Incident on the ATPu nuclear facility (Cadarache CEA site): the ASN rates incident as level 2, draws up a report and suspends all dismantling operations

The incident that occurred at the ATPu (Plutonium Technology facility), a nuclear facility located at the Cadarache CEA (Atomic Energy Commission) site, and declared by the CEA on 6 October 2009, was rated as level 2 on the International Nuclear Event Scale (INES) – a scale with 7 severity levels – by ASN (French Nuclear Safety Authority) on 12 October 2009. The CEA holds the ATPu’s licence and AREVA runs the facility.

The Cadarache CEA has informed ASN of the underestimation of plutonium deposits in the facility glove boxes. Estimated at around 8kg during the facility operation, the Plutonium deposits discovered to date are, according to the CEA, of approximately 22kg. The CEA further estimates that the total quantity could rise to as much as 39kg.

ASN Marseille local division inspected the ATPu site on 9 October to garner further information on this incident. This inspection confirmed that the CEA was aware of this incident since June 2009.

ASN has requested that an expertise be carried out by the IRSN (French Institute for Nuclear Safety and Radiation Protection), which returned its report on 14 October.

On 14 October 2009, the ASN Commission decided to suspend the ATPu facility dismantling operations accountability (ASN Commission decision No. 2009-160 of 14 October 2009). Resumption of dismantling operations must be subject to prior approval from ASN.

The incident has had no consequences. However, the underestimation of plutonium amount has led to the significant reduction in the security margins provided by the facility design to prevent a criticality accident**, whose potential consequences could be dangerous to workers.

 ASN considers that the non-detection of this underestimation during the facility operation, as well as the late declaration of the event to ASN, point to a significant lack in safety culture from the facility licensee and operator. Consequently, the ASN has rated this event as level 2 on the INES, out of a total of 7.

 ASN has drawn up and sent a report to the facility’s owner for failure to observe non-incident declaration dispositions provided for by the law.

The ATPu is currently being dismantled. During 40 years, its main activity was the production of MOX fuel for nuclear power reactors. The Decree dated 6 March 2009 authorised the decommissioning and dismantling of the ATPu facility. Since that date, the licensee has begun dismantling operations, with the aim of decommissioning the facility. Radioactive waste created by the facility’s past activities had been removed prior to the start of dismantling operations. This removal ended in June 2008, in accordance with an ASN decision.

* A glove box enables the safe access to a containment chamber where nuclear material is used.

** The criticality risk regards the risk of a nuclear chain reaction start-up when a too-large stock of fissile material is located in a same place.