Criteria and methodology for presentation

Since the accident in the Japanese nuclear power plant Fukushima Dai‐ichi the discussion on severe nuclear accidents has increased. Much interest has been directed towards severe nuclear accident prevention and mitigation, which both are needed in order to lower the risk of a nuclear accident and ensure public safety. This report describes a study of civil nuclear related risks of events with very low probability but severe consequences. The study aims to create a concept of a methodology on how to include low probability severe consequence risks in a risk management process; focusing on the economic consequence for the operator and owner. The studied risk management is a part of E.ON Kärnkraft Sverige AB’s (EKS) risk management process. EKS experienced an interest to expand their risk management process to include risks with low probability and severe consequences and in this report a methodology on how this can be done is presented. The methodology has been created from studying the risk management process focusing on the tree reactors at the nuclear power plant Oskarshamn Kraft Grupp (OKG) outside Oskarshamn. In order to understand the included risks as well as the context and concept of the risk management process several areas needed to be studied. The project included studies on severe accident mitigation and prevention, important severe accident sequences, possible economic consequences, legal and insurance framework within the Swedish nuclear industry, and the EKS and OKG risk management process. The methodology focuses on the severe consequences of the risks and assumes that these may be initiated by a number of accident sequences. The consequences of the sequences are described using three parameters: radioactive release, property damage and business interruption, which are connected to an economic impact on the owner and operator. The analyses of these risks should provide risk assessment material for further steps in the risk management process