Kalkwarf D R, Jackson P O, Hardin J M
Health Phys. 1984 Jul;47(1):37-45. doi: 10.1097/00004032-198407000-00003.
Lung-clearance classifications for 238U, 232Th, 230Th, 228Th, 226Ra, 210Pb and 210Po in respirable coal fly ash were estimated for use with the lung clearance model proposed by the ICRP Task Group on Lung Dynamics. Estimates were based on measurements of the dissolution rates for these radionuclides from sized fly-ash samples into simulated lung fluid at 37 degrees C. The estimates were expressed in the classification terms of the model, i.e. D, W and Y, indicating lung clearance half-times of 0-10 days, 11-100 days, and more than 100 days, respectively. Ash from eastern bituminous coal, western bituminous coal and mid-western bituminous coal was examined. Both Class-D and Class-Y components of 238U were found in all samples, whereas all the other radionuclides dissolved very slowly and were classified 100% Class Y. The fraction of 238U in Class D increased with decreasing particle size and increased linearly from 0.02 to 0.17 as the concentration of U in the volatile-metal portion of the samples increased. This relationship suggests that a major fraction of the U in coal fly ash may be shielded from exposure to simulated lung fluid by more-abundant metals deposited on the outer surface of fly ash during coal combustion.
根据国际辐射防护委员会肺部动力学问题特别工作组提出的肺部清除模型，估算了可吸入煤飞灰中238U、232Th、230Th、228Th、226Ra、210Pb和210Po的肺部清除分类。估算基于对这些放射性核素从不同粒径飞灰样品在37摄氏度下溶解到模拟肺液中的溶解速率的测量。估算结果用该模型的分类术语表示，即D、W和Y，分别表示肺部清除半衰期为0至10天、11至100天和超过100天。对东部烟煤、西部烟煤和中西部烟煤的飞灰进行了检测。在所有样品中均发现了238U的D类和Y类成分，而所有其他放射性核素溶解非常缓慢，100%被归类为Y类。D类中238U的比例随粒径减小而增加，并且随着样品挥发性金属部分中U浓度的增加，从0.02线性增加到0.17。这种关系表明，煤燃烧过程中沉积在飞灰外表面的更丰富的金属可能会使煤飞灰中的大部分U免受模拟肺液的暴露。
