Electricite de France SA’s plan to bolster the concrete base of its oldest reactor would be a world first and could be extended to the rest of its French reactor fleet, the atomic safety regulator said.
EDF, which operates all of the country’s 58 reactors, has submitted a plan to the Autorite de Surete Nucleaire to carry out a project to thicken the base of the 900-megawatt Unit 1 of the Fessenheim plant in eastern France. The regulator, which ordered EDF to improve safety or shutter the reactor by the middle of 2013, could rule within two months on whether the plan is viable.
The utility is having to increase spending at reactors after stricter safety measures were brought in following the Fukushima disaster and also to extend the lives of existing plants. The state auditor has estimated EDF will have to invest 55 billion euros ($70 billion) through 2025.
The concrete slab of the Fessenheim reactor, which began operating in 1977, is thinner than those at other plants. When the ASN watchdog gave the utility permission in 2011 to operate the reactor for another decade to 40 years, it ordered the base to be strengthened to contain a core meltdown and breach of the reactor vessel. EDF has said the work will be carried out even though the government has slated the plant for closure by the end of 2016.
“No one has ever done this before,” Andre-Claude Lacoste, outgoing head of the ASN, said in an interview. “It isn’t extraordinarily complicated, but it will be very delicate work.”
EDF’s choice of concrete and methods to limit the radiation doses received by workers during the operation are among issues being considered by the safety authority. Another is whether the reactor base should be enlarged to allow a catchment area for the spreading and cooling of the molten mix of nuclear fuel in the event of a meltdown, Lacoste said.
The lava-like mixture, known as corium, accumulated at the bottom of the reactor vessel in the 1979 Three Mile Island accident in the U.S. In the case of Chernobyl, it spread into the reactor building basement. Areva SA’s so-called third generation EPR reactor model, which EDF is developing at Flamanville in Normandy, has a metal corium recovery system designed for catchment if the vessel cracks, according to its website. The barrier aims to prevent radioactive fuel from leaking.
“The base at Fessenheim was originally built as a foundation for the reactor, it wasn’t developed with the idea of containment for the corium,” said Lacoste, who is retiring from the ASN today.
A similar operation will “most probably” have to be carried out on Unit 2 and the same deadline may apply, he said.
The safety authority is considering EDF’s proposal to add to Fessenheim’s corium containment and this operation “could be an option” for all of the utility’s other reactors in order to gain approval to operate them for 60 years, ASN director Jean-Christophe Niel said in a separate interview.
EDF Chief Executive Officer Henri Proglio has said the utility wants to operate its reactors for six decades. The utility has estimated the cost of reinforcing the base of Unit 1 at Fessenheim would be about 15 million euros.
Jill Coulombez, a spokeswoman for EDF, confirmed the utility’s plan for Fessenheim is being considered by the ASN, although she declined to comment on whether the new safety measure could be rolled out at other plants.
Fessenheim has emerged as a flashpoint for debate over France’s future dependence on nuclear power. President Francois Hollande, who campaigned to cut reliance on nuclear generation to 50 percent by about 2025 from more than three quarters at present, has ordered a permanent shutdown of the plant at the end of 2016. The safety authority said EDF won’t automatically gain approval to operator reactors for 60 years.
“It’s not a given at this stage,” Pierre-Franck Chevet, who will replace Lacoste, told a parliamentary hearing Nov. 6. An answer will come at a “technical rendezvous” in 2015.
“The life extensions must take into account new generation reactors with higher standards,” he said. “The French approach is to try to get as close as possible to the best technology available.”