Estimation on the Underwater Explosion Equivalent Based on the Threshold Monitoring Technique

Underwater nuclear explosions can be monitored in near real-time by the hydroacoustic network of the International Monitoring System (IMS) established by the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which could also be used to monitor underground and atmospheric nuclear explosions. The equivalent is an important parameter for the nuclear explosions’ monitoring. The traditional equivalent estimation method is to calculate the bubble pulsation period, which is difficult to obtain satisfactory results under the current conditions. In this paper, based on the passive sonar equation and the conversion process of acoustic energy parameters in the hydroacoustic station, the threshold monitoring technique used for underwater explosion equivalent estimation was studied, which was not limited to the measurement conditions and calculation results of the bubble pulsation period. Through the analysis of practical monitoring data, estimation on the underwater explosion equivalent based on the threshold monitoring technique was verified to be able to reach the accuracy upper boundary of current methods and expand the measurement range to further ocean space, along with the real-time monitoring capability of IMS hydroacoustic stations which could be estimated by this method.

HISTORICAL SEISMIC STATIONS IN USSR AND REGISTRATION UNDERGROUND NUCLEAR EXPLOSIONS

During the Cold War of the 20th century and the classification of information between the largest nuclear states the Soviet Union (USSR) and the United States of America (USA), data on the registration of nuclear explosions were not published in the reports of the Unitied Seismic Observation Service. However, underground nuclear explosions were recorded. For example, underground nuclear explosions, produced by the United States on Amchitka island, were recorded by more than 30 stations of the USSR at epicentral distances Δ ~ 8–160°. Tests at the Nevada Test Site were found especially well throughout the USSR seismic stations. As a result of processing the bulletins of registered events, checking the values with the time service, the registration parameters for the Soviet stations were destroyed. However, thanks to an employee of the laboratory 5-s of the Institute of Physics of the Earth named after O.Yu. Schmidt of the USSR Academy of Sciences Kh.D. Rubinstein is kept at the Institute for the Dynamics of Geospheres of the Russian Academy of Sciences named after Academician M.A. Sadovsky. Only after 1985 messages from some seismic stations of the former USSR began to be published in the operational reports of the Geophysical Service of the Russian Academy of Sciences. This material is intended to publish that layer of invaluable information on the registration of underground nuclear explosions, made by the United States, which has been so carefully created for decades, and has not been published anywhere at the moment.

Full Moment Tensor Solutions of U.S. Underground Nuclear Tests for Event Screening and Yield Estimation

ABSTRACT Moment tensor (MT) solutions are proving increasingly valuable in explosion monitoring, especially now that they are more routinely calculated for the unconstrained, full (six component) MT. In this study, we have calculated MTs for U.S. underground nuclear tests conducted at the Nevada National Security Site using seismic recordings primarily from the Livermore Nevada Network. We are able to determine them for 130 nuclear explosions from 1970 to 1996 for a range of yields and under a variety of material conditions, which we have supplemented with 10 additional chemical explosions at the test site. The result is an extensive database of MTs that can be used to assess the performance of important monitoring tasks such as event identification and yield determination. We test the explosion event screening on the fundamental lune of the MT eigensphere and find MT screening to be a robust discriminant between earthquakes and explosions. We then explore the estimation of moment-derived yield, in which we find that material properties are the largest contributor to differences in the estimated moment-to-yield ratio. Further research conducted on this dataset can be used to develop, test, and improve various explosion monitoring methodologies.

GAMMA-RAY BURSTS: A PERSONAL VIEW

The first observations in gamma-ray astronomy were made in the late 1960's, primarily by balloon-borne observations. In the early 1970's, gamma-ray bursts were discovered, completely by accident, by satellites looking for man-made nuclear explosions in space. The celestial nature of these events were soon confirmed by other satellites. The first large detector system designed for cosmic gamma-ray bursts observations was the BATSE instrument on the Compton Gamma-Ray Observatory. Some of the details of the instrumentation onboard ballons and satellites and the gamma-ray bursts observational properties they determined are presented.

RADIOECOLOGICAL SITUATION ON THE TERRITORY OF KARAUL VILLAGE OF ABAYSKY DISTRICT OF EAST KAZAKHSTAN REGION

As part of the research work on the topic «Development of scientific and methodological foundations for minimizing the environmental burden, medical support, social protection and health improvement of the population of environmentally unfavorable territories of the Republic of Kazakhstan», the Research Institute of Radiation Medicine and Ecology carried out radioecological studies in the Karaul village of Abay district of East Kazakhstan region. The radiation situation of Karaul village was formed in the 50s of the last century by local contamination of this settlement from nuclear explosions carried out at the Semipalatinsk Nuclear Test Site. Measurements of radiation parameters of the current environmental situation on the ground and sampling of environmental objects that carried out in the period of May 2018. The radiation parameters of the environmental situation (MED, radon concentration, alpha and beta particle flux densities, and the content of radioactive elements in environmental objects) on the territory of the village are within the established standards

A Closed-form Solution for Source-term Emission of Xenon Isotopes from Underground Nuclear Explosions

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.