Heat removal possibilities of nuclear containments during a severe accident

After the accident in Fukushima the safety reviews of nuclear power plants showed several safety shortcomings. One of the identified problems is the long term depressurization of containment buildings, in case of a station blackout. A possible solution for the problem for VVER-440 type nuclear power plants was analyzed in the work: how heat exchangers placed in the containment can reduce the pressure. The analysis was made with the integral source term code ASTEC. To prove the effectiveness of heat exchangers, a containment model was built and different simulations - without heat exchangers or with heat exchanger installed at different locations inside the containment building - were run.. The plant specific parameters came from the Paks Nuclear Power Plant. The analysis proved the efficiency of heat exchangers for depressurization, but showed that their effect highly depends on the location they are built in.