The In Vessel Retention (IVR) Strategy for VVER 1000 Units Based on Existing Level of Research and Development Work

The Fukushima severe accident needs very intensive and detailed response from all involved, to develop relevant mitigation strategies. For VVER type units this strategy is already developed and proved for smaller output units type VVER 440 MW. For higher output units type VVER 1000 MW this strategy is under development. In presented paper recent development based on analytical and experimental research work is presented. The research work is not yet finished, however, analytical and experimental work is building strong arguments that the IVR strategy is possible even for higher power existing units in operation, with application of proved measures which will be described.