Containment Challenges and Requirements in a Nuclear Powered World

Abstract

Nuclear power already makes a significant contribution to world energy supplies but, if the role of nuclear power is to expand significantly in the future, it may prove necessary to argue that major releases of radioactivity to the environment cannot, rather than will not, occur. Containment strategy will necessarily be a crucial part of such a case, but design solutions will also have to be highly cost-effective if nuclear power is to flourish. Containment concepts are not unique to nuclear power and were included from the earliest nuclear power plants. However, containment cannot be treated as a separate issue from the threats which the containment could face and, as such, is part of the entire plant design concept. The solutions adopted for specific designs of reactor or other facilities such as reprocessing plants therefore differ. They are generally based on specification of design basis accidents but PRA has provided a powerful tool to assess the implications of beyond design basis and severe accidents. As a result the installation of systems to protect containments from such threats, including accident management systems, has been considered and adopted in some cases. For the longer term, design changes to reduce the threats to containments or to strengthen containment structures have been proposed. PRA is likely to provide the best information on which to base decisions on these matters, as they all involve judgements about relative risks and cost-effectiveness of risk-reductions. The degree of flexibility to be given to operators in using accident management systems and the information and training the operators would need to take decisions in accident situations need careful consideration. PRA can also provide a useful input into some aspects of these matters.