A composite control rod for use in controlling a nuclear reactor is described. The control rod is of sandwich construction in which finned dowel pins are utilized to hold together sheets of the neutron absorbing material and nonabsorbing structural material thereby eliminating the need for being dependent on the absorbing ...

In this work thermal neutron self-shielding in aqueous bulk samples containing neutron absorbing materials is studied using bulk sample prompt gamma neutron activation analysis (BSPGNAA) with the MCNP code. The code was used to perform three dimensional simulations of a ...

One class of neutron spectrometers is devices that provide a measure of the neutron spectrum by using moderating and absorbing materials together with thermal-neutron detectors. Pacific Northwest National Laboratory has developed scintillating fibers that are sensitive to thermal neutrons. ...

A ''plastic-like'' supporting material impregnated with a neutron-absorbing agent that is suitable for ''lining'' the inner surfaces of fissile-material storage containers was fabricated. The material consists, by weight, of 50% food-grade borax, 25% coal tar, and 25% epoxy resin. It costs much less than ...

Elemental analyses have been performed on twenty samples taken from the moisture standards prepared to use in performing experimental calibrations of the surface neutron moisture measurement system. These standards consisted of mixtures of sand, hydrated alumina, and boron carbide. Elemental analyses were performed ...

Materials for neutron absorber, thermal shunt, and fill gas for use in the waste package were selected using a qualitative approach. For each component, selection criteria were identified; candidate materials were selected; and candidates were evaluated against these criteria. The neutron absorber materials ...

Siemens Power Corporation (SPC), in cooperation with the Electric Power Research Institute (EPRI), has developed the RackSaver neutron absorbing insert. The RackSaver insert can be installed onto spent nuclear fuel assemblies to replace deteriorating Boraflex neutron absorbing material installed in some spent-fuel ...

... Abstract : The criticality and distribution conditions of neutron ... thermal-neutron reactor with a system of absorbing ... circle in the core or radial reflector. ...

A small pulsed thermal neutron source has been designed based on results of the MCNP simulations of the thermalization of 14 MeV neutrons in a cluster-moderator which consists of small moderating cells decoupled by an absorber. Optimum dimensions of the single cell and of the whole cluster have been selected, considering the thermal ...

The approach to a problem on optimization of neutron-physical performances of nuclear reactor with the system of absorbers moving during the reactor period is described to improve the performances of the designed reactors and also to provide automatizatio...

Fast neutron radiotherapy (FNT) can be combined with boron neutron capture therapy (BNCT). The selective incremental absorbed dose in the target volume that is thus obtained may be sufficient to produce a significant improvement in tumor control probability in some cases. Potential applications include certain non-small-cell lung ...

The disclosure is directed to an apparatus and method for determining the content and distribution of a thermal neutron absorbing material within an object. Neutrons having an energy higher than thermal neutrons are generated and thermalized. The thermal neutrons are detected and counted. The ...

Burnable absorber usage for pressurized water reactor (PWR) reload cores continues to increase as utilities seek improved fuel efficiency and increased plant availability. Extended cycle lengths, increased fuel burnups, and reduced neutron leakage fuel management strategies have contributed to this trend. To help customers meet their core management ...

This thesis consists of three main parts. The first part is related to boron neutron capture therapy (BNCT), the second part to boron neutron capture synovectomy (BNCS), and the third part to the neutron generator development. A monoenergetic neutron beam simulation study is carried out to determine the most ...

The occurrence of normal tissue complications and probability of tumor control are steep functions of absorbed dose. Consequently the delivery of the dose to the patient should be performed with a precision better than +lt. slash-2% and an overall uncertainty less than +lt. slash-5%. The sequence of dosimetry procedures to deliver the ...

The occurrence of normal tissue complications and probability of tumor control are steep functions of absorbed dose. Consequently the delivery of the dose to the patient should be performed with a precision better than +/- 2% and an overall uncertainty less than +/- 5%. The sequence of dosimetry procedures to deliver the absorbed dose ...

... Title : Basic Research on Quantitative Neutron Radiography Using Neutron Absorbing Honeycomb Collimator,. Corporate Author : ...

Calculations have been made of the incident neutron and gamma-ray absorbed dose response as a function of energy in the mid-head position of a phantom model. The calculations were performed with the DOT discrete ordinates transport code in the adjoint mod...

As a follow-on study to the feasibility of neutron capture therapy (NCT) with {sup 235}U brachytherapy seeds, physical doses were calculated and measured for the radiation from a {sup 235}U foil in a lucite phantom which was irradiated at the epithermal neutron irradiation port of the Brookhaven Medical Research Reactor. In addition, cell survival ...

In this work, personal thermoluminescence dosimeter (TLD) cards type of GN-6770 (holder type 8806) from Harshaw were used for personal neutron dosimetry. The response of the dosimeters has been determined in terms of the personal absorbed dose and personal dose equivalent for different neutron energy components, based on the ...

The U.S. Department of Energy requires nuclear criticality control measures for storage of its highly enriched spent nuclear fuel. A new alloy based on the Ni-Cr-Mo alloy system with a gadolinium addition has been developed. Gadolinium has been chosen as the neutron absorption alloying element because of its high thermal neutron absorption cross section. ...

Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the alloy at specific ...

A historical survey of neutron dosimetry by thermoluminescence dosimeters (TLD) is given, and as the basic problems for neutron dosimetry, the energy response to neutrons, gamma-ray discrimination, performance in gamma neutron mixed fields, and sensitivity improvement are described. ...

Presently there are no standard protocols for dosimetry in neutron beams for boron neutron capture therapy (BNCT) treatments. Because of the high radiation intensity and of the presence at the same time of radiation components having different linear energy transfer and therefore different biological weighting factors, treatment planning in epithermal ...

An epithermal neutron filter using iron, aluminum, and sulfur was evaluated to determine if the therapeutic performance could be improved with respect to aluminum--sulfur-based filters. An empirically optimized filter was developed that delivered a 93% pure beam of 24-keV epithermal neutrons. It was expected that a thick filter using ...

A fully-absorbing neutron detector is being developed to measure the absolute flux (s-1) of a cold neutron beam at the level of 0.1,%. The device will be used to calibrate a neutron flux monitor used in an in-beam neutron lifetime measurement performed at NIST (?n= (886.3 ...

Recent studies show that subassemblies containing various spent fuels could be assayed rapidly and accurately by a nondestructive assay system using active neutron interrogation and prompt-neutron detection. Subassembly penetration is achieved by 24-keV (Sb--Be) interrogation neutrons; the spent-fuel neutron ...

Decay constant and modal analysis measurements were performed in a U/sup 235/-water critical assembly, and infinitemedium neutron spectra in water poisoned with a 1/V absorber were measured at various pressures and temperatures. The results were compared with theoretical predictions. Neutron penetration of ...

Table sugar samples were irradiated with accelerated carbon ions and fast neutrons. Electron paramagnetic resonance (EPR) analysis performed after the irradiation revealed a complex spectrum similar to that observed after gamma-ray irradiations. The total concentration of the paramagnetic centers induced by accelerated carbon ions and ...

This report describes the analysis and modeling approaches used in the evaluation for criticality-control applications of the neutron-absorbing structural-amorphous metal (SAM) coatings. The applications of boron-containing high-performance corrosion-resistant material (HPCRM)--amorphous metal as the neutron-absorbing coatings to the ...

The following measures of physical effects in a spherical cell nucleus, resulting from heavy charged particles caused by thermal neutron reactions in tissue, were evaluated by analytical calculation: (1) the absorbed energy in a cell nucleus, (2) the number of particles hitting and/or passing through a cell nucleus, (3) the integrated particle track length ...

Efficient initiation of large-volume chemical lasers may be achieved by neutron induced reactions which produce charged particles in the final state. When a burst mode nuclear reactor is used as the neutron source, both a sufficiently intense neutron flux and a sufficient short initiation pulse may be possible. Proof-of-principle ...

Efficient initiation of large-volume chemical lasers may be achieved by neutron induced reactions which produce charged particles in the final state. When a burst mode nuclear reactor is used as the neutron source, both a sufficiently intense neutron flux and a sufficiently short initiation pulse may be possible. Proof-of-principle ...

Efficient initiation of large-volume chemical lasers may be achieved by neutron induced reactions which produce charged particles in the final state. When a burst mode nuclear reactor is used as the neutron source, both a sufficiently intense neutron flux and a sufficient short initiation pulse may be possible. Proof-of-principle ...

Energy selective neutron radiography was performed to describe a complex structure in polycrystalline materials. Experiments were performed with currently the highest energy and spatial resolutions achieved simultaneously, by employing a double crystal monochromator for selecting narrow energy bands from the initially polychromatic ...

A pre-clinical characterization of the first fission converter based epithermal neutron beam (FCB) designed for boron neutron capture therapy (BNCT) has been performed. Calculated design parameters describing the physical performance of the aluminium and Teflon� filtered beam were confirmed from ...

The survival of Chinese hamster cells in culture was used as a test system to determine the RBE of neutrons over a wide energy range. The Radiological Research Accelerator Facility (RARAF) at Brookhaven National Laboratory was used for experiments involving nine neutron energies between 110 keV and 15 MeV; for all but the lowest energy the beams ...

Often neutrons are produced in nuclear reactors with high energies, but they are needed at low energies for uses like activation analysis and neutron capture therapy. The evaluation of the slowed down neutron amount by using the Monte Carlo method is very expensive in computation time and the variance is large for natural simulation. ...

A neutron-absorbant shield is described which consists of or contains one or more boric acid esters of monoaliphatic alcohols containing 9 carbon atoms or more. (R.J.S.)

A neutron range spectrometer and method for determining the neutron energy spectrum of a neutron emitting source are disclosed. Neutrons from the source are colliminated along a collimation axis and a position sensitive neutron counter is disposed in the path of the collimated ...

A description is given of the experimental measurement of the prompt- neutron lifetlme parameter of a SPERT watermoderated and reflected reactor using the l/v-absorber pertarbation technique. The l/ beta /sub eff/ result given by the experiment is compared with the dynamic value obtained from super prompt- critical power excursion experiments ...

A methodology has been recently developed for evaluation of doses absorbed by samples irradiated in research reactors, in which the partial doses due to thermal neutrons, epithermal neutrons, fast neutrons and gamma radiation are individually quantified. ...

An International Neutron Dosimetry Intercomparison (INDI) was carried out in 1973 at the Radiological Research Accelerator Facility (RRAF) of Brookhaven National Laboratory under the sponsorship of the International Commission on Radiation Units and Measurements (ICRU). Fourteen groups of scientists, from six countries, performed measurements to determine ...

Transmission measurements were performed using Maxwellian distributed neutrons from the R1 reactor perpendicularly incident upon a boral absorption plate. American, English, German, Swedish, and Swiss samples were investigated, and the results are compared to calculated values. The influence of the absorber grain size is ...

The Advanced Test Reactor (ATR) is a high power density and high neutron flux research reactor operating in the United States. Powered with highly enriched uranium (HEU), the ATR has a maximum thermal power rating of 250 MWth. Because of the large test vo...

... Meth- ods of fast neutron dosimetry based on blackening are ... and measuring the range of proton tracks in ... to the number of recoil protons times the ...

We report on a new solid state dosimeter based on chemical vapor deposition (CVD) single crystal diamond fabricated at Roma "Tor Vergata" University laboratories. The dosimeter has been specifically designed for direct neutron dose measurements in boron neutron capture therapy (BNCT). The response to thermal neutrons of the proposed ...

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 ...

This paper concerns the neutron attenuation behavior of boron-alloyed stainless steels, and quantitative estimations of secondary effects on the neutron transmission measurements, such as beam hardening, background and micro-structure of neutron absorber causing a decrease in the total macroscopic cross-sections. ...

Boron alloyed stainless-steel sheets are predominantly used in nuclear engineering as neutron shielding for radioactive waste disposal equipment. The neutron absorption depends strongly on the amount and the distribution of the 10B isotope. A systematic transmission study of 10B enriched steel plates by means of neutron time-of-flight ...

At Kyoto University Research Reactor Institute (KURRI), cyclotron-based epithermal neutron source was installed in December 2008, and the supplementary construction works have been performed. As of December 2010, the various irradiation characteristics important for BNCT were mostly evaluated. The whole body exposure during BNCT medical irradiation is one ...

The critical experiments reported provide data for the effect of a soluble neutron absorber (cadmium nitrate) on the criticality of high-enriched uranium nitrate solution. These data can be used in criticality control and for validation of calculational methods. The experiments were performed with cylindrical vessels of two different ...

A process is described for fabrication of neutron shielding from thermoplastic plastic with incorporated neutron absorber with a proportion of more than 5%, in which the plastic is applied in prefabricated form on the surface to be protected, characterize...

Water, whether liquid or frozen, absorbs neutrons more than other substances. The Detector of Albedo Neutrons on the Mars Science Laboratory rover will use ...

Methods of controlling reactors are presented. Specifically, a plurality of neutron absorber members are adjustably disposed in the reactor core at different distances from the center thereof. The absorber members extend into the core from opposite faces thereof and are operated by motive means coupled in a manner to ...

The ratio between the thermal and fast neutron flux in a BWR (Boiling Water Reactor) depends on the void fraction. The density of the steam-water mixture present in the core determines the efficiency of the moderation of fast neutrons born in fission, and therefore the void fraction could be determined by means of a simultaneous measurement of the thermal ...

We are developing cryogenic high-energy resolution fast-neutron spectrometers using superconducting transition-edge sensors (TES) for nuclear science and non-proliferation applications. Fast neutrons are absorbed in 94% enriched 6LiF single crystals with volumes of �1 cm3 in an exothermic 6Li(n,?)3H capture reaction. The ...

A variety of needs exists for knowing the energy spectral content of a neutron flux. Among these needs are arms-control and national-security applications, which arise because different neutron sources produce different neutron energy spectra. This work is primarily directed at these applications. The concept described herein is a ...

Measurements in nearly monoenergetic beams of 144, 24.5, and 2 keV neutrons and of thermal neutrons have been performed with low-pressure proportional counters. The suitability of a tissue-equivalent proportional counter (TEPC) for dosimetry of low-energy neutrons has been investigated. In contrast to higher ...

As a negative pion stops in tissue, it attaches itself to an adjacent atom to form a mesonic atom. Subsequently, the wave function of the pion interacts with that of the nucleus and the pion is absorbed. Because the energy associated with the rest mass of the pion is greater than the separation energy of the nuclear particles, the nucleus disintegrates (pion star). In tissue, ...

Values of the fast neutron absorbed dose rate in an ethylene absorber are given as a function of penetration distance in hydrogen. The dose rates were obtained by numerical integration of the product of the differential number spectrum and the ethylene conversion factors. (auth)

A neutron shielding material using a metathesis-polymer matrix, which is a thermosetting resin, was developed. This shielding material has characteristics that can be controlled for different mixing ratios of neutron absorbers and for formation in the laboratory. Additionally, the elastic modulus can be changed at the hardening ...

Neutron radiography was used for the investigation of the nuclear fuel and control rod cladding behaviour during steam oxidation under severe nuclear accident conditions. In order to verify the hypothesis that the unexpectedly high neutron cross-section found after oxidation of Zircaloy-4 in wet air containing 10% steam is caused by a strong hydrogen ...

Central axis depth dose (CADD) and off-axis absorbed dose ratio (OAR) measurements were made in water, muscle and whole skeletal bone TE-solutions, mineral oil and glycerin with a clinical neutron therapy beam. These measurements show that, for a given neutron beam quality and field size, there is a universal CADD distribution at ...

Lithium-based ceramics have been proposed as tritium breeders for fusion reactors. The lithium aluminate (gamma phase) seems to be thermally and structurally stable, the damages produced by neutron irradiation depend on the absorbed dose. A method based on the measurement of neutron activation of foils through ...

This patent relates to a reflector means for a neutronic reactor. A reflector comprised of a plurality of vertically movable beryllium control members is provided surrounding the sides of the reactor core. An absorber of fast neutrons comprised of natural uramum surrounds the reflector. An absorber of ...

Application of new absorbing materials which are the neutron spectrum detectors when determining the neutron gas temperature are examined. The method based on measurements of reactivity of absorbing samples has been chosen to measure the spectral characte...

Neutron therapy beams are obtained by accelerating protons or deuterons on Beryllium. These neutron therapy beams present comparable dosimetric characteristics as those for photon beams obtained with linear accelerators; for instance, the penetration of a p(65)+Be neutron beam is comparable with the penetration of an 8 MV photon beam. ...

The LR-0 experimental reactor facility to study the neutron physical features of WWER-1000 reactor cores at the NRI Rez was used to perform benchmark experiments on control absorber clusters. The benchmark experiments were performed in the standard LR-0 c...

A neutron absorber control rod for use in a fuel assembly of a nuclear reactor is described comprising: (a) an elongated hollow tubular member having opposite ends and a hermetically sealed chamber; (b) neutron absorber material pellets contained in the chamber and located nearer to the trailing than to the ...

Tissue-equivalent proportional counters (TEPC) allow the measurements of the absorbed dose and the ambient dose equivalent for neutron fields. A device based on this approach, called NAUSICAA((1,2)), has already been developed by IRSN to be used in high energy neutron fields for space applications. The response of this detector ...

A series of 62 critical and critical approach experiments were performed to evaluate a possible novel means of storing large volumes of fissile solution in a critically safe configuration. This study is intended to increase safety and economy through use of such a system in commercial plants which handle fissionable materials in liquid form. The fissile solution`s ...

Verification of the presence of neutron-absorbing materials in fuel storage racks and nuclear fuel process tanks is in many cases essential for criticality safety. Neutron counting techniques have been used previously for this purpose. Previous measurements with high-flux isotope reactor (HFIR) fuel elements using neutron noise ...

Low-pressure proportional counters (LPPCs) with walls made from the elements C, Mg, Al, Si, Fe and Zr and from the chemical compounds A-150 plastic, AlN, Al2O3, SiO2 and ZrO2 were used to measure neutron fluence-to-kerma conversion coefficients at energies up to 66 MeV. The LPPCs served to measure the absorbed dose deposited in the gas of a cavity ...

Spent nuclear fuel contains fissionable materials ({sup 235}U, {sup 239}Pu, {sup 241}Pu, etc.). Neutron multiplication and the potential for criticality are enhanced by the presence of a moderator during cask loading in water, water incursion in accidents conditions during spent fuel storage or transport. To prevent nuclear criticality in spent fuel storage, transportation, ...

A preconceptual design for an Accelerator Production of Tritium (APT) facility is currently under development by several national laboratories in conjunction with industry. The design consists of an accelerator that bombards a spallation target with high energy protons. Neutrons are produced in the spallation target and are absorbed in a blanket material ...

This paper describes the neutron tomography investigation on archaeological artifacts from museums in South Africa. While X-rays fail to penetrate the brass matrix of the samples, neutrons can easily reveal, on a non-invasive manner, the content and structure of these precious samples. The South African Neutron Radiography (SANRAD) ...

Neutron and Triton Production by 800 MeV Protons: The experiments presented in this report were performed in support of the Accelerator Production of Tritium (APT) project at the Los Alamos Weapons Neutron Research (WNR) facility in order to provide data to benchmark and validate physics simulations used in the APT target/blanket ...

A method to obtain the absorbed dose in Drosophila melanogaster irradiated in the thermal column facility of the Triga Mark III Reactor has been developed. The method is based on the measurements of neutron activation of gold foils produced by neutron capture to obtain the neutron fluxes. These fluxes, combined ...

A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with ...

... Accession Number : ADD854581. Title : The Effect of Absorbed Energy on the CAI Performance for Composite Materials. ...

Although neutron diffraction is a basic and relatively simple technique and should be available at a neutron source, it is not possible to perform neutron diffraction measurements at IRI at this moment. Until recently a neutron diffractometer with a relat...

The neutron absorbing material chosen for the absorber elements of the European fast reactor (EFR) is boron carbide. Various pin designs are studied in Europe: (1) vented helium-bonded pins chosen for prototype fast reactor (PFR) control rods, (2) vented sodium-bonded pins chosen for the Phenix and Superphenix control rods, (3) vented ...

Different materials and proton beam energies have been studied in order to search for an optimized neutron production target and beam shaping assembly for accelerator-based BNCT. The solution proposed in this work consists of successive stacks of Al, polytetrafluoroethylene, commercially known as Teflon, and LiF as moderator and neutron ...

A series of critical experiments was completed with an array of mixed oxide fuel pins surrounded by plutonium-uranium nitrate solutions. The objectives of these experiments are to provide criticality data for a heterogeneous system of fuel pins moderated with plutonium-uranium solutions, and to determine the effectiveness of soluble gadolinium as a neutron ...

A Monte Carlo simulation has been developed for neutron stimulated emission computed tomography (NSECT) using the GEANT4 toolkit. NSECT is a new approach to biomedical imaging that allows spectral analysis of the elements present within the sample. In NSECT, a beam of high-energy neutrons interrogates a sample and the nuclei in the sample are stimulated to ...

A portable tissue equivalent calorimeter has been constructed and employed to measure absorbed dose in a mixed fast-neutron and gamma-ray field. Design details and measurement techniques are described along with the limits of precision and absolute accuracy. Experiments have been carried out with a cyclotron produced neutron ...

Operation of the 242-16H High Level Waste Evaporator proves crucial to liquid waste management in the H-Area Tank Farm. Recent inspection of the evaporator showed significant formation of solids in secondary lines and in the evaporator pot. Tests completed at Savannah River Technology Center (SRTC) showed dilute nitric acid will dissolve the solids. Because the solids contain significant ...

A scoping corrosion test was performed on candidate waste package basket materials in order to assist in selecting materials for package design and to help in designing longer-term corrosion tests. The corrosion solution was buffered near pH4, was in contact with air, and contained chemical species expected to be produced by radiolysis. The test was conducted at 90 C for 96 ...

Neutron absorption cross sections for over 50 elements have been measured in the neutron flux of the Argonne heavy water reactor. Measurements were made by observing the oscillating component of reactor power as a neutron absorber sample was oscillated in and out of the central flux of the pile. Calibration was ...

The present invention relates to an upper neutron protection device for a nuclear reactor assembly. This device comprises at least one container partly filled with a neutron-absorbing product and maintained within a wall located in the upper part of the assembly by at least one spacing plate. Application to fast neutron reactors.

Fluence-to-dose conversion coefficients for the radiation protection quantity effective dose were calculated for neutrons, photons and protons with energies up to 2 GeV using the MCNPX code. The calculations were performed using the Pacific Northwest National Laboratory versions of the MIRD-V male and female anthropomorphic phantoms modified to include the ...

The design and performance of a trough-tray dissolver are described. In this design a number of troughs are combined into a single tray by placing them side by side in a horizortal plane and connecting them together. Each trough is sized to be geometrically safe for a heterogeneous 3% U/sup 235/ system and each trough is separated from the next by a moderator and ...

The PREMOR computer code was written to exploit a simple, two-group point nuclear reactor power plant model for survey analysis. Up to thirteen actinides, fourteen fission products, and one lumped absorber nuclide density are followed over a reactor history. Successive feed batches are accounted for with provision for from one to twenty batches resident. The effect of exposure ...

This is a control systemo with no mooving paris, performing the functions of shutdown and power control, and a moeans of adjusting flux distribution. It comprises tubes in the core filled with a neutron absorbing fiuid, formed of a variable mixture of two components. Fluid is supplied to the reactor tubes from a main ...

A series of experiments have been performed containing highly enriched uranium, hydrogenous moderator (polyethylene), and gadolinium as a neutron absorber. The purpose of the experiments is to provide additional criticality data that can be used to verify and validate criticality safety evaluations in support of the National Spent Fuel ...

A benchmark evaluation has been performed for a set of twenty-one critical experiments involving high enriched uranyl nitrate solution with and without cadmium nitrate as a soluble neutron absorber. The critical experiments analyzed include two types of c...

There is a continuing interest in the use of fixed neutron absorbers (poisons) for criticality control, since their use would permit safely handling larger quantities of nuclear materials with reduced probability of criticality. The effectiveness of such absorbers as neutron poisons depends on self-shielding ...

An investigation of three control element designs for sodium-graphite reactors is presented: the first design utilizes wire rope supporting a rod of neutron absorber material, permitting installation of the complete actuator in the upper end of a control rod thimble below the reactor loading face; the second concept uses overlapping fuel and ...

A perturbation theory expression has been developed to predict the incremental detector output realized when traces of neutron-absorbing elements are present during prompt fission neutron uranium logging. The most restrictive constraint on the validity of the theory is that changes in the neutron flux caused by the presence of ...

Essentially the dose-meter consists of a thin strip, or several strips, of a material absorbing thermal neutrons. Neutron bombardment provokes anisotropic expansion of the strip which bends toward the neutron source. Screens can be used to protect the other side of the strip when required. B and Li as well as B/sub ...

Amorphous metal and ceramic thermal spray coatings have been developed with excellent corrosion resistance and neutron absorption. These coatings, with further development, could be cost-effective options to enhance the corrosion resistance of drip shields and waste packages, and limit nuclear criticality in canisters for the transportation, aging, and disposal of spent ...

Spent nuclear fuel contains fissionable materials ({sup 235}U, {sup 239}Pu, {sup 241}Pu, etc.). To prevent nuclear criticality in spent fuel storage, transportation, and during disposal, neutron-absorbing materials (or neutron poisons, such as borated stainless steel, Boral{sup TM}, Metamic{sup TM}, Ni-Gd, and others) would have to be applied. The success ...

To assess the effect of ionization chamber wall thickness on absolute neutron absorbed dose determinations, measurements were made of the charge collected by an A-150 tissue-equivalent plastic ionization chamber irradiated by a p(66)Be(49) neutron therapy beam as a function of chamber wall thickness both in air and in four different ...

To assess the effect of ionization chamber wall thickness on absolute neutron absorbed dose determinations, measurements were made of the charge collected by an A-150 tissue-equivalent plastic ionization chamber irradiated by a p(66)Be(49) neutron therapy beam as a function of chamber wall thickness both in air and in four different ...

Line at the Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source (SNS.9 #23; A Neutron Line at the Fundamental Neutron Physics Beamline (FNPB) at the Spallation Neutron Source (SNS will be performed at the Fundamental Neutron ...

The reduction of thermal neutron density by an absorbing disc is calculated for both cases in which the disc is of large radius and in which the radius is comparable to the mean free path. (D.L.C.)

A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coatin...

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

Technique for measuring background by a double pulse slow neutron spectrometer is described. To measure the background on oscillating absorbing screen (OAS) periodically overlapping primary neutron beam at the input of a mechanical interrupter was used. D...

A bimetallic helix is described comprising a neutronflux-responsive strip and a second strip having the same coefficient of thermal expansion for adjusting the extent to which an inner neutron-absorbing member protrudes from an outer hollow neutron-absorbing member.

The monoenergetic steady-state integral neutron transport equation is solved analytically for several simple source configurations for pure absorbers. Specifically, the scalar neutron flux, phi(r), is derived for configurations in cartesian geometry repre...

Neutron imaging is a non-invasive method for material research on the macroscopic level. It is carried out at laboratories equipped with powerful neutron sources, suitable neutron beam lines and neutron detection systems. Decades ago neutron radiography began capturing images with film ...

A precise evaluation of the dosimetric performance of epithermal neutron beams designed for boron neutron capture theory of brain tumours requires the use of a phantom material that closely matches brain tissue. The aim of this study was to investigate how well polyacrylamide gel (or PAG) and A-150 plastic ...

Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy and chromium-nickel (Cr-Ni) stainless steel, modified by the addition of boron. The primary purpose of the experiments was to demonstrate the thermal ...

The standard method outlines a procedure for calculating the absorbed dose in a material given the material composition, the neutron fluence, and threshold-foil data related to the neutron spectrum. The method is applicable to fast-pulsed reactors of the Godiva or TRIGA type, where a substantial fraction of the ...

... AS INDICATORS OF ABSORBED RADIATION DOSE IN RATS. ... of doses of mixed gamma-neutron radiations or 14 ... was a function of dose over the ...

Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a ...

A method for the approximate calculation of the neutron physical lifetime of absorber materials with several absorbing nuclides was developed, and the lifetimes of various materials were determined as a function of the layer thickness. A crude economic comparison gives a survey on the favorable introduction range for various ...

The standard HEU fuel cycle characteristics are compared with those of several different LEU fuel cycles in the new vessel configuration. The primary design goals were to provide similar reactivity performance and neutron flux profiles with a minimal increase in /sup 235/U loading. The fuel cycle advantages of Cd burnable absorbers ...

We describe the fabrication techniques of novel, compact optical elements for collimating and/or focusing beams of X- rays or thermal neutrons. These optical elements are solid composite arrays consisting of regular stacks of alternating micro-foils, analogous in action to Soller slit collimators, but up to three orders of magnitude smaller. The arrays are made of alternating ...

A reactor shielding of the multilayer type is designed which can be used at high temperatures where separation of boron and bitumen mixtures is likely to occur. The shielding comprhses a gamma absorbent layer nearest the source of radiation, a thermal neutron absorbent layer, a fast neutron ...

Boron of 10 atomic weight is one of the best neutron absorbing elements. Among the boron compounds, B(sub 4)C and its composites exhibit excellent material properties. Those materials absorb thermal and fast neutrons, are thermally and chemically very sta...

A neutron absorbing composition is described and consists of a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a ...

A neutron absorbing composition comprises a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysilioxane polymer of a boron compound or ...

A neutron absorbing composition comprising a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or ...

The main detectors used for clinical dosimetry are ionisation chambers and semiconductors. Thermoluminescent (TL) dosimeters are also of interest because of their following advantages: (i)wide useful dose range, (ii)small physical size, (iii)no need for high voltage or cables, i.e. stand alone character, and (iv)tissue equivalence (LiF) for most radiation types. TL detectors can particularly be ...

The neutron absorber described contains a spinel type of mixed oxide having the formula Me (II)/sub 2/O/sub 4/, where Me (I) stands for zirconium and Me(I) for cadmium, or Me(I) for cadmium and Me(II) for aluminum. The absorber also consists of a mixed oxide made from a mixture of mixed oxides with a ceramic substance of low ...

The pulsed neutron problem is studied in small but finite sized assemblies of liquid water and heavy water poisoned with such non-1/v neutron absorbers as samarium, cadmium, and gadolinium. It is found that the asymptotic neutron density is markedly dependent on the nature of the non-1/v ...

The key elements of the Muon Ionization Cooling Experiment (MICE) cooling channel are the absorbers that are a part of the MICE absorber focus coil modules (AFC modules). The boundaries of room temperature solid absorbers are well defined. The density of most solid absorber materials is also well understood. The ...

the absorber. A classical estimation for the distance #l between two subsequent collisions of a neutron false effects in the transmission measurement. The excess of neutrons in the measurement that, sizeable diffraction effects would depend strongly on the neutron wavelength, which is defined

Apparatus and method for producing synthetic fuels and synthetic fuel components by using a neutron source as the energy source, such as a fusion reactor. Neutron absorbers are disposed inside a reaction pipe and are heated by capturing neutrons from the ...

A black plate with zero thickness, finite width and infinite height, imbedded in an infinite and homogeneous medium which scatters and absorbs neutrons, is considered. The problem is time-independent and the neutrons, which are supposed to have a unique s...

A spherical proportional detector was developed and used in a study of the pulse-height spectra and resultant dose distributions for monoenergetic neutrons as a function of neutron energy and sample size. Results of the measurements are presented graphically and discussed. (C.H.)

Applicant's present invention is a composite scintillator for neutron detection comprising a matrix material fabricated from an inorganic sol-gel precursor solution homogeneously doped with a liquid scintillating material and a neutron absorbing material....

ABS>The thermalization of neutrons in a moderating material is viewed as a Markov process in which there is one absorbing state and the energies are the transient states. The state populations are the neutron densities. By replacing the continuum of thermal energies with a set of energy intervals, the process is reduced to ...

A facility for the irradiation of a section of patients' explanted liver and lung was constructed at RA-3 reactor, Comisi�n Nacional de Energ�a At�mica, Argentina. The facility, located in the thermal column, is characterized by the possibility to insert and extract samples without the need to shutdown the reactor. In order to reach the best levels of security and efficacy of the treatment, ...

This invention is a switchable neutron generating apparatus comprised of a pair of plates, the first plate having an alpha emitter section on it and the second plate having a target material portion on it which generates neutrons when its nuclei absorb an alpha particle. In operation, the alpha portion of the first plate is aligned ...

A nuclear reactor includes an active portion with fissionable fuel and neutron moderating material surrounded by neutron reflecting material. A control element in the active portion includes a group of movable rods constructed of neutron-absorbing material. Each rod is movable with respect to the other rods to vary the absorption of ...