ASN Report 2020

Depending on the current or future uses of the site, decontam­ ination objectives must be set. The removal of the waste produced during post-operation clean-out of the premises and removal of the contaminated soil must be managed from the site through to storage or disposal. The management of contaminated objects also follows these same principles. 2.2.6 Activities using radioactive substances of natural origin Exposure to ionising radiation of natural origin, when increased due to human activities, justifies monitoring measures if it is likely to create a hazard for the exposed workers and, where applicable, the neighbouring population. Thus, certain activities included in the definition of “nuclear activities” can use materials containing naturally occurring radio­ active materials at concentration levels that could significantly increase the exposure of workers to ionising radiation and, to a lesser extent, the exposure of populations living near the places in which these activities are carried out. The natural families of uranium and thorium are the main radionuclides found in these activities, which include: ∙ the production of oil and gas, geothermal energy, titanium dioxide, phosphate fertilizers and cement; ∙ the extraction of rare earths and granites; ∙ the casting of tin, lead and copper. The radiation protection measures to take in this area target not only the workers (risk of external irradiation and internal contamination, radon) but also the general public, for example in the case of effluent discharges into the environment or the production of residues that could be reused, in construction materials for example. As of June 2018, these activities are subject to the same rules as the Installations Classified for Protection of the Environment (ICPEs). 3. Monitoring exposure to ionising radiation Given the difficulty in attributing a cancer solely to the ionising radiation risk factor, “risk monitoring” to prevent cancers in the population is performed by measuring ambient radioactivity indicators (measurement of dose rates for example), internal contamination or, failing this, by measuring values (activities in radioactive effluent discharges) which can then be used – by modelling and calculation – to estimate the doses received by the exposed populations. The entire population of France is exposed to ionising radiation of natural or anthropogenic origin, but to different extents across the country. The average exposure of the French population is estimated at 4.5 mSv per person per year (see Diagram 1), but this exposure is subject to wide individual variability, particularly depending on the place of residence and the number of radiological examinations received (source: IRSN, 2015). The average annual individual effective dose can thus vary by a factor of up to five depending on the département . Diagram 1 represents an estimate of the respective contributions of the various sources of exposure to ionising radiation for the French population. These data are however still too imprecise to allow identification of the most exposed categories or groups of individuals for each exposure source category with the exception of the radon risk. 3.1  Doses received by workers 3.1.1 Monitoring the exposure of persons working in nuclear facilities The system for monitoring the external exposure of persons liable to be exposed to ionising radiation, working in BNIs or in small‑scale nuclear facilities for example, has been in place for several decades. This system is based primarily on the mandatory wearing of passive dosimeters for workers liable to be exposed and enables compliance with the regulatory limits applicable to workers to be checked. These limits concern the total exposure (since 2003, the annual limit expressed in terms of effective dose has been 20 mSv for 12 consecutive months), obtained by adding the dose due to external exposure to that resulting from any internal con-tamination; other limits, called equivalent dose limits, are defined for the external exposure of certain parts of the body such as the hands and the lens of the eye (see “References” heading on asn.fr ). The recorded data allow the identification of the cumulative exposure dose for a given period (month or quarter) for each worker, including those from outside contractors. They are grouped together in Ionizing Radiation Exposure Monitoring Information System (Siseri) managed by the IRSN and are published annually. The results of worker exposure to ionising radiation presented below are taken from the IRSN 2019 assessment entitled La radioprotection des travailleurs: exposition professionnelle aux rayonnements ionisants en France (Worker radiation protection: occupational exposure to ionising radiation in France) . From the methodological aspect, as in the two preceding years, the IRSN 2019 assessment was based exclusively on data from individual monitoring of the external exposure of workers recorded in the Siseri database. The assessment of the preceding years, for its part, was produced exclusively by aggregating the annual summaries requested of the dosimetry organisations. Consequently, 0.02 Others (discharges from facilities, fallout from atmospheric tests) 0.6 Telluric radiation 1.6 Medical 1.4 Radon TOTAL 4.5 mSv/year 0.6 Water and foodstuffs 0.3 Cosmic radiation DIAGRAM 1 Average exposure of the French population to ionising radiation (mSv/year) Source: IRSN, 2015. ASN Report on the state of nuclear safety and radiation protection in France in 2020 109 01 – NUCLEAR ACTIVITIES: IONISING RADIATION AND HEALTH AND ENVIRONMENTAL RISKS 01