The nuclear safety Authority has requested the operator to proceed under three months of strength checks of the funds of the steam generators.
The French nuclear safety Authority (ASN) said for its part to have asked the operator to carry out checks, within three months, the strength of the fund of the steam generators (SGS).
these are, in effect, to segregation, that is to say, excessive concentrations of carbon in some areas, it is likely to weaken the steel of this important component of the nuclear island of the plant, since it produces steam that is sent into the turbine for producing the electricity. This heat exchanger subjected to pressure and elevated temperatures, therefore, must be foolproof.
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These five “slices” are part of the ten-eight of which have been noted these anomalies in the forging of the parts. A fault which had been first highlighted on the vessel of the EPR in construction at Flamanville (Manche). Each reactor has three or four generators according to its power, the total GV concerned is forty-six : twenty-six have been forged in Japan by JFCC for the account of Areva, and twenty in the factory of le Creusot (Saône-et-Loire) of Areva, which is the subject of an in-depth audit for months by the experts of the group of nuclear and EDF’s.
On the ten-eight reactors concerned by the warning of the ASN launched before the summer, six have been inspected and have been able to restart with the agreement of the authority of nuclear and the other seven (Bugey 4, Civaux 2, Dampierre 3, Gravelines 2, Saint-Laurent-des-Eaux B1 and Tricastin 1 and 3) are in the course of the inspection and waiting for a restart. Five more reactors for which the ASN has prescribed controls will, therefore, bring to twelve the number of slices in the judgment.
” These twelve reactors are equipped with steam generators are forged in Japan, on which the first analyses are state of concentration of carbon higher than on the other “, explains Olivier Gupta, director-general of ASN. As a general rule, he says, the carbon content of the steel of these components is of the order of 0.2 %. On the GV equipping the six other reactors in question, the rate of carbon amounted to about 0.3 per cent. But, on some of the twelve remaining installments, it approaches 0.4 percent.
The Institute of radiation protection and nuclear safety (IRSN), after study of these anomalies, indicates that” it does not at this stage data on the behavior of materials at such levels of concentration of carbon, significantly higher than those studied in the framework of the fault of the vessel of the EPR “.
where, ” says Mr. Gupta, the decision to prescribe at EDF controls without waiting for a scheduled stop of five new reactors. The operator shall provide to the safety authority a record of the rationale for establishing the reliability of the offending pieces. Its review will then prompt several weeks. “ at this stage emphasizes ASN, we can’t prejudge our decision. It is not excluded that we allow ourselves not the restart of the reactors concerned. “
The electrician, who had programmed these stops between the end of 2016 and 2017, wants to make the checks before entering the cold season so that the park of fifty-eight reactors to be available between January and march, the months when the consumption is often the highest. EDF may also want to register the loss of revenue related to the shutdown of reactors in its accounts 2016 rather than defer to its fiscal year 2017.
It is also expected that the conclusions of the ASN concerning the resistance of the vessel of the EPR of Flamanville (Manche), of which the top of the lid and the bottom have also a too high concentration of carbon. Areva, which has forged the piece in le Creusot, and EDF, which has already been installed in the reactor building, must submit the latest results of their tests at the end of the year. ASN will rule at the end of the first half of 2017 on its compliance – or non – standards drastic that apply to pressure equipment nuclear.
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