According to a message on the EDF website, unit 3 at Flamanville NPP is now expected to achieve full power “before the end of autumn 2025”. Previously it had been scheduled for this summer.
The 1630 MWe (net) EPR pressurised water reactor was first connected to the grid in December 2024. It was taken offline in February for checks and maintenance operations and reconnected to the power grid on 19 April. The plant resumed operation at a lower level of 90 MWe, according to EDF, and tests at various power levels were carried out with full power scheduled for mid-year.
“After its next reconnection to the grid, the Flamanville 3 teams will continue the testing phase before commissioning with an objective to reach full capacity before the end of autumn 2025,” the EDF message says. “At the end of this testing period, the unit is expected to be operated at 100% capacity until the first planned outage for maintenance and refuelling, called Visite Complète 1 (VC1). This first planned outage should mainly take place in 2026. Its organisation, content and subsequent duration are under construction.”
During the February-April shutdown, EDF carried out work on a cooling system, the turbo-alternator unit and in a number of other areas necessary to ensure a safe power-up sequence. EDF said adjustments had been made to the bearings guiding the turbine rotors, adding that more than 1,500 safety criteria are assessed during initial startup, which can require several planned stoppages or unexpected adjustments.
Construction of Flamanville 3 started in 2007 and the plant was originally expected to be completed in 2012. The unit is some 12 years overdue and the expected final construction costs have increased from an initial estimate of €3.3bn ($3.7bn) to over €13.2bn.
The project faced a series of problems. In 2022, work was needed following repairs on welds that proved to be more complicated than expected. EDF attributed that delay to additional studies needed to establish a new process for the stress-relieving heat treatment of some welds that were subsequently upgraded. In addition, components for the complex design had to be retooled, some after complaints from l’Autorité de Sûreté Nucléaire (ASN – Nuclear Safety Authority).
In April Ouest-France reported that EDF has decided to fully restructure the core of the EPR to prevent possible problems of fuel rods leaks. This decision was based on the experience of the Taishan NPP in China, which experienced such problems during its second production cycle.
It is necessary to regulate disturbances of neutron flux at the bottom of the reactor vessel, a problem that risks fuel rod leakage. As a preventive measure, the core of the EPR reactor in Flamanville will therefore be restructured with reinforced fuel after its first shutdown at the end of 2026 or early 2027, Ouest-France cited EDF as saying.
Taishan 1&2 were the first two EPR reactors to be built in China. The project is owned by the Guangdong Taishan Nuclear Power Joint Venture Company Limited (TNPJVC), a joint venture between EDF (30%) and China General Nuclear. Construction of the units began in 2009 and 2010 and they began commercial operation in 2018 and 2019, some five years behind schedule.
In 2021, an increase in radiation levels was detected in the primary circuit of Taishan 1. The increase was caused by damage to the cladding in a small number of fuel rods, which China’s Ministry of Ecology & Environment said was normal during the production, transportation and loading of fuel. It estimated that around five of more than 60,000 fuel rods in the Taishan 1 reactor core had been damaged.
