SCIENTIFIC METROLOGY IN SUPPORT OF RADON AND NORM ASSESSMENT
Naturally occurring radionuclides are present in many natural resources such as raw materials and mineral feedstocks. Industrial activities that exploit these resources may lead to enhanced potential for exposure to Naturally Occurring Radioactive Materials (NORM) in products, by-products, residues and wastes. Over the last years, the building industry has developed new building materials that may contain significant quantities of technologically enhanced levels of natural radioactivity that should be evaluated. Building materials contribute to natural radiation exposure, either by gamma radiation from 40K, 238U and 232Th and their decay products to an external whole body dose exposure, or by radon exhalation to an internal dose exposure due to deposition of radon decay products in the human lung tissue. Reliable, traceable and consistent NORM activity measurements are necessary in order to optimize counter measures for the reduction of the exposure to the public and to NORM industry workers. This will then reduce the related follow-up costs. The lower the uncertainties of the NORM activity measurement results, the lower is the risk of possible over-responses of counter measures, with low radiological but high economic impact.
The new NORM measurement methods, traceable reference materials and calibration sources developed under the EURAMET MetroNORM Joint Research Project, contribute to improve the radiological impact assessment models for the reuse of NORM residues in building materials and to establish a metrological sound basis for radiation protection in the NORM industries.