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The influence of simulating factors of a nuclear explosion and proton irradiation on the photoelectric properties of photodiodes based on indium selenide was studied. It was established that neutron pulses lead to an improvement in the photoelectric properties of the photodiodes under study. It has been shown that high fluences of neutron irradiation facilitate the process of breaking off complexes in the interlayer space of layered indium selenide, as a result of which the photoelectric parameters of photodiodes somewhat deteriorate. [ABSTRACT FROM AUTHOR]

In the early years of nuclear explosion monitoring, experts used downwind detections with meaningful ratios of radioactive species to identify an explosion. Today's reality is sparse networks of radionuclide monitoring stations looking for weak signals. Analysts need to discriminate between industrial background radioactivity and nuclear explosion signals, even using the detection of one isotope. Aerosol and xenon measurements potentially related to nuclear tests in 2006 and 2013 announced by the Democratic People's Republic of Korea and from worldwide civilian background radioactivity are considered when defining radionuclide detection anomalies to objectively guide the use of limited analyst resources and reduce the possibility of not detecting nuclear explosions. [ABSTRACT FROM AUTHOR]

The article analyzes the process of formation and establishes the characteristics of the striking factors of a nuclear explosion of tactical nuclear ammunition with a power of 0.1 to 10 kt when damaging military facilities and the accompanying damage to the population of civilian communities and personnel of infrastructure facilities. Calculated are data on the parameters of air shock wave action zones, penetrating radiation flow, light pulse energy beam flow, and the dimensions of the zone of radioactive contamination of the area, which can create a negative impact on the population, residential buildings, personnel, and critical infrastructure facilities in the area of application of tactical nuclear weapons. It is shown that the zone affected by an air shock wave, depending on the type of explosion of tactical nuclear ammunition and its power, can reach a radius of up to 3100 m. Dangerous light pulse damage to the population and personnel located in the open area will be observed at a distance of 440 to 3700 m from the epicenter of the nuclear explosion. The negative impact of the penetrating radiation of a nuclear explosion on the population and personnel of critical infrastructure facilities will be observed at distances from 560 to 1300 m, depending on the type of explosion and the power of the tactical nuclear ammunition. The dimensions of the zone of radioactive contamination, in the case of the explosion of tactical nuclear ammunition, in which the most severe degree of radiation damage to the population and personnel of critical infrastructure objects will be observed, with their open location in the area, depending on the power and type of explosion, can reach from 1400 to 2600 m. And the zone in which it is necessary to carry out the priority immediate evacuation of the population can be from 3.4 to 44.0 km in the direction of the average wind. It was determined that the scale of radioactive contamination of the area will have the greatest values of the size of the areas of negative impact relative to other types of impressive factors of the nuclear explosion of tactical nuclear ammunition. In large areas of the regions adjacent to the area of application of the specified ammunition, a significant negative radiation effect will be created, which will require measures of radiation protection and evacuation of the population. [ABSTRACT FROM AUTHOR]

Many well-established models exist for predicting the dispersion of radioactive particles that will be generated in the surrounding environment after a nuclear weapon explosion. However, without exception, almost all models rely on accurate source term parameters, such as DELFIC, DNAF-1, and so on. Unlike nuclear experiments, accurate source term parameters are often not available once a nuclear weapon is used in a real nuclear strike. To address the problems of unclear source term parameters and meteorological conditions during nuclear weapon explosions and the complexity of the identification process, this article proposes a nuclear weapon source term parameter identification method based on a genetic algorithm (GA) and a particle swarm optimization algorithm (PSO) by combining real-time monitoring data. The results show that both the PSO and the GA are able to identify the source term parameters satisfactorily after optimization, and the prediction accuracy of their main source term parameters is above 98%. When the maximum number of iterations and population size of the PSO and GA were the same, the running time and optimization accuracy of the PSO were better than those of the GA. This study enriches the theory and method of radioactive particle dispersion prediction after a nuclear weapon explosion and is of great significance to the study of environmental radioactive particles. [ABSTRACT FROM AUTHOR]

An asteroid impact can potentially destroy life on this planet. Therefore, asteroids should be prevented from impacting the Earth to impede severe disasters. Nuclear explosions are currently the only option to prevent an incoming asteroid impact when the asteroid is large or the warning time is short. However, asteroids exist in an absolute vacuum, where the explosion energy propagation mechanism differs from that in an air environment. It is difficult to describe this process using standard numerical simulation methods. In this study, we used the single-material arbitrary Lagrangian–Eulerian (ALE) method and the finite element-smoothed particle hydrodynamics (FE-SPH) adaptive method to simulate the process of deflecting hazardous asteroids using penetrating explosions. The single-material ALE method can demonstrate the expansion process of explosion products and energy coupling in absolute vacuum. The FE-SPH adaptive method can transform failed elements into SPH particles during the simulation, avoiding system mass loss, energy loss, and element distortion. We analyzed the shock initiation and explosion damage process and obtained an effective simulation of the damage evolution, stress propagation, and fragment distribution of the asteroid. In addition, we decoupled the penetrating explosion into two processes: kinetic impact and static explosion at the impact crater. The corresponding asteroid damage modes, velocity changes, and fragmentation degrees were simulated and compared. Finally, the high efficiency of the nuclear explosion was confirmed by comparing the contribution rates of the kinetic impact and nuclear explosion in the penetrating explosion scheme. [ABSTRACT FROM AUTHOR]

Radionuclide monitoring for nuclear explosions includes measuring radioactive aerosol and noble gas concentrations in the atmosphere. The International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban Treaty has made such measurements for decades, revealing much about how atmospheric radioactivity impacts the sensitivity of the network. For example, civilian emissions of radioiodine make a substantial regional impact, but a minor global impact, while civilian radioxenon emissions create major regional and complex global impacts. The impacts are strongly influenced by the minimum releases anticipated to be interesting. The original design of the IMS anticipated relatively large releases, and the current IMS network substantially meets or exceeds the sensitivity needed to detect those levels. Much lower signal levels can be motivated from historical tests. Using a release that corresponds roughly to a one-ton equivalent of fission in the atmosphere rather than the design level of one-kiloton equivalent, the network detection probabilities for 140Ba and 131I are quite good (~ 75%) and for 133Xe is still considerable (~ 45%). Using measured and simulated background concentrations, various possible desired signal levels, and an innovative anomaly threshold, maps of sensitivity and a station ranking are developed for IMS radionuclide stations. These provide a strong motivation for additional experimentation to learn about sources and the potential plusses of new technology. [ABSTRACT FROM AUTHOR]

Underground nuclear explosions generate non-isothermal two-phase flow, heat and mass transfer, and tracer transport through fractured porous media. The governing equations of these coupled phenomena on the Darcy scale are presented and the corresponding numerical code is briefly described. Two configurations are considered. In the first one, the damaged zone generated by the explosion is replaced by equivalent macroscopic boundary conditions at the bottom of the medium. Vapor condensation at distance from this zone plays a crucial role and slows down the tracer transport to the ground surface, while the presence of hot liquid water and of hot rubble particles in it accelerates it. In the second configuration, the damaged zone itself is treated as a porous medium with specific properties and is integrated in the simulation domain. Several regions can be distinguished with different properties, such as the chimney, the cavity, the solidified magma, the fractured porous medium, and the intact porous medium. Phase change, heat transfer and tracer transport can be detailed in these regions and at the boundaries between them. Among the most important conclusions, the role of phase change, of the thermal properties and therefore of the temperature, is pointed out. [ABSTRACT FROM AUTHOR]

Monitoring radiation background in the near-surface atmosphere and gamma rays, geoacoustic emission, and temperature in a borehole at 40 m depth, as well as Doppler sounding on a low-inclined radio pass, proceeded at the Tien Shan mountain station (3340 m a.s.l.) in northern Tien Shan with the common goal of searching for seismogenic effects preceding earthquakes. The flux of gamma rays in the borehole varied negligibly between the days, and it was not influenced by precipitation. Characteristic bay-like drops of the gamma ray flux were found (2–8) days before the M5.0–M6.2 earthquakes. In an M4.2 earthquake event with a 5.3 km epicenter distance, anomalies were detected (7–10) days before the earthquake in variation of the gamma ray flux, geoacoustic emission, and temperature. Simultaneously with gamma rays, a disturbance was detected in the Doppler shift of the ionospheric signal. Similarly, ionosphere disturbances triggered by the growth of radioactivity in the near-surface atmosphere were found in a retrospective analysis of the Doppler shift data acquired after underground nuclear explosions at the Semipalatinsk testing site. This effect is considered from the viewpoint of the lithosphere-atmosphere-ionosphere coupling concept. [ABSTRACT FROM AUTHOR]

The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT. [ABSTRACT FROM AUTHOR]

An analysis is made of Earth‐surface geoelectric fields and voltages on electricity transmission power‐grids induced by a late‐phase E3 nuclear electromagnetic pulse (EMP). A hypothetical scenario is considered of an explosion of several hundred kilotons set several hundred kilometers above the eastern‐midcontinental United States. Ground‐level E3 geoelectric fields are estimated by convolving a standard parameterization of E3 geomagnetic field variation with magnetotelluric Earth‐surface impedance tensors derived from wideband measurements acquired across the study region during a recent survey. These impedance tensors are a function of subsurface three‐dimensional electrical conductivity structure. Results, presented as a movie‐map, demonstrate that localized differences in surface impedance strongly distort the amplitude, polarization, and variational phase of induced E3 geoelectric fields. Locations with a high degree of E3 geoelectric polarization tend to have high geoelectric amplitude. Uniform half‐space models and one‐dimensional, depth‐dependent models of Earth‐surface impedance, such as those widely used in government and industry reports informing power‐grid vulnerability assessment projects, do not provide accurate estimates of the E3 geoelectric hazard in complex geological settings. In particular, for the Eastern‐Midcontinent, half‐space models can lead to (order‐one) overestimates/underestimates of EMP‐induced geovoltages on parts of the power grid by as much as ±1,000 volts (a range of 2,000 volts)—comparable to the amplitudes of the geovoltages themselves. Plain Language Summary: A nuclear explosion in the near‐Earth space environment can produce an electromagnetic pulse (EMP) at the Earth's surface. A low‐frequency part of the EMP signal, known as E3 and covering periods from about a tenth of a second to a few hundred seconds, can induce geoelectric fields in the conducting solid Earth, interfering with the operation of electricity power grids. To investigate this, accurate estimates are required of the Earth's surface impedance—that is, the relationship between geomagnetic and geoelectric field variation. Surface impedance is a function of the electrical conductivity of subsurface rock structures. Using impedance tensors obtained from survey measurements, time‐dependent scenario maps are constructed of the E3 geoelectric fields and power‐grid geovoltages that would be generated by a hypothetical nuclear explosion above the United States. Over the course of the scenario, geoelectric amplitude, polarization, and variational phase are shown to differ significantly from one location to another, mostly as the result of geographic granularity in impedance. It is concluded that extremely simple impedance models, such as those widely used in government and industry reports concerned with power‐grid vulnerability assessment, do not generally provide accurate estimates of the E3 geoelectric hazard in complex geological settings. Key Points: Local differences in surface impedance distort the amplitude, polarization, and variational phase of induced E3 electromagnetic pulse (EMP) geoelectric fieldsHalf‐space models of Earth‐surface impedance do not generally provide accurate estimates of the E3 geoelectric hazard in complex geological settingsUntil a realistic treatment is made of Earth‐surface impedance, the E3 EMP hazard is not being accurately mapped [ABSTRACT FROM AUTHOR]

Isotopic ratios of radioactive xenons sampled in the subsurface and atmosphere can be used to detect underground nuclear explosions (UNEs) and civilian nuclear reactors. Disparities in the half-lives of the radioactive decay chains are principally responsible for time-dependent concentrations of xenon isotopes. Contrasting timescales, combined with modern detection capabilities, make the xenon isotopic family a desirable surrogate for UNE detection. However, without including the physical details of post-detonation cavity changes that affect radioxenon evolution and subsurface transport, a UNE is treated as an idealized system that is both closed and well mixed for estimating xenon isotopic ratios and their correlations so that the spatially dependent behavior of xenon production, cavity leakage, and transport are overlooked. In this paper, we developed a multi-compartment model with radioactive decay and interactions between compartments. The model does not require the detailed domain geometry and parameterization that is normally needed by high-fidelity computer simulations, but can represent nuclide evolution within a compartment and migration among compartments under certain conditions. The closed-form solution to all nuclides in the series 131–136 is derived using analytical singular-value decomposition. The solution is further used to express xenon ratios as functions of time and compartment position. [ABSTRACT FROM AUTHOR]

Among the most important problems for the world-wide nuclear explosion monitoring is the interference of naturally occurring and man-made radionuclides. The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) frequently detects these interferences using sensitive radionuclide measurement equipment. We commonly refer to the presence of radionuclides that are relevant to the CTBT but do not originate from a nuclear explosion as "background". Backgrounds are highest near the sources but are known to have regional and global effects on the IMS. This review paper summarizes much of the relevant work in the area of background and discusses issues of interest for nuclear explosion detection. [ABSTRACT FROM AUTHOR]

A nuclear test was done on September 3, 2017 in North Korea. This activity is regarded as a nuclear test based on both CTBTO analysis and the statement of the official North Korean news agency. The type of explosion was announced as a fusion based thermonuclear hydrogen bomb. Preliminary solution of CTBTO International Data Center (IDC) reported the origin time, epicenter coordinates and magnitude as 03:30:01 UTC, 41.3°N 129.1°E, and mb 6.1. U.S. Geological Survey (USGS) determined these parameters as 41.343°N, 129.036 °E and body wave magnitude, mb 6.3. In this study the seismograms of September 3, 2017 North Korean nuclear test recorded by the Sakarya University and Kandilli Observatory seismic stations were investigated. As we observed the first motion polarity is upwards for the explosion records but the first motion polarity is downwards for the April 14, 2014 Japan earthquake records. Also we statistically analyzed the North Korean nuclear explosions and some teleseismic earthquakes near Japan by using mb/Ms values. Linear discriminant function (LDF) was used to discriminate teleseismic events and nuclear explosions. The discrimination success percentage is 100 % in this study. [ABSTRACT FROM AUTHOR]

“Aerodynamic debris” has often been observed from explosion debris collected on the fringe of surface nuclear tests. The material forms small glassy particulates, ranging in shape from near perfectly spherical glassy beads and occasionally agglomerates of two or more particles. Producing material with a similar range of characteristics in the laboratory is quite challenging, as the temperatures required exceed 1800 K. In this paper, we describe an apparatus that can heat lofted sediment particulates very rapidly above their melting points, for seconds to minutes. Examples of the different material forms produced will be compared to real aerodynamic debris recovered from nuclear explosions described in the literature. [ABSTRACT FROM AUTHOR]

Copyright of Electrical Engineering & Electromechanics is the property of National Technical University, Kharkiv Polytechnic Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We compare the P-, S- and Lg- spectra of the 11 May, 1998 Pokhran underground nuclear explosion (NE) with those of an earthquake (EQ) of comparable magnitude that occurred in its vicinity (~100 km west) on 9 April, 2009, utilizing the waveforms recorded by a Global Seismograph Network station at Nilore (NIL), Pakistan. The contiguous occurrence of these events and the similarity of the travel paths provided a good opportunity to discriminate the nature of the sources. Our results suggest that the Pn/Lg and Pn/Sn amplitude ratios of the explosion and earthquake waveforms exhibit distinct differences in the higher frequency window. Further, since the P-phases have high signal to noise ratio compared to their S counterparts, we utilize their spectra to derive the source parameters of the NE and EQ sources. Our results show that the seismic moment, corner frequency and source dimension of the explosion are ~1.58X10 Nm, 1.18 Hz and ~0.793 km respectively. The moment magnitude (M) and surface wave magnitude (M) for the nuclear explosion are estimated to be ~5.4 and ~3.57 respectively. The values of M (5.3) and M (4.3) obtained by us for the earthquake are consistent with the estimates in the Harvard catalog and earlier published results. The estimate of M for the nuclear explosion was hitherto not available. Lastly, we estimate the yield of the NE to be ~50 kt from the surface wave magnitude and discuss the various limitations related to its estimation. [ABSTRACT FROM AUTHOR]

In the 1980s-1990s possible climatic consequences of the nuclear war were assessed in the papers by academician G.S. Golitsyn and other scientists. The assessment was based on the data of modeling of radiation and circulation processes in the atmosphere under different scenarios of ground-based and air nuclear exchange. Perhaps, underground nuclear explosions do not result in considerable climate effects associated with the emission of the large amount of aerosol to the atmosphere. However, they may cause changes in the rock structure at the big depth, in the composition of underground water as well as of liquid and gas hydrocarbons; the migration of radioactive products from the explosion melt cavity to the water and hydrocarbon layers. The incompleteness of nuclear reactions and heat emission in the melt cavity can be indirectly judged by the results of a thermal survey of the Earth surface in the epicentral zone of the explosion. It is demonstrated that a thermal anomaly is formed here, the temperature exceeds the background temperature of the Earth surface by 8-10°C. The possibility of the space monitoring of thermal anomalies using low-orbiting satellites is considered. It is shown that at cloudless weather for the typical size and temperature of thermal anomalies the flux density is about 9 × 10−2 × 10 W/cm at the space vehicle orbit in the spectral band of 8-14 μm; so, these objects can be registered. [ABSTRACT FROM AUTHOR]

Both radioxenon and radioiodine are possible indicators for a nuclear explosion. Therefore, they will be, together with other relevant radionuclides, globally monitored by the International Monitoring System in order to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty once the treaty has entered into force. This paper studies the temporal development of radioxenon and radioiodine activities with two different assumptions on fractionation during the release from an underground test. In the first case, only the noble gases are released, in the second case, radioiodine is released as well while the precursors remain underground. For the second case, the simulated curves of activity ratios are compared to prompt and delayed atmospheric radioactivity releases from underground nuclear tests at Nevada as a function of the time of atmospheric air sampling for concentration measurements of I, I and I. In addition, the effect of both fractionation cases on the isotopic activity ratios is shown in the four-isotope-plot (with Xe, Xe, Xe and Xe) that can be utilized for distinguishing nuclear explosion sources from civilian releases. [ABSTRACT FROM AUTHOR]

Abstract: The upper-mantle structure was studied from first-arrival data along the Meteorite profile, run using underground nuclear explosions. Unlike the layered, slightly inhomogeneous models in the previous works, emphasis was laid on lateral inhomogeneity at the minimum possible number of abrupt seismic boundaries. We used forward ray tracing of the traveltimes of refracted and overcritical reflected waves. The model obtained is characterized by considerable velocity variations, from 7.7 km/s in the Baikal Rift Zone to 8.0–8.45 km/s beneath the Tunguska syneclise. A layer of increased velocity (up to 8.5–8.6 km/s), 30–80 km thick, is distinguished at the base of seismic lithosphere. The depth of the layer top varies from 120 km in the northern Siberian craton to 210 km in its southeastern framing. It has been shown that, with crustal density anomalies excluded, the reduced gravity field is consistent with the upper-mantle velocity model. [Copyright &y& Elsevier]

Pollution has no limits and its local (national) effects could quickly evolve into regional, continental or worldly effects. That is why protecting the environment from the aggressive factors must be a concern for each human being on the planet and especially for those who take decisions regarding issues of this field.[3] One of the most dangerous forms of aggression over the living and non-living world is nuclear pollution, an almost perfect aggression, with a multiple and universal character, because all of the components of environment are affected: earth, water, air, life. It is the most perfidious destructive force because it destroys in a slow but certain fashion any form of life. It is invisible, without color or smell, it doesn't cause immediate pain and has no established or known limits in time. Regarding the risks briefly presented earlier, a careful survey is required, but above all, elaborate legal regulations of nuclear power production and utilization, to avoid accidents that can cause serious damage to people and to the environment. Sometimes nuclear pollution can't be avoided even though security measures are taken. The danger and also possible nuclear damages caused to the environment, persist. That is why the issue of the legal responsibility for nuclear damages arises, and also the legal responsibility of damage repairs in the field of nuclear power production and employment. [ABSTRACT FROM AUTHOR]

The use of nuclear charges to prevent dangerous space objects from impacting the Earth is considered. Emphasis is placed on of two problems: imparting momentum to small cosmic bodies (SCBs) detected at a sufficient distance from the Earth to divert their trajectory to a safe distance from the planet; disintegration of SCBs by a nuclear explosion into fragments small enough compared to the initial body so that their impact on the Earth does not lead to an accident. The energy release of nuclear charges necessary to achieve this goal is estimated. The fragmentation process is considered using as an example a hypothetical SCB of the type of the asteroid Icarus. [ABSTRACT FROM AUTHOR]

The impact of a large asteroid or a nuclear explosion in Black Sea may cause a catastrophic poisonous gas (H2S) release in the atmosphere. Some effects of this phenomenon are evaluated. The land surface area covered by the H2S cloud generated by a 1,000 m size asteroid ranges between about 5,760 km2 and 9,920 km2. This may affect between 1,400,000 and 2,470,000 people. In case of a 70 m size asteroid, the cloud covers between 105 km2 and 210 km2 and 26,000 to 52,000 people may be affected. The evaluations may be a few times underestimated for some particular wind directions. Nuclear explosions of 1 Mton and 50 Mton TNT may be assimilated to the impact by asteroids of about 33 m and 120 m diameter, respectively. The social effects of these events may be diminished if some general procedures are implemented. [ABSTRACT FROM AUTHOR]

The hydrogen sulphide rich waters of the Black Sea pose a potential danger for the surrounding land regions. The impact of an asteroid exceeding tens of metres in size or a very large nuclear explosion may cause a catastrophic poisonous gas release in the atmosphere. A 250 m size asteroid impacting the southern regions of the Black Sea is treated here as an example. Wind speed and direction play an important role in H2S cloud dynamics. At 10 m/s wind speed, the cloud margins may be seen at about 185 km from impact location in about 3 hours. The influence of the impact position on the distance travelled by hydrogen sulphide clouds is rather weak, as the seawater depth does not change significantly. The land surface area covered by the H2S cloud during the run-in ranges between about 1400 km2 and 2100 km2 and up to 120,000 people may be affected. These evaluations do not include the population of the towns on or near the seashore. [ABSTRACT FROM AUTHOR]

The history of the first test sites for nuclear and thermonuclear explosions in the USSR is described. The important role of M. A. Sadovskii in the development of scientific fundamentals and equipment for obtaining reliable comprehensive data on nuclear-explosion parameters is emphasized. The history of underwater and under- ground nuclear explosions and also underground explosions of large-scale charges of conventional high explosives is described. New research directions in geophysics and seismology based on experiments performed are discussed. Unique large-scale explosions for constructing dams, dykes, etc., are described. [ABSTRACT FROM AUTHOR]

Mechanical characteristics of rock massifs and constituent rocks in the zones of influence of underground nuclear explosions are experimentally determined. Zones with a different post-explosion structure of the rock massif and different properties of rocks are identified. [ABSTRACT FROM AUTHOR]

On the basis of fracture mechanics earthquake rupture model, the relations between source parameters and τ 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 τ 0 values of nuclear explosions have about 20 MPa, which is obviously higher than average τ 0 values of earthquakes with the same magnitude. This result can be used to discriminate nuclear explosions from earthquakes. [ABSTRACT FROM AUTHOR]

Copyright of Annals of Telecommunications is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Une explosion nucléaire exoatmosphérique crée, par les interactions photonsmatière, un champ électromagnétique impulsionnel ( iem ha). Son couplage avec les lignes aériennes du réseau d'énergie à basse tension de l' e.d.f. induit sur cellesci un parasite électrique impulsionnel, rapide et intense, susceptible de perturber, dégrader ou détruire les équipements électriques et électroniques disposés en aval. Par ailleurs, la foudre peut également engendrer, sur ces mêmes liaisons, des parasites électriques impulsionnels de caractéristiques différentes. Après un rapide exposé du problème et un rappel des spécifications prises en compte, on décrit une méthode de conception de système de protection ( s.d.p.) contre les parasites générés par l' iem ha et la foudre et injectés sur un réseau d'énergie à basse tension. Cette méthode met en æuvre des moyens de simulation mathématique sur ordinateur ( cao) et des moyens expérimentaux spécifiques. L'efficacité du sdp est évaluée et validée, des exemples de réalisations sont montrés. An exoatmospheric nuclear burst creates, by interactions photonsmatters, an electromagnetic field (electromagnetic pulse- Emp ). Its coupling with links, particularly overhead power ac supply lines of ground stations, induced a parasitic electrical pulse fast and intense, susceptible to perturb, damage or destroy down stream electrical or electronic equipments. Otherwise, the lightning can also generates, on the same links, electrical pulses with some différents characteristics. After a quick recall of the problem and specifications, the design methodology of protective devices against this pulse created by nemp and lightning, for ac power lines, is given. This method implement computed aided design ( cad) and specific experimental ways. The protection efficiency is evaluated and validated, exemples of achievements described. [ABSTRACT FROM AUTHOR]

Cet article a pour objet le calcul du courant induit sur un ensemble de lignes aériennes, situées au voisinage du sol, dans la zone source d'une explosion nucléaire et balayé par le champ électromagnétique engendré par une explosion nucléaire proche. Analytical expressions are derived for the current induced on a system of overhead lines located near the ground by an incident electromagnetic wave generated by a nuclear explosion. [ABSTRACT FROM AUTHOR]

Experimental and analytical studies were performed of the deformation and failure of cavities produced for condensed gas storage at depths of 920-1100 m in a salt massif by 15 nuclear explosions. From the results of the studies a method is proposed to preserve the volume of the cavities after explosion by producing a back pressure in them. [ABSTRACT FROM AUTHOR]

In the event of a single, low-yield nuclear detonation in a major urban area, rapidly providing adequate shelter to affected populations could save 10 000–100 000 individuals from a fatal exposure to fallout radiation. However, poorly sheltered individuals may remain at risk. Current guidance and prior studies are not consistent as to the timing and conditions under which poorly sheltered individuals should leave their shelters to evacuate or obtain better shelter. This study proposes methods to determine the optimal shelter time based on information potentially available following a nuclear detonation. For the case in which individuals move to an adequate shelter that can be reached within 15 min, individuals should stay in a poor-quality shelter for at most 30 min after the detonation. If adequate shelter is available nearby (within 5 min), then poorly sheltered individuals should immediately proceed to the better shelter. [ABSTRACT FROM AUTHOR]