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2001年,我院现场辐射防护人员对反应堆、加速器、同位素生产车间及放射性化学实验室等工作场所进行了辐射监测,监测内容包括:表面污染、气溶胶浓度和辐射场(γ、中子)。通过监测并采取切实可行的措施,有效地控制了污染和工作人员受照剂量,对于确保工作人员的健康与安全、保证科研生产顺利进行以及加强核安全与辐射防护管理起到了监督作用。1 个人剂量和工作场所监测 相似文献
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为了解放射性气溶胶垂直分布情况,优化气溶胶监测及防护措施,在相同条件下,采集4组放射性工作场所空气中~(131)I气溶胶样品,通过γ谱仪对样品进行分析。实验结果表明,~(131)I气溶胶浓度随高度的增加而逐渐减小,并按指数衰减规律衰减。提示,应优化放射性工作场所气溶胶监测及防护措施。 相似文献
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被动式氚取样器性能的实验研究 总被引:1,自引:0,他引:1
介绍了核设施工作场所和环境空气中氚化水蒸气HTO的监测,被动式氚取样器在国外已经得到非常广泛的应用,所研制的被动式氚取样器,特别适用于7-30d的长期取样,给出该取样周期内空气中HTO浓度的平均值。 相似文献
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根据相关的放射卫生国家标准与方法,为保护放射工作人员和公众的健康,对某压水堆核燃料元件生产线工作场所进行了职业危害因素识别,对场所的γ剂量率、主工艺生产岗位α、β表面污染平均水平、α放射性气溶胶浓度进行了监测,对工作人员受照剂量及职业健康体检进行了调查。结果表明,该压水堆核燃料元件生产线属职业病因素危害严重的建设项目,在正常运行时,作业场所的放射性水平符合《电离辐射防护与辐射源安全基本标准》的要求,在正常运行条件下该生产线不会对工作人员的身体造成辐射危害。 相似文献
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随着核医学快速发展,99mTc、18F、131I等放射性核素引起的内照射污染应引起重视。对两家医院核医学科工作场所开展空气中放射性核素浓度监测,对核医学工作人员开展内照射监测,探讨核医学科内存在放射性核素污染的原因。结果发现,核医学工作场所中存在18F、131I气溶胶,未发现99mTc气溶胶;核医学工作人员体内存在131I内照射污染;核医学工作人员外照射个人剂量监测结果正常。通过对两家医院核医学工作场所的共同性分析,讨论造成放射性核素污染的原因以及如何避免核医学放射性核素污染。 相似文献
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选用Logistic回归对潘生丁-~(201)Tl心肌显像作了预后分析。在五年随访期间,41例受检者中有13例发生心肌事件,其中心因性死亡5例,心肌梗塞8例。结果提示潘生丁铊显像有明显的预后意义,异常显像将增加随后发生心肌梗塞或心因性死亡的危险性(O.R.=18.54)。暂时性多壁段缺损可进一步增加心脏事件的危险度。 相似文献
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This paper reviews recent calculations and experiments dealing with charge transport and capture in activated alkali halide scintillators. Both electrons and holes are captured at thallium sites in crystals such as KI(Tl) and NaI(Tl). The kinetics of charge transport is governed either by the diffusive motion of the self-trapped hole, or by the release of electrons from a thallium site. 相似文献
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Z. Wu P.D. Townsend 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(21):4757-4761
Four radioluminescence bands associated with thallium at 400, 488, 550 and 593 nm, plus an intrinsic band at 340 nm have been observed in the temperature range 280-25 K in CsI:Tl. The temperature dependence of the emission intensity is obviously different from each band to another. The 488, 550 and 593 nm bands are associated with the decay of different type thallium perturbed VK-e excitons, respectively, and the 340 nm band is related with the unperturbed H-F excitons. It is suggested that VK centres are also involved in the emission of the 400 nm photons. The re-absorption of the 488 nm signals and the resulting increase of the 593 nm band have been discussed. At 25 and 290 K, the relative RL intensities between the four thallium associated bands do not change with the X-ray tube voltage from 15 to 40 kV. But the intensity of the 340 nm band increases faster than that of the thallium related bands when the tube voltage increases. 相似文献
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The pulse shape of ?-induced photopeak scintillations in NaI(Tl) has been measured as a function of temperature for several standard commercial crystals and for crystals containing known thallium concentrations. A detailed analysis of the data indicates that the first two microseconds of the pulse is characterized by at least nine separate decay processes. Four of these are attributed to one radiative and three metastable states associated with a thallous ion. Two fast processes are attributed to emission characteristic of pure NaI while two others are associated with high thallium concentration. Energy transport is suggested as the ninth process. 相似文献
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Kaufman R. Gilbert Hadley Wayne B. Hersh Herbert N. 《IEEE transactions on nuclear science》1970,17(3):82-88
In the scintillation mechanism for alkali iodides doped with thallous iodide: 1. Most of the luminescence, and possibly all of it, is from recombination and therefore energy transfer is predominantly from charge transport to thallium. 2. There are two modes of recombination at thallium which differ in the sequence of charge trapping at Tl+. The electron may be trapped before a mobile hole recombines with it, or the hole may be trapped before recombination with a free electron. 3. Thermal hole diffusion is an important process at room temperature and determines which mode a recombination event follows. 4. Both modes of recombination are active. 5. There is non-thermal hole trapping which is a significant part of the scintillator mechanism. 相似文献
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The licensing of the prototype liquid lead bismuth spallation target MEGAPIE required the assessment of the amount of radioactivity that can be released from the liquid metal to the gas phase under various scenarios. To estimate the radiological consequences of evaporation processes under normal operation conditions, the concentrations of hazardous volatile radionuclides in the gas phase of the MEGAPIE expansion volume were estimated using a simplified model based on an equilibrium state. In this report, we focus on those volatile impurities that do not show a strong retention in the liquid metal caused by chemical interactions, comprising mercury, cadmium and thallium. For mercury, temperature functions for the effective vapour pressure of mercury over liquid eutectic lead bismuth alloy were deduced from experimental data and compared to literature data available for the binary systems Hg-Pb and Hg-Bi. Conservative functions were selected from the data on hand for the evaluation of the maximum possible amounts of mercury, cadmium and thallium radioactivity in the gas phase of the MEGAPIE target. Substantial amounts of radioactive mercury are predicted to be released to the cover gas phase of MEGAPIE and liquid lead-alloy based spallation targets in general. The radioactivity resulting from evaporation of cadmium and thallium nuclides is expected to be low. Consequences for liquid metal spallation target systems are discussed. 相似文献
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It is proposed that the possibility of fabricating fuel elements by extrusion using nonremovable liquid-metal plasticizer
be investigated. Alloys of sodium with potassium and thallium are examined as plasticizers. The implementation of this method
will permit fabricating fuel elements remotely using high-activity fuel produced in breeder reactors. 相似文献
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The thallium dimer center, which is a pair of thallous ions occupying nearest neighbor cation sites in NaI, is found to have a decay time of less than 7 nanoseconds. Analysis of the emission spectrum of a typical NaI(Tl) scintillation crystal indicates that the dimer centers are responsible for approximately 25% of the scintillation light although only a small part of this is rapid. It is proposed that energy of excitation migrates among the monomers and between monomers and dimers as a result of thermal excitation. 相似文献
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Tl作为类113号元素,测定了它在Ni,Pd,Mo,Ta,Zr,Ti,Au,Ag,Cu,Fe等金属表面上和SiO_2及石墨等非金属表面上的释放率和释放动力学,理论上计算了Tl在上述金属表面上的附吸焓并与实验结果进行了比较,讨论了两者之间存在差异的原因以及有关的影响因素。定性地预计了113号元素在上述表面上的释放行为和吸附焓。 相似文献