惰性气体核素127Xe制备实验研究

在军控核查研究气体在环境中的沉积、扩散等的项目中，为寻找1种气体核素示踪方法，本工作对放射性气体核素¹²⁷Xe的制备方法进行研究。在反应堆中对盛装在玻璃管中的普通氙辐照96h，经一定时间冷却后，将辐照产物吸附到处于液氮温度下的特制源盒中，20min后，待Xe气体在源盒中达到均匀分布再进行γ能谱测量，以获得¹²⁷Xe的准确活度值。实验结果证实，应用上述方法制备放射性气体示踪核素¹²⁷Xe是可行的。     

从混合裂变产物中放化分离132I

依据混合裂变产物中碘及其母体碲的同位素的半衰期设计分离¹³²I的流程。该流程的主要步骤为浓HBr蒸发和CCl₄萃取。实验研究了浓HBr蒸发对碘的去污效果；在硝酸介质中，用含I₂的CCl₄作为萃取剂，研究了HNO₃浓度、水相中KI含量和有机相CCl₄中I₂含量对¹³²I萃取率的影响，测定了含SO₂水溶液对¹³²I的反萃率。用设计的推荐流程获得了放化纯的¹³²I，其中含有的¹³¹I的活度为¹³²I的1.3％，分离流程全程对¹³²I的化学回收率约为60％，流程对主要γ核素的去污因子大于10³。     

内充气正比计数管系统绝对测量87Kr放射性活度浓度

本工作研制建立1套气体放射性活度绝对测量装置——内充气正比计数管系统。对该系统的坪特性、本底、死时间、端效应和壁效应等性能进行了测试。在此基础上，采用该系统对放射性气体⁸⁷Kr的放射性活度浓度进行了绝对测量，测得值为40.64（1±0.9％）Bq/mL。     

气体裂变产物87Kr半衰期测定

⁸⁷Kr是核燃料裂变燃耗测定中重要的气体裂变产物。为准确测定核燃料的裂变燃耗，要求⁸⁷Kr半衰期具有很高的准确度。本工作用单个HPGe探测器连续跟踪和双HPGe探测器位置接续法测定⁸⁷Kr的半衰期。⁸⁷Kr半衰期的测定结果为（76.33±0.07）min。     

HPGe测量气体裂变产物中微量77Kr的可行性分析

针对气体裂变产物中微量⁷⁷Kr的测量问题,利用MCNP模拟计算了气体裂变产物对⁷⁷Kr的影响。结果表明,HPGe不可能直接测量气体样品中的⁷⁷Kr,但可通过测量其子体⁷⁷Br来推算⁷⁷Kr。     

戈壁汇水区测年与沉积速率研究

运用¹³⁷Cs法和²¹⁰Pb法对核试验场区汇水区沉积物的沉积速率进行估算，对沉积物的蓄积峰进行年代判定。用分衰减段方法计算²¹⁰Pb分布异常情况下沉积物的沉积速率，得到的沉积速率与¹³⁷Cs法获得的沉积速率基本符合。结合应用¹³⁷Cs法和²¹⁰Pb法，可得到汇水区的沉积速率和沉积层的年代。     

通排风系统中239PuO2气溶胶微粒的流动特性

运用计算流体动力学(CFD)方法模拟研究了事故状态下有人员工作时,²³⁹PuO₂微粒在不同工况下的流动特性及其粒子轨迹。结果表明：工作间关门,有利于放射性气溶胶微粒及时从排风口排出。研究结果对工作人员在事故条件下规避放射性气溶胶的危害提供了重要的参考。     

反符合法测量152Eu放射性溶液的活度

¹⁵²Eu的衰变纲图复杂,包括72.1%的EC衰变和27.9%的β-衰变,衰变子体退激过程中又放出140多条γ射线,其中,12条能量处在122~1408keV之间,是主要γ射线。¹⁵²Eu常用于HPGeγ谱仪能量校准和效率校准等,¹⁵²Eu的放射性活度准确测量极为重要。本工作利用4πβ(PPC)-γ(HPGe)反符合测量装置对¹⁵²Eu的活度进行绝对测量,并与4πβ-4πγ符合效率外推法和HPGeγ谱仪、4πγ高气压电离室测量的结果进行了比较。这几种方法的测量结果在不确定度范围内一致。     

肺支气管中239PuO2微粒沉积分布数值模拟

为研究核事故条件下钚材料对人体产生的危害，用计算流体动力学模拟计算²³⁹PuO₂微粒在人体支气管中的沉积率和沉积位置。结果表明：所吸入的²³⁹PuO₂微粒主要沉积在肺气管一、二级分叉处。研究结果可对事故状态下²³⁹PuO₂微粒的防护和人体活体肺中铀、钚等核素沉积量的测量提供参考。     

133Xe活度浓度的绝对测量

惰性气体氙监测是全面禁止核试验条约（CTBT）国际监测系统（IMS）的关注重点,其中,放射性氙同位素的活度浓度主要采用HPGeγ能谱法和β-γ符合法测量,如何准确刻度系统的探测效率是放射性氙测量的难点。本工作介绍了一种采用内充气正比计数管长度补偿绝对测量放射性氙活度的原理和方法,对¹³³Xe活度浓度进行了绝对测量,其活度浓度测量结果为21.36×（1±1.5%）Bq/mL。     

星载核爆X射线探测技术进展

卫星有效载荷对核爆炸的探测是实现国土及全球核爆监测的最佳手段，核爆传感器也可为空间科学研究积累数据。而星载X射线探测的途径，可较理想地实现对近地太空核爆的探测、识别、定位与确定核爆炸的当量。主要介绍利用X射线探测太空核爆在国外的发展历史及现状，并且预测了今后的发展趋势。     

Diffusion and Evaporation of Fission Products in Coated Fuel Particles

Fractional releases of ¹³³Xe, ¹⁴⁰Ba and ⁸⁹Sr from slightly-irradiated pyrolytic-carbon-coated and SiC-coated particles were measured over a temperature range of 1,200°–1,750°C. The results are analyzed mathematically in order to obtain the diffusion and evaporation coefficients relevant to PyC and SiC. The resulting expressions for the coefficient of diffusion in PyC are 2.9x10-⁷ exp(-61x10³/RT) for ¹³³Xe and 4.7x10-² exp(51x10³/RT) for ¹⁴⁰Ba. For the coefficients of evaporation of ¹⁴⁰Ba from PyC, the expression is 3.5x10³ exp(-42x10³ /RT). As for SiC, the diffusion and evaporation coefficients of these nuclides are given for a temperature of 1,750°C. A high diffusivity path for the diffusion of ¹⁴⁰Ba is postulated to explain the difference in diffusion behavior between ¹³³Xe and ¹⁴⁰Ba in PyC.     

On the influence of atomic explosions on meteorological processes

We consider the influence of the physical processes arising as results of atomic explosions on the meteorological factors of the earth's atmosphere. Calculations based on an analysis of the existing data show that the thermodynamical effect of an explosion is insignificant and can have no important effect on meteorological processes. Some changes of weather can be caused indirectly by the considerable disturbance of the electrical properties of the atmosphere and the consequent intensification of processes of condensation. In order of magnitude these changes may be comparable with the changes of weather caused by the periodic variations of solar activity.     

Improvements in the description of the multiplicities of the prompt neutrons emitted in fission

Various parameterizations of the multiplicity distribution of prompt neutrons from nuclear fission are investigated. The currently accepted formalism is found to fail for those fission processes which release on average a low number of neutrons. Based on realistic assumptions regarding binary fission, an improved multiplicity distribution formula gives much better agreement with the experimental data. Explicit details of the practical usage of the new formalism are presented. Finally, it is shown that for spontaneously fissioning isotopes, it is possible to calculate the variance of the neutron multiplicity distribution from a knowledge of the mass yield and the variances of the neutron multiplicity distributions of the individual fission fragments.     

从铀及其裂变产物中提取~(140)Ba

一、引言自铀及其裂变产物中提取~(140)Ba的方法较多,通常是先用离子交换法或萃取法除去大量的铀和高价态离子,然后用发烟硝酸将Sr,Ba与其他裂变产物分离,最后再进一步纯化Ba。这样操作麻烦费时。本文推荐一个方便快速的制取高纯~(140)Ba的方法,而且用此程序可分离测定铀样品中的~(140)Ba。     

Nuclear alternating parity bands and transition rates in a model of coherent quadrupole–octupole motion in neutron-rich barium isotopes

Deformed even–even nuclei Barium isotopes with quadrupole–octupole deformations are investigated on the basis of a collective model.The model describes energy levels of the yrast band with alternating parity in the neutron-rich~(140;142;144;146;148)Ba.The structure of the alternating parity bands is examined by odd–even (△I=1) staggering diagrams.An analytical method of the collective model is proposed for the calculation of E2 transition probabilities in alternating spectra of the nuclei~(140;142;144;146)Ba.     

24.4KeV中子诱发^235U裂变的产额测量

一、前言 对~(235)U热中子裂变已经作了充分的研究,裂变产物的产额作了广泛的测量,并对实验数据进行了多次编评。但是对于其它单能中子诱发~(235)U裂变研究还远远不够,尤其是keV能区的中子更是如此。J.G.Cuninghame等测量了130-1700keV中子诱发~(235)U裂变中一些核素的产额。但是低于130keV中子诱发的裂变研究,文献中未见过报道。为了研究产额随中子能     

Total cross section parameterizations for pion production in nucleon-nucleon collisions

Total cross section parameterizations for neutral and charged pion production in nucleon-nucleon collisions are compared to experimental data over the projectile momentum range from threshold to 300 GeV. Both proton-proton and proton-neutron reactions are considered. Overall excellent agreement between parameterizations and experiment is found, except for some disagreements near threshold. This gives much greater confidence to previously developed pion cross section formulas for nucleon-nucleon, proton-nucleus, and nucleus-nucleus reactions. These results are useful for particle transport.     

Rossi-α and Feynmann Y functions for non-Poissonian pulsed sources of neutrons in the stochastic pulsing method: Application to subcriticality monitoring in ADS and comparison with the results of Poissonian pulsed neutron sources

In this paper, analytical expressions for the Rossi-α and the Feynmann Y functions are deduced for the case of Poissonian and non-Poissonian neutron sources when the stochastic pulsing method is used. These analytical expressions are used to fit the experimental data and to obtain the prompt neutron time constant. Also we perform in this paper a comparison of the results obtained for the Rossi-α and Feynmann Y functions with Poissonian and non-Poissonian neutron sources, and we study how much change the shape of these functions when the fission probability decreases and the capture probability increases due to the depletion with time of the fuel, and the increase of the fission products. Some comparisons with experimental data and with the results of other authors have been performed. Another important question analyzed in this paper and that it is interesting from an academic point of view is that the average number of detected counts induced by one single neutron injected in the system at an arbitrary time t′, should obey in point kinetics theory an adjoint equation in the time domain. Also the cross-factorial moment of the number of counts induced by one neutron in two counting intervals should obey also an adjoint equation in the time domain with a source term that depends on the first moments. These results are a consequence of more general results that have been obtained using stochastic transport theory for the one particle probability generating function or Kernel generating function.     

次声波估算大气层核爆参数的计算方法综述

在介绍大气层核爆炸爆点距次声探测站点之间距离的计算方法基础上,总结国内外的历次核爆次声监测数据分析结果,给出了几种求解大气层核爆当量的经验计算方程式,并进行了分析比较。