The worldwide NORM production and a fully automated gamma-ray spectrometer for their characterization

Materials containing radionuclides of natural origin, which is modified by human made processes and being subject to regulation because of their radioactivity are known as NORM. We present a brief review of the main categories of non-nuclear industries together with the levels of activity concentration in feed raw materials, products and waste, including mechanisms of radioisotope enrichments. The global management of NORM shows a high level of complexity, mainly due to different degrees of radioactivity enhancement and the huge amount of worldwide waste production. The future tendency of guidelines concerning environmental protection will require both a systematic monitoring based on the ever-increasing sampling and high performance of gamma ray spectroscopy. On the ground of these requirements a new low background fully automated high-resolution gamma-ray spectrometer MCA_Rad has been developed. The design of Pb and Cu shielding allowed to reach a background reduction of two order of magnitude with respect to laboratory radioactivity. A severe lowering of manpower cost is obtained through a fully automation system, which enables up to 24 samples to be measured without any human attendance. Two coupled HPGe detectors increase the detection efficiency, performing accurate measurements on sample volume (180 cc) with a reduction of sample transport cost of material. Details of the instrument calibration method are presented. MCA_Rad system can measure in less than one hour a typical NORM sample enriched in U and Th with some hundreds of Bq/kg, with an overall uncertainty less than 5%. Quality control of this method has been tested. Measurements of certified reference materials RGK-1, RGU-2 and RGTh-1 containing concentrations of K, U and Th comparable to NORM have been performed, resulting an overall relative discrepancy of 5% among central values within the reported uncertainty.Comment: 21 pages, 4 figures, 6 table

Phosphorus:Reserves, production, and applications

The demand of phosphate fertilizers is growing as a result of a rising population, changing human diets resulting in the increasing (meat) consumption per capita, and an expansion in the production of biofuels. Besides the fertilizer industry, there is a steady growth of using phosphorus compounds in the chemical industry for applications in, e.g., soft drinks, pharmaceuticals, and flame retardants. To meet this growth, it is important to know if the P reserves are sufficient and what kind of processes are used to produce such phosphorus compounds. Reserves are not equally spread around the world, with three-quarters located in Morocco and The Western Sahara. Prices can be volatile, as shown in 2008 with an eightfold price increase. Moreover, the estimated time till depletion of phosphate rock differs substantially between several studies. Therefore, phosphate rock was added on the critical material list of the European Commission. An important aspect for the processing of phosphate rock is the quality of the rock, which is dependent on the ore type (sedimentary or igneous), level of radioactivity, and hazardous metal contents. The main intermediary compounds for phosphorus products are phosphoric acid and white phosphorus. About 95% of the phosphoric acid is made via the wet process: acidulation of phosphate rock to create wet phosphoric acid and the main by-products phosphogypsum and hydrogen fluoride. The purity and thus the reusability of phosphogypsum are dependent on the type of digestion process. However, at the moment, reusing phosphogypsum is not a common practice. Wet phosphoric acid can be purified via several processes. The most common processes are extraction and precipitation. Via extraction, wet phosphoric acid can be purified up to phosphoric acid comparable to that produced with the thermal process. Separation of specific compounds can be done through precipitation. Additionally, cationic impurities can be removed via precipitation, but the product will then be changed into a phosphate salt, which is unfavorable for its use in industrial applications