ASN Report 2017
46 ASN report on the state of nuclear safety and radiation protection in France in 2017 Chapter 01 - Nuclear activities: ionising radiation and health and environmental risks 1. State of knowledge of the hazards and risks associated with ionising radiation Ionising radiation is defined as being capable of producing ions – directly or indirectly – when it passes through matter. It includes X-rays, alpha, beta and gamma rays, and neutron radiation, all of which are characterized by different energies and penetration powers. 1.1 Biological and health effects Whether it consists of charged particles, for example an electron (beta radiation) or a helium nucleus (alpha radiation), or of photons (X rays or gamma rays), ionising radiation interacts with the molecules making up the cells of living matter and alters them chemically. Of the resulting damage, the most significant concerns the DNA of the cells and this damage is not fundamentally different from that caused by certain toxic chemical substances, whether exogenous or endogenous (resulting from cellular metabolism). When not repaired by the cells themselves, this damage can lead to cell death and the appearance of harmful biological effects if tissues are no longer able to carry out their functions. These effects, called “deterministic effects”, have been known for a long time, as the first effects were observed with the discovery of X rays by W. Roentgen (in the early 1900’s). They depend on the nature of the exposed tissue and are certain to appear as soon as the quantity of radiation absorbed exceeds a certain dose level. These effects include, for example, erythema, radiodermatitis, radionecrosis and cataract formation. The higher the radiation dose received by the tissue, the more serious the effects. Cells can also repair the damage thus caused, although imperfectly or incorrectly. Of the damage that persists, that to I onising radiation may be of natural origin or be produced by nuclear activities of human origin. The exposure of the population to naturally occurring ionising radiation results from the presence of radionuclides of terrestrial origin in the environment, radon emanations from the ground and exposure to cosmic radiation. Nuclear activities are defined in the Public Health Code as “activities involving a risk of exposure of persons to ionising radiation associated with the utilisation of artificial sources of radiation, whether substances or devices, or natural sources of radiation, whether natural radioactive substances or materials containing natural radionuclides…” These nuclear activities include those carried out in Basic Nuclear Installations (BNI) and during the transport of radioactive substances, as well as in the medical, veterinary, industrial and research fields. The various principles with which the nuclear activities must comply, particularly those of nuclear safety and radiation protection, are set out in chapter 3. In addition to the effects of ionising radiation, BNIs are similar to all industrial installations in that they are the source of non-radiological risks and detrimental effects such as the discharge of chemical substances into the environment or noise emission. DNA is of a particular type because residual genetic anomalies can be transmitted by successive cellular divisions to new cells. A single genetic mutation is far from being sufficient to cause the transformation into a cancerous cell, but this damage due to ionising radiation may be a first step towards cancerisation. The suspicion of a causal link between exposure to ionising radiation and the appearance of a cancer dates back to 1902 (observation of skin cancer in a case of radiodermatitis). Subsequently, several types of cancers were observed in occupational situations, including certain types of leukemia, broncho-pulmonary cancers (owing to radon inhalation) and jawbone sarcomas. Outside the professional area, the monitoring FUNDAMENTALS UNSCEAR The UNSCEAR 2016 Report Sources, effects and risks of ionising radiation takes stock more particularly of current knowledge concerning exposure of the public to ionising radiation resulting from the electricity production industries. The first part of the report presents the developments of the methodology used to estimate public exposure due to radioactive discharges from the electricity generation industry. It compares the exposure to ionising radiation resulting from the different electricity generation sources: nuclear, coal, gas, oil, geothermal, solar and wind. Particular attention was focused on the contribution of the industries generating electricity from nuclear energy and coal. The results show that the coal cycle industry, contributes more than half of the collective dose received by the public for one year of electricity production. For a given quantity of electricity produced, the coal cycle makes the largest contribution to the collective dose of the public, followed by nuclear energy and, to a lesser extent, the other sources with the exception of geothermal energy.