基于γ与中子探测的钚元件模板测量方法研究  

Template measurement of plutonium pit based on γ-ray and neutron detection

作　　者：张昌繁[1] 龚建[1] 刘素萍[1] 胡广春[1] 向永春[1] 

机构地区：[1]中国工程物理研究院核物理与化学研究所,绵阳621900

出　　处：《核技术》2010年第7期506-512,共7页Nuclear Techniques

摘　　要：钚元件的模板测量是深度核裁军中的重要核查方法。钚元件的类型决定其γ能谱具有独特的特征:即如果两种钚部件设计相同,γ能谱是相似的,否则会出现差异。目前,钚元件模板测量主要是从申报钚元件衰变产生γ能谱中提取反映类型的特征量作为模板,将核查对象的特征量与模板进行比较,从而判断核查对象与申报钚部件是否属于同一类型。本文研究了从γ能谱中提取信息作为判别钚元件结构的模板数据的局限性:由于钚材料对γ射线的自吸收作用较强,在某些特定场景下仅依靠γ能谱不能有效辨别核查物与作为模板的钚元件的结构是否一致。通过MCNP模拟对该问题进行了验证。进一步研究发现在测量γ能谱的同时,测量钚元件自发裂变的中子计数率可以改善这个问题。Template measurement is of importance in deep nuclear disarmament. The γ-ray spectrum of plutonium pit shows unique property due to age, isotopic abundance and mass of the plutonium pit. The pits of the same design have similar γ-ray spectra, but the spectrum differs form that of a pit in different design. Useful information can be extracted from γ-ray spectrum generated by using a standard plutonium pit as a template. A comparison between the inspected objects and the template leads to conclusion whether they are of the same type. In this paper, we study how to choose the template data from γ-ray spectrum and discuss limitations of using the γ-ray spectrum only. Because of strong self-absorption of plutonium, some characteristics of plutonium pit cannot be identified by the gamma spectrum only. MCNP simulations were employed to prove that, in some cases, template depending on just the γ-ray spectrum cannot effectively distinguish the spurious objects. And a further approach indicates that enhancing neutron counting rate of spontaneous fission of plutonium can improve the model identification.

关 键 词：钚部件 模板测量 Γ能谱 中子计数率 

分 类 号：TJ910.89[兵器科学与技术—武器系统与运用工程] TL242.1[核科学技术—核燃料循环与材料]