France's nuclear regulator, the ASN, has been informed by Areva NC subsidiary Socatri that it has exceeded its annual limit for releases of carbon-14 (C-14). ASN has ordered the company to suspend all its activities that generate the long-lived radionuclide until the end of 2008.
|The Tricastin complex (Image: IRSN)
On 4 July, following the processing in June of solid waste on behalf of French radioactive waste management agency Andra, Socatri discovered that it has exceeded its monthly limit for C-14. The company informed Nuclear Safety Authority (Autorité De Sûreté Nucléaire, ASN) and immediately stopped work at the waste treatment facility at the Tricastin nuclear complex in the Rhone valley. However, gaseous releases of C-14 continued.
Socatri began analyses to determine the nature of the release. The results showed that it had exceeded its annual limit for C-14 releases by 5%. Socatri informed ASN on 5 August that it had exceed its limit and ASN subsequently prohibited the company from performing any activity that would result in further C-14 releases until the end of the year.
According to the ASN, initial estimates indicate that the impact of the releases on the environment and local population was "very low, around a few microsieverts, or less than a few thousandths of the permissible annual dose to the public." The ASN has classified the incident as Level 1 on the International Nuclear Event Scale (INES), an 'anomaly.'
The ASN has requested that the Institute for Radiological Protection and Nuclear Safety (Institut de Radioprotection et de Sûreté Nucléaire, IRSN) conducts an assessment of the impact of this event and to make measurements of radioactivity in the environment.
Socatri specialises in maintaining and dismantling nuclear equipment while cleaning and recovering uranium contamination. The company, on behalf of Andra, provides storage, sorting and packaging of very low-level radioactive waste from "small producers" of nuclear waste, including hospitals and research laboratories.
Socrati's facilities at Tricastin were the scene of an earlier incident, when a leak of 74 kilograms of uranium occurred on 7 July. Some 30 cubic metres of a solution including 12g of uranium per litre escaped from an overflow tank and drained away into the ground. Areva said this was during a draining operation at a water treatment installation, downstream from the George Besse uranium enrichment plant. That incident was also graded at Level 1 on INES scale. The ASN has criticised Socatri for its handling of that incident.
Tricastin is a very large nuclear site, home to four power reactors, the Comhurex uranium conversion facility, the Eurodif enrichment plant and the Pierrelatte weapons facility, operated by the Atomic Energy Commission, (Commissariat à l'énergie atomique, CEA).