ASN Report 2017

360 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 12  - EDF Nuclear Power Plants 2.7 Personnel radiation protection 2.7.1 Monitoring of personnel radiation protection Exposure to ionising radiation in a nuclear power reactor comes from activation of primary system corrosion products (mainly) and from fuel fission products. All types of radiation are present (neutrons, α , β and γ ) and the risk of exposure is both external and internal. In practice, more than 90% of the doses received come from external exposure to β and γ radiation. Exposure is primarily linked to maintenance operations during reactor outages. ASN checks compliance with the regulations relative to the protection of workers liable to be exposed to ionising radiation in NPPs. In this respect, ASN concerns itself with all workers active on the sites, whether EDF or contractor personnel. This oversight is carried out during inspections (specifically on the topic of radiation protection, one to two times per year and per site, during reactor outages, following incidents, or occasionally in the EDF head office departments and engineering centres), and during the review of files concerning occupational radiation protection (significant events, design, maintenance or modification files, EDF documents implementing the regulations, etc.) with the support of IRSN when necessary. Periodic meetings are held with EDF as part of the technical dialogue with the licensee. These enable ASN to check the progress of technical or organisational projects. Significant contamination events Three significant contamination events were notified in 2017 in the NPPs operated by EDF. These events, which led to exposure greater than one quarter the regulation limit per square centimetre of skin, were rated level 1 on the INES scale. They concern: ཛྷ ཛྷ contamination of the face of a contractor staff member assigned to maintenance worksite tear-down operations in the Le Blayais NPP; ཛྷ ཛྷ contamination of the skin of the groin of a contractor staff member assigned to maintenance work on a press compacting radioactive waste in the FessenheimNPP; ཛྷ ཛྷ contamination of the skin behind the ear of a contractor staff member assigned to maintenance work on the fuel loading machine in the Cattenom NPP. Reinforced radiation protection inspections In 2017, ASN carried out in-depth inspections on radiation protection in the Cattenom, Chooz and Nogent-sur- Seine NPPs. Each of these inspections required six to eight ASN inspectors and two to three IRSN experts. They more particularly examined the organisation and management of radiation protection, the integration of operating experience feedback, the management of worksites, the application of the optimisation approach, the management of radiological cleanness and of radioactive sources. The main strong points identified by the inspectors are the initiatives taken to improve personnel working conditions. ASN considers that improvements must be made to the process to optimise occupational dosimetry, the characterisation and analysis of radiation protection deviations and the care and treatment of contaminated personnel. 2.7.2 Evaluation of personnel radiation protection In 2017, ASN carried out 27 radiation protection inspections. The collective dose on all the reactors fell in 2017 by comparison with 2016 (Graph 6), as did the average dose received by workers for one hour of work in a controlled zone. The doses received by the workers are broken down as shown below in Graphs 5 and 6. Graph 5 shows the breakdown of the workers in terms of whole body external dosimetry. It can be seen that the dosimetry for 78% of the exposed workers is less than 1 mSv for the year 2017, which corresponds to the annual regulation limit for the public. The annual regulation limit for whole body external dosimetry (20 mSv) was exceeded on no occasion in 2017. Graph 6 shows the trend in the collective dose received by NPP workers over the past ten years. This graph shows a reduction in the average collective dose per reactor, reflecting contrasting results between the sites, and the continued optimisation efforts at a time of rising volumes of maintenance work in controlled areas in recent years. Graph 7 shows the trend in whole body average individual dosimetry according to the worker categories in NPPs. The most exposed worker categories in 2017 are personnel in charge of thermal insulation, monitoring, inspection and welding. ASN considers that the radiation protection situation of the NPPs in 2017 could be improved more particularly on the following points: ཛྷ ཛྷ The organisation of control of the dispersal of contamination inside the reactor building must be improved, notably with regard to the confinement of worksites. ཛྷ ཛྷ On several sites, the ASN inspectors found a lack of radiation protection culture on the part of certain workers. ཛྷ ཛྷ Weaknesses remain in the control of industrial radiography sites: ASN more specifically identified several events involving overstepping of operation areas demarcation lines or the presence of workers inside the exclusion zone demarcation lines. Progress is required in the preparation of the worksites, more specifically multiple contractor activities and the quality of the installation walkdowns carried out when preparing these worksites. ཛྷ ཛྷ The radiation protection optimisation approach falls short of that in previous years. ASN more particularly identifies relatively unambitious reactor outage predicted dose targets. Progress is also expected in the drafting of the risk assessments for the work and the integration of contingencies. ཛྷ ཛྷ Control of radiological zoning and the associated provisions remains vulnerable. More specifically the risk assessments for the work do not always identify the risk of entering a specially regulated area. ཛྷ ཛྷ Shortcomings in the operational dosimetry alarms analysis process and in the assessment of the significant nature of these events were brought to light during ASN inspections in  2016 and  2017, which led EDF to notify a generic significant radiation protection event.