Analytical validation of operator actions based on SAMG for VVER 1000 with ASTECv2r3 computer code

•Performing of analytical validation of operator action based SAMG.•Simulation of base calculation of SBO scenario without operator action for VVER 1000.•Simulation of SBO scenario with investigation of operator actions based on SAMG for VVER 1000. This paper presents the analytical validation of operator action based on severe accident management guidelines (SAMG) for Kozloduy NPP VVER1000 with severe accident computer code ASTECv2r3. The work is oriented on investigation of plant behavior during total loss of power and the operator actions performed based on strategies considered in severe accident management guidelines (SAMG) in Kozloduy nuclear power plant (KNPP). Using the SAMG strategies the operator depressurize primary circuit by gas removing system (YR) and try to cool down the reactor core by high pressure injection system (HPIS). The purpose of these analyses is to examine the possibility of keeping the core from further damage during a severe accident and to assess the likelihood of additional generation of hydrogen by additional flooding of the heated core. For this purpose it have been simulated a SBO scenario with injection of cold water by a high pressure pump (HPP) in cold leg at different core exit temperatures at 923K and 1253K. The selection of investigated analyses was based on severe accident management strategy of KNPP VVER1000. The presented work is important for analytical validation, verification, and further improvements of SAMG as well as for assessment of Level 2 probabilistic safety analyses (L2 PSA). The work was performed at the Institute for Nuclear Research and Nuclear Energy (INRNE) in the frame of severe accident research.