3.1.1 The different methods used Gamma radiography Gamma radiography devices usually contain high-activity sealed sources, mainly iridium-192, cobalt-60 or selenium-75, whose activity can reach about twenty terabecquerels. A gamma radiography device is usually a mobile device which can be moved from one worksite to another. It consists primarily of: ∙ a source projector, which acts as a storage container and ensures radiological protection when the source is not in use; ∙ a guide tube which guides the movement of the source up to the object to be examined; ∙ and a remote control cable allowing remote manipulation by the operator. When the source is ejected out of the projector, the dose rates can reach several grays per hour at one metre from the source, depending on the radionuclide and its activity level. As a result of the activity of the sources and the movement of the sources outside the storage container when the device is being used, gamma radiography can entail significant risks for the operators in the event of incorrect use, failure to comply with radiation protection rules, or operating incidents. Furthermore, these gamma radiography activities are often carried out on work sites under difficult conditions (working at night, or in places that are exposed to the elements, or in cramped spaces). This is therefore an activity with serious radiation protection implications that figures among ASN’s inspection priorities. Industrial X‑ray radiography Industrial X‑ray radiography devices are very varied, ranging from fixed devices (integrated in a facility of very variable size) to worksite devices which can be used equally well in worksite conditions as in a facility. In application of the principle of optimisation, they must be used instead of gamma radiography devices when the conditions so permit because they do not make use of a radioactive source. Apart from non-destructive inspection, these devices can also be used for more specific and therefore rarer purposes, such as radiography for the restoration of musical instruments or paintings, archaeological study of mummies or the analysis of fossils. 3.1.2 Evaluation of radiation protection Industrial radiography activities are high-risk activities which have been an inspection priority for ASN for several years now. In 2022, ASN conducted 144 inspections in this area, a number that is stable with respect to the three preceding years. Among these inspections, 60 were unannounced inspections on worksites which also include night work. The on-line notification of worksite schedules for industrial radiography companies put in place by ASN in 2014 facilitates the planning of these inspections. ASN notes that virtually all the companies concerned routinely use this system for giving notification of their worksites. The reliability of the information transmitted however, is still very varied. The points to improve include: ∙ the updating of schedules when they are changed or cancelled; ∙ the accuracy of the worksite location information (not to be confused with the address of the ordering company); ∙ the completeness of the worksite notification; ∙ the identification of the device used on the worksite (gamma radiography or X‑ray device). ASN finds that the large majority of companies maintained the necessary rigour to meet the regulatory requirements with respect to the appointing of a radiation protection advisor, worker dose monitoring and radiological zoning of their facilities (less than 10% noncompliance observed). Furthermore, the inspectors noted that the frequency of maintenance of gamma radiography devices on the whole complies with regulations (no non-compliance found for projectors, 7% non-compliance found for accessories). Similarly, nearly all the operators inspected by ASN held, when it was necessary, the Certificate of competence in the use of industrial radiology devices (CAMARI) required by Article R. 4451-61 of the Labour Code (only 3 cases of noncompliance observed, all concerning use in a facility). The inspectors also noted that the efforts made by the companies to train newly-arrived classified workers had been maintained. Consequently, this information was duly dispensed to the new staff in more than 91% of the inspected facilities concerned in 2022. Furthermore, although the inspections found only one noncompliance with the licences issued by ASN concerning radionuclides or maximum activity held, companies must nevertheless be more thorough in checking that their inventory of sealed radioactive sources is consistent with the national inventory held by IRSN. ASN still considers that the deviations observed in cordoning off the work zones on worksites (found in virtually one inspection in three) give cause for concern. ASN underlines that the lack of preparation and cooperation between the ordering customers and the radiography contractors before starting temporary worksites (particularly the failure to draw up a precise prevention plan) is one of the causes of these deviations. ASN points out that the work area must be cordoned off before the work begins and, in all events, before the radiography equipment is installed, that the cordoning off must be continuous and that it is essential to have warning lights in sufficient quantity. To ascertain that cordoning off ensures compliance with the effective dose integrated over one hour set by the regulations, it is vital to take at one or more measurements and to record the results. Zoning and cordoning off effectively constitute the main safety barrier in worksite conditions, particularly to prevent unintended exposures. Consequently, ASN remains extremely vigilant regarding this point, which is systematically checked during worksite inspections. Moreover, penal enforcement actions have already been proposed for serious breaches. The recurrence of the deviations observed in the last few years in cordoning off the work zone induced ASN to address a circular letter to the profession as a whole in 2021, asking for tightened vigilance in this respect. ASN also points out that in the case of gamma radiography, it is vital to approach a measuring device to the projector in order to check that the radioactive source is effectively in the safe position. It is still found too frequently that this check is either not carried out or does not go right up to the tip of the projector (where the guide tube is connected to the projector), which could lead to significant exposures of the operators in the event of an equipment failure. ASN also notes disparities in the quality of the technical files it has to examine for inspection preparation or follow-up, and those received for license applications. The companies must in particular be more attentive to the reports establishing the conformity of their facilities with the appropriate technical baseline requirements. ASN still detects errors too frequently, particularly when production of these reports has been subcontracted, and these errors sometimes lead to non-conformities 252 ASN Report on the state of nuclear safety and radiation protection in France in 2022 • 08 • Sources of ionising radiation and their industrial, veterinary and research applications 08
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