动力堆辐照元件中燃耗测定和~(149)Sm,~(150)Sm含量,~(154)Eu/~(155)Eu,~(154)Eu/~(152)Eu比值与燃耗的关系

本文用同位素稀释质谱法,以~(148)Nd为燃耗监测体对某动力堆元件的燃耗进行了测定。还测定了裂变产物中的高中子毒物~(149)Sm的含量。对~(150)Sm的含量测定结果表明,它能反映出核燃料燃烧的程度,为一直线关系。γ谱法测得的~(154)Eu/~(155)Eu比值和燃耗呈曲线关系。     

烯土元素干扰裂变产物~(149)Sm测定的研究

一、前言 ~(235)U热中子裂变产生的裂变产物钐有~(144)Sm、~(147)Sm、~(149)Sm、~(152)Sm、~(154)Sm同位素,其中~(148)m热中子吸收截面最大,约41000靶。~(149)Sm对反应性影响甚大,在反应堆技术中人们又称之为可燃毒物。为了确定裂变产物~(149)Sm的绝对量,一般都采用同位素稀释质谱法,此法既准确,又灵敏。被选作稀释剂的同位素,大部分是浓缩度高的同位素(一般大于90％)。通过质谱测定稀释剂浓度、未加稀释剂样品和加了稀释剂的混合     

天然钐和浓缩钐同位素丰度比质谱测定

裂变产物~(149)Sm热中子吸收截面大,是反应堆中妨碍提高反应性的可燃毒物。用MATCH5质谱计,测定了天然氧化钐和浓缩钐同位素丰度比和百分原子浓度,~(149)Sm同位素丰度比测定精度在0.4％左右,为同位素稀释质谱法准确测定~(149)Sm绝对浓度奠定了基础。     

秦山核电站考验元件燃耗的辐照史校正计算

通过实验测得反应堆停堆时刻裂变产物~(137)CS、~(148)Nd等监测体的浓度值,进而推算出辐照燃料元件的燃耗值是通常采用的方法。它需要若干参数,如裂变产物的平均裂变产额,反应(n,γ)的修正量,放射性裂变产物的堆内衰变修正量,可裂变核素的平均裂变能量等。这些参数都同燃料的辐照历史紧密关联。本文概述了上述参数的计算方法并给出了计算结果。方法的主要特点是:1.以考验元件的实际参数为输入数据;2.根据反应堆实际运行史反复循环模拟计算;3.除计算重核素及所要求的裂变产物的原子浓度和放射性外,仔细计算了~(137)Cs和~(148)Nd等核素(n—1)衰变链中子俘获反应的修正量。     

同位素稀释质谱法测定动力堆卸料元件中裂变产物~(149)Sm的含量

同位素稀释质谱法测定裂变产物钐的绝对量时,国外通常用浓缩钐作为稀释剂。本报告介绍了以高纯的天然钐作稀释剂,用 MAT CH_5 质谱计测定了动力堆卸料元件中裂变产物~(149)Sm 的含量,并把它换算成每克铀燃料溶液中累积裂变产额~(149)Sm 绝对量,与理论计算符合。相对标准偏差为±1.6%(置信度95%),本报告对稀释剂选择,污染等问题作了认真的探讨。为评价物理计算提供了实验数据。     

~(235)U的有效“俘获/裂变”截面比(α_5)和堆元件燃耗[Bu(%)]的一种计算方法

一、引言~(235)U的有效“俘获/裂变”截面比(α_5)对测定反应堆元件的燃耗B_u(%)、研究反应堆的特性和运行状况都是很重要的参数。在一定燃耗深度但仍属浅燃耗范围内,α_5值变化较小,还可以通过测定反应堆元件辐照前和辐照后~(235)U和~(236)U的含量来确定它的数值,常采用的α_5值     

Zr-2包壳管爆破力学性能

核燃料元件是反应堆的核心部件，由燃料芯块、包壳及其构件组成。由于燃料元件的运行环境比较恶劣，中子辐照、冷却剂的腐蚀及在开堆、停堆、和运行后期燃料芯块与包壳的机械相互作用和裂变气体产物的释放，使包壳管承受双向应力，均会造成燃料元件的力学性能下降，形成安全隐患，它的安全性能直接影响反应堆的安全可靠性。为更好地模拟包壳在堆内的受力状态，一般采用内压爆破试验来获得包壳材料的断裂强度与延性数据。     

核燃料组件高能X射线无损探测技术研究

正燃料组件是反应堆堆芯的关键部件,其性能质量直接关系到反应堆的安全性、经济性和先进性,核燃料组件在反应堆运行期间会在裂变产物、高温、中子辐照等因素的综合作用下发生开裂、肿胀,严重的情况下会出现破碎,这些将对反应堆的安全运行造成威胁,因此对核燃料组件的定期检测尤为重要。辐照后核燃料组件存在很强的放射性,对其进行检测存在一定的技术难度,通过国外的经验及相关研究,利用高能X射线直线加速器射线源进行核燃料组件的无损探测是一种有效的检测手段。中国原子能科学研究院"十二五"期间在核能     

反应堆事故引起的急性皮肤辐射损伤及应急处理

一、前言核燃料铀放入反应堆工作后,在生产新的核燃料钚-239的同时,还有许多放射性很强的裂变产物如碘、锆、铌、锶等,通常一吨铀棒的放射性可达100多万居里。反应堆在正常运行时,人的肢体皮肤不会受到照射。但在检修反应堆及反应堆事故发生时,尤其是核燃料元件的烧结事故,由于元件破裂,裂变产物以气溶胶方式污染现场空气,或者因裂变产物的碎片,污染一回路水等而沾染皮肤,造成局部皮肤直接照射。当剂量达到一定水平时。即可引起程度不同的急性皮肤辐射损伤。总之,经反应堆照射过的任     

契连柯夫计数器的新应用

日本采用契连柯夫计数器来探测释热元件的破裂情况。从反应堆活性区取出的水样利用契连柯夫辐射进行分析,这种辐射是由短寿命裂变碎片放出的高能β粒子通过水中时放出的。同目前所采用的γ能谱仪或缓发中子探测器比较起采,契连柯夫计算器更能保证分析的速度和灵敏度。泽见和山田(东京中央研究实验室)对释热元件破裂所时行的一些实验的结果表明,当水中裂变产物的浓度低于600微微居里/厘米~3时,信号计数同本底计数之比可达到10:1.对一般的反应堆系统来说,这一浓度相当于1厘米~2的核燃料表面的放射性。应用契连柯夫计数器的最大优点是:在含有衰变的裂变产物的水样中,光信号本身加强。计数管     

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.     

The preclinical pharmacological study of dopamine transporter imaging agent 18F-FP-β-CIT

The paper is to study pharmacologic characteristics of 18F-FP-β-CIT (18F-N-(3-fluoropropyl)-2β- carbomethoxy-3β- (4-iodophenyl)nortropane) as an imaging agent for dopamine transporter. The radiochemical purity of 18F-FP-β-CIT in aqueous solution was over 95% after standing at room temperature for 4h. Biodistribution displayed rapid uptake in rat brain (1.375 %ID/organ at 5min and 0.100 %ID/organ at 180 min) and the striatal uptake was 1.444,0.731, 0.397, 0.230 and 0.146 %ID/g at 5, 30, 60, 120 and 180 min, respectively. The values of striatum/cerebellum,striatum/frontal cortex and striatum / hippocampus in rat's brain at 30 min were 3.38, 2.17 and 2.40 respectively. The uptake in striatum can be blocked by β-CFT, suggesting that 18F-FP-β-CIT binds to DAT peculiarly. The compound was rapidly cleared from monkey's blood. The striatal uptake was bilaterally decreased in the left-sided lesioned PD rats, compared with normal control. Brain PET imaging studies in normal monkey showed that 18F-FP-β-CIT was concentrated in striatum. The test of undue toxicity showed that the dose received by mice was 1250 times as by human, which indicates that 18F-FP-β-CIT is very safe. So 18F-FP-β-CIT is a promising PET imaging agent for DAT with safety and validity.     

PLASMA SCIENCE AND TECHNOLOGY AUTHOR INDEX TO VOLUME 16(2014)

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Radioactivity levels in soil of salt field area,Kelambakkam,Tamilnadu,India

Soil samples in and around salt field area have been analyzed for natural radioactivity concentration using gamma ray spectrometer.The activity concentration for ~(232)Th,~(238)U and ~(40)K are ranged from 27.88 to 45.27 Bq/kg, from BDL to 13.30 Bq/kg,and from 135.54 to 381.28 Bq/kg,respectively.The measured activity concentrations for these radionuclides were compared with world average activity of soil.The average activity concentration of ~(232)Th in the present study is 1.19 times higher than world median value while the activity of ~(238)U and ~(40)K is found to be lower. The absorbed dose rates due to these radionuclides were calculated.The average absorbed gamma dose rate due to the presence of ~(232)Th,~(238)U and ~(40)K in soil samples is 36.99 nGy·h~(-1).These results indicate no radiological anomaly. The data presented in this study will serve as a base line survey for primordial radionuclides concentration in the study area.     

Non-FDG PET imaging of brain tumors

Due to relatively high uptake of glucose in the brain cortex, the use of FDG PET imaging is greatly limited in brain tumor imaging, especially for low-grade gliomas and some metastatic tumours. More and more tracers with higher specificity were developed lately for brain tumor imaging. There are 3 main types of non-FDG PET tracers： amino acid tracers, choline tracers and nucleic acid tracers. These tracers are now widely applied in many aspects of brain tumor imaging. This article summarized the general use of non-FDG PET in different aspects of brain tumor imaging.     

基于NPL-NMC系统的γ测量子系统的建模与优化

在军控核查中,核部件的质量、丰度、年龄属性需采用无损方法进行核查,NPL-NMC系统是一套利用中子多重性测量核部件质量属性的装置,为建立完善的属性测量系统,还需在NPL-NMC系统的基础上建立γ测量子系统。本文通过设计γ测量子系统在NPL-NMC系统上的布局及对中子屏蔽的优化,使系统能对铀部件的丰度、年龄属性进行测量。模拟计算结果表明,该γ测量子系统能很好地满足军控核查对铀部件丰度、年龄属性测量的要求。     

Improvement of carbon fiber surface properties using electron beam irradiation

Carbon fiber-reinforced advance composites have been used for structural applications,mainly on account of their mechanical properties.The main factor for a good mechanical performance of carbon fiber-reinforced com- posite is the interfacial interaction between its components,which are carbon fiber and polymeric matrix.The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite.EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests.Experimental results showed that EB irradiation improved the ten- sile strength of carbon fiber samples.The maximum value in tensile strength was reached using doses of about 250 kGy.After breakage,the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated car- bon fibers were evaluated.SEM micrographs showed modifications on the carbon fiber surface.     

Measurement system for SSRF pulsed magnets

This paper describes the magnetic field measurement system for pulsed magnets in SSRF.The system consists of magnetic probes,analog active integrator,oscilloscope,stepper motor and a controller.An application pro- gram based on LabVIEW has been developed as main control unit.After the magnetic field mapping of a septum magnet prototype,it is verified that the test results accord with the results of theoretical calculation and computer simulation.     

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。     

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。