Exposure of a worker in excess of the statutory dose limit
On 31 October 2022, ASN was informed by Aperam Stainless France of a significant radiation protection event which had occurred on 28 October 2022 on its Gueugnon site, concerning the accidental exposure of a worker to ionising radiation.
The impacted worker was carrying out maintenance work close to an X-ray generator used to measure the thickness of steel sheets. The X-ray generator was operating while the maintenance work was in progress, whereas it should have been switched off in order to avoid all risk of accidental exposure of the maintenance personnel. The worker was exposed for about twenty minutes, with part of his body being directly within the radiation beam for about five minutes.
This worker was employed by a contractor for activities which do not normally entail any risk of radiological exposure, held no Labour Code classification, and was not subject to any individual dosimetric monitoring, which is compatible with his presence in this zone if the X-ray generator had indeed been switched off for the duration of his work.
The dosimetric reconstruction carried out following the incident, as part of the medical care given to the worker, concluded that a whole body effective dose of about 0.2 millisieverts (mSv) had been received, as well as an equivalent dose to the skin of about 2 Sieverts (Sv) on a highly localised surface area, corresponding to that directly exposed to the beam.
Although the whole body effective dose does not exceed the statutory annual limit for a non-classified worker, this equivalent dose to the skin exceeds the statutory annual exposure limit for workers, set by the Labour Code at 500 mSv (average dose on any 1 cm2 surface area of skin, whatever the surface area exposed). The exposure received by this worker led to no immediate health effect, cutaneous in particular (burn, necrosis, etc.); however, given the highly localised but significant exposure of a part of the body, the need for specific medical follow-up will be examined.
The Aperam Stainless France company has initiated an analysis of the causes of this event in order to implement appropriate corrective measures.
In order to check the investigations being carried out and the ongoing analysis of the event, along with the steps taken or planned by the company to prevent such an event from happening again, ASN will shortly be conducting an inspection on the Gueugnon site.
Furthermore, ASN underlines that the heads of "ordering customer" companies must ensure the overall coordination of the risk prevention actions implemented for their workers, but also for the workers of contracted companies performing work on their site.
In view of the fact that one of the statutory exposure limits for a worker has been exceeded and considering the information currently available, ASN rates this event level 2 on the INES scale (international nuclear and radiological events scale, graded from 0 to 7 in increasing order of severity). This rating could be reviewed depending on the conclusions of the examinations currently under way.
- The exposure limits concerning a member of the public (annual effective dose greater than 1 mSv and average annual equivalent dose on the skin greater than 50 mSv for any 1 cm surface area of skin, whatever the surface area exposed) were therefore applicable to this person.
Date of last update : 13/12/2022