ASN Report 2017

18 ASN report on the state of nuclear safety and radiation protection in France in 2017 Ionising radiationmay be of natural origin or caused by human activities referred to as nuclear activities. The exposure of the population to naturally occurring ionising radiation is the result of the presence of radionuclides of terrestrial origin, radon emanations from the ground and exposure to cosmic radiation. Nuclear activities include those conducted in Basic Nuclear Installations (BNIs) and the transport of radioactive substances, as well as activities conducted in all medical, veterinary, industrial and research facilities where ionising radiation is used. Ionising radiation is capable of producing ions – directly or indirectly – when it passes throughmatter. It includes X-rays, alpha, beta and gamma rays, and neutron radiation, all of which have different energies and penetration powers. The effects of ionising radiation on living beings can be “deterministic” (clinical effects such as erythema, radiodermatitis, radionecrosis or cataract); these effects occur systematically once the radiation dose exceeds a certain threshold. Ionising radiation is also the cause of probabilistic effects, primarily the occurrence of cancers, the probability of which increases with the dose received by the subject. The protective measures against ionising radiation aim to avoid deterministic effects, but also tominimise the probability of occurrence of radiation- induced cancers, which constitute the main risk. Understanding the risks linked to ionising radiation is based on follow-up studies of cohorts of exposed subjects (Hiroshima, Nagasaki, nuclear accidents, etc.) epidemiological surveys, the studyof cancer registers and pre-clinical experimentation data. Risk management is based on the hypothesis of the linear relationship without threshold and evaluation of the low-dose risks by an extrapolation from those observed at high doses. Numerous unknown factors and uncertainties nonetheless persist, more particularly with regard to the actual effects at low doses, the deterministic risks for the vascular system, the radio- sensitivity of certain subjects and the existence or otherwise of a radiological signature for radiation induced cancers. Exposure to ionising radiation in France The entire French population is potentially exposed to ionising radiation, but to differing degrees, depending on whether the ionising radiation is of natural origin or the result of human activities. On average, the exposure of an individual in France was estimated by the French Institute for Radiation Protection and Nuclear Safety (IRSN) at 4.5 millisieverts (mSv) per year in 2015, varying by a factor of from 1 to 3 depending on the location, the eating habits, the medical exposures, etc. The sources of this exposure are as follows: ཛྷ ཛྷ accounting for about 2.9 mSv/year, radioactivity of natural origin, including 0.6 mSv/year for telluric radiation (except radon), 0.3 mSv/year for cosmic radiation, 0.6 mSv/year for internal exposure due to food or tobacco, as well as about 1.4 mSv/year for radon, although with considerable variations linked to the geological characteristics of the land and the buildings themselves. A newnational radon exhalation potential map was drawn up in 2011. In the zones defined as high priority, periodic measurements must be taken in places open to the public and in workplaces; a third national action plan has been defined for the period 2016-2019; ཛྷ ཛྷ accounting for about 1.6 mSv/year (2012 estimation), radiological diagnostic examinations, trending upward (+ 23% between 2007 and 2012); particular attention must be given to managing the doses delivered to patients; ཛྷ ཛྷ accounting for 0.02 mSv/year, the other sources of artificial exposure: past airborne nuclear tests, accidents in facilities, discharges from nuclear facilities. 01 Significant events and outlook Nuclear activities: ionising radiation and health and environmental risks