Dynamic Analysis of Large Fast Reactor

抄録

The dynamic behavior of a 1, 000 MWth sodium-cooled oxide-fuel fast breeder reactor was analyzed. To determine the stability of fast reactors, a new analytical model was introduced. The transfer function of EBR-I Mark IV calculated therewith agreed closely with experimental data, and the stability study on the model case was carried out with this model. The present analysis was extended to cover such accidents as reactivity insertion, coolant flow coast down and loss of coolant flow, which are commonly considered in fast reactor safety analysis, and further, the influence of changes in reactivity coefficients upon the consequences of such accidents was also surveyed.
The results indicated no appearance of instability in large fast reactors under credible conditions, and that fuel center melting should occur prior to sodium boiling in the case of a reactivity insertion accident, when the Doppler coefficient should have great influence, in contrast to the sodium coefficient, whose effect should be small. It was also ascertained that there should be no fear of coolant flow coast down from pumping power failure if the scram system operates normally, and that in the event of channel blockage sodium should begin to boil within a few seconds at about two thirds of core height. Compared to the case of reactivity insertion, the effects of the individual coefficients were found to act in the inverse direction in these latter cases.