This Thursday, September 5, the Nuclear Safety Authority (ASN) put an end to the suspense. The automatic shutdown of the EPR reactor in Flamanville, in the Manche, shortly after its start-up, followed “a human error” in the configuration of electronic systems. The cause was the operating mode which was “not strictly respected” according to the ASN.
“A bad configuration”
After obtaining the green light from the nuclear police, EDF was able to carry out the first nuclear reaction inside the production unit on Tuesday. A crucial step in the start-up of the European pressurized reactor. By the end of autumn, it was due to produce its first electrons on the network, no less than twelve years after the initial date set by the calendar. But barely started up, the reactor went into automatic shutdown on Wednesday.
How could this sudden interruption have occurred? “As part of the tests to be carried out for the start-up of the EPR after the divergence [NDLR : la première réaction nucléaire en chaîne ]the operator must modify a certain number of parameters of the control command. However, during one of these operations, an incorrect configuration of the electronic systems took place, which led to the appearance of a certain number of alarms and the automatic shutdown of the reactor”, explained the ASN to AFP. According to several experts interviewed by Agence France Presse, this type of hazard can occur during reactor start-up tests. A process known to be complex.
Towards a revival of divergence
On the evening of the incident, the EDF group spokesperson spoke out, informing that the teams were carrying out “the necessary technical checks and analyses”, were following “the usual procedures and will then relaunch the reactor divergence”. This Thursday, September 5, the analyses were still in progress. According to the group, this setback “could be linked to an inappropriate configuration of the installation which would have led to the automatic shutdown of the reactor in accordance with the device provided for in the design”.
The ASN, for its part, ensured that the population was reassured, ruling out any safety risk. “From a physical point of view in the core, the neutron reactions remained permanently under control, and no physical hazard that could lead to an automatic shutdown of the reactor was encountered before the aforementioned automatic shutdown,” the spokesperson for the Nuclear Safety Authority was keen to stress.