ASN Report 2017

306 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 10  - Sources of ionising radiation and their industrial, veterinary and research applications The reported significant events are of three main types: ཛྷ ཛྷ theft or loss of radioactive sources (29%); ཛྷ ཛྷ discovery of sources (43%); ཛྷ ཛྷ detection of contamination that can sometimes lead to contamination of workers (44%). The predominance of these themes matches the findings already noted for the period 2014-2016. The source losses and discoveries can be explained in particular by poor overall traceability: lack of measures to ensure their disposal when laboratories ceased their activities in the past; irregular and non-exhaustive inventories. The detection of contamination, which caused several significant events, is due to the type of sources used in this sector, these being mainly unsealed sources for which contamination cannot be completely excluded, plus bad handling practices. The individual doses involved in these events in 2017 however did not exceed 150 µSv. 6. Assessment of radiation protection in the industrial, research and veterinary sectors, and outlook In the regulation of practices involving ionising radiation in the industrial, research and veterinary sectors, ASN is working to ensure that the operators take full account of the risks involved in the use of ionising radiation. Industrial radiography Industrial radiography activities involve serious radiation risks for the workers and are an inspection priority for ASN, with some 100 inspections carried out per year in this field, including unannounced night-time inspections on worksites. The system of on-line notification of worksite schedules for industrial radiography contractors put in place by ASN in 2014 facilitates the organisation of these inspections. A lack of reliability of the FUNDAMENTALS Loss of control of the source in gamma radiography Gamma radiography is a non-destructive testing technique consisting in positioning a radioactive source close to the element to be inspected in order to obtain a radiographic image which can subsequently be used to check the quality of the part. The loss of control of the sources is one of the main causes of incidents in this area. It can lead to significant exposure of the workers situated nearby, or even of the public when working in an urban area. This loss of control is primarily encountered in two situations: ཛྷ ཛྷ The radioactive source remains jammed in its guide tube. The cause of jamming is often the presence of foreign bodies in the tube, or deterioration of the tube itself. ཛྷ ཛྷ The source-holder containing the radionuclide is no longer connected to the remote control. The cable joining the source and the remote control is not correctly connected and the source can no longer be moved. In France, gamma radiography projectors comply with technical specifications that are stricter than the international standards. However, equipment failures can never be ruled out, especially in the event of poor upkeep of the equipment. Inappropriate operator actions are also observed following source jamming incidents. ASN notes in particular that the procedures and steps to be taken by radiographers when confronted with these situations are not well enough known and applied. information communicated by some contractors has nevertheless been observed. From its inspection findings, ASN considers that the way risks are taken into account varies between companies. On the whole, the regulations relating to worker training, to the periodic third party inspection of sources and devices and to worker dosimetry are complied with. The preparation of radiography operations however, particularly on worksites, with the cordoning off of the work zone and the estimation of predicted doses, remains insufficient despite the progress made. To remedy these problems, the various actors involved, namely the ordering customers and service providers, must improve their coordination to implement effective preventive measures. ASN considers the deficiencies in work zone delimitation and marking to be worrying, as cordoning off constitutes the main safety barrier in the worksite configuration, in particular to prevent incidental exposure. The work conditions on the site (poor accessibility, night work, etc.), equipment maintenance (projectors, guide tubes, etc.) are major factors affecting worker safety. The incidents often result from sources getting jammed outside the safe position. ASN notes that the radiographer’s workload and condition of the equipment are not unrelated to the probability of an incident. It moreover underlines that if any anomalies are observed when using a gamma ray projector, such as abnormal source projection or retraction forces, operations should be immediately stopped and the equipment inspected (see paragraph relative to incidents). Furthermore, if a source becomes jammed, no improvised attempt should be made to free it. The blocking of a source should lead to the deployment of on-site emergency plans, which are required by the regulations but rarely drawn up by the companies. With regard to justification and optimisation, the work undertaken by the non-destructive inspection professionals have resulted in guidelines which aim to promote the use of alternative methods to industrial radiography. The work is continuing within the professional bodies, in particular with the updating of the construction and maintenance codes for industrial equipment, in order to promote the use of non- ionising inspection methods.