Estimation of Radiation Dose with Radionuclides in Nuclear Medicine Application

To study the level of radiation dose on nuclear medicine of radionuclides with estimation method. We chose some diagnostic and therapeutic radionuclide to estimate the dose of internal radiation and external exposure with the estimation model of the dose coefficient method and point source. The results showed that the effective dose that patient suffered in a single diagnostic CNM procedure was up to 1.63 Sv; the single effective dose that A and B medical staffs suffered were 1.48 μSv and 1.15 μSv. The dosage level of some part of Diagnostic radionuclide beyond medical guidance level. The estimation results was slightly larger than the measured effective dose, less than other estimation. Combined with the actual situation, the estimation model can be used as an effective estimation method of the radiation dose level of nuclear medicine radionuclide.     

伴生放射性矿中放射性核素检测实验室比对总结

The state has issued a series of measures to regulate the radiation of associated radioactive ores. For this reason, the Beijing Research Institute of Uranium Geology organized the activity of “BRIUG IC-2018 Interlaboratory Comparison of Radionuclides and Heavy Metals in Associated Radioactive Mines”. Our laboratory actively participated in 238U, 232Th, 226Ra, 40K comparing activities and studied measuring parameters, sample loading conditions and so on. Satisfactory results were obtained in the comparison activities.It shows that our laboratory has strong detection ability, which lays a solid foundation for similar radionuclide detection work in the future. Finally, some suggestions for future work improvement are put forward.     

铀尾矿库区浅层地下水中U(Ⅵ)迁移的模拟

在详细分析中国南部某大型铀水冶尾矿库的结构特点、运营情况和库区水文地质条件的基础上，对库区水文地质条件进行概述，运用溶质反应-运移模拟软件PHREEQC-Ⅱ，建立研究区U(Ⅵ)在浅层地下水中迁移的一维溶质反应-输运耦合模型，并分析在不同时间、距离、扩散系数、弥散度等条件下铀在铀尾矿库区浅层地下水中的迁移，即铀浓度随时间及距离的变化。模拟结果与现场观测资料基本吻合，表明该软件能较好地模拟U(Ⅵ)的迁移情况，证明了该模型的可行性。研究还表明，弥散作用对铀迁移有显著影响，弥散度的取值是模拟可靠与否的关键参数，而分子扩散对本模拟的影响可忽略不计。      

海洋γ谱连续监测方法模拟

通过蒙特卡罗程序MCNP(Monte Carlo N Particle Transport Code)建立了海洋γ谱连续监测的测量模型,模拟计算不同能量γ射线在海水中的衰减情况和有效探测距离。根据我国近岸海域海水中天然放射性核素活性浓度,模拟得到不同晶体尺寸NaI探测器连续监测的本底谱,分析能量分辨率对全能峰本底计数率的影响并探讨了影响NaI探测器能量分辨率的因素。最后针对我国核电厂周围海域中重点关注的人工放射性核素,并假设不同尺寸NaI晶体在能量662 keV处分辨率保持7.0%不变的条件下,分别计算了不同尺寸NaI晶体探测器在海洋γ谱连续监测中的探测效率、本底计数率和最小可探测活性浓度等技术参数。模拟结果为海洋或其它水体中γ谱连续监测方法的应用提供技术参考。     

239Pu(Ⅳ)在花岗岩裂隙介质中迁移的数值模拟

基于双重连续介质模型,根据单裂隙岩体核素迁移规律,推导了核素在平行板单裂隙岩体裂隙域和基质域中的迁移方程,并得出了核素在基质域和裂隙域中的相对浓度。模拟过程中选择²³⁹Pu(Ⅳ)作为分析对象,结合研究区渗透系数和分配系数等参数值,分析了研究区花岗岩岩体裂隙域和基质域中相对浓度的分布情况,预测了²³⁹Pu(Ⅳ)在裂隙域和基质域中的发展趋势和迁移情况。模拟表明²³⁹Pu(Ⅳ)在基质域内的扩散非常缓慢,经过0.5×10⁵ a,扩散范围仅在毫米量级,而在裂隙域中大约迁移3m,模拟结果表明该花岗岩区域具备处置含²³⁹Pu(Ⅳ)等放射性废物的条件。同时讨论了裂隙域水的平均速度、隙宽、渗透系数、基质域和裂隙域内阻滞系数等参数的变化对放射性核素裂隙域迁移情况的影响。     

北京市气溶胶放射性核素分析(2013—2016)

利用中国锦屏地下实验室(CJPL)低本底γ谱仪对北京地区近4年34组气溶胶样品中长寿命放射性核素进行研究。发现气溶胶样品中含有²³⁸U、²²⁶Ra、²¹⁰Pb、²³²Th、²²⁸Ra、 ⁴⁰K、⁷Be、¹³⁷Cs,其活度浓度均值分别为17.47 μBq·m^-3、21.19 μBq·m^-3、2.39 mBq·m^-3、11.12 μBq·m^-3、14.43 μBq·m^-3、226.64 μBq·m^-3、6.98 mBq·m^-3、2.36 μBq·m^-3,且均在本底范围之内。同时,放射性核素活度浓度与环境参数存在相关性,⁷Be、⁴⁰K、¹³⁷Cs、²²⁶Ra均与季节负相关,²¹⁰Pb与季节正相关;⁴⁰K与空气质量指数(AQI)正相关。     

混合放射性核素参考溶液的研制

将^103Ru标准溶液中的^103RuCl3转化为Na2[^103RuNO(NO2)4OH]，并通过选择适宜的化学组成和酸度，建立了制备^103Ru,^131I,^137Cs,^134Cs和^40K等混合放射性核素参考溶液的方法。经实验检验和放射性比对测量，结果表明，采用该方法制得的混合放射性核素参考溶液是均匀、稳定的、符合放射性计量标准的要求。     

非饱和黄土介质中含水量对^85Sr迁移的影响

通过对现场示踪试验笔实验室模拟实验的分析和拟合发现,^85Sr在非饱和黄土介质中的延迟系数Rd并非常数,它随土壤含水量θ的增加而增大;而且,Rd随θ的变化趋势也与常用公式计算的结果相反。这表明：对于非饱和黄土,由实验室测量的分配系数Kd直接导出用于现场评价的Rd是不可行的,公式的应用范围以及kd的测量方法和取值亦值得研究。     

2-D NUMERICAL SIMULATION OF RADIONUCLIDE TRANSPORT IN THE LOWER YANGTZE RIVER

The assessment of the radiological impact of the liquid discharges from nuclear power plants is a major issue for the environmental protection. In this study, a numerical model for the radionuclide transport in the aquatic environment is built, based on the hydrodynamic equations, including the complete set of Saint-Venant equations, the sediment transport equations, with consideration of several different particle sizes and the deposition and erosion of the suspended sediments, and the radionuclide transport equations. The exchanges of radionuclides between water, suspended matter and bed sediments are described in terms of kinetic transfer coefficients. The model is used to simulate the transport of the radionuclides discharged from a planned nuclear power plant project to be sited along the lower Yangtze River. From the model results, one may see the detailed temporal-spatial evolution of the radionuclide contamination in the solution, in the suspended matter and in the bed sediments. The model can be used as a basic tool for studying the environmental impacts of the liquid discharges from nuclear facilities on a river system.     

南海岛礁工程中建筑材料的天然放射性核素含量及辐射水平评价

本研究利用高纯锗γ谱仪测量南海15个不同岛礁最主要的建筑材料———珊瑚砂和珊瑚骨骼碎屑中的放射性水平。结果表明,珊瑚砂中²³⁸U、²²⁶Ra、²²⁸Ra、⁴⁰K的平均比活度分别为24.8 Bq/kg、2.38 Bq/kg、2.10 Bq/kg、11.6 Bq/kg;珊瑚骨骼碎屑中²³⁸U、²²⁶Ra、²²⁸Ra、⁴⁰K的平均比活度分别为28.7 Bq/kg、3.47 Bq/kg、12.6 Bq/kg、10.9 Bq/kg;南海岛礁珊瑚砂和珊瑚骨骼碎屑的放射性水平仅为国际推荐限值的1%～10%。通过对比国内外多种建筑材料的放射性水平,南海岛礁珊瑚砂和珊瑚骨骼碎屑拥有很低的放射性水平。珊瑚砂和珊瑚骨骼碎屑作为低放射性水平的建筑材料,可能可以应用于低本底实验室的建设,也可以作为高放射性建筑材料(煤灰渣、矿渣)生产过程中的添加剂(稀释剂),有效降低建筑材料的放射性水平。