In-vessel retention via external reactor cooling

In-vessel corium retention via external reactor pressure vessel cooling is considered to be an effective severe accident management strategy for corium localisation and stabilisation. The main idea consists in flooding the reactor cavity and transferring the decay heat through the reactor wall to the encirclement water and than to the atmosphere of the containment of nuclear power plant. The aim of this strategy is to localise and to stabilise the corium inside reactor pressure vessel. Not using this procedure could destroy the integrity of vessel and might cause the interaction of the corium with the concrete at the bed of the reactor cavity. Several experimental facilities and computer codes were applied to simulate this strategy for concrete reactor designs. There were applied necessary technical modifications concerning the implementation of this concept at the Loviisa VVER-440/V213 in Finland. In 2009, this concept was implemented into Bohunice VVER-440/V213 in Slovak republic. This strategy is also an important part of the advanced reactor designs AP600 and AP1000. This concept is taken into account at high-power reactor APR1400 that is going to be finished in Korea in 2013.