A radiological evaluation of phosphogypsum.
Phosphogypsum is the by-product resulting from phosphoric acid or phosphate fertilizer production. The phosphate are used in these chemical processes contains the naturally occurring radioactive material U and all its subsequent decay products. During processing, the U generally remains in the phosphoric acid product, while the daughter, 226Ra, tends to be concentrated in the phosphogypsum. Phosphogypsum has physical properties that make it useful as a sub-base for roadways, parking lots, and similar construction. A radiological evaluation, to determine exposures to workers mixing this material with a stabilizing agent (portland cement), was performed at a South Louisiana phosphoric acid chemical plant. Measurements of the 226Ra content of the phosphogypsum showed an average of 1.1 +/- 0.3 Bq g-1 (0.7-1.7 Bq g-1). The average measured gross gamma exposure rate on the phosphogypsum pile corresponded to a dose equivalent rate of 0.368 +/- 0.006 mu Sv h-1 (0.32-0.42 mu Sv h-1). Radon daughter concentrations measured on top of the phosphogypsum pile ranged from 0.0006 to 0.001 working levels. An analysis of the airborne 226Ra concentrations showed only background levels.
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Nuclear Science Center, Louisiana State University, Baton Rouge 70808-5820.
Scott
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D001729:Bismuth / Q000032:analysis; D002133:Calcium Sulfate; D002617:Chemical Industry; D007854:Lead / Q000032:analysis; D016273:Occupational Exposure; D010756:Phosphoric Acids; D011059:Polonium / Q000032:analysis; D011850:Radioactive Waste; D011883:Radium / Q000032:analysis; D017687:Radon Daughters; D012037:Refuse Disposal
D010756:Phosphoric Acids; D011850:Radioactive Waste; D017687:Radon Daughters; D007854:Lead; D011059:Polonium; D001729:Bismuth; D011883:Radium; D002133:Calcium Sulfate