On 14 October 2009, French nuclear regulator ASN suspended decommissioning of the so-called ‘Atelier de Technologie du Plutonium’ or ATPu, roughly translated as plutonium technology workshop, located at French nuclear R&D organisation CEA’s plant in Cardarache, France. The ATPu facility was operated for 40 years to produce MOX fuel.

The CEA informed ASN that the amount of plutonium deposits in the facility glove boxes was underestimated. The amount of plutonium deposits during the facility operation was estimated to about 8 kg by the CEA. The amount of plutonium collected during dismantling activities greatly exceeds this value and is currently reaching 22kg, according to ASN.

In a report on the IAEA INES website, the ASN said:

“This incident has no impact on the environment nor on the public. However, the underestimation of the amount of plutonium has led to deeply reduce the security margins provided by the facility design to prevent a criticality accident.

ASN has sent a record to the public prosecutor for failure to observe the terms of incident notification, as prescribed by regulations.

ASN considers that the failure to detect this underestimation of fissile material amounts during dismantling activities and the late notification of this incident to ASN have revealed weaknesses in the safety culture of both the licensee and the operator. Consequently, ASN has decided to rate this incident at level 2 on the INES scale.”

In a press conference on 15 October, CEA director general Bernard Bigot said that there were 450 gloveboxes being dismantled.

He disputed the significance of one of the ASN’s primary complaints, that it has discovered that the CEA has been aware of the incident since June 2009.

He said that the CEA orally reported that more plutonium was being found than expected in the course of dismantling the first gloveboxes to regulators in June and July. But it was decided at the time to wait to try to give the ASN an overall estimate based on the total amounts of plutonium expected, rather than a partial report based on the amount of plutonium found.

The ATPu is operated by AREVA NC and the license holder of this facility is the CEA.

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