No abstract

Materials containing radionuclides of natural\ud origin and being subject to regulation because of their\ud radioactivity are known as Naturally Occurring Radioactive\ud Material (NORM). By following International Atomic\ud Energy Agency, we include in NORM those materials with\ud an activity concentration, which is modified by human\ud made processes. We present a brief review of the main\ud categories of non-nuclear industries together with the levels of activity concentration in feed raw materials,\ud products and waste, including mechanisms of radioisotope\ud enrichments. The global management of NORM shows a\ud high level of complexity, mainly due to different degrees of\ud radioactivity enhancement and the huge amount of worldwide\ud waste production. The future tendency of guidelines\ud concerning environmental protection will require both a\ud systematic monitoring based on the ever-increasing sampling\ud and high performance of gamma-ray spectroscopy.\ud On the ground of these requirements a new low-background\ud fully automated high-resolution gamma-ray spectrometer\ud MCA_Rad has been developed. The design of\ud lead and cooper shielding allowed to reach a background\ud reduction of two order of magnitude with respect to laboratory\ud radioactivity. A severe lowering of manpower cost is\ud obtained through a fully automation system, which enables\ud up to 24 samples to be measured without any human\ud attendance. Two coupled HPGe detectors increase the\ud detection efficiency, performing accurate measurements on\ud small sample volume (180 cm\ud 3\ud ) with a reduction of sample\ud transport cost of material. Details of the instrument calibration\ud method are presented. MCA_Rad system can\ud measure in less than one hour a typical NORM sample\ud enriched in U and Th with some hundreds of Bq kg\ud , with\ud an overall uncertainty less than 5 %. Quality control of this\ud method has been tested. Measurements of three certified\ud reference materials RGK-1, RGU-2 and RGTh-1 containing\ud concentrations of potassium, uranium and thorium\ud comparable to NORM have been performed. As a result,\ud this test achieved an overall relative discrepancy of 5 %\ud among central values within the reported uncertainty

No abstract

No abstract