Plutonium cleanup suspended after mix-up

Thursday, 15 October 2009

Updated on 16 October to include CEA's response to ASN's statement.

France's nuclear regulator has suspended decommissioning and castigated a plant operator after discovering that plutonium inventory was much higher than thought. The plant owner has now contradicted the regulator's version of events.

 

The Nuclear Safety Authority (Autorité de Sûreté Nucléaire, ASN) said that the Atomic Energy Commission (Commissariat a l'Energie Atomique, CEA) had discovered that plutonium deposits inside glove boxes at the ATPu facility at Cadarache had been underestimated as early as June 2009 but had failed to notify it of the underestimation until earlier this month.

The plant produced plutonium-containing mixed oxide (MOX) fuel pellets for 40 years, during which time it was estimated to contain a total of 8 kg of plutonium in deposits that gradually built up in inaccessible parts of some 450 glove boxes. However, around 22 kg of plutonium deposits have been recovered since decommissioning began in March 2009, and the CEA now estimates that the total could be in the region of 39 kg.

 
Although the incident itself was without any safety consequences, the regulator noted that underestimation of the quantities of plutonium reduces safety margins calculated to prevent criticality accidents: "ASN considers the lack of detection of this underestimation during the operating period of the installation, as well as the late reporting of this event to the ASN, reveal a gap in safety culture."

ASN was further incensed by what it considered the late reporting of the matter. A statement from the regulator said that it had only been informed of the underestimation on 6 October and that its inspection on 9 October it confirmed that the CEA had known about the discrepancy since June. The ASN was highly critical of this delay, which caused it to raise the incident from Level 1 to Level 2 on the International Nuclear Event Scale (INES). However, CEA has since responded with an alternative timeline in which it verbally informed ASN of the discrepancy on 11 June. Furthermore, CEA said that the discrepancy had been recognised by the Euratom inspectors on 23 June as well as other officials from the Institute of Radiation Protection and Nuclear Safety (IRSN) on 1 and 2 July.

   

French energy and ecology minister Jean-Louis Borloo issued a statement calling for "complete transparency" on the situation: "This transparency and safety requirements are essential conditions for the supply of electricity from nuclear sources," he said. "They will be respected."

The ATPu started up in 1964 and was operated by French fuel cycle company Areva from 1991 until its closure in June 2008. The CEA's massive Cadarache site, in the south of France, is about to celebrate its 50th anniversary and is home to some 19 nuclear installations as well as the site of international ITER fusion demonstration project.