Identification and characterization of NORM industries in Belgium

摘要

An overview of the NORM issue in the Belgium industry is given, mainly based on a study on behalfof ONDRAF/NIRAS, the Belgian agency for radioactive waste. The phosphate industry, which was identified asthe main source of enhanced natural radioactivity, is mainly located in Flanders, the northern part of Belgium. Thefive Flemish phosphate plants handled, from 1920 to 2006, 60 Mton of phosphate ore containing 72 TBq ofuranium-238 (radium-226) and 3.5 TBq of thorium-232. This resulted in a vast legacy of 500 ha of contaminatedsites. In the non-ferro industry high activity-concentrations of the thorium decay series were identified withcassiterite (tin ore). Zircon sands with high uranium concentrations are applied for the production of precisioncasting molds. Almost every industry with a large turnover of materials has some problems with NORM, becauseof the selective concentration of certain radionuclides in by-products, residues or product streams. Examples of ablast furnace and a coal-fired power plant are given. In these cases the natural radioactivity is concentrated in blastfurnace slag or fly ash, both of which are used as input material in the cement industry. The extraction andpurification of ground water was also identified as a potential source for generating NORM sludges. Finally,ample remains from past NORM practices exist. A number of historical sites, including a former mining area ofalum shale in the valley of the Meuse, several coal mining sites, a coltan processing site in Ghent and a radiumfacility in Olen were contaminated before present standards of radiological protection were developed.