Study of in-containment source term behavior for VVER-1000 under LOCA conditions using the IRBURN code system

Abstract

The purpose of this paper is to present a kinetic model for simulation and calculation of in-containment activity in LWR power reactors after severe accidents. In-containment accident source term depends on the reactor containment specification as well as its safety performance under different accident conditions. A module is developed for quantification of the in-containment activity and loss of coolant accident scenario in a VVER-1000 reactor was modeled asan illustrative example in this study. This module is implemented in the new version of the IRBURN code system. The effects of engineering safety features on the fission products activities during accident time have been investigated.According to the results, the impact of re-suspension rate from free surfaces on the source term production is dominant during initiation of the accident, while the influence of volumetric time dependent source increases during the evolution of the accident. Besides, the deposition on the containment surfaces has almost the largest contribution in removal of activity during the accident.