ASN Report 2020

limit the risks of intrusion, erosion, dispersion of the stored products and the risks of external and internal exposure of the neighbouring populations. The studies submitted for the PNGMDR have enhanced knowledge of: ∙ the dosimetric impact of the mine tailing disposal areas on man and the environment, in particular through the comparison of data obtained from monitoring and the results of modelling; ∙ the evaluation of the long-term dosimetric impact of the mining waste rock piles and the mining waste rock in the public domain in relation to the results obtained in the context of the Circular of 22 July 2009; ∙ the strategy chosen for the changes in the treatment of water collected from former mining sites; ∙ the relation between the discharged flows and the accumulation of marked sediments in the rivers and lakes; ∙ the methodology for assessing the long-term integrity of the embankments surrounding tailings disposal sites; ∙ transport of uranium from the waste rock piles to the environ­ ment; ∙ the mechanisms governing the mobility of uranium and radium within uranium-bearing mining tailings. In accordance with ASN opinion 2016-AV-0255 of 9 February 2016, these various studies are continuing under the PNGMDR 2016‑2018, as is the work of the two technical working groups focusing on: ∙ maintaining the functions of the structures surrounding the disposal facilities for uranium ore treatment residues; the interim report on this work was published on the ASN website; ∙ management of the water from the former uranium mining sites, for which the interim report drawn up from 2018 to 2019 was published on the ASN website. The studies required under the PNGMDR 2016-2018 were carried out following on from the previous PNGMDRs. Orano thus submitted eleven studies between January 2017 and February 2020, supplementing those submitted previously. ASN opinion 2021-AV-0374 of 4 February 2021 on the PNGMDR specifies the studies still to be carried out to meet the challenges associated with the former mining sites reiterated above. It recommends continuation of the work of the two working groups mentioned above, and proposes the creation of a third group dedicated to updating the methodology for assessing the long-term impact of the disposal facilities for mining processing residues. It details more specifically the long-term deterioration scenarios for the cover of mining processing residue disposal facilities, in relation with the radioactive waste disposal site development scenarios and the work carried out by the GEP Limousin, a pluralistic expert assessment group for the uranium mining sites of the Limousin region. Management of reused mining waste rock Most of the mining waste rock has remained on its site of production (mine in-fill, redevelopment work or spoil heaps). Nonetheless, 1 to 2% of the mining waste rock may have been used as backfill, in earthworks or for road beds in public places situated near the mining sites. Although the reuse of waste rock on public land has been traced since 1984, knowledge of reuses prior to 1984 remains incomplete. ASN and the Ministry responsible for the environment, in the framework of the action plan drawn up further to the Circular of 22 July 2009, asked Orano Mining to inventory the mining waste rock reused on public land in order to verify compatibility of the uses and to reduce the impacts if necessary. Orano Mining has thus deployed a plan of action comprising three broad phases: ∙ aerial overflight around the former French mining sites to identify radiological singularities; ∙ inspection on the ground of areas identified in the overflight to confirm the presence of waste rock; ∙ treatment of areas of interest incompatible with the land usage. The second phase of this action plan was completed in 2014. The Ministry responsible for the environment defined the procedures for managing cases of confirmed presence of mining waste rock in an Instruction to Prefects of 8 August 2013 and a complementary Instruction of 4 April 2014. This work has been carried out since 2015 on sites classified as priorities, that is to say sites where the calculation of the added annual effective dose excluding radon due to the presence of waste rock on generic scenarios exceeds the value of 0.6 millisieverts per year (mSv/year) on the basis of a radiological impact study. In January 2018, under the PNGMDR 2016-2018, Orano submitted an assessment of the actions taken when inventorying the mining waste rock on public land, which was supplemented in October 2019. ASN considers that the survey of waste rock piles and mining waste rock in the public domain is now complete. Based on this survey, corrective measures have been applied for situations presenting an average annual exposure exceeding 0.6 mSv/year in the public domain, or, in the case of radon exposures that could be of man-made origin, to levels exceeding 2,500 becquerels per cubic metre (Bq/m 3 ). 4. Management of sites and soils contaminated by radioactive substances A site contaminated by radioactive substances is defined as a site which, due to the presence of old deposits of radioactive substances or waste, or to the utilisation or infiltration of radioactive substances or radiological activation of materials, presents radioactive contamination that could cause adverse effects or a lasting risk for people or the environment. Contamination by radioactive substances can result from industrial, craft, medical or research activities involving radioactive substances. It can concern the places where these activities are carried out, but also their immediate or more remote vicinity. The activities concerned are generally either nuclear activities as defined by the Public Health Code, or activities concerned by natural radioactivity. However, most of the sites contaminated by radioactive substances and today requiring management have been the seat of past industrial activities, dating back to a time when radioactive hazards were not perceived in the same way as at present. The main industrial sectors that generated the radioactive contamination identified today were radium extraction for medical and parapharmaceutical needs, from the early 1900s until the end of the 1930s, the manufacture and application of luminescent radioactive paint for night vision, and the industries working ores such as monazite or zircons. Sites contaminated by radioactive substances are managed on a case-by-case basis, which necessitates having a precise diagnosis of the site. Article L.125-6 of the Environment Code provides for the State to create soil information sectors in the light of the information ASN Report on the state of nuclear safety and radiation protection in France in 2020 371 14 – RADIOACTIVE WASTE AND CONTAMINATED SITES AND SOILS 14