A faulty weighing scale and "out of procedure" instructions are the cause of an incident - without consequences for the environment or health - which occurred on November 6, 2006 at the Plutonium Technology Workshop (ATPu). This Areva NC facility is located on the site of the Atomic Energy Commission (CEA), in Cadarache (Bouches-du-Rhône).
"The accumulation of human errors and the failures observed in the quality assurance processes highlight major shortcomings in the operator's safety culture", judges the Nuclear Safety Authority (ASN). This is why ASN announced on Tuesday 9 January that it had classified the incident at level 2 on the international scale of nuclear events, which goes from 1 to 7. The CEA, which had made the incident public on 10 November, proposed to classify it at level 1 of this scale.
A handling error led employees of Areva NC, operational manager of ATPu, to load a shredder twice with scrap MOX fuel pellets (mixture of plutonium and uranium oxides). An ASN inspection, carried out on November 16, showed that the scale used to control the loading of the shredder had been broken since March 2006.
NO "CRITICAL MASS"
Fortunately, the "critical mass" - of about 16 kg of fissile material -, from which a nuclear reaction can start spontaneously, has not been reached. Instead of the 8 kg authorized, the mill contained 13 kg of pellets, corresponding to 3,9 kg of fissile material.
ATPu had experienced a contamination incident in 2004: a human error had caused slight contamination of the premises and of an operator. Opened in 1964, this workshop, where the first MOX assemblies were produced, is now in the renovation phase. ASN hopes to see the operation completed at the end of 2007, and is preparing a decree relating to the final shutdown of the installation.
Placed under the responsibility of the CEA, ATPu has long been the bane of environmental associations. As early as 1995, the Nuclear Safety Authority had asked for its closure due to a reassessment of the seismic risk. It was not until July 2003 that Areva, the real operator of the installation, complied.
source: the Monde.fr