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Sample records for neutron irradiated fissile

  1. Separation and Quantification of Chemically Diverse Analytes in Neutron Irradiated Fissile Materials

    SciTech Connect

    Douglas, Matthew; Friese, Judah I.; Greenwood, Lawrence R.; Farmer, Orville T.; Thomas, Linda MP; Maiti, Tapas C.; Finn, Erin C.; Garofoli, Stephanie J.; Gassman, Paul L.; Huff, Morgan M.; Schulte, Shannon M.; Smith, Steven C.; Thomas, Kathie K.; Bachelor, Paula P.

    2009-10-01

    Quantitative measurement of fission and activation products resulting from neutron irradiation of fissile materials is of interest for applications in environmental monitoring, nuclear waste management, and national security. To overcome mass and spectral interferences, and the relative small quantities of some target analytes, an extensive series of chemical separations is necessary. Based on established separations processes involving co-precipitation, solvent extraction, and ion-exchange and extraction chromatography, we have been evaluating and optimizing a proposed sequence of separation steps to allow for the timely quantification of analytes of interest. For simplicity, much of the chemical separation development work has been performed using stable elements as surrogates for the radioactive material. We have recently evaluated the optimized procedures using an irradiated sample to examine the adequacy of separations for measurement of desired analytes by gamma spectrometry. Here we present the results of this evaluation and describe the radiochemical separations utilized.

  2. Experimental Studies on the Self-Shielding Effect in Fissile Fuel Breeding Measurement in Thorium Oxide Pellets Irradiated with 14 MeV Neutrons

    NASA Astrophysics Data System (ADS)

    Mitul, Abhangi; Nupur, Jain; Rajnikant, Makwana; Sudhirsinh, Vala; Shrichand, Jakhar; K. Basu, T.; V. S. Rao, C.

    2013-02-01

    The 14 MeV neutrons produced in the D-T fusion reactions have the potential of breeding Uranium-233 fissile fuel from fertile material Thorium-232. In order to estimate the amount of U-233 produced, experiments are carried out by irradiating thorium dioxide pellets with neutrons produced from a 14 MeV neutron generator. The objective of the present work is to measure the reaction rates of 232Th + 1n → 233Th → 233Pa → 233U in different pellet thicknesses to study the self-shielding effects and adopt a procedure for correction. An appropriate assembly consisting of high-density polyethylene is designed and fabricated to slow down the high-energy neutrons, in which Thorium pellets are irradiated. The amount of fissile fuel (233U) produced is estimated by measuring the 312 keV gammas emitted by Protactinium-233 (half-life of 27 days). A calibrated High Purity Germanium (HPGe) detector is used to measure the gamma ray spectrum. The amount of 233U produced by Th232 (n, γ) is calculated using MCNP code. The self-shielding effect is evaluated by calculating the reaction rates for different foil thickness. MCNP calculation results are compared with the experimental values and appropriate correction factors are estimated for self-shielding of neutrons and absorption of gamma rays.

  3. Fissile solution measurement apparatus

    DOEpatents

    Crane, T.W.; Collinsworth, P.R.

    1984-06-11

    An apparatus for determining the content of a fissile material within a solution by detecting delayed fission neutrons emitted by the fissile material after it is temporarily irradiated by a neutron source. The apparatus comprises a container holding the solution and having a portion defining a neutron source cavity centrally disposed within the container. The neutron source cavity temporarily receives the neutron source. The container has portions defining a plurality of neutron detector ports that form an annular pattern and surround the neutron source cavity. A plurality of neutron detectors count delayed fission neutrons emitted by the fissile material. Each neutron detector is located in a separate one of the neutron detector ports.

  4. Impact of delayed neutron precursor mobility in fissile solution systems

    SciTech Connect

    Kiedrowski, B. C.

    2012-07-01

    A research version of the Monte Carlo software package MCNP6 is modified to incorporate advection and diffusion of delayed neutron precursors, resulting in the emission of delayed neutrons at locations different from the original fission sites. Results of two test problems, a pipe carrying flowing fissile solution and a sphere of fissile solution with precursor diffusion, show that the fission product mobility tends to perturb the fundamental mode, has a negative reactivity effect, and, perhaps most importantly, causes a decrease in the effective delayed neutron fraction. (authors)

  5. Fissile mass estimation by pulsed neutron source interrogation

    NASA Astrophysics Data System (ADS)

    Israelashvili, I.; Dubi, C.; Ettedgui, H.; Ocherashvili, A.; Pedersen, B.; Beck, A.; Roesgen, E.; Crochmore, J. M.; Ridnik, T.; Yaar, I.

    2015-06-01

    Passive methods for detecting correlated neutrons from spontaneous fissions (e.g. multiplicity and SVM) are widely used for fissile mass estimations. These methods can be used for fissile materials that emit a significant amount of fission neutrons (like plutonium). Active interrogation, in which fissions are induced in the tested material by an external continuous source or by a pulsed neutron source, has the potential advantages of fast measurement, alongside independence of the spontaneous fissions of the tested fissile material, thus enabling uranium measurement. Until recently, using the multiplicity method, for uranium mass estimation, was possible only for active interrogation made with continues neutron source. Pulsed active neutron interrogation measurements were analyzed with techniques, e.g. differential die away analysis (DDA), which ignore or implicitly include the multiplicity effect (self-induced fission chains). Recently, both, the multiplicity and the SVM techniques, were theoretically extended for analyzing active fissile mass measurements, made by a pulsed neutron source. In this study the SVM technique for pulsed neutron source is experimentally examined, for the first time. The measurements were conducted at the PUNITA facility of the Joint Research Centre in Ispra, Italy. First promising results, of mass estimation by the SVM technique using a pulsed neutron source, are presented.

  6. Fissile Materials Detection via Neutron Differential Die-Away Technique

    NASA Astrophysics Data System (ADS)

    Batyaev, V. F.; Bochkarev, O. V.; Sklyarov, S. V.

    2014-02-01

    This work is devoted to the differential die-away technique that is widely used for active detection of fissile materials via pulsed neutron generators. The technique allows direct detection of milligram quantities of uranium-235 and plutonium-239 in objects with volumes up to several cubic meters. Our group has demonstrated this technique, creating a special installation based on the commercially produced ING-07T pulsed neutron generator. The installation includes eight proportional 3He-counters mounted inside a polyethylene moderator with a cadmium filter, as well as a polyethylene chamber into which a 70-liter container is loaded for inspection. Preliminary testing showed that the minimum detectable mass of unshielded uranium-235 is ˜3 mg, using a 5.108 n/s neutron yield and 8 min measurement time. When the container is filled with neutron absorbing materials, e.g., iron, the minimum detectable mass increases to ˜30 mg. Use of borated screens further increases the minimum mass that can be detected. The tested installation and/or its modifications can be used for control and detection of fissile materials in various applications from luggage inspection to control containers with nuclear fuel cycle radioactive wastes.

  7. Non-destructive assay of fissile materials through active neutron interrogation technique using pulsed neutron (plasma focus) device

    NASA Astrophysics Data System (ADS)

    Tomar, B. S.; Kaushik, T. C.; Andola, Sanjay; Ramniranjan; Rout, R. K.; Kumar, Ashwani; Paranjape, D. B.; Kumar, Pradeep; Ramakumar, K. L.; Gupta, S. C.; Sinha, R. K.

    2013-03-01

    Pulsed neutrons emitted from a plasma focus (PF) device have been used for the first time for the non-destructive assay of 235U content in different chemical forms (oxide and metal). The PF device generates (1.2±0.3)×109 D-D fusion neutrons per shot with a pulse width of 46±5 ns. The method involves the measurement of delayed neutrons from an irradiated sample 50 ms after exposure to the neutron pulse for a time of about 100 s in the multichannel scaling (MCS) mode. The calibration of the active interrogation delayed neutron counter (AIDNEC) system was carried out by irradiating U3O8 samples of varying amounts (0.1-40 g) containing enriched 235U (14.8%) in the device. The delayed neutrons were monitored using a bank of six 3He detectors. The sensitivity of the system was found to be about 100 counts/s/g over the accumulation time of 25 s per neutron pulse of ˜109. The detection limit of the system is estimated to be 18 mg of 235U. The system can be suitably modified for applications toward non-destructive assay of fissile content in waste packets.

  8. FISSILE MATERIAL AND FUEL ELEMENTS FOR NEUTRONIC REACTORS

    DOEpatents

    Shaner, B.E.

    1961-08-15

    The fissile material consists of about 64 to 70% (weight) zirconium dioxide, 15 to 19% uranium dioxide, and 8 to 17% calcium oxide. The fissile material is formed into sintered composites which are disposed in a compartmented fuel element, comprising essentially a flat filler plate having a plurality of compartments therein, enclosed in cladding plates of the same material as the filler plate. The resultant fuel has good resistance to corrosion in high temperature pressurized water, good dimensional stability to elevated temperatures, and good resistance to thermal shock. (AEC)

  9. Development and calibration of the shielded measurement system for fissile contents measurements on irradiated nuclear fuel in dry storage.

    SciTech Connect

    Mosby, W. R.; Jensen, B. A.

    2002-05-31

    In recent years there has been a trend towards storage of Irradiated Nuclear Fuel (INF) in dry conditions rather than in underwater environments. At the same time, the Department of Energy (DOE) has begun encouraging custodians of INF to perform measurements on INF for which no recent fissile contents measurement data exists. INF, in the form of spent fuel from Experimental Breeder Reactor 2 (EBR-II), has been stored in close-fitting, dry underground storage locations at the Radioactive Scrap and Waste Facility (RSWF) at Argonne National Laboratory-West (ANL-W) for many years. In Fiscal Year 2000, funding was obtained from the DOE Office of Safeguards and Security Technology Development Program to develop and prepare for deployment a Shielded Measurement System (SMS) to perform fissile content measurements on INF stored in the RSWF. The SMS is equipped to lift an INF item out of its storage location, perform scanning neutron coincidence and high-resolution gamma-ray measurements, and restore the item to its storage location. The neutron and gamma-ray measurement results are compared to predictions based on isotope depletion and Monte Carlo neutral-particle transport models to provide confirmation of the accuracy of the models and hence of the fissile material contents of the item as calculated by the same models. This paper describes the SMS and discusses the results of the first calibration and validation measurements performed with the SMS.

  10. Assessment of neutron dosemeters around standard sources and nuclear fissile objects.

    PubMed

    Raimondi, N; Tournier, B; Groetz, J E; Piot, J; Riebler, E; Crovisier, P; Chambaudet, A; Cabanné, N

    2002-01-01

    In order to evaluate the neutron doses around nuclear fissile objects, a comparative study has been made on several neutron dosemeters: bubble dosemeters, etched-track detectors (CR-39) and 3He-filled proportional counters used as dose-rate meters. The measurements were made on the ambient and the personal dose equivalents H*(10) and Hp(10). Results showed that several bubble dosemeters should have been used due to a low reproducibility in the measurements. A strong correlation with the neutron energy was also found, with about a 30% underestimation of Hp(10) for neutrons from the PuBe source, and about a 9% overestimation for neutrons from the 252Cf source. Measurements of the nuclear fissile objects were made using the CR-39 and the dose-rate meters. The CR-39 led to an underestimation of 30% with respect to the neutron dose-rate meter measurements. In addition, the MCNP calculation code was used in the different configurations. PMID:12382734

  11. Direct fissile assay of enriched uranium using random self-interrogation and neutron coincidence response

    DOEpatents

    Menlove, Howard O.; Stewart, James E.

    1986-01-01

    Apparatus and method for the direct, nondestructive evaluation of the .sup.235 U nuclide content of samples containing UF.sub.6, UF.sub.4, or UO.sub.2 utilizing the passive neutron self-interrogation of the sample resulting from the intrinsic production of neutrons therein. The ratio of the emitted neutron coincidence count rate to the total emitted neutron count rate is determined and yields a measure of the bulk fissile mass. The accuracy of the method is 6.8% (1.sigma.) for cylinders containing UF.sub.6 with enrichments ranging from 6% to 98% with measurement times varying from 3-6 min. The samples contained from below 1 kg to greater than 16 kg. Since the subject invention relies on fast neutron self-interrogation, complete sampling of the UF.sub.6 takes place, reducing difficulties arising from inhomogeneity of the sample which adversely affects other assay procedures.

  12. Direct fissile assay of enriched uranium using random self-interrogation and neutron coincidence response

    DOEpatents

    Menlove, H.O.; Stewart, J.E.

    1985-02-04

    Apparatus and method for the direct, nondestructive evaluation of the /sup 235/U nuclide content of samples containing UF/sub 6/, UF/sub 4/, or UO/sub 2/ utilizing the passive neutron self-interrogation of the sample resulting from the intrinsic production of neutrons therein. The ratio of the emitted neutron coincidence count rate to the total emitted neutron count rate is determined and yields a measure of the bulk fissile mass. The accuracy of the method is 6.8% (1sigma) for cylinders containing UF/sub 6/ with enrichments ranging from 6% to 98% with measurement times varying from 3-6 min. The samples contained from below 1 kg to greater than 16 kg. Since the subject invention relies on fast neutron self-interrogation, complete sampling of the UF/sub 6/ takes place, reducing difficulties arising from inhomogeneity of the sample which adversely affects other assay procedures. 4 figs., 1 tab.

  13. Canyon transfer neutron absorber to fissile material ratio analysis. Revision 1

    SciTech Connect

    Clemmons, J.S.

    1994-03-04

    Waste tank fissile material and non-fissile material estimates are used to evaluate criticality safety for the existing sludge inventory and batches of sludge sent to Extended Sludge Processing (ESP). This report documents the weight ratios of several non-fissile waste constituents to fissile waste constituents from canyon reprocessing waste streams. Weight ratios of Fe, Mn, Al, Mi, and U-238 to fissile material are calculated from monthly loss estimates from the F and H Canyon Low Heat Waste (LHW) and High Heat Waste (HHW) streams. The monthly weight ratios for Fe, Mn and U-238 are then compared to calculated minimum safe weight ratios. Documented minimum safe weight ratios for Al and Ni to fissile material are currently not available. Total mass data for the subject sludge constituents is provided along with scatter plots of the monthly weight ratios for each waste stream.

  14. Apparatus for in situ determination of burnup, cooling time and fissile content of an irradiated nuclear fuel assembly in a fuel storage pond

    DOEpatents

    Phillips, John R.; Halbig, James K.; Menlove, Howard O.; Klosterbuer, Shirley F.

    1985-01-01

    A detector head for in situ inspection of irradiated nuclear fuel assemblies submerged in a water-filled nuclear fuel storage pond. The detector head includes two parallel arms which extend from a housing and which are spaced apart so as to be positionable on opposite sides of a submerged fuel assembly. Each arm includes an ionization chamber and two fission chambers. One fission chamber in each arm is enclosed in a cadmium shield and the other fission chamber is unshielded. The ratio of the outputs of the shielded and unshielded fission chambers is used to determine the boron content of the pond water. Correcting for the boron content, the neutron flux and gamma ray intensity are then used to verify the declared exposure, cooling time and fissile material content of the irradiated fuel assembly.

  15. Apparatus for in situ determination of burnup, cooling time and fissile content of an irradiated nuclear fuel assembly in a fuel storage pond

    DOEpatents

    Phillips, J.R.; Halbig, J.K.; Menlove, H.O.; Klosterbuer, S.F.

    1984-01-01

    A detector head for in situ inspection of irradiated nuclear fuel assemblies submerged in a water-filled nuclear fuel storage pond. The detector head includes two parallel arms which extend from a housing and which are spaced apart so as to be positionable on opposite sides of a submerged fuel assembly. Each arm includes an ionization chamber and two fission chambers. One fission chamber in each arm is enclosed in a cadmium shield and the other fission chamber is unshielded. The ratio of the outputs of the shielded and unshielded fission chambers is used to determine the boron content of the pond water. Correcting for the boron content, the neutron flux and gamma ray intensity are then used to verify the declared exposure, cooling time and fissile material content of the irradiated fuel assembly.

  16. Fissile material detector

    DOEpatents

    Ivanov, Alexander I.; Lushchikov, Vladislav I.; Shabalin, Eugeny P.; Maznyy, Nikita G.; Khvastunov, Michael M.; Rowland, Mark

    2002-01-01

    A detector for fissile materials which provides for integrity monitoring of fissile materials and can be used for nondestructive assay to confirm the presence of a stable content of fissile material in items. The detector has a sample cavity large enough to enable assay of large items of arbitrary configuration, utilizes neutron sources fabricated in spatially extended shapes mounted on the endcaps of the sample cavity, incorporates a thermal neutron filter insert with reflector properties, and the electronics module includes a neutron multiplicity coincidence counter.

  17. Determining fissile content in PWR spent fuel assemblies using a passive neutron Albedo reactivity with fission chambers technique

    SciTech Connect

    Conlin, Jeremy Lloyd; Tobin, Stephen J

    2010-01-01

    State regulatory bodies and organizations such as the IAEA that are concerned with preventing the proliferation of nuclear weapons are interested in a means of quantifying the amount of plutonium in a given spent fuel assembly. The complexity of spent nuclear fuel makes the measurement of plutonium content challenging. There are a variety of techniques that can measure various properties of spent nuclear fuel including burnup, and mass of fissile content. No single technique can provide all desired information, necessitating an approach using multiple detector systems and types. This paper presents our analysis of the Passive Neutron Albedo Reactivity Fission Chamber (PNAR-FC) detector system. PNAR-FC is a simplified version of the PNAR technique originally developed in 1997. This earlier research was performed with a high efficiency, {sup 3}He-based system (PNAR-3He) with which multiplicty analysis was performed. With the PNAR technique a portion of the spent fuel assembly is wrapped in a 1 mm thick cadmium liner. Neutron count rates are measured both with and without the cadmium liner present. The ratio of the count rate with the cadmium liner to the count rate without the cadmium liner is calculated and called the cadmium ratio. In the PNAR-3He technique, multiplicity measurements were made and the cadmium ratio was shown to scale with the fissile content of the material being measured. PNAR-FC simplifies the PNAR technique by using only a few fission chambers instead of many {sup 3}He tubes. Using a simplified PNAR-FC technique provides for a cheaper, lighter, and thus more portable detector system than was possible with the PNAR-3He system. The challenge with the PNAR-FC system are two-fold: (1) the change in the cadmium ratio is weaker as a afunction of the changing fissile content relative to multiplicity count rates, and (2) the efficiency for the fission chamber based system are poorer than for the {sup 3}He based detectors. In this paper, we present our

  18. 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.

  19. A novel method for active fissile mass estimation with a pulsed neutron source

    NASA Astrophysics Data System (ADS)

    Dubi, C.; Ridnik, T.; Israelashvili, I.; Pedersen, B.

    2013-07-01

    Neutron interrogation facilities for mass evaluation of Special Nuclear Materials (SNM) samples are divided into two main categories: passive interrogation, where all neutron detections are due to spontaneous events, and active interrogation, where fissions are induced on the tested material by an external neutron source. While active methods are, in general, faster and more effective, their analysis is much harder to carry out. In the paper, we will introduce a new formalism for analyzing the detection signal generated by a pulsed source active interrogation facility. The analysis is aimed to distinct between fission neutrons from the main neutron source in the system, and the surrounding "neutron noise". In particular, we derive analytic expressions for the first three central moments of the number of detections in a given time interval, in terms of the different neutron sources. While the method depends on exactly the same physical assumptions as known models, the simplicity of the suggested formalism allows us to take into account the variance of the external neutron source—an effect that was so far neglected.

  20. Development of self-interrogation neutron resonance densitometry (sinrd) to measure the fissile content in nuclear fuel

    NASA Astrophysics Data System (ADS)

    LaFleur, Adrienne Marie

    The development of non-destructive assay (NDA) capabilities to directly measure the fissile content in spent fuel is needed to improve the timely detection of the diversion of significant quantities of fissile material. Currently, the International Atomic Energy Agency (IAEA) does not have effective NDA methods to verify spent fuel and recover continuity of knowledge in the event of a containment and surveillance systems failure. This issue has become increasingly critical with the worldwide expansion of nuclear power, adoption of enhanced safeguards criteria for spent fuel verification, and recent efforts by the IAEA to incorporate an integrated safeguards regime. In order to address these issues, the use of Self-Interrogation Neutron Resonance Densitometry (SINRD) has been developed to improve existing nuclear safeguards and material accountability measurements. The following characteristics of SINRD were analyzed: (1) ability to measure the fissile content in Light Water Reactors (LWR) fuel assemblies and (2) sensitivity and penetrability of SINRD to the removal of fuel pins from an assembly. The Monte Carlo Neutral Particle eXtended (MCNPX) transport code was used to simulate SINRD for different geometries. Experimental measurements were also performed with SINRD and were compared to MCNPX simulations of the experiment to verify the accuracy of the MCNPX model of SINRD. Based on the results from these simulations and measurements, we have concluded that SINRD provides a number of improvements over current IAEA verification methods. These improvements include: (1) SINRD provides absolute measurements of burnup independent of the operator's declaration. (2) SINRD is sensitive to pin removal over the entire burnup range and can verify the diversion of 6% of fuel pins within 3o from LWR spent LEU and MOX fuel. (3) SINRD is insensitive to the boron concentration and initial fuel enrichment and can therefore be used at multiple spent fuel storage facilities. (4) The

  1. Total body calcium analysis. [neutron irradiation

    NASA Technical Reports Server (NTRS)

    Lewellen, T. K.; Nelp, W. B.

    1974-01-01

    A technique to quantitate total body calcium in humans is developed. Total body neutron irradiation is utilized to produce argon 37. The radio argon, which diffuses into the blood stream and is excreted through the lungs, is recovered from the exhaled breath and counted inside a proportional detector. Emphasis is placed on: (1) measurement of the rate of excretion of radio argon following total body neutron irradiation; (2) the development of the radio argon collection, purification, and counting systems; and (3) development of a patient irradiation facility using a 14 MeV neutron generator. Results and applications are discussed in detail.

  2. Neutrons as Party Animals: An Analogy for Understanding Heavy-Element Fissility

    NASA Astrophysics Data System (ADS)

    Reed, B. Cameron

    2012-12-01

    I teach a general education class on the history of nuclear physics and the Manhattan Project. About halfway through the course we come to the discovery of fission and Niels Bohr's insight that it is the rare isotope of uranium, U-235, which fissions under slow-neutron bombardment as opposed to the much more common U-238 isotope. As an "explanation" of the differing responses of the two isotopes to bombarding neutrons, I use the known (measured) masses of the various isotopes involved to compute the energies released upon neutron capture and then compare them to the fission barriers of the "compound" nuclei so formed (U-236 and U-239). The energy released in the (neutron + U-235) reaction exceeds the fission barrier by about one million electron-volts (1 MeV), while that for the (neutron + U-238) case falls about 1.6 MeV short. (The fission barriers are respectively about 5.7 and 6.5 MeV.)

  3. New facility for post irradiation examination of neutron irradiated beryllium

    SciTech Connect

    Ishitsuka, Etsuo; Kawamura, Hiroshi

    1995-09-01

    Beryllium is expected as a neutron multiplier and plasma facing materials in the fusion reactor, and the neutron irradiation data on properties of beryllium up to 800{degrees}C need for the engineering design. The acquisition of data on the tritium behavior, swelling, thermal and mechanical properties are first priority in ITER design. Facility for the post irradiation examination of neutron irradiated beryllium was constructed in the hot laboratory of Japan Materials Testing Reactor to get the engineering design data mentioned above. This facility consist of the four glove boxes, dry air supplier, tritium monitoring and removal system, storage box of neutron irradiated samples. Beryllium handling are restricted by the amount of tritium;7.4 GBq/day and {sup 60}Co;7.4 MBq/day.

  4. Neutrons as Party Animals: An Analogy for Understanding Heavy-Element Fissility

    ERIC Educational Resources Information Center

    Reed, B. Cameron

    2012-01-01

    I teach a general education class on the history of nuclear physics and the Manhattan Project. About halfway through the course we come to the discovery of fission and Niels Bohr's insight that it is the rare isotope of uranium, U-235, which fissions under slow-neutron bombardment as opposed to the much more common U-238 isotope. As an…

  5. Neutron irradiation effects in GaAs

    SciTech Connect

    Patel, J.U.

    1992-01-01

    Changes in electrical properties of n-GaAs as a result of irradiations with fast neutron have been studied, after epitaxial layers doped with Si at concentrations in the range 1.35 x 10[sup 15] to 1.60 x 10[sup 16] cm[sup [minus]3] were irradiated with reactor neutron fluences up to 1.31 x 10[sup 15] cm [sup [minus]2]. When the changes in carrier concentration, Hall mobility and resistivity were more than 25% of their initial values, nonlinear dependence on neutron fluence was apparent. New theory is proposed which explains the changes in electrical properties in terms of rates of trapping and release of charges. A theoretical relationship is derived for the change in carrier concentration as a function of neutron fluence and Fermi level shift was found to be consistent with the observed changes in carrier concentration. A correlation has been found between the changes in carrier concentration and mobility with neutron fluence using newly defined physically meaningful parameters in the case of two pairs of samples. The correlation has been explained in terms of the increased scattering of charge carriers from the defects created by neutrons that trap the free carriers. Mobility changes were measured at temperatures from 15 K to 305 K in n-GaAs van-der Pauw samples irradiated by fast reactor neutrons. The inverse mobility values obtain versus temperature, from the variable temperature Hall measurements, in the case of irradiated and in-irradiated samples were fitted using the relation [mu][sup [minus]1] = T[sup [minus]3/2] + B T[sup 3/2]. The inverse mobility increased as a result of neutron irradiations over the whole range of temperature, the increase being attributed to the increased scattering from neutron induced charged defects.

  6. Neutron-Absorbing Coatings for Safe Storage of Fissile Materials with Enhanced Shielding & Criticality Safety

    SciTech Connect

    Choi, J; Farmer, J; Lee, C; Fischer, L; Boussoufi, M; Liu, B; Egbert, H

    2007-07-03

    Neutron-absorbing Fe-based amorphous-metal coatings have been developed that are more corrosion resistant than other criticality-control materials, including Al-B{sub 4}C composites, borated stainless steels, and Ni-Cr-Mo-Gd alloys. The presence of relatively high concentration of boron in these coatings not only enhances its neutron-absorption capability, but also enables these coatings to exist in the amorphous state. Exceptional corrosion resistance has been achieved with these Fe-based amorphous-metal alloys through additions of chromium, molybdenum, and tungsten. The addition of rare earth elements such as yttrium has lowered the critical cooling rate of these materials, thereby rendering them more easily processed. Containers used for the storage of nuclear materials, and protected from corrosion through the application of amorphous metal coatings, would have greatly enhanced service lives, and would therefore provide greater long-term safety. Amorphous alloy powders have been successfully produced in multi-ton quantities with gas atomization, and applied to several half-scale spent fuel storage containers and criticality control structures with the high-velocity oxy-fuel (HVOF) thermal spray process. Salt fog testing and neutron radiography of these prototypes indicates that such an approach is viable for the production of large-scale industrial-scale facilities and containers. The use of these durable neutron-absorbing materials to coat stainless steel containers and storage racks, as well as vaults, hot-cell facilities and glove boxes could substantially reduce the risk of criticality in the event of an accident. These materials are particularly attractive for shielding applications since they are fire proof. Additionally, layers of other cold and thermal sprayed materials that include carbon and/or carbides can be used in conjunction with the high-boron amorphous metal coatings for the purpose of moderation. For example, various carbides, including boron

  7. Neoplasia in fast neutron-irradiated beagles

    SciTech Connect

    Bradley, E.W.; Zook, B.C.; Casarett, G.W.; Deye, J.A.; Adoff, L.M.; Rogers, C.C.

    1981-09-01

    One hundred fifty-one beagle dogs were irradiated with either photons or fast neutrons (15 MeV) to one of three dose-limiting normal tissues--spinal cord, lung, or brain. The radiation was given in four fractions per week for 5 weeks (spinal cord), 6 weeks (lung), or 7 weeks (brain) to total doses encompassing those given clinically for cancer management. To date, no nonirradiated dogs or photon-irradiated dogs have developed any neoplasms. Seven dogs receiving fast neutrons have developed 9 neoplasms within the irradiated field. Of the neutron-irradiated dogs at risk, the incidence of neoplasia was 15%. The latent period for radiation-induced cancers has varied from 1 to 4 1/2 years at this time in the study.

  8. Neoplasia in fast neutron-irradiated beagles

    SciTech Connect

    Bradley, E.W.; Zook; B.C.; Casarett, G.W.

    1981-09-01

    One hundred fifty-one beagle dogs were irradiated with either photons or fast neutrons (15 MeV) to one of three dose-limiting normal tissues - spinal cord, lung, or brain. The radiation was given in four fractions per week for 5 weeks (spinal cord), 6 weeks (lung), 7 weeks (brain) to total doses encompassing those given clinically for cancer management. To date, no nonirradiated dogs or photon-irradiated dogs have developed neoplasms within the irradiated field. Of the neutron-irradiated dogs at risk, the incidence of neoplasia was 15%. The latent period for radiation-induced cancers has varied from 1 to 4 1/2 years at this time in the study.

  9. Neutron irradiation induced amorphization of silicon carbide

    SciTech Connect

    Snead, L.L.; Hay, J.C.

    1998-09-01

    This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 {times} 10{sup 25} n/m{sup 2}. Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density ({minus}10.8%), elastic modulus as measured using a nanoindentation technique ({minus}45%), hardness as measured by nanoindentation ({minus}45%), and standard Vickers hardness ({minus}24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C.

  10. Neutron irradiation of beryllium pebbles

    SciTech Connect

    Gelles, D.S.; Ermi, R.M.; Tsai, H.

    1998-03-01

    Seven subcapsules from the FFTF/MOTA 2B irradiation experiment containing 97 or 100% dense sintered beryllium cylindrical specimens in depleted lithium have been opened and the specimens retrieved for postirradiation examination. Irradiation conditions included 370 C to 1.6 {times} 10{sup 22} n/cm{sup 2}, 425 C to 4.8 {times} 10{sup 22} n/cm{sup 2}, and 550 C to 5.0 {times} 10{sup 22} n/cm{sup 2}. TEM specimens contained in these capsules were also retrieved, but many were broken. Density measurements of the cylindrical specimens showed as much as 1.59% swelling following irradiation at 500 C in 100% dense beryllium. Beryllium at 97% density generally gave slightly lower swelling values.

  11. Neutron Irradiation Resistance of RAFM Steels

    SciTech Connect

    Gaganidze, Ermile; Dafferner, Bernhard; Aktaa, Jarir

    2008-07-01

    The neutron irradiation resistance of the reduced-activation ferritic/martensitic (RAFM) steel EUROFER97 and international reference steels (F82H-mod, OPTIFER-Ia, GA3X and MANET-I) have been investigated after irradiation in the Petten High Flux Reactor up to 16.3 dpa at different irradiation temperatures (250-450 deg. C). The embrittlement behavior and hardening are investigated by instrumented Charpy-V tests with sub-size specimens. Neutron irradiation-induced embrittlement and hardening of EUROFER97 was studied under different heat treatment conditions. Embrittlement and hardening of as-delivered EUROFER97 steel are comparable to those of reference steels. Heat treatment of EUROFER97 at a higher austenitizing temperature substantially improves the embrittlement behaviour at low irradiation temperatures. Analysis of embrittlement vs. hardening behavior of RAFM steels within a proper model in terms of the parameter C={delta}DBTT/{delta}{sigma} indicates hardening-dominated embrittlement at irradiation temperatures below 350 deg. C with 0.17 {<=} C {<=} 0.53 deg. C/MPa. Scattering of C at irradiation temperatures above 400 deg. C indicates non hardening embrittlement. A role of He in a process of embrittlement is investigated in EUROFER97 based steels, that are doped with different contents of natural B and the separated {sup 10}B-isotope (0.008-0.112 wt.%). Testing on small scale fracture mechanical specimens for determination of quasi-static fracture toughness will be also presented in a view of future irradiation campaigns. (authors)

  12. Vanadium irradiation at ATR - neutronics aspects

    SciTech Connect

    Gomes, I.C.; Smith, D.L.

    1995-04-01

    Calculations were performed to estimate damage and transmutation rates in vanadium irradiated in the ATR (Advanced Test Reactor) located in Idaho. The main focuses of the study are to evaluate the transmutation of vanadium to chromium and to explore ways to design the irradiation experiment to avoid excessive transmutation. It was found that the A-hole of ATR produces damage rate of {approximately} 0.2%/dpa of vanadium to chromium. A thermal neutron filter can be incorporated into the design to reduce the vanadium-to-chromium transmutation rate to low levels. A filter 1-2 mm thick of gadolinium or hafnium can be used.

  13. Neutron Spectrum Measurements from Irradiations at NCERC

    SciTech Connect

    Jackman, Kevin Richard; Mosby, Michelle A.; Bredeweg, Todd Allen; Hutchens, Gregory Joe; White, Morgan Curtis

    2015-04-15

    Several irradiations have been conducted on assemblies (COMET/ZEUS and Flattop) at the National Criticality Experiments Research Center (NCERC) located at the Nevada National Security Site (NNSS). Configurations of the assemblies and irradiated materials changed between experiments. Different metallic foils were analyzed using the radioactivation method by gamma-ray spectrometry to understand/characterize the neutron spectra. Results of MCNP calculations are shown. It was concluded that MCNP simulated spectra agree with experimental measurements, with the caveats that some data are limited by statistics at low-energies and some activation foils have low activities.

  14. THERMAL NEUTRON INTENSITIES IN SOILS IRRADIATED BY FAST NEUTRONS FROM POINT SOURCES. (R825549C054)

    EPA Science Inventory

    Thermal-neutron fluences in soil are reported for selected fast-neutron sources, selected soil types, and selected irradiation geometries. Sources include 14 MeV neutrons from accelerators, neutrons from spontaneously fissioning 252Cf, and neutrons produced from alp...

  15. Effect of neutron irradiation on vanadium alloys

    SciTech Connect

    Braski, D.N.

    1986-01-01

    Neutron-irradiated vanadium alloys were evaluated for their susceptibility to irradiation hardening, helium embrittlement, swelling, and residual radioactivity, and the results were compared with those for the austenitic and ferritic stainless steels. The VANSTAR-7 and V-15Cr-5Ti alloys showed the greatest hardening between 400 and 600/sup 0/C while V-3Ti-1Si and V-20Ti had lower values that were comparable to those of ferritic steels. The V-15Cr-5Ti and VANSTAR-7 alloys were susceptible to helium embrittlement caused by the combination of weakened grain boundaries and irradiation-hardened grain matrices. Specimen fractures were entirely intergranular in the most severe instances of embrittlement. The V-3Ti-1Si and V-20Ti alloys were more resistant to helium embrittlement. Except for VANSTAR-7 irradiated to 40 dpa at 520/sup 0/C, all of the vanadium alloys exhibited low swelling that was similar to the ferritic steels. Swelling was greater in specimens that were preimplanted with helium using the tritium trick. The vanadium alloys clearly exhibit lower residual radioactivity after irradiation than the ferrous alloys.

  16. Persistent photoconductivity in neutron irradiated GaN

    NASA Astrophysics Data System (ADS)

    Minglan, Zhang; Ruixia, Yang; Naixin, Liu; Xiaoliang, Wang

    2013-09-01

    Unintentionally doped GaN films grown by MOCVD were irradiated with neutrons at room temperature. In order to investigate the influence of neutron irradiation on the optical properties of GaN films, persistent photoconductivity (PPC) and low temperature photoluminescence (PL) measurements were carried out. Pronounced PPC was observed in the samples before and after neutron irradiation without the appearance of a yellow luminescence (YL) band in the PL spectrum, suggesting that the origin of PPC and YL are not related. Moreover, PPC phenomenon was enhanced by neutron irradiation and quenched by the followed annealing process at 900 °C. The possible origin of PPC is discussed.

  17. Neutron irradiation of human melanoma cells.

    PubMed

    Brown, K; Mountford, M H; Allen, B J; Mishima, Y; Ichihashi, M; Parsons, P

    1989-01-01

    The biological characteristics and in vitro radiosensitivity of melanoma cells to thermal neutrons were investigated as a guide to the effectiveness of boron neutron capture therapy. Plateau phase cultures of three human malignant melanoma-established cell lines were examined for cell density at confluence, doubling time, cell cycle parameters, chromosome constitution, and melanin content. Cell survival dose-response curves, for cells preincubated in the presence or absence of p-boronophenylalanine. HCl (10B1-BPA), were measured over the dose range 0.6-8.0 Gy (N + gamma). The neutron fluence rate was 2.6 x 10(9) n/cm2/s and the total dose rate 3.7 Gy/h (31% gamma). Considerable differences were observed in the morphology and cellular properties of the cell lines. Two cell lines (96E and 96L) were amelanotic, and one was melanotic (418). An enhanced killing for neutron irradiation was found only for the melanotic cells after 20 h preincubation with 10 micrograms/ml 10B1-BPA. In view of the doubling times of the cell lines of about 23 h (96E and 96L) or of 36 h (418), it seems likely that an increased boron uptake, and hence increased radiosensitivity, might result if the preincubation period with 10B1-BPA is extended to several hours longer than the respective cell cycle times. PMID:2798324

  18. DECONTAMINATION OF NEUTRON-IRRADIATED REACTOR FUEL

    DOEpatents

    Buyers, A.G.; Rosen, F.D.; Motta, E.E.

    1959-12-22

    A pyrometallurgical method of decontaminating neutronirradiated reactor fuel is presented. In accordance with the invention, neutron-irradiated reactor fuel may be decontaminated by countercurrently contacting the fuel with a bed of alkali and alkaine fluorides under an inert gas atmosphere and inductively melting the fuel and tracking the resulting descending molten fuel with induction heating as it passes through the bed. By this method, a large, continually fresh surface of salt is exposed to the descending molten fuel which enhances the efficiency of the scrubbing operation.

  19. TEM study of neutron-irradiated iron

    SciTech Connect

    Horton, L.L.; Bentley, J.; Farrell, K.

    1981-01-01

    Results of a transmission electron microscopy study of the defect structure in iron neutron-irradiated to low fluences (less than or equal to 1 dpa) at temperatures of 455 to 1013/sup 0/K are presented. The dislocation microstructures coarsen with increasing irradiation temperature from decorated dislocations, through clusters of dislocation loops, to near-edge, interstitial dislocation loops with b = a<100>, and network segments. Significant cavity formation occurred only at 548 to 723/sup 0/K, with homogeneous distributions found only at 623 and 673/sup 0/K. The maximum swelling of 0.07% occurred at 673/sup 0/K. Large cavities had a truncated octahedral shape with (111) facets and (100) truncations. Damage halos were observed around boron-containing precipitates. The effects of interstitial impurities on microstructural development and the differences in the observed microstructures compared to those in refractory bcc metals are discussed. 8 figures, 6 tables.

  20. Laser annealing of neutron irradiated boron-10 isotope doped diamond

    SciTech Connect

    Jagannadham, K.; Butler, J. E.

    2011-01-01

    10B isotope doped p-type diamond epilayer grown by chemical vapor deposition on (110) oriented type IIa diamond single crystal substrate was subjected to neutron transmutation at a fluence of 2.4 9 1020 thermal and 2.4 9 1020 fast neutrons. After neutron irradiation, the epilayer and the diamond substrate were laser annealed using Nd YAG laser irradiation with wave length, 266 nm and energy, 150 mJ per pulse. The neutron irradiated diamond epilayer and the substrate were characterized before and after laser annealing using different techniques. The characterization techniques include optical microscopy, secondary ion mass spectrometry, X-ray diffraction, Raman, photoluminescence and Fourier Transform Infrared spectroscopy, and electrical sheet conductance measurement. The results indicate that the structure of the irradiation induced amorphous epilayer changes to disordered graphite upon laser annealing. The irradiated substrate retains the (110) crystalline structure with neutron irradiation induced defects.

  1. Phase transformations in neutron-irradiated Zircaloys

    SciTech Connect

    Chung, H.M.

    1986-04-01

    Microstructural evolution in Zircaloy-2 and -4 spent-fuel cladding specimens after approx.3 years of irradiation in commercial power reactors has been investigated by TEM and HVEM. Two kinds of precipitates induced by the fast-neutron irradiation in the reactors have been identified, i.e., Zr/sub 3/O and cubic-ZrO/sub 2/ particles approximately 2 to 10 nm in size. By means of a weak-beam dark-field ''2-1/2D-microscopy'' technique, the bulk nature of the precipitates and the surficial nature of artifact oxide and hydride phases could be discerned. The Zr(Fe/sub x/,Cr/sub 1-x/)/sub 2/ and Zr/sub 2/(Fe/sub x/,Ni/sub 1-x/) intermetallic precipitates normally present in the as-fabricated material virtually dissolved in the spent-fuel cladding specimens after a fast-neutron fluence of approx.4 x 10/sup 21/ ncm/sup -2/ in the power reactors. The observed radiation-induced phase transformations are compared with predictions based on the currently available understanding of the alloy characteristics. 29 refs.

  2. 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

  3. 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.

  4. Neutron Radiography of Irradiated Nuclear Fuel at Idaho National Laboratory

    NASA Astrophysics Data System (ADS)

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

    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 paper 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.

  5. Effect of neutron energy and fluence on deuterium retention behaviour in neutron irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Fujita, Hiroe; Yuyama, Kenta; Li, Xiaochun; Hatano, Yuji; Toyama, Takeshi; Ohta, Masayuki; Ochiai, Kentaro; Yoshida, Naoaki; Chikada, Takumi; Oya, Yasuhisa

    2016-02-01

    Deuterium (D) retention behaviours for 14 MeV neutron irradiated tungsten (W) and fission neutron irradiated W were evaluated by thermal desorption spectroscopy (TDS) to elucidate the correlation between D retention and defect formation by different energy distributions of neutrons in W at the initial stage of fusion reactor operation. These results were compared with that for Fe2+ irradiated W with various damage concentrations. Although dense vacancies and voids within the shallow region near the surface were introduced by Fe2+ irradiation, single vacancies with low concentration were distributed throughout the sample for 14 MeV neutron irradiated W. Only the dislocation loops were introduced by fission neutron irradiation at low neutron fluence. The desorption peak of D for fission neutron irradiated W was concentrated at low temperature region less than 550 K, but that for 14 MeV neutron irradiated W was extended toward the higher temperature side due to D trapping by vacancies. It can be said that the neutron energy distribution could have a large impact on irradiation defect formation and the D retention behaviour.

  6. Analysis of Electron and Antineutrino Energy Spectra from Fissile Samples under Irradiation based on Gross Theory of Beta-decay

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Tachibana, T.; Chiba, S.

    2016-06-01

    We applied the gross theory of β-decay to calculate the reactor electron and antineutrino ({{{bar ν }}{e}}) spectra emitted from 235,238U and 239,241Pu by summing up all the contributions from a large number of decaying fission-products (FPs). We make it clear what kinds of transition types and FP nuclides are important to shape the lepton spectra. After taking the ambiguity in the current data for fission yields and Qβ-values into account, we suggested a possibility that the high-energy part of the widely referred electron-spectra by Schreckenbach et al., almost only one experimental data set available now, might possibly be too low. Arguments on a special role of the odd(Z)-odd(N) nuclides and on the consistency between U-238 and other fissiles in the experimental data lead to the importance of a new and independent measurement of electron energy spectra which could be converted into the reactor {{{bar ν }}{e}} spectra.

  7. Irradiation embrittlement of neutron-irradiated low activation ferritic steels

    NASA Astrophysics Data System (ADS)

    Kayano, H.; Kimura, A.; Narui, M.; Sasaki, Y.; Suzuki, Y.; Ohta, S.

    1988-07-01

    Effects of neutron irradiation and additions of small amounts of alloying elements on the ductile-brittle transition temperature (DBTT) of three different groups of ferritic steels were investigated by means of the Charpy impact test in order to gain an insight into the development of low-activation ferritic steels suitable for the nuclear fusion reactor. The groups of ferritic steels used in this study were (1) basic 0-5% Cr ferritic steels, (2) low-activation ferritic steels which are FeCrW steels with additions of small amounts of V, Mn, Ta, Ti, Zr, etc. and (3) FeCrMo, Nb or V ferritic steels for comparison. In Fe-0-15% Cr and FeCrMo steels, Fe-3-9% Cr steels showed minimum brittleness and provided good resistance against irradiation embrittlement. Investigations on the effects of additions of trace amounts of alloying elements on the fracture toughness of low-activation ferritic steels made clear the optimum amounts of each alloying element to obtain higher toughness and revealed that the 9Cr-2W-Ta-Ti-B ferritic steel showed the highest toughness. This may result from the refinement of crystal grains and improvement of quenching characteristics caused by the complex effect of Ti and B.

  8. Neutron Flux Characterization of Irradiation Holes for Irradiation Test at HANARO

    NASA Astrophysics Data System (ADS)

    Yang, Seong Woo; Cho, Man Soon; Choo, Kee Nam; Park, Sang Jun

    2016-02-01

    The High flux Advanced Neutron Application ReactOr (HANARO) is a unique research reactor in the Republic of Korea, and has been used for irradiation testing since 1998. To conduct irradiation tests for nuclear materials, the irradiation holes of CT and OR5 have been used due to a high fast-neutron flux. Because the neutron flux must be accurately calculated to evaluate the neutron fluence of irradiated material, it was conducted using MCNP. The neutron flux was measured using fluence monitor wires to verify the calculated result. Some evaluations have been conducted, however, more than 20% errors have frequently occurred at the OR irradiation hole, while a good agreement between the calculated and measured data was shown at the CT irradiation hole.

  9. Proton and neutron irradiation effect of Ti: Sapphires

    SciTech Connect

    Wang, G.; Zhang, J.; Yang, J.

    1999-07-01

    Various effects of proton and neutron irradiated Ti: sapphires were studied. Proton irradiation induced F, F{sup +} and V center in Ti: sapphires and 3310 cm{sup -1} infrared absorption, and made ultraviolet absorption edge shift to short wave. Neutron irradiation produced a number of F, F{sup +} and F{sub 2} centers and larger defects in Ti: sapphires, and changed Ti{sup 4+}into Ti{sup 3+} ions. Such valence state variation enhanced characteristic luminescence of Ti: sapphires, and no singular variances of intrinsic fluorescence spectra of Ti: sapphires took place with neutron flux of 1 x 10{sup 17}n/cm{sup 2}, but the fluorescence vanished with neutron flux of 1 x 10{sup 18}n/cm{sup 2} which means the threshold for the concentration of improving Ti{sup 3+} ions by neutron irradiation.

  10. Properties of polymers after cryogenic neutron irradiation

    NASA Astrophysics Data System (ADS)

    Tucker, D. S.; Clinard, F. W.; Hurley, G. F.; Fowler, J. D.

    1985-08-01

    Organic matrix insulation has been specified for use in fusion reactor superconducting coils due to lower material and fabrication costs compared to other forms of insulation. Glass fabric filled resins are prime candidates since they provide not only electrical insulation, but also the mechanical strength necessary to withstand the high magnetic forces present during coil operation. Two epoxy- and two polyimide-based fiber reinforced materials were irradiated to neutron fluences of 4.1 × 10 21n/m 2, E > 0.1 MeV at 4.2 K. Post-irradiation testing included flexural (3 pt. bend), as well as DC conductivity and dielectric breakdown strength. Measurements were made at 77 K and 300 K. Flexural strength was observed to decrease for the epoxy-based materials while the polyimide-based materials exhibited essentially no change in strength. Both DC conductivity and dielectric breakdown strength revealed little or no pattern of degradation at all levels of radiation exposure.

  11. Weldability of neutron irradiated austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Asano, Kyoichi; Nishimura, Seiji; Saito, Yoshiaki; Sakamoto, Hiroshi; Yamada, Yuji; Kato, Takahiko; Hashimoto, Tsuneyuki

    1999-01-01

    Degradation of weldability in neutron irradiated austenitic stainless steel is an important issue to be addressed in the planning of proactive maintenance of light water reactor core internals. In this work, samples selected from reactor internal components which had been irradiated to fluence from 8.5 × 10 22 to 1.4 × 10 26 n/m 2 ( E > 1 MeV) corresponding to helium content from 0.11 to 103 appm, respectively, were subjected to tungsten inert gas arc (TIG) welding with heat input ranged 0.6-16 kJ/cm. The weld defects were characterized by penetrant test and cross-sectional metallography. The integrity of the weld was better when there were less helium and at lower heat input. Tensile properties of weld joint containing 0.6 appm of helium fulfilled the requirement for unirradiated base metal. Repeated thermal cycles were found to be very hazardous. The results showed the combination of material helium content and weld heat input where materials can be welded with little concern to invite cracking. Also, the importance of using properly selected welding procedures to minimize thermal cycling was recognized.

  12. Characterization of neutron calibration fields at the TINT's 50 Ci americium-241/beryllium neutron irradiator

    NASA Astrophysics Data System (ADS)

    Liamsuwan, T.; Channuie, J.; Ratanatongchai, W.

    2015-05-01

    Reliable measurement of neutron radiation is important for monitoring and protection in workplace where neutrons are present. Although Thailand has been familiar with applications of neutron sources and neutron beams for many decades, there is no calibration facility dedicated to neutron measuring devices available in the country. Recently, Thailand Institute of Nuclear Technology (TINT) has set up a multi-purpose irradiation facility equipped with a 50 Ci americium-241/beryllium neutron irradiator. The facility is planned to be used for research, nuclear analytical techniques and, among other applications, calibration of neutron measuring devices. In this work, the neutron calibration fields were investigated in terms of neutron energy spectra and dose equivalent rates using Monte Carlo simulations, an in-house developed neutron spectrometer and commercial survey meters. The characterized neutron fields can generate neutron dose equivalent rates ranging from 156 μSv/h to 3.5 mSv/h with nearly 100% of dose contributed by neutrons of energies larger than 0.01 MeV. The gamma contamination was less than 4.2-7.5% depending on the irradiation configuration. It is possible to use the described neutron fields for calibration test and routine quality assurance of neutron dose rate meters and passive dosemeters commonly used in radiation protection dosimetry.

  13. Spectroscopic study of lithium oxide irradiated by fast neutrons

    NASA Astrophysics Data System (ADS)

    Masaki, N. M.; Noda, K.; Watanabe, H.; Clemmer, R. G.; Hollenberg, G. W.

    1994-09-01

    Lithium oxide (Li 2O) is a candidate material for solid breeder blankets in d-t fusion reactors. Radiation damage in Li 2O was investigated in IEA BEATRIX-II phase 1 irradiation tests using the Fast Flux Test Facility (FFTF). Li 2O single crystal specimens with various 6Li concentrations, 6Li/( 6Li + 7Li), were irradiated at about 650 K for 300 effective full power days in FFTF by fast neutrons (the fast neutron fluence) ( > 0.1 MeV): 3.9 × 10 26 n/m 2). After the neutron-irradiation, measurements of electron-spin resonance (ESR) and optical absorption were carried out for the specimens at room temperature. From the measurements, colloidal lithium metal was found to be formed in Li 2O irradiated with fast neutrons.

  14. A separation of protactinium from neutron-irradiated thorium.

    PubMed

    Lyle, S J; Shendrikar, A D

    1966-01-01

    A convenient-method, based on liquid-liquid extraction with N-benzoyl-N-phenylhydroxylamine in chloroform, is given for the separation of protactinium-233 from neutron-irradiated thorium. PMID:18959855

  15. PROCESSING OF NEUTRON-IRRADIATED URANIUM

    DOEpatents

    Hopkins, H.H. Jr.

    1960-09-01

    An improved "Purex" process for separating uranium, plutonium, and fission products from nitric acid solutions of neutron-irradiated uranium is offered. Uranium is first extracted into tributyl phosphate (TBP) away from plutonium and fission products after adjustment of the acidity from 0.3 to 0.5 M and heating from 60 to 70 deg C. Coextracted plutonium, ruthenium, and fission products are fractionally removed from the TBP by three scrubbing steps with a 0.5 M nitric acid solution of ferrous sulfamate (FSA), from 3.5 to 5 M nitric acid, and water, respectively, and the purified uranium is finally recovered from the TBP by precipitation with an aqueous solution of oxalic acid. The plutonium in the 0.3 to 0.5 M acid solution is oxidized to the tetravalent state with sodium nitrite and extracted into TBP containing a small amount of dibutyl phosphate (DBP). Plutonium is then back-extracted from the TBP-DBP mixture with a nitric acid solution of FSA, reoxidized with sodium nitrite in the aqueous strip solution obtained, and once more extracted with TBP alone. Finally the plutonium is stripped from the TBP with dilute acid, and a portion of the strip solution thus obtained is recycled into the TBPDBP for further purification.

  16. Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites

    SciTech Connect

    Newsome G, Snead L, Hinoki T, Katoh Y, Peters D

    2007-03-26

    The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon{trademark} Type-S, Hi-Nicalon{trademark} or Sylramic{trademark} fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) at 300, 500 and 800 C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing. Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon{trademark} Type-S, while composites reinforced with Hi-Nicalon{trademark} or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential reduction is not known.

  17. Neutron and gamma irradiation damage to organic materials.

    SciTech Connect

    White, Gregory Von, II; Bernstein, Robert

    2012-04-01

    This document discusses open literature reports which investigate the damage effects of neutron and gamma irradiation on polymers and/or epoxies - damage refers to reduced physical chemical, and electrical properties. Based on the literature, correlations are made for an SNL developed epoxy (Epon 828-1031/DDS) with an expected total fast-neutron fluence of {approx}10{sup 12} n/cm{sup 2} and a {gamma} dosage of {approx}500 Gy received over {approx}30 years at < 200 C. In short, there are no gamma and neutron irradiation concerns for Epon 828-1031/DDS. To enhance the fidelity of our hypotheses, in regards to radiation damage, we propose future work consisting of simultaneous thermal/irradiation (neutron and gamma) experiments that will help elucidate any damage concerns at these specified environmental conditions.

  18. Neutron and gamma irradiation effects on power semiconductor switches

    NASA Technical Reports Server (NTRS)

    Schwarze, G. E.; Frasca, A. J.

    1990-01-01

    The performance characteristics of high power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

  19. Neutron and gamma irradiation effects on power semiconductor switches

    NASA Technical Reports Server (NTRS)

    Schwarze, G. E.; Frasca, A. J.

    1990-01-01

    The performance characteristics of high-power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

  20. Neutron and gamma irradiation effects on power semiconductor switches

    SciTech Connect

    Schwarze, G.E.; Frasca, A.J.

    1994-09-01

    The performance characteristics of high power semiconductor switches subjected to high levels of neutron fluence and gamma dose must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect the electrical and switching characteristics of solid state power switches is discussed. The experimental measurement system and radiation facilities are described. Experimental data showing the effects of neutron and gamma irradiation on the performance characteristics are given for power-type NPN Bipolar Junction Transistors (BJTs), and Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). BJTs show a rapid decrease in gain, blocking voltage, and storage time for neutron irradiation, and MOSFETs show a rapid decrease in the gate threshold voltage for gamma irradiation.

  1. Neutron flux assessment of a neutron irradiation facility based on inertial electrostatic confinement fusion.

    PubMed

    Sztejnberg Gonçalves-Carralves, M L; Miller, M E

    2015-12-01

    Neutron generators based on inertial electrostatic confinement fusion were considered for the design of a neutron irradiation facility for explanted organ Boron Neutron Capture Therapy (BNCT) that could be installed in a health care center as well as in research areas. The chosen facility configuration is "irradiation chamber", a ~20×20×40 cm(3) cavity near or in the center of the facility geometry where samples to be irradiated can be placed. Neutron flux calculations were performed to study different manners for improving scattering processes and, consequently, optimize neutron flux in the irradiation position. Flux distributions were assessed through numerical simulations of several models implemented in MCNP5 particle transport code. Simulation results provided a wide spectrum of combinations of net fluxes and energy spectrum distributions. Among them one can find a group that can provide thermal neutron fluxes per unit of production rate in a range from 4.1·10(-4) cm(-2) to 1.6·10(-3) cm(-2) with epithermal-to-thermal ratios between 0.3% and 13% and fast-to-thermal ratios between 0.01% to 8%. Neutron generators could be built to provide more than 10(10) n s(-1) and, consequently, with an arrangement of several generators appropriate enough neutron fluxes could be obtained that would be useful for several BNCT-related irradiations and, eventually, for clinical practice. PMID:26122974

  2. 49 CFR 173.420 - Uranium hexafluoride (fissile, fissile excepted and non-fissile).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... uranium hexafluoride; and (iii) withstand the test specified in 10 CFR 71.73(c)(4) without rupture of the... 49 Transportation 2 2012-10-01 2012-10-01 false Uranium hexafluoride (fissile, fissile excepted....420 Uranium hexafluoride (fissile, fissile excepted and non-fissile). (a) In addition to any...

  3. Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source

    SciTech Connect

    Andreani, C.; Pietropaolo, A.; Salsano, A.; Gorini, G.; Tardocchi, M.; Paccagnella, A.; Gerardin, S.; Frost, C. D.; Ansell, S.; Platt, S. P.

    2008-03-17

    The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 10{sup 7}. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays.

  4. Radiation Damage Study in Natural Zircon Using Neutrons Irradiation

    SciTech Connect

    Lwin, Maung Tin Moe; Amin, Yusoff Mohd.; Kassim, Hasan Abu; Mohamed, Abdul Aziz; Karim, Julia Abdul

    2011-03-30

    Changes of atomic displacements in crystalline structure of natural zircon (ZrSiO{sub 4}) can be studied by using neutron irradiation on the surface of zircon and compared the data from XRD measurements before and after irradiation. The results of neutron irradiation on natural zircon using Pneumatic Transfer System (PTS) at PUSPATI TRIGA Research Reactor in the Malaysian Nuclear Agency are discussed in this work. The reactor produces maximum thermal power output of 1 MWatt and the neutron flux of up to 1x10{sup 13} ncm{sup -2}s{sup -1}. From serial decay processes of uranium and thorium radionuclides in zircon crystalline structure, the emission of alpha particles can produce damage in terms of atomic displacements in zircon. Hence, zircon has been extensively studied as a possible candidate for immobilization of fission products and actinides.

  5. Radiation Damage Study in Natural Zircon Using Neutrons Irradiation

    NASA Astrophysics Data System (ADS)

    Lwin, Maung Tin Moe; Amin, Yusoff Mohd.; Kassim, Hasan Abu; Mohamed, Abdul Aziz; Karim, Julia Abdul

    2011-03-01

    Changes of atomic displacements in crystalline structure of natural zircon (ZrSiO4) can be studied by using neutron irradiation on the surface of zircon and compared the data from XRD measurements before and after irradiation. The results of neutron irradiation on natural zircon using Pneumatic Transfer System (PTS) at PUSPATI TRIGA Research Reactor in the Malaysian Nuclear Agency are discussed in this work. The reactor produces maximum thermal power output of 1 MWatt and the neutron flux of up to 1×1013 ncm-2s-1. From serial decay processes of uranium and thorium radionuclides in zircon crystalline structure, the emission of alpha particles can produce damage in terms of atomic displacements in zircon. Hence, zircon has been extensively studied as a possible candidate for immobilization of fission products and actinides.

  6. Neutron irradiation influence on magnesium aluminium spinel inversion

    NASA Astrophysics Data System (ADS)

    Skvortsova, V.; Mironova-Ulmane, N.; Ulmanis, U.

    2002-05-01

    Grown by the Verneuil method MgO · nAl 2O 3 single crystals and natural spinel crystal have been studied using X-ray diffraction and photoluminescence spectra. The fast neutron irradiation of magnesium aluminium spinel leads to the lattice parameter decrease. The bond lengths of Mg-O and Al-O vary with the u-parameter and the lattice parameter. On the other hand, the bond lengths are related with the inversion parameter. Using changes of the lattice parameter during irradiation we have calculated the inversion parameter, which is 15-20%. In the luminescence spectra, the fast neutron radiation (fluence 10 16 cm -2) produces an increase in the intensity ratio of the N- to R-lines by 5-20%. Taking into account that intensity of the N-lines is closely associated with the inversion parameter, it is possible to state that the neutron irradiation causes the increasing of the spinel inversion.

  7. Microstructural development of neutron irradiated W?Re alloys

    NASA Astrophysics Data System (ADS)

    Nemoto, Yoshiyuki; Hasegawa, Akira; Satou, Manabu; Abe, Katsunori

    2000-12-01

    Tungsten (W) alloys are candidate materials to be used as high-heat-flux materials in fusion reactors. In our previous work, W-26 wt% Re showed drastic hardening and embrittlement after the neutron irradiation. In this study, to clarify the irradiation hardening and embrittlement behavior of W-26 wt% Re, from the viewpoint of microstructural development, the microstructure observation of the neutron irradiated W-26 wt% Re was carried out using transmission electron microscope (TEM). The specimens were irradiated at the materials open test assembly of the fast flux test facility (FFTF/MOTA-2A cycle 11) up to ˜1×10 27 n/m2, ( En>0.1 MeV). The irradiation temperatures were 646, 679, 792, 873 and 1073 K. In all neutron irradiated W-26 wt% Re samples, sigma-phase precipitates and chi-phase precipitates were observed, while in the thermally aged specimen, only sigma-phase precipitates were observed. Irradiation effects on microstructural development are discussed.

  8. Defect microstructures in neutron-irradiated copper and stainless steel

    SciTech Connect

    Zinkle, S.J.; Sindelar, R.L.

    1987-09-01

    The defect microstructures of copper and type 304L austenitic stainless steel have been examined following neutron irradiation under widely different conditions. Less than 0.2% of the defect clusters in steel irradiated at 120/sup 0/C with moderated fission neutrons were resolvable as stacking fault tetrahedra (SFT). The fraction of defect clusters identified as SFT in copper varied from approx.10% for a low-dose 14-MeV neutron irradiation at 25/sup 0/C to approx.50% for copper irradiated to 1.3 dpa in a moderated fission spectrum at 182/sup 0/C. The mean cluster size in copper was about 2.6 nm for both cases, despite the large differences in irradiation conditions. The mean defect cluster size in the irradiated steel was about 1.8 nm. The absence of SFT in stainless steel may be due to the generation of 35 appm He during the irradiation, which caused the vacancies to form helium-filled cavities instead of SFT. 20 refs.

  9. Comparison of Deuterium Retention for Ion-irradiated and Neutron-irradiated Tungsten

    SciTech Connect

    Yasuhisa Oya; Masashi Shimada; Makoto Kobayashi; Takuji Oda; Masanori Hara; Hideo Watanabe; Yuji Hatano; Pattrick Calderoni; Kenji Okuno

    2011-12-01

    The behavior of D retention for Fe{sup 2+}-irradiated tungsten with a damage of 0.025-3 dpa was compared with that for neutron-irradiated tungsten with 0.025 dpa. The D{sub 2} thermal desorption spectroscopy (TDS) spectra for Fe{sup 2+}-irradiated tungsten consisted of two desorption stages at 450 and 550 K, while that for neutron-irradiated tungsten was composed of three stages and an addition desorption stage was found at 750 K. The desorption rate of the major desorption stage at 550K increased as the displacement damage increased due to Fe{sup 2+} irradiation increasing. In addition, the first desorption stage at 450K was found only for damaged samples. Therefore, the second stage would be based on intrinsic defects or vacancy produced by Fe{sup 2+} irradiation, and the first stage should be the accumulation of D in mono-vacancy and the activation energy would be relatively reduced, where the dislocation loop and vacancy is produced. The third one was found only for neutron irradiation, showing the D trapping by a void or vacancy cluster, and the diffusion effect is also contributed to by the high full-width at half-maximum of the TDS spectrum. Therefore, it can be said that the D{sub 2} TDS spectra for Fe{sup 2+}-irradiated tungsten cannot represent that for the neutron-irradiated one, indicating that the deuterium trapping and desorption mechanism for neutron-irradiated tungsten is different from that for the ion-irradiated one.

  10. The physics experimental study for in-hospital neutron irradiator

    SciTech Connect

    Li Yiguo; Xia Pu; Zou Shuyun; Zhang Yongbao; Zheng Iv; Zheng Wuqing; Shi Yongqian; Gao Jijin; Zhou Yongmao

    2008-07-15

    MNSRs (Miniature Neutron Source Reactor) are low power research reactors designed and manufactured by China Institute of Atomic Energy (CIAE). MNSRs are mainly used for NAA, training and teaching, testing of nuclear instrumentation. The first MNSR, the prototype MNSR, was put into operation in 1984, later, eight other MNSRs had been built both at home and abroad. For MNSRs, highly enriched uranium (90%) is used as the fuel material. The In-Hospital Neutron Irradiator (IHNI) is designed for Boron Neutron Capture Therapy (BNCT) based on Miniature Neutron Source Reactor(MNSR). On both sides of the reactor core, there are two neutron beams, one is thermal neutron beam, and the other opposite to the thermal beam, is epithermal neutron beam. A small thermal neutron beam is specially designed for the measurement of blood boron concentration by the prompt gamma neutron activation analysis (PGNAA). In this paper, the experimental results of critical mass worth of the top Be reflectors worth of the control rod, neutron flux distribution and other components worth were measured, the experiment was done on the Zero Power Experiment equipment of MNSR. (author)

  11. Fast Neutron Irradiation of the Highly Radioresistant Bacterium Deinococcus Radiodurans

    NASA Astrophysics Data System (ADS)

    Case, Diane Louise

    Fast neutron dose survival curves were generated for the bacterium Deinococcus radiodurans, which is renowned for its unusually high resistance to gamma, x-ray, and ultraviolet radiation, but for which fast neutron response was unknown. The fast neutrons were produced by the University of Massachusetts Lowell 5.5-MV, type CN Van de Graaff accelerator through the ^7Li(p,n)^7 Be reaction by bombarding a thick metallic lithium target with a 4-MeV proton beam. The bacteria were uniformly distributed on 150-mm agar plates and were exposed to the fast neutron beam under conditions of charged particle equilibrium. The plates were subdivided into concentric rings of increasing diameter from the center to the periphery of the plate, within which the average neutron dose was calculated as the product of the precisely known neutron fluence at the average radius of the ring and the neutron energy dependent kerma factor. The neutron fluence and dose ranged from approximately 3 times 1013 n cm^ {-2} to 1 times 1012 n cm^ {-2}, and 200 kilorad to 5 kilorad, respectively, from the center to the periphery of the plate. Percent survival for Deinococcus radiodurans as a function of fast neutron dose was derived from the ability of the irradiated cells to produce visible colonies within each ring compared to that of a nonirradiated control population. The bacterium Escherichia coli B/r (CSH) was irradiated under identical conditions for comparative purposes. The survival response of Deinococcus radiodurans as a result of cumulative fast neutron exposures was also investigated. The quantification of the ability of Deinococcus radiodurans to survive cellular insult from secondary charged particles, which are produced by fast neutron interactions in biological materials, will provide valuable information about damage and repair mechanisms under extreme cellular stress, and may provide new insight into the origin of this bacterium's unprecedented radiation resistance.

  12. Test of radiation hardness of CMOS transistors under neutron irradiation

    SciTech Connect

    Sadrozinski, H.F.W.; Rowe, W.A.; Seiden, A.; Spencer, E.; Hoffman, C.M.; Holtkamp, D.; Kinnison, W.W.; Sommer, W.F. Jr.; Ziock, H.J.

    1989-01-01

    We have tested 2 micron CMOS test structures from various foundries in the LAMPF Beam stop for radiation damage under prolongued neutron irradiation. The fluxes employed covered the region expected to be encountered at the SSC and led to fluences of up to 10/sup 14/ neutrons/cm/sup 2/ in about 500 hrs of running. We show that test structures which have been measured to survive ionizing radiation of the order MRad also survive these high neutron fluences. 5 refs., 4 figs.

  13. Neutron irradiation creep in stainless steel alloys

    NASA Astrophysics Data System (ADS)

    Schüle, Wolfgang; Hausen, Hermann

    1994-09-01

    Irradiation creep elongations were measured in the HFR at Petten on AMCR steels, on 316 CE-reference steels, and on US-316 and US-PCA steels varying the irradiation temperature between 300°C and 500°C and the stress between 25 and 300 MPa. At the beginning of an irradiation a type of "primary" creep stage is observed for doses up to 3-5 dpa after which dose the "secondary" creep stage begins. The "primary" creep strain decreases in cold-worked steel materials with decreasing stress and decreasing irradiation temperature achieving also negative creep strains depending also on the pre-treatment of the materials. These "primary" creep strains are mainly attributed to volume changes due to the formation of radiation-induced phases, e.g. to the formation of α-ferrite below about 400°C and of carbides below about 700°C, and not to irradiation creep. The "secondary" creep stage is found for doses larger than 3 to 5 dpa and is attributed mainly to irradiation creep. The irradiation creep rate is almost independent of the irradiation temperature ( Qirr = 0.132 eV) and linearly dependent on the stress. The total creep elongations normalized to about 8 dpa are equal for almost every type of steel irradiated in the HFR at Petten or in ORR or in EBR II. The negative creep elongations are more pronounced in PCA- and in AMCR-steels and for this reason the total creep elongation is slightly smaller at 8 dpa for these two steels than for the other steels.

  14. Dosimetry in Thermal Neutron Irradiation Facility at BMRR

    SciTech Connect

    Hu, J. P.; Holden, N. E.; Reciniello, R. N.

    2014-05-23

    Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4 - 7

  15. Dosimetry in Thermal Neutron Irradiation Facility at BMRR

    NASA Astrophysics Data System (ADS)

    Hu, J.-P.; Holden, N. E.; Reciniello, R. N.

    2016-02-01

    Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4-7% lower than

  16. Radiation resistance of endohedral metallofullerenols under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Szhogina, A. A.; Shilin, V. A.; Sedov, V. P.; Lebedev, V. T.

    2016-07-01

    The endohedral metallofullerenols Me@C2 n (OH)38-40 + C2 n (OH)38-40 ( Me = Tb, Sc, Gd, Fe, Pr, Mo) have been obtained and their radiation resistance under irradiation by a neutron flux of 8 × 1013 cm-2 s-1 has been studied. The factors affecting the radiation resistance of endohedral metallofullerenols are discussed.

  17. Radiation Damages in Aluminum Alloy SAV-1 under Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Salikhbaev, Umar; Akhmedzhanov, Farkhad; Alikulov, Sherali; Baytelesov, Sapar; Boltabaev, Azizbek

    2016-05-01

    The aim of this work was to study the effect of neutron irradiation on the kinetics of radiation damages in the SAV-1 alloy, which belongs to the group of aluminum alloys of the ternary system Al-Mg-Si. For fast-neutron irradiation by different doses up to fluence 1019 cm-2 the SAV-1 samples were placed in one of the vertical channels of the research WWR type reactor (Tashkent). The temperature dependence of the electrical resistance of the alloy samples was investigated in the range 290 - 490 K by the four-compensation method with an error about 0.1%. The experimental results were shown that at all the temperatures the dependence of the SAV-1 alloy resistivity on neutron fluence was nonlinear. With increasing neutron fluence the deviation from linearity and the growth rate of resistivity with temperature becomes more appreciable. The observed dependences are explained by means of martensitic transformations and the radiation damages in the studied alloy under neutron irradiation. The mechanisms of radiation modification of the SAV-1 alloy structure are discussed.

  18. Radioisotopes produced by neutron irradiation of food.

    PubMed

    Albright, S; Seviour, R

    2016-04-01

    The use of neutrons for cargo interrogation has the potential to drastically improve threat detection. Previous research has focussed on the production of (24)Na, based on the isotopes produced in pharmaceuticals and medical devices. For both the total activity and the ingestion dose we show that a variety of isotopes contribute and that (24)Na is only dominant under certain conditions. The composition of the foods has a strong influence on the resulting activity and ingestion dose suggesting that the pharmaceuticals and medical devices considered initially are not a viable analogue for foodstuffs. There is an energy dependence to the isotopes produced due to the cross-sections of different reactions varying with neutron energy. We show that this results in different isotopes dominating the ingestion dose at different energies, which has not been considered in the previous literature. PMID:26749562

  19. SPECTER: neutron damage calculations for materials irradiations

    SciTech Connect

    Greenwood, L.R.; Smither, R.K.

    1985-01-01

    Neutron displacement damage-energy cross sections have been calculated for 41 isotopes in the energy range from 10/sup -10/ to 20 MeV. Calculations were performed on a 100-point energy grid using nuclear cross sections from ENDF/B-V and the DISCS computer code. Elastic scattering is treated exactly including angular distributions from ENDF/B-V. Inelastic scattering calculations consider both discrete and continuous nuclear level distributions. Multiple (n,xn) reactions use a Monte Carlo technique to derive the recoil distributions. The (n,d) and (n,t) reactions are treated as (n,p) and (n,/sup 3/He) as (n,/sup 4/He). The (n,..gamma..) reaction and subsequent ..beta..-decay are also included, using a new treatment of ..gamma..-..gamma.. coincidences, angular correlations, ..beta..-neutrino correlations, and the incident neutron energy. The Lindhard model was used to compute the energy available for nuclear displacement at each recoil energy. The SPECTER computer code has been developed to simplify damage calculations. The user need only specify a neutron energy spectrum. SPECTER will then calculate spectral-averaged displacements, recoil spectra, gas production, and total damage energy (Kerma). The SPECTER computer code package is readily accessible to the fusion community via the National Magnetic Fusion Energy Computer Center (NMFECC) at Lawrence Livermore National laboratory.

  20. Retention of Hydrogen Isotopes in Neutron Irradiated Tungsten

    SciTech Connect

    Yuji Hatano; Masashi Shimada; Yasuhisa Oya; Guoping Cao; Makoto Kobayashi; Masanori Hara; Brad J. Merrill; Kenji Okuno; Mikhail A. Sokolov; Yutai Katoh

    2013-03-01

    To investigate the effects of neutron irradiation on hydrogen isotope retention in tungsten, disk-type specimens of pure tungsten were irradiated in the High Flux Isotope Reactor in Oak Ridge National Laboratory followed by exposure to high flux deuterium (D) plasma in Idaho National Laboratory. The results obtained for low dose n-irradiated specimens (0.025 dpa for tungsten) are reviewed in this paper. Irradiation at coolant temperature of the reactor (around 50 degrees C) resulted in the formation of strong trapping sites for D atoms. The concentrations of D in n-irradiated specimens were ranging from 0.1 to 0.4 mol% after exposure to D plasma at 200 and 500 degrees C and significantly higher than those in non-irradiated specimens because of D-trapping by radiation defects. Deep penetration of D up to a depth of 50-100 µm was observed at 500 degrees C. Release of D in subsequent thermal desorption measurements continued up to 900 degrees C. These results were compared with the behaviour of D in ion-irradiated tungsten, and distinctive features of n-irradiation were discussed.

  1. Positron annihilation in neutron irradiated iron-based materials

    NASA Astrophysics Data System (ADS)

    Lambrecht, M.; Almazouzi, A.

    2011-01-01

    The hardening and embrittlement of reactor pressure vessel steels is of great concern in the actual nuclear power plant life assessment. This embrittlement is caused by irradiation-induced damage, like vacancies, interstitials, solutes and their clusters. But the reason for the embrittlement of the material is not yet totally known. The real nature of the irradiation damage should thus be examined as well as its evolution in time. Positron annihilation spectroscopy has been shown to be a powerful method for analyzing some of these defects. In fact, both vacancy type clusters and precipitates can be visualized by positrons. Recently, at SCK·CEN, a new setup has been constructed, calibrated and optimized to measure the coincidence Doppler broadening and lifetime of neutron irradiated materials. To be able to compare the results obtained by the positron studies, with those of other techniques (such as transmission electron microscopy, atom probe tomography and small angle neutron scattering), quantitative estimations of the size and density of the annihilation sites are needed. Using the approach proposed by Vehanen et al., an attempt is made to calculate the needed quantities in Fe and Fe-Cu binary alloys that were neutron irradiated to different doses. The results obtained are discussed highlighting the difficulties in defining the annihilation centres even in these simple model alloys, in spite of using both lifetime and Doppler broadening measurements in the same samples.

  2. Use of delayed gamma rays for active non-destructive assay of 235U irradiated by pulsed neutron source (plasma focus)

    NASA Astrophysics Data System (ADS)

    Andola, Sanjay; Niranjan, Ram; Kaushik, T. C.; Rout, R. K.; Kumar, Ashwani; Paranjape, D. B.; Kumar, Pradeep; Tomar, B. S.; Ramakumar, K. L.; Gupta, S. C.

    2014-07-01

    A pulsed neutron source based on plasma focus device has been used for active interrogation and assay of 235U by monitoring its delayed high energy γ-rays. The method involves irradiation of fissile material by thermal neutrons obtained after moderation of a burst of neutrons emitted upon fusion of deuterium in plasma focus (PF) device. The delayed gamma rays emitted from the fissile material as a consequence of induced fission were detected by a large volume sodium iodide (NaI(Tl)) detector. The detector is coupled to a data acquisition system of 2k input size with 2k ADC conversion gain. Counting was carried out in pulse height analysis mode for time integrated counts up to 100 s while the temporal profile of delayed gamma has been obtained by counting in multichannel scaling mode with dwell time of 50 ms. To avoid the effect of passive (natural) and active (from surrounding materials) backgrounds, counts have been acquired for gamma energy between 3 and 10 MeV. The lower limit of detection of 235U in the oxide samples with this set-up is estimated to be 14 mg.

  3. Cation disorder in high-dose, neutron-irradiated spinel

    SciTech Connect

    Sickafus, K.E.; Larson, A.C.; Yu, N.

    1995-04-01

    The objective of this effort is to determine whether MgAl{sub 2}O{sub 4} spinel is a suitable ceramic for fusion applications. The crystal structures of MgAl{sub 2}O{sub 4} spinel single crystals irradiated to high neutron fluences [>5{times}10{sup 26} n/m{sup 2} (E{sub n}>0.1 MeV)] were examined by neutron diffraction. Crystal structure refinement of the highese dose sample indicated that the average scattering strength of the tetrahedral crystal sites decreased by {approx}20% while increasing by {approx}8% on octahedral sites.

  4. Precipitate stability in neutron-irradiated Zircaloy-4

    NASA Astrophysics Data System (ADS)

    Yang, W. J. S.

    1988-09-01

    Zircaloy-4, a zirconium-base alloy used extensively as cladding and core structural materials in water-cooled nuclear reactors, was examined by transmission electron microscopy, after neutron irradiation and postirradiation annealing. Phase instabilities found during irradiation at 561 K include the amorphous transformation and the dissolution of the intermetallic Zr(Fe,Cr) 2. The α-matrix is driven toward a single phase solid solution as the neutron fluence increases. This is evidenced by the continuous dissolution of the precipitate without precipitation of any new phase during irradiation. During postirradiation annealing at 833 K, solute Fe precipitates out particularly at the grain boundaries as Zr-Fe zeta-phase. Recrystallization of the amorphous precipitates occurs at a postirradiation annealing temperature of 1023 K. In general, the observed phenomena of amorphous transformation, precipitate dissolution, reprecipitation and recrystallization reflect the complex solute-point defect interactions in the α-matrix. The continuous solute dissolution during irradiation is expected to have a potential effect on irradiation growth, creep and corrosion properties of the alloy.

  5. Neutron irradiation and compatibility testing of Li 2O

    NASA Astrophysics Data System (ADS)

    Porter, D. L.; Krsul, J. R.; Laug, M. T.; Walters, L. C.; Tetenbaum, M.

    1984-05-01

    A study was made of the neutron irradiation behavior of 6Li-enriched Li 2O in EBR-II. In addition, a stress corrosion study was performed ex-reactor to test the compatibility of Li 2O with a variety of stainless steels. The irradiation tests showed that tritium and helium retention in the Li 2O (˜ 89% dense) lessened with neutron exposure, and the retentions appear to approach a steady-state after ˜ 1% 6Li burnup. The stress corrosion studies, using 316 stainless steel (Ti-modified) and a 35% Ni alloy, showed that stress does not enhance the corrosion, and that dry Li 2O is not significantly corrosive, the LiOH content producing the corrosive effects. Corrosion, in general, was not severe because a passivation in sealed capsules seemed to occur after a time which greatly reduced corrosion rates.

  6. Elastic stability of high dose neutron irradiated spinel

    SciTech Connect

    Li, Z.; Chan, S.K.; Garner, F.A.

    1995-04-01

    The objective of this effort is to identify ceramic materials that are suitable for fusion reactor applications. Elastic constants (C{sub 11}, C{sub 12}, and C{sub 44}) of spinel (MgAl{sub 2}O{sub 4}) single crystals irradiated to very high neutron fluences have geen measured by an ultrasonic technique. Although results of a neutron diffraction study show that cation occupation sites are significantly changed in the irradiated samples, no measurable differences occurred in their elastic properties. In order to understand such behavior, the elastic properties of a variety of materials with either normal or inverse spinel structures were studied. The cation valence and cation distribution appear to have little influence on the elastic properties of spinel materials.

  7. Fast neutron irradiation for advanced tumors in the pelvis

    SciTech Connect

    Battermann, J.J.; Breur, K.

    1981-08-01

    Since the end of 1975, fast neutron irradiation has been used in the Antoni van Leeuwenhoek Hospital for the treatment of advanced tumors, which had no prospect of cure by other treatment modalities. Fifty-nine patients were irradiated in the pelvic area, 22 for inoperable bladder cancer, 25 for rectal and 12 for gynecological cancer. Treatments were given 5 times per week with a 14 MeV d + T neutron generator. Persisting complete tumor regression was achieved in 11 of 22 bladded patients, 14 of 25 rectum patients and 6 of 12 gynecological patients. Because of unfavorable beam characteristics, 15 of 59 (25%) treated patients had severe radiation-induced intestinal and skin complications.

  8. Development of positron annihilation spectroscopy for characterizing neutron irradiated tungsten

    SciTech Connect

    C.N. Taylor; M. Shimada; D.W. Akers; M.W. Drigert; B.J. Merrill; Y. Hatano

    2013-05-01

    Tungsten samples (6 mm diameter, 0.2 mm thick) were irradiated to 0.025 and 0.3 dpa with neutrons in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Samples were then exposed to deuterium plasma in the tritium plasma experiment (TPE) at 100, 200 and 500ºC to a total fluence of 1 x 1026 m-2. Nuclear reaction analysis (NRA) and Doppler broadening positron annihilation spectroscopy (DB-PAS) were performed at various stages to characterize damage and retention. We present the first known results of neutron damaged tungsten characterized by DB-PAS in order to study defect concentration. Two positron sources, 22Na and 68Ge, probe ~58 µm and through the entire 200 µm thick samples, respectively. DB-PAS results reveal clear differences between the various irradiated samples. These results, and the calibration of DB-PAS to NRA data are presented.

  9. Evaluation of weld crack susceptibility for neutron irradiated stainless steels

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Kohyama, A.; Hirose, T.; Narui, M.

    In order to clarify the mechanisms of weld cracking, especially for heat affected zone cracking in heavily neutron irradiated stainless steels and to establish a measure to evaluate crack susceptibility, a mini-sized Varestraint (variable restraint) test machine for hot laboratory operation was designed and fabricated. This unique PIE facility was successfully applied in the hot laboratory of IMR Oarai Branch of Tohoku University. The maximum restraint applied was 4% at the surface of the specimen. Specimen surface morphology and specimen microstructures were inspected by video microscope, SEM and TEM. Under the 2% surface restraint condition, clear formation of heat affected zone (HAZ) crack was observed for the case of neutron irradiation to produce 0.5 appm He and of 2.4 kJ heat input by TIG.

  10. Interpretation of infrared data in neutron-irradiated silicon

    SciTech Connect

    Londos, C.A.; Georgiou, G.I.; Fytros, L.G. ); Papastergiou, K. )

    1994-10-15

    Czochralski-grown Si samples were irradiated by fast neutrons, at room temperature, with the aim of studying the identity of the defects produced, using infrared spectroscopy. Two localized vibrational modes at 914 and 1000 cm[sup [minus]1] were considered as intermediate defect stages between VO and VO[sub 2] complexes. We express the view that they may arise from a [VO+O[sub [ital i

  11. Neutron irradiation effects on high Nicalon silicon carbide fibers

    SciTech Connect

    Osborne, M.C.; Steiner, D.; Snead, L.L.

    1996-10-01

    The effects of neutron irradiation on the mechanical properties and microstructure of SiC and SiC-based fibers is a current focal point for the development of radiation damage resistant SiC/SiC composites. This report discusses the radiation effects on the Nippon Carbon Hi-Nicalon{trademark} fiber system and also discusses an erratum on earlier results published by the authors on this material. The radiation matrix currently under study is also summarized.

  12. Photofission Analysis for Fissile Dosimeters Dedicated to Reactor Pressure Vessel Surveillance

    NASA Astrophysics Data System (ADS)

    Bourganel, Stéphane; Faucher, Margaux; Thiollay, Nicolas

    2016-02-01

    Fissile dosimeters are commonly used in reactor pressure vessel surveillance programs. In this paper, the photofission contribution is analyzed for in-vessel 237Np and 238U fissile dosimeters in French PWR. The aim is to reassess this contribution using recent tools (the TRIPOLI-4 Monte Carlo code) and latest nuclear data (JEFF3.1.1 and ENDF/B-VII nuclear libraries). To be as exhaustive as possible, this study is carried out for different configurations of fissile dosimeters, irradiated inside different kinds of PWR: 900 MWe, 1300 MWe, and 1450 MWe. Calculation of photofission rate in dosimeters does not present a major problem using the TRIPOLI-4® Monte Carlo code and the coupled neutron-photon simulation mode. However, preliminary studies were necessary to identify the origin of photons responsible of photofissions in dosimeters in relation to the photofission threshold reaction (around 5 MeV). It appears that the main contribution of high enough energy photons generating photofissions is the neutron inelastic scattering in stainless steel reactor structures. By contrast, 137Cs activity calculation is not an easy task since photofission yield data are known with high uncertainty.

  13. Neutron irradiation facilities for fission and fusion reactor materials studies

    SciTech Connect

    Rowcliffe, A.F.

    1985-01-01

    The successful development of energy-conversion machines based upon nuclear fission or fusion reactors is critically dependent upon the behavior of the engineering materials used to construct the full containment and primary heat extraction systems. The development of radiation damage-resistant materials requires irradiation testing facilities which reproduce, as closely as possible, the thermal and neutronic environment expected in a power-producing reactor. The Oak Ridge National Laboratory (ORNL) reference core design for the Center for Neutron Research (CNR) reactor provides for instrumented facilities in regions of both hard and mixed neutron spectra, with substantially higher fluxes than are currently available. The benefits of these new facilities to the development of radiation damage resistant materials are discussed in terms of the major US fission and fusion reactor programs.

  14. Automated pneumatic transfer irradiation system for delayed neutron counting

    SciTech Connect

    Heifer, Paul G.; Millard, Hugh T. Jr.; Zermane, Albert J

    1982-07-01

    The Geological Survey TRIGA Reactor has been used for uranium and thorium neutron activation analysis by delayed neutron counting for the past eleven years. As the requirements for analysis increased the original General Atomic pneumatic system was upgraded in several stages. By 1979 we had reached the practical limits of safe through-put for that system and a new pneumatic transfer system was built. A single large Roots type blower is used to drive four individual transfer tubes simultaneously (two termini in the core and two outside the reflector). A microprocessor controls the operation and is paced by a minicomputer, which is also used to collect and reduce the counting data. Two irradiations and counting cycles are performed on each sample, one in the core, a Cd-lined terminus for thorium, and one in the reflector mounted terminus for uranium. Video displays at both the reactor console and the pneumatic system operating station indicate the status of the system and the locations of the samples at all times. This highly automated system is capable of 1,200 irradiations for delayed neutron counting in a 10 hour day, and, in addition, incorporates programmable versatility for other irradiation-counting experiments, and provides a high degree of reactor and radiological safety with only remote operator attention. (author)

  15. Development of positron annihilation spectroscopy for characterizing neutron irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Taylor, C. N.; Shimada, M.; Merrill, B. J.; Drigert, M. W.; Akers, D. W.; Hatano, Y.

    2014-04-01

    Tungsten samples (6 mm diameter and 0.2 mm thick) were irradiated to 0.025 and 0.3 dpa with neutrons in the High Flux Isotope Reactor at Oak Ridge National Laboratory as part of the US/Japan Tritium, Irradiation and Thermofluids for America and Nippon (TITAN) collaboration. Samples were then exposed to deuterium plasma in Idaho National Laboratory's Tritium Plasma Experiment at 100, 200 and 500 °C to a total fluence of 1 × 1026 m-2. Nuclear reaction analysis (NRA) and Doppler broadening positron annihilation spectroscopy (DB-PAS) were performed at various stages to characterize radiation damage and retention. We present the first results of neutron irradiated tungsten characterized by DB-PAS in order to study defect concentration. Two positron sources, 22Na and 68Ge, probe ˜58 μm and through the entire 200 μm thick samples, respectively. DB-PAS results reveal clear differences between the various irradiated samples. These results, and a correlation between DB-PAS and NRA data, are presented.

  16. Neutron irradiation of superconductors and damage energy scaling of different neutron spectra

    NASA Astrophysics Data System (ADS)

    Hahn, P. A.; Weber, H. W.; Guinan, M. W.; Birtcher, R. C.; Brown, B. S.; Greenwood, L. R.

    1985-08-01

    Three different neutron sources were used to irradiate identical sets of NbTi superconductors up to about half the lifetime dose of a superconducting magnet in a fusion reactor. Based on a careful source characterization of the TRIGA Mark-II reactor in Vienna, the spallation neutron source IPNS at Argonne and the 14 MeV neutron source RTNS-II at Livermore, the damage energy cross sections were calculated for four different types of NbTi alloys (42, 46.5, 49 and 54 wt % Ti). The experimental results on the variations of critical current densities j sub c with neutron dose are found to scale within the experimental uncertainties with the appropriate damage energy cross sections. This first explicit proof of damage energy scaling for j sub c-variations in superconductors is considered to be most valuable for the evaluation of radiation damage in superconductors under fusion reactor conditions.

  17. 49 CFR 173.420 - Uranium hexafluoride (fissile, fissile excepted and non-fissile).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Uranium hexafluoride (fissile, fissile excepted and non-fissile). 173.420 Section 173.420 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS REGULATIONS SHIPPERS-GENERAL REQUIREMENTS...

  18. Fusion-Fission Hybrid for Fissile Fuel Production without Processing

    SciTech Connect

    Fratoni, M; Moir, R W; Kramer, K J; Latkowski, J F; Meier, W R; Powers, J J

    2012-01-02

    Two scenarios are typically envisioned for thorium fuel cycles: 'open' cycles based on irradiation of {sup 232}Th and fission of {sup 233}U in situ without reprocessing or 'closed' cycles based on irradiation of {sup 232}Th followed by reprocessing, and recycling of {sup 233}U either in situ or in critical fission reactors. This study evaluates a third option based on the possibility of breeding fissile material in a fusion-fission hybrid reactor and burning the same fuel in a critical reactor without any reprocessing or reconditioning. This fuel cycle requires the hybrid and the critical reactor to use the same fuel form. TRISO particles embedded in carbon pebbles were selected as the preferred form of fuel and an inertial laser fusion system featuring a subcritical blanket was combined with critical pebble bed reactors, either gas-cooled or liquid-salt-cooled. The hybrid reactor was modeled based on the earlier, hybrid version of the LLNL Laser Inertial Fusion Energy (LIFE1) system, whereas the critical reactors were modeled according to the Pebble Bed Modular Reactor (PBMR) and the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) design. An extensive neutronic analysis was carried out for both the hybrid and the fission reactors in order to track the fuel composition at each stage of the fuel cycle and ultimately determine the plant support ratio, which has been defined as the ratio between the thermal power generated in fission reactors and the fusion power required to breed the fissile fuel burnt in these fission reactors. It was found that the maximum attainable plant support ratio for a thorium fuel cycle that employs neither enrichment nor reprocessing is about 2. This requires tuning the neutron energy towards high energy for breeding and towards thermal energy for burning. A high fuel loading in the pebbles allows a faster spectrum in the hybrid blanket; mixing dummy carbon pebbles with fuel pebbles enables a softer spectrum in the critical reactors

  19. 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.

    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.

  20. 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.

    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.

  1. Thermal neutron irradiation field design for boron neutron capture therapy of human explanted liver.

    PubMed

    Bortolussi, S; Altieri, S

    2007-12-01

    The selective uptake of boron by tumors compared to that by healthy tissue makes boron neutron capture therapy (BNCT) an extremely advantageous technique for the treatment of tumors that affect a whole vital organ. An example is represented by colon adenocarcinoma metastases invading the liver, often resulting in a fatal outcome, even if surgical resection of the primary tumor is successful. BNCT can be performed by irradiating the explanted organ in a suitable neutron field. In the thermal column of the Triga Mark II reactor at Pavia University, a facility was created for this purpose and used for the irradiation of explanted human livers. The neutron field distribution inside the organ was studied both experimentally and by means of the Monte Carlo N-particle transport code (MCNP). The liver was modeled as a spherical segment in MCNP and a hepatic-equivalent solution was used as an experimental phantom. In the as-built facility, the ratio between maximum and minimum flux values inside the phantom ((phi(max)/phi(min)) was 3.8; this value can be lowered to 2.3 by rotating the liver during the irradiation. In this study, the authors proposed a new facility configuration to achieve a uniform thermal neutron flux distribution in the liver. They showed that a phi(max)/phi(min) ratio of 1.4 could be obtained without the need for organ rotation. Flux distributions and dose volume histograms were reported for different graphite configurations. PMID:18196797

  2. Thermal neutron irradiation field design for boron neutron capture therapy of human explanted liver

    SciTech Connect

    Bortolussi, S.; Altieri, S.

    2007-12-15

    The selective uptake of boron by tumors compared to that by healthy tissue makes boron neutron capture therapy (BNCT) an extremely advantageous technique for the treatment of tumors that affect a whole vital organ. An example is represented by colon adenocarcinoma metastases invading the liver, often resulting in a fatal outcome, even if surgical resection of the primary tumor is successful. BNCT can be performed by irradiating the explanted organ in a suitable neutron field. In the thermal column of the Triga Mark II reactor at Pavia University, a facility was created for this purpose and used for the irradiation of explanted human livers. The neutron field distribution inside the organ was studied both experimentally and by means of the Monte Carlo N-particle transport code (MCNP). The liver was modeled as a spherical segment in MCNP and a hepatic-equivalent solution was used as an experimental phantom. In the as-built facility, the ratio between maximum and minimum flux values inside the phantom ({phi}{sub max}/{phi}{sub min}) was 3.8; this value can be lowered to 2.3 by rotating the liver during the irradiation. In this study, the authors proposed a new facility configuration to achieve a uniform thermal neutron flux distribution in the liver. They showed that a {phi}{sub max}/{phi}{sub min} ratio of 1.4 could be obtained without the need for organ rotation. Flux distributions and dose volume histograms were reported for different graphite configurations.

  3. Influence of neutron irradiation on conduction cooling superconducting magnets

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Yoshida, M.; Ogitsu, T.; Makida, Y.; Nakamoto, T.; Okamura, T.; Sasaki, K.; Sugano, M.

    2015-12-01

    The conduction-cooled superconducting magnets are now widely used in various applications due to their minimum usage of helium. In the accelerator science, they also play an increasingly important role in particle detector solenoids because they can minimize the materials needed for the magnet such that they can be more transparent against irradiated particles. For the same reason they are currently used in high radiation environments because they can reduce the heat load from the irradiation. However, the hadronic reactions, such as neutron or proton irradiation, can create degradation on the thermal conductivity of pure aluminum which is used as a cooling path. It leads to a poor cooling condition of the magnets. In Japan, there are two conduction-cooled superconducting magnets for muon production; one is already constructed and under operation, the other is now under construction. This paper briefly reports the influence of the irradiation on those magnets and discusses the possibilities of HTS based conduction-cooled magnets under high irradiation environments.

  4. Impurities effect on the swelling of neutron irradiated beryllium

    SciTech Connect

    Donne, M.D.; Scaffidi-Argentina, F.

    1995-09-01

    An important factor controlling the swelling behaviour of fast neutron irradiated beryllium is the impurity content which can strongly affect both the surface tension and the creep strength of this material. Being the volume swelling of the old beryllium (early sixties) systematically higher than that of the more modem one (end of the seventies), a sensitivity analysis with the aid of the computer code ANFIBE (ANalysis of Fusion Irradiated BEryllium) to investigate the effect of these material properties on the swelling behaviour of neutron irradiated beryllium has been performed. Two sets of experimental data have been selected: the first one named Western refers to quite recently produced Western beryllium, whilst the second one, named Russian refers to relatively old (early sixties) Russian beryllium containing a higher impurity rate than the Western one. The results obtained with the ANFIBE Code were assessed by comparison with experimental data and the used material properties were compared with the data available in the literature. Good agreement between calculated and measured values has been found.

  5. Age-dependent protection quantities for external neutron irradiation.

    PubMed

    Chou, D P; Wang, J N; Chen, I J; Chang, B J

    2003-01-01

    Based on the recommendations issued by the International Commission on Radiological Protection (ICRP), equivalent doses and effective doses for different ages are obtained for external neutron sources. The calculations at 28 neutron energies from 1 x 10(-9) MeV to 20 MeV are carried out for six irradiation geometries: AP, PA, RLAT, LLAT, ROT and ISO. An age-dependent anthropomorphic mathematical phantom series of six age groups: newborn, 1, 5, 10, 15 years old and adult is used with the Monte Carlo computer code MCNP for the dose evaluations. The results for adults are compared with those in ICRP Publication 74 and are in good agreement. At low energies the effective doses increase as the phantom age increases, but at high energics they decrease with increasing age for the AP, PA, ROT and ISO irradiation geometries. In the whole energy region the effective doses decrease as the phantom age increases for the RLAT and LLAT irradiation geometries. The age-dependent equivalent doses behave similarly to the effective doses, with some exceptions caused by the influence of the organ position. PMID:12862238

  6. Radioactivity of neutron-irradiated cat's-eye chrysoberyls

    NASA Astrophysics Data System (ADS)

    Tang, S. M.; Tay, T. S.

    1999-04-01

    The recent report of marketing of radioactive chrysoberyl cat's-eyes in South-East Asian markets has led us to use an indirect method to estimate the threat to health these color-enhanced gemstones may pose if worn close to skin. We determined the impurity content of several cat's-eye chrysoberyls from Indian States of Orissa and Kerala using PIXE, and calculated the radioactivity that would be generated from these impurities and the constitutional elements if a chrysoberyl was irradiated by neutrons in a nuclear reactor for color enhancement. Of all the radioactive nuclides that could be created by neutron irradiation, only four ( 46Sc, 51Cr, 54Mn and 59Fe) would not have cooled down within a month after irradiation to the internationally accepted level of specific residual radioactivity of 2 nCi/g. The radioactivity of 46Sc, 51Cr and 59Fe would only fall to this safe limit after 15 months and that of 54Mn could remain above this limit for several years.

  7. The medical-irradiation characteristics for neutron capture therapy at the Heavy Water Neutron Irradiation Facility of Kyoto University Research Reactor.

    PubMed

    Sakurai, Yoshinori; Kobayashi, Tooru

    2002-10-01

    At the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor, the mix irradiation of thermal and epi-thermal neutrons, and the solo irradiation of epi-thermal neutrons are available additionally to the thermal neutron irradiation, and then the neutron capture therapy (NCT) at this facility became more flexible, after the update in 1996. The estimation of the depth dose distributions in NCT clinical irradiation, were performed for the standard irradiation modes of thermal, mixed and epi-thermal neutrons, from the both sides of experiment and calculation. On the assumption that the 10B concentration in tumor part was 40 ppm and the ratio of tumor to normal tissue was 3.5, the advantage depth were estimated to 5.4, 6.0, and 8.0, for the respective standard irradiation modes. It was confirmed that the various irradiation conditions can be selected according to the target-volume conditions, such as size, depth, etc. Besides, in the viewpoint of the radiation shielding for patient, it was confirmed that the whole-body exposure is effectively reduced by the new clinical collimators, compared with the old one. PMID:12408307

  8. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    PubMed Central

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources. PMID:25589504

  9. Post irradiation examination of the Spallation Neutron Source target vessels

    SciTech Connect

    McClintock, David A; Ferguson, Phillip D; Mansur, Louis K

    2010-01-01

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is an accelerator-based pulsed neutron source that produces high-energy spallation neutrons by bombarding liquid mercury flowing through a stainless steel target vessel. During operation the proton beam and spallation neutrons produce radiation damage in the AISI 316L austenitic stainless steel target vessel and water-cooled shroud. The beam pulses also cause rapid heating of the liquid mercury, which may produce cavitation erosion damage on the inner surface of the target vessel. The cavitation erosion rate is thought to be highly sensitive to beam power and predicted to be the primary life-limiting factor of target vessel. Though mitigation of cavitation erosion and radiation damage to the target vessel will be a critical for successful high-power operation of the SNS facility, the effects of radiation damage and cavitation erosion to target vessels in liquid metal spallation systems are not well known. Therefore preparations are being undertaken to perform post irradiation examination (PIE) of the liquid mercury target vessel and water-cooled shroud after end-of-life occurs. An overview of the planned PIE for the SNS target vessel is presented here, including proposed techniques for specimen acquisition and subsequent material properties characterization.

  10. Tritium release properties of neutron-irradiated Be 12Ti

    NASA Astrophysics Data System (ADS)

    Uchida, M.; Ishitsuka, E.; Kawamura, H.

    2002-12-01

    Be 12Ti has a high melting point and good chemical stability and is a promising advanced material for the neutron multiplier of the DEMO reactor that requires temperatures higher than 600 °C in a blanket. To evaluate the tritium inventory in the breeding blanket, a tritium release experiment of neutron-irradiated Be 12Ti with a total fast fluence of about 4×10 20 n/cm 2 ( E>1 MeV) was carried out at 330, 400 and 500 °C. It was clear that tritium could be released easier than from beryllium, and the apparent diffusion coefficient in Be 12Ti was about two orders larger than that in beryllium at 600-100 °C. In addition to the good tritium release property, the swelling calculated from the density change of the specimens up to 1100 °C in this test was smaller than that of beryllium.

  11. Crystallographic changes in lead zirconate titanate due to neutron irradiation

    DOE PAGESBeta

    Henriques, Alexandra; Graham, Joseph T.; Landsberger, Sheldon; Ihlefeld, Jon F.; Brennecka, Geoff L.; Brown, Donald W.; Forrester, Jennifer S.; Jones, Jacob L.

    2014-11-17

    Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method) is used to quantify the type and extent of structural changes in PbZr0.5Ti0.5O3 after exposure to a 1 MeV equivalent neutron fluence of 1.7 × 1015 neutrons/cm2. The results show a measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. The results demonstrate a method by which the effects of radiation on crystallographic structure maymore » be investigated.« less

  12. Crystallographic changes in lead zirconate titanate due to neutron irradiation

    SciTech Connect

    Henriques, Alexandra; Graham, Joseph T.; Landsberger, Sheldon; Ihlefeld, Jon F.; Brennecka, Geoff L.; Brown, Donald W.; Forrester, Jennifer S.; Jones, Jacob L.

    2014-11-17

    Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method) is used to quantify the type and extent of structural changes in PbZr0.5Ti0.5O3 after exposure to a 1 MeV equivalent neutron fluence of 1.7 × 1015 neutrons/cm2. The results show a measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. The results demonstrate a method by which the effects of radiation on crystallographic structure may be investigated.

  13. Crystallographic changes in lead zirconate titanate due to neutron irradiation

    DOE PAGESBeta

    Henriques, Alexandra; Graham, Joseph T.; Landsberger, Sheldon; Ihlefeld, Jon F.; Brennecka, Geoff L.; Brown, Donald W.; Forrester, Jennifer S.; Jones, Jacob L.

    2014-11-17

    Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method) is used to quantify the type and extent of structural changes in PbZr0.5Ti0.5O3 after exposure to a 1 MeV equivalent neutron fluence of 1.7 × 1015 neutrons/cm2. The results show a measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. Lastly, the results demonstrate a method by which the effects of radiation on crystallographic structuremore » may be investigated.« less

  14. Crystallographic changes in lead zirconate titanate due to neutron irradiation

    SciTech Connect

    Henriques, Alexandra; Graham, Joseph T.; Landsberger, Sheldon; Ihlefeld, Jon F.; Brennecka, Geoff L.; Brown, Donald W.; Forrester, Jennifer S.; Jones, Jacob L.

    2014-11-17

    Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method) is used to quantify the type and extent of structural changes in PbZr0.5Ti0.5O3 after exposure to a 1 MeV equivalent neutron fluence of 1.7 × 1015 neutrons/cm2. The results show a measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. Lastly, the results demonstrate a method by which the effects of radiation on crystallographic structure may be investigated.

  15. Crystallographic changes in lead zirconate titanate due to neutron irradiation

    SciTech Connect

    Henriques, Alexandra; Graham, Joseph T.; Landsberger, Sheldon; Ihlefeld, Jon F.; Brennecka, Geoff L.; Brown, Donald W.; Forrester, Jennifer S.; Jones, Jacob L.

    2014-11-15

    Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method) is used to quantify the type and extent of structural changes in PbZr{sub 0.5}Ti{sub 0.5}O{sub 3} after exposure to a 1 MeV equivalent neutron fluence of 1.7 × 10{sup 15} neutrons/cm{sup 2}. The results show a measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. The results demonstrate a method by which the effects of radiation on crystallographic structure may be investigated.

  16. Quantum transport in neutron-irradiated modulation-doped heterojunctions. I. Fast neutrons

    SciTech Connect

    Jin, W.; Zhou, J.; Huang, Y.; Cai, L.

    1988-12-15

    We have investigated the characteristics of low-temperature quantum transport in Al/sub x/Ga/sub 1-//sub x/As/GaAs modulation-doped heterojunctions irradiated by fast neutrons of about 14 MeV energy. The concentration and the mobility of the two-dimensional electron gas (2D EG) under low magnetic fields decrease with increase in the concentrations of scatterers, such as ionized impurities, lattice defects, and interface roughness. On the other hand, under strong magnetic fields, the Hall plateau broadening associated with the Landau localized states, and the Shubnikov--de Hass (SdH) oscillation enhancement associated with the Landau extended states, increase markedly after fast-neutron irradiation.

  17. Quantum transport in neutron-irradiated modulation-doped heterojunctions. II. Thermal neutrons

    SciTech Connect

    Jin, W.; Zhou, J.; Huang, Y.; Cai, L.

    1988-12-15

    We have investigated the characteristics of the low-temperature quantum transport Al/sub x/Ga/sub 1-//sub x/As/GaAs modulation-doped heterojunctions irradiated by thermal neutrons of about 0.025 eV energy. Time-dependent effects related to nuclear radiation such as ..beta../sup -/ decay and ..gamma.. radiation are discussed in detail. The concentration and the mobility of the two-dimensional electron gas (2D EG) under low magnetic fields, the Hall plateau broadening, and the Shubnikov--de Haas (SdH) oscillation enhancement under strong magnetic fields all increase immediately after the irradiation, and then relax for long times. Above all, parallel conduction without illumination is first observed by us with a higher flux of thermal neutrons.

  18. Observation of Gamma Irradiation-Induced Suppression of Reversed Annealing in Neutron Irradiated MCZ Si Detectors

    SciTech Connect

    Li, Z.; Gul, R.; Harkonen, J.; Kierstead, J.; Metcalfe, J.; Seidel, S.

    2009-02-06

    For the development of radiation-hard Si detectors for the SiD BeamCal program for the future ILC (International Linear Collider), n-type MCZ Si detectors have been irradiated first by fast neutrons to flueneces of 1.5 x 1014 and 3 x 1014 neq/cm2, and then by gamma up to 500 Mrad. The motivation of this mixed radiation project is to develop a Si detector that can utilize the gamma/electron radiation that exists in the ICL radiation environment, which also includes neutrons. By using the positive space charge (SC) created by gamma radiation in MCZ Si detectors, one can cancel the negative space charge created by neutrons, thus reducing the overall/net space charge density and therefore the full depletion voltage of the detector.

  19. 49 CFR 173.459 - Mixing of fissile material packages with non-fissile or fissile-excepted material packages.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Mixing of fissile material packages with non... (Radioactive) Materials § 173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages. Mixing of fissile material packages with other types of Class 7 (radioactive)...

  20. Progress on performance assessment of ITER enhanced heat flux first wall technology after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hirai, T.; Bao, L.; Barabash, V.; Chappuis, Ph; Eaton, R.; Escourbiac, F.; Giqcuel, S.; Merola, M.; Mitteau, R.; Raffray, R.; Linke, J.; Loewenhoff, Th; Pintsuk, G.; Wirtz, M.; Boomstra, D.; Magielsen, A.; Chen, J.; Wang, P.; Gervash, A.; Safronov, V.

    2016-02-01

    ITER first wall (FW) panels are irradiated by energetic neutrons during the nuclear phase. Thus, an irradiation and high heat flux testing programme is undertaken by the ITER organization in order to evaluate the effects of neutron irradiation on the performance of enhanced heat flux (EHF) FW components. The test campaign includes neutron irradiation (up to 0.6-0.8 dpa at 200 °C-250 °C) of mock-ups that are representative of the final EHF FW panel design, followed by thermal fatigue tests (up to 4.7 MW m-2). Mock-ups were manufactured by the same manufacturing process as proposed for the series production. After a pre-irradiation thermal screening, eight mock-ups will be selected for the irradiation campaigns. This paper reports the preparatory work of HHF tests and neutron irradiation, assessment results as well as a brief description of mock-up manufacturing and inspection routes.

  1. The effect of neutron irradiation on silicon carbide fibers

    SciTech Connect

    Newsome, G.A.

    1997-01-01

    Nine types of SiC fiber have been exposed to neutron radiation in the Advanced Test Reactor at 250 C for various lengths of time ranging from 83 to 128 days. The effects of these exposures have been initially determined using scanning electron microscopy. The fibers tested were Nicalon{trademark} CG, Tyranno, Hi-Nicalon{trademark}, Dow Corning SiC, Carborundum SiC, Textron SCS-6, polymethysilane (PMS) derived SiC from the University of Michigan, and two types of MER SiC fiber. This covers a range of fibers from widely used commercial fibers to developmental fibers. Consistent with previous radiation experiments, Nicalon fiber was severely degraded by the neutron irradiation. Similarly, Tyranno suffered severe degradation. The more advanced fibers which approach the composition and properties of SiC performed well under irradiation. Of these, the Carborundum SiC fiber appeared to perform the best. The Hi-Nicalon and Dow Corning Fibers exhibited good general stability, but also appear to have some surface roughening. The MER fibers and the Textron SCS-6 fibers both had carbon cores which adversely influenced the overall stability of the fibers.

  2. Irradiation Effects for the Pulsed Fast Neutron Analysis (PFNA) Cargo Interrogation System

    SciTech Connect

    Slater, C.O.

    2001-02-02

    At the request of Safety and Ecology Corporation of Tennessee, radiation effects of the proposed Pulsed Fast Neutron Analysis (PFNA) Cargo Interrogation System have been examined. First, fissile cargo were examined to determine if a significant neutron signal would be observable during interrogation. Results indicated that ample multiplication would be seen for near critical bare targets. The water-reflected sphere showed relatively little multiplication. By implication, a fissile target shielded by hydrogenous cargo might not be detectable by neutron interrogation, particularly if reliance is placed on the neutron signal. The cargo may be detectable if use can be made of the ample increase in the photon signal. Second, dose rates were calculated at various locations within and just outside the facility building. These results showed that some dose rates may be higher than the target dose rate of 0.05 mrem/h. However, with limited exposure time, the total dose may be well below the allowed total dose. Lastly, estimates were made of the activation of structures and typical cargo. Most cargo will not be exposed long enough to be activated to levels of concern. On the other hand, portions of the structure may experience buildup of some radionuclides to levels of concern.

  3. Particle LET spectra from microelectronics packaging materials subjected to neutron and proton irradiation

    NASA Astrophysics Data System (ADS)

    Browning, J. S.; Holtkamp, D. B.

    1988-12-01

    Cumulative fractions for LET spectra were measured for particles ejected from microelectronics packaging materials subjected to neutron and proton irradiation. The measurements for the neutron irradiation compare well with Monte Carlo theoretical calculations. The spectra can be used to access microelectronics vulnerabilities in strategic-nuclear- weapon, space-trapped, and neutral-beam directed-energy particle environments.

  4. Optical absorption and luminescence in neutron-irradiated, silica-based fibers

    SciTech Connect

    Cooke, D.W.; Farnum, E.H.; Clinard, F.W.

    1995-04-01

    The objectives of this work are to assess the effects of thermal annealing and photobleaching on the optical absorption of neutron-irradiated, silica fibers of the type proposed for use in ITER diagnostics, and to measure x-ray induced luminescence of unirradiated (virgin) and neutron-irradiated fibers.

  5. Characterization of the fast neutron irradiation facility of the Portuguese Research Reactor after core conversion.

    PubMed

    Marques, J G; Sousa, M; Santos, J P; Fernandes, A C

    2011-08-01

    The fast neutron irradiation facility of the Portuguese Research Reactor was characterized after the reduction in uranium enrichment and rearrangement of the core configuration. In this work we report on the determination of the hardness parameter and the 1MeV equivalent neutron flux along the facility, in the new irradiation conditions, following ASTM E722 standard. PMID:21071234

  6. Point defect production and annihilation in neutron-irradiated zirconium

    SciTech Connect

    MacEwen, S.R.; Zee, R.H.; Birtcher, R.C.; Abromeit, C.

    1984-05-01

    High-purity Zr has been irradiated to a dose of 2.2 x 10/sup 21/ n/m/sup 2/ (E < 0.1 MeV) using the pulsed spallation source at IPNS. Electrical resistivity was monitored continuously during irradiation. The saturation resistivity, found from a linear extrapolation of the damage-rate curve between four and five n..cap omega...m. However, comparison with data from the literature shows that the normalized damage-rate curves from five experiments at different temperatures (less than or equal to 77 K) and with different neutron spectra, all fall on the same common curve. A saturation resistivity of 100 n..cap omega...m is found from the high-dose, linear part of this curve. A spontaneous recombination volume in the range 280 to 400 atomic volumes is found using the theory of Dettmann, Leibfried and Schroeder and the saturation resistivity of 100 n..cap omega...m. Post-irradiation annealing has been done up to 300 K using stepped, isochronal anneals. The recovery spectrum is in reasonable agreement with previous work, showing a large peak near 100 K, and two smaller peaks at 160 K and 250 K.

  7. Separation of radiation defects in Ni and Ni-C alloys under electron and neutron irradiation

    NASA Astrophysics Data System (ADS)

    Arbuzov, S. E.; Danilov, V. L.; Goshchitskii, B. N.; Kar'kin, A. E.; Parkhomenko, V. D.

    2016-02-01

    Complex investigations of radiation damage of Ni and Ni- 880 at. ppm C alloy under electron and neutron irradiation in the region of room temperature hardened and deformed state. In pure nickel, with the deformation microstructure, both in electron and in the neutron irradiation is observed separation of radiation-induced defects. When electron irradiation in the alloy Ni-C separation effect is observed, and when neutron irradiation there is no. This is due to the interaction of carbon atoms with radiation defects. The main sinks for radiation-induced defects are the areas with a high concentration of defects in cascades of atomic displacements.

  8. Determining organ dose conversion coefficients for external neutron irradiation by using a voxel mouse model

    PubMed Central

    Zhang, Xiaomin; Xie, Xiangdong; Qu, Decheng; Ning, Jing; Zhou, Hongmei; Pan, Jie; Yang, Guoshan

    2016-01-01

    A set of fluence-to-dose conversion coefficients has been calculated for neutrons with energies <20 MeV using a developed voxel mouse model and Monte Carlo N-particle code (MCNP), for the purpose of neutron radiation effect evaluation. The calculation used 37 monodirectional monoenergetic neutron beams in the energy range 10−9 MeV to 20 MeV, under five different source irradiation configurations: left lateral, right lateral, dorsal–ventral, ventral–dorsal, and isotropic. Neutron fluence-to-dose conversion coefficients for selected organs of the body were presented in the paper, and the effect of irradiation geometry conditions, neutron energy and the organ location on the organ dose was discussed. The results indicated that neutron dose conversion coefficients clearly show sensitivity to irradiation geometry at neutron energy below 1 MeV. PMID:26661852

  9. Lithium target for accelerator based BNCT neutron source: Influence by the proton irradiation on lithium

    NASA Astrophysics Data System (ADS)

    Fujii, R.; Imahori, Y.; Nakakmura, M.; Takada, M.; Kamada, S.; Hamano, T.; Hoshi, M.; Sato, H.; Itami, J.; Abe, Y.; Fuse, M.

    2012-12-01

    The neutron source for Boron Neutron Capture Therapy (BNCT) is in the transition stage from nuclear reactor to accelerator based neutron source. Generation of low energy neutron can be achieved by 7Li (p, n) 7Be reaction using accelerator based neutron source. Development of small-scale and safe neutron source is within reach. The melting point of lithium that is used for the target is low, and durability is questioned for an extended use at a high current proton beam. In order to test its durability, we have irradiated lithium with proton beam at the same level as the actual current density, and found no deterioration after 3 hours of continuous irradiation. As a result, it is suggested that lithium target can withstand proton irradiation at high current, confirming suitability as accelerator based neutron source for BNCT.

  10. Determining organ dose conversion coefficients for external neutron irradiation by using a voxel mouse model.

    PubMed

    Zhang, Xiaomin; Xie, Xiangdong; Qu, Decheng; Ning, Jing; Zhou, Hongmei; Pan, Jie; Yang, Guoshan

    2016-03-01

    A set of fluence-to-dose conversion coefficients has been calculated for neutrons with energies <20 MeV using a developed voxel mouse model and Monte Carlo N-particle code (MCNP), for the purpose of neutron radiation effect evaluation. The calculation used 37 monodirectional monoenergetic neutron beams in the energy range 10(-9) MeV to 20 MeV, under five different source irradiation configurations: left lateral, right lateral, dorsal-ventral, ventral-dorsal, and isotropic. Neutron fluence-to-dose conversion coefficients for selected organs of the body were presented in the paper, and the effect of irradiation geometry conditions, neutron energy and the organ location on the organ dose was discussed. The results indicated that neutron dose conversion coefficients clearly show sensitivity to irradiation geometry at neutron energy below 1 MeV. PMID:26661852

  11. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2015-01-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor (HFIR), Oak Ridge National Laboratory at reactor coolant temperatures of 50-70 °C to low displacement damage of 0.025 and 0.3 dpa. After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5 × 1025 m-2 to reach the total ion fluence of 1 × 1026 m-2 in order to investigate the near-surface deuterium retention and saturation via nuclear reaction analysis. Final thermal desorption spectroscopy was performed to elucidate the irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near-surface (<5 µm depth) deuterium concentration increased from 0.5 at% D/W in 0.025 dpa samples to 0.8 at% D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near-surface retention via nuclear reaction analysis indicated the deuterium was trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.3 dpa) at 500 °C cases even in the relatively low ion fluence of 1026 m-2.

  12. Development and characteristics of the HANARO neutron irradiation facility for applications in the boron neutron capture therapy field

    NASA Astrophysics Data System (ADS)

    Kim, Myong-Seop; Lee, Byung-Chul; Hwang, Sung-Yul; Kim, Heonil; Jun, Byung-Jin

    2007-05-01

    The HANARO neutron irradiation facility for various applications in the boron neutron capture therapy (BNCT) field was developed, and its characteristics were investigated. In order to obtain the sufficient thermal neutron flux with a low level of contamination by fast neutrons and gamma rays, a radiation filtering method was adopted. The radiation filter was designed by using a silicon single crystal, cooled by liquid nitrogen, and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room was finished. Neutron beam characteristics were measured by using bare and cadmium-covered gold foils and wires. The in-phantom neutron flux distribution was measured for flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimental data. The thermal neutron flux and Cd ratio available at this facility were confirmed to be 1.49 × 109 n cm-2 s-1 and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79 × 109 n cm-2 s-1 at a depth of 3 mm in the phantom. The two-dimensional in-phantom neutron flux distribution was determined, and significant neutron irradiation was observed within 20 mm from the phantom surface. The gamma-ray dose rate for the free beam condition was expected to be about 80 cGy h-1. These experimental results were reasonably well supported by calculation using the facility design code. This HANARO thermal neutron facility can be used not only for clinical trials, but also for various pre-clinical studies in the BNCT field.

  13. Development and characteristics of the HANARO neutron irradiation facility for applications in the boron neutron capture therapy field.

    PubMed

    Kim, Myong-Seop; Lee, Byung-Chul; Hwang, Sung-Yul; Kim, Heonil; Jun, Byung-Jin

    2007-05-01

    The HANARO neutron irradiation facility for various applications in the boron neutron capture therapy (BNCT) field was developed, and its characteristics were investigated. In order to obtain the sufficient thermal neutron flux with a low level of contamination by fast neutrons and gamma rays, a radiation filtering method was adopted. The radiation filter was designed by using a silicon single crystal, cooled by liquid nitrogen, and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room was finished. Neutron beam characteristics were measured by using bare and cadmium-covered gold foils and wires. The in-phantom neutron flux distribution was measured for flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimental data. The thermal neutron flux and Cd ratio available at this facility were confirmed to be 1.49 x 10(9) n cm(-2) s(-1) and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79 x 10(9) n cm(-2) s(-1) at a depth of 3 mm in the phantom. The two-dimensional in-phantom neutron flux distribution was determined, and significant neutron irradiation was observed within 20 mm from the phantom surface. The gamma-ray dose rate for the free beam condition was expected to be about 80 cGy h(-1). These experimental results were reasonably well supported by calculation using the facility design code. This HANARO thermal neutron facility can be used not only for clinical trials, but also for various pre-clinical studies in the BNCT field. PMID:17440252

  14. Protecting Intestinal Epithelial Cell Number 6 against Fission Neutron Irradiation through NF-κB Signaling Pathway

    PubMed Central

    Chang, Gong-Min; Gao, Ya-Bing; Wang, Shui-Ming; Xu, Xin-Ping; Zhao, Li; Zhang, Jing; Li, Jin-Feng; Wang, Yun-Liang; Peng, Rui-Yun

    2015-01-01

    The purpose of this paper is to explore the change of NF-κB signaling pathway in intestinal epithelial cell induced by fission neutron irradiation and the influence of the PI3K/Akt pathway inhibitor LY294002. Three groups of IEC-6 cell lines were given: control group, neutron irradiation of 4Gy group, and neutron irradiation of 4Gy with LY294002 treatment group. Except the control group, the other groups were irradiated by neutron of 4Gy. LY294002 was given before 24 hours of neutron irradiation. At 6 h and 24 h after neutron irradiation, the morphologic changes, proliferation ability, apoptosis, and necrosis rates of the IEC-6 cell lines were assayed and the changes of NF-κB and PI3K/Akt pathway were detected. At 6 h and 24 h after neutron irradiation of 4Gy, the proliferation ability of the IEC-6 cells decreased and lots of apoptotic and necrotic cells were found. The injuries in LY294002 treatment and neutron irradiation group were more serious than those in control and neutron irradiation groups. The results suggest that IEC-6 cells were obviously damaged and induced serious apoptosis and necrosis by neutron irradiation of 4Gy; the NF-κB signaling pathway in IEC-6 was activated by neutron irradiation which could protect IEC-6 against injury by neutron irradiation; LY294002 could inhibit the activity of IEC-6 cells. PMID:25866755

  15. Quantitative TEM analysis of precipitation and grain boundary segregation in neutron irradiated EUROFER 97

    NASA Astrophysics Data System (ADS)

    Dethloff, Christian; Gaganidze, Ermile; Aktaa, Jarir

    2014-11-01

    Characterization of irradiation induced microstructural defects is essential for assessing the applicability of structural steels like the Reduced Activation Ferritic/Martensitic steel EUROFER 97 in upcoming fusion reactors. In this work Transmission Electron Microscopy (TEM) is used to analyze the types and structure of precipitates, and the evolution of their size distributions and densities caused by neutron irradiation to a dose of 32 displacements per atom (dpa) at 330-340 °C in the irradiation experiment ARBOR 1. A significant growth of MX and M23C6 type precipitates is observed after neutron irradiation, while the precipitate density remains unchanged. Hardening caused by MX and M23C6 precipitate growth is assessed by applying the Dispersed Barrier Hardening (DBH) model, and shown to be of minor importance when compared to other irradiation effects like dislocation loop formation. Additionally, grain boundary segregation of chromium induced by neutron irradiation was investigated and detected in irradiated specimens.

  16. Microstructure and mechanical behavior of neutron irradiated ultrafine grained ferritic steel

    SciTech Connect

    Ahmad Alsabbagh; Apu Sarkar; Brandon Miller; Jatuporn Burns; Leah Squires; Douglas Porter; James I. Cole; K. L. Murty

    2014-10-01

    Neutron irradiation effects on ultra-fine grain (UFG) low carbon steel prepared by equal channel angular pressing (ECAP) has been examined. Counterpart samples with conventional grain (CG) sizes have been irradiated alongside with the UFG ones for comparison. Samples were irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) to 1.24 dpa. Atom probe tomography revealed manganese, silicon-enriched clusters in both ECAP and CG steel after neutron irradiation. X-ray quantitative analysis showed that dislocation density in CG increased after irradiation. However, no significant change was observed in UFG steel revealing better radiation tolerance.

  17. New E‧ centers in neutron-irradiated α-quartz

    NASA Astrophysics Data System (ADS)

    Mashkovtsev, R. I.; Pan, Y.

    2016-03-01

    Several E‧-type defects have been revealed in neutron-irradiated natural and synthetic α-quartz by using electron paramagnetic resonance (EPR) spectroscopy. For the known E'2 center the primary spin Hamiltonian parameter matrices g and A(29Si) (hyperfine interaction with 29Si) have been refined and provide compelling evidence for spin trapping on the long-bond Si atom. The EPR spectra of the new E'11 center demonstrate that the super-hyperfine structure arises from the interaction with 27Al, the first-ever example of Al-associated E‧ centers in crystalline quartz. The matrices g and A(29Si) of E'11 and another new center (E'12) support the forward-oriented configuration proposed for the E'α center in amorphous silica.

  18. Microstructural evolution in fast-neutron-irradiated austenitic stainless steels

    SciTech Connect

    Stoller, R.E.

    1987-12-01

    The present work has focused on the specific problem of fast-neutron-induced radiation damage to austenitic stainless steels. These steels are used as structural materials in current fast fission reactors and are proposed for use in future fusion reactors. Two primary components of the radiation damage are atomic displacements (in units of displacements per atom, or dpa) and the generation of helium by nuclear transmutation reactions. The radiation environment can be characterized by the ratio of helium to displacement production, the so-called He/dpa ratio. Radiation damage is evidenced microscopically by a complex microstructural evolution and macroscopically by density changes and altered mechanical properties. The purpose of this work was to provide additional understanding about mechanisms that determine microstructural evolution in current fast reactor environments and to identify the sensitivity of this evolution to changes in the He/dpa ratio. This latter sensitivity is of interest because the He/dpa ratio in a fusion reactor first wall will be about 30 times that in fast reactor fuel cladding. The approach followed in the present work was to use a combination of theoretical and experimental analysis. The experimental component of the work primarily involved the examination by transmission electron microscopy of specimens of a model austenitic alloy that had been irradiated in the Oak Ridge Research Reactor. A major aspect of the theoretical work was the development of a comprehensive model of microstructural evolution. This included explicit models for the evolution of the major extended defects observed in neutron irradiated steels: cavities, Frank faulted loops and the dislocation network. 340 refs., 95 figs., 18 tabs.

  19. Neutron-Irradiated Samples as Test Materials for MPEX

    DOE PAGESBeta

    Ellis, Ronald James; Rapp, Juergen

    2015-10-09

    Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of themore » samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.« less

  20. Neutron-Irradiated Samples as Test Materials for MPEX

    SciTech Connect

    Ellis, Ronald James; Rapp, Juergen

    2015-10-09

    Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of the samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.

  1. Neutron energy spectrum influence on irradiation hardening and microstructural development of tungsten

    DOE PAGESBeta

    Fukuda, Makoto; Kiran Kumar, N. A. P.; Koyanagi, Takaaki; Garrison, Lauren M.; Snead, Lance L.; Katoh, Yutai; Hasegawa, Akira

    2016-07-02

    We performed a neutron irradiation to single crystal pure tungsten in the mixed spectrum High Flux Isotope Reactor (HFIR). In order to investigate the influences of neutron energy spectrum, the microstructure and irradiation hardening were compared with previous data obtained from the irradiation campaigns in the mixed spectrum Japan Material Testing Reactor (JMTR) and the sodium-cooled fast reactor Joyo. The irradiation temperatures were in the range of ~90–~800 °C and fast neutron fluences were 0.02–9.00 × 1025 n/m2 (E > 0.1 MeV). Post irradiation evaluation included Vickers hardness measurements and transmission electron microscopy. Moreover, the hardness and microstructure changes exhibitedmore » a clear dependence on the neutron energy spectrum. The hardness appeared to increase with increasing thermal neutron flux when fast fluence exceeds 1 × 1025 n/m2 (E > 0.1 MeV). Finally, irradiation induced precipitates considered to be χ- and σ-phases were observed in samples irradiated to >1 × 1025 n/m2 (E > 0.1 MeV), which were pronounced at high dose and due to the very high thermal neutron flux of HFIR. Although the irradiation hardening mainly caused by defects clusters in a low dose regime, the transmutation-induced precipitation appeared to impose additional significant hardening of the tungsten.« less

  2. Migration and accumulation at dislocations of transmutation helium in austenitic steels upon neutron irradiation

    NASA Astrophysics Data System (ADS)

    Kozlov, A. V.; Portnykh, I. A.

    2016-04-01

    The model of the migration and accumulation at dislocations of transmutation helium and the formation of helium-vacancy pore nuclei in austenitic steels upon neutron irradiation has been proposed. As illustrations of its application, the dependences of the characteristics of pore nuclei on the temperature of neutron irradiation have been calculated. The results of the calculations have been compared with the experimental data in the literature on measuring the characteristics of radiation-induced porosity that arises upon the irradiation of shells of fuel elements of a 16Cr-19Ni-2Mo-2Mn-Si-Ti-Nb-V-B steel in a fast BN600 neutron reactor at different temperatures.

  3. Optical absorption and luminescence studies of fast neutron-irradiated complex oxides for jewellery applications

    NASA Astrophysics Data System (ADS)

    Mironova-Ulmane, N.; Skvortsova, V.; Popov, A. I.

    2016-07-01

    We studied the optical absorption and luminescence of agate (SiO2), topaz (Al2[SiO4](F,OH)2), beryl (Be3Al2Si6O18), and prehnite (Ca2Al(AlSi3O10)(OH)2) doped with different concentrations of transition metal ions and exposed to fast neutron irradiation. The exchange interaction between the impurity ions and the defects arising under neutron irradiation causes additional absorption as well as bands' broadening in the crystals. These experimental results allow us to suggest the method for obtaining new radiation-defect induced jewellery colors of minerals due to neutron irradiation.

  4. Effects of hole doping by neutron irradiation of magnetic field induced electronic phase transitions in graphite

    SciTech Connect

    Singleton, John; Yaguchi, Hiroshi

    2008-01-01

    We have investigated effects of hole doping by fast-neutron irradiation on the magnetic-field induced phase transitions in graphite using specimens irradiated with fast neutrons. Resistance measurements have been done in magnetic fields of up to above 50 T and at temperatures down to about 1.5 K. The neutron irradiation creates lattice defects acting as acceptors, affecting the imbalance of the electron and hole densities and the Fermi level. We have found that the reentrant field from the field induced state back to the normal state shifts towards a lower field with hole doping, suggestive of the participation of electron subbands in the magnetic-field induced state.

  5. THE FISSILE MATERIAL TRANSPARENCY TECHNOLOGY DEMONSTRATION (FMTTD)

    SciTech Connect

    L. R. AVENS; J. E. DOYLE; M. F. MULLEN

    2001-06-01

    The United States Department of Defense, Defense Threat Reduction Agency Cooperative Threat Reduction program is supporting the construction of a fissile material storage facility at Mayak in the Russian Federation. Up to 34 tons of weapon-grade plutonium will be stored in the facility to await disposition. In order to meet arms control and nonproliferation objectives, the U.S. Congress has requested assurances that the nuclear material stored at the Mayak facility is derived from dismantled nuclear weapons. The usual approach to identify the origin or state of radioactive materials is to measure the intensity and energy of neutron and gamma radiation emitted. However, the Russian Federation considers such details as isotopic composition and mass to be classified. The solution arrived at by a DOE multilaboratory team is to place the radioactive specimen, the gamma and neutron counters, and all the computational equipment behind an information barrier. In the Fissile Materials Transparency Technology Demonstration (FMTD), this equipment was configured and programmed to measure the following six attributes: isotopic ratio, threshold mass, absence of oxide, presence of plutonium, age, and symmetry. On August 16, 2000, at Los Alamos National Laboratory, a delegation of Russian officials observed the successful demonstration of this new technology (called an Attribute Measurement System with Information Barrier, or AMS/IB). The scientists were able to demonstrate without releasing classified information that the nuclear material sample being tested (a nuclear weapon pit) had the declared weapon-grade plutonium characteristics. Once fully developed, AMS/IB technology will protect sensitive information while providing the United States increased confidence that the mandated Russian fissile materials have been stored. Attribute measurement systems can play a role in a number of U.S.-Russian nuclear security regimes such as the Trilateral Initiative, the Plutonium

  6. Properties of a Cold-Neutron Irradiation Facility for In Vitro Research on Boron Neutron Capture Therapy at the Geesthacht Neutron Facility

    SciTech Connect

    Luedemann, L.; Kampmann, R.; Sosaat, W.; Staron, P.; Wille, P.

    2000-05-15

    A new irradiation facility, GBET (basic research on boron neutron capture therapy), especially designed for in vitro experiments on boron neutron capture therapy was put into operation at the Geesthacht Neutron Facility of the GKSS Research Center. Its location at a cold-neutron guide without direct view of the reactor core has two advantages: First, contamination of the primary beam with fast neutrons or photons is negligible. Second, GBET yields a high cold-neutron flux of 1.4 x 10{sup 8}/(cm{sup 2}.s) over an area of 3 x 4 cm. As a result of the energy dependence of the neutron absorption cross section of boron, this corresponds to a higher effective thermal flux of 4.7 x 10{sup 8}/(cm{sup 2}.s). This effect is used to reduce the irradiation times by a factor of 3.32.The effective flux is sufficient for irradiation of thin samples like cell monolayers in conventional culture flasks. For such in vitro irradiations, a survival fraction of 1% is achieved at a homogeneous boron concentration of 100 ppm {sup 10}B within {approx}20 min. Furthermore, the beam can be used for boron radiography. The respective experimental conditions are discussed, especially the neutron flux distribution, available for these different types of samples.

  7. Biomedical irradiation system for boron neutron capture therapy at the Kyoto University Reactor.

    PubMed

    Kobayashi, T; Kanda, K; Ujeno, Y; Ishida, M R

    1990-01-01

    Physics studies related to radiation source, spectroscopy, beam quality, dosimetry, and biomedical applications using the Kyoto University Reactor Heavy Water Facility are described. Also, described are a Nickel Mirror Neutron Guide Tube and a Super Mirror Neutron Guide Tube that are used both for the measurement of boron concentration in phantom and living tissue and for precise measurements of neutron flux in phantom in the presence of both light and heavy water. Discussed are: (1) spectrum measurements using the time of flight technique, (2) the elimination of gamma rays and fast neutrons from a thermal neutron irradiation field, (3) neutron collimation without producing secondary gamma rays, (4) precise neutron flux measurements, dose estimation, and the measurement of boron concentration in tumor and its periphery using guide tubes, (5) the dose estimation of boron-10 for the first melanoma patient, and (6) special-purpose biological irradiation equipment. Other related subjects are also described. PMID:2176458

  8. Irradiation tests of ITER candidate Hall sensors using two types of neutron spectra.

    PubMed

    Ďuran, I; Bolshakova, I; Viererbl, L; Sentkerestiová, J; Holyaka, R; Lahodová, Z; Bém, P

    2010-10-01

    We report on irradiation tests of InSb based Hall sensors at two irradiation facilities with two distinct types of neutron spectra. One was a fission reactor neutron spectrum with a significant presence of thermal neutrons, while another one was purely fast neutron field. Total neutron fluence of the order of 10(16) cm(-2) was accumulated in both cases, leading to significant drop of Hall sensor sensitivity in case of fission reactor spectrum, while stable performance was observed at purely fast neutron spectrum. This finding suggests that performance of this particular type of Hall sensors is governed dominantly by transmutation. Additionally, it further stresses the need to test ITER candidate Hall sensors under neutron flux with ITER relevant spectrum. PMID:21033987

  9. Irradiation tests of ITER candidate Hall sensors using two types of neutron spectra

    SciTech Connect

    Duran, I.; Viererbl, L.; Lahodova, Z.; Sentkerestiova, J.; Bem, P.

    2010-10-15

    We report on irradiation tests of InSb based Hall sensors at two irradiation facilities with two distinct types of neutron spectra. One was a fission reactor neutron spectrum with a significant presence of thermal neutrons, while another one was purely fast neutron field. Total neutron fluence of the order of 10{sup 16} cm{sup -2} was accumulated in both cases, leading to significant drop of Hall sensor sensitivity in case of fission reactor spectrum, while stable performance was observed at purely fast neutron spectrum. This finding suggests that performance of this particular type of Hall sensors is governed dominantly by transmutation. Additionally, it further stresses the need to test ITER candidate Hall sensors under neutron flux with ITER relevant spectrum.

  10. Characterization of the neutron irradiation system for use in the Low-Dose-Rate Irradiation Facility at Sandia National Laboratories.

    SciTech Connect

    Franco, Manuel,

    2014-08-01

    The objective of this work was to characterize the neutron irradiation system consisting of americium-241 beryllium (241AmBe) neutron sources placed in a polyethylene shielding for use at Sandia National Laboratories (SNL) Low Dose Rate Irradiation Facility (LDRIF). With a total activity of 0.3 TBq (9 Ci), the source consisted of three recycled 241AmBe sources of different activities that had been combined into a single source. The source in its polyethylene shielding will be used in neutron irradiation testing of components. The characterization of the source-shielding system was necessary to evaluate the radiation environment for future experiments. Characterization of the source was also necessary because the documentation for the three component sources and their relative alignment within the Special Form Capsule (SFC) was inadequate. The system consisting of the source and shielding was modeled using Monte Carlo N-Particle transport code (MCNP). The model was validated by benchmarking it against measurements using multiple techniques. To characterize the radiation fields over the full spatial geometry of the irradiation system, it was necessary to use a number of instruments of varying sensitivities. First, the computed photon radiography assisted in determining orientation of the component sources. With the capsule properly oriented inside the shielding, the neutron spectra were measured using a variety of techniques. A N-probe Microspec and a neutron Bubble Dosimeter Spectrometer (BDS) set were used to characterize the neutron spectra/field in several locations. In the third technique, neutron foil activation was used to ascertain the neutron spectra. A high purity germanium (HPGe) detector was used to characterize the photon spectrum. The experimentally measured spectra and the MCNP results compared well. Once the MCNP model was validated to an adequate level of confidence, parametric analyses was performed on the model to optimize for potential

  11. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    DOE PAGESBeta

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2014-12-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor, Oak Ridge National Laboratory at reactor coolant temperatures of 50-70°C to low displacement damage of 0.025 and 0.3 dpa under the framework of the US-Japan TITAN program (2007-2013). After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5×10²⁵ m⁻² to reach a total ion fluence of 1×10²⁶ m⁻² in order to investigate the near surface deuterium retention and saturation via nuclear reaction analysis. Finalmore » thermal desorption spectroscopy was performed to elucidate irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near surface (<5 µm depth) deuterium concentration increased from 0.5 at % D/W in 0.025 dpa samples to 0.8 at. % D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near surface retention via nuclear reaction analysis indicated the deuterium was migrated and trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.025 dpa) at 500 °C case even in the relatively low ion fluence of 10²⁶ m⁻².« less

  12. Irradiation effect on deuterium behaviour in low-dose HFIR neutron-irradiated tungsten

    SciTech Connect

    Shimada, Masashi; Cao, G.; Otsuka, T.; Hara, M.; Kobayashi, M.; Oya, Y.; Hatano, Y.

    2014-12-01

    Tungsten samples were irradiated by neutrons in the High Flux Isotope Reactor, Oak Ridge National Laboratory at reactor coolant temperatures of 50-70°C to low displacement damage of 0.025 and 0.3 dpa under the framework of the US-Japan TITAN program (2007-2013). After cooling down, the HFIR neutron-irradiated tungsten samples were exposed to deuterium plasmas in the Tritium Plasma Experiment, Idaho National Laboratory at 100, 200 and 500 °C twice at the ion fluence of 5×10²⁵ m⁻² to reach a total ion fluence of 1×10²⁶ m⁻² in order to investigate the near surface deuterium retention and saturation via nuclear reaction analysis. Final thermal desorption spectroscopy was performed to elucidate irradiation effect on total deuterium retention. Nuclear reaction analysis results showed that the maximum near surface (<5 µm depth) deuterium concentration increased from 0.5 at % D/W in 0.025 dpa samples to 0.8 at. % D/W in 0.3 dpa samples. The large discrepancy between the total retention via thermal desorption spectroscopy and the near surface retention via nuclear reaction analysis indicated the deuterium was migrated and trapped in bulk (at least 50 µm depth for 0.025 dpa and 35 µm depth for 0.025 dpa) at 500 °C case even in the relatively low ion fluence of 10²⁶ m⁻².

  13. Development of microstructure and irradiation hardening of Zircaloy during low dose neutron irradiation at nominally 358 C

    SciTech Connect

    Cockeram, Brian V; Smith, Richard W; Leonard, Keith J; Byun, Thak Sang; Snead, Lance Lewis

    2011-01-01

    Wrought Zircaloy-2 and Zircaloy-4 were neutron irradiated at nominally 358 C in the high flux isotope reactor (HFIR) at relatively low neutron fluences between 5.8 1022 and 2.9 1025 n/m2 (E > 1 MeV). The irradiation hardening and change in microstructure were characterized following irradiation using tensile testing and examinations of microstructure using Analytical Electron Microscopy (AEM). Small increments of dose (0.0058, 0.11, 0.55, 1.08, and 2.93 1025 n/m2) were used in the range where the saturation of irradiation hardening is typically observed so that the role of microstructure evolution and hai loop formation on irradiation hardening could be correlated. An incubation dose between 5.8 1023 and 1.1 1024 n/m2 was needed for loop nucleation to occur that resulted in irradiation hardening. Increases in yield strength were consistent with previous results in this temperature regime, and as expected less irradiation hardening and lower hai loop number density values than those generally reported in literature for irradiations at 260 326 C were observed. Unlike previous lower temperature data, there is evidence in this study that the irradiation hardening can decrease with dose over certain ranges of fluence. Irradiation induced voids were observed in very low numbers in the Zircaloy-2 materials at the highest fluence.

  14. Defect clusters formed from large collision cascades in fcc metals irradiated with spallation neutrons

    NASA Astrophysics Data System (ADS)

    Satoh, Y.; Matsuda, Y.; Yoshiie, T.; Kawai, M.; Matsumura, H.; Iwase, H.; Abe, H.; Kim, S. W.; Matsunaga, T.

    2013-11-01

    Fcc pure metals were irradiated with spallation neutrons (energies up to 500 MeV) at room temperature to a neutron fluence of 1 × 1018 n m-2 at KENS, High Energy Accelerator Research Organization (KEK). Defect clusters induced by large collision cascades were examined using transmission electron microscopy (TEM). In Au, large groups of defects included more than 10 clusters, and the damage zone extended over 50 nm, which was larger than that induced by fusion neutron irradiation (<20 nm). Although small stacking fault tetrahedra (SFT) are formed in subcascades by fission and fusion neutron irradiation, dislocation loops were also observed in the present experiments. Large dislocation loops (>10 nm) were identified as vacancy type by the conventional inside-outside contrast method. Because of the low neutron fluence, spatial overlapping of collision cascades was ignored. Large vacancy loops are formed through cooperative reactions among subcascades in a single collision cascade with large recoil energy.

  15. Effects of neutron irradiation of ultra-thin HfO{sub 2} films

    SciTech Connect

    Hsu, K.-W.; Bian, S.; Shohet, J. L.; Ren, H.; Agasie, R. J.; Nishi, Y.

    2014-01-20

    Neutron irradiation at low fluence decreases the Pb-type and E′ defect levels in ultra-thin hafnium dioxide films because electrons can fill existing states. These electrons come from electron-hole pairs generated by neutron interactions with silicon and oxygen. Thus, a low fluence of neutrons “anneals” the sample. However, when neutron fluence increases, more neutrons collide with oxygen atoms and cause them to leave the lattice or to transmute into different atoms. This causes the E′ states to increase. As defect-state concentrations increase, leakage currents increase, but since the E′ is much lower than the Pb concentration, this is not a dominant factor.

  16. Identification of neutron irradiation induced strain rate sensitivity change using inverse FEM analysis of Charpy test

    NASA Astrophysics Data System (ADS)

    Haušild, Petr; Materna, Aleš; Kytka, Miloš

    2015-04-01

    A simple methodology how to obtain additional information about the mechanical behaviour of neutron-irradiated WWER 440 reactor pressure vessel steel was developed. Using inverse identification, the instrumented Charpy test data records were compared with the finite element computations in order to estimate the strain rate sensitivity of 15Ch2MFA steel irradiated with different neutron fluences. The results are interpreted in terms of activation volume change.

  17. Improvement of depth dose distribution using multiple-field irradiation in boron neutron capture therapy.

    PubMed

    Fujimoto, N; Tanaka, H; Sakurai, Y; Takata, T; Kondo, N; Narabayashi, M; Nakagawa, Y; Watanabe, T; Kinashi, Y; Masunaga, S; Maruhashi, A; Ono, K; Suzuki, M

    2015-12-01

    It is important that improvements are made to depth dose distribution in boron neutron capture therapy, because the neutrons do not reach the innermost regions of the human body. Here, we evaluated the dose distribution obtained using multiple-field irradiation in simulation. From a dose volume histogram analysis, it was found that the mean and minimum tumor doses were increased using two-field irradiation, because of improved dose distribution for deeper-sited tumors. PMID:26282566

  18. Neutron dosimetry and damage calculations for the EBRII COBRA-1A irradiations

    SciTech Connect

    Greenwood, L.R.; Ratner, R.T.

    1997-04-01

    Neutron fluence measurements and radiation damage calculations are reported for the joint U.S. and Japanese COBRA-1A1 and 1A2 irradiations in the Experimental Breeder Reactor II. The maximum total neutron fluences at midplane were 2.0E+22 and 7.5E+22 n/cm{sup 2}, for the 1A1 and 1A2 irradiations, respectively, resulting in about 8.0 and 30.3 dpa in stainless steel.

  19. Deuterium Depth Profile in Neutron-Irradiated Tungsten Exposed to Plasma

    SciTech Connect

    Masashi Shimada; G. Cao; Y. Hatano; T. Oda; Y. Oya; M. Hara; P. Calderoni

    2011-05-01

    The effect of radiation damage has been mainly simulated using high-energy ion bombardment. The ions, however, are limited in range to only a few microns into the surface. Hence, some uncertainty remains about the increase of trapping at radiation damage produced by 14 MeV fusion neutrons, which penetrate much farther into the bulk material. With the Japan-US joint research project: Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), the tungsten samples (99.99 % pure from A.L.M.T., 6mm in diameter, 0.2mm in thickness) were irradiated to high flux neutrons at 50 C and to 0.025 dpa in the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL). Subsequently, the neutron-irradiated tungsten samples were exposed to a high-flux deuterium plasma (ion flux: 1021-1022 m-2s-1, ion fluence: 1025-1026 m-2) in the Tritium Plasma Experiment (TPE) at the Idaho National Laboratory (INL). First results of deuterium retention in neutron-irradiated tungsten exposed in TPE have been reported previously. This paper presents the latest results in our on-going work of deuterium depth profiling in neutron-irradiated tungsten via nuclear reaction analysis. The experimental data is compared with the result from non neutron-irradiated tungsten, and is analyzed with the Tritium Migration Analysis Program (TMAP) to elucidate the hydrogen isotope behavior such as retention and depth distribution in neutron-irradiated and non neutron-irradiated tungsten.

  20. Application of nondestructive gamma-ray and neutron techniques for the safeguarding of irradiated fuel materials

    SciTech Connect

    Phillips, J.R.; Halbig, J.K.; Lee, D.M.; Beach, S.E.; Bement, T.R.; Dermendjiev, E.; Hatcher, C.R.; Kaieda, K.; Medina, E.G.

    1980-05-01

    Nondestructive gamma-ray and neutron techniques were used to characterize the irradiation exposures of irradiated fuel assemblies. Techniques for the rapid measurement of the axial-activity profiles of fuel assemblies have been developed using ion chambers and Be(..gamma..,n) detectors. Detailed measurements using high-resolution gamma-ray spectrometry and passive neutron techniques were correlated with operator-declared values of cooling times and burnup.

  1. The effect of neutron irradiation on the properties of AlGaAs/GaAs laser diodes

    NASA Technical Reports Server (NTRS)

    Barnes, C. E.; Heflinger, D.; Reel, R.

    1990-01-01

    The effects of neutron irradiation on several properties of both single and multiple stripe laser diodes have been examined. Prior to fast neutron irradiation, total light output as a function of laser current, threshold current, near-field pattern, far-field pattern, and laser output wavelength spectra were measured at room temperature. These measurements were then repeated at intermittent neutron fluence levels. It was observed that the threshold current increased with neutron fluence for all devices examined. In contrast, neutron irradiation had only an indirect effect on the remainder of the laser diode properties in that the higher currents required for operation after irradiation caused variations in these properties.

  2. Microstructures of deformed VTiCrSi type alloys after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Satou, Manabu; Abe, Katsunori; Kayano, Hideo

    1996-10-01

    The alloy of V5Ti5Cr1SiAl,Y (nominal composition, weight percentage) was developed to improve oxidation properties and high temperature strength, and has been studied as one of the candidates for fusion applications. This alloy showed low swelling properties and enough tensile ductility after neutron irradiation to high fluence levels. The dislocation microstructures after tensile deformation and defect microstructures in the neutron-irradiated alloy to high fluences were studied. Irradiation was conducted in the Materials Open Test Assembly of the Fast Flux Test Facility (FFTF/MOTA-2A) at 406°C to 46 dpa and the deformation microstructures were examined by transmission electron microscopy. Slip dislocations were developed inhomogeneously in the specimen deformed at ambient temperature after neutron irradiation. Dislocation loops contributed mainly to hardening of the alloy after irradiation; however, cavities and radiation-induced precipitates did not so much.

  3. A review of irradiation effects on LWR core internal materials - neutron embrittlement.

    SciTech Connect

    Chopra, O. K.; Rao, A. S.

    2011-05-01

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of light water reactor (LWR) pressure vessels because of their relatively high strength, ductility, and fracture toughness. However, exposure to neutron irradiation for extended periods not only changes the microstructure and microchemistry of these steels, but also degrades their fracture properties. The existing data on irradiated austenitic SSs are reviewed to determine the effects of key parameters such as material type and condition and irradiation temperature, dose, and dose rate on neutron embrittlement. Differences in the radiation-induced degradation of fracture properties between LWR and fast-reactor irradiations are also discussed. The results are used to (a) define a threshold fluence above which irradiation effects on fracture toughness of the material are significant, (b) evaluate the potential of neutron embrittlement under LWR operating conditions, and (c) assess the potential effects of voids on fracture toughness.

  4. Model of defect reactions and the influence of clustering in pulse-neutron-irradiated Si

    SciTech Connect

    Myers, S. M.; Cooper, P. J.; Wampler, W. R.

    2008-08-15

    Transient reactions among irradiation defects, dopants, impurities, and carriers in pulse-neutron-irradiated Si were modeled taking into account the clustering of the primal defects in recoil cascades. Continuum equations describing the diffusion, field drift, and reactions of relevant species were numerically solved for a submicrometer spherical volume, within which the starting radial distributions of defects could be varied in accord with the degree of clustering. The radial profiles corresponding to neutron irradiation were chosen through pair-correlation-function analysis of vacancy and interstitial distributions obtained from the binary-collision code MARLOWE, using a spectrum of primary recoil energies computed for a fast-burst fission reactor. Model predictions of transient behavior were compared with a variety of experimental results from irradiated bulk Si, solar cells, and bipolar-junction transistors. The influence of defect clustering during neutron bombardment was further distinguished through contrast with electron irradiation, where the primal point defects are more uniformly dispersed.

  5. A review of irradiation effects on LWR core internal materials - Neutron embrittlement

    NASA Astrophysics Data System (ADS)

    Chopra, O. K.; Rao, A. S.

    2011-05-01

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of light water reactor (LWR) pressure vessels because of their relatively high strength, ductility, and fracture toughness. However, exposure to neutron irradiation for extended periods not only changes the microstructure and microchemistry of these steels, but also degrades their fracture properties. The existing data on irradiated austenitic SSs are reviewed to determine the effects of key parameters such as material type and condition and irradiation temperature, dose, and dose rate on neutron embrittlement. Differences in the radiation-induced degradation of fracture properties between LWR and fast-reactor irradiations are also discussed. The results are used to (a) define a threshold fluence above which irradiation effects on fracture toughness of the material are significant, (b) evaluate the potential of neutron embrittlement under LWR operating conditions, and (c) assess the potential effects of voids on fracture toughness.

  6. Neutron irradiated uranium silicides studied by neutron diffraction and Rietveld analysis

    SciTech Connect

    Birtcher, R.C.; Mueller, M.H.; Richardson, J.W. Jr.

    1990-11-01

    The irradiation behavior of high-density uranium silicides has been a matter of interest to the nuclear industry for use in high power or low enrichment applications. Transmission electron microscopy studies have found that heavy ion bombardment renders U{sub 3}Si and U{sub 3}Si{sub 2} amorphous at temperatures below about 250 C and that U{sub 3}Si becomes mechanically unstable suffering rapid growth by plastic flow. In this present work, crystallographic changes preceding amorphization by fission fragment damage have been studied by high-resolution neutron diffraction as a function of damage produced by uranium fission at room temperature. Initially, both silicides had tetragonal crystal structures. Crystallographic and amorphous phases were studied simultaneously by combining conventional Rietveld refinement of the crystallographic phases with Fourier-filtering analysis of the non-crystalline scattering component. 13 refs., 5 figs.

  7. Effect of neutron irradiation on the mechanical properties of weld overlay cladding for reactor pressure vessel

    NASA Astrophysics Data System (ADS)

    Tobita, Tohru; Udagawa, Makoto; Chimi, Yasuhiro; Nishiyama, Yutaka; Onizawa, Kunio

    2014-09-01

    This study investigates the effects of high fluence neutron irradiation on the mechanical properties of two types of cladding materials fabricated using the submerged-arc welding and electroslag welding methods. The tensile tests, Charpy impact tests, and fracture toughness tests were conducted before and after the neutron irradiation with a fluence of 1 × 1024 n/m2 at 290 °C. With neutron irradiation, we could observe an increase in the yield strength and ultimate strength, and a decrease in the total elongation. All cladding materials exhibited ductile-to-brittle transition behavior during the Charpy impact tests. A reduction in the Charpy upper-shelf energy and an increase in the ductile-to-brittle transition temperature was observed with neutron irradiation. There was no obvious decrease in the elastic-plastic fracture toughness (JIc) of the cladding materials upon irradiation with high neutron fluence. The tearing modulus was found to decrease with neutron irradiation; the submerged-arc-welded cladding materials exhibited low JIc values at high temperatures.

  8. PROCESSES FOR SEPARATING AND RECOVERING CONSTITUENTS OF NEUTRON IRRADIATED URANIUM

    DOEpatents

    Connick, R.E.; Gofman, J.W.; Pimentel, G.C.

    1959-11-10

    Processes are described for preparing plutonium, particularly processes of separating plutonium from uranium and fission products in neutron-irradiated uraniumcontaining matter. Specifically, plutonium solutions containing uranium, fission products and other impurities are contacted with reducing agents such as sulfur dioxide, uranous ion, hydroxyl ammonium chloride, hydrogen peroxide, and ferrous ion whereby the plutoninm is reduced to its fluoride-insoluble state. The reduced plutonium is then carried out of solution by precipitating niobic oxide therein. Uranium and certain fission products remain behind in the solution. Certain other fission products precipitate along with the plutonium. Subsequently, the plutonium and fission product precipitates are redissolved, and the solution is oxidized with oxidizing agents such as chlorine, peroxydisulfate ion in the presence of silver ion, permanganate ion, dichromate ion, ceric ion, and a bromate ion, whereby plutonium is oxidized to the fluoride-soluble state. The oxidized solution is once again treated with niobic oxide, thus precipitating the contamirant fission products along with the niobic oxide while the oxidized plutonium remains in solution. Plutonium is then recovered from the decontaminated solution.

  9. Radioxenon production through neutron irradiation of stable xenon gas

    SciTech Connect

    Haas, Derek A.; Biegalski, Steven R.; Foltz Biegalski, Kendra M.

    2009-12-01

    The Spectral Deconvolution Analysis Tool (SDAT) software was developed to improve counting statistics and detection limits for nuclear explosion radionuclide measurements. SDAT utilizes spectral deconvolution spectroscopy techniques and can analyze both β-γ coincidence spectra for radioxenon isotopes and high-resolution HPGe spectra from aerosol monitors. The deconvolution algorithm of the SDAT requires a library of β-γ coincidence spectra of individual radioxenon isotopes to determine isotopic ratios in a sample. In order to get experimentally produced spectra of the individual isotopes we have irradiated enriched samples of 130Xe, 132Xe, and 134Xe gas with a neutron beam from the TRIGA reactor at The University of Texas. The samples produced were counted in an Automated Radioxenon Sampler/Analyzer (ARSA) style β-γ coincidence detector. The spectra produced show that this method of radioxenon production yields samples with very high purity of the individual isotopes for 131mXe and 135Xe and a sample with a substantial 133mXe to 133Xe ratio.

  10. Boron neutron capture enhancement (BNCE) of fast neutron irradiation for glioblastoma: increase of thermal neutron flux with heavy material collimation, a theoretical evaluation.

    PubMed

    Paquis, P; Pignol, J P; Lonjon, M; Brassart, N; Courdi, A; Chauvel, P; Grellier, P; Chatel, M

    1999-01-01

    Despite the fact that fast neutron irradiation of glioblastoma has shown on autopsies an ability to sterilize tumors, no therapeutic windows have been found for these particles due to their toxicity toward normal brain. Therefore, the Boron Neutron Capture Enhancement (BNCE) of fast neutron beam has been suggested. This paper addresses the problem of fast neutron beam collimation, which induces a dramatic decrease of the thermal neutron flux in the depth of the tissues when smaller irradiation fields are used. Thermoluminescent dosimeter TLD-600 and TLD-700 were used to determine the thermal neutron flux within a Plexiglas phantom irradiated under the Nice Biomedical Cyclotron p(60)+Be(32) fast neutron beam. A BNCE of 4.6% in physical dose was determined for a 10 x 10 cm2 field, and of 10.4% for a 20 x 20 cm2 one. A Dose Modification Factor of 1.19 was calculated for CAL 58 glioblastoma cells irradiated thanks to the larger field. In order to increase the thermal flux in depth while shaping the beam, heavy material collimation was studied with Monte Carlo simulations using coupled FLUKA and MCNP-4A codes. The use of 20 cm width lead blocks allowed a 2 fold thermal neutron flux increase in the depth of the phantom, while shielding the fast neutron beam with a fast neutron dose transmission of 23%. Using the DMF of 1.19, a BNCE of 40% was calculated in the beam axis. This enhancement might be sufficient to open, at least theoretically, a therapeutic window. PMID:10222419

  11. Behavior of structural and target materials irradiated in spallation neutron environments

    SciTech Connect

    Stubbins, J.F.; Wechsler, M.; Borden, M.; Sommer, W.F.

    1995-05-01

    This paper describes considerations for selection of structural and target materials for accelerator-driven neutron sources. Due to the operating constraints of proposed accelerator-driven neutron sources, the criteria for selection are different than those commonly applied to fission and fusion systems. Established irradiation performance of various alloy systems is taken into account in the selection criteria. Nevertheless, only limited materials performance data are available which specifically related to neutron energy spectra anticipated for spallation sources.

  12. Irradiation performance of HTGR fuel in HFIR experiment HRB-13

    SciTech Connect

    Tiegs, T.N.

    1982-03-01

    Irradiation capsule HRB-13 tested High-Temperature Gas-Cooled Reactor (HTGR) fuel under accelerated conditions in the High Flux Isotope Reactor (HFIR) at ORNL. The ORNL part of the capsule was designed to provide definitive results on how variously misshapen kernels affect the irradiation performance of weak-acid-resin (WAR)-derived fissile fuel particles. Two batches of WAR fissile fuel particles were Triso-coated and shape-separated into four different fractions according to their deviation from spericity, which ranged from 9.6 to 29.7%. The fissile particles were irradiated for 7721 h. Heavy-metal burnups ranged from 80 to 82.5% FIMA (fraction of initial heavy-metal atoms). Fast neutron fluences (>0.18 MeV) ranged from 4.9 x 10/sup 25/ neutrons/m/sup 2/ to 8.5 x 10/sup 25/ neutrons/m/sup 2/. Postirradiation examination showed that the two batches of fissile particles contained chlorine, presumably introduced during deposition of the SiC coating.

  13. Temperature dependence of the deformation behavior of 316 stainless steel after low temperature neutron irradiation

    SciTech Connect

    Pawel-Robertson, J.E.; Rowcliffe, A.F.; Grossbeck, M.L.

    1996-10-01

    The effects of low temperature neutron irradiation on the tensile behavior of 316 stainless steel have been investigated. A single heat of solution annealed 316 was irradiated to 7 and 18 dpa at 60, 200, 330, and 400{degrees}C. The tensile properties as a function of dose and as a function of temperature were examined. Large changes in yield strength, deformation mode, strain to necking, and strain hardening capacity were seen in this irradiation experiment. The magnitudes of the changes are dependent on both irradiation temperature and neutron dose. Irradiation can more than triple the yield strength over the unirradiated value and decrease the strain to necking (STN) to less than 0.5% under certain conditions. A maximum increase in yield strength and a minimum in the STN occur after irradiation at 330{degrees}C but the failure mode remains ductile.

  14. Irradiation creep of nano-powder sintered silicon carbide at low neutron fluences

    SciTech Connect

    Koyanagi, Takaaki; Shimoda, Kazuya; Kondo, Sosuke; Hinoki, Tatsuya; Ozawa, Kazumi; Katoh, Yutai

    2014-12-01

    The irradiation creep behavior of nano-powder sintered silicon carbide was investigated using the bend stress relaxation method under neutron irradiation up to 1.9 dpa. The creep deformation was observed at all temperatures ranging from 380 to 1180 °C mainly from the irradiation creep but with the increasing contributions from the thermal creep at higher temperatures. Microstructural observation and data analysis were performed.

  15. Correlating radiation exposure with embrittlement: Comparative studies of electron- and neutron-irradiated pressure vessel alloys

    SciTech Connect

    Alexander, D. E.; Rehn, L. E.; Odette, G. R.; Lucas, G. E.; Klingensmith, D.; Gragg, D.

    1999-12-22

    Comparative experiments using high energy (10 MeV) electrons and test reactor neutrons have been undertaken to understand the role that primary damage state has on hardening (embrittlement) induced by irradiation at 300 C. Electrons produce displacement damage primarily by low energy atomic recoils, while fast neutrons produce displacements from considerably higher energy recoils. Comparison of changes resulting from neutron irradiation, in which nascent point defect clusters can form in dense cascades, with electron irradiation, where cascade formation is minimized, can provide insight into the role that the in-cascade point defect clusters have on the mechanisms of embrittlement. Tensile property changes induced by 10 MeV electrons or test reactor neutron irradiations of unalloyed iron and an Fe-O.9 wt.% Cu-1.0 wt.% Mn alloy were examined in the damage range of 9.0 x 10{sup {minus}5} dpa to 1.5 x 10{sup {minus}2} dpa. The results show the ternary alloy experienced substantially greater embrittlement in both the electron and neutron irradiate samples relative to unalloyed iron. Despite their disparate nature of defect production similar embrittlement trends with increasing radiation damage were observed for electrons and neutrons in both the ternary and unalloyed iron.

  16. Extinction Coefficient of Optical Fibers Irradiated by Thermal Neutrons and Compressed

    NASA Astrophysics Data System (ADS)

    Ospanova, N. A.; Kemel'bekov, B. Zh.; Bakhtiyarova, E. A.; Zhetpisbaeva, A. T.; Kulakaeva, A. E.; Kosyakov, I. O.

    2015-07-01

    Results of experimental studies of the extinction coefficient of optical fibers preliminary irradiated by thermal neutrons and compressed are presented. In this case, mechanical stresses arising in the multimode optical fiber (MOF) irradiated by thermal neutrons lead to further increase in the extinction coefficients. It is established that with increasing loading on the irradiated multimode optical fiber, the extinction coefficient changes in a wide range of wavelengths. Microfractures of the multimode optical fiber subjected to compression take place with a certain delay relative to the instant of maximum force application. This can be caused by the inertia of the process of mechanical failure of the MOF.

  17. Behaviour of neutron irradiated beryllium during temperature excursions up to and beyond its melting temperature

    NASA Astrophysics Data System (ADS)

    Pajuste, Elina; Kizane, Gunta; Avotiņa, Līga; Zariņš, Artūrs

    2015-10-01

    Beryllium pebble behaviour has been studied regarding the accidental operation conditions of tritium breeding blanket of fusion reactors. Structure evolution, oxidation and thermal properties have been compared for nonirradiated and neutron irradiated beryllium pebbles during thermal treatment in a temperature range from ambient temperature to 1600 K. For neutron irradiated pebbles tritium release process was studied. Methods of temperature programmed tritium desorption (TPD) in combination with thermogravimetry (TG) and temperature differential analysis (TDA), scanning electron microscopy (SEM) in combination with Energy Dispersive X-ray analysis (EDX) have been used. It was found that there are strong relation between tritium desorption spectra and structural evolution of neutron irradiated beryllium. The oxidation rate is also accelerated by the structure damages caused by neutrons.

  18. 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

  19. Techniques for the separation of neutron and gamma irradiations in thermoluminescent LiF

    SciTech Connect

    Abhold, M.E.

    1987-01-01

    The light emission spectra from thermoluminescent LiF in the form of TLD-100 is investigated for irradiations from Cs-137 gammas, thermal neutrons, and Am-241 alphas. The light emission spectra for thermal neutron and Cs-137 gamma irradiations is observed to be identical over the spectral range from 300 nm to 660 nm. The spectral observed for Am-241 alpha irradiations exhibit an enhancement in the spectral region from 520 nm to 600 nm with respect to the gamma and thermal neutron irradiations. This enhancement is shown to be due to contaminants on the surface of the TLD most likely introduced by the standard cleansing rinse in Methanol. The design of a carbon dioxide laser heated TLD reader developed to observe the light emission spectrum of LiF is presented. The TLD reader is shown to exhibit excellent reproducibility in the heating rate, which allows for a repeatability in radiation dose measurements of less than two percent.

  20. State of beryllium after irradiation at low temperature up to extremely high neutron doses

    NASA Astrophysics Data System (ADS)

    Chakin, V. P.; Kupryanov, I. B.; Melder, R. R.

    2004-08-01

    A study was made for four beryllium grades manufactured in Russia by hot extrusion (HE) and hot isostatic pressing (HIP) methods. Irradiation of specimens in the SM-3 reactor at a temperature of 70 °C up to a neutron fluence of (0.6-11.1) × 10 22 cm -2 ( E>0.1 eV) was performed and followed by post irradiation examination. The obtained results do not provide evidence of the advantage of one beryllium grade over another in terms of resistance to radiation damage in the fission reactor. In particular, neutron irradiation leads to absolutely brittle failure of all investigated beryllium specimens, according to the results of mechanical tensile and compression tests. Swelling of all grades at the maximum neutron dose does not exceed 1-2%. Some difference among the irradiated beryllium grades becomes apparent only in the brittle strength level.

  1. Nitrogen-promoted formation of graphite-like aggregations in SiC during neutron irradiation

    SciTech Connect

    Wang, P. F.; Ruan, Y. F.; Huang, L.; Zhu, W.

    2012-03-15

    The undoped and nitrogen-doped SiC bulk crystals irradiated with two neutron fluences were investigated by using confocal micro-Raman spectroscopy to analyze the effect of nitrogen impurity on irradiation damage. We found that the nitrogen impurity can promote the segregation of carbon atoms into graphite during heavy neutron irradiation, demonstrated by the presence of typical D and G graphite bands. Further experimental analysis indicated that the graphite-like aggregations uniformly distribute in SiC and possess much inferior thermal stability to crystalline graphite. The nucleation, namely generation of stable sp{sup 2} C=C configuration induced by nitrogen atoms, and growth during neutron irradiation can account for the formation of graphite-like aggregations.

  2. Radiological risks from irradiation of cargo contents with EURITRACK neutron inspection systems

    NASA Astrophysics Data System (ADS)

    Giroletti, E.; Bonomi, G.; Donzella, A.; Viesti, G.; Zenoni, A.

    2012-07-01

    The radiological risk for the population related to the neutron irradiation of cargo containers with a tagged neutron inspection system has been studied. Two possible effects on the public health have been assessed: the modification of the nutritional and organoleptic properties of the irradiated materials, in particular foodstuff, and the neutron activation of consumer products (i.e. food and pharmaceuticals). The result of this study is that irradiation of food and foodstuff, pharmaceutical and medical devices in container cargoes would neither modify the properties of the irradiated material nor produce effective doses of concern for public health. Furthermore, the dose received by possible stowaways present inside the container during the inspection is less than the annual effective dose limit defined by European Legislation for the public.

  3. High-dose neutron irradiation performance of dielectric mirrors

    SciTech Connect

    Nimishakavi Anantha Phani Kiran Kumar; Leonard, Keith J.; Jellison, Jr., Gerald Earle; Snead, Lance Lewis

    2015-05-01

    The study presents the high-dose behavior of dielectric mirrors specifically engineered for radiation-tolerance: alternating layers of Al2O3/SiO2 and HfO2/SiO2 were grown on sapphire substrates and exposed to neutron doses of 1 and 4 dpa at 458 10K in the High Flux Isotope Reactor (HFIR). In comparison to previously reported results, these higher doses of 1 and 4 dpa results in a drastic drop in optical reflectance, caused by a failure of the multilayer coating. HfO2/SiO2 mirrors failed completely when exposed to 1 dpa, whereas the reflectance of Al2O3/SiO2 mirrors reduced to 44%, eventually failing at 4 dpa. Transmission electron microscopy (TEM) observation of the Al2O3/SiO2 specimens showed SiO2 layer defects which increases size with irradiation dose. The typical size of each defect was 8 nm in 1 dpa and 42 nm in 4 dpa specimens. Buckling type delamination of the interface between the substrate and first layer was typically observed in both 1 and 4 dpa HfO2/SiO2 specimens. Composition changes across the layers were measured in high resolution scanning-TEM mode using energy dispersive spectroscopy. A significant interdiffusion between the film layers was observed in Al2O3/SiO2 mirror, though less evident in HfO2/SiO2 system. Lastly, the ultimate goal of this work is the provide insight into the radiation-induced failure mechanisms of these mirrors.

  4. High-dose neutron irradiation performance of dielectric mirrors

    DOE PAGESBeta

    Nimishakavi Anantha Phani Kiran Kumar; Leonard, Keith J.; Jellison, Jr., Gerald Earle; Snead, Lance Lewis

    2015-05-01

    The study presents the high-dose behavior of dielectric mirrors specifically engineered for radiation-tolerance: alternating layers of Al2O3/SiO2 and HfO2/SiO2 were grown on sapphire substrates and exposed to neutron doses of 1 and 4 dpa at 458 10K in the High Flux Isotope Reactor (HFIR). In comparison to previously reported results, these higher doses of 1 and 4 dpa results in a drastic drop in optical reflectance, caused by a failure of the multilayer coating. HfO2/SiO2 mirrors failed completely when exposed to 1 dpa, whereas the reflectance of Al2O3/SiO2 mirrors reduced to 44%, eventually failing at 4 dpa. Transmission electron microscopymore » (TEM) observation of the Al2O3/SiO2 specimens showed SiO2 layer defects which increases size with irradiation dose. The typical size of each defect was 8 nm in 1 dpa and 42 nm in 4 dpa specimens. Buckling type delamination of the interface between the substrate and first layer was typically observed in both 1 and 4 dpa HfO2/SiO2 specimens. Composition changes across the layers were measured in high resolution scanning-TEM mode using energy dispersive spectroscopy. A significant interdiffusion between the film layers was observed in Al2O3/SiO2 mirror, though less evident in HfO2/SiO2 system. Lastly, the ultimate goal of this work is the provide insight into the radiation-induced failure mechanisms of these mirrors.« less

  5. Tensile property changes of metals irradiated to low doses with fission, fusion and spallation neutrons

    SciTech Connect

    Heinisch, H.L.; Hamilton, M.L.; Sommer, W.F.; Ferguson, P.D.

    1991-11-01

    Radiation effects due to low doses of spallation neutrons are compared directly to those produced by fission and fusion neutrons. Yield stress changes of pure Cu, alumina-dispersion-strengthened Cu and AISI 316 stainless steel irradiated at 36--55{degrees}C in the Los Alamos Spallation Radiation Effects Facility (LASREF) are compared with earlier results of irradiations at 90{degrees}C using 14 MeV D-T fusion neutrons at the Rotating Target Neutron Source and fission reactor neutrons in the Omega West Reactor. At doses up to 0.04 displacements per atom (dpa), the yield stress changes due to the three quite different neutron spectra correlate well on the basis of dpa in the stainless steel and the Cu alloy. However, in pure Cu, the measured yield stress changes due to spallation neutrons were anomalously small and should be verified by additional irradiations. With the exception of pure Cu, the low dose, low temperature experiments reveal no fundamental differences in radiation hardening by fission, fusion or spallation neutrons when compared on the basis of dpa.

  6. MCNP study for epithermal neutron irradiation of an isolated liver at the Finnish BNCT facility.

    PubMed

    Kotiluoto, P; Auterinen, I

    2004-11-01

    A successful boron neutron capture treatment (BNCT) of a patient with multiple liver metastases has been first given in Italy, by placing the removed organ into the thermal neutron column of the Triga research reactor of the University of Pavia. In Finland, FiR 1 Triga reactor with an epithermal neutron beam well suited for BNCT has been extensively used to irradiate patients with brain tumors such as glioblastoma and recently also head and neck tumors. In this work we have studied by MCNP Monte Carlo simulations, whether it would be beneficial to treat an isolated liver with epithermal neutrons instead of thermal ones. The results show, that the epithermal field penetrates deeper into the liver and creates a build-up distribution of the boron dose. Our results strongly encourage further studying of irradiation arrangement of an isolated liver with epithermal neutron fields. PMID:15308144

  7. Neutron irradiation of Am-241 effectively produces curium

    NASA Technical Reports Server (NTRS)

    Anderson, R. W.; Milstead, J.; Stewart, D. C.

    1967-01-01

    Computer study was made on the production of multicurie amounts of highly alpha-active curium 242 from americium 241 irradiation. The information available includes curium 242 yields, curium composition, irradiation data, and production techniques and safeguards.

  8. Shuffler instruments for the nondestructive assay of fissile materials

    SciTech Connect

    Rinard, P.M.

    1991-05-01

    A shuffler is a nondestructive assay instrument used to determine the fissile content of materials. It places an isotopic source of neutrons near the material to induce fissions, withdraws the source, and counts the delayed neutrons. The source is shuffled until a sufficient number of delayed neutrons have been counted. The shuffler technique is generally applied to difficult assay cases. The amount of material present may be very small (a few milligrams), and thus it does not spontaneously emit neutrons of consequence; the amount of material is also below an active well counter's level of sensitivity. On the other hand, the fissile amount may be fairly large, but the rate of spontaneously emitted neutrons may still be low (so a passive neutron count will not work) or the highest assay precision may be desired (favoring a shuffler over an active well counter) even if the material is inhomogeneous (making it difficult to interrogate with thermal neutrons). In all these cases, gamma-ray backgrounds, self- shielding, or matrix effects can make gamma-ray assays impractical. Materials ranging from highly radioactive spent-fuel assemblies to low-level waste drums have been assayed with shufflers, as have leached hulls, various process materials, scrap, and waste. This report presents a theoretical background for shufflers and describes techniques for practical applications. Procedures for assaying mixtures of fissile isotopes, inhomogeneous materials, and flowing liquids are discussed. It is shown how the precision and limits of detection of a shuffler can be calculated for a given neutron background rate. A section on data analysis gives a stepwise procedure for converting the measured counts into an assay value, including random, systematic, and total uncertainties. 31 refs.

  9. Microstructure evolution in austenitic Fe-Cr-Ni alloys irradiated with rotons: comparison with neutron-irradiated microstructures

    NASA Astrophysics Data System (ADS)

    Gan, J.; Was, G. S.

    2001-08-01

    Irradiation-induced microstructures of high purity and commercial purity austenitic stainless steels were investigated using proton-irradiation. For high purity alloys, Fe-20Cr-9Ni (HP 304 SS), Fe-20Cr-24Ni and Ni-18Cr-9Fe were irradiated using 3.2 MeV protons between 300°C and 600°C at a dose rate of 7×10 -6 dpa/ s to doses up to 3.0 dpa. The commercial purity alloys, CP 304 SS and CP 316 SS were irradiated at 360°C to doses between 0.3 and 5.0 dpa. The dose, temperature and composition dependence of the number density and size of dislocation loops and voids were characterized. The changes in yield strength due to irradiation were estimated from Vickers hardness measurements and compared to calculations using a dispersed-barrier-hardening (DBH) model. The dose and temperature dependence of proton-irradiated microstructure (loops, voids) and the irradiation hardening are consistent with the neutron-data trend. Results indicate that proton-irradiation can accurately reproduce the microstructure of austenitic alloys irradiated in LWR cores.

  10. Microstructure of V-4Cr-4Ti following low temperature neutron irradiation

    SciTech Connect

    Rice, P.M.; Snead, L.L.; Alexander, D.J.; Zinkle, S.J.

    1996-12-31

    The V-4Cr-4Ti alloys displays excellent mechanical properties, including a ductile-to-brittle transition temperature (DBTT) below - 200 C in the unirradiated conditions. Samples were fission neutron- irradiated in HFBR to a 0.4 dpa dose at 100-275 C. Mechanical tests showed significant irradiation hardening which increased with irradiation temperature. Charpy impact testing also showed a dramatic increase in DBTT on the order of 100 to 350 C. The mechanical property changes are correlated with preliminary results from TEM analysis of the defect microstructure resulting from the low-dose neutron irradiations. TEM of the irradiated material showed a nearly constant defect density of {approximately}1.6x10{sup 23}m{sup -3}, with an average defect diameter of slightly greater than 3 nm.

  11. Biological effectiveness of neutron irradiation on animals and man

    SciTech Connect

    Straume, T.

    1982-11-01

    Neutron experiments on a highly radiosensitive in vivo system - oocytes in mice - provide new insight into the nature of the radiosensitive targets of these important cells. With the radiobiological literature as background, neutron data from animals and humans are integrated, and the controversial question of radiation protection standards for neutrons is addressed. Oocyte killing in juvenile mice by 0.43-MeV, /sup 252/Cf-fission, and 15 MeV neutrons, compared with that by /sup 60/Co gamma rays, yields unusually low neutron RBEs (relative biological effectiveness). At 0.1 rad of 0.43-MeV neutrons the RBE is only 1.8, contrasting greatly with values of 100 or more reported at low-doses for other endpoints. In mice just prior to birth, however, when oocytes are less radiosensitive, the neutron RBE is much higher, similar to values for most other mammalian endpoints. This dramatic change in neutron RBE with mouse age (occurring within 2 to 3 days) can be explained as the result of a shift from a less radiosensitive target (presumably nuclear DNA) to a much more radiosensitive one (probably the oocyte plasma membrane). Using various approaches, a value for the neutron Quality Factor (Q, a radiation protection standard) is estimated as 17 (+-100%), much lower than 100 which has been suggested. With the large uncertainty, 17 is not markedly different from the value of 10 presently in general use.

  12. Plasma deposition of amorphous silicon carbide thin films irradiated with neutrons

    NASA Astrophysics Data System (ADS)

    Huran, J.; Bohacek, P.; Kucera, M.; Kleinova, A.; Sasinkova, V.; IEE SAS, Bratislava, Slovakia Team; Polymer Institute, SAS, Bratislava, Slovakia Team; Institute of Chemistry, SAS, Bratislava, Slovakia Team

    2015-09-01

    Amorphous silicon carbide and N-doped silicon carbide thin films were deposited on P-type Si(100) wafer by plasma enhanced chemical vapor deposition (PECVD) technology using silane, methane, ammonium and argon gases. The concentration of elements in the films was determined by RBS and ERDA method. Chemical compositions were analyzed by FTIR spectroscopy. Photoluminescence properties were studied by photoluminescence spectroscopy (PL). Irradiation of samples with various neutron fluencies was performed at room temperature. The films contain silicon, carbon, hydrogen, nitrogen and small amount of oxygen. From the IR spectra, the films contained Si-C, Si-H, C-H, Si-N, N-H and Si-O bonds. No significance effect on the IR spectra after neutron irradiation was observed. PL spectroscopy results of films showed decreasing PL intensity after neutron irradiation and PL intensity decreased with increased neutron fluencies. The measured current of the prepared structures increased after irradiation with neutrons and rise up with neutron fluencies.

  13. The Effect of Neutron Irradiation on the Fracture Toughness of Graphite

    SciTech Connect

    Burchell, Timothy D; Strizak, Joe P

    2012-01-01

    As part of our irradiated graphite recycle program a small quantity of PCEA grade graphite was irradiated in the High Flux Isotope Reactor (HFIR) at ORNL. The graphite will provide the raw material for future recycle experiments. The geometry of the irradiated graphite allowed us to study the effects of neutron irradiation on the Critical Stress Intensity Factor, KIc, of graphite. The specimens where irradiated in two groups of 6 at an irradiation temperature of 900 C in rabbit capsules to doses of 6.6 and 10.2 DPA, respectively. Following a full suite of pre-and post-irradiation examination, which included dimensions, mass, electrical resistivity, elastic constants, and thermal expansion (to 800 C) the samples were notched and tested to determine their KIc using the newly approved ATSM test method for SENB fracture toughness of graphite. Here we report the irradiation induced changes in the dimensions, elastic constants, resistivity, and coefficient of thermal expansion of PCEA graphite. Moreover, irradiation induced changes in the Critical Stress Intensity Factor, KIc, or fracture toughness, are reported and discussed. Very little work on the effect of neutron irradiation on the fracture toughness of graphite has previously be performed or reported.

  14. Dosimetric characterization of the irradiation cavity for accelerator-based in vivo neutron activation analysis.

    PubMed

    Byun, S H; Pejović-Milić, A; McMaster, S; Matysiak, W; Aslam; Liu, Z; Watters, L M; Prestwich, W V; McNeill, F E; Chettle, D R

    2007-03-21

    A neutron irradiation cavity for in vivo activation analysis has been characterized to estimate its dosimetric specifications. The cavity is defined to confine irradiation to the hand and modifies the neutron spectrum produced by a low energy accelerator neutron source to optimize activation per dose. Neutron and gamma-ray dose rates were measured with the microdosimetric technique using a tissue-equivalent proportional counter at the hand irradiation site and inside the hand access hole. For the outside of the cavity, a spherical neutron dose equivalent meter and a Farmer dosemeter were employed instead due to the low intensity of the radiation field. The maximum dose equivalent rate at the outside of the cavity was 2.94 microSv/100 microA min, which is lower by a factor of 1/2260 than the dose rate at the hand irradiation position. The local dose contributions from a hand, an arm and the rest of a body to the effective dose rate were estimated to be 1.73, 0.782 and 2.94 microSv/100 microA min, respectively. For the standard irradiation protocol of the in vivo hand activation, 300 microA min, an effective dose of 16.3 microSv would be delivered. PMID:17455391

  15. Significant disparity in base and sugar damage in DNA resulting from neutron and electron irradiation.

    PubMed

    Pang, Dalong; Nico, Jeffrey S; Karam, Lisa; Timofeeva, Olga; Blakely, William F; Dritschilo, Anatoly; Dizdaroglu, Miral; Jaruga, Pawel

    2014-11-01

    In this study, a comparison of the effects of neutron and electron irradiation of aqueous DNA solutions was investigated to characterize potential neutron signatures in DNA damage induction. Ionizing radiation generates numerous lesions in DNA, including base and sugar lesions, lesions involving base-sugar combinations (e.g. 8,5'-cyclopurine-2'-deoxynucleosides) and DNA-protein cross-links, as well as single- and double-strand breaks and clustered damage. The characteristics of damage depend on the linear energy transfer (LET) of the incident radiation. Here we investigated DNA damage using aqueous DNA solutions in 10 mmol/l phosphate buffer from 0-80 Gy by low-LET electrons (10 Gy/min) and the specific high-LET (∼0.16 Gy/h) neutrons formed by spontaneous (252)Cf decay fissions. 8-hydroxy-2'-deoxyguanosine (8-OH-dG), (5'R)-8,5'-cyclo-2'-deoxyadenosine (R-cdA) and (5'S)-8,5'-cyclo-2'-deoxyadenosine (S-cdA) were quantified using liquid chromatography-isotope-dilution tandem mass spectrometry to demonstrate a linear dose dependence for induction of 8-OH-dG by both types of radiation, although neutron irradiation was ∼50% less effective at a given dose compared with electron irradiation. Electron irradiation resulted in an exponential increase in S-cdA and R-cdA with dose, whereas neutron irradiation induced substantially less damage and the amount of damage increased only gradually with dose. Addition of 30 mmol/l 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), a free radical scavenger, to the DNA solution before irradiation reduced lesion induction to background levels for both types of radiation. These results provide insight into the mechanisms of DNA damage by high-LET (252)Cf decay neutrons and low-LET electrons, leading to enhanced understanding of the potential biological effects of these types of irradiation. PMID:25034731

  16. Controllability of depth dose distribution for neutron capture therapy at the Heavy Water Neutron Irradiation Facility of Kyoto University Research Reactor.

    PubMed

    Sakurai, Yoshinori; Kobayashi, Tooru

    2002-10-01

    The updating construction of the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor has been performed from November 1995 to March 1996 mainly for the improvement in neutron capture therapy. On the performance, the neutron irradiation modes with the variable energy spectra from almost pure thermal to epi-thermal neutrons became available by the control of the heavy-water thickness in the spectrum shifter and by the open-and-close of the cadmium and boral thermal neutron filters. The depth distributions of thermal, epi-thermal and fast neutron fluxes were measured by activation method using gold and indium, and the depth distributions of gamma-ray absorbed dose rate were measured using thermo-luminescent dosimeter of beryllium oxide for the several irradiation modes. From these measured data, the controllability of the depth dose distribution using the spectrum shifter and the thermal neutron filters was confirmed. PMID:12408308

  17. Radiation hardening of V C, V O, V N alloys neutron-irradiated to high fluences

    NASA Astrophysics Data System (ADS)

    Chuto, Toshinori; Satou, Manabu; Abe, Katsunori

    1998-10-01

    Vanadium has a large affinity for interstitial impurities such as C, N and O. Mechanical properties and irradiation performance of vanadium alloys are affected by the impurities. Radiation hardening and defect microstructures of vanadium alloys doped with relatively large amounts of these interstitial elements were studied. Neutron irradiation was conducted in the Materials Open Test Assembly of the Fast Flux Test Facility (FFTF/MOTA-1F) to 47.9 dpa at temperatures of 679, 793 and 873 K. Irradiation hardening decreased with increasing irradiation temperature. Increase in hardness for the V-C alloy was relatively greater after irradiation at the low temperatures. Decorated dislocations and voids were observed depending on the alloying elements. The factors for irradiation hardening were different for each interstitial element in the alloys irradiated at 873 K to 47.9 dpa.

  18. Neutron irradiation study of Nd-Fe-B permanent magnets made from melt-spun ribbons

    NASA Astrophysics Data System (ADS)

    Brown, R. D.; Cost, J. R.; Meisner, G. P.; Brewer, E. G.

    1988-11-01

    Radiation-induced changes in the magnetization of sintered Nd-Fe-B permanent magnets are known to vary widely among specimens produced by different manufacturers. Samples of Nd-Fe-B MAGNEQUENCH magnets, which are made from melt-spun ribbons, have not been studied and show a much reduced sensitivity to neutron irradiation than do sintered Nd-Fe-B magnets. All melt-spun ribbon-based MAGNEQUENCH magnets, i.e., epoxy-bonded, hot-pressed, and die-upset magnets, show essentially the same slow decrease in magnetic remanence with neutron dose. Measurements of the open-circuit remanence Br/Br 0 at various times during the irradiation show a decay of only 1.5% of the preirradiated value for the MAGNEQUENCH magnets after 1 h of irradiation, or a dose of 1.4×1016 neutrons/cm2, compared to a 4.6% drop in remanence for the best sintered Nd-Fe-B magnet (Sumitomo 30H) with the same irradiation dose. Moreover, after 5.3 h of irradiation, the remanence drops by only 3% for the MAGNEQUENCH magnets. Magnets made from melt-spun ribbons are thus the least sensitive to neutron irradiation so far measured for Nd-Fe-B permanent magnets, but are somewhat more sensitive than samarium-cobalt magnets.

  19. 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.

  20. Coronary arteriosclerosis and atherosclerosis in fast neutron or photon irradiated dogs

    SciTech Connect

    Bradley, E.W.; Zook, B.C.; Casarett, G.W.

    1981-08-01

    Thirty-nine adult male beagles received either fast neutron or photon irradiation to the right thorax to obtain values for the relative biological effectiveness (RBE) of fast neutrons as assessed by quantitative parameters of lung function. Fast neutrons (15 MeV avg.) were delivered in 4 fx/wk for six weeks to total doses of 1000, 1500, 2250, or 3375 rad while the photon irradiated dogs received total doses of 3000, 4500, or 6750 rad in the same fractionation schedule. The right atrium and coronary groove of the heart were included in the irradiated field. Cholesterol levels (and triglyceride levels when obtainable) were measured prior to irradiation and every three months until death. Arteries were graded (0, negative to 5, severe) for endothelial proliferation, disruption and duplication of the elastic lamina, perivascular fibrosis and the presence of foamy macrophages. All dogs that survived 75 days post-irradiation developed arterial changes; two neutron irradiated dogs showed severe atherosclerotic plaque formation. Data suggest an RBE between 4 and 5.

  1. Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation

    SciTech Connect

    Maziasz, P.J.

    1985-11-01

    This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs.

  2. Temperature dependence of the deformation behavior of type 316 stainless steel after low temperature neutron irradiation

    SciTech Connect

    Robertson, J.P.; Rowcliffe, A.F.; Grossbeck, M.L.; Ioka, Ikuo; Jitsukawa, Shiro

    1996-12-31

    A single heat of solution annealed 316 ss was irradiated to 7 and 18 dpa at 60, 200, 330, and 400 C. Tensile properties were studied vs dose and temperature. Large changes in yield strength, deformation mode, strain to necking (STN), and strain hardening capacity were seen. Magnitude of the changes are dependent on both irradiation temperature and neutron dose. Irradiation can more than triple the yield strength and decrease STN to <0.5% under certain conditions. A maximum increase in yield strength and a minimum in STN occur after irradiation at 330 C but failure mode remains ductile.

  3. A new irradiation method with a neutron filter for silicon neutron transmutation doping at the Japan research reactor no. 3 (JRR-3).

    PubMed

    Komeda, Masao; Kawasaki, Kozo; Obara, Toru

    2013-04-01

    We studied a new silicon irradiation holder with a neutron filter designed to make the vertical neutron flux profile uniform. Since an irradiation holder has to be made of a low activation material, we applied aluminum blended with B4C as the holder material. Irradiation methods to achieve uniform flux with a filter are discussed using Monte-Carlo calculation code MVP. Validation of the use of the MVP code for the holder's analyses is also discussed via characteristic experiments. PMID:23395784

  4. Photo-fission Methods to detect Fissile Materials

    NASA Astrophysics Data System (ADS)

    Johnson, Micah S.; Glenn, A.; Hartouni, E. P.; Sheets, S. A.; Soltz, R. A.; Danagoulian, A.; Korbly, S. E.; Ledoux, R. J.

    2014-09-01

    A mission objective of various national security agencies is to develop systems that can detect fissile material. There are a myriad of researchers at national laboratories, academic institutions, and industry who are investigating various methods to detect fissile materials. These methods are broken down into active or passive detection systems. Examples of active systems include neutron or photon sources to stimulate and/or scatter from materials. Our focus has been to use photons near the fission barrier of various actinides to excite fission modes and measure the correlated and uncorrelated neutrons. We will present and discuss results from recent measurements. We will present the overall results of our effort and discuss some of the open questions. A mission objective of various national security agencies is to develop systems that can detect fissile material. There are a myriad of researchers at national laboratories, academic institutions, and industry who are investigating various methods to detect fissile materials. These methods are broken down into active or passive detection systems. Examples of active systems include neutron or photon sources to stimulate and/or scatter from materials. Our focus has been to use photons near the fission barrier of various actinides to excite fission modes and measure the correlated and uncorrelated neutrons. We will present and discuss results from recent measurements. We will present the overall results of our effort and discuss some of the open questions. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  5. Deterioration of performance of neutron moderators under intense irradiation

    SciTech Connect

    Carpenter, J.M.; Cudrnak, S.S.; DeCusatis, C.M.

    1986-01-01

    In pulsed neutron sources, fixed moderators such as polyethylene and solid methane slow down fast (MeV) neutrons from the primary source to energies of use for spectroscopy (less than or equal to10 eV). Radiation-induced changes in their composition alter their spectral and pulse characteristics. We report the results of fitting time-average spectra from polyethylene and solid methane moderators in Argonne's Intense Pulsed Neutron Source as a function of total fast-neutron radiation dose. The thermal-to-epithermal flux ratio varies most significantly, while the Maxwellian energy and the parameters describing the epithermal component change only slightly. We have used modified forms of Westcott's joining function for this purpose. We provide an integral of the spectrum that is useful for determining the delayed neutron background.

  6. Correlation between locally deformed structure and oxide film properties in austenitic stainless steel irradiated with neutrons

    NASA Astrophysics Data System (ADS)

    Chimi, Yasuhiro; Kitsunai, Yuji; Kasahara, Shigeki; Chatani, Kazuhiro; Koshiishi, Masato; Nishiyama, Yutaka

    2016-07-01

    To elucidate the mechanism of irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water for neutron-irradiated austenitic stainless steels (SSs), the locally deformed structures, the oxide films formed on the deformed areas, and their correlation were investigated. Tensile specimens made of irradiated 316L SSs were strained 0.1%-2% at room temperature or at 563 K, and the surface structures and crystal misorientation among grains were evaluated. The strained specimens were immersed in high-temperature water, and the microstructures of the oxide films on the locally deformed areas were observed. The appearance of visible step structures on the specimens' surface depended on the neutron dose and the applied strain. The surface oxides were observed to be prone to increase in thickness around grain boundaries (GBs) with increasing neutron dose and increasing local strain at the GBs. No penetrative oxidation was observed along GBs or along surface steps.

  7. Determination of proton and neutron spectra in the LANSCE spallation irradiation facility

    SciTech Connect

    James, M.R.; Maloy, S.A.; Sommer, W.F.; Fowler, M.M.; Dry, D.; Ferguson, P.D.; Mueller, G.; Corzine, R.K.

    1999-06-01

    Materials samples were recently irradiated in the Los Alamos Radiation Effects Facility (LASREF) at the Los Alamos Neutron Science Center (LANSCE) to provide data for the Accelerator Production of Tritium (APT) project on the effect of irradiation on the mechanical and physical properties of materials. The targets were configured to expose samples to a variety of radiation environments including, high-energy protons, mixed protons and high-energy neutrons, and low-energy neutrons. The samples were irradiated for approximately six months during a ten month period using an 800 MeV proton beam with a circular Gaussian shape of approximately 2{sigma} = 3.0 cm. At the end of this period, the samples were extracted and tested. Activation foils were also extracted that had been placed in proximity to the materials samples. These were used to quantify the fluences in various locations.

  8. Welding-induced microstructure in austenitic stainless steels before and after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Stoenescu, R.; Schäublin, R.; Gavillet, D.; Baluc, N.

    2007-02-01

    The effects of neutron irradiation on the microstructure of welded joints made of austenitic stainless steels have been investigated. The materials were welded AISI 304 and AISI 347, so-called test weld materials, and irradiated with neutrons at 300 °C to 0.3 and 1.0 dpa. In addition, an AISI 304 type from a decommissioned pressurised water reactor, so-called in-service material, which had accumulated a maximum dose of 0.35 dpa at about 300 °C, was investigated. The microstructure of heat-affected zones and base materials was analysed before and after irradiation, using transmission electron microscopy. Neutron diffraction was performed for internal stress measurements. It was found that the heat-affected zone contains, relative to the base material, a higher dislocation density, which relates well to a higher residual stress level and, after irradiation, a higher irradiation-induced defect density. In both materials, the irradiation-induced defects are of the same type, consisting in black dots and Frank dislocation loops. Careful analysis of the irradiation-induced defect contrast was performed and it is explained why no stacking fault tetrahedra could be identified.

  9. Tensile behavior and microstructure of neutron-irradiated Mo-5% Re alloy

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira; Abe, Katsunori; Satou, Manabu; Namba, Chusei

    1995-08-01

    This work reports the effect of heat treatment on the tensile behavior and and microstructure of neutron-irradiated Mo-5% Re alloy. Stress-relived and recrystallized specimens conditions were irradiated at five temperatures between 646 and 1073 K in FFTF/MOTA. The exposure levels were in the range of 6.8 to 34 dpa depending on the irradiation temperatures. Tensile tests were carried out at room temperature and 673 K and microstructures of the irradiated specimens were observed by TEM. The Mo-5% Re alloy irradiated at high temperatures shows ductile behavior even at room temperature. The total elongation of stress-relived specimens irradiated at 873 and 1073 K ranged from 5 to 10%, and that of recrystallized specimens irradiated at 1073 K was 5%. The fracture modes of these specimens were transgranular type. Voids were observed in all of the irradiated specimens, but precipitates were found only in specimens irradiated above 792 K. It is important for the Mo sbnd Re alloy to be used in high-heat flux components of fusion reactors that the alloy showed the ductility after neutron exposures of relatively high fluences.

  10. Neutron Exposure Parameters for the Dosimetry Capsule in the Heavy-Section Steel Irradiation Program Tenth Irradiation Series

    SciTech Connect

    C.A. Baldwin; F.B.K. Kam; I. Remec

    1998-10-01

    This report describes the computational methodology for the least-squares adjustment of the dosimetry data from the HSSI 10.OD dosimetry capsule with neutronics calculations. It presents exposure rates at each dosimetry location for the neutron fluence greater than 1.0 MeV, fluence greater than 0.1 MeV, and displacements per atom. Exposure parameter distributions are also described in terms of three- dimensional fitting functions. When fitting functions are used it is suggested that an uncertainty of 6% (1 o) should be associated with the exposure rate values. The specific activity of each dosimeter at the end of irradiation is listed in the Appendix.

  11. Method and apparatus for measuring reactivity of fissile material

    DOEpatents

    Lee, David M.; Lindquist, Lloyd O.

    1985-01-01

    Given are a method and apparatus for measuring nondestructively and non-invasively (i.e., using no internal probing) the burnup, reactivity, or fissile content of any material which emits neutrons and which has fissionable components. No external neutron-emitting interrogation source or fissile material is used and no scanning is required, although if a profile is desired scanning can be used. As in active assays, here both reactivity and content of fissionable material can be measured. The assay is accomplished by altering the return flux of neutrons into the fuel assembly. The return flux is altered by changing the reflecting material. The existing passive neutron emissions in the material being assayed are used as the source of interrogating neutrons. Two measurements of either emitted neutron or emitted gamma-ray count rates are made and are then correlated to either reactivity, burnup, or fissionable content of the material being assayed, thus providing a measurement of either reactivity, burnup, or fissionable content of the material being assayed. Spent fuel which has been freshly discharged from a reactor can be assayed using this method and apparatus. Precisions of 1000 MWd/tU appear to be feasible.

  12. Neutron dosimetry and damage calculations for the ATR-A1 irradiation

    SciTech Connect

    Greenwood, L.R.; Ratner, R.T.

    1998-09-01

    Neutron fluence measurements and radiation damage calculations are reported for the collaborative US/Japan ATR-A1 irradiation in the Advanced Test Reactor (ATR) at Idaho National Engineering Laboratory (INEL). The maximum total neutron fluence at midplane was 9.4 {times} 10{sup 21} n/cm{sup 2} (5.5 {times} 10{sup 21} n/cm{sup 2} above 0.1 MeV), resulting in about 4.6 dpa in vanadium.

  13. Antiradiation Vaccine: Technology Development Of Prophylaxis, Prevention And Treatment Of Biological Consequences And Complications After Neutron Irradiation.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Maliev, Slava; Jones, Jeffrey

    Introduction: Neutrons irradiation produce a unique biological effectiveness compare to different types of radiation because their ability to create a denser trail of ionized atoms in biological living tissues[Straume 1982; Latif et al.2010; Katz 1978; Bogatyrev 1982]. The efficacy of an Anti-Radiation Vaccine for the prophylaxis, prevention and therapy of acute radiation pathology was studied in a neutron exposure facility. The biological effects of fast neutrons include damage of central nervous system and cardiovascular system with development of Acute Cerebrovascular and Cardiovascular forms of acute radiation pathology. After irradiation by high doses of fast neutron, formation of neurotoxins, hematotoxins,cytotoxins forming from cell's or tissue structures. High doses of Neutron Irradiation generate general and specific toxicity, inflammation reactions. Current Acute Medical Management and Methods of Radiation Protection are not effective against moderate and high doses of neutron irradiation. Our experiments demonstrate that Antiradiation Vaccine is the most effective radioprotectant against high doses of neutron-radiation. Radiation Toxins(biological substances with radio-mimetic properties) isolated from central lymph of gamma-irradiated animals could be working substance with specific antigenic properties for vaccination against neutron irradiation. Methods: Antiradiation Vaccine preparation standard - mixture of a toxoid form of Radiation Toxins - include Cerebrovascular RT Neurotoxin, Cardiovascular RT Neurotoxin, Gastrointestinal RT Neurotoxin, Hematopoietic RT Hematotoxin. Radiation Toxins were isolated from the central lymph of gamma-irradiated animals with different forms of Acute Radiation Syndromes - Cerebrovascular, Cardiovascular, Gastrointestinal, Hematopoietic forms. Devices for Y-radiation were "Panorama","Puma". Neutron exposure was accomplished at the Department of Research Institute of Nuclear Physics, Dubna, Russia. The neutrons

  14. Determination of mixed proton/neutron fluences in the LANSCE irradiation environment

    SciTech Connect

    James, M.R.; Maloy, S.A; Sommer, W.F.; Ferguson, P.; Fowler, M.M.; Corzine, K.

    1998-12-31

    In support of the Accelerator Production of Tritium (APT) program, several materials were exposed to a high-energy proton and spallation neutron environments. Large differences in mechanical property changes in this environment are expected compared to the typical fusion or fission systems. To make proper dose correlations, it is important to accurately quantify the fluences. Activation foils consisting of a stack of disks of Co, Ni, Fe, Al, Nb and Cu were irradiated concurrent with mechanical testing samples in the Los Alamos Spallation Radiation Effects Facility (LASREF) at the Los Alamos Neutron Science Center (LANSCE) facility. The irradiation consisted of an 800 MeV, 1 mA proton beam and a W target in the beam provided a source of spallation neutrons. The maximum proton fluence was around 3 {times} 10{sup 21} p/cm{sup 2} and the maximum neutron fluence approximately 3 {times} 10{sup 20} n/cm{sup 2}. After irradiation, the foils were withdrawn and the radioactive isotopes analyzed using gamma spectroscopy. From initial estimates for the fluences and spectra derived from the Los Alamos High-Energy Transport (LAHET) Code System (LCS), comparisons to the measured levels of activation products were made. The Na-22 activation products in the Al foils were measured from different regions of the target in order to profile the spatial levels of the fluences. These tests gave empirical confirmation of the proton and neutron fluences of the irradiated samples throughout the target region.

  15. Method and apparatus for measuring reactivity of fissile material

    DOEpatents

    Lee, D.M.; Lindquist, L.O.

    1982-09-07

    Given are a method and apparatus for measuring nondestructively and noninvasively (i.e., using no internal probing) the burnup, reactivity, or fissile content of any material which emits neutrons and which has fissionable components. The assay is accomplished by altering the return flux of neutrons into the fuel assembly by means of changing the reflecting material. The existing passive neutron emissions in the material being assayed are used as the source of interrogating neutrons. Two measurements of either emitted neutron or emitted gamma-ray count rates are made and are then correlated to either reactivity, burnup, or fissionable content of the material being assayed, thus providing a measurement of either reactivity, burnup, or fissionable content of the material being assayed. Spent fuel which has been freshly discharged from a reactor can be assayed using this method and apparatus. Precisions of 1000 MWd/tU appear to be feasible.

  16. ac susceptibility of thermally annealed and neutron irradiated Cu-Ni alloys

    NASA Technical Reports Server (NTRS)

    Catchings, R. M., III; Borg, R. J.; Violet, C. E.

    1985-01-01

    Thermal annealing and high-flux neutron irradiation are used to vary the degree of short-range atomic order in Cu-Ni alloys of composition 40, 50, and 60 at. pct Ni. The magnetic state is measured by ac magnetic susceptibility measurements. It is shown that annealing at 350 C causes significant changes in the susceptibility of all the samples. In the 50 and 60 at. pct Ni samples, the transition is broadened and extended to higher temperatures, while the 40 at. pct Ni sample changes from a paramagnetic system to a weakly ferromagnetic system. The neutron irradiation, in contrast to the thermal treatment, causes the development of smaller size cluster formations. The irradiated 60 at. pct Ni sample exhibits no change in the shape of its susceptibility curve from that of the quenched sample, whereas, the 40 pct alloy is changed, by irradiation, from a paramagnetic system to a spin-glass system.

  17. Effects of silicon, carbon and molybdenum additions on IASCC of neutron irradiated austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Nakano, J.; Miwa, Y.; Kohya, T.; Tsukada, T.

    2004-08-01

    To study the effects of minor elements on irradiation assisted stress corrosion cracking (IASCC), high purity type 304 and 316 stainless steels (SSs) were fabricated and minor elements, Si or C were added. After neutron irradiation to 3.5 × 10 25 n/m 2 ( E>1 MeV), slow strain rate tests (SSRTs) of irradiated specimens were conducted in oxygenated high purity water at 561 K. Specimen fractured surfaces were examined using a scanning electron microscope (SEM) after the SSRTs. The fraction of intergranular stress corrosion cracking (IGSCC) on the fractured surface after the SSRTs increased with neutron fluence. In high purity SS with added C, the fraction of IGSCC was the smallest in the all SSs, although irradiation hardening level was the largest of all the SSs. Addition of C suppressed the susceptibility to IGSCC.

  18. Additive analysis of nano silicon under the influence of neutron irradiation

    NASA Astrophysics Data System (ADS)

    Garibli, Aydan; Huseynov, Elchin; Garibov, Adil; Mehdiyeva, Ravan

    2016-04-01

    Nano silicon with 80m2g‑1 specific surface area, 100 nm size and 0.08 g/cm3 density has been irradiated continuously with neutrons (2 × 1013n ṡcm‑2s‑1) up to 20 h at various periods in TRIGA Mark II type research reactor. After the neutron irradiation, cooling time of the samples is taken approximately 360 h. It is found that the initial radioactivity of the irradiated samples changes within 0.1 kBq-3.1 GBq range. Definition of elements’ concentration is determined based on the activities formed in the relevant energy range. After the irradiation, the result of activity analysis carried out the element content of 1% mixture existing in nano Si which has been defined with radionuclides of the relevant element. Moreover, from activities of mixed radioisotopes, their amounts in percentage has been determined.

  19. Neutron irradiation effects on the ductile-brittle transition of ferritic/martensitic steels

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.

    1997-08-01

    Ferritic/martensitic steels such as the conventional 9Cr-1MoVNb (Fe-9Cr-1Mo-0.25V-0.06Nb-0.1C) and 12Cr-1MoVW (Fe-12Cr-1Mo-0.25V-0.5W-0.5Ni-0.2C) steels have been considered potential structural materials for future fusion power plants. The major obstacle to their use is embrittlement caused by neutron irradiation. Observations on this irradiation embrittlement is reviewed. Below 425-450{degrees}C, neutron irradiation hardens the steels. Hardening reduces ductility, but the major effect is an increase in the ductile-brittle transition temperature (DBTT) and a decrease in the upper-shelf energy, as measured by a Charpy impact test. After irradiation, DBTT values can increase to well above room temperature, thus increasing the chances of brittle rather than ductile fracture.

  20. Stochastic annealing simulation of copper under neutron irradiation

    SciTech Connect

    Heinisch, H.L.; Singh, B.N.

    1998-03-01

    This report is a summary of a presentation made at ICFRM-8 on computer simulations of defect accumulation during irradiation of copper to low doses at room temperature. The simulation results are in good agreement with experimental data on defect cluster densities in copper irradiated in RTNS-II.

  1. Location and chemical bond of radionuclides in neutron-irradiated nuclear graphite

    NASA Astrophysics Data System (ADS)

    Vulpius, D.; Baginski, K.; Fischer, C.; Thomauske, B.

    2013-07-01

    The locations and the chemical forms (chemical bonds) of radionuclides in neutron-irradiated nuclear graphite have been determined in order to develop principal strategies for the management of graphitic nuclear waste. Due to the relatively low concentration of radionuclides in neutron-irradiated nuclear graphite (<1 ppm) direct spectroscopic methods are not applicable to investigate chemical structures. Therefore, methods by analogy have been applied. Such methods are investigations of the chemically detectable precursors of radionuclides in neutron-irradiated nuclear graphite and subjection of irradiated graphite to different chemical reactions followed by measurements of the radionuclide-containing reaction products by sensitive radiochemical methods. The paper discusses the applicability of these methods. The radionuclides investigated in this study can be divided into three parts: tritium, radiocarbon and metallic activation and fission products. Tritium can be bound in neutron-irradiated nuclear graphite as strongly adsorbed tritiated water (HTO), in oxygen-containing functional groups (e.g. C-OT) and as hydrocarbons (C-T). Radiocarbon is covalently bound with the graphite structure. The activity can be described by a homogeneously distributed part and a heterogeneously distributed part (enriched on surfaces or in hotspots). Metallic radionuclides can be bound as ions or covalent metal-carbon compounds. The distribution of all these radionuclides is mainly dependent on the distribution of their inactive precursors.

  2. Simulation of neutron-induced damage in tungsten by irradiation with energetic self-ions

    NASA Astrophysics Data System (ADS)

    Ogorodnikova, O. V.; Gann, V.

    2015-05-01

    A direct comparison of the deuterium (D) decoration of radiation-induced damage in polycrystalline tungsten irradiated with self-ions [present work] and neutrons in the high-flux isotope reactor (HFIR) (Hatano et al., 2013) shows a reasonably good agreement at least up to 0.3 displacement per atom indicating that MeV heavy ions can be a good proxy to simulate neutron-produced damage at room temperature and low dpa. The coefficient of similarity between two kinds of irradiation was obtained experimentally to be Kexp ∼ 0.65 ± 0.1 in the case of the deuterium decoration of both kinds of radiation-induced defects with low and high de-trapping energies for deuterium. We introduced the theoretical estimation for coefficient of similarity between neutron- and self-ion-irradiations, which is a fraction of common area under the curves of two overlapping damage energy spectra of primary knock-on atom (PKA) produced in tungsten by these two types of irradiation. In other words, Ksim is a part of displaced atoms produced in the similar conditions under two different types of irradiation. The theoretical values of Ksim = 0.34 and Ksim = 0.29 were obtained for tungsten target irradiated with 20 MeV self-ions in comparison to irradiation with neutrons in HFIR reactor (>0.1 MeV) and 14 MeV neutrons, respectively. The theoretical value of Ksim = 0.34 is about two times less than the experimental value of Kexp = 0.65. It means that high energy PKAs can play more important role in the production of similar damage structure by irradiation with self-ions and neutrons which is responsible for deuterium retention. The model assuming that all cascades with an energy higher than Tc = 150 keV split into identical sub-cascades gives the value of Ksim = 0.64 ± 0.01 for the coefficient of similarity between HFIR-neutron and 20 MeV self-ion irradiations that is in an agreement with experimental value of Kexp = 0.65 ± 0.1. Consequently, splitting of high-energy part of cascades might take

  3. Neutron irradiation experiments for fusion reactor materials through JUPITER program

    NASA Astrophysics Data System (ADS)

    Abe, K.; Kohyama, A.; Namba, C.; Wiffen, F. W.; Jones, R. H.

    1998-10-01

    A Japan-USA Program of irradiation experiments for fusion research, "JUPITER", has been established as a 6 year program from 1995 to 2000. The goal is to study "the dynamic behavior of fusion reactor materials and their response to variable and complex irradiation environment". This is phase-three of the collaborative program, which follows RTNS-II Program (Phase-1: 1982-1986) and FFTF/MOTA Program (Phase-2: 1987-1994). This program is to provide a scientific basis for application of materials performance data, generated by fission reactor experiments, to anticipated fusion environments. Following the systematic study on cumulative irradiation effects, done through FFTF/MOTA Program, JUPITER is emphasizing the importance of dynamic irradiation effects on materials performance in fusion systems. The irradiation experiments in this program include low activation structural materials, functional ceramics and other innovative materials. The experimental data are analyzed by theoretical modeling and computer simulation to integrate the above effects.

  4. Correlation between shear punch and tensile data for neutron-irradiated aluminum alloys

    SciTech Connect

    Hamilton, M.L.; Edwards, D.J.; Toloczko, M.B.

    1995-04-01

    This work was performed to determine whether shear punch and tensile data obtained on neutron irradiated aluminum alloys exhibited the same type of relationship as had been seen in other work and to assess the validity of extrapolating the results to proton-irradiated alloys. This work was also meant to be the first of a series of similar test matrices designed to determine whether the shear punch/tensile relationship varied or was the same for different alloy classes.

  5. Annealing studies of silicon microstrip detectors irradiated at high neutron fluences

    NASA Astrophysics Data System (ADS)

    Miñano, M.; Balbuena, J. P.; García, C.; González, S.; Lacasta, C.; Lacuesta, V.; Lozano, M.; Martí i Garcia, S.; Pellegrini, G.; Ullán, M.

    2008-06-01

    Silicon p-type detectors are being investigated for the development of radiation-tolerant detectors for the luminosity upgrade of the CERN large hadron collider (Super-LHC (sLHC)). Microstrip detectors have been fabricated by CNM-IMB with an n-side read-out on p-type high-resistivity float zone substrates. They have been irradiated with neutrons at the TRIGA Mark II nuclear reactor in Ljubljana. The irradiation fluxes match with the expected doses for the inner tracker at the sLHC (up to 10 16 equivalent 1 MeV neutrons cm -2). The macroscopic properties of the irradiated prototypes after irradiation were characterized at the IFIC-Valencia laboratory. The charge collection studies were carried out by means of a radioactive source setup as well as by an infrared laser illumination. The annealing behavior was studied in detail on a microstrip detector irradiated with a flux of 10 15 equivalent 1 MeV neutrons cm -2. Collected charge measurements were made after accelerated annealing times at 80 °C up to an equivalent annealing time of several years at room temperature. This note reports on the recorded results from the annealing of the irradiated p-type microstrip sensor.

  6. Long counter and its application for the calibration of the neutron irradiators.

    PubMed

    Park, Hyeonseo; Kim, Jungho; Choi, Kil-Oung

    2014-10-01

    The Korea Research Institute of Standards and Science (KRISS) has constructed a new long counter that can be disassembled in parts and reassembled. This counter can be easily transported and used as a transfer standard instrument for neutron fluence measurements. The response function and the effective centre of the counter are investigated by calculating neutron energies from thermal to 30 MeV using MCNPX. By carrying out measurements using a (252)Cf source in the KRISS irradiation room, the accuracy of the evaluated effective centre position is confirmed. The 'distance variation method' is adopted to eliminate the effect of inscatter neutrons. This method is effective and used for the experimental determination of the effective centre. The neutron emission rates determined by the neutron fluence measurements using the long counter developed are compared with those measured by a manganese sulphate bath, and show good agreement within 3 %. PMID:24381205

  7. Perspectives for online analysis of raw material by pulsed neutron irradiation

    NASA Astrophysics Data System (ADS)

    Bach, Pierre; Le Tourneur, P.; Poumarede, B.

    1997-02-01

    On-line analysis by pulsed neutron irradiation is an example of an advanced technology application of nuclear techniques, concerning real problems in the cement, mineral and coal industries. The most significant of these nuclear techniques is their capability of continuous measurement without contact and without sampling, which can lead to improved control of processes and resultant large financial savings. Compared to Californium neutron sources, the use of electrical pulsed neutron generators allows to obtain a higher signal/noise ratio for a more sensitive measurement, and allows to overcome a number of safety problems concerning transportation, installation and maintenance. An experiment related to a possible new on-line raw material analyzer is described, using a pulsed neutron generator. The key factors contributing to an accurate measurement are related to a suitable generator, to a high count rate gamma ray spectroscopy electronics, and to computational tools. Calculation and results for the optimization of the neutron irradiation time diagram are reported. One of the operational characteristics of such an equipment is related to neutron flux available: it is possible to adjust it to the requested accuracy, i.e. for a high accuracy during a few hours/day and for a lower accuracy the rest of the time. This feature allows to operate the neutron tube during a longer time, and then to reduce the cost of analysis.

  8. Technical Specifications for the Neutron Radiography Facility (TRIGA Mark 1 Reactor). Revision 6

    SciTech Connect

    Tomlinson, R.L.; Perfect, J.F.

    1988-04-01

    These Technical Specifications state the limits under which the Neutron Radiography Facility, with its associated TRIGA Mark I Reactor, is operated by the Westinghouse Hanford Company for the US Department of Energy. These specifications cover operation of the Facility for the purpose of examination of specimens (including contained fissile material) by neutron radiography, for the irradiation of specimens in the pneumatic transfer system and approved in-core or in-pool irradiation facilities and operator training. The Final Safety Analysis Report (TC-344) and its supplements, and these Technical Specifications are the basic safety documents of the Neutron Radiography Facility.

  9. 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

  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 irradiation embrittlement of molybdenum rhenium alloys and their improvement by heat treatment

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira; Ueda, Kazukiyo; Satou, Manabu; Abe, Katsunori

    1998-10-01

    Irradiation-induced embrittlement is one of the major problems with molybdenum alloys, which have been considered as one of the candidates for divertor structural materials. The effects of rhenium content, heat-treatment and irradiation condition on mechanical properties and microstructural development of molybdenum rhenium alloys were studied after neutron exposure by FFTF/MOTA up to high fluence (˜1 × 10 27 n/m 2, En>0.1 MeV). Appreciable plastic deformation was observed in a bending test on stress-relieved Mo-5 wt% Re irradiated at high temperatures. Fine, dense precipitates were observed in Mo-41 wt% Re, resulting in large hardening and embrittlement.

  12. Cation disorder determined by MAS {sup 27}Al NMR in high dose neutron irradiated spinel

    SciTech Connect

    Cooper, E.A.; Sickafus, K.E.; Hughes, C.D.; Earl, W.L.; Hollenberg, G.W.; Garner, F.A.; Bradt, R.C.

    1995-12-31

    Spinel (MgAl{sub 2}O{sub 4}) single crystals which had been neutron irradiated to high doses (53-250 dpa) were examined using {sup 27}Al magic angle spinning (MAS) nuclear magnetic resonance (NMR). The sensitivity of this procedure to a specific cation (Al) residing in different crystallographic environments allowed one to determine the distribution of the Al between the two cation sites in the spinel structure. The samples were irradiated at two different temperatures (400 and 750{degrees}C) and various doses. These results indicate that the Al was nearly fully disordered over the two lattice sites after irradiation.

  13. The observation of structural defects in neutron-irradiated lithium-doped silicon solar cells

    NASA Technical Reports Server (NTRS)

    Sargent, G. A.

    1971-01-01

    Electron microscopy has been used to observe the distribution and morphology of lattice defects introduced into lithium-doped silicon solar cells by neutron irradiation. Upon etching the surface of the solar cells after irradiation, crater-like defects are observed that are thought to be associated with the space charge region around vacancy clusters. Thermal annealing experiments showed that the crater defects were stable in the temperature range 300 to 1200 K in all of the lithium-doped samples. Some annealing of the crater defects was observed to occur in the undoped cells which were irradiated at the lowest doses.

  14. Parotid gland pathophysiology after mixed gamma and neutron irradiation of cancer patients

    SciTech Connect

    Anderson, M.W.; Izutsu, K.T.; Rice, J.C.

    1981-11-01

    Electrolyte and protein concentrations were measured in parotid saliva samples obtained from patients receiving localized, fractionated, neutron and gamma irradiation for the treatment of cancer. Salivary sodium chloride concentration increased transiently but then usually decreased to preirradiation values after 2 weeks of therapy. There were concurrent decreases in salivary flow rate, pH, and bicarbonate concentration. The decreases in sodium chloride concentration and flow rate are inconsistent with a previously suggested, irradiation-induced ductal sodium resorption defect. The findings contribute toward understanding how salivary gland physiology is altered in irradiation injury.

  15. Small punch test evaluation of neutron-irradiation-induced embrittlement of a Cr-Mo low-alloy steel

    SciTech Connect

    Song, S.-H. . E-mail: shsonguk@yahoo.co.uk; Faulkner, R.G.; Flewitt, P.E.J.; Marmy, P.; Weng, L.-Q.

    2004-09-15

    Neutron-irradiation-induced embrittlement of a 2.25Cr1Mo steel is investigated by means of small punch testing along with scanning electron microscopy. There is an apparent irradiation-induced embrittlement effect after the steel is irradiated at about 400 deg. C for 86 days with a neutron dose rate of 1.75x10{sup -8} dpa/s. The embrittlement is mainly nonhardening embrittlement caused by impurity grain boundary segregation.

  16. RNA and DNA changes in the bone marrow and blood of rats after neutron and continuous gamma irradiation.

    PubMed

    Misúrová, E; Gábor, J; Kropácová, K; Pado, D

    1989-01-01

    Quantitative changes in nucleic acids and DNA synthesis in the bone marrow and blood were followed after a single neutron irradiation with the dose of 2 Gy alone and combined with subsequent continuous gamma irradiation up to accumulated dose of 6 Gy. The pattern of changes after neutron exposure was similar as after other kinds of ionizing radiation. Additional continuous gamma irradiation affected mainly the rate of regenerative processes. PMID:2479958

  17. Irradiation creep in austenitic and ferritic steels irradiated in a tailored neutron spectrum to induce fusion reactor levels of helium

    SciTech Connect

    Grossbeck, M.L.; Gibson, L.T.; Jitsukawa, S.

    1996-04-01

    Six austenitic stainless steels and two ferritic alloys were irradiated sequentially in two research reactors where the neutron spectrum was tailored to produce a He production rate typical of a fusion device. Irradiation began in the Oak Ridge Research Reactor where an atomic displacement level of 7.4 dpa was achieved and was then transferred to the High Flux Isotope Reactor for the remainder of the irradiation to a total displacement level of 19 dpa. Temperatures of 60 and 330{degree}C are reported on. At 330{degree}C irradiation creep was found to be linear in stress and fluence with rates in the range of 1.7 - 5.5 x 10{sup -4}% MPa{sup -1} dpa{sup -1}. Annealed and cold-worked materials exhibited similar creep rates. There is some indication that austenitic alloys with TiC or TiO precipitates had a slightly higher irradiation creep rate than those without. The ferritic alloys HT-9 and Fe-16Cr had irradiatoin creep rates about 0.5 x 10{sup -4}% MPa{sup -1} dpa{sup -1}. No meaningful data could be obtained from the tubes irradiated at 60{degree}C because of damage to the tubes.

  18. 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.

  19. Neutron irradiation of polycrystalline yttrium aluminate garnet, magnesium aluminate spinel and α-alumina.

    NASA Astrophysics Data System (ADS)

    Neeft, E. A. C.; Konings, R. J. M.; Bakker, K.; Boshoven, J. G.; Hein, H.; Schram, R. P. C.; van Veen, A.; Conrad, R.

    1999-08-01

    Polycrystalline pellets of yttrium aluminate garnet (Y 3Al 5O 12), magnesium aluminate spinel (MgAl 2O 4) and α-alumina (α-Al 2O 3) have been irradiated in the high flux reactor (HFR) at Petten to a neutron fluence of 1.7 × 10 26 m -2 ( E>0.1 MeV) at a temperature of about 815 K. Volume changes smaller than 1% have been measured for Y 3Al 5O 12 and MgAl 2O 4. Transmission electron microscopy (TEM) results of Y 3Al 5O 12 show no difference between the unirradiated TEM samples and neutron-irradiated samples. For MgAl 2O 4, dislocation loops in some grains are found in the irradiated samples. TEM results of Al 2O 3 show a dense network of dislocation loops after neutron irradiation. The increase in volume is 4.2% for a neutron fluence of 1.7 × 10 26 m -2.

  20. [CYTOGENETIC EFFECTS IN MICE BONE MARROW AFTER IRRADIATION BY FAST NEUTRONS].

    PubMed

    Vorozhtsova, S V; Bulynina, T M; Ivanov, A A

    2016-01-01

    Mechanisms of damaging mice bone marrow cells by 1.5 MeV neutrons at the dose of 25-250 cGy, dose rate of 23.9 cGy/s and γ-quants ⁶⁰Co as a standard radiation were studied. The mitotic index and aberrant mitoses in marrow preparations were counted in 24 and 72 hours after irradiation. Coefficients of relative biological effectiveness (RBE) of fast neutrons 24 and 72 hours post irradiation calculated from mitotic index reduction and aberrant mitoses formation were within the range from 4.1 ± 0.1 to 7.3 ± 0.1. Mean time of the existence of chromosomal aberrations in marrow cells was determined. For the specified doses from γ-rays, the period of aberrations existence was 1.4-1.1 cycles and for neutrons, 1.0-0.6 cycles. Morphologic analysis of neutron-induced damages and ratio of the most common breaks demonstrated a high production of bridges, which outnumbered cells with fragments in 3 to 4 times suggesting a more destructive effect on the genetic structures of cells. RBE of fast neutrons is a variable that grows with a radiation dose. Moreover, RBE estimated after 72 hours exceeded values it had 24 hours after irradiation. PMID:27347593

  1. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reactions by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  2. Results of d+T fast neutron irradiation on advanced tumors of bladder and rectum

    SciTech Connect

    Battermann, J.J.

    1982-12-01

    From November, 1975 to November, 1981, around 400 patients were irradiated with 14 MeV d+T fast neutrons at the Antoni van Leeuwenhoek Hospital in Amsterdam. Special interest was focused on inoperable tumors of bladder and rectum. During the pilot phase of the study 47 patients were treated, mostly via two parallel opposed ports with dosages that ranged from 18 to more than 22 Gy. Although persistent local control was achieved in 23 patients (48%), 14 patients (29%) died of severe complications. By the introduction of a six field technique, the fatal complication rate could be reduced significantly. Since May 1978 patients were randomized in a three arm trial, using two dose levels on the neutron site. The preliminary results of a group of 91 patients show a similar survival in the three treatment arms with a somewhat better local control rate for high dose neutrons. An attempt was made to estimate RBE values for tumor control and normal tissue reaction by comparing the data for neutron irradiation with the data obtained with photons on a similar group of patients. From the values derived it must be concluded that the gain for neutron irradiation on these tumors in the pelvis will be negligible.

  3. Accumulation of /sup 254g/Es in the neutron irradiation of californium

    SciTech Connect

    Adaev, V.A.; Klinov, A.V.; Mamelin, A.V.; Toporov, Yu.G.

    1987-06-01

    Preliminary calculations have shown that the ratio of the rates of formation and burnup of /sup 254g/Es can be shifted toward the rate of formation, provided that the californium-containing targets are irradiated with neutrons having a very hard spectrum, (the hardness of the neutron spectrum is defined as the ratio of the flux density of ipithermal neutrons per unit mean logarithmic energy decrement to the flux density of the thermal neutrons). For the purpose of experimentally verifying this conclusion, we irradiated two test samples provided with metal cadmium shields and containing a mixture of californium isotopes as the initial material (approx. 70% of the total was /sup 252/Cf nuclei). After target irradiation, the targets were subjected to a radiochemical treatment and the concentration of the products accumulated was analyzed. It follows from a comparison of experimental and calculated data that the published data on the neutron cross section of the einsteinium isotopes render excessive /sup 254g/Es yields and too small /sup 253/Es yields. Therefore a series of calculations was made for the various values of the resonance integral of the /sup 253/Es absorption and of the partial resonances of the radiative capture integrals of /sup 253/Es in the reaction leading to the formation of /sup 254g/Es and /sup 254m/Es. The calculations have shown that the /sup 253/Es yield in the targets can be satisfactorily predicted with a resonance integral I/sub a/ = 3500 b of absorption

  4. Prenatal exposure to gamma/neutron irradiation: Sensorimotor alterations and paradoxical effects on learning

    SciTech Connect

    Di Cicco, D.; Antal, S.; Ammassari-Teule, M. )

    1991-01-01

    The effects of prenatal exposure on gamma/neutron radiations (0.5 Gy at about the 18th day of fetal life) were studied in a hybrid strain of mice (DBA/Cne males x C57BL/Cne females). During ontogeny, measurements of sensorimotor reflexes revealed in prenatally irradiated mice (1) a delay in sensorial development, (2) deficits in tests involving body motor control, and (3) a reduction of both motility and locomotor activity scores. In adulthood, the behaviour of prenatally irradiated and control mice was examined in the open field test and in reactivity to novelty. Moreover, their learning performance was compared in several situations. The results show that, in the open field test, only rearings were more frequent in irradiated mice. In the presence of a novel object, significant sex x treatment interactions were observed since ambulation and leaning against the novel object increased in irradiated females but decreased in irradiated males. Finally, when submitted to different learning tasks, irradiated mice were impaired in the radial maze, but paradoxically exhibited higher avoidance scores than control mice, possibly because of their low pain thresholds. Taken together, these observations indicate that late prenatal gamma/neutron irradiation induces long lasting alterations at the sensorimotor level which, in turn, can influence learning abilities of adult mice.

  5. 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.

  6. Numerical and experimental determination of neutron characteristics in irradiation rigs operated in LVR-15 research reactor.

    PubMed

    Koleska, Michal; Viererbl, Ladislav; Lahodova, Zdena; Ernest, Jaroslav; Zmitkova, Jelena; Marek, Milan

    2014-10-01

    The LVR-15 reactor is a 10-MW research reactor mostly dedicated to material research and isotope production. Material testing can be performed in various irradiation loops and rigs. For specimen irradiation, several rig constructions can be used, including standard single-cell CHOUCA rigs or special dedicated multi-cell rigs. The temperature in the rigs is controlled by a temperature control system, which can be operated in a stable or pulsed mode, with regard to the rig design. Irradiation conditions in the rig are monitored by a set of various fluence detectors. From these detectors, neutron fluence and its energy distribution can be determined for the whole volume of irradiation samples. Besides measurement, irradiation conditions are calculated by the Monte Carlo code MCNPX, which provides a complete review of irradiation conditions including neutron fluence and its energy distribution in samples and detectors, radiation damage and radiation heating conditions for the rig. A set of experimental and theoretical characteristics for dedicated irradiation positions in the core reflector and in fuel will be provided. PMID:24972899

  7. Effect of core structure irradiation on the RBMK neutron characteristics

    SciTech Connect

    Balygin, A. A. Krayushkin, A. V.

    2014-12-15

    The effect of changes in the graphite density and fuel channel diameters on the RBMK neutron characteristics is estimated. It is shown that uncertainty of those quantities can lead to a noticeable difference between the calculated and experimental values of the steam coefficient of reactivity and the subcriticality of the reactor.

  8. Microstructural analysis of neutron-irradiated martensitic steels

    NASA Astrophysics Data System (ADS)

    Kai, J. J.; Klueh, R. L.

    1996-06-01

    Four martensitic steels for fusion applications were examined by transmission electron microscopy after irradiation in the Fast Flux Test Facility (FFTF) at 420°C to 7.8 X 10 26 n/m 2 ( E > 0.1 MeV), about 35 dpa. There were two commercial steels, 9Cr-IMoVNb and 12Cr-1MoVW, and two experimental reduced-activation steels, 9Cr-2WV and 9Cr-2WVTa. Before irradiation, the tempered martensite microstructures of the four steels contained a high dislocation density, and the major precipitate was M 23C 6 carbide, with few MC carbides. Irradiation caused minor changes in these precipitates. Voids were found in all irradiated specimens, but swelling remained below 1%, with the 9Cr-1MoVNb having the highest void density. Although the 12Cr-IMoVW steel showed the best swelling resistance, it also contained the highest density of radiation-induced new phases, which were identified as chi-phase and possibly α'. Radiation-induced chi-phase was also observed in the 9Cr-1MoVNb steel. The two reduced-activation steels showed very stable behavior under irradiation: a high density of dislocation loops replaced the original high dislocation density; moderate void swelling occurred, and no new phase formed. The differences in microstructural evolution of the steels can explain some of the mechanical properties observations made in these steels.

  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. Defects in SiO 2 crystals after neutron irradiations at 20 K and 360 K

    NASA Astrophysics Data System (ADS)

    Nakagawa, M.; Okada, M.; Kawabata, Y.; Atobe, K.; Itoh, H.; Nakanishi, S.

    1994-06-01

    The synthetic silicon dioxide (SiO2), cut parallel (x-plate) or perpendicular (z-plate) to c-axis, are irradiated by reactor neutrons at 360 K (2.8 × 1018 n/cm2) or at 20 K (8.0 × 1016 n/cm2). After neutron irradiation at 360 K, the main absorption peak can be observed at 212 nm (5.84 eV) for z-plate and 217 nm (5.71 eV) for x-plate. After irradiation at 20 K a new band at 250 nm (4.96 eV) can be observed in addition to the band at about 220 nm. The 250 nm band having FWHM ∼ 0.44 eV disappears at 300-340 K. Thermoluminescences are also observed between 80 to 400 K; which show some difference between x-plate and z-plate.

  11. First result of deuterium retention in neutron-irradiated tungsten exposed to high flux plasma in TPE

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Hatano, Y.; Calderoni, P.; Oda, T.; Oya, Y.; Sokolov, M.; Zhang, K.; Cao, G.; Kolasinski, R.; Sharpe, J. P.

    2011-08-01

    With the Japan-US joint research project Tritium, Irradiations, and Thermofluids for America and Nippon (TITAN), an initial set of tungsten samples (99.99% purity, A.L.M.T. Co.) were irradiated by high flux neutrons at 323 K to 0.025 dpa in High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Subsequently, one of the neutron-irradiated tungsten samples was exposed to a high-flux deuterium plasma (ion flux: 5 × 1021 m-2 s-1, ion fluence: 4 × 1025 m-2) in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory (INL). The deuterium retention in the neutron-irradiated tungsten was 40% higher in comparison to the unirradiated tungsten. The observed broad desorption spectrum from neutron-irradiated tungsten and associated TMAP modeling of the deuterium release suggest that trapping occurs in the bulk material at more than three different energy sites.

  12. Voids in neutron-irradiated metals and alloys

    SciTech Connect

    Hendricks, R.W.

    1980-01-01

    Small-angle x-ray and neutron scattering are powerful analytical tools for investigating long-range fluctuations in electron (x-rays) or magnetic moment (neutrons) densities in materials. In recent years they have yielded valuable information about voids, void size distributions, and swelling in aluminum, aluminum alloys, copper, molybdenum, nickel, nickel-aluminum, niobium and niobium alloys, stainless steels, graphite and silicon carbide. In the case of aluminum, information concerning the shape of the voids and the ratio of specific surface energies was obtained. The technique of small-angle scattering and its application to the study of voids is reviewed in the paper. Emphasis is placed on the conditions which limit the applicability of the technique, on the interpretation of the data, and on a comparison of the results obtained with companion techniques such as transmission electron microscopy and bulk density. 8 figures, 41 references.

  13. Neutron capture effects in lunar gadolinium and the irradiation histories of some lunar rocks.

    NASA Technical Reports Server (NTRS)

    Lugmair, G. W.; Marti, K.

    1971-01-01

    The Gd isotopic composition in 19 lunar rock and soil samples from three Apollo sites is reported. The analytical techniques and the high precision mass spectrometric measurements are discussed. Enrichments in the Gd-158 oxide to G-157 oxide ratio due to neutron capture range up to 0.75%. Integrated 'thermal' neutron fluxes derived from the isotopic anomalies of Gd are compared with spallation Kr data from aliquot samples to construct a model which gives both average cosmic-ray irradiation depths and effective neutron exposure ages for some rocks. Rock 14310 is the first lunar sample where Kr anomalies due to resonance neutron capture in Br are observed. A Kr-81/Kr exposure age of 262 (plus or minus 7)m.y. is calculated for this rock.

  14. Fissile Material Detection by Differential Die Away Analysis

    NASA Astrophysics Data System (ADS)

    Shaw, Timothy J.; Strellis, Dan A.; Stevenson, John; Keeley, Doug; Gozani, Tsahi

    2009-03-01

    Detection and interdiction of Special Nuclear Material (SNM) in transportation is one of the most critical security issues facing the United States. Active inspection by inducing fission in fissile nuclear materials, such as 235U and 239Pu, provides several strong and unique signatures that make the detection of concealed nuclear materials technically very feasible. Differential Die-Away Analysis (DDAA) is a very efficient, active neutron-based technique that uses the abundant prompt fission neutrons signature. It benefits from high penetrability of the probing and signature neutrons, high fission cross section, high detection sensitivity, ease of deployment and relatively low cost. DDAA can use any neutron source or energy as long as it can be suitably pulsed. The neutron generator produces pulses of neutrons that are directed into a cargo. As each pulse passes through the cargo, the neutrons are thermalized and absorbed. If SNM is present, the thermalized neutrons create a new source of (fission) neutrons with a distinctive time profile. An efficient laboratory system was designed, fabricated and tested under a US Government DHS DNDO contract. It was shown that a small uranium sample can be detected in a large variety of cargo types and configurations within practical measurement times using commercial compact (d,T) sources. Using stronger sources and wider detector distribution will further cut inspection time. The system can validate or clear alarms from a primary inspection system such as an automated x-ray system.

  15. Intergranular stress corrosion cracking susceptibility of neutron-irradiated, thermally sensitized type 304 stainless steel

    SciTech Connect

    Onchi, T.; Hide, K.; Mayuzumi, M.; Hoshiya, T.

    2000-05-01

    Austenitic stainless steels (SS) have been used as core component materials for light water reactors. As reactors age, however, the material tends to suffer from degradation primarily resulting from irradiation-assisted stress corrosion cracking (IASCC) as well as intergranular stress corrosion cracking (IGSCC). Neutron-irradiated, thermally sensitized Type 304 (UNS S30400) stainless steels (SS) were examined by slow strain rate (SSR) stress corrosion cracking (SCC) tests in 290 C water of 0.2 ppm dissolved oxygen concentration (DO) and by SSR tensile tests in 290 C inert gas environment. Neutron fluences ranged from 4 x 10{sup 22} n/m{sup 2} to 3 x 10{sup 25} n/m{sup 2} (energy [E] > 1 MeV). percent intergranular (%IG) cracking, which has been used as an intergranular (IG) cracking susceptibility indicator in the SSR SCC tests, changes anomalously with neutron fluence in spite of the strain-to-failure rate decreasing with an increase of neutron fluence. Apparently, %IG is a misleading indicator for the irradiated, thermally sensitized Type 304 SS and for the irradiated, nonsensitized SS when IG cracking susceptibility is compared at different neutron fluences, test temperatures, DO, and strain rates. These test parameters may affect deformation and fracture behaviors of the irradiated SS during the SSR SCC tests, resulting in changing %IG, which is given by the ratio of the total IG cracking area to the entire fracture surface area. It is suggested that strain-to-IG crack initiation for the irradiated, thermally sensitized SS and for the irradiated, nonsensitized SS is the alternative indicator in the SSR SCC tests. An engineering expedient to determine the IG crack initiation strain is given by a deviating point on superposed stress-strain curves in inert gas and in oxygenated water. The strain-to-IG crack initiation becomes smaller with an increase of neutron fluence and DO. The SSR tensile tests in inert gas are needed to obtain strain-to-IG crack initiation in

  16. Significant disparity in base and sugar damage in DNA resulting from neutron and electron irradiation

    PubMed Central

    Pang, Dalong; Nico, Jeffrey S.; Karam, Lisa; Timofeeva, Olga; Blakely, William F.; Dritschilo, Anatoly; Dizdaroglu, Miral; Jaruga, Pawel

    2014-01-01

    In this study, a comparison of the effects of neutron and electron irradiation of aqueous DNA solutions was investigated to characterize potential neutron signatures in DNA damage induction. Ionizing radiation generates numerous lesions in DNA, including base and sugar lesions, lesions involving base–sugar combinations (e.g. 8,5′-cyclopurine-2′-deoxynucleosides) and DNA–protein cross-links, as well as single- and double-strand breaks and clustered damage. The characteristics of damage depend on the linear energy transfer (LET) of the incident radiation. Here we investigated DNA damage using aqueous DNA solutions in 10 mmol/l phosphate buffer from 0–80 Gy by low-LET electrons (10 Gy/min) and the specific high-LET (∼0.16 Gy/h) neutrons formed by spontaneous 252Cf decay fissions. 8-hydroxy-2′-deoxyguanosine (8-OH-dG), (5′R)-8,5′-cyclo-2′-deoxyadenosine (R-cdA) and (5′S)-8,5′-cyclo-2′-deoxyadenosine (S-cdA) were quantified using liquid chromatography–isotope-dilution tandem mass spectrometry to demonstrate a linear dose dependence for induction of 8-OH-dG by both types of radiation, although neutron irradiation was ∼50% less effective at a given dose compared with electron irradiation. Electron irradiation resulted in an exponential increase in S-cdA and R-cdA with dose, whereas neutron irradiation induced substantially less damage and the amount of damage increased only gradually with dose. Addition of 30 mmol/l 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), a free radical scavenger, to the DNA solution before irradiation reduced lesion induction to background levels for both types of radiation. These results provide insight into the mechanisms of DNA damage by high-LET 252Cf decay neutrons and low-LET electrons, leading to enhanced understanding of the potential biological effects of these types of irradiation. PMID:25034731

  17. Optical absorption of neutron-irradiated silica fibers

    SciTech Connect

    Cooke, D.W.; Farnum, E.H.; Bennett, B.L.

    1996-10-01

    Induced-loss spectra of silica-based optical fibers exposed to high (10{sup 23} n-m{sup {minus}2}) and low (10{sup 21} n-m{sup {minus}2}) fluences of neutrons at the Los Alamos Spallation Radiation Effects Facility (LASREF) have been measured. Two types of fibers consisting of a pure fused silica core with fluorine-doped ({approximately}4 mole %) cladding were obtained from Fiberguide Industries and used in the as-received condition. Anhydroguide{trademark} and superguide{trademark} fibers contained less than 1 ppm, and 600 to 800 ppm of OH, respectively. The data suggest that presently available silica fibers can be used in plasma diagnostics, but the choice and suitability depends upon the spectral region of interest. Low-OH content fibers can be used for diagnostic purposes in the interval {approximately}800 to 1400 mn if the exposure is to high-fluence neutrons. For low-fluence neutron exposures, the low-OH content fibers are best suited for use in the interval {approximately}800 to 2000 nm, and the high-OH content fibers are the choice for the interval {approximately}400 to 800 nm.

  18. Neutron irradiation effect on site distribution of cations in non-stoichiometric magnesium aluminate spinel

    NASA Astrophysics Data System (ADS)

    Sawabe, Takashi; Yano, Toyohiko

    2008-02-01

    Neutron irradiation effects on cation distribution in non-stoichiometric Mg-Al spinel were examined by ALCHEMI (Atom Location by Channeling Enhanced Microanalysis) method. Parameter n, or non-stoichiometry of MgO · nAl 2O 3 of the specimens, were n = 1.00, 1.01, 1.10, 1.48. These specimens were neutron-irradiated up to a fluence of 2.3 × 10 24 n/m 2 ( E > 0.1 MeV) at 500-530 °C in JMTR. Some specimens contracted by the irradiation and the arrangement of cations became more disorder. The other specimens showed very small swelling by the irradiation and the cation distribution became slightly ordered. The cation distribution of the contracted specimen returned stepwise to the pre-irradiated condition after the annealing at 700 °C. The cation distribution of the slightly swollen specimens did not change after the annealing up to 700 °C. Cation distribution in the T-site was more sensitively influenced by the irradiation.

  19. Significant role of fissility in evaporation residue cross sections as a probe of presaddle nuclear dissipation

    SciTech Connect

    Ye, W.

    2010-01-15

    Using a Langevin model, we explore the role of fissility in probing presaddle nuclear dissipation by calculating the excess of the evaporation residue cross section over its standard statistical-model value as a function of nuclear dissipation strength for nuclei {sup 190}Os and {sup 210}Po, which are taken as two representatives that have the same neutron-to-proton ratio (N/Z) but have a difference in fissility. We find that a large fissility not only amplifies the dissipation effects on the excess of evaporation residues, but also significantly increases the sensitivity of this excess to nuclear dissipation. The results suggest that in experiments, to obtain a more accurate information of nuclear dissipation inside the saddle point by measuring evaporation residue cross sections, it is best to populate among the various compound systems with equal N/Z those with high fissility.

  20. Neutron-transmuted carbon-14 in neutron-irradiated GaN: Compensation of DX-like center

    SciTech Connect

    Ida, T.; Oga, T.; Kuriyama, K.; Kushida, K.; Xu, Q.; Fukutani, S.

    2013-12-04

    The transmuted-C related luminescence and net carrier concentration are studied by combining photoluminescence, liquid scintillation, and Raman scattering. GaN single crystal films grown by metalorganic-vapor-phase epitaxy are irradiated with fast and thermal neutrons at fluxes of 3.9 × 10{sup 13} cm{sup −2}s{sup −1} and 8.15 × 10{sup 13} cm{sup −2}s{sup −1}, respectively. Irradiation time is 48 hours. The calculated {sup 72}Ge and {sup 14}C concentrations are 1.24 × 10{sup 18} cm{sup −3} and 1.13 × 10{sup 18} cm{sup −3}, respectively. The transmuted {sup 14}C is detected by the liquid scintillation method to survey β-rays emitted in the process of {sup 14}C decays from {sup 14}N. Tritium ({sup 3}H) is also emitted by a (n,t) reaction of {sup 14}N due to the neutron irradiation above 4.5 MeV. Photoluminescence relating to C, DX-like center of Ge and yellow luminescence band are observed in 1000 °C annealed NTD-GaN. The free electron concentration estimated from Raman scattering is 4.97 × 10{sup 17} cm{sup −3}. This value is lower than that from the transmuted Ge concentration, suggesting the compensation due to the transmuted {sup 14}C acceptors.

  1. Mechanical property changes of low activation ferritic/martensitic steels after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Kohno, Y.; Kohyama, A.; Hirose, T.; Hamilton, M. L.; Narui, M.

    Mechanical property changes of Fe- XCr-2W-0.2V,Ta ( X: 2.25-12) low activation ferritic/martensitic steels including Japanese Low Activation Ferritic/martensitic (JLF) steels and F82H after neutron irradiation were investigated with emphasis on Charpy impact property, tensile property and irradiation creep properties. Dose dependence of ductile-to-brittle transition temperature (DBTT) in JLF-1 (9Cr steel) irradiated at 646-700 K increased with irradiation up to 20 dpa and then decreased with further irradiation showing highest DBTT of 260 K at 20 dpa. F82H showed similar dose dependence in DBTT to JLF-1 with higher transition temperature than that of JLF-1 at the same displacement damage. Yield strength in JLF steels and F82H showed similar dose dependence to that of DBTT. Yield strength increased with irradiation up to 15-20 dpa and then decreased to saturate above about 40 dpa. Irradiation hardening in 7-9%Cr steels (JLF-1, JLF-3, F82H) were observed to be smaller than those in steels with 2.25%Cr (JLF-4) or 12%Cr (JLF-5). Dependences of creep strain on applied hoop stress and neutron fluence were measured to be 1.5 and 1, respectively. Temperature dependence of creep coefficient showed a maximum at about 700 K which was caused by irradiation induced void formation or irradiation enhanced creep deformation. Creep coefficient of F82H was larger than those of JLF steels above 750 K. This was considered to be caused by the differences in N and Ta concentration between F82H and JLF steels.

  2. Helium release from neutron-irradiated Li 2O single crystals

    NASA Astrophysics Data System (ADS)

    Yamaki, Daiju; Tanifuji, Takaaki; Noda, Kenji

    1998-10-01

    Lithium oxide (Li 2O) single crystals with various sizes (0.15-5 mm) were used as specimens. After the irradiation in JRR-4 and JRR-2 (thermal neutron fluence: 2 × 10 17-2 × 10 19 n/cm 2), and fast neutrons in FFTF (fast neutron fluence: 4 × 10 22 n/cm 2), helium release from the Li 2O specimens during the heating at a constant heating rate was continuously measured with a quadrupole mass spectrometer. The helium release curves from JRR-4 and JRR-2 specimens have only one broad peak each. From the dependence of the peak temperature on the neutron fluence and the crystal diameter, and the comparison with the results of sintered pellets, it is concluded that the helium generated in the crystal is released through the processes of bulk diffusion with trapping by irradiation defects such as some defect clusters. For the helium release from FFTF specimens, two broad peaks were observed in the release curves. It is considered that two different migration paths exist for helium migration in the specimen, that is, bulk diffusion and diffusion through the micro-cracks formed due to the heavy irradiation.

  3. Calculations of helium production in materials irradiated at spallation neutron sources

    SciTech Connect

    Corzine, R.K.; Dudziak, D.J.; Wechsler, M.S.; Barnett, M.H.; Mansur, L.K.

    1998-09-01

    Experience with materials irradiated in fission reactor neutron environments has shown that radiation-produced helium can exacerbate the degradation of properties caused by radiation-produced defects and defect clusters. Whereas fission-reactor neutron energies extend up to {approximately}10 MeV, the neutrons and protons at spallation neutron sources reach up to 1,000 to 2,000 MeV, and He production is much greater. For example, calculations have shown for the innermost shell of the containment vessel of the spallation neutron source, under collaborative design by several national laboratories led by the Oak Ridge National Laboratory, that full-power displacement and He production rates are {approximately}20 displacements per atom (dpa)/yr and 1,000 atomic parts per million (appm) He/yr, which corresponds to 50 appm He/dpa. By contrast, materials in fission reactor cores usually experience <1 appm He/dpa. In this paper, the authors summarize methods and results for the calculation of He production cross sections appropriate to the neutron and proton energies to which target and containment materials are exposed at spallation neutron sources. The principal calculational tool is LAHET or, more broadly, the LAHET code system (LCS).

  4. Effect of electron- and neutron-irradiation on Fe-Cu model alloys studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Nagai, Y.; Takadate, K.; Tang, Z.; Ohkubo, H.; Sunaga, H.; Takizawa, H.; Hasegawa, M.

    2011-01-01

    Electron- and neutron-irradiation effects on dilute Fe-Cu model alloys of nuclear reactor pressure vessel steels are studied by positron annihilation spectroscopy. We have found that, not only by high-dose neutron-irradiation but also by low-dose electron-irradiation, the aggregation of Cu atoms and vacancies takes place and the ultrafine Cu precipitates are formed after post-irradiation annealing at 400°C. In spite of large difference in the irradiation doses between the electron- and the neutron-irradiated samples, no significant difference is observed in the isochronal annealing behaviour above 400°C of positron annihilation and micro-hardness, indicating that small amount of extra vacancies enhance the aggregation of Cu atoms in Fe during the annealing-out process of the vacancies.

  5. Influence of heat-treatment on tensile behavior of neutron irradiated molybdenum

    NASA Astrophysics Data System (ADS)

    Hasegawa, A.; Abe, K.; Satou, M.; Ueda, K.; Namba, C.

    1996-10-01

    Tensile specimens of stress-relieved and recrystallized molybdenum were irradiated at five temperatures between 646 and 1073 K in FFTF/MOTA cycle 11. The exposure levels were in the range of 6.8 to 34 dpa depending on the irradiation temperatures. After irradiation tensile tests and hardness test were carried out at room temperature. The total elongation of stress-relived specimens irradiated at 792, 873 and 1073 K ranged from 9 to 13%, and those of recrystallized specimens irradiated at these temperatures were almost 0%. The fracture modes of the stress-relieved specimens irradiated at 646-873 K were transgranular type and those of recrystallized specimens irradiated at 646-1073 K were intergranular type. Grain growth and intergranular fracture surface were observed in the stress-relieved specimen irradiated at 1073 K but it still has 9% total elongation. It is important that the stress-relived molybdenum had enough ductility at room temperature after neutron exposures up to relatively high fluences.

  6. Mechanical properties of neutron-irradiated nickel-containing martensitic steels: I. Experimental study

    NASA Astrophysics Data System (ADS)

    Klueh, R. L.; Hashimoto, N.; Sokolov, M. A.; Shiba, K.; Jitsukawa, S.

    2006-10-01

    Tensile and Charpy specimens of 9Cr-1MoVNb (modified 9Cr-1Mo) and 12Cr-1MoVW (Sandvik HT9) steels and these steels doped with 2% Ni were irradiated at 300 and 400 °C in the High Flux Isotope Reactor (HFIR) up to ≈12 dpa and at 393 °C in the Fast Flux Test Facility (FFTF) to ≈15 dpa. In HFIR, a mixed-spectrum reactor, ( n, α) reactions of thermal neutrons with 58Ni produce helium in the steels. Little helium is produced during irradiation in FFTF. After HFIR irradiation, the yield stress of all steels increased, with the largest increases occurring for nickel-doped steels. The ductile-brittle transition temperature (DBTT) increased up to two times and 1.7 times more in steels with 2% Ni than in those without the nickel addition after HFIR irradiation at 300 and 400 °C, respectively. Much smaller differences occurred between these steels after irradiation in FFTF. The DBTT increases for steels with 2% Ni after HFIR irradiation were 2-4 times greater than after FFTF irradiation. Results indicated there was hardening due to helium in addition to hardening by displacement damage and irradiation-induced precipitation.

  7. Crack initiation behavior of neutron irradiated model and commercial stainless steels in high temperature water

    NASA Astrophysics Data System (ADS)

    Stephenson, Kale J.; Was, Gary S.

    2014-01-01

    The objective of this study was to isolate key factors affecting the irradiation-assisted stress corrosion cracking (IASCC) susceptibility of eleven neutron-irradiated austenitic stainless steel alloys. Four commercial purity and seven high purity stainless steels were fabricated with specific changes in composition and microstructure, and irradiated in a fast reactor spectrum at 320 °C to doses between 4.4 and 47.5 dpa. Constant extension rate tensile (CERT) tests were performed in normal water chemistry (NWC), hydrogen water chemistry (HWC), or primary water (PW) environments to isolate the effects of environment, elemental solute addition, alloy purity, alloy heat, alloy type, cold work, and irradiation dose. The irradiated alloys showed a wide variation in IASCC susceptibility, as measured by the relative changes in mechanical properties and crack morphology. Cracking susceptibility measured by %IG was enhanced in oxidizing environments, although testing in the lowest potential environment caused an increase in surface crack density. Alloys containing solute addition of Ni or Ni + Cr exhibited no IASCC. Susceptibility was reduced in materials cold worked prior to irradiation, and increased with increasing irradiation dose. Irradiation-induced hardening was accounted for by the dislocation loop microstructure, however no relation between crack initiation and radiation hardening was found.

  8. Deuterium trapping at defects created with neutron and ion irradiations in tungsten

    SciTech Connect

    Y. Hatano; M. Shimada; T. Otsuka; Y. Oya; V.Kh. Alimov; M. Hara; J. Shi; M. Kobayashi; T. Oda; G. Cao; K. Okuno; T. Tanaka; K. Sugiyama; J. Roth; B. Tyburska-Püschel; J. Dorner; N. Yoshida; N. Futagami; H. Watanabe; M. Hatakeyama; H. Kurishita; M. Sokolov; Y. Katoh

    2013-07-01

    The effects of neutron and ion irradiations on deuterium (D) retention in tungsten (W) were investigated. Specimens of pure W were irradiated with neutrons to 0.3 dpa at around 323 K and then exposed to high-flux D plasma at 473 and 773 K. The concentration of D significantly increased by neutron irradiation and reached 0.8 at% at 473 K and 0.4 at% at 773 K. Annealing tests for the specimens irradiated with 20 MeV W ions showed that the defects which play a dominant role in the trapping at high temperature were stable at least up to 973 K, while the density decreased at temperatures equal to or above 1123 K. These observations of the thermal stability of traps and the activation energy for D detrapping examined in a previous study (˜1.8 eV) indicated that the defects which contribute predominantly to trapping at 773 K were small voids. The higher concentration of trapped D at 473 K was explained by additional contributions of weaker traps. The release of trapped D was clearly enhanced by the exposure to atomic hydrogen at 473 K, though higher temperatures are more effective for using this effect for tritium removal in fusion reactors.

  9. Point defects in 4H-SiC epilayers introduced by neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hazdra, Pavel; Záhlava, Vít; Vobecký, Jan

    2014-05-01

    Electronic properties of radiation damage produced in 4H-SiC by neutron irradiation and its effect on electrical parameters of Junction Barrier Schottky (JBS) diodes were investigated. 4H-SiC N-epilayers, which formed the low-doped N-base of JBS power diodes, were irradiated with 1 MeV neutrons with fluences ranging from 1.3 × 1013 to 4.0 × 1014 cm-2. Radiation defects were then characterized by capacitance deep-level transient spectroscopy, I-V and C-V measurement. Results show that neutron irradiation introduces different point defects giving rise to acceptor levels lying 0.61/0.69, 0.88, 1.03, 1.08 and 1.55 eV below the SiC conduction band edge. Introduction rates of these centers are ranging from 0.64 to 4.0 cm-1. These defects have a negligible effect on blocking and dynamic characteristics of irradiated diodes. However, the acceptor character of introduced deep levels and their fast introduction deteriorate diode's ON-state resistance already at fluences exceeding 1 × 1014 cm-2.

  10. Degradation of mechanical properties of stainless steel cladding due to neutron irradiation and thermal aging

    SciTech Connect

    Haggag, F.M.

    1994-09-01

    Thermal aging of three-wire series-arc stainless steel weld overlay cladding at 288{degrees}C for 1605 h resulted in an appreciable decrease (16%) in the Charpy V-notch (CVN) upper-shelf energy (USE), but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect following neutron irradiation at 288{degrees}C to a fluence of 5 X 10{sup 19} neutrons/cm{sup 2} (>1 MeV) was a 22% reduction in the USE and a 29{degrees}C shift in the 41-J transition temperature. The effect of thermal aging on tensile properties was very small. However, the combined effect of irradiation and aging was an increase in the yield strength (6 to 34% at test temperatures from 288 to -125{degrees}C) and no apparent change in ultimate tensile strength or total elongation. Neutron irradiation reduced the initiation fracture toughness (J{sub {kappa}}) much more than did thermal aging alone. However, irradiation slightly decreased the tearing modulus but no reduction was caused by thermal aging alone. The effects of long-term thermal exposure times (20,000 and 50,000 h) will be investigated when the specimens become available. Also, long-term thermal exposure of the three-wire cladding as well as type 308 stainless steel weld materials at 343{degrees}C is in progress.

  11. gamma. -ray and neutron irradiation characteristics of pure silica core single mode fiber and its life time estimation

    SciTech Connect

    Chigusa, Y.; Watanabe, M.; Kyoto, M.; Ooe, M.; Matsubara, T.; Okamoto, S.; Yamamoto, T.; Iida, T.; Sumita, K.

    1988-02-01

    The investigation of the induced loss for a single mode (SM) optical fiber under ..gamma..-ray irradiation and neutron irradiation are described and the estimation method for induced loss with low dose rate and long-term ..gamma..-ray irradiation is proposed. The induced loss of pure silica core SM fiber was estimated to be 50 times lower than that of germanium containing silica core SM fiber after irradiation with 1 R/Hr for 25 years.

  12. Trehalose dimycolate enhances survival of fission neutron-irradiated mice and Klebsiella pneumoniae-challenged irradiated mice

    SciTech Connect

    McChesney, D.G.; Ledney, G.D.; Madonna, G.S. )

    1990-01-01

    The survival of B6D2F1 female mice exposed to lethal doses of fission neutron radiation is increased when trehalose dimycolate (TDM) preparations are given either 1 h after exposure or 1 day before exposure to radiation. TDM in an emulsion of squalene, Tween 80, and saline was the most effective formulation for increasing the 30-day survival of mice when given 1 day before (90%) or 1 h after (88%) exposure to radiation. An aqueous suspension of a synthetic analog of TDM was less effective at increasing 30-day survival (60%) when given 1 day prior to radiation exposure and not effective when given 1 h after radiation. Mice receiving a sublethal dose (3.5 Gy) of fission neutron radiation and either the TDM emulsion or synthetic TDM 1 h after irradiation were substantially more resistant to challenge with 10, 100, 1000, or 5000 times the LD50/30 dose of Klebsiella pneumoniae than untreated mice.

  13. Effect of initial oxygen content on the void swelling behavior of fast neutron irradiated copper

    NASA Astrophysics Data System (ADS)

    Zinkle, S. J.; Garner, F. A.

    2004-08-01

    Density measurements were performed on high purity copper specimens containing ⩽10 and ˜90 wt ppm oxygen following irradiation in FFTF MOTA 2B. Significant amounts of swelling were observed in both the low-oxygen and oxygen-doped specimens following irradiation to ˜17 dpa at 375 °C and ˜47 dpa at 430 °C. Oxygen doping up to 360 appm (˜90 wt ppm) did not significantly affect the void swelling of copper for these irradiation conditions. This implies that surface energy reduction associated with oxygen segregation and chemisorption on void surfaces is not a significant factor controlling the void swelling behavior in copper irradiated with neutrons to high doses at ˜400 °C.

  14. A polycrystalline modeling of the mechanical behavior of neutron irradiated zirconium alloys

    NASA Astrophysics Data System (ADS)

    Onimus, Fabien; Béchade, Jean-Luc

    2009-02-01

    Zirconium alloys used as fuel cladding tubes in the nuclear industry undergo important changes after neutron irradiation in the microstructure as well as in the mechanical properties. However, the effects of the specific post-irradiation deformation mechanisms on the mechanical behavior are not clearly understood and modeled. Based on experimental results it is discussed that the kinematic strain hardening is increased by the plastic strain localization inside the dislocation channels as well as the only basal slip activation observed for specific mechanical tests. From this analysis, the first polycrystalline model is developed for irradiated zirconium alloys, taking into account the irradiation induced hardening, the intra-granular softening as well as the intra-granular kinematic strain hardening due to the plastic strain localization inside the channels. This physically based model reproduces the mechanical behavior in agreement with the slip systems observed. In addition, this model reproduces the Bauschinger effect observed during low cycle fatigue as well as the cyclic strain softening.

  15. Fast neutron irradiation effects on magnetization relaxation in YBCO single crystals

    SciTech Connect

    Lensink, J.G.; Griessen, R. . Faculty of Physics and Astronomy); Wiesinger, H.P.; Sauerzopf, F.M.; Weber, H.W. ); Crabtree, G.W. )

    1991-07-01

    A high-quality YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} single crystal has been investigated by torque magnetometry prior to and following fast neutron irradiation to a fluence of 2{times}10{sup 21} m{sup {minus}2} (E > 0.1 MeV). In addition to large enhancements of the critical current densities, which have been observed in similar form previously by Sauerzopf et al, we find a dramatic change in the relaxation behavior following irradiation. At low temperatures ({le} 50 k) the relaxation rates are lowered by factors up to 4 in the irradiated state in a magnetic field of 1.5 T. At higher temperatures, on the other hand, they are enhanced compared to the unirradiated state. Both before and after irradiation, the magnetization relaxation follows a logarithmic time dependence, which we ascribe to thermally activated flux motion.

  16. Relationship of microstructure and tensile properties for neutron-irradiated vanadium alloys

    SciTech Connect

    Loomis, B.A.; Smith, D.L.

    1990-01-01

    The microstructures in V-15Cr-5Ti, V-10Cr-5RTi, V-3Ti-1Si, V-15Ti-7.5Cr, and V-20Ti alloys were examined by transmission electron microscopy after neutron irradiation at 600{degree}C to 21--84 atom displacements per atom in the Materials Open Test Assembly of the Fast Flux Test Facility. The microstructures in these irradiated alloys were analyzed to determine the radiation-produced dislocation density, precipitate number density and size, and void number density and size. The results of these analyses were used to compute increases in yield stress and swelling of the irradiated alloys. The computed increase in yield stress was compared with the increase in yield stress determined from tensile tests on these irradiated alloys. This comparison made it possible to evaluate the influence of alloy composition on the evolution of radiation-damaged microstructures and the resulting tensile properties. 11 refs.

  17. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    SciTech Connect

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Wirth, Brian D; Snead, Lance Lewis

    2016-01-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (~90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutron irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S–W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage. This provides insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.

  18. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    NASA Astrophysics Data System (ADS)

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Snead, Lance L.; Wirth, Brian D.

    2016-03-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (∼90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutron irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S-W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage, providing insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.

  19. The effect of neutron irradiation dose on vacancy defect accumulation and annealing in pure nickel

    NASA Astrophysics Data System (ADS)

    Druzhkov, A. P.; Arbuzov, V. L.; Perminov, D. A.

    2012-02-01

    In order to investigate the dose dependence of vacancy defect evolution in nickel, specimens of high-purity Ni were neutron-irradiated at ˜330 K in the IVV-2M reactor (Russia) to fluencies in the range of 1 × 10 21-1 × 10 23 n/m 2 ( E > 0.1 MeV) corresponding to displacement dose levels in the range of about 0.0001-0.01 dpa and subsequently stepwise annealed to about 900 K. Ni was characterized both in as-irradiated state as well as after post-irradiation annealing by positron annihilation spectroscopy. The formation of three-dimensional vacancy clusters (3D-VCs) in cascades was observed under neutron irradiation, the concentration of 3D-VCs increases with increasing dose level. 3D-VCs collapse into secondary-type clusters (stacking fault tetrahedra (SFTs), and vacancy loops) during stepwise annealing at 350-450 K. It is shown that the thermal stability of SFTs grow with increasing dose level, probably, it is due to growth of the average SFT size during annealing. The results of annealing experiments on electron-irradiated Ni at 300 K are indicated in the paper, for comparison. We also have briefly discussed the positron response to the SFT-like structures.

  20. Welding-induced mechanical properties in austenitic stainless steels before and after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Stoenescu, R.; Schäublin, R.; Gavillet, D.; Baluc, N.

    2007-03-01

    The effects of neutron irradiation on the mechanical properties of welded joints made of austenitic stainless steels have been investigated. The materials are welded AISI 304 and AISI 347, so-called test weld materials, irradiated with neutrons at 573 K to doses of 0.3 and 1.0 dpa. In addition, an AISI 304 from a decommissioned pressurised water reactor, so-called in-service material, which had accumulated a maximum dose of 0.35 dpa at about 573 K, was investigated. The mechanical properties of heat-affected zones and base materials were analysed before and after irradiation. Tensile parameters were determined at room temperature and at 573 K, for all materials and irradiation conditions. In the test weld materials it is found that radiation hardening is lower and loss of ductility is higher in the heat-affected zone than in the base material. In the in-service material radiation hardening is about the same in heat-affected zone and base material. After irradiation, deformation takes place by stacking faults and twins, at both room temperature and high temperature, contrary to unirradiated materials, where deformation takes place by twinning at room temperature and by dislocation cells at high temperature. No defect free channels are observed.

  1. Evaluation of Damage Tolerance of Advanced SiC/SiC Composites after Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Ozawa, Kazumi; Katoh, Yutai; Nozawa, Takashi; Hinoki, Tatsuya; Snead, Lance L.

    2011-10-01

    Silicon carbide composites (SiC/SiC) are attractive candidate materials for structural and functional components in fusion energy systems. The effect of neutron irradiation on damage tolerance of the nuclear grade SiC/SiC composites (plain woven Hi-Nicalon™ Type-S reinforced CVI matrix composites multilayer interphase and unidirectional Tyranno™-SA3 reinforced NITE matrix with carbon mono-layer interphase) was evaluated by means of miniaturized single-edged notched beam test. No significant changes in crack extension behavior and in the load-loadpoint displacement characteristics such as the peak load and hysteresis loop width were observed after irradiation to 5.9 × 1025 n/m2 (E > 0.1 MeV) at 800°C and to 5.8 × 1025 n/m2 at 1300°C. By applying a global energy balance analysis based on non-linear fracture mechanics, the energy release rate for these composite materials was found to be unchanged by irradiation with a value of 3±2 kJ/m2. This has led to the conclusion that, for these fairly aggressive irradiation conditions, the effect of neutron irradiation on the fracture resistance of these composites appears insignificant.

  2. Terahertz generation from electron- and neutron-irradiated semiconductor crystal surfaces

    NASA Astrophysics Data System (ADS)

    Bereznaya, S. A.; Korotchenko, Z. V.; Redkin, R. A.; Sarkisov, S. Yu.; Brudnyi, V. N.; Kosobutsky, A. V.; Atuchin, V. V.

    2016-07-01

    Terahertz generation from the InP, InSb, GaAs and GaSe crystal surfaces excitated by femtosecond laser pulses has been studied. The terahertz spectra emitted from the native crystals and the crystals previously irradiated by high-energy neutrons or electrons have been recorded. Also, a simulation of the terahertz emission process has been performed. A weak terahertz signal generated from the GaSe native surface has been registered. In the case of electron-irradiated GaSe, the signal is increased several fold because of increased laser radiation absorption.

  3. Fissile solution dynamics: Student research

    SciTech Connect

    Hetrick, D.L.

    1994-09-01

    There are two research projects in criticality safety at the University of Arizona: one in dynamic simulation of hypothetical criticality accidents in fissile solutions, and one in criticality benchmarks using transport theory. We have used the data from nuclear excursions in KEWB, CRAC, and SILENE to help in building models for solution excursions. An equation of state for liquids containing gas bubbles has been developed and coupled to point-reactor dynamics in an attempt to predict fission rate, yield, pressure, and kinetic energy. It appears that radiolytic gas is unimportant until after the first peak, but that it does strongly affect the shape of the subsequent power decrease and also the dynamic pressure.

  4. Defect structure development in a pure iron and dilute iron alloys irradiated with neutrons and electrons

    NASA Astrophysics Data System (ADS)

    Okada, A.; Maeda, H.; Hamada, K.; Ishida, I.

    The defect structure and mechanical property changes were observed for pure iron of 99.99% purity and a series of Fe-(0.1% and 0.4%) Cr and Fe-(0.1% and 0.4%) Mn dilute alloys irradiated with neutrons. From the comparison of the defect structures with yield strength change, a large contribution of the invisible defect clusters to the irradiation hardening was expected in the specimens irradiated in Japan Materials Test Reactor (JMTR), whereas these clusters are not found after irradiation in the Fast Flux Test Facility (FFTF). The electron irradiation experiments showed that addition of chromium and manganese to 0.1% in pure iron, development of large dislocation loops is suppressed, and frequent nucleation of small loops at the early stage of the electron irradiation is observed, similar to that in ultra-high purity iron of 99.9999% purity. The mechanisms of dislocation loop development in the early stage of irradiation for Fe-Cr and Fe-Mn are considered to be different.

  5. Effects of neutron irradiation on microstructural evolution in candidate low activation ferritic steels

    NASA Astrophysics Data System (ADS)

    Kohno, Yutaka; Kohyama, Akira; Yoshino, Masahiko; Asakura, Kentaro

    1994-09-01

    Fe-(2.25-12)Cr-2W-V, Ta low activation ferritic steels (JLF series steels) were developed in the fusion materials development program of Japanese universities. Microstructural observations, including precipitation response, were performed after neutron irradiation in the FFTF/MOTA. The preirradiation microstructure was stable after irradiation at low temperature (< 683 K). Recovery of martensitic lath structure and coarsening of precipitates took place above 733 K. Precipitates observed after irradiation were the same as those in unirradiated materials in 7-9Cr steels, and no irradiation induced phase was identified. The irradiation induced shift in DBTT in the 9Cr-2W steel proved to be very small which is a reflection of stable precipitation response in these steels. A high density of fine α' precipitates was observed in the 12Cr steel which might be responsible for the large irradiation hardening found in the 12Cr steel. Void formation was observed in 7-9Cr steels irradiated at 683 K, but the amount of void swelling was very small.

  6. The neutron irradiation effect on the mechanical properties and structure of beryllium

    SciTech Connect

    Fabritsiev, S.A.; Pokrovsky, A.S.; Bagautdinov, R.M.

    1999-10-01

    The neutron irradiation effect on the mechanical properties and structure of beryllium are presented. Irradiation was performed in the BOR-60 reactor up to doses of 0.7--1.1 {times} 10{sup 22} n/cm{sup 2} (E > 0.1 MeV) at irradiation temperatures of 350 C, 400 C, 520 C, 780 C. Two modifications of RF beryllium, i.e., DShG-200 and TShG-56, were chosen for investigation. For irradiation at temperatures of 350--400 C Be hardening due to the accumulation of radiation defect complexes. Hardening is accompanied with a sharp drop in plasticity at T{sub test} {le} 300 C. The fracture of samples is of brittle, mainly transcrystallite, type. High-temperature irradiation (T{sub irr} = 780 C) gives rise to large helium pores over the grain boundaries and smaller pores in the grain body. Fracture is brittle and intercrystalline at T{sub test} {ge} 600 C. Helium embrittlement is also accompanied with a drop in the Be mechanical properties. The conclusion is made that the irradiation temperature range, where irradiated beryllium has a satisfactory level of properties, is rather narrow: 300 C {le} T {le} 500 C.

  7. Properties of copper?stainless steel HIP joints before and after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Tähtinen, S.; Laukkanen, A.; Singh, B. N.; Toft, P.

    2002-12-01

    The tensile and fracture behaviour of CuCrZr and CuAl25 IG0 alloys joint to 316L(N) stainless steel by hot isostatic pressing (HIP) have been determined in unirradiated and neutron-irradiated conditions. The tensile and fracture behaviour of copper alloy HIP joint specimens are dominated by the properties of the copper alloys, and particularly, by the strength mismatch and mismatch in strain hardening capacities between copper alloys and stainless steel. The test temperature, neutron irradiation and thermal cycles primarily affect the copper alloy HIP joint properties through changing the strength mismatch between the base alloys. Changes in the loading conditions i.e. tensile, bend ( JI) and mixed-mode bend ( JI/ JII) lead to different fracture modes in the copper alloy HIP joint specimens.

  8. 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

  9. Grain boundary segregation in neutron-irradiated 304 stainless steel studied by atom probe tomography

    NASA Astrophysics Data System (ADS)

    Toyama, T.; Nozawa, Y.; Van Renterghem, W.; Matsukawa, Y.; Hatakeyama, M.; Nagai, Y.; Al Mazouzi, A.; Van Dyck, S.

    2012-06-01

    Radiation-induced segregation (RIS) of solute atoms at a grain boundary (GB) in 304 stainless steel (SS), neutron-irradiated to a dose of 24 dpa at 300 °C in the fuel wrapper plates of a commercial pressurized water reactor, was investigated using laser-assisted atom probe tomography (APT). Ni, Si, and P enrichment and Cr and Fe depletion at the GB were evident. The full-width at half-maximum of the RIS region was ˜3 nm for the concentration profile peaks of Ni and Si. The atomic percentages of Ni, Si, and Cr at the GB were ˜19%, ˜7%, and ˜14%, respectively, in agreement with previously-reported values for neutron-irradiated SS. A high number density of intra-granular Ni-Si rich precipitates formed in the matrix. A precipitate-denuded zone with a width of ˜10 nm appeared on both sides of the GB.

  10. Study of the response of PICASSO bubble detectors to neutron irradiation

    NASA Astrophysics Data System (ADS)

    Marlisov, Daniiar

    The objective of this work was to simulate the PICASSO experiment and to study the detector response to neutron irradiation. The results of the simulation show the rock neutron rate to be 1-2 neutrons/day for the setup used until 2009 and less than 0.1 neutrons/day for the setup used after 2010. The shielding efficiency was calculated to be 98% and 99.6% for the two setups respectively. The detector response to an AmBe source was simulated. Neutron rates differ for two AmBe source spectra from the literature. The observed data rate is in agreement with the rate from the simulation. The detector stability was examined and found to be stable. The source position and orientation affect the detector efficiency creating a systematic uncertainity on the order of 10-35%. This uncertainity was eliminated with a source holder. The localisation of recorded events inside the detector and the simulated neutron distribution agree.

  11. Irradiation tests of prototype self-powered gamma and neutron detectors

    SciTech Connect

    Vermeeren, L.; Carcreff, H.

    2011-07-01

    In the framework of the SCK.CEN-CEA Joint Instrumentation Laboratory, we are developing and optimizing a self-powered detector for selective in-core monitoring of the gamma field. Several prototypes with bismuth emitters were developed and tested in a pure gamma field (the PAGURE gamma irradiation facility at CEA) and in mixed neutron and gamma fields (in the OSIRIS reactor at CEA and in the BR2 reactor at SCK.CEN). Detailed MCNP modelling was performed to calculate the gamma and neutron sensitivities. Apart from a few failing prototypes, all detectors showed equilibrium signals proportional to the gamma field with a good long-term stability (under irradiation during several weeks). A tubular geometry design was finally selected as the most appropriate for in-core gamma detection, coupling a larger sensitivity with better response characteristics. In the same experiment in BR2 six prototype Self-Powered Neutron Detectors (SPNDs) with continuous sheaths (i.e. without any weld between the sensitive part and the cable) were extensively tested: two SPNDs with Co emitter, two with V emitter and two with Rh emitters, with varying geometries. All detector responses were verified to be proportional to the reactor power. The prompt and delayed response contributions were quantified. The signal contributions due to the impact of gamma rays were experimentally determined. The evolution of the signals was continuously followed during the full irradiation period. The signal-to-noise level was observed to be well below 1% in typical irradiation conditions. The absolute neutron and gamma responses for all SPNDs are consistent. (authors)

  12. Random effects of fissile lumps in molten salt reactors

    SciTech Connect

    Dulla, S.; Ravetto, P.; Prinja, A. K.

    2013-07-01

    The problem of the effect of fissile lumps spatially appearing in a random fashion inside a fluid fuel reactor is addressed. The effect on reactivity is evaluated by means of first-order perturbation theory. The analysis is carried out in diffusion theory with the presence of delayed neutron emissions in one dimensional plane geometry. The estimation of the mean value and standard deviation of the reactivity inserted is performed by Monte Carlo simulations and a deterministic quadrature approach, to compare the methods in terms of computational effort and the accuracy of the results. The results presented show that the effects constitute an important issue in the assessment of these innovative systems. (authors)

  13. Recovery capacity of glial progenitors after in vivo fission-neutron or X irradiation: age dependence, fractionation and low-dose-rate irradiations.

    PubMed

    Philippo, H; Winter, E A M; van der Kogel, A J; Huiskamp, R

    2005-06-01

    Previous experiments on the radiosensitivity of O-2A glial progenitors determined for single-dose fission-neutron and X irradiation showed log-linear survival curves, suggesting a lack of accumulation of recovery of sublethal damage. In the present study, we addressed this question and further characterized the radiobiological properties of these glial stem cells by investigating the recovery capacity of glial stem cells using either fractionated or protracted whole-body irradiation. Irradiations were performed on newborn, 2-week-old or 12-week-old rats. Fractionated irradiations (four fractions) were performed with 24-h intervals, followed by cell isolations 16- 24 h after the last irradiation. Single-dose irradiations were followed by cell isolation 16-24 h after irradiation or delayed cell isolation (4 days after irradiation) of the O-2A progenitor cells from either spinal cord (newborns) or optic nerve (2- and 12-week-old rats). Results for neonatal progenitor cell survival show effect ratios for both fractionated fission-neutron and X irradiation of the order of 1.8 when compared with single-dose irradiation. A similar ratio was found after single-dose irradiation combined with delayed plating. Comparable results were observed for juvenile and adult optic nerve progenitors, with effect ratios of the order of 1.2. The present investigation clearly shows that fractionated irradiation regimens using X rays or fission neutrons and CNS tissue from rats of various ages results in an increase in O-2A progenitor cell survival while repair is virtually absent. This recovery of the progenitor pool after irradiation can be observed at all ages but is greatest in the neonatal spinal cord and can probably be attributed to repopulation. PMID:15913395

  14. Simulation of synergistic effects on lateral PNP bipolar transistors induced by neutron and gamma irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Chenhui; Bai, Xiaoyan; Chen, Wei; Yang, Shanchao; Liu, Yan; Jin, Xiaoming; Ding, Lili

    2015-10-01

    With semiconductor device simulation software TCAD, numerical simulations of ionizing/displacement synergistic effects on 6 kinds of lateral PNP bipolar transistors induced by the mixed irradiation of neutron and gamma are carried out by means of changing the minority carrier lifetimes, adding charged traps to the oxide layer and increasing the surface recombination velocity in Si/SiO2 interface. The results indicate that ionizing/displacement synergistic effects on the lateral PNP bipolar transistors are not a simple sum of total ionizing dose effects and displacement effects, and total ionizing dose effects can enhance neutron displacement damages, leading to greater gain degradation. The physical mechanisms of ionizing/displacement synergistic effects are analyzed based on the results. The positive charge in the oxide layer and Si/SiO2 interface traps induced by gamma irradiation can enhance the recombination processes of carriers in the bulk defects induced by neutron irradiation, and this is the main cause of ionizing/displacement synergistic effects on the lateral PNP bipolar transistors.

  15. Energy spectra of primary knock-on atoms under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Gilbert, M. R.; Marian, J.; Sublet, J.-Ch.

    2015-12-01

    Materials subjected to neutron irradiation will suffer from a build-up of damage caused by the displacement cascades initiated by nuclear reactions. Previously, the main "measure" of this damage accumulation has been through the displacements per atom (dpa) index, which has known limitations. This paper describes a rigorous methodology to calculate the primary atomic recoil events (often called the primary knock-on atoms or PKAs) that lead to cascade damage events as a function of energy and recoiling species. A new processing code SPECTRA-PKA combines a neutron irradiation spectrum with nuclear recoil data obtained from the latest nuclear data libraries to produce PKA spectra for any material composition. Via examples of fusion relevant materials, it is shown that these PKA spectra can be complex, involving many different recoiling species, potentially differing in both proton and neutron number from the original target nuclei, including high energy recoils of light emitted particles such as α-particles and protons. The variations in PKA spectra as a function of time, neutron field, and material are explored. The application of PKA spectra to the quantification of radiation damage is exemplified using two approaches: the binary collision approximation and stochastic cluster dynamics, and the results from these different models are discussed and compared.

  16. Spectral effects in low-dose fission and fusion neutron irradiated metals and alloys

    SciTech Connect

    Heinisch, H.L.; Atkin, S.D.; Martinez, C.

    1986-04-01

    Flat miniature tensile specimens were irradiated to neutron fluences up to 9 x 10/sup 22/ n/m/sup 2/ in the RTNS-II and in the Omega West Reactor. Specimen temperatures were the same in both environments, with runs being made at both 90/sup 0/C and 290/sup 0/C. The results of tensile tests on AISI 316 stainless steel, A302B pressure vessel steel and pure copper are reported here. The radiation-induced changes in yield strength as a function of neutron dose in each spectrum are compared. The data for 316 stainless steel correlate well on the basis of displacements per atom (dpa), while those for copper and A302B do not. In copper the ratio of fission dpa to 14 MeV neutron dpa for a given yield stress change is about three to one. In A302B pressure vessel steel this ratio is more than three at lower fluences, but the yield stress data for fission and 14 MeV neutron-irradiated A302B steel appears to coalesce or intersect at the higher fluences.

  17. 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

  18. Photon and neutron dose contributions and mean quality factors in phantoms of different size irradiated by monoenergetic neutrons

    SciTech Connect

    Dietze, G.; Siebert, B.R.L.

    1994-10-01

    The International Commission on Radiological Protection (ICRP) in its Publication 60 introduced important changes in the concept of risk-related quantities. For external neutron radiation in particular the introduction of the equivalent dose with the radiation weighting factor w{sub R} instead of the dose equivalent concept with the quality factor Q(L) has many consequences. The value of w{sub R} is defined by the external neutron radiation field, while the radiation quality in the phantom depends on the radiation field at the position of interest and hence on the size of and the position in the phantom. It has been investigated to what extent the size of the phantom influences the mean irradiation quality in the phantoms. For incident monoenergetic neutrons, mean photon dose contributions and mean quality factors have been calculated. Results are presented for various phantoms which characterize the conditions for a mouse, a rat, the ICRU sphere and a human body. 9 refs., 2 figs., 1 tab.

  19. Tritium Retention and Permeation in Ion- and Neutron-Irradiated Tungsten under US-Japan PHENIX Collaboration

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi; Taylor, Chase N.; Kolasinski, Robert D.; Buchenauer, Dean A.; Chikada, Takumi; Oya, Yasuhisa; Hatano, Yuji

    2015-11-01

    A critical challenge for long-term operation of ITER and beyond to a FNSF, a DEMO and future fusion reactor will be the development of plasma-facing components (PFCs) that demonstrate erosion resistance to intense heat and neutral/ion particle fluxes under the extreme fusion nuclear environment, while minimizing in-vessel inventories and ex-vessel permeation of tritium. Recent work at Tritium Plasma Experiment demonstrated that tritium diffuses in bulk tungsten at elevated temperatures, and can be trapped in radiation-induced trap site (up to 1 at. % T/W) in tungsten [M. Shimada, et.al., Nucl. Fusion 55 (2015) 013008]. US-Japan PHENIX collaboration (2013-2019) investigates irradiation response on tritium behavior in tungsten, and performs one-of-a-kind neutron-irradiation with Gd thermal neutron shield at High Flux Isotope Reactor, ORNL. This presentation describes the challenge in elucidating tritium behavior in neutron-irradiated PFCs, the PHENIX plans for neutron-irradiation and post irradiation examination, and the recent findings on tritium retention and permeation in 14MeV neutron-irradiated and Fe ion irradiated tungsten. This work was prepared for the U.S. Department of Energy, Office of Fusion Energy Sciences, under the DOE Idaho Field Office contract number DE-AC07-05ID14517.

  20. Mechanical properties of advanced SiC/SiC composites after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Ozawa, K.; Nozawa, T.; Katoh, Y.; Hinoki, T.; Kohyama, A.

    2007-08-01

    The effect of neutron irradiation on tensile properties in advanced 2D-SiC/SiC composites was evaluated. The composites used were composed of a SiC matrix obtained by the forced-flow chemical vapor infiltration (FCVI) process and either Tyranno™-SA Grade-3 or Hi-Nicalon™ Type-S fibers with single-layered PyC coating as the interphase. Neutron irradiation fluence and temperature were 3.1 × 10 25 n/m 2 ( E > 0.1 MeV) and 1.2 × 10 26 n/m 2 at 740-750 °C. Tensile properties were evaluated by cyclic tensile test, and hysteresis loop analysis was applied in order to evaluate interfacial properties. Both composites exhibited excellent irradiation resistance in ultimate and proportional limit tensile stresses. From the hysteresis loop analysis, the level of interfacial sliding stress decreased significantly after irradiation to 1.5 × 10 26 n/m 2 at 750 °C.

  1. 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.

  2. Neutron irradiation effects in magnesium-aluminate spinel doped with transition metals

    NASA Astrophysics Data System (ADS)

    Gritsyna, V. T.; Afanasyev-Charkin, I. V.; Kobyakov, V. A.; Sickafus, K. E.

    2000-12-01

    We present data on optical properties for stoichiometric (MgO · Al 2O 3) and non-stoichiometric (MgO · 2Al 2O 3) spinel crystals: (1) nominally pure; (2) doped with transition metals Mn, Cr, and Fe to a concentration of 0.01 wt%; (3) irradiated with neutrons to a fluence of 1.8×10 21 m -2; (4) post-annealed at 650 K. The temperature during neutron irradiation was 350 K. Optical absorption and thermoluminescence measurements were performed on irradiated and annealed samples at room temperature. Results of absorption measurements show spectra with the following features: (1) a prominent band at 2.33 eV (for stoichiometric spinel); (2) overlapping bands attributed to hole centers (3.17 eV); (3) optical centers on antisite defects (3.78 and 4.14 eV); (4) F +- and F-centers (4.75 and 5.3 eV); (5) bands related to defect complexes. For nominally pure samples, the efficiency of optical center formation in stoichiometric spinel is half that in non-stoichiometric spinel. Doped crystals exhibit high efficiencies for defect creation, independent of spinel composition. All dopants enhance the efficiency of defect creation in spinel. Doping with Mn has the least effect on increasing the number of radiation-induced stable defects. Apparently, impurities in spinel serve as centers for stabilization of irradiation-induced interstitials or vacancies.

  3. Transmission electron microscopy study on neutron irradiated pure iron and RPV model alloys

    NASA Astrophysics Data System (ADS)

    Hernández-Mayoral, M.; Gómez-Briceño, D.

    2010-04-01

    The radiation induced microstructure was examined by Transmission Electron Microscopy in Fe, FeCu, FeMnCuNi, FeMnNi and a Reactor Pressure Vessel steel that were neutron irradiated to 0.026, 0.051, 0.10 and 0.19 dpa at 300 °C. The effect of dose and composition on defect accumulation and microstructure evolution was investigated. The damaged microstructure consisted in the presence of dislocation loops of interstitial type. The presence of voids was also studied in pure iron. Results on density, size and Burgers vector of radiation induced dislocation loops showed that the evolution of the interstitial component of the neutron irradiation induced microstructure was strongly affected by the presence of solutes such as Cu, Mn and Ni. Density and size increased with increasing dose in all the materials, while the effect of solutes is clearly to decrease the size of defects compared to pure iron. It has been observed that, for the same irradiation dose, the defect size decreases as the material becomes more complex, with the extreme case of the RPV steel where no defects were observed at any of the irradiation doses studied.

  4. Irradiation creep of nano-powder sintered silicon carbide at low neutron fluences

    NASA Astrophysics Data System (ADS)

    Koyanagi, T.; Shimoda, K.; Kondo, S.; Hinoki, T.; Ozawa, K.; Katoh, Y.

    2014-12-01

    The irradiation creep behavior of nano-powder sintered silicon carbide was investigated using the bend stress relaxation method under neutron irradiation up to 1.9 dpa. The creep deformation was observed at all temperatures ranging from 380 to 1180 °C mainly from the irradiation creep but with the increasing contributions from the thermal creep at higher temperatures. The apparent stress exponent of the irradiation creep slightly exceeded unity, and instantaneous creep coefficient at 380-790 °C was estimated to be ∼1 × 10-5 [MPa-1 dpa-1] at ∼0.1 dpa and 1 × 10-7 to 1 × 10-6 [MPa-1 dpa-1] at ∼1 dpa. The irradiation creep strain appeared greater than that for the high purity SiC. Microstructural observation and data analysis indicated that the grain-boundary sliding associated with the secondary phases contributes to the irradiation creep at 380-790 °C to 0.01-0.11 dpa.

  5. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance L.

    2015-10-01

    The Fe-Cr-Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe-Cr-Al alloys has not been fully established. In this study, a series of Fe-Cr-Al alloys with 10-18 wt % Cr and 2.9-4.9 wt % Al were neutron irradiated at 382 °C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2<111> and a<100> were detected and quantified. Results indicate precipitation of Cr-rich α‧ is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. A structure-property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α‧ precipitates at sufficiently high chromium contents after irradiation.

  6. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    DOE PAGESBeta

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance Lewis

    2015-07-14

    The Fe Cr Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe Cr Al alloys has not been fully established. In this study, a series of Fe Cr Al alloys with 10 18 wt % Cr and 2.9 4.9 wt % Al were neutron irradiated at 382 C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition.more » Dislocation loops with Burgers vector of a/2 111 and a 100 were detected and quantified. Results indicate precipitation of Cr-rich is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. Furthermore, a structure property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α' precipitates at sufficiently high chromium contents after irradiation.« less

  7. Nano-cluster stability following neutron irradiation in MA957 oxide dispersion strengthened material

    NASA Astrophysics Data System (ADS)

    Ribis, J.; Lozano-Perez, S.

    2014-01-01

    ODS steels are promising materials for Sodium cooled Fast Reactors since their fine distribution of nano-clusters confers excellent mechanical properties. However, the nano-feature stability needs to be assessed under neutron irradiation. Before irradiation, the characterizations show that nano-particles are finely distributed within the ferritic matrix and are identified to have a pyrochlore type structure. After irradiation of the MA957 alloy in the Phenix French reactor at 412 °C up to 50 dpa and 430 °C up to 75 dpa, transmission electron microscopy characterization reveals a very slight density fall but no distinguishable difference in nano-features size before and after irradiation. In addition, after both irradiations, the nano-oxides are still (Y, Ti, O) compounds with orientation relationship with the matrix. A multislice simulation of high resolution images suggests that nano-particles still have a fcc pyrochlore type structure after irradiation. A possible change of lattice parameter seems to be highlighted, possibly due to disordering by cascade effect.

  8. Neutron-irradiation creep of silicon carbide materials beyond the initial transient

    NASA Astrophysics Data System (ADS)

    Koyanagi, Takaaki; Katoh, Yutai; Ozawa, Kazumi; Shimoda, Kazuya; Hinoki, Tatsuya; Snead, Lance L.

    2016-09-01

    Irradiation creep beyond the transient regime was investigated for various silicon carbide (SiC) materials. The materials examined included polycrystalline or monocrystalline high-purity SiC, nanopowder sintered SiC, highly crystalline and near-stoichiometric SiC fibers (including Hi-Nicalon Type S, Tyranno SA3, isotopically-controlled Sylramic and Sylramic-iBN fibers), and a Tyranno SA3 fiber-reinforced SiC matrix composite fabricated through a nano-infiltration transient eutectic phase process. Neutron irradiation experiments for bend stress relaxation tests were conducted at irradiation temperatures ranging from 430 to 1180 °C up to 30 dpa with initial bend stresses of up to ∼1 GPa for the fibers and ∼300 MPa for the other materials. Initial bend stress in the specimens continued to decrease from 1 to 30 dpa. Analysis revealed that (1) the stress exponent of irradiation creep above 1 dpa is approximately unity, (2) the stress normalized creep rate is ∼1 × 10-7 [dpa-1 MPa-1] at 430-750 °C for the range of 1-30 dpa for most polycrystalline SiC materials, and (3) the effects on irradiation creep of initial microstructures-such as grain boundary, crystal orientation, and secondary phases-increase with increasing irradiation temperature.

  9. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance L.

    2015-10-01

    The Fe-Cr-Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe-Cr-Al alloys has not been fully established. In this study, a series of Fe-Cr-Al alloys with 10-18 wt % Cr and 2.9-4.9 wt % Al were neutron irradiated at 382 °C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2<111> and a<100> were detected and quantified. Results indicate precipitation of Cr-rich α‧ is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. A structure-property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α‧ precipitates at sufficiently high chromium contents after irradiation.

  10. Neutron-irradiation creep of silicon carbide materials beyond the initial transient

    DOE PAGESBeta

    Katoh, Yutai; Ozawa, Kazumi; Shimoda, Kazuya; Hinoki, Tatsuya; Snead, Lance Lewis; Koyanagi, Takaaki

    2016-06-04

    Irradiation creep beyond the transient regime was investigated for various silicon carbide (SiC) materials. Here, the materials examined included polycrystalline or monocrystalline high-purity SiC, nanopowder sintered SiC, highly crystalline and near-stoichiometric SiC fibers (including Hi-Nicalon Type S, Tyranno SA3, isotopically-controlled Sylramic and Sylramic-iBN fibers), and a Tyranno SA3 fiber–reinforced SiC matrix composite fabricated through a nano-infiltration transient eutectic phase process. Neutron irradiation experiments for bend stress relaxation tests were conducted at irradiation temperatures ranging from 430 to 1180 °C up to 30 dpa with initial bend stresses of up to ~1 GPa for the fibers and ~300 MPa for themore » other materials. Initial bend stress in the specimens continued to decrease from 1 to 30 dpa. Analysis revealed that (1) the stress exponent of irradiation creep above 1 dpa is approximately unity, (2) the stress normalized creep rate is ~1 × 10–7 [dpa–1 MPa–1] at 430–750 °C for the range of 1–30 dpa for most polycrystalline SiC materials, and (3) the effects on irradiation creep of initial microstructures—such as grain boundary, crystal orientation, and secondary phases—increase with increasing irradiation temperature.« less

  11. Radiation tolerance of neutron-irradiated model Fe-Cr-Al alloys

    SciTech Connect

    Field, Kevin G.; Hu, Xunxiang; Littrell, Kenneth C.; Yamamoto, Yukinori; Snead, Lance Lewis

    2015-07-14

    The Fe Cr Al alloy system has the potential to form an important class of enhanced accident-tolerant cladding materials in the nuclear power industry owing to the alloy system's higher oxidation resistance in high-temperature steam environments compared with traditional zirconium-based alloys. However, radiation tolerance of Fe Cr Al alloys has not been fully established. In this study, a series of Fe Cr Al alloys with 10 18 wt % Cr and 2.9 4.9 wt % Al were neutron irradiated at 382 C to 1.8 dpa to investigate the irradiation-induced microstructural and mechanical property evolution as a function of alloy composition. Dislocation loops with Burgers vector of a/2 111 and a 100 were detected and quantified. Results indicate precipitation of Cr-rich is primarily dependent on the bulk chromium composition. Mechanical testing of sub-size-irradiated tensile specimens indicates the hardening response seen after irradiation is dependent on the bulk chromium composition. Furthermore, a structure property relationship was developed; it indicated that the change in yield strength after irradiation is caused by the formation of these radiation-induced defects and is dominated by the large number density of Cr-rich α' precipitates at sufficiently high chromium contents after irradiation.

  12. Quantitative characterization of microstructural defects in up to 32 dpa neutron irradiated EUROFER97

    NASA Astrophysics Data System (ADS)

    Weiß, Oliver J.; Gaganidze, Ermile; Aktaa, Jarir

    2012-07-01

    The microstructure of the neutron-irradiated reduced activation ferritic/martensitic (RAFM) steel EUROFER97 was evaluated by transmission electron microscopy (TEM). Emphasis was put on analyzing the influence of the irradiation dose on the evolution of size and density of microstructural defects like dislocation loops and voids at low irradiation temperatures of 330-340 °C. To study the dose dependence, samples irradiated to 15 and 32 dpa were analyzed. The weak-beam dark-field (WBDF) technique was applied to analyze dislocation loops and small defect clusters using different diffraction conditions. The average densities and sizes of the defects increase slightly from 1.4 × 1022 m-3 and 3.4 nm at 15 dpa to 1.7 × 1022 m-3 and 4.8 nm at 32 dpa. Through-focus series also revealed the presence of small voids in the material, but with a density at least one order of magnitude lower than that of the dislocation loops. In order to correlate the irradiation induced changes in the microstructure to the changes in the mechanical properties, the obtained quantitative data was used to estimate dose-dependent hardening with the dispersed barrier hardening model. The estimation of hardening by using recent literature results on the loop obstacle strength shows, that alone the defects visible in the TEM are not sufficient to explain the hardening quantified in the post-irradiation tensile tests.

  13. High dose effects in neutron irradiated face-centered cubic metals

    SciTech Connect

    Garner, F.A.; Toloczko, M.B.

    1993-06-01

    During neutron irradiation, most face-centered cubic metals and alloys develop saturation or quasi-steady state microstructures. This, in turn, leads to saturation levels in mechanical properties and quasi-steady state rates of swelling and creep deformation. Swelling initially plays only a small role in determining these saturation states, but as swelling rises to higher levels, it exerts strong feedback on the microstructure and its response to environmental variables. The influence of swelling, either directly or indirectly via second order mechanisms, such as elemental segregation to void surfaces, eventually causes major changes, not only in irradiation creep and mechanical properties, but also on swelling itself. The feedback effects of swelling on irradiation creep are particularly complex and lead to problems in applying creep data derived from highly pressurized creep tubes to low stress situations, such as fuel pins in liquid metal reactors.

  14. Neutron-irradiation effect on the mechanical properties of alumina fiber

    NASA Astrophysics Data System (ADS)

    Sakuma, Yoichi; Iwanaga, Katsusuke; Tsujimoto, Tadashi; Yoshimoto, Takaaki; Okada, Moritami; Miyata, Kiyomi; Iwanaga, Hiroshi

    1998-04-01

    This paper describes the neutron irradiation effects on the deterioration of alumina fiber (made by Mitsui Mining Material, Almax), a typical electrical insulation material. The material was irradiated at the research reactor at Kyoto University Research Reactor Institute with a maximum fluence of 5.6×10 23 n/m 2 (energy: E>0.1 MeV). Tensile strength and tensile modulus of the specimen scarcely changed. Observation with a scanning electron microscope (SEM) and a transmission electron microscope (TEM) did not indicate any changes in crystal or pore structure. However, the Weibull coefficient of tensile strength decreased as the irradiation dose increased. This suggests an increase in the defect size distribution.

  15. Microstructural changes in a neutron-irradiated Fe-15 at.%Cr alloy

    NASA Astrophysics Data System (ADS)

    Bachhav, Mukesh; Robert Odette, G.; Marquis, Emmanuelle A.

    2014-11-01

    Microstructural changes in a Fe-15 at.%Cr model alloy neutron irradiated to 1.82 dpa at 290 °C were characterized by atom probe tomography. Homogenously distributed α‧ precipitates as well as fewer clusters containing Si, P, Ni, and Cr, were observed in the matrix. Grain boundary analyses before and after irradiation revealed segregation of Cr, with W-shape concentration profiles developing in the vicinity of grain boundary carbide and nitride particles. After irradiation, impurities such as C, Si and P were segregated to the grain boundaries. Zones depleted of α‧ clusters, and Si were found at the interfaces of carbide and nitride precipitates and along grain boundaries in the vicinity of these precipitates.

  16. Apparatus for irradiating a continuously flowing stream of fluid. [For neutron activation analysis

    DOEpatents

    Speir, L.G.; Adams, E.L.

    1982-05-13

    An apparatus for irradiating a continuously flowing stream of fluid is disclosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4..pi.. radiation geometry. The irradiation source, for example a /sup 252/Cf neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

  17. Defect annealing and thermal desorption of deuterium in low dose HFIR neutron-irradiated tungsten

    SciTech Connect

    Masashi Shimada; M. Hara; T. Otsuka; Y. Oya; Y. Hatano

    2014-05-01

    Accurately estimating tritium retention in plasma facing components (PFCs) and minimizing its uncertainty are key safety issues for licensing future fusion power reactors. D-T fusion reactions produce 14.1 MeV neutrons that activate PFCs and create radiation defects throughout the bulk of the material of these components. Recent studies show that tritium migrates and is trapped in bulk (>> 10 µm) tungsten beyond the detection range of nuclear reaction analysis technique [1-2], and thermal desorption spectroscopy (TDS) technique becomes the only established diagnostic that can reveal hydrogen isotope behavior in in bulk (>> 10 µm) tungsten. Radiation damage and its recovery mechanisms in neutron-irradiated tungsten are still poorly understood, and neutron-irradiation data of tungsten is very limited. In this paper, systematic investigations with repeated plasma exposures and thermal desorption are performed to study defect annealing and thermal desorption of deuterium in low dose neutron-irradiated tungsten. Three tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) irradiated at High Flux Isotope Reactor at Oak Ridge National Laboratory were exposed to high flux (ion flux of (0.5-1.0)x1022 m-2s-1 and ion fluence of 1x1026 m-2) deuterium plasma at three different temperatures (100, 200, and 500 °C) in Tritium Plasma Experiment at Idaho National Laboratory. Subsequently, thermal desorption spectroscopy (TDS) was performed with a ramp rate of 10 °C/min up to 900 °C, and the samples were annealed at 900 °C for 0.5 hour. These procedures were repeated three (for 100 and 200 °C samples) and four (for 500 °C sample) times to uncover damage recovery mechanisms and its effects on deuterium behavior. The results show that deuterium retention decreases approximately 90, 75, and 66 % for 100, 200, and 500 °C, respectively after each annealing. When subjected to the same TDS recipe, the desorption temperature shifts from 800 °C to 600 °C after 1st annealing

  18. Comparison of properties and microstructures of Trefimetaux and Hycon 3HP{trademark} after neutron irradiation

    SciTech Connect

    Edwards, D.J.; Singh, B.N.; Toft, P.; Eldrup, M.

    1998-09-01

    The precipitation strengthened CuNiBe alloys are among three candidate copper alloys being evaluated for application in the first wall, divertor, and limiter components of ITER. Generally, CuNiBe alloys have higher strength but poorer conductivity compared to CuCrZr and CuAl{sub 2}O{sub 3} alloys. Brush-Wellman Inc. has manufactured an improved version of their Hycon CuNiBe alloy that has higher conductivity while maintaining a reasonable level strength. It is of interest, therefore, to investigate the effect of radiation on the physical and mechanical properties of this alloy. In the present work the authors have investigated the physical and mechanical properties of the Hycon 3HP{trademark} alloy both before and after neutron irradiation and have compared its microstructure and properties with the European CuNiBe candidate alloy manufactured by Trefirmetaux. Tensile specimens of both alloys were irradiated in the DR-3 reactor at Risoe to displacement dose levels up to 0.3 dpa at 100, 250 and 350 C. Both alloys were tensile tested in the unirradiated and irradiated conditions at 100, 250 and 350 C. Both pre- and post-irradiation microstructures of the alloys were investigated in detail using transmission electron microscopy. Fracture surfaces were examined under a scanning electron microscope. Electrical resistivity measurements were made on tensile specimens before and after irradiation; all measurements were made at 23 C. At this point it seems unlikely that CuNiBe alloys can be recommended for applications in neutron environments where the irradiation temperature exceeds 200 C. Applications at temperatures below 200 C might be plausible, but only after careful experiments have determined the dose dependence of the mechanical properties and the effect of sudden temperature excursions on the material to establish the limits on the use of the alloy.

  19. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    DOE PAGESBeta

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Wirth, Brian D; Snead, Lance Lewis

    2016-01-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (~90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutronmore » irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S–W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage. This provides insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.« less

  20. PGNAA system preliminary design and measurement of In-Hospital Neutron Irradiator for boron concentration measurement.

    PubMed

    Zhang, Zizhu; Chong, Yizheng; Chen, Xinru; Jin, Congjun; Yang, Lijun; Liu, Tong

    2015-12-01

    A prompt gamma neutron activation analysis (PGNAA) system has been recently developed at the 30-kW research reactor In-Hospital Neutron Irradiator (IHNI) in Beijing. Neutrons from the specially designed thermal neutron beam were used. The thermal flux of this beam is 3.08×10(6) cm(-2) s(-1) at a full reactor power of 30 kW. The PGNAA system consists of an n-type high-purity germanium (HPGe) detector of 40% efficiency, a digital spectrometer, and a shielding part. For both the detector shielding part and the neutron beam shielding part, the inner layer is composed of (6)Li2CO3 powder and the outer layer lead. The boron-10 sensitivity of the PGNAA system is approximately 2.5 cps/ppm. Two calibration curves were produced for the 1-10 ppm and 10-50 ppm samples. The measurement results of the control samples were in accordance with the inductively coupled plasma atomic emission spectroscopy (ICP-AES) results. PMID:26242556

  1. Fusion neutron yield from a laser-irradiated heavy-water spray

    SciTech Connect

    Ter-Avetisyan, S.; Schnuerer, M.; Hilscher, D.; Jahnke, U.; Busch, S.; Nickles, P.V.; Sandner, W.

    2005-01-01

    The fusion neutron yield from a laser-irradiated heavy-water (D{sub 2}O) spray target was studied. Heavy-water droplets of about 150 nm diameter in the spray were exposed to 35 fs laser pulses at an intensity of 1x10{sup 19} W/cm{sup 2}. Due to the 10-50 times bigger size of the spray droplets compared to usual cluster sizes, deuterons are accelerated to considerably higher kinetic energies of up to 1 MeV. Neutrons are generated by the deuterons escaping from the plasma and initiating a fusion reaction within the surrounding cold plume of the spray jet. For each 0.6 J of laser pulse energy, 6x10{sup 3} neutrons are produced by about 10{sup 11} accelerated deuterons. This corresponds to a D(d,n) reaction probability of about 6x10{sup -8}. Compared to cluster targets, the reaction probability in the spray target is found to be two orders of magnitude larger. This finding apparently is due to both the considerably higher deuteron energies and the larger effective target thickness in the spray target. The measured neutron yield per accelerated deuteron [i.e., the D(d,n) reaction probability], is employed to compare and extrapolate the neutron emission characteristics from different target arrangements.

  2. Genome Resilience and Prevalence of Segmental Duplications Following Fast Neutron Irradiation of Soybean

    PubMed Central

    Bolon, Yung-Tsi; Stec, Adrian O.; Michno, Jean-Michel; Roessler, Jeffrey; Bhaskar, Pudota B.; Ries, Landon; Dobbels, Austin A.; Campbell, Benjamin W.; Young, Nathan P.; Anderson, Justin E.; Grant, David M.; Orf, James H.; Naeve, Seth L.; Muehlbauer, Gary J.; Vance, Carroll P.; Stupar, Robert M.

    2014-01-01

    Fast neutron radiation has been used as a mutagen to develop extensive mutant collections. However, the genome-wide structural consequences of fast neutron radiation are not well understood. Here, we examine the genome-wide structural variants observed among 264 soybean [Glycine max (L.) Merrill] plants sampled from a large fast neutron-mutagenized population. While deletion rates were similar to previous reports, surprisingly high rates of segmental duplication were also found throughout the genome. Duplication coverage extended across entire chromosomes and often prevailed at chromosome ends. High-throughput resequencing analysis of selected mutants resolved specific chromosomal events, including the rearrangement junctions for a large deletion, a tandem duplication, and a translocation. Genetic mapping associated a large deletion on chromosome 10 with a quantitative change in seed composition for one mutant. A tandem duplication event, located on chromosome 17 in a second mutant, was found to cosegregate with a short petiole mutant phenotype, and thus may serve as an example of a morphological change attributable to a DNA copy number gain. Overall, this study provides insight into the resilience of the soybean genome, the patterns of structural variation resulting from fast neutron mutagenesis, and the utility of fast neutron-irradiated mutants as a source of novel genetic losses and gains. PMID:25213171

  3. Neutron, gamma ray and post-irradiation thermal annealing effects on power semiconductor switches

    NASA Technical Reports Server (NTRS)

    Schwarze, G. E.; Frasca, A. J.

    1991-01-01

    The effects of neutron and gamma rays on the electrical and switching characteristics of power semiconductor switches must be known and understood by the designer of the power conditioning, control, and transmission subsystem of space nuclear power systems. The SP-100 radiation requirements at 25 m from the nuclear source are a neutron fluence of 10(exp 13) n/sq cm and a gamma dose of 0.5 Mrads. Experimental data showing the effects of neutrons and gamma rays on the performance characteristics of power-type NPN Bipolar Junction Transistors (BJTs), Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), and Static Induction Transistors (SITs) are presented. These three types of devices were tested at radiation levels which met or exceeded the SP-100 requirements. For the SP-100 radiation requirements, the BJTs were found to be most sensitive to neutrons, the MOSFETs were most sensitive to gamma rays, and the SITs were only slightly sensitive to neutrons. Post-irradiation thermal anneals at 300 K and up to 425 K were done on these devices and the effectiveness of these anneals are also discussed.

  4. Fusion neutron yield from a laser-irradiated heavy-water spray

    NASA Astrophysics Data System (ADS)

    Ter-Avetisyan, S.; Schnürer, M.; Hilscher, D.; Jahnke, U.; Busch, S.; Nickles, P. V.; Sandner, W.

    2005-01-01

    The fusion neutron yield from a laser-irradiated heavy-water (D2O) spray target was studied. Heavy-water droplets of about 150nm diameter in the spray were exposed to 35fs laser pulses at an intensity of 1×1019W/cm2. Due to the 10-50 times bigger size of the spray droplets compared to usual cluster sizes, deuterons are accelerated to considerably higher kinetic energies of up to 1MeV. Neutrons are generated by the deuterons escaping from the plasma and initiating a fusion reaction within the surrounding cold plume of the spray jet. For each 0.6J of laser pulse energy, 6×103 neutrons are produced by about 1011 accelerated deuterons. This corresponds to a D(d ,n) reaction probability of about 6×10-8. Compared to cluster targets, the reaction probability in the spray target is found to be two orders of magnitude larger. This finding apparently is due to both the considerably higher deuteron energies and the larger effective target thickness in the spray target. The measured neutron yield per accelerated deuteron [i.e., the D(d ,n) reaction probability], is employed to compare and extrapolate the neutron emission characteristics from different target arrangements.

  5. Neutron, gamma ray and post-irradiation thermal annealing effects on power semiconductor switches

    SciTech Connect

    Schwarze, G.E.; Frasca, A.J.

    1994-09-01

    The effects of neutrons and gamma rays on the electrical and switching characteristics of power semiconductor switches must be known and understood by the designer of the power conditioning, control, and transmission subsystem of space nuclear power systems. The SP-100 radiation requirements at 25 m from the nuclear source are a neutron fluence of 10{sup 13} n/cm {sup 2} and a gamma dose of 0.5 Mrads. Experimental data showing the effects of neutrons and gamma rays on the performance characteristics of power-type NPN Bipolar Junction Transistors (BJTs), Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), and Static Induction Transistors (SITs) are given in this paper. These three types of devices were tested at radiation levels which met or exceeded the SP-100 requirements. For the SP-100 radiation requirements, the BJTs were found to be most sensitive to neutrons, the MOSFETs were most sensitive to gamma rays, and the SITs were only slightly sensitive to neutrons. Post-irradiation thermal anneals at 300 K and up to 425 K were done on these devices and the effectiveness of these anneals are also discussed.

  6. Post-irradiation annealing behavior of neutron-irradiated FeCu, FeMnNi and FeMnNiCu model alloys investigated by means of small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Bergner, F.; Ulbricht, A.; Lindner, P.; Keiderling, U.; Malerba, L.

    2014-11-01

    Neutron irradiation of reactor pressure vessel steels gives rise to the formation of thermodynamically stable and unstable nano-features. The present work is focused on the stability of Cu-, Mn- and Ni-containing solute clusters in model alloys exposed to post-irradiation annealing. Fe0.1Cu, Fe1.2Mn0.7Ni and Fe1.2Mn0.7Ni0.1Cu (wt%) model alloys irradiated up to neutron exposures of 0.1 and 0.19 dpa (displacements per atom) were annealed at stepwise increasing temperatures in the range from 300 °C (i.e. near irradiation temperature) to 500 °C and characterized by means of small-angle neutron scattering (SANS). We have found characteristic differences in the annealing behavior of the alloys. In particular, there is a non-trivial (synergistic-antagonistic) interplay of Mn/Ni and Cu.

  7. Generation of peanut mutants by fast neutron irradiation combined with in vitro culture

    PubMed Central

    Wang, Jing-Shan; Sui, Jiong-Ming; Xie, Yong-Dun; Guo, Hui-Jun; Qiao, Li-Xian; Zhao, Li-Lan; Yu, Shan-Lin; Liu, Lu-Xiang

    2015-01-01

    Induced mutations have played an important role in the development of new plant varieties. In this study, we investigated the effects of fast neutron irradiation on somatic embryogenesis combined with plant regeneration in embryonic leaflet culture to develop new peanut (Arachis hypogaea L.) germplasm for breeding. The dry seeds of the elite cultivar Luhua 11 were irradiated with fast neutrons at dosages of 9.7, 14.0 and 18.0 Gy. The embryonic leaflets were separated and incubated in a medium with 10.0-mg/l 2,4-D to induce somatic embryogenesis. Next, they were incubated in a medium with 4.0-mg/l BAP for plant regeneration. As the irradiation dosage increased, the frequency of both somatic embryo formation and plantlet regeneration decreased. The regenerated plantlets were grafted onto rootstocks and were transplanted into the field. Later, the mature seeds of the regenerated plants were harvested. The M2 generation plants from most of the regenerated cultivars exhibited variations and segregation in vigor, plant height, branch and pod number, pod size, and pod shape. To determine whether the phenotypes were associated with genomic modification, we compared the DNA polymorphisms between the wild-type plants and 19 M3-generation individuals from different regenerated plants. We used 20 pairs of simple sequence repeat (SSR) primers and detected polymorphisms between most of the mutants and the wild-type plants (Luhua 11). Our results indicate that using a combination of fast neutron irradiation and tissue culture is an effective approach for creating new peanut germplasm. PMID:25653418

  8. Generation of peanut mutants by fast neutron irradiation combined with in vitro culture.

    PubMed

    Wang, Jing-Shan; Sui, Jiong-Ming; Xie, Yong-Dun; Guo, Hui-Jun; Qiao, Li-Xian; Zhao, Li-Lan; Yu, Shan-Lin; Liu, Lu-Xiang

    2015-05-01

    Induced mutations have played an important role in the development of new plant varieties. In this study, we investigated the effects of fast neutron irradiation on somatic embryogenesis combined with plant regeneration in embryonic leaflet culture to develop new peanut (Arachis hypogaea L.) germplasm for breeding. The dry seeds of the elite cultivar Luhua 11 were irradiated with fast neutrons at dosages of 9.7, 14.0 and 18.0 Gy. The embryonic leaflets were separated and incubated in a medium with 10.0-mg/l 2,4-D to induce somatic embryogenesis. Next, they were incubated in a medium with 4.0-mg/l BAP for plant regeneration. As the irradiation dosage increased, the frequency of both somatic embryo formation and plantlet regeneration decreased. The regenerated plantlets were grafted onto rootstocks and were transplanted into the field. Later, the mature seeds of the regenerated plants were harvested. The M2 generation plants from most of the regenerated cultivars exhibited variations and segregation in vigor, plant height, branch and pod number, pod size, and pod shape. To determine whether the phenotypes were associated with genomic modification, we compared the DNA polymorphisms between the wild-type plants and 19 M3-generation individuals from different regenerated plants. We used 20 pairs of simple sequence repeat (SSR) primers and detected polymorphisms between most of the mutants and the wild-type plants (Luhua 11). Our results indicate that using a combination of fast neutron irradiation and tissue culture is an effective approach for creating new peanut germplasm. PMID:25653418

  9. RhG-CSF improves radiation-induced myelosuppression and survival in the canine exposed to fission neutron irradiation.

    PubMed

    Yu, Zu-Yin; Li, Ming; Han, A-Ru-Na; Xing, Shuang; Ou, Hong-Ling; Xiong, Guo-Lin; Xie, Ling; Zhao, Yan-Fang; Xiao, He; Shan, Ya-Jun; Zhao, Zhen-Hu; Liu, Xiao-Lan; Cong, Yu-Wen; Luo, Qing-Liang

    2011-01-01

    Fission-neutron radiation damage is hard to treat due to its critical injuries to hematopoietic and gastrointestinal systems, and so far few data are available on the therapeutic measures for neutron-radiation syndrome. This study was designed to test the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in dogs which had received 2.3 Gy mixed fission-neutronirradiation with a high ratio of neutrons (~90%). Following irradiation, rhG-CSF treatment induced 100% survival versus 60% in controls. Only two of five rhG-CSF-treated dogs experienced leukopenia (white blood cells [WBC] count < 1.0 × 10(9)/L) and neutropenia (neutrophil [ANC] count < 0.5 × 10(9)/L), whereas all irradiated controls displayed a profound period of leukopenia and neutropenia. Furthermore, administration of rhG-CSF significantly delayed the onset of leukopenia and reduced the duration of leucopenia as compared with controls. In addition, individual dogs in the rhG-CSF-treated group exhibited evident differences in rhG-CSF responsiveness after neutron-irradiation. Finally, histopathological evaluation of the surviving dogs revealed that the incidence and severity of bone marrow, thymus and spleen damage decreased in rhG-CSF-treated dogs as compared with surviving controls. Thus, these results demonstrated that rhG-CSF administration enhanced recovery of myelopoiesis and survival after neutron-irradiation. PMID:21785235

  10. Deterioration of Watt and Voltage Characteristics of AlGalnP Heterostructures under Irradiation by Fast Neutrons

    NASA Astrophysics Data System (ADS)

    Gradoboev, A. V.; Orlova, K. N.

    2016-02-01

    The paper presents the results of studying characteristic deterioration of AlGaInP heterostructures with multiple quantum wells. The research was completed for light emitting diodes (emission wavelengths 623 nm and 590 nm) under fast neutron irradiation in passive mode. It has been revealed that the change in emission power and operating current under irradiation is conditioned by band gap and level of electron injection. Here, the change of current flowing mechanism is a distinctive parameter of the boundary between the first and second stages of emission power reduction caused by fast neutron irradiation of AlGaInP heterostructures (X=625 nm).

  11. Emission properties of InGaAs/GaAs heterostructures with quantum wells and dots after irradiation with neutrons

    SciTech Connect

    Baidus, N. V.; Vikhrova, O. V. Zvonkov, B. N.; Malysheva, E. I.; Trufanov, A. N.

    2015-03-15

    The effect of neutron radiation on the luminescence of InGaAs/GaAs heterostructures with quantum wells and quantum dots is studied. It is found that neutron radiation results both in the formation of defects and in the radiation-induced annealing of growth-related defects. Quantum dots are more stable to neutron radiation in comparison with quantum wells. It is shown that the layer of InGaAs/GaAs quantum dots located near the surface is less sensitive to irradiation with neutrons compared with a similar layer located in the bulk. In the first case, one can observe an increase in the photoluminescence and electroluminescence intensities after irradiation with neutrons, which is related to the effects of radiation-induced annealing. The pronounced effect of elastic strains in the InGaAs/GaAs quantum wells on the extent of quenching of the photoluminescence intensity upon irradiation with neutrons is revealed. In heterostructures with quantum wells, the effect of radiation-induced annealing manifests itself in a shift of the photoluminescence peak to longer wavelengths as a result of a decrease in elastic strains upon irradiation with neutrons. Doping of the GaAs buffer layer with silicon also reduces the value of this spectral shift.

  12. Recovery of fissile materials from plutonium residues, miscellaneous spent nuclear fuel, and uranium fissile wastes

    SciTech Connect

    Forsberg, C.W.

    1997-03-01

    A new process is proposed that converts complex feeds containing fissile materials into a chemical form that allows the use of existing technologies (such as PUREX and ion exchange) to recover the fissile materials and convert the resultant wastes to glass. Potential feed materials include (1) plutonium scrap and residue, (2) miscellaneous spent nuclear fuel, and (3) uranium fissile wastes. The initial feed materials may contain mixtures of metals, ceramics, amorphous solids, halides, and organics. 14 refs., 4 figs.

  13. Mechanical Behaviour of Cyanate Ester/epoxy Blends after Reactor Irradiation to High Neutron Fluences

    NASA Astrophysics Data System (ADS)

    Prokopec, R.; Humer, K.; Fillunger, H.; Maix, R. K.; Weber, H. W.

    2008-03-01

    The mechanical strength of conventional epoxy resins drops dramatically after irradiation to a fast neutron fluence of 1×1022 m-2 (E>0.1 MeV). Recent results demonstrated that cyanate ester/epoxy blends were not affected at this fluence level. The aim of this study is to investigate the performance potential of these blends at higher fluence levels without significant degradation of their mechanical properties. Short-beam shear as well as static tensile tests were carried out at 77 K prior to and after irradiation to fast neutron fluences of up to 4×1022 m-2 (E>0.1 MeV) in the TRIGA reactor at ambient temperature (340 K). In addition, load controlled tension-tension fatigue measurements were performed, in order to simulate the pulsed operation conditions of a tokamak. Initial results show that only a small reduction of the mechanical strength under static and dynamic load is observed at a fast neutron fluence of 2×1022 m-2 (E>0.1 MeV). After exposure to 4×1022 m-2 (E>0.1 MeV) the interlaminar shear strength of materials with a cyanate ester content of 40% or more is only reduced by 20% to 30%.

  14. Effects of thermal annealing of power BJTs, MOSFETs, and SITs following neutron and gamma irradiation

    NASA Astrophysics Data System (ADS)

    Frasca, Albert J.; Schwarze, Gene E.

    1991-01-01

    The electrical and switching characteristics of high power semiconductor switches subjected to high levels of neutron fluences and gamma doses must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect switch performance are briefly discussed. The effects of post-irradiation thermal anneals at 300 K and up to 425 K for NPN Bipolar Junction Transistors (BJTs), N-channel Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), and N-channel Static Induction Transistors (SITs) are discussed in terms of recovery of degraded electrical and switching parameters caused by either neutron or gamma irradiation. The important experimental results from these annealing tests show that BJTs have very good recovery to leakage current degradation but poor recovery to current gain degradation; MOSFETs show some recovery in gate-source threshold voltage degradation but no significant recovery in drain-source on-resistance degradation; and likewise, SITs show no significant recovery in drain-source on-resistance degradation.

  15. Investigation of laser ion acceleration inside irradiated solid targets by neutron spectroscopy

    SciTech Connect

    Youssef, A.; Kodama, R.; Tampo, M.

    2006-03-15

    Origins and acceleration directions of accelerated ions inside solid LiF, CH-LiF, and LiF-CH targets irradiated by a 450 fs, 20 J, 1053 nm laser at an intensity of 3x10{sup 18} W/cm{sup 2} have been investigated by neutron spectroscopy. The irradiated targets generate neutrons through the reaction {sup 7}Li (p,n){sup 7}Be between accelerated protons and background {sup 7}Li ions inside the target. The produced neutron spectra observed from two different observation angles 20 deg. and 120 deg. to the target rear-side normal. From the measured and calculated spectra, by three-dimensional Monte Carlo code, the maximum energy, the total number, and the slope temperature of the accelerated ions are investigated. The results indicate that ions are not only accelerated from the front surface toward the rear surface, but also from the rear surface toward the front surface with comparable maximum energy and higher number.

  16. Pathologic findings in canine brain irradiated with fractionated fast neutrons or photons

    SciTech Connect

    Zook, B.C.; Bradley, E.W.; Casarett, G.W.; Rogers, C.C.

    1980-12-01

    Thirty-seven adult male purebred beagles received total doses of 1333, 2000, 3000, or 4500 rad of fast neutrons (15 MeV av) in 4 fractions/week for 7 weeks to the entire brain. Nineteen dogs received 4000, 6000, or 9000 rad of photons (/sup 60/Co) in an identical fractionation pattern. Dogs receiving 4500, 3000, and 2000 rad of neutrons and 9000 rad of photons developed neurologic signs and died or were euthanatized when moribund followed irradiation. Cerebrospinal fluid contained excess protein and erythrocytes during and sometimes before the generally brief course. The onset of neurologic symptoms was usually followed by a moribund state in less than 48 h. The relative biological effectiveness (RBE) as measured by onset of neurologic symptoms and mortality was greater than 4.5. Gross changes included hemorrhage, edema, and malacia primarily in the white matter, especially the corona radiata, cerebellar white matter, corpus callosum, and corpus fornicis. One beagle developed a brain tumor and died 1207 days following 1333-rad neutron irradiation.

  17. Effects of thermal annealing of power BJTs, MOSFETs, and SITs following neutron and gamma irradiation

    SciTech Connect

    Frasca, A.J. ); Schwarze, G.E. )

    1991-01-10

    The electrical and switching characteristics of high power semiconductor switches subjected to high levels of neutron fluences and gamma doses must be known by the designer of the power conditioning, control and transmission subsystem of space nuclear power systems. Location and the allowable shielding mass budget will determine the level of radiation tolerance required by the switches to meet performance and reliability requirements. Neutron and gamma ray interactions with semiconductor materials and how these interactions affect switch performance are briefly discussed. The effects of post-irradiation thermal anneals at 300 K and up to 425 K for NPN Bipolar Junction Transistors (BJTs), N-channel Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), and N-channel Static Induction Transistors (SITs) are discussed in terms of recovery of degraded electrical and switching parameters caused by either neutron or gamma irradiation. The important experimental results from these annealing tests show that BJTs have very good recovery to leakage current degradation but poor recovery to current gain degradation; MOSFETs show some recovery in gate-source threshold voltage degradation but no significant recovery in drain-source on-resistance degradation; and likewise, SITs show no significant recovery in drain-source on-resistance degradation.

  18. MECHANICAL BEHAVIOUR OF CYANATE ESTER/EPOXY BLENDS AFTER REACTOR IRRADIATION TO HIGH NEUTRON FLUENCES

    SciTech Connect

    Prokopec, R.; Humer, K.; Fillunger, H.; Maix, R. K.; Weber, H. W.

    2008-03-03

    The mechanical strength of conventional epoxy resins drops dramatically after irradiation to a fast neutron fluence of 1x10{sup 22} m{sup -2} (E>0.1 MeV). Recent results demonstrated that cyanate ester/epoxy blends were not affected at this fluence level. The aim of this study is to investigate the performance potential of these blends at higher fluence levels without significant degradation of their mechanical properties. Short-beam shear as well as static tensile tests were carried out at 77 K prior to and after irradiation to fast neutron fluences of up to 4x10{sup 22} m{sup -2} (E>0.1 MeV) in the TRIGA reactor at ambient temperature (340 K). In addition, load controlled tension-tension fatigue measurements were performed, in order to simulate the pulsed operation conditions of a tokamak. Initial results show that only a small reduction of the mechanical strength under static and dynamic load is observed at a fast neutron fluence of 2x10{sup 22} m{sup -2} (E>0.1 MeV). After exposure to 4x10{sup 22} m{sup -2} (E>0.1 MeV) the interlaminar shear strength of materials with a cyanate ester content of 40% or more is only reduced by 20% to 30%.

  19. Correlation of microstructure and tensile and swelling behavior of neutron-irradiated vanadium alloys

    SciTech Connect

    Chung, H.M.; Smith, D.L.

    1991-10-01

    The microstructures of V-Ti, V-Cr-Ti, and V-Ti-Si alloys were characterized by transmission electron microscopy (TEM) after neutron irradiation in the Fast Flux Test Facility (FFTF) at 420 and 600{degrees}C to influences up to 114 dpa. Two types of irradiation-induced precipitates were identified, i.e., Ti{sub 2}O and Ti{sub 5}(Si,P){sub 3}. Blocky Ti(O,N,C) precipitates, which form by thermal processes during ingot fabrication, also were observed in all unirradiated and irradiated specimens. Irradiation-induced precipitation of spherical (<15 nm in diameter) Ti{sub 5}(Si,P){sub 3} phase was associated with superior resistance to void swelling. In specimens with negligible swelling, Ti{sub 5}(Si,P){sub 3} precipitation was significant. It seems that ductility is significantly reduced when the precipitation of Ti{sub 2}O and Ti{sub 5}(Si,P){sub 3} is pronounced. These observations indicate that initial composition; fabrication processes; actual solute compositions of Ti, O, N, C, P, and Si after fabrication; O, N, and C uptake during service; and irradiation-induced precipitation ae interrelated and are important factors to consider in developing an optimized alloy. 15 refs., 8 figs.

  20. Analytical description of true stress-true strain curves for neutron-irradiated stainless austenitic steels

    SciTech Connect

    Gussev, Maxim N; Byun, Thak Sang; Busby, Jeremy T

    2012-01-01

    This paper summarizes the results of an investigation for the deformation hardening behaviors of neutron-irradiated stainless steels in terms of true stress( ) true strain( ) curves. It is commonly accepted that the - curves are more informative for describing plastic flow, but there are few papers devoted to using the true curves for describing constitutive behaviors of materials. This study uses the true curves obtained from stainless steel samples irradiated to doses in the range of 0 55 dpa by various means: finite element calculation, optic extensomentry, and recalculation of engineering curves. It is shown that for the strain range 0 0.6 the true curves can be well described by the Swift equation: =k ( - 0)0.5. The influence of irradiation on the parameters of the Swift equation is investigated in detail. It is found that in most cases the k-parameter of this equation is not changed significantly by irradiation. Since large data scattering was observed for the 0-parameter, a modified Swift equation =k*( - 0 2/k2)0.5 was proposed and evaluated. This equation is based on the concept of zero stress, which is, in general, close to yield stress. The relationships among k, 0, and damage dose are discussed in detail, so as to more accurately describe the true curves for irradiated stainless steels.

  1. A state-of-the-art epithermal neutron irradiation facility for neutron capture therapy.

    PubMed

    Riley, K J; Binns, P J; Harling, O K

    2004-08-21

    At the Massachusetts Institute of Technology (MIT) the first fission converter-based epithermal neutron beam (FCB) has proven suitable for use in clinical trials of boron neutron capture therapy (BNCT). The modern facility provides a high intensity beam together with low levels of contamination that is ideally suited for use with future, more selective boron delivery agents. Prescriptions for normal tissue tolerance doses consist of 2 or 3 fields lasting less than 10 min each with the currently available beam intensity, that are administered with an automated beam monitoring and control system to help ensure safety of the patient and staff alike. A quality assurance program ensures proper functioning of all instrumentation and safety interlocks as well as constancy of beam output relative to routine calibrations. Beam line shutters and the medical room walls provide sufficient shielding to enable access and use of the facility without affecting other experiments or normal operation of the multipurpose research reactor at MIT. Medical expertise and a large population in the greater Boston area are situated conveniently close to the university, which operates the research reactor 24 h a day for approximately 300 days per year. The operational characteristics of the facility closely match those established for conventional radiotherapy, which together with a near optimum beam performance ensure that the FCB is capable of determining whether the radiobiological promise of NCT can be realized in routine practice. PMID:15446801

  2. Neutron yields upon irradiation of thick targets by ions with energies below 1.75 MeV/Nucleon

    NASA Astrophysics Data System (ADS)

    Gikal, K. B.; Teterev, Yu. G.; Zdorovets, M. V.; Ivanov, I. A.; Koloberdin, M. V.; Kozin, S. G.

    2016-03-01

    The yields of neutrons produced in thick LiF, Be, C, Al, Al2O3, and Cu targets irradiated by Li, C, and N ions with energies below 1.75 MeV/nucleon are measured on the DC-60 cyclotron at the Institute of Nuclear Physics, Astana Branch, Kazakhstan. The experimental angular distributions of the neutron yields from the targets are measured and an empirical equation to describe the distributions is proposed. The measured neutron yields are compared with the figures calculated by the LISE++ program. The measured and predicted neutron yields in the reactions coincide to within a factor of 2.

  3. Examining the stability of thermally fissile Th and U isotopes

    NASA Astrophysics Data System (ADS)

    Kumar, Bharat; Biswal, S. K.; Singh, S. K.; Patra, S. K.

    2015-11-01

    The properties of recently predicted thermally fissile Th and U isotopes are studied within the framework of the relativistic mean-field approach using the axially deformed basis. We calculate the ground, first intrinsic excited state for highly neutron-rich thorium and uranium isotopes. The possible modes of decay such as α decay and β decay are analyzed. We found that neutron-rich isotopes are stable against α decay, however, they are very unstable against β decay. The lifetime of these nuclei is predicted to be tens of seconds against β decay. If these nuclei are utilized before their decay time, a lot of energy can be produced with the help of multifragmentation fission. Also, these nuclei have great implications from the astrophysical point of view. In some cases, we found that the isomeric states with energy range from 2 to 3 MeV and three maxima in the potential energy surface of Th-230228 and U-234228 isotopes.

  4. Apparatus and method for quantitatively evaluating total fissile and total fertile nuclide content in samples

    DOEpatents

    Caldwell, John T.; Kunz, Walter E.; Cates, Michael R.; Franks, Larry A.

    1985-01-01

    Simultaneous photon and neutron interrogation of samples for the quantitative determination of total fissile nuclide and total fertile nuclide material present is made possible by the use of an electron accelerator. Prompt and delayed neutrons produced from resulting induced fissions are counted using a single detection system and allow the resolution of the contributions from each interrogating flux leading in turn to the quantitative determination sought. Detection limits for .sup.239 Pu are estimated to be about 3 mg using prompt fission neutrons and about 6 mg using delayed neutrons.

  5. Neutron irradiation effects on the microstructural development of tungsten and tungsten alloys

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira; Fukuda, Makoto; Yabuuchi, Kiyohiro; Nogami, Shuhei

    2016-04-01

    Data on the microstructural development of tungsten (W) and tungsten rhenium (Re) alloys were obtained after neutron irradiation at 400-800 °C in the Japan Materials Testing Reactor (JMTR), the experimental fast test reactor Joyo, and the High Flux Isotope Reactor (HFIR) for irradiation damage levels in the range of 0.09-1.54 displacement per atom (dpa). Microstructural observations showed that a small amount of Re (3-5%) in W-Re alloys is effective in suppressing void formation. In W-Re alloys with Re concentrations greater than 10%, acicular precipitates are the primary structural defects. In the HFIR-irradiated specimen, in which a large amount of Re was expected to be produced by the nuclear transmutation of W to Re because of the reactor's high thermal neutron flux, voids were not observed even in pure W. The synergistic effects of displacement damage and solid transmutation elements on microstructural development are discussed, and the microstructural development of tungsten materials utilized in fusion reactors is predicted.

  6. Investigation of the combined effect of neutron irradiation and electron beam exposure on pure tungsten

    NASA Astrophysics Data System (ADS)

    Van Renterghem, W.; Uytdenhouwen, I.

    2016-08-01

    Pure tungsten samples were neutron irradiated in the BR2 reactor of SCK·CEN to fluences of 1.47 × 1020 n/cm2 and 4.74 × 1020 n/cm2 at 300 °C under Helium atmosphere and exposed to the electron beam of the Judith 1 installation The effect of these treatments on the defect structure was studied with transmission electron microscopy. In the irradiated samples the defect structure in the bulk is compared to the structure at the surface. The neutron irradiation created a large amount of a/2‹111› type dislocation loops forming dislocation rafts. The loop density increased from 8.5 × 1021/m³ to 9 × 1022/m³ with increasing dose, while the loop size decreased from 5.2 nm to 3.5 nm. The electron beam exposure induced significant annealing of the defects and almost all of the dislocation loops were removed. The number of line dislocations in that area increased as a result of the thermal stresses from the thermal shock.

  7. Tritium release from neutron irradiated beryllium: Kinetics, long-time annealing and effect or crack formation

    SciTech Connect

    Scaffidi-Argentina, F.; Werle, H.

    1995-09-01

    Since beryllium is considered as one of the best neutron multiplier materials in the blanket of the next generation fusion reactors, several studies have been started to evaluate its behaviour under irradiation during both operating and accidental conditions. Based on safety considerations, tritium produced in beryllium during neutron irradiation represents one important issue, therefore it is necessary to investigate tritium transport processes by using a comprehensive mathematical model and comparing its predictions with well characterized experimental tests. Because of the difficulties in extrapolating the short-time tritium release tests to a longer time scale, also long-time annealing experiments with beryllium samples from the SIBELIUS irradiation. have been carried out at the Forschungszentrum Karlsruhe. Samples were annealed up to 12 months at temperatures up to 650{degrees}C. The inventory after annealing was determined by heating the samples up to 1050{degrees}C with a He+0.1 vo1% H{sub 2} purge gas. Furthermore, in order to investigate the likely effects of cracks formation eventually causing a faster tritium release from beryllium, the behaviour of samples irradiated at low temperature (40-50{degrees}C) but up to very high fast neutron fluences (0.8-3.9{center_dot}10{sup 22} cm{sup -2}, E{sub n}{ge}1 MeV) in the BR2 reactor has been investigated. Tritium was released by heating the beryllium samples up to 1050{degrees}C and purging them with He+0.1 vo1% H{sub 2}. Tritium release from high-irradiated beryllium samples showed a much faster kinetics than from the low-irradiated ones, probably because of crack formation caused by thermal stresses in the brittle material and/or by helium bubbles migration. The obtained experimental data have been compared with predictions of the code ANFIBE with the goal to better understand the physical mechanisms governing tritium behaviour in beryllium and to assess the prediction capabilities of the code.

  8. Fissile and fertile nuclear material measurements using a new differential die-away self-interrogation technique

    SciTech Connect

    Menlove, Howard O; Tobin, Stephen J; Menlove, S H

    2008-01-01

    This paper presents a new technique for the measurement of fissile and fertile nuclear materials in spent fuel and plutonium laden materials such as mixed oxide (MOX) fuel. The technique, called differential die-away self-interrogation, is similar to traditional differential die-away analysis, but it does not require a pulsed neutron generator or pulsed beam accelerator, and it can measure the fertile mass in addition to the fissile mass. The new method uses the spontaneous fission neutrons from {sup 244}Cm in spent fuel and {sup 240}Pu effective neutrons in MOX as the 'pulsed' neutron source with an average of {approx} 2.7 neutrons per pulse. The time correlated neutrons from the spontaneous fission and the subsequent induced fissions are analyzed as a function of time to determine the spontaneous fission rate, the induced fast-neutron fissions, and the induced thermal-neutron fissions. The fissile mass is determined from the induced thermal-neutron fissions that are produced by reflected thermal neutrons that originated from the spontaneous fission reaction. The sensitivity of the fissile mass measurement is enhanced by the use of two measurements, with and without a cadmium liner between the sample and the hydrogenous moderator. The fertile mass is determined from the multiplicity analysis of the neutrons detected soon after the initial triggering neutron is detected. The method obtains good sensitivity by the optimal design of two different neutron die-away regions: a short die-away for the neutron detector region and a longer die-away for the sample interrogation region.

  9. Microdosimetric measurements of radiation quality variations in homogeneous phantoms irradiated by fast neutron beams

    SciTech Connect

    Beach, J.L.; Milavickas, L.R.

    1982-01-01

    The Dual Radiation Action Theory of Kellerer and Rossi (DRA), along with presently available microdosimetric techniques, is applied to the detrmination of radiation quality variation within tissue equivalent phantoms irradiated by collimated fast neutron beams. The neutron beams investigated were produced by the bombardment of 22.5 and 16 MeV d+ on beryllium and by the T(d,n)/sup 4/He reaction (15-MeV neutrons). Microdosimetric spectra were obtained at points of varying depth and lateral distance from the central axis within a tissue equivalent phantom, including points within the penumbra. From the microdosimetric spectra the parameter RQ, a first approximation to RBE derived from DRA theory, is calculated for each point. All RQ values are calculated for the same level of effect. For these three different beams the results show that the RQ values for the total radiation spectrum of neutron and gamma radiation remain fairly constant with depth and with lateral distance from the beam axis at 2 and 10 cm depths. The largest central axis variation in RQ is 8% for the d(16)+Be beam. The largest variation between a penumbra and an on-axis RQ value is 4% at 2 cm depth in the d(22.5)+Be beam. The results for the d(22.5)+Be beam disagree with previously reported radiobiological results while the 15 MeV beam results are in good agreement.

  10. Post-irradiation examination of the Spallation Neutron Source target module

    NASA Astrophysics Data System (ADS)

    McClintock, D. A.; Ferguson, P. D.; Mansur, L. K.

    2010-03-01

    The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is an accelerator-based pulsed neutron source that produces high-energy spallation neutrons by bombarding liquid mercury flowing through a stainless steel target vessel. During operation the proton beam and spallation neutrons produce radiation damage in the AISI 316L austenitic stainless steel target vessel and water-cooled shroud. The beam pulses also cause rapid heating of the liquid mercury, which may produce cavitation erosion damage on the inner surface of the target vessel. The cavitation erosion rate is thought to be highly sensitive to beam power and predicted to be the primary life-limiting factor of the target module. Though cavitation erosion and radiation damage to the target vessel are expected to dictate its lifetime, the effects of radiation damage and cavitation erosion to target vessels in liquid metal spallation systems are not well known. Therefore preparations are being undertaken to perform post-irradiation examination (PIE) of the liquid mercury target vessel and water-cooled shroud after end-of-life occurs. An overview of the planned PIE for the SNS target vessel is presented here, including proposed techniques for specimen acquisition and subsequent material properties characterization.

  11. Thermal, structural and mechanical properties of neutron irradiated Bayfol nuclear track detector

    NASA Astrophysics Data System (ADS)

    Nouh, S. A.; Mohamed, Amal; Bahammam, S.

    2009-07-01

    Samples from sheets of the polymeric material Bayfol have been exposed to neutrons of incident energy in the range 0.8-19.2 MeV. The resultant effect of neutron irradiation on the thermal properties of Bayfol has been investigated using thermo-gravimetric analysis. The onset temperature of decomposition and activation energy of thermal decomposition were calculated. The variation of transition temperatures with neutron energy has been determined using differential thermal analysis. The results indicate Bayfol thermograms characterized by the appearance of an endothermic peak due to melting. Melting temperature was found to be dependent on the neutron energy. Structural property studies using infrared spectroscopy were performed and results indicated that scission takes place at the carbonate site with the formation of a hydroxyl group. Mechanical properties were studied and it is shown that, at the fluence range 0-4.4 MeV, the standard chains and a great number of chain ends weaken and the material may become softer.

  12. Degradation of Nylon 6,6 Fire-Suppression Casing from Plutonium Glove Boxes Under Alpha and Neutron Irradiation

    DOE PAGESBeta

    Millsap, Donald W.; Cournoyer, Michael E.; Landsberger, Sheldon; Tesmer, Joseph R.; Wang, Matthew Y.

    2015-04-23

    Nylon 6,6 tensile specimens, conforming to the casing for self-contained fire extinguisher systems, have been irradiated using both an accelerator He++ ion beam and a 5-Ci PuBe neutron source to model the radiation damage these systems would likely incur over a lifetime of operation within glove boxes. Following irradiation, these samples were mechanically tested using standard practices as described in ASTM D638. The results of the He++ study indicate that the tensile strength of the nylon specimens undergoes some slight (<10%) degradation while other properties of the samples, such as elongation and tangent modulus, appear to fluctuate with increasing dosemore » levels. The He++-irradiated specimens also have a noticeable level of discoloration corresponding to increasing levels of dose. The neutron-irradiated samples show a higher degree of mechanical degradation than the He++-irradiated samples.« less

  13. Degradation of Nylon 6,6 Fire-Suppression Casing from Plutonium Glove Boxes Under Alpha and Neutron Irradiation

    SciTech Connect

    Millsap, Donald W.; Cournoyer, Michael E.; Landsberger, Sheldon; Tesmer, Joseph R.; Wang, Matthew Y.

    2015-04-23

    Nylon 6,6 tensile specimens, conforming to the casing for self-contained fire extinguisher systems, have been irradiated using both an accelerator He++ ion beam and a 5-Ci PuBe neutron source to model the radiation damage these systems would likely incur over a lifetime of operation within glove boxes. Following irradiation, these samples were mechanically tested using standard practices as described in ASTM D638. The results of the He++ study indicate that the tensile strength of the nylon specimens undergoes some slight (<10%) degradation while other properties of the samples, such as elongation and tangent modulus, appear to fluctuate with increasing dose levels. The He++-irradiated specimens also have a noticeable level of discoloration corresponding to increasing levels of dose. The neutron-irradiated samples show a higher degree of mechanical degradation than the He++-irradiated samples.

  14. Effects of neutron irradiation on microstructures and hardness of stainless steel weld-overlay cladding of nuclear reactor pressure vessels

    NASA Astrophysics Data System (ADS)

    Takeuchi, T.; Kakubo, Y.; Matsukawa, Y.; Nozawa, Y.; Toyama, T.; Nagai, Y.; Nishiyama, Y.; Katsuyama, J.; Yamaguchi, Y.; Onizawa, K.

    2014-06-01

    The microstructures and the hardness of stainless steel weld overlay cladding of reactor pressure vessels subjected to neutron irradiation at a dose of 7.2 × 1019 n cm-2 (E > 1 MeV) and a flux of 1.1 × 1013 n cm-2 s-1 at 290 °C were investigated by atom probe tomography and by a nanoindentation technique. To isolate the effects of the neutron irradiation, we compared the results of the measurements of the neutron-irradiated samples with those from a sample aged at 300 °C for a duration equivalent to that of the irradiation. The Cr concentration fluctuation was enhanced in the δ-ferrite phase of the irradiated sample. In addition, enhancement of the concentration fluctuation of Si, which was not observed in the aged sample, was observed. The hardening in the δ-ferrite phase occurred due to both irradiation and aging; however, the hardening of the irradiated sample was more than that expected from the Cr concentration fluctuation, which suggested that the Si concentration fluctuation and irradiation-induced defects were possible origins of the additional hardening.

  15. The comparison of microstructure and nanocluster evolution in proton and neutron irradiated Fe-9%Cr ODS steel to 3 dpa at 500 °C

    NASA Astrophysics Data System (ADS)

    Swenson, M. J.; Wharry, J. P.

    2015-12-01

    A model Fe-9%Cr oxide dispersion strengthened (ODS) steel was irradiated with protons or neutrons to a dose of 3 displacements per atom (dpa) at a temperature of 500 °C, enabling a direct comparison of ion to neutron irradiation effects at otherwise fixed irradiation conditions. The irradiated microstructures were characterized using transmission electron microscopy and atom probe tomography including cluster analysis. Both proton and neutron irradiations produced a comparable void and dislocation loop microstructure. However, the irradiation response of the Ti-Y-O oxide nanoclusters varied. Oxides remained stable under proton irradiation, but exhibited dissolution and an increase in Y:Ti composition ratio under neutron irradiation. Both proton and neutron irradiation also induced varying extents of Si, Ni, and Mn clustering at existing oxide nanoclusters. Protons are able to reproduce the void and loop microstructure of neutron irradiation carried out to the same dose and temperature. However, since nanocluster evolution is controlled by both diffusion and ballistic impacts, protons are rendered unable to reproduce the nanocluster evolution of neutron irradiation at the same dose and temperature.

  16. Extraction of protactinium-233 and separation from thermal neutron-irradiated thorium-232 using crown ethers

    SciTech Connect

    Jalhoom, Moayyed G.; Mohammed, Dawood A.; Khalaf, Jumah S.

    2008-07-01

    A new method was developed for the extraction and separation of {sup 233}Pa from thermal neutron-irradiated {sup 232}Th. Solutions of Pa{sup 233} were prepared in LiCI-HCl solutions from which appreciable extraction was obtained using dibenzo-18-crown-6 in 1,2-dichloroethane. The effects of cavity size, substitutions on the crown ring, type of the organic solvent, and temperature on extraction are discussed. Very high separation factors were obtained for the pairs {sup 233}Pa/{sup 232}Th (>105), {sup 233}Pa/{sup 233}U (> 1000), and {sup 232}U/{sup 232}Th (>60). (authors)

  17. Neutron and X-ray irradiation of silicon based Mach-Zehnder modulators

    NASA Astrophysics Data System (ADS)

    El Nasr-Storey, S. S.; Détraz, S.; Olanterä, L.; Sigaud, C.; Soós, C.; Pezzullo, G.; Troska, J.; Vasey, F.; Zeiler, Marcel

    2015-03-01

    We report on our recent investigation into the potential for using silicon-based Mach-Zehnder modulators in the harshest radiation environments of the High-Luminosity LHC. The effect of ionizing and non-ionizing radiation on the performance of the devices have been investigated using the 20 MeV neutron beam line at the Cyclotron Resource Centre in Louvain-La-Neuve and the X-ray irradiation facility in the CERN PH department. The devices were exposed to a total fluence and ionizing dose of 1.2×1015 n cm-2 and 1.3 MGy respectively.

  18. Dislocation sweeping of defects in neutron- and electron-irradiated niobium

    SciTech Connect

    Loomis, B.A.; Otero, M.P.

    1983-10-01

    The glide of dislocations in a (441)-oriented Nb single crystal irradiated at 325 K with 5.5 x 10/sup 21/ neutrons/m/sup 2/ (E > 0.1 MeV) is shown for increasing time of tensile elongation (2 x 10/sup -4/ mm/s) in the High Voltage Electron Microscope at Argonne National Laboratory. The dimensions of the tensile specimen in the guage length were approximately 2 mm x 0.5 mm x 0.0001 mm. An electron energy of 900 keV was used during the simultaneous deformation and TEM observation.

  19. Thermal annealing of stabilization products from recoil bromine-82 atoms in neutron-irradiated ammonium perbromate

    SciTech Connect

    Isupov, V.K.; Gavrilov, V.V.

    1987-11-01

    A study has been made on the thermal annealing of stabilization products from recoil bromine-82 atoms in neutron-irradiated ammonium perbromate. Paper and ion-exchange chromatography show that the oxidation of /sup 82/Br/sup -/ to /sup 82/BrO/sub 3//sup -/ in that case occurs only to a small extent, in contrast to alkali-metal perbromates. The effect is ascribed to metastable radiolysis products from the ammonium group. The pyrolysis of ammonium perbromate has also been examined.

  20. Neutron beam irradiation study of workload dependence of SER in a microprocessor

    SciTech Connect

    Michalak, Sarah E; Graves, Todd L; Hong, Ted; Ackaret, Jerry; Sonny, Rao; Subhasish, Mitra; Pia, Sanda

    2009-01-01

    It is known that workloads are an important factor in soft error rates (SER), but it is proving difficult to find differentiating workloads for microprocessors. We have performed neutron beam irradiation studies of a commercial microprocessor under a wide variety of workload conditions from idle, performing no operations, to very busy workloads resembling real HPC, graphics, and business applications. There is evidence that the mean times to first indication of failure, MTFIF defined in Section II, may be different for some of the applications.

  1. Microstructural examination of fast-neutron irradiated Li/sub 2/O

    SciTech Connect

    Liu, Y.Y.; Mattas, R.F.; Smith, D.L.; Porter, D.L.

    1984-10-01

    Scanning Electron Microscopy examinations of fast-neutron irradiated Li/sub 2/O at 608 to 625/sup 0/C to 1 and 3 at. % /sup 6/Li burnups have been performed. Of particular interests are the helium bubble morphologies and their relationships to the reported tritium/helium retentions and swelling in Li/sub 2/O. Possible defect trapping of tritium is suggested, along with discussions of two other phenomena (microcracking, swelling) on the performance of an Li/sub 2/O fusion reactor blanket.

  2. Combined use of FLUKA and MCNP-4A for the Monte Carlo simulation of the dosimetry of 10B neutron capture enhancement of fast neutron irradiations.

    PubMed

    Pignol, J P; Cuendet, P; Brassart, N; Fares, G; Colomb, F; M'Bake Diop, C; Sabattier, R; Hachem, A; Prevot, G

    1998-06-01

    Boron neutron capture enhancement (BNCE) of the fast neutron irradiations use thermal neutrons produced in depth of the tissues to generate neutron capture reactions on 10B within tumor cells. The dose enhancement is correlated to the 10B concentration and to thermal neutron flux measured in the depth of the tissues, and in this paper we demonstrate the feasibility of Monte Carlo simulation to study the dosimetry of BNCE. The charged particle FLUKA code has been used to calculate the primary neutron yield from the beryllium target, while MCNP-4A has been used for the transport of these neutrons in the geometry of the Biomedical Cyclotron of Nice. The fast neutron spectrum and dose deposition, the thermal flux and thermal neutron spectrum in depth of a Plexiglas phantom has been calculated. The thermal neutron flux has been compared with experimental results determined with calibrated thermoluminescent dosimeters (TLD-600 and TLD-700, respectively, doped with 6Li or 7Li). The theoretical results were in good agreement with the experimental results: the thermal neutron flux was calculated at 10.3 X 10(6) n/cm2 s1 and measured at 9.42 X 10(6) n/cm2 s1 at 4 cm depth of the phantom and with a 10 cm X 10 cm irradiation field. For fast neutron dose deposition the calculated and experimental curves have the same slope but different shape: only the experimental curve shows a maximum at 2.27 cm depth corresponding to the build-up. The difference is due to the Monte Carlo simulation which does not follow the secondary particles. Finally, a dose enhancement of, respectively, 4.6% and 10.4% are found for 10 cm X 10 cm or 20 cm X 20 cm fields, provided that 100 micrograms/g of 10B is loaded in the tissues. It is anticipated that this calculation method may be used to improve BNCE of fast neutron irradiations through collimation modifications. PMID:9650176

  3. Hardness of Carburized Surfaces in 316LN Stainless Steel after Low Temperature Neutron Irradiation

    SciTech Connect

    Byun, TS

    2005-01-31

    A proprietary surface carburization treatment is being considered to minimize possible cavitation pitting of the inner surfaces of the stainless steel target vessel of the SNS. The treatment gives a large supersaturation of carbon in the surface layers and causes substantial hardening of the surface. To answer the question of whether such a hardened layer will remain hard and stable during neutron irradiation, specimens of the candidate materials were irradiated in the High Flux Isotope Reactor (HFIR) to an atomic displacement level of 1 dpa. Considerable radiation hardening occurred in annealed 316LN stainless steel and 20% cold rolled 316LN stainless steel, and lesser radiation hardening in Kolsterised layers on these materials. These observations coupled with optical microscopy examinations indicate that the carbon-supersaturated layers did not suffer radiation-induced decomposition and softening.

  4. Effect of neutron-irradiation on the microstructure of a Fe-12at.%Cr alloy

    NASA Astrophysics Data System (ADS)

    Kuksenko, V.; Pareige, C.; Genevois, C.; Cuvilly, F.; Roussel, M.; Pareige, P.

    2011-08-01

    A nanoscale description of the microstructure in a Fe-12at%Cr model alloy of low purity which has been neutron irradiated at 300°C up to 0.6 dpa, has been performed owing to atom probe tomography (APT). APT investigations have shown that the impurities are also involved in the microstructural evolution under irradiation. Two different populations of clusters have been observed: Cr-enriched and NiSiPCr-enriched clusters. As expected with a process of enhanced precipitation, Cr-enriched clusters are homogeneously distributed inside grains and certainly not correlated to dislocation loops. The NiSiPCr-enriched clusters, which are probably radiation induced segregations, are independent of the Cr-enriched clusters and are also homogeneously distributed. A quantitative description of these objects is presented in this paper and results are compared to SANS data of the literature obtained for the same model alloy.

  5. Rat mammary cell survival following irradiation with 14. 3-MeV neutrons

    SciTech Connect

    Mahler, P.A.; Gould, M.N.; DeLuca, P.M. Jr.; Pearson, D.W.; Clifton, K.H.

    1982-08-01

    The survival of rat mammary gland cells irradiated in situ with either single or split doses of 14.3-MeV neutrons was determined by an in vivo transplantation assay. The single-dose data are best fit to the multitarget single-hit model by the parameters D/sub o/ = 97 cGy and n = 0.6 while the split-dose data are best fit by the parameters D/sub o/ = 100 cGy and n = 1.2.Analysis of the combined data sets suggests that the two survival curves are not identical. Comparison of these data with previously published results following irradiation with 250-kVp X rays is reported.

  6. Rat mammary-cell survival following irradiation with 14. 3-MeV neutrons

    SciTech Connect

    Mahler, P.A.; Gould, M.N.; DeLuca, P.M. Jr.; Pearson, D.W.; Clifton, K.H.

    1982-01-01

    The survival of rat mammary gland cells irradiated in situ with either single or split doses of 14.3-MeV neutrons was determined by an in vivo transplantation assay. The single-dose data are best fit to the multitarget single-hit model by the parameters D/sub 0/ = 97 cGy and n = 0.6 while the split-dose data are best fit by the parameters D/sub 0/ = 100 cGy and n = 1.2. Analysis of the combined data sets suggests that the two survival curves are not identical. Comparison of these data with previously published results following irradiation with 250-kVp x-rays is reported.

  7. 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.

  8. National Low-Temperature Neutron Irradiation Facility (NLTNIF). The status of development

    SciTech Connect

    Coltman, R.R. Jr.; Kerchner, H.R.; Klabunde, C.E.; Young, F.W. Jr.

    1985-12-01

    In May 1983, the Department of Energy authorized the establishment of a National Low-Temperature Neutron Irradiation Facility (NLTNIF) at ORNL's Bulk Shielding Reactor (BSR). The NLTNIF, which will be available for qualified experiments at no cost to users, will provide a combination of high radiation intensities and special environmental and testing conditions that have not been previously available in the US. Since the DOE authorization, work has proceeded on the design and construction of the new facility without interruption. This report describes the present status of the development of the NLTNIF and the anticipated schedule for completion and performance testing. There is a table of the major specifications and capabilities and a schematic layout of the irradiation cryostate for design and dimensioning of test and experiment assemblies.

  9. Micromechanisms of Twin Nucleation in TiAl: Effects of Neutron Irradiation

    SciTech Connect

    Hishinuma, A.; Yoo, M.H.

    1999-01-28

    The so-called radiation-induced ductility (RID) reported in neutron-irradiated 47at%Al alloys is attributed to the formation of effective twin embryos in the presence of interstitial-type Frank loops in {gamma}-TiAl and the subsequent nucleation and growth of microtwins during post-irradiation tensile deformation. The stability of large faulted Frank loops is explained in terms of the repulsive interaction between Shockley and Frank partials. Interaction of only six ordinary slip dislocations with a Frank loop can facilitate a pole mechanism for twin formation to work. The relative ease of heterogeneous twin nucleation is the reason for the RID and the lack of changes in yield strength and work hardening.

  10. Influence of nickel and beryllium content on swelling behavior of copper irradiated with fast neutrons

    SciTech Connect

    Singh, B.N.; Garner, F.A.; Edwards, D.J.; Evans, J.H.

    1996-10-01

    In the 1970`s, the effects of nickel content on the evolution of dislocation microstructures and the formation and growth of voids in Cu-Ni alloys were studied using 1 MeV electrons in a high voltage electron microscope. The swelling rate was found to decrease rapidly with increasing nickel content. The decrease in the swelling rate was associated with a decreasing void growth rate with increasing nickel content at irradiation temperatures up to 450{degrees}C. At 500{degrees}C, both void size and swelling rate were found to peak at 1 and 2% Ni, respectively, and then to decrease rapidly with increasing nickel content. However, recent work has demonstrated that the swelling behavior of Cu-5%Ni irradiated with fission neutrons is very similar for that of pure copper. The present experiments were designed to investigate this apparent discrepancy.

  11. The effects of neutron irradiation on fracture toughness of austenitic stainless steels.

    SciTech Connect

    Chopra, O. K.; Gruber, E. E.; Shack, W. J.

    1999-05-21

    Austenitic stainless steels are used extensively as structural alloys in reactor pressure vessel internal components because of their superior fracture toughness properties. However, exposure to high levels of neutron irradiation for extended periods leads to significant reduction in the fracture resistance of these steels. This paper presents results of fracture toughness J-R curve tests on four heats of Type 304 stainless steel that were irradiated to fluence levels of {approx}0.3 and 0.9 x 10{sup 21} n cm{sup {minus}2} (E >1 MeV) at {approx}288 C in a helium environment in the Halden heavy water boiling reactor. The tests were performed on 1/4-T compact tension specimens in air at 288 C; crack extensions were determined by both DC potential and elastic unloading compliance techniques.

  12. The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells.

    NASA Technical Reports Server (NTRS)

    Ghosh, S.; Sargent, G. A.

    1972-01-01

    Study regions of lattice disorder produced in lithium-doped float-zone melted n/p-type silicon solar cells by irradiation with monoenergetic neutrons at doses between 10 to the 10th and 10 to the 13th per cu cm. The defect regions were revealed by chemically etching the surface of the solar cells and by observing carbon replicas in an electron microscope. It was found that the defect density increased with increasing irradiation dose and increased lithium content, whereas the average defect diameter was found to decrease. From thermal annealing experiments it was found that in the lithium-doped material the defect structure was stable at temperatures between 300 and 1200 K. This was found to be in contrast to the undoped material where at the lowest doses considerable annealing was observed to occur. These results are discussed in terms of the theoretical predictions and models of defect clusters proposed by Gossick (1959) and Crawford and Cleland (1959).

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n th +10 B → 7 Li + (γ)+ α were studied in nuclear track emulsions enriched in boron. Nuclear track emulsions were also irradiated with 86Kr+17 and 124Xe+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.

  14. A TCT and annealing study on Magnetic Czochralski silicon detectors irradiated with neutrons and 24 GeV/ c protons

    NASA Astrophysics Data System (ADS)

    Pacifico, Nicola; Creanza, Donato; de Palma, Mauro; Manna, Norman; Kramberger, Gregor; Moll, Michael

    2010-01-01

    Silicon diodes (pad detectors) were irradiated with 24 GeV/ c protons at the CERN PS IRRAD1 facility and with neutrons at the TRIGA reactor in Ljubljana (Slovenia). The diodes were realized on Magnetic Czochralski (MCz) grown silicon, of both n- and p-type. After irradiation, an annealing study with CV measurements was performed on 24 GeV/ c proton irradiated detectors, looking for hints of type inversion after irradiation and during annealing. Other pad detectors were studied using the TCT (transient current technique), to gather information about the field profile in the detector bulk and thus about the effective space charge distribution within it.

  15. Mechanical- and physical-property changes of neutron-irradiated chemical-vapor-deposited silicon carbide

    SciTech Connect

    Osborne, M.C.; Steiner, D.; Hay, J.C.; Snead, L.L.

    1999-09-01

    Indentation and density measurements have revealed important changes in the mechanical and physical properties of silicon carbide (SiC) due to neutron irradiation. Specifically, the changes in the elastic modulus, hardness, fracture toughness, and density with irradiation have provided an understanding of the expected performance of SiC and SiC composites in nuclear applications. After the accumulated damage has saturated, these mechanical properties were affected primarily by the irradiation temperature. Chemical-vapor-deposited (CVD) SiC was irradiated above the saturation fluence and yielded volumetric swelling of 2.6% and 1.3% for irradiation temperatures of 100--150 C and 500--550 C, respectively. At the same respective temperatures, the elastic modulus decreased from an unirradiated value of 503 GPa to {approximately} 420 and 450 GPa. Conversely, the hardness increased from 36 GPa for the unirradiated at 100--150 C and 500--550 C, respectively. Interestingly, these two independent properties approached almost-constant levels after exposure to a fluence of 0.5 {times} 10{sup 25} n/m{sup 2}, E > 0.1 MeV. Indentation fracture toughness measurements, which were within the range of values in the literature for conventional fracture toughness procedures for SiC, increased from {approximately} 2.8 MPa{center_dot}m{sup 1/2} for the unirradiated samples to 3.7 and 4.2 MPa{center_dot}m{sup 1/2} for the samples that were irradiated at 100--150 C and 500--550 C, respectively.

  16. Effects of neutron irradiation on deformation behavior of nickel-base fastener alloys

    SciTech Connect

    Bajaj, R.; Mills, W.J.; Kammenzind, B.F.; Burke, M.G.

    1999-07-01

    This paper presents the effects of neutron irradiation on the fracture behavior and deformation microstructure of high-strength nickel-base alloy fastener materials, Alloy X-750 and Alloy 625. Alloy X-750 in the HTH condition, and Alloy 625 in the direct aged condition were irradiated to a fluence of 2.4x10{sup 20} n/cm{sup 2} at 264 C in the Advanced Test Reactor. Deformation structures at low strains were examined. It was previously shown that Alloy X-750 undergoes hardening, a significant degradation in ductility and an increase in intergranular fracture. In contrast, Alloy 625 had shown softening with a concomitant increase in ductility and transgranular failure after irradiation. The deformation microstructures of the two alloys were also different. Alloy X-750 deformed by a planar slip mechanism with fine microcracks forming at the intersections of slip bands with grain boundaries. Alloy 625 showed much more homogeneous deformation with fine, closely spaced slip bands and an absence of microcracks. The mechanism(s) of irradiation assisted stress corrosion cracking (IASCC) are discussed.

  17. Flux pinning in neutron irradiated YBa sub 2 Cu sub 3 O sub 7 minus x

    SciTech Connect

    Lessure, H.A.; Simizu, S.; Baumert, B.A.; Sankar, S.G.; McHenry, M.E. ); Maley, M.P.; Cost, J.R.; Willis, J.O. )

    1991-03-01

    This paper reports on identical polycrystalline samples of YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} irradiated with fast neutrons (E {gt} 0.1 MeV) in eight steps between 0 and 2.1 {times} 10{sup 18} n/cm{sup 2}. Notable irradiation effects include a T{sub c} depression of nearly 2 K at the highest fluence and large improvement in the critical current density for fields from 0-9 T and temperatures between 4-80 K. Critical currents approaching 2 {times} 10{sup 7} A/cm{sup 2} are observed for optimally irradiated materials at 5K (in zero field) while at 77 K, J{sub c} (O kOe) approaches 5 {times} 10{sup 5} A/cm{sup 2}. Irradiation is seen to take a nearly equilibrium magnetization curve at 77 K and broaden it to a significantly hysteretic curve. A substantial shift in the effective pinning potential as a function of current density is inferred from magnetic relaxation measurements at H = 1T. This is the first such measurement in which systematically increased activation energies for flux creep (as a function of current density) are noted.

  18. On He bubbles in neutron irradiated SYLRAMIC type SiC fibers

    SciTech Connect

    Gelles, David S; Youngblood, Gerald E

    2006-03-01

    SylramicTM type SiC fibers, which contain at least 2.3 wt% B, were examined by TEM following neutron irradiation to dose levels of ~7 dpa in HFIR at 800°C and to ~1 dpa in ATR at 1090°C. At these radiation damage dose levels, transmutation of the boron-10 component effectively “dopes” the Sylramic type fibers with up to 10,000 appm helium. Following irradiation at 800°C, bubble development was too fine to resolve even by high resolution TEM. However, following irradiation at 1090°C helium bubble development was resolvable, but complex. A fine dispersion of 1-nm bubbles was observed within the SiC grains and a coarse, non-uniform distribution of irregular 25-nm bubbles was observed on grain boundaries. In addition, some unusual arrays of planar 2.5-nm thick bubbles were observed in the SiC grains and equiaxed bubbles were observed in the boride precipitate particles contained within the fiber microstructure. Not unexpectedly, helium retention and bubble formation in β-SiC depends on details of the polycrystalline microstructure as well as the irradiation conditions.

  19. Fissile Nuclei Rotation Effect in {sup 235}U(n,{gamma}f) Process

    SciTech Connect

    Danilyan, Gevorg; Krakhotin, Vyacheslav; Kuznetsov, Valery; Novitsky, Vadim; Pavlov, Valery; Shatalov, Pavel; Granz, Peter; Mezei, Ferenz; Russina, Margarita; Wilpert, Thomas; Klenke, Jens

    2009-01-28

    A small shift of an angular distribution of prompt {gamma}-rays relative to the fission axis of {sup 236}U* {sup 235}U(n,{gamma}f) process is presented. This effect has been observed in the experiment at BER-II reactor of BENSC/HMI (Berlin). The sign of the shift depends on the direction of the incident neutron beam polarization. This phenomena can be explained by the rotation of fissile nucleus {sup 236}U*, like the effect that has been observed recently at ILL in ternary fission of {sup 235}U by cold polarized neutrons. The main surprise of this result is the detection of scission gamma-rays radiated by a fissile nucleus during the time interval of the order of 10{sup -21} s before or after the moment of the neck rupture. Detailed measurements of trigger {gamma}-rays energy dependence are in progress at the neutron beam 'MEPHISTO' of FRM-II reactor (Garching)

  20. Development for fissile assay in recycled fuel using lead slowing down spectrometer

    SciTech Connect

    Lee, Yong Deok; Je Park, C.; Kim, Ho-Dong; Song, Kee Chan

    2013-07-01

    A future nuclear energy system is under development to turn spent fuels produced by PWRs into fuels for a SFR (Sodium Fast Reactor) through the pyrochemical process. The knowledge of the isotopic fissile content of the new fuel is very important for fuel safety. A lead slowing down spectrometer (LSDS) is under development to analyze the fissile material content (Pu{sup 239}, Pu{sup 241} and U{sup 235}) of the fuel. The LSDS requires a neutron source, the neutrons will be slowed down through their passage in a lead medium and will finally enter the fuel and will induce fission reactions that will be analysed and the isotopic content of the fuel will be then determined. The issue is that the spent fuel emits intense gamma rays and neutrons by spontaneous fission. The threshold fission detector screens the prompt fast fission neutrons and as a result the LSDS is not influenced by the high level radiation background. The energy resolution of LSDS is good in the range 0.1 eV to 1 keV. It is also the range in which the fission reaction is the most discriminating for the considered fissile isotopes. An electron accelerator has been chosen to produce neutrons with an adequate target through (e{sup -},γ)(γ,n) reactions.

  1. Complete suppression of reverse annealing of neutron radiation damage during active gamma irradiation in MCZ Si detectors

    NASA Astrophysics Data System (ADS)

    Li, Z.; Verbitskaya, E.; Chen, W.; Eremin, V.; Gul, R.; Härkönen, J.; Hoeferkamp, M.; Kierstead, J.; Metcalfe, J.; Seidel, S.

    2013-01-01

    For the development of radiation-hard Si detectors for the SiD BeamCal (Si Detector Beam Calorimeter) program for International Linear Collider (ILC), n-type Magnetic Czochralski Si detectors have been irradiated first by fast neutrons to fluences of 1.5×1014 and 3×1014 neq/cm2, and then by gamma up to 500 Mrad. The motivation of this mixed radiation project is to test the radiation hardness of MCZ detectors that may utilize the gamma/electron radiation to compensate the negative effects caused by neutron irradiation, all of which exists in the ILC radiation environment. By using the positive space charge created by gamma radiation in MCZ Si detectors, one can cancel the negative space charge created by neutrons, thus reducing the overall net space charge density and therefore the full depletion voltage of the detector. It has been found that gamma radiation has suppressed the room temperature reverse annealing in neutron-irradiated detectors during the 5.5 month of time needed to reach a radiation dose of 500 Mrad. The room temperature annealing (RTA) was verified in control samples (irradiated to the same neutron fluences, but going through this 5.5 month RTA without gamma radiation). This suppression is in agreement with our previous predictions, since negative space charge generated during the reverse annealing was suppressed by positive space charge induced by gamma radiation. The effect is that regardless of the received neutron fluence the reverse annealing is totally suppressed by the same dose of gamma rays (500 Mrad). It has been found that the full depletion voltage for the two detectors irradiated to two different neutron fluences stays the same before and after gamma radiation. Meanwhile, for the control samples also irradiated to two different neutron fluences, full depletion voltages have gone up during this period. The increase in full depletion voltage in the control samples corresponds to the generation of negative space charge, and this

  2. Effects of neutron irradiation and hydrogen on ductile-brittle transition temperatures of V-Cr-Ti alloys*1

    NASA Astrophysics Data System (ADS)

    Loomis, B. A.; Chung, H. M.; Nowicki, L. J.; Smith, D. L.

    1994-09-01

    The effects of neutron irradiation and hydrogen on the ductile-brittle transition temperatures (DBTTs) of unalloyed vanadium and V-Cr-Ti alloys were determined from Charpy-impact tests on {1}/{3} ASTM-standard-size specimens and from impact tests on 3-mm diameter discs. The tests were conducted on specimens containing < 30 appm hydrogen and 600-1200 appm hydrogen and on specimens after neutron irradiation to 28-46 atom displacements per atom at 420, 520, and 600°C. The DBTTs were minimum (< -220°C) for V-(1-5)Ti alloys and for V-4Cr- 4Ti alloy with < 30 appm hydrogen. The effect of 600-1200 appm hydrogen in the specimens was to raise the DBTTs by 60-100°C. The DBTTs were minimum (< -200°C) for V-(3-5)Ti and V-4Cr-4Ti alloys after neutron irradiation.

  3. Specific features in the change of electrical resistivity of carbon nanocomposites based on nanodiamonds under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Gordeev, S. K.; Konopleva, R. F.; Chekanov, V. A.; Korchagina, S. B.; Belyaev, S. P.; Golosovskii, I. V.; Denisov, I. A.; Belobrov, P. I.

    2013-07-01

    The physical properties of bulk composite materials consisting of nanodiamond, pyrolytic carbon, and nanopores were investigated. Samples were irradiated in a channel of the reactor by fast neutrons ( E > 0.5MeV) in ampoules with helium and in an aqueous medium. The dependences of the electrical transport properties of materials with different compositions on the dose of irradiation with fast neutrons were studied. A nonmonotonic change in the electrical resistivity with an increase in the neutron fluence was revealed. Possible explanations were offered for the observed dependence of the electrical resistivity on the neutron fluence, in particular, those related to the physical processes occurring in surface states of the three-phase system of the nanocomposite.

  4. Neutron irradiation effects on domain wall mobility and reversibility in lead zirconate titanate thin films

    SciTech Connect

    Graham, Joseph T.; Brennecka, Geoff L.; Ihlefeld, Jon F.; Ferreira, Paulo; Small, Leo; Duquette, David; Apblett, Christopher; Landsberger, Sheldon

    2013-03-28

    The effects of neutron-induced damage on the ferroelectric properties of thin film lead zirconate titanate (PZT) were investigated. Two sets of PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} films of varying initial quality were irradiated in a research nuclear reactor up to a maximum 1 MeV equivalent neutron fluence of (5.16 {+-} 0.03) Multiplication-Sign 10{sup 15} cm{sup -2}. Changes in domain wall mobility and reversibility were characterized by polarization-electric field measurements, Rayleigh analysis, and analysis of first order reversal curves (FORC). With increasing fluence, extrinsic contributions to the small-signal permittivity diminished. Additionally, redistribution of irreversible hysterons towards higher coercive fields was observed accompanied by the formation of a secondary hysteron peak following exposure to high fluence levels. The changes are attributed to the radiation-induced formation of defect dipoles and other charged defects, which serve as effective domain wall pinning sites. Differences in damage accumulation rates with initial film quality were observed between the film sets suggesting a dominance of pre-irradiation microstructure on changes in macroscopic switching behavior.

  5. Static and Dynamic Performance of Newly Developed ITER Relevant Insulation Systems after Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Prokopec, R.; Humer, K.; Fillunger, H.; Maix, R. K.; Weber, H. W.

    2006-03-01

    Fiber reinforced plastics will be used as insulation systems for the superconducting magnet coils of ITER. The fast neutron and gamma radiation environment present at the magnet location will lead to serious material degradation, particularly of the insulation. For this reason, advanced radiation-hard resin systems are of special interest. In this study various R-glass fiber / Kapton reinforced DGEBA epoxy and cyanate ester composites fabricated by the vacuum pressure impregnation method were investigated. All systems were irradiated at ambient temperature (340 K) in the TRIGA reactor (Vienna) to a fast neutron fluence of 1×1022 m-2 (E>0.1 MeV). Short-beam shear and static tensile tests were carried out at 77 K prior to and after irradiation. In addition, tension-tension fatigue measurements were used in order to assess the mechanical performance of the insulation systems under the pulsed operation conditions of ITER. For the cyanate ester based system the influence of interleaving Kapton layers on the static and dynamic material behavior was investigated as well.

  6. A microstructural study of phosphorus segregation and intergranular fracture in neutron irradiated submerged-arc welds

    SciTech Connect

    Bischler, P.J.E.; Wild, R.K.

    1996-12-31

    Accelerated irradiation experiments have been carried out on submerged-arc welds to obtain validation of trend curves built up from surveillance results. This was done by withdrawing surveillance specimens and re-irradiating them in higher flux positions. One batch, from weld HS, showed a significantly higher increase in the Charpy {Delta}T{sub 40J} value than that for weld LS at a similar dose. Work done to explain this difference is described in this paper. Selected Charpy specimens were examined using a shielded scanning electron microscope to determine the fracture modes present. Regions of mixed cleavage, micro-void coalescence (MVC) and intergranular failure (IGF) were found on HS weld specimens fractured in the transition region. The IFG was confined to certain regions within each weld bead. Significantly less IGF was found on LS weld specimens. Sub-fracture surface matchstick specimens were removed from embrittled regions and fractured within a scanning Auger microscope. IGF occurred in these specimens, and phosphorus was found to be the main grain boundary segregant. The levels of phosphorus increased with increasing neutron dose. No other embrittling element was consistently found at any significant level, but carbon was also found on grain boundary surfaces in some cases. The grain boundary coverage of phosphorus was determined for each weld at several neutron dose levels.

  7. Static and Dynamic Performance of Newly Developed ITER Relevant Insulation Systems after Neutron Irradiation

    SciTech Connect

    Prokopec, R.; Humer, K.; Fillunger, H.; Maix, R. K.; Weber, H. W.

    2006-03-31

    Fiber reinforced plastics will be used as insulation systems for the superconducting magnet coils of ITER. The fast neutron and gamma radiation environment present at the magnet location will lead to serious material degradation, particularly of the insulation. For this reason, advanced radiation-hard resin systems are of special interest. In this study various R-glass fiber / Kapton reinforced DGEBA epoxy and cyanate ester composites fabricated by the vacuum pressure impregnation method were investigated. All systems were irradiated at ambient temperature (340 K) in the TRIGA reactor (Vienna) to a fast neutron fluence of 1x1022 m-2 (E>0.1 MeV). Short-beam shear and static tensile tests were carried out at 77 K prior to and after irradiation. In addition, tension-tension fatigue measurements were used in order to assess the mechanical performance of the insulation systems under the pulsed operation conditions of ITER. For the cyanate ester based system the influence of interleaving Kapton layers on the static and dynamic material behavior was investigated as well.

  8. Spectrum and density of neutron flux in the irradiation beam line no. 3 of the IBR-2 reactor

    NASA Astrophysics Data System (ADS)

    Shabalin, E. P.; Verkhoglyadov, A. E.; Bulavin, M. V.; Rogov, A. D.; Kulagin, E. N.; Kulikov, S. A.

    2015-03-01

    Methodology and results of measuring the differential density of the neutron flux in irradiation beam line no. 3 of the IBR-2 reactor using neutron activation analysis (NAA) are presented in the paper. The results are compared to the calculation performed on the basis of the 3D MCNP model. The data that are obtained are required to determine the integrated radiation dose of the studied samples at various distances from the reactor.

  9. Effects of neutron irradiation on pinning force scaling in state-of-the-art Nb3Sn wires

    NASA Astrophysics Data System (ADS)

    Baumgartner, T.; Eisterer, M.; Weber, H. W.; Flükiger, R.; Scheuerlein, C.; Bottura, L.

    2014-01-01

    We present an extensive irradiation study involving five state-of-the-art Nb3Sn wires which were subjected to sequential neutron irradiation up to a fast neutron fluence of 1.6 × 1022 m-2 (E > 0.1 MeV). The volume pinning force of short wire samples was assessed in the temperature range from 4.2 to 15 K in applied fields of up to 7 T by means of SQUID magnetometry in the unirradiated state and after each irradiation step. Pinning force scaling computations revealed that the exponents in the pinning force function differ significantly from those expected for pure grain boundary pinning, and that fast neutron irradiation causes a substantial change in the functional dependence of the volume pinning force. A model is presented, which describes the pinning force function of irradiated wires using a two-component ansatz involving a point-pinning contribution stemming from radiation induced pinning centers. The dependence of this point-pinning contribution on fast neutron fluence appears to be a universal function for all examined wire types.

  10. Segmented Ge detector rejection of internal beta activity produced by neutron irradiation

    NASA Technical Reports Server (NTRS)

    Varnell, L. S.; Callas, J. L.; Mahoney, W. A.; Pehl, R. H.; Landis, D. A.

    1991-01-01

    Future Ge spectrometers flown in space to observe cosmic gamma-ray sources will incorporate segmented detectors to reduce the background from radioactivity produced by energetic particle reactions. To demonstrate the effectiveness of a segmented Ge detector in rejecting background events due to the beta decay of internal radioactivity, a laboratory experiment has been carried out in which radioactivity was produced in the detector by neutron irradiation. A Cf-252 source of neutrons was used to produce, by neutron capture on Ge-74 (36.5 percent of natural Ge) in the detector itself, Ge-75 (t sub 1/2 = 82.78 min), which decays by beta emission with a maximum electron kinetic energy of 1188 keV. By requiring that an ionizing event deposit energy in two or more of the five segments of the detector, each about 1-cm thick, the beta particles, which have a range of about 1-mm, are rejected, while most external gamma rays incident on the detector are counted. Analysis of this experiment indicates that over 85 percent of the beta events from the decay of Ge-75 are rejected, which is in good agreement with Monte Carlo calculations.

  11. Structural characterization of nanoscale intermetallic precipitates in highly neutron irradiated reactor pressure vessel steels

    SciTech Connect

    Sprouster, D. J.; Sinsheimer, J.; Dooryhee, E.; Ghose, S.; Wells, P.; Stan, T.; Almirall, N.; Odette, G. R.; Ecker, L. E.

    2015-10-21

    Here, massive, thick-walled pressure vessels are permanent nuclear reactor structures that are exposed to a damaging flux of neutrons from the adjacent core. The neutrons cause embrittlement of the vessel steel that increases with dose (fluence or service time), as manifested by an increasing temperature transition from ductile-to-brittle fracture. Moreover, extending reactor life requires demonstrating that large safety margins against brittle fracture are maintained at the higher neutron fluence associated with 60 to 80 years of service. Here synchrotron-based x-ray diffraction and small angle x-ray scattering measurements are used to characterize a new class of highly embrittling nm-scale Mn-Ni-Si precipitates that develop in the irradiated steels at high fluence. Furthermore, these precipitates can lead to severe embrittlement that is not accounted for in current regulatory models. Application of the complementarity techniques has, for the very first time, successfully characterized the crystal structures of the nanoprecipitates, while also yielding self-consistent compositions, volume fractions and size distributions.

  12. Structural characterization of nanoscale intermetallic precipitates in highly neutron irradiated reactor pressure vessel steels

    DOE PAGESBeta

    Sprouster, D. J.; Sinsheimer, J.; Dooryhee, E.; Ghose, S.; Wells, P.; Stan, T.; Almirall, N.; Odette, G. R.; Ecker, L. E.

    2015-10-21

    Here, massive, thick-walled pressure vessels are permanent nuclear reactor structures that are exposed to a damaging flux of neutrons from the adjacent core. The neutrons cause embrittlement of the vessel steel that increases with dose (fluence or service time), as manifested by an increasing temperature transition from ductile-to-brittle fracture. Moreover, extending reactor life requires demonstrating that large safety margins against brittle fracture are maintained at the higher neutron fluence associated with 60 to 80 years of service. Here synchrotron-based x-ray diffraction and small angle x-ray scattering measurements are used to characterize a new class of highly embrittling nm-scale Mn-Ni-Si precipitatesmore » that develop in the irradiated steels at high fluence. Furthermore, these precipitates can lead to severe embrittlement that is not accounted for in current regulatory models. Application of the complementarity techniques has, for the very first time, successfully characterized the crystal structures of the nanoprecipitates, while also yielding self-consistent compositions, volume fractions and size distributions.« less

  13. Contribution To Degradation Study, Behavior Of Unsaturated Polyester Resin Under Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Abellache, D.; Lounis, A.; Taïbi, K.

    2010-01-01

    Applications of unsaturated polyester thermosetting resins are numerous in construction sector, in transport, electric spare parts manufactures, consumer goods, and anticorrosive materials. This survey reports the effect of thermosetting polymer degradation (unsaturated polyester): degradation by neutrons irradiation. In order to evaluate the deterioration of our material, some comparative characterizations have been done between standard samples and damaged ones. Scanning electron microscopy (SEM), ultrasonic scanning, hardness test (Shore D) are the techniques which have been used. The exposure to a neutrons flux is carried out in the column of the nuclear research reactor of Draria (Algiers-Algeria). The energetic profile of the incidental fluxes is constituted of fast neutrons (ΦR = 3.1012n.cm-2.s-1, E = 2 Mev) of thermal neutrons (ΦTH = 1013n.cm-2.s-1; E = 0.025 ev) and epithermal neutrons (Φepi = 7.1011 n.cm-2.s-1; E>4,9 ev). The received dose flow is 0,4 Kgy. We notice only a few scientific investigations can be found in this field. In comparison with the standard sample (no exposed) it is shown that the damage degree is an increasing process with the exposure. Concerning the description of irradiation effects on polymers, we can advance that several reactions are in competition : reticulation, chain break, and oxidation by radical mechanism. In our case the incidental particle of high energy fast neutrons whose energy is greater or equal to 2 Mev, is braked by the target with a nuclear shock during which the incidental particle transmits a part of its energy to an atom. If the energy transfer is sufficient, the nuclear shock permits to drive out an atom of its site the latter will return positioning interstitially, the energy that we used oversteps probably the energy threshold (displacement energy). This fast neutrons collision with target cores proceeds to an indirect ionization by the preliminary creation of excited secondary species that will

  14. Contribution To Degradation Study, Behavior Of Unsaturated Polyester Resin Under Neutron Irradiation

    SciTech Connect

    Abellache, D.; Lounis, A.; Taiebi, K.

    2010-01-05

    Applications of unsaturated polyester thermosetting resins are numerous in construction sector, in transport, electric spare parts manufactures, consumer goods, and anticorrosive materials. This survey reports the effect of thermosetting polymer degradation (unsaturated polyester): degradation by neutrons irradiation. In order to evaluate the deterioration of our material, some comparative characterizations have been done between standard samples and damaged ones. Scanning electron microscopy (SEM), ultrasonic scanning, hardness test (Shore D) are the techniques which have been used. The exposure to a neutrons flux is carried out in the column of the nuclear research reactor of Draria (Algiers-Algeria). The energetic profile of the incidental fluxes is constituted of fast neutrons (PHI{sub R} = 3.10{sup 12} n.cm{sup -2}.s{sup -1}, E = 2 Mev) of thermal neutrons (PHI{sub TH} = 10{sup 13} n.cm{sup -2}.s{sup -1}; E = 0.025 ev) and epithermal neutrons (PHI{sub epi} = 7.10{sup 11} n.cm{sup -2}.s{sup -1}; E>4,9 ev). The received dose flow is 0,4 Kgy. We notice only a few scientific investigations can be found in this field. In comparison with the standard sample (no exposed) it is shown that the damage degree is an increasing process with the exposure. Concerning the description of irradiation effects on polymers, we can advance that several reactions are in competition: reticulation, chain break, and oxidation by radical mechanism. In our case the incidental particle of high energy fast neutrons whose energy is greater or equal to 2 Mev, is braked by the target with a nuclear shock during which the incidental particle transmits a part of its energy to an atom. If the energy transfer is sufficient, the nuclear shock permits to drive out an atom of its site the latter will return positioning interstitially, the energy that we used oversteps probably the energy threshold (displacement energy). This fast neutrons collision with target cores proceeds to an indirect

  15. Investigation of Effects of Neutron Irradiation on Tantalum Alloys for Radioisotope Power System Applications

    SciTech Connect

    Barklay, Chadwick D.; Kramer, Daniel P.; Talnagi, Joseph

    2007-01-30

    Tantalum alloys have been used by the U.S. Department of Energy as structural alloys for space nuclear power systems such as Radioisotopic Thermoelectric Generators (RTG) since the 1960s. Tantalum alloys are attractive for high temperature structural applications due to their high melting point, excellent formability, good thermal conductivity, good ductility (even at low temperatures), corrosion resistance, and weldability. A number of tantalum alloys have been developed over the years to increase high-temperature strength (Ta-10%W) and to reduce creep strain (T-111). These tantalum alloys have demonstrated sufficient high-temperature toughness to survive the increasing high pressures of the RTG's operating environment resulting from the alpha decay of the 238-plutonium dioxide fuel. However, 238-plutonium is also a powerful neutron source. Therefore, the RTG operating environment produces large amounts of 3-helium and neutron displacement damage over the 30 year life of the RTG. The literature to date shows that there has been very little work focused on the mechanical properties of irradiated tantalum and tantalum alloys and none at the fluence levels associated with a RTG operating environment. The minimum, reactor related, work that has been reported shows that these alloys tend to follow trends seen in the behavior of other BCC alloys under irradiation. An understanding of these mechanisms is important for the confident extrapolation of mechanical-property trends to the higher doses and gas levels corresponding to actual service lifetimes. When comparing the radiation effects between samples of Ta-10%W and T-111 (Ta-8%W-2%Hf) subjected to identical neutron fluences and environmental conditions at temperatures <0.3Tm ({approx}700 deg. C), evidence suggests the possibility that T-111 will exhibit higher levels of internal damage accumulation and degradation of mechanical properties compared to Ta-10%W.

  16. Investigation of Effects of Neutron Irradiation on Tantalum Alloys for Radioisotope Power System Applications

    NASA Astrophysics Data System (ADS)

    Barklay, Chadwick D.; Kramer, Daniel P.; Talnagi, Joseph

    2007-01-01

    Tantalum alloys have been used by the U.S. Department of Energy as structural alloys for space nuclear power systems such as Radioisotopic Thermoelectric Generators (RTG) since the 1960s. Tantalum alloys are attractive for high temperature structural applications due to their high melting point, excellent formability, good thermal conductivity, good ductility (even at low temperatures), corrosion resistance, and weldability. A number of tantalum alloys have been developed over the years to increase high-temperature strength (Ta-10%W) and to reduce creep strain (T-111). These tantalum alloys have demonstrated sufficient high-temperature toughness to survive the increasing high pressures of the RTG's operating environment resulting from the alpha decay of the 238-plutonium dioxide fuel. However, 238-plutonium is also a powerful neutron source. Therefore, the RTG operating environment produces large amounts of 3-helium and neutron displacement damage over the 30 year life of the RTG. The literature to date shows that there has been very little work focused on the mechanical properties of irradiated tantalum and tantalum alloys and none at the fluence levels associated with a RTG operating environment. The minimum, reactor related, work that has been reported shows that these alloys tend to follow trends seen in the behavior of other BCC alloys under irradiation. An understanding of these mechanisms is important for the confident extrapolation of mechanical-property trends to the higher doses and gas levels corresponding to actual service lifetimes. When comparing the radiation effects between samples of Ta-10%W and T-111 (Ta-8%W-2%Hf) subjected to identical neutron fluences and environmental conditions at temperatures <0.3Tm (˜700 °C), evidence suggests the possibility that T-111 will exhibit higher levels of internal damage accumulation and degradation of mechanical properties compared to Ta-10%W.

  17. Low cycle fatigue properties of reduced activation ferritic/martensitic steels after high-dose neutron irradiation

    NASA Astrophysics Data System (ADS)

    Gaganidze, E.; Petersen, C.; Aktaa, J.; Povstyanko, A.; Prokhorov, V.; Diegele, E.; Lässer, R.

    2011-08-01

    This paper focuses on the low cycle fatigue (LCF) behaviour of reduced activation ferritic/martensitic steels irradiated to a displacement damage dose of up to 70 dpa at 330-337 °C in the BOR 60 reactor within the ARBOR 2 irradiation programme. The influence of neutron irradiation on the fatigue behaviour was determined for the as-received EUROFER97, pre-irradiation heat-treated EUROFER97 HT and F82H-mod steels. Strain-controlled push-pull loading was performed using miniaturized cylindrical specimens at a constant temperature of 330 °C with total strain ranges between 0.8% and 1.1%. Comparison of the LCF behaviour of irradiated and reference unirradiated specimens was performed for both the adequate total and inelastic strains. Neutron irradiation-induced hardening may have various effects on the fatigue behaviour of the steels. The reduction of inelastic strain in the irradiated state compared with the reference unirradiated state at common total strain amplitudes may increase fatigue lifetime. The increase in the stress at the adequate inelastic strain, by contrast, may accelerate fatigue damage accumulation. Depending on which of the two effects mentioned dominates, neutron irradiation may either extend or reduce the fatigue lifetime compared with the reference unirradiated state. The results obtained for EUROFER97 and EUROFER97 HT confirm these considerations. Most of the irradiated specimens show fatigue lifetimes comparable to those of the reference unirradiated state at adequate inelastic strains. Some irradiated specimens, however, show lifetime reduction or increase in comparison with the reference state at adequate inelastic strains.

  18. Investigation of X-ray spectral response of D-T fusion produced neutron irradiated PIPS detectors for plasma X-ray diagnostics

    NASA Astrophysics Data System (ADS)

    Vigneshwara Raja, P.; Narasimha Murty, N. V. L.; Rao, C. V. S.; Abhangi, Mitul

    2015-10-01

    This paper describes the fusion-produced neutron irradiation induced changes in the X-ray spectral response of commercially available Passivated Implanted Planar Silicon (PIPS) detectors using the accelerator based D-T generator. After 14.1 MeV neutron irradiation up to a fluence of 3.6× 1010 n/cm2, the energy resolution (i.e. FWHM) of the detectors at room temperature is found to degrade by about 3.8 times that of the pre-irradiated value. From the X-ray spectral characteristics, it has been observed that the room temperature spectral response of PIPS detectors is too poor even at low neutron fluences. Irradiation is also carried out with Am-Be neutron source for studying the effect of scattered neutrons from the reactor walls on the detector performance. Comparative studies of the damage caused by 14.1 MeV neutrons and Am-Be source produced neutrons at the same neutron fluence are carried out by analyzing the irradiated detector characteristics. The degradation in the energy resolution of the detectors is attributed to the radiation induced changes in the detector leakage current. No considerable changes in the full depletion voltage and the effective doping concentration up to the neutron fluence of 3.6× 1010 n/cm2, are observed from the measured C-V characteristics. Partial recovery of the neutron irradiated detector characteristics is discussed.

  19. High-dose neutron irradiation of Hi-Nicalon Type S silicon carbide composites. Part 2: Mechanical and physical properties

    NASA Astrophysics Data System (ADS)

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wally; Snead, Lance L.

    2015-07-01

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573-1073 K. The material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating the irradiation temperature, but only to a limited extent. The observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.

  20. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    SciTech Connect

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wallace D; Snead, Lance Lewis

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating the irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.

  1. Fission meter and neutron detection using poisson distribution comparison

    SciTech Connect

    Rowland, Mark S; Snyderman, Neal J

    2014-11-18

    A neutron detector system and method for discriminating fissile material from non-fissile material wherein a digital data acquisition unit collects data at high rate, and in real-time processes large volumes of data directly into information that a first responder can use to discriminate materials. The system comprises counting neutrons from the unknown source and detecting excess grouped neutrons to identify fission in the unknown source. Comparison of the observed neutron count distribution with a Poisson distribution is performed to distinguish fissile material from non-fissile material.

  2. Nuclear archaeology: Verifying declarations of fissile-material production

    SciTech Connect

    Fetter, S. )

    1993-01-01

    Controlling the production of fissile material is an essential element of nonproliferation policy. Similarly, accounting for the past production of fissile material should be an important component of nuclear disarmament. This paper describes two promising techniques that make use of physical evidence at reactors and enrichment facilities to verify the past production of plutonium and highly enriched uranium. In the first technique, the concentrations of long-lived radionuclides in permanent components of the reactor core are used to estimate the neutron fluence in various regions of the reactor, and thereby verify declarations of plutonium production in the reactor. In the second technique, the ratio of the concentration of U-235 to that of U-234 in the tails is used to determine whether a given container of tails was used in the production of low- enriched uranium, which is suitable for reactor fuel, or highly enriched uranium, which can be used in nuclear weapons. Both techniques belong to the new field of [open quotes]nuclear archaeology,[close quotes] in which the authors attempt to document past nuclear weapons activities and thereby lay a firm foundation for verifiable nuclear disarmament. 11 refs., 1 fig., 3 tabs.

  3. Dimensional isotropy of 6H and 3C SiC under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki; Terrani, Kurt; Specht, Eliot D.

    2016-04-01

    This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.02-20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstrated equivalent swelling behavior. Moreover the 6H-SiC expanded isotropically. The magnitude of the swelling followed a ∼0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ∼7.8% volume expansion in SiC was observed prior to amorphization. Above ∼0.9 × 1025 n/m2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm3. The as-amorphized density was the same at the 2 × 1025 and 2 × 1026 n/m2 (E > 0.1 MeV) dose levels.

  4. Dimensional isotropy of 6H and 3C SiC under neutron irradiation

    DOE PAGESBeta

    Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki; Terrani, Kurt A.; Specht, Eliot D.

    2016-01-16

    This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.02–20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstrated equivalent swelling behavior.more » Moreover the 6H–SiC expanded isotropically. The magnitude of the swelling followed a ~0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ~7.8% volume expansion in SiC was observed prior to amorphization. Above ~0.9 × 1025 n/m2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm3. As a result, the as-amorphized density was the same at the 2 × 1025 and 2 × 1026 n/m2 (E > 0.1 MeV) dose levels.« less

  5. Why neutron guides may end up breaking down? Some results on the macroscopic behaviour of alkali-borosilicate glass support plates under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Boffy, R.; Kreuz, M.; Beaucour, J.; Köster, U.; Bermejo, F. J.

    2015-09-01

    In this paper we report on a first part of a study on the mechanisms leading to brittle fracture in neutron guides made of glass as structural element. Such devices are widely used to deliver thermal and cold neutron beams to experimental lines in most large neutron research facilities. We present results on macroscopic properties of samples of guide glass substrates which are subjected to neutron irradiation at relatively large fluences. The results show a striking dependence of some of the macroscopic properties such as density, shape or surface curvature upon the specific chemical composition of a given glass. The relevance of the present findings for the installation of either replacement guides at the existing facilities or for the deployment of instruments for ongoing projects such as the European Spallation Source is briefly discussed.

  6. Response of dynamically compacted tungsten to high fluence neutron irradiation at 423?600$deg;C in FFTF

    NASA Astrophysics Data System (ADS)

    Megusar, J.; Garner, F. A.

    1998-10-01

    When pure tungsten produced by dynamic compaction at 95.3% theoretical density was irradiated in FFTF at temperatures of 423-600°C and neutron doses as high as 14.4 × 10 22 n cm -2 ( E > 0.1 MeV), it densified 2-3% and became very brittle. The brittle behavior resulted in failure at grain surfaces and appears not to be related to neutron-induced transmutation or segregation of transmutants. Based on density change measurements, it can be concluded that significant cavity formation did not occur at these high neutron exposures.

  7. Ion, X-Ray, UV And Neutron Microbeam Systems For Cell Irradiation

    SciTech Connect

    Bigelow, A. W.; Randers-Pehrson, G.; Garty, G.; Geard, C. R.; Xu, Y.; Harken, A. D.; Johnson, G. W.; Brenner, D. J.

    2011-06-01

    The array of microbeam cell-irradiation systems, available to users at the Radiological Research Accelerator Facility (RARAF), Center for Radiological Research, Columbia University, is expanding. The HVE 5MV Singletron particle accelerator at the facility provides particles to two focused ion microbeam lines: the sub-micron microbeam II and the permanent magnetic microbeam (PMM). Both the electrostatic quadrupole lenses on the microbeam II system and the magnetic quadrupole lenses on the PMM system are arranged as compound lenses consisting of two quadrupole triplets with 'Russian' symmetry. Also, the RARAF accelerator is a source for a proton-induced x-ray microbeam (undergoing testing) and is projected to supply protons to a neutron microbeam based on the {sup 7}Li(p,n){sup 7}Be nuclear reaction (under development). Leveraging from the multiphoton microscope technology integrated within the microbeam II endstation, a UV microspot irradiator - based on multiphoton excitation - is available for facility users. Highlights from radiation-biology demonstrations on single living mammalian cells are included in this review of microbeam systems for cell irradiation at RARAF.

  8. Deformation localization and dislocation channel dynamics in neutron-irradiated austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Gussev, Maxim N.; Field, Kevin G.; Busby, Jeremy T.

    2015-05-01

    The dynamics of deformation localization and dislocation channel formation were investigated in situ in a neutron-irradiated AISI 304 austenitic stainless steel and a model 304-based austenitic alloy by combining several analytical techniques including optic microscopy and laser confocal microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy (TEM). Channel formation was observed at ∼70% of the polycrystalline yield stress of the irradiated materials (σ0.2). It was shown that triple junction points do not always serve as a source of dislocation channels; at stress levels below the σ0.2, channels often formed near the middle of the grain boundary. For a single grain, the role of elastic stiffness value (Young's modulus) in channel formation was analyzed; it was shown that in the irradiated 304 steels the initial channels appeared in "soft" grains with a high Schmid factor located near "stiff" grains with high elastic stiffness. The spatial organization of channels in a single grain was analyzed; it was shown that secondary channels operating in the same slip plane as primary channels often appeared at the middle or at one-third of the way between primary channels. The twinning nature of dislocation channels was analyzed for grains of different orientation using TEM. In the AISI 304 steel, channels in grains oriented close to <0 0 1>||TA (tensile axis) and <1 0 1>||TA were twin free and grain with <1 1 1>||TA and grains oriented close to a Schmid factor maximum contained deformation twins.

  9. Positron annihilation study of neutron irradiated model alloys and of a reactor pressure vessel steel

    NASA Astrophysics Data System (ADS)

    Lambrecht, M.; Almazouzi, A.

    2009-03-01

    The hardening and embrittlement of reactor pressure vessel steels are of great concern in the actual nuclear power plant life assessment. This embrittlement is caused by irradiation-induced damage, and positron annihilation spectroscopy has been shown to be a suitable method for analysing most of these defects. In this paper, this technique (both positron annihilation lifetime spectroscopy and coincidence Doppler broadening) has been used to investigate neutron irradiated model alloys, with increasing chemical complexity and a reactor pressure vessel steel. It is found that the clustering of copper takes place at the very early stages of irradiation using coincidence Doppler broadening, when this element is present in the alloy. On the other hand, considerations based on positron annihilation spectroscopy analyses suggest that the main objects causing hardening are most probably self-interstitial clusters decorated with manganese in Cu-free alloys. In low-Cu reactor pressure vessel steels and in (Fe, Mn, Ni, Cu) alloys, the main effect is still due to Cu-rich precipitates at low doses, but the role of manganese-related features becomes pre-dominant at high doses.

  10. Fracture properties of a neutron-irradiated stainless steel submerged arc weld cladding overlay

    SciTech Connect

    Corwin, W.R.; Berggren, R.G.; Nanstad, R.K.

    1984-01-01

    The ability of stainless steel cladding to increase the resistance of an operating nuclear reactor pressure vessel to extension of surface flaws depends greatly on the properties of the irradiated cladding. Therefore, weld overlay cladding irradiated at temperatures and fluences relevant to power reactor operation was examined. The cladding was applied to a pressure vessel steel plate by the submerged arc, single-wire, oscillating-electrode method. Three layers of cladding provided a thickness adequate for fabrication of test specimens. The first layer was type 309, and the upper two layers were type 308 stainless steel. The type 309 was diluted considerably by excessive melting of the base plate. Specimens were taken from near the base plate-cladding interface and also from the upper layers. Charpy V-notch and tensile specimens were irradiated at 288/sup 0/C to a fluence of 2 x 10/sup 23/ neutrons/m/sup 2/ (>1 MeV). 10 refs., 16 figs., 4 tabs.

  11. Fissile material holdup measurement systems: an historical review of hardware and software

    SciTech Connect

    Chapman, Jeffrey Allen; Smith, Steven E; Rowe, Nathan C

    2015-01-01

    The measurement of fissile material holdup is accomplished by passively measuring the energy-dependent photon flux and/or passive neutron flux emitted from the fissile material deposited within an engineered process system. Both measurement modalities--photon and neutron--require the implementation of portable, battery-operated systems that are transported, by hand, from one measurement location to another. Because of this portability requirement, gamma-ray spectrometers are typically limited to inorganic scintillators, coupled to photomultiplier tubes, a small multi-channel analyzer, and a handheld computer for data logging. For neutron detection, polyethylene-moderated, cadmium-back-shielded He-3 thermal neutron detectors are used, coupled to nuclear electronics for supplying high voltage to the detector, and amplifying the signal chain to the scaler for counting. Holdup measurement methods, including the concept of Generalized Geometry Holdup (GGH), are well presented by T. Douglas Reilly in LA-UR-07-5149 and P. Russo in LA-14206, yet both publications leave much of the evolutionary hardware and software to the imagination of the reader. This paper presents an historical review of systems that have been developed and implemented since the mid-1980s for the nondestructive assay of fissile material, in situ. Specifications for the next-generation holdup measurements systems are conjectured.

  12. Implementation of the Fissile Mass Flow Monitor Source Verification and Confirmation

    SciTech Connect

    Uckan, Taner; March-Leuba, Jose A; Powell, Danny H; Nelson, Dennis; Radev, Radoslav

    2007-12-01

    This report presents the verification procedure for neutron sources installed in U.S. Department of Energy equipment used to measure fissile material flow. The Fissile Mass Flow Monitor (FMFM) equipment determines the {sup 235}U fissile mass flow of UF{sub 6} gas streams by using {sup 252}Cf neutron sources for fission activation of the UF{sub 6} gas and by measuring the fission products in the flow. The {sup 252}Cf sources in each FMFM are typically replaced every 2 to 3 years due to their relatively short half-life ({approx} 2.65 years). During installation of the new FMFM sources, the source identity and neutronic characteristics provided by the manufacturer are verified with the following equipment: (1) a remote-control video television (RCTV) camera monitoring system is used to confirm the source identity, and (2) a neutron detection system (NDS) is used for source-strength confirmation. Use of the RCTV and NDS permits remote monitoring of the source replacement process and eliminates unnecessary radiation exposure. The RCTV, NDS, and the confirmation process are described in detail in this report.

  13. Evaluation of neutron flux parameters in irradiation sites of research reactor using the Westcott-formalism for the k0 neutron activation analysis method

    NASA Astrophysics Data System (ADS)

    Kasban, H.; Hamid, Ashraf

    2015-12-01

    Instrumental Neutron Activation Analysis using k0 (k0-INAA) method has been used to determine a number of elements in sediment samples collected from El-Manzala Lake in Egypt. k0-INAA according to Westcott's formalism has been implemented using the complete irradiation kit of the fast pneumatic rabbit and some selected manually loaded irradiation sites for short and long irradiation at Egypt Second Research Reactor (ETRR-2). Zr-Au and Co sets as neutron flux monitors are used to determine the neutron flux parameters (f and α) in each irradiation sites. Two reference materials IAEA Soil-7 samples have been inserted and implemented for data validation and an internal monostandard multi monitor used (k0 based IM-NAA). It was given a good agreement between the experimental analyzed values and that obtained of the certified values. The major and trace elements in the sediment samples have been evaluated with the use of Co as an internal and Au as an external monostandard comparators. The concentrations of the elements (Cr, Mn and Zn) in the sediment samples of the present work are discussed regarding to those obtained from other sites.

  14. Neutron and X-ray diffraction analysis of the effect of irradiation dose and temperature on microstructure of irradiated HT-9 steel

    NASA Astrophysics Data System (ADS)

    Mosbrucker, P. L.; Brown, D. W.; Anderoglu, O.; Balogh, L.; Maloy, S. A.; Sisneros, T. A.; Almer, J.; Tulk, E. F.; Morgenroth, W.; Dippel, A. C.

    2013-11-01

    Material harvested from several positions within a nuclear fuel duct (the ACO-3 duct) used in a 6-year irradiation of a fuel assembly in the Fast Flux Test Reactor Facility (FFTF) was examined using neutron and high-energy X-ray diffraction. Samples with a wide range of irradiation dose and irradiation temperature history, reaching doses of up to 147 dpa and temperatures of up to 777 K, were examined. The response of various microstructural characteristics such as the weight fraction of M23C6 carbides, the dislocation density and character, and the crystallographic texture were determined using whole profile analysis of the diffraction data and related to the macroscopic mechanical behavior. For instance, the dislocation density was observed to be intimately linked with observed flow strength of the irradiated materials, following the Taylor law. In general, at the high doses studied in this work, the irradiation temperature is the predominant controlling factor of the dislocation density and, thus, the flow strength of the irradiated material. The results, representing some of the first diffraction work done on samples exposed to such a high received dose, demonstrate how non-destructive and stand-off diffraction techniques can be used to characterize irradiation induced microstructure and at least estimate mechanical properties in irradiated materials without exposing workers to radiation hazards.

  15. The recovery of irradiation damage for Zircaloy-2 and Zircaloy-4 following low dose neutron irradiation at nominally 358 °C

    NASA Astrophysics Data System (ADS)

    Cockeram, B. V.; Leonard, K. J.; Byun, T. S.; Snead, L. L.; Hollenbeck, J. L.

    2015-06-01

    The recovery of irradiation damage in wrought Zircaloy-2 and Zircaloy-4 was determined following a series of post-irradiation anneals at temperatures ranging from 343 °C to 510 °C and for time periods ranging from 1-h to 500 h. The materials had been irradiated at nominally 358 °C in the High Flux Isotope Reactor (HFIR) at neutron fluences of nominally 3 × 1025 n/m2 (E > 1 MeV). Irradiation at nominally 358 °C resulted in a coarser distribution of loops that result in a 25-45% lower irradiation hardening than reported in the literature for irradiations at 260-326 °C. The irradiation hardening and recovery were determined using tensile testing at room-temperature. Post-irradiation annealing at 343-427 °C was shown to result in an increase in irradiation hardening to values even higher than for the as-irradiated material in the first 1-10 h of annealing. This Radiation Anneal Hardening (RAH) was followed by a relatively slow recovery of the irradiation damage. Much faster recovery with no RAH was observed for post-irradiation annealing at temperatures of 454-510 °C. Irradiation at 358 °C was shown to result in different recovery kinetics than observed in the literature for irradiation at 260-326 °C. While the general trend described above is true for the four materials tested (alpha-annealed and beta-treated Zircaloy-2 and Zircaloy-4), notable and yet unexplained differences in RAH and in recovery are observed between the materials that might be a result of differing solute effects. Examinations of microstructure using Transmission Electron Microscopy were used to investigate the RAH and recovery mechanisms. Agreement between the measured and calculated irradiation hardening using a generalized Orowan hardening model to account for the observed loop structure was not as close for the post irradiation annealed condition as for the as-irradiated condition, which can likely be attributed to unaccounted for changes in the configuration of the loops to

  16. Mechanical behavior of AISI 304SS determined by miniature test methods after neutron irradiation to 28 dpa

    SciTech Connect

    Ellen M. Rabenberg; Brian J. Jaques; Bulent H. Sencer; Frank A. Garner; Paula D. Freyer; Taira Okita; Darryl P. Butt

    2014-05-01

    The mechanical properties of AISI 304 stainless steel irradiated for over a decade in the Experimental Breeder Reactor (EBR-II) were measured using miniature mechanical testing methods. The shear punch method was used to evaluate the shear strengths of the neutron-irradiated steel and a correlation factor was empirically determined to predict its tensile strength. The strength of the stainless steel slightly decreased with increasing irradiation temperature, and significantly increased with increasing dose until it saturated above approximately 5 dpa. Ferromagnetic measurements were used to observe and deduce the effects of the stress-induced austenite to martensite transformation as a result of shear punch testing.

  17. THE INFLUENCE OF NEUTRON-IRRADIATION AT LOW TEMPERATURES ON THE DIELECTRIC PARAMETERS OF 3C-SiC

    SciTech Connect

    J.A.A. Engelbrecht; G. Deyzel; E. Minnaar; W.E. Goosen; I. J. van Rooyen

    2014-04-01

    3C-SiC wafers were irradiated with neutrons of various fluences and at low (200 - 400 ?C) irradiation temperatures. Fourier Transform infrared (FTIR) reflectance spectra were obtained for the samples, and the spectra used to extract the dielectric parameters for each specimen, using statistical curve-fitting procedures. Analysis of all data revealed trends in reflectance peak heights as well as in the dielectric parameters. The surface roughness of the irradiated samples was measured by atomic force spectroscopy (AFM) and certain trends could be ascribed to surface roughness.

  18. Effects of low-temperature fusion neutron irradiation on critical properties of a monofilament niobium-tin superconductor

    SciTech Connect

    Guinan, M.W.; Van Konynenburg, R.A.; Mitchell, J.B.

    1984-03-22

    The objective of this work was to irradiate a Nb/sub 3/Sn superconductor with 14.8 MeV neutrons at 4 K and measure critical current in transverse fields of up to 12 T, irradiating up to a fluence sufficient to decrease the critical current to below its initial value. Critical temperatures were also to be measured. The samples were to be kept near 4 K between the irradiation and the measurement of critical properties. This work is directed toward establishing an engineering design fluence limit for Nb/sub 3/Sn when used in fusion reactor superconducting magnets.

  19. Comparison of Calculated and Measured Neutron Fluence in Fuel/Cladding Irradiation Experiments in HFIR

    SciTech Connect

    Ellis, Ronald James

    2011-01-01

    A recently-designed thermal neutron irradiation facility has been used for a first series of irradiations of PWR fuel pellets in the high flux isotope reactor (HFIR) at Oak Ridge National Laboratory. Since June 2010, irradiations of PWR fuel pellets made of UN or UO{sub 2}, clad in SiC, have been ongoing in the outer small VXF sites in the beryllium reflector region of the HFIR, as seen in Fig. 1. HFIR is a versatile, 85 MW isotope production and test reactor with the capability and facilities for performing a wide variety of irradiation experiments. HFIR is a beryllium-reflected, light-water-cooled and -moderated, flux-trap type reactor that uses highly enriched (in {sup 235}U) uranium (HEU) as the fuel. The reactor core consists of a series of concentric annular regions, each about 2 ft (0.61 m) high. A 5-in. (12.70-cm)-diam hole, referred to as the flux trap, forms the center of the core. The fuel region is composed of two concentric fuel elements made up of many involute-shaped fuel plates: an inner element that contains 171 fuel plates, and an outer element that contains 369 fuel plates. The fuel plates are curved in the shape of an involute, which provides constant coolant channel width between plates. The fuel (U{sub 3}O{sub 8}-Al cermet) is nonuniformly distributed along the arc of the involute to minimize the radial peak-to-average power density ratio. A burnable poison (B{sub 4}C) is included in the inner fuel element primarily to reduce the negative reactivity requirements of the reactor control plates. A typical HEU core loading in HFIR is 9.4 kg of {sup 235}U and 2.8 g of {sup 10}B. The thermal neutron flux in the flux trap region can exceed 2.5 x 10{sup 15} n/cm{sup 2} {center_dot} s while the fast flux in this region exceeds 1 x 10{sup 15} n/cm{sup 2} {center_dot} s. The inner and outer fuel elements are in turn surrounded by a concentric ring of beryllium reflector approximately 1 ft (0.30 m) thick. The beryllium reflector consists of three regions

  20. Radiation damage induced in Al2O3 single crystal sequentially irradiated with reactor neutrons and 90 MeV Xe ions

    NASA Astrophysics Data System (ADS)

    Zirour, H.; Izerrouken, M.; Sari, A.

    2016-06-01

    The present investigation reports the effect of 90 MeV Xe ion irradiation on neutron irradiated Al2O3 single crystals. Three irradiation experiments were performed, with neutrons only, 90 MeV Xe ions only and with neutrons followed by 90 MeV Xe ions. Neutron and 90 MeV Xe ion irradiations were performed at NUR research reactor, Algiers, Algeria and at GANIL accelerator, Caen, France respectively. After irradiation, the radiation damage was investigated by Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), optical absorption measurements, and X-ray diffraction (XRD) techniques. Raman technique revealed that the concentration of the defects formed in Al2O3 samples subsequently irradiated with neutrons and 90 MeV Xe ions is lower than that formed in Al2O3 samples which were irradiated only with neutrons. This reveals the occurrence of ionization-induced recovery of the neutron damage. Furthermore, as revealed by XRD analysis, a new peak is appeared at about 2θ = 38.03° after irradiation at high fluence (>3 × 1013 Xe/cm2). It can be assigned to the formation of new lattice plane.

  1. Characterization of neutron-irradiated HT-UPS steel by high-energy X-ray diffraction microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; Park, Jun-Sang; Almer, Jonathan; Li, Meimei

    2016-04-01

    This paper presents the first measurement of neutron-irradiated microstructure using far-field high-energy X-ray diffraction microscopy (FF-HEDM) in a high-temperature ultrafine-precipitate-strengthened (HT-UPS) austenitic stainless steel. Grain center of mass, grain size distribution, crystallographic orientation (texture), diffraction spot broadening and lattice constant distributions of individual grains were obtained for samples in three different conditions: non-irradiated, neutron-irradiated (3dpa/500 °C), and irradiated + annealed (3dpa/500 °C + 600 °C/1 h). It was found that irradiation caused significant increase in grain-level diffraction spot broadening, modified the texture, reduced the grain-averaged lattice constant, but had nearly no effect on the average grain size and grain size distribution, as well as the grain size-dependent lattice constant variations. Post-irradiation annealing largely reversed the irradiation effects on texture and average lattice constant, but inadequately restored the microstrain.

  2. Fissile material production potential in South Asia

    SciTech Connect

    Nayyar, A.H.; Toor, A.H.; Mian, Z.

    1997-01-01

    The cases of India and Pakistan show how civilian nuclear activities could potentially contribute significantly to the production of weapons-grade fissile materials. The paper estimates the amount of weapons-grade plutonium that could have been produced from unsafeguarded power reactors in India if these reactors were operated deliberately for this purpose, and the rate at which Pakistan could accumulate weapons-grade uranium if it used its stockpile of low-enriched uranium as feed material to its enrichment facilities. These estimates are not judgments of what these countries have actually done or intend to do, but are forwarded to call attention to an issue that will have to be addressed under a fissile material production cutoff in South Asia and elsewhere. The prospect of a Fissile Material Cut-off convention raises important questions about the accumulated fissile material stocks in countries which are known to have nuclear weapons capability. We look here at the cases of India and Pakistan. These two countries have followed different routes to produce fissile material: India has reprocessed spent fuel from nuclear reactors to extract plutonium, while Pakistan has relied on uranium enrichment. While there are estimates available of weapons-grade plutonium (WGPu) production in India, they have assumed that the Indian nuclear power program has made no contribution to such production. Similarly, estimates for uranium enrichment in Pakistan have focused on production of highly enriched uranium (HEU) and not examined the stockpiling of low enriched uranium (LEU) and the time it would take to turn such stockpiled material into weapons-grade material. 24 refs., 5 tabs.

  3. Physics concept on the constellation type fissile fuels and its application to the prospective Th-{sup 233}U reactor

    SciTech Connect

    Jiahua Zhange

    1994-12-31

    In contrast with the conventional nuclear reactor which usually fuelled with one single fissile nuclide, a constellation type fissile fuels reactor consists of a parent nuclide such as {sup 232}Th or {sup 238}U and its whole family of neutron generated daughter nuclides. All of them are regarded as fissile fuels but of quite different fission ability. The concentration of each daughter nuclide is determined by its saturate concentration ratio with the parent nuclide. In such fuel system, the whole fuel consumed by neutron reaction almost completely results in fission production. In this article, some interesting properties of such fuel system, determination of the saturate concentration of each daughter nuclide and applicability to Th-{sup 233}U reactor will be discussed.

  4. Effects of low temperature neutron irradiation on deformation behavior of austenitic stainless steels

    SciTech Connect

    Pawel, J.E.; Rowcliffe, A.F.; Alexander, D.J.; Grossbeck, M.L.; Shiba, K.

    1996-04-01

    An austenitic stainless steel, designated 316LN-IG, has been chosen for the first wall/shield (FW/S) structure for the International Thermonuclear Experimental Reactor (ITER). The proposed operational temperature range for the structure (100 to 250{degree}C) is below the temperature regimes for void swelling (400-600{degree}C) and for helium embrittlement (500-700{degree}C). However, the proposed neutron dose is such that large changes in yield strength, deformation mode, and strain hardening capacity could be encountered which could significantly affect fracture properties. Definition of the irradiation regimes in which this phenomenon occurs is essential to the establishment of design rules to protect against various modes of failure.

  5. Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors.

    PubMed

    Belloir, Jean-Marc; Goiffon, Vincent; Virmontois, Cédric; Raine, Mélanie; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Molina, Romain; Magnan, Pierre; Gilard, Olivier

    2016-02-22

    The dark current produced by neutron irradiation in CMOS Image Sensors (CIS) is investigated. Several CIS with different photodiode types and pixel pitches are irradiated with various neutron energies and fluences to study the influence of each of these optical detector and irradiation parameters on the dark current distribution. An empirical model is tested on the experimental data and validated on all the irradiated optical imagers. This model is able to describe all the presented dark current distributions with no parameter variation for neutron energies of 14 MeV or higher, regardless of the optical detector and irradiation characteristics. For energies below 1 MeV, it is shown that a single parameter has to be adjusted because of the lower mean damage energy per nuclear interaction. This model and these conclusions can be transposed to any silicon based solid-state optical imagers such as CIS or Charged Coupled Devices (CCD). This work can also be used when designing an optical imager instrument, to anticipate the dark current increase or to choose a mitigation technique. PMID:26907077

  6. Effects of thermal aging and neutron irradiation on the mechanical properties of stainless steel weld overlay cladding

    SciTech Connect

    Haggag, F.M.; Nanstad, R.K.

    1991-01-01

    Stainless steel weld overlay cladding was fabricated using the three-wire, series-arc method. Three layers of cladding were applied to a pressure vessel plate to provide adequate thickness for fabrication of test specimens. Since irradiation of the stainless steel cladding to 5 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV) was conducted at 288{degrees}C for 1605 h, tensile, Charpy V-notch (CVN), precracked Charpy V-notch (PCVN), and compact fracture toughness specimens were thermally aged at 288{degrees}C for 1605 h. Additional specimens are being aged to 20,000 and 50,000 h. Thermal aging of three-wire, series-arc stainless steel weld overlay cladding at 288{degrees}C for 1604 h resulted in appreciable decrease (16%) in the CVN upper-shelf energy, but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect, following neutron irradiation at 288{degrees}C to a fluence of 5 {times} 10{sup 19} neutrons/cm{sup 2} (>MeV), was a 22% reduction in the CVN upper-shelf energy and a 29{degrees}C shift at the 41-J level. The effect of thermal aging on tensile properties was very small or negligible. However, the combined effect after neutron irradiation was an increase in the yield strength (6 to 34% at test temperatures from 288 to {minus}125{degrees}C) and no apparent change in ultimate strength and total elongation. Also, neutron irradiation reduced the initiation fracture toughness (J{sub Ic}) much more than did thermal aging. However, irradiation slightly decreased the tearing modulus, but no reduction was caused by thermal aging alone. The effects of long-term thermal exposure times (20,000 and 50,000 h) will be investigated when the specimen become available.

  7. Effects of thermal aging and neutron irradiation on the mechanical properties of stainless steel weld overlay cladding

    SciTech Connect

    Haggag, F.M.; Nanstad, R.K.

    1991-12-31

    Stainless steel weld overlay cladding was fabricated using the three-wire, series-arc method. Three layers of cladding were applied to a pressure vessel plate to provide adequate thickness for fabrication of test specimens. Since irradiation of the stainless steel cladding to 5 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV) was conducted at 288{degrees}C for 1605 h, tensile, Charpy V-notch (CVN), precracked Charpy V-notch (PCVN), and compact fracture toughness specimens were thermally aged at 288{degrees}C for 1605 h. Additional specimens are being aged to 20,000 and 50,000 h. Thermal aging of three-wire, series-arc stainless steel weld overlay cladding at 288{degrees}C for 1604 h resulted in appreciable decrease (16%) in the CVN upper-shelf energy, but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect, following neutron irradiation at 288{degrees}C to a fluence of 5 {times} 10{sup 19} neutrons/cm{sup 2} (>MeV), was a 22% reduction in the CVN upper-shelf energy and a 29{degrees}C shift at the 41-J level. The effect of thermal aging on tensile properties was very small or negligible. However, the combined effect after neutron irradiation was an increase in the yield strength (6 to 34% at test temperatures from 288 to {minus}125{degrees}C) and no apparent change in ultimate strength and total elongation. Also, neutron irradiation reduced the initiation fracture toughness (J{sub Ic}) much more than did thermal aging. However, irradiation slightly decreased the tearing modulus, but no reduction was caused by thermal aging alone. The effects of long-term thermal exposure times (20,000 and 50,000 h) will be investigated when the specimen become available.

  8. Simultaneous impact of neutron irradiation and sputtering on the surface structure of self–damaged ITER–grade tungsten

    SciTech Connect

    Belyaeva, A. I. Savchenko, A. A.; Galuza, A. A.; Kolenov, I. V.

    2014-07-15

    Simultaneous effects of neutron irradiation and long–term sputtering on the surface relief of ITER–grade tungsten were studied. The effects of neutron–induced displacement damage have been simulated by irradiation of tungsten target with W{sup 6+} ions of 20 MeV energy. Ar{sup +} ions with energy 600 eV were used as imitation of charge exchange atoms in ITER. The surface relief was studied after each sputtering act. The singularity in the WJ–IG surface relief was ascertained experimentally at the first time, which determines the law of roughness extension under sputtering. As follows from the experimental data, the neutron irradiation has not to make a decisive additional contribution in the processes developing under impact of charge exchange atoms only.

  9. Radiation hardness of plastic scintillating fiber against fast neutron and [gamma]-ray irradiation

    SciTech Connect

    Murakami, Akira; Yoshinaka, Hideki; Goto, Minehiko . Dept. of Physics)

    1993-08-01

    In future collider experiments, where a background radiation level is estimated to be very high, e.g. around 10[sup 2] [approximately] 10[sup 5] Gy/yr and 10[sup 11] [approximately] 10[sup 14] n/cm[sup 2]/yr at SSC, the detectors operating around the collision point in the experiments will encounter a considerable amount of radiation. Therefore, the detectors, especially the calorimeter, are required to be resistive against high radiation levels. From this point of view, it is of great importance to study the effects of radiation damage on the performance of the detectors. The authors report preliminary results of measurements of radiation hardness of the plastic scintillating fiber Kuraray SCSF-81 against irradiation with fast neutrons and [sup 60]Co [gamma]-rays in the region of the neutron fluence from 1 [times] 10[sup 11] to 5 [times] 10[sup 13] n/cm[sup 2] and the integrated [gamma]-ray dose from 890 to 10[sup 5] Gy, respectively. Deterioration of both intrinsic light yield and light transmittance of the SCSF-81 has been studied.

  10. Development of positron annihilation spectroscopy for investigating deuterium decorated voids in neutron-irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Taylor, C. N.; Shimada, M.; Merrill, B. J.; Akers, D. W.; Hatano, Y.

    2015-08-01

    The present work is a continuation of a recent research to develop and optimize positron annihilation spectroscopy (PAS) for characterizing neutron-irradiated tungsten. Tungsten samples were exposed to neutrons in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory and damaged to 0.025 and 0.3 dpa. Subsequently, they were exposed to deuterium plasmas in the Tritium Plasma Experiment (TPE) at Idaho National Laboratory. The implanted deuterium was desorbed through sample heating to 900 °C, and Doppler broadening (DB)-PAS was performed both before and after heating. Results show that deuterium impregnated tungsten is identified as having a smaller S-parameter. The S-parameter increases after deuterium desorption. Microstructural changes also occur during sample heating. These effects can be isolated from deuterium desorption by comparing the S-parameters from the deuterium-free back face with the deuterium-implanted front face. The application of using DB-PAS to examine deuterium retention in tungsten is examined.

  11. Response of unirradiated and neutron-irradiated vanadium alloys to Charpy-impact loading*1

    NASA Astrophysics Data System (ADS)

    Loomis, B. A.; Smith, D. L.

    1991-03-01

    The ductile-brittle transition temperature (DBTT) was determined by Charpy-impact tests for dehydrogenated ( < 30 appm H) and hydrogenated (400-1200 appm H) V-7.2Cr-14.5Ti, V-9.9Cr-9.2Ti, V-13.5Cr-5.2Ti, V-17.7Ti, V-9.2Cr-4.9Ti, V-9.0Cr-3.2Fe-1.2Zr, V-3.1Ti-0.5Si, V-4.1Cr-4.3Ti, V-4.6Ti, and V-2.5Ti-1.0Si alloys. The DBTT was also determined for V-13.5Cr-5.2Ti, V-9.2Cr-4.9Ti, V-7.2Cr-14.5Ti, and V-17.7Ti alloys after neutron irradiation at 420 and 600°C to 41-44 dpa. The DBTTs determined for these vanadium alloys show that a vanadium alloy containing Cr and/or Ti and Si alloying additions to be used as a structural material in a fusion reactor should contain 3-9 wt% total alloying addition for maximum resistance to hydrogen- and/or irradiation-induced embrittlement.

  12. n-Values of commercial YBCO tapes before and after irradiation by fast neutrons

    NASA Astrophysics Data System (ADS)

    Chudy, M.; Zhong, Z.; Eisterer, M.; Coombs, T.

    2015-03-01

    The n-value is an important superconducting parameter, which represents the homogeneity of characterized superconductor as well as thermally activated depinning. In addition, n-values are important for the evaluation of pinning mechanisms and pinning forces. n-values are crucial input parameters for the numerical simulations of superconducting tapes, coils and other complicated superconducting applications where E-J power law applies. In this publication, complex measurement data of n-values from different 2nd generation of high temperature superconducting (2G HTS) tapes are presented and analysed. In addition, 2G HTS tapes were step-by-step irradiated by fast neutron fluences up to 1 × 1022 m-2. n-values of the irradiated tapes, containing additional randomly distributed pinning centres, are presented, analysed and compared with unirradiated samples. Special attention is placed on the underlying physics resulting in the power-law part of the I-V curve and on the correlation between critical currents and n-values. The measurements are performed within the temperature range of 50-85 K and magnetic fields up to 15 T.

  13. Characterization of irradiated AISI 316L stainless steel disks removed from the Spallation Neutron Source

    SciTech Connect

    Vevera, Bradley J; Hyres, James W; McClintock, David A; Riemer, Bernie

    2014-01-01

    Irradiated AISI 316L stainless steel disks were removed from the Spallation Neutron Source (SNS) for post-irradiation examination (PIE) to assess mechanical property changes due to radiation damage and erosion of the target vessel. Topics reviewed include high-resolution photography of the disk specimens, cleaning to remove mercury (Hg) residue and surface oxides, profile mapping of cavitation pits using high frequency ultrasonic testing (UT), high-resolution surface replication, and machining of test specimens using wire electrical discharge machining (EDM), tensile testing, Rockwell Superficial hardness testing, Vickers microhardness testing, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effectiveness of the cleaning procedure was evident in the pre- and post-cleaning photography and permitted accurate placement of the test specimens on the disks. Due to the limited amount of material available and the unique geometry of the disks, machine fixturing and test specimen design were critical aspects of this work. Multiple designs were considered and refined during mock-up test runs on unirradiated disks. The techniques used to successfully machine and test the various specimens will be presented along with a summary of important findings from the laboratory examinations.

  14. Critical current anisotropy in Nd-1111 single crystals and the influence of neutron irradiation

    NASA Astrophysics Data System (ADS)

    Eisterer, M.; Mishev, V.; Zehetmayer, M.; Zhigadlo, N. D.; Katrych, S.; Karpinski, J.

    2014-04-01

    We report on angle-resolved magnetization measurements on NdFeAsO0.65F0.35 (Nd-1111) single crystals. The field dependence of the critical current density, Jc, is non-monotonic in these crystals at all orientations and temperatures due to the fishtail effect, which strongly influences the angular dependence of Jc. The currents decrease as the field is tilted from the crystallographic c-axis at low fields, but increase at high fields. A peak occurs in the angular dependence of Jc at intermediate fields. The critical currents are significantly enhanced after irradiation with fast neutrons and the fishtail disappears. The different current anisotropies at low and high fields, however, persist. We discuss the data in the framework of the anisotropic scaling approach and propose a transition from dominant pinning by large defects of low density at low fields to pinning by small defects of high density at high fields in the pristine crystal. Strong pinning dominates at all fields after the irradiation, and the angular dependence of Jc can be described via anisotropic scaling only after an appropriate extension to this pinning regime.

  15. Microstructural characterization of deformation localization at small strains in a neutron-irradiated 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Field, Kevin G.; Gussev, Maxim N.; Busby, Jeremy T.

    2014-09-01

    A specific phenomenon - highly localized regions of deformation - was found and investigated at the free surface and near-surface layer of a neutron irradiated AISI 304 stainless steel bend specimen deformed to a maximum surface strain of 0.8%. It was shown that local plastic deformation near the surface might reach significant levels being localized at specific spots even when the maximum free surface strain remains below 1%. The effect was not observed in non-irradiated steel of the same composition at similar strain levels. Cross-sectional EBSD analysis demonstrated that the local misorientation level was highest near the free surface and diminished with increasing depth in these regions. (S)TEM indicated that the local density of dislocation channels might vary up to an order of magnitude. These channels may contain twins or may be twin free depending on grain orientation and local strain levels. BCC-phase (α-martensite) formation associated with channel-grain boundary intersection points was observed using EBSD and STEM in the near-surface layer.

  16. TEM study of radiation damage and annealing of neutron irradiated zirconolite

    SciTech Connect

    Lumpkin, G.R.; Smith, K.L.; Blake, R.G.

    1996-08-01

    Neutron irradiation was used to simulate alpha-decay damage in zirconolite, resulting in a transformation from the crystalline to the amorphous state at doses of 4--25 {times} 10{sup 19} n/cm{sup 2} (E {ge} 1 MeV). With increasing dose, the radiation damage microstructures resemble damage caused by: (1) alpha-decay of {sup 232}Th and {sup 238}U in natural zirconolites, (2) alpha-decay of {sup 238}Pu or {sup 244}Cm in synthetic samples, and (3) collision cascades in samples irradiated with heavy ions. Heavily damaged zirconolite recovers to a defect fluorite phase on annealing at temperatures up to 1,000 C. The main stage of structural recovery was found to occur at temperatures of 600--800 C. The microstructures after heating depend on the initial level of damage: zirconolite grains with low to moderate levels of damage anneal to imperfect single crystals, whereas heavily damaged grains recrystallize to a polycrystalline microstructure. Complications encountered in this work include the production of fission tracks (due to trace amounts of U) and a non-uniform distribution of damage at higher dose levels (possibly due to electron beam heating).

  17. Re-weldability of neutron-irradiated stainless steels studied by multi-pass TIG welding

    NASA Astrophysics Data System (ADS)

    Nakata, K.; Oishi, M.; Koshiishi, M.; Hashimoto, T.; Anzai, H.; Saito, Y.; Kono, W.

    2002-12-01

    Weldability of neutron-irradiated stainless steel (SS) has been studied by multi-pass bead-on-plate and build-up tungsten inert gas (TIG) welding, simulating the repair-welding of reactor components. Specimens were submerged arc welding (SAW) joint of Type 304 SS containing 0.5 appm helium (1.8 appm in the SAW weld metal). Sound welding could be obtained by one- to three-pass welding on the plates at weld heat inputs less than 1 MJ/m in the irradiated 304 SS base metal. In the case of the build-up welding of a groove, no visible defects appeared in the specimen at a heat input as low as 0.4 MJ/m. However, build-up welding at a high heat input of 1 MJ/m was prone to weld cracking, owing to the formation of helium bubbles on grain boundaries of the base metal or dendrite boundaries of pre-existing SAW weld metal, in the area within 0.6 mm from the fusion line.

  18. Deformation localization and dislocation channel dynamics in neutron-irradiated austenitic stainless steels

    DOE PAGESBeta

    Gussev, Maxim N.; Field, Kevin G.; Busby, Jeremy T.

    2015-02-24

    We investigated dynamics of deformation localization and dislocation channel formation in situ in a neutron irradiated AISI 304 austenitic stainless steel and a model 304-based austenitic alloy by combining several analytical techniques including optic microscopy and laser confocal microscopy, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Channel formation was observed at 70% of the formal tensile yield stress for both alloys. It was shown that triple junction points do not always serve as a source of dislocation channels; at stress levels below the yield stress, channels often formed near the middle of the grain boundary. For amore » single grain, the role of elastic stiffness value (Young modulus) in the channel formation was analyzed; it was shown that in the irradiated 304 steels the initial channels appeared in soft grains with a high Schmid factor located near stiff grains with high elastic stiffness. Moreover, the spatial organization of channels in a single grain was analyzed; it was shown that secondary channels operating in the same slip plane as primary channels often appeared at the middle or at one third of the way between primary channels. The twinning nature of dislocation channels was analyzed for grains of different orientation using TEM. Finally, it was shown that in the AISI 304 steel, channels were twin-free in grains oriented close to [001] and [101] of standard unit triangle; [111]-grains and grains oriented close to Schmid factor maximum contained deformation twins.« less

  19. Deformation localization and dislocation channel dynamics in neutron-irradiated austenitic stainless steels

    SciTech Connect

    Gussev, Maxim N.; Field, Kevin G.; Busby, Jeremy T.

    2015-02-24

    We investigated dynamics of deformation localization and dislocation channel formation in situ in a neutron irradiated AISI 304 austenitic stainless steel and a model 304-based austenitic alloy by combining several analytical techniques including optic microscopy and laser confocal microscopy, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Channel formation was observed at 70% of the formal tensile yield stress for both alloys. It was shown that triple junction points do not always serve as a source of dislocation channels; at stress levels below the yield stress, channels often formed near the middle of the grain boundary. For a single grain, the role of elastic stiffness value (Young modulus) in the channel formation was analyzed; it was shown that in the irradiated 304 steels the initial channels appeared in soft grains with a high Schmid factor located near stiff grains with high elastic stiffness. Moreover, the spatial organization of channels in a single grain was analyzed; it was shown that secondary channels operating in the same slip plane as primary channels often appeared at the middle or at one third of the way between primary channels. The twinning nature of dislocation channels was analyzed for grains of different orientation using TEM. Finally, it was shown that in the AISI 304 steel, channels were twin-free in grains oriented close to [001] and [101] of standard unit triangle; [111]-grains and grains oriented close to Schmid factor maximum contained deformation twins.

  20. Effect of Neutron Irradiation on Properties of Pb(Mg(1/3)Nb(2/3))O3-PbTiO3.

    PubMed

    Kim, Yong-Il; Choi, Namkyoung; Kim, Geunwoo; Lee, Yun-Hee; Baek, Kwang-Sae; Kim, Ki-Bok

    2015-11-01

    The effect of neutron irradiation on the electrical and piezoelectric properties of a PMN-PT [(Pb(Mg(1/3)Nb(2/3))O3-PbTiO3)] single crystal such as permittivity, electrical impedance and piezoelectric constant d33 has been investigated at 1 kHz. The changes of d33 and permittivity depending on the dose of neutron irradiation for all samples of PMN-PT single crystal were found. In all samples, the permittivity, and piezoelectric constant d33 decreased with the increase of irradiation dose. Changes of XRD patterns depending on the dose of neutron irradiation for all samples were found. From the results of XRDs for analyzing the formation of the PMN-PT single crystals in single phase, the neutron irradiation will affect the crystallinity of PMN-PT single crystals. PMID:26726526

  1. Characterization of neutron flux spectra in the irradiation sites of a 37 GBq 241Am-Be isotopic source

    NASA Astrophysics Data System (ADS)

    Yücel, Haluk; Budak, Mustafa Guray; Karadag, Mustafa; Yüksel, Alptuğ Özer

    2014-11-01

    For the applicability of instrumental neutron activation analysis (NAA) technique, an irradiation unit with a 37 GBq 241Am-Be neutron source was installed at Institute of Nuclear Sciences of Ankara University. Design and configuration properties of the irradiation unit are described. It has two different sample irradiation positions, one is called site #1 having a pneumatic sample transfer system and the other is site #2 having a location for manual use. In order to characterize neutron flux spectra in the irradiation sites, the measurement results were obtained for thermal (Фth) and epithermal neutron fluxes (Фepi), thermal to epithermal flux ratio (f) and epithermal spectrum shaping factors (α) by employing cadmium ratios of gold (Au) and molybdenum (Mo) monitors. The activities produced in these foils were measured by using a p-type, 44.8% relative efficiency HPGe well detector. For the measured γ-rays, self-absorption and true coincidence summing effects were taken into account. Additionally, thermal neutron self-shielding and resonance neutron self-shielding effects were taken into account in the measured results. For characterization of site #1, the required parameters were found to be Фth = (2.11 ± 0.05) × 103 n cm-2 s-1, Фepi = (3.32 ± 0.17) × 101 n cm-2 s-1, f = 63.6 ± 1.5, α = 0.045 ± 0.009, respectively. Similarly, those parameters were measured in site #2 as Фth = (1.49 ± 0.04) × 103 n cm-2 s-1, Фepi = (2.93 ± 0.15) × 101 n cm-2 s-1, f = 50.9 ± 1.3 and α = 0.038 ± 0.008. The results for f-values indicate that good thermalization of fast neutrons on the order of 98% was achieved in both sample irradiation sites. This is because an optimum combination of water and paraffin moderator is used in the present configuration. In addition, the shielding requirements are met by using natural boron oxide powder (5.5 cm) and boron loaded paraffin layers against neutrons, and a 15 cm thick lead bricks against gamma-rays from source and its

  2. Transmission electron microscopy investigation of the microstructure of Fe-Cr alloys induced by neutron and ion irradiation at 300 °C

    NASA Astrophysics Data System (ADS)

    Hernández-Mayoral, M.; Heintze, C.; Oñorbe, E.

    2016-06-01

    Four Fe-Cr binary alloys, with Cr content from 2.5 up to 12wt%, were neutron or ion irradiated up to a dose of 0.6 dpa at 300 °C. The microstructural response to irradiation has been characterised using Transmission Electron Microscopy (TEM). Both, neutrons and ions, gave rise to the formation of dislocation loops. The most striking difference between ion and neutron irradiation is the distribution of these loops in the sample. Except for the lowest Cr content, loops are distributed mainly along grain boundaries and dislocations in the neutron irradiated samples. The inhomogeneous distribution of dislocation loops could be related to the presence of α‧ precipitates in the matrix. In contrast, a homogeneous distribution is observed in all ion irradiated samples. This important difference is attributed to the orders of magnitude difference in dose rate between these two irradiation conditions. Moreover, the density of loops depends non-monotonically on Cr content in case of neutron irradiation, while it seems to increase with Cr content for ion implantation. Differences are also observed in terms of cluster size, with larger sizes for neutron irradiation than for ion implantation, again pointing towards an effect of the dose rate.

  3. Changes in magnetic parameters of neutron irradiated SA 508 Cl. 3 reactor pressure vessel forging and weld surveillance specimens

    NASA Astrophysics Data System (ADS)

    Chi, Se-Hwan; Chang, Kee-Ok; Hong, Jun-Hwa; Kuk, Il-Hiun; Kim, Chong-Oh

    1999-04-01

    Irradiation-induced changes in the magnetic parameters and mechanical properties were measured and compared to explore possible correlations for reactor pressure vessel (RPV) forging and weld surveillance Charpy specimens which were irradiated to the neutron fluence of 2.3×1019n/cm2 (E>1.0 MeV) in a typical pressurized water reactor environment at 290 °C. For mechanical property parameters, Vickers microhardness, tensile and Charpy impact tests were performed and saturation magnetization (Ms), remanence (Mr), coercivity (Hc), and Barkhausen noise amplitude (BNA) were measured for magnetic parameters for both unirradiated and irradiated specimens, respectively. Results of mechanical property measurements showed an increase in yield and tensile strength, Vickers microhardness, 30 ft. lb indexed RTNDT and a decrease in Charpy upper-shelf energy irrespective of forging and weld metals. Hysteresis loops appeared to turn clockwise, resulting in an increase in Hc, and BNA appeared to decrease after irradiation. Both magnetic parameters showed viable correlations to the changes in mechanical parameters (Vickers microhardness, Charpy upper shelf energy) due to irradiation. Even limited, the present study seems to show additional possibilities for the application of this magnetic method in monitoring the mechanical parameter changes due to neutron irradiation.

  4. FISSION NEUTRON IRRADIATION EFFECT ON INTERLAMINAR SHEAR STRENGTH OF CYANATE ESTER RESIN GFRP AT RT AND 77 K

    SciTech Connect

    Nishimura, A.; Izumi, Y.; Nishijima, S.; Hemmi, T.; Koizumi, K.; Takeuchi, T.; Shikama, T.

    2010-04-08

    A glass fiber reinforced plastic (GFRP) with cyanate ester resin was fabricated and neutron irradiation tests up to 1x10{sup 22} n/m{sup 2} of fast neutron with over 0.1 MeV energy were carried out in fission reactor. The fabrication process of cyanate ester GFRP was established and a collaboration network to perform investigations on irradiation effect of superconducting magnet materials was constructed. Three kinds of samples were fabricated. The first was CTD403 GFRP made by NIFS, the second was (cyanate ester+epoxy) GFRP provided by Toshiba, and the last was CTD403 GFRP made by Toshiba. The irradiation was carried out at JRR-3 in Japan Atomic Energy Agency using Rabbit capsules.After the irradiation, short beam tests were conducted at room temperature and 77 K and interlaminar shear strength (ILSS) was evaluated. The irradiation of 1x10{sup 21} n/m{sup 2} increased ILSS a little but 1x10{sup 22} n/m{sup 2} irradiation decreased ILSS to around 50 MPa. These tendencies were observed in all three kinds of GFRPs.

  5. Fission Neutron Irradiation Effect on Interlaminar Shear Strength of Cyanate Ester Resin Gfrp at RT and 77 K

    NASA Astrophysics Data System (ADS)

    Nishimura, A.; Izumi, Y.; Nishijima, S.; Hemmi, T.; Koizumi, K.; Takeuchi, T.; Shikama, T.

    2010-04-01

    A glass fiber reinforced plastic (GFRP) with cyanate ester resin was fabricated and neutron irradiation tests up to 1×1022 n/m2 of fast neutron with over 0.1 MeV energy were carried out in fission reactor. The fabrication process of cyanate ester GFRP was established and a collaboration network to perform investigations on irradiation effect of superconducting magnet materials was constructed. Three kinds of samples were fabricated. The first was CTD403 GFRP made by NIFS, the second was (cyanate ester+epoxy) GFRP provided by Toshiba, and the last was CTD403 GFRP made by Toshiba. The irradiation was carried out at JRR-3 in Japan Atomic Energy Agency using Rabbit capsules. After the irradiation, short beam tests were conducted at room temperature and 77 K and interlaminar shear strength (ILSS) was evaluated. The irradiation of 1×1021 n/m2 increased ILSS a little but 1×1022 n/m2 irradiation decreased ILSS to around 50 MPa. These tendencies were observed in all three kinds of GFRPs.

  6. Industrial production of 131I by neutron irradiation and melting of sintered TeO2

    NASA Astrophysics Data System (ADS)

    Alanis, Jose; Navarrete, Manuel

    2001-07-01

    Optimal conditions of temperature and reaction rate have been settled to produce high purity TeO2 by the chemical reaction between Te and HNO3. Also, heating and time conditions for sintering this product have been found, in order to create cavities in the crystal inside, where a gaseous element such as iodine can be adsorbed with minimal leaking. In this way it is fabricated a suitable target to be irradiated with thermal neutrons for obtaining 131Te(t1/2=24.8 m) and 131mTe(t1/2=30 h) by (n, γ) nuclear reactions. Irradiation time has been chosen to get 131Te saturation activity (ti=150 m) because much longer irradiation times do not increase significantly total activity. Since parents 131Te and 131mTe have shorter half life than daughter 131I(t1/2=8.05 d) optimal cooling time must permit daughter activity to grow up till a maximum (tc=4d). Then, sintered cylinder shaped radioactive sample is manipulated in a hot cell, transported and put on a quartz tray, keeping Health Physics regulations. The quartz tray is inside a small electric oven enclosed in an airtight box with negative pressure (water 0.5 cm). There, it is gradually heated till melting point (733 °C). From 400 °C on, vapors are pumped out and bubbled in two solutions: one is 0.1 M NaOH, which retains nearly 99.9% of pumped 131I. Other is 0.02 M Na2CO3 (60%) plus 0.0025 M NaHCO3 (40%), which retains the remaining sample residue. Air filtering is accomplished by activated carbon and alumina filters in the inflow, glass wool fiber before bubbling, and activated carbon again in the outflow.

  7. Fissile material measurements using the differential die-away self interrogation technique

    SciTech Connect

    Schear, Melissa A; Menlove, Howard O; Tobin, Stephen J; Evans, Louise G; Lee, S Y

    2010-01-01

    Currently, there is substantial research effort focused on quantifying plutonium (Pu) mass in spent fuel using non-destructive assay (NDA) techniques. Of the several techniques being investigated for this purpose, Differential Die-Away Self-Interrogation (DDSI) is a recently proposed, neutron-based NDA technique capable of quantifying the total fissile content in an assembly. Unlike the conventional Differential Die-Away (DDA) technique, DOSI does not require an external neutron source for sample interrogation, but rather, uses the spontaneous fission neutrons originating from {sup 244}Cm within the spent fuel for self-interrogation. The essence of the technique lies in the time separation between the detection of spontaneous fission neutrons from {sup 244}Cm and the detection of induced fission neutrons at a later time. The DDSI detector design imposes this time separation by optimizing the die-away times ({tau}) of the detector and sample interrogation regions to obtain an early and late neutron distribution respectively. The ratio of the count rates in the late gate to the early gate for singles, doubles, and triples is directly proportional to the fissile content present in the sample, which has already been demonstrated for simplified fuel cases using the Monte Carlo N-Particle eXtended (MCNPX) code. The current work applies the DDSI concept to more complex samples, specifically spent Pressurized Water Reactor (PWR) assemblies with varying isotopics resulting from a range of initial enrichment, bumup, and cooling time. We assess the feasibility of using the late gate to early gate ratio as a reliable indicator of overall fissile mass for a range of assemblies by defining a {sup 239}Pu effective mass which indicates the mass of {sup 239}Pu that would yield the same DDSI signal as the combined mass of major fissile isotopes present in the sample. This work is important for assessing the individual capability of the DDSI instrument in quantifying fissile mass in

  8. Subtask 12F4: Effects of neutron irradiation on the impact properties and fracture behavior of vanadium-base alloys

    SciTech Connect

    Chung, H.M.; Loomis, B.A.; Smith, D.L.

    1995-03-01

    Up-to-date results on the effects of neutron irradiation on the impact properties and fracture behavior of V, V-Ti, V-Cr-Ti and V-Ti-Si alloys are presented in this paper, with an emphasis on the behavior of the U.S. reference alloys V-4Cr-4Ti containing 500-1000 wppm Si. Database on impact energy and cluctile-brittle transition temperature (DBTT) has been established from Charpy impact tests of one-third-size specimens irradiated at 420{degrees}C-600{degrees}C up to {approx}50 dpa in lithium environment in fast fission reactors. To supplement the Charpy impact tests fracture behavior was also characterized by quantitative SEM fractography on miniature tensile and disk specimens that were irradiated to similar conditions and fractured at -196{degrees}C to 200{degrees}C by multiple bending. For similar irradiation conditions irradiation-induced increase in DBTT was influenced most significantly by Cr content, indicating that irradiation-induced clustering of Cr atoms takes place in high-Cr (Cr {ge} 7 wt.%) alloys. When combined contents of Cr and Ti were {le}10 wt.%, effects of neutron irradiation on impact properties and fracture behavior were negligible. For example, from the Charpy-impact and multiple-bend tests there was no indication of irradiation-induced embrittlement for V-5Ti, V-3Ti-1Si and the U.S. reference alloy V-4Cr-4Ti after irradiation to {approx}34 dpa at 420{degrees}C to 600{degrees}C, and only ductile fracture was observed for temperatures as low as -196{degrees}C. 14 refs., 8 figs., 1 tab.

  9. Irradiation Effect of 14 MeV Neutron on Interlaminar Shear Strength of Glass Fiber Reinforced Plastics

    SciTech Connect

    Nishimura, A.; Hishinuma, Y.; Seo, K.; Tanaka, T.; Muroga, T.; Nishijima, S.; Katagiri, K.; Takeuchi, T.; Shindo, Y.; Ochiai, K.; Nishitani, T.; Okuno, K.

    2006-03-31

    Design activity of International Thermonuclear Experimental Reactor clarifies intense neutron streaming from ports for neutral beam injectors. Energy spectrum of the streaming is very wide and 14 MeV neutron and gamma ray are the typical radiations. Large amount of glass fiber reinforced plastics will be used in a superconducting magnet system as an electric insulation material and a support structure, for such organic material is easy to manufacture, and light and cheap. In this report, effects of 14 MeV neutron and gamma ray irradiation on interlaminar shear strength and fracture mode are investigated using G-10CR small specimen of which configuration was proposed as a standard for evaluation of the interlaminar shear strength. A short beam test under three point bending was conducted at room temperature and 77 K. Neutron fluence of 3.91 x 1019 n/m2 was irradiated and the specimens did not show clear degradation of the strength. On the other hand, gamma ray irradiation of 1 MGy made the specimen weaker and 10 MGy caused delamination. Most of the specimens showed both of interlaminar cracking and bending fracture, but some specimens were fractured with irregular shear occurred on the planes connecting loading point and supporting points.

  10. Irradiation effects in 6H-SiC induced by neutron and heavy ions: Raman spectroscopy and high-resolution XRD analysis

    NASA Astrophysics Data System (ADS)

    Chen, Xiaofei; Zhou, Wei; Feng, Qijie; Zheng, Jian; Liu, Xiankun; Tang, Bin; Li, Jiangbo; Xue, Jianming; Peng, Shuming

    2016-09-01

    Irradiation effects of neutron and 3 MeV C+, Si+ in 6H-SiC were investigated by Raman spectroscopy and high-resolution XRD. The total disorder values of neutron irradiated SiC agree well with that of samples irradiated by ions at the same doses respectively. On the other hand, high-resolution XRD results shows that the lattice strain rate caused by neutron irradiation is 6.8%/dpa, while it is only 2.6%/dpa and 4.2%/dpa for Si+ and C+ irradiations respectively. Our results illustrate that the total disorder in neutron irradiated SiC can be accurately simulated by MeV Si+ or C+ irradiations at the same dose, but for the lattice strain and strain-related properties like surface hardness, the depth profile of irradiation damages induced by energetic ions must be considered. This research will contribute to a better understanding of the difference in irradiation effects between neutron and heavy ions.

  11. Response functions for computing absorbed dose to skeletal tissues from neutron irradiation.

    PubMed

    Bahadori, Amir A; Johnson, Perry; Jokisch, Derek W; Eckerman, Keith F; Bolch, Wesley E

    2011-11-01

    Spongiosa in the adult human skeleton consists of three tissues-active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM(50)), defined as all tissues lying within the first 50 µm of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM(50) targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM(50) and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM(50) DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 Me

  12. Response functions for computing absorbed dose to skeletal tissues from neutron irradiation

    NASA Astrophysics Data System (ADS)

    Bahadori, Amir A.; Johnson, Perry; Jokisch, Derek W.; Eckerman, Keith F.; Bolch, Wesley E.

    2011-11-01

    Spongiosa in the adult human skeleton consists of three tissues—active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM50), defined as all tissues lying within the first 50 µm of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM50 targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM50 and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM50 DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 Me

  13. Neutron irradiation and frequency effects on the electrical conductivity of nanocrystalline silicon carbide (3C-SiC)

    NASA Astrophysics Data System (ADS)

    Huseynov, Elchin

    2016-09-01

    In this present work nanocrystalline silicon carbide (3C-SiC) has been irradiated with neutron flux (∼ 2 ×1013 ncm-2s-1) up to 20 hours at different periods. Electrical conductivity of nanocrystalline 3C-SiC particles (∼18 nm) is comparatively analyzed before and after neutron irradiation. The frequency dependencies of electrical conductivity of 3C-SiC nanoparticles is reviewed at 100 K-400 K temperature range before and after irradiation. The measurements were carried out at 0.1 Hz-2.5 MHz frequency ranges and at different temperatures. Radiation-induced conductivity (RIC) was observed in the nanocrystalline 3C-SiC particles after neutron irradiation and this conductivity study as a function of frequency are presented. The type of conductivity has been defined based on the interdependence between real and imaginary parts of electrical conductivity function. Based on the obtained results the mechanism behind the electrical conductivity of nanocrystalline 3C-SiC particles is explained in detail.

  14. Characterization of Neutron and Gamma Dose in the Irradiation Cell of Texas A and M University Research Reactor

    SciTech Connect

    Vasudevan, Latha; Reece, Warren D.; Chirayath, Sunil S.; Aghara, Sukesh

    2011-07-01

    The Monte Carlo N-Particle (MCNP) code was used to develop a three dimensional computational model of the Texas A and M University Nuclear Science Center Reactor (NSCR) operating against the irradiation (dry cell) at steady state thermal power of 1 MW. The geometry of the NSCR core and the dry cell were modeled in detail. NSCR is used for a wide variety of experiments that utilizes the dry cell for neutron as well as gamma irradiation of samples. Information on the neutron and gamma radiation environment inside the dry cell is required to facilitate irradiation of samples. This paper presents the computed neutron flux, neutron and gamma dose rate, and foil reaction rates in the dry cell, obtained through MCNP5 simulations of the NSCR core. The neutron flux was measured using foil activation method and the reaction rates obtained from {sup 197}Au(n,{gamma}){sup 198}Au and {sup 54}Fe(n,p){sup 54}Mn were compared with the model and they showed agreement within {approx} 20%. The gamma dose rate at selected locations inside the dry cell was measured using radiochromic films and the results indicate slightly higher dose rates than predicted from the model. This is because the model calculated only prompt gamma dose rates during reactor operation while the radiochromic films measured gammas from activation products and fission product decayed gammas. The model was also used to calculate the neutron energy spectra for the energy range from 0.001 eV- 20 MeV. (authors)

  15. Anisotropic swelling and microcracking of neutron irradiated Ti3AlC2-Ti5Al2C3 materials

    DOE PAGESBeta

    Ang, Caen K.; Silva, Chinthaka M.; Shih, Chunghao Phillip; Koyanagi, Takaaki; Katoh, Yutai; Zinkle, Steven J.

    2015-12-17

    Mn + 1AXn (MAX) phase materials based on Ti–Al–C have been irradiated at 400 °C (673 K) with fission neutrons to a fluence of 2 × 1025 n/m2 (E > 0.1 MeV), corresponding to ~ 2 displacements per atom (dpa). We report preliminary results of microcracking in the Al-containing MAX phase, which contained the phases Ti3AlC2 and Ti5Al2C3. Equibiaxial ring-on-ring tests of irradiated coupons showed that samples retained 10% of pre-irradiated strength. Volumetric swelling of up to 4% was observed. Phase analysis and microscopy suggest that anisotropic lattice parameter swelling caused microcracking. Lastly, variants of titanium aluminum carbide may bemore » unsuitable materials for irradiation at light water reactor-relevant temperatures.« less

  16. Mechanical behavior of AISI 304SS determined by miniature test methods after neutron irradiation to 28 dpa

    NASA Astrophysics Data System (ADS)

    Rabenberg, Ellen M.; Jaques, Brian J.; Sencer, Bulent H.; Garner, Frank A.; Freyer, Paula D.; Okita, Taira; Butt, Darryl P.

    2014-05-01

    The mechanical properties of AISI 304 stainless steel irradiated for over a decade in the Experimental Breeder Reactor (EBR-II) were measured using miniature mechanical testing methods. The shear punch method was used to evaluate the shear strengths of the neutron-irradiated steel and a correlation factor was empirically determined to predict its tensile strength. The strength of the stainless steel slightly decreased with increasing irradiation temperature, and significantly increased with increasing dose until it saturated above approximately 5 dpa. An effective tensile strain hardening exponent was also obtained from the data which shows a relative decrease in ductility of steel with increased irradiation damage. Ferromagnetic measurements were used to observe and deduce the effects of the stress-induced austenite to martensite transformation as a result of shear punch testing.

  17. Resistance of (Fe, Ni)/sub 3/V long-range-ordered alloys to neutron and ion irradiation

    SciTech Connect

    Braski, D.N.

    1981-01-01

    A series of (Fe, Ni)/sub 3/V long-range-ordered alloys were irradiated with neutrons in the Oak Ridge Research Reactor (ORR) and with 4 MeV Ni ions at temperatures above 250/sup 0/C. The displacement damage levels for the two irradiations were 3.8 and 70 dpa, and the helium levels were 29 and 560 at. ppM, respectively. Irradiation in ORR generally increased the yield strength and lowered the ductility of an LRO alloy, but produced relatively little swelling. The LRO alloys retained their long-range order after ion irradiation below the critical ordering temperature, T/sub c/, and exhibited low swelling. Above T/sub c/ the alloys were disordered and showed greater swelling. Adjustment of alloy composition to prevent sigma phase formation reduced swelling.

  18. Neutron spectrum effect on pressure vessel embrittlement: Dosimetry and qualification of irradiation locations in OSIRIS and SILOE reactors

    SciTech Connect

    Alberman, A.; Bourdet, L.; Carcreff, H.; Beretz, D.

    1994-12-31

    Two irradiation experiments have been undertaken in OSIRIS (Saclay) and SILOE (Grenoble) reactors, in order to establish the correlation between the embrittlement of pressure vessel steels and neutron spectrum. Target fluence is 0.1 dpa for both experiments. This damage fluence corresponds to a fluence of 7.5 10{sup 19} n.cm{sup {minus}2} E > 1 MeV (7.5 10{sup 15} n.m{sup {minus}2}) in the case of a well moderated light water spectrum, but only 45 10{sup 19} n.cm{sup {minus}2} in the case of the specially designed SILOE irradiation location. One irradiation run is now completed, the second one is underway. This paper presents the experimental dosimetry data and irradiation parameters obtained in the preliminary qualification program, needed to assess this damage correlation.

  19. Overview of the US-Japan collaborative investigation on hydrogen isotope retention in neutron-irradiated and ion-damaged tungsten

    SciTech Connect

    Masashi Shimada; Y. Hatano; Y. Oya; T. Oda; M. Hara; G. Cao; M. Kobayashi; M. Sokolov; H. Watanabe; B. Tyburska; Y. Ueda; P. Calderoni

    2011-09-01

    Plasma-facing components (PFCs) will be exposed to 14 MeV neutrons from deuterium-tritium (D-T) fusion reactions, and tungsten, a candidate PFC for the divertor in ITER, is expected to receive a neutron dose of 0.7 displacement per atom (dpa) by the end of operation in ITER. The effect of neutron-irradiation damage has been mainly simulated using high-energy ion bombardment. While this prior database of results is quite valuable for understanding the behavior of hydrogen isotopes in PFCs, it does not encompass the full range of effects that must be considered in a practical fusion environment due to short penetration depth, damage gradient, high damage rate, and high PKA energy spectrum of the ion bombardment. In addition, neutrons change the elemental composition via transmutations, and create a high radiation environment inside PFCs, which influence the behavior of hydrogen isotope in PFCs, suggesting the utilization of fission reactors is necessary for neutron irradiation. Therefore, the effort to correlate among high-energy ions, fission neutrons, and fusion neutrons is crucial for accurately estimating tritium retention under a neutron-irradiation environment. Under the framework of the US-Japan TITAN program, tungsten samples (99.99 at. % purity from A.L.M.T. Co.) were irradiated by neutron in the High Flux Isotope Reactor (HFIR), ORNL, at 50 and 300C to 0.025, 0.3, and 1.2 dpa, and the investigation of deuterium retention in neutron-irradiation was performed in the INL Tritium Plasma Experiment (TPE), the unique high-flux linear plasma facility that can handle tritium, beryllium and activated materials. This paper reports the recent results from the comparison of ion-damaged tungsten via various ion species (2.8 MeV Fe2+, 20 MeV W2+, and 700 keV H-) with that from neutron-irradiated tungsten to identify the similarities and differences among them.

  20. Simultaneous {sup 233}U and{sup 235}U characterization through the assay of delayed neutron temporal behavior

    SciTech Connect

    Sellers, M. T.; Corcoran, E. C.; Kelly, D. G.

    2012-07-01

    Aqueous solutions containing dissolved uranium-233 and uranium-235 were irradiated for 60's in the SLOWPOKE-2 reactor at the Royal Military College of Canada. The temporal behavior of the delayed neutrons produced was recorded by the Facility's Delayed Neutron Counting (DNC) system. The percentage of uranium-233 as a function of total fissile mass present in each sample ranged from 0 to 100% and was predicted by the DNC system with average absolute errors of {+-} 4%. Future work will upgrade the system electronics and software to reduce both uncertainties in timings and electrical noise. Mixture analysis will also be expanded to include plutonium-239 and fissile materials contained in non-aqueous matrices. (authors)

  1. Apparatus and method for quantitatively evaluating total fissile and total fertile nuclide content in samples. [Patent application

    DOEpatents

    Caldwell, J.T.; Kunz, W.E.; Cates, M.R.; Franks, L.A.

    1982-07-07

    Simultaneous photon and neutron interrogation of samples for the quantitative determination of total fissile nuclide and total fertile nuclide material present is made possible by the use of an electron accelerator. Prompt and delayed neutrons produced from resulting induced fission are counted using a single detection system and allow the resolution of the contributions from each interrogating flux leading in turn to the quantitative determination sought. Detection limits for /sup 239/Pu are estimated to be about 3 mg using prompt fission neutrons and about 6 mg using delayed neutrons.

  2. Effect of neutron irradiation at low temperature on the embrittlement of the reduced-activation ferritic steels

    NASA Astrophysics Data System (ADS)

    Rybin, V. V.; Kursevich, I. P.; Lapin, A. N.

    1998-10-01

    Effects of neutron irradiation to fluence of 2.0 × 10 24 n/m 2 ( E > 0.5 MeV) in temperature range 70-300°C on mechanical properties and structure of the experimental reduced-activation ferritic 0.1%C-(2.5-12)%Cr-(1-2)%W-(0.2-0.7)%V alloys were investigated. The steels were studied in different initial structural conditions obtained by changing the modes of heat treatments. Effect of neutron irradiation estimated by a shift in ductile-brittle transition temperature (ΔDBTT) and reduction of upper shelf energy (ΔUSE) highly depends on both irradiation condition and steel chemical composition and structure. For the steel with optimum chemical composition (9Cr-1.5WV) after irradiation to 2 × 10 24 n/m 2 ( E ⩾ 0.5 MeV) at 280°C the ΔDBTT does not exceed 25°C. The shift in DBTT increased from 35°C to 110°C for the 8Cr-1.5WV steel at a decrease in irradiation temperature from 300°C to 70°C. The CCT diagrams are presented for several reduced-activated steels.

  3. Experimental plan for irradiation experiment HRB-21

    SciTech Connect

    Goodin, D. T.; Kania, M. J.; Patton, B. W.

    1989-04-01

    Irradiation experiment HRB-21 is the first in a series of test capsules that are designed to provide a fuel-performance data base to be used for the validation of modular high-temperature gas-cooled reactor (MHTGR) coated-particle fuel performance models under MHTGR normal operating conditions and specific licensing basis events. Capsule HRB-21 will contain an advanced TRISO-P UCO/ThO{sub 2} - coated-particle fuel system with demonstrated low defective-particle fraction ({le}5 {times} 10{sup {minus}5}) and a heavy metal-contamination fraction ({le}1 {times} 10{sup {minus}5}) that meets MHTGR quality specifications. The coated particles and fuel compacts were fabricated in laboratory-scale facilities using MHTGR reference procedures at General Atomics (GA). Nearly 150,000 fissile and fertile particles will be irradiated in capsule HRB-21 at a mean volumetric fuel temperature of 975{degree}C and will achieve a peak fissile burnup of 26% fissions per initial metal atom (FIMA) while accumulating a fast neutron fluence of about 4.5 {times} 10{sup 25} neutrons/m{sup 2}. This experiment is a cooperative effort between the US Department of Energy (DOE) and the Japan Atomic Energy Research Institute (JAERI). The participants are the Oak Ridge National Laboratory (ORNL), GA, and the Tokai Research Establishment. Capsule HRB-21 will contain the US MHTGR fuel specimens, and a companion capsule, HRB-22, will contain the JAERI fuel. The irradiation will take place in the removable beryllium reflector facility of the High Flux Isotope Reactor (HFIR) at ORNL. The performance of the fuel during irradiation will be closely monitored through on-line fission gas release measurements. Detailed postirradiation examination and conduction cooldown simulation testing will be performed on the irradiated fuel compacts from both the HRB-21 and HRB-22 capsules. 5 refs., 9 figs., 6 tabs.

  4. Experimental validation of the new nanodosimetry-based cell survival model for mixed neutron and gamma-ray irradiation.

    PubMed

    Wang, C-K Chris; Zhang, Xin; Gifford, Ian; Burgett, Eric; Adams, Vince; Al-Sheikhly, Mohamad

    2007-09-01

    The new nanodosimetry-based linear-quadratic (LQ) formula has been reviewed for mixed-LET irradiation. V-79 Chinese hamster cells have been irradiated with a mixed-LET field of fission neutrons and gamma rays at the University of Maryland Training Reactor (MUTR). The results show that the experimental survival curve agrees well with that predicted by the new nanodosimetry-based LQ model. The experimental study described in this note, therefore, serves as a validation for the new model to be used for mixed-LET radiotherapies, e.g. 252Cf brachytherapy. PMID:17762072

  5. Experimental validation of the new nanodosimetry-based cell survival model for mixed neutron and gamma-ray irradiation

    NASA Astrophysics Data System (ADS)

    Wang, C.-K. Chris; Zhang, Xin; Gifford, Ian; Burgett, Eric; Adams, Vince; Al-Sheikhly, Mohamad

    2007-09-01

    The new nanodosimetry-based linear-quadratic (LQ) formula has been reviewed for mixed-LET irradiation. V-79 Chinese hamster cells have been irradiated with a mixed-LET field of fission neutrons and gamma rays at the University of Maryland Training Reactor (MUTR). The results show that the experimental survival curve agrees well with that predicted by the new nanodosimetry-based LQ model. The experimental study described in this note, therefore, serves as a validation for the new model to be used for mixed-LET radiotherapies, e.g. 252Cf brachytherapy.

  6. Neutron irradiation of V-Cr-Ti alloys in the BOR-60 fast reactor: Description of the fusion-1 experiment

    SciTech Connect

    Rowcliffe, A.F.; Tsai, H.C.; Smith, D.L.

    1997-08-01

    The FUSION-1 irradiation capsule was inserted in Row 5 of the BOR-60 fast reactor in June 1995. The capsule contains a collaborative RF/U.S. experiment to investigate the irradiation performance of V-Cr-Ti alloys in the temperature range 310 to 350{degrees}C. This report describes the capsule layout, specimen fabrication history, and the detailed test matrix for the U.S. specimens. A description of the operating history and neutronics will be presented in the next semiannual report.

  7. Experimental verification of equilibrium para-hydrogen levels in hydrogen moderators irradiated by spallation neutrons at J-PARC

    NASA Astrophysics Data System (ADS)

    Teshigawara, M.; Harada, M.; Tatsumoto, H.; Aso, T.; Ohtsu, K.; Takada, H.; Futakawa, M.; Ikeda, Y.

    2016-02-01

    By sampling gaseous hydrogen from a circulating liquid hydrogen loop for Laser Raman spectroscopy, we measured the para-/ortho-hydrogen fractions in liquid hydrogen under neutron irradiation for the first time to identify whether irradiated hydrogen has an elevated ortho-hydrogen fraction. This measurement indicates that para-hydrogen equilibrium persists at 300 kW proton power in the presence of an iron(III) oxide hydroxide [Fe(OH)3] catalyst. The measurements will be repeated as the power at the Japan Proton Accelerator Research Complex (J-PARC) increases to the MW level.

  8. THE EFFECT OF POST-IRRADATION ANNEALING ON STACKING FAULT TETRAHEDRA IN NEUTRON-IRRADIATED OFHC COPPER

    SciTech Connect

    Edwards, Danny J.; Singh, Bachu N.; Eldrup, M.

    2003-09-03

    Two irradiation experiments have been completed wherein two sets of tensile specimens of OFHC copper were irradiated with fission neutrons, one set at 200 degrees C and the other at 250 degrees C. Post-irradiation annealing in vacuum was then used to evaluate the change in the defect microstructure, including vacancy-type SFT, voids, and dislocation loops. Individual samples within each set were given one annealing exposure at 300, 350, 400, 450, 500, or 550 degrees C for 2 hours. The fine-scale defect microstructure was characterized by transmission electron microscopy (TEM) to compare the defect size and spatial distribution at each annealing temperature and reference the results to that measured in the as-irradiated condition. Based on the change in the SFT size distributions, post-irradiation annealing led to a preferential removal of the smaller sized SFT, but did not lead to a general coarsening as might be expected from an Oswald ripening scenario. The issue of whether the SFT produced during irradiation are all structurally perfect is still being investigated at the time of this report, however, the images of the SFT appeared more perfect after annealing at 300 degrees C and higher. Further analysis is being performed to determine whether intermediate stages of SFT formation exist in the as-irradiated condition.

  9. Therapy of infections in mice irradiated in mixed neutron/photon fields and inflicted with wound trauma: A review of current work. (Reannouncement with new availability information)

    SciTech Connect

    Ledney, G.D.; Madonna, G.S.; Elliott, T.B.; Moore, M.M.; Jackson, W.E.

    1991-12-31

    When host antimicrobial defenses are severely compromised by radiation or trauma in conjunction with radiation, death from sepsis results. To evaluate therapies for sepsis in radiation casualties, the authors developed models of acquired and induced bacterial infections in irradiated and irradiated-wounded mice. Animals were exposed to either a mixed radiation field of equal proportions of neutrons and gamma rays (n/gamma = 1) from a TRIGA reactor or pure gamma rays from 60 (Co sources). Skin wounds (15% of total body surface area) were inflicted under methoxyflurane anesthesia 1 h after irradiation. In all mice, wounding after irradiation decreased resistance to infection. Treatments with the immunomodulator synthetic trehalose dicorynomycolate (S-TDCM) before or after mixed neutron-gamma irradiation or gamma irradiation increased survival. Therapy with S-TDCM for mice irradiated with either a mixed field or gamma rays increased resistance to Klebsiella pneumoniae-induced infections.

  10. Effect of neutron irradiation on mechanical properties of Cu/SS joints after single and multiple HIP cycles

    NASA Astrophysics Data System (ADS)

    Tähtinen, S.; Singh, B. N.; Toft, P.

    2000-12-01

    The present design of the ITER plasma facing components consists of a copper alloy heat sink layer between plasma facing materials and stainless steel structure. The main option for manufacturing these components is hot isostatic pressing (HIP) method and several HIP thermal cycles are foreseen for manufacturing of the complete blanket module. Mechanical characterisation of HIP joints between dissimilar metals is a complicated issue, where information on mechanical properties of base alloys, metallurgy of the HIP joints and mechanical testing methods will be required. The tensile and three point bend tests produced different fracture modes, depending on test temperature, applied HIP thermal cycles and neutron irradiation. The fracture mode was either ductile fracture of copper alloy or joint interface fracture. The mechanical properties of the HIP joint specimens were dominated by strength mismatch of the base alloys which was affected by HIP thermal cycles and neutron irradiation.

  11. Clinical potential of boron neutron capture therapy for locally recurrent inoperable previously irradiated head and neck cancer.

    PubMed

    Lim, Diana; Quah, Daniel S C; Leech, Michelle; Marignol, Laure

    2015-12-01

    This review compares the safety and efficacy of boron neutron capture therapy (BNCT) in the treatment of previously irradiated, inoperable locoregional recurrent HNC patients and compares BNCT against the standard treatment of platinum-based chemotherapy. Our analysis of published clinical trials highlights efficacy of BNCT associated with mild side effects. However, the use of BNCT should be explored in stratified randomised trials. PMID:26277052

  12. Reconstitution and Upgrade of the Thermal Neutron Irradiation Facility in the Basement Medical Room of the MIT Research Reactor

    SciTech Connect

    Harling, Otto, K.; Riley, Kent, J.; Binns, Peter J.

    2004-12-31

    The M-011 thermal neutron beam has been reconstituted and upgraded to provide a high intensity and high quality facility for preclinical and certain clinical studies. Intensities of thermal neutrons in the beam range from 5.0-8.5 x 109 n cm-2 s-1. Beam contamination is at a low level where it has no practical influence on beam performance. New computer controlled dose and beam monitoring systems have been implemented which assure precise dose delivery and redundant safety interlocks. An additional beam shutter and massive shielding in the back of the medical room have been added which significantly reduce room background and now permit staff entry without the necessity for lowering the reactor power. This system is needed for BNCT research by the MIT group as well as other US groups. This need became acute with the closure of the BMRR which previously had the only high quality thermal neutron irradiation facility for BNCT in the USA.

  13. Effect of neutron irradiation on the microstructure of the stainless steel electroslag weld overlay cladding of nuclear reactor pressure vessels

    NASA Astrophysics Data System (ADS)

    Takeuchi, T.; Kakubo, Y.; Matsukawa, Y.; Nozawa, Y.; Nagai, Y.; Nishiyama, Y.; Katsuyama, J.; Onizawa, K.; Suzuki, M.

    2013-11-01

    Microstructural changes in the stainless steel weld overlay cladding of reactor pressure vessels subjected to neutron irradiation with a fluence of 7.2 × 1023 n m-2 (E > 1 MeV) and a flux of 1.1 × 1017 n m-2 s-1 at 290 °C were investigated by atom probe tomography. The results showed a difference in the microstructural changes that result from neutron irradiation and thermal aging. Neutron irradiation resulted in the slight progression of Cr spinodal decomposition and an increase in the fluctuation of the Si, Ni, and Mn concentrations in the ferrite phases, with formation of γ‧-like clusters in the austenite phases. On the other hand, thermal aging resulted in the considerable progression of the Cr spinodal decomposition, formation of G-phases, and a decrease in the Si and an increase in the Ni and Mn concentration fluctuations at the matrix in the ferrite phases, without the microstructural changes in the austenite phases.

  14. Effect of irradiation with reactor neutrons and the temperature of subsequent heat treatment on the structure of InP single crystals

    SciTech Connect

    Boiko, V. M.; Bublik, V. T.; Voronova, M. I.; Kolin, N. G. Merkurisov, D. I.; Shcherbatchev, K. D.

    2006-06-15

    The results of studying the features of the effect of irradiation with fast and full-spectrum reactor neutrons and subsequent heat treatments on the structural characteristics of InP single crystals are reported. It is shown that, in contrast to other III-V semiconductor compounds, the lattice constant decreases in InP as a result of irradiation with neutrons. Fast neutrons make the major contribution to the variation in the lattice constant. The presence of the component of thermal neutrons that give rise to Sn atoms in the material does not bring about any appreciable variation in the lattice constant. Heat treatment of irradiated samples at temperatures as high as 600 deg. C leads to annealing of radiation defects and recovery of the lattice constant; in the samples irradiated with high neutron fluences, the lattice constant becomes even larger than that before irradiation. An analysis of the obtained experimental data made it possible to assume that the decrease in the InP lattice constant as a result of irradiation with neutrons is mainly caused by the introduction of the P{sub In} antisite defects that give rise to an effect similar to that of vacancy-related defects.

  15. Thermal stability and kinetics of defects in magnesium aluminate spinel irradiated with fast neutrons

    NASA Astrophysics Data System (ADS)

    Yasuda, Kazuhiro; Kinoshita, Chiken; Fukuda, Korehisa; Garner, Frank A.

    2000-12-01

    Thermal stability of interstitial-type dislocation loops and cavities in single crystals of MgAl 2O 4 was examined during isochronal and isothermal annealing. The specimens were irradiated with fast-neutrons in FFTF/MOTA at 658 and 1023 K up to 249 dpa. During the isochronal annealing, dislocation loops started to shrink around 1000 K and completely disappeared at 1470 K without changing their character. Cavities grew slightly around 1570 K, and above this temperature, cavities shrunk with increasing annealing temperature. The recovery stage of point defects in MgAl 2O 4 was discussed in terms of the thermal stability of defect clusters; vacancy migration starts around 1000 K (corresponding to stage III), whereas vacancy clusters start to dissociate around 1570 K (corresponding to stage V). The vacancy migration energy for rate controlling species was estimated from the shrinkage process of interstitial-type dislocation loops to be 2.0 ± 0.7 eV.

  16. A target station for plasma exposure of neutron irradiated fusion material samples to reactor relevant conditions

    NASA Astrophysics Data System (ADS)

    Rapp, Juergen; Giuliano, Dominic; Ellis, Ronald; Howard, Richard; Lore, Jeremy; Lumsdaine, Arnold; Lessard, Timothy; McGinnis, William; Meitner, Steven; Owen, Larry; Varma, Venugopal

    2015-11-01

    The Material Plasma Exposure eXperiment (MPEX) is a device planned to address scientific and technological gaps for the development of viable plasma facing components for fusion reactor conditions (FNSF, DEMO). It will have to address the relevant plasma conditions in a reactor divertor (electron density, electron temperature, ion fluxes) and it needs to be able to expose a-priori neutron irradiated samples. A pre design of a target station able to handle activated materials will be presented. This includes detailed MCNP as well as SCALE and MAVRIC calculations for all potential plasma-facing materials to estimate dose rates. Details on the remote handling schemes for the material samples will be presented. 2 point modeling of the linear plasma transport has been used to scope out the parameter range of the anticipated power fluxes to the target. This has been used to design the cooling capability of the target. The operational conditions of surface temperatures, plasma conditions, and oblique angle of incidence of magnetic field to target surface will be discussed. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  17. Production of Samples of Individual Radioxenon Isotopes Through Neutron Irradiation of Stable Xenon Gas

    SciTech Connect

    Haas, Derek A.; Biegalski, Steven R.; Foltz Biegalski, Kendra M.

    2008-09-23

    The Spectral Deconvolution Analysis Tool (SDAT) software was developed to improve counting statistics and detection limits for nuclear explosion radionuclide measurements. SDAT utilizes spectral deconvolution spectroscopy techniques and can analyze both β-γ coincidence spectra for radioxenon isotopes and high-resolution HPGe spectra from aerosol monitors. The deconvolution algorithm of the SDAT requires a library of β-γ coincidence spectra of individual radioxenon isotopes to determine isotopic ratios in a sample. In order to get experimentally produced spectra of the individual isotopes we have irradiated enriched samples of 130Xe, 132Xe, and 134Xe gas with a neutron beam from the TRIGA reactor at The University of Texas. The samples produced were counted in an Automated Radioxenon Sampler/Analyzer (ARSA) style β-γ coincidence detector. The spectra produced show that this method of radioxenon production yields samples with very high purity of the individual isotopes for 131mXe and 135Xe and a sample with a substantial 133mXe to 133Xe ratio.

  18. Kinetics that govern the release of tritium from neutron-irradiated lithium oxide

    SciTech Connect

    Bertone, P.C.

    1986-01-01

    The Lithium Blanket Module (LBM) program being conducted at the Princeton Plasma Physics Laboratory requires that tritium concentrations as low as 0.1 nCi/g, bred in both LBM lithium oxide pellets and gram-size lithium samples, be measured with an uncertainty not exceeding +/-6%. This thesis reports two satisfactory methods of assaying LBM pellets and one satisfactory method of assaying lithium samples. Results of a fundamental kinetic investigation are also reported. The thermally driven release of tritium from neutron-irradiated lithium oxide pellets is studied between the temperatures of 300 and 400/sup 0/C. The observed release clearly obeys first-order kinetics, and the governing activation energy appears to be 28.4 kcal/mole. Finally, a model is presented that may explain the thermally driven release of tritium from a lithium oxide crystal and assemblies thereof. It predicts that under most circumstances the release is controlled by either the diffusion of a tritiated species through the crystal, or by the desorption of tritiated water from it.

  19. Distinguishing Pu Metal From Pu Oxide Using Fast Neutron Counting

    SciTech Connect

    Verbeke, J M; Chapline, G F; Nakae, L; Wurtz, R; Sheets, S

    2012-05-29

    We describe a method for simultaneously determining the {alpha}-ratio and k{sub eff} for fissile materials using fast neutrons. Our method is a generalization of the Hage-Cifarrelli method for determining k{sub eff} for fissile assemblies which utilizes the shape of the fast neutron spectrum. In this talk we illustrate the method using Monte Carlo simulations of the fast neutrons generated in PuO{sub 2} to calculate the fast neutron spectrum and Feynman correlations.

  20. Mixed-Field Dosimetry of a Fast Neutron Beam at the Portuguese Research Reactor for the Irradiation of Electronic Circuits - Measurements and Calculations

    NASA Astrophysics Data System (ADS)

    Fernandes, A. C.; Gonçalves, I. C.; Marques, J. G.; Santos, J.; Ramalho, A. J. G.; Osvay, M.

    2003-06-01

    The neutron and photon fields present at the Fast Neutron Beam of RPI were simulated with MCNP-4C and measured with activation foils, TLDs and ionisation chambers. In general, there is a good agreement between calculations and measurements, although the model overestimates the thermal neutron component. Aluminum oxide TLDs were found to be promising for monitoring the photon dose in actual irradiations of circuits.

  1. Radiation-induced strengthening in EB welds of Mo-Re alloys during high temperature neutron irradiation

    NASA Astrophysics Data System (ADS)

    Morito, F.; Chakin, V. P.; Danylenko, M. I.; Krajnikov, A. V.

    2011-10-01

    Mo-Re alloys have been known as excellent construction materials with good thermal stability and resistivity for chemical corrosion. These alloys may be fabricated into equipments for various chemical plants and new energy facilities such as fusion reactor. Accordingly it is interesting to elucidate the weldability and radiation performance of Mo-Re alloys in the actual constructions. In this study Mo-Re welds with 16-50% Re exhibited a large radiation-induced strengthening and embrittlement by irradiation at ˜1073 K to ˜5 × 10 21 cm -2 ( E > 0.1 MeV). High temperature neutron irradiation leads to intensive homogeneous nucleation of Re-rich σ-phases in all studied Mo-Re alloys that equalizes the difference in mechanical properties between melting zone, heat-affected zone and base metal. As a result, all parts of as-irradiated welds displayed approximately same level of strength. Therefore, the application of EB welding in Mo-Re constructions operating under high temperature neutron irradiation does not limit lifetime of such constructions.

  2. Characterization of neutron-irradiated ferritic model alloys and a RPV steel from combined APT, SANS, TEM and PAS analyses

    NASA Astrophysics Data System (ADS)

    Meslin, E.; Lambrecht, M.; Hernández-Mayoral, M.; Bergner, F.; Malerba, L.; Pareige, P.; Radiguet, B.; Barbu, A.; Gómez-Briceño, D.; Ulbricht, A.; Almazouzi, A.

    2010-11-01

    Understanding the behavior of reactor pressure vessel (RPV) steels under irradiation is a mandatory task that has to be elucidated in order to be able to operate safely a nuclear power plant or to extend its lifetime. To build up predictive tools, a substantial experimental data base is needed at the nanometre scale to extract quantitative information on neutron-irradiated materials and to validate the theoretical models. To reach this experimental goal, ferritic model alloys and French RPV steel were neutron irradiated in a test reactor at an irradiation flux of 9 × 10 17 nm -2 s, doses from 0.18 to 1.3 × 10 24 nm -2 and 300 °C. The main goal of this paper is to report the characterization of the radiation-induced microstructural change in the materials by using the state-of-the-art of characterization techniques available in Europe at the nanometre scale. Possibilities, limitations and complementarities of the techniques to each other are highlighted.

  3. Microstructure of V-4Cr-4Ti alloy after low-temperature irradiation by ions and neutrons.

    SciTech Connect

    Gazda, J.

    1998-04-01

    Recent interest in the application of a V-4Cr-4Ti alloy in the ITER prompted an investigation of the effects of low-to-moderate temperature irradiation (<420 C) on the alloy's mechanical properties. Two sets of experiments were conducted. The effects of fast neutron irradiation to {approx_equal}4 dpa at 390 C were investigated in the X530 experiment in the EBR-II reactor. Irradiation with single (4.5-MeV Ni{sup 2}) and dual ion beams (350-keV He{sup +} simultaneously with 4.5-MeV Ni{sup 2}) complemented this study. TEM observations showed the formation of a high density of point-defect clusters and dislocation loops (<30 nm diameter) distributed uniformly in both types of specimens. Mechanical property testing of neutron irradiated material showed embrittlement of the alloy. The deformed microstructure were examined by TEM to determine the causes of embrittlement and revealed dislocation channels propagating through the undeformed matrix. The channels are the sole slip paths and they cause early onset of necking and loss of work-hardening. Based on a review of the available literature, suggestions are made for further research of slip localization in V-4Cr-4Ti alloys.

  4. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    DOE PAGESBeta

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wallace D; Snead, Lance Lewis

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating themore » irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.« less

  5. Technologies for Fissile Material Detection and Prevention of Fissile Material Introduction into International Shipping

    SciTech Connect

    Richardson, J

    2003-07-01

    Prevention of the introduction of fissile materials into international shipping, and hence into a given country, is a complex problem. Some pieces of the solution to the puzzle are conceptually well defined, but lack definition of a technical pathway and/or operational implementation. Other elements are a little more fuzzy, and some elements are probably undefined at this point in time. This paper reviews the status of the more well-defined elements, and suggests needed additional measures to enhance the probability that fissile materials are not illicitly introduced into distant countries. International commerce proceeds through a number of steps from point of origin to final destination. Each step offers the possibility of a well-defined choke point to monitor and interdict the illicit shipment of fissile materials. However, because there are so many potential points and venues of entry into a large country such as the United States (e.g., air cargo, shipping containers, truck and rail transport, private vehicles, boats and planes, commercial passenger travel), it behooves the world to ensure that fissile material does not illicitly leave its point of origin.

  6. Recovery of fissile materials from nuclear wastes

    SciTech Connect

    Forsberg, Charles W.

    1997-12-01

    A process is described for recovering fissile materials such as uranium, and plutonium, and rare earth elements, from complex waste feed material, and converting the remaining wastes into a waste glass suitable for storage or disposal. The waste feed is mixed with a dissolution glass formed of lead oxide and boron oxide resulting in oxidation, dehalogenation, and dissolution of metal oxides. Carbon is added to remove lead oxide, and a boron oxide fusion melt is produced. The fusion melt is essentially devoid of organic materials and halogens, and is easily and rapidly dissolved in nitric acid. After dissolution, uranium, plutonium, and rare earth elements are separated from the acid and recovered by processes such as PUREX or ion exchange. The remaining acid waste stream is vitrified to produce a waste glass suitable for storage or disposal. Potential waste feed materials include plutonium scrap and residue, miscellaneous spent nuclear fuel, and uranium fissile wastes. The initial feed materials may contain mixtures of metals, ceramics, amorphous solids, halides, organic material and other carbon-containing material.

  7. Recovery of fissile materials from nuclear wastes

    DOEpatents

    Forsberg, Charles W.

    1999-01-01

    A process for recovering fissile materials such as uranium, and plutonium, and rare earth elements, from complex waste feed material, and converting the remaining wastes into a waste glass suitable for storage or disposal. The waste feed is mixed with a dissolution glass formed of lead oxide and boron oxide resulting in oxidation, dehalogenation, and dissolution of metal oxides. Carbon is added to remove lead oxide, and a boron oxide fusion melt is produced. The fusion melt is essentially devoid of organic materials and halogens, and is easily and rapidly dissolved in nitric acid. After dissolution, uranium, plutonium and rare earth elements are separated from the acid and recovered by processes such as PUREX or ion exchange. The remaining acid waste stream is vitrified to produce a waste glass suitable for storage or disposal. Potential waste feed materials include plutonium scrap and residue, miscellaneous spent nuclear fuel, and uranium fissile wastes. The initial feed materials may contain mixtures of metals, ceramics, amorphous solids, halides, organic material and other carbon-containing material.

  8. Fissile solubility and monosodium titanate loading tests

    SciTech Connect

    Hobbs, D.T.; Fleischman, S.D.

    1993-02-12

    The solubilities of plutonium and uranium have been determined for alkaline salt solutions having compositions which bound those which will be processed in the In-Tank Precipitation (ITP) process. Loadings of plutonium and uranium onto monosodium titanate (MST) have been determined at temperatures bounding those expected to occur during ITP and using a salt solution which was determined to have the maximum solubility for uranium and plutonium. Fissile loadings increase with decreasing amounts of MST in contact with the salt solutions saturated in plutonium and uranium. At MST concentrations bounding those which are planned for the ITP process, expressions for the maximum loadings (wt %) are determined to be 0.29 - 0.20x[MST] for plutonium and 1.8 - 0.29x[MST] for uranium, where [MST] is the concentration of MST in grams/liter. These expressions are valid over the range of MST concentrations from 0.05 to 0.51 g/L and temperatures of 17{degrees}--74{degrees}C. These loadings are below the individual infinitely safe limits for plutonium and uranium. Additional confirmatory experiments are planned to verify the effects of temperature and multiple contacts of the MST with fresh salt solution on the fissile loadings.

  9. Fissile solubility and monosodium titanate loading tests

    SciTech Connect

    Hobbs, D.T.; Fleischman, S.D.

    1993-02-12

    The solubilities of plutonium and uranium have been determined for alkaline salt solutions having compositions which bound those which will be processed in the In-Tank Precipitation (ITP) process. Loadings of plutonium and uranium onto monosodium titanate (MST) have been determined at temperatures bounding those expected to occur during ITP and using a salt solution which was determined to have the maximum solubility for uranium and plutonium. Fissile loadings increase with decreasing amounts of MST in contact with the salt solutions saturated in plutonium and uranium. At MST concentrations bounding those which are planned for the ITP process, expressions for the maximum loadings (wt %) are determined to be 0.29 - 0.20x[MST] for plutonium and 1.8 - 0.29x[MST] for uranium, where [MST] is the concentration of MST in grams/liter. These expressions are valid over the range of MST concentrations from 0.05 to 0.51 g/L and temperatures of 17[degrees]--74[degrees]C. These loadings are below the individual infinitely safe limits for plutonium and uranium. Additional confirmatory experiments are planned to verify the effects of temperature and multiple contacts of the MST with fresh salt solution on the fissile loadings.

  10. Radiation cataractogenesis induced by neutron or gamma irradiation in the rat lens is reduced by vitamin E

    SciTech Connect

    Ross, W.M.; Creighton, M.O.; Trevithick, J.R. )

    1990-09-01

    Although cataract of the eye lens is a known late effect of ionizing radiation exposure, most of the experimental work to date has concentrated on single, acute high doses or multiple, fractionated, chronic exposures. Many papers have dealt with biochemical alterations in metabolism and cellular components, with microscopic and electron microscopic lesions to the epithelial and cortical layers, and with clinical cataract formation. However, the minimum cataractogenic dose for rats has for many years been considered to be about 2 Gy for a single, acute dose of low LET radiation. Our purpose in designing this pilot study was three fold: firstly, to determine whether any physical damage could be detected after low, acute exposure to neutron radiation (10 and 100 cGy); secondly, to compare the relative effectiveness of fast (14 MeV) neutrons with gamma-rays; and thirdly, to investigate the possibility that vitamin E could protect the lenses from radiation damage. The results revealed that morphological damage was already discernible within minutes after exposure to neutrons or gamma-rays, that it became greater after 24 hours, that neutrons were more damaging than gamma-rays, and that vitamin E could effectively reduce the cataractogenic damage induced by ionizing radiation. Control, non-irradiated lenses with or without vitamin E, either in vivo or in vitro, showed no damage. Also, it appeared that in vitro irradiation was more damaging to lenses than in vivo irradiation, so this culture technique may prove to be a sensitive tool for assessing early damage caused by ionizing radiation.

  11. Swelling, irradiation creep and growth of pure rhenium irradiated with fast neutrons at 1030-1330°C

    NASA Astrophysics Data System (ADS)

    Garner, F. A.; Toloczko, M. B.; Greenwood, L. R.; Eiholzer, C. R.; Paxton, M. M.; Puigh, R. J.

    2000-12-01

    This paper discusses the results of two series of experiments conducted on pure hcp rhenium in the EBR-II and FFTF fast reactors. In FFTF, density change data were derived from open tubes and solid rods irradiated at temperatures and fluences in the range of 1020-1250°C and 4.4-8.3×1022 n cm-2, respectively (E > 0.1 MeV). Both density change and diametral change data were obtained from pressurized tubes irradiated in EBR-II to ∼0.65 and ∼5.1×1022 n cm-2 at temperatures between 1030°C and 1330°C. Analysis of the data shows that four concurrent processes contribute to the radiation-induced strains observed in these experiments. These are void swelling, transmutation-induced densification via production of osmium, irradiation creep and irradiation growth.

  12. 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.

  13. Temperature Effects on the Mechanical Properties of Candidate SNS Target Container Materials after Proton and Neutron Irradiation

    SciTech Connect

    Byun, T.S.

    2001-11-09

    This report presents the tensile properties of EC316LN austenitic stainless steel and 9Cr-2WVTa ferritic/martensitic steel after 800 MeV proton and spallation neutron irradiation to doses in the range 0.54 to 2.53 dpa. Irradiation temperatures were in the range 30 to 100 C. Tensile testing was performed at room temperature (20 C) and 164 C to study the effects of test temperature on the tensile properties. Test materials displayed significant radiation-induced hardening and loss of ductility due to irradiation. The EC316LN stainless steel maintained notable strain-hardening capability after irradiation, while the 9Cr-2WVTa ferritic/martensitic steel posted negative strain hardening. In the EC316LN stainless steel, increasing the test temperature from 20 C to 164 C decreased the strength by 13 to 18% and the ductility by 8 to 36%. The tensile data for the EC316LN stainless steel irradiated in spallation conditions were in line with the values in a database for 316 stainless steels for doses up to 1 dpa irradiated in fission reactors at temperatures below 200 C. However, extra strengthening induced by helium and hydrogen contents is evident in some specimens irradiated to above about 1 dpa. The effect of test temperature for the 9Cr-2WVTa ferritic/martensitic steel was less significant than for the EC316LN stainless steel. In addition, strain-hardening behaviors were analyzed for EC316LN and 316L stainless steels. The strain-hardening rate of the 316 stainless steels was largely dependent on test temperature. It was estimated that the 316 stainless steels would retain more than 1% true stains to necking at 164 C after irradiation to 5 dpa. A calculation using reduction of area (RA) measurements and stress-strain data predicted positive strain hardening during plastic instability.

  14. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    NASA Astrophysics Data System (ADS)

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; Hoffman, Elizabeth N.; Kohse, Gordon; Sindelar, Robert L.; Barsoum, Michel W.

    2016-01-01

    Herein we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation - up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ± 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 × 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.

  15. Effects of thermal aging and neutron irradiation on the mechanical properties of three-wire stainless steel weld overlay cladding

    SciTech Connect

    Haggag, F.M.; Nanstad, R.K.

    1997-05-01

    Thermal aging of three-wire series-arc stainless steel weld overlay cladding at 288{degrees}C for 1605 h resulted in an appreciable decrease (16%) in the Charpy V-notch (CVN) upper-shelf energy (USE), but the effect on the 41-J transition temperature shift was very small (3{degrees}C). The combined effect of aging and neutron irradiation at 288{degrees}C to a fluence of 5 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV) was a 22% reduction in the USE and a 29{degrees}C shift in the 41-J transition temperature. The effect of thermal aging on tensile properties was very small. However, the combined effect of irradiation and aging was an increase in the yield strength (6 to 34% at test temperatures from 288 to {minus}125{degrees}C) but no apparent change in ultimate tensile strength or total elongation. Neutron irradiation reduced the initiation fracture toughness (J{sub Ic}) much more than did thermal aging alone. Irradiation slightly decreased the tearing modulus, but no reduction was caused by thermal aging alone. Other results from tensile, CVN, and fracture toughness specimens showed that the effects of thermal aging at 288 or 343{degrees}C for 20,000 h each were very small and similar to those at 288{degrees}C for 1605 h. The effects of long-term thermal exposure time (50,000 h and greater) at 288{degrees}C will be investigated as the specimens become available in 1996 and beyond.

  16. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    DOE PAGESBeta

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; Hoffman, Elizabeth N.; Kohse, Gordon; Sindelar, Robert L.; Barsoum, Michel W.

    2015-10-23

    Here, we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation – up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ±more » 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 x 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.« less

  17. Monte Carlo simulation of biological effects of boron neutron capture irradiation with d(14)+Be neutrons in vitro

    SciTech Connect

    Poeller, F.; Sauerwein, W.

    1995-04-01

    It was shown that radiation effects in tumor cells treated with fast neutrons may be increased by the neutron capture reaction {sup 10}B(n,{alpha}){sup 7}Li. The classic approach for macroscopic dosimetry in fast-neutron therapy cannot be applied to the dose in boron neutron capture therapy (BNCT). The effectiveness of BNCT in killing tumor cells depends on the number of {sup 10}B atoms delivered to the tumor, the subcellular distribution of {sup 10}B and the thermal neutron fluence at the site of the tumor. Monte Carlo calculations of the energy dispositions of short-range particles with high LET coming from {sup 10}B disintegrations were performed and compared to the observed biological effects. The simulation allows us to study the influence of the localization of intracellular {sup 10}B in the nucleus, cytoplasm, plasma membrane or extracellular space. The biological response function which describes the probability of the lethal effect produced by a single particle track through the cell nucleus was found by comparing the calculated microscopic dose distribution spectra for single events with the survival observed experimentally. Calculations for a human melanoma cell population treated as a monolayer in the presence or absence of boron with d(14)+Be neutrons will be demonstrated. Two different boron compounds enriched in {sup 10}B were investigated in this study: boric acid (H{sub 3}{sup 10}BO{sub 3}) and p-dihydroxyboryl phenylalanine (BPA). The study shows that a high fraction of BPA enters the cytoplasm while boric acid was found only in the extracellular space. The computer simulations indicate that BPA yields a higher potential effectiveness for inactivation of melanoma cells than boric acid. 52 refs., 9 figs., 3 tabs.

  18. SU-E-T-557: Measuring Neutron Activation of Cardiac Devices Irradiated During Proton Therapy Using Indium Foils

    SciTech Connect

    Avery, S; Christodouleas, J; Delaney, K; Diffenderfer, E; Brown, K

    2014-06-01

    Purpose: Measuring Neutron Activation of Cardiac devices Irradiated during Proton Therapy using Indium Foils Methods: The foils had dimensions of 25mm x 25mm x 1mm. After being activated, the foils were placed in a Canberra Industries well chamber utilizing a NaI(Tl) scintillation detector. The resulting gamma spectrum was acquired and analyzed using Genie 2000 spectroscopy software. One activation foil was placed over the upper, left chest of RANDO where a pacemaker would be. The rest of the foils were placed over the midline of the patient at different distances, providing a spatial distribution over the phantom. Using lasers and BBs to align the patient, 200 MU square fields were delivered to various treatment sites: the brain, the pancreas, and the prostate. Each field was shot at least a day apart, giving more than enough time for activity of the foil to decay (t1=2 = 54.12 min). Results: The net counts (minus background) of the three aforementioned peaks were used for our measurements. These counts were adjusted to account for detector efficiency, relative photon yields from decay, and the natural abundance of 115-In. The average neutron flux for the closed multi-leaf collimator irradiation was measured to be 1.62 x 106 - 0.18 x 106 cm2 s-1. An order of magnitude estimate of the flux for neutrons up to 1 keV from Diffenderfer et al. gives 3 x 106 cm2 s-1 which does agree on the order of magnitude. Conclusion: Lower energy neutrons have higher interaction cross-sections and are more likely to damage pacemakers. The thermal/slow neutron component may be enough to estimate the overall risk. The true test of the applicability of activation foils is whether or not measurements are capable of predicting cardiac device malfunction. For that, additional studies are needed to provide clinical evidence one way or the other.

  19. Neutron field measurements of the CRNA OB26 irradiator using a Bonner sphere spectrometer for radiation protection purposes.

    PubMed

    Mazrou, H; Allab, M

    2012-08-01

    The present work deals with the Bonner sphere spectrometer (BSS) measurements performed, to support the authors' Monte-Carlo calculations, to estimate accurately the main characteristics of the neutron field of the (241)Am-Be-based OB26 irradiator acquired for radiation protection purposes by the Nuclear Research Centre of Algiers. The measurements were performed at a reference irradiation position selected at 150 cm from the geometrical centre of the neutron source. The spectrometric system in use is based on a central spherical (3)He thermal neutron proportional counter. The response matrix of the present spectrometer has been taken to be similar to the original Physikalisch-Technische Bundesanstalt (PTB) (Braunschweig, Germany) BSS's response matrix, with a five bins per decade energy group structure, as there is no significant difference in the BSS's physical characteristics. Thereafter, the authors' BSS measurements were used together with MCNP5 results to unfold the neutron spectrum by means of MAXED and GRAVEL computer codes from the U.M.G. 3.3 package, developed at PTB. Besides, sensitivity analysis has been performed to test the consistency of the unfolding procedure. It reveals that no significant discrepancy was observed in the total neutron fluence and total ambient dose values following the perturbation of some pertinent unfolding parameters except for the case where a 10 bins energy structure was assumed for the guess spectrum. In this latter case, a 5 % difference was observed in the ambient dose equivalent compared with the reference case. Finally, a comparative study performed between different counting systems together with MCNP5 and predictive formulas results shows that they were globally satisfactory, highlighting thereby the relevance of the unfolding procedure and the reliability of the obtained results. PMID:22345213

  20. A comparative study of the neutron flux spectra in the MNSR irradiation sites for the HEU and LEU cores using the MCNP4C code.

    PubMed

    Dawahra, S; Khattab, K; Saba, G

    2015-10-01

    A comparative study for fuel conversion from the HEU to LEU in the Miniature Neutron Source Reactor (MNSR) has been performed in this paper using the MCNP4C code. The neutron energy and lethargy flux spectra in the first inner and outer irradiation sites of the MNSR reactor for the existing HEU fuel (UAl4-Al, 90% enriched) and the potential LEU fuels (U3Si2-Al, U3Si-Al, U9Mo-Al, 19.75% enriched and UO2, 12.6% enriched) were investigated using the MCNP4C code. The neutron energy flux spectra for each group was calculated by dividing the neutron flux by the width of each energy group. The neutron flux spectra per unit lethargy was calculated by multiplying the neutron energy flux spectra for each energy group by the average energy of each group. The thermal neutron flux was calculated by summing the neutron fluxes from 0.0 to 0.625 eV, the fast neutron flux was calculated by summing the neutron fluxes from 0.5 MeV to 10 MeV for the existing HEU and potential LEU fuels. Good agreements have been noticed between the flux spectra for the potential LEU fuels and the existing HEU fuels with maximum relative differences less than 10% and 8% in the inner and outer irradiation sites. PMID:26142805