The safety culture in the elimination of the nuclear legacy from the defense and civil programs of the former USSR is demonstrated by the example of three different technologies for handling nuclear waste and spent nuclear fuel. These technologies have been implemented by RFNC-VNIITF together with RFNC-VNIIEF, OJSC RI, JSC NIKIET, and the National Nuclear Center of the Republic of Kazakhstan (NCC RK). The export of nuclear fuel from the NCC RK research reactors to Russia is considered. The key aspects of eliminating access to nuclear waste at the former Semipalatinsk Test Site in the interests of the non-proliferation regime are discussed. The set of activities associated with the export of the spent fuel assemblies (SFAs) of reactors AMB-100 and AMB-200 as the nuclear legacy of the first civil nuclear power facilities to the “Mayak” PA is shown. It is noted that compliance with the national laws, regulatory documents, and safety culture has made it possible to successfully perform unique technical and organizational tasks. As a result, the Republic of Kazakhstan has met all the requirements for a non-nuclear state when staging research reactor complexes under the IAEA safeguards; the Russian Federation, the Republic of Kazakhstan, and the United States have jointly eliminated the threat to non-proliferation regime at the former Semipalatinsk Test Site, the State Atomic Energy Corporation “Rosatom” has eliminated the “sluggish accident” at one of the sites of the nuclear legacy of the civil nuclear power engineering.

The article describes the characteristics of optical diagnostics of the tokamak KTM and the results of measuring the plasma parameters of the tokamak KTM obtained with their help. The measurements of the parameters of the plasma discharge were carried out as part of the work at the second stage of the physical start-up of the tokamak KTM. Based on the obtained experimental data the elemental composition of the plasma was estimated by measuring line radiation in the visible range (380–700 nm), the moment of plasma breakdown was determined and the position and shape of the plasma column was estimated.

The results are presented of a fractographic study of the fracture surface of samples of irradiated steel 0.12C18Cr10NiTi after tensile tests at temperatures of 24, 350, 450 °C. Samples for research were cut from the face of duct of spent fuel assemblies of fast neutron reactor BN-350. On the basis of a multilevel approach of physical mesomechanics, an attempt is made to explain the decrease in the ductility of steel with an increase in the temperature of mechanical tests. Based on the analysis results, it was concluded that a decrease in the ductility of steel with an increase in the test temperature may be due to quasi-uniform stress distribution in the area of localization of deformations, which was facilitated by the local increase in the porosity of the material caused by the accommodative processes of the rotary type.

The paper presents the results of a detailed analysis of seismic events in the vicinity of Lop Nor nuclear test site (PCR) and its adjacent areas. The quality of determination of main parameters of seismic events in this area (time in epicenter and event magnitude) was compared based on bulletins of Kazakhstan National Data Center (KNDC) and China Earthquake Networks Center (CENC). The presence of quarry explosions was detected from the Lop Nor test site area in KNDC seismic bulletin. Based on the space images, coal quarries were detected on the site’s territory; in these quarries ndustrial explosions of a small yield can be carried out.

The paper researched an example of a recording of the explosions at the ammunition storage facility by the monitoring stations of the Institute of Geophysical Research, which took place on 24.06.2019 near Arys town to the south of Kazakhstan. Seismic and infrasound station managed to trace the chronology of the explosions for more than 24 hours, to parameterize the sequence from more than 30 explosions. The strongest yield of the explosions based on energy class is 7,8. The results of the research of explosions’ recordings can be used during identification of the nature of the recorded events.

The paper presents the results of study of geodynamically active zones in the vicinity of “Baikal-1” Research Reactors Complex (RRC) site using methods of seismic survey (method of refracted waves), electrical survey (induced polarization) in conjunction with atmogeochemical surveys. The most active zone in the context of geodynamics was detected in the vicinity of south-western border of RRC “Baikal-1” site, where the most significant changes were established in the time of gas permeability, elastic and geoelectric parameters. Based on these parameters the efficiency of monitoring of weakly manifested geodynamic processes and the water-bearing nature of the soil was shown.

Long-period seismic event of 11.11.2018 was studied; this event is connected with the birth of a volcano near Mayotte island (Comoro islands archipelago). Using seismic records from the networks of stations of Institute of Geophysical Research, a seismic bulletin was created; kinematic and dynamic parameters of this event were studied; its localization was identified and regional magnitude on surface MLH waves was calculated. Seismic records of analog events on 02.09.2018 were found and researched. Recommendations for analysts on processing and classification of long-period monochrome tremors were proposed.

North Korea conducted underground nuclear explosions on October 9, 2006 (m_b 4.3), May 25, 2009 (m_b 4.7), February 12, 2013 (m_b 5,1), January 6, 2016 (m_b 5,1), September 9, 2016 (m_b 5,3) and September 3, 2017 (m_b 6,3). We estimated source depths for the North Korean nuclear tests using regional and teleseismic data. We found the burial depth at around 2 km for all North Korean nuclear tests using spectral nulls using pP+P/sP+P and pPn + Pn/ sPn+Pn including spectral minima (holes) of the fundamental-mode Rayleigh wave amplitude spectra. It should be noted that utilizing azimuth averaged spectra from the observations is most appropriate to estimate depth for unknown sources in the nonlinear topographic region such as the North Korean nuclear test sites. It is also noticeable to have found spectral anomalies depending on not only source effects but also the site effects. We found higher spectral nulls at the Fennoscandian Shield stations like ARCES and FINES due to the higher crustal velocity resulting in the fast P-wave arrivals with high Q and low attenuation containing high frequencies which very fit to underground nuclear detection, whereas spectral nulls at ASAR are found to be much lower because there is the Great Artesian Basin beneath the array including the low velocity zone in the upper mantle as well. These phenomena are also observed from spectral nulls due to reflection from the bottom of the 660-km Discontinuity by a deep-focus earthquake. It is also notable that the possibility of the over-burial detonation would affect MS : mb and seismic yield for the North Korean underground nuclear tests [1].

A comparative analysis of the KNET waveforms of underground nuclear explosions conducted at regional distances at the Lop Nor test site (China) in 1992–1996, as well as tectonic earthquakes with epicenters in the same area, was carried out for the purposes of seismic discrimination. The spectral ratios of the main regional phases of Sn/Pn and Lg/Pg were studied with the aim of seismic recognition of the source nature. The best discrimination parameter is the Lg/Pg spectral ratios for narrow-band filters with central frequencies of 2,5 and 5 Hz.

The paper presents information on an archive of records of nuclear explosions created at the Institute of Geophysical Research with the support of a number of foreign organizations. During recent twenty years the work has been done on scanning and digitization of historical analog records at the Institute; this allowsтto keep and use archive seismograms in research on improving theтefficiency of monitoring of nuclear tests and earthquakes.

Research and analyses of archive data conducted during the recent years have shown that tectonic and technogenic earthquakes have been occurring in the area of Semipalatinsk Test Site (STS) and its adjacent territories, which according to the maps of general seismic zoning of the Republic of Kazakhstan (2003) is considered aseismic. In order to assess the seismicity of the STS area, world seismological bulletins, data on historical seismicity from literature references were analyzed; parameters of earthquakes were clarified based on collected historical analog records, starting from 1925. It was shown that in this researched area during the period prior to 1994, long before the start of nuclear tests, rather strong local earthquakes were observed at STS. The obtained data were compared with the STS contemporary seismic regime.

The Geophysical Service of the Russian Academy of Sciences (Obninsk, Moscow Region) made it possible to process seismograms of “Mirnyy” station in Antarctica. Seismograms for the period 1961–1991 were viewed, when underground nuclear explosions were conducted at the Nevada Test Site of the United States. To calculate and construct a local travel time curve and a linear trend of the PKIKP_BC body wave travel time on the Nevada Test Site (NTS) – “Mirnyy” seismic station (MIR), 120 seismograms from Kirnos seismograph (SVKM) were selected for the period May 13, 1966 – October 18, 1991: 60 for each site Pahute and Yucca of the Nevada Test Site (NTS). The article presents local travel-time curves and linear trends of the PKIKPBC wave on the travelpath NTS – MIR. Increase in time travel with years as in travelpaths Nevada Test Site – Borovoye [14]. Dependency of arrival times of the PKIKP_BC wave on mb magnitude was detected. The obtained data can be used for comparison of results of PKIKPBC wave study from the Nevada Test Site on other stations, for examples, at “Novolazarevskaya” Antarctic station.

Using the example of recording of 5 underground nuclear explosions from 1979 to 1981 at Balapan Semipalatinsk Test Site (STS) carried out during the period, local time-travel curves and linear trends of the body wave travel time of P wave, which was recorded by peripheral points Zerenda, Vostochnyy, Chkalovo of the large-base system of a seismic array “Borovoye”, were obtained and studied. The values of the constant in obtained equations of the trend are close, which signifies high accuracy of the explosions’ recording at Balapan Test Site by the subsystem seismic arrays “Ozherel’e”.

The article presents information about the organization and arrangement of the seismic monitoring network in the Rivne NPP area, as well as the results of the analysis of interfering conditions and the influence of microarrays of various orderтon the ability to record useful signals on the network elements. The average values of the microseismic background at the checkpoints were calculated based on the records obtained using seismic sensors installed in instrument wells and on the day surface. In the course of instrumental observations, local, regional, and teleseismic events of different nature and energy levels were recorded. The vast majority of recorded earthquakes are located in Romania in the Vrancea seismic zone, in Poland, and in Southern Belarus. According to the results of seismic record processing, the intensity of shaking in the region of Rivne NPP was determined and conclusions were made regarding the necessity of changes of the initial data for the assessment of the seismic stability of the RNPP site.

The paper presents results of detailed analysis of range of magnitude MS values for teleseismic earthquakes recorded by seismic stations of Voronezh network (VMGSR) with regards to values presented in the cumulative bulletin of FRC UGS RAS and Obninsk station bulletin. Based on more than 1000 earthquakes with magnitude MS of more than 4 from different regions with epicentral distances from 100 to 1800, deviations in identification of the magnitude (ΔМ) are calculated and distribution scheme of ΔМ was created. It was established that ~90% of the magnitude values of earthquakes recorded by seismic stations of VMGSR network, do not have deviations of more than allowed errors with regards to the values in cumulative bulletin of FRC UGS RAS. At the same time, areas with deviation of magnitude values of more than allowed ones were identified with regards to the cumulative bulletin of FRC UGS RAS, both with “+” sign and “−” sign. The purposefulness of recording of errors on the value of −0.3 of magnitude MS for the earthquakes with epicenters in the vicinity of Japanese islands was shown; this increases the share of events, for which the magnitude is identified without deviations with regards to the cumulative bulletin of FRC UGS RAS.

In 1997, Institute of Geophysical Research NNC RK conducted seismic study of the Balapan site at Semipalatinsk Test Site, within the borders of which 14 underground nuclear explosions were carried out earlier. One of the tasks of the study was to develop a detection methodology in the upper part of the traces section from underground nuclear explosions as target objects during the On-site Inspection. In epicentral regions of the underground nuclear explosions with depths down to 100–120 m sites with lower velocity values were noted down to 3,0–3,5 km/s for P and 1,6–1,8 km/s for S waves; these were interpreted as slabbing occurrences. The rocks within the slabbing zones are different with increased Poisson’s ratio values up to 0.35, which is 0.07 higher than its pre-explosion values. Using pre- and post-explosion parameters of the background medium (seismic waves velocity, mountain rocks density, elastic modules) a parameter of fractures’ density was calculated within industrially changed layer. A correlation of post-explosion fracture of mountain rocks with engineering and technical parameters of underground explosions was established – a weight of nuclear charge and its laying depth.

The paper proposes a new technology using mercury-metric tomography of the borders of underground nuclear explosions induced fractures in the geological medium. Physical and mathematical modelling of the processes of halo formations of geo-chemical mercury in the medium under the impact of hot gaseous products of explosions that arise to the day surface became the theoretical basis of the algorithms of this technology.

As a result of the processing of gravimetric data from the GOSE and GRACE satellites, a global gravimetric map of the vertical gradient of gravity and a gravimetric map for the Northern Tien Shan region were obtained. In constructing the vertical gradient of gravity at the height of the satellite, the data of the gravitational gradient from the website of the European Space Agency were used. The provided gravitational gradient data formats are defined by two main subsets of files: a subset of gravitational gradients in the gradiometer reference system (GRF) and a subset of gradients in the reference system that rotates relatively to the ground reference system (TRF), in particular, in a spherical locally north-oriented reference system (LNOF). The gradients of the gravitational gradient 225 km and 255 km above the ellipsoid were calculated using GRACE-GOCE gravity gradients along the orbit as input. Satellite gravity data are used to analyze seismically active zones. As a result of studies, it was found that the epicenters of the centers of large earthquakes correlate with the location of the zones of sharp changes in the vertical gradient of gravity.

We have been studying some seismicity characteristics in the vicinity of Japanese capital, Tokyo. It was established that two pairs of ring-shaped seismicity structures at depths of 0–33 and 34–70 km have been formed here in 1976–2018. Ring-shaped structures, as in the other subduction zones form prior to large and great earthquakes. They are characterized by threshold magnitude values (Mt1 and Mt2 correspondingly) as well as big axes lengths (L and l). The first ring pair, located mainly to the south of Tokyo, intersects partly with the rupture zone of the Great Kanto earthquake of 1923 (Mw 7,9), and the second one is to the east of the city. Earlier we have found correlation dependences of parameters Mt1 and Mt2 on magnitudes Mw of the main events for the west of the Pacific. Using these dependences we estimated magnitudes of possible great earthquakes: Mw 7,9±0,1 and 8,1±0,1 for the two areas mentioned correspondingly. It is supposed that in the near years the great earthquake is most probable to the east of Tokyo, because a rate of seismo-tectonic deformation has increased sharply in the area of the ring structure during the last decade.

We have been studying some seismicity characteristics at depths down to 110 km prior to large and great earthquakes (Mw=7,0–9,0) in subduction zones of the Pacific. It was shown that prior to large events at depths of 0–40 and 42–110 km, which we called conditionally as shallow and deep ones respectively, during a few decades ring-shaped structures have been forming in three depth ranges: 0–33, 34–70 and 71–110 km. The structures are characterized by threshold magnitude values: Mt1, Mt2 and Mt3 correspondingly. We analyzed differences of Mt1 − Mt2, Mt2 − Mt3 and Mt1 − Mt3 values. It was established that parameters Mt2 − Mt3 and Mt1 − Mt3 are considerably higher for large shallow earthquakes in comparison with deep ones. Besides, we found differences of mean Mt1 − Mt2 values at the west and east of the Pacific. We believe that ring-shaped structures formation is connected with dehydration of subducting plates material and deep- seated fluid migration. The obtained data allow us to forecast depths of preparing large events using parameters of ring-shaped structures.

We have been studying some seismicity characteristics in the regions of the eastern Aegean Sea and Western Turkey. We used a method based on identification of ring-shaped seismicity structures. It was established that shallow (h=0–33 km) ring-shaped structures with threshold magnitude values of Mt in the range of 3,8–4,5 have been formed during a few decades prior to five large earthquakes (Mw=6,4–7,6) that occurred in 1995–2017. The sizes of these structures were a few times less than for intracontinental earthquakes with mechanisms of strike-slip and normal faulting types that have corresponding magnitudes. Besides that, deep (h=34–70 km) seismicity strips were identified there. It was shown that epicenters of large earthquakes are often located near areas of crossing or the closest rapprochement of shallow rings and deep strips. Shallow ring-shaped structure (Mt=4,3) was identified in the area of the sea of Marmara, where no eventswith Мw≥7,0 occurred at least since 1900. Moreover, deep seismicity strips also were displayed here. We estimated magnitude of the large event, which can prepare in the area of the ring-shaped structure. The estimate is based on earlier obtained correlation dependences of seismicity ring parameters on energy of main earthquakes with mechanisms of strike-slip type: Mw=7,3±0,1. The formation of ring-shaped structures and deep seismicity strips is supposed to be connected with processes of geological systems self-organization, which result in deep-seated fluids migration.

More than 20 years of seismological observations on the territory of the Voronezh crystal core area have shown that the territory of the region is not seismically passive. 590 seismic events of different energy classes were registered. Analysis showed that modern seismic activity has a quasi-periodic character. A graph of the frequency of earthquakes of different energy classes is constructed, which allows us to judge the seismic regime of the region.

From a geophysical point of view, gas-dynamic phenomena (GDPH) as little-known seismic sources recorded by the seismic monitoring networks along with earthquakes and industrial chemical explosions are considered. Data are presented indicating the mass distribution of GDPH in the center of the Asian continent associated with the Kuzbass and Karaganda coal basins. Usually they are considered as one of the types of completely unpredictable accidents in deep coal mines - powerful emissions of methane and rock. The short-term nature of the formation of GDPH anomalies is noted, which may open up the prospects for their forecasting during the operation of deep coal mines. The theoretical and field aspects of monitoring these small seismic sources are considered. The influence of the Earth’s strongest earthquakes on the characteristics of GDPH is shown. The phenomenon of dilatancy allows one to explain the mass occurrence of these temporary phenomena in coal basins. Official data are presented that do not contradict the considered models of the occurrence of GDPH.

The paper considers questions of application of modern methods of instrumental studies of geological environment diagnostics.