22 Nov (NucNet): France’s nuclear regulator says it has extended the deadline for checks to be carried out by operator EDF on the Bugey-5 nuclear plant in eastern France.
The Autorité de Sûreté Nucléaire (ASN) said the deadline extension did not have any safety implications and the 880-MW pressurised water reactor remains in cold shutdown.
The checks include pressure and leak tests of the unit’s safety containment. ASN said these tests have been delayed because EDF detected a leak during an earlier test and needs to repair it before new tests can be carried out.
EDF also needs to add equipment which prevents the containment from rupturing or breaking in the event of the failure of thermal insulation on a primary motor pump. Modifications need to be carried out on the containment’s passive equipment, valves and pipe supports, ASN said.
In December 2015, ASN asked EDF to submit details of work it planned to carry out to resolve defects in the inner, metallic liner of the Bugey-5 reactor containment building.
ASN said EDF must provide the information before restarting the reactor.
Significant leaks from the containment were seen during a pressure test carried out in 2011 during the unit’s third decennial inspection.
In December 2014, ASN said new tests of the containment should be carried out during the reactor’s next shutdown. EDF carried out these tests during a shutdown for preventive maintenance and fuel loading which began on 27 August 2015.
ASN said the tests showed there had been further degradation of the inner liner of the containment since the previous tests. Leaks were also found in the lower part of the reactor building.
ASN said EDF submitted on 7 April 2016 a safety case detailing proposals on how to deal with the containment issue. ASN said the safety case is “technically complex” and is being reviewed by ASN and its technical support organisation, the Institute for Radiological Protection and Nuclear Safety (IRSN).
Bugey-5 began commercial operation in January 1980. The Bugey station has four commercial nuclear units.