基于武器级铀的核弹头内部炸药探测的模拟研究

Simulation Study on Explosive Detection in Nuclear Warhead with Weapons-grade Uranium

在军备控制核查技术领域,核弹头内部炸药的探测是一项重要的研究。本文利用GEANT4软件研究了基于武器级铀的核弹头(即铀弹头)内部炸药的被动探测法(利用铀弹头内部裂变中子作为中子源)的可行性,计算得到了从铀弹头中出射的γ射线能谱,能谱的形状与预期相符,但由于铀弹头内部裂变中子与炸药中^(14) N反应产生的特征γ光子的事例率太低,该方法可能不适用于铀弹头的现场测量。因此又利用GEANT4软件研究了铀弹头内部炸药的主动探测法(利用铀弹头外部的中子源对铀弹头进行辐照)的可行性。研究结果表明,主动探测法可在1h内实现对铀弹头内部炸药中^(14) N的探测和确认,进而能为判定铀弹头内部是否含有炸药提供重要依据。

In the field of arms control verification techniques,the detection of the explosives in the nuclear warheads is an important research.In this paper,GEANT4 software was used to study the feasibility of the passive detection（using the fission neutrons in the nuclear warheads as the neutron source）of the explosives in the nuclear warheads with weapons-grade uranium cores（namely WgU warheads）.Theγspectrum emitted from the nuclear warhead was calculated,agreeing with the expectation.However,due to the low event rate of the characteristicγphotons produced by the reactions of the fission neutrons in the WgU warheads and ^（14） N in the explosive,this method is not applicable for the field measurement of the WgU warheads.So the feasibility of the active detection（using the neutron source outside the nuclear warheads to irradiate the warheads）of the explosives in the WgU warheads was studied based on GEANT4 software.The simulation results show that the ^（14） N in explosives in the WgU warheads canbe detected and confirmed within 1 h based on the active detection method,which can provide important evidence for judging whether the WgU warhead contains explosive.