ASN Report 2018

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. The natural families of uranium and thorium are the main radionuclides found in these activities. Examples 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. 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 (see Diagram 1) per person per year, 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 5 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 exposure of persons liable to be exposed to ionising radiation, particularly those working in BNIs or in small-scale nuclear facilities, has been in place for several decades. This system is primarily based on the mandatory wearing of a passive dosimeter by workers liable to be exposed and it is used to check compliance with the regulation limits applicable to workers. 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 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 person working in nuclear facilities, including workers from subcontractor companies. They are grouped together in Siseri (Ionizing radiation exposure monitoring information system) managed by IRSN and are published annually. The monitoring system does not at present include worker exposure to radon. The results of worker exposure to ionising radiation presented below are taken from the IRSN 2017 assessment of occupational exposure to ionising radiation in France. From the methodological aspect, the IRSN assessment for 2017 introduces a significant change. This is because the 2017 assessment of external exposure has been drawn up exclusively using data recorded in Siseri, whereas in the previous years it was established by aggregating the annual syntheses requested of the dosimetry organisations. Consequently, the 2017 results are not directly comparable with those published in the preceding reports. Nevertheless, for comparison purposes, the results for 2015 and 2016 have been retroactively reassessed applying the new methodological approach (see Table 3). Tables 1 and 2 present, per area of activity and for the year 2017, a breakdown of the populations monitored, the collective dose Average exposure of the French population to ionising radiation (mSv/year)* Source: IRSN 2015. * This diagram does not integrate the data published in ICRP 167  of January 2018. 0.02 Others (BNI discharges, fallout from atmospheric testing) 0.6 Telluric radiation 1.6 Medical 1.4 Radon TOTAL 4.5 mSv/an 0.6 Water and foodstuffs 0.3 Cosmic radiation Diagram 1 ASN report on the state of nuclear safety and radiation protection in France in 2018  97 01 – NUCLEAR ACTIVITIES: IONISING RADIATION AND HEALTH AND ENVIRONMENTAL RISKS 01