NORM in the petroleum and geothermal industries : evolution of the French radioprotection legislation
Résumé
Fluids produced from oil or gasfields and aquifers are naturally radioactive due to the presence of potassium-40 and isotopes from decay chains of uranium-238 and thorium-232 in these reservoirs. Thus, natural radionuclides can be carried away towards surface when petroleum or geothermal reservoirs are drilled and produced. These radio- nuclides can precipitate in deposits forming in process equipment, which can then be unusually radioactive, expose workers to hazardous materials and create waste disposal problems. Workers can also be exposed to high concentrations of radon. Due to their natural origin, these accumulations of radionuclides in equipment are called Naturally Occurring Radioactive Materials (NORM). They are also known as TENORM, because they are technologically enhanced. In closed systems, exposition to gamma radiations penetrating equipment to the external surface can be reduced by restricting and controlling access to appropriate areas. But personnel may come into direct contact with NORM during maintenance and cleaning operations, when opening equipment and vessels. In France, hygiene and safety rules concerning the protection of workers in the petroleum and geothermal industries are formulated in a speciac legislation related to extraction and mining. Presently, both petroleum and geothermal industries are not included in the list of activities which have to follow radioprotection measures given by this legislation. French authorities are currently planning to update the list by including these two activities. There is a real need to realize a state-of-the art of the exposition level of French workers and to match the dose limits to those given by the Labor and Public Health Codes. This paper will present the origin of NORM and radon contamination in the petroleum and geothermal industries and discuss the French legislation evolution for the radioprotection of personnel working in these two industries
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