Contrôler et limiter la dispersion des produits radioactifs des centrales électronucléaires en cas d'accident

We examine the role of physical, chemical and physicochemical differences between the consequences of accidents occurring in high-risk technologies (oil extraction, refinery and transport, big chemistry process, space shuttle flying start, airplane, underground mining, high velocity train transportation, etc.) and the major radioactive major accidents in nuclear power plants (NPP) from the viewpoint of their sequels, confined or not confined, in space and time, and then, their serious impact on human societies, neighboring or not. We identify chemical (as volatile species, noble gases, etc.), physical bodies (as aerosols, etc.) containing radioactive nuclei released in these accidents and seek to control and reduce the causes of their diffusion in the atmosphere, migrations in soils and land, transfer in inland waters and oceans. We propose ways of scientific research leading to solutions with a view to get an improved control of these radioactive substances, and in particular:. A.reducing as much as possible the irradiation duration by removing the fuel elements from the nuclear core of the NPP reactor and extracting all culprit radioactive nuclei;B.designing power reactors using liquid fuels that can be frequently or even continuously removed from the core of the reactor. The disputed radioactive substances can, then, be extracted by chemical processes. The purified nuclear fuel fluid may then be returned to the core;C.to separate, in a more radical manner, the circuits of the nuclear fuel and that of the cooling fluid, in order to decrease strongly the radioactive phenomena in the latter, easing its design, operation, maintenance and dismantling;D.using a fuel of lower atomic number than uranium or plutonium, as thorium. The use in the present-time fuel cycle of actinides with high atomic numbers Z (number of protons) and A (number of nucleons) leads, by successive neutron captures, to very high Z and A pair-pair nuclei (as americium and curium) subject to spontaneous fissions, then emitting neutrons of fission, even when the nuclear chain reaction is stopped. Neutron emissions are a major hazard if their mass production oversizes the laboratory level. It poses difficult, complicated scientific problems for human radioprotection. A way to improve concepts further than A, B, and C consists in using a nuclear fuel whose Z and A numbers are much smaller than those of uranium, for instance thorium. This is concept D studied here. A substantial part of these lines of these four research routes has been already studied in other contexts, during the last half-century. What can be used is specified here, with the necessary extensions to the fields of physics, chemistry, and physical chemistry.