Practical Development Of Sodium Cooled Fast Reactor System Analysis Program

Fuel-pin cladding temperature under accident cases is an important parameter in evaluating the safety of the reactor. Cladding the first physical barrier to prevent radioactivity releasing from the reactor to environment, so the integrity of the cladding is in the direct relation to the reactor safety. In the accident, the temperature is the main variable, so the cladding temperature limiting is one of the important parameters that must be cosidered.Based on the characteristics of the DINROS code, A hottest channel model for the transient maximum cladding temperature is presented.The simplification and hypotheses for the hottest channel are presented as, 1 The velocity of the coolant in the hottest channel is approximated by Novendstern model, for which axial flow of the channel is considered to be invariable along the axial position, cosidering the crossflow induced by pressure difference, crossflow mixing by wire wrap and the cross conduction of the neighboring subchannels, which are of little effect to the transient maximum coolant temperature. 2 The conservative parameter for the hottest channel, the hottest subchannel of the hottest SA. at the beginning of the equilibrium in the core, has been selected.The results and the comparisons of the maximum coolant temperature, which are from the hottest channel model with the subchannel analysis code COBRA, are presented. It is noted that, the simplification and hypotheses for the hottest model are reasonable and conservative.The hottest channel model for the maximum cladding temperature has been demonstrated to be suitable for analyzing the maximum cladding temperature of the transient accident calculated by DINROS. With the hottest channel model, DINROS has been more integral. We can obtain the hottest cladding temperature of the transient accident without applying time consuming subchannel analysis code. The paper has solved the remained problem of the preliminary safety analysis report, and has provided a useful tool for the final safety analysis report.