摘要:

AbstractNumerical investigations have been made on thermally, mechanically, and thermomechanically driven flows of a weakly compressible gas in a gas centrifuge assuming an axisymmetric continuum flow. The finite difference method developed for these computations is based on the Euler/upwind scheme and provides a numerically stable solution. It is found that an almost cylindrical Couette flow is established in an annulus despite the end effects of the plates and that the two mechanically driven circulations interact with the thermally driven circulations.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19848

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractA major portion of the safety analysis effort for the liquid-metal fast breeder reactor is involved in assessing the consequences of a hypothetical core disruptive accident. A postulated loss-of-flow transient without scram may produce a two-phase fuel source at high pressures. The heat transfer process between the fuel and the sodium coolant as it is ejected into the upper plenum is described in this study. One mechanism that can cause the coolant to become entrained in the two-phase fuel is Taylor instabilities. The characteristic size of the entrained coolant droplets is considered to be equal to the critical wavelength of a Taylor instability. Analysis of full-scale reactor conditions indicates that the dominant heat transfer mechanism is radiation. Also, if noncondensible gases are absent, fuel vapor condensation on the sodium coolant droplets is controlled by mass diffusion, hence the subsequent rate of coolant vaporization is small. The net effect of the heat transfer is to reduce the fuel vapor pressure and reduce the expansion work by a factor of 1.2 to 2.5. Small-scale simulant experiments utilizing refrigerants could confirm the fuel condensation/sodium vaporization behavior, while reactor material tests must be done to investigate the radiation heat transfer mechanism.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19849

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractMeasurements of neutron and gamma-ray penetrations in an iron shield were performed up to a 60-cm depth in a tightly coupled source shield configuration with the fast-neutron reactor YAYOI as a source. Rates of neutron reactions and gamma-ray dose rates in the iron shield were obtained using activation foils and thermoluminescent dosimeters. Analyses of the experiments were made by using the DOT-III code with coupled neutron and gamma-ray cross sections from ENDF/B-IV and POPOP4 libraries. To obtain the source condition for the iron shield analyses, the calculated spectrum was adjusted to the measured reaction rates at the reactor shield boundary. The calculated neutron and gamma-ray distributions in the iron shield show fairly good agreement with the experiments. The effect of difference in Bondarenko-type self-shielding factors on the analyses of the iron shield is also shown.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19850

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractA general problem of time-dependent neutron transport in a spatially heterogeneous medium is analyzed by two perturbation methods that have previously been applied to specialized problems. These“buckling”and“asymptotic”methods are shown to be equivalent in the sense that the asymptotic method leads to a time-dependent diffusion equation with constant coefficients, whereas the buckling method leads to the corresponding dispersion law. Two applications, the calculation of keff, and the derivation of a point reactor model are given. Also, the general results obtained here are shown, in several special cases, to reduce to the simpler results obtained previously.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19851

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractA methodology for combining physical considerations with those of autoregressive integrated moving average time series analysis is presented. It is shown that the former can provide identification of the resultant model, while the latter can furnish a means for parameter estimation. Application of the techniques so derived to an analysis of a simulated liquid-metal fast breeder reactor accident experiment demonstrates the method and its usefulness in analyzing transient situations.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19852

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractHigher order generalized perturbative formulations are derived in relation to linear functionals for systems at generally nonstationary conditions, starting from perturbative expressions of the density function. Formulations relevant to stationary shielding problems are finally simply obtained as particular cases.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19853

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractDiffusion theory analysis of a series of multidimensional space-time experiments is appraised in terms of the final experiment of the series. In particular, TRIMHX diffusion calculations were examined for an experiment involving free-fall insertion of a235U-bearing rod into a heavy-water-moderated reactor with a large reflector. The experimental transient flux-tilts were accurately reproduced after cross-section adjustments forced agreement between static diffusion calculations and static reactor measurements. The time-dependent features were particularly well modeled, and the bulk of the small discrepancies in space-dependent features should be removable by more refined cross-section adjustments. This experiment concludes a series of space-time experiments that span a wide range of delayed neutron holdback effects. TRIMHX calculations of these experiments demonstrate the accuracy of the modeling employed in the code.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19854

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE80-A19856

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE80-A19857

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE80-A19858

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor