[Webinar] Relive the Historic First Criticality of Flamanville 3 EPR

On Tuesday, September 3rd, the 57th reactor of the French nuclear fleet achieved criticality. To celebrate this historic milestone in the nuclear energy ecosystem, the French Nuclear Energy Society (SFEN) organized a webinar to discuss the key stages of this first criticality and the upcoming steps in the following weeks.

After receiving the green light from the Nuclear Safety Authority on September 2nd, the teams mobilized successfully achieved the reactor’s criticality at 15:54 on Tuesday, September 3rd. This marks a historic moment as it is the first start-up of a new reactor in France in 20 years and it is also the 4th EPR to be commissioned in the world (after the two in Taishan, China, and the one in Olkiluoto, Finland). To celebrate this event, SFEN organized a webinar with Gregory Heinfling, Plant Director of Fla3 at EDF, Fabien Hensch, Fla3 Project Director at Framatome, and Loïc Andries, a research engineer in neutron physics at Framatome, to discuss the startup of Fla3 and the next steps.

Reactor Divergence

Since the fuel loading in May, the Flamanville 3 EPR has entered its “start-up phase,” a process that is carried out step-by-step and includes a significant commissioning program with nearly 200 test procedures. It is conducted in constant communication with the nuclear safety authority. The team successfully achieved the first criticality on September 3rd, marking the start of zero-power physics tests, which will measure the core’s parameters against theoretical values.

In the main control room, responsibilities are shared among different teams. “The Framatome teams conduct and carry out the tests according to the program, ensure the post-processing calculations, and analyze the results’ compliance with the design assumptions. EDF’s design and commissioning team supervises the tests and the compliance of their results with safety criteria, while EDF’s operations team, i.e., the future reactor operating team, performs all operations, technically and practically, from the main control room or on the reactor site itself, thus verifying the parameters against the technical operating specifications,” detailed Gregory Heinfling. In total, more than 1,000 people are mobilized during the commissioning phase.

Shortly after the reactor’s divergence, there was an unexpected shutdown. This event was due to human error during the initial tests, but all safety protections functioned as planned. The teams analyzed the incident to improve procedures and training to capitalize on the experience for the future and future projects. It was clarified that such unexpected shutdowns are common during startup phases.

Next Steps

Subsequently, the next testing phases will continue on the reactor core, as well as on the secondary systems and the turbine. Once the turbine and associated systems are fully validated and the EPR reaches 25% of its nominal power, it will proceed to connect to the grid. Again, many additional tests will be conducted thereafter up to 60% and then 100% power. ■