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 radioactive 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. 7. Exposure of the French population to ionising radiation – Results for 2014-2019, IRSN, 2021. 8. For information, the collective dose is the sum of the individual doses received by a given group of persons. 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. Since 2018, these activities are subject to the system of Installations Classified for Protection of the Environment (ICPEs). 3. Monitoring of 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, but this exposure is subject to wide individual variability, particularly depending on the place of residence (radon potential of the municipality, level of terrestrial radiation), the number of radiological examinations the person undergoes, consumption (smoking, foodstuffs) and living habits (air travel). The average annual individual effective dose can thus vary from 1.6 mSv to 28 mSv(7).The adoption of the new radon dose coefficient recommended by the ICRP (see box page 102 and point 2.1.3), will lead to an increase in the dose resulting from exposure to radon, and thus in the calculated dose relative to total average exposure which would thereby increase from 4.5 mSv to 6.5 mSv. Diagram 1 shows an estimate of the respective contributions to the average total dose of the different sources of exposure to ionising radiation for the French population, considering firstly the radon dose coefficient stipulated by the current regulations, and secondly the dose coefficient recommended by ICRP 137. 3.1 Doses received by workers 3.1.1 Monitoring the exposure of persons working in nuclear facilities The system for monitoring 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. Based primarily on the mandatory wearing of passive dosimeters for workers liable to be exposed, this system enables compliance with the regulatory limits applicable to workers to be verified. 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 contamination; other limits, called “equivalent dose limits”, are defined for the external exposure of certain parts of the body such as the hands, the skin 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 the Ionising radiation exposure monitoring information system (Siseri) managed by IRSN and are published annually. The results of worker exposure to ionising radiation presented below are taken from the IRSN 2021 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 four preceding years, the IRSN 2021 assessment of external exposure was based exclusively on data from individual monitoring of the external exposure of workers recorded in the Siseri database. Until 2016, the assessments were produced exclusively by aggregating the annual summaries provided by the dosimetry organisations. Consequently, external exposure results for 2021 are not directly comparable with those of 2020, 2019, 2018 and 2017. Nevertheless, in order to establish trends, the results for the years 2015 and 2016 have been reassessed applying the new methodological approach (see Table 3). Tables 1 and 2 present, per area of activity and for the year 2021, the breakdown of the populations monitored, the collective dose(8) and the number of exceedances of the annual limit of 20 mSv. They show a large disparity in the breakdown of doses depending on the sector. For example, the medical and veterinary activities sector, which accounts for a significant share of the population monitored (60%), accounts for only 12% of the collective dose; conversely, the civil nuclear industry, which represents just 22% of the headcount, accounts for 55% of the collective dose and the sector concerned by exposure to natural radioactivity, which represents only 5.5% of the total headcount, accounts for 27% of the collective dose. The non-nuclear industry and the research sectors represent 4.2% and 2.7% of the headcount respectively and account for 3.3% and 0.37% of the collective dose respectively. ASN Report on the state of nuclear safety and radiation protection in France in 2022 107 • 01 • Nuclear activities: ionising radiation and health and environmental risks 07 08 13 AP 04 10 06 12 14 03 09 05 11 02 01
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