INFO DEPECHE. Corrosion on the pipeline of the Golfech nuclear power plant: the ten-year outage of the unit was extended by six months

INFO DEPECHE.  Corrosion on the pipeline of the Golfech nuclear power plant: the ten-year outage of the unit was extended by six months

The third ten-year shutdown of the No. 1 reactor at the Golfech nuclear power plant, which began on February 26 and was to end this summer (August), will eventually be extended by another six months. The reason is a corrosion problem on the auxiliary circuit piping leading to small cracks. The studies to be carried out and the work to be commissioned led the power plant to postpone reconnecting the reactor until February 2023.

Fifteen days after publication annual report of the nuclear safety authority (ASN), which provided a “very satisfactory” assessment of the safety performance of the Golfech nuclear power plant, which has nevertheless been subject to a “strict safety plan” (our box) since 2019, has encountered problems. CNPE (Nuclear Power Generation Center) in Golfech.

On the occasion of the third ten-year inspection of Reactor No. 1 – the oldest of the two 1,300 MWe PWRs (pressurized water reactors) in operation at Tarn-et-Garonne – which began on 26 February and was programmed to last until early August anomalies (LAUGHTER).

“During this ten-year outage, we were brought under inspection because we discovered ‘indications’ (abnormalities) on this RIS circuit,” says Romain Philippot, EDF Communications Manager at Golfech. Irregularities which have led to in-depth inspections and additional expertise by means of ultrasound or radiography, “said the information report opened by EDF on 14 January, which was updated in the light of progress since these corrosion problems were discovered in parts. , these “circuits are important for the safety of installations,” says the EDF report, the latest update of which dates from 19.

Remember that the “RIS” auxiliary circuit allows boron water to be injected into the reactor core to stop the nuclear reaction. It also maintains the volume of water in the primary circuit in the event of a primary refrigerant loss accident. However, this problem is not limited to the Golfech race.

Since last year, when these corrosion problems were first detected on the pipeline at the Civaux power plant, 12 of EDF’s 56 power plants in the French nuclear fleet have been affected by this corrosion problem. “In-depth metallurgical expertise will be carried out in the coming weeks,” confirms Romain Philippot, who is not yet able to say whether these anomalies are caused by “stress corrosion” (SCC) or “thermal fatigue” (1).

On the part of the Local Information Commission Golfech (CLI), which, together with the plant’s director Cyril Hisbacq, visited this shutdown of the unit last month, we are leaning towards the anomaly due to the “geometry of the pipelines”. A phenomenon that would be related to the project of the latest French nuclear power plants. The point at which ASN remains very cautious.

In April, the race director organized a visit to CLI Golfech members during the outage
Photo Golfech Nuclear Power Plant

The consequences of these corrosion problems on the small-crack auxiliary circuit pipeline are not neutral for the Golfech power plant, and will prolong this ten-year outage. “The studies and assignments lead us to postpone the reconnection of Reactor No. 1 to February 2023,” says Romain Philippot, half a year behind the planned restart of the reactor.

The nuclear police officer still accurately determines the operation of the power plant

With just three major incidents reported in 2021, the Golfech nuclear power plant performed much better than in previous years with 33 incidents in 2019, a record. ASN has since implemented a strict security plan. In an annual report published on May 17 after a 14-day inspection of the work spent at the Golfech nuclear power plant, the nuclear police officer states that “the efforts made in this regard have not yet shown visible results. […] the decommissioning of reactor 2 in 2021 pointed to shortcomings […] lack of skills, calm and insufficient organization in the control room. ”A shutdown that was“ extended by 4 and a half months in the initial program ”. The plant we have joined takes note of ASN’s recommendations for the “In 2022, safety is a priority, especially improving the skills of our employees”, says Philippine, adding that the training plan for this new generation continues with training and practice procedures. Progress has been made in the field of the environment and radiation protection, “adds the plant’s communications manager.

(1) These defects occur in the form of microcracks (initiated on the surface of the material) propagating through the thickness of the part. The mechanism that causes cracking is called stress corrosion cracking (SCC).

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