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被动式累积测tu方法研究 总被引:3,自引:3,他引:0
研究了平等测量氡、?暴露量和国吸收体甄别掉氡的直接测量?暴露量的两种方法,并建立了简易刻度系统。平行测量氡、?暴露量时,两个相同剂量计的过滤窗分别装上不同滤材,使两个剂量计的扩散速率常数λd存在一定的差异,而导致它们测量氡、?时具有不同的响应。该方法测量氡、?暴露量的探测下限分别为0.74kBq.m^-1.h和1.25kBq.m^-3.h。加吸气体甄别掉氡测?的方法是在CR-39SSNTD上加盖45μm铝膜和10μmPE塑料膜甄别掉氡及其子体产生的α粒子,直接测量?的衰变子体^212Po(ThC′)产生的部分α粒子。该方法测量?暴露量的探测下限为22.1Bq.m^-3.h。 相似文献
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本文介绍了烟盒式和无芯电池式两种被动式热释光氡累积探测器,可用于室内及矿井空气中氡的监测。本探测器具有体积小、重量轻、携带方便等优点。通过比对和现场应用,证明这些探测器的测量结果是可靠的。 相似文献
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核电厂运行寿期内放射性气载流出物通过烟囱向环境排放,其中部分放射性物质会沉降并在环境中累积。为评估其累积效应,本文选取3H、14C和以气溶胶形式存在的88Kr/88Rb、60Co、131I和137Cs作为代表性核素,采用3H、14C平衡模型和气溶胶迁移扩散模型,分析了核电厂运行寿期内各核素的环境累积活度浓度。分析结果表明:代表性核素显示出了环境累积效应,绝大多数代表性核素的环境累积活度浓度远小于0.1 Bq/kg,但3H和14C的环境累积活度浓度略高,分别达2.51 Bq/kg和2.35 Bq/kg;各核素环境累积活度浓度预测结果远低于EPR-RSR给出的相应限值,不会对土地再利用造成影响;以气溶胶形式存在的放射性核素的环境浓度表现出较明显的累积增长趋势,增长趋势与半衰期和放射性核素在环境中的迁移行为相关。根据研究结果,对我国核电厂环境影响评价中典型核素的环境累积效应预测和环境监测提出了建议。 相似文献
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ESR法测牙珐琅化石年龄中累积剂量测量的初步研究 总被引:5,自引:3,他引:2
研究了牙珐琅化石的ESR信号对辐射剂量的响应关系,讨论了用指数函数拟合定牙珐琅累积剂量AD的适用范围和所产生的系统误差的大小,并以郧县古人类遗址牙珐琅样品为实例检验了上述研究结果。 相似文献
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用于被动积分测 220Rn剂量计刻度的简易 220Rn室 总被引:4,自引:3,他引:1
用有机玻璃板制作了一 3 5 0mm× 2 5 0mm× 1 80mm的2 2 0 Rn积累箱 ,用特制的闪烁室测量2 2 0 Rn室内2 2 0 Rn水平 ,闪烁室测量2 2 0 Rn的刻度因子是用标准氡源刻度其对氡及其子体释放α粒子的探测效率 ,并经能量修正后得到。2 2 0 Rn源和循环气流混合后以约 1 3L·min-1充进积累箱 ,其2 2 0 Rn水平通过充源回路添加不同体积的延迟箱和气体流量的控制加以调节。在充源和循环气流条件不变时 ,测量充源孔和循环孔所在两个侧面上不同位置采样孔的2 2 0 Rn水平 ,测量结果的相对标准偏差为 0 3 % ;每 1h测量一次 ,连续 1 0h在同一采样孔采样 ,测量结果的相对标准偏差为 1 0 %。系统总不确定度小于 5 6%。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(8):716-719
Compared with radon (222Rn) and its progeny, thoron (220Rn) and its progeny have not been well studied in the natural radiation fields. In this paper, some important factors (232Th content in soil and building material as well as building structure) relating to the level of indoor thoron and its progeny in China are reviewed. Limited results of small-scale surveys are also cited. The facts indicate that the public exposure from the inhalation of thoron progeny may be higher than the representative value in the UNSCEAR 1993 report, and thoron and its progeny may be a significant indoor pollutant in some regions or specific dwellings in China. 相似文献
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对氡析出率测量的影响 总被引:1,自引:0,他引:1
采用局部静态法测量介质表面的氡析出率时 ,受表面同时析出 土气的影响 ,测量值可能偏高。由于土气子体 2 16Po的半衰期T1/2 =0 .1 5s,在设计氡析出率测量装置时 ,合理选择采样器高度可有效减小甚至克服 土气对氡析出率的测量影响。用采样截面为1 88mm、高 1 2 5mm、内加静电场 (由直流电源或驻极体产生 )的采样器 ,采样周期分别为 1、2和 3h ,被测介质表面 土气析出率比氡的高 2个数量级条件下 ,研究了氡析出率受 土气干扰的程度。理论计算结果表明 :采用CR 39固体核径迹探测器的驻极体多功能快速测氡仪和电源式多功能快速测氡仪测量氡析出率时 ,测量结果受 土气的干扰可能偏大 35 5 % ,而采用金硅面垒作探测器的PCMR 1连续测氡仪测量 ,氡析出率受 土气的干扰可忽略不计。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(9):799-803
Small surveys on thoron, radon and their progeny were carried out in four areas in China. Both high thoron concentrations near to walls and high thoron progeny concentrations were found in some dwellings through the surveys. It is suggested from the limited data that attention shall be paid to the exposure from the inhalation of thoron and its progeny in some kinds of dwellings or areas, and much works on thoron study in detail is necessary. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(4):664-672
In this study, the authors considered the effect of soil moisture in the emanation process of radon and thoron gases. Weathered granite soil was selected as the test soil and it was packed in a polypropylene container (275 × 210mm2 and 100mm in height), up to 50mm in depth from the bottom. The container was covered with the exhalation rate measuring instrument adopting the accumulation method and γ-particles were counted at 30 s intervals for 30 min to estimate the exhalation rates. A sporadic increase in the radon and thoron exhalation rates was caused by the increase in the moisture content up to 8%. However, the exhalation rates showed a decreasing tendency with the increase in moisture content over 8%. Although the measured radon exhalation rate was about 25% of the calculated one, both measured and calculated radon exhalation rates had similar trends with an increase in the moisture content in the soil. The measured thoron exhalation rate agreed well with the calculated one. When the moisture content was in the range of 3.5–18%, it was considered that applying the correlation between the moisture content and the measured thoron exhalation rate is useful for estimating the thoron effective diffusion coefficient. 相似文献
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Lu Guo Volkmar Schmidt Oliver Meisenberg Qiuju Guo Jochen Tschiersch 《Journal of Nuclear Science and Technology》2016,53(12):1999-2005
For the purpose of directly measuring radon and thoron progeny concentrations simultaneously, an unattended battery-operated progeny measurement (UBPM) device, which samples aerosol particles in an electric field, was improved by adopting two different thickness aluminum foils for alpha particles discriminating. The equations for the calculation of the results were derived, and a series of calibration experiments and comparison tests were carried out in the potential alpha energy concentration calibration chamber in BfS Berlin and the HMGU experimental thoron house, respectively. Results show that the calibration coefficients are stable in different levels of radon and thoron progeny. The lower level detection limits of the device for radon and thoron progeny concentration are 1.22 and 0.14 Bq m?3, respectively, for three months exposure. The instrument proved to be independent from environmental conditions in ordinary living room conditions (humidity <65% RH, aerosol particle concentration >1500 cm?1). Comparison results show that the measurement results of the UBPM device are comparable with the reference instrument and suitable for long-term radon and thoron survey in dwellings. 相似文献
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针对闪烁室法^222Rn、^220Rn的测量装置,介绍了一种调节仪器最佳工作状态的比较完善的方法,并用实验进行了探测效率比较。结果表明,通过调节闪烁室法测量此^222Rn、^220Rn浓度装置的工作状态,可以提高仪器的探测效率约10%。 相似文献
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非能动技术在核电工程领域越来越受重视,文章列举了非能动自然循环在核电系统中的应用,对其在运行过程中可能存在的问题进行了分析。介绍了非能动自然循环可靠性分析目前的数学研究方法,并简要总结了这些方法的优缺点。最后展望了非能动自然循环的发展方向。由于非能动自然循环存在失效的可能,在系统运行过程中应对非能动自然循环物理过程失效及其可靠性予以足够重视和积极研究;为了确保系统运行的安全性,系统运行过程中要能动与非能动相互结合,同时选择精确模型,完善非能动可靠性分析方法,准确实现理论计算与实验验证。 相似文献