A worker exceeds the regulatory annual radiation exposure limit

On 24 April 2019, ASN, the French nuclear regulator, was informed by the company Eiffage Énergie Système – Clevia Ouest, located in Saint-Grégoire (Ille-et-Vilaine département), of a significant radiation protection event involving a worker who exceeded the regulatory annual ionising radiation exposure limit.

The worker concerned carries out climatic control and energy maintenance services on the sites of customers of Eiffage Énergie Système. Some of these sites perform nuclear activities that can expose the workers (internal or external) to ionising radiation. As a prevention measure, this worker was subject to individual dosimetric monitoring.

The individual dosimetry results indicated that the worker apparently received an effective dose of 156 millisieverts (mSv) between October 2018 and January 2019. As a "non-classified" worker, by virtue of the regulations this person was not authorized to receive an annual dose exceeding 1 mSv. The effective dose measured is to be compared with the regulatory annual exposure limit for "classified" workers which is set by the Labour Code at 20 mSv. Such a dose is not likely to cause an immediate health effect (burn, necrosis, cataract, etc.);  it can however, should it be confirmed, lead to a slight probability of increase in the risk of cancer in the long term.

Eiffage Énergie Système conducted initial investigations into this event, but to date these investigations have not identified the origin of the overexposure. It is possible that the recorded dose is due to incorrect use of the dosimeter and does not correspond to the actual exposure of the worker. The company has nevertheless highlighted malfunctions in the management of the dosimetry devices and in the analysis of results, as well as a lack of radiation protection culture.

In view of the exceeding of the annual exposure limit and considering the information currently available, ASN provisionally rates this event level 2 on the INES scale (international scale of nuclear and radiological events, graded from 0 to 7 in increasing order of severity).

ASN will shortly conduct an inspection into this event to check the investigative measures and the actions taken by Eiffage Énergie Système. ASN will try to ensure that the dose effectively received by the worker is established.

Furthermore, ASN wishes to underline that the heads of "ordering customer" companies are obliged to ensure the overall coordination of the risk prevention actions implemented for their employees and for the workers of outside companies performing work on their site.