By akademiotoelektronik, 01/10/2022

Paluel: production unit 1 of the nuclear power plant is in maintenance for four months

It was a short circuit that triggered the disaster. On Sunday April 4, 2021, around 10:30 p.m., the main transformer of production unit one of the Cauchoise nuclear power plant caught fire, causing an automatic shutdown of the reactor. Barely a few days later, on Thursday April 8, the director of the site Jean-Marie Boursier deciphers: “It is certainly due to a technical failure, even if the exact origin of the incident is still unknown. An expertise is in progress. However, there is no reason to worry, the fire did not take place in the nuclear part, and there were no injuries or rejection at sea. " He salutes the responsiveness of the operating staff on site, who brought the fire under control "in less than an hour", even before the arrival of the firefighters. “Our 400 operating personnel are trained in fire prevention and firefighting,” he says. The other 900 have regular training. »

"13,000 activities"

The affected production unit has not been restarted because, according to a schedule established "for more than a year", it has been the subject of Saturday, April 10, and for four months of what the profession calls a "partial visit".

"More than 13,000 activities are planned during this scheduled maintenance shutdown, including in-depth checks of the main primary circuit, a complete inspection of the engine of one of the two emergency generators and hydraulic tests of the secondary capacities" , delivers the EDF communication department. Is the April 4 fire a sign that it was high time for this operation to take place? “It has nothing to do with it, defends the director. It is a damage, it is the fault of bad luck. The transformer affected was changed in 2016, and like the rest of the equipment is subject to a trend analysis - oil, temperature... - on a regular basis. »

Between the end of January and the beginning of March, another of the four production units of the Paluel power plant was also the subject of a partial visit. And in the fall of 2021, a third will follow. Production shutdowns are thus staggered, rather on sunny days, because in winter, the country's energy consumption increases.

40 years old, and after?

The final stage of checks on these sensitive units are the ten-year inspections - therefore every ten years -, again one for each production unit. “A complete check-up of the plant, image Jean-Marie Boursier. It requires six to seven months of shutdown, and allows an update of the installations in terms of security. The Fukushima nuclear disaster in 2011 was logically incorporated into EDF's software.

The next local ten-year inspection is due to take place in December 2025. The country's nuclear reactors were originally designed to last forty years, although the Nuclear Safety Authority (ASN, read below) has since considered their extension, on a case-by-case basis. Commissioned in 1986, the Pauelle plant completed its third cycle of ten-year inspections last year.

ASN, the authority keeping watch

The Nuclear Safety Authority (ASN) is an independent administrative authority. It is responsible for three main missions, in particular with the 19 nuclear power plants currently in operation in the country: informing the general public, regulating (advising the government on decrees and ministerial orders, making regulatory decisions of a technical nature) and controlling on site compliance with the requirements - general rules and specific prescriptions.

Seven incident notices in 2020

Based in Caen, ASN Normandie carries out these missions with three plants: Flamanville (Manche), Penly (Seine-Maritime) and therefore Paluel, the first plant of Normandy with its four reactors of 1,300 megawatts each. Beyond that, the independent authority also controls other facilities (Ganil in Caen for example), but also approved laboratories, or local nuclear activities in various fields: medical, veterinary, industrial, research, etc.

A detailed bulletin for each structure can be consulted on its website www.asn.fr. In its 2019 assessment of the Paluel NPP, the ASN specifies for nuclear safety: "The process for managing deviations [from compliance affecting equipment, editor's note] implemented on the site is efficient and the analyzes of the causes relating to organizational and human factors are explored”. In terms of operation, "the performance of the nuclear power plant has deteriorated slightly and reveals a lack of rigor in the management activities". Finally, in terms of maintenance, "the performances are satisfactory", with nevertheless, among the recommendations, an improvement of "the monitoring of the interventions carried out by service providers", also at the environmental level, "mainly concerning the wastewater treatment plant Wastewater ".

In 2020, ASN issued seven incident notices for Paluel, including one level two (out of a total of seven).

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