辐射工作场所改造中的辐射监测与管理

主要介绍辐射工作场所改造前期的辐射监测与管理经验。在辐射场所改造前期,预先对改造场所进行调查,制定工作计划,选择合适的仪器和设备,设计监测流程,培训人员并结合实际进行现场处理,较好地完成了前期去污、拆除和场所清理工作,为辐射场所改造中后期工作的顺利开展打下了坚实的基础。     

某矿山222Rn及其子体污染的调查

介绍了2005～2007年用DHZM-I型氡及其子体连续监测仪对某矿山的工作场所和生活区分别进行环境氡及其子体浓度的测量。监测结果表明,所监测的工作场所中,大部分监测点的氡及其子体浓度都在国家规定的限值范围内;在居民区,扣除本底后,未发现任何监测点的个人有效剂量当量超过国家规定的限值。笔者还对该矿山的平衡因子进行了分析研究,并给出了研究结果。     

工作场所辐射监测与核安全辐射防护管理

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     

131I气溶胶垂直分布特性研究

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。     

被动式氚取样器性能的实验研究

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。     

工作场所的氡

2000年5月欧盟成员国完成了新的基本安全标准(BSS)指令。该指令的第Ⅷ部分特别适用于工作场所的氡。要求成员国监测有关的工作场所，在这些场所安装适当的装置监测氡的照射，如若必要，使用全部或部分放射防护系统。BSS对天然辐射的规定是基于国际放射防护委员会(ICRP)1990年的建议。在1992年芬兰制定的辐射法规中已对该建议作了考虑，结果是确定控制所有类型工作场所的氡。本文根据过去7a芬兰监测工作场所氡的经验，就BSS有关氡职业性照射的实际情况进行了论述。     

某压水堆核燃料元件生产线辐射水平及对作业人员的健康影响

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。     

大茶园矿氡及其子体监测方法和工人的受照剂量

本文简要介绍了大茶园矿氡及其子体浓度的监测方法,由近五年1967对监测数据,得到的平衡因子 F 均值为0.33。根据对22名采掘工人连续6个月的工时调查工作场所的氡及其子体浓度和γ照射量率监测数据,采用 ICRP 第32号出版物中推荐的剂量换算因子,算得由吸入氡子体和γ外照射引起的采掘工人的人均年有效剂量当量分别为0.042Sv 和0.0027Sv。     

核医学工作场所放射性污染探讨

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。     

某稀土冶炼厂放射卫生现状调查

报道了对某稀土冶炼厂辐射环境和职业性查体调查结果。调查的主要内容有：环境放射性检测与评价,工人肺内钍沉积量测定及其对健康的影响。调查结果表明：该厂4个接尘车间属于放射性工作场所,9名接尘工人肺内钍沉积量超过1个调查水平（2．22Bq）,未发现接尘工人中出现尘肺,其外周血象和肝功能均未发现异常。     

潘生丁—^201Tl心肌灌注显像五年预后意义分析

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。     

Energy Transfer in Alkali Halide Scintillators by Electron-Hole Diffusion and Capture

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.     

Low temperature radioluminescence spectra of CsI:Tl

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 V_K-e excitons, respectively, and the 340 nm band is related with the unperturbed H-F excitons. It is suggested that V_K 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.     

Dependence of the NaI(Tl) Pulse Shape on Thallium Concentration and Temperature

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.     

The Scintillation Mechanism in Thallium Doped Alkali Halides

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.     

Vapour phase concentrations of volatile nuclear reaction products in the MEGAPIE cover gas

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.     

Liquid-metal plasticizer for forming fuel-element kernels

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.     

BMIPP的同位素标记条件的研究

研究了一种碘标的新方法－新生态Ⅰ价铜法,并与其它碘标方法作了比较。研究了其标记条件,经TLC和放射自显影证实,标记率可达95％以上。     

Energy Transfer and the Role of Thallium Dimers in the Nal(Tl) Scintillation Process

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.     

~(204)Tl在几种金属和非金属表面上的释放行为研究

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。