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 for the operators to have the necessary tools to verify that the equivalent dose rate outside the work zone is that which is expected (deviations observed in one in four inspections in 2024), more specifically by taking one or more measurements with a functional dose rate meter whose calibration has been verified (deviations observed in one in ten inspections in 2024), and recording the results. Cordoning off the work zone effectively constitute the main safety barrier in worksite configurations, 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 (in nearly one in three inspections in 2024) 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 nonconformities, even if few deviations are found during the inspections of components of the safety, signalling and alarm system. ASN considers that the risks of incidents and the workers’ occupational exposure are generally well controlled by the companies when radiography is performed in a bunker complying with the applicable regulations. France has a good network of permanent industrial radiography facilities, despite some regional disparities. The figures in 2024 stand at: ∙97 licensed gamma radiography facilities (39 gamma radiography facilities and 58 combined facilities, that is to say which can accommodate either gamma ray projectors or electrical devices emitting X-rays or particle accelerators); ∙511 licensed X-ray radiography facilities (447 facilities using electrical devices, Loss of control of a gamma ray project in Colmar (Haut-Rhin département) with off-site consequences On 10 April 2024, during an industrial radiography operation conducted at the end of the day by a contractor in the ordering customer’s facility in Colmar (Haut-Rhin département), control of the iridium-192 gamma radiography source was lost during the first exposure. The ensuing high equivalent ambient dose rate led to the intervention of the Prefecture to coordinate the action of the emergency services (fire brigade, police force, civil protection, ASN, etc.) and the setting up of a no-go area extending beyond the boundary of the ordering customer’s site, leading to the evacuation of neighbouring companies and homes (an extremely rare decision given that events involving loss of control of gamma radiography sources usually have no impact on the public). The following day, the intervention of the gamma ray projector manufacturer, the fire brigade and the civil protection services succeeded in decreasing the ambient equivalent dose rate, enabling the no-go area to be considerably reduced (to within the bounds of the ordering customer’s site) and the evacuation order to be lifted. During a subsequent intervention, the manufacturer managed to regain control of the gamma radiography source and safely take it away. The reactive inspection by ASN revealed insufficient preparation and coordination between the radiography contractor and the ordering customer when determining the conditions of the industrial radiography work, which was decisive in the chain of events that led to the setting up of a no-go area extending onto public land. First of all, the optimisation approach was not stringent enough given the dense site environment (first exposure done without using an ionising radiation collimator which could have been replaced by several exposures with a collimator, especially given that the delimiting of the work area for this exposure extended substantially beyond the limits of the ordering customer’s site). In actual fact, firstly the work area effectively put in place was not the area planned for the exposure without a collimator but a smaller area intended for the subsequent exposures (planned to be carried out using a collimator); and secondly there was no verification of the equivalent dose rate at boundary of the area. Lastly, as is found regularly during ASN’s worksite inspections, the prevention plan was incomplete, more specifically given the particular nature of the operation with inadequate equipment at the operators’ disposal, be it for the performing the radiography work or for managing an emergency situation (in particular, no lead mats available). For further information on the event, refer to the information notice and its complement published by ASN on its website. Loss of control of the source in gamma radiography Loss of control of the source (“source jamming”) is one of the main causes of incidents in this area of gamma radiography. It can lead to significant exposure of the workers situated nearby, or even of the public when working in urban areas. This loss of control is primarily encountered in two situations: • The radioactive source remains jammed in its guide tube. The cause of the blockage is often the presence of foreign bodies in the tube, or deterioration of the tube itself. • The front of the projector is not fully blanked due to either the presence of foreign bodies in the channel preventing full retraction of the source, or breaking of the plug. In France, gamma radiography projectors comply with technical specifications that are stricter than the international ISO standards. However, equipment failures can never be ruled out, especially in the event of poor upkeep of the equipment. In the last few years, incorrect manipulations have also been observed further to “source jamming” incidents. ASN Report on the state of nuclear safety and radiation protection in France in 2024 265 11 12 13 14 15 AP 10 09 Sources of ionising radiation and their industrial, veterinary and research applications 08 01 02 03 04 05 06 07
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