Abstract Before a nuclear warhead is dismantled, the special nuclear material and explosives must be identified and authenticated. This paper proposes a passive method to detect and identify weapons-grade plutonium cores and explosives in nuclear warheads based on neutron analyses techniques. This paper first describes the principles of a passive detection method that calculates the element number ratio (namely the ratio between the nucleus numbers of two different elements) of the element of interest to identify a source and how this method could be applied to the detection of warhead explosives. Second, a simulation of weapons-grade plutonium using JMCT software is described. The simulation assumes the elemental components of the explosives are activated by the production and transport of neutrons from the weapons-grade plutonium core and counted the gamma ray emissions of from the resultant hydrogen, carbon, and nitrogen nuclides with a high-purity germanium detector (HPGe) array. After an hour of counting, the element number ratios of these elements in the simulation were reconstructed and accurately matched the values for the explosives in the warhead. These results suggest that the passive method can be used to identify the presence of weapons-grade plutonium in the warhead. In addition, the simulation showed that the passive method can also discriminate between the various types of explosives in warheads, providing important physical information for the verification process during dismantlement.

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一种检测核弹头中爆炸物和武器级钚的被动方法

摘要 在拆除核弹头之前，必须对特殊核材料和爆炸物进行鉴定和鉴定。本文提出了一种基于中子分析技术的被动检测和识别核弹头中的武器级钚芯和炸药的方法。本文首先介绍了一种被动检测方法的原理，该方法通过计算感兴趣元素的元素数比（即两种不同元素的核数之比）来识别来源，以及该方法如何应用于检测弹头炸药。其次，描述了使用 JMCT 软件对武器级钚的模拟。模拟假设炸药的元素成分通过武器级钚核心中子的产生和传输而被激活，并使用高纯度锗探测器计算由此产生的氢、碳和氮核素的伽马射线发射（ HPGe) 阵列。经过一个小时的计数，模拟中这些元素的元素数量比被重建，并准确匹配弹头中炸药的值。这些结果表明，被动方法可用于识别弹头中是否存在武器级钚。此外，模拟结果表明，被动法还可以区分弹头中的各种爆炸物，为拆除过程中的验证过程提供重要的物理信息。