A novel method for simulating nuclear explosion with chemical explosion to form an approximate plane wave: Field test and numerical simulation

A nuclear explosion in the rock mass medium can produce strong shock waves,seismic shocks,and other destructive effects,which can cause extreme damage to the underground protection infrastructures.With the increase in nuclear explosion power,underground protection engineering enabled by explosion-proof impact theory and technology ushered in a new challenge.This paper proposes to simulate nuclear explosion tests with on-site chemical explosion tests in the form of multi-hole explosions.First,the mechanism of using multi-hole simultaneous blasting to simulate a nuclear explosion to generate approximate plane waves was analyzed.The plane pressure curve at the vault of the underground protective tunnel under the action of the multi-hole simultaneous blasting was then obtained using the impact test in the rock mass at the site.According to the peak pressure at the vault plane,it was divided into three regions:the stress superposition region,the superposition region after surface reflection,and the approximate plane stress wave zone.A numerical simulation approach was developed using PFC and FLAC to study the peak particle velocity in the surrounding rock of the underground protective cave under the action of multi-hole blasting.The time-history curves of pressure and peak pressure partition obtained by the on-site multi-hole simultaneous blasting test and numerical simulation were compared and analyzed,to verify the correctness and rationality of the formation of an approximate plane wave in the simulated nuclear explosion.This comparison and analysis also provided a theoretical foundation and some research ideas for the ensuing study on the impact of a nuclear explosion.

Hydromechanical characterization of gas transport amidst uncertainty for underground nuclear explosion detection

Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of underground nuclear explosions(UNEs).However,the migration of signature radionuclide gases between the nuclear cavity and surface is not well understood because complex processes are involved,including the generation of complex fracture networks,reactivation of natural fractures and faults,and thermo-hydro-mechanical-chemical(THMC)coupling of radionuclide gas transport in the subsurface.In this study,we provide an experimental investigation of hydro-mechanical(HM)coupling among gas flow,stress states,rock deformation,and rock damage using a unique multi-physics triaxial direct shear rock testing system.The testing system also features redundant gas pressure and flow rate measurements,well suited for parameter uncertainty quantification.Using porous tuff and tight granite samples that are relevant to historic UNE tests,we measured the Biot effective stress coefficient,rock matrix gas permeability,and fracture gas permeability at a range of pore pressure and stress conditions.The Biot effective stress coefficient varies from 0.69 to 1 for the tuff,whose porosity averages 35.3%±0.7%,while this coefficient varies from 0.51 to 0.78 for the tight granite(porosity<1%,perhaps an underestimate).Matrix gas permeability is strongly correlated to effective stress for the granite,but not for the porous tuff.Our experiments reveal the following key engineering implications on transport of radionuclide gases post a UNE event:(1)The porous tuff shows apparent fracture dilation or compression upon stress changes,which does not necessarily change the gas permeability;(2)The granite fracture permeability shows strong stress sensitivity and is positively related to shear displacement;and(3)Hydromechanical coupling among stress states,rock damage,and gas flow appears to be stronger in tight granite than in porous tuff.

Atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering correction

In high-altitude nuclear detonations,the proportion of pulsed X-ray energy can exceed 70%,making it a specific monitoring signal for such events.These pulsed X-rays can be captured using a satellite-borne X-ray detector following atmospheric transmission.To quantitatively analyze the effects of different satellite detection altitudes,burst heights,and transmission angles on the physical processes of X-ray transport and energy fluence,we developed an atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering correction.The proposed method is an improvement over the traditional analytical method that only computes direct-transmission X-rays.The traditional analytical method exhibits a maximum relative error of 67.79% compared with the Monte Carlo method.Our improved method reduces this error to within 10% under the same conditions,even reaching 1% in certain scenarios.Moreover,its computation time is 48,000 times faster than that of the Monte Carlo method.These results have important theoretical significance and engineering application value for designing satellite-borne nuclear detonation pulsed X-ray detectors,inverting nuclear detonation source terms,and assessing ionospheric effects.

Impact of atmospheric ionization by delayed radiation from highaltitude nuclear explosions on radio communication

In this study,we investigated the motion,shape,and delayed radiation intensity of a radioactive cloud by establishing a volume-source model of delayed radiation after high-altitude nuclear explosions.Then,the spatial distribution of electron number density at different moments on the north side of the explosion point generated by delayed γ-rays and delayed β-rays from the radioactive cloud under the influence of the geomagnetic field was calculated by solving chemical reaction kinetics equations.The impact of radio communication in the different frequency bands on the process of atmospheric ionization was also studied.The numerical results of the high-altitude nuclear explosion (120 km high and with a 1 megaton equivalent at 40°N latitude) indicated that the peak of electron number density ionized delayed γ-rays is located at a height of approximately 100 km and that of electron number density ionized delayed β-rays is about 90 km high.After 1 min of explosion,the radio communication in the medium frequency (MF) and high-frequency (HF)bands was completely interrupted,and the energy attenuation of the radio wave in the very high-frequency (VHF)band was extremely high.Five minutes later,the VHF radio communication was basically restored,but the energy attenuation in the HF band was still high.After 30 min,theVHF radio communication returned to normal,but its influence on the HF and MF radio communication continued.

Nuclear fusion from Coulomb explosions of deuterated methane clusters subjected to ultraintense femtosecond laser pulses

This paper reports that Coulomb explosions taken place in the experiment of heteronuclear deuterated methane clusters （（CD4）n） in a gas jet subjected to intense femtoseeond laser pulses （170 mJ, 70 fs） have led to table-top laser driven DD nuclear fusion. The clusters produced in supersonic expansion had an average size of about 5 nm in radius and the laser intensity used was 3 × 10^17 W/cm^2.The measured maximum and average energies of deuterons produced in the laser-cluster interaction were 60 and 13.5 keV, respectively. Prom DD collisions of energetic deuterons, a yield of 2.5（±0.4） × 10^4 fusion neutrons of 2.45 MeV per shot was realized, giving rise to a neutron production efficiency of about 1.5 × 10^5 per joule of incident laser pulse energy. Theoretical calculations were performed and a fairly good agreement of the calculated neutron yield with that obtained from the present experiment was found.

Discrimination between nuclear explosions and earthquakes based on consideration of tectonic ambient shear stress values

On the basis of fracture mechanics earthquake rupture model, the relations between source parameters and (0, the value of tectonic ambient shear stress in the place where the earthquake occurs, have been derived. Thus, we can calculate a large number of values of tectonic ambient shear stress or values of background stress in the place where the earthquake occurs. If nuclear explosions are treated as earthquakes in the calculation, we find that (0 values of nuclear explosions have about 20 MPa, which is obviously higher than average (0 values of earthquakes with the same magnitude. This result can be used to discriminate nuclear explosions from earthquakes.

Study on Contact Explosion Performance of Nuclear Containment

Reinforced concrete (RC) shield building as the first external defense layer of AP1000 structure plays an important role in protection the population and environment when against the outer explosion. The strain rate effect of reinforced concrete was taken into consideration in the establishment of an AP1000 nuclear island structure-air-explosives fully coupled model by using the software AUTODYN. Object using damage mass as index, to infer the degree of damage. This paper studied the pressure evolution and damage mechanism. The analysis results provide valuable data on improving the anti-explosion capabilities in design based on the damage characteristics.

Discrimination Between Nuclear Explosions and Earthquakes: An Application of Wigner Distribution

In this paper,the nonstationary theory of Wigner Distribution is used to discriminate between underground nuclear explosions and natural earthquakes.Five underground explosions in Kazakhstan region and seven regional earthquakes in its adjacent areas have been analyzed.The result shows that the transient spectra of underground nuclear explosions are concentrated in the frequency range of 5-10 Hz,while the transient spectra of natural earthquakes are distributed widely from lower frequency to higher frequency.The transient frequency of nuclear explosions shows linearity in the first stage(0【t【0.75 s)and its initial frequency is negative.The transient frequency of natural earthquakes rapidly changes in a jumping form and its initial frequency alternates between being positive and negative.The obtained results show that the method is more effective than previous ones in discriminating between underground nuclear explosions and earthquakes.This paper also gives a preliminary explanation of the discrepancy

Nuclear Explosion Fusion Power Plant——the Hope of the Mankind Future Energy

In this article,the basic concept,constitute and brief development history of Nuclear Explosions Fusion Power Plant is introduced.A series of technique is put forward to solve the implement safety of nuclear explosion;the designs of nuclear devicein deuterium-type and the reclamation of nuclear fuel are put forward.The technique possibility of power station is analyzed,and the prospect of all kinds of nuclear energy project to provide energy of the mankind future are compared.

Discriminating between explosions and earthquakes

Earthquake, explosion, and a nuclear test data are compared with forward modeling and band-pass filtered surface wave amplitude data for exploring methodologies to improve earthquake–explosion discrimination. The proposed discrimination method is based on the solutions of a double integral transformation in the wavenumber and frequency domains. Recorded explosion data on June 26, 2001（39.212°N, 125.383°E） and October 30, 2001（38.748°N, 125.267°E）, a nuclear test on October 9, 2006（41.275°N, 129.095°E）, and two earthquakes on April 14, 2002（39.207°N, 125.686°E） and June 7, 2002（38.703°N, 125.638°E）, all in North Korea, are used to discriminate between explosions and earthquakes by seismic wave analysis and numerical modeling. The explosion signal is characterized by first P waves with higher energy than that of S waves. Rg waves are clearly dominant at 0.05–0.5 Hz in the explosion data but not in the earthquake data. This feature is attributed to the dominant P waves in the explosion and their coupling with the SH components.

Explosion of Sun

The Sun contains ~74% hydrogen by weight. The isotope hydrogen-1 (99.985% of hydrogen in nature) is a usable fuel for fusion thermonuclear reactions. This reaction runs slowly within the Sun because its temperature is low (relative to the needs of nuclear reactions). If we create higher temperature and density in a limited region of the solar interior, we may be able to produce self-supporting detonation thermonuclear reactions that spread to the full solar volume. This is analogous to the triggering mechanisms in a thermonuclear bomb. Conditions within the bomb can be optimized in a small area to initiate ignition, then spread to a larger area, allowing producing a hydrogen bomb of any power. In the case of the Sun certain targeting practices may greatly increase the chances of an artificial explosion of the Sun. This explosion would annihilate the Earth and the Solar System, as we know them today. The reader naturally asks: Why even contemplate such a horrible scenario? It is necessary because as thermonuclear and space technology spreads to even the least powerful nations in the centuries ahead, a dying dictator having thermonuclear missile weapons can proce (with some considerable mobilization of his military/industrial complex)—an artificial explosion of the Sun and take into his grave the whole of humanity. It might take tens of thousands of people to make and launch the hardware, but only a very few need know the final targeting data of what might be otherwise a weapon purely thought of (within the dictator’s defense industry) as being built for peaceful, deterrent use. Those concerned about Man’s future must know about this possibility and create some protective system—or ascertain on theoretical grounds that it is entirely impossie. Humanity has fears, justified to greater or lesser degrees, about asteroids, warming of Earthly climate, extinctions, etc. which have very small probability. But all these would leave survivors—nobody thinks that the terrible annihilation of the Solar System would leave a single person alive. That explosion appears possible at the present time. In this paper is derived the “AB-Criterion” which shows conditions wherein the artificial explosion of Sun is possible. The author urges detailed investigation and proving or disproving of this rather horrifying possibility, so that it may be dismissed from mind—or defended against.

Study of the Electric Explosion of Titanium Foils in Uranium Salts

The results of experiments on electroexplosion titanic foil in water solutions of salts of uranium are presented in this paper. It is shown, that as a result of electroexplosion occurs appreciable (to 20%) distortion of an initial isotope parity of uranium. In the most solution parts, observable isotope distortion occurs in favour of enrichment by 235U. At the moment of electroexplosion it was not observed an appreciable stream of the neutrons. By means of Cs label and by methods by α, β, γ-spectrometry and mass-spectrometry it have been shown, that isotope distortion occurs at the expense of non-uniform “disappearance” of both isotopes from a solution. The isotope distortion leads to infringement of the 234Th secular equilibrium in the uranyl solution. The equilibrium infringement between the 234Th and 234mPa, i.e. within the proper thorium decay chain, was observed also. The assumption about that the effects are caused of low-energy nuclear reactions at the moment of electroexplosion is suggested.

Concept of Application of Nuclear Explosive Devices in a Space-Rocket Complex to Protect the Earth against AsteroidaI-Cometary Danger

Herein an estimation is given to the efficiency of nuclear explosive devices in a space-rocket complex to withdraw Hazardous Space Objects （HS0）-asteroids and cometary nuclei from the trajectories leading to their dangerous entry to the atmosphere and falling to the Earth. A conceptual choice of parameters and schemes of application of nuclear explosive devices in impact modules of space-rocket complexes to ensure asteroidal-cometary safety was made.

高空核爆炸晚期核电磁脉冲的数值模拟研究

根据高空核爆炸晚期核电磁脉冲(E3)的产生机理,将E3的计算分解为大气电离、碎片云运动、大气等离子体运动和低频电磁场在等离子体中的传播4个过程,给出了E3的数值模拟方法。利用该方法模拟了美国Starfish试验的E3过程,通过与试验观测地磁数据的比对验证了该方法的正确性。对离子的能量沉积分析结果表明,爆心正下方存在大气等离子体火球,能量峰值约为175 km,此火球向下膨胀导致地磁场增强,向上运动导致磁场变弱。该结果解释了Starfish试验地磁扰动波形的变化机理,与原有解释机理相比,无需引入额外的假设。

利用区域地震资料监测朝鲜地下核试验的研究进展

根据朝鲜6次地下核试验在中国东北及邻近地区产生的宽频带区域地震资料,中国科学院地质与地球物理研究所地震学学科组发展了一套用于监测地下核试验的地震学方法,主要包括震级测量和当量估计、高精度震中定位以及爆炸与天然地震事件识别等.在全球范围内,存在多个用于震级-当量转换的经验公式,确定何种公式适合于朝鲜半岛地区至关重要.通过搜集一组用于地震测深的化学爆炸的当量和埋深,并以这些已知爆炸源作为量规事件,能够标定朝鲜地下核试验场的震级-当量关系,从而实现对朝鲜地下核爆进行当量估计.在精确定位方面,发展了利用多事件之间波形互相关方法精确测定它们之间的走时差从而完成高精度相对震中定位.通过进一步利用Pn和Pg等多震相数据还实现了对核爆深度的相对定位.在爆炸震源识别方面,利用统计处理方法分析研究了不同类型事件所产生地震波的特征,包括6次地下核试验、4次天然地震和3次化学爆炸,以及一些矿区塌陷等.结果发现P和S类型波的振幅比,例如Pn/Lg、Pg/Lg和Pn/Sn等,在2 Hz以上能够较好区分各类震源.其中爆炸震源产生的振幅比显著高于天然地震的值.特别是,通过计算谱振幅比的台网平均值能够显著提高识别的可靠性.利用中国东北和附近地区地震台网所提供的数据可以准确地将朝鲜地下核试验从周边天然地震事件中识别出来.该方法同时得到化学爆炸的P/S谱振幅比值介于核爆炸和天然地震的群组之间.

基于升降轨SAR数据的地下核爆参数反演与3D形变监测方法

以朝鲜第6次地下核试验为例,基于升降轨ALOS-2 SAR数据,首先利用D-InSAR技术获取核试验场的视线向形变,以此为基础,基于贝叶斯反演方法确定核爆参数,然后引入POT技术测量核试验场方位向和距离向形变,最后,融合D-InSAR与POT结果计算核试验地表三维形变场.研究发现,核爆位于朝鲜丰溪里试验场万塔山下,其坐标为东经129.0792°,北纬41.3026°,深度约为550 m,核爆导致发生水平方向位移约3 m,垂直方向位移约1 m.结果表明天基SAR遥感技术,特别是长波段SAR,在地下核试验监测中具有重要的应用价值,可为地下核试验监测提供新思路.

高空核爆炸磁流体动力学电磁脉冲

高空核爆炸产生的磁流体动力学(晚期)电磁脉冲对电力系统等国家重要基础设施具有严重影响。由于晚期电磁脉冲产生的机理复杂,依赖因素众多,包括爆炸当量、爆高、爆炸方位、爆炸时间、观察点位置以及土壤电导率等,因此,目前还没有成熟的代码可以模拟整个晚期电磁脉冲的产生过程。介绍晚期电磁脉冲的产生机理,讨论晚期电磁脉冲电场随核装置爆炸当量、爆高和大气状况的变化关系。E3A电场峰值随爆炸当量线性增加,而E3B电场峰值则随爆炸当量增加出现明显的饱和效应。分析了当前晚期电磁脉冲模拟代码现状,为进一步研究晚期电磁脉冲数值模拟方法和代码研发提供参考。

基于短波段电离层探测数据分析地下核爆引起的电离层扰动

同全球导航卫星系统(global navigation satellite system, GNSS)获取电离层总电子含量(total electron content, TEC)数据相比,传统的电离层垂测、斜测等短波段数据具有特征参数丰富、高度分辨率高、历史数据多等优点。为利用电离层垂测和斜测数据,研究地下核爆引起的电离层扰动。利用2016年1月6日朝鲜地下核试验当天的斜测、垂测数据分析电离层扰动现象。结果表明,本次地下核爆造成的行波电离层扰动为小尺度电离层扰动,传播速度为150.3~158.7 m/s。同时核爆发生后0.5 h在距离爆点421.4 km处,观测到F2层临界频率(critical frequency of the F2layer, foF2)较月中值增加了0.7 MHz,较1月5日、1月7日在协调世界时(coordinated universal time, UTC)2:00 UTC的增加了0.5 MHz,极有可能是地下核爆通过岩石圈-大气圈-电离层圈耦合机制造成电离层电子浓度增加。本文分析结果与其他文献资料非常吻合。由此可见,基于短波段电离层探测方式感知电离层扰动从而实现地下核爆炸事件的监测,是一种有效的核爆电离层效应监测手段,可与其他直接监测手段相印证,提高核爆事件监测能力。

核爆炸光辐射能量分布的模拟仿真研究

光辐射是核爆炸中能量的重要组成部分,因此研究其在空间中的热能分布规律具有重要的意义。根据核爆炸理论中火球的发展规律和光辐射的瞬时能量特征得到核爆炸光辐射的热能计算公式,该公式主要与爆炸高度、爆炸当量、大气衰减系数、火球半径和火球温度有关。首先,通过设计不同地图、改变核爆的相关参数进行模拟计算,分析了核爆炸光辐射热能的分布特点。然后,结合光辐射烧伤的伤情分级标准,在模拟程序中添加搜寻功能,实现自动对虚拟地图的伤情分级半径区域进行划分。最后,采用神经网络训练模拟数据,得到核爆的相关参数与地图伤情分级半径的映射关系,从而能够由核爆炸参数直接预测目标地图上的伤情分级半径,可大大缩短计算时间。

无风条件下近地爆烟尘的大气γ电离辐射环境模拟

近地爆烟尘由不同粒径尺度的放射性颗粒组成,且运动的时空尺度大。针对近地爆烟尘的大气γ电离辐射环境模拟这一难题,首先开展了γ大气辐射机理分析,进行了无风条件设定,建立了烟尘γ辐射的理论模型,其次引入和提出了相应的数值差分与积分算法,最后给出了对1000 kt内华达近地爆烟尘在大气中的放射性活度和辐射剂量率的模拟算例,完成了一定的辐射环境时空演变规律总结与结果对比,对比发现本模型在保证活度结果一致性的同时,能计算出大气辐射剂量率的理论最大值。