A New Simulation Code for Analyzing Loss of Coolant Accidents in VVER-440/213 Reactors Concerning Activity Transport Available to Purchase

In the Atomic Energy Research Institute, Budapest, Hungary a computer code for modelling the in-containment fission product related processes of a design basis LOCA in VVER-440/213 type nuclear reactors is under development. The model is based on the lumped-parameter approach (the total volume of the simulated containment is divided into distinct, connected sub-volumes in which the parameters are assumed to be homogenous). The structural and functional models of the adequate reactor units are implemented in the code. The main considered physical processes of the fission product elements are radioactive decay, transport by gas flows, removal from the containment atmosphere by adsorption to wall surfaces and wash-out. In order to test the abilities of the code we performed sample calculations for the units of the Paks Nuclear Power Plant, Hungary. In this study the discussion of the first results is presented following a summary of the basics of the physical models implemented in the code.