Advances in operational safety and severe accident research. Final report of the Nordic Nuclear Safety Research Project SOS-2
A project on reactor safety was carried out as a part of the NKS programme during 1999-2001. The objective of the project was to obtain a shared Nordic view of certain key safety issues related to the operating nuclear power plants in Finland and Sweden. The focus of the project was on selected central aspects of nuclear reactor safety that are of common interest for the Nordic nuclear authorities, utili-ties and research bodies.
The project consisted of three sub-projects. One of them concentrated on the prob-lems related to risk-informed decision making, especially on the uncertainties and incompleteness of probabilistic safety assessments and their impact on the possi-bilities to use the PSA results in decision making. Another sub-project dealt with questions related to maintenance, such as human and organisational factors in maintenance and maintenance management. The focus of the third sub-project was on severe accidents. This sub-project concentrated on phenomenological studies of hydrogen combustion, formation of organic iodine, and core recriticality due to molten core coolant interaction in the lower head of reactor vessel. Moreover, the current status of severe accident research and management was reviewed.