Credit: EDF
On Tuesday 16 July 2024, EDF, the operator of the Cattenom nuclear power plant in France, reported a late detection of the sensor failure measuring the pressure in Reactor 3's turbine.
According to EDF, several sensors continuously monitor the turbine’s operating parameters in the engine room (outside the nuclear zone). The sensors provide information to the system that controls the reactor and the reactor protection system, which can automatically shut down the reactor if the turbine fails.
Between 23 June and 6 July 2024, production Reactor 3 was in operation and several tests and checks were carried out on the four steam pressure measurement sensors. On 6 July, the nuclear power plant teams detected a slight excess of the operating criterion compared to the maximum expected value on one of the sensors (deviation of 1%). This issue caused the sensor to be marked as unavailable, so its electronic card was replaced. The other backup sensors were checked and were still fully functional.
EDF noted that its operating rules prescribe a maximum repair period of three days for this type of equipment. However, the investigations carried out by the teams revealed that the fault in the sensor concerned dates back to March 2024.
This event did not impact the safety of the installations, as the other backup sensors were available and would have worked if the turbine failed, the EDF stressed. However, the late detection of the sensor fault was not in compliance with the EDF’s operating rules. On 12 July 2024, the management of the Cattenom power plant reported this as a significant safety event at level 1 on the INES scale, which goes up to 7, to the Nuclear Safety Authority.
