Abstract
<abstract> <p>Naturally Occurring Radioactive Materials (NORMs) and Technologically Enhanced NORMs (TENORMs) are among the principal sources of radiation exposure for humans and for the environment. Therefore, the assessment of the impact of NORMs and TENORMs waste on human health is a key issue for their management and for acceptance of disposal sites. The radiological doses to workers and public due to TENORMs disposal depend on the waste inventory, on the usage of the site during operational activities and post closure phase and on the presence of dwelling areas in the vicinity of the disposal site. In the present study it is presented a methodology to preliminary assess the feasibility of a disposal of TENORMs, mainly constituted by phosphate sludges, originated from phosphoric acid industry activities. The hypothetical case study here presented is inspired by a real case study. Different possible scenarios have been considered. The potential doses to workers and to the public on-site have been estimated by the use of the TSD Dose and the RESRAD on-site codes both during the production life cycle of the site and once it ended. Sensitivity analyses were conducted to evaluate the impact of some key parameters, such the coverage thickness and wind velocity, on potential risk for workers and public.</p> </abstract>
Highlights
Industrial processes such as oil and gas production, fertilizers production, extraction and processing of metal ores produce large quantities of Naturally Occurring Radioactive Material, Naturally Occurring Radioactive Materials (NORMs), and can cause NORMs to be concentrated at levels above natural background, giving rise to by-product waste streams referred to as Technologically Enhanced NORMs or TENORMs.Minimization of risks to public and environment is a key issue for the disposal and management of NORM and TENORM wastes
From the analysis of the results obtained with TSD dose for the workers involved during the production life cycle of the landfill it is clear that the total dose rate is predominantly due to exposure from external radiation and that the most critical scenarios are those relating to the workers unloading and covering the big bags containing TENORMs
In an extremely conservative way, that these activities are carried out up to 2200 hours per year, an annual dose of approximately 0.1 mSv would be involved; the activity concerning the placement of TENORMs in landfills, on the other hand, would involve an annual dose lower of 1 order of magnitude, i.e. of approximately 0.02 mSv
Summary
Minimization of risks to public and environment is a key issue for the disposal and management of NORM and TENORM wastes In this regard, adequate protection of the human health and the environment must be guaranteed according to assessment of dose limits to workers and population, by minimizing doses on the basis of the ALARA principle "As Low As Reasonably Achievable" [1,2]. For the disposal of residues contaminated by NORM, the long-term acceptability and safety of the proposed method of disposal must be demonstrated. To this end, a radiological risk assessment is required for workers and the general public in order to demonstrate that the proposed method of disposal meets all the requirements of existing legislation and regulations. Near Surface Disposal (NSD) takes advantage and justification from the numerous studies carried out on low-activity radioactive waste originated from nuclear activities which, unlike NORMs, are real radioactive waste and fall within the most stringent radiation protection legislation. [11,12,13]
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