Implications of large scale sodium water reactions in an LMFBR

Large leak sodium-water reaction in the steam generator is one of the important events to be considered for the Liquid Metal cooled Fast Breeder Reactor (LMFBR). For the design of secondary sodium circuit components a design basis water/steam leak has been defined. For PFBR (Prototype Fast Breeder Reactor), under commissioning at Kalpakkam, India, a computer code SWEPT developed for the pressure transient analysis is used for estimating the maximum design pressure of the components. In order to study the possibility of any cliff edge effect, large scale sodium-water reaction analyses beyond the design basis leak have been carried out using SWEPT and CAST3M computer codes and the results are presented in this paper. Based on the studies it is found that simultaneous double ended guillotine failure of 15 tubes can be managed with the available design margin. Possibility of core sub assembly vibration is also studied using the CAST3M computer code.