Carrigan Charles R, Sun Yunwei, Hunter Steven L, Ruddle David G, Wagoner Jeffrey L, Myers Katherine B L, Emer Dudley F, Drellack Sigmund L, Chipman Veraun D
Lawrence Livermore National Laboratory, Livermore, California, USA.
National Security Technologies, Las Vegas, Nevada, USA.
Sci Rep. 2016 Mar 16;6:23032. doi: 10.1038/srep23032.
Radionuclide signals from underground nuclear explosions (UNEs) are strongly influenced by the surrounding hydrogeologic regime. One effect of containment is delay of detonation-produced radioxenon reaching the surface as well as lengthening of its period of detectability compared to uncontained explosions. Using a field-scale tracer experiment, we evaluate important transport properties of a former UNE site. We observe the character of signals at the surface due to the migration of gases from the post-detonation chimney under realistic transport conditions. Background radon signals are found to be highly responsive to cavity pressurization suggesting that large local radon anomalies may be an indicator of a clandestine UNE. Computer simulations, using transport properties obtained from the experiment, track radioxenon isotopes in the chimney and their migration to the surface. They show that the chimney surrounded by a fractured containment regime behaves as a leaky chemical reactor regarding its effect on isotopic evolution introducing a dependence on nuclear yield not previously considered. This evolutionary model for radioxenon isotopes is validated by atmospheric observations of radioxenon from a 2013 UNE in the Democratic People's Republic of Korea (DPRK). Our model produces results similar to isotopic observations with nuclear yields being comparable to seismic estimates.
地下核爆炸（UNE）产生的放射性核素信号受到周围水文地质条件的强烈影响。与无约束爆炸相比，约束作用的一个效果是延迟爆炸产生的放射性氙到达地表，并延长其可探测期。通过一项野外尺度的示踪剂实验，我们评估了一个前地下核爆炸场地的重要输运特性。我们在实际输运条件下观测了爆后烟囱中气体迁移导致的地表信号特征。发现背景氡信号对空洞增压高度敏感，这表明局部大的氡异常可能是秘密地下核爆炸的一个指标。利用从实验中获得的输运特性进行的计算机模拟，追踪了烟囱中的放射性氙同位素及其向地表的迁移。模拟结果表明，被破碎的约束层包围的烟囱在其对同位素演化的影响方面表现为一个泄漏的化学反应器，这引入了一种对核产量的依赖性，而这种依赖性以前未被考虑。通过对朝鲜2013年一次地下核爆炸产生的放射性氙进行大气观测，验证了这种放射性氙同位素的演化模型。我们的模型产生的结果与同位素观测结果相似，核产量与地震估计值相当。
