核临界安全计算的一个新方法:单中子蒙特卡罗方法

应用蒙特卡罗方法计算K_(eff)通常情况下,需要首先计算给出裂变中子源分布,然后再根据裂变中子源分布计算给出K_(eff)。作为蒙特卡罗方法计算K_(eff)的主要困难,在于计算给出裂变中子源分布。正是由于这一原因,进入七十年代前后,人们开始把注意力集中到了所谓最优源对策问题的研究上。本文给出了一种计算K_(eff)的新的方法——单中子蒙特卡罗方法,改变了过去用蒙特卡罗方法计算K_(eff)时必须首先计算给出裂变中子源分布,然后再计算给出K_(eff)的分为两步的传统方法,而变成只有一步,即直接计算给出K_(eff)。证明了单中子蒙特卡罗估计为渐近无偏估计,概率收敛于K_(eff),并且给出了方差的近似计算公式。通过具体计算的例子表明,单中子蒙特卡罗估计可以很快地收敛于K_(eff),至少节省了通常蒙特卡罗方法计算K_(eff)时所需要的计算给出裂变中子源分布的计算机的全部时间。     

二维自适应数值网格的构造方法及其实现

讨论了一种二维自适应网格的构造方法,并具体地给出了它的实施过程。指出当控制函数连续给出时,方法是有效和便于实现的,给出了一些区域的网格构造图:实际计算中自适应网格控制量的数值解一般是离散给出的,这时为了形成连续的控制函数,需要对离     

高速旋转氚钛靶系统设计和靶温度的数值模拟

给出了用于强流中子发生器的高速旋转氚钛靶系统的设计方案,并对靶的温度变化进行了数值模拟,给出了强流中子发生器的运行参数。     

HL-1托卡马克数据获取系统及其在物理实验中的初步应用

给出了HL-1托卡马克数据获取系统的硬件配置情况及其在物理实验中的应用,并给出了系统采集及处理的典型数据图形。     

计算维修不独立马尔可夫系统瞬态不可用度的六种蒙特卡罗方法

在马尔可夫可维修系统状态转移积分模型的基础上 ,给出了维修不独立马尔可夫系统瞬态不可用度的六种估计量 ,结合状态转移时间偏倚抽样技术 ,给出了计算维修不独立马尔可夫系统瞬态不可用度的六种蒙特卡罗方法。用两个实际算例考察了各种计算方法的效率随系统运行时间的变化。给出了各种算法适用范围的结论。     

中子反照效应实验理论设计

为深化中子反照效应的认识,获得宏观测量数据,本文开展了中子反照效应实验的理论设计,给出了反照效应分析的理论公式。采用两组不同的实验状态分别给出了直照能谱和反照能谱下两种核素反应率的测量结果,再通过某测点这两种核素反应率的测量实现反照影响的定量分析。分析认为,给出的理论公式和实验布局方案是有效的,获得实验测量数据后可给出中子反照效应的定量信息。     

质子剂量的解析计算

计算了质子束垂直入射于水中的剂量分布,首先给出宽束入射时的剂量深度曲线。然后以－高斯函数描述多重散射作用,得到了三维剂量分布的积分公式。最后给出了入射粒子束为均匀圆柱时剂量分布离轴比的级数表达式。结果表明,给出的部分计算结果与ＰＴＲＡＮ的结果和实验结果符合较好。     

铀溶液核临界安全实验装置首次物理启动

介绍了用于核临界安全问题研究的铀溶液实验装置,给出了在活性区全水反射层情况下首次物理启动时的核燃料装料步骤。用外推法、内插法、功率稳定法实验测定的硝酸铀酰溶液的临界体积为20479.62mL,从而给出235U的临界质量为1579.184g。最后给出控制棒价值的实验刻度等。     

高精度正电子谱仪脉冲调制系统设计

中国科学技术大学的核固体物理实验室设计了一套正电子谱仪装置,此装置要求其脉冲调制系统能够给出一路边沿小于2ns、宽度约7ns、幅度大于5V的50MHz脉冲信号和两路频率分别为50MHz、200MHz的正弦信号.本文给出了为此装置设计的高精度脉冲调制系统,并给出了该系统各项指标的测试结果.     

Woods-Saxon位壳模型的二阶常微分方程数值解的迭代法

本工作给出了一种求Woods-Saxon位壳模型的二阶常微分方程数值解的迭代方法,并对其差分方程和边界条件进行了讨论,并以~(16)O为例给出了计算结果。     

Containment vessel design and practice

This paper attempts to review the state of the art of methods of analysis and design of the concrete containment vessels required for BWR and PWR. A step-by-step critical appraisal of the existing work is given. Elastic, inelastic and cracking conditions under extreme loads are fully discussed. Problems associated with these structures are highlighted. A three-dimensional finite element analysis given by the author is included to cater for service, overload and dynamic cracking of such structures. Missile impact and seismic effects are included in this work. The second analysis is known as the limit state analysis, which is given to design such vessels for any kind of load.Two existing vessels in reinforced and pre-stressed concrete are examined. Substantial calculations are given in order to assess their behaviour. Both these original analyses were developed by the author and are given in the appendices. They have been fully tested on four other vesels and two models. Due to limitations of space, some of these details could not be revealed. A brief explanation is given regarding the computer programs supporting the above analysis.     

热中子俘获瞬发γ射线强度计算

简要介绍了热中子俘获发γ射线强度的计算方法,并以实例进行说明,还给出了有关物理自洽检验的方法及其讨论。     

Annals of the ICRP. A report of: doses to infants from ingestion of radionuclides in mothers' milk

In the present report, ICRP provides information on radiation doses to the infant due to intakes of radionuclides in maternal milk. As in Publication 88 (ICRP, 2001) on doses to the embryo and fetus following intakes of radionuclides by the mother, intakes by female members of the public and female workers are addressed. Acute and chronic intakes are considered at various times before and during pregnancy as well as during the period of breastfeeding. Dose coefficients per unit intake by the mother (Sv/Bq) are given for the selected radionuclides of the same 31 elements for which age-specific biokinetic models were given in Publications 56, 67, 69, and 71 (ICRP, 1989, 1993, 1995a,b). For these elements, doses were calculated for the most radiologically significant natural or artificial radionuclides that might be released into the environment due to various human activities. Dose coefficients are also given in this report for radionuclides of an additional four elements: sodium, magnesium,phosphorus, and potassium. Relevant human and animal data on elemental and radionuclide transfer to milk are reviewed. The biokinetic models for adults given in earlier ICRP publications are adapted to include transfer to milk. Model predictions of fractional transfer of ingested or inhaled activity to milk are discussed in the report, and the corresponding dose coefficients for the infant are compared with dose coefficients for in utero exposure, as given in Publication 88 (ICRP, 2001). Illustrative information is also given on doses to the female breast from radionuclides in breastmilk, and external doses received by the child from radionuclides retained in the tissues of the mother. For the additional elements considered in this report, but not in Publication 88 (ICRP,2001), information is also given on doses to the embryo and fetus following maternal intakes of radioisotopes during or before pregnancy. A CD-ROM is to be issued giving data that will supplement the information given in this report. In addition to the dose coefficients given here, committed equivalent doses to the various organs and tissues of the offspring will be given. Dose coefficients will also be given for inhalation of a range of aerosol sizes for the selected radionuclides of the elements covered by this report.     

α衰变的γ射线强度计算

根据α衰变的α强度和γ跃迁强度平衡,导出了α衰变的γ射线强度的计算公式,并以实例进行说明,并给出了有关强度平衡的物理自洽检验方法及其讨论。     

Target-thickness-angular-spread tables for proton and pion beams

When passing through materials, a parallel beam of charged particles is given an angular divergence by multiple Coulomb scattering processes. Convenient measures of the spreading of the scattered beam are given by the standard-deviation angle, the full-width-half-maximum angle, and the full-width-tenth-maximum angle. These tables present the thicknesses of materials that produce these three angular spreadings in the range 5 to 60 mrad. Values are given for protons with energies between 200 and 850 MeV and for pions with energies between 50 and 700 MeV. Steps of 50 MeV are employed in both cases. The target materials are He, C, Al, Ar, Ca, Fe, Zn, Ge, Kr, Zr, Ag, Cs, Hf, Au, and Pb. The tabulated values were computed from Molière theory with constants chosen to fit experimental data. Suggestions for interpolation in Z, A, particle energy, and angle are given.     

流动欠热沸腾通道内净蒸汽产生起始点的确定

给出了在低压条件下 ,竖直的环形通道内 ,流动欠热沸腾过程中净蒸汽产生起始点的实验结果。讨论了净蒸汽产生起始点的特征及用γ射线衰减法测量净蒸汽产生起始点时应注意的问题。实验数据与有关模型进行了比较 ,实验数据与计算模型符合较好     

5MW THR热工水力设计

本文介绍了5MW THR 热工水力设计准则、设计方法及特点,给出了压水及压水微沸腾两种运行方式下的主参数。     

Use of cadmium sulfide photocells in measuring ionizing radiations

The need for new methods of measuring ionizing radiation is very great. The use of crystalline counters in the field of dosimetry is particularly interesting. The present paper deals with the use of cadmium sulfide photocells as counters in dosimetric devices; these have considerably higher sensitivity to various types of radiation than have air ionizatlon chambers. Due to its high sensitivity, finely crystalline CdS can be used successfully in solving a series of dosimetric problems. A resume is given here of the work of both, Soviet and foreign authors on this subject. Methods of obtaining mono- and polycrystalline CdS are briefly described and their dosimetric, time and temperature properties are given. Certain defects of CdS counters are also listed and possible means of eliminating them are presented. Diagrams of CdS dosimeters are also given.     

The Space Radiation Environment

The particle space radiation environment is reviewed and some of the latest models for the various phenomena are presented. The properties of the solar wind and interplanetary magnetic fields based on recent satellite measurements are given and solar proton events are discussed. The magnetospheric cavity and the character of the boundary between it and the solar wind based on Imp 1 results are shown. Flux maps and energy spectra for the inner and outer radiation zones are given and examples of temporal variations are shown.