The accumulation of Naturally Occurring Radioactive Materials is a well-known phenomenon in the upstream oil sector since a long time: production water flowing into the production and treatment plants together with crude oil and gas might transports natural radionuclides from the reservoir to the surface and chemical and physical mechanisms can produce their deposition inside processing equipment. Presence of TENORM might accounts for a significant radiological hazard for the human health and in some cases requires monitoring during routine, maintenance and decommissioning activities.

In the downstream oil sector however, the volume of stratum water that enters the refineries together with the crude is very small (maximum 1-2 % of total product), nevertheless in certain points of production plants deposition of TENORM has been observed.

A multi-step approach has been developed to manage TENORM (Technologically Enhanced Naturally Occurring Radioactive Material) risks in refinery plants, in compliance with Italian regulations and international guidelines.

The first step to assess the radiological TENORM risk in refineries consists in a on-field survey in a plant, that allows to determine, together with the knowledge of the production process, the points most likely subjected to potential accumulation of TENORM. Next steps consist of an extensive radiometric survey, sampling and radiometric analysis of matrices potentially affected by TENORM, evaluation of radiological risks, definition of criteria for the releasing of materials and waste, development of radiation protection procedures at workplace and workers training.

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