Severe accident analysis for VVER-1000/V-320 for a station blackout accident scenario with ASTEC V1.3.0

This paper presents the results from a severe accident analysis performed with ASTEC V1.3.0 code for a nuclear power plant with a VVER-1000/V-320 reactor. The purpose of this analysis is to assess the ASTEC code behaviour in modelling of main severe accident phenomena in the primary and secondary circuit arising during a hypothetical severe accident. The performed analyses cover a station blackout (SBO) sequence with passive safety injection systems (hydro-accumulators), in order to investigate the capabilities of ASTEC to model the physical phenomena during the in-vessel phase of such a transient.

An investigation on a SBO scenario with primary side depressurization has been carried out. The code results show delayed RPV failure by depressurization of the primary side, as slowing the core damage would allow more time for systems to be recovered to mitigate or terminate the accident. This would give more time and different possibilities for operator interventions.