Underground Nuclear Explosions Research Articles

Evaluating the Radiation Status of the Environment on the Underground Nuclear Explosion Site Code-Named Tavda

This paper analyzes the radiation status of environmental components on the underground nuclear explosion site codenamed Tavda, which is located in the Nizhnetavdinsky District of Tyumen Oblast. This underground nuclear explosion occurred in 1967 and was part of the Program #7 Nuclear Explosions for the National Economy; it is currently one of the sources of radiation pollution in its environment. The authors hereof present the analysis of technogenic radionuclide contamination of soils in the explosion epicenter as well as within 500 meters thereof, which analysis takes into account the horizontal and vertical migration of radionuclides, and the contamination of grassy vegetation with strontium-90 and caesium-137 (measurements were taken at 100 m intervals).We have found out that the radiation burden is essentially a function of strontium-90 content in the soil. Maximum density of strontium-90 and caesium-137 contamination is observed in deeper soil layers. Technogenic radionuclide contamination is present in naturally growing grass on the Tavda site due to a high concentration of strontium-90 with a mean specific radionuclide activity of 288.33 Bq/kg, while the maximum permissible concentration of this element in natural hay is 180 Bq/kg. The concentration of caesium-137 in collected samples was not found to be in excess of the permissible concentrations.

Geomagnetic conjugate observations of ionospheric disturbances in response to a North Korean underground nuclear explosion on 3 September 2017

Abstract. We report observations of ionospheric disturbances in response to a North Korean underground nuclear explosion (UNE) on 3 September 2017. By using data from IGS (International GNSS Service) stations and Swarm satellites, geomagnetic conjugate ionospheric disturbances were observed. The observational evidence showed that UNE-generated ionospheric disturbances propagated radially from the UNE epicenter with a velocity of ∼280 m s−1. We propose that the ionospheric disturbances are results of electrodynamic process caused by LAIC (lithosphere–atmosphere–ionosphere coupling) electric field penetration. The LAIC electric field can also be mapped to the conjugate hemispheres along the magnetic field line and consequently cause ionospheric disturbances in conjugate regions. The UNE-generated LAIC electric field penetration plays an important role in the ionospheric disturbances in the region of the nuclear test site nearby and the corresponding geomagnetic conjugate points.

Radioecological Situation in the Region of Gorizont-4 Underground Nuclear Explosion in Sakha Republic (Yakutia)

The modern radioecological situation on the site of the Gorizont-4 underground nuclear explosion and on the adjacent territories is analyzed. The maps of the exposure dose rates and concentrations of natural radionuclides (40K, 238U, 232Th) on the territory including the explosion epicenter are constructed. The modern levels of the global fallout of 137Cs, 90Sr, and 239,240Pu in the soil and plant cover and in foodstuffs were determined on the site. The current annual internal dose for the population of the Kyusyur village due to consumption of foodstuffs containing 137Cs and 90Sr was determined. It is lower by two orders of magnitude than the annual dose limit for population. The underground nuclear explosion performed in the mid-1980s did not affect significantly the radioecological situation on the adjacent territories, including the Kyusyur village.

The Refined USSR Peaceful Nuclear Explosions Database for Borovoye Geophysical Observatory

This paper shows the results of the refined locations for underground Peaceful Nuclear Explosions (PNEs). Peaceful nuclear explosions (PNEs) were made for industrial applications in the Soviet Union. This study is based on a comparison of PNEs’ parameters. These explosions were recorded by seismographic stations in Kazakhstan from 1966 to 1988. The monitoring/verification community generally utilizes PNE locations from Sultanov et al. (1999). In reality, there are errors and some PNEs are poorly located. Our locations were determined using an integrated approach encompassing published open literature sources and archive seismogram analysis from Borovoye Geophysical Observatory. Treated PNEs seismograms have been available to researchers since 2001. They became available after the cooperation between Russian and U.S. organizations. The first one was the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IDG RAS), the organization that operated the Observatory in the Soviet era. The second one was the National Nuclear Center of the Republic of Kazakhstan (NNC since 1992). The third one, from the U.S. side, was the Lamont‒Doherty Earth Observatory of Columbia University (LDEO). We present two digital seismograms of old-style seismograms from a digitized archive in ASCII format. We provide travel times for P-waves, some seismograms, and additional source parameters.

Seismic detection of strong ground motions by MW5.6 North Korean nuclear explosion

The North Korean nuclear explosion test site in Punggye-ri is located in a seismically quiescent region on a stable Precambrian basement. The 3 September 2017 MW5.6 North Korean underground nuclear explosion (UNE) test produced unprecedented strong ground motions. The peak ground accelerations might reach tens to hundreds m/s2 on the surface of the UNE test site, decaying exponentially with distance. Ten shallow events with magnitudes greater than or equal to ML2.5 and source depths less than 3 km followed the 2017 UNE for 5 months in an area with a radius of 15 km from the UNE where strong ground shaking was experienced. The largest event with MW3.7 occurred 20 days after the 2017 UNE test at shallow depths less than 3 km. Its moment tensor solution indicates a combined source behavior with comparable strengths of double-couple and compensated linear vector dipole (CLVD) components, suggesting an unusual event different from typical natural earthquakes in the Korean Peninsula. The clustered shallow seismic events appeared to have occurred in damaged media that were effectively perturbed by the strong ground motions of the UNE.

Evaluating the Importance of Barometric Pumping for Subsurface Gas Transport Near an Underground Nuclear Test Site

Core Ideas Gas transport modeling can estimate ground surface breakthrough after an underground nuclear explosion. Comparison tracer‐injection experimental and model results reveals parameter sensitivity. Barometric pumping may explain gas breakthrough following an underground nuclear explosion. Amplitude and period of barometric pressure signal are key in controlling breakthrough. An underground nuclear explosion (UNE) generates and distributes radioactive gases that can be transported to the ground surface though preexisting and explosion‐induced fractures over timescales of hours to months. If detected, the presence of short‐lived radionuclides in gas is evidence of a recent UNE. Numerical modeling can provide estimates of surface arrival times that can help inform gas monitoring strategies at suspected foreign test sites. Efforts are underway at historic US UNE sites to better understand subsurface gas‐transport processes following a UNE by geologic characterization of the near‐field damage structures, field‐scale tracer experiments, and subsurface air pressure monitoring. The development of numerical models using historical and experimental datasets from former UNE sites can improve predictions by testing conceptual models, highlighting key processes, and constraining parameter ranges. The models developed in this study represent the U20az site at the Nevada National Security Site where the Barnwell device was expended in December 1989. A two‐phase (water and air), dual‐permeability flow and transport model of the U20az site was built to investigate gas transport processes under recent experimental conditions and following the Barnwell nuclear event. Results indicate that the model can explain both the lack of arrival of radioactive gas tracers in a 2013 field experiment as well as the observed arrival of radioactive gases following the 1989 Barnwell event using barometric pressure records from the respective periods, even when additional advective processes associated with the Barnwell detonation are ignored. The results demonstrate that the character of the barometric records may be a key factor in explaining the differences in transport behavior.

ВЛИЯНИЕ ИЗМЕНЕНИЙ ГЕОЛОГИЧЕСКОЙ СРЕДЫ, ВЫЗВАННЫХ ПОДЗЕМНЫМ ЯДЕРНЫМ ВЗРЫВОМ, НА ИНДУКЦИОННЫЕ ПЕРЕХОДНЫЕ ХАРАКТЕРИСТИКИ (ПО РЕЗУЛЬТАТАМ 3D-МОДЕЛИРОВАНИЯ)

The paper presents the results of 3D modelling of transient induction responses under the medium with consequences of underground nuclear explosions (UNE). Several geoelectrical models of the consequences of explosions are considered. It is shown that the TEM method allows to determine lateral distribution of the consequences of surfactants. The vertical dimensions of the medium disturbance are determined only under certain assumptions (the shape of the fracture zone, the depth of the charge, etc.).

ТЕХНОГЕННЫЙ СЛОЙ В МЕСТАХ ПРОВЕДЕНИЯ ПОДЗЕМНЫХ ЯДЕРНЫХ ВЗРЫВОВ НА ПРИМЕРЕ СЕМИПАЛАТИНСКОГО ПОЛИГОНА

Results of seismic investigation of the underground nuclear explosions area at the Semipalatinsk test site are considered. Using refracted waves method subsurface zones of surrounding geological media disintegration were revealed. These zones are characterized by decrease of P and S waves velocity on the value of 0,5-1,5 km/s and increase of Poisson coefficient on 0,07. Estimation of the induced fracturing was done; parameter of crack density measures up to 0,45.

СОДЕРЖАНИЕ УРАНА И РАДИЯ-226 В ПОДЗЕМНЫХ РАССОЛАХ СИБИРСКОЙ ПЛАТФОРМЫ

Activities of natural radionuclides 226Ra, 238U in underground brines of Cambrian sedimentary sequence in area of “Udachnaya” kimberlite pipe (Siberian plate) are considered. Activity of radium increases with the degree of the metamorphization of the underground brines. The work is done with the help of high-resolution semiconductor gamma-spectroscopy on state assignment of IGM SB RAS and on the project No. 18-45-140020 «Features of nuclear technogenesis by the example of the object of the peaceful underground nuclear explosion «Crystal» supported by the Russian foundation for basic research.

РАСПРОСТРАНЕНИЕ ТРИТИЯ В ПОВЕРХНОСТНОЙ ВОДЕ ОБЪЕКТА МИРНОГО ПОДЗЕМНОГО ЯДЕРНОГО ВЗРЫВА «КРИСТАЛЛ» В 2018 Г.

The content of technogenic radionuclide tritium in surface water of peaceful underground nuclear explosion «Crystall» site is considered. The volumic activity of tritium in surface water of the explosion well reaches 12 Bq/l in 2018. It is 630 times less than the intervention limit of drinking water (7600 Bq/kg) according to radiation safety standards. At once it is in 5,5 times higher than the regional background level of tritium activity in river water (in the order of 2,2 Bq/l). The work is done with the help of liquid-scintillation spectrometry on state assignment of IGM SB RAS and on the project No. 18-45-140020 «Features of nuclear technogenesis by the example of the object of the peaceful underground nuclear explosion «Crystal» supported by the Russian foundation for basic research (RFBR).

Measurement of radioxenon and radioargon in air from soil with elevated uranium concentration

Among the most important indicators for an underground nuclear explosion are the radioactive xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe and the radioactive argon isotope 37Ar. In order to evaluate a detection of these nuclides in the context of a nuclear test verification regime it is crucial to have knowledge about expected background concentrations. Sub soil gas sampling was carried out on the oil shale ash waste pile in Kvarntorp, Sweden, a location with known elevated uranium content where 133Xe and 37Ar were detected in concentrations up to 120 mBq/m3 and 40 mBq/m3 respectively. These data provides one of the first times when xenon and argon were both detected in the same sub soil gas. This, and the correlations between the radionuclides, the sub soil gas contents (i.e. CO2, O2, and radon) and uranium concentration in the pile, provide very interesting information regarding the natural background and the xenon concentration levels and can most likely be used as an upper limit on what to be expected naturally occurring.

Temporal Variations of the S-Wave Attenuation Field in the Area of the Lop Nor Nuclear Test Site

The characteristics of the shear wave attenuation field in the area of the Lop Nor nuclear test site, China, are considered. Methods are used that analyze the relative level of Sn and Pn waves (parameter Sn/Pn) and the slope of P-coda envelopes. An Sn wave is formed by shear waves reflected from multiple boundaries in the upper mantle, while P-coda is formed by S–P type conversion in the lithosphere of the source region. Twenty-six records of underground nuclear explosions (UNEs) and earthquakes obtained by station BRVK at epicentral distances of ∼1800–2000 km have been processed. It is found that from the late 1960s until the mid-1990s, the mean Sn/Pn values in the records of UNEs have substantially decreased and the slope of the P-coda envelope has increased in the area of the test site. These effects indicate an increase in S-wave attenuation in the lithosphere of the source region. A decrease in Sn/Pn with time in earthquake records for the test site region has also been observed after the termination of UNE series. Similar results were obtained earlier for the areas of the Semipalatinsk and Nevada nuclear test sites. The revealed effects are supposedly caused by deep fluid migration as a result of intensive long-term anthropogenic impact.

Geomagnetic Conjugate Observations of Ionospheric Disturbances in response to North Korea Underground Nuclear Explosion on 3 September 2017

<p><strong>Abstract.</strong> We report observations of ionospheric disturbances in response to North Korea underground nuclear explosion (UNE) on 3 September 2017. By using data from IGS (International GNSS Service) stations and Swarm satellite, geomagnetic conjugate ionospheric disturbances were observed. The observational evidences showed that UNE-generated ionospheric disturbances propagated radially from the UNE epicenter with the velocity of ~<span class="thinspace"></span>280<span class="thinspace"></span>m/s. We propose that the ionospheric disturbances are results of electrodynamic process caused by LAIC (Lithosphere-Atmosphere-Ionosphere Coupling) electric field penetration. LAIC electric field can also be mapped to the conjugate hemispheres along the magnetic field line and consequently cause ionospheric disturbances in conjugate regions. The UNE-generated LAIC electric field penetration plays an important role in the ionospheric disturbances in the region of the nuclear test site nearby and the corresponding geomagnetic conjugate points.</p>

The characteristic release of noble gases from an underground nuclear explosion

Prompt release of gases at the ground surface resulting from explosively propagated vents or large operational releases has typically been considered to be the only mode of transport for detonation gases from an underground nuclear explosion (UNE) giving rise to detectable levels of radioxenon gases in downwind atmospheric samples captured at distances exceeding 100 km. Using a model for thermally and barometrically driven post-detonation transport across the broad surface of a simulated UNE site, we show in conjunction with the results of an atmospheric tracer-release experiment that even deep, well-contained UNEs, without prompt vents or leaks, are potentially detectable tens of kilometers downwind with current technology; distances that are significant for localizing the source of detected atmospheric signals during on-site monitoring or inspection. For a given yield, the bulk permeability of the UNE site and to a lesser extent the depth of detonation appear to be the primary source-term parameters controlling the distance of detection from the detonation point. We find for test-site bulk permeabilities exceeding 1 darcy (10−12 m2) that broad-area surface fluxes of radioxenon gas exhibit exponential dependence on permeability resulting in order-of-magnitude enhancements of surface flux for changes in permeability of only a darcy. Simulations of subsurface transport assuming a canonical detonation-depth-versus-nuclear-yield relationship generally resulted in larger atmospheric signals for shallower, lower-yield explosions allowing downwind detection at distances greater than 1000 km. Additionally, atmospheric simulations suggest that the lowest atmospheric boundary layer heights, such as occur at night, produced concentrations above minimum detectable levels at the greatest distances downwind.

Optimisation of radioxenon measurement for comprehensive nuclear test-ban treaty

ABSTRACTThe international monitoring system (IMS) has been developed to verify compliance with the comprehensive nuclear test-ban treaty (CTBT) and radionuclide monitoring stations are the smoking gun for underground nuclear explosions identification. One of the main objectives of the verification regime is to improve the sensitivity of measurements providing background reduction and, as a result, decrease the minimum detectable activity (MDA) values. At this ENEA laboratory an anticoincidence system has been developed: the system is comprised of a high purity germanium (HPGe) detector surrounded by a low–background shield and two plastic scintillators able to detect coincident cosmic-ray interactions. Tests conducted with the anticoincidence system have shown a reduction of the Compton continuum that contributes to the spectrum background and the measured MDA values, compared to those obtained using the standard system, decreased for all the four radioxenon isotopes.

High‐Precision Relocation and Event Discrimination for the 3 September 2017 Underground Nuclear Explosion and Subsequent Seismic Events at the North Korean Test Site

High‐Precision Relocation and Event Discrimination for the 3 September 2017 Underground Nuclear Explosion and Subsequent Seismic Events at the North Korean Test Site

Identification of Seismic Events on and near the North Korean Test Site after the Underground Nuclear Test Explosion of 3 September 2017

Identification of Seismic Events on and near the North Korean Test Site after the Underground Nuclear Test Explosion of 3 September 2017

Infrasound observations from the site of past underground nuclear explosions in North Korea

Infrasound observations from the site of past underground nuclear explosions in North Korea

Remote sensing volatile elements for new signatures from underground nuclear explosions

The detection of radioactive noble gas isotopes is one of the key tools in detecting underground nuclear explosions, but other volatile elemental species, that have historically been overlooked, may also migrate to the surface. To investigate this possibility we have been studying which elements are most readily volatilized into air from solid materials (rocks, concrete, glass, etc.) following short duration (60–120 s) spot heating spanning a wide temperature range (100–2000 °C). The widest possible range of elements (Li–U) was monitored during the experiments that produced some unexpected results with regards to the apparent atmospheric persistence of some volatile signatures long after heating had ceased and the sample had returned to room temperature. Results highlighting elemental volatility as a function of temperature from different materials will be presented along with examples illustrating the extended periods over which some elements remain detectable by real time atmospheric sampling.

Evaluation of carbon tetrafluoride as a xenon surrogate for underground gas transport

Detection of radioxenon is a critical component of underground nuclear explosion monitoring. Sulfur hexafluoride (SF6) has historically served as a Xe tracer. This work explores the use of carbon tetrafluoride (CF4) as an alternative for field tests given its general suitability as a tracer and reduced greenhouse gas potential compared to SF6. Gas Chromatography–Mass Spectrometry measurements characterized the diffusive behavior of CF4 in a 2-bulb apparatus to determine how well int approximates Xe. The measured diffusion coefficient of SF6 was 78% of that of Xe, agreeing with literature values, while CF4 diffused at 97% the rate of Xe.