ASN Classifies Plutonium Inventory Incident As INES Level 2
Written by NucNet
Friday, 16 October 2009
France’s nuclear safety authority (Autorité de Sûreté Nucléaire, ASN) has suspended decommissioning operations after discovering that an inventory of plutonium at a former mixed oxide (MOX) fuel manufacturing facility in southern France was much higher than thought.
ASN said the Atomic Energy Commission (Commissariat à l’Energie Atomique, CEA) discovered that plutonium deposits inside glove boxes at its Atelier de Technologie du Plutonium (ATPu) facility at Cadarache had been underestimated as early as June 2009, but the CEA had failed to notify the ASN of the underestimation until earlier this month.
The CEA is the plant’s licence holder and it is operated by Areva NC, the fuel cycle division of energy company Areva. ASN said the failure to detect the underestimation of fissile material and the late notification of the incident revealed “weaknesses in the safety culture of both the licensee and the operator”.
ASN said it had decided to rate the incident at level 2 on the International Atomic Energy Agency’s (IAEA) International Nuclear Event Scale (INES).
The ATPu plant, which is now shut down and being dismantled, produced plutonium-containing mixed oxide (MOX) fuel pellets for 40 years.
The amount of plutonium deposits that had gradually built up in inaccessible parts of the glove boxes during the facility’s operation was estimated by the CEA to be about 8 kilogrammes (kg). However, around 22 kg of plutonium deposits have been recovered since decommissioning began in March 2009 and the CEA now estimates the total could be in the region of 39 kg.
ASN performed a comprehensive inspection at the ATPu facility on 9 October 2009 and said the inspection confirmed that the CEA had known of the incident since June 2009.
On 14 October 2009, ASN decided to suspend the ATPu facility dismantling activities, pending verification of the amount of fissile material.
In a statement on 15 October, CEA said that inspectors from the safety authorities had been told about the issue in early July. CEA also said that no undue risk had been taken during the dismantling operations.
The incident has had no impact on the environment or the public, but an incident report on the IAEA’s INES website said the underestimation of the amount of plutonium has deeply reduced security margins designed to prevent a criticality accident.
