ICONE15-10327 VVER SAFETY ANALYSIS BY THE COUPLED CODE ATHLET/BIPR-VVER

Abstract

The paper describes the modelling features for a VVER-1000 nuclear power plant by the coupled system code ATHLET/BIPR-VVER. Special attention is paid on the reactor pressure vessel model and its nodalization schema. They play an important role for the realistic prediction of the fluid mixing phenomena in case of asymmetric transients. For such a transient - simultaneous isolation of one steam generator from the steam line and the feed water supply at low power level - validation to measured parameters are presented and analysed. The results of the simulation are compared with experimental local and integral plant loop data from NPP Kozloduy Unit 6 collected during the plant-commissioning phase. Additional examples of coupled code application for VVER-1000 reactor applying detailed reactor pressure vessel nodalization are also presented, choosing Exercise 3 of the CEA-NEA/OECD VVER-1000 Coolant Transient Benchmark (V1000CT-2) - a main steam line break.