Pressuriser safety valve stuck open severe accident analysis for VVER 1000 NPP

Kudankulam Nuclear Power Project is a 1000 MWe VVER type reactor incorporating special design features. In AERB analysis was performed for this reactor using RELAP5/SCDAP/Mod 3.2 for an accident, which is initiated due to inadvertent opening of a pressuriser safety valve and remaining in stuck open position. Without Passive Heat Removal System (not taking credit of PHRS), the accident turns into severe accident due to active safety systems failure. Continued heating and loss of primary coolant lead fuel failures and melting. This paper gives the brief description of system and its modeling using RELAP5/SCDAP/Mod 3.2 along with the initial and boundary conditions. Finally the analysis results and event sequence based on variation of important parameters such as core maximum temperature, oxidation and hydrogen generation, fuel melting and relocation etc. are discussed. (author)