Long-time neutron-temperature dynamics of fast-neutron systems in supercritical emergency regimes

The results of experimental and computational investigations of the long-ti me (less than or equal to 60 h) behavior of the BIR-2M and BIGR pulsed reac tors with abrupt transfer into a supercritical state under conditions with no externally initiated reactivity changes are presented. these conditions simulate possible incidents when all mechanisms for regulating reactivity a nd emergency protection fail. The computational characteristics of the accidental fission burst in a meta llic critical assembly consisting of highly enriched uranium on the FKBN-2M stand, which occurred at the All-Russia Scientific-Research Institute of E xperimental Physics on June 17, 1997, are presented. 6 figures, 1 table, an d 6 references.