An example of operating experience in France: The Tricastin 1 incident on August 3, 1982

On August 3, 1982, at the Unit 1 of the Tricastin nuclear power plant, the rupture of the plug of a pressure reducing valve on the compressed air system serving the containment air lock resulted in the loss of air to the inflatable seal of the two air lock doors; the loss was signalled in the control room by the alarm ''air lock 0 m untight''. The containment integrity was lost for 45 minutes; but the activity released to the outside was very slight. By a rapid intervention of the operator (another plug was put on) the compressed air feeding was restored and consequently the hatch tightness; the unit remained on power during the intervention. The basic cause of the incident is a design error: the non-respect of the single failure criterion on one auxiliary system of a function important for safety (containment integrity). This example of an incident, one of the most significant in French 900 MWe PWR units since their commissioning, will serve as an illustration of the experience feed-back process in France. Difficulties in the implementation of the correctives actions decided after the incident resulted in unjustified delays and in reoccurrences of similar incidents. (orig.)