外照射辐射监测中的运用量——ICRU第39号报告简介

辐射防护的基本限值量是人体器官剂量当量 H_T 和有效剂量当量 H_E。但是,H_T 和 H_E 都无法直接测量。为便于辐射防护评价,国际放射防护委员会(ICRГ)曾建议,在外照射情况下,采用剂量当量指数 H_I 作为辐射防护的次级限值量,即当身体内剂量当量的实际分布不明时,可以估算由软组织等效材料组成,直径为30cm 的 ICRU 球中,深度大于10mm 范     

ICRU、ICRP新建议中的辐射防护量和单位

1 引言 任何一种物理量应有的属性是可以通过测量或计算、定量描述某一具体物体或现象的某种特性。然而,辐射防护的基本量在实践中常常是不可测量的,这也是由来已久的事实。为此,1980年国际辐射单位与测量委员会（ICRU）第33号报告提出了“指数量”。此后,在辐射防护领域引起了一系列的讨论,特别是对辐射防护测量中使用的量这个问题。讨论的结果引出了ICRU第39号、43号、47号和51号报告。为了对外照射情况下的区域监测和个人监测中用的剂量当量作一详细规定,在39号报告中引入了实用量。后来的ICRU第43号报告（ICRU,1988）和ICRU第47号报告（ICRU,1992）给出了有关这些量的补充资料。ICRU 51     

ICRU 95号报告:外照射实用量及其对剂量学的影响（英文）

国际放射防护委员会(ICRP)提出了“防护量”这一概念。最常用的防护量,即有效剂量E,用于设定照射限值,并在实用辐射防护中使用,以实现最优化原则。然而,有效剂量不是一个可测量的量,基于此国际辐射单位与测量委员会(ICRU)为外照射的剂量测定提出了一个可测量的量,即实用量,用于估计有效剂量。目前使用的实用量定义于20世纪80年代,当时核工业是职业辐射防护的主要关注点。当前,在其他辐射领域,特别是高能辐射,实用量的不足之处变得很明显：可能高估或低估有效剂量。因此,ICRU和ICRP在全面研究的基础上,为外照射的剂量测定提出了新的实用量,以克服上述缺点。实用量的新定义与防护量(包括有效剂量)的定义更具相关性,特别是使用了相同的仿真体模。当前提出的实用量通过缩小防护量与实用量之间的定义差异简化了辐射防护量体系,并从整体上改进了对有效剂量的估计。本文讨论了提出的新实用量对实际剂量测定的影响。     

外照射辐射防护中的量

在外照射辐射防护中,国际辐射单位和测量委员会(ICRU)提出的四个新的辐射量对解决实用量的问题是一个重要进展。本文综述了四个量应用研究进展概况,并着重讨论了实用量与基本限值量的关系和实用量与现有防护监测仪表的特性的适应性问题。文中指出:目前对四个量的应用研究已积累了相当多的数据;由这些数据资料可以看出,新量在大多数情况下不会低估或过高地高估限值量;多数现有防护监测仪表基本上能满足测量新量的要求;但是还存在一些具体问题,如个人监测量[贯穿性个人剂量当量H_P(10)和浅表个人剂量当量H_S(0.07)]的刻度问题需要解决,新量体系的推广应用还有待时日。     

外照射光子和电子辐射的剂量当量测量

1 测量方法 ICRU第39号报告给出了用于环境监测和个人监测的4个实用辐射量:周围剂量当量、定向剂量当量、深部个人剂量当量和浅表个人剂量当量,并建议用这些实用辐射量来校准辐射防护仪器。在提出这些新量的同时,ICRU已考虑到:除了对现有辐射防护仪器的标度名称及其刻度作必要的改变外,仍容许继续使用（或稍加修改）现行的辐射防护仪器的校准方法。目前的辐射防护仪器都是用空气比释动能、照射量或空气吸收剂量作为校准量进行校准的,为使其转化（或再校准）为所要求的剂量当量,就需要乘上一个合适的转换因子（亦称为转换系数）。 实际校准时,仍是沿用通行、常规的方法来确定仪器的校准因子N,即 N=H/M （1）式中M为在已知剂量当量H的校准辐射场中的仪器读数。这种校准是在特定的条件（如ISO推荐的辐射场）下完成的;但是其校准量通常不是剂量当量,因此要求利用所计算的转换因子来求得剂量当量。例如,当校准γ射线巡测仪时,最初的校准量可以是空气比释动能或照射量,那么由空气比释动能或照射量到周围剂量当量的转换因子就用来确定剂量当量。这个转换因子就是上面的校准因子N。     

光子和电子辐射外照射剂量当量的测定

光子和电子辐射外照射剂量当量的测定１引言多年以来，剂量当量就是辐射防护中的基本量。然而，在什么条件下来测定剂量当量却一直意见不一。１９７７年国际放射防护委员会（ＩＣＲＰ，１９７７）建议，对随机性效应的剂量限值应基于有效剂量当量ＨＥ来制定。国际辐射单位...     

关于现有X,γ射线防护监测仪对测量光子周围剂量当量适用性的探讨

本文扼要地论述了现有 X,γ射线防护监测仪对测量 ICRU 第39号报告定义的周围剂量当量的适用性问题。     

“外照射实用运行量”联合报告草案

正国际辐射单位与测量委员会(ICRU)与国际放射防护委员会(ICRP)"外照射实用运行量"联合报告草案现在向公众开放征求意见。草案文档可从ICRP网站下载。提交意见的时间截至2017年11月3日。内容概要:委员会为确定外照射量定义了一套通过测量或计算得出的实用运行剂量量。该量对ICRP提出的通常无法测量的防护量值进行估算。目前使用的ICRU实用运行剂量量定义于30年前。将最近防护量定     

外照射辐射防护中使用的实用量

本文简要地回顾了外照射辐射防护中使用的实用量概念的进展情况,介绍了国际辐射单位与测量委员会(ICRU)47号报告中提出的新建议,并针对实用量在应用中的一些问题进行了讨论。     

监测用剂量当量

国际辐射单位和测量委员会(ICRU)于1985年2月发表了39号报告;“外部辐射源产生的剂量当量的测定”,该报告是由一个关于剂量当量实际测量的专门委员会拟定的,作为对ICRU25号和33号报告中有关应用吸收剂量指数和剂量当量指数的建议在实际测量方面的补充。报告中定义了监测用剂量当量,这些量在定义的严谨、实际可测性以及与ICRP当前的剂量限制体系的密切关联等方面都是以前定义的指数量所不能比     

CEFR 100%额定功率运行汽轮机发电能力分析

中国实验快堆(CEFR)首次100%额定功率发电运行中,实际电功率较设计值相差较多。为判断影响机组实际发电能力的主要原因,以现场采集的运行数据和汽轮机厂商提供的设计资料为基础,进行了相应的计算分析。对汽轮机内效率进行修正,绘制汽轮机近似热力过程曲线,并通过实测的各段抽汽压力,在热力过程曲线上获得抽汽焓值;利用换热器的能量守恒和流量守恒的基本方程进行除氧器和各加热器的热平衡计算,获得各段抽汽的流量;利用汽轮机的功率计算方程,得到汽轮机发电功率的计算值。通过计算值与实际值的比较分析,得出主蒸汽参数不达标是影响CEFR汽轮机发电能力的主要因素。     

旁路阀调节对高温气冷堆闭式布雷顿循环瞬态特性影响研究

闭式布雷顿循环是第4代高温堆核能系统的关键技术之一,其典型的动态过程是旁路阀调节。为分析这一过程,建立了循环中关键部件的动态模型,其中压气机在径向平衡模型基础上耦合了对附面层发展的预测,兼顾了计算效率与准确性;换热部件模型基于双曲型守恒律方程,对工质的热物性和参数的快速变化有较好的适应性。在此基础上根据回路的质量守恒和压力平衡原则将各部件的模型耦合,建立了系统的动态模型。由于旁路阀调节是氦气透平发电系统主要的功率快速调节手段,瞬态效应较为显著,以模块式高温气冷堆（HTR-10GT）旁路阀开启后的过渡过程作为算例,分析了主要循环参数的响应特性,并通过分析,给出了降低输出功率的机制。计算结果表明：系统的容积惯性对旁路阀调节的响应速度影响较大,而阀门的开度则决定了系统在末态的输出功率;回热器的温度冲击现象可能发生在调节过程中,但可通过两旁路阀联动的方式缓解;反应堆出口温度变化幅度很小,因此反应堆模型的准确程度对结果基本无影响。     

Unfolding the measured neutron spectra in the irradiation chamber of the UZrH reactor using iterative method

In the procedure of neutron fluence measurement in the whole energy range （10^-4 eV-18 MeV）, in the irradiation chamber of a UZrH reactor, the neutron energy spectra are unfolded using the method of minimizing directed divergence and SAND-II, which are used broadly at home and abroad. These methods belong to the iterative methods. In this article, the procedure of the spectra unfolding using the two methods is described in detail. The neutron spectrum distribution unfolded by the two methods agree well with each other. In the end, the major differences of the two iterative methods are compared with each other, and the main factors affecting the accuracy of the spectra unfolding with the iterative method are discussed.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

抗振条面内接触刚度对蒸汽发生器传热管流致振动的影响

流弹性失稳是引起蒸汽发生器传热管管束失效的一种主要原因。在相同流场条件下,传热管是否出现流弹性失稳与其模态频率直接相关。在实际结构中,抗振条对U型传热管弯管段面内支撑机理与面外的方向上不同,是通过摩擦约束实现的。这使得在模态分析计算中,传热管弯管段支撑处的边界条件设置非常重要。本文将传热管与抗振条接触点处的面外边界条件假设为简支,而在面内方向上用弹簧来模拟抗振条对传热管的摩擦约束。同时,通过改变弹簧刚度,讨论了不同强弱的面内支撑对传热管流致振动的影响。分析结果表明,当抗振条与传热管面内接触刚度较弱时,面内流弹性失稳可能较面外流弹性失稳出现得更早。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

Remote open-path laser-induced breakdown spectroscopy for the analysis of manganese in steel samples at high temperature

A remote open-path laser-induced breakdown spectroscopy(LIBS) system was designed and studied in the present work for the purpose of combining the LIBS technique with the steel production line. In this system, the relatively simple configuration and optics were employed to measure the steel samples at a remote distance and a hot sample temperature. The system has obtained a robustness for the deviation of the sample position because of the open-path and alloptical structure. The measurement was carried out at different sample temperatures by placing the samples in a muffle furnace with a window in the front door. The results show that the intensity of the spectral lines increased as the sample temperature increased. The influence of the sample temperature on the quantitative analysis of manganese in the steel samples was investigated by measuring ten standard steel samples at different temperatures. Three samples were selected as the test sample for the simulation measurement. The results show that, at the sample temperature of 500 ℃, the average relative error of prediction is 3.1% and the average relative standard deviation is 7.7%, respectively.     

Accumulation of Co in Yeast Cells under Metabolically Active Condition—Implication for Role of Yeast in Migration of Radioactive Co—

The accumulation and change in the chemical states of Co have been studied to elucidate the role of the yeast Saccharomyces cerevisiae in the migration of radioactive cobalt in the environment. The yeast was grown in a solution containing Co(II) ions, a carbon source, and essential elements (metabolically active condition). For comparison, an adsorption experiment of Co(II) ions on the yeast cells under resting condition without essential elements was performed. Time courses of Co concentration in the solution, in the cells, and chemical states of the accumulated Co were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), particle-induced X-ray emission (PIXE), and X-ray absorption fine structure (XAFS) analyses. The time courses of Co concentration in the solution showed that a higher amount of Co was accumulated by the yeast cells under the metabolically active condition than under the resting one. PIXE analyses showed the concurrent accumulation of Fe with Co accumulation under the metabolically active condition, suggesting the intracellular accumulation of Co. XAFS analyses showed that the k³-weighted extended-XAFS functions and the radial structural function of Co accumulated by the yeast cells under the metabolically active condition are similar to those under the resting condition, indicating that the chemical states of the accumulated Co were nearly the same between both conditions. These results indicate that the yeast performs better retardation of the migration of Co under the metabolically active condition than under the resting one.     

Extraction of Uranium from Sea Water by Method of Dispersion and Deposition

The extraction of uranium from sea water by the adsorption on the mixture of titanic acid and bentonite making the uranium rich deposit on the sea bottom is described. The purpose of this work is the minimization of energy required for contacting the vast volume of sea water with the adsorbent. Unique features of bentonite are applied to the coagulation of adsorbent forming the particles of suitable size in the sea water to make uranium rich deposit on the sea bottom close to the land. The concentration of uranium in the deposit is about 380 times that of sea water, and the loss of titanium is about 2% of the total amount of titanium which is used with the bentonite of ten times as much as it.

The depths of sea necessary to make uranium rich deposit for the various conditions were calculated and the result was obtained that 50 m was sufficient for this method. As a trial of the second stage of concentration of deposited uranium, the continuous RIP method was carried out in counter-current fluidized bed which was operated without reversal of flow.

The results reported in this paper are based on the laboratory scale experiments using the artificial sea water and on the calculations concerned with the rate of adsorption in agitated systems.