The Evaluation of a Simple Measurement Method using NaI(Tl) Scintillation Survey-Meter for Radiation Safety Management of Radioactivated Armor Tiles of LHD Vacuum Vessel
The Evaluation of a Simple Measurement Method using NaI(Tl) Scintillation Survey-Meter for Radiation Safety Management of Radioactivated Armor Tiles of LHD Vacuum Vessel
复制标题
NaI(Tl)闪烁测量仪简易测量方法对铲运机真空容器放射性装甲板辐射安全管理的评价
DOI：
10.12950/rsm.210416
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
M. Osakabe
中科院分区：
文献类型：
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作者：
Makoto I. Kobayashi;N. Suzuki;T. Saze;H. Miyake;K. Nishimura;H. Hayashi;T. Kobuchi;K. Ogawa;M. Isobe;M. Osakabe
1)、2)本研究利用NaI（Tl）闪烁测量仪对LHD真空容器在氘等离子体实验中暴露于快中子中的装甲瓦进行了简单的测量，以控制大量装甲瓦储存的职业暴露。高纯锗探测器（HPGe）对活化装甲砖的伽马能谱分析显示了58 Co， 54 Mn和60 Co的伽马射线峰。通过PHITS评估了这些核素对HPGe的探测效率，以估计这些核素的浓度。通过密封伽玛射线源的伽玛射线测量，验证了高温锗在PHITS中的辐射输运模型。然后，用PHITS对这些核素在NaI（Tl）闪烁测量仪上的探测效率进行了同样的评价。NaI（Tl）闪烁测量仪对活性装甲片的预测剂量率与实际测量结果一致。由于具有较长的半衰期，60 Co将成为装甲层中的确定核素，在间隙水平上，NaI（Tl）闪烁测量仪的预测计数率足以高于具有简单环境辐射屏蔽的NaI（Tl）闪烁测量仪的最小可探测计数率。
1),2) In this study, the application of a simple measurement method using NaI(Tl) scintillation survey-meter to detect the gamma-rays in the armor tiles of LHD vacuum vessel exposed to fast neutrons during deuterium plasma experiments was evaluated to control the occupational exposure for the storage of huge numbers of the armor tiles. The gamma-ray spectrometry for an activated armor tile by high-purity germanium detector (HPGe) showed the gamma-ray peaks from 58 Co, 54 Mn and 60 Co. The detection efficiencies of these nuclides for HPGe were evaluated by PHITS to estimate the concentrations of these nuclides. The radiation transport model for HPGe in PHITS were validated by the gamma-ray measurements for sealed gamma-ray sources. Then, the detection efficiencies of these nuclides for NaI(Tl) scintillation survey-meter were also evaluated by the same manner using PHITS. The predicted dose rate of the activated armor tiles in NaI(Tl) scintillation survey-meter was consistent with the actual measurement. The predicted count rate in NaI(Tl) scintillation survey-meter for 60 Co, which will be a deterministic nuclide in the armor tile due to longer half-life, in the clearance level was sufficiently higher than the minimum detectable count rate of NaI(Tl) scintillation survey-meter with a simple shielding for environmental radiation.