EDF begins start up process for Flamanville EPR

Workers at the Flamanville EPR have begun the process required for achieving the first nuclear reaction in the reactor following approval from the French nuclear regulator. The reactor is expected to be connected to the grid in the coming months.

The Autorité de Sûreté Nucléaire (ASN) on 7 May authorised the commissioning of the Flamanville EPR reactor, clearing the way for EDF to begin loading the 241 fuel assemblies into the reactor and to carry out start-up tests and subsequent operation of the reactor. The loading of fuel was completed on 22 May.

"After loading the reactor last May, Flamanville EPR teams carried out numerous technical tests and put the facilities into the required conditions to initiate nuclear fission," EDF said today.

On 30 August, EDF sent ASN the information required to issue an agreement for the first nuclear reaction - referred to as 'divergence' - to proceed, in particular the results of the installation tests carried out since the commissioning authorisation.

In a resolution of 2 September, ASN authorised the launch of divergence operations at the Flamanville EPR reactor. "The examination of EDF's request and the checks carried out by ASN did not reveal any factor likely to call into question EDF's ability to diverge the reactor," ASN said.

EDF said divergence involves creating a stable nuclear reaction at very low power. It is achieved by reducing the boron concentration in the primary system's water, then gradually raising the reactor core's control rods. When neutron production is higher than absorption, divergence will be achieved and the chain reaction will start. The chain reaction's intensity and thus the reactor's power will be controlled by the control rods and the boron concentration. Once divergence is completed, the reactor will be at 0.2% of its rated power.

In a post on LinkedIn, Xavier Ursat, EDF Group Senior Executive in charge of Engineering and New Nuclear Projects Division, announced that the nuclear reaction at Flamanville 3 was initiated at 3.54pm on 3 September.

A test programme to achieve a power level of 25% will be implemented when the reactor reaches 0.2% power, EDF said. Once at 25% capacity, the Flamanville EPR will be connected to the national electricity grid for the first time and will generate electricity. "This first connection is scheduled before the end of autumn 2024," the company noted. "Testing will continue throughout reactor ramp-up, which will be carried out in successive stages over several months."

ASN said it will monitor the subsequent stages of the reactor's start-up, until it reaches its rated power. "In particular, EDF will have to seek the agreement of ASN to go through certain stages of the reactor's ramp-up," it said.

Construction work began in December 2007 on the third unit at the Flamanville site in Normandy in northern France - where two reactors have been operating since 1986 and 1987. The dome of the reactor building was put in place in July 2013 and the reactor vessel was installed in January 2014. The reactor was originally expected to start commercial operation in 2013 but has faced a series of delays.

The first EPR units came online at Taishan in China, where unit 1 became the first EPR to enter commercial operation in 2018 followed by Taishan 2 in September 2019. In Europe, Olkiluoto 3 in Finland entered commercial operation in 2023 and two units are under construction at Hinkley Point C in the UK.

EDF also announced that it has raised its estimate for nuclear power generation in France in 2024. Initially estimated between 315-345 TWh, nuclear power generation is now estimated between 340-360 TWh.

Is said this higher estimate is based on "improved performance of outages and industrial control of stress corrosion inspections and repair work, and the absence of major climatic event during summer".

EDF noted that since early 2024, eleven reactors have been reconnected to the grid before the scheduled date.