By Benjamin Mallet
PARIS (Reuters) -French utility EDF discovered a radioactive leak last Wednesday in the primary cooling circuit of its Civaux nuclear plant in southwestern France, the company said, adding there was no safety risk and no radioactivity was measured outside the plant.
The leak could delay the reactor's planned Jan. 8 restart, an industry source familiar with the situation told Reuters on Monday.
"It is too soon to establish what impact this hazard will have on the duration of the reactor's standstill," EDF said, adding it was premature to suggest this would delay the reactor's restart.
The Civaux 1 1,500-megawatt reactor has been shut since August 2021 for scheduled 10-year maintenance. Work on the plant had already been delayed by a week and EDF now faces "a potential major further delay," the industry source familiar with the situation told Reuters.
Nuclear regulator ASN said EDF had to hand over a report on the incident before any decision could be taken on any timing of the restart.
Civaux 1 is among a series of reactors that EDF hopes to restart early enough to be able to produce sufficient power this winter.
EDF said in a statement on Thursday last week that the leak happened during a hydraulics test aimed at verifying the sealing and resistance of piping, welding and valves of the reactor's primary circuit.
"As the pressure reached 190 bar and the temperature 95 degrees Celsius, steam has escaped into the reactor building and simultaneous depressurisation of the primary circuit was registered," EDF said.
The company said no staff had been in proximity of the leak while it happened, that the incident had caused no injury or contamination of people and that no radiological activity had been registered outside the plant.
"A leak on the circuit has been confirmed. The water was caught in dedicated recipients and is confined within the reactor building," EDF said, adding there had been no impact on plant safety.
Although Civaux is one of several reactors affected by corrosion problems, the incident on Wednesday was not linked to that problem or to the works to fix it, the industry source said.
On Thursday, EDF had to lower its 2022 nuclear output forecast again to 275-285 terawatt-hours due to the impact of strikes on reactor maintenance and due to an extension of four reactor outages for repairs linked to corrosion problems.
(Reporting by Benjamin Mallet in ParisWriting by GV De Clercq and Benoit Van OverstraetenEditing by Jane Merriman and Matthew Lewis)