(Read 30 cm (not 3 cm) in §20)
by Benjamin Mallett
PARIS (Reuters) – Companies working to refurbish reactors affected by corrosion problems at EDF are planning to raise the limits of radioactivity to which some of their technicians are likely to be exposed in order to help the group meet its deadlines, we learned from EDF.
While the new limits remain well below the regulations and the levels from which a health hazard is identified, this unusual measure illustrates the race against time in which France is engaged to restart as many reactors as possible before winter, in a context of energy crisis which is weakening its electricity system and those of its European neighbours.
EDF explained in written statements that each employer whose employees are subject to the effects of ionizing radiation had to, under the labor code, set a “dose constraint” not to be exceeded for these employees, to “promote a ambitious approach to dose reduction” below the threshold of 20 millisieverts (mSv) per year, set by the regulations.
“The activities currently carried out on our facilities lead to an increase in the number of hours worked in the nuclear part of our facilities, this additional activity had not been considered by our partners when establishing their ‘constraint of dose'”, added EDF, in response to questions from Reuters.
“We have been informed by some of our partners that they plan to raise this dose constraint for some of their employees. We are thus aware of a situation where it could be raised from 12 to 14 mSv. “
The constraint is 14 mSv per year for EDF employees, a value also adopted by the group’s industrial partners but which some have chosen to set at lower levels, added EDF.
FRENCH NUCLEAR PRODUCTION AT THE LOWEST FOR 30 YEARS
The group also indicated that it had undertaken with its industrial partners “dose reduction actions which apply to stress corrosion sites”, with in particular “thorough rinsing of the circuits before intervention on certain reactors” and the use of ” remotely operated tools”.
Two sources with direct knowledge of the works in progress had previously told Reuters that at least one French service provider, namely the company Monteiro, had raised the exposure limit for some of its technicians – mainly pipe fitters and welders – by 12 to 14 mSv approximately on an annual basis. The millisievert is the unit used to assess the impact of radiation on humans.
A Monteiro spokeswoman said she was unable to comment on this information. Reuters also contacted five other EDF service providers, three of whom did not respond to a request for comment and one did not wish to comment on the subject, while no one could be reached at the last.
The proposed dose limit changes come at a time when EDF wants to restart 15 reactors shut down since last winter as soon as possible after the detection of a “stress corrosion” phenomenon on the safety circuits of certain power plants.
Fourteen other reactors are also shut down, in particular due to conventional scheduled maintenance operations and fuel saving measures, which brings the total unavailability of French nuclear electricity production capacities to 54%. .
While French nuclear production is at its lowest for 30 years, EDF announced Thursday that it has once again revised upwards the estimated impact of the fall in this production on its accounts, which now reaches 29 billion euros on the 2022, against 24 billion announced at the end of July.
The company attributes part of its difficulties to a shortage of qualified professionals and the need to limit exposure to radioactivity in the context of work related to corrosion.
“IT IS NOT BECAUSE WE ARE IN CRISIS THAT WE ARE GOING TO CRAMER THEM”
An adviser to the Ministry for Energy Transition stressed that the Nuclear Safety Authority (ASN) ensured “strictly independent radiation protection for workers”, adding that 14 mSv constituted a minimal dose similar to that caused by two chest scanners.
According to the Institute for Radiation Protection and Nuclear Safety (IRSN), a French person receives a total average annual dose of around 4.5 mSv – due in particular to exposure to natural and medical radioactivity – and, for a level below 100 mSv, no long-term health effects have been demonstrated.
“In health terms, it would be difficult to assess an effect by going from 12 to 14 mSv,” Klervi Leuraud, head of the institute’s research service on the biological and health effects of ionizing radiation, told Reuters.
“As long as we are below the threshold imposed by the regulations, the impact on health is difficult to qualify. It would be difficult to observe an increase in the risk of cancer for a population which would be exposed to low levels like these.”
Sources interviewed by Reuters stressed that work related to the welding problems was taking place in areas with high levels of radioactivity but the aim remained to minimize technician exposure.
“We try to maintain respect for this principle and it is not because we are in crisis that we are going to burn them,” said one of the sources.
AMERICAN WELDERS AS REINFORCEMENT
“We are in constrained environments, we repair pipes that are 30 centimeters in diameter in places that are no bigger than Parisian studios. We try to secure our profession and our interventions, but there are hazards. Our schedules have margins, but sometimes those margins aren’t enough,” the source added.
“You have to rotate the staff and the problem with these highly specialized trades is that the number of people with the required level of skills is limited.”
EDF calls on several hundred specialists employed by six French companies as well as welders working for two American companies, including Westinghouse.
“Experienced North American teams, usually working with one of our industrial partners, will be able to intervene on the nuclear fleet, as part of work related to stress corrosion. This situation is not exceptional”, according to the group .
EDF also had to order replacement pipes from Italian companies but, according to the sources, some were not made to the correct dimensions.
The group, however, indicated that the elements ordered from its steel suppliers were “raw parts” which must be systematically reworked.” This is a normal industrial process and no raw part is ever supplied at the final dimension. “
FOR CIVAUX, “THE SCHEDULE IS HELD”
In addition, the work related to corrosion problems generally involves complex control procedures which do not make it possible to speed up the worksites. A single weld, for example, represents around three days of work and requires hundreds of document signatures, according to sources interviewed by Reuters, which EDF did not comment on.
The government has publicly urged the group to stick to its maintenance schedule, with EDF believing that it will be able to restart enough reactors by early 2023 to ensure nuclear production levels in line with those of the last year.
While some analysts believe his timetable may prove to be too optimistic, one of the sources said that a six-week deadline was expected to complete the remaining welds of the Civaux reactor n ° 1, which seems to him “unrealistic” .
“The maintenance and repair schedules take into account the realization of current and future activities. With regard to Civaux, the schedule is kept,” EDF told Reuters on Friday.
(With contributions from Elizabeth Pineau, Forrest Crellin and Matthieu Protard)