On February 20, 2020, EDF declared to the Nuclear Safety Authority (ASN) a significant safety event concerning an earthquake resistance fault in the pipes of the raw water supply circuit (SEC) of the four reactors at the power station Tricastin nuclear power plant. The SEC circuit contributes to cooling in normal operation as well as in an accident situation all the circuits and equipment important for the safety of the installation. The SEC circuit consists of two redundant channels. By design, if one channel fails, the other provides the same functions. Following the identification of under-thicknesses on piping in the SEC circuit of the reactors at the Saint-Laurent nuclear power plant in Loir-et-Cher, the checks conducted by EDF showed in November 2019 that piping SEC circuits of the four reactors at the Tricastin nuclear power plant were insufficient in thickness to guarantee their resistance in the event of an earthquake. In the event of an earthquake, the SEC circuits could therefore not have been able to perform their reactor cooling function.
ASN 3rd April 2020 read more »