河流放射性核素水体弥散模型及其应用

Modelling the Dispersion of Radionuclide in River Water and Its Application

随着我国核能及核技术利用产业的迅速发展,放射性物质运输对饮用水水源地的潜在放射性污染健康风险越来越大,阐明事故情况下放射性物质在地表水体中的迁移弥散行为可为居民饮水健康风险防范提供科学依据。针对含钴-60、铯-137、锶-90货包公路运输在事故工况下放射性物质释放造成黄河兰州段河流型饮用水源放射性污染,讨论了河流放射性物质弥散模型和居民饮用水的健康风险。结合国内现有放射源活度水平及国内外放射性物质事故资料,考虑泥沙的影响,设定铯-137不同活度水平、不同流量情形,根据饮用水中铯-137的死亡风险系数和患病风险系数对距离事故点为64 km、114 km的河流下游两个饮用水源地居民饮用受污染自来水存在的健康风险进行评估,同时选择钴-60、锶-90两种核素以30年间河水平均流量偏小值为例进行对比评估。放射性核素在黄河河流的稀释作用下,由饮用受钴-60、铯-137、锶-90污染的水随放射源活度、河水流量及泥沙含量的变化存在不同程度的死亡风险与患病风险。因此,应当对受到放射性污染的水源及时采取适当措施,预防放射性核素造成的风险。

The potential health risk caused by transporting of radioactive material is increasing with the fast development of nuclear energy and nuclear technology. In present paper, the contamination of cesium-137, cobalt-60 and strontium-90 to the Yellow River of Lanzhou region was considered and the dispersion of these radionuclides were modeled. Furthermore, the potential health risk brought out by the radionuclide dispersion to drinking water were discussed. Based on the existing domestic activity of the radionuclide sources and the data obtained from the international radioactive accidents, the activity levels and flow rates of cesium-137 was presented with consideration of the effect brought out by the sediment. The potential health risk of cesium-137 at two different drinking water sources, which were 64 km and 114 km from the accident position in the river downstream, were calculated, respectively. The mortality risk and morbid risk coefficients of cesium-137 were obtained and used to evaluate its health risk induced by ingestion of tap water. At the same time, the potential health rick of cobalt-60 and strontium-90 were also assessed by using the minimum average flow rate of the Yellow River during the nearest past 30 years. All the results showed that the dispersion of cesium-137, cobalt-60 and strontium-90 in the Yellow River varied with the radioactivity of the nuclides, the flow rate of the river and suspended sediment in the river, and ingestion of tap water contaminated by these radionuclides will cause mortality and morbid risk. Hence, it is very important to react promptly to the river drinking water contamination caused by radionuclides so as to reduce their health risk to human beings.