External contamination of a worker leading to exceeding of the annual statutory dose limit for the equivalent dose to the skin

On 2 February 2023, this worker was reinstalling thermal insulation on valves of various systems in the building of reactor 3, which was shut down for inspection and repair work linked to the stress corrosion (SC) phenomenon. The radioactivity check performed on leaving the controlled zone detected skin contamination on the worker's cheek. The worker received immediate medical attention and the radioactive particle causing the contamination was removed.

For workers likely to be exposed to ionising radiation in the course of their professional activity, the annual statutory dose limits for twelve consecutive months are 20 millisieverts for the whole body and 500 millisieverts for a skin surface area of 1 cm².

EDF evaluated the received dose by retracing the path and activity of the worker within the reactor building. This evaluation gives a dose at the worker's cheek exceeding the regulatory limit set for the equivalent dose to the skin. The whole body dose received by the worker, however, is well below the annual statutory dose limit .

Due to the exceeding of an occupational regulatory exposure limit, this event was rated level 2 on the INES (International Nuclear and Radiological Events Scale) scale.

As soon as the contamination was discovered, the licensee took action to identify the cause. However, the radiological checks carried out in the places where the worker had been revealed no particular anomaly.

ASN conducted an on-site inspection on 9 February 2023. The inspectors verified that EDF had taken all the necessary measures to manage the event appropriately and to analyse its causes. An event analysis report setting out the corrective actions put in place to prevent its recurrence is to be transmitted to ASN within two months.