[en] The critical masses and fission and explosive energy releases of PuO₂, PuO₂-UO₂, UO₂ and UO₃ assemblies were calculated. The choice of parameters used in the model is conservative and was chosen after review of appropriate plants that have been and are proposed for construction in the future. The resulting data envelopes are intended to include any conceivable set of circumstances that could ultimately lead to a nuclear incident. All energy release analysis was performed for initial fission spikes only; recriticality mechanisms were not considered

[en] Los Alamos has performed independent safety and environmental reviews or has performed evaluations in specific task areas for both the Nuclear Regulatory Commission and the Department of Energy (DOE) since initiation of the program in 1974. During this period reviews were performed on nine commercial and four DOE operated nuclear facilities. Safety reviews were completed on fourteen research reactors. In addition, physical security reviews were performed on all operating commercial nuclear power reactors and most research reactors

No abstract available

[en] Measurements in seven Los Alamos fast critical facilities are described; all are related to elucidating the causes of the central reactivity discrepancy in fast reactors. Specific capabilities of these specialized assemblies permit measurements well-above delayed critical and these confirm the validity of the delayed neutron data used for calibration; there is therefore no reactivity-scale error. Reactivity measurements in these homogeneous assemblies exhibit no discrepancy. It is concluded that nuclear data should not be adjusted to eliminate the discrepancy found in other, heterogeneous assemblies

[en] The paper discusses reactor disassembly comparisons between (1) the PAD and VENUS-II computer codes and (2) the PAD code and a simple theoretical analysis. In the former comparisons a voided core model of an intermediate size LMFBR was the starting point for variations in the reactivity insertion rate, Doppler modeling, and fuel vapor equation of state. The study has shown that the peak-to-average power density is an important ratio whose value should be conserved when mapping from two- to one-dimensional geometry. Additionally, fission energy and peak temperature values agreed to within 10-15 percent, and kinetic energy as calculated by PAD is shown to be consistent with the post-VENUS-II work evaluation. Finally, relatively small fission energy differences yielded substantially larger variations in the kinetic energy. The base for the latter comparison study was the original Bethe-Tait analysis. Results indicate good agreement between the two analyses with the exception of kinetic energy releases which differed by a factor of approximately 2. Parameter variations show high sensitivity of the calculated kinetic energy to thermal energy deposition and Doppler feedback

No abstract available

No abstract available

[en] The critical masses and fission and explosive energy releases of PuO₂, PuO₂--UO₂, UO₂, and UO₃ assemblies have been calculated. The parameters selected for the model are conservative. They were chosen after review of appropriate plants that have been and are proposed for construction in the future. The resulting data envelopes are intended to include any conceivable set of circumstances that could ultimately lead to a nuclear incident. All energy release analysis was performed for initial fission spikes only: recriticality mechanisms were not considered

[en] A systematic investigation of heavy isotope behavior in the Pajarito fast-neutron critical assemblies is described. Included will be central reactivity coefficient measurements and fission rate measurements in natural uranium reflected plutonium and 93%-enriched uranium metal assemblies and in Big Ten, a depleted uranium reflected 10%-enriched uranium metal assembly

[en] Measurements in seven Los Alamos fast critical facilities are described; all are related to elucidating the causes of the central reactivity discrepancy in fast reactors. Specific capabilities of these specialized assemblies permit measurements well-above delayed critical and these confirm the validity of the delayed neutron data used for calibration; there is therefore no reactivity-scale error. Reactivity measurements in these homogeneous assemblies exhibit no discrepancy. It is concluded that nuclear data should not be adjusted to eliminate the discrepancy found in other, heterogeneous assemblies