EDF has reported a level 1 alert to the Nuclear Safety Authority (ASN) following the delayed discovery of a sensor fault at the Cattenom nuclear power plant (Moselle), as revealed on Thursday.
Delayed Detection Prompts Safety Declaration
In a statement on its website, EDF announced it had “declared a significant safety event at level 1 on the INES scale” to the ASN on Friday.
The cause was the “late detection” of a fault in a sensor monitoring the operating parameters of the turbine in one of the plant’s production units.
The fault was discovered on July 6th during tests and inspections, where the sensor was deemed unavailable. However, investigations revealed that the defect dated back to March, significantly exceeding the “maximum repair time” of “three days for this type of equipment,” the energy company specified.
Sensor’s Role in Reactor Control and Protection
“The information provided by these sensors is used both by the control system for reactor operation and by the reactor protection system, which can trigger automatic reactor shutdown commands in the event of a turbine failure,” explained EDF.
The INES scale has eight levels, ranging from deviation (0) to major accident (7). Around a hundred level 1 events are classified each year in France, according to the ASN.
“This event had no actual impact on the safety of the facilities, as other redundant sensors remained available and would have ensured their function in case of turbine failure,” assured EDF.
Cattenom Power Plant and Its Significance
The Cattenom power plant is located near Thionville, north of Metz. According to the ASN, the site comprises four pressurized water reactors, each with a capacity of 1300 megawatts, commissioned between 1986 and 1991. They produce approximately 37 TWh annually, representing about 7% of EDF’s national production.