the crack discovered in Penly further complicates the situation of EDF

by time news

The phenomenon of stress corrosion, detected in October 2021, continues to weigh on the French nuclear fleet. A new large-scale crack has been detected on the safety injection circuit of reactor number one at the Penly power plant (Seine-Maritime), with a power of 1,300 megawatts (MW), but currently at the ‘stop. While EDF estimated, at the end of 2022, to be “out of the stress corrosion crisis situation” and entered “in a phase of industrialization and standardization” repairs, the Nuclear Safety Authority (ASN) asked the electrician, on Tuesday March 7, to “revise your strategy”.

Read also: Nuclear: the Safety Authority summons EDF to “revise its control strategy” after the discovery of a crack in Penly

Revealed by the specialized site Context, Tuesday, this crack had been reported in a note published by EDF on February 24, but had so far gone unnoticed. Unlike the microcracks detected on other reactors (such as those of Chooz, in the Ardennes, and Civaux, in Vienne, 1,450 MW, the most powerful and most recent), the defect observed at Penly is described as particularly important: the ASN describes a crack extending over 155 millimeters (mm), “that is approximately a quarter of the circumference of the piping”. The nuclear policeman adds that its maximum depth is 23 mm, for a pipe thickness of 27 mm.

Although the Penly 1 reactor had already been identified as being among the most sensitive to the phenomenon of stress corrosion, this portion of the circuit in particular was considered “non-sensitive” by EDF, due to its geometry. The licensee, like ASN, considers that the presence of corrosion could be explained by the double repair to which the piping was subjected during the construction of the reactor.

“Increased probability of rupture”

According to ASN, the presence of this crack leads to “the resistance of the piping is no longer demonstrated” et “affects the safety function related to reactor cooling”. The safety injection circuit is in fact an essential element: it is this safeguard system which makes it possible to inject water into the main primary circuit to cool the reactor core in the event of a breach.

Because of “potential consequences and increased probability of rupture”, ASN classified this incident as level 2 on the International Scale of Nuclear and Radiological Events, graduated from 0 to 7 according to severity. Level 2 events are very rare.

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