Practical Aspects of Monitoring and Dosimetry of Long-Lived Dust in Uranium Mines and Mills - Determination of the Annual Limit on Intake for Uranium and Uranium/Thorium Ore Dust

Abstract

Based on the recommendations of ICRP Publication 26, the dosimetric and metabolic data of ICRP Publication 30, and using available information on the physical and solubility characteristics of uranium and uranium/thorium ore, the ALI values for airborne ore dust were calculated. Four hypothetical types of ore were considered: uranium ore with no radon emanation, uranium ore with 50% radon emanation, uranium/thorium ore with neither 222Rn nor thoron emanation, and uranium/thorium ore with 50% 222Rn and 220Rn emanation. Furthermore, the ALI values were calculated assuming the radionuclides present in the ore were all: (a) solubility class Y; (b) solubility class W; and (c) equal parts of classes Y and W. The ALI values were also calculated for Activity Median Aerodynamic Diameters (AMAD) ranging from 1 to 10 µm. The results of the calculations show that the solubility class of the radionuclides is the single most important factor that governs ALI values. The ALI value for uranium and uranium-thorium ore dust is proportional to (AMAD)0.5 for class Y materials, (AMAD)0.2 for a mixture of equal parts of class Y and class W materials, and is independent of the AMAD for class W materials. A series of graphs is given from which it is possible to evaluate the ALI for airborne ore dust when the AMAD of the dust and the solubility characteristics are known approximately.