摘要:

Two in-pile transient experiments were performed in the TREAT Reactor Facility to investigate fuel-coolant interaction phenomena that might occur in a hypothetical prompt-burst disassembly accident involving extensive fuel vaporization in a nearly unvoided liquid-metal fast breeder reactor core. In these tests, a single fuel pin containing 28 g of UO2was subjected to a self-limited 23-msec-period TREAT power excursion which deposited fission energy of 1700 cal/g of UO2in the fuel. The pin was contained in an instrumented autoclave filled with stagnant sodium. Failure of the fuel pins occurred at a mean energy input of about 540 cal/g, corresponding to a UO2vapor pressure of about 100 atm. Results of these tests indicated that no energetic fuel-coolant interaction was produced and that the measured transient pressures can be reasonably described by the time history of the fuel vapor pressure.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26737

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

Samples of235U,233U,239Pu, and232Th have been irradiated in high neutron fluxes [>1014n/ (cm2sec)] and their decay heat has been measured as a function of cooling time ranging from 14 to 4500 h after removal from the high flux. To measure the rate of heat emission, an underwater calorimeter has been developed. For the measured exposure histories, decay heat has also been calculated for concentrations of 190 fission products, all significant heavy isotopes, and structural nuclides. Account is taken of the energy carried by gamma rays that escape the calorimeter. Measurements and calculations of the decay heat captured within the calorimeter agree within two standard deviations for all samples and cooling times and, in general, agree within 2%. For the235U sample, calculations based on the Proposed ANS Standard ANS-5.1 (ANSI N18.6) agree with the measurements within a few percent.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26738

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

Gamma-ray buildup factors in ordinary concrete have been calculated by the moments method. Results for concrete kerma and air kerma are tabulated for source energies from 15 MeV to 15 keV. Parameters are given that allow calculation of the buildup factor by means of a simple analytic expression. Comparisons are made with earlier calculations, and the effects of annihilation radiation are discussed.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26739

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

The spatial distribution of the neutron importance in bare and natural-uranium-reflected uranium (∼93.2 wt%235U) and plutonium (∼4.7 at %240Pu) metal spheres was measured using252Cf neutron sources. The spatial distribution of the fission density from activation measurements in the bare spheres and those previously measured for the reflected spheres are presented.Comparison of these distributions with those from S16transport theory calculations showed that the measured and calculated results agreed very well for the bare spheres and in the central core of the reflected spheres. The disagreement in the natural uranium reflector increased with radius and attained values as large as∼35% at the outer surface. The sensitivity of the calculations to the cross sections is examined.These measurements were undertaken to properly account for spatial effects in the point reactor kinetics description of Rossi-αmeasurements. The spatial-effects factors obtained from these measurements, which multiply the correlated amplitude of the Rossi-αmeasurement, were 1.123, 1.109, 1.163, and 1.214 for the bare uranium, bare plutonium, reflected uranium, and reflected plutonium spheres, respectively. The error in these values is±0.010.

ISSN:0029-5639    

DOI:10.13182/NSE75-3

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

Space-dependent reactor kinetics problems can be solved by response techniques in which subassemblies of the core (called cells) are treated as“black box”transducers of neutron currents. In this paper we present a continuous integral theory of space-time neutronics, reduce this theory to an approximate response-matrix method, and solve some monoenergetic one-dimensional problems.The principal advantage over more usual reactor kinetics methods is the achievement of accuracy with a coarse spatial grid. Previously, criticality calculations using response-matrix methods had established this principle. The present work extends the result to time-dependent situations.The author believes that development of the response-matrix technique can significantly reduce the computational effort required for solution, without loss of accuracy, of a broad class of space-time reactor problems.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26741

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractEnergy may possibly be released in purely fissionable materials or in mixtures of fission/fusion materials following irradiation to produce compression and heating leading to micro-explosions. This is a variation of the“laser-fusion”concept A design of a pellet is presented that consists of a fissionable trigger and a mantle of fusionable material. Sophisticated neutronics and burnup calculations for the fission trigger show that such a device possesses a substantially higher“gain”than a purely fusionable pellet. This may open a new outlook for the peaceful utilization of nuclear energy through a breeder reactor system with an extremely short fuel doubling time and with the possibility of directly converting the released energy into electricity. Furthermore, the fission trigger may be used to kindle not only DT and LiD mantles but also DD and probably p-11B mantles to full thermonuclear ignition.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26742

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractA reanalysis of the Experimental Breeder Reactor-I meltdown shows that far better agreement with experiment is obtained by the assumption that the coolant feedback coefficient operating during the later stages of the transient is positive and unstabilizing. A possible reason for such an occurrence is suggested.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26743

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractNeutron spectra in uranium depleted in the235U isotope are analyzed with ENDF/B-III data, accounting for high-order anisotropic scattering. Two principal conclusions are made. First, changes made to inelastic scattering data relative to earlier ENDF/B files are not effective in reducing discrepancies between calculated and measured spectra. Second, changes made to unresolved capture data lead to significant improvement in the relation between calculation and experiment.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26744

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

An exact infinite-series solution to the one-speed neutron transport equation in spherical geometry is presented. The analysis is based on a partial-range variant of the spherical harmonics formalism and admits arbitrary directional discontinuities in the vector flux. Numerical results are presented to illustrate the appearance of discontinuities in the flux associated with an absorbing sphere.

ISSN:0029-5639    

DOI:10.13182/NSE75-A26745

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor

摘要:

AbstractA simple, straightforward method of solving the integral equations of neutron transport is discussed. As specific examples, highly accurate results for the Milne’s problem for half-space and a black sphere are obtained.

ISSN:0029-5639    

DOI:10.13182/NSE75-2

出版商:Taylor&Francis    

年代:1975

数据来源: Taylor