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Distribution of the radiation doses in South Urals of former Soviet Union investigated by Electron Spin Resonance dosimetry of mammal teeth

哺乳动物牙齿电子自旋共振剂量测定研究前苏联南乌拉尔地区辐射剂量分布

基本信息

批准号：
13575033
负责人：
TOYODA Shin
金额：
$ 6.02万
依托单位：
Okayama University of Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

After the World War II, former Soviet Union constructed its first plant complex in South Ural, which produces plutonium, starting its operation in 1948. There were three major accidents, such as contamination of Techa river, associated with this plant complex. This region of South Ural has been contaminated with huge amount of radioactive nuclei from nuclear waste, especially with Strontium-90. Strontium replaces calcium of bones and teeth, therefore, it is taken into hydroxyapatite of tooth enamel and dentin which are examined by the present research project, giving internal doses. In the present study, 25 cow teeth from Ozersk in which the plant complex is located and from surrounding villages were examined to obtain the concentrations of Strontium-90 and radiation doses. Imaging plates sensitive to beta rays were used to obtain the concentrations. The teeth were cut in half and were placed on an imaging plate for a week in a low background lead cave. The images of the Strontium-90 distribution were obtained by the imaging scanner from the imaging plate. Quantitative measurement was available by measuring the standard samples of dentin containing known concentrations of Strontium-90. The images were found for 5 teeth of those samples. The concentrations of Strontium-90 were low in enamel but higher in the region between dentin and enamel. The maximum concentration was about 15 Bq/g. Teeth from highly contaminated area have higher Strontium-90 concentrations but with some variations. The radiation doses given to tooth enamel were measured by ESR method. Nominal doses of 300 to 400 mGy were obtained for 4 teeth samples, however, these should be considered to be tentative values because these may be overestimated due to larger background signal which is different from human teeth. Another scheme to obtain doses from cow teeth should be developed with considering the species-specific background signal.

二战后，前苏联在南乌拉尔建造了第一座生产钚的工厂，于1948年开始运营。与该核电站相关的三起重大事故，如特查河污染。南乌拉尔的这一地区已经被核废料产生的大量放射性核污染，特别是锶-90。锶替代了骨骼和牙齿中的钙，因此被吸收到牙釉质和牙本质的羟基磷灰石中，给出了内照射剂量。在本研究中，对工厂所在的厄泽尔斯克及其周围村庄的25颗牛牙进行了检测，以获得锶-90的浓度和辐射剂量。使用对β射线敏感的成像板获得浓度。这些牙齿被切成两半，并被放置在成像盘上，在一个低背景的铅洞中持续一周。用成像扫描仪从成像板上获得锶-90分布的图像。定量测量是通过测量含有已知浓度的锶-90的牙本质标准样品来实现的。在这些样本中发现了5颗牙齿的图像。锶-90在牙釉质中含量较低，但在牙本质与牙釉质之间的区域含量较高。高污染区牙齿的锶-90浓度较高，但有一定的变化。用电子自旋共振(ESR)法测量牙釉质的辐射剂量。4个牙齿样本的标称剂量为300~400mGy.然而，这些值应被认为是暂定值，因为与人类牙齿不同的背景信号较大，这些值可能被高估。应考虑特定物种的背景信号，开发另一种从奶牛牙齿获得剂量的方案。