Novel methodology for the quantitative assay of fissile materials using temporal and spectral β-delayed γ-ray signatures

An analytical model for the generation of β-delayed γ-ray spectra following thermal-neutron-induced fission of mixed samples of ²³⁵U and ²³⁹Pu is presented. Using an energy-dependent figure-of-merit to designate the spectral regions employed in the assay, the unique temporal β-delayed γ-ray signatures are utilized to determine the fraction of ²³⁹Pu in a mixed U-Pu sample. By evaluating the β-delayed γ-ray temporal signatures of both ²³⁵U and ²³⁹Pu within a 3 keV energy bin, traditional sources of systematic uncertainty in quantitative assay using β-delayed γ-ray signals, such as self-attenuation of the sample and energy-dependent γ-ray detection efficiency, are significantly reduced. The effects of the time-dependent Compton-continuum and growth of longer-lived nuclides on the quantitative assessment are explored. This methodology represents a promising extension of the conventional means of analysis for quantitative assay of fissile materials using β-delayed γ-ray signatures.     

Experimental determination of photofission cross-sections of Th using electron accelerator

Photofission cross-section of ²³²Th was measured using Bremsstrahlung radiation energy 7.4–9.2 MeV with energy step of 0.3 MeV by employing Lexan polycarbonate film as Solid State Nuclear Track Detectors (SSNTD). The photon intensity from the Microtron accelerator facility was estimated to be 10¹⁰ photons/s at a distance of 15 cm from the Bremsstrahlung converter using EGS-4 code (Nelson et al., 1985). Photofission cross-sections were evaluated using fission fragment angular distribution measurements. The present experimental results were compared with EMPIRE-2.19 (Herman et al., 2005) code prediction of RIPL-1 and RIPL-2 ( and ) and a new analytical formula (Gupta and Saxena, 2005) for fission barrier.     

固体径迹探测器测量微型反应堆裂变率

利用固体径迹探测器测量处于微型反应堆不同位置的燃料元件内单位体积的裂变率,得到了堆的裂变率分布和总裂变率,并与其它参数相结合,求得了反应堆功率。同时,测量了对应功率下反应堆内辐照座的热中子通量密度,得到了单位功率的热中子通量密度,从而求得了额定中子通量密度下的运行功率。文章给出的测量方法,避免了其它方法测量功率所引入的近似假设。     

裂变径迹长度标准化研究进展

本文叙述了裂变径迹热历史研究中裂变径迹长度测量标准化的必要性,总结了影响长度测量的各种因素和解决方法,以及锆石的蚀刻程序及长度标准样品的提出,并进行了初步的实验研究。     

机床夹具结构设计及方案构思原则

结合生产实践,应用一些简单实用图例,由多个方面说明机床夹具零部件设计中结构设计及方案构思的要点和技巧,供技术人员在解决实际问题时参考.     

Apoptosis in immune cells induced by fission fragment ^147Pm

Apoptosis in human acute lymphoblastic leukemia cell line Molt-4 cell and macrophage cell line Ana-1 cell could be induced by fission fragment 147Pm,The cumulative absorption dose of ^147Pm in cultural cells through different periods were estimated.By using fluorescence microscopy and microautoradiographic tracing it can be found that Molt-4 and Anal-1 cells internally irradiated by ^147Pm,displayed an obvious nuclear fragmentation and a marked phknosis in immune cell nucei,as well as DNA chain fragmentation and apoptotic bodies formation.The microautoradiographic study showed that ^147Pm could infiltrate thourgh cell membrane and displayed membrane-seeking condensation in cells.At the same time.the membrane-bounded apoptotic bodies were observed.Experimental results in recent study provide evidence that Molt-4 and Ano-1 immune cells undergo apoptosis while internally irradiated with ^147Pm.     

从“第五不稳定核素系”展望^238U增强利用的前景

对目前水反应堆中＾２３８Ｕ的利用现状作了剖析，根据作者在以前文章中介绍的“第五不稳定核素系”的性质，提出了使＾２３８Ｕ得到更好利用的可能性，并对可能遇到的问题作了估计。     

微型反应堆裂变率分布实验研究

利用固体径迹探测器测量处于微型反应堆不同益的燃料元件内单位体积的裂变率，得到了堆的裂变经分布和总裂变率，并与其它参数相结合求得了反应堆功率。同时，测量了对应功率下反应堆内辐照座的热中子通量密度得到单位功率的热中子能量密度，即额定中子能量密度下的运行功率。文章给出的测量方法，避免了金箔法测量反应堆功率所引入的近似假设。     

用于裂变径迹刻度的国产铀标准玻璃

叙述了用于裂变径迹刻度的国产铀标准玻璃的各项性能；并对铀玻璃中的铀含量进行了定值，对杂质元素进行了准确分析；检验的铀玻璃发裂变径迹的响应。     

钍-铀燃料后处理中新萃取剂的研究——Ⅱ.亚砜类的研究及其结构与性能的关系

研究了5种亚砜类萃取剂在稀释剂(煤油及芳烃稀释剂)中的溶解性及对钍、铀的萃取性能。结果表明,二个具支链的烷基亚砜,即二(2-乙基己基)亚砜及二(1-甲基庚基)亚砜不仅与TBP一样可与煤油互溶,而且某些性能优于TBP。还对亚砜萃取剂结构与性能的关系作了初步探讨。