The largest part of Belgian phosphate industry happened Flanders,since 1920,producing phosphoric acid, fertilizers and cattle food.Over 60 Mt of ore were used,containing about 72TBq of 226Ra and 3.5 TBq of 232Th.Three different processing techniques in six large production sites yielded 50 Mt of phosphogypsum and 2.7 Mt of calcium fluoride sludge,all mainly stored on large deposits. Some phosphogypsum was recycled in building materials and 10 Mt of gypsum was discharged into the Scheldt. One plant still produces 0.25 Mt of gypsum yearly.Liquid effluents containing 13 TBq of radium chloride were discharged in two small rivers, contaminating over 200 ha of land. Some 8 TBq of 226Ra and 1.2 TBq thorium remained in finished products such as fertilizers. Despite these large production figures, the radiological impact for the Flemish population has been fairly limited so far,but this might worsen in the future. The major risk appears to exist where land contaminated with 226Ra, would be converted to residential area, resulting in possibly enhanced indoor radon concentrations. In three isolated cases, we found houses built on gypsum deposits, were the increase in indoor radon levels are likely to increase the annual radiation dose to the inhabitants by 4 mSv.
|State||Published - Oct 2008|