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Event Report Forms (ERFs) are filed to the IAEA. Sometimes there are multiple event reports, updating the rating, the event description. Here you only see the latest event report

ERF send date: Wed, 03-07-1991
ERF description: During the yearly outage of Gravelines NPP (Unit 6) for checking and refuelling an inspection revealed that 2 valves of an auxiliary circuit were blocked in close position. A pressurized water reactor of 900 to 1300 MWe has a reactor heat removal circuit which assures the removal of residual heat from the fuel during shut-down of the reactor. This circuit has 2 pumps and 2 heat exchangers on which level the water of the primary circuit after flowing through the reactor core is giving up heat to an auxiliary circuit which is called component cooling, which has next to his 2 heat exchangers a pressure valve to relieve excess pressure. The investigations undertaken have shown that the valves have been blocked in closed position since the reactor began operating in 1985. As a result of this detection EDF has started a campaign for all other pressurized water reactors to verify the availability of valves of the same type. Further checks carried out in other plants on March 4 showed that 30 pressure valves were not operative. These were in circuits classed as "important for safety": in the component cooling circuit - and in the case of Gravelines - and in other circuits, such as those providing pressurized air and those for the treatment and storage of effluents. A full assessment will be completed in the next few days.
Relating to other anomalies mentioned in Magnuc (information system of the French Nuclear Safety Authority, SCSIN) (anomalies of maintenance, of sand filters, anomalies in the installation of sump filters) which are affecting the quality of installation completion of pressurized water reactors, the Ministers of Industry and the Environment asked EDF to make a special effort to detect such problems. It is by making such an effort that EDF discovered that valves in certain auxiliary circuits were not in the right state to fulfill their function.
It is therfore welcome to encourage the efforts made by EDF and to correct such anomalies; at first these efforts could lead to an increase in the anomalies detected. But on the other hand, it is appropriate to state that the final phase of reactor construction proves yet again that it may conceal some significant errors in the organization of quality control. Upgrading the level of quality control at certain construction sites appears even more indispensable. In the first analysis these anomalies found in the auxiliary systems classed as "important for safety" do not seem to have resulted in an important cummulative risk, but it is worrying that there has been lack of compliance with installation methods, with control and quality assurance of the circuits concerned, and this demands deeper analysis.
BASIS FOR RATING: For this reason the whole of these anomalies has been provisionally classed a level 2 on the (French) severity scale. This classification could be reviewed at a later date after having taken into account the results of checks and analysis.
ERF rating date: 01-01-1991
ERF contact person: Mr. J. Breuil
ERF address: 99 rue de Grenelle, F-75700 Paris, France
ERF affiliation: Ministere de l'industrie, Service central de surete des, installations nucleaires

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