Containment management in the event of a severe accident in French power plants

Monitoring of the quality of the containment is a preoccupation which is present at all stages of construction and operation of French PWR plant units. In case of accident, the emergency operating procedures give priority to preventing core uncovering. Monitoring of the containment then aims to detect any abnormal feature and to limit any risk of release which might not be strictly justified by a safeguard action. In the event of a severe accident, the priority is clearly given to safeguarding the containment. The strategic options proposed to the team in charge of the situation are determined pragmatically in the Severe Accident Intervention Guide which includes the emergency procedures for containment monitoring (U2) and decompression-filtration (U5). In all cases, maintaining the containment is based on the earliest possible detection of the leak tightness defect or of bypass. For this reason, in parallel with the operating procedures, a guide devoted to the overall monitoring of the containment has been developed for the use of crisis teams. All the monitoring techniques and strategies chosen aim, in the event of a severe accident, to bring the plant back as quickly as possible to a situation in which any radiological releases are delayed, limited and filtered In order to enable the population protection plan to be applied. On future plant units, it is possible to include installation progress at design stage, both in order to reduce the risk of severe accident and to limit the impact that this would have. Special attention is given to preventing energy accidents within the containment, and to ensuring the removal of power outside the containment in the long term