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

第二次世界大战后，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。有三起重大事故，如Techa河污染，与该工厂综合体有关。南乌拉尔的这个地区已经被核废料中大量的放射性核污染，特别是锶-90。锶替代了骨骼和牙齿中的钙，因此，本研究将其纳入牙釉质和牙本质中的羟基磷灰石中，给予内照射剂量。在本研究中，从Ozersk的25个奶牛牙齿中的植物复杂的位置和周围的村庄进行了检查，以获得锶-90和辐射剂量的浓度。使用对β射线敏感的成像板来获得浓度。将牙齿切成两半，并在低背景铅洞穴中放置在成像板上一周。通过成像扫描仪从成像板获得锶-90分布的图像。通过测量含有已知浓度的锶-90的牙本质标准样品，可进行定量测量。这些样本中有5颗牙齿的图像。锶-90在釉质中的浓度较低，但在牙本质和釉质之间的区域较高。最大浓度约为15 Bq/g。来自高污染地区的牙齿具有较高的锶-90浓度，但存在一些差异。用ESR法测量牙釉质受照剂量。4个牙齿样本获得的标称剂量为300至400 mGy，但是，这些应被视为暂定值，因为这些可能被高估，因为背景信号较大，与人类牙齿不同。另一种方案，以获得剂量从牛牙齿应考虑到物种特异性的背景信号。

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.