 and MCNP was used to compute the self shielding factor to correct the cross section for each element. With the Expectation-Maximization algorithm (EM) we were able to unfold the neutron flux energy distribution at dry tube position, near the RECH-1 core. In this work, we present the unfolding results using the EM algorithm.

  8. Preparation and characterisation of thin film nuclear targets for neutron physical measurements

    NASA Astrophysics Data System (ADS)

    Sapundjiev, D.; Dean, A.; Jacobsson, U.; Luyckx, K.; Moens, A.; Sibbens, G.; Eykens, R.; Aregbe, Y.

    2012-09-01

    In the target preparation laboratory of the Institute for Reference Materials and Measurements, lithium fluoride, boron, and tristearin thin films are produced by physical vapour deposition for neutron spectroscopy experiments and for neutron cross-section measurements. In all of these applications the accuracy of the obtained measurements greatly depends on the properties of the deposited films and the characterisation of the areal density. In this work we describe the production of various nuclear targets. The characterisation methods depend on the nature of the particular film/substrate system. Different characterisation techniques and the uncertainties in the determined areal densities necessary for neutron physical calculations are presented and compared.

  9. Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux

    DOEpatents

    Bowman, Charles D.

    1992-01-01

    Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

  10. Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux

    DOEpatents

    Bowman, C.D.

    1992-11-03

    Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

  11. Detection of previous neutron irradiation and reprocessing of uranium materials for nuclear forensic purposes.

    PubMed

    Varga, Zsolt; Surányi, Gergely

    2009-04-01

    The paper describes novel analytical methods developed for the detection of previous neutron irradiation and reprocessing of illicit nuclear materials, which is an important characteristic of nuclear materials of unknown origin in nuclear forensics. Alpha spectrometry and inductively coupled plasma sector-field mass spectrometry (ICP-SFMS) using solution nebulization and direct, quasi-non-destructive laser ablation as sample introduction were applied for the measurement of trace-level (232)U, (236)U and plutonium isotopes deriving from previous neutron irradiation of uranium-containing nuclear materials. The measured radionuclides and isotope ratios give important information on the raw material used for fuel production and enable confirm the supposed provenance of illicit nuclear material. PMID:19179085

  12. Intrinsic neutron background of nuclear emulsions for directional Dark Matter searches

    NASA Astrophysics Data System (ADS)

    Alexandrov, A.; Asada, T.; Buonaura, A.; Consiglio, L.; D'Ambrosio, N.; De Lellis, G.; Di Crescenzo, A.; Di Marco, N.; Di Vacri, M. L.; Furuya, S.; Galati, G.; Gentile, V.; Katsuragawa, T.; Laubenstein, M.; Lauria, A.; Loverre, P. F.; Machii, S.; Monacelli, P.; Montesi, M. C.; Naka, T.; Pupilli, F.; Rosa, G.; Sato, O.; Strolin, P.; Tioukov, V.; Umemoto, A.; Yoshimoto, M.

    2016-07-01

    Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark Matter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the neutron-induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.06 per year per kilogram, fully compatible with the design of a 10 kg × year exposure.

  13. Intrinsic neutron background of nuclear emulsions for directional Dark Matter searches

    NASA Astrophysics Data System (ADS)

    Alexandrov, A.; Asada, T.; Buonaura, A.; Consiglio, L.; D'Ambrosio, N.; De Lellis, G.; Di Crescenzo, A.; Di Marco, N.; Di Vacri, M. L.; Furuya, S.; Galati, G.; Gentile, V.; Katsuragawa, T.; Laubenstein, M.; Lauria, A.; Loverre, P. F.; Machii, S.; Monacelli, P.; Montesi, M. C.; Naka, T.; Pupilli, F.; Rosa, G.; Sato, O.; Strolin, P.; Tioukov, V.; Umemoto, A.; Yoshimoto, M.

    2016-07-01

    Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark Matter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the neutron-induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.06 per year per kilogram, fully compatible with the design of a 10 kg × year exposure.

  14. Recent Fast Neutron Imaging Measurements with the Fieldable Nuclear Materials Identification System

    SciTech Connect

    Mullens, James Allen; Mihalczo, John T; Archer, Daniel E; Thompson, Thad; Britton Jr, Charles L; Ezell, N Dianne Bull; Ericson, Milton Nance; Farquhar, Ethan; Lind, Randall F; Carter, Jake

    2015-01-01

    This paper describes some recent fast neutron imaging measurements of the fieldable nuclear materials identification system (FNMIS) under development by the National Nuclear Security Administration (NNSA-NA-22) for possible future use in arms control and nonproliferation applications. The general configuration of FNMIS has been previously described, and a description of the application-specific integrated circuit (ASIC) electronics designed for FNMIS has been reported. This paper presents initial imaging measurements performed at ORNL with a Thermo Fisher API 120 DT generator and the fast-neutron imaging module of FNMIS.

  15. Neutron dosimetry at commercial nuclear plants. Final report of Subtask B: dosimeter response

    SciTech Connect

    Cummings, F.M.; Endres, G.W.R.; Brackenbush, L.W.

    1983-03-01

    As part of a larger program to evaluate personnel neutron dosimetry at commercial nuclear power plants, this study was designed to characterize neutron dosimeter responses inside the containment structure of commercial nuclear plants. In order to characterize those responses, dosimeters were irradiated inside containment at 2 pressurized water reactors and at pipe penetrations outside the biological shield at two boiling water reactors. The reactors were operating at full power during the irradiations. Measurements were also performed with electronic instruments, the tissue equivalent proportional counter (TEPC), and portable remmeters, SNOOPY, RASCAL and PNR-4.

  16. Contribution of Neutron Beta Decay to Radiation Belt Pumping from High Altitude Nuclear Explosion

    SciTech Connect

    Marrs, R

    2002-11-13

    In 1962, several satellites were lost following high altitude nuclear tests by the United States and the Soviet Union. These satellite failures were caused by energetic electrons injected into the earth's radiation belts from the beta decay of bomb produced fission fragments and neutrons. It has been 40 years since the last high altitude nuclear test; there are now many more satellites in orbit, and it is important to understand their vulnerability to radiation belt pumping from nuclear explosions at high altitude or in space. This report presents the results of a calculation of the contribution of neutron beta decay to artificial belt pumping. For most high altitude nuclear explosions, neutrons are expected to make a smaller contribution than fission products to the total trapped electron inventory, and their contribution is usually neglected. However, the neutron contribution may dominate in cases where the fission product contribution is suppressed due to the altitude or geomagnetic latitude of the nuclear explosion, and for regions of the radiation belts with field lines far from the detonation point. In any case, an accurate model of belt pumping from high altitude nuclear explosions, and a self-consistent explanation of the 1962 data, require inclusion of the neutron contribution. One recent analysis of satellite measurements of electron flux from the 1962 tests found that a better fit to the data is obtained if the neutron contribution to the trapped electron inventory was larger than that of the fission products [l]. Belt pumping from high altitude nuclear explosions is a complicated process. Fission fragments are dispersed as part of the ionized bomb debris, which is constrained and guided by the earth's magnetic field. Those fission products that beta decay before being lost to the earth's atmosphere can contribute trapped energetic electrons to the earth's radiation belts. There has been a large effort to develop computer models for the contribution of

  17. Nuclear data requirements for fission reactor neutronics calculations.

    SciTech Connect

    Finck, P.

    1998-06-29

    The paper discusses current European nuclear data measurement and evaluation requirements for fission reactor technology applications and problems involved in meeting the requirements. Reference is made to the NEA High Priority Nuclear Data Request List and to the production of the new JEFF-3 library of evaluated nuclear data. There are requirements for both differential (or basic) nuclear data measurements and for different types of integral measurement critical facility measurements and isotopic sample irradiation measurements. Cross-section adjustment procedures are being used to take into account the simpler types of integral measurement, and to define accuracy needs for evaluated nuclear data.

  18. Compact Short-Pulsed Electron Linac Based Neutron Sources for Precise Nuclear Material Analysis

    NASA Astrophysics Data System (ADS)

    Uesaka, M.; Tagi, K.; Matsuyama, D.; Fujiwara, T.; Dobashi, K.; Yamamoto, M.; Harada, H.

    2015-10-01

    An X-band (11.424GHz) electron linac as a neutron source for nuclear data study for the melted fuel debris analysis and nuclear security in Fukushima is under development. Originally we developed the linac for Compton scattering X-ray source. Quantitative material analysis and forensics for nuclear security will start several years later after the safe settlement of the accident is established. For the purpose, we should now accumulate more precise nuclear data of U, Pu, etc., especially in epithermal (0.1-10 eV) neutrons. Therefore, we have decided to modify and install the linac in the core space of the experimental nuclear reactor "Yayoi" which is now under the decommission procedure. Due to the compactness of the X-band linac, an electron gun, accelerating tube and other components can be installed in a small space in the core. First we plan to perform the time-of-flight (TOF) transmission measurement for study of total cross sections of the nuclei for 0.1-10 eV energy neutrons. Therefore, if we adopt a TOF line of less than 10m, the o-pulse length of generated neutrons should be shorter than 100 ns. Electronenergy, o-pulse length, power, and neutron yield are ~30 MeV, 100 ns - 1 micros, ~0.4 kW, and ~1011 n/s (~103 n/cm2/s at samples), respectively. Optimization of the design of a neutron target (Ta, W, 238U), TOF line and neutron detector (Ce:LiCAF) of high sensitivity and fast response is underway. We are upgrading the electron gun and a buncher to realize higher current and beam power with a reasonable beam size in order to avoid damage of the neutron target. Although the neutron flux is limited in case of the X-band electron linac based source, we take advantage of its short pulse aspect and availability for nuclear data measurement with a short TOF system. First, we form a tentative configuration in the current experimental room for Compton scattering in 2014. Then, after the decommissioning has been finished, we move it to the "Yayoi" room and perform

  19. Neutron multiplicities in spontaneous fission and nuclear structure studies

    SciTech Connect

    Hamilton, J.H.; Kormicki, J.; Lu, Q.

    1993-12-31

    New insights into the fission process can be gained by better quantitative knowledge of how the energy released in fission is distributed between the kinetic energy of the two fragments, the excitation energy of the two fragments and the number of neutrons emitted. Studies of prompt gamma-rays emitted in spontaneous fission (SF) with large arrays of Compton suppressed Ge detector arrays are providing new quantitative answers to longstanding questions concerning fission as well as new insights into the structure of neutron-rich nuclei. For the first time the triple gamma coincidence technique was employed in spontaneous fission studies. Studies of SF of {sup 252}Cf and {sup 242}Pu have been carried out. These {gamma}-{gamma}-{gamma} data provide powerful ways to identify uniquely gamma rays from a particular nucleus in the very complex gamma-ray spectra given off by the over 100 different nuclei produced. The emphasis of this paper is on the first quantitative measurements of the multiplicities of the neutrons emitted in SF and the energy levels populated in the fragments. Indeed, in the break up into Mo-Ba pairs, we have identified for the first time fragments associated with from zero up to ten neutrons emitted and observed the excited energy states populated in these nuclei. The zero neutron emission pairs like {sup 104}Mo- {sup 148}Ba, {sup 106}Mo- {sup 146}Ba and {sup 104}Zr- {sup 148}Ce observed in this work are particularly interesting because they represent a type of cold fission or a new mode of cluster radioactivity as proposed by Greiner, Sandulescu and co-workers. These data provide new insights into the processes of cluster radioactivity and cold fission.

  20. APSTNG: neutron interrogation for detection of explosives, drugs, and nuclear and chemical warfare materials

    NASA Astrophysics Data System (ADS)

    Rhodes, Edgar A.; Peters, Charles W.

    1993-02-01

    A recently developed neutron diagnostic probe system has the potential to satisfy a significant number of van-mobile and fixed-portal requirements for nondestructive detection, including monitoring of contraband explosives, drugs, and weapon materials, and treaty verification of sealed munitions. The probe is based on a unique associated-particle sealed-tube neutron generator (APSTNG) that interrogates the object of interest with a low-intensity beam of 14- MeV neutrons generated from the deuterium-tritium reaction and that detects the alpha-particle associated with each neutron. Gamma-ray spectra of resulting neutron reactions identify nuclides associated with all major chemicals in explosives, drugs, and chemical warfare agents, as well as many pollutants and fissile and fertile special nuclear material. Flight times determined from detection times of the gamma-rays and alpha-particles yield a separate coarse tomographic image of each identified nuclide. The APSTNG also forms the basis for a compact fast-neutron transmission imaging system that can be used along with or instead of the emission imaging system. Proof-of-concept experiments have been performed under laboratory conditions for simulated nuclear and chemical warfare munitions and for explosives and drugs. The small and relatively inexpensive APSTNG exhibits high reliability and can be quickly replaced. Surveillance systems based on APSTNG technology can avoid the large physical size, high capital and operating expenses, and reliability problems associated with complex accelerators.

  1. Determination of nuclear fuel burn-up axial profile by neutron emission measurement

    NASA Astrophysics Data System (ADS)

    Prokopowicz, Rafal; Pytel, Krzysztof

    2016-12-01

    Burning-up of nuclear fuel is usually not a space-isotropic phenomenon. It depends on both the neutron flux density and energy spectrum distribution during fuel operation in a nuclear reactor. This paper presents the method of measurement of burn-up spatial distribution of spent nuclear fuel element. The method is based on recording of the neutron emission from investigated fuel element. Based on performed analyses and calculations, a suitable measuring setup has been designed and constructed. The subjects of investigation were fuel elements used in the MARIA research reactor, operated by National Centre for Nuclear Research in Świerk, Poland. The results of measurements made over a period of several years by means of the described method are presented in the paper.

  2. Irradiation of nuclear track emulsions with thermal neutrons, heavy ions, and muons

    SciTech Connect

    Artemenkov, D. A. Bradnova, V.; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.; Kattabekov, R. R.; Mamatkulov, K. Z.; Rusakova, V. V.

    2015-07-15

    Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n{sub th} +{sup 10} B → {sup 7} Li + (γ)+ α were studied in nuclear track emulsions enriched in boron. Nuclear track emulsions were also irradiated with {sup 86}Kr{sup +17} and {sup 124}Xe{sup +26} ions of energy about 1.2 MeV per nucleon. Measurements of ranges of heavy ions in nuclear track emulsionsmade it possible to determine their energies on the basis of the SRIM model. The formation of high-multiplicity nuclear stars was observed upon irradiating nuclear track emulsions with ultrarelativistic muons. Kinematical features studied in this exposure of nuclear track emulsions for events of the muon-induced splitting of carbon nuclei to three alpha particles are indicative of the nucleardiffraction interaction mechanism.

  3. Modeled Neutron Induced Nuclear Reaction Cross Sections for Radiochemistry in the region of Iriduim and Gold

    SciTech Connect

    Hoffman, R D; Dietrich, F S; Kelley, K; Escher, J; Bauer, R; Mustafa, M

    2008-02-26

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for targets ranging from osmium (Z = 76) to gold (Z = 79). Of particular interest are the cross sections on Ir and Au including reactions on isomeric targets.

  4. Neutron angular distribution in a plasma focus obtained using nuclear track detectors.

    PubMed

    Castillo-Mejía, F; Herrera, J J E; Rangel, J; Golzarri, J I; Espinosa, G

    2002-01-01

    The dense plasma focus (DPF) is a coaxial plasma gun in which a high-density, high-temperature plasma is obtained in a focused column for a few nanoseconds. When the filling gas is deuterium, neutrons can be obtained from fusion reactions. These are partially due to a beam of deuterons which are accelerated against the background hot plasma by large electric fields originating from plasma instabilities. Due to a beam-target effect, the angular distribution of the neutron emission is anisotropic, peaked in the forward direction along the axis of the gun. The purpose of this work is to illustrate the use of CR-39 nuclear track detectors as a diagnostic tool in the determination of the time-integrated neutron angular distribution. For the case studied in this work, neutron emission is found to have a 70% contribution from isotropic radiation and a 30% contribution from anisotropic radiation.

  5. Nuclear research emulsion neutron spectrometry at the Little-Boy replica

    SciTech Connect

    Gold, R.; Roberts, J.H.; Preston, C.C.

    1985-10-01

    Nuclear research emulsions (NRE) have been used to characterize the neutron spectrum emitted by the Little-Boy replica. NRE were irradiated at the Little-Boy surface as well as approximately 2 m from the center of the Little-Boy replica using polar angles of 0/sup 0/, 30/sup 0/, 60/sup 0/ and 90/sup 0/. For the NRE exposed at 2 m, neutron background was determined using shadow shields of borated polyethylene. Emulsion scanning to date has concentrated exclusively on the 2-m, 0/sup 0/ and 2-m, 90/sup 0/ locations. Approximately 5000 proton-recoil tracks have been measured in NRE irradiated at each of these locations. Neutron spectra obtained from these NRE proton-recoil spectra are compared with both liquid scintillator neutron spectrometry and Monte Carlo calculations. NRE and liquid scintillator neutron spectra generally agree within experimental uncertainties at the 2-m, 90/sup 0/ location. However, at the 2-m, 0/sup 0/ location, the neutron spectra derived from these two independent experimental methods differ significantly. NRE spectra and Monte Carlo calculations exhibit general agreement with regard to both intensity as well as energy dependence. Better agreement is attained between theory and experiment at the 2-m, 90/sup 0/ location, where the neutron intensity is considerably higher. 14 refs., 18 figs., 11 tabs.

  6. Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

    NASA Astrophysics Data System (ADS)

    Silva, Hector O.; Sotani, Hajime; Berti, Emanuele

    2016-07-01

    The lowest neutron star masses currently measured are in the range 1.0-1.1 M⊙, but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass M/M⊙ = 1.174 ± 0.004 (Martinez et al. 2015) in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al. recently found empirical formulas relating the mass and surface redshift of non-rotating neutron stars to the star's central density and to the parameter η ≡ (K0L2)1/3, where K0 is the incompressibility of symmetric nuclear matter and L is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al. to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotational Love number and apsidal constant of slowly rotating neutron stars by integrating the Hartle-Thorne equations at second order in rotation, and we fit all of these quantities as functions of η and of the central density. These fits may be used to constrain η, either via observations of binary pulsars in the electromagnetic spectrum, or via near-future observations of inspiralling compact binaries in the gravitational-wave spectrum.

  7. Novel Al2O3:C,Mg fluorescent nuclear track detectors for passive neutron dosimetry.

    PubMed

    Sykora, G Jeff; Akselrod, Mark S; Salasky, M; Marino, Stephen A

    2007-01-01

    The latest advances in the development of a fluorescent nuclear track detector (FNTD) for neutron and heavy charged particle dosimetry are described and compared with CR-39 plastic nuclear etched track detectors (PNTDs). The technique combines a new luminescent aluminium oxide single crystal detector (Al(2)O(3):C,Mg) with an imaging technique based on laser scanning and confocal fluorescence detection. Detection efficiency was obtained after irradiations with monoenergetic neutron and proton beams. Dose dependences were measured for different configurations of the detectors exposed in fast- and thermal-neutron fields. A specially developed image processing technique allows for fast fluorescent track identification and counting. The readout method is non-destructive, and detectors can be reused after thermal annealing. PMID:17522030

  8. Neutron nuclear data evaluation of actinide nuclei for CENDL-3.1

    NASA Astrophysics Data System (ADS)

    Chen, Guo-Chang; Cao, Wen-Tian; Yu, Bao-Sheng; Tang, Guo-You; Shi, Zhao-Min; Tao, Xi

    2012-09-01

    New evaluations for several actinide nuclei of the third version of Chinese Evaluated Nuclear Data Library for Neutron Reaction Data (CENDL-3.1) have been completed and released. The evaluation is for all neutron induced reactions with uranium, neptunium, plutonium and americium in the mass range A = 232-241, 236-239, 236-246 and 240-244, respectively, and cover the incident neutron energy up to 20 MeV. In the present evaluation, much more effort was devoted to improving the reliability of the evaluated nuclear data for available new measured data, especially scarce or absent experimental data. A general description for the evaluation of several actinides' data is presented.

  9. Gamma and neutron detection modeling in the nuclear detection figure of merit (NDFOM) portal

    SciTech Connect

    Stroud, Phillip D; Saeger, Kevin J

    2009-01-01

    The Nuclear Detection Figure Of Merit (NDFOM) portal is a database of objects and algorithms for evaluating the performance of radiation detectors to detect nuclear material. This paper describes the algorithms used to model the physics and mathematics of radiation detection. As a first-principles end-to-end analysis system, it starts with the representation of the gamma and neutron spectral fluxes, which are computed with the particle and radiation transport code MCNPX. The gamma spectra emitted by uranium, plutonium, and several other materials of interest are described. The impact of shielding and other intervening material is computed by the method of build-up factors. The interaction of radiation with the detector material is computed by a detector response function approach. The construction of detector response function matrices based on MCNPX simulation runs is described in detail. Neutron fluxes are represented in a three group formulation to treat differences in detector sensitivities to thermal, epithermal, and fast neutrons.

  10. Tokamak D T fusion neutron source requirements for closing the nuclear fuel cycle

    NASA Astrophysics Data System (ADS)

    Stacey, W. M.

    2007-03-01

    This paper summarizes a series of conceptual design studies conducted with the purpose of determining if tokamak fusion neutron sources based on ITER physics and technology could meet the neutron source requirements for sub-critical fast-spectrum nuclear reactors that would help to close the nuclear fuel cycle by transmuting the transuranics in spent nuclear fuel. The studies were constrained to nuclear reactor and materials technologies under consideration in the US nuclear programme. Fuel cycle studies indicate that fusion neutron sources in the range ~200-500 MW would meet the needs of transmutation reactors, depending on other constraints such as materials damage to the nuclear fuel. A tokamak with R = 3.75 m, a = 1.1 m, B = 5.7-5.9 T, q95 = 3.00-4.0, I = 8.3-10 MA, βN = 2.0-2.85, HIPB98 = 1.0-1.06, γcd = 0.6 A Wm-2 would meet these requirements.

  11. A NEW METHOD FOR EXTRACTING SPIN-DEPENDENT NEUTRON STRUCTURE FUNCTIONS FROM NUCLEAR DATA

    SciTech Connect

    Kahn, Y.F.; Melnitchouk, W.

    2009-01-01

    High-energy electrons are currently the best probes of the internal structure of nucleons (protons and neutrons). By collecting data on electrons scattering off light nuclei, such as deuterium and helium, one can extract structure functions (SFs), which encode information about the quarks that make up the nucleon. Spin-dependent SFs, which depend on the relative polarization of the electron beam and the target nucleus, encode quark spins. Proton SFs can be measured directly from electron-proton scattering, but those of the neutron must be extracted from proton data and deuterium or helium-3 data because free neutron targets do not exist. At present, there is no reliable method for accurately determining spin-dependent neutron SFs in the low-momentum-transfer regime, where nucleon resonances are prominent and the functions are not smooth. The focus of this study was to develop a new method for extracting spin-dependent neutron SFs from nuclear data. An approximate convolution formula for nuclear SFs reduces the problem to an integral equation, for which a recursive solution method was designed. The method was then applied to recent data from proton and deuterium scattering experiments to perform a preliminary extraction of spin-dependent neutron SFs in the resonance region. The extraction method was found to reliably converge for arbitrary test functions, and the validity of the extraction from data was verifi ed using a Bjorken integral, which relates integrals of SFs to a known quantity. This new information on neutron structure could be used to assess quark-hadron duality for the neutron, which requires detailed knowledge of SFs in all kinematic regimes.

  12. Note: Fast neutron efficiency in CR-39 nuclear track detectors

    SciTech Connect

    Cavallaro, S.

    2015-03-15

    CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed.

  13. Note: fast neutron efficiency in CR-39 nuclear track detectors.

    PubMed

    Cavallaro, S

    2015-03-01

    CR-39 samples are commonly employed for fast neutron detection in fusion reactors and in inertial confinement fusion experiments. The literature reported efficiencies are strongly depending on experimental conditions and, in some cases, highly dispersed. The present note analyses the dependence of efficiency as a function of various parameters and experimental conditions in both the radiator-assisted and the stand-alone CR-39 configurations. Comparisons of literature experimental data with Monte Carlo calculations and optimized efficiency values are shown and discussed.

  14. Nuclear fission of neutron-deficient protactinium nuclides

    SciTech Connect

    Nishinaka, I.; Nagame, Y.; Tsukada, K.; Ikezoe, H.; Sueki, K.; Nakahara, H.; Tanikawa, M.; Ohtsuki, T.

    1997-08-01

    Fragment velocity, kinetic energy, mass yield, and element yield distributions in the fission of neutron-deficient Pa isotopes produced in the reactions of {sup 16}O and {sup 18}O on {sup 209}Bi have been measured at incident beam energies near and above the Coulomb barriers by the time-of-flight and radiochemical methods. An asymmetric mass-division component has been observed. Measured fission cross sections were compared with the results of statistical model calculations which take into account two fission barrier heights for symmetric and asymmetric yields. The fission barrier height deduced for the asymmetric fission is found slightly lower than that for the symmetric one. The difference between the two barrier heights in the fission of the present protactinium nuclides (N{approximately}135) is considerably smaller than that in the neutron-rich nuclide of {sup 233}Pa (N{approximately}142), indicating that the difference sensitively depends on the neutron number of the fissioning nuclide. {copyright} {ital 1997} {ital The American Physical Society}

  15. Neutron scattering and models: Iron. Nuclear data and measurements series

    SciTech Connect

    Smith, A.B.

    1995-08-01

    Differential elastic and inelastic neutron-scattering cross sections of elemental iron are measured from 4.5 to 10 MeV in increments of {approx} 0.5 MeV. At each incident energy the measurements are made at forty or more scattering angles distributed between {approx} 17{degrees} and 160{degrees}, with emphasis on elastic scattering and inelastic scattering due to the excitation of the yrast 2{sup +} state. The measured data is combined with earlier lower-energy results from this laboratory, with recent high-precision {approx} 9.5 {yields} 15 MeV results from the Physilalisch Technische Bundesanstalt and with selected values from the literature to provide a detailed neutron-scattering data base extending from {approx} 1.5 to 26 MeV. This data is interpreted in the context of phenomenological spherical-optical and coupled-channels (vibrational and rotational) models, and physical implications discussed. Deformation, coupling, asymmetry and dispersive effects are explored. It is shown that, particularly in a collective context, a good description of the interaction of neutrons with iron is achieved over the energy range {approx} 0 {yields} 26 MeV, avoiding the dichotomy between high and low-energy interpretations found in previous work.

  16. Advanced neutron irradiation system using Texas A&M University Nuclear Science Center Reactor

    NASA Astrophysics Data System (ADS)

    Jang, Si Young

    A heavily filtered fast neutron irradiation system (FNIS) was developed for a variety of applications, including the study of long-term health effects of fast neutrons by evaluating the biological mechanisms of damage in cultured cells and living animals such as rats or mice. This irradiation system includes an exposure cave made with a lead-bismuth alloy, a cave positioning system, a gamma and neutron monitoring system, a sample transfer system, and interchangeable filters. This system was installed in the irradiation cell of the Texas A&M University Nuclear Science Center Reactor (NSCR). By increasing the thickness of the lead-bismuth alloy, the neutron spectra were shifted into lower energies by the scattering interactions of fast neutrons with the alloy. It is possible, therefore, by changing the alloy thickness, to produce distinctly different dose weighted neutron spectra inside the exposure cave of the FNIS. The calculated neutron spectra showed close agreement with the results of activation foil measurements, unfolded by SAND-II close to the cell window. However, there was a considerable less agreement for locations far away from the cell window. Even though the magnitude of values such as neutron flux and tissue kerma rates in air differed, the weighted average neutron energies showed close agreement between the MCNP and SAND-II since the normalized neutron spectra were in a good agreement each other. A paired ion chamber system was constructed, one with a tissue equivalent plastic (A-150) and propane gas for total dose monitoring, and another with graphite and argon for photon dose monitoring. Using the pair of detectors, the neutron to gamma ratio can be inferred. With the 20 cm-thick FNIS, the absorbed dose rates of neutrons measured with the paired ion chamber method and calculated with the SAND-II results were 13.7 +/- 0.02 Gy/min and 15.5 Gy/min, respectively. The absorbed dose rate of photons and the gamma contribution to total dose were 6.7 x 10

  17. Nuclear factor erythroid 2-related factor gene variants and susceptibility of arsenic-related skin lesions.

    PubMed

    Cordova, E J; Valenzuela, O L; Sánchez-Peña, L C; Escamilla-Guerrero, G; Hernández-Zavala, A; Orozco, L; Del Razo, L M

    2014-06-01

    Inorganic arsenic (iAs) is an important pollutant associated with various chronic-degenerative diseases. The cytoprotective protein nuclear factor erythroid 2-related factor (NRF2) has been proposed as an important responsive mechanism against iAs exposure. The aim of this study was to determine whether the risk of skin lesions in people exposed to iAs-contaminated water could be modified by the presence of single nucleotide polymorphisms in the NRF2 coding gene. We studied 117 individuals with long-term iAs exposure and 120 nonexposed individuals. Total As was determined in water, meanwhile iAs and its metabolites were measured in urine. The iAs-induced skin lesion status was evaluated by expert dermatologists. We sequenced the promoter region of NRF2 in a sample of 120 healthy donors. We found four polymorphisms previously reported and one novel polymorphism in the 5' regulatory region of the NRF2. In this study, we did not find allelic and genotype association of NRF2 polymorphisms with iAs-related skin lesion. However, the analysis of haplotypes composed by -653GA, and -617CA NRF2 single nucleotide polymorphisms showed a significant association with protection against skin lesions in the low-As exposure group. This is the first report studying the association between NRF2 polymorphisms and susceptibility of As-related skin lesions. Increasing the sample size will allow us to confirm this data. PMID:24107458

  18. Nuclear factor erythroid 2-related factor gene variants and susceptibility of arsenic-related skin lesions.

    PubMed

    Cordova, E J; Valenzuela, O L; Sánchez-Peña, L C; Escamilla-Guerrero, G; Hernández-Zavala, A; Orozco, L; Del Razo, L M

    2014-06-01

    Inorganic arsenic (iAs) is an important pollutant associated with various chronic-degenerative diseases. The cytoprotective protein nuclear factor erythroid 2-related factor (NRF2) has been proposed as an important responsive mechanism against iAs exposure. The aim of this study was to determine whether the risk of skin lesions in people exposed to iAs-contaminated water could be modified by the presence of single nucleotide polymorphisms in the NRF2 coding gene. We studied 117 individuals with long-term iAs exposure and 120 nonexposed individuals. Total As was determined in water, meanwhile iAs and its metabolites were measured in urine. The iAs-induced skin lesion status was evaluated by expert dermatologists. We sequenced the promoter region of NRF2 in a sample of 120 healthy donors. We found four polymorphisms previously reported and one novel polymorphism in the 5' regulatory region of the NRF2. In this study, we did not find allelic and genotype association of NRF2 polymorphisms with iAs-related skin lesion. However, the analysis of haplotypes composed by -653GA, and -617CA NRF2 single nucleotide polymorphisms showed a significant association with protection against skin lesions in the low-As exposure group. This is the first report studying the association between NRF2 polymorphisms and susceptibility of As-related skin lesions. Increasing the sample size will allow us to confirm this data.

  19. Measurement of leakage neutron spectra from graphite cylinders irradiated with D-T neutrons for validation of evaluated nuclear data.

    PubMed

    Luo, F; Han, R; Chen, Z; Nie, Y; Shi, F; Zhang, S; Lin, W; Ren, P; Tian, G; Sun, Q; Gou, B; Ruan, X; Ren, J; Ye, M

    2016-10-01

    A benchmark experiment for validation of graphite data evaluated from nuclear data libraries was conducted for 14MeV neutrons irradiated on graphite cylinder samples. The experiments were performed using the benchmark experimental facility at the China Institute of Atomic Energy (CIAE). The leakage neutron spectra from the surface of graphite (Φ13cm×20cm) at 60° and 120° and graphite (Φ13cm×2cm) at 60° were measured by the time-of-flight (TOF) method. The obtained results were compared with the measurements made by the Monte Carlo neutron transport code MCNP-4C with the ENDF/B-VII.1, CENDL-3.1 and JENDL-4.0 libraries. The results obtained from a 20cm-thick sample revealed that the calculation results with CENDL-3.1 and JENDL-4.0 libraries showed good agreements with the experiments conducted in the whole energy region. However, a large discrepancy of approximately 40% was observed below the 3MeV energy region with the ENDF/B-VII.1 library. For the 2cm-thick sample, the calculated results obtained from the abovementioned three libraries could not reproduce the experimental data in the energy range of 5-7MeV. The graphite data in CENDL-3.1 were verified for the first time and were proved to be reliable. PMID:27620063

  20. Measurement of leakage neutron spectra from graphite cylinders irradiated with D-T neutrons for validation of evaluated nuclear data.

    PubMed

    Luo, F; Han, R; Chen, Z; Nie, Y; Shi, F; Zhang, S; Lin, W; Ren, P; Tian, G; Sun, Q; Gou, B; Ruan, X; Ren, J; Ye, M

    2016-10-01

    A benchmark experiment for validation of graphite data evaluated from nuclear data libraries was conducted for 14MeV neutrons irradiated on graphite cylinder samples. The experiments were performed using the benchmark experimental facility at the China Institute of Atomic Energy (CIAE). The leakage neutron spectra from the surface of graphite (Φ13cm×20cm) at 60° and 120° and graphite (Φ13cm×2cm) at 60° were measured by the time-of-flight (TOF) method. The obtained results were compared with the measurements made by the Monte Carlo neutron transport code MCNP-4C with the ENDF/B-VII.1, CENDL-3.1 and JENDL-4.0 libraries. The results obtained from a 20cm-thick sample revealed that the calculation results with CENDL-3.1 and JENDL-4.0 libraries showed good agreements with the experiments conducted in the whole energy region. However, a large discrepancy of approximately 40% was observed below the 3MeV energy region with the ENDF/B-VII.1 library. For the 2cm-thick sample, the calculated results obtained from the abovementioned three libraries could not reproduce the experimental data in the energy range of 5-7MeV. The graphite data in CENDL-3.1 were verified for the first time and were proved to be reliable.

  1. Bright flash neutron radiography capability of the research reactor at the McClellan Nuclear Research Center

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Lerche, M.; Schillinger, B.; Feller, W. B.

    2014-06-01

    The capability to produce a bright, short neutron pulse at the McClellan Nuclear Research Center (MNRC) can be very attractive for some neutron imaging applications. Complementary to conventional thermal neutron radiography conducted at the reactor, operating at the average power of 1 MW, a short pulse of ~25 ms FWHM duration can be produced at MNRC with the peak power exceeding 350 MW. Combination of a fast thermal neutron counting detector with a short neutron pulse at MNRC, enables high-resolution stroboscopic imaging to complement conventional neutron radiography. The results presented in this paper demonstrate the MNRC capabilities for conducting conventional thermal neutron radiography, demonstrating imaging spatial resolution below 100 μm, as well as bright flash neutron radiography with multiple nearly simultaneous events detected with microsecond timing resolution.

  2. Performance of a PADC personal neutron dosemeter at simulated and real workplace fields of the nuclear industry.

    PubMed

    Fiechtner, A; Boschung, M; Wernli, C

    2007-01-01

    In the framework of the EVIDOS (Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields) project, funded by the EC, measurements with PADC personal neutron dosemeters were carried out at several workplace fields of the nuclear industry and at simulated workplace fields. The measured personal neutron dose equivalents of the PADC personal neutron dosemeter are compared with values that were assessed within the EVIDOS project by other partners. The detection limits for different spectra types are given. In cases were the neutron dose was too low to be measured by the PADC personal neutron dosemeter, the response is estimated by convoluting the responses to monoenergetic neutrons with the dose energy distribution measured within EVIDOS. The advantages and limitations of the PADC personal neutron dosemeter are discussed. PMID:17578876

  3. Relevance of β-delayed neutron data for reactor, nuclear physics and astrophysics applications

    NASA Astrophysics Data System (ADS)

    Kratz, Karl-Ludwig

    2015-02-01

    Initially, yields (or abundances) and branching ratios of β-delayed neutrons (βdn) from fission products (Pn-values) have had their main importance in nuclear reactor control. At that time, the six-group mathematical approximation of the time-dependence of βdn-data in terms of the so-called "Keepin groups" was generally accepted. Later, with the development of high-resolution neutron spectroscopy, βdn data have provided important information on nuclear-structure properties at intermediate excitation energy in nuclei far from stability, as well as in nuclear astrophysics. In this paper, I will present some examples of the βdn-studies performed by the Kernchemie Mainz group during the past three decades. This work has been recognized as an example of "broad scientific diversity" which has led to my nomination for the 2014 Hans A. Bethe prize.

  4. Relevance of β-delayed neutron data for reactor, nuclear physics and astrophysics applications

    SciTech Connect

    Kratz, Karl-Ludwig

    2015-02-24

    Initially, yields (or abundances) and branching ratios of β-delayed neutrons (βdn) from fission products (P{sub n}-values) have had their main importance in nuclear reactor control. At that time, the six-group mathematical approximation of the time-dependence of βdn-data in terms of the so-called 'Keepin groups' was generally accepted. Later, with the development of high-resolution neutron spectroscopy, βdn data have provided important information on nuclear-structure properties at intermediate excitation energy in nuclei far from stability, as well as in nuclear astrophysics. In this paper, I will present some examples of the βdn-studies performed by the Kernchemie Mainz group during the past three decades. This work has been recognized as an example of 'broad scientific diversity' which has led to my nomination for the 2014 Hans A. Bethe prize.

  5. Results from the TARC experiment: spallation neutron phenomenology in lead and neutron-driven nuclear transmutation by adiabatic resonance crossing

    NASA Astrophysics Data System (ADS)

    Abánades, A.; Aleixandre, J.; Andriamonje, S.; Angelopoulos, A.; Apostolakis, A.; Arnould, H.; Belle, E.; Bompas, C. A.; Brozzi, D.; Bueno, J.; Buono, S.; Carminati, F.; Casagrande, F.; Cennini, P.; Collar, J. I.; Cerro, E.; Del Moral, R.; Díez, S.; Dumps, L.; Eleftheriadis, C.; Embid, M.; Fernández, R.; Gálvez, J.; García, J.; Gelès, C.; Giorni, A.; González, E.; González, O.; Goulas, I.; Heuer, D.; Hussonnois, M.; Kadi, Y.; Karaiskos, P.; Kitis, G.; Klapisch, R.; Kokkas, P.; Lacoste, V.; Le Naour, C.; López, C.; Loiseaux, J. M.; Martínez-Val, J. M.; Méplan, O.; Nifenecker, H.; Oropesa, J.; Papadopoulos, I.; Pavlopoulos, P.; Pérez-Enciso, E.; Pérez-Navarro, A.; Perlado, M.; Placci, A.; Poza, M.; Revol, J.-P.; Rubbia, C.; Rubio, J. A.; Sakelliou, L.; Saldaña, F.; Savvidis, E.; Schussler, F.; Sirvent, C.; Tamarit, J.; Trubert, D.; Tzima, A.; Viano, J. B.; Vieira, S.; Vlachoudis, V.; Zioutas, K.

    2002-02-01

    We summarize here the results of the TARC experiment whose main purpose is to demonstrate the possibility of using Adiabatic Resonance Crossing (ARC) to destroy efficiently Long-Lived Fission Fragments (LLFFs) in accelerator-driven systems and to validate a new simulation developed in the framework of the Energy Amplifier programme. An experimental set-up was installed in a CERN PS proton beam line to study how neutrons produced by spallation at relatively high energy ( E n⩾1 MeV) slow down quasi-adiabatically with almost flat isolethargic energy distribution and reach the capture resonance energy of an element to be transmuted where they will have a high probability of being captured. Precision measurements of energy and space distributions of spallation neutrons (using 2.5 and 3.5 GeV/ c protons) slowing down in a 3.3 m×3.3 m×3 m lead volume and of neutron capture rates on LLFFs 99Tc, 129I, and several other elements were performed. An appropriate formalism and appropriate computational tools necessary for the analysis and understanding of the data were developed and validated in detail. Our direct experimental observation of ARC demonstrates the possibility to destroy, in a parasitic mode, outside the Energy Amplifier core, large amounts of 99Tc or 129I at a rate exceeding the production rate, thereby making it practical to reduce correspondingly the existing stockpile of LLFFs. In addition, TARC opens up new possibilities for radioactive isotope production as an alternative to nuclear reactors, in particular for medical applications, as well as new possibilities for neutron research and industrial applications.

  6. Energy dependence of nuclear charge distribution in neutron induced fission of Z-even nuclei

    NASA Astrophysics Data System (ADS)

    Roshchenko, V. A.; Piksaikin, V. M.; Isaev, S. G.; Goverdovski, A. A.

    2006-07-01

    For the first time the distribution of nuclear charge of fission products with mass numbers 87, 88, 89, 91, 93, 94, 95, 137, 138, 139, and 140 and their complementary products have been studied for neutron induced fission of U235 and Pu239 in the energy range from thermal up to 1.2 MeV. The energy dependences of the cumulative yields of Br87, Br88, Br89, Br91, Kr93, Rb94, Rb95, I137, I138, I139, and I140 have been obtained by delayed neutron measurements. The most probable charge ZP(A)in the appropriate isobaric β-decay chains was estimated. The results were analyzed in terms of the deviation ΔZP(A') of the most probable charge of isobaric β-decay chains from the unchanged charge distribution before prompt neutron emission (nuclear charge polarization) and they are compared with experimental data of other authors and with predictions from Nethaway's ZP-formula and Wahl's ZP-model. We show that the nuclear charge polarization of primary fission fragments <ΔZP(A')> before prompt neutron evaporation decreases as the excitation energy of the compound nucleus increases. This decrease is more pronounced for fission of U235. The energy dependencies of ΔZP(A') and ΔZP(ZP) obtained in the present work show an attenuation of the odd-even effects in the charge distribution as the excitation energy of the compound nucleus increases.

  7. Correlation functions for a di-neutron condensate in asymmetric nuclear matter

    NASA Astrophysics Data System (ADS)

    Isayev, A. A.

    2008-07-01

    Recent calculations with an effective isospin-dependent contact interaction show the possibility of the crossover from superfluidity of neutron Cooper pairs in the S10 pairing channel to Bose-Einstein condensation (BEC) of di-neutron bound states in dilute nuclear matter. The density and spin correlation functions are calculated for a di-neutron condensate in asymmetric nuclear matter with the aim of finding the possible features of the BCS-BEC crossover. It is shown that the zero-momentum transfer spin correlation function satisfies the sum rule at zero temperature. In symmetric nuclear matter, the density correlation function changes sign at low momentum transfer across the BCS-BEC transition, and this feature can be considered as a signature of the crossover. At finite isospin asymmetry, this criterion gives too large a value for the critical asymmetry αcd~0.9, at which the BEC state is quenched. Therefore, it can be trusted for the description of the density-driven BCS-BEC crossover of neutron pairs only at small isospin asymmetry. This result generalizes the conclusion of the study in Phys. Rev. Lett. 95, 090402 (2005), where the change of sign of the density correlation function at low momentum transfer in two-component quantum fermionic atomic gas with the balanced populations of fermions of different species was considered as an unambiguous signature of the BCS-BEC transition.

  8. A dual neutron/gamma source for the Fissmat Inspection for Nuclear Detection (FIND) system.

    SciTech Connect

    Doyle, Barney Lee; King, Michael; Rossi, Paolo; McDaniel, Floyd Del; Morse, Daniel Henry; Antolak, Arlyn J.; Provencio, Paula Polyak; Raber, Thomas N.

    2008-12-01

    Shielded special nuclear material (SNM) is very difficult to detect and new technologies are needed to clear alarms and verify the presence of SNM. High-energy photons and neutrons can be used to actively interrogate for heavily shielded SNM, such as highly enriched uranium (HEU), since neutrons can penetrate gamma-ray shielding and gamma-rays can penetrate neutron shielding. Both source particles then induce unique detectable signals from fission. In this LDRD, we explored a new type of interrogation source that uses low-energy proton- or deuteron-induced nuclear reactions to generate high fluxes of mono-energetic gammas or neutrons. Accelerator-based experiments, computational studies, and prototype source tests were performed to obtain a better understanding of (1) the flux requirements, (2) fission-induced signals, background, and interferences, and (3) operational performance of the source. The results of this research led to the development and testing of an axial-type gamma tube source and the design/construction of a high power coaxial-type gamma generator based on the {sup 11}B(p,{gamma}){sup 12}C nuclear reaction.

  9. Displacement damage effects on CMOS APS image sensors induced by neutron irradiation from a nuclear reactor

    SciTech Connect

    Wang, Zujun Huang, Shaoyan; Liu, Minbo; Xiao, Zhigang; He, Baoping; Yao, Zhibin; Sheng, Jiangkun

    2014-07-15

    The experiments of displacement damage effects on CMOS APS image sensors induced by neutron irradiation from a nuclear reactor are presented. The CMOS APS image sensors are manufactured in the standard 0.35 μm CMOS technology. The flux of neutron beams was about 1.33 × 10{sup 8} n/cm{sup 2}s. The three samples were exposed by 1 MeV neutron equivalent-fluence of 1 × 10{sup 11}, 5 × 10{sup 11}, and 1 × 10{sup 12} n/cm{sup 2}, respectively. The mean dark signal (K{sub D}), dark signal spike, dark signal non-uniformity (DSNU), noise (V{sub N}), saturation output signal voltage (V{sub S}), and dynamic range (DR) versus neutron fluence are investigated. The degradation mechanisms of CMOS APS image sensors are analyzed. The mean dark signal increase due to neutron displacement damage appears to be proportional to displacement damage dose. The dark images from CMOS APS image sensors irradiated by neutrons are presented to investigate the generation of dark signal spike.

  10. Parameterization of nuclear cross-sections for coupled neutronic- thermalhydraulic codes

    SciTech Connect

    Miro, R.; Verdu, G.; Barrachina, T.; Rosello, O.

    2006-07-01

    The present work consists of developing an in-house methodology, called SIMTAB, to characterize, in a simplified way, the reactor core of LWR Nuclear Power Plants. Specifically, a cross-sections and kinetic parameters set are obtained as a function of the prompt and control variables. So that, the core can be modeled using a limited number of neutronic regions, in such a way that the reactor kinetic behavior is properly characterized. This simplification of the reactor core permits, from an operative point of view, the use of few cross sections data sets in coupled 3D neutronic-thermalhydraulic codes. (authors)

  11. Evolution of Nuclear Deformation in Neutron-Rich kr Isotopes

    NASA Astrophysics Data System (ADS)

    Albers, M.; Warr, N.; Blazhev, A.; Jolie, J.; Bernards, C.; Bettermann, L.; Cappellazzo, M.; Fransen, C.; Hackstein, M.; Moschner, K.; Pfeiffer, M.; Radeck, D.; Reiter, P.; Rudigier, M.; Seidlitz, M.; Siebeck, B.; Thoele, P.; Thomas, T.; Zell, K. O.; Marginean, N.; Mücher, D.; Bastin, B.; Dewitte, H.; Diriken, J.; van Duppen, P.

    2013-03-01

    The aim of this work was to investigate the behavior of the even-even Z=36 (Kr) isotopes in the phase transition region around the neutron number N=60 by determining the energies of the 2+1 states and their E2 decay transition strengths to the ground state in 94Kr (N=58) and 96Kr (N=60). Information on the energies of the first excited 2+ states existed only for the Kr isotopes up to N=58. For N=60, contradictory results on this observable were published recently. To clarify this contradiction two experimental runs were performed at REX-ISOLDE at CERN in 2009 and 2010, utilizing the high-efficiency MINI-BALL γ-ray spectrometer and analyzing the emitted γ-rays and scattered particles after the Coulomb-excitation reactions. The results of these experiments are presented and discussed.

  12. A Methodology for the Neutronics Design of Space Nuclear Reactors

    SciTech Connect

    King, Jeffrey C.; El-Genk, Mohamed S.

    2004-02-04

    A methodology for the neutronics design of space power reactors is presented. This methodology involves balancing the competing requirements of having sufficient excess reactivity for the desired lifetime, keeping the reactor subcritical at launch and during submersion accidents, and providing sufficient control over the lifetime of the reactor. These requirements are addressed by three reactivity values for a given reactor design: the excess reactivity at beginning of mission, the negative reactivity at shutdown, and the negative reactivity margin in submersion accidents. These reactivity values define the control worth and the safety worth in submersion accidents, used for evaluating the merit of a proposed reactor type and design. The Heat Pipe-Segmented Thermoelectric Module Converters space reactor core design is evaluated and modified based on the proposed methodology. The final reactor core design has sufficient excess reactivity for 10 years of nominal operation at 1.82 MW of fission power and is subcritical at launch and in all water submersion accidents.

  13. A Methodology for the Neutronics Design of Space Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    King, Jeffrey C.; El-Genk, Mohamed S.

    2004-02-01

    A methodology for the neutronics design of space power reactors is presented. This methodology involves balancing the competing requirements of having sufficient excess reactivity for the desired lifetime, keeping the reactor subcritical at launch and during submersion accidents, and providing sufficient control over the lifetime of the reactor. These requirements are addressed by three reactivity values for a given reactor design: the excess reactivity at beginning of mission, the negative reactivity at shutdown, and the negative reactivity margin in submersion accidents. These reactivity values define the control worth and the safety worth in submersion accidents, used for evaluating the merit of a proposed reactor type and design. The Heat Pipe-Segmented Thermoelectric Module Converters space reactor core design is evaluated and modified based on the proposed methodology. The final reactor core design has sufficient excess reactivity for 10 years of nominal operation at 1.82 MW of fission power and is subcritical at launch and in all water submersion accidents.

  14. How useful is neutron diffusion theory for nuclear rocket engine design

    SciTech Connect

    Hilsmeier, T.A.; Aithal, S.M.; Aldemir, T. )

    1992-01-01

    Correct modeling of neutron leakage and geometry effects is important in the design of a nuclear rocket engine because of the need for small reactor cores in space applications. In principle, there are generalized procedures that can account for these effects in a reliable manner (e.g., a three-dimensional, continuous-energy Monte Carlo calculation with all core components explicitly modeled). However, these generalized procedures are not usually suitable for parametric design studies because of the long computational times required, and the feasibility of using faster running, more approrimate neutronic modeling approaches needs to be investigated. Faster running neutronic models are also needed for simulator development to assess the engine performance during startup and power level changes. This paper investigates the potential of the few-group diffusion approach for nuclear rocket engine core design and optimization by comparing the k[sub eff] and power distributions obtained by the MCNP code against those obtained from the LEOPARD and 2DB codes for the particle bed reactor (PBR) concept described. The PBRs have been identified as one of the two near-term options for nuclear thermal propulsion by the joint National Aeronautics and Space Administration (NASA)/US Department of Energy/US Department of Defense program that was recently set up at the NASA Lewis Research Center to develop a flight-rated nuclear rocket engine by the 2020s.

  15. New approach to creation of geometrical module for nuclear reactor neutron transport computer simulation analysis

    SciTech Connect

    Poveschenko, T.; Poveschenko, O.

    2012-07-01

    This paper presents the new approach to creation of geometrical module for nuclear reactor neutron transport computer simulation analysis so called the differential cross method. It is elaborated for detecting boards between physical zones. It is proposed to use GMSH open source mesh editor extended by some features: a special option and a special kind of mesh (cubic background mesh).This method is aimed into Monte Carlo Method as well as for deterministic neutron transport methods. Special attention is attended for reactor core composed of a set of material zones with complicate geometrical boundaries. The idea of this approach is described. In general case method works for 3-D space. Algorithm of creation of the geometrical module is given. 2-D neutron transport benchmark-test for RBMK reactor cluster cell is described. It demonstrates the ability of this approach to provide flexible definition of geometrical meshing with preservation of curved surface or any level of heterogeneity. (authors)

  16. Analysis of the Nuclear Structure of 186 Re Using Neutron-Induced Reactions

    NASA Astrophysics Data System (ADS)

    Matters, David; McClory, John; Carroll, James; Chiara, Chris; Fotiades, Nikolaos; Devlin, Matt; Nelson, Ron O.

    2015-04-01

    Evaluated nuclear structure data for 186 Re identifies the majority of spin-parity assignments as tentative, with approximate values associated with the energies of several levels and transitions. In particular, the absence of known transitions that feed the Jπ =8+ isomer motivates their discovery, which would have astrophysical implications and a potential application in the development of an isomer power source. Using the GErmanium Array for Neutron Induced Excitations (GEANIE) spectrometer at the Los Alamos Neutron Science Center (LANSCE) Weapons Neutron Research (WNR) facility, the (n,2n γ) and (n,n' γ) reactions in a 99.52% enriched 187 Re target were used to measure γ-ray excitation functions in 186 Re and 187 Re, respectively. A preliminary analysis of the data obtained from the experiment reveals several new transitions in 186 Re and 187 Re.

  17. High-Flux Neutron Generator Facility for Geochronology and Nuclear Physics Research

    NASA Astrophysics Data System (ADS)

    Waltz, Cory; HFNG Collaboration

    2015-04-01

    A facility based on a next-generation, high-flux D-D neutron generator (HFNG) is being commissioned at UC Berkeley. The generator is designed to produce monoenergetic 2.45 MeV neutrons at outputs exceeding 1011 n/s. The HFNG is designed around two RF-driven multi-cusp ion sources that straddle a titanium-coated copper target. D + ions, accelerated up to 150 keV from the ion sources, self-load the target and drive neutron generation through the d(d,n)3 He fusion reaction. A well-integrated cooling system is capable of handling beam power reaching 120 kW impinging on the target. The unique design of the HFNG target permits experimental samples to be placed inside the target volume, allowing the samples to receive the highest neutron flux (1011 cm-2 s-1) possible from the generator. In addition, external beams of neutrons will be available simultaneously, ranging from thermal to 2.45 MeV. Achieving the highest neutron yields required carefully designed schemes to mitigate back-streaming of high energy electrons liberated from the cathode target by deuteron bombardment. The proposed science program is focused on pioneering advances in the 40 Ar/39 Ar dating technique for geochronology, new nuclear data measurements, basic nuclear science, and education. An end goal is to become a user facility for researchers. This work is supported by NSF Grant No. EAR-0960138, U.S. DOE LBNL Contract No. DE-AC02-05CH11231, U.S. DOE LLNL Contract No. DE-AC52-07NA27344, and UC Office of the President Award 12-LR-238745.

  18. Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

    NASA Astrophysics Data System (ADS)

    O. Silva, Hector; Berti, Emanuele; Sotani, Hajime

    2016-03-01

    Compact objects such as neutron stars are ideal astrophysical laboratories to test our understanding of the fundamental interactions in the regime of supranuclear densities, unachievable by terrestrial experiments. Despite recent progress, the description of matter (i.e., the equation of state) at such densities is still debatable. This translates into uncertainties in the bulk properties of neutron stars, masses and radii for instance. Here we will consider low-mass neutron stars. Such stars are expected to carry important information on nuclear matter near the nuclear saturation point. It has recently been shown that the masses and surface redshifts of low-mass neutron stars smoothly depend on simple functions of the central density and of a characteristic parameter η associated with the choice of equation of state. Here we extend these results to slowly-rotating and tidally deformed stars and obtain empirical relations for various quantities, such as the moment of inertia, quadrupole moment and ellipticity, tidal and rotational Love numbers, and rotational apsidal constants. We discuss how these relations might be used to constrain the equation of state by future observations in the electromagnetic and gravitational-wave spectra.

  19. PREFACE: XX International School on Nuclear Physics, Neutron Physics and Applications (Varna2013)

    NASA Astrophysics Data System (ADS)

    Stoyanov, Chavdar; Dimitrova, Sevdalina

    2014-09-01

    The present volume contains the lectures and short talks given at the XX International School on Nuclear Physics, Neutron Physics and Applications. The School was held from 16-22 September 2013 in 'Club Hotel Bolero' located in 'Golden Sands' (Zlatni Pyasaci) Resort Complex on the Black Sea coast, near Varna, Bulgaria. The School was organized by the Institute for Nuclear Research and Nuclear Energy of Bulgarian Academy of Sciences. Co-organizer of the School was the Bulgarian Nuclear Regulatory Agency and the Bogoliubov Laboratory of Theoretical Physics of Joint Institute for Nuclear Research - Dubna. Financial support was also provided by the Bulgarian Ministry of Education and Science. According to the long-standing tradition the School has been held every second year since 1973. The School's program has been restructured according to our enlarged new international links and today it is more similar to an international conference than to a classical nuclear physics school. This new image attracts many young scientists and students from around the world. This year, 2013, we had the pleasure to welcome more than sixty distinguished scientists as lecturers. Additionally, twenty young colleagues received the opportunity to present a short contribution. Ninety-four participants altogether enjoyed the scientific presentations and discussions as well as the relaxing atmosphere at the beach and during the pleasant evenings. The program of the School ranged from latest results in fundamental areas such as nuclear structure and reactions to the hot issues of application of nuclear methods, reactor physics and nuclear safety. The main topics have been the following: Nuclear excitations at various energies. Nuclei at high angular moments and temperature. Structure and reactions far from stability. Symmetries and collective phenomena. Methods for lifetime measurements. Astrophysical aspects of nuclear structure. Neutron nuclear physics. Nuclear data. Advanced methods in

  20. PREFACE: XIX International School on Nuclear Physics, Neutron Physics and Applications (VARNA 2011)

    NASA Astrophysics Data System (ADS)

    Stoyanov, Chavdar; Dimitrova, Sevdalina; Voronov, Victor

    2012-05-01

    This volume contains the lectures and short talks given at the XIX International School on Nuclear Physics, Neutron Physics and Applications. The School was held from 19-25 September 2011 in 'Club Hotel Bolero' located in the 'Golden Sands' (Zlatni Pyasaci) Resort Complex on the Black Sea coast, near Varna, Bulgaria. The School was organized by the Institute for Nuclear Research and Nuclear Energy of the Bulgarian Academy of Sciences. The co-organizer of the School was the Bulgarian Nuclear Regulatory Agency and the Bogoliubov Laboratory of Theoretical Physics of the Joint Institute for Nuclear Research - Dubna. According to long-standing tradition the School has been held every second year since 1973. The School's program has been restructured according to our enlarged new international links and today it is more similar to an international conference than to a classical nuclear physics school. This new image attracts many young scientists and students from around the world. This year - 2011, we had the pleasure of welcoming more than 50 distinguished scientists as lecturers. Additionally, 14 young colleagues received the opportunity to each present a short contribution. The program ranged from recent achievements in areas such as nuclear structure and reactions to the hot topics of the application of nuclear methods, reactor physics and nuclear safety. The 94 participants enjoyed the scientific presentations and discussions as well as the relaxing atmosphere at the beach and during the pleasant evenings. The main topics were as follows: Nuclear excitations at various energies Nuclei at high angular moments and temperature Structure and reactions far from stability Symmetries and collective phenomena Methods for lifetime measurements Astrophysical aspects of nuclear structure Neutron nuclear physics Nuclear data Advanced methods in nuclear waste treatment Nuclear methods for applications Several colleagues helped with the organization of the School. We would like

  1. New exclusive CHIPS-TPT algorithms for simulation of neutron-nuclear reactions

    NASA Astrophysics Data System (ADS)

    Kosov, M.; Savin, D.

    2015-05-01

    The CHIPS-TPT physics library for simulation of neutron-nuclear reactions on the new exclusive level is being developed in CFAR VNIIA. The exclusive modeling conserves energy, momentum and quantum numbers in each neutron-nuclear interaction. The CHIPS-TPT algorithms are based on the exclusive CHIPS library, which is compatible with Geant4. Special CHIPS-TPT physics lists in the Geant4 format are provided. The calculation time for an exclusive CHIPS-TPT simulation is comparable to the time of the corresponding Geant4- HP simulation. In addition to the reduction of the deposited energy fluctuations, which is a consequence of the energy conservation, the CHIPS-TPT libraries provide a possibility of simulation of the secondary particles correlation, e.g. secondary gammas, and of the Doppler broadening of gamma lines in the spectrum, which can be measured by germanium detectors.

  2. Nuclear shape transitions in neutron-rich medium-mass nuclei

    SciTech Connect

    Sarriguren, P.; Rodriguez-Guzman, R.; Robledo, L. M.

    2012-10-20

    We study the isotopic evolution of the ground-state nuclear shapes in neutron-rich Kr, Rb, Sr, Y, Zr, Nb, and Mo isotopic chains. Both even-even and odd-A nuclei are included in the analysis. For the latter we also study the systematics of their one-quasiparticle low-lying configurations. The theoretical approach is based on a selfconsistent Hartree-Fock-Bogoliubov formalism with finite range Gogny energy density functionals. Neutron separation energies, charge radii, and the spin-parity of the ground states are calculated and compared with available data. Shape-transition signatures are identified around N= 60 isotones as discontinuities in both charge radii isotopic shifts and spin-parities of the ground states. The nuclear deformation including triaxiality is shown to play a relevant role in the understanding of the bulk and spectroscopic features of the ground and low-lying one-quasiparticle states.

  3. A Search for Nonstandard Neutron Spin Interactions using Dual Species Xenon Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Bulatowicz, Michael; Larsen, Michael; Mirijanian, James; Fu, Changbo; Yan, Haiyang; Smith, Erick; Snow, Mike; Walker, Thad

    2012-06-01

    NMR measurements using polarized noble gases can constrain possible exotic spin-dependent interactions involving nucleons. A differential measurement insensitive to magnetic field fluctuations can be performed using a mixture of two polarized species with different ratios of nucleon spin to magnetic moment. We used the NMR cell test station at Northrop Grumman Corporation (NGC) (developed to evaluate dual species xenon vapor cells for the Nuclear Magnetic Resonance Gyroscope) to search for NMR frequency shifts of xenon-129 and xenon-131 when a non-magnetic zirconia rod is modulated near the NMR cell. We simultaneously excited both Xe isotopes and detected free-induction-decay transients. In combination with theoretical calculations of the neutron spin contribution to the nuclear angular momentum, the measurements put a new upper bound on possible monopole-dipole interactions of the neutron for ranges around 1mm. This work is supported by the NGC Internal Research and Development (IRAD) funding, the Department of Energy, and the NSF.

  4. Associated-particle sealed-tube neutron probe: Detection of explosives, contraband, and nuclear materials

    SciTech Connect

    Rhodes, E.; Dickerman, C.E.

    1996-05-01

    Continued research and development of the APSTNG shows the potential for practical field use of this technology for detection of explosives, contraband, and nuclear materials. The APSTNG (associated-particle sealed-tube generator) inspects the item to be examined using penetrating 14-MeV neutrons generated by the deuterium-tritium reaction inside a compact accelerator tube. An alpha detector built into the sealed tube detects the alpha-particle associated with each neutron emitted in a cone encompassing the volume to be inspected. Penetrating high-energy gamma-rays from the resulting neutron reactions identify specific nuclides inside the volume. Flight-times determined from the detection times of gamma-rays and alpha-particles separate the prompt and delayed gamma-ray spectra and allow a coarse 3-D image to be obtained of nuclides identified in the prompt spectrum. The generator and detectors can be on the same side of the inspected object, on opposite sides, or with intermediate orientations. Thus, spaces behind walls and other confined regions can be inspected. Signals from container walls can be discriminated against using the flight-time technique. No collimators or shielding are required, the neutron generator is relatively small, and commercial-grade electronics are employed. The use of 14-MeV neutrons yields a much higher cross-section for detecting nitrogen than that for systems based on thermal-neutron reactions alone, and the broad range of elements with significant 14-MeV neutron cross-sections extends explosives detection to other elements including low-nitrogen compounds, and allows detection of many other substances. Proof-of-concept experiments have been successfully performed for conventional explosives, chemical warfare agents, cocaine, and fissionable materials.

  5. A Fast Pulsed Neutron Source for Time-of-Flight Detection of Nuclear Materials and Explosives

    SciTech Connect

    Krishnan, Mahadevan; Bures, Brian; James, Colt; Madden, Robert; Hennig, Wolfgang; Breus, Dimitry; Asztalos, Stephen; Sabourov, Konstantin; Lane, Stephen

    2011-12-13

    AASC has built a fast pulsed neutron source based on the Dense Plasma Focus (DPF). The more current version stores only 100 J but fires at {approx}10-50 Hz and emits {approx}10{sup 6}n/pulse at a peak current of 100 kA. Both sources emit 2.45{+-}0.1 MeV(DD) neutron pulses of {approx}25-40 ns width. Such fast, quasi-monoenergetic pulses allow time-of-flight detection of characteristic emissions from nuclear materials or high explosives. A test is described in which iron targets were placed at different distances from the point neutron source. Detectors such as Stilbene and LaBr3 were used to capture inelastically induced, 847 keV gammas from the iron target. Shielding of the source and detectors eliminated most (but not all) of the source neutrons from the detectors. Gated detection, pulse shape analysis and time-of-flight discrimination enable separation of gamma and neutron signatures and localization of the target. A Monte Carlo simulation allows evaluation of the potential of such a fast pulsed source for a field-portable detection system. The high rep-rate source occupies two 200 liter drums and uses a cooled DPF Head that is <500 cm{sup 3} in volume.

  6. Study of astrophysical ({alpha}, n) reactions using light-neutron rich radioactive nuclear beams

    SciTech Connect

    Ishiyama, Hironobu; Watanabe, Yutaka; Imai, Nobuaki; Hirayama, Yoshikazu; Miyatake, Hiroari; Tanaka, Masa-Hiko; Yoshikawa, Nobuharu; Jeong, Sunchan; Fuchi, Yoshihide; Katayama, Ichiro; Nomura, Toru; Ishikawa, Tomoko; Das, Suranjan K.; Mizoi, Yutaka; Fukuda, Tomokazu; Hashimoto, Takashi; Nishio, Katsuhisa; Mitsuoka, Shinichi; Ikezoe, Hiroshi; Matsuda, Makoto

    2006-07-12

    A systematic study of astrophysical reaction rates of ({alpha}, n) reactions on light neutron-rich nuclei using low-energy radioactive nuclear beams is in progress at the tandem facility of Japan Atomic Energy Agency. Exclusive measurements of 8Li({alpha}, n)11B and 12B({alpha}, n)15N reaction cross sections have been performed successfully. Their excitation functions together with the experimental method are presented.

  7. Nuclear moments and charge radii of neutron-deficient francium isotopes and isomers

    NASA Astrophysics Data System (ADS)

    Voss, A.; Buchinger, F.; Cheal, B.; Crawford, J. E.; Dilling, J.; Kortelainen, M.; Kwiatkowski, A. A.; Leary, A.; Levy, C. D. P.; Mooshammer, F.; Ojeda, M. L.; Pearson, M. R.; Procter, T. J.; Tamimi, W. Al

    2015-04-01

    Collinear laser fluorescence spectroscopy has been performed on the ground and isomeric states of Fr,206204 in order to determine their spins, nuclear moments, and changes in mean-squared charge radii. A new experimental technique has been developed as part of this work which much enhances the data collection rate while maintaining the high resolution. This has permitted the extension of this study to the two isomeric states in each nucleus. The investigation of nuclear g factors and mean-squared charge radii indicates that the neutron-deficient Fr isotopes lie in a transitional region from spherical towards more collective structures.

  8. PREFACE: XVIII International School on Nuclear Physics, Neutron Physics and Applications

    NASA Astrophysics Data System (ADS)

    Stoyanov, Chavdar; Janeva, Natalia

    2010-11-01

    This volume contains the lectures and short talks given at the XVIII International School on Nuclear Physics, Neutron Physics and Applications. The School was held from 21 to 27 September 2009 in Hotel 'Lilia' located on 'Golden Sands' (Zlatni Pyasaci) Resort Complex on the Black Sea coast, near Varna, Bulgaria. The School was organized by Institute for Nuclear Research and Nuclear Energy of Bulgarian Academy of Sciences. Co-organizer of the School was Bulgarian Nuclear Regulatory Agency. The event was sponsored by National Science Fund of Bulgaria. According to the long-standing tradition the School has taken place every second year since 1973. The School content has been restructured according to our new enlarged international links and today it is more similar to an international conference than to a classical nuclear physics school. This new image attracts a lot of young scientists and students from many countries. This year - 2009, we had the pleasure to welcome more than 50 distinguished scientists as lecturers. Additionally, 14 young colleagues received the opportunity to present a short contribution. The program ranges from recent achievements in nuclear structure and reactions to the hot problems of the application of nuclear methods, reactor physics and nuclear safety. The 94 participants enjoyed the scientific presentations and discussions as well as the relaxing atmosphere at the beach and the pleasant evenings. The main topics were the following: Nuclear excitations at various energies. Nuclei at high angular moments and temperature. Structure and reactions far from stability Symmetries and collective phenomena Methods for lifetime measurements Astrophysical aspects of nuclear structure Neutron nuclear physics Nuclear data Advanced methods in nuclear waste treatment Nuclear methods for applications Several colleagues contributed to the organization of the School. We would like to thank to them and especially to the Scientific Secretary of the School Dr

  9. Improved Modeling of Prompt Fission Neutron Spectra for Nuclear Data Evaluations

    NASA Astrophysics Data System (ADS)

    Neudecker, Denise; Talou, Patrick; Kawano, Toshihiko; Kahler, Albert C.; White, Morgan C.

    2015-10-01

    The prompt fission neutron spectra (PFNS) of major actinides such as 239Pu and 235U are quantities of interest for nuclear physics application areas including reactor physics and national security. Nuclear data evaluations provide recommended data for those application areas based on nuclear theory and experiments. Here, we present improvements made to the effective models predicting the PFNS up to incident neutron energies of 30 MeV and their impact on evaluations. These models describe relevant physics processes better than those used for the current US nuclear data library ENDF/B-VII.1. In addition, the use of higher-fidelity models such as Monte Carlo Hauser-Feshbach calculations will be discussed in the context of future PFNS evaluations. (LA-UR-15-24763) This work was carried out under the auspices of the US Department of Energy, National Nuclear Security Administration and Office of Science, and performed by Los Alamos National Security LLC under Contract DE-AC52-06NA25396.

  10. Nuclear receptor function in skin health and disease: therapeutic opportunities in the orphan and adopted receptor classes.

    PubMed

    Yin, Kelvin; Smith, Aaron G

    2016-10-01

    The skin forms a vital barrier between an organism's external environment, providing protection from pathogens and numerous physical and chemical threats. Moreover, the intact barrier is essential to prevent water and electrolyte loss without which terrestrial life could not be maintained. Accordingly, acute disruption of the skin through physical or chemical trauma needs to be repaired timely and efficiently as sustained skin pathologies ranging from mild irritations and inflammation through to malignancy impact considerably on morbidity and mortality. The Nuclear Hormone Receptor Family of transcriptional regulators has proven to be highly valuable targets for addressing a range of pathologies, including metabolic syndrome and cancer. Indeed members of the classic endocrine sub-group, such as the glucocorticoid, retinoid, and Vitamin D receptors, represent mainstay treatment strategies for numerous inflammatory skin disorders, though side effects from prolonged use are common. Emerging evidence has now highlighted important functional roles for nuclear receptors belonging to the adopted and orphan subgroups in skin physiology and patho-physiology. This review will focus on these subgroups and explore the current evidence that suggests these nuclear receptor hold great promise as future stand-alone or complementary drug targets in treating common skin diseases and maintaining skin homeostasis. PMID:27544210

  11. Nuclear receptor function in skin health and disease: therapeutic opportunities in the orphan and adopted receptor classes.

    PubMed

    Yin, Kelvin; Smith, Aaron G

    2016-10-01

    The skin forms a vital barrier between an organism's external environment, providing protection from pathogens and numerous physical and chemical threats. Moreover, the intact barrier is essential to prevent water and electrolyte loss without which terrestrial life could not be maintained. Accordingly, acute disruption of the skin through physical or chemical trauma needs to be repaired timely and efficiently as sustained skin pathologies ranging from mild irritations and inflammation through to malignancy impact considerably on morbidity and mortality. The Nuclear Hormone Receptor Family of transcriptional regulators has proven to be highly valuable targets for addressing a range of pathologies, including metabolic syndrome and cancer. Indeed members of the classic endocrine sub-group, such as the glucocorticoid, retinoid, and Vitamin D receptors, represent mainstay treatment strategies for numerous inflammatory skin disorders, though side effects from prolonged use are common. Emerging evidence has now highlighted important functional roles for nuclear receptors belonging to the adopted and orphan subgroups in skin physiology and patho-physiology. This review will focus on these subgroups and explore the current evidence that suggests these nuclear receptor hold great promise as future stand-alone or complementary drug targets in treating common skin diseases and maintaining skin homeostasis.

  12. [RBE of neutrons from the BR-10 reactor based on their antitumor effect and on acute radiation reactions of the skin].

    PubMed

    Kuznetsova, M N; Ul'ianenko, S E

    1989-05-01

    The paper is concerned with the results of investigation of antitumor effectiveness (rats, sarcoma M-1) of neutron radiation of a BR-10 reactor with the mean energy of 0.85 MeV, correlated with the effect of 60Co gamma radiation (Luch-1). RBE in single local tumor radiation with neutrons was 4.5, being higher than RBE based on acute skin radiation reactions over a tumor (4.0). For this case FTA is over I (1.13) but slightly lower than after dose fractionated irradiation (1.18). Experimental data indicate the necessity of extending the clinical use of reactor neutrons and a profound study of the effects after neutron irradiation, particularly in dose-fractionated regimens.

  13. Fast rotating neutron stars with realistic nuclear matter equation of state

    NASA Astrophysics Data System (ADS)

    Cipolletta, F.; Cherubini, C.; Filippi, S.; Rueda, J. A.; Ruffini, R.

    2015-07-01

    We construct equilibrium configurations of uniformly rotating neutron stars for selected relativistic mean-field nuclear matter equations of state (EOS). We compute, in particular, the gravitational mass (M ), equatorial (Req) and polar (Rpol) radii, eccentricity, angular momentum (J ), moment of inertia (I ) and quadrupole moment (M2) of neutron stars stable against mass shedding and secular axisymmetric instability. By constructing the constant frequency sequence f =716 Hz of the fastest observed pulsar, PSR J1748-2446ad, and constraining it to be within the stability region, we obtain a lower mass bound for the pulsar, Mmin=[1.2 - 1.4 ]M⊙ , for the EOS employed. Moreover, we give a fitting formula relating the baryonic mass (Mb) and gravitational mass of nonrotating neutron stars, Mb/M⊙=M /M⊙+(13 /200 )(M /M⊙)2 [or M /M⊙=Mb/M⊙-(1 /20 )(Mb/M⊙)2], which is independent of the EOS. We also obtain a fitting formula, although not EOS independent, relating the gravitational mass and the angular momentum of neutron stars along the secular axisymmetric instability line for each EOS. We compute the maximum value of the dimensionless angular momentum, a /M ≡c J /(G M2) (or "Kerr parameter"), (a /M )max≈0.7 , found to be also independent of the EOS. We then compare and contrast the quadrupole moment of rotating neutron stars with the one predicted by the Kerr exterior solution for the same values of mass and angular momentum. Finally, we show that, although the mass quadrupole moment of realistic neutron stars never reaches the Kerr value, the latter is closely approached from above at the maximum mass value, as physically expected from the no-hair theorem. In particular, the stiffer the EOS, the closer the mass quadrupole moment approaches the value of the Kerr solution.

  14. Testing JEFF-3.1.1 and ENDF/B-VII.1 Decay and Fission Yield Nuclear Data Libraries with Fission Pulse Neutron Emission and Decay Heat Experiments

    NASA Astrophysics Data System (ADS)

    Cabellos, O.; de Fusco, V.; Diez de la Obra, C. J.; Martinez, J. S.; Gonzalez, E.; Cano-Ott, D.; Alvarez-Velarde, F.

    2014-04-01

    The aim of this work is to test the present status of Evaluated Nuclear Decay and Fission Yield Data Libraries to predict decay heat and delayed neutron emission rate, average neutron energy and neutron delayed spectra after a neutron fission pulse. Calculations are performed with JEFF-3.1.1 and ENDF/B-VII.1, and these are compared with experimental values. An uncertainty propagation assessment of the current nuclear data uncertainties is performed.

  15. Detection of special nuclear material from delayed neutron emission induced by a dual-particle monoenergetic source

    NASA Astrophysics Data System (ADS)

    Mayer, M.; Nattress, J.; Jovanovic, I.

    2016-06-01

    Detection of unique signatures of special nuclear materials is critical for their interdiction in a variety of nuclear security and nonproliferation scenarios. We report on the observation of delayed neutrons from fission of uranium induced in dual-particle active interrogation based on the 11B(d,n γ)12C nuclear reaction. Majority of the fissions are attributed to fast fission induced by the incident quasi-monoenergetic neutrons. A Li-doped glass-polymer composite scintillation neutron detector, which displays excellent neutron/γ discrimination at low energies, was used in the measurements, along with a recoil-based liquid scintillation detector. Time-dependent buildup and decay of delayed neutron emission from 238U were measured between the interrogating beam pulses and after the interrogating beam was turned off, respectively. Characteristic buildup and decay time profiles were compared to the common parametrization into six delayed neutron groups, finding a good agreement between the measurement and nuclear data. This method is promising for detecting fissile and fissionable materials in cargo scanning applications and can be readily integrated with transmission radiography using low-energy nuclear reaction sources.

  16. Correlation of the neutron star crust-core properties with the slope of the symmetry energy and the lead skin thickness

    NASA Astrophysics Data System (ADS)

    Pais, H.; Sulaksono, A.; Agrawal, B. K.; Providência, C.

    2016-04-01

    The correlations of the crust-core transition density and pressure in neutron stars with the slope of the symmetry energy and the neutron skin thickness are investigated, using different families of relativistic mean-field parametrizations with constant couplings and nonlinear terms mixing the σ - , ω - , and ρ -meson fields. It is shown that the modification of the density dependence of the symmetry energy, involving the σ or the ω meson, gives rise to different behaviors: the effect of the ω meson may also be reproduced within nonrelativistic phenomenological models, while the effect of the σ meson is essentially relativistic. Depending on the parametrization with σ -ρ or ω -ρ mixing terms, different values of the slope of the symmetry energy at saturation must be considered in order to obtain a neutron matter equation of state compatible with results from chiral effective field theory. This difference leads to different pressures at the crust-core transition density. A linear correlation between the transition density and the symmetry energy slope or the neutron skin thickness of the 208Pb nucleus is obtained, only when the ω meson is used to describe the density dependence of the symmetry energy. A comparison is made between the crust-core transition properties of neutron stars obtained by three different methods, the relativistic random phase approximation (RRPA), the Vlasov equation, and thermodynamical method. It is shown that the RRPA and the Vlasov methods predict similar transition densities for p n e β -equilibrium stellar matter.

  17. DOSIMETRIC response of a REM-500 in low energy neutron fields typical of nuclear power plants.

    PubMed

    Aslam; Matysiak, W; Atanackovic, J; Waker, A J

    2012-06-01

    This study investigates the response of a REM-500 to assess neutron quality factor and dose equivalent in low energy neutron fields, which are commonly encountered in the workplace environment of nuclear power stations. The McMaster University 3 MV Van de Graaff accelerator facility was used to measure the response of the instrument in monoenergetic neutron fields in the energy range 51 to 727 keV by bombarding a thin LiF target with 1.93-2.50 MeV protons. The energy distribution of the neutron fields produced in the facility was measured by a (3)He filled gas ionization chamber. The MCA mode of the REM-500 instrument was used to collect lineal energy distributions at varying neutron energies and to calculate the frequency and dose-mean lineal energies. The effective quality factor, Q-, was also calculated using the values of Q(y)listed in the REM-500 operation manual and compared with those of ICRP 60. The authors observed a continuously increasing trend in y - F, y-D, and Q-with an increase in neutron energy. It is interesting to note that standard tissue equivalent proportional counters (TEPCs) filled with tissue equivalent(TE) gas give rise to a similar trend for these microdosimetric quantities of interest in the same energy range; however, the averages calculated in this study are larger by about 15%compared to a TEPC filled with propane-based TE gas probably because of the larger stopping power of protons in propane compared to TE gas. These somewhat larger event sizes did not result in any significant increase in the Q-compared to those obtained from a TEPC filled with TE gas and were found to be in good agreement with other measurements reported earlier at corresponding neutron energies. The instrument quality factor response, R(Q), defined as the ratio of measured quality factor to the calculated quality factor in an ICRU tissue sphere,was found to vary with neutron energy. The instrument response,R(Q), was ~0.6 at 727 keV, which deteriorates further to

  18. Nuclear Recoil Calibrations in the LUX Detector Using Direct and Backscattered D-D Neutrons

    NASA Astrophysics Data System (ADS)

    Rhyne, Casey; LUX Collaboration

    2016-03-01

    The LUX dark matter search experiment is a 350 kg two-phase liquid/gas xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. I will discuss the latest calibration of the nuclear recoil (NR) response in liquid xenon (LXe), performed in-situ in the LUX detector using mono-energetic 2.45 MeV neutrons produced via the Adelphi Technologies, Inc. DD108 D-D neutron generator. The calibration measured the NR charge yield in LXe (Qy) to 0.7 keVnr recoil energy with an absolute determination of deposited energy and the NR light yield in LXe (Ly) to recoil energies of 1.1 keVnr, both of which improve upon all previous measurements. I will then focus in depth on the extension of this calibration using a new technique for generating a beam of sub-300 keV quasi-mono-energetic neutrons via the backscatter of 2.45 MeV neutrons off a deuterium-based reflector. Current simulations work optimizing the technique, its advantages, and its impact on future research will be discussed, including the extension of the NR Qy calibration down to 0.14 keVnr, an independent NR Ly calibration, and an a priori estimate of the expected 8B solar neutrino-nucleus coherent scattering signal in the upcoming LUX-ZEPLIN experiment.

  19. Nuclear reactor with internal thimble-type delayed neutron detection system

    DOEpatents

    Gross, Kenny C.; Poloncsik, John; Lambert, John D. B.

    1990-01-01

    This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus is located in the primary heat exchanger which conveys part of the reactor coolant past at least three separate delayed-neutron detectors mounted in this heat exchanger. The detectors are spaced apart such that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the delay time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector. At least two of these time components are determined during calibrated operation of the reactor. Thereafter during normal reactor operation, repeated comparisons are made by the method of regression approximation of the third time component for the best-fit line correlating measured delayed-neutron activity against activity that is approximated according to specific equations. The equations use these time-delay components and known parameter values of the fuel and of the part and emitting daughter isotopes.

  20. Design of sample carrier for neutron irradiation facility at TRIGA MARK II nuclear reactor

    NASA Astrophysics Data System (ADS)

    Abdullah, Y.; Hamid, N. A.; Mansor, M. A.; Ahmad, M. H. A. R. M.; Yusof, M. R.; Yazid, H.; Mohamed, A. A.

    2013-06-01

    The objective of this work is to design a sample carrier for neutron irradiation experiment at beam ports of research nuclear reactor, the Reaktor TRIGA PUSPATI (RTP). The sample carrier was designed so that irradiation experiment can be performed safely by researchers. This development will resolve the transferring of sample issues faced by the researchers at the facility when performing neutron irradiation studies. The function of sample carrier is to ensure the sample for the irradiation process can be transferred into and out from the beam port of the reactor safely and effectively. The design model used was House of Quality Method (HOQ) which is usually used for developing specifications for product and develop numerical target to work towards and determining how well we can meet up to the needs. The chosen sample carrier (product) consists of cylindrical casing shape with hydraulic cylinders transportation method. The sample placing can be done manually, locomotion was by wheel while shielding used was made of boron materials. The sample carrier design can shield thermal neutron during irradiation of sample so that only low fluencies fast neutron irradiates the sample.

  1. Filtered fast neutron irradiation system using Texas A&M University Nuclear Science Center Reactor

    NASA Astrophysics Data System (ADS)

    Jang, S. Y.; Kim, C. H.; Reece, W. D.; Braby, L. A.

    2004-09-01

    A heavily filtered fast neutron irradiation system (FNIS) was developed for a variety of applications, including the study of long-term health effects of fast neutrons by evaluating the biological mechanisms of damage in cultured cells and living animals such as rats or mice. This irradiation system includes an exposure cave made with a lead-bismuth alloy, a cave positioning system, a gamma and neutron monitoring system, a sample transfer system, and interchangeable filters. This system was installed in the irradiation cell of the Texas A&M University Nuclear Science Center Reactor (NSCR). For a realistic modeling of the NSCR, the irradiation cell, and the FNIS, this study used the Monte Carlo N-Particle (MCNP) code and a set of high-temperature ENDF/B-VI continuous neutron cross-section data. Sensitivity analysis was performed to find the characteristics of the FNIS as a function of the thickness of the lead-bismuth alloy. A paired ion chamber system was constructed with a tissue-equivalent plastic (A-150) and propane gas for total dose monitoring and with graphite and argon for gamma dose monitoring. This study, in addition, tested the Monte Carlo modeling of the FNIS system, as well as the performance of the system by comparing the calculated results with experimental measurements using activation foils and paired ion chambers.

  2. Los Alamos neutron science center nuclear weapons stewardship and unique national scientific capabilities

    SciTech Connect

    Schoenberg, Kurt F

    2010-12-15

    This presentation gives an overview of the Los Alamos Neutron Science Center (LANSCE) and its contributions to science and the nuclear weapons program. LANSCE is made of multiple experimental facilities (the Lujan Center, the Weapons Neutron Research facility (WNR), the Ultra-Cold Neutron facility (UCN), the proton Radiography facility (pRad) and the Isotope Production Facility (IPF)) served by the its kilometer long linear accelerator. Several research areas are supported, including materials and bioscience, nuclear science, materials dynamics, irradiation response and medical isotope production. LANSCE is a national user facility that supports researchers worldwide. The LANSCE Risk Mitigation program is currently in progress to update critical accelerator equipment to help extend the lifetime of LANSCE as a key user facility. The Associate Directorate of Business Sciences (ADBS) plays an important role in the continued success of LANSCE. This includes key procurement support, human resource support, technical writing support, and training support. LANSCE is also the foundation of the future signature facility MARIE (Matter-Radiation Interactions in Extremes).

  3. Personal neutron dosimetry in nuclear power plants using etched track and albedo thermoluminescence dosemeters.

    PubMed

    Fernández, F; Bakali, M; Amgarou, K; Nourreddine, A; Mouhssine, D

    2004-01-01

    Measurement of the personal dose equivalent rates for neutrons is a difficult task because available dosemeters do not provide the required energy response and sensitivity. Furthermore, the available wide calibration spectra recommended by the International Standard Organisation does not reproduce adequately the spectra encountered in practical situations of the nuclear industry. There is a real necessity to characterise the radiation field, in which workers can be exposed, and to calibrate personal dosemeters in order to determine the dose equivalent in these installations. For this reason, we measure the neutron spectrum with our Bonner sphere system and we fold this spectrum with energy-dependent fluence-to-dose conversion coefficients to obtain the reference dose equivalent rate. This reference value is then compared with the personal dosemeter reading to determine a field-specific correction factor. In this paper, we present the values of this field-specific correction factor for etched track and albedo thermoluminescence dosemeters at three measurement locations inside the containment building of the Vandellòs II nuclear power plant. We have found that assigning to each personal dosemeter the mean value of the field-specific correction factors of the three measurement locations, allows the evaluation of neutron personal dose equivalent rate with a relative uncertainty of approximately 25 and 15% for the PADC and albedo dosemeters, respectively. PMID:15353734

  4. Development of neutron measurement in high gamma field using new nuclear emulsion

    SciTech Connect

    Kawarabayashi, J.; Ishihara, K.; Takagi, K.; Tomita, H.; Iguchi, T.; Naka, T.; Morishima, K.; Maeda, S.

    2011-07-01

    To precisely measure the neutron emissions from a spent fuel assembly of a fast breeder reactor, we formed nuclear emulsions based on a non-sensitized Oscillation Project with Emulsion tracking Apparatus (OPERA) film with AgBr grain sizes of 60, 90, and 160 nm. The efficiency for {sup 252}Cf neutron detection of the new emulsion was calculated to be 0.7 x 10{sup -4}, which corresponded to an energy range from 0.3 to 2 MeV and was consistent with a preliminary estimate based on experimental results. The sensitivity of the new emulsion was also experimentally estimated by irradiating with 565 keV and 14 MeV neutrons. The emulsion with an AgBr grain size of 60 nm had the lowest sensitivity among the above three emulsions but was still sensitive enough to detect protons. Furthermore, the experimental data suggested that there was a threshold linear energy transfer of 15 keV/{mu}m for the new emulsion, below which no silver clusters developed. Further development of nuclear emulsion with an AgBr grain size of a few tens of nanometers will be the next stage of the present study. (authors)

  5. Sustainable Thorium Nuclear Fuel Cycles: A Comparison of Intermediate and Fast Neutron Spectrum Systems

    DOE PAGESBeta

    Brown, Nicholas R.; Powers, Jeffrey J.; Feng, B.; Heidet, F.; Stauff, N.; Zhang, G.; Todosow, Michael; Worrall, Andrew; Gehin, Jess C.; Kim, T. K.; et al

    2015-05-21

    This paper presents analyses of possible reactor representations of a nuclear fuel cycle with continuous recycling of thorium and produced uranium (mostly U-233) with thorium-only feed. The analysis was performed in the context of a U.S. Department of Energy effort to develop a compendium of informative nuclear fuel cycle performance data. The objective of this paper is to determine whether intermediate spectrum systems, having a majority of fission events occurring with incident neutron energies between 1 eV and 105 eV, perform as well as fast spectrum systems in this fuel cycle. The intermediate spectrum options analyzed include tight lattice heavymore » or light water-cooled reactors, continuously refueled molten salt reactors, and a sodium-cooled reactor with hydride fuel. All options were modeled in reactor physics codes to calculate their lattice physics, spectrum characteristics, and fuel compositions over time. Based on these results, detailed metrics were calculated to compare the fuel cycle performance. These metrics include waste management and resource utilization, and are binned to accommodate uncertainties. The performance of the intermediate systems for this selfsustaining thorium fuel cycle was similar to a representative fast spectrum system. However, the number of fission neutrons emitted per neutron absorbed limits performance in intermediate spectrum systems.« less

  6. Sustainable Thorium Nuclear Fuel Cycles: A Comparison of Intermediate and Fast Neutron Spectrum Systems

    SciTech Connect

    Brown, Nicholas R.; Powers, Jeffrey J.; Feng, B.; Heidet, F.; Stauff, N.; Zhang, G.; Todosow, Michael; Worrall, Andrew; Gehin, Jess C.; Kim, T. K.; Taiwo, T. A.

    2015-05-21

    This paper presents analyses of possible reactor representations of a nuclear fuel cycle with continuous recycling of thorium and produced uranium (mostly U-233) with thorium-only feed. The analysis was performed in the context of a U.S. Department of Energy effort to develop a compendium of informative nuclear fuel cycle performance data. The objective of this paper is to determine whether intermediate spectrum systems, having a majority of fission events occurring with incident neutron energies between 1 eV and 105 eV, perform as well as fast spectrum systems in this fuel cycle. The intermediate spectrum options analyzed include tight lattice heavy or light water-cooled reactors, continuously refueled molten salt reactors, and a sodium-cooled reactor with hydride fuel. All options were modeled in reactor physics codes to calculate their lattice physics, spectrum characteristics, and fuel compositions over time. Based on these results, detailed metrics were calculated to compare the fuel cycle performance. These metrics include waste management and resource utilization, and are binned to accommodate uncertainties. The performance of the intermediate systems for this selfsustaining thorium fuel cycle was similar to a representative fast spectrum system. However, the number of fission neutrons emitted per neutron absorbed limits performance in intermediate spectrum systems.

  7. Thermal and neutron-physical features of the nuclear reactor for a power pulsation plant for space applications

    NASA Astrophysics Data System (ADS)

    Gordeev, É. G.; Kaminskii, A. S.; Konyukhov, G. V.; Pavshuk, V. A.; Turbina, T. A.

    2012-05-01

    We have explored the possibility of creating small-size reactors with a high power output with the provision of thermal stability and nuclear safety under standard operating conditions and in emergency situations. The neutron-physical features of such a reactor have been considered and variants of its designs preserving the main principles and approaches of nuclear rocket engine technology are presented.

  8. Evaluation of dose equivalent by the electronic personal dosemeter for neutron 'Saphydose-N' at different workplaces of nuclear facilities.

    PubMed

    Chau, Q; Lahaye, T

    2007-01-01

    This paper presents the results of measurements made with the electronic personal neutron Saphydose-N during the four campaigns of the European contract EVIDOS (EValuation of Individual DOSimetry in mixed neutron and photon radiation fields). These measurements were performed at Institute for Radiological Protection and Nuclear Safety (IRSN) in France (C0), at the Krümmel Nuclear Power Plant in Germany (C1), at the VENUS Research Reactor and the Belgonucléaire fuel processing plant in Belgium (C2) and at the Ringhals Nuclear Power Plant in Sweden (C3). The results for Saphydose-N are compared with reference values for dose equivalent.

  9. Neutron monitoring systems including gamma thermometers and methods of calibrating nuclear instruments using gamma thermometers

    DOEpatents

    Moen, Stephan Craig; Meyers, Craig Glenn; Petzen, John Alexander; Foard, Adam Muhling

    2012-08-07

    A method of calibrating a nuclear instrument using a gamma thermometer may include: measuring, in the instrument, local neutron flux; generating, from the instrument, a first signal proportional to the neutron flux; measuring, in the gamma thermometer, local gamma flux; generating, from the gamma thermometer, a second signal proportional to the gamma flux; compensating the second signal; and calibrating a gain of the instrument based on the compensated second signal. Compensating the second signal may include: calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups; calculating a third signal that corresponds to delayed local gamma flux based on the selected yield fractions and time constants; and calculating the compensated second signal by subtracting the third signal from the second signal. The specific groups may have decay time constants greater than 5.times.10.sup.-1 seconds and less than 5.times.10.sup.5 seconds.

  10. Studies of neutron and proton nuclear activation in low-Earth orbit

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1982-01-01

    The expected induced radioactivity of experimental material in low Earth orbit was studied for characteristics of activating particles such as cosmic rays, high energy Earth albedo neutrons, trapped protons, and secondary protons and neutrons. The activation cross sections for the production of long lived radioisotopes and other existing nuclear data appropriate to the study of these reactions were compiled. Computer codes which are required to calculate the expected activation of orbited materials were developed. The decreased computer code used to predict the activation of trapped protons of materials placed in the expected orbits of LDEF and Spacelab II. Techniques for unfolding the fluxes of activating particles from the measured activation of orbited materials are examined.

  11. {sup 33}S for Neutron Capture Therapy: Nuclear Data for Monte Carlo Calculations

    SciTech Connect

    Porras, I.; Sabaté-Gilarte, M.; Praena, J.; Quesada, J.M.; Esquinas, P.L.

    2014-06-15

    A study of the nuclear data required for the Monte Carlo simulation of boron neutron capture therapy including the {sup 33}S isotope as an enhancer of the dose at small depths has been performed. In particular, the controversy on the available data for the {sup 33}S(n, α) cross section will be shown, which motivates new measurements. In addition to this, kerma factors for the main components of tissue are calculated with the use of fitting functions. Finally, we have applied these data to a potential neutron capture treatment with boron and sulfur addition to tissue in which part of the hydrogen atoms are replaced by deuterium, which improves the procedure.

  12. Nuclear Reaction Models Responsible for Simulation of Neutron-induced Soft Errors in Microelectronics

    SciTech Connect

    Watanabe, Y. Abe, S.

    2014-06-15

    Terrestrial neutron-induced soft errors in MOSFETs from a 65 nm down to a 25 nm design rule are analyzed by means of multi-scale Monte Carlo simulation using the PHITS-HyENEXSS code system. Nuclear reaction models implemented in PHITS code are validated by comparisons with experimental data. From the analysis of calculated soft error rates, it is clarified that secondary He and H ions provide a major impact on soft errors with decreasing critical charge. It is also found that the high energy component from 10 MeV up to several hundreds of MeV in secondary cosmic-ray neutrons has the most significant source of soft errors regardless of design rule.

  13. Nuclear level densities of 64,66Zn from neutron evaporation

    NASA Astrophysics Data System (ADS)

    Ramirez, A. P. D.; Voinov, A. V.; Grimes, S. M.; Schiller, A.; Brune, C. R.; Massey, T. N.; Salas-Bacci, A.

    2013-12-01

    Double differential cross sections of neutrons from d+63,65Cu reactions have been measured at deuteron energies of 6 and 7.5 MeV. The cross sections measured at backward angles have been compared to theoretical calculations in the framework of the statistical Hauser-Feshbach model. Three different level density models were tested: the Fermi-gas model, the Gilbert-Cameron model, and the microscopic approach through the Hartree-Fock-Bogoliubov method (HFBM). The calculations using the Gilbert-Cameron model are in best agreement with our experimental data. Level densities of the residual nuclei 64Zn and 66Zn have been obtained from statistical neutron evaporation spectra. The angle-integrated cross sections have been analyzed with the exciton model of nuclear reaction.

  14. Burst Oscillation Probes of Neutron Stars and Nuclear Burning with LOFT

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2012-01-01

    X-ray brightness oscillations during thermonuclear X-ray bursts--burst oscillations--have provided a new probe of neutron star spins as well as of the dependent nuclear burning processes. The frequency drift and amplitude evolution of the oscillations observed during bursts can in principle place constraints on the physics of thermonuclear flame spreading and the dynamics of the burning atmosphere. I use simulations appropriate to LOFT to explore the precision with which the time dependence of the oscillation frequency can be inferred. This can test, for example, different models for the frequency drift, such as up-lift versus geostrophic drift. I also explore the precision with which asymptotic frequencies can be constrained in order to estimate the capability for LOFT to detect the Doppler shifts induced by orbital motion of the neutron star from a sample of bursts at different orbital phases.

  15. Disordered nuclear pasta, magnetic field decay, and crust cooling in neutron stars

    NASA Astrophysics Data System (ADS)

    Horowitz, C. J.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Cumming, A.; Schneider, A. S.

    2015-04-01

    Nuclear pasta, with non-spherical shapes, is expected near the base of the crust in neutron stars. Large scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low conductivity pasta layer by increasing an impurity parameter Qimp. Predictions of light curves for the low mass X-ray binary MXB 1659-29, assuming a large Qimp, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust). This research was supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  16. Disordered Nuclear Pasta, Magnetic Field Decay, and Crust Cooling in Neutron Stars

    NASA Astrophysics Data System (ADS)

    Horowitz, C. J.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Cumming, A.; Schneider, A. S.

    2015-01-01

    Nuclear pasta, with nonspherical shapes, is expected near the base of the crust in neutron stars. Large-scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low-conductivity pasta layer by increasing an impurity parameter Qimp . Predictions of light curves for the low-mass x-ray binary MXB 1659-29, assuming a large Qimp, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore, observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust).

  17. Disordered nuclear pasta, magnetic field decay, and crust cooling in neutron stars.

    PubMed

    Horowitz, C J; Berry, D K; Briggs, C M; Caplan, M E; Cumming, A; Schneider, A S

    2015-01-23

    Nuclear pasta, with nonspherical shapes, is expected near the base of the crust in neutron stars. Large-scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low-conductivity pasta layer by increasing an impurity parameter Q_{imp}. Predictions of light curves for the low-mass x-ray binary MXB 1659-29, assuming a large Q_{imp}, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore, observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust).

  18. Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel

    DOEpatents

    Schreiber, Roger B.; Fero, Arnold H.; Sejvar, James

    1997-01-01

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor.

  19. Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel

    DOEpatents

    Schreiber, R.B.; Fero, A.H.; Sejvar, J.

    1997-12-16

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor. 8 figs.

  20. Nuclear level densities of 64,66 Zn from neutron evaporation

    DOE PAGESBeta

    Ramirez, A. P. D.; Voinov, A. V.; Grimes, S. M.; Schiller, A.; Brune, C. R.; Massey, T. N.; Salas-Bacci, A.

    2013-12-26

    Double differential cross sections of neutrons from d+63,65Cu reactions have been measured at deuteron energies of 6 and 7.5 MeV. The cross sections measured at backward angles have been compared to theoretical calculations in the framework of the statistical Hauser-Feshbach model. Three different level density models were tested: the Fermi-gas model, the Gilbert-Cameron model, and the microscopic approach through the Hartree-Fock-Bogoliubov method (HFBM). The calculations using the Gilbert-Cameron model are in best agreement with our experimental data. Level densities of the residual nuclei 64Zn and 66Zn have been obtained from statistical neutron evaporation spectra. In conclusion, the angle-integrated cross sectionsmore » have been analyzed with the exciton model of nuclear reaction.« less

  1. Constraints on the inner edge of neutron star crusts from relativistic nuclear energy density functionals

    SciTech Connect

    Moustakidis, Ch. C.; Lalazissis, G. A.; Niksic, T.; Vretenar, D.; Ring, P.

    2010-06-15

    The transition density n{sub t} and pressure P{sub t} at the inner edge between the liquid core and the solid crust of a neutron star are analyzed using the thermodynamical method and the framework of relativistic nuclear energy density functionals. Starting from a functional that has been carefully adjusted to experimental binding energies of finite nuclei, and varying the density dependence of the corresponding symmetry energy within the limits determined by isovector properties of finite nuclei, we estimate the constraints on the core-crust transition density and pressure of neutron stars: 0.086 fm{sup -3}<=n{sub t}<0.090 fm{sup -3} and 0.3 MeV fm{sup -3}

  2. Neutron spectrometry and dosimetry study at two research nuclear reactors using Bonner sphere spectrometer (BSS), rotational spectrometer (ROSPEC) and cylindrical nested neutron spectrometer (NNS).

    PubMed

    Atanackovic, J; Matysiak, W; Hakmana Witharana, S S; Aslam, I; Dubeau, J; Waker, A J

    2013-01-01

    Neutron spectrometry and subsequent dosimetry measurements were undertaken at the McMaster Nuclear Reactor (MNR) and AECL Chalk River National Research Universal (NRU) Reactor. The instruments used were a Bonner sphere spectrometer (BSS), a cylindrical nested neutron spectrometer (NNS) and a commercially available rotational proton recoil spectrometer. The purposes of these measurements were to: (1) compare the results obtained by three different neutron measuring instruments and (2) quantify neutron fields of interest. The results showed vastly different neutron spectral shapes for the two different reactors. This is not surprising, considering the type of the reactors and the locations where the measurements were performed. MNR is a heavily shielded light water moderated reactor, while NRU is a heavy water moderated reactor. The measurements at MNR were taken at the base of the reactor pool, where a large amount of water and concrete shielding is present, while measurements at NRU were taken at the top of the reactor (TOR) plate, where there is only heavy water and steel between the reactor core and the measuring instrument. As a result, a large component of the thermal neutron fluence was measured at MNR, while a negligible amount of thermal neutrons was measured at NRU. The neutron ambient dose rates at NRU TOR were measured to be between 0.03 and 0.06 mSv h⁻¹, while at MNR, these values were between 0.07 and 2.8 mSv h⁻¹ inside the beam port and <0.2 mSv h⁻¹ between two operating beam ports. The conservative uncertainty of these values is 15 %. The conservative uncertainty of the measured integral neutron fluence is 5 %. It was also found that BSS over-responded slightly due to a non-calibrated response matrix.

  3. Binary neutron star mergers: Dependence on the nuclear equation of state

    SciTech Connect

    Hotokezaka, Kenta; Kyutoku, Koutarou; Okawa, Hirotada; Shibata, Masaru; Kiuchi, Kenta

    2011-06-15

    We perform a numerical-relativity simulation for the merger of binary neutron stars with 6 nuclear-theory-based equations of states (EOSs) described by piecewise polytropes. Our purpose is to explore the dependence of the dynamical behavior of the binary neutron star merger and resulting gravitational waveforms on the EOS of the supernuclear-density matter. The numerical results show that the merger process and the first outcome are classified into three types: (i) a black hole is promptly formed, (ii) a short-lived hypermassive neutron star (HMNS) is formed, (iii) a long-lived HMNS is formed. The type of the merger depends strongly on the EOS and on the total mass of the binaries. For the EOS with which the maximum mass is larger than 2M{sub {center_dot}}, the lifetime of the HMNS is longer than 10 ms for a total mass m{sub 0}=2.7M{sub {center_dot}}. A recent radio observation suggests that the maximum mass of spherical neutron stars is M{sub max{>=}}1.97{+-}0.04M{sub {center_dot}} in one {sigma} level. This fact and our results support the possible existence of a HMNS soon after the onset of the merger for a typical binary neutron star with m{sub 0}=2.7M{sub {center_dot}}. We also show that the torus mass surrounding the remnant black hole is correlated with the type of the merger process; the torus mass could be large, {>=}0.1M{sub {center_dot}}, in the case that a long-lived HMNS is formed. We also show that gravitational waves carry information of the merger process, the remnant, and the torus mass surrounding a black hole.

  4. Nuclear shape dependence of Gamow-Teller distributions in neutron-deficient Pb isotopes

    SciTech Connect

    Sarriguren, P.; Moreno, O.; Alvarez-Rodriguez, R.; Moya de Guerra, E.

    2005-11-01

    We study Gamow-Teller strength distributions in the neutron-deficient even isotopes {sup 184-194}Pb in a search for signatures of deformation. The microscopic formalism used is based on a deformed quasiparticle random-phase approximation (QRPA) approach, which involves a self-consistent quasiparticle deformed Skyrme Hartree-Fock (HF) basis and residual spin-isospin forces in both the particle-hole and particle-particle channels. By analyzing the sensitivity of the Gamow-Teller strength distributions to the various ingredients in the formalism, we conclude that the {beta} decay of these isotopes could be a useful tool to look for fingerprints of nuclear deformation.

  5. Nuclear microprobe study of TiO 2-penetration in the epidermis of human skin xenografts

    NASA Astrophysics Data System (ADS)

    Kertész, Zs.; Szikszai, Z.; Gontier, E.; Moretto, P.; Surlève-Bazeille, J.-E.; Kiss, B.; Juhász, I.; Hunyadi, J.; Kiss, Á. Z.

    2005-04-01

    Titanium-dioxide is a widely used physical photoprotective component of various cosmetic products. However, very few experiments have been carried out on its penetration through the human epidermal barrier and its possible biological effects in vivo and in vitro. In the frame of the NANODERM EU5 project, the penetration of TiO2-nanoparticles through the epidermis of human foreskin grafts transplanted into SCID mice was investigated in the Debrecen and Bordeaux nuclear microprobe laboratories using combined IBA techniques. Transmission electron microscope studies of the same samples were also carried out in the DMPFCS laboratory. The skin grafts were treated with a hydrophobic emulsion containing micronised TiO2-nanoparticles in occlusion, for different time periods. Quantitative elemental concentrations and distributions have been determined in 14-16 μm thick freeze-dried sections obtained from quick frozen punch biopsies using STIM, PIXE and RBS analytical methods. Using both microscopic methods, we have observed nanoparticles having penetrated into the corneocyte layers of stratum corneum by direct visualisation in TEM and via their chemical fingerprint in PIXE. The human skin xenograft has proved to be a model particularly well adapted to such penetration studies.

  6. Electric dipole polarizability and the neutral skin

    SciTech Connect

    Piechaczek, A.; Nazarewicz, Witold; Reinhard, P.-G.; Agrawal, Bijay K; Colo, Gianluca; Paar, Nils; Roca-Maza, X; Vretenar, Dario

    2012-01-01

    The recent high-resolution measurement of the electric dipole (E1) polarizability {alpha}{sub D} in {sup 208}Pb [A. Tamii et al. Phys. Rev. Lett. 107 062502 (2011)] provides a unique constraint on the neutron-skin thickness of this nucleus. The neutron-skin thickness r{sub skin} of {sup 208}Pb is a quantity of critical importance for our understanding of a variety of nuclear and astrophysical phenomena. To assess the model dependence of the correlation between {alpha}{sub D} and r{sub skin}, we carry out systematic calculations for {sup 208}Pb, {sup 132}Sn, and {sup 48}Ca based on the nuclear density functional theory using both nonrelativistic and relativistic energy density functionals. Our analysis indicates that whereas individual models exhibit a linear dependence between {alpha}{sub D} and r{sub skin}, this correlation is not universal when one combines predictions from a host of different models. By averaging over these model predictions, we provide estimates with associated systematic errors for r{sub skin} and {alpha}{sub D} for the nuclei under consideration. We conclude that precise measurements of r{sub skin} in both {sup 48}Ca and {sup 208}Pb - combined with the recent measurement of {alpha}{sub D} - should significantly constrain the isovector sector of the nuclear energy density functional.

  7. On the idea of low-energy nuclear reactions in metallic lattices by producing neutrons from protons capturing "heavy" electrons

    NASA Astrophysics Data System (ADS)

    Tennfors, Einar

    2013-02-01

    The present article is a critical comment on Widom and Larsens speculations concerning low-energy nuclear reactions (LENR) based on spontaneous collective motion of protons in a room temperature metallic hydride lattice producing oscillating electric fields that renormalize the electron self-energy, adding significantly to the effective electron mass and enabling production of low-energy neutrons. The frequency and mean proton displacement estimated on the basis of neutron scattering from protons in palladium and applied to the Widom and Larsens model of the proton oscillations yield an electron mass enhancement less than one percent, far below the threshold for the proposed neutron production and even farther below the mass enhancement obtained by Widom and Larsen assuming a high charge density. Neutrons are not stopped by the Coulomb barrier, but the energy required for the neutron production is not low.

  8. Automatic neutron dosimetry system based on fluorescent nuclear track detector technology.

    PubMed

    Akselrod, M S; Fomenko, V V; Bartz, J A; Haslett, T L

    2014-10-01

    For the first time, the authors are describing an automatic fluorescent nuclear track detector (FNTD) reader for neutron dosimetry. FNTD is a luminescent integrating type of detector made of aluminium oxide crystals that does not require electronics or batteries during irradiation. Non-destructive optical readout of the detector is performed using a confocal laser scanning fluorescence imaging with near-diffraction limited resolution. The fully automatic table-top reader allows one to load up to 216 detectors on a tray, read their engraved IDs using a CCD camera and optical character recognition, scan and process simultaneously two types of images in fluorescent and reflected laser light contrast to eliminate false-positive tracks related to surface and volume crystal imperfections. The FNTD dosimetry system allows one to measure neutron doses from 0.1 mSv to 20 Sv and covers neutron energies from thermal to 20 MeV. The reader is characterised by a robust, compact optical design, fast data processing electronics and user-friendly software.

  9. Odd-even staggering in the neutron-proton interaction and nuclear mass models

    NASA Astrophysics Data System (ADS)

    Cheng, Y. Y.; Zhao, Y. M.; Arima, A.

    2015-02-01

    In this paper we study odd-even staggering of the empirical neutron-proton interaction between the last neutron and the last proton, denoted as δ V1 n -1 p , and its consequence in the Garvey-Kelson mass relations (GKs) and nuclear mass models. The root-mean-squared deviations of predicted masses respectively for even-A and odd-A nuclei by using two combinatorial GKs suggest a large odd-even staggering of δ V1 n -1 p between even-odd and odd-even nuclei, while the odd-even difference of δ V1 n -1 p between even-even and odd-odd nuclei is much smaller. The contribution of the odd-even staggering of δ V1 n -1 p between even-A and odd-A nuclei in deviations of theoretical δ V1 n -1 p values of the Duflo-Zuker model and the improved Weizs a ̈cker -Skyrme model are well represented by an isospin-dependent term. The consideration of this odd-even staggering improves our description of binding energies and one-neutron separation energies in both the Duflo-Zuker model and the improved Weizs a ̈cker -Skyrme model.

  10. Nuclear tracks, Sm isotopes and neutron capture effects in the Elephant Morraine shergottite

    NASA Technical Reports Server (NTRS)

    Rajan, R. S.; Lugmair, G.; Tamhane, A. S.; Poupeau, G.

    1986-01-01

    Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine shergottite, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12 + or - 2 cm, corresponding to a preatmospheric mass of 28 + or - 13 kg. Phosphates have U concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron-induced fission of U and Th, during the regolith exposure in the shergottite parent body (SPB). Sm-isotope studies, while not showing any clear-cut excess in Sm-150, make it possible to derive meaningful upper limits to thermal neutron fluences of 2 to 3 x 10 to the 15th n/sq cm, during a possible regolith irradiation. These limits are consistent with the track data and also make it possible to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith.

  11. A microstructural comparison of two nuclear-grade martensitic steels using small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Coppola, R.; Fiori, F.; Little, E. A.; Magnani, M.

    1997-06-01

    Results are presented of a small-angle neutron scattering (SANS) study on two 10-13% Cr martensitic stainless steels of interest for nuclear applications, viz. DIN 1.4914 (MANET specification, for fusion reactors) and AISI 410. The investigation has focussed principally on microstructural effects associated with the differences in chromium content between the two alloys. The size distribution functions determined from nuclear and magnetic SANS components for the two steels given identical heat treatments are in accord with an interpretation based on the presence of ˜ 1 nm size CCr aggregates in the microstructure. Much larger (˜ 10 nm) scattering inhomogeneities with different magnetic contrast are also present and tentatively identified as carbides.

  12. Computer analysis of nuclear track emulsion exposed to thermal neutrons and Cf source

    NASA Astrophysics Data System (ADS)

    Mamatkulov, K. Z.; Ambřozová, I.; Artemenkov, D. A.; Bradnova, V.; Kamanin, D. V.; Kattabekov, R. R.; Majling, L.; Marey, A.; Ploc, O.; Rusakova, V. V.; Stanoeva, R.; Turek, K.; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.

    2016-02-01

    Application of the nuclear track emulsion technique (NTE) in radioactivity and nuclear fission studies is discussed. It is suggested to use a HSP-1000 automated microscope for searching for a collinear cluster tri-partition of heavy nuclei implanted in NTE. Calibrations of α-particles and ion ranges in a novel NTE are carried out. Surface exposures of NTE samples to a Cf-252 source started. Planar events containing fragments and long-range α-particles as well as fragment triples only are studied. Splittings induced by thermal neutrons are studied in boron-enriched emulsion. Use of the image recognition program ”ImageJ” for obtaining characteristics of individual events and for events from the large scan area is presented.

  13. Neutron measurements in the Vandellòs II nuclear power plant with a Bonner sphere system.

    PubMed

    Fernández, F; Bakali, M; Tomás, M; Muller, H; Pochat, J L

    2004-01-01

    In some Spanish nuclear power plants of pressurised water reactor (PWR) type, albedo thermoluminescence dosemeters are used for personal dosimetry while survey meters, based on a thermal-neutron detector inside a cylindrical or spherical moderator, are used for dose rate assessment in routine monitoring. The response of both systems is highly dependent on the energy of the existing neutron fields. They are usually calibrated by means of ISO neutron sources with energy distributions quite different from those encountered at these installations. Spectrometric measurements with a Bonner sphere system (BSS) allow us to determine the reference dosimetric values. The UAB group, under request from the National Coordinated Research Action, was in charge of characterising the neutron fields and evaluating the response of personal dosemeters at several measurement points inside the containment building of the Catalan Nuclear Power Plant Vandellòs II. The neutron fields were characterised at five places using the UAB-BSS and a home made unfolding code called MITOM. The results obtained confirm the presence of low-energy components in the neutron field in most of the selected points. Moreover, we have found no influence of the nuclear fuel burning on the shape of the spectrum.

  14. Neutron measurements in the Vandellòs II nuclear power plant with a Bonner sphere system.

    PubMed

    Fernández, F; Bakali, M; Tomás, M; Muller, H; Pochat, J L

    2004-01-01

    In some Spanish nuclear power plants of pressurised water reactor (PWR) type, albedo thermoluminescence dosemeters are used for personal dosimetry while survey meters, based on a thermal-neutron detector inside a cylindrical or spherical moderator, are used for dose rate assessment in routine monitoring. The response of both systems is highly dependent on the energy of the existing neutron fields. They are usually calibrated by means of ISO neutron sources with energy distributions quite different from those encountered at these installations. Spectrometric measurements with a Bonner sphere system (BSS) allow us to determine the reference dosimetric values. The UAB group, under request from the National Coordinated Research Action, was in charge of characterising the neutron fields and evaluating the response of personal dosemeters at several measurement points inside the containment building of the Catalan Nuclear Power Plant Vandellòs II. The neutron fields were characterised at five places using the UAB-BSS and a home made unfolding code called MITOM. The results obtained confirm the presence of low-energy components in the neutron field in most of the selected points. Moreover, we have found no influence of the nuclear fuel burning on the shape of the spectrum. PMID:15353701

  15. Neutron Flux Interpolation with Finite Element Method in the Nuclear Fuel Cell Calculation using Collision Probability Method

    SciTech Connect

    Shafii, M. Ali; Su'ud, Zaki; Waris, Abdul; Kurniasih, Neny; Ariani, Menik; Yulianti, Yanti

    2010-12-23

    Nuclear reactor design and analysis of next-generation reactors require a comprehensive computing which is better to be executed in a high performance computing. Flat flux (FF) approach is a common approach in solving an integral transport equation with collision probability (CP) method. In fact, the neutron flux distribution is not flat, even though the neutron cross section is assumed to be equal in all regions and the neutron source is uniform throughout the nuclear fuel cell. In non-flat flux (NFF) approach, the distribution of neutrons in each region will be different depending on the desired interpolation model selection. In this study, the linear interpolation using Finite Element Method (FEM) has been carried out to be treated the neutron distribution. The CP method is compatible to solve the neutron transport equation for cylindrical geometry, because the angle integration can be done analytically. Distribution of neutrons in each region of can be explained by the NFF approach with FEM and the calculation results are in a good agreement with the result from the SRAC code. In this study, the effects of the mesh on the k{sub eff} and other parameters are investigated.

  16. Role of nuclear couplings in the inelastic excitation of weakly-bound neutron-rich nuclei

    SciTech Connect

    Dasso, C.H.; Lenzi, S.M.; Vitturi, A.

    1996-12-31

    Much effort is presently devoted to the study of nuclear systems far from the stability line. Particular emphasis has been placed in light systems such as {sup 11}Li, {sup 8}B and others, where the very small binding energy of the last particles causes their density distribution to extend considerably outside of the remaining nuclear core. Some of the properties associated with this feature are expected to characterize also heavier systems in the vicinity of the proton or neutron drip lines. It is by now well established that low-lying concentrations of multipole strength arise from pure configurations in which a peculiar matching between the wavelength of the continuum wavefunction of the particles and the range of the weakly-bound hole states occurs. To this end the authors consider the break-up of a weakly-bound system in a heavy-ion collision and focus attention in the inelastic excitation of the low-lying part of the continuum. They make use of the fact that previous investigations have shown that the multipole response in this region is not of a collective nature and describe their excited states as pure particle-hole configurations. Since the relevant parameter determining the strength distributions is the binding energy of the last bound orbital they find it most convenient to use single-particle wavefunctions generated by a sperical square-well potential with characteristic nuclear dimensions and whose depth has been adjusted to give rise to a situation in which the last occupied neutron orbital is loosely-bound. Spin-orbit couplings are, for the present purpose, ignored. The results of this investigation clearly indicate that nuclear couplings have the predominant role in causing projectile dissociation in many circumstances, even at bombarding energies remarkably below the Coulomb barrier.

  17. Performance assessment of self-interrogation neutron resonance densitometry for spent nuclear fuel assay

    NASA Astrophysics Data System (ADS)

    Hu, Jianwei; Tobin, Stephen J.; LaFleur, Adrienne M.; Menlove, Howard O.; Swinhoe, Martyn T.

    2013-11-01

    Self-Interrogation Neutron Resonance Densitometry (SINRD) is one of several nondestructive assay (NDA) techniques being integrated into systems to measure spent fuel as part of the Next Generation Safeguards Initiative (NGSI) Spent Fuel Project. The NGSI Spent Fuel Project is sponsored by the US Department of Energy's National Nuclear Security Administration to measure plutonium in, and detect diversion of fuel pins from, spent nuclear fuel assemblies. SINRD shows promising capability in determining the 239Pu and 235U content in spent fuel. SINRD is a relatively low-cost and lightweight instrument, and it is easy to implement in the field. The technique makes use of the passive neutron source existing in a spent fuel assembly, and it uses ratios between the count rates collected in fission chambers that are covered with different absorbing materials. These ratios are correlated to key attributes of the spent fuel assembly, such as the total mass of 239Pu and 235U. Using count rate ratios instead of absolute count rates makes SINRD less vulnerable to systematic uncertainties. Building upon the previous research, this work focuses on the underlying physics of the SINRD technique: quantifying the individual impacts on the count rate ratios of a few important nuclides using the perturbation method; examining new correlations between count rate ratio and mass quantities based on the results of the perturbation study; quantifying the impacts on the energy windows of the filtering materials that cover the fission chambers by tallying the neutron spectra before and after the neutrons go through the filters; and identifying the most important nuclides that cause cooling-time variations in the count rate ratios. The results of these studies show that 235U content has a major impact on the SINRD signal in addition to the 239Pu content. Plutonium-241 and 241Am are the two main nuclides responsible for the variation in the count rate ratio with cooling time. In short, this work

  18. Exclusive CHIPS-TPT algorithms for simulation of neutron-nuclear reactions

    NASA Astrophysics Data System (ADS)

    Kosov, Mikhail; Savin, Dmitriy

    2016-09-01

    The CHIPS-TPT physics library for simulation of neutron-nuclear reactions on the new exclusive level is being developed in CFAR VNIIA. The exclusive modeling conserves energy, momentum and quantum numbers in each neutron-nuclear interaction. The CHIPS-TPT algorithms are based on the exclusive CHIPS library, which is compatible with Geant4. Special CHIPS-TPT physics lists in the Geant4 format are provided. The calculation time for an exclusive CHIPS-TPT simulation is comparable to the time of the corresponding inclusive Geant4-HP simulation and much faster for mono-isotopic simulations. In addition to the reduction of the deposited energy fluctuations, which is a consequence of the energy conservation, the CHIPS-TPT libraries provide a possibility of simulation of the secondary particles correlation, e.g. secondary gammas or n-γ correlations, and of the Doppler broadening of the γ-lines in the simulated spectra, which can be measured by germanium detectors.

  19. Triga Mark III Reactor Operating Power and Neutron Flux Study by Nuclear Track Methodology

    NASA Astrophysics Data System (ADS)

    Espinosa, G.; Golzarri, J. I.; Raya-Arredondo, R.; Cruz-Galindo, S.; Sajo-Bohus, L.

    The operating power of a TRIGA Mark III reactor was studied using Nuclear Track Methodology (NTM). The facility has a Highly Enriched Uranium core that provides a neutron flux of around 2 x 1012 n cm-2 s-1 in the TO-2 irradiation channel. The detectors consisted of a Landauer® CR-39 (allyl diglycol polycarbonate) chip covered with a 3 mm Plexiglas® converter. After irradiation, the detectors were chemically etched in a 6.25M-KOH solution at 60±1 °C for 6 h. Track density was determined by a custom-made Digital Image Analysis System. The results show a direct proportionality between reactor power and average nuclear track density for powers in the range 0.1-7 kW. Data reproducibility and relatively low uncertainty (±3%) were achieved. NTM is a simple, fast and reliable technique that can serve as a complementary procedure to measure reactor operating power. It offers the possibility of calibrating the neutron flux density in any low power reactor.

  20. Nuclear shape and structure in neutron-rich {sup 110,111}Tc

    SciTech Connect

    Luo, Y. X.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Gore, P. M.; Jones, E. F.; Fong, D.; Rasmussen, J. O.; Lee, I. Y.; Stefanescu, I.; Che, X. L.; Zhu, S. J.; Wu, S. C.; Ginter, T. N.; Ma, W. C.; Ter-Akopian, G. M.; Daniel, A. V.; Stoyer, M. A.; Donangelo, R.; Gelberg, A.

    2006-08-15

    The high-spin nuclear structure of Tc isotopes is extended to more neutron-rich regions based on the measurements of prompt {gamma} rays from the spontaneous fission of {sup 252}Cf at the Gammasphere. The high-spin level scheme of N=67 neutron-rich {sup 110}Tc (Z=43) is established for the first time, and that of {sup 111}Tc is extended and expanded. The ground band of {sup 111}Tc reaches the band-crossing region, and the new observation of the weakly populated {alpha}=-1/2 member of the band provides important information on signature splitting. The systematics of band crossings in the isotopic and isotonic chains and a CSM calculation suggest that the band crossing of the ground band of {sup 111}Tc is due to alignment of a pair of h{sub 11/2} neutrons. The best fit to signature splitting, branching ratios, and excitations of the ground band of {sup 111}Tc by the rigid triaxial rotor plus particle model calculations result in a shape of {epsilon}{sub 2}=0.32 and {gamma}=-26 deg. for this nucleus. Its triaxiality is larger than that of {sup 107,109}Tc, which indicates increasing triaxiality in Tc isotopes with increasing neutron number. The identification of the weakly populated K+2 satellite band provides strong evidence for the large triaxiality of {sup 111}Tc. In {sup 110}Tc, the four lowest-lying levels observed are very similar to those in {sup 108}Tc. At an excitation of 478.9 keV above the lowest state observed, ten states of a {delta}I=1 band are observed. This band of {sup 110}Tc is very analogous to the {delta}I=1 bands in {sup 106,108}Tc, but it has greater and reversal signature splitting at higher spins.

  1. New Kohn-Sham density functional based on microscopic nuclear and neutron matter equations of state

    NASA Astrophysics Data System (ADS)

    Baldo, M.; Robledo, L. M.; Schuck, P.; Viñas, X.

    2013-06-01

    A new version of the Barcelona-Catania-Paris energy functional is applied to a study of nuclear masses and other properties. The functional is largely based on calculated ab initio nuclear and neutron matter equations of state. Compared to typical Skyrme functionals having 10-12 parameters apart from spin-orbit and pairing terms, the new functional has only 2 or 3 adjusted parameters, fine tuning the nuclear matter binding energy and fixing the surface energy of finite nuclei. An energy rms value of 1.58 MeV is obtained from a fit of these three parameters to the 579 measured masses reported in the Audi and Wapstra [Nucl. Phys. ANUPABL0375-947410.1016/j.nuclphysa.2003.11.003 729, 337 (2003)] compilation. This rms value compares favorably with the one obtained using other successful mean field theories, which range from 1.5 to 3.0 MeV for optimized Skyrme functionals and 0.7 to 3.0 for the Gogny functionals. The other properties that have been calculated and compared to experiment are nuclear radii, the giant monopole resonance, and spontaneous fission lifetimes.

  2. Equation of state of neutron star matter, and the nuclear symmetry energy

    SciTech Connect

    Loan, Doan Thi; Tan, Ngo Hai; Khoa, Dao T.; Margueron, Jerome

    2011-06-15

    The nuclear mean-field potentials obtained in the Hartree-Fock method with different choices of the in-medium nucleon-nucleon (NN) interaction have been used to study the equation of state (EOS) of the neutron star (NS) matter. The EOS of the uniform NS core has been calculated for the npe{mu} composition in the {beta} equilibrium at zero temperature, using version Sly4 of the Skyrme interaction as well as two density-dependent versions of the finite-range M3Y interaction (CDM3Yn and M3Y-Pn), and versions D1S and D1N of the Gogny interaction. Although the considered effective NN interactions were proven to be quite realistic in numerous nuclear structure and/or reaction studies, they give quite different behaviors of the symmetry energy of nuclear matter at supranuclear densities that lead to the soft and stiff scenarios discussed recently in the literature. Different EOS's of the NS core and the EOS of the NS crust given by the compressible liquid drop model have been used as input of the Tolman-Oppenheimer-Volkov equations to study how the nuclear symmetry energy affects the model prediction of different NS properties, like the cooling process as well as the gravitational mass, radius, and moment of inertia.

  3. TANGRA-Setup for the Investigation of Nuclear Fission Induced by 14.1 MeV Neutrons

    NASA Astrophysics Data System (ADS)

    Ruskov, I. N.; Kopatch, Yu. N.; Bystritsky, V. M.; Skoy, V. R.; Shvetsov, V. N.; Hambsch, F.-J.; Oberstedt, S.; Noy, R. Capote; Sedyshev, P. V.; Grozdanov, D. N.; Ivanov, I. Zh.; Aleksakhin, V. Yu.; Bogolubov, E. P.; Barmakov, Yu. N.; Khabarov, S. V.; Krasnoperov, A. V.; Krylov, A. R.; Obhođaš, J.; Pikelner, L. B.; Rapatskiy, V. L.; Rogachev, A. V.; Rogov, Yu. N.; Ryzhkov, V. I.; Sadovsky, A. B.; Salmin, R. A.; Sapozhnikov, M. G.; Slepnev, V. M.; Sudac, D.; Tarasov, O. G.; Valković, V.; Yurkov, D. I.; Zamyatin, N. I.; Zeynalov, Sh. S.; Zontikov, A. O.; Zubarev, E. V.

    The new experimental setup TANGRA (Tagged Neutrons & Gamma Rays), for the investigation of neutron induced nuclear reactions, e.g. (n,xn'), (n,xn'γ), (n,γ), (n,f), on a number of important isotopes for nuclear science and engineering (235,238U, 237Np, 239Pu, 244,245,248Cm) is under construction and being tested at the Frank Laboratory of Neutron Physics (FLNP) of the Joint Institute for Nuclear Research (JINR) in Dubna. The TANGRA setup consists of: a portable neutron generator ING-27, with a 64-pixel Si charge-particle detector incorporated into its vacuum chamber for registering of α-particles formed in the T(d, n)4He reaction, as a source of 14.1 MeV steady-state neutrons radiation with an intensity of ∼5x107n/s; a combined iron (Fe), borated polyethylene (BPE) and lead (Pb) compact shielding-collimator; a reconfigurable multi-detector (neutron plus gamma ray detecting system); a fast computer with 2 (x16 channels) PCI-E 100 MHz ADC cards for data acquisition and hard disk storage; Linux ROOT data acquisition, visualization and analysis software. The signals from the α-particle detector are used to 'tag' the neutrons with the coincident α-particles. Counting the coincidences between the α-particle and the reaction-product detectors in a 20ns time-interval improves the effect/background-ratio by a factor of ∼200 as well as the accuracy in the neutron flux determination, which decreases noticeably the overall experimental data uncertainty.

  4. Fission cross-sections, prompt fission neutron and γ-ray emission in request for nuclear applications

    NASA Astrophysics Data System (ADS)

    Hambsch, F.-J.; Salvador-Castiñeira, P.; Oberstedt, S.; Göök, A.; Billnert, R.

    2016-06-01

    In recent years JRC-IRMM has been investigating fission cross-sections of 240,242Pu in the fast-neutron energy range relevant for innovative reactor systems and requested in the High Priority Request List (HPRL) of the OECD/Nuclear Energy Agency (NEA). In addition to that, prompt neutron multiplicities are being investigated for the major isotopes 235U, 239Pu in the neutron-resonance region using a newly developed scintillation detector array (SCINTIA) and an innovative modification of the Frisch-grid ionisation chamber for fission-fragment detection. These data are highly relevant for improved neutron data evaluation and requested by the OECD/Working Party on Evaluation Cooperation (WPEC). Thirdly, also prompt fission γ-ray emission is investigated using highly efficient lanthanide-halide detectors with superior timing resolution. Again, those data are requested in the HPRL for major actinides to solve open questions on an under-prediction of decay heat in nuclear reactors. The information on prompt fission neutron and γ-ray emission is crucial for benchmarking nuclear models to study the de-excitation process of neutron-rich fission fragments. Information on γ-ray emission probabilities is also useful in decommissioning exercises on damaged nuclear power plants like Fukushima Daiichi to which JRC-IRMM is contributing. The results on the 240,242Pu fission cross section, 235U prompt neutron multiplicity in the resonance region and correlations with fission fragments and prompt γ-ray emission for several isotopes will be presented and put into perspective.

  5. Nuclear reactions with 14 MeV neutrons and bremsstrahlungs in giant dipole resonance (GDR) region using small accelerators

    NASA Astrophysics Data System (ADS)

    Thiep, Tran Duc; Van Do, Nguyen; An, Truong Thi; Son, Nguyen Ngoc

    2003-07-01

    In 1974 an accelerator of deterium, namely neutron generator NA-3-C was put into operation and in 1982 another accelerator of electron Microtron MT-17 started its work in the Institute of Physics. Though very modest these accelerators are useful for developing countries as Vietnam in both Nuclear Physics Research and Training. In this report we present some results obtained in studies on Nuclear Data, Nuclear Reactions as well as nuclear activation analysis methods. We also would like to discuss about the possibilities of collaboration in the future.

  6. On the robustness of the r-process in neutron-star mergers against variations of nuclear masses

    NASA Astrophysics Data System (ADS)

    Mendoza-Temis, J. J.; Wu, M. R.; Martínez-Pinedo, G.; Langanke, K.; Bauswein, A.; Janka, H.-T.; Frank, A.

    2016-07-01

    r-process calculations have been performed for matter ejected dynamically in neutron star mergers (NSM), such calculations are based on a complete set of trajectories from a three-dimensional relativistic smoothed particle hydrodynamic (SPH) simulation. Our calculations consider an extended nuclear reaction network, including spontaneous, β- and neutron-induced fission and adopting fission yield distributions from the ABLA code. In this contribution we have studied the sensitivity of the r-process abundances to nuclear masses by using diferent mass models for the calculation of neutron capture cross sections via the statistical model. Most of the trajectories, corresponding to 90% of the ejected mass, follow a relatively slow expansion allowing for all neutrons to be captured. The resulting abundances are very similar to each other and reproduce the general features of the observed r-process abundance (the second and third peaks, the rare-earth peak and the lead peak) for all mass models as they are mainly determined by the fission yields. We find distinct differences in the predictions of the mass models at and just above the third peak, which can be traced back to different predictions of neutron separation energies for r-process nuclei around neutron number N = 130.

  7. Design of the Testing Set-up for a Nuclear Fuel Rod by Neutron Radiography at CARR

    NASA Astrophysics Data System (ADS)

    Wei, Guohai; Han, Songbai; Wang, Hongli; Hao, Lijie; Wu, Meimei; He, Linfeng; Wang, Yu; Liu, Yuntao; Sun, Kai; Chen, Dongfeng

    In this paper, an experimental set-up dedicated to non-destructively test a 15cm-long Pressurized Water Reactor (PWR) nuclear fuel rod by neutron radiography (NR) is described. It consists of three parts: transport container, imaging block and steel support. The design of the transport container was optimized with Monte-Carlo Simulation by the MCNP code. The material for the shell of the transport container was chosen to be lead with the thickness of 13 cm. Also, the mechanical devices were designed to control fuel rod movement inside the container. The imaging block was designed as the exposure platform, with three openings for the neutron beam, neutron converter foil, and specimen. Development and application of this experimental set-up will help gain much experience for investigating the actual irradiated fuel rod by neutron radiography at CARR in the future.

  8. Imprints of the nuclear symmetry energy on gravitational waves from the axial w-modes of neutron stars

    SciTech Connect

    Wen Dehua; Li Baoan; Krastev, Plamen G.

    2009-08-15

    The eigenfrequencies of the axial w-modes of oscillating neutron stars are studied using the continued fraction method with an equation of state (EOS) partially constrained by the recent terrestrial nuclear laboratory data. It is shown that the density dependence of the nuclear symmetry energy E{sub sym}({rho}) affects significantly both the frequencies and the damping times of these modes. Besides confirming the previously found universal behavior of the mass-scaled eigenfrequencies as functions of the compactness of neutron stars, we explored several alternative universal scaling functions. Moreover, the w{sub II}-mode is found to exist only for neutron stars having a compactness of M/R{>=}0.1078 independent of the EOS used.

  9. The Brueckner-Hartree-Fock Equation of State for Nuclear Matter and Neutron Skin

    NASA Astrophysics Data System (ADS)

    Qing-Yang, Bu; Zeng-Hua, Li; Hans-Josef, Schulze

    2016-03-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 11075037 and 11475045, the Scientific Research Foundation for the Returned Overseas Chinese Scholars of the Ministry of Education of China, the Fundamental Research Funds for the Central Universities of China, the Shanghai Leading Academic Discipline Project under Grant No B107, and the ‘NewCompStar’, COST Action MP1304.

  10. Pulsed, Photonuclear-induced, Neutron Measurements of Nuclear Materials with Composite Shielding

    SciTech Connect

    James Jones; Kevin Haskell; Rich Waston; William Geist; Jonathan Thron; Corey Freeman; Martyn Swinhoe; Seth McConchie; Eric Sword; Lee Montierth; John Zabriskie

    2011-07-01

    Active measurements were performed using a 10-MeV electron accelerator with inspection objects containing various nuclear and nonnuclear materials available at the Idaho National Laboratory’s Zero Power Physics Reactor (ZPPR) facility. The inspection objects were assembled from ZPPR reactor plate materials to evaluate the measurement technologies for the characterization of plutonium, depleted uranium or highly enriched uranium shielded by both nuclear and non-nuclear materials. A series of pulsed photonuclear, time-correlated measurements were performed with unshielded calibration materials and then compared with the more complex composite shield configurations. The measurements used multiple 3He detectors that are designed to detect fission neutrons between pulses of an electron linear accelerator. The accelerator produced 10-MeV bremsstrahlung X-rays at a repetition rate of 125 Hz (8 ms between pulses) with a 4-us pulse width. All inspected objects were positioned on beam centerline and 100 cm from the X-ray source. The time-correlated data was collected in parallel using both a Los Alamos National Laboratory-designed list-mode acquisition system and a commercial multichannel scaler analyzer. A combination of different measurement configurations and data analysis methods enabled the identification of each object. This paper describes the experimental configuration, the ZPPR inspection objects used, and the various measurement and analysis results for each inspected object.

  11. Neutron dosimetry

    DOEpatents

    Quinby, Thomas C.

    1976-07-27

    A method of measuring neutron radiation within a nuclear reactor is provided. A sintered oxide wire is disposed within the reactor and exposed to neutron radiation. The induced radioactivity is measured to provide an indication of the neutron energy and flux within the reactor.

  12. A potential alternative/complement to the traditional thermal neutron based counting in Nuclear Safeguards and Security

    NASA Astrophysics Data System (ADS)

    Chernikova, Dina; Naeem, Syed F.; Axell, Kåre; Trnjanin, Nermin; Nordlund, Anders

    2016-02-01

    A new concept for thermal neutron based correlation and multiplicity measurements is proposed in this paper. The main idea of the concept consists of using 2.223 MeV gammas (or 1.201 MeV, DE) originating in the 1 H (n , γ) 2 D-reaction instead of using traditional thermal neutron counting. Results of investigations presented in this paper indicate that gammas from thermal neutron capture reactions preserve the information about the correlation characteristics of thermal (fast) neutrons in the same time scale. Therefore, instead of thermal neutron detectors (or as a complement) one may use traditional and inexpensive gamma detectors, such as NaI, BGO, CdZnTe or any other gamma detector. In this work we used D8×8 cm2 NaI scintillator to test the concept. Thus, the new approach helps to address the problem of replacement of 3He-counters and problems related to the specific measurements of spent nuclear fuel directly in the spent fuel pool. It has a particular importance for Nuclear Safeguards and Security. Overall, this work represents the proof of concept study and reports on the experimental and numerical evidence that thermal neutron capture gammas may be used in the context of correlation and multiplicity measurements. Investigations were performed using a 252Cf-correlated neutron source and an 241Am-Be-random neutron source. The related idea of the Gamma Differential Die-Away approach is investigated numerically in this paper as well, and will be tested experimentally in future work.

  13. MCNP (Monte Carlo Neutron Photon) capabilities for nuclear well logging calculations

    SciTech Connect

    Forster, R.A.; Little, R.C.; Briesmeister, J.F.

    1989-01-01

    The Los Alamos Radiation Transport Code System (LARTCS) consists of state-of-the-art Monte Carlo and discrete ordinates transport codes and data libraries. The general-purpose continuous-energy Monte Carlo code MCNP (Monte Carlo Neutron Photon), part of the LARTCS, provides a computational predictive capability for many applications of interest to the nuclear well logging community. The generalized three-dimensional geometry of MCNP is well suited for borehole-tool models. SABRINA, another component of the LARTCS, is a graphics code that can be used to interactively create a complex MCNP geometry. Users can define many source and tally characteristics with standard MCNP features. The time-dependent capability of the code is essential when modeling pulsed sources. Problems with neutrons, photons, and electrons as either single particle or coupled particles can be calculated with MCNP. The physics of neutron and photon transport and interactions is modeled in detail using the latest available cross-section data. A rich collections of variance reduction features can greatly increase the efficiency of a calculation. MCNP is written in FORTRAN 77 and has been run on variety of computer systems from scientific workstations to supercomputers. The next production version of MCNP will include features such as continuous-energy electron transport and a multitasking option. Areas of ongoing research of interest to the well logging community include angle biasing, adaptive Monte Carlo, improved discrete ordinates capabilities, and discrete ordinates/Monte Carlo hybrid development. Los Alamos has requested approval by the Department of Energy to create a Radiation Transport Computational Facility under their User Facility Program to increase external interactions with industry, universities, and other government organizations. 21 refs.

  14. A Novel Nuclear Recoil Calibration in the LUX Detector Using a D-D Neutron Generator

    NASA Astrophysics Data System (ADS)

    Verbus, James; LUX Collaboration

    2015-04-01

    The LUX dark matter search experiment is a 350 kg two-phase liquid/gas xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. I will describe a novel calibration of nuclear recoils (NR) in liquid xenon (LXe) performed in-situ in the LUX detector using mono-energetic 2.45 MeV neutrons produced by a D-D neutron generator. This technique was used to measure the NR charge yield in LXe (Qy) to < 1 keV recoil energy with an absolute determination of the deposited energy. The LUX Qy result is a factor of × 5 lower in energy compared to any other previous measurement in the field, and provides a significant improvement in calibration uncertainties. We also present a measurement of the NR light yield in LXe (Leff) to recoil energies as low as ~ 2 keV using the LUX D-D data. The Leff result is also lower in energy with smaller uncertainties than has been previously achieved. These absolute, ultra-low energy calibrations of the NR signal yields in LXe are a clear confirmation of the detector response used for the first LUX WIMP search analysis. Strategies for extending this calibration technique to even lower energies and smaller uncertainties will be discussed.

  15. Image processing analysis of nuclear track parameters for CR-39 detector irradiated by thermal neutron

    NASA Astrophysics Data System (ADS)

    Al-Jobouri, Hussain A.; Rajab, Mustafa Y.

    2016-03-01

    CR-39 detector which covered with boric acid (H3Bo3) pellet was irradiated by thermal neutrons from (241Am - 9Be) source with activity 12Ci and neutron flux 105 n. cm-2. s-1. The irradiation times -TD for detector were 4h, 8h, 16h and 24h. Chemical etching solution for detector was sodium hydroxide NaOH, 6.25N with 45 min etching time and 60 C˚ temperature. Images of CR-39 detector after chemical etching were taken from digital camera which connected from optical microscope. MATLAB software version 7.0 was used to image processing. The outputs of image processing of MATLAB software were analyzed and found the following relationships: (a) The irradiation time -TD has behavior linear relationships with following nuclear track parameters: i) total track number - NT ii) maximum track number - MRD (relative to track diameter - DT) at response region range 2.5 µm to 4 µm iii) maximum track number - MD (without depending on track diameter - DT). (b) The irradiation time -TD has behavior logarithmic relationship with maximum track number - MA (without depending on track area - AT). The image processing technique principally track diameter - DT can be take into account to classification of α-particle emitters, In addition to the contribution of these technique in preparation of nano- filters and nano-membrane in nanotechnology fields.

  16. Neutron irradiation induced microstructural changes in NBG-18 and IG-110 nuclear graphites

    SciTech Connect

    Karthik, Chinnathambi; Kane, Joshua; Butt, Darryl P.; Windes, William E.; Ubic, Rick

    2015-05-01

    This paper reports the neutron-irradiation-induced effects on the microstructure of NBG-18 and IG-110 nuclear graphites. The high-temperature neutron irradiation at two different irradiation conditions was carried out at the Advanced Test Reactor National User Facility at the Idaho National Laboratory. NBG-18 samples were irradiated to 1.54 dpa and 6.78 dpa at 430 °C and 678 °C respectively. IG-110 samples were irradiated to 1.91 dpa and 6.70 dpa at 451 °C and 674 °C respectively. Bright-field transmission electron microscopy imaging was used to study the changes in different microstructural components such as filler particles, microcracks, binder and quinoline-insoluble (QI) particles. Significant changes have been observed in samples irradiated to about 6.7 dpa. The closing of pre-existing microcracks was observed in both the filler and the binder phases. The binder phase exhibited substantial densification with near complete elimination of the microcracks. The QI particles embedded in the binder phase exhibited a complete microstructural transformation from rosettes to highly crystalline solid spheres. The lattice images indicate the formation of edge dislocations as well as extended line defects bridging the adjacent basal planes. The positive climb of these dislocations has been identified as the main contributor to the irradiation-induced swelling of the graphite lattice.

  17. Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

    SciTech Connect

    Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.; Schlage, Kai; Wetterskog, Erik; Bergstrom, Lennart; Hermann, Raphael P.

    2016-01-01

    The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization to 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.

  18. Nuclear Charge Radii of {sup 9,11}Li: The Influence of Halo Neutrons

    SciTech Connect

    Sanchez, R.; Ewald, G.; Dax, A.; Goette, S.; Kirchner, R.; Kluge, H.-J.; Kuehl, Th.; Wojtaszek, A.; Noertershaeuser, W.; Albers, D.; Behr, J.; Bricault, P.; Dilling, J.; Dombsky, M.; Lassen, J.; Levy, C.D.P.; Pearson, M.R.; Prime, E.J.; Ryjkov, V.; Bushaw, B.A.

    2006-01-27

    The nuclear charge radius of {sup 11}Li has been determined for the first time by high-precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a {sup 7}Li-{sup 11}Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free 2s {sup 2}S{sub 1/2}{yields}3s {sup 2}S{sub 1/2} transition. IS accuracy for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from {sup 6}Li to {sup 9}Li, and then increases from 2.217(35) to 2.467(37) fm for {sup 11}Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.

  19. Nuclear Charge Radii of 9,11Li: The Influence of Halo Neutrons

    SciTech Connect

    Sanchez, Rodolfo; Nortershauser, W.; Ewald, G; Albers, Daniel; Behr, John; Bricault, Pierre; Bushaw, Bruce A.; Dax, A; Dilling, Jens; Dombsky, Marik; Drake, Gordon W. F.; Gotte, S; Kirchner, R G.; Kluge, H J.; Lassen, J; Kuhl, T H.; Levy, C.D. P.; Pearson, Matthew; Prime, Erika; Ryjkov, Vladimir L.; Wojtaszek, A.; Yan, Z C.; Zimmerman, C.

    2006-01-27

    The nuclear charge radius of 11Li has been determined for the first time by high precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a 7Li ? 11Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free 2s 2S1=2 ! 3s 2S1=2 transition. IS precision for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from 6Li to 9Li, and then increases from 2.216(35) fm to 2.467(37) fm for 11Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.

  20. Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

    DOE PAGESBeta

    Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.; Schlage, Kai; Wetterskog, Erik; Bergstrom, Lennart; Hermann, Raphael P.

    2016-01-01

    The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization tomore » 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.« less

  1. Current Issues in Nuclear Data Evaluation Methodology: {sup 235}U Prompt Fission Neutron Spectra and Multiplicity for Thermal Neutrons

    SciTech Connect

    Trkov, A.; Capote, R.; Pronyaev, V.G.

    2015-01-15

    Issues in evaluation methodology of the prompt fission neutron spectra (PFNS) and neutron multiplicity for the thermal-neutron-induced fission of the {sup 235}U are discussed. The inconsistency between the experimental differential and integral data is addressed. By using differential data as ”shape data” good consistency was achieved between available sets of differential data. Integral dosimetry data have been used to define the PFNS slope at high outgoing neutron energies, where the quality of the differential data is poor. The inclusion into the fit of measured integral (spectrum-averaged) cross sections had a very small impact in the region where differential PFNS data are abundant and accurate, but removed the discrepancy with integral data at higher neutron emission energies. All experimental data are consistently fitted giving a PFNS average energy of 2.008 MeV. The impact on criticality prediction of the newly evaluated PFNS was tested. The highly enriched {sup 235}U solution assemblies with high leakage HEU-SOL-THERM-001 and HEU-SOL-THERM-009 benchmarks are the most sensitive to the PFNS. Criticality calculations for those solutions show a significant increase in reactivity if the average neutron energy of the fission neutrons is reduced from the ENDF/B-VI.5 value of 2.03 MeV. The proposed reduction of the PFNS average energy by 1.1% can be compensated by reducing the average number of neutrons per fission ν{sup ¯} at the thermal energy to the Gwin et al. measured value. The simple least-squares PFNS fit was confirmed by a more sophisticated combined fit of differential PFNS data for {sup 233,235}U, {sup 239}Pu and {sup 252}Cf nuclides with the generalised least-squares method using the GMA and GANDR codes.

  2. Active Interrogation of Sensitive Nuclear Material Using Laser Driven Neutron Beams

    SciTech Connect

    Favalli, Andrea; Roth, Markus

    2015-05-01

    An investigation of the viability of a laser-driven neutron source for active interrogation is reported. The need is for a fast, movable, operationally safe neutron source which is energy tunable and has high-intensity, directional neutron production. Reasons for the choice of neutrons and lasers are set forth. Results from the interrogation of an enriched U sample are shown.

  3. Many-particle theory of nuclear systems with application to neutron star matter

    NASA Technical Reports Server (NTRS)

    Chakkalakal, D. A.; Yang, C. H.

    1974-01-01

    The energy-density relation was calculated for pure neutron matter in the density range relevant for neutron stars, using four different hard-core potentials. Calculations are also presented of the properties of the superfluid state of the neutron component, along with the superconducting state of the proton component and the effects of polarization in neutron star matter.

  4. Optimization of combined delayed neutron and differential die-away prompt neutron signal detection for characterization of spent nuclear fuel assemblies

    SciTech Connect

    Blanc, Pauline; Tobin, Stephen J; Croft, Stephen; Menlove, Howard O; Swinhoe, M; Lee, T

    2010-12-02

    The Next Generation Safeguards Initiative (NGSI) of the U.S. Department of Energy (DOE) has funded multiple laboratories and universities to develop a means to accurately quantify the Plutonium (Pu) mass in spent nuclear fuel assemblies and ways to also detect potential diversion of fuel pins. Delayed Neutron (DN) counting provides a signature somewhat more sensitive to {sup 235}U than Pu while Differential Die-Away (DDA) is complementary in that it has greater sensitivity to Pu. The two methods can, with care, be combined into a single instrument which also provides passive neutron information. Individually the techniques cannot robustly quantify the Pu content but coupled together the information content in the signatures enables Pu quantification separate to the total fissile content. The challenge of merging DN and DDA, prompt neutron (PN) signal, capabilities in the same design is the focus of this paper. Other possibilities also suggest themselves, such as a direct measurement of the reactivity (multiplication) by either the boost in signal obtained during the active interrogation itself or by the extension of the die-away profile. In an early study, conceptual designs have been modeled using a neutron detector comprising fission chambers or 3He proportional counters and a {approx}14 MeV neutron Deuterium-Tritium (DT) generator as the interrogation source. Modeling was performed using the radiation transport code Monte Carlo N-Particles eXtended (MCNPX). Building on this foundation, the present paper quantifies the capability of a new design using an array of {sup 3}He detectors together with fission chambers to optimize both DN and PN detections and active characterization, respectively. This new design was created in order to minimize fission in {sup 238}U (a nuisance DN emitter), to use a realistic neutron generator, to reduce the cost and to achieve near spatial interrogation and detection of the DN and PN, important for detection of diversion, all within

  5. Basic results of investigations of scission neutrons in nuclear fission at low excitation energies

    SciTech Connect

    Petrov, G. A. Gagarski, A. M.; Guseva, I. S.; Sokolov, V. E.; Val'ski, G. V.; Vorobiev, A. S.; Krinitcin, D. O.; Shcherbakov, O. A.; Nikolaev, D. V.; Pleva, Yu. S.; Petrova, V. I.; Zavarukhina, T. A.

    2008-07-15

    To estimate the main characteristics of neutrons emitted shortly before the scission of a fissioning nucleus, various experiments sensitive to the presence of these scission neutrons in thermal-neutron-induced fission of {sup 235}U and spontaneous fission of {sup 252}Cf were performed. The results of the experiments were analyzed within theoretical calculations allowing for various possible neutron-emission mechanisms, including the possibility of the emergence of neutrons from the scission of a nucleus.

  6. Advanced sample environments for in situ neutron diffraction studies of nuclear materials

    NASA Astrophysics Data System (ADS)

    Reiche, Helmut Matthias

    Generation IV nuclear reactor concepts, such as the supercritical-water-cooled nuclear reactor (SCWR), are actively researched internationally. Operating conditions above the critical point of water (374°C, 22.1 MPa) and fuel core temperature that potentially exceed 1850°C put a high demand on the surrounding materials. For their safe application, it is essential to characterize and understand the material properties on an atomic scale such as crystal structure and grain orientation (texture) changes as a function of temperature and stress. This permits the refinement of models predicting the macroscopic behavior of the material. Neutron diffraction is a powerful tool in characterizing such crystallographic properties due to their deep penetration depth into condensed matter. This leads to the ability to study bulk material properties, as opposed to surface effects, and allows for complex sample environments to study e.g. the individual contributions of thermo-mechanical processing steps during manufacturing, operating or accident scenarios. I present three sample environments for in situ neutron diffraction studies that provide such crystallographic information and have been successfully commissioned and integrated into the user program of the High Pressure -- Preferred Orientation (HIPPO) diffractometer at the Los Alamos Neutron Science Center (LANSCE) user facility. I adapted a sample changer for reliable and fast automated texture measurements of multiple specimens. I built a creep furnace combining a 2700 N load frame with a resistive vanadium furnace, capable of temperatures up to 1000°C, and manipulated by a pair of synchronized rotation stages. This combination allows following deformation and temperature dependent texture and strain evolutions in situ. Utilizing the presented sample changer and creep furnace we studied pressure tubes made of Zr-2.5wt%Nb currently employed in CANDURTM nuclear reactors and proposed for future SCWRs, acting as the primary

  7. Experimental approach to neutron stars

    SciTech Connect

    Leifels, Yvonne

    2014-05-09

    The equation of state (EOS) of nuclear matter is of fundamental importance in many areas of nuclear physics and astrophysics In the laboratory, there are different means to study the nuclearmatter equation of state and its density dependence in particular: nuclear masses, neutron skins, pygmy resonance, and nuclear structure at the drip line give access to nuclear matter properties at densities lower than and at saturation density ρ0. Heavy ion reactions at energies above 0.1 AGeV are the only means to study nuclear matter at densities larger than normal nuclear matter density ρ0. In the beamenergy range of 0.1 to 2A GeV nuclear matter is compressed upto three times ρ0. Access to nuclear matter properties is achieved by simulating nuclear collisions by means of microscopic transport codes, or statistical or hydrodynamicalmodels. Characteristics of heavy-ion collisions are discussed, and experimental observables which allow to constrain nuclear matter properties by comparing experimental results with those of transport codes are presented. Special emphasis will be given to the density dependence of the symmetry energy which is the most relevant connection between neutron stars and heavy ion collisions.

  8. Experimental approach to neutron stars

    NASA Astrophysics Data System (ADS)

    Leifels, Yvonne

    2014-05-01

    The equation of state (EOS) of nuclear matter is of fundamental importance in many areas of nuclear physics and astrophysics In the laboratory, there are different means to study the nuclearmatter equation of state and its density dependence in particular: nuclear masses, neutron skins, pygmy resonance, and nuclear structure at the drip line give access to nuclear matter properties at densities lower than and at saturation density ρ0. Heavy ion reactions at energies above 0.1 AGeV are the only means to study nuclear matter at densities larger than normal nuclear matter density ρ0. In the beamenergy range of 0.1 to 2A GeV nuclear matter is compressed upto three times ρ0. Access to nuclear matter properties is achieved by simulating nuclear collisions by means of microscopic transport codes, or statistical or hydrodynamicalmodels. Characteristics of heavy-ion collisions are discussed, and experimental observables which allow to constrain nuclear matter properties by comparing experimental results with those of transport codes are presented. Special emphasis will be given to the density dependence of the symmetry energy which is the most relevant connection between neutron stars and heavy ion collisions.

  9. Analysis of optical density data generated from neutron radiographs of uranium-plutonium mixed oxide fuel pellets inside sealed nuclear fuel pins

    NASA Astrophysics Data System (ADS)

    Panakkal, J. P.; Ghosh, J. K.; Roy, P. R.

    1986-03-01

    A quantitative analysis of neutron radiographs of welded nuclear fuel pins containing uranium-plutonium mixed oxide fuel pellets has been carried out to obtain a simple model for the transmission of neutrons through fuel pins during neutron radiography. The optical density data obtained by detailed microdensitometer scanning across the image of pellets of varying plutonium enrichment has been correlated to the product of the macroscopic neutron cross section and the distance traversed by the neutrons. Based on the experimental data, a simple model which can be applied to fuel pins of different dimensions and plutonium enrichment has been derived.

  10. Cynaropicrin from Cynara scolymus L. suppresses photoaging of skin by inhibiting the transcription activity of nuclear factor-kappa B.

    PubMed

    Tanaka, Yuka Tsuda; Tanaka, Kiyotaka; Kojima, Hiroyuki; Hamada, Tomoji; Masutani, Teruaki; Tsuboi, Makoto; Akao, Yukihiro

    2013-01-15

    Aging of skin is characterized by skin wrinkling, laxity, and pigmentation induced by several environmental stress factors. Histological changes during the photoaging of skin include hyperproliferation of keratinocytes and melanocytes causing skin wrinkles and pigmentation. Nuclear factor kappa B (NF-κB) is one of the representative transcription factors active in conjunction with inflammation. NF-κB is activated by stimulation such as ultraviolet rays and inflammatory cytokines and induces the expression of various genes such as those of basic fibroblast growth factor (bFGF) and matrix metalloprotease-1 (MMP-1). We screened several plant extracts for their possible inhibitory effect on the transcriptional activity of NF-κB. One of them, an extract from Cynara scolymus L., showed a greatest effect on the suppression of NF-κB transactivation. As a result, we found that cynaropicrin, which is a sesquiterpene lactone, inhibited the NF-κB-mediated transactivation of bFGF and MMP-1. Furthermore, it was confirmed that in an in vivo mouse model cynaropicrin prevented skin photoaging processes leading to the hyperproliferation of keratinocytes and melanocytes. These findings taken together indicate that cynaropicrin is an effective antiphotoaging agent that acts by inhibiting NF-κB-mediated transactivation. PMID:23232059

  11. Cynaropicrin from Cynara scolymus L. suppresses photoaging of skin by inhibiting the transcription activity of nuclear factor-kappa B.

    PubMed

    Tanaka, Yuka Tsuda; Tanaka, Kiyotaka; Kojima, Hiroyuki; Hamada, Tomoji; Masutani, Teruaki; Tsuboi, Makoto; Akao, Yukihiro

    2013-01-15

    Aging of skin is characterized by skin wrinkling, laxity, and pigmentation induced by several environmental stress factors. Histological changes during the photoaging of skin include hyperproliferation of keratinocytes and melanocytes causing skin wrinkles and pigmentation. Nuclear factor kappa B (NF-κB) is one of the representative transcription factors active in conjunction with inflammation. NF-κB is activated by stimulation such as ultraviolet rays and inflammatory cytokines and induces the expression of various genes such as those of basic fibroblast growth factor (bFGF) and matrix metalloprotease-1 (MMP-1). We screened several plant extracts for their possible inhibitory effect on the transcriptional activity of NF-κB. One of them, an extract from Cynara scolymus L., showed a greatest effect on the suppression of NF-κB transactivation. As a result, we found that cynaropicrin, which is a sesquiterpene lactone, inhibited the NF-κB-mediated transactivation of bFGF and MMP-1. Furthermore, it was confirmed that in an in vivo mouse model cynaropicrin prevented skin photoaging processes leading to the hyperproliferation of keratinocytes and melanocytes. These findings taken together indicate that cynaropicrin is an effective antiphotoaging agent that acts by inhibiting NF-κB-mediated transactivation.

  12. Prompt gamma ray diagnostics and enhanced hadron-therapy using neutron-free nuclear reactions

    NASA Astrophysics Data System (ADS)

    Giuffrida, L.; Margarone, D.; Cirrone, G. A. P.; Picciotto, A.; Cuttone, G.; Korn, G.

    2016-10-01

    We propose a series of simulations about the potential use of Boron isotopes to trigger neutron-free (aneutronic) nuclear reactions in cancer cells through the interaction with an incoming energetic proton beam, thus resulting in the emission of characteristic prompt gamma radiation (429 keV, 718 keV and 1435 keV). Furthermore assuming that the Boron isotopes are absorbed in cancer cells, the three alpha-particles produced in each p-11B aneutronic nuclear fusion reactions can potentially result in the enhancement of the biological dose absorbed in the tumor region since these multi-MeV alpha-particles are stopped inside the single cancer cell, thus allowing to spare the surrounding tissues. Although a similar approach based on the use of 11B nuclei has been proposed in [Yoon et al. Applied Physics Letters 105, 223507 (2014)], our work demonstrate, using Monte Carlo simulations, the crucial importance of the use of 10B nuclei (in a solution containing also 11B) for the generation of prompt gamma-rays, which can be applied to medical imaging. In fact, we demonstrate that the use of 10B nuclei can enhance the intensity of the 718 keV gamma-ray peak more than 30 times compared to the solution containing only 11B nuclei. A detailed explanation of the origin of the different prompt gamma-rays, as well as of their application as real-time diagnostics during a potential cancer treatment, is here discussed.

  13. Isotope identification as a part of the decommissioning of San Diego State University`s Texas Nuclear neutron generator

    SciTech Connect

    Taylor, D.

    1997-07-01

    The Department of Physics at San Diego State University has maintained a Neutron Generator facility in room P-32C since the mid 1960`s. This facility has provided students and faculty with a resource for the study of neutron interactions with matter, such as activation analysis, flux determinations, cross section determinations and shielding studies. The model 9500 was built by Texas Nuclear Research in the early 1960`s, and could be used for either photon or neutron generation, depending on the source ions introduced into the accelerator`s plasma bottle and the target material. In February of 1988, the Texas Nuclear Research neutron generator was replaced by a unit manufactured by Kaman Sciences Corporation. The Texas Nuclear unit was then removed and stored for later disassembly and disposal. In the summer of 1993, the neutron generator was disassembled into three large sections consisting of the titanium-tritide target, the oil diffusion pump and the corona shield/accelerator tube assembly. The target was packaged and stored in room P-33A and the other 2 assemblies were wrapped in plastic for storage. In June of 1995 the neutron generator was further disassembled to enable storage in 55 gallon drums and thoroughly surveyed for loose surface contamination. Openings on the disassembled hardware components were closed off using either duct tape or bolted stainless steel flanges to prevent the possible spread of contamination. Significant levels of removable surface contamination could be found on system internal and some external surfaces, up to five hundred thousand disintegrations per minute. Initial analysis of the removable contamination using aluminum absorbers and a Geiger-Meuller tube indicated beta particle or possibly photon emitters with an energy of approximately 180 keV. This apparent radiation energy conflicted with what one would be expected to find, given knowledge of the source material and the possible neutron activated products that would be

  14. Neutron imaging methods for the investigation of energy related materials. Fuel cells, battery, hydrogen storage and nuclear fuel

    NASA Astrophysics Data System (ADS)

    Lehmann, Eberhard H.; Boillat, Pierre; Kaestner, Anders; Vontobel, Peter; Mannes, David

    2015-10-01

    After a short explanation of the state-of-the-art in the field of neutron imaging we give some examples how energy related materials can be studied successfully. These are in particular fuel cell studies, battery research approaches, the storage of hydrogen, but also some investigations with nuclear fuel components. The high contrast for light isotopes like H-1, Li-6 or B-10 are used to trace low amounts of material even within compact sealing of metals which are relatively transparent for neutrons at the same time.

  15. Radiogenic lead with dominant content of {sup 208}Pb: New coolant and neutron moderator for innovative nuclear reactors

    SciTech Connect

    Shmelev, A. N.; Kulikov, G. G.; Kryuchkov, E. F.; Apse, V. A.; Kulikov, E. G.

    2012-07-01

    The advantages of radiogenic lead with dominant content of {sup 208}Pb as a reactor coolant with respect to natural lead are caused by unique nuclear properties of {sup 208}Pb which is a double-magic nucleus with closed proton and neutron shells. This results in significantly lower micro cross section and resonance integral of radiative neutron capture by {sup 208}Pb than those for numerous light neutron moderators. The extremely weak ability of {sup 208}Pb to absorb neutrons results in the following effects. Firstly, neutron moderating factor (ratio of scattering to capture cross sections) is larger than that for graphite and light water. Secondly, age and diffusion length of thermal neutrons are larger than those for graphite, light and heavy water. Thirdly, neutron lifetime in {sup 208}Pb is comparable with that for graphite, beryllium and heavy water what could be important for safe reactor operation. The paper presents some results obtained in neutronics and thermal-hydraulics evaluations of the benefits from the use of radiogenic lead with dominant content of {sup 208}Pb instead of natural lead as a coolant of fast breeder reactors. The paper demonstrates that substitution of radiogenic lead for natural lead can offer the following benefits for operation of fast breeder reactors. Firstly, improvement of the reactor safety thanks to the better values of coolant temperature reactivity coefficient and, secondly, improvement of some thermal-hydraulic reactor parameters. Radiogenic lead can be extracted from thorium sludge without isotope separation as {sup 208}Pb is a final isotope in the decay chain of {sup 232}Th. (authors)

  16. Relativistic effective interaction for nuclei, giant resonances, and neutron stars

    SciTech Connect

    Fattoyev, F. J.; Piekarewicz, J.; Horowitz, C. J.; Shen, G.

    2010-11-15

    Nuclear effective interactions are useful tools in astrophysical applications especially if one can guide the extrapolations to the extremes regions of isospin and density that are required to simulate dense, neutron-rich systems. Isospin extrapolations may be constrained in the laboratory by measuring the neutron skin thickness of a heavy nucleus, such as {sup 208}Pb. Similarly, future observations of massive neutron stars will constrain the extrapolations to the high-density domain. In this contribution we introduce a new relativistic effective interaction that is simultaneously constrained by the properties of finite nuclei, their collective excitations, and neutron-star properties. By adjusting two of the empirical parameters of the theory, one can efficiently tune the neutron skin thickness of {sup 208}Pb and the maximum neutron-star mass. We illustrate this procedure in response to the recent interpretation of x-ray observations by Steiner, Lattimer, and Brown that suggests that the FSUGold effective interaction predicts neutron-star radii that are too large and a maximum stellar mass that is too small. The new effective interaction is fitted to a neutron skin thickness in {sup 208}Pb of only R{sub n}-R{sub p}=0.16 fm and yields a moderately large maximum neutron-star mass of 1.94 M{sub {center_dot}}.

  17. Neutron and Gamma-Ray Kerma Factors Based on LLNL Nuclear Data Files.

    1991-07-08

    Version 00 Kerma factors are used extensively in biomedical applications. Specifically, neutron kerma factors are used in determining heating in materials of interest from neutron-induced reactions in fission or fusion power applications.

  18. Performance of the electronic personal dosemeter for neutron 'Saphydose-N' at different workplaces of nuclear facilities.

    PubMed

    Lahaye, T; Chau, Q; Ménard, S; Lacoste, V; Muller, H; Luszik-Bhadra, M; Reginatto, M; Bruguier, P

    2006-01-01

    This paper mainly aims at presenting the measurements and the results obtained with the electronic personal neutron dosemeter Saphydose-N at different facilities. Three campaigns were led in the frame of the European contract EVIDOS ('Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields'). The first one consisted in the measurements at the IRSN French research laboratory in reference neutron fields generated by a thermal facility (SIGMA), radionuclide ISO sources ((241)AmBe; (252)Cf; (252)Cf(D(2)O)\\Cd) and a realistic spectrum (CANEL/T400). The second one was performed at the Krümmel Nuclear Power Plant (Germany) close to the boiling water reactor and to a spent fuel transport cask. The third one was realised at Mol (Belgium), at the VENUS Research Reactor and at Belgonucléaire, a fuel processing factory.

  19. Heavy ion collisions with A = 10/sup 57/: Aspects of nuclear stability and the nuclear equation of state in coalescing neutron-star binary systems

    SciTech Connect

    Mathews, G.J.; Wilson, J.R.; Evans, C.R.; Detweiler, S.L.

    1987-12-01

    The dynamics of the final stages of the coalescence of two neturon stars (such as the binary pulsar PSR 1913+16) is an unsolved problem in astrophysics. Such systems are probably efficient generators of gravitational radiation, and may be significant contributors to heavy-element nucleosynthesis. The input physics for the study of such systems is similar to that required for the strudy of heavy-ion collision hydrodynamics; e.g., a finite temperature nuclear equation of state, properties of nuclei away from stability, etc. We discuss the development of a relativistic hydrodynamics code in three spatial dimensions for the purpose of studying such neutron-star systems. The properties of the mass-radius relation (determined by the nuclear equation of state) may lead to a proposed mechanism by which hot, highly neutronized matter is ejected from the coalescing stars. This material is photodisintegrated into a free (mostly) neutron gas which may subsequently experience rapid-neutron capture (r-process) nucleosynthesis. 15 refs., 4 figs.

  20. Laser Intertial Fusion Energy: Neutronic Design Aspects of a Hybrid Fusion-Fission Nuclear Energy System

    SciTech Connect

    Kramer, Kevin James

    2010-04-08

    having a packing fraction of 20% in 2 cm diameter fuel pebbles. The fission blanket is cooled by the same radial flibe flow that travels through perforated ODS walls to the reflector blanket. This reflector blanket is 75 cm thick comprised of 2 cm diameter graphite pebbles cooled by flibe. The flibe extraction plenum surrounds the reflector bed. Detailed neutronics designs studies are performed to arrive at the described design. The LFFH engine thermal power is controlled using a technique of adjusting the 6Li/7Li enrichment in the primary and secondary coolants. The enrichment adjusts system thermal power in the design by increasing tritium production while reducing fission. To perform the simulations and design of the LFFH engine, a new software program named LFFH Nuclear Control (LNC) was developed in C++ to extend the functionality of existing neutron transport and depletion software programs. Neutron transport calculations are performed with MCNP5. Depletion calculations are performed using Monteburns 2.0, which utilizes ORIGEN 2.0 and MCNP5 to perform a burnup calculation. LNC supports many design parameters and is capable of performing a full 3D system simulation from initial startup to full burnup. It is able to iteratively search for coolant 6Li enrichments and resulting material compositions that meet user defined performance criteria. LNC is utilized throughout this study for time dependent simulation of the LFFH engine. Two additional methods were developed to improve the computation efficiency of LNC calculations. These methods, termed adaptive time stepping and adaptive mesh refinement were incorporated into a separate stand alone C++ library name the Adaptive Burnup Library (ABL). The ABL allows for other client codes to call and utilize its functionality. Adaptive time stepping is useful for automatically maximizing the size of the depletion time step while maintaining a desired level of accuracy. Adaptive meshing allows for analysis

  1. Charge radii and nuclear moments of neutron-deficient potassium isotopes

    NASA Astrophysics Data System (ADS)

    Minamisono, K.; Barquest, B. R.; Bollen, G.; Hughes, M.; Strum, R.; Tarazona, D.; Asberry, H. B.; Cooper, K.; Hammerton, K.; Klose, A.; Mantica, P. F.; Morrissey, D. J.; Geppert, Ch.; Harris, J.; Ringle, R.; Rodriguez, J. A.; Rossi, D. M.; Ryder, C. A.; Smith, A.; Schwarz, S.; Sumithrarachchi, C.

    2014-09-01

    The monotonic change of charge radii of K isotopes across N = 20 suggests a reduction of the shell gap. A systematic study of the charge radii and ground state magnetic and quadrupole moments of neutron-deficient 35-37K isotopes is underway at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU to investigate the anomalous trend in charge radii. The K isotopes were produced by fragmentation of a 40Ca beam, thermalized in a linear gas cell, extracted at an energy of 30 keV, and transported to BECOLA. The K ion beam was cooled and bunched, and neutralized in a Na vapor cell. Laser-induced fluorescence was detected as a function of the Doppler-tuned laser frequency and time relative to the release of the beam bunch. The beta-NMR technique was used to determine ground-state nuclear moments, where hyperfine splittings are too small to resolve using collinear laser spectroscopy. The monotonic change of charge radii of K isotopes across N = 20 suggests a reduction of the shell gap. A systematic study of the charge radii and ground state magnetic and quadrupole moments of neutron-deficient 35-37K isotopes is underway at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU to investigate the anomalous trend in charge radii. The K isotopes were produced by fragmentation of a 40Ca beam, thermalized in a linear gas cell, extracted at an energy of 30 keV, and transported to BECOLA. The K ion beam was cooled and bunched, and neutralized in a Na vapor cell. Laser-induced fluorescence was detected as a function of the Doppler-tuned laser frequency and time relative to the release of the beam bunch. The beta-NMR technique was used to determine ground-state nuclear moments, where hyperfine splittings are too small to resolve using collinear laser spectroscopy. This work was supported in part by NSF Grant No. PHY-11-02511.

  2. Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: Dependence in the binary parameters

    NASA Astrophysics Data System (ADS)

    Foucart, Francois; Deaton, M. Brett; Duez, Matthew D.; O'Connor, Evan; Ott, Christian D.; Haas, Roland; Kidder, Lawrence E.; Pfeiffer, Harald P.; Scheel, Mark A.; Szilagyi, Bela

    2014-07-01

    We present a first exploration of the results of neutron star-black hole mergers using black hole masses in the most likely range of 7M⊙-10M⊙, a neutrino leakage scheme, and a modeling of the neutron star material through a finite-temperature nuclear-theory based equation of state. In the range of black hole spins in which the neutron star is tidally disrupted (χBH≳0.7), we show that the merger consistently produces large amounts of cool (T ≲1 MeV), unbound, neutron-rich material (Mej˜0.05M⊙-0.20M⊙). A comparable amount of bound matter is initially divided between a hot disk (Tmax˜15 MeV) with typical neutrino luminosity of Lν˜1053 erg /s, and a cooler tidal tail. After a short period of rapid protonization of the disk lasting ˜10 ms, the accretion disk cools down under the combined effects of the fall-back of cool material from the tail, continued accretion of the hottest material onto the black hole, and neutrino emission. As the temperature decreases, the disk progressively becomes more neutron rich, with dimmer neutrino emission. This cooling process should stop once the viscous heating in the disk (not included in our simulations) balances the cooling. These mergers of neutron star-black hole binaries with black hole masses of MBH˜7M⊙-10M⊙, and black hole spins high enough for the neutron star to disrupt provide promising candidates for the production of short gamma-ray bursts, of bright infrared postmerger signals due to the radioactive decay of unbound material, and of large amounts of r-process nuclei.

  3. Pulsed and monoenergetic beams for neutron cross-section measurements using activation and scattering techniques at Triangle Universities Nuclear Laboratory

    NASA Astrophysics Data System (ADS)

    Hutcheson, A.; Angell, C. T.; Becker, J. A.; Boswell, M.; Crowell, A. S.; Dashdorj, D.; Fallin, B.; Fotiades, N.; Howell, C. R.; Karwowski, H. J.; Kelley, J. H.; Kiser, M.; Macri, R. A.; Nelson, R. O.; Pedroni, R. S.; Tonchev, A. P.; Tornow, W.; Vieira, D. J.; Weisel, G. J.; Wilhelmy, J. B.

    2007-08-01

    In support of the Stewardship Science Academic Alliances initiative, an experimental program has been developed at Triangle Universities Nuclear Laboratory (TUNL) to measure (n,xn) cross-sections with both in-beam and activation techniques with the goal of improving the partial cross-section database for the NNSA Stockpile Stewardship Program. First experimental efforts include excitation function measurements on 235,238U and 241Am using pulsed and monoenergetic neutron beams with En = 5-15 MeV. Neutron-induced partial cross-sections were measured by detecting prompt γ rays from the residual nuclei using various combinations of clover and planar HPGe detectors in the TUNL shielded neutron source area. Complimentary activation measurements using DC neutron beams have also been performed in open geometry in our second target area. The neutron-induced activities were measured in the TUNL low-background counting area. In this presentation, we include detailed information about the irradiation procedures and facilities and preliminary data on first measurements using this capability.

  4. Determination of fast neutron flux distribution in irradiation sites of the Malaysian Nuclear Agency research reactor.

    PubMed

    Yavar, A R; Sarmani, S B; Wood, A K; Fadzil, S M; Radir, M H; Khoo, K S

    2011-05-01

    Determination of thermal to fast neutron flux ratio (f(fast)) and fast neutron flux (ϕ(fast)) is required for fast neutron reactions, fast neutron activation analysis, and for correcting interference reactions. The f(fast) and subsequently ϕ(fast) were determined using the absolute method. The f(fast) ranged from 48 to 155, and the ϕ(fast) was found in the range 1.03×10(10)-4.89×10(10) n cm(-2) s(-1). These values indicate an acceptable conformity and applicable for installation of the fast neutron facility at the MNA research reactor.

  5. The Transmutation of Nuclear Waste in the Two-Zone Subcritical System Driven by High- Intensity Neutron Generator - 12098

    SciTech Connect

    Babenko, V.O.; Gulik, V.I.; Pavlovych, V.M.

    2012-07-01

    The main problems of transmutation of high-level radioactive waste (minor actinides and long-lived fission products) are considered in our work. The range of radioactive waste of nuclear power is analyzed. The conditions under which the transmutation of radioactive waste will be most effective are analyzed too. The modeling results of a transmutation of the main radioactive isotopes are presented and discussed. The transmutation of minor actinides and long-lived fission products are modeled in our work (minor actinides - Np-237, Am-241, Am-242, Am-243, Cm-244, Cm-245; long-lived fission products - I-129, Tc-99). The two-zone subcritical system is calculated with help of different neutron-physical codes (MCNP, Scale, Montebarn, Origen). The ENDF/B-VI nuclear data library used in above calculations. Thus, radioactive wastes can be divided into two main groups that need to be transmuted. The minor actinides form the first group and the long-lived fission products form the second one. For the purpose of effective transmutation these isotopes must be extracted from the spent nuclear fuel with the help of either PUREX technology or pyrometallurgical technology. The two-zone reactor system with fast and thermal regions is more effective for nuclear waste transmutation than the one-zone reactor. Modeling results show that nearly all radioactive wastes can be transmuted in the two-zone subcritical system driven by a high-intensity neutron generator with the external neutron source strength of 1.10{sup 13} n/sec. Obviously, transmutation rate will increase with a rise of the external neutron source strength. From the results above we can also see that the initial loading of radioactive isotopes into the reactor system should exceed by mass those isotopes that are finally produced. (authors)

  6. MCNPX simulations of the silicon carbide semiconductor detector response to fast neutrons from D-T nuclear reaction

    NASA Astrophysics Data System (ADS)

    Sedlačková, Katarína; Šagátová, Andrea; Zat'ko, Bohumír; Nečas, Vladimír; Solar, Michael; Granja, Carlos

    2016-09-01

    Silicon Carbide (SiC) has been long recognized as a suitable semiconductor material for use in nuclear radiation detectors of high-energy charged particles, gamma rays, X-rays and neutrons. The nuclear interactions occurring in the semiconductor are complex and can be quantified using a Monte Carlo-based computer code. In this work, the MCNPX (Monte Carlo N-Particle eXtended) code was employed to support detector design and analysis. MCNPX is widely used to simulate interaction of radiation with matter and supports the transport of 34 particle types including heavy ions in broad energy ranges. The code also supports complex 3D geometries and both nuclear data tables and physics models. In our model, monoenergetic neutrons from D-T nuclear reaction were assumed as a source of fast neutrons. Their energy varied between 16 and 18.2 MeV, according to the accelerating voltage of the deuterons participating in D-T reaction. First, the simulations were used to calculate the optimum thickness of the reactive film composed of High Density PolyEthylene (HDPE), which converts neutral particles to charged particles and thusly enhancing detection efficiency. The dependency of the optimal thickness of the HDPE layer on the energy of the incident neutrons has been shown for the inspected energy range. Further, from the energy deposited by secondary charged particles and recoiled ions, the detector response was modeled and the effect of the conversion layer on detector response was demonstrated. The results from the simulations were compared with experimental data obtained for a detector covered by a 600 and 1300 μm thick conversion layer. Some limitations of the simulations using MCNPX code are also discussed.

  7. Statistical description of complex nuclear phases in supernovae and proto-neutron stars

    NASA Astrophysics Data System (ADS)

    Raduta, Ad. R.; Gulminelli, F.

    2010-12-01

    We develop a phenomenological statistical model for dilute star matter at finite temperature, in which free nucleons are treated within a mean-field approximation and nuclei are considered to form a loosely interacting cluster gas. Its domain of applicability, that is, baryonic densities ranging from about ρ>108 g/cm3 to normal nuclear density, temperatures between 1 and 20 MeV, and proton fractions between 0.5 and 0, makes it suitable for the description of baryonic matter produced in supernovae explosions and proto-neutron stars. The first finding is that, contrary to the common belief, the crust-core transition is not first order, and for all subsaturation densities matter can be viewed as a continuous fluid mixture between free nucleons and massive nuclei. As a consequence, the equations of state and the associated observables do not present any discontinuity over the whole thermodynamic range. We further investigate the nuclear matter composition over a wide range of densities and temperatures. At high density and temperature our model accounts for a much larger mass fraction bound in medium nuclei with respect to traditional approaches as Lattimer-Swesty, with sizable consequences on the thermodynamic quantities. The equations of state agree well with the presently used EOS only at low temperatures and in the homogeneous matter phase, while important differences are present in the crust-core transition region. The correlation among the composition of baryonic matter and neutrino opacity is finally discussed, and we show that the two problems can be effectively decoupled.

  8. Detection of special nuclear materials using prompt gamma-rays from fast and slow neutron-induced fission

    NASA Astrophysics Data System (ADS)

    Kane, Steven Ze

    A complete system has been simulated using experimentally obtained input parameters for the detection of special nuclear materials (SNM). A variation of the associated particle imaging (API) technique, referred to as reverse associated particle imaging detection (RAPID), has been developed in the context of detecting 5-kg spherical samples of U-235 in cargo containers uniformly filled with wood (low-Z) or iron (high-Z) at densities ranging from 0.1 g/cm3 to 0.4 g/cm3, the maximal density for a uniformly fully loaded 40-ft standard cargo container. In addition, samples were located at the center of a given container to study worst-case scenarios. The RAPID technique allows for the interrogation of containers at neutron production rates between 1x108 neutrons/s and 4x108 neutrons/s, depending on cargo material and density. These rates are low enough to prevent transmutation of materials in cargo and radiation safety hazards are limited. The merit of performance for the system is the time to detect the threat material with 95% probability of detection and 10-4 false positive rate per interrogated voxel of cargo. The detection of 5-kg of U-235 was chosen because this quantity of material is near the lower limit of the amount of special nuclear material that might be used in a nuclear weapon. This is in contrast to the 25-kg suggested sensitivity proposed by the International Atomic Energy Agency (IAEA).

  9. A numerical simulation package for analysis of neutronics and thermal fluids of space nuclear power and propulsion systems

    SciTech Connect

    Anghaie, S.; Feller, G.J. ); Peery, S.D.; Parsley, R.C. )

    1993-01-20

    A system of computer codes for engineering simulation and in-depth analysis of nuclear and thermal fluid design of nuclear thermal rockets is developed. The computational system includes a neutronic solver package, a thermal fluid solver package and a propellant and materials property package. The Rocket Engine Transient Simulation (ROCETS) system code is incorporated with computational modules specific to nuclear powered engines. ROCETS features a component based performance architecture that interfaces component modules into the user designed configuration, interprets user commands, creates an executable FORTRAN computer program, and executes the program to provide output to the user. Basic design features of the Pratt Whitney XNR2000 nuclear rocket concept and its operational performance are analyzed and simulated.

  10. Nuclear Rocket Facility Decommissioning Project: Controlled Explosive Demolition of Neutron-Activated Shield Wall

    SciTech Connect

    Michael R. Kruzic

    2008-06-01

    Located in Area 25 of the Nevada Test Site (NTS), the Test Cell A (TCA) Facility (Figure 1) was used in the early to mid-1960s for testing of nuclear rocket engines, as part of the Nuclear Rocket Development Program, to further space travel. Nuclear rocket testing resulted in the activation of materials around the reactors and the release of fission products and fuel particles. The TCA facility, known as Corrective Action Unit 115, was decontaminated and decommissioned (D&D) from December 2004 to July 2005 using the Streamlined Approach for Environmental Restoration (SAFER) process, under the Federal Facility Agreement and Consent Order. The SAFER process allows environmental remediation and facility closure activities (i.e., decommissioning) to occur simultaneously, provided technical decisions are made by an experienced decision maker within the site conceptual site model. Facility closure involved a seven-step decommissioning strategy. First, preliminary investigation activities were performed, including review of process knowledge documentation, targeted facility radiological and hazardous material surveys, concrete core drilling and analysis, shield wall radiological characterization, and discrete sampling, which proved to be very useful and cost-effective in subsequent decommissioning planning and execution and worker safety. Second, site setup and mobilization of equipment and personnel were completed. Third, early removal of hazardous materials, including asbestos, lead, cadmium, and oil, was performed ensuring worker safety during more invasive demolition activities. Process piping was to be verified void of contents. Electrical systems were de-energized and other systems were rendered free of residual energy. Fourth, areas of high radiological contamination were decontaminated using multiple methods. Contamination levels varied across the facility. Fixed beta/gamma contamination levels ranged up to 2 million disintegrations per minute (dpm)/100

  11. Theoretical study on neutron distribution of 208Pb by parity-violating electron scattering

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Zhang, Cun; Ren, Zhong-Zhou; Xu, Chang

    2016-03-01

    The precise determination of neutron distribution has important implications for both nuclear structure and nuclear astrophysics. The purpose of this paper is to study the characteristics of neutron distribution of 208Pb by parity-violating electron scattering (PVS). Parity-violating asymmetries of 208Pb with different types of neutron skins are systematically calculated and compared with the experimental data of PREx. The results indicate that the PVS experiments are very sensitive to the nuclear neutron distributions. From further PVS measurements, detailed information on nuclear neutron distributions can be extracted. Supported by the National Natural Science Foundation of China (11505292, 11175085, 11235001, 11447226), by the Shandong Provincial Natural Science Foundation, China (BS2014SF007), by the Fundamental Research Funds for the Central Universities (15CX02072A, 15CX02070A, 15CX05026A, 13CX10022A, 14CX02157A).

  12. A compact neutron beam generator system designed for prompt gamma nuclear activation analysis.

    PubMed

    Ghassoun, J; Mostacci, D

    2011-08-01

    In this work a compact system was designed for bulk sample analysis using the technique of PGNAA. The system consists of (252)Cf fission neutron source, a moderator/reflector/filter assembly, and a suitable enclosure to delimit the resulting neutron beam. The moderator/reflector/filter arrangement has been optimised to maximise the thermal neutron component useful for samples analysis with a suitably low level of beam contamination. The neutron beam delivered by this compact system is used to irradiate the sample and the prompt gamma rays produced by neutron reactions within the sample elements are detected by appropriate gamma rays detector. Neutron and gamma rays transport calculations have been performed using the Monte Carlo N-Particle transport code (MCNP5).

  13. Many-particle theory of nuclear systems with application to neutron star matter

    NASA Technical Reports Server (NTRS)

    Chakkalakal, D. A.; Yang, C.

    1973-01-01

    The research is reported concerning energy-density relation for the normal state of neutron star matter, and the effects of superfluidity and polarization on neutron star matter. Considering constraints on variation, and the theory of quantum fluids, three methods for calculating the energy-density range are presented. The effects of polarization on neutron star structure, and polarization effects on condensation and superfluid-state energy are discussed.

  14. Detection of fast neutrons from D-T nuclear reaction using a 4H-SiC radiation detector

    NASA Astrophysics Data System (ADS)

    Zatko, Bohumir; Sagatova, Andrea; Sedlackova, Katarina; Necas, Vladimir; Dubecky, Frantisek; Solar, Michael; Granja, Carlos

    2016-09-01

    The particle detector based on a high purity epitaxial layer of 4H-SiC exhibits promising properties in detection of various types of ionizing radiation. Due to the wide band gap of 4H-SiC semiconductor material, the detector can reliably operate at room and also elevated temperatures. In this work we focused on detection of fast neutrons generated the by D-T (deuterium-tritium) nuclear reaction. The epitaxial layer with a thickness of 105 μm was used as a detection part. A circular Schottky contact of a Au/Ni double layer was evaporated on both sides of the detector material. The detector structure was characterized by current-voltage and capacitance-voltage measurements, at first. The results show very low current density (<0.1 nA/cm2) at room temperature and good homogeneity of free carrier concentration in the investigated depth. The fabricated detectors were tested for detection of fast neutrons generated by the D-T reaction. The energies of detected fast neutrons varied from 16.0 MeV to 18.3 MeV according to the acceleration potential of deuterons, which increased from 600 kV up to 2 MV. Detection of fast neutrons in the SiC detector is caused by the elastic and inelastic scattering on the silicon or carbide component of the detector material. Another possibility that increases the detection efficiency is the use of a conversion layer. In our measurements, we glued a HDPE (high density polyethylene) conversion layer on the detector Schottky contact to transform fast neutrons to protons. Hydrogen atoms contained in the conversion layer have a high probability of interaction with neutrons through elastic scattering. Secondary generated protons flying to the detector can be easily detected. The detection properties of detectors with and without the HDPE conversion layer were compared.

  15. A system for the measurement of delayed neutrons and gammas from special nuclear materials

    DOE PAGESBeta

    Andrews, M. T.; Corcoran, E. C.; Goorley, J. T.; Kelly, D. G.

    2014-11-27

    The delayed neutron counting (DNC) system at the Royal Military College of Canada has been upgraded to accommodate concurrent delayed neutron and gamma measurements. This delayed neutron and gamma counting (DNGC) system uses a SLOWPOKE-2 reactor to irradiate fissile materials before their transfer to a counting arrangement consisting of six ³He and one HPGe detector. The application of this system is demonstrated in an example where delayed neutron and gamma emissions are used in complement to examine ²³³U content and determine fissile mass with an average relative error and accuracy of -2.2 and 1.5 %, respectively.

  16. A system for the measurement of delayed neutrons and gammas from special nuclear materials

    SciTech Connect

    Andrews, M. T.; Corcoran, E. C.; Goorley, J. T.; Kelly, D. G.

    2015-03-01

    The delayed neutron counting (DNC) system at the Royal Military College of Canada has been upgraded to accommodate concurrent delayed neutron and gamma measurements. This delayed neutron and gamma counting (DNGC) system uses a SLOWPOKE-2 reactor to irradiate fissile materials before their transfer to a counting arrangement consisting of six ³He and one HPGe detector. The application of this system is demonstrated in an example where delayed neutron and gamma emissions are used in complement to examine ²³³U content and determine fissile mass with an average relative error and accuracy of -2.2 and 1.5 %, respectively.

  17. Sensitivity of the neutron star r-mode instability window to the density dependence of the nuclear symmetry energy

    NASA Astrophysics Data System (ADS)

    Wen, De-Hua; Newton, W. G.; Li, Bao-An

    2012-02-01

    Using a simple model of a neutron star with a perfectly rigid crust constructed with a set of crust and core equations of state that span the range of nuclear experimental uncertainty in the symmetry energy, we calculate the instability window for the onset of the Chandrasekhar-Friedmann-Schutz instability in r-mode oscillations for canonical neutron stars (1.4M⊙) and massive neutron stars (2.0M⊙). In these models the crust-core transition density, and thus crustal thickness, is calculated consistently with the core equation of state (EOS). The EOSs are calculated using a simple model for the energy density of nuclear matter and probe the dependence on the symmetry energy by varying the slope of the symmetry energy at saturation density L from 25 MeV (soft symmetry energy and EOS) to 115 MeV (stiff symmetry energy and EOS) while keeping the EOS of symmetric nuclear matter fixed. For the canonical neutron star, the lower bound of the r-mode instability window is reduced in frequency by ≈150 Hz from the softest to the stiffest symmetry energy used, independent of mass and temperature. The instability window also drops by ≈100 Hz, independent of EOS when the mass is raised from 1.4M⊙ to 2.0M⊙. Where temperature estimates are available, the observed neutron stars in low-mass x-ray binaries (LMXBs) have frequencies below the instability window for the 1.4M⊙ models, while some LMXBs fall within the instability window for 2.0M⊙ stars if the symmetry energy is relatively stiff, indicating that a softer symmetry energy is more consistent with observations within this model. Thus we conclude that smaller values of L help stabilize neutron stars against runaway r-mode oscillations. The critical temperature, below which no star can reach the instability window without exceeding its Kepler frequency, varies by nearly an order of magnitude from soft to stiff symmetry energies. When the crust thickness and core EOS are treated consistently, a thicker crust

  18. Developments in Neutron Spectrometry and Dosimetry in Support of the U.K. Naval Nuclear Propulsion Program

    SciTech Connect

    P. A. Beeley; N. M. Spyrou; J. M. Brushwood; A. M. Williams

    2000-11-12

    The Defence Radiological Protection Service (DRPS) is tasked with providing the approved dosimetry service to the Naval Nuclear Propulsion Program (NNPP). Within this requirement, DRPS operates a track-etch system for whole-body neutron dosimetry, using the well-known material polyally dyglycol carbonate as the sensitive element. These dosimeters have a number of limitations, including a high limit of detection (typically 200 microsieverts), insensitivity to low-energy neutrons, and a strong angular dependence. Such limitations, along with the incorporation of the recommendations of the International Commission on Radiological Protection (ICRP) 60 into the revised U.K. Ionizing Radiation Regulations 1999, have provided the opportunity to reconsider spectrometric and dosimetric research in support of the NNPP. Area neutron dosimetry is most usually performed using a Leake-type spherical survey meter. In both the case of area and, more significantly, personal dosimetry, the differences in the energy spectra between the calibration and the operational fields require a location correction factor (LCF) to be applied. To determine these LCFs, it is necessary to accurately characterize the operational energy spectra. This characterization is undertaken using the transportable neutron spectrometer (TNS) developed by the U.K. Atomic Energy Establishment at Winfrith in the 1980s. Our research has focused on two areas, the development of an improved TNS system and a complimentary program to design a new area survey meter.

  19. Neutronic reactor

    DOEpatents

    Wende, Charles W. J.

    1976-08-17

    A safety rod for a nuclear reactor has an inner end portion having a gamma absorption coefficient and neutron capture cross section approximately equal to those of the adjacent shield, a central portion containing materials of high neutron capture cross section and an outer end portion having a gamma absorption coefficient at least equal to that of the adjacent shield.

  20. On the combination of delayed neutron and delayed gamma techniques for fission rate measurement in nuclear fuel

    SciTech Connect

    Perret, G.; Jordan, K. A.

    2011-07-01

    Novel techniques to measure newly induced fissions in spent fuel after re-irradiation at low power have been developed and tested at the Proteus zero-power research reactor. The two techniques are based on the detection of high energy gamma-rays emitted by short-lived fission products and delayed neutrons. The two techniques relate the measured signals to the total fission rate, the isotopic composition of the fuel, and nuclear data. They can be combined to derive better estimates on each of these parameters. This has potential for improvement in many areas. Spent fuel characterisation and safeguard applications can benefit from these techniques for non-destructive assay of plutonium content. Another application of choice is the reduction of uncertainties on nuclear data. As a first application of the combination of the delayed neutron and gamma measurement techniques, this paper shows how to reduce the uncertainties on the relative abundances of the longest delayed neutron group for thermal fissions in {sup 235}U, {sup 239}Pu and fast fissions in {sup 238}U. The proposed experiments are easily achievable in zero-power research reactors using fresh UO{sub 2} and MOX fuel and do not require fast extraction systems. The relative uncertainties (1{sigma}) on the relative abundances are expected to be reduced from 13% to 4%, 16% to 5%, and 38% to 12% for {sup 235}U, {sup 238}U and {sup 239}Pu, respectively. (authors)

  1. Evaluation of Aluminum-Boron Carbide Neutron Absorbing Materials for Interim Storage of Used Nuclear Fuel

    SciTech Connect

    Wang, Lumin; Wierschke, Jonathan Brett

    2015-04-08

    The objective of this work was to understand the corrosion behavior of Boral® and Bortec® neutron absorbers over long-term deployment in a used nuclear fuel dry cask storage environment. Corrosion effects were accelerated by flowing humidified argon through an autoclave at temperatures up to 570°C. Test results show little corrosion of the aluminum matrix but that boron is leaching out of the samples. Initial tests performed at 400 and 570°C were hampered by reduced flow caused by the rapid build-up of solid deposits in the outlet lines. Analysis of the deposits by XRD shows that the deposits are comprised of boron trioxide and sassolite (H3BO3). The collection of boron- containing compounds in the outlet lines indicated that boron was being released from the samples. Observation of the exposed samples using SEM and optical microscopy show the growth of new phases in the samples. These phases were most prominent in Bortec® samples exposed at 570°C. Samples of Boral® exposed at 570°C showed minimal new phase formation but showed nearly the complete loss of boron carbide particles. Boron carbide loss was also significant in Boral samples at 400°C. However, at 400°C phases similar to those found in Bortec® were observed. The rapid loss of the boron carbide particles in the Boral® is suspected to inhibit the formation of the new secondary phases. However, Material samples in an actual dry cask environment would be exposed to temperatures closer to 300°C and less water than the lowest test. The results from this study conclude that at the temperature and humidity levels present in a dry cask environment, corrosion and boron leaching will have no effect on the performance of Boral® and Bortec® to maintain criticality control.

  2. Development and Applications of X-ray and Neutron Tomography for Nuclear and Industrial Applications

    SciTech Connect

    Sinha, Amar; Sarkar, P. S.; Kashyap, Yogesh; Roy, Tushar; Agrawal, A.

    2008-09-26

    We present an overview of work being carried out by us in the field of X-ray and neutron imaging in general and tomography in particular. We have discussed our work on microtomography, cone beam tomography, phase imaging and phase tomography, emission tomography, neutron tomography and two phase flow being carried out by us.

  3. Modeled Neutron and Charged-Particle Induced Nuclear Reaction Cross Sections for Radiochemistry in the Region of Yttrium, Zirconium, Niobium, and Molybdenum

    SciTech Connect

    Hoffman, R D; Kelley, K; Dietrich, F S; Bauer, R; Mustafa, M G

    2006-06-13

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron, proton, and deuteron induced nuclear reaction cross sections for targets ranging from strontium (Z = 38) to rhodium (Z = 45).

  4. Application of Neutron-Absorbing Structural-Amorphous Metal (SAM) Coatings for Spent Nuclear Fuel (SNF) Container to Enhance Criticality Safety Control

    SciTech Connect

    Choi, J

    2007-01-12

    This report describes the analysis and modeling approaches used in the evaluation for criticality-control applications of the neutron-absorbing structural-amorphous metal (SAM) coatings. The applications of boron-containing high-performance corrosion-resistant material (HPCRM)--amorphous metal as the neutron-absorbing coatings to the metallic support structure can enhance criticality safety controls for spent nuclear fuel in baskets inside storage containers, transportation casks, and disposal containers. The use of these advanced iron-based, corrosion-resistant materials to prevent nuclear criticality in transportation, aging, and disposal containers would be extremely beneficial to the nuclear waste management programs.

  5. Nuclear microprobe analysis of 7Li profile induced in HfB 2 by a neutron irradiation

    NASA Astrophysics Data System (ADS)

    Simeone, D.; Deschanels, X.; Gosset, D.; Bonal, J. P.; Berthoumieux, E.

    2001-09-01

    HfB 2, a solid poor in boron, was irradiated by thermal neutrons in an experimental reactor. Using a nuclear microprobe, we have tracked lithium atoms produced by the 10B( n, α) 7Li reaction and compared the calculated and measured 7Li profiles in HfB 2 irradiated samples. This comparison shows that Li atoms do not diffuse during irradiation (323 K). The comparison of non-annealed and annealed irradiated HfB 2 plates clearly shows that lithium atoms do not migrate out of samples even at high temperatures (1273 K). These results associated to previous transmission electron microscopy (TEM) observations seem to show that lithium atoms are trapped by dislocation loops created by displacement cascades during neutron irradiation.

  6. Impact of the symmetry energy on nuclear pasta phases and crust-core transition in neutron stars

    NASA Astrophysics Data System (ADS)

    Bao, S. S.; Shen, H.

    2015-01-01

    We study the impact of the symmetry energy on properties of nuclear pasta phases and crust-core transition in neutron stars. We perform a self-consistent Thomas-Fermi calculation employing the relativistic mean-field model. The properties of pasta phases presented in the inner crust of neutron stars are investigated and the crust-core transition is examined. It is found that the slope of the symmetry energy plays an important role in determining the pasta phase structure and the crust-core transition. The correlation between the symmetry energy slope and the crust-core transition density obtained in the Thomas-Fermi approximation is consistent with that predicted by the liquid-drop model.

  7. A review on the relativistic effective field theory with parameterized couplings for nuclear matter and neutron stars

    SciTech Connect

    Vasconcellos, C. A. Zen

    2015-12-17

    Nuclear science has developed many excellent theoretical models for many-body systems in the domain of the baryon-meson strong interaction for the nucleus and nuclear matter at low, medium and high densities. However, a full microscopic understanding of nuclear systems in the extreme density domain of compact stars is still lacking. The aim of this contribution is to shed some light on open questions facing the nuclear many-body problem at the very high density domain. Here we focus our attention on the conceptual issue of naturalness and its role in shaping the baryon-meson phase space dynamics in the description of the equation of state (EoS) of nuclear matter and neutrons stars. In particular, in order to stimulate possible new directions of research, we discuss relevant aspects of a recently developed relativistic effective theory for nuclear matter within Quantum Hadrodynamics (QHD) with genuine many-body forces and derivative natural parametric couplings. Among other topics we discuss in this work the connection of this theory with other known effective QHD models of the literature and its potentiality in describing a new physics for dense matter. The model with parameterized couplings exhausts the whole fundamental baryon octet (n, p, Σ{sup −}, Σ{sup 0}, Σ{sup +}, Λ, Ξ{sup −}, Ξ{sup 0}) and simulates n-order corrections to the minimal Yukawa baryon couplings by considering nonlinear self-couplings of meson fields and meson-meson interaction terms coupled to the baryon fields involving scalar-isoscalar (σ, σ∗), vector-isoscalar (ω, Φ), vector-isovector (ϱ) and scalar-isovector (δ) virtual sectors. Following recent experimental results, we consider in our calculations the extreme case where the Σ{sup −} experiences such a strong repulsion that its influence in the nuclear structure of a neutron star is excluded at all. A few examples of calculations of properties of neutron stars are shown and prospects for the future are discussed.

  8. Why baryons are Yang-Mills magnetic monopoles, validated by nuclear binding energies and proton and neutron masses

    NASA Astrophysics Data System (ADS)

    Yablon, Jay R.

    2013-10-01

    Evidence is summarized from four recent papers that baryons including protons and neutrons are magnetic monopoles of non-commuting Yang-Mills gauge theories: 1) Protons and neutrons are ``resonant cavities'' with binding energies determined strictly by the masses of the quarks they contain. This is proven true at parts-per million accuracy for each of the 2H, 3H,3He, 4He binding energies and the neutron minus proton mass difference. 2) Respectively, each free proton and neutron contains 7.64 MeV and 9.81 MeV of mass/energy used to confine its quarks. When these nucleons bind, some, never all, of this energy is released and the mass deficit goes into binding. The balance continues to confine quarks. 56Fe releases 99.8429% of this energy for binding, more than any other nuclide. 3) Once we consider the Fermi vev one also finds an entirely theoretical explanation of proton and neutron masses, which also connects within experimental errors to the CKM quark mixing angles. 4) A related GUT explains fermion generation replication based on generator loss during symmetry breaking, and answers Rabi's question ``who ordered this?'' 5) Nuclear physics is governed by combining Maxwell's two classical equations into one equation using non-commuting gauge fields in view of Dirac theory and Fermi-Dirac-Pauli Exclusion. 6) Atoms themselves are core magnetic charges (nucleons) paired with orbital electric charges (electrons and elusive neutrinos), with the periodic table itself revealing an electric/magnetic symmetry of Maxwell's equations often pondered but heretofore unrecognized for a century and a half.

  9. Enhanced thermal conductivity oxide nuclear fuels by co-sintering with BeO: II. Fuel performance and neutronics

    NASA Astrophysics Data System (ADS)

    McCoy, Kevin; Mays, Claude

    2008-04-01

    The fuel rod performance and neutronics of enhanced thermal conductivity oxide (ECO) nuclear fuel with BeO have been compared to those of standard UO 2 fuel. The standards of comparison were that the ECO fuel should have the same infinite neutron-multiplication factor kinf at end of life and provide the same energy extraction per fuel assembly over its lifetime. The BeO displaces some uranium, so equivalence with standard UO 2 fuel was obtained by increasing the burnup and slightly increasing the enrichment. The COPERNIC fuel rod performance code was adapted to account for the effect of BeO on thermal properties. The materials considered were standard UO 2, UO 2 with 4.0 vol.% BeO, and UO 2 with 9.6 vol.% BeO. The smaller amount of BeO was assumed to provide increases in thermal conductivity of 0, 5, or 10%, whereas the larger amount was assumed to provide an increase of 50%. A significant improvement in performance was seen, as evidenced by reduced temperatures, internal rod pressures, and fission gas release, even with modest (5-10%) increases in thermal conductivity. The benefits increased monotonically with increasing thermal conductivity. Improvements in LOCA initialization performance were also seen. A neutronic calculation considered a transition from standard UO 2 fuel to ECO fuel. The calculation indicated that only a small increase in enrichment is required to maintain the kinf at end of life. The smallness of the change was attributed to the neutron-multiplication reaction of Be with fast neutrons and the moderating effect of BeO. Adoption of ECO fuel was predicted to provide a net reduction in uranium cost. Requirements for industrial hygiene were found to be comparable to those for processing of UO 2.

  10. Simultaneous Observation of Cells and Nuclear Tracks from the Boron Neutron Capture Reaction by UV-C Sensitization of Polycarbonate.

    PubMed

    Portu, Agustina; Rossini, Andrés Eugenio; Thorp, Silvia Inés; Curotto, Paula; Pozzi, Emiliano César Cayetano; Granell, Pablo; Golmar, Federico; Cabrini, Rómulo Luis; Martin, Gisela Saint

    2015-08-01

    The distribution of boron in tissue samples coming from boron neutron capture therapy protocols can be determined through the analysis of its autoradiography image on a nuclear track detector. A more precise knowledge of boron atom location on the microscopic scale can be attained by the observation of nuclear tracks superimposed on the sample image on the detector. A method to produce an "imprint" of cells cultivated on a polycarbonate detector was developed, based on the photodegradation properties of UV-C radiation on this material. Optimal conditions to generate an appropriate monolayer of Mel-J cells incubated with boronophenylalanine were found. The best images of both cells and nuclear tracks were obtained for a neutron fluence of 1013 cm-2, 6 h UV-C (254 nm) exposure, and 4 min etching time with a KOH solution. The imprint morphology was analyzed by both light and scanning electron microscopy. Similar samples, exposed to UV-A (360 nm) revealed no cellular imprinting. Etch pits were present only inside the cell imprints, indicating a preferential boron uptake (about threefold the incubation concentration). Comparative studies of boron absorption in different cell lines and in vitro evaluation of the effect of diverse boron compounds are feasible with this methodology. PMID:26155721

  11. Simultaneous Observation of Cells and Nuclear Tracks from the Boron Neutron Capture Reaction by UV-C Sensitization of Polycarbonate.

    PubMed

    Portu, Agustina; Rossini, Andrés Eugenio; Thorp, Silvia Inés; Curotto, Paula; Pozzi, Emiliano César Cayetano; Granell, Pablo; Golmar, Federico; Cabrini, Rómulo Luis; Martin, Gisela Saint

    2015-08-01

    The distribution of boron in tissue samples coming from boron neutron capture therapy protocols can be determined through the analysis of its autoradiography image on a nuclear track detector. A more precise knowledge of boron atom location on the microscopic scale can be attained by the observation of nuclear tracks superimposed on the sample image on the detector. A method to produce an "imprint" of cells cultivated on a polycarbonate detector was developed, based on the photodegradation properties of UV-C radiation on this material. Optimal conditions to generate an appropriate monolayer of Mel-J cells incubated with boronophenylalanine were found. The best images of both cells and nuclear tracks were obtained for a neutron fluence of 1013 cm-2, 6 h UV-C (254 nm) exposure, and 4 min etching time with a KOH solution. The imprint morphology was analyzed by both light and scanning electron microscopy. Similar samples, exposed to UV-A (360 nm) revealed no cellular imprinting. Etch pits were present only inside the cell imprints, indicating a preferential boron uptake (about threefold the incubation concentration). Comparative studies of boron absorption in different cell lines and in vitro evaluation of the effect of diverse boron compounds are feasible with this methodology.

  12. NUCLEAR PHYSICS: Comparison of Properties of the Simplest Neutron Stars in Three RMF Models

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Hua; Fu, Wei-Jie; Liu, Yu-Xin

    2008-08-01

    We study some properties of the simplest neutron stars (NSs) in the Glendenning-Moszkowski (GM) model, the hybrid derivative coupling (HD) model and the Zimanyi-Moszkowski (ZM) model in the framework of relativistic mean field (RMF) theory with and without the interaction by exchanging the S-meson. We show that the maximal mass of the NSs becomes smaller, but the redshift becomes larger from the GM model to the HD model, then to the ZM model. The interaction with the S-meson exchange enlarges the maximal mass of neutron stars, increases the relative population of charged particles (proton, electron and muon) and descends the relative population of neutron.

  13. Evolution of nuclear ground-state properties of neutron-deficient isotopes around Z =82 from precision mass measurements

    NASA Astrophysics Data System (ADS)

    Böhm, Ch.; Borgmann, Ch.; Audi, G.; Beck, D.; Blaum, K.; Breitenfeldt, M.; Cakirli, R. B.; Cocolios, T. E.; Eliseev, S.; George, S.; Herfurth, F.; Herlert, A.; Kowalska, M.; Kreim, S.; Lunney, D.; Manea, V.; Minaya Ramirez, E.; Naimi, S.; Neidherr, D.; Rosenbusch, M.; Schweikhard, L.; Stanja, J.; Wang, M.; Wolf, R. N.; Zuber, K.

    2014-10-01

    High-precision mass measurements of neutron-deficient Tl (A =184, 186, 190, 193-195, 198) isotopes as well as Pb (A =202,208), Fr (A =207,208), and Ra (A =224) are performed with the Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The improved precision of the mass data now allows the study of subtle odd-even effects. The gradual development of collectivity with the removal of protons from the magic Z =82 core is analyzed by combining the new mass results with nuclear charge-radii data and mean-field model predictions.

  14. Study on neutronic of very small Pb - Bi cooled no-onsite refueling nuclear power reactor (VSPINNOR)

    SciTech Connect

    Arianto, Fajar; Su'ud, Zaki; Zuhair

    2014-09-30

    A conceptual design study on Very Small Pb-Bi No-Onsite Refueling Cooled Nuclear Reactor (VSPINNOR) with Uranium nitride fuel using MCNPX program has been performed. In this design the reactor core is divided into three regions with different enrichment. At the center of the core is laid fuel without enrichment (internal blanket). While for the outer region using fuel enrichment variations. VSPINNOR fast reactor was operated for 10 years without refueling. Neutronic analysis shows optimized result of VSPINNOR has a core of 50 cm radius and 100 cm height with 300 MWth thermal power output at 60% fuel fraction that can be operated 18 years without refueling or fuel shuffling.

  15. Nuclear Sturcture Along the Neutron Dripline: MoNa-LISA and the dinueutron system

    SciTech Connect

    Spyou, Artemis

    2012-09-05

    Nuclei with extreme neutron-to-proton ratios were found to present different structures from what was known for the stable ones. With the current facilities we can now study nuclei that lie even beyond the neutron drip line. At the National Superconducting Cyclotron Laboratory at Michigan State University we use the MoNA/Sweeper setup to perform such studies of neutron unbound nuclei. In a typical experiment, a radioactive beam is employed to produce the nucleus of interest. This unbound nucleus immediately decays into a neutron and a remaining charged fragment, both of which are detected and used to reconstruct the original nucleus and study its properties. In this Colloquium, new exciting findings from recent experiments will be presented. These include the first observation of a dineutron decay from 16Be, the exploration of the “south shore” of the Island of Inversion and the first evidence of the decay of the troubling nucleus 26O.

  16. Development of Neutron Polarization Measurement System for Studying NN interaction in Nuclear Medium

    NASA Astrophysics Data System (ADS)

    Yasuda, J.; Wakasa, T.; Dozono, M.; Fukunaga, T.; Gotanda, S.; Hatanaka, K.; Kanaya, Y.; Maeda, Y.; Maeda, Y.; Miki, K.; Nishio, Y.; Noro, T.; Ohnaka, K.; Sakaguchi, S.; Sakemi, Y.; Sekiguchi, K.; Tamii, A.; Taguchi, T.; Wada, Y.

    2016-02-01

    We have developed the neutron polarization measurement system to perform the first polarization-transfer measurement for the exclusive (p,np) reaction. For the neutron polarization measurement, we have reconstructed the neutron polarimeter NPOL3. The NPOL3 system has been calibrated by using the polarized neutron from the 2H(p→,n→) reaction, and the resulting effective analyzing power is Ay:eff = 0.127. For the exclusive measurement, the Large Acceptance Spectrometer (LAS) has been used for the recoil proton detection. The energy resolution of 6 MeV is achieved for separation energy, which is sufficient to separate the 1s and 1p orbits for light nuclei.

  17. Neutron Energy Spectra and Yields from the 7Li(p,n) Reaction for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Tessler, M.; Friedman, M.; Schmidt, S.; Shor, A.; Berkovits, D.; Cohen, D.; Feinberg, G.; Fiebiger, S.; Krása, A.; Paul, M.; Plag, R.; Plompen, A.; Reifarth, R.

    2016-01-01

    Neutrons produced by the 7Li(p, n)7Be reaction close to threshold are widely used to measure the cross section of s-process nucleosynthesis reactions. While experiments have been performed so far with Van de Graaff accelerators, the use of RF accelerators with higher intensities is planned to enable investigations on radioactive isotopes. In parallel, high-power Li targets for the production of high-intensity neutrons at stellar energies are developed at Goethe University (Frankfurt, Germany) and SARAF (Soreq NRC, Israel). However, such setups pose severe challenges for the measurement of the proton beam intensity or the neutron fluence. In order to develop appropriate methods, we studied in detail the neutron energy distribution and intensity produced by the thick-target 7Li(p,n)7Be reaction and compared them to state-of- the-art simulation codes. Measurements were performed with the bunched and chopped proton beam at the Van de Graaff facility of the Institute for Reference Materials and Measurements (IRMM) using the time-of-flight (TOF) technique with thin (1/8") and thick (1") detectors. The importance of detailed simulations of the detector structure and geometry for the conversion of TOF to a neutron energy is stressed. The measured neutron spectra are consistent with those previously reported and agree well with Monte Carlo simulations that include experimentally determined 7Li(p,n) cross sections, two-body kinematics and proton energy loss in the Li-target.

  18. Transmutation of All German Transuranium under Nuclear Phase Out Conditions – Is This Feasible from Neutronic Point of View?

    PubMed Central

    Merk, Bruno; Litskevich, Dzianis

    2015-01-01

    The German government has decided for the nuclear phase out, but a decision on a strategy for the management of the highly radioactive waste is not defined yet. Partitioning and Transmutation (P&T) could be considered as a technological option for the management of highly radioactive waste, therefore a wide study has been conducted. In the study group objectives for P&T and the boundary conditions of the phase out have been discussed. The fulfillment of the given objectives is analyzed from neutronics point of view using simulations of a molten salt reactor with fast neutron spectrum. It is shown that the efficient transmutation of all existing transuranium isotopes would be possible from neutronic point of view in a time frame of about 60 years. For this task three reactors of a mostly new technology would have to be developed and a twofold life cycle consisting of a transmuter operation and a deep burn phase would be required. A basic insight for the optimization of the time duration of the deep burn phase is given. Further on, a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation in the molten salt fast reactor. The effect of modeling and simulation is investigated based on three different modeling strategies and two different code versions. PMID:26717509

  19. Transmutation of All German Transuranium under Nuclear Phase Out Conditions - Is This Feasible from Neutronic Point of View?

    PubMed

    Merk, Bruno; Litskevich, Dzianis

    2015-01-01

    The German government has decided for the nuclear phase out, but a decision on a strategy for the management of the highly radioactive waste is not defined yet. Partitioning and Transmutation (P&T) could be considered as a technological option for the management of highly radioactive waste, therefore a wide study has been conducted. In the study group objectives for P&T and the boundary conditions of the phase out have been discussed. The fulfillment of the given objectives is analyzed from neutronics point of view using simulations of a molten salt reactor with fast neutron spectrum. It is shown that the efficient transmutation of all existing transuranium isotopes would be possible from neutronic point of view in a time frame of about 60 years. For this task three reactors of a mostly new technology would have to be developed and a twofold life cycle consisting of a transmuter operation and a deep burn phase would be required. A basic insight for the optimization of the time duration of the deep burn phase is given. Further on, a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation in the molten salt fast reactor. The effect of modeling and simulation is investigated based on three different modeling strategies and two different code versions.

  20. Transmutation of All German Transuranium under Nuclear Phase Out Conditions - Is This Feasible from Neutronic Point of View?

    PubMed

    Merk, Bruno; Litskevich, Dzianis

    2015-01-01

    The German government has decided for the nuclear phase out, but a decision on a strategy for the management of the highly radioactive waste is not defined yet. Partitioning and Transmutation (P&T) could be considered as a technological option for the management of highly radioactive waste, therefore a wide study has been conducted. In the study group objectives for P&T and the boundary conditions of the phase out have been discussed. The fulfillment of the given objectives is analyzed from neutronics point of view using simulations of a molten salt reactor with fast neutron spectrum. It is shown that the efficient transmutation of all existing transuranium isotopes would be possible from neutronic point of view in a time frame of about 60 years. For this task three reactors of a mostly new technology would have to be developed and a twofold life cycle consisting of a transmuter operation and a deep burn phase would be required. A basic insight for the optimization of the time duration of the deep burn phase is given. Further on, a detailed balance of different isotopic inventories is given to allow a deeper understanding of the processes during transmutation in the molten salt fast reactor. The effect of modeling and simulation is investigated based on three different modeling strategies and two different code versions. PMID:26717509

  1. LYNX: An unattended sensor system for detection of gamma-ray and neutron emissions from special nuclear materials

    SciTech Connect

    Runkle, Robert C.; Myjak, Mitchell J.; Kiff, Scott D.; Sidor, Daniel E.; Morris, Scott J.; Rohrer, John S.; Jarman, Kenneth D.; Pfund, David M.; Todd, Lindsay C.; Bowler, Ryan S.; Mullen, Crystal A.

    2009-01-21

    This manuscript profiles an unattended and fully autonomous detection system sensitive to gamma-ray and neutron emissions from special nuclear material. The LYNX design specifically targets applications that require radiation detection capabilities but possess little or no infrastructure. In these settings, users need the capability to deploy sensors for extended periods of time that analyze whatever signal-starved data can be captured, since little or no control may be exerted over measurement conditions. The fundamental sensing elements of the LYNX system are traditional NaI(Tl) and 3He detectors. The new developments reported here center on two themes: low-power electronics and computationally simple analysis algorithms capable of discriminating gamma-ray signatures indicative of special nuclear materials from those of naturally occurring radioactive material. Incorporating tripwire-detection algorithms based on gamma-ray spectral signatures into a low-power electronics package significantly improves performance in environments where sensors encounter nuisance sources.

  2. Assay of scrap plutonium oxide by thermal neutron multiplicity counting for IAEA verification of excess materials from nuclear weapons production

    SciTech Connect

    Stewart, J.E.; Krick, M.S.; Xiao, J.; LeMaire, R.J.; Fotin, V.; McRae, L.; Scott, D.; Westsik, G.

    1996-09-01

    The US Nonproliferation and Export Control Policy commits the US to placing under International Atomic Energy Agency (IAEA) safeguards excess nuclear materials no longer needed for the US nuclear deterrent. As of January 1,1996, the IAEA has completed Initial Physical Inventory Verification (IPIV) at the Oak Ridge Y-12 plant, the Hanford Plutonium Finishing Plant, and a plutonium storage vault at Rock Flats. Two IPIVs were performed at Hanford . This paper reports the results of thermal neutron multiplicity assay of plutonium residues during the second IPIV at Hanford. Using the Three Ring Multiplicity Counter (3RMC), measurements were performed on 69 individual cans of plutonium residues, each containing approximately 1 kg of material. Of the 69 items, 67 passed the IAEA acceptance criteria and two were selected for destructive analysis.

  3. Semi-insulating GaAs detectors with HDPE layer for detection of fast neutrons from D-T nuclear reaction

    NASA Astrophysics Data System (ADS)

    Sagatova, Andrea; Zatko, Bohumir; Sedlackova, Katarina; Pavlovic, Marius; Necas, Vladimir; Fulop, Marko; Solar, Michael; Granja, Carlos

    2016-09-01

    Bulk semi-insulating (SI) GaAs detectors optimized for fast-neutron detection were examined using mono-energetic neutrons. The detectors have an active area of 7.36 mm2 defined by a multi-pixel structure of a AuZn Schottky contact allowing a relatively high breakdown voltage (300 V) sufficient for full depletion of the detector structure. The Schottky contact is covered by a HDPE (high density polyethylene) conversion layer, where neutrons transfer their kinetic energy to hydrogen atoms through elastic nuclear collisions. The detectors were exposed to mono-energetic neutrons generated by a deuterium (D)-tritium (T) nuclear reaction at a Van de Graaff accelerator. Neutrons reached a kinetic energy of 16.8 MeV when deuterons were accelerated by 1 MV potential. The influence of the HDPE layer thickness on the detection efficiency of the fast neutrons was studied. The thickness of the conversion layer varied from 50 μm to 1300 μm. The increase of the HDPE layer thickness led to a higher detection efficiency due to higher conversion efficiency of the HDPE layer. The effect of the active detector thickness modified by the detector reverse bias voltage on the detection efficiency was also evaluated. By increasing the detector reverse voltage, the detector active volume expands to the depth and also to the sides, slightly increasing the neutron detection efficiency.

  4. Nuclear structure from radioactive decay

    SciTech Connect

    Wood, J.L.

    1991-09-30

    This report discusses nuclear structure from radioactive decay of the following: Neutron-Deficient Iridium Isotopes; Neutron-Deficient Platinum Isotopes; Neutron-Deficient Gold Isotopes; Neutron-Deficient Mercury Isotopes; Neutron-Deficient Thallium Isotopes; Neutron-Deficient Lead Isotopes; Neutron-Deficient Samarium Isotopes; Neutron-Deficient Promethium Isotopes; Neutron-Deficient Neodymium Isotopes; and Neutron-Deficient Praseodymium Isotopes. Also discussed are Nuclear Systematics and Models.

  5. Electroweak Measurements of Neutron Densities in CREX and PREX at JLab, USA

    SciTech Connect

    Horowitz, Charles J.; Kumar, Krishna S.; Michaels, Robert W.

    2014-02-01

    Measurement of the parity-violating electron scattering asymmetry is an established technique at Jefferson Lab and provides a new opportunity to measure the weak charge distribution and hence pin down the neutron radius in nuclei in a relatively clean and model-independent way. This is because the Z boson of the weak interaction couples primarily to neutrons. We will describe the PREX and CREX experiments on ${}^{208}$Pb and ${}^{48}$Ca respectively; these are both doubly-magic nuclei whose first excited state can be discriminated by the high resolution spectrometers at JLab. The heavier lead nucleus, with a neutron excess, provides an interpretation of the neutron skin thickness in terms of properties of bulk neutron matter. For the lighter ${}^{48}$Ca nucleus, which is also rich in neutrons, microscopic nuclear theory calculations are feasible and are sensitive to poorly constrained 3-neutron forces.

  6. Sample registration software for process automation in the Neutron Activation Analysis (NAA) Facility in Malaysia nuclear agency

    SciTech Connect

    Rahman, Nur Aira Abd Yussup, Nolida; Ibrahim, Maslina Bt. Mohd; Mokhtar, Mukhlis B.; Soh Shaari, Syirrazie Bin Che; Azman, Azraf B.; Salim, Nazaratul Ashifa Bt. Abdullah; Ismail, Nadiah Binti

    2015-04-29

    Neutron Activation Analysis (NAA) had been established in Nuclear Malaysia since 1980s. Most of the procedures established were done manually including sample registration. The samples were recorded manually in a logbook and given ID number. Then all samples, standards, SRM and blank were recorded on the irradiation vial and several forms prior to irradiation. These manual procedures carried out by the NAA laboratory personnel were time consuming and not efficient. Sample registration software is developed as part of IAEA/CRP project on ‘Development of Process Automation in the Neutron Activation Analysis (NAA) Facility in Malaysia Nuclear Agency (RC17399)’. The objective of the project is to create a pc-based data entry software during sample preparation stage. This is an effective method to replace redundant manual data entries that needs to be completed by laboratory personnel. The software developed will automatically generate sample code for each sample in one batch, create printable registration forms for administration purpose, and store selected parameters that will be passed to sample analysis program. The software is developed by using National Instruments Labview 8.6.

  7. On the mechanism of the interactions of neutrons and gamma radiation with nuclear graphite—Implications to HTGRs

    NASA Astrophysics Data System (ADS)

    Goodwin, C.; Barkatt, A.; Al-Sheikhly, M.

    2014-04-01

    Nuclear-grade varieties of graphite being considered for use in high-temperature gas reactors were exposed to gamma radiation (up to 87 MGy) and to fast neutrons (up to 5.4×1017 n/cm2 in air, 8.8×1011 n/cm2 in water-saturated helium). Results of XPS measurements indicated that gamma or mixed-field irradiation initially enhances the oxygen content in the surface region of the graphite, but this content decreases at higher doses, probably due to decomposition of surface CO complexes. Results of EPR measurements showed that gamma irradiation at low doses causes a decrease in the concentration of unpaired spins, but higher doses cause this concentration to rise. SQUID measurements of magnetic susceptibility support the EPR findings. At the dose range explored in this study, no structural changes were observed using XRD and Raman spectroscopy. In general, no significant differences were observed among the five varieties of graphite with respect to the effects of irradiation. Impurity analysis by means of GDMS and ICP-AES showed that impurity concentrations that concentrations of impurities, particularly those of neutron-absorbing impurities, were within the range specified for high-purity nuclear graphite. Activation relevant impurity concentrations, too, were very low.

  8. Sample registration software for process automation in the Neutron Activation Analysis (NAA) Facility in Malaysia nuclear agency

    NASA Astrophysics Data System (ADS)

    Rahman, Nur Aira Abd; Yussup, Nolida; Salim, Nazaratul Ashifa Bt. Abdullah; Ibrahim, Maslina Bt. Mohd; Mokhtar, Mukhlis B.; Soh@Shaari, Syirrazie Bin Che; Azman, Azraf B.; Ismail, Nadiah Binti

    2015-04-01

    Neutron Activation Analysis (NAA) had been established in Nuclear Malaysia since 1980s. Most of the procedures established were done manually including sample registration. The samples were recorded manually in a logbook and given ID number. Then all samples, standards, SRM and blank were recorded on the irradiation vial and several forms prior to irradiation. These manual procedures carried out by the NAA laboratory personnel were time consuming and not efficient. Sample registration software is developed as part of IAEA/CRP project on `Development of Process Automation in the Neutron Activation Analysis (NAA) Facility in Malaysia Nuclear Agency (RC17399)'. The objective of the project is to create a pc-based data entry software during sample preparation stage. This is an effective method to replace redundant manual data entries that needs to be completed by laboratory personnel. The software developed will automatically generate sample code for each sample in one batch, create printable registration forms for administration purpose, and store selected parameters that will be passed to sample analysis program. The software is developed by using National Instruments Labview 8.6.

  9. Implementation of neutron counting techniques at US facilities for IAEA verification of excess materials from nuclear weapons production

    SciTech Connect

    Stewart, J.E.; Krick, M.S.; Langner, D.G.; Reilly, T.D.; Theis, W.; Lemaire, R.J.; Xiao, J.

    1995-08-01

    The U.S. Nonproliferation and Export Control Policy, announced by President Clinton before the United Nations General Assembly on September 27, 1993, commits the U.S. to placing under International Atomic Energy Agency (IAEA) Safeguards excess nuclear materials no longer needed for the U.S. nuclear deterrent. As of July 1, 1995, the IAEA had completed Initial Physical Inventory Verification (IPIV) at two facilities: a storage vault in the Oak Ridge Y-12 plant containing highly enriched uranium (HOW) metal and another storage vault in the Hanford Plutonium Finishing Plant (PFP) containing plutonium oxide and plutonium-bearing residues. Another plutonium- storage vault, located at Rocky Flats, is scheduled for the IPIV in the fall of 1995. Conventional neutron coincidence counting is one of the routinely applied IAEA nondestructive assay (ND) methods for verification of uranium and plutonium. However, at all three facilities mentioned above, neutron ND equipment had to be modified or developed for specific facility needs such as the type and configuration of material placed under safeguards. This document describes those modifications and developments.

  10. Neutron dosimetry: Spectrometry with CR 39 polymer solid state nuclear track detector

    NASA Astrophysics Data System (ADS)

    Spurny, F.

    1991-05-01

    Studies were performed with two commercial CR-39 etch track materials to enhance their application to neutron dosimetry and spectrometry. The work included: (1) Validation and optimization of the etching procedures used to process selected CR-39 plastic track etch detectors for measurement of fast neutrons; (2) Design of a multi-sample etch chamber capable of processing up to 100 track detectors; (3) Verification of uniform bulk etching homogeneity for the selected materials studied; (4) Evaluation of two commercial image analysis systems for measurement of neutron induced etch track densities in plastic track detectors; (5) Confirmation of the dose equivalent response of selected CR-39 track detectors for 3 benchmark neutron spectra (Cf-252, (241)AmBe, and 14 MeV); (6) Test and evaluation of a method for passive neutron spectrometry using a variety of etch track detectors with different energy responses; and (7) Determination of the dose equivalent response of selected CR-39 track detectors in two high energy accelerator fields. The conclusions drawn by the chief investigator include: (1) The signal-to-noise ratio of the CR-39 track detectors can be improved by removing some of the surface layer, either by chemical etching or mechanical brushing; (2) Reproducibility is highly dependent on the time profile of the etch chamber temperature; and (3) Use of a multi-sample etching chamber simplifies manipulation and solves some important problems such as etchant break through.

  11. Evidence of neutron leakage at the Fukushima nuclear plant from measurements of radioactive 35S in California

    PubMed Central

    Priyadarshi, Antra; Dominguez, Gerardo; Thiemens, Mark H.

    2011-01-01

    A recent earthquake and the subsequent tsunami have extensively damaged the Fukushima nuclear power plant, releasing harmful radiation into the environment. Despite the obvious implication for human health and the surrounding ecology, there are no quantitative estimates of the neutron flux leakage during the weeks following the earthquake. Here, using measurements of radioactive 35S contained in sulfate aerosols and SO2 gas at a coastal site in La Jolla, California, we show that nearly 4 × 1011 neutrons per m2 leaked at the Fukushima nuclear power plant before March 20, 2011. A significantly higher activity as measured on March 28 is in accord with neutrons escaping the reactor core and being absorbed by the coolant seawater 35Cl to produce 35S by a (n, p) reaction. Once produced, 35S oxidizes to and and was then transported to Southern California due to the presence of strong prevailing westerly winds at this time. Based on a moving box model, we show that the observed activity enhancement in is compatible with long-range transport of the radiation plume from Fukushima. Our model predicts that , the concentration in the marine boundary layer at Fukushima, was approximately 2 × 105 atoms per m3, which is approximately 365 times above expected natural concentrations. These measurements and model calculations imply that approximately 0.7% of the total radioactive sulfate present at the marine boundary layer at Fukushima reached Southern California as a result of the trans-Pacific transport. PMID:21844372

  12. Fast-neutron total and scattering cross sections of sup 58 Ni and nuclear models

    SciTech Connect

    Smith, A.B.; Guenther, P.T.; Whalen, J.F. ); Chiba, S. . Tokai Research Establishment)

    1991-07-01

    The neutron total cross sections of {sup 58}Ni were measured from {approx} 1 to > 10 MeV using white-source techniques. Differential neutron elastic-scattering cross sections were measured from {approx} 4.5 to 10 MeV at {approx} 0.5 MeV intervals with {ge} 75 differential values per distribution. Differential neutron inelastic-scattering cross sections were measured, corresponding to fourteen levels with excitations up to 4.8 MeV. The measured results, combined with relevant values available in the literature, were interpreted in terms of optical-statistical and coupled-channels model using both vibrational and rotational coupling schemes. The physical implications of the experimental results nd their interpretation are discussed in the contexts of optical-statistical, dispersive-optical, and coupled-channels models. 61 refs.

  13. Measurement of neutron multiplicity from fission of {sup 228}U and nuclear dissipation

    SciTech Connect

    Singh, Hardev; Behera, B. R.; Singh, Gulzar; Govil, I. M.; Golda, K. S.; Jhingan, Akhil; Singh, R. P.; Sugathan, P.; Chatterjee, M. B.; Datta, S. K.; Pal, Santanu; Ranjeet; Mandal, S.; Shidling, P. D.; Viesti, G.

    2009-12-15

    Pre- and post-scission neutron multiplicities are measured at different excitation energies of the compound nucleus {sup 228}U populated using the {sup 19}F+{sup 209}Bi reaction. The measured yield of pre-scission and total neutrons are compared with the statistical model calculation for the decay of a compound nucleus. The statistical model calculations are performed using the Bohr-Wheeler transition state fission width as well as the dissipative dynamical fission width due to Kramers. Comparison between the measured and the calculated values shows that, while the Bohr-Wheeler fission width grossly underestimates the pre-scission neutron yield, a large amount of dissipation is required in the Kramers width to fit the experimental pre-scission multiplicities. Various factors contributing to the large excitation energy dependence of the fitted values of the dissipation coefficient are discussed.

  14. Nuclear level densities of 64,66Zn from neutron evaporation

    NASA Astrophysics Data System (ADS)

    Ramirez, Anthony Paul; Voinov, Alexander; Grimes, Steven; Brune, Carl; Massey, Thomas

    2013-10-01

    The neutron spectra from the reactions 63Cu(d,n)64Zn and 65Cu(d,n)66Zn have been measured at deuteron beam energies of 6 and 7.5 MeV. Level densities of the residual nuclei 64Zn and 66Zn were extracted and compared with different level density models: (1) Gilbert-Cameron model, (2) Backshifted Fermi gas model using the Egidy systematics, and (3) microscopic combinatorial level densities. We found that the Gilbert-Cameron model closely agrees with the experimental results. We have also studied the non-compound component of the reactions from the neutron angular distributions. The non-compound component has been shown to be dominant in forward angles and is more pronounced at high neutron emission energies. We have also observed a slight enhancement of the non-compound contribution as the incident deuteron energy is increased.

  15. Neutron Transport and Nuclear Burnup Analysis for the Laser Inertial Confinement Fusion-Fission Energy (LIFE) Engine

    SciTech Connect

    Kramer, K J; Latkowski, J F; Abbott, R P; Boyd, J K; Powers, J J; Seifried, J E

    2008-10-24

    Lawrence Livermore National Laboratory is currently developing a hybrid fusion-fission nuclear energy system, called LIFE, to generate power and burn nuclear waste. We utilize inertial confinement fusion to drive a subcritical fission blanket surrounding the fusion chamber. It is composed of TRISO-based fuel cooled by the molten salt flibe. Low-yield (37.5 MJ) targets and a repetition rate of 13.3 Hz produce a 500 MW fusion source that is coupled to the subcritical blanket, which provides an additional gain of 4-8, depending on the fuel. In the present work, we describe the neutron transport and nuclear burnup analysis. We utilize standard analysis tools including, the Monte Carlo N-Particle (MCNP) transport code, ORIGEN2 and Monteburns to perform the nuclear design. These analyses focus primarily on a fuel composed of depleted uranium not requiring chemical reprocessing or enrichment. However, other fuels such as weapons grade plutonium and highly-enriched uranium are also under consideration. In addition, we have developed a methodology using {sup 6}Li as a burnable poison to replace the tritium burned in the fusion targets and to maintain constant power over the lifetime of the engine. The results from depleted uranium analyses suggest up to 99% burnup of actinides is attainable while maintaining full power at 2GW for more than five decades.

  16. Use of neutron reflection method to assay nuclear materials in solutions.

    PubMed

    Mohapatra, D K; Reddy, C P

    2001-11-01

    Neutron reflection methods are used in the chemical analysis of bulk samples, especially for the determination of contents in hydrogenous solutions. In these techniques albedo is measured by measuring either the activation of a foil, or count rate from a neutron detector. In the present paper Monte Carlo simulations are performed using this method for the possibility of detecting inadvertent criticality in the reprocessing plants and also estimation of 10B in heavy water, which is used as a moderator in PHWRs. PMID:11573803

  17. Nuclear structure studies via neutron interactions. Progress report, 1 July 1994--30 June 1995

    SciTech Connect

    Carlton, R.F.

    1995-01-01

    Neutron total cross section measurements of {sup 122}Sn has been analyzed over the energy range 0.013 to 0.310 MeV. The R - matrix analysis has resulted in resonance and average parameters which provide for a complete representation of the neutron entrance the s{sub 1/2}, p{sub 1/2}, and p{sub 3/2} contributions. The s - and p - neutron strength functions have been determined to be 0.123 {plus_minus} 0.023 and 2.0 {plus_minus} 0.200, respectively (in units of 10{sup {minus}4}). Limits are placed on level spacings and strength functions for the individual partial wave components. The s - wave potential scattering radius has been determined to be 6.3 {plus_minus} 0.1 fm. Average scattering functions, deduced from the average parameters, have been used to determine the real well depth of an optical model potential which reproduces these functions. We find, as have others, that the real well depth is parity dependent. Two computer codes were developed: (1) a minimization program for finding parameters of a dispersive optical model which reproduce the high resolution data of the ORELA facility, and (2) an X-windows graphical user interface has been developed to permit interactive resonance analysis of the neutron total cross section data using analysis-and-minimization codes developed previously. These will contribute to the more routine analysis of ORELA data.

  18. Nuclear Shape And Size Properties For Rare-earth Neutron-rich Nuclei

    SciTech Connect

    Benhamouda, N.; Oudih, M. R.; Allal, N. H.; Fellah, M.

    2009-01-28

    Two-neutron separation energies, quadrupole moments and mean square charge radii, are evaluated for even-even Osmium isotopes with 78{<=}N{<=}114. The calculations are performed in the framework of a microscopic model including the pairing correlations rigorously by means of the FSBCS (Fixed-Sharp-BCS) method.

  19. Analytical three-dimensional neutron transport benchmarks for verification of nuclear engineering codes. Final report

    SciTech Connect

    Ganapol, B.D.; Kornreich, D.E.

    1997-07-01

    Because of the requirement of accountability and quality control in the scientific world, a demand for high-quality analytical benchmark calculations has arisen in the neutron transport community. The intent of these benchmarks is to provide a numerical standard to which production neutron transport codes may be compared in order to verify proper operation. The overall investigation as modified in the second year renewal application includes the following three primary tasks. Task 1 on two dimensional neutron transport is divided into (a) single medium searchlight problem (SLP) and (b) two-adjacent half-space SLP. Task 2 on three-dimensional neutron transport covers (a) point source in arbitrary geometry, (b) single medium SLP, and (c) two-adjacent half-space SLP. Task 3 on code verification, includes deterministic and probabilistic codes. The primary aim of the proposed investigation was to provide a suite of comprehensive two- and three-dimensional analytical benchmarks for neutron transport theory applications. This objective has been achieved. The suite of benchmarks in infinite media and the three-dimensional SLP are a relatively comprehensive set of one-group benchmarks for isotropically scattering media. Because of time and resource limitations, the extensions of the benchmarks to include multi-group and anisotropic scattering are not included here. Presently, however, enormous advances in the solution for the planar Green`s function in an anisotropically scattering medium have been made and will eventually be implemented in the two- and three-dimensional solutions considered under this grant. Of particular note in this work are the numerical results for the three-dimensional SLP, which have never before been presented. The results presented were made possible only because of the tremendous advances in computing power that have occurred during the past decade.

  20. Nuclear structure from radioactive decay

    SciTech Connect

    Wood, J.L.

    1990-09-30

    This report discusses the nuclear structure of the following isotopes as a result of radioactive decays: neutron-deficient iridium isotopes; neutron-deficient platinum isotopes; neutron-deficient gold isotopes; neutron-deficient mercury isotopes; neutron-deficient thallium isotopes; neutron-deficient lead isotopes; neutron-deficient promethium isotopes; and neutron-deficient samarium isotopes.

  1. A short note on physical properties to irradiated nuclear fuel by means of X-ray diffraction and neutron scattering techniques

    NASA Astrophysics Data System (ADS)

    Abdullah, Yusof; Husain, Hishamuddin; Hak, Cik Rohaida Che; Alias, Nor Hayati; Yusof, Mohd Reusmaazran; Kasim, Norasiah Ab; Zali, Nurazila Mat; Mohamed, Abdul Aziz

    2015-04-01

    For nuclear reactor applications, understanding the evolution of the fuel materials microstructure during irradiation are of great importance. This paper reviews the physical properties of irradiated nuclear fuel analysis which are considered to be of most importance in determining the performance behavior of fuel. X-rays diffraction was recognize as important tool to investigate the phase identification while neutron scattering analyses the interaction between uranium and other materials and also investigation of the defect structure.

  2. Detection of Special Nuclear Material in Cargo Containers Using Neutron Interrogation

    SciTech Connect

    Slaughter, D; Accatino, M; Bernstein, A; Candy, J; Dougan, A; Hall, J; Loshak, A; Manatt, D; Meyer, A; Pohl, B; Prussin, S; Walling, R; Weirup, D

    2003-08-01

    The goal of the work reported here is to develop a concept for an active neutron interrogation system that can detect small targets of SNM contraband in cargo containers, roughly 5 kg HEU or 1 kg Pu, even when well shielded by a thick cargo. It is essential that the concept be reliable and have low false-positive and false-negative error rates. It also must be rapid to avoid interruption of commerce, completing the analysis in minutes. A new radiation signature unique to SNM has been identified that utilizes high-energy (E{sub {gamma}} = 3-7 MeV) fission product {gamma}-ray emission. Fortunately, this high-energy {gamma}-ray signature is robust in that it is very distinct compared to normal background radiation where there is no comparable high-energy {gamma}-ray radiation. Equally important, it has a factor of 10 higher yield than delayed neutrons that are the basis of classical interrogation technique normally used on small unshielded specimens of SNM. And it readily penetrates two meters of low-Z and high-Z cargo at the expected density of {approx} 0.5 gm/cm{sup 3}. Consequently, we expect that in most cases the signature flux at the container wall is at least 2-3 decades more intense than delayed neutron signals used historically and facilitates the detection of SNM even when shielded by thick cargo. Experiments have verified this signature and its predicted characteristics. However, they revealed an important interference due to the activation of {sup 16}O by the {sup 16}O(n,p){sup 16}N reaction that produces a 6 MeV {gamma}-ray following a 7-sec {beta}-decay of the {sup 16}N. This interference is important when irradiating with 14 MeV neutrons but is eliminated when lower energy neutron sources are utilized since the reaction threshold for {sup 16}O(n,p){sup 16}N is 10 MeV. The signature {gamma}-ray fluxes exiting a thick cargo can be detected in large arrays of scintillation detectors to produce useful signal count rates of 2-4 x 10{sup 4} cps. That is high

  3. Direct observation of electronic and nuclear ground state splitting in external magnetic field by inelastic neutron scattering on oxidized ferrocene and ferrocene containing polymers

    NASA Astrophysics Data System (ADS)

    Appel, Markus; Frick, Bernhard; Elbert, Johannes; Gallei, Markus; Stühn, Bernd

    2015-01-01

    The quantum mechanical splitting of states by interaction of a magnetic moment with an external magnetic field is well known, e.g., as Zeeman effect in optical transitions, and is also often seen in magnetic neutron scattering. We report excitations observed in inelastic neutron spectroscopy on the redox-responsive polymer poly(vinylferrocene). They are interpreted as splitting of the electronic ground state in the organometallic ferrocene units attached to the polymer chain where a magnetic moment is created by oxidation. In a second experiment using high resolution neutron backscattering spectroscopy we observe the hyperfine splitting, i.e., interaction of nuclear magnetic moments with external magnetic fields leading to sub-μeV excitations observable in incoherent neutron spin-flip scattering on hydrogen and vanadium nuclei.

  4. An apparatus for the study of high temperature water radiolysis in a nuclear reactor: calibration of dose in a mixed neutron/gamma radiation field.

    PubMed

    Edwards, Eric J; Wilson, Paul P H; Anderson, Mark H; Mezyk, Stephen P; Pimblott, Simon M; Bartels, David M

    2007-12-01

    The cooling water of nuclear reactors undergoes radiolytic decomposition induced by gamma, fast electron, and neutron radiation in the core. To model the process, recombination reaction rates and radiolytic yields for the water radical fragments need to be measured at high temperature and pressure. Yields for the action of neutron radiation are particularly hard to determine independently because of the beta/gamma field also present in any reactor. In this paper we report the design of an apparatus intended to measure neutron radiolysis yields as a function of temperature and pressure. A new methodology for separation of neutron and beta/gamma radiolysis yields in a mixed radiation field is proposed and demonstrated.

  5. Application of Neutron-Absorbing Structural-Amorphous Metal (SAM) Coatings for Spent Nuclear Fuel (SNF) Container to Enhance Criticality Safety Controls

    SciTech Connect

    Choi, Jor-Shan; Lee, Chuck; Farmer, Joseph; Day, Dan; Wall, Mark; Saw, Cheng; Boussoufi, Moe; Liu, Ben; Egbert, Harold; Branagan, Dan; D'Amato, Andy

    2007-07-01

    Spent nuclear fuel contains fissionable materials ({sup 235}U, {sup 239}Pu, {sup 241}Pu, etc.). To prevent nuclear criticality in spent fuel storage, transportation, and during disposal, neutron-absorbing materials (or neutron poisons, such as borated stainless steel, Boral{sup TM}, Metamic{sup TM}, Ni-Gd, and others) would have to be applied. The success in demonstrating that the High-Performance Corrosion- Resistant Material (HPCRM){sup [1]} can be thermally applied as coating onto base metal to provide for corrosion resistance for many naval applications raises the interest in applying the HPCRM to USDOE/OCRWM spent fuel management program. The fact that the HPCRM relies on the high content of boron to make the material amorphous - an essential property for corrosion resistance - and that the boron has to be homogeneously distributed in the HPCRM qualify the material to be a neutron poison. (authors)

  6. Angular distribution of products of ternary nuclear fission induced by cold polarized neutrons

    SciTech Connect

    Bunakov, V. E. Kadmensky, S. G. Kadmensky, S. S.

    2008-11-15

    Within quantum fission theory, angular distributions of products originating from the ternary fission of nuclei that is induced by polarized cold and thermal neutrons are investigated on the basis of a non-evaporative mechanism of third-particle emission and a consistent description of fission-channel coupling. It is shown that the inclusion of Coriolis interaction both in the region of the discrete and in the region of the continuous spectrum of states of the system undergoing fission leads to T-odd correlations in the aforementioned angular distributions. The properties of the TRI and ROT effects discovered recently, which are due to the interference between the fission amplitudes of neutron resonances, are explored. The results obtained here are compared with their counterparts from classic calculations based on the trajectory method.

  7. Nuclear structure in the neutron-rich doubly magic sup 78 Ni region

    SciTech Connect

    Hill, J.C.; Wohn, F.K.; Winger, J.A.; Warburton, E.K.; Gill, R.L.; Schuhmann, R.B.; Brookhaven National Lab., Upton, NY; Clark Univ., Worcester, MA )

    1989-01-01

    The magic numbers Z=28 and N=50 imply that very neutron-rich {sup 78}Ni, which has not yet been observed, is doubly magic. The {sup 78}Ni region was investigated by studying the N=50 isotones and neutron-rich Zn isotopes. Results on the level structure of {sup 83}As, {sup 74}Zn, and {sup 76}Zn populated in the decays of {sup 83}Ge, {sup 74}Cu, and {sup 76}Cu are presented. The parent nuclides were produced and mass separated using the TRISTAN facility on-line to the High-Flux Beam Reactor at Brookhaven. The systematics of the N=50 isotones and even-A Zn isotopes are discussed and compared with shell-model calculations involving active nucleons outside of a {sup 78}Ni and {sup 66}Ni core, respectively. The extent to which the {sup 78}Ni region can be considered doubly magic is assessed. 43 refs., 7 figs.

  8. Transmutation of nuclear waste with a low-aspect-ratio tokamak neutron source

    NASA Astrophysics Data System (ADS)

    Hong, Bong Guen; Moon, Se Youn

    2014-10-01

    The transmutation characteristics of transuranics (TRUs) in a transmutation reactor based on a LAR (Low-aspect-ratio) tokamak as a neutron source are investigated. The optimum radial build of a transmutation reactor is found by using a coupled analysis of the tokamak systems and the neutron transport. The dependences of the transmutation characteristics on the aspect ratio A in the range of 1.5 to 2.5 and on the fusion power in the range of 150 to 500 MW are investigated. An equilibrium fuel cycle is developed for effective transmutation, and show that with one unit of the transmutation reactor based on the LAR tokamak producing fusion power in the range of a few hundred MWs, up to 3 PWRs (1.0 GWe capacity) can be supported with a burn-up fraction larger than 50%.

  9. Effect of pre-equilibrium emission on probing postsaddle nuclear dissipation with neutrons

    NASA Astrophysics Data System (ADS)

    Tian, Jian; Ye, Wei

    2016-09-01

    Using the stochastic Langevin model coupled with a statistical decay model, we study the influence of pre-equilibrium (PE) emission on probing postsaddle friction (β) with neutrons. A postsaddle friction value of (14 ‑ 16.5) × 1021 s‑1 and (11 ‑ 13) × 1021 s‑1 is obtained from comparing calculated and measured prescission neutron multiplicities of heavy fissioning systems 248Fm and 256Fm in the absence and presence of the deformation factor. Moreover, it is found that a larger β is required to fit multiplicity data after the PE effect is accounted for, and that the effect becomes stronger when more energy is removed by PE particles. Our findings suggest that, to more accurately determine the postsaddle friction strength through the measurement of prescission neutrons, in addition to incorporating the contribution of PE evaporation source into the experimental multi-source analysis for particle energy spectra in coincidence with fission fragments, on the theoretical side, it is very important to make a precise evaluation of the energy that PE emission carries away from excited compound systems produced in heavy-ion fusion reactions. Supported by National Nature Science Foundation of China (11575044)

  10. Effect of pre-equilibrium emission on probing postsaddle nuclear dissipation with neutrons

    NASA Astrophysics Data System (ADS)

    Tian, Jian; Ye, Wei

    2016-09-01

    Using the stochastic Langevin model coupled with a statistical decay model, we study the influence of pre-equilibrium (PE) emission on probing postsaddle friction (β) with neutrons. A postsaddle friction value of (14 - 16.5) × 1021 s-1 and (11 - 13) × 1021 s-1 is obtained from comparing calculated and measured prescission neutron multiplicities of heavy fissioning systems 248Fm and 256Fm in the absence and presence of the deformation factor. Moreover, it is found that a larger β is required to fit multiplicity data after the PE effect is accounted for, and that the effect becomes stronger when more energy is removed by PE particles. Our findings suggest that, to more accurately determine the postsaddle friction strength through the measurement of prescission neutrons, in addition to incorporating the contribution of PE evaporation source into the experimental multi-source analysis for particle energy spectra in coincidence with fission fragments, on the theoretical side, it is very important to make a precise evaluation of the energy that PE emission carries away from excited compound systems produced in heavy-ion fusion reactions. Supported by National Nature Science Foundation of China (11575044)

  11. INL Capabilities For Nuclear Data Measurements Using The Argonne Intense Pulsed Neutron Source Facility

    SciTech Connect

    R. Aryaeinejad; D. W. Nigg; R.V.F. Janssens; B. J. Micklich; G. Ter-Akopian; J. D. Cole

    2005-07-01

    The relevant facts concerning the Argonne National Laboratory – Intense Pulsed Neutron Source (ANL/IPNS) and the Idaho National Laboratory (INL) apparatus for use at the ANL/IPNS facility to measure differential neutron interaction cross sections of interest for advanced reactor physics applications are presented. The INL apparatus, which consists of an array of multiple types of multiple detectors operated in coincidence, signal electronics, and a data acquisition system, is presented as an application of new means and methods to measure the relevant parameters described. The immediate measurement goals involve measurement of neutron induced interaction cross sections for 240Pu and 242Pu with 241Pu, 241Am, with measurements for other nuclides of interest for advanced reactor physics applications to follow later. Specific uncertainties and error limits are presented and methods for controlling these uncertainties are described. The post experiment analysis using data sorts and data selection from a large, self-consistent data set to produce spectra that will be analyzed for direct results and used to determine cross sections is also discussed.

  12. Comparison of codes and neutron IC data used in US and Russia for the Topaz-II nuclear reactor assessment

    SciTech Connect

    Glushkov, Y.S.; Ponomarev-Stepnoi, N.N.; Kompanietz, G.V.; Gomin, Y.A.; Maiorov, L.V.; Lobynstev, V.A.; Polyakov, D.N.; Sapir, J.; Streetman, J.R.

    1993-11-01

    Topaz-II is a heterogeneous, epithermal reactor, fueled with highly enriched uranium-dioxide, cooled with NaK, and moderated with zirconium-hydride. The reactor core contains 37 single-cell thermionic fuel elements, and is surrounded by a radial beryllium reflector that contains 12 rotatable control drums with poison segments. For the physics analysis of TOPAZ II it is necessary to use the Monte Carlo method. The United States (US) and Russia used two different Monte Carlo codes, namely MCNP and MCU-2, respectively. The work described in this paper was aimed at comparing the codes and neutronic data used in the US and Russia for verification of Topaz-II nuclear safety. For this purpose, the US and Russia developed a joint benchmark model of the Topaz-II reactor. The American and Russian teams performed independent computations for a series of variants representing potential water immersion accidents. Comparison of the MCNP and MCU-2 codes showed somewhat different results both for the absolute values of k{sub eff} and for reactivity effects. Future calculations will be performed to obtain a detailed understanding of the reasons for such discrepancies. For these analyses it will be necessary for the US and Russian teams to exchange neutronic data on Topaz-II physics calculations.

  13. A critical assembly designed to measure neutronic benchmarks in support of the Space Nuclear Thermal Propulsion program

    NASA Astrophysics Data System (ADS)

    Parma, E. J.; Ball, R. M.; Hoovler, G. S.; Selcow, E. C.; Cerbone, R. J.

    1992-10-01

    A reactor designed to perform criticality experiments in support of the Space Nuclear Thermal Propulsion program is currently in operation at the Sandia National Laboratories' reactor facility. The reactor is a small, water-moderated system that uses highly enriched uranium particle fuel in a 19-element configuration. Its purpose is to obtain neutronic measurements under a variety of experimental conditions that are subsequently used to benchmark reactor-design computer codes. Brookhaven National Laboratory, Babcock & Wilcox, and Sandia National Laboratories participated in determining the reactor's performance requirements, design, follow on experimentation, and in obtaining the licensing approvals. Brookhaven National Laboratory is primarily responsible for the analytical support, Babcock & Wilcox the hardware design, and Sandia National Laboratories the operational safety. All of the team members participate in determining the experimentation requirements, performance, and data reduction. Initial criticality was achieved in October 1989. An over-all description of the reactor is presented along with key design features and safety-related aspects.

  14. A critical assembly designed to measure neutronic benchmarks in support of the space nuclear thermal propulsion program

    NASA Astrophysics Data System (ADS)

    Parma, Edward J.; Ball, Russell M.; Hoovler, Gary S.; Selcow, Elizabeth C.; Cerbone, Ralph J.

    1993-01-01

    A reactor designed to perform criticality experiments in support of the Space Nuclear Thermal Propulsion program is currently in operation at the Sandia National Laboratories' reactor facility. The reactor is a small, water-moderated system that uses highly enriched uranium particle fuel in a 19-element configuration. Its purpose is to obtain neutronic measurements under a variety of experimental conditions that are subsequently used to benchmark rector-design computer codes. Brookhaven National Laboratory, Babcock & Wilcox, and Sandia National Laboratories participated in determining the reactor's performance requirements, design, follow-on experimentation, and in obtaining the licensing approvals. Brookhaven National Laboratory is primarily responsible for the analytical support, Babcock & Wilcox the hardware design, and Sandia National Laboratories the operational safety. All of the team members participate in determining the experimentation requirements, performance, and data reduction. Initial criticality was achieved in October 1989. An overall description of the reactor is presented along with key design features and safety-related aspects.

  15. Predicting fissile content of spent nuclear fuel assemblies with the passive neutron Albedo reactivity technique and Monte Carlo code emulation

    SciTech Connect

    Conlin, Jeremy Lloyd; Tobin, Stephen J

    2010-10-13

    There is a great need in the safeguards community to be able to nondestructively quantify the mass of plutonium of a spent nuclear fuel assembly. As part of the Next Generation of Safeguards Initiative, we are investigating several techniques, or detector systems, which, when integrated, will be capable of quantifying the plutonium mass of a spent fuel assembly without dismantling the assembly. This paper reports on the simulation of one of these techniques, the Passive Neutron Albedo Reactivity with Fission Chambers (PNAR-FC) system. The response of this system over a wide range of spent fuel assemblies with different burnup, initial enrichment, and cooling time characteristics is shown. A Monte Carlo method of using these modeled results to estimate the fissile content of a spent fuel assembly has been developed. A few numerical simulations of using this method are shown. Finally, additional developments still needed and being worked on are discussed.

  16. Propagation of nuclear burning fronts on accreting neutron stars: X-ray bursts and sub-hertz noise

    NASA Technical Reports Server (NTRS)

    Bildsten, Lars

    1995-01-01

    We identify a new regime of time dependent helium burning for high accretion rate neutron stars and suggest that this burning is the origin of the low-level luminosity variations (on timescales of 10-10(exp 4) s, designated the 'very low-frequency noise'(VLFN) by van der Klis and collaborators) always detected in the brightest accreting X-ray sources. Only two nuclear burning regimes were previously recognized. At accretion rates in excess of the Eddington limit (dot-M approximately greater than (1-3) x 10(exp -8) solar mass/yr), the accreted matter fuses steadily. At very low dot-M, the star's entire surface is rapidly (approximately less than 10 s) burned by a fast propagating convective burning front at regular intervals, giving quasi-periodic Type I X-ray bursts. We show that for the observationally interesting range of 5 x 10(exp -10) solar mass/yr approximately less than dot-M approximately less than 10(exp -8) solar mass/yr, parts of the stellar surface burn slowly. At these accretion rates, a local thermonuclear instability starts a fire which propagates horizontally at v approximately 300 cm/s. The fire propagates around the flammable surface in roughly the same time it takes to accrete enough fuel for the next instability (approximately 10(exp 3)-10(exp 4), so that only a few fires are burning at once, giving rise to large luminosity flares. Nuclear burning is always time dependent for sub-Eddington local accretion rates: a local patch undergoes a recurrent cycle, accumulation fuel for hours until it becomes thermally unstable or is 'ignited' by a nearby burning region. The global pattern of burning and the resulting luminosity are thus very dependent on how fast nuclear fires spread around the star. The nuclear burning luminosity is not uniform over the stellar surface and so may provide a handle on measuring, or constraining, the spin periods of these neutron stars.

  17. Neutronics of accelerator-driven subcritical fission for burning transuranics in used nuclear fuel

    SciTech Connect

    Sattarov, A.; Assadi, S.; Badgley, K.; Baty, A.; Comeaux, J.; Gerity, J.; Kellams, J.; Mcintyre, P.; Pogue, N.; Sooby, E.; Tsvetkov, P.; Rosaire, G.; Mann, T.

    2013-04-19

    We report the development of a conceptual design for accelerator-driven subcritical fission in a molten salt core (ADSMS). ADSMS is capable of destroying all of the transuranics at the same rate and proportion as they are produced in a conventional nuclear power plant. The ADSMS core is fueled solely by transuranics extracted from used nuclear fuel and reduces its radiotoxicity by a factor 10,000. ADSMS offers a way to close the nuclear fuel cycle so that the full energy potential in the fertile fuels uranium and thorium can be recovered.

  18. Neutronics of accelerator-driven subcritical fission for burning transuranics in used nuclear fuel

    NASA Astrophysics Data System (ADS)

    Sattarov, A.; Assadi, S.; Badgley, K.; Baty, A.; Comeaux, J.; Gerity, J.; Kellams, J.; Mcintyre, P.; Pogue, N.; Sooby, E.; Tsvetkov, P.; Rosaire, G.; Mann, T.

    2013-04-01

    We report the development of a conceptual design for accelerator-driven subcritical fission in a molten salt core (ADSMS). ADSMS is capable of destroying all of the transuranics at the same rate and proportion as they are produced in a conventional nuclear power plant. The ADSMS core is fueled solely by transuranics extracted from used nuclear fuel and reduces its radiotoxicity by a factor 10,000. ADSMS offers a way to close the nuclear fuel cycle so that the full energy potential in the fertile fuels uranium and thorium can be recovered.

  19. Skin Dictionary

    MedlinePlus

    ... your skin, hair, and nails Skin dictionary Camp Discovery Good Skin Knowledge lesson plans and activities Video library Find a ... your skin, hair, and nails Skin dictionary Camp Discovery Good Skin Knowledge lesson plans and activities Video library Find a ...

  20. Determination of optimal imaging parameters for the reconstruction of a nuclear fuel assembly using limited angle neutron tomography

    NASA Astrophysics Data System (ADS)

    Abir, M. I.; Islam, F. F.; Craft, A.; Williams, W. J.; Wachs, D. M.; Chichester, D. L.; Meyer, M. K.; Lee, H. K.

    2016-01-01

    The core components of nuclear reactors (e.g., fuel assemblies, spacer grids, control rods) encounter harsh environments due to high temperature, physical stress, and a tremendous level of radiation. The integrity of these elements is crucial for safe operation of nuclear power plants; post-irradiation examination (PIE) can reveal information about the integrity of these components. Neutron computed tomography (CT) is one important PIE measurement tool for nondestructively evaluating the structural integrity of these items. CT typically requires many projections to be acquired from different view angles, after which a mathematical algorithm is used for image reconstruction. However, when working with heavily irradiated materials and irradiated nuclear fuel, obtaining many projections is laborious and expensive. Image reconstruction from a smaller number of projections has been explored to achieve faster and more cost-efficient PIE. Classical reconstruction methods (e.g., filtered backprojection), unfortunately, do not typically offer stable reconstructions from a highly asymmetric, few-projection data set and often create severe streaking artifacts. We propose an iterative reconstruction technique to reconstruct curved, plate-type nuclear fuel assemblies using limited-angle CT. The performance of the proposed method is assessed using simulated data and validated through real projections. We also discuss the systematic strategy for establishing the conditions of reconstructions and finding the optimal imaging parameters for reconstructions of the fuel assemblies from few projections using limited-angle CT. Results show that a fuel assembly can be reconstructed using limited-angle CT if 36 or more projections are taken from a particular direction with 1° angular increment.

  1. Comparison of Codes and Neutronics Data Used in the United States and Russia for the TOPAZ-2 Nuclear Safety Assessment

    NASA Astrophysics Data System (ADS)

    Glushkov, Y. S.; Ponomarov-Stepnoy, N. N.; Kompaniets, G. V.; Gomin, Y. A.; Mayorov, L. V.; Lobyntsev, V. A.; Polyakov, D. N.; Sapir, Joe; Pelowitz, Denise; Streetman, J. Robert

    1994-07-01

    The TOPAZ-2 reactor system is a heterogeneous epithermal system fueled with highly-enriched fuel based on uranium oxide, cooled by a sodium-potassium liquid metal (NaK), using a zirconium hydride moderator, with 37 thermionic fuel elements (TFEs) built into the core. The core is surrounded by a radial beryllium reflector which contains rotating regulating drums with moderating segments. An important problem is the guaranteeing of nuclear safety upon the accidental falling of the TOPAZ-2 reactor into water, which leads to the growth of the reactivity of the reactor. It has turned out that it is necessary to use the Monte-Carlo method for the conduct of neutronics calculations of such a complex reactor. In the United States (U.S.) and Russia, different codes based on the Monte-Carlo method are used for calculations - the MCNP code in the U.S., and the MCU-2 code in Russia. The goal of this work is the comparison of the codes and neutronics data used in the U.S. and Russia for the basis of the TOPAZ-2 nuclear safety. With this goal, a joint computer model benchmark of the TOPAZ-2 reactor was developed and the calculations of a series of variants, differing by the presence and absence of water in the reactor cavities and behind the radial reflector, in the position of the regulating drums, in the presence of the radial reflector, etc. were done independently by specialists in both the U.S. and Russia. Along with the reactor calculations, calculations were also done of the nuclei of the core using the MCNP code (U.S.) and the MCU-2 code (Russia). The work done allowed one to obtain results comparing the MCNP code to the MCU-2 code which gave somewhat different results both for the absolute values of Keff and for reactivity effects. In the future it remains to conduct a detailed analysis of the reasons for the discrepancies. For this it is necessary to exchange neutronics data used for TOPAZ-2 reactor calculations in the U.S. and Russia.

  2. Exotic States of Nuclear Matter

    NASA Astrophysics Data System (ADS)

    Lombardo, Umberto; Baldo, Marcello; Burgio, Fiorella; Schulze, Hans-Josef

    2008-02-01

    hadronization, Hawking-Unruh radiation and event horizon in QCD / P. Castorina. Ferromagnetism in the QCD phase diagram / T. Tatsumi. Asymmetric neutrino emission in quark matter and pulsar kicks / I. Sagert & J. Schaffner-Bielich. Effects of the transition of neutron stars to quark stars on the cooling / T. Noda ... [et al.]. The energy release - stellar angular momentum independence in rotating compact stars undergoing first-order phase transitions / M. Bejger ... [et al.]. Hyperon-quark mixed phase in dense matter / T. Maruyama ... [et al.]. Nucleation of quark matter in neutron stars: role of color superconductivity / I. Bombaci, G. Lugones & I. Vidaña. The bulk viscosity and r-mode instability of strange quark matter / B. A. Sa'd. Neutrino trapping in neutron stars in the presence of Kaon condensation / A. Li ... [et al.]. P. Auger Observatory: status and preliminary results / A. Insolia -- pt. F. Nuclear structure from laboratory to stars. Recent advances in the theory of nuclear forces and its impact on microscopic nuclear structure / R. Machleidt. Kohn-Sham density functional approach to nuclear binding / X. Viñas ... [et al.]. Structure and decay of Kaon-condensed hypernuclei / T. Muto. Isoscalar and isovector nuclear matter properties and giant resonances / H. Sagawa & S. Yoshida. The Skyrme interaction and its tensor component / G. Col, P. F. Bortignon & H. Sagawa. Spin-isospin physics and ICHOR project / H. Sakai for the ICHOR collaboration. Neutron skin thickness of [symbol]Zr determined by (p, n) and (n, p) reactions / K. Yako, H. Sakai & H. Sagawa. Synthesis of super-heavy nuclei in a modified di-nuclear system model / E. G. Zhao et al. -- pt. G. Nuclear superfluidity. Mesoscopic treatment of superfluid neutron current in solid star crust / B. Carter. Equation of state in the inner crust of neutron stars: discussion of the unbound neutrons states / J. Margueron, N. Van Giai & N. Sandulescu. Pairing and bound states in nuclear matter / J. W. Clark & A. Sedrakian

  3. Nuclear shape and structure in neutron-rich 110,111Tc

    SciTech Connect

    Luo, Y.X.; Hamilton, J.H.; Rasmussen, J.O.; Ramayya, A.V.; Stefanescu, I.; Hwang, J.K.; Zhu, S.J.; Gore, P.M.; Jones, E.F.; Fong,D.; Wu, S.C.; Lee, I.Y.; Ginter, T.N.; Ter-Akopian, G.M.; Daniel, A.V.; Stoyer, M.A.; Donangelo, R.; Gelberg, A.

    2006-02-02

    The structure of Tc nuclei is extended to the moreneutron-rich regions based on measurements of prompt gamma rays from thespontaneous fission of 252Cf at Gammasphere. The level scheme of N=67neutron-rich (Z=43) 110Tc is established for the first time and that of111Tc is expanded. The ground-state band of 111Tc reaches theband-crossing region and the new observation of the weakly populatedalpha = -1/2 member of the band provides important information ofsignature splitting. The systematics of band crossings in the isotopicand isotonic chains and a CSM calculation suggest that the band crossingof the gs band of 111Tc is due to alignment of a pair of h11/2 neutrons.The best fit to signature splitting, branching ratios, and excitations ofthe ground-state band of 111Tc by RTRP model calculations result in ashape of epsilon2 = 0.32 and gamma = -26 deg. for this nucleus. Itstriaxiality is larger than that of 107Tc, to indicate increasingtriaxiality with increasing neutron number. The identification of theweakly-populated "K+2 satellite" band provides strong evidence for thelarge triaxiality of 111Tc. In 110Tc the four lowest-lying levelsobserved are very similar to those in 108Tc. At an excitation of 478.9keV above the lowest state observed, ten states of a delta I = 1 band areobserved. This band is very analogous to the delta I = 1 bands in106,108Tc, but it has greater signature splitting at higherspins.

  4. Nuclear structure of the odd-odd N=85 neutron-rich nucleus {sup 140}Cs

    SciTech Connect

    Liu, S. H.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Luo, Y. X.; Rasmussen, J. O.; Daniel, A. V.; Ter-Akopian, G. M.; Zhu, S. J.; Ma, W. C.

    2010-03-15

    High-spin excited states in the neutron-rich nucleus {sup 140}Cs were re-investigated from the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. Seven new transitions at low and moderate spin and 13 at high spin were observed in {sup 140}Cs and the level scheme of {sup 140}Cs was extended to 3794 keV with a new sideband. Spins and parities were assigned to levels based on angular correlation measurements and the systematics in the N=85 isotones.

  5. Atomic parity nonconservation, neutron radii, and effective field theories of nuclei

    SciTech Connect

    Sil, Tapas; Centelles, M.; Vinas, X.; Piekarewicz, J.

    2005-04-01

    Accurately calibrated effective field theories are used to compute atomic parity nonconserving (APNC) observables. Although accurately calibrated, these effective field theories predict a large spread in the neutron skin of heavy nuclei. Whereas the neutron skin is strongly correlated to numerous physical observables, in this contribution we focus on its impact on new physics through APNC observables. The addition of an isoscalar-isovector coupling constant to the effective Lagrangian generates a wide range of values for the neutron skin of heavy nuclei without compromising the success of the model in reproducing well-constrained nuclear observables. Earlier studies have suggested that the use of isotopic ratios of APNC observables may eliminate their sensitivity to atomic structure. This leaves nuclear structure uncertainties as the main impediment for identifying physics beyond the standard model. We establish that uncertainties in the neutron skin of heavy nuclei are at present too large to measure isotopic ratios to better than the 0.1% accuracy required to test the standard model. However, we argue that such uncertainties will be significantly reduced by the upcoming measurement of the neutron radius in {sup 208}Pb at the Jefferson Laboratory.

  6. Neutron activation analysis of nuclides from stellar and man-induced nuclear reactions

    NASA Astrophysics Data System (ADS)

    Oliver, L. L.

    Neutron activation and gamma counting were used to determine the relative abundances of six stable tellurium isotopes in the acid-etched residues of the Allende meteorite. The results were correlated with the isotopic compositions of xenon and the elemental abundances of helium and neon in similarly prepared residues. Nucleosynthesis appears to be the only viable explanation or the anomalous isotopic and elemental compositions observed in these residues. Results suggest that the solar system condensed from an isotopically and chemically zoned nebula that was produced by the explosion of a supernova, concentric with the present Sun. A combination of neutron activation and mass spectrometry was used to determine the concentrations of fissiogenic iodine 129 and stable iodine 127 in rain, milk and the thyroids of man, cow and deer from Missouri. Rain and deer thyroids show the highest average values of the iodine 129/iodine 127 ratio. Milk and the thyroids of cattle and humans show successively lower values of the iodine 129/iodine 127 ratio due to dietary additives of mineral iodine and to biological averaging.

  7. Coupled thermohydraulic-neutronic instabilities in boiling water nuclear reactors: A review of the state of the art

    SciTech Connect

    March-Leuba, J. ); Rey, J.M. )

    1992-01-01

    This paper provides a review of the current state of the art on the topic of coupled neutronic-thermohydraulic instabilities in boiling water nuclear reactors (BWRs). The topic of BWR instabilities is of great current relevance since it affects the operation of a large number of commercial nuclear reactors. The recent trends towards introduction of high efficiency fuels that permit reactor operation at higher power densities with increased void reactivity feedback and decreased response times, has resulted in a decrease of the stability margin in the low-flow, high-power region of the operating map. This trend has resulted in a number of unexpected'' instability events. For instance, United States plants have experienced two instability events recently, one of them resulted in an automatic reactor scram; in Spain, two BWR plants have experienced unstable limit cycle oscillations that required operator action to suppress. Similar events have been experienced in other European countries. In recent years, BWR instabilities have been one of the more exciting topics of work in the area of transient thermohydraulics. As a result, significant advances in understanding the physics behind these events have occurred, and a new and improved'' state of the art has emerged recently.

  8. Coupled thermohydraulic-neutronic instabilities in boiling water nuclear reactors: A review of the state of the art

    SciTech Connect

    March-Leuba, J.; Rey, J.M.

    1992-05-01

    This paper provides a review of the current state of the art on the topic of coupled neutronic-thermohydraulic instabilities in boiling water nuclear reactors (BWRs). The topic of BWR instabilities is of great current relevance since it affects the operation of a large number of commercial nuclear reactors. The recent trends towards introduction of high efficiency fuels that permit reactor operation at higher power densities with increased void reactivity feedback and decreased response times, has resulted in a decrease of the stability margin in the low-flow, high-power region of the operating map. This trend has resulted in a number of ``unexpected`` instability events. For instance, United States plants have experienced two instability events recently, one of them resulted in an automatic reactor scram; in Spain, two BWR plants have experienced unstable limit cycle oscillations that required operator action to suppress. Similar events have been experienced in other European countries. In recent years, BWR instabilities have been one of the more exciting topics of work in the area of transient thermohydraulics. As a result, significant advances in understanding the physics behind these events have occurred, and a ``new and improved`` state of the art has emerged recently.

  9. Symmetry energy and surface properties of neutron-rich exotic nuclei

    SciTech Connect

    Gaidarov, M. K.; Antonov, A. N.; Sarriguren, P.; Moya de Guerra, E.

    2014-07-23

    The symmetry energy, the neutron pressure and the asymmetric compressibility of spherical Ni, Sn, and Pb and deformed Kr and Sm neutron-rich even-even nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the deformed self-consistent mean-field Skyrme HF+BCS method. The mass dependence of the nuclear symmetry energy and the neutron skin thickness are also studied together with the role of the neutron-proton asymmetry. The studied correlations reveal a smoother behavior in the case of spherical nuclei than for deformed ones. We also notice that the neutron skin thickness obtained for {sup 208}Pb with SLy4 force is found to be in a good agreement with the recent data. In addition to the interest that this study may have by itself, we give some numerical arguments in proof of the existence of peculiarities of the studied quantities in Ni and Sn isotopic chains that are not present in the Pb chain.

  10. Compilation and evaluation of 14-MeV neutron-activation cross sections for nuclear technology applications. Set I

    SciTech Connect

    Evain, B.P.; Smith, D.L.; Lucchese, P.

    1985-04-01

    Available 14-MeV experimental neutron activation cross sections are compiled and evaluated for the following reactions of interest for nuclear-energy technology applications: /sup 27/Al(n,p)/sup 27/Mg, Si(n,X)/sup 28/Al, Ti(n,X)/sup 46/Sc, Ti(n,X)/sup 47/Sc, Ti(n,X)/sup 48/Sc, /sup 51/V(n,p)/sup 51/Ti, /sup 51/V(n,..cap alpha..)/sup 48/Sc, Cr(n,X)/sup 52/V, /sup 55/Mn(n,..cap alpha..)/sup 52/V, /sup 55/Mn(n,2n)/sup 54/Mn, Fe(n,X)/sup 54/Mn, /sup 54/Fe(n,..cap alpha..)/sup 51/Cr, /sup 59/Co(n,p)/sup 59/Fe, /sup 59/Co(n,..cap alpha..)/sup 56/Mn, /sup 59/Co(n,2n)/sup 58/Co, /sup 65/Cu(n,p)/sup 65/Ni, Zn(n,X)/sup 64/Cu, /sup 64/Zn(n,2n)/sup 63/Zn, /sup 113/In(n,n')/sup 113m/In, /sup 115/In(n,n') /sup 115m/In. The compiled values are listed and plotted for reference without adjustments. From these collected results those values for which adequate supplementary information on nuclear constants, standards and experimental errors is provided are selected for use in reaction-by-reaction evaluations. These data are adjusted as needed to account for recent revisions in the nuclear constants and cross section standards. The adjusted results are subsequently transformed to equivalent cross sections at 14.7 MeV for the evaluation process. The evaluations are performed utilizing a least-squares method which considers correlations between the experimental data. 440 refs., 41 figs., 46 tabs.

  11. Neutron irradiation damage of nuclear graphite studied by high-resolution transmission electron microscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Krishna, R.; Jones, A. N.; McDermott, L.; Marsden, B. J.

    2015-12-01

    Nuclear graphite components are produced from polycrystalline artificial graphite manufacture from a binder and filler coke with approximately 20% porosity. During the operational lifetime, nuclear graphite moderator components are subjected to fast neutron irradiation which contributes to the change of material and physical properties such as thermal expansion co-efficient, young's modulus and dimensional change. These changes are directly driven by irradiation-induced changes to the crystal structure as reflected through the bulk microstructure. It is therefore of critical importance that these irradiation changes and there implication on component property changes are fully understood. This work examines a range of irradiated graphite samples removed from the British Experimental Pile Zero (BEPO) reactor; a low temperature, low fluence, air-cooled Materials Test Reactor which operated in the UK. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) have been employed to characterise the effect of increased irradiation fluence on graphite microstructure and understand low temperature irradiation damage processes. HRTEM confirms the structural damage of the crystal lattice caused by irradiation attributed to a high number of defects generation with the accumulation of dislocation interactions at nano-scale range. Irradiation-induced crystal defects, lattice parameters and crystallite size compared to virgin nuclear graphite are characterised using selected area diffraction (SAD) patterns in TEM and Raman Spectroscopy. The consolidated 'D'peak in the Raman spectra confirms the formation of in-plane point defects and reflected as disordered regions in the lattice. The reduced intensity and broadened peaks of 'G' and 'D' in the Raman and HRTEM results confirm the appearance of turbulence and disordering of the basal planes whilst maintaining their coherent layered graphite structure.

  12. Neutron matter, symmetry energy and neutron stars

    SciTech Connect

    Stefano, Gandolfi; Steiner, Andrew W

    2016-01-01

    Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

  13. Low energy nuclear spin excitations in Ho metal investigated by high resolution neutron spectroscopy.

    PubMed

    Chatterji, Tapan; Jalarvo, Niina

    2013-04-17

    We have investigated the low energy excitations in metallic Ho by high resolution neutron spectroscopy. We found at T = 3 K clear inelastic peaks in the energy loss and energy gain sides, along with the central elastic peak. The energy of this low energy excitation, which is 26.59 ± 0.02 μeV at T = 3 K, decreased continuously and became zero at TN ≈ 130 K. By fitting the data in the temperature range 100-127.5 K with a power law we obtained the power-law exponent β = 0.37 ± 0.02, which agrees with the expected value β = 0.367 for a three-dimensional Heisenberg model. Thus the energy of the low energy excitations can be associated with the order parameter.

  14. Exact calculations of nuclear-recoil energies from prompt gamma decays resulting from neutron capture

    SciTech Connect

    Kinney, J.H.

    1981-07-20

    The results of an accurate determination of the recoil spectrum from (n, ..gamma..) reactions in molybdenum are presented. The recoil spectrum has been calculated from nuclear level structure data and measured branching ratios. Angular correlations between successive gammas have been accounted for using the standard theoretical techniques of Racah algebra and the density matrix formalism.

  15. Georgia Tech Studies of Sub-Critical Advanced Burner Reactors with a D-T Fusion Tokamak Neutron Source for the Transmutation of Spent Nuclear Fuel

    NASA Astrophysics Data System (ADS)

    Stacey, W. M.

    2009-09-01

    The possibility that a tokamak D-T fusion neutron source, based on ITER physics and technology, could be used to drive sub-critical, fast-spectrum nuclear reactors fueled with the transuranics (TRU) in spent nuclear fuel discharged from conventional nuclear reactors has been investigated at Georgia Tech in a series of studies which are summarized in this paper. It is found that sub-critical operation of such fast transmutation reactors is advantageous in allowing longer fuel residence time, hence greater TRU burnup between fuel reprocessing stages, and in allowing higher TRU loading without compromising safety, relative to what could be achieved in a similar critical transmutation reactor. The required plasma and fusion technology operating parameter range of the fusion neutron source is generally within the anticipated operational range of ITER. The implications of these results for fusion development policy, if they hold up under more extensive and detailed analysis, is that a D-T fusion tokamak neutron source for a sub-critical transmutation reactor, built on the basis of the ITER operating experience, could possibly be a logical next step after ITER on the path to fusion electrical power reactors. At the same time, such an application would allow fusion to contribute to meeting the nation's energy needs at an earlier stage by helping to close the fission reactor nuclear fuel cycle.

  16. Diagnostic and Impact Estimation of Nuclear Data Inconsistencies on Energy Deposition Calculations in Coupled Neutron-Photon Monte-Carlo Simulation, with TRIPOLI-4®

    NASA Astrophysics Data System (ADS)

    Péron, A.; Malouch, F.; Zoia, A.; Diop, C. M.

    2014-06-01

    Nuclear heating evaluation by Monte-Carlo simulation requires coupled neutron-photon calculation so as to take into account the contribution of secondary photons. Nuclear data are essential for a good calculation of neutron and photon energy deposition and for secondary photon generation. However, a number of isotopes of the most common nuclear data libraries happen to be affected by energy and/or momentum conservation errors concerning the photon production or inaccurate thresholds for photon emission sections. In this paper, we perform a comprehensive survey of the three evaluations JEFF3.1.1, JEFF3.2T2 (beta version) and ENDF/B-VII.1, over 142 isotopes. The aim of this survey is, on the one hand, to check the existence of photon production data by neutron reaction and, on the other hand, to verify the consistency of these data using the kinematic limits method recently implemented in the TRIPOLI-4 Monte-Carlo code, developed by CEA (Saclay center). Then, the impact of these inconsistencies affecting energy deposition scores has been estimated for two materials using a specific nuclear heating calculation scheme in the context of the OSIRIS Material Testing Reactor (CEA/Saclay).

  17. Relativistic mean field models for finite nuclei and neutron stars

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Chia

    In this dissertation we have created theoretical models for finite nuclei, nuclear matter, and neutron stars within the framework of relativistic mean field (RMF) theory, and we have used these models to investigate the elusive isovector sector and related physics, in particular, the neutron-skin thickness of heavy nuclei, the nuclear symmetry energy, and the properties of neutron stars. To build RMF models that incorporate collective excitations in finite nuclei in addition to their ground-state properties, we have extended the non-relativistic sum rule approach to the relativistic domain. This allows an efficient estimate of giant monopole energies. Moreover, we have combined an exact shell-model-like approach with the mean-field calculation to describe pairing correlations in open-shell nuclei. All the ingredients were then put together to establish the calibration scheme. We have also extended the transformation between model parameters and pseudo data of nuclear matter within the RMF context. Performing calibration in this pseudo data space can not only facilitate the searching algorithm but also make the pseudo data genuine model predictions. This calibration scheme is also supplemented by a covariance analysis enabling us to extract the information content of a model, including theoretical uncertainties and correlation coefficients. A series of RMF models subject to the same isoscalar constraints but one differing isovector assumption were then created using this calibration scheme. By comparing their predictions of the nuclear matter equation of state to both experimental and theoretical constraints, we found that a small neutron skin of about 0.16 fm in Pb208 is favored, indicating that the symmetry energy should be soft. To obtain stronger evidence, we proceeded to examine the evolution of the isotopic chains in both oxygen and calcium. Again, it was found that the model with such small neutron skin and soft symmetry energy can best describe both isotopic

  18. Measurement/Evaluation Techniques and Nuclear Data Associated with Fission of 239Pu by Fission Spectrum Neutrons

    SciTech Connect

    Baisden, P; Bauge, E; Ferguson, J; Gilliam, D; Granier, T; Jeanloz, R; McMillan, C; Robertson, D; Thompson, P; Verdon, C; Wilkerson, C; Young, P

    2010-03-16

    This Panel was chartered to review and assess new evaluations of work on fission product data, as well as the evaluation process used by the two U.S. nuclear weapons physics laboratories. The work focuses on fission product yields resulting from fission spectrum neutrons incident on plutonium, and includes data from measurements that had not been previously published as well as new or revised fission product cumulative yield data, and related quantities such as Q values and R values. This report documents the Panel's assessment of the work presented by Los Alamos National Laboratory (LANL) and Lawrence Livermore National Laboratory (LLNL). Based on the work presented we have seven key observations: (1) Experiments conducted in the 1970s at LANL, some of which were performed in association with a larger, NIST-led, program, have recently been documented. A preliminary assessment of this work, which will be referred to in this document as ILRR-LANL, shows it to be technically sound. (2) LLNL has done a thorough, unbiased review and evaluation of the available literature and is in the process of incorporating the previously unavailable LANL data into its evaluation of key fission product yields. The results of the LLNL effort, which includes a preliminary evaluation of the ILRR-LANL data, have been documented. (3) LANL has also conducted an evaluation of fission product yields for fission spectrum neutrons on plutonium including a meta-analysis of benchmark data as part of a planned upgrade to the ENDF/B compilation. We found that the approach of using meta-analysis provides valuable additional insight for evaluating the sparse data sets involved in this assessment. (4) Both laboratories have provided convincing evidence for energy dependence in the fission product yield of {sup 147}Nd produced from the bombardment of {sup 239}Pu with fission spectrum neutrons over an incident neutron energy range of 0.2 to 1.9 MeV. (5) Consistent, complete, and explicit treatment of

  19. Neutronic reactor

    DOEpatents

    Carleton, John T.

    1977-01-25

    A graphite-moderated nuclear reactor includes channels between blocks of graphite and also includes spacer blocks between adjacent channeled blocks with an axis of extension normal to that of the axis of elongation of the channeled blocks to minimize changes in the physical properties of the graphite as a result of prolonged neutron bombardment.

  20. NEUTRONIC REACTORS

    DOEpatents

    Anderson, H.L.

    1958-10-01

    The design of control rods for nuclear reactors are described. In this design the control rod consists essentially of an elongated member constructed in part of a neutron absorbing material and having tube means extending therethrough for conducting a liquid to cool the rod when in use.

  1. Laser inertial fusion-based energy: Neutronic design aspects of a hybrid fusion-fission nuclear energy system

    NASA Astrophysics Data System (ADS)

    Kramer, Kevin James

    the same radial flibe flow that travels through perforated ODS walls to the reflector blanket. This reflector blanket is 75 cm thick comprised of 2 cm diameter graphite pebbles cooled by flibe. The flibe extraction plenum surrounds the reflector bed. Detailed neutronics designs studies are performed to arrive at the described design. The LFFH engine thermal power is controlled using a technique of adjusting the 6Li/7Li enrichment in the primary and secondary coolants. The enrichment adjusts system thermal power in the design by increasing tritium production while reducing fission. To perform the simulations and design of the LFFH engine, a new software program named LFFH Nuclear Control (LNC) was developed in C++ to extend the functionality of existing neutron transport and depletion software programs. Neutron transport calculations are performed with MCNP5. Depletion calculations are performed using Monteburns 2.0, which utilizes ORIGEN 2.0 and MCNP5 to perform a burnup calculation. LNC supports many design parameters and is capable of performing a full 3D system simulation from initial startup to full burnup. It is able to iteratively search for coolant 6Li enrichments and resulting material compositions that meet user defined performance criteria. LNC is utilized throughout this study for time dependent simulation of the LFFH engine. Two additional methods were developed to improve the computation efficiency of LNC calculations. These methods, termed adaptive time stepping and adaptive mesh refinement were incorporated into a separate stand alone C++ library name the Adaptive Burnup Library (ABL). The ABL allows for other client codes to call and utilize its functionality. Adaptive time stepping is useful for automatically maximizing the size of the depletion time step while maintaining a desired level of accuracy. Adaptive meshing allows for analysis of fixed fuel configurations that would normally require a computationally burdensome number of depletion zones

  2. Sagging Skin

    MedlinePlus

    ... Non-ablative Laser Rejuvenation Non-invasive Body Contouring Treatments Skin Cancer Skin Cancer Information Free Skin Cancer Screenings Skin ... Non-ablative Laser Rejuvenation Non-invasive Body Contouring Treatments Skin Cancer Skin Cancer Information Free Skin Cancer Screenings Skin ...

  3. Characterisation of an accelerator-based neutron source for BNCT versus beam energy

    NASA Astrophysics Data System (ADS)

    Agosteo, S.; Curzio, G.; d'Errico, F.; Nath, R.; Tinti, R.

    2002-01-01

    Neutron capture in 10B produces energetic alpha particles that have a high linear energy transfer in tissue. This results in higher cell killing and a higher relative biological effectiveness compared to photons. Using suitably designed boron compounds which preferentially localize in cancerous cells instead of healthy tissues, boron neutron capture therapy (BNCT) has the potential of providing a higher tumor cure rate within minimal toxicity to normal tissues. This clinical approach requires a thermal neutron source, generally a nuclear reactor, with a fluence rate sufficient to deliver tumorcidal doses within a reasonable treatment time (minutes). Thermal neutrons do not penetrate deeply in tissue, therefore BNCT is limited to lesions which are either superficial or otherwise accessible. In this work, we investigate the feasibility of an accelerator-based thermal neutron source for the BNCT of skin melanomas. The source was designed via MCNP Monte Carlo simulations of the thermalization of a fast neutron beam, generated by 7 MeV deuterons impinging on a thick target of beryllium. The neutron field was characterized at several deuteron energies (3.0-6.5 MeV) in an experimental structure installed at the Van De Graaff accelerator of the Laboratori Nazionali di Legnaro, in Italy. Thermal and epithermal neutron fluences were measured with activation techniques and fast neutron spectra were determined with superheated drop detectors (SDD). These neutron spectrometry and dosimetry studies indicated that the fast neutron dose is unacceptably high in the current design. Modifications to the current design to overcome this problem are presented.

  4. Skin Diseases: Skin Health and Skin Diseases

    MedlinePlus

    Skip Navigation Bar Home Current Issue Past Issues Skin Diseases Skin Health and Skin Diseases Past Issues / Fall 2008 Table of Contents ... acne to wrinkles Did you know that your skin is the largest organ of your body? It ...

  5. Nuclear Rocket Test Facility Decommissioning Including Controlled Explosive Demolition of a Neutron-Activated Shield Wall

    SciTech Connect

    Michael Kruzic

    2007-09-01

    Located in Area 25 of the Nevada Test Site, the Test Cell A Facility was used in the 1960s for the testing of nuclear rocket engines, as part of the Nuclear Rocket Development Program. The facility was decontaminated and decommissioned (D&D) in 2005 using the Streamlined Approach For Environmental Restoration (SAFER) process, under the Federal Facilities Agreement and Consent Order (FFACO). Utilities and process piping were verified void of contents, hazardous materials were removed, concrete with removable contamination decontaminated, large sections mechanically demolished, and the remaining five-foot, five-inch thick radiologically-activated reinforced concrete shield wall demolished using open-air controlled explosive demolition (CED). CED of the shield wall was closely monitored and resulted in no radiological exposure or atmospheric release.

  6. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  7. Nuclear Structure Relevant to Double-beta Decay: Studies of 76Ge and 76Se using Inelastic Neutron Scattering

    NASA Astrophysics Data System (ADS)

    Crider, Benjamin P.

    While neutrino oscillations indicate that neutrino flavors mix and that neutrinos have mass, they do not supply information on the absolute mass scale of the three flavors of neutrinos. Currently, the only viable way to determine this mass scale is through the observation of the theoretically predicted process of neutrinoless double-beta decay (0nubetabeta). This yet-to-be-observed decay process is speculated to occur in a handful of nuclei and has predicted half-lives greater than 1025 years. Observation of 0nubetabeta is the goal of several large-scale, multinational efforts and consists of detecting a sharp peak in the summed energies at the Q-value of the reaction. An exceptional candidate for the observation of 0nubetabeta is 76Ge, which offers an excellent combination of capabilities and sensitivities, and two such collaborations, MAJORANA and GERDA, propose tonne-scale experiments that have already begun initial phases using a fraction of the material. The absolute scale of the neutrino masses hinges on a matrix element, which depends on the ground-state wave functions for both the parent (76Ge) and daughter (76Se) nuclei in the 0nubetabeta decay and can only be calculated from nuclear structure models. Efforts to provide information on the applicability of these models have been undertaken at the University of Kentucky Accelerator Laboratory using gamma-ray spectroscopy following inelastic scattering reactions with monoenergetic, accelerator-produced fast neutrons. Information on new energy levels and transitions, spin and parity assignments, lifetimes, multipole mixing ratios, and transition probabilities have been determined for 76Se, the daughter of 76Ge 0nubetabeta, up to 3.0 MeV. Additionally, inaccuracies in the accepted level schemes have been addressed. Observation of 0nubetabeta requires precise knowledge of potential contributors to background within the region of interest, i.e., approximately 2039 keV for 76Ge. In addition to backgrounds

  8. Application of Neutron-Absorbing Structural-Amorphous Metal (SAM) Coatings for Spent Nuclear Fuel (SNF) Container to Enhance Criticality Safety Controls

    SciTech Connect

    Choi, J; Lee, C; Day, D; Wall, M; Saw, C; MoberlyChan, W; Farmer, J; Boussoufl, M; Liu, B; Egbert, H; Branagan, D; D'Amato, A

    2006-11-13

    Spent nuclear fuel contains fissionable materials ({sup 235}U, {sup 239}Pu, {sup 241}Pu, etc.). Neutron multiplication and the potential for criticality are enhanced by the presence of a moderator during cask loading in water, water incursion in accidents conditions during spent fuel storage or transport. To prevent nuclear criticality in spent fuel storage, transportation, and during disposal, neutron-absorbing materials (or neutron poisons, such as borated stainless steel, Boral{trademark}, Metamic{trademark}, Ni-Gd, and others) would have to be applied. The success in demonstrating that the High-Performance Corrosion-Resistant material (HPCRM) can be thermally applied as coating onto base metal to provide for corrosion resistance for many naval applications raises the interest in applying the HPCRM to USDOE/OCRWM spent fuel management program. The fact that the HPCRM relies on the high content of boron to make the material amorphous--an essential property for corrosion resistance--and that the boron has to be homogeneously distributed in the HPCRM qualify the material to be a neutron poison.

  9. Nuclear Rocket Facility Decommissioning Project: Controlled Explosive Demolition of Neutron Activated Shield Wall

    SciTech Connect

    Michael R. Kruzic

    2007-09-16

    Located in Area 25 of the Nevada Test Site (NTS), the Test Cell A (TCA) Facility was used in the early to mid-1960s for the testing of nuclear rocket engines, as part of the Nuclear Rocket Development Program, to further space travel. Nuclear rocket testing resulted in the activation of materials around the reactors and the release of fission products and fuel particles in the immediate area. Identified as Corrective Action Unit 115, the TCA facility was decontaminated and decommissioned (D&D) from December 2004 to July 2005 using the Streamlined Approach for Environmental Restoration (SAFER) process, under the ''Federal Facility Agreement and Consent Order''. The SAFER process allows environmental remediation and facility closure activities (i.e., decommissioning) to occur simultaneously provided technical decisions are made by an experienced decision maker within the site conceptual site model, identified in the Data Quality Objective process. Facility closure involved a seven-step decommissioning strategy. Key lessons learned from the project included: (1) Targeted preliminary investigation activities provided a more solid technical approach, reduced surprises and scope creep, and made the working environment safer for the D&D worker. (2) Early identification of risks and uncertainties provided opportunities for risk management and mitigation planning to address challenges and unanticipated conditions. (3) Team reviews provided an excellent mechanism to consider all aspects of the task, integrated safety into activity performance, increase team unity and ''buy-in'' and promoted innovative and time saving ideas. (4) Development of CED protocols ensured safety and control. (5) The same proven D&D strategy is now being employed on the larger ''sister'' facility, Test Cell C.

  10. A novel Al 2O 3 fluorescent nuclear track detector for heavy charged particles and neutrons

    NASA Astrophysics Data System (ADS)

    Akselrod, G. M.; Akselrod, M. S.; Benton, E. R.; Yasuda, N.

    2006-06-01

    A novel Al2O3 fluorescent nuclear track detector (FNTD), recently developed by Landauer, Inc., has demonstrated sensitivity and functionality superior to that of existing nuclear track detectors. The FNTD is based on single crystals of aluminum oxide doped with carbon and magnesium, and having aggregate oxygen vacancy defects (Al2O3:C,Mg). Radiation-induced color centers in the new material have an absorption band at 620 nm and produce fluorescence at 750 nm with a high quantum yield and a short, 75 ± 5 ns, fluorescence lifetime. Non-destructive readout of the detector is performed using a confocal fluorescence microscope. Scanning of the three-dimensional spatial distribution of fluorescence intensity along the track of a heavy charged particle (HCP) permits reconstruction of particle trajectories through the crystal and the LET can be determined as a function of distance along the trajectory based on the fluorescence intensity. Major advantages of Al2O3:C,Mg FNTD over conventionally processed CR-39 plastic nuclear track detector include superior spatial resolution, a wider range of LET sensitivity, no need for post-irradiation chemical processing of the detector and the capability to anneal and reuse the detector. Preliminary experiments have demonstrated that the material possesses a low-LET threshold of <1 keV/μm, does not saturate at LET in water as high as 1800 keV/μm, and is capable of irradiation to fluences in excess of 106 cm-2 without saturation (track overlap).

  11. Supercritical Water Nuclear Steam Supply System: Innovations In Materials, Neutronics & Thermal-Hydraulics

    SciTech Connect

    Mark Anderson; M.L. Corradini; K. Sridharan; P. WIlson; D. Cho; T.K. Kim; S. Lomperski

    2004-09-02

    In the 1990's supercritical light-water reactors were considered in conceptual designs. A nuclear reactor cooled by supercritical waster would have a much higher thermal efficiency with a once-through direct power cycle, and could be based on standardized water reactor components (light water or heavy water). The theoretical efficiency could be improved by more than 33% over that of other water reactors and could be simplified with higher reliability; e.g., a boiling water reactor without steam separators or dryers.

  12. Building relativistic mean field models for finite nuclei and neutron stars

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Chia; Piekarewicz, J.

    2014-10-01

    Background: Theoretical approaches based on density functional theory provide the only tractable method to incorporate the wide range of densities and isospin asymmetries required to describe finite nuclei, infinite nuclear matter, and neutron stars. Purpose: A relativistic energy density functional (EDF) is developed to address the complexity of such diverse nuclear systems. Moreover, a statistical perspective is adopted to describe the information content of various physical observables. Methods: We implement the model optimization by minimizing a suitably constructed χ2 objective function using various properties of finite nuclei and neutron stars. The minimization is then supplemented by a covariance analysis that includes both uncertainty estimates and correlation coefficients. Results: A new model, "FSUGold2," is created that can well reproduce the ground-state properties of finite nuclei, their monopole response, and that accounts for the maximum neutron-star mass observed up to date. In particular, the model predicts both a stiff symmetry energy and a soft equation of state for symmetric nuclear matter, suggesting a fairly large neutron-skin thickness in Pb208 and a moderate value of the nuclear incompressibility. Conclusions: We conclude that without any meaningful constraint on the isovector sector, relativistic EDFs will continue to predict significantly large neutron skins. However, the calibration scheme adopted here is flexible enough to create models with different assumptions on various observables. Such a scheme—properly supplemented by a covariance analysis—provides a powerful tool to identify the critical measurements required to place meaningful constraints on theoretical models.

  13. Nuclear level densities in {sup 47}V, {sup 48}V, {sup 49}V, {sup 53}Mn, and {sup 54}Mn from neutron evaporation spectra

    SciTech Connect

    Zhuravlev, B. V. Lychagin, A. A.; Titarenko, N. N.; Demenkov, V. G.; Trykova, V. I.

    2011-03-15

    The spectra of neutrons from the (p, n) reactions on {sup 47}Ti, {sup 48}Ti, {sup 49}Ti, {sup 53}Cr, and {sup 54}Cr nuclei were measured in the proton-energy range 7-11 MeV. The measurements were performed with the aid of a fast-neutron spectrometer by the time-of-flight method over the base of the EGP-15 tandem accelerator of the Institute for Physics and Power Engineering (IPPE, Obninsk). Owing to a high resolution and a high stability of the time-of-flight spectrometer used, low-lying discrete levels could be identified reliably along with a continuum section of neutron spectra. An analysis of measured data was performed within the statistical equilibrium and preequilibrium models of nuclear reactions. The relevant calculations were performed by using the exact formalism of Hauser-Feshbach statistical theory supplemented with the generalized model of a superfluid nucleus, the back-shifted Fermi gas model, and the Gilbert-Cameron composite formula for the nuclear level density. The nuclear level densities for {sup 47}V, {sup 48}V, {sup 49}V, {sup 53}Mn, and {sup 54}Mn were determined along with their energy dependences and model parameters. The results are discussed together with available experimental data and recommendations of model systematics.

  14. Intense fusion neutron sources

    NASA Astrophysics Data System (ADS)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-01

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

  15. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    NASA Astrophysics Data System (ADS)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-01

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from 235U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 × 10-5. The upper limit for the asymmetry coefficient has been set to | D n | < 6 × 10-5 at 99% confidence level, whereas for ternary fission correlation coefficient D α = (170±20) × 10-5. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5° to the fission axis, the correlation coefficient was found to be (1.57 ± 0.20) × 10-4, while at the angle of 67.5° it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt γ-rays.

  16. The effect of high fluence neutron irradiation on the properties of a fine-grained isotropic nuclear graphite

    NASA Astrophysics Data System (ADS)

    Ishiyama, S.; Burchell, T. D.; Strizak, J. P.; Eto, M.

    1996-05-01

    A fine-grained isotropic nuclear graphite (IG-110), manufactured from a petroleum coke, was irradiated to a total neutron dose of 3.8 × 10 26 n/m 2 or 25 displacements per atom (dpa) at 600°C in the high flux isotope reactor (HFIR) at Oak Ridge: National Laboratory (ORNL). The effect of irradiation and the influence of post-irradiation thermal annealing on the properties of the graphite were evaluated. Volume change turnaround was clearly observed at 15—20 dpa and the return to original volume ( {ΔV}/{V 0} = 0 ) can be estimated to occur at ˜ 30 dpa. Strength and elastic moduli of the irradiated graphite increased by a factor of 2-3, and maximums in the {δ}/{δ 0}, and {E}/{E o} curves were at ˜20 dpa at 600°C. Recovery of volume, fracture strength and thermal conductivity by thermal annealing were found., and thermal conductivity returned to better than about 30% of the unirradiated value after 1200°C thermal annealing.

  17. Format requirements of thermal neutron scattering data in a nuclear data format to succeed the ENDF format

    SciTech Connect

    Brown, D.

    2014-03-31

    In November 2012, the Working Party on Evaluation Cooperation Subgroup 38 (WPEC-SG38) began with the task of developing a nuclear data format and supporting infrastructure to replace the now nearly 50 year old ENDF format. The first step in this process is to develop requirements for the new format and infrastructure. In this talk, I will review the status of ENDF's Thermal Scattering Law (TSL) formats as well as support for this data in the GND format (from which the new format is expected to evolve). Finally, I hope to begin a dialog with members of the thermal neutron scattering community so that their data needs can be accurately and easily accommodated by the new format and tools, as captured by the requirements document. During this discussion, we must keep in mind that the new tools and format must; Support what is in existing data files; Support new things we want to put in data files; and Be flexible enough for us to adapt it to future unanticipated challenges.

  18. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.

    1958-04-22

    A nuclear reactor for isotope production is described. This reactor is designed to provide a maximum thermal neutron flux in a region adjacent to the periphery of the reactor rather than in the center of the reactor. The core of the reactor is generally centrally located with respect tn a surrounding first reflector, constructed of beryllium. The beryllium reflector is surrounded by a second reflector, constructed of graphite, which, in tune, is surrounded by a conventional thermal shield. Water is circulated through the core and the reflector and functions both as a moderator and a coolant. In order to produce a greatsr maximum thermal neutron flux adjacent to the periphery of the reactor rather than in the core, the reactor is designed so tbat the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the materials in the reflector is approximately twice the ratio of neutron scattering cross section to neutron absorption cross section averaged over all of the material of the core of the reactor.

  19. Nuclear-decay studies of neutron-rich rare-earth nuclides

    SciTech Connect

    Chasteler, R.M. . Dept. of Chemistry Lawrence Berkeley Lab., CA )

    1990-04-26

    Neutron-rich rare-earth nuclei were produced in multinucleon transfer reactions of {sup 170}Er and {sup 176}Yb projectiles on {sup nat}W targets at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decays properties studied at the on-line mass separation facility OASIS. Two unknown isotopes, {sup 169}Dy (t {sub 1/2} {equals} 39 {plus minus} 8 s) and {sup 174}Er(t{sub 1/2} {equals} 3.3 {plus minus} 0.2 m) were discovered and their decay characteristics determined. The decay schemes for two previously identified isotopes, {sup 168}Dy (t{sub 1/2} {equals} 8.8 {plus minus} 0.3 m) and {sup 171}Ho (t{sub 1/2} {equals} 55 {plus minus} 3 s), were characterized. Evidence for a new isomer of 3.0 m {sup 168}Ho{sup g}, {sup 168}Ho{sup m} (t{sub 1/2} {equals} 132 {plus minus} 4 s) which decays by isomeric transition (IT) is presented. Beta particle endpoint energies were determined for the decay of {sup 168}Ho{sup g}, {sup 169}Dy, {sup 171}Ho, and {sup 174}Er, the resulting Q{beta}-values are: 2.93 {plus minus} 0.03, 3.2 {plus minus} 0.3, 3.2 {plus minus} 0.6, and 1.8 {plus minus} 0.2 MeV, respectively. These values were compared with values calculated using recent atomic mass formulae. Comparisons of various target/ion source geometries used in the OASIS mass separator facility for these multinucleon transfer reactions were performed. 73 refs., 40 figs., 11 tabs.

  20. Direct Measurement of Neutron-Neutron Scattering

    SciTech Connect

    Sharapov, E.I.; Furman, W.I.; Lychagin, W.I.; Muzichka, G.V.; Nekhaev, G.V.; Safronov, Yu.V.; Shvetsov, V.N.; Strelkov, A.V.; Bowman, C.D.; Crawford, B.E.; Stephenson, S.L.; Howell, C.R.; Tornow, W.; Levakov, B.G.; Litvin, V.I.; Lyzhin, A.E.; Magda, E.P.; Mitchell, G.E.

    2003-08-26

    In order to resolve long-standing discrepancies in indirect measurements of the neutron-neutron scattering length ann and contribute to solving the problem of the charge symmetry of the nuclear force, the collaboration DIANNA (Direct Investigation of ann Association) plans to measure the neutron-neutron scattering cross section {sigma}nn. The key issue of our approach is the use of the through-channel in the Russia reactor YAGUAR with a peak neutron flux of 10{sup 18} /cm2/s. The proposed experimental setup is described. Results of calculations are presented to connect {sigma}nn with the nn-collision detector count rate and the neutron flux density in the reactor channel. Measurements of the thermal neutron fields inside polyethylene converters show excellent prospects for the realization of the direct nn-experiment.

  1. NEUTRONIC REACTOR

    DOEpatents

    Wigner, E.P.; Weinberg, A.W.; Young, G.J.

    1958-04-15

    A nuclear reactor which uses uranium in the form of elongated tubes as fuel elements and liquid as a coolant is described. Elongated tubular uranium bodies are vertically disposed in an efficient neutron slowing agent, such as graphite, for example, to form a lattice structure which is disposed between upper and lower coolant tanks. Fluid coolant tubes extend through the uranium bodies and communicate with the upper and lower tanks and serve to convey the coolant through the uranium body. The reactor is also provided with means for circulating the cooling fluid through the coolant tanks and coolant tubes, suitable neutron and gnmma ray shields, and control means.

  2. FOREWORD: Neutron metrology Neutron metrology

    NASA Astrophysics Data System (ADS)

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  3. Antioxidative effects of the spice cardamom against non-melanoma skin cancer by modulating nuclear factor erythroid-2-related factor 2 and NF-κB signalling pathways.

    PubMed

    Das, Ila; Acharya, Asha; Berry, Deborah L; Sen, Supti; Williams, Elizabeth; Permaul, Eva; Sengupta, Archana; Bhattacharya, Sudin; Saha, Tapas

    2012-09-28

    The role of dietary factors in inhibiting or delaying the development of non-melanoma skin cancer (NMSC) has been investigated for many years. Cardamom, which is a dietary phytoproduct, has been commonly used in cuisines for flavour and has numerous health benefits, such as improving digestion and stimulating metabolism and having antitumorigenic effects. We have investigated the efficacy of dietary cardamom against 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin papillomatogenesis in Swiss albino mice that closely resembles human NMSC. Mice were grouped into normal wild type (untreated), vehicle-treated (acetone), carcinogen-treated (DMBA), and DMBA and cardamom-treated (DMBA+CARD) to delineate the role of cardamom against DMBA-induced papillomatogenesis. Oral administration of cardamom to DMBA-treated mice up-regulated the phase II detoxification enzymes, such as glutathione-S-transferase and glutathione peroxidase, probably via activation of nuclear factor erythroid-2-related factor 2 transcription factor in 'DMBA+CARD' mice. Furthermore, reduced glutathione, glutathione reductase, superoxide dismutase and catalase were also up-regulated by cardamom in the same 'DMBA+CARD' group of mice compared with DMBA-treated mice. Cardamom ingestion in DMBA-treated mice blocked NF-κB activation and down-regulated cyclo-oxygenase-2 expression. As a consequence, both the size and the number of skin papillomas generated on the skin due to the DMBA treatment were reduced in the 'DMBA+CARD' group. Thus, the results from the present study suggest that cardamom has a potential to become a pivotal chemopreventive agent to prevent papillomagenesis on the skin. PMID:22182368

  4. Antioxidative effects of the spice cardamom against non-melanoma skin cancer by modulating nuclear factor erythroid-2-related factor 2 and NF-κB signalling pathways.

    PubMed

    Das, Ila; Acharya, Asha; Berry, Deborah L; Sen, Supti; Williams, Elizabeth; Permaul, Eva; Sengupta, Archana; Bhattacharya, Sudin; Saha, Tapas

    2012-09-28

    The role of dietary factors in inhibiting or delaying the development of non-melanoma skin cancer (NMSC) has been investigated for many years. Cardamom, which is a dietary phytoproduct, has been commonly used in cuisines for flavour and has numerous health benefits, such as improving digestion and stimulating metabolism and having antitumorigenic effects. We have investigated the efficacy of dietary cardamom against 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin papillomatogenesis in Swiss albino mice that closely resembles human NMSC. Mice were grouped into normal wild type (untreated), vehicle-treated (acetone), carcinogen-treated (DMBA), and DMBA and cardamom-treated (DMBA+CARD) to delineate the role of cardamom against DMBA-induced papillomatogenesis. Oral administration of cardamom to DMBA-treated mice up-regulated the phase II detoxification enzymes, such as glutathione-S-transferase and glutathione peroxidase, probably via activation of nuclear factor erythroid-2-related factor 2 transcription factor in 'DMBA+CARD' mice. Furthermore, reduced glutathione, glutathione reductase, superoxide dismutase and catalase were also up-regulated by cardamom in the same 'DMBA+CARD' group of mice compared with DMBA-treated mice. Cardamom ingestion in DMBA-treated mice blocked NF-κB activation and down-regulated cyclo-oxygenase-2 expression. As a consequence, both the size and the number of skin papillomas generated on the skin due to the DMBA treatment were reduced in the 'DMBA+CARD' group. Thus, the results from the present study suggest that cardamom has a potential to become a pivotal chemopreventive agent to prevent papillomagenesis on the skin.

  5. Isotope-Identifying neutron reflectometry

    SciTech Connect

    Nikitenko, Yu. V. Petrenko, A. V.; Gundorin, N. A.; Gledenov, Yu. M.; Aksenov, V. L.

    2015-07-15

    The possibilities of an isotope-indentifying study of layered structures in different regimes of a neutron wave field are considered. The detection of specularly reflected neutrons and secondary radiation (caused by neutron capture) in the form of charged particles, γ quanta, and nuclear fission fragments, as well as neutrons spin-flipped in a noncollinear magnetic field and on nuclei of elements with spin, makes it possible to implement isotope-indentifying neutron reflectometry.

  6. Advanced Sample Environments for in situ Neutron Diffraction Studies of Nuclear Materials

    SciTech Connect

    Reiche, Helmut M.

    2012-07-19

    Summaries of this presentation are: (1) the author successfully developed and commissioned three sample environments and applied them to study scientific problems of nuclear materials; (2) sample changer - reliable, unattended operation, Reiche and Vogel, 2010; (3) creep furnace - 1000 C, 2.7 kN, texture, Reiche et al., 2012; (4) Zr-2.5Nb pressure tubes - deconvolute the contributions of heating, phase transformation, deformation at temperature in the {beta}-field, and phase transformation during cooling; (5) our data informs currently developed mechanical models predicting texture evolution during phase transformation and high temperature deformation (MST-8, LANL); (6) high-temperature furnace - >2200 C, texture, paper in progress; (7) UC - Bowman's NaCl-type structure correct for cubic UC{sub 2}, recent reactor safetly calculations by Chevalier and Fischer (2001) and independent work by Freyss (2010) incorrect, as fluorite structure is assumed; and (8) UC - order-disorder transition starting at 1800 C discovered which will improve current models, as these do not predict this transition (e.g. Basak, 2007), or confirm the prediction (Wen et al., 2012, T-1, LANL).

  7. Nuclear Structure Investigations of Neutron Deficient Nuclei in the Region Z = 103 to 105

    SciTech Connect

    Heberger, F.P.; Hofmann, S.; Ackermann, D.; Armbruster, P.; Munzenberg, G.; Stodel, Ch.; Lavrentev, A.Yu.; Popeko, A.G.; Yeremin, A.V.; Saro, S.; Leino, M.

    1999-12-31

    The isotopes {sup 257,255}Rf, {sup 257,256}Db, {sup 253,252}Lr have been produced in bombardments of {sup 207,208}Pb and {sup 209}Bi target nuclei with {sup 50}Ti and identified by their {alpha}-decay. New or improved decay data could be obtained. Analysis of the fine structure of the {alpha}-decay pattern of {sup 257}Rf allowed the construction of a first tentative level scheme for the daughter nucleus {sup 253}No and also the identification of a low lying high spin isomeric state, while from {alpha}-{gamma} coincidence measurements for {sup 255}Rf a first tentative level scheme of the daughter nucleus {sup 251}No was derived. For {sup 257}Db we found that two nuclear levels decay by {alpha}-emission and populate also different levels in the daughter nucleus {sup 253}Lr. The levels are produced by the reaction process. In bombardments of {sup 209}Bi with {sup 50}Ti at E*{sub cn} = 26.4 MeV and 30.8 MeV the previously unknown isotopes {sup 256}Db and {sup 22}Lr were identified.

  8. Nuclear structure investigations of neutron deficient nuclei in the region Z=103 to 105

    SciTech Connect

    Hessberger, F. P.; Hofmann, S.; Armbruster, P.; Muenzenberg, G.; Stodel, Ch.; Ackermann, D.; Lavrentev, A. Yu.; Popeko, A. G.; Yeremin, A. V.; Saro, S.; Leino, M.

    1999-11-16

    The isotopes {sup 257,255}Rf, {sup 257,256}Db, {sup 253,252}Lr have been produced in bombardments of {sup 207,208}Pb and {sup 209}Bi target nuclei with {sup 50}Ti and identified by their {alpha}-decay. New or improved decay data could be obtained. Analysis of the fine structure of the {alpha}-decay pattern of {sup 257}Rf allowed the construction of a first tentative level scheme for the daughter nucleus {sup 253}No and also the identification of a low lying high spin isomeric state, while from {alpha}-{gamma}- coincidence measurements for {sup 255}Rf a first tentative level scheme of the daughter nucleus {sup 251}No was derived. For {sup 257}Db we found that two nuclear levels decay by {alpha}-emission and populate also different levels in the daughter nucleus {sup 253}Lr. The levels are produced by the reaction process. In bombardments of {sup 209}Bi with {sup 50}Ti at E{sub CN}*=26.4 MeV and 30.8 MeV the previously unknown isotopes {sup 256}Db and {sup 252}Lr were identified.

  9. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    SciTech Connect

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-15

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from {sup 235}U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 Multiplication-Sign 10{sup -5}. The upper limit for the asymmetry coefficient has been set to vertical bar D{sub n} vertical bar < 6 Multiplication-Sign 10{sup -5} at 99% confidence level, whereas for ternary fission correlation coefficient D{sub {alpha}} = (170{+-}20) Multiplication-Sign 10{sup -5}. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5 Degree-Sign to the fission axis, the correlation coefficient was found to be (1.57 {+-} 0.20) Multiplication-Sign 10{sup -4}, while at the angle of 67.5 Degree-Sign it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt {gamma}-rays.

  10. Neutron scatter camera

    DOEpatents

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  11. A new view of nuclear shells

    NASA Astrophysics Data System (ADS)

    Kanungo, Rituparna

    2013-01-01

    The nuclear shell structure that has served as a fundamental framework for understanding the arrangement of nucleons exhibits dramatic changes as the neutron to proton ratio in nuclei increases. This paper describes how reaction spectroscopy of the neutron- and proton-rich nuclei has brought about a new revolution towards a more global view of nuclear shells. The relationship between changes in shell structure and the discovery of exotic forms of nuclei such as nuclear halo and skin is discussed. It is shown that the well-known shell gaps (magic numbers) N = 8 and 20 disappear. The discovery of a new magic number at N = 16 at the limit of nuclear binding is discussed.

  12. Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into human skin affected by atopic dermatitis

    NASA Astrophysics Data System (ADS)

    Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Borbíró, I.; Angyal, A.; Csedreki, L.; Furu, E.; Szoboszlai, Z.; Kiss, Á. Z.; Hunyadi, J.

    2011-10-01

    Skin penetration is one of the potential routes for nanoparticles to gain access into the human body. Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the particle size smaller than 200 nm makes the product more transparent compared to formulations containing coarser particles. The present study continues the work carried out in the frame of the NANODERM: “Quality of skin as a barrier to ultrafine particles” European project and complements our previous investigations on human skin with compromised barrier function. Atopic dermatitis (a type of eczema) is an inflammatory, chronically relapsing, non-contagious skin disease. It is very common in children but may occur at any age. The exact cause of atopic dermatitis is unknown, but is likely due to a combination of impaired barrier function together with a malfunction in the body's immune system. In this study, skin samples were obtained from two patients suffering from atopic dermatitis. Our results indicate that the ultrafine zinc oxide particles, in a hydrophobic basis gel with an application time of 2 days or 2 weeks, have penetrated deeply into the stratum corneum in these patients. On the other hand, penetration into the stratum spinosum was not observed even in the case of the longer application time.

  13. NEUTRALIZATIONS OF HIGH ALUMINUM LOW URANIUM USED NUCLEAR FUEL SOLUTIONS CONTAINING GADOLINIUM AS A NEUTRON POISON

    SciTech Connect

    Taylor-Pashow, K.

    2011-06-08

    H-Canyon will begin dissolving High Aluminum - Low Uranium (High Al/Low U) Used Nuclear Fuel (UNF) following approval by DOE which is anticipated in CY2011. High Al/Low U is an aluminum/enriched uranium UNF with small quantities of uranium relative to aluminum. The maximum enrichment level expected is 93% {sup 235}U. The High Al/Low U UNF will be dissolved in H-Canyon in a nitric acid/mercury/gadolinium solution. The resulting solution will be neutralized and transferred to Tank 39H in the Tank Farm. To confirm that the solution generated could be poisoned with Gd, neutralized, and discarded to the Savannah River Site (SRS) high level waste (HLW) system without undue nuclear safety concerns the caustic precipitation of simulant solutions was examined. Experiments were performed with three simulant solutions representative of the H-Canyon estimated concentrations in the final solutions after dissolution. The maximum U, Gd, and Al concentration were selected for testing from the range of solution compositions provided. Simulants were prepared in three different nitric acid concentrations, ranging from 0.5 to 1.5 M. The simulant solutions were neutralized to four different endpoints: (1) just before a solid phase was formed (pH 3.5-4), (2) the point where a solid phase was obtained, (3) 0.8 M free hydroxide, and (4) 1.2 M free hydroxide, using 50 wt % sodium hydroxide (NaOH). The settling behavior of the neutralized solutions was found to be slower compared to previous studies, with settling continuing over a one week period. Due to the high concentration of Al in these solutions, precipitation of solids was observed immediately upon addition of NaOH. Precipitation continued as additional NaOH was added, reaching a point where the mixture becomes almost completely solid due to the large amount of precipitate. As additional NaOH was added, some of the precipitate began to redissolve, and the solutions neutralized to the final two endpoints mixed easily and had expected

  14. Neutronic Reactor Design to Reduce Neutron Loss

    DOEpatents

    Miles, F. T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall. The wall is surrounded by successive layers of pure fertile material and moderator containing fertile material. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. Since the steel has a smaller capture cross section for the fast neutrons, greater nunnbers of neutrons will pass into the blanket, thereby increasing the over-all efficiency of the reactor. (AEC)

  15. NEUTRONIC REACTOR DESIGN TO REDUCE NEUTRON LOSS

    DOEpatents

    Mills, F.T.

    1961-05-01

    A nuclear reactor construction is described in which an unmoderated layer of the fissionable material is inserted between the moderated portion of the reactor core and the core container steel wall which is surrounded by successive layers of pure fertile material and fertile material having moderator. The unmoderated layer of the fissionable material will insure that a greater portion of fast neutrons will pass through the steel wall than would thermal neutrons. As the steel has a smaller capture cross-section for the fast neutrons, then greater numbers of the neutrons will pass into the blanket thereby increasing the over-all efficiency of the reactor.

  16. Characterization of the neutron source term and multiplicity of a spent fuel assembly in support of NSDA safeguards of spent nuclear fuel

    SciTech Connect

    Richard, Joshua G; Fensin, Michael L; Tobin, Stephen J; Swinhoe, Martyn T; Menlove, Howard O; Baciak, James

    2010-01-01

    The gross neutron signal (GNS) is being considered as part of a fingerprinting or neutron balance approach to safeguards of spent nuclear fuel (SNF). Because the GNS is composed of many derivative components, understanding the time-dependent contribution of these derivative components is crucial to gauging the limitations of these approaches. The major components of the GNS are ({alpha}, n), spontaneous fission (SF), and multiplication neutrons. A methodology was developed to link MCNPX burnup output files to SOURCES4C input files for the purpose of automatically generating both the ({alpha}, n) and SF signals. Additional linking capabilities were developed to write MCNPX multiplication input files using the data obtained from the SOURCES4C output files. In this paper, the following are presented: (1) the relative contributions by source nuclide to the ({alpha}, n) signal as a function of initial enrichment/burnup/cooling time; (2) the relative contributions by source nuclide to the SF signal as a function of initial enrichment/burnup/cooling time; (3) the relative contributions by reaction type ({alpha},n vs. SF) to the GNS; and (4) the multiplication of the GNS as a function of initial enrichment/burnup/cooling time/counting environment. By developing these technologies to characterize the GNS, we can better evaluate the viability of the GNS fingerprint and neutron balance concepts for SNF.

  17. Neutron-emission measurements at a white neutron source

    SciTech Connect

    Haight, Robert C

    2010-01-01

    Data on the spectrum of neutrons emittcd from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ''white'' neutron source (continuous in energy) allows measurements over a wide range of neutron energies all in one experiment. We use the tast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of the fission neutron spectra from {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

  18. A Code for the Generation of Group Constants for Reactor Calculations from Neutron Nuclear Data in KEDAK Format.

    1988-09-15

    Version 00 Group averaged neutron cross sections, energy resonance self shielding factors, elastic transfer elements up to P5 approximation, the inelastic, (n,2n) and (n,3n) transfer elements, fission spectra, etc., for coarse groups (26 groups in the standard case) in the fast neutron energy range are calculated.

  19. Mapping of the thermal neutron distribution in the lead block assembly of the PS-211 experiment at CERN, using thermoluminescence and nuclear track detectors.

    PubMed

    Savvidis, E; Eleftheriadis, C A; Kitis, G

    2002-01-01

    The main purpose of the TARC (Transmutation by Adiabatic Resonance Crossing) experiment (PS-211), was to demonstrate the possibility to destroy efficiently Long-Lived Fission Fragments (LLFF) in Accelerator Driven Systems (ADS). The experimental set-up which consisted of a lead block with dimensions 3.3 x 3.3 x 3 m3, was installed in a CERN Proton Synchrotron (PS) beam line. The proton beam at 2.5 GeV/c and 3.5 GeV/c, was incident in the centre of the lead block assembly producing neutrons via spallation reactions. In this study, neutron flux measurements are presented in the lead block assembly using thermoluminescence and nuclear track detectors. The results are in good agreement with Monte Carlo calculations as well as with the results of the other methods used in the framework of the TARC experiment.

  20. Neutron scattering studies of nuclear and magnetic structures of YBa 2(Cu 1-yZn y) 3O 6+x

    NASA Astrophysics Data System (ADS)

    Villenueve, R.; Mirebeau, I.; Collin, G.; Bourée, F.

    1994-12-01

    Elastic neutron diffraction experiments were performed on YBa 2(Cu 1-yZn y) 3O 6+x powders, Nuclear structures have been refined using the Rietveld method on powders of compositions x=1 and y ranging from 0.01 to 0.06. The results suggest a solubility limit of zinc in the coper planes at y≈0.04 and zinc may start to substitute for chain coper sites for higher y values. Magnetic structure of a y=0.02 and x=0.05 powder has been studied by neutron elastic diffraction. The antiferromagnetic structure is not affected by non-magnetic zinc atoms but the ordering temperature is strongly reduced.

  1. Nuclear structure beyond the neutron drip line: The lowest energy states in 9He via their T = 5/2 isobaric analogs in 9Li

    NASA Astrophysics Data System (ADS)

    Uberseder, E.; Rogachev, G. V.; Goldberg, V. Z.; Koshchiy, E.; Roeder, B. T.; Alcorta, M.; Chubarian, G.; Davids, B.; Fu, C.; Hooker, J.; Jayatissa, H.; Melconian, D.; Tribble, R. E.

    2016-03-01

    The level structure of the very neutron rich and unbound 9He nucleus has been the subject of significant experimental and theoretical study. Many recent works have claimed that the two lowest energy 9He states exist with spins Jπ = 1 /2+ and Jπ = 1 /2- and widths on the order of 100-200 keV. These findings cannot be reconciled with our contemporary understanding of nuclear structure. The present work is the first high-resolution study with low statistical uncertainty of the relevant excitation energy range in the 8He+n system, performed via a search for the T = 5 / 2 isobaric analog states in 9Li populated through 8He+p elastic scattering. The present data show no indication of any narrow structures. Instead, we find evidence for a broad Jπ = 1 /2+ state in 9He located approximately 3 MeV above the neutron decay threshold.

  2. Nuclear level densities of 64,66 Zn from neutron evaporation

    SciTech Connect

    Ramirez, A. P. D.; Voinov, A. V.; Grimes, S. M.; Schiller, A.; Brune, C. R.; Massey, T. N.; Salas-Bacci, A.

    2013-12-26

    Double differential cross sections of neutrons from d+63,65Cu reactions have been measured at deuteron energies of 6 and 7.5 MeV. The cross sections measured at backward angles have been compared to theoretical calculations in the framework of the statistical Hauser-Feshbach model. Three different level density models were tested: the Fermi-gas model, the Gilbert-Cameron model, and the microscopic approach through the Hartree-Fock-Bogoliubov method (HFBM). The calculations using the Gilbert-Cameron model are in best agreement with our experimental data. Level densities of the residual nuclei 64Zn and 66Zn have been obtained from statistical neutron evaporation spectra. In conclusion, the angle-integrated cross sections have been analyzed with the exciton model of nuclear reaction.

  3. Characterisation of neutron fields at Cernavoda NPP.

    PubMed

    Cauwels, Vanessa; Vanhavere, Filip; Dumitrescu, Dorin; Chirosca, Alecsandru; Hager, Luke; Million, Marc; Bartz, James

    2013-04-01

    Near a nuclear reactor or a fuel container, mixed neutron/gamma fields are very common, necessitating routine neutron dosimetry. Accurate neutron dosimetry is complicated by the fact that the neutron effective dose is strongly dependent on the neutron energy and the direction distribution of the neutron fluence. Neutron field characterisation is indispensable if one wants to obtain a reliable estimate for the neutron dose. A measurement campaign at CANDU nuclear power plant located in Cernavoda, Romania, was set up to characterise the neutron fields in four different locations and to investigate the behaviour of different neutron personal dosemeters. This investigation intends to assist in choosing a suitable neutron dosimetry system at this nuclear power plant.

  4. Nuclear structure from radioactive decay. Annual progress report

    SciTech Connect

    Wood, J.L.

    1991-09-30

    This report discusses nuclear structure from radioactive decay of the following: Neutron-Deficient Iridium Isotopes; Neutron-Deficient Platinum Isotopes; Neutron-Deficient Gold Isotopes; Neutron-Deficient Mercury Isotopes; Neutron-Deficient Thallium Isotopes; Neutron-Deficient Lead Isotopes; Neutron-Deficient Samarium Isotopes; Neutron-Deficient Promethium Isotopes; Neutron-Deficient Neodymium Isotopes; and Neutron-Deficient Praseodymium Isotopes. Also discussed are Nuclear Systematics and Models.

  5. Theoretical and Experimental Research in Neutron Spectra and Nuclear Waste Transmutation on Fast Subcritical Assembly with MOX Fuel

    NASA Astrophysics Data System (ADS)

    Arkhipkin, D. A.; Buttsev, V. S.; Chigrinov, S. E.; Kutuev, R. Kh.; Polanski, A.; Rakhno, I. L.; Sissakian, A.; Zulkarneev, R. Ya.; Zulkarneeva, Yu. R.

    2003-07-01

    The paper deals with theoretical and experimental investigation of transmutation rates for a number of long-lived fission products and minor actinides, as well as with neutron spectra formed in a subcritical assembly driven with the following monodirectional beams: 660-MeV protons and 14-MeV neutrons. In this work, the main objective is the comparison of neutron spectra in the MOX assembly for different external driving sources: a 660-MeV proton accelerator and a 14-MeV neutron generator. The SAD project (JINR, Russia) has being discussed. In the context of this project, a subcritical assembly consisting of a cylindrical lead target surrounded by a cylindrical MOX fuel layer will be constructed. Present conceptual design of the subcritical assembly is based on the core with a nominal unit capacity of 15 kW (thermal). This corresponds to a multiplication coefficient, keff= 0.945, and an accelerator beam power of 0.5 kW. The results of theoretical investigations on the possibility of incinerating long-lived fission products and minor actinides in fast neutron spectrum and formation of neutron spectra with different hardness in subcritical systems based on the MOX subcritical assembly are discussed. Calculated neutron spectra emitted from a lead target irradiated by a 660-MeV protons are also presented.

  6. Nuclear-level densities in the 49V and 57Co nuclei on the basis of evaporated-neutron spectra in ( p, n) and ( d, n) reactions

    NASA Astrophysics Data System (ADS)

    Zhuravlev, B. V.; Titarenko, N. N.

    2016-03-01

    The spectra of neutrons from the reactions 49Ti( p, n)49V and 57Fe ( p, n)57Co were measured in the range of proton energies between 8 and 11 MeV along with their counterparts from the reactions 48Ti( d, n)49V and 56Fe ( d, n)57Co at the deuteron energies of 2.7 and 3.8 MeV. These measurements were conducted with the aid of a time-of-flight fast-neutron spectrometer on the basis of the EGP-15 pulsed tandem accelerator of the Institute for Physics and Power Engineering (IPPE, Obninsk). An analysis of measured data was performed within the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations based on the Hauser-Feshbach formalism of statistical theory were carried out with nuclear-level densities given by the generalized superfluid model of the nucleus, the backshifted Fermi-gas model, and the Gilbert-Cameron composite formula. The nuclear-level densities of 49V and 57Co and their energy dependences were determined. The results were discussed together with available experimental data and data recommended by model systematics.

  7. Perforated diode neutron sensors

    NASA Astrophysics Data System (ADS)

    McNeil, Walter J.

    A novel design of neutron sensor was investigated and developed. The perforated, or micro-structured, diode neutron sensor is a concept that has the potential to enhance neutron sensitivity of a common solid-state sensor configuration. The common thin-film coated diode neutron sensor is the only semiconductor-based neutron sensor that has proven feasible for commercial use. However, the thin-film coating restricts neutron counting efficiency and severely limits the usefulness of the sensor. This research has shown that the perforated design, when properly implemented, can increase the neutron counting efficiency by greater than a factor of 4. Methods developed in this work enable detectors to be fabricated to meet needs such as miniaturization, portability, ruggedness, and adaptability. The new detectors may be used for unique applications such as neutron imaging or the search for special nuclear materials. The research and developments described in the work include the successful fabrication of variant perforated diode neutron detector designs, general explanations of fundamental radiation detector design (with added focus on neutron detection and compactness), as well as descriptive theory and sensor design modeling useful in predicting performance of these unique solid-state radiation sensors. Several aspects in design, fabrication, and operational performance have been considered and tested including neutron counting efficiency, gamma-ray response, perforation shapes and depths, and silicon processing variations. Finally, the successfully proven technology was applied to a 1-dimensional neutron sensor array system.

  8. NEUTRONIC REACTOR CONTROL

    DOEpatents

    Untermyer, S.; Hutter, E.

    1959-08-01

    This patent relates to "shadow" control of a nuclear reactor. The control means comprises a plurality ot elongated rods disposed adjacent and parallel to each other, The morphology and effects of gases generated within sections of neutron absorbing materials and equal length sections of neutron permeable materials together with means for longitudinally pcsitioning the rcds relative to each other.

  9. Measuring the Noble Metal and Iodine Composition of Extracted Noble Metal Phase from Spent Nuclear Fuel Using Instrumental Neutron Activation Analysis

    SciTech Connect

    Palomares, R. I.; Dayman, Kenneth J.; Landsberger, Sheldon; Biegalski, Steven R.; Soderquist, Chuck Z.; Casella, Amanda J.; Brady Raap, Michaele C.; Schwantes, Jon M.

    2015-04-01

    Mass quantities of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis (NAA). Nuclide presence is predicted using fission yield analysis, and mass quantification is derived from standard gamma spectroscopy and radionuclide decay analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO2 fuel dissolved in nitric acid and UO2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared. Lastly, the implications of the rapid analytic speed of instrumental NAA are discussed in relation to potential nuclear forensics applications.

  10. Nuclear and microtubule remodeling and in vitro development of nuclear transferred cat oocytes with skin fibroblasts of the domestic cat (Felis silvestris catus) and leopard cat (Prionailurus bengalensis).

    PubMed

    Yin, X J; Lee, Y H; Jin, J Y; Kim, N H; Kong, I K

    2006-10-01

    The leopard cat (Prionailurus bengalensis), a member of the felidae family, is a threatened animal in South Korea. In terms of protecting endangered felids, nuclear transfer (NT) is a potentially valuable technique for assuring the continuation of species with dwindling numbers. In the present experiment, nuclear and microtubule remodeling and the in vitro developmental potential of enucleated domestic cat oocytes reconstructed with nuclei of somatic cells from either domestic cat fibroblast (DCF) or leopard cat fibroblast (LCF) were evaluated. Microtubule aster is allocated to de-condensed chromatin following nuclear transfer (3h after activation) of fibroblast cells from both domestic and leopard cats, suggesting the introduction of a somatic cell centrosome. The transferred fibroblast nuclei formed a large, swollen, pronuclear-like structure in most reconstructed oocytes, in the cat or leopard cat. At 18h following nuclear transfer, mitosis occurred, and according to the photo (F) it appears that spindle microtubules and two asters were observed. The percentages of blastocyst formation from nuclear transfer embryos derived from domestic cat fibroblasts (4/46, 8.6%) were not significantly different than those for nuclear transfer embryos constructed with leopard cat fibroblasts (4/52, 7.6%). These results indicate that nuclear and microtubule remodeling processes and in vitro developmental ability are similar in reconstructed cat oocytes following transfer of nuclei from either domestic or leopard cats. PMID:16310987

  11. Neutron resonance averaging

    SciTech Connect

    Chrien, R.E.

    1986-10-01

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

  12. Calculations of Nuclear Astrophysics and Californium Fission Neutron Spectrum Averaged Cross Section Uncertainties Using ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0 and Low-fidelity Covariances

    SciTech Connect

    Pritychenko, B.

    2015-01-15

    Nuclear astrophysics and californium fission neutron spectrum averaged cross sections and their uncertainties for ENDF materials have been calculated. Absolute values were deduced with Maxwellian and Mannhart spectra, while uncertainties are based on ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0 and Low-Fidelity covariances. These quantities are compared with available data, independent benchmarks, EXFOR library, and analyzed for a wide range of cases. Recommendations for neutron cross section covariances are given and implications are discussed.

  13. Calculations of Nuclear Astrophysics and Californium Fission Neutron Spectrum Averaged Cross Section Uncertainties Using ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0 and Low-fidelity Covariances

    NASA Astrophysics Data System (ADS)

    Pritychenko, B.

    2015-01-01

    Nuclear astrophysics and californium fission neutron spectrum averaged cross sections and their uncertainties for ENDF materials have been calculated. Absolute values were deduced with Maxwellian and Mannhart spectra, while uncertainties are based on ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0 and Low-Fidelity covariances. These quantities are compared with available data, independent benchmarks, EXFOR library, and analyzed for a wide range of cases. Recommendations for neutron cross section covariances are given and implications are discussed.

  14. The Neutron Capture Cross Sections of 237NP(n,{gamma}) and 240Pu(n,{gamma}) and Its Relevance in the Transmutation of Nuclear Waste

    SciTech Connect

    Guerrero, C.; Koehler, Paul Edward; Collaboration, n_TOF

    2008-01-01

    Neutron capture cross sections of actinides are of great relevance for the Transmutation of Nuclear Waste in Accelerator Driven Systems (ADS) and Generation-IV reactors. The neutron capture cross sections of {sup 237}Np and {sup 240}Pu were measured at the n{_}TOF facility with a Total Absorption Calorimeter. The data have been analyzed with the SAMMY code. The corresponding covariance matrices have been generated. The final cross sections are presented and compared to the previously existing ones.

  15. ITER Generic Diagnostic Upper Port Plug Nuclear Heating and Personnel Dose Rate Assesment Neutronics Analysis using the ATTILA Discrete Ordinates Code

    SciTech Connect

    Russell Feder and Mahmoud Z. Yousef

    2009-05-29

    Neutronics analysis to find nuclear heating rates and personnel dose rates were conducted in support of the integration of diagnostics in to the ITER Upper Port Plugs. Simplified shielding models of the Visible-Infrared diagnostic and of the ECH heating system were incorporated in to the ITER global CAD model. Results for these systems are representative of typical designs with maximum shielding and a small aperture (Vis-IR) and minimal shielding with a large aperture (ECH). The neutronics discrete-ordinates code ATTILA® and SEVERIAN® (the ATTILA parallel processing version) was used. Material properties and the 500 MW D-T volume source were taken from the ITER “Brand Model” MCNP benchmark model. A biased quadrature set equivelant to Sn=32 and a scattering degree of Pn=3 were used along with a 46-neutron and 21-gamma FENDL energy subgrouping. Total nuclear heating (neutron plug gamma heating) in the upper port plugs ranged between 380 and 350 kW for the Vis-IR and ECH cases. The ECH or Large Aperture model exhibited lower total heating but much higher peak volumetric heating on the upper port plug structure. Personnel dose rates are calculated in a three step process involving a neutron-only transport calculation, the generation of activation volume sources at pre-defined time steps and finally gamma transport analyses are run for selected time steps. ANSI-ANS 6.1.1 1977 Flux-to-Dose conversion factors were used. Dose rates were evaluated for 1 full year of 500 MW DT operation which is comprised of 3000 1800-second pulses. After one year the machine is shut down for maintenance and personnel are permitted to access the diagnostic interspace after 2-weeks if dose rates are below 100 μSv/hr. Dose rates in the Visible-IR diagnostic model after one day of shutdown were 130 μSv/hr but fell below the limit to 90 μSv/hr 2-weeks later. The Large Aperture or ECH style shielding model exhibited higher and more persistent dose rates. After 1-day the dose rate was 230

  16. When beauty is only skin deep; optimizing the sensitivity of specular neutron reflectivity for probing structure beneath the surface of thin filmsa)

    NASA Astrophysics Data System (ADS)

    Majkrzak, Charles F.; Carpenter, Elisabeth; Heinrich, Frank; Berk, Norman F.

    2011-11-01

    Specular neutron reflectometry has become an established probe of the nanometer scale structure of materials in thin film and multilayered form. It has contributed especially to our understanding of soft condensed matter of interest in polymer science, organic chemistry, and biology and of magnetic hard condensed matter systems. In this paper we examine a number of key factors which have emerged that can limit the sensitivity of neutron reflection as such a probe. Among these is loss of phase information, and we discuss how knowledge about material surrounding a film of interest can be applied to help resolve the problem. In this context we also consider what role the quantum phenomenon of interaction-free measurement might play in enhancing the statistical efficiency for obtaining reflectivity or transmission data.

  17. Skin Cancer

    MedlinePlus

    ... are specialized skin cells that produce pigment called melanin. The melanin pigment produced by melanocytes gives skin its color. ... absorbing and scattering the energy. People with more melanin have darker skin and better protection from UV ...

  18. Skin Conditions

    MedlinePlus

    Your skin is your body's largest organ. It covers and protects your body. Your skin Holds body fluids in, preventing dehydration Keeps harmful ... it Anything that irritates, clogs, or inflames your skin can cause symptoms such as redness, swelling, burning, ...

  19. Regulation of p53, nuclear factor {kappa}B and cyclooxygenase-2 expression by bromelain through targeting mitogen-activated protein kinase pathway in mouse skin

    SciTech Connect

    Kalra, Neetu; Bhui, Kulpreet; Roy, Preeti; Srivastava, Smita; George, Jasmine; Prasad, Sahdeo; Shukla, Yogeshwer

    2008-01-01

    Bromelain is a pharmacologically active compound, present in stems and immature fruits of pineapples (Ananas cosmosus), which has been shown to have anti-edematous, anti-inflammatory, anti-thrombotic and anti-metastatic properties. In the present study, antitumorigenic activity of bromelain was recorded in 7,12-dimethylbenz(a)anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted 2-stage mouse skin model. Results showed that bromelain application delayed the onset of tumorigenesis and reduced the cumulative number of tumors, tumor volume and the average number of tumors/mouse. To establish a cause and effect relationship, we targeted the proteins involved in the cell death pathway. Bromelain treatment resulted in upregulation of p53 and Bax and subsequent activation of caspase 3 and caspase 9 with concomitant decrease in antiapoptotic protein Bcl-2 in mouse skin. Since persistent induction of cyclooxygenase-2 (Cox-2) is frequently implicated in tumorigenesis and is regulated by nuclear factor-kappa B (NF-{kappa}B), we also investigated the effect of bromelain on Cox-2 and NF-{kappa}B expression. Results showed that bromelain application significantly inhibited Cox-2 and inactivated NF-{kappa}B by blocking phosphorylation and subsequent degradation of I{kappa}B{alpha}. In addition, bromelain treatment attenuated DMBA-TPA-induced phosphorylation of extracellular signal-regulated protein kinase (ERK1/2), mitogen-activated protein kinase (MAPK) and Akt. Taken together, we conclude that bromelain induces apoptosis-related proteins along with inhibition of NF-{kappa}B-driven Cox-2 expression by blocking the MAPK and Akt/protein kinase B signaling in DMBA-TPA-induced mouse skin tumors, which may account for its anti-tumorigenic effects.

  20. Assessment of the neutron activation of a stainless steel sample in a Research Nuclear Reactor using the Monte Carlo method and CINDER'90

    NASA Astrophysics Data System (ADS)

    Lázaro, Ignacio; Ródenas, José; Marques, José G.; Gallardo, Sergio

    2014-06-01

    Materials in a nuclear reactor are activated by neutron irradiation. When they are withdrawn from the reactor and placed in some storage, the potential dose received by workers in the surrounding area must be taken into account. In previous papers, activation of control rods in a NPP with BWR and dose rates around the storage pool have been estimated using the MCNP5 code based on the Monte Carlo method. Models were validated comparing simulation results with experimental measurements. As the activation is mostly produced in stainless steel components of control rods the activation model can be also validated by means of experimental measurements on a stainless steel sample after being irradiated in a reactor. This has been done in the Portuguese Research Reactor at Instituto Tecnológico e Nuclear. The neutron activation has been calculated by two different methods, Monte Carlo and CINDER'90, and results have been compared. After irradiation, dose rates at the water surface of the reactor pool were measured, with the irradiated stainless steel sample submerged at different positions under water. Experimental measurements have been compared with simulation results using Monte Carlo. The comparison shows a good agreement confirming the validation of models.

  1. In vessel detection of delayed neutron emitters from clad failure in sodium cooled nuclear reactors: An estimation of the signal

    NASA Astrophysics Data System (ADS)

    Filliatre, P.; Jammes, C.; Chapoutier, N.; Jeannot, J.-P.; Jadot, F.; Batail, R.; Verrier, D.

    2014-04-01

    The detection of clad failures is mandatory in sodium-cooled fast neutron reactors in compliance with the "clean sodium" concept. An in-vessel detection system, sensitive to delayed neutrons from fission products released into the primary coolant by failures, partially tested in SUPERPHENIX, is foreseen in current SFR projects in order to reduce significantly the delay before an alarm is issued. In this paper, an estimation of the signal received by such a system in case of a failure is derived, taking the French project ASTRID as a working example. This failure induced signal is compared to that of the contribution of the neutrons from the core itself. The sensitivity of the system is defined in terms of minimal detectable surface of clad failure. Possible solutions to improve this sensitivity are discussed, involving either the sensor itself, or the hydraulic design of the vessel in the early stage of the reactor conception.

  2. Surface harmonics method for two-dimensional time-dependent neutron transport problems of square-lattice nuclear reactors

    SciTech Connect

    Boyarinov, V. F.; Kondrushin, A. E.; Fomichenko, P. A.

    2013-07-01

    Time-dependent equations of the Surface Harmonics Method (SHM) have been derived from the time-dependent neutron transport equation with explicit representation of delayed neutrons for solving the two-dimensional time-dependent problems. These equations have been realized in the SUHAM-TD code. The TWIGL benchmark problem has been used for verification of the SUHAM-TD code. The results of the study showed that computational costs required to achieve necessary accuracy of the solution can be an order of magnitude less than with the use of the conventional finite difference method (FDM). (authors)

  3. NEUTRON DENSITY CONTROL IN A NEUTRONIC REACTOR

    DOEpatents

    Young, G.J.

    1959-06-30

    The method and means for controlling the neutron density in a nuclear reactor is described. It describes the method and means for flattening the neutron density distribution curve across the reactor by spacing the absorbing control members to varying depths in the central region closer to the center than to the periphery of the active portion of the reactor to provide a smaller neutron reproduction ratio in the region wherein the members are inserted, than in the remainder of the reactor thereby increasing the over-all potential power output.

  4. Constraining the EoS of neutron-rich matter by laboratory measurements

    NASA Astrophysics Data System (ADS)

    Lynch, William

    2014-09-01

    The density and momentum dependencies of the symmetry energy play an important role in the masses, isobaric analog states, low-lying E1 strength functions, neutron skins, giant resonances of neutron rich nuclei, and the isospin dependence of transport and emission during nuclear collisions. It also governs the internal structure of neutron stars, influences their radii and cooling rates as well as the neutrino transport in core-collapse supernova. This talk will discuss some current experimental constraints on the density and momentum dependence of the symmetry energy. It will also discuss future plans to extend these constraints to densities greater than that found in nuclei and similar to those found in the interiors of neutron stars. The density and momentum dependencies of the symmetry energy play an important role in the masses, isobaric analog states, low-lying E1 strength functions, neutron skins, giant resonances of neutron rich nuclei, and the isospin dependence of transport and emission during nuclear collisions. It also governs the internal structure of neutron stars, influences their radii and cooling rates as well as the neutrino transport in core-collapse supernova. This talk will discuss some current experimental constraints on the density and momentum dependence of the symmetry energy. It will also discuss future plans to extend these constraints to densities greater than that found in nuclei and similar to those found in the interiors of neutron stars. Work supported by the National Science Foundation under Grant PHY 1102511 and the Department of Energy under Grant No. DE-SC0004835.

  5. CONSTRAINING THE SYMMETRY PARAMETERS OF THE NUCLEAR INTERACTION

    SciTech Connect

    Lattimer, James M.; Lim, Yeunhwan E-mail: yeunhwan.lim@gmail.com

    2013-07-01

    One of the major uncertainties in the dense matter equation of state has been the nuclear symmetry energy. The density dependence of the symmetry energy is important in nuclear astrophysics, as it controls the neutronization of matter in core-collapse supernovae, the radii of neutron stars and the thicknesses of their crusts, the rate of cooling of neutron stars, and the properties of nuclei involved in r-process nucleosynthesis. We show that fits of nuclear masses to experimental masses, combined with other experimental information from neutron skins, heavy ion collisions, giant dipole resonances, and dipole polarizabilities, lead to stringent constraints on parameters that describe the symmetry energy near the nuclear saturation density. These constraints are remarkably consistent with inferences from theoretical calculations of pure neutron matter, and, furthermore, with astrophysical observations of neutron stars. The concordance of experimental, theoretical, and observational analyses suggests that the symmetry parameters S{sub v} and L are in the range 29.0-32.7 MeV and 40.5-61.9 MeV, respectively, and that the neutron star radius, for a 1.4 M{sub Sun} star, is in the narrow window 10.7 km neutron star crusts and the fractional moment of inertia they contain, as well as the overall moment of inertia and quadrupole polarizability of 1.4 M{sub Sun} stars. Our results also have implications for the disk mass and ejected mass of compact mergers involving neutron stars.

  6. Microscopic time-dependent analysis of neutrons transfers at low-energy nuclear reactions with spherical and deformed nuclei

    NASA Astrophysics Data System (ADS)

    Samarin, Viacheslav

    2014-03-01

    Time-dependent Schrödinger equation is numerically solved by difference method for external neutrons of nuclei 6He, 18O, 48Са, 238U at their grazing collisions with energies in the vicinity of a Coulomb barrier. The spin-orbital interaction and Pauli's exclusion principle were taken into consideration during the solution.

  7. Skin Biomes.

    PubMed

    Fyhrquist, N; Salava, A; Auvinen, P; Lauerma, A

    2016-05-01

    The cutaneous microbiome has been investigated broadly in recent years and some traditional perspectives are beginning to change. A diverse microbiome exists on human skin and has a potential to influence pathogenic microbes and modulate the course of skin disorders, e.g. atopic dermatitis. In addition to the known dysfunctions in barrier function of the skin and immunologic disturbances, evidence is rising that frequent skin disorders, e.g. atopic dermatitis, might be connected to a dysbiosis of the microbial community and changes in the skin microbiome. As a future perspective, examining the skin microbiome could be seen as a potential new diagnostic and therapeutic target in inflammatory skin disorders.

  8. Portable Neutron Sensors for Emergency Response Operations

    SciTech Connect

    ,

    2012-06-24

    This article presents the experimental work performed in the area of neutron detector development at the Remote Sensing Laboratory–Andrews Operations (RSL-AO) sponsored by the U.S. Department of Energy, National Nuclear Security Administration (NNSA) in the last four years. During the 1950s neutron detectors were developed mostly to characterize nuclear reactors where the neutron flux is high. Due to the indirect nature of neutron detection via interaction with other particles, neutron counting and neutron energy measurements have never been as precise as gamma-ray counting measurements and gamma-ray spectroscopy. This indirect nature is intrinsic to all neutron measurement endeavors (except perhaps for neutron spin-related experiments, viz. neutron spin-echo measurements where one obtains μeV energy resolution). In emergency response situations generally the count rates are low, and neutrons may be scattered around in inhomogeneous intervening materials. It is also true that neutron sensors are most efficient for the lowest energy neutrons, so it is not as easy to detect and count energetic neutrons. Most of the emergency response neutron detectors are offshoots of nuclear device diagnostics tools and special nuclear materials characterization equipment, because that is what is available commercially. These instruments mostly are laboratory equipment, and not field-deployable gear suited for mobile teams. Our goal is to design and prototype field-deployable, ruggedized, lightweight, efficient neutron detectors.

  9. Deployment of a three-dimensional array of Micro-Pocket Fission Detector triads (MPFD3) for real-time, in-core neutron flux measurements in the Kansas State University TRIGA Mark-II Nuclear Reactor

    NASA Astrophysics Data System (ADS)

    Ohmes, Martin Francis

    A Micro-Pocket Fission Detector (MPFD) is a miniaturized type of fission chamber developed for use inside a nuclear reactor. Their unique design allows them to be located between or even inside fuel pins while being built from materials which give them an operational lifetime comparable to or exceeding the life of the fuel. While other types of neutron detectors have been made for use inside a nuclear reactor, the MPFD is the first neutron detector which can survive sustained use inside a nuclear reactor while providing a real-time measurement of the neutron flux. This dissertation covers the deployment of MPFDs as a large three-dimensional array inside the Kansas State University TRIGA Mark-II Nuclear Reactor for real-time neutron flux measurements. This entails advancements in the design, construction, and packaging of the Micro-Pocket Fission Detector Triads with incorporated Thermocouple, or MPFD3-T. Specialized electronics and software also had to be designed and built in order to make a functional system capable of collecting real-time data from up to 60 MPFD3-Ts, or 180 individual MPFDs and 60 thermocouples. Design of the electronics required the development of detailed simulations and analysis for determining the theoretical response of the detectors and determination of their size. The results of this research shows that MPFDs can operate for extended times inside a nuclear reactor and can be utilized toward the use as distributed neutron detector arrays for advanced reactor control systems and power mapping. These functions are critical for continued gains in efficiency of nuclear power reactors while also improving safety through relatively inexpensive redundancy.

  10. Nuclear data uncertainty propagation for neutronic key parameters of CEA's SFR V2B and CFV sodium fast reactor designs

    SciTech Connect

    Archier, P.; Buiron, L.; De Saint Jean, C.; Dos Santos, N.

    2012-07-01

    This paper presents a nuclear data uncertainty propagation analysis for two CEA's Sodium-cooled Fast Reactor designs: the SFR V2B and CFV cores. The nuclear data covariance matrices are provided by the DER/SPRC/LEPh's nuclear data team (see companion paper) for several major isotopes. From the current status of this analysis, improvements on certain nuclear data reactions are highlighted as well as the need for new specific integral experiments in order to meet the technological breakthroughs proposed by the CFV core. (authors)

  11. Measurement of the Neutron Radius of 208Pb Through Parity Violation in Electron Scattering

    SciTech Connect

    Saenboonruang, Kiadtisak

    2013-05-01

    In contrast to the nuclear charge densities, which have been accurately measured with electron scattering, the knowledge of neutron densities still lack precision. Previous model-dependent hadron experiments suggest the difference between the neutron radius, Rn, of a heavy nucleus and the proton radius, Rp, to be in the order of several percent. To accurately obtain the difference, Rn-Rp, which is essentially a neutron skin, the Jefferson Lab Lead (208Pb) Radius Experiment (PREX) measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 208Pb at an energy of 1.06 GeV and a scattering angle of 5° . Since Z0 boson couples mainly to neutrons, this asymmetry provides a clean measurement of Rn with respect to Rp. PREX was conducted at the Jefferson lab experimental Hall A, from March to June 2010. The experiment collected a final data sample of 2x 107 helicity-window quadruplets. The measured parity-violating electroweak asymmetry APV = 0.656 ± 0.060 (stat) ± 0.014 (syst) ppm corresponds to a difference between the radii of the neutron and proton distributions, Rn-Rp = 0.33+0.16-0.18 fm and provides the first electroweak observation of the neutron skin as expected in a heavy, neutron-rich nucleus. The value of the neutron radius of 208Pb has important implications for models of nuclear structure and their application in atomic physics and astrophysics such as atomic parity non-conservation (PNC) and neutron stars.

  12. Neutron star crusts

    NASA Technical Reports Server (NTRS)

    Lorenz, C. P.; Ravenhall, D. G.; Pethick, C. J.

    1993-01-01

    We calculate properties of neutron star matter at subnuclear densities using an improved nuclear Hamiltonian. Nuclei disappear and the matter becomes uniform at a density of about 0.6n(s), where n(s) of about 0.16/cu fm is the saturation density of nuclear matter. As a consequence, the mass of matter in the crusts of neutron stars is only about half as large as previously estimated. In about half of that crustal mass, nuclear matter occurs in shapes very different from the roughly spherical nuclei familiar at lower densities. The thinner crust and the unusual nuclear shape have important consequences for theories of the rotational and thermal evolution of neutron stars, especialy theories of glitches.

  13. Similarity of nuclear structure in the {sup 132}Sn and {sup 208}Pb regions: Proton-neutron multiplets

    SciTech Connect

    Coraggio, L.; Gargano, A.; Covello, A.; Itaco, N.

    2009-08-15

    Starting from the striking similarity of proton-neutron multiplets in {sup 134}Sb and {sup 210}Bi, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the V{sub low-k} approach. The calculated results for {sup 136}Sb, {sup 212}Bi, {sup 136}I, and {sup 212}At are in very good agreement with the available experimental data. The similarity between {sup 132}Sn and {sup 208}Pb regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.

  14. Development of the quantum theory of T-odd asymmetries for prescission and evaporated third particles in ternary nuclear fission induced by cold polarized neutrons

    SciTech Connect

    Kadmensky, S. G.; Bunakov, V. E.; Titova, L. V.; Kadmensky, S. S.

    2011-10-15

    A comparative analysis of the results obtained by experimentally and theoretically studying T-odd asymmetries for various third particles in the true and delayed ternary nuclear fission induced by cold polarized neutrons was performed. It was confirmed that the appearance of these asymmetries was associated with the effect of rotation of a polarized system undergoing fission on the angular distributions of prescission and evaporated third particles with respect to the direction along which the emerging fission fragments flew apart, this effect being determined by the Coriolis interaction of the rotational and the internalmotion of the fissioning system. A quantum-mechanical description of particle motion in a rotating coordinate system was generalized to the case where gamma-ray emission was present. It was shown that the separation of the motions of an axially symmetric fissile system into a rotational and an internal motion was valid in the external region as well, where ternary-fission products had already been formed, if it was considered that the motion of fission fragments was tightly connected with the system symmetry axis, which rotated in the laboratory frame. It was found that the dependence of the fissile-system moment of inertia appearing in the Coriolis interaction Hamiltonian on the distance between the fission fragments flying apart generated an additional phase in the amplitude of the radial distribution of fission fragments. It was shown that this phase might change sizably the contribution of the interference between fission amplitudes of neutron resonances excited in a fissile compound nucleus to the absolute values of T -odd asymmetries, especially for third particles such as neutrons and photons, which interacted only slightly with fission fragments.

  15. Neutron Imaging Investigations of the Secondary Hydriding of Nuclear Fuel Cladding Alloys during Loss of Coolant Accidents

    NASA Astrophysics Data System (ADS)

    Grosse, M.; Roessger, C.; Stuckert, J.; Steinbrueck, M.; Kaestner, A.; Kardjilov, N.; Schillinger, B.

    The hydrogen concentration and distribution at both sides of the burst opening of cladding tubes used in three QUENCH-LOCA simulation bundle experiments were investigated by means of neutron radiography and tomography. The quantitative correlation between the total macroscopic neutron cross-section and the atomic number density ratio between hydrogen and zirconium was determined by testing calibration specimens with known hydrogen concentrations. Hydrogen enrichments located at the end of the ballooning zone of the tested tubes were detected in the inner rods of the test bundles. Nearly all of the peripheral claddings exposed to lower temperatures do not show such enrichments. This implies that under the conditions investigated a threshold temperature exists below which no hydrogen enrichments can be formed. In order to understand the hydrogen distribution a model was developed describing the processes occurring during loss of coolant accidents after rod burst. The general shape of the hydrogen distributions with a peak each side of the ballooning region is well predicted by this model whereas the absolute concentrations are underestimated compared to the results of the neutron tomography investigations. The model was also used to discuss the influence of the alloy composition on the secondary hydrogenation. Whereas the relations for the maximal hydrogen concentrations agree well for one and the same alloy, the agreement for tests with different alloys is less satisfying, showing that material parameters such as oxidation kinetics, phase transition temperature for the zirconium oxide, and yield strength and ductility at high temperature have to be taken into account to reproduce the results of neutron imaging investigations correctly.

  16. Passive cigarette smoke exposure inhibits ultraviolet light B-induced skin tumors in SKH-1 hairless mice by blocking the nuclear factor kappa B signalling pathway.

    PubMed

    Gottipati, Koteswara R; Poulsen, Henrik; Starcher, Barry

    2008-09-01

    Chronic exposure to sunlight [ultraviolet light B (UVB) irradiation] is the most common cause of non-melanoma skin tumors. In the present study, we investigated the effects of passive cigarette smoke superimposed over UVB irradiation, on tumor development, skin pathology and matrix changes in SKH-1 hairless mice. Groups of mice were exposed to 0.1 J/cm(2) of UVB five times per week for 20 weeks and/or exposure to passive cigarette smoke from 40 cigarettes a day over the same time period. UVB exposure resulted in an average of four large squamous cell carcinomas (SCC) and 15 smaller papillomas per mouse, whereas exposing the mice to both UVB + passive cigarette smoke completely prevented SCC formation and averaged less than one small papilloma per mouse. Oxidative DNA damage was investigated and there were no significant changes in the levels of urinary DNA adducts between control, smoke, UV and UV + smoke groups with the exception of 8-oxo guanine which was significantly reduced in the presence of passive cigarette smoke. Immunohistochemistry results revealed that tumor necrosis factor receptor 2 (TNF-R2), glycogen synthase kinase-3 beta, nuclear factor kappa B (NF-kappaB)/p65, KI-67 and cyclooxygenase 2 (COX-2) were markedly up-regulated in the epithelium by UVB exposure, whereas passive smoke exposure combined with the UVB irradiation completely blocked the expression of these proteins. Our results suggest that passive smoke exposure prevents UVB-induced SCC in mice and dramatically reduces the incidence of non-malignant papillomas by altering the NF-kappaB signalling pathway of tumorigenesis. PMID:18312384

  17. Californium-252: A New Isotopic Source for Neutron Radiography

    SciTech Connect

    Reinig, W.C.

    2001-08-29

    This report discusses a new isotopic source for neutron radiography, Californium-252. Nuclear reactors are the usual source of neutrons for radiography, primarily because of their intense neutron beams. If neutron radiography is to have widespread use, intense transportable neutron sources are required that can be used in plants, in laboratories and in the field.

  18. Modulation of expression of genes encoding nuclear proteins following exposure to JANUS neutrons or {gamma}-rays

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, Chin-Mei

    1994-05-01

    Previous work has shown that exposure of cells to ionizing radiations causes modulation of a variety of genes, including those encoding c-fos, interleukin-1, tumor necrosis factor, and cytoskeletal elements. The experiments reported herein were designed to examine the effects of either JANUS neutron or {gamma}-ray exposure on expression of genes encoding nucleus-associated proteins (H4-histone, c-jun, c-myc, Rb, and p53). Cycling Syrian hamster embryo cells were irradiated with varying doses and dose rates of either JANUS fission-spectrum neutrons or {gamma}-rays; after incubation of the cell cultures for 1 h following radiation exposure, mRNA was harvested and analyzed by Northern blot. Results revealed induction of transcripts for c-jun, H4-histone, and (to a lesser extent) Rb following {gamma}-ray but not following neutron exposure. Expression of p53 and c-myc genes was unaffected by radiation exposure. Radiations at different doses and dose rates were compared for each of the genes studied.

  19. Nuclear structure beyond the neutron drip line. The lowest energy states in 9He via their T=5/2 isobaric analogs in 9Li

    DOE PAGESBeta

    Uberseder, E.; Rogachev, G. V.; Goldberg, V. Z.; Koshchiy, E.; Roeder, B. T.; Alcorta, M.; Chubarian, G.; Davids, B.; Fu, C.; Hooker, J.; et al

    2016-03-01

    The level structure of the very neutron rich and unbound 9He nucleus has been the subject of significant experimental and theoretical study. Many recent works have claimed that the two lowest energy 9He states exist with spins Jπ=1/2+and Jπ=1/2-and widths on the order of 100–200 keV. These find-ings cannot be reconciled with our contemporary understanding of nuclear structure. Our present work is the first high-resolution study with low statistical uncertainty of the relevant excitation energy range in the 8He+n system, performed via a search for the T =5/2 isobaric analog states in 9Li populated through 8He+p elastic scattering. Moreover, themore » present data show no indication of any narrow structures. Instead, we find evidence for a broad Jπ=1/2+state in 9He located approximately 3 MeV above the neutron decay threshold.« less

  20. Determination of the ¹⁴C content in activated steel components from a neutron spallation source and a nuclear power plant.

    PubMed

    Schumann, Dorothea; Stowasser, Tanja; Volmert, Benjamin; Günther-Leopold, Ines; Linder, Hanspeter; Wieland, Erich

    2014-06-01

    The (14)C content in activated steel components from the Swiss Nuclear Power Plant (NPP) Gösgen and the Spallation Neutron Source SINQ at the Paul Scherrer Institute is determined using a wet chemistry digestion technique and liquid scintillation counting for (14)C activity measurements. The (14)C activity of an activated fuel assembly steel nut from the NPP is further compared with theoretical predictions made on the basis of a Monte Carlo reactor model for this NPP. Knowledge of the (14)C inventory in these activated steel materials is important in conjunction with future corrosion studies on these materials aimed at identifying the (14)C containing organic compounds possibly formed in the cement-based near field of a repository for radioactive waste.