水体放射性在线监测系统校准装置设计

水体放射性在线监测系统在长时间不间断地工作中，由于探测器和各种电子元件温度变化、元器件老化等原因会造成谱线漂移、谱线展宽和峰位变化，导致谱线解析困难和解析结果误差变大。针对基于溴化铈探测器的水体放射性在线监测系统，研制了一种在线校准谱线漂移的附加装置，该装置由¹³⁷Cs(豁免源)、铅挡块、校准孔、直线电机和铅屏蔽层组成。校准孔最佳的开孔半径和铅挡块最佳厚度通过蒙特卡罗模拟得到，分别为2.2 cm和5 cm；使用标准豁免级¹³⁷Cs源作为标准参考峰，通过软件对¹³⁷Cs全能峰峰位漂移及峰面积进行分析，计算增益，实时调节参数等完成峰位及峰面积的校准。最后用该装置进行现场应用验证，结果表明该装置能够把系统测量谱线的峰位变化控制在了±1%以内，峰面积变化控制在±5%以内。     

新型稳峰双能量γ射线双道分析器

本文介绍一种新型的用于闪烁计数器的具有自动稳峰功能的双能量分析器，它明显地改善了峰位的漂移。分析器的结构为双宽度ＮＩＭ插件，它将线性放大器、双道能量分析器和基于一种新方法的能根据峰位漂移量自动调整光电倍增管偏压的高压电源构成一个整体，结构紧凑。     

13N监测仪的稳谱技术研究

本文论述了13N监测仪中的谱漂移和稳谱问题,给出了实验测量方法及测量原理框图,并对谱仪系统的能量与温度的非线性关系进行了测量;采用非线性方法稳谱,温度在10-45℃范围内变化时,511keVγ光子的峰位道址漂移小于±1道.     

质量控制谱法校正惰性气体氙β-γ符合谱能量漂移

针对CTBT放射性核素台站惰性气体氙β -γ符合谱能量漂移问题,提出了一种基于质量控制(QC)谱的谱能量漂移校正方法,利用质量控制谱中的γ能谱和二维β -γ符合谱分别对γ探测器和β探测器的能量漂移进行校正,确定氙样品二维β -γ符合谱中四种放射性氙同位素(131mXe,133mXe,133Xe和135Xe)的符合能量区域,实现了放射性氙同位素活度浓度的准确定量分析。     

峰位微扰动修正在构建高斯响应矩阵中的应用研究

现有的高斯响应矩阵在对高分辨率γ能谱进行重建时,极易出现假峰、峰位漂移等问题。本文针对测量条件（温/湿度、电压波动等）微弱变化引起峰位扰动进而影响高斯响应矩阵重建结果准确度的问题,通过引入微扰动修正因子,对现有高斯响应矩阵进行修正。采用IAEA重峰分解测试谱及GMX40P高纯锗探测器实测能谱对修正前后的高斯响应矩阵进行谱线解析测试。结果表明：通过修正后响应矩阵重建的能谱,其峰位与实际峰位保持一致,净峰面积的相对偏差分别低于1025%和550%。     

嫦娥二号γ谱的非线性谱漂校正

针对嫦娥二号γ谱的非线性谱漂特点,提出了一种基于能量对应的谱漂校正方法。选取了嫦娥二号γ谱线作为研究对象,进行谱漂校正实验。结果显示:该方法能够有效校正嫦娥二号γ谱的非线性漂移,使Fe峰和Mg/K峰的峰位漂移范围控制在±1道范围内。     

大尺寸BGO晶体的温度特性研究

锦屏深地核天体物理（JUNA）实验项目将在中国锦屏深地实验室开展恒星平稳氦燃烧阶段关键的(α,γ)和(α,n)反应以及恒星平稳氢燃烧阶段关键的(p,γ)和(p,α)反应的直接测量。该项目计划研制一套锗酸铋（BGO）探测器阵列用于(α,γ)和(p,γ)反应的γ射线探测。由于BGO晶体的光产额对温度敏感,温度的变化会导致γ能谱峰位的漂移和能量分辨率的变化。本文使用制冷系统对尺寸为6 cm×8 cm×25 cm的BGO晶体进行降温,利用¹³⁷Cs源测量了其γ能谱峰位和能量分辨率,对BGO探测器性能随温度的变化关系进行了研究。结果表明：在-20～22.1 ℃温度区间内,BGO探测器的γ能谱峰位与温度呈良好的线性关系,能量分辨率随温度的降低而提高。     

CTBT气溶胶γ能谱的能量漂移校正方法

CTBT放射性核素台站气溶胶样品通常采用HPGe γ谱仪系统测量,能量刻度是核素识别的关键。针对放射性核素台站气溶胶γ能谱存在的能量漂移问题,提出了一种基于²¹²Pb、²¹²Bi、²⁰⁸Tl、²¹⁰Pb、⁴⁰K和⁷Be等天然放射性核素γ射线的能量漂移校正方法。测试结果表明,该能量漂移校正方法能有效校正能谱中γ峰能量偏差。     

模块化神经网络数据融合在谱线核测量中的应用

针对谱峰随不同干扰量漂移的问题,尝试使用模块化神经网络的信息融合对谱仪谱峰随温度、电压等干扰漂移进行致据融合.对谱仪峰位漂移,建立了融合的网络模型、算法及其学习方式.最后在建立的数学模型上对谱漂移试验数据进行计算和仿真.实验结果表明建立的数学模型有较好的精度,基于模块化神经网络的融合技术能运用在谱仪的谱峰漂移的数据融合中.     

海水就地γ谱仪能谱温漂修正研究

介绍了基于NaI(Tl)探测器的海水就地γ谱仪测量能谱的温漂修正方法。该方法改进了POE的温度补偿装置,通过设计实验探索了γ谱仪测量能谱随温度变化的函数关系,同时利用曲线拟合方法得到的修正函数对测量能谱进行修正。实验结果表明:γ谱仪测量能谱的峰位偏移与温度变化有一定的对应关系,通过60Co和152Eu的能谱修正实验验证了修正函数的有效性。此方法为海水放射性核素识别及核素活度的准确测量提供了参考。     

中国先进研究堆中子残余应力谱仪校准

为校准中国先进研究堆（CARR）中子残余应力谱仪,获得一维位置灵敏探测器（PSD）的灵敏度系数、位置坐标与衍射角的几何关系及零点等参数,设计了校准实验和软件,并将获得的校准参数用于标准Fe粉前4个衍射峰的数据预处理,校正衍射峰位与计算衍射角的差值符合残余应力谱仪的误差要求。结果表明,该工作能准确获得校准参数,并可用于CARR中子残余应力谱仪的数据预处理。     

The effect of damage rate on void growth in metals

The rate theory formulation of void growth was utilized to analyze the effects of damage rate on metal swelling. In particular, the swelling behavior of 316 SS was modeled as a function of temperature, over a range of displacement damage rates between 10^?6dpa/s and 10^?3dpa/s. Detailed analysis of the rate processes for point defect annihilation, migration, and loss to sinks indicated that small vacancy loops limit void growth at high damage rates. The reduction of void growth rates by vacancy emission from voids was found to be shifted towards higher temperature at higher displacement rates. In effect, the peak swelling temperature as well as the upper cutoff temperature for swelling are increased as the displacement rate is increased. The influence of constant or rate dependent nucleation conditions on the final swelling was investigated and it was shown that the initial microstructure before the growth stage essentially determines the peak swelling temperature. When appropriate empirical expressions for void and loop densities were used, the final peak swelling temperature shift agrees reasonably well with experimental data.     

Recombination Centers in Gamma-Irradiated Arsenic-Doped Germanium

A comprehensive investigation has been performed of the properties of recombination centers introduced in As-doped Ge by Co60 gamma rays. Materials of three resistivities were used: ~0.2, ~1 and ~8 ?-cm. Measurements of lifetime versus temperature were made at low excess densities following various anneals. Numerous measurements of lifetime as a function of excess density with temperature as a parameter and with different annealing histories were performed. The position of the recombination center was observed to shift slightly with anneal temperature from Ev + 0. 346 ±.005 eV for room temperature stable defects to 0. 322 ±0.003 eV for samples which have been annealed in the range of ~70°C to ~120°C. These values are based on excess density measurements and assume unity statistical weight. The possible error from this assumption is estimated to be ±0.02 eV. The variation of electron capture probability with temperature was indicated by comparison with temperature dependence data; it varies approximately as T3/4. The hole-to-electron capture probability ratio near room temperature is 400 ±30 %. The arsenic atom appears to play no significant role in the process of recombination center creation or annihilation.     

In-Line Uranium Monitoring in Reprocessing Waste Solution by Time-Resolved Laser-Induced Fluorometry

In-line monitoring by fluorometry of uranium concentration in reprocessing waste solution has been realized. The reduction of U0₂ ²⁺ fluorescence by coexisting ions and solution temperature can be corrected by measuring fluorescence lifetime, absorbance of excitation beam wavelength and absorbance of fluorescence wavelength. The method applicability was examined by using a sample solution simulating the waste solution of the codecontamination process. When the coexisting ion concentrations were increased in the sample solution which included 50 mg//of uranium, the corrected value of the uranium concentration was constant in the range of 0~1.5 times the coexisting ion concentrations. When the temperature was changed in the range of 30~45°C, the corrected value was also constant. The precision of the correcting method was ±15%'. These results verified that the correcting method could be applied to in-line monitoring of uranium concentration even though species and amounts of the coexisting ions and solution temperature were changed in the waste solution.     

二苯并-18冠-6的热中子散射谱和红外光谱

一、引言冠醚是一种良好的吸附剂,它能有选择地吸附某种物质,起到有效地浓缩的作用、例如吸附自然界中丰度极低的~(235)U或~6Li等。它的静态结构已用X衍射和中子衍射技术研究过,而它的动态结构尚待作进一步的研究。十多年来,使用红外吸收光谱和喇曼散射光谱来研究大环多醚类化合物的动态结构与性能间联系等工作已取得了不少结果,然而由于光谱受光学选择定则的限制,不能真实地反映它的本来面貌,使用中子散射技术能较好地反映它的本质。到目前为止,国外关于中子散射方面的工作报导寥寥无几。本文主要介     

用金活化法测定加速器中子源中子注量及MCNP4C修正

在四川大学720所2.5MeV静电质子加速器上,由核反应7Li(p,n)7Be,T(p,n)3He产生中子,对中国工程物理研究院研制的新型中子探测器进行效率刻度实验中,需要知道探测器位置处的中子绝对注量,为此我们测量了0.165、0.352、0.576、1.400MeV四个能点的中子注量。测量方法采用的是金活化法,在实验测量中,由靶头材料、冷却水层和样品的包层材料等引起的多次散射效应及中子在样品中的自屏蔽效应等均对实验结果产生影响。这些因素在实验中不可避免,也难以通过实验方法扣除,因此用Monte Carlo程序MCNP4C对上述效应进行了修正计算。     

压力和温度对静力水准系统精度影响分析

静力水准系统(Hydrostatic leveling system,HLS)的工作介质是液体.由于纯净水的诸多优点,在本系统中采用水作为工作介质.液体的特性是极易受到外界的影响而改变它的物理形态.在HLS系统中,压力、温度等因素对系统的测量有着非常大的影响.本文分别分析了压力和温度对静力水准系统测量精度的影响.为了消除压力的影响,在系统设计的时候采用了密封钵体和钵体之间用等压气管连接的办法,保证系统在工作时每个钵体中的工作液体表面上的大气压是一致的.温度的影响包括水管中温度梯度的影响和钵体之间温度差异的影响.通过分析,对于水管中温度梯度的影响,只要在安装系统时保证水管的垂直高差足够小,就可以忽略;而对于钵体之间的温度差异的影响,在每个钵体传感器中都安装了温度传感器,实时地测量钵体的温度,并和CCD测量数据同时采集,通过理论计算得到温度修正公式,对每个钵体中的CCD读数进行温度修正.通过实验数据分析,可以把温度的影响修正到允许的误差范围以内.     

单盒钠冷快堆燃料组件堵流事故的CFD分析

钠冷快堆大都采用金属绕丝来固定燃料组件,细长狭窄的流道容易积聚腐蚀沉积物,可能会引起钠的局部沸腾和包壳的传热恶化。本文利用商用计算流体动力学软件STAR-CCM+程序对中国实验快堆单盒燃料组件的堵流事故进行了数值模拟,分析了包壳内壁面温度与冷却剂在堵块附近的轴向流场分布,并与正常工况下的计算结果进行对比。计算结果表明：实心介质堵流危害比多孔介质更为严重;实心介质堵流事故的包壳峰值温度局部最高点始终位于堵块中心位置,而多孔介质堵流事故的位于堵块后方,且随堵块面积的增大而往下游偏移;堵块的孔隙率对包壳在堵块下游的最大温升有明显影响,随堵块孔隙率的增大而减小。     

Thermal annealing as a method to predict results of high temperature irradiation embrittlement

In order to assess the validity of post-irradiation annealing as a method to predict results of high temperature irradiation a new analysis of experimental data has been performed revealing the combined influence of annealing temperature and impurities content on residual embrittlement after annealing. For 2CrMoV (WWER-440 reactor pressure vessel) steel with low contents of copper and phosphorus, the comparison of two embrittlement dependencies has been done: on irradiation temperature and post-irradiation annealing temperature. It is demonstrated that data for both the transition temperature shift after irradiation, ΔT_k, and the residual transition temperature shift after post-irradiation annealing, ΔT_res, fall within the same scatter band. A similarly close correlation is observed by comparison of yield strength increases after irradiation and after post-irradiation annealing.     

Radiation-Induced Laser Action in CdSe

Laser emission of CdSe excited by Ga(AsP) laser diode has been studied near liquid helium temperature both before and after irradiation with fast neutrons. Irradiation introduces new laser peaks at ~6895?, ~690?, and ~6924?, which are situated at longer wavelengths as compared to the peaks observed before irradiation. The laser peak at ~6905? can be associated with the strong spontaneous emission that is observed at the same wavelength after irradiation. These results are interpreted in terms of the recombination of excitons bound to the defects introduced by irradiation.