The draft EPR under pressure : the lid of the container raises questions




The site of the nuclear reactor of new generation at Flamanville 3, said “EPR”, could suffer a new setback with the publication of a report by the Nuclear Safety Authority, calling into question the durability of the lid of the tank, whose life would be no more than “a few years”. A problem for EDF, which has already swallowed up more than € 10 billion in the project…
The problems of the EPR are not resolved. According to a report by the Nuclear Safety Authority (ASN), the lid of the vessel could not remain in service more than “a few years“, due to defects in the metal of the parts produced at the plant Areva Creusot. A too high concentration of carbon in certain areas calls into question their mechanical strength, particularly the toughness of the steel.
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According to the report, which was prepared by the Institute of Radioprotection and Nuclear Safety (IRSN) : “The use of the cover of the current vessel of the EPR cannot be considered beyond a few years of operation without the necessary controls to the strengthening of the second level of defence in depth have been implemented“. It is therefore the responsibility of EDF and to its future subsidiary, Areva NP, to demonstrate that it could check the evolution of the part in service. The report of the ASN considers that the deficiencies would not call into question the entry into service of the plant.

 

To compliance by replacing the lid ?

 

The replacement of the lid – removable – would be already programmed for 2021, at which time the reactor will be shut down for the first time, in order to recharge fuel. Only one condition : start now the making of the second cover, so that it is ready on time, the production of such a piece is particularly complex, as evidenced by the current difficulties. Recall that the ice sheet extent 4,72 metres in diameter 23,2 cm thick. Hemispherical, it is breakthrough of 107 lines which control the nuclear fuel rods but also to pass the instrumentation necessary for the control of the chain reaction as well as a vent tube. The manufacturing process is to crush an ingot to forge, of 156 tons, sunk under vacuum, to obtain a disc of 450 mm thickness, practical and then to heat-treat and stamp it in order to obtain materials hemispherical. In the case of parts produced in le Creusot, the concentrations of carbon (to 0.30 % instead of 0.22% of maximum value) were found in the periphery, areas where they would have had to be eliminated during the manufacturing process.
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The final decision of the DSC is expected to occur in the fall of 2017, following a public consultation. A green light or a stop will be decisive for EDF and the nuclear industry the French, because they condition the recapitalization of Areva by the State, to the tune of 4.5 Bn €, and the sale of its activity in reactors in the energy French. A reappraisal of the whole program EPR would be a disaster for EDF, which has investments in Flamanville have tripled since the launch of the project, from 3 Bn € 10.5 Bn €. The French group has also embarked on an ambitious project in Great Britain at Hinkley Point, where… two-reactor type EPR need to be assembled. A program to 21 Bn €, of which a large part made by the French company.

 

Timeline of events :
* End 2014 : Areva discovers an anomaly in the chemical composition of the steel of the central part of the lid and the bottom of the tank of the EPR reactor of Flamanville
* Early 2015 : Areva offers a justification of mechanical resistance of the caps of the tank
* September 2015 : the experts of the ASN and the IRSN formulate the requirements to validate this approach of justification (verification of the absence of other defects, “harmful”, a program of tests carried out on samples collected in three caps sacrificial originally intended for projects of reactors of EPR type in the United Kingdom and the United States, calculation of the maximum induced by the pressure and the temperature in normal operation and accidental, verification of the toughness minimum material)
* December 2016 : Areva transmits the analysis results obtained in accordance with the established protocol (including 1.700 mechanical tests and 1,500 chemical analyses)
* June 2017 : following a thorough review of these results, the ASN and IRSN to produce a joint report presented to the permanent group of experts for the pressure equipment in nuclear power in order that he make a notice




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