Large Break LOCA Analysis For KAPP-34 Using Computer Code RELAP-5/Mod.3.2

摘要

Kakrapar Atomic Power Project units-3&4 (KAPP-3&4) are 700 MWe Pressurized Heavy Water Reactors (PHWR) are presently under construction. This paper presents the results of large break LOCA (Loss of Coolant Accident) analysis performed, for KAPP-3&4 as a part of safety studies to investigate the plant behavior. System thermal hydraulics code RELAP-5/MODS.2 has been used for the analysis.. Here the overall thermal hydraulics of the plant along with various control systems, trip and actuation logics have been simulated. High pressure accumulators and low pressure recirculation system of emergency core cooling system are modeled. The modeling of secondary system includes modeling of Atmospheric Steam Discharge Valves (ASDVs), Safety Relief Valves (SRVs), Condensate Steam Discharge Valves (CSDVs), Governor valves, the U-tubes of the steam generator, the riser, the separator and the steam drum. Using this model, critical break size in the Reactor Outlet Header(100% break) was analysed, for evaluating maximum peak clad temperature. Following postulated accidents, the event progression and the variation of different parameters like different Header pressures, mass flow rate in the core, fuel clad temperature, rate of discharge from break, injection rate of ECCS in core etc have been studied.