Natural attenuation processes control groundwater contamination in the Chernobyl exclusion zone: evidence from 35 years of radiological monitoring.

The Chernobyl Exclusion Zone (CEZ) contains the vast majority of radionuclides released by the accident in nuclear fuel particle form. We present and analyze groundwater measurements collected from the monitoring network in CEZ covering key aquifers over 35 years since the accident. These new data, together with a comprehensive analysis of historical data shows that 90Sr remains mobile in the subsurface environment, while groundwater concentrations of 137Cs, Pu isotopes and 241Am are relatively low, and are not of radiological concern. During the last two decades, 90Sr and 137Cs levels have declined or remained stable over time in the majority of monitoring locations. This is due to natural attenuation driven by gradual exhaustion of the fuel particle source, geochemical evolution of groundwater downstream from waste dumps and radionuclide retention in surface soil due to absorption and bio-cycling. Decommissioning of the cooling pond and construction of the 'New safe confinement' over Unit 4 (damaged reactor) also favored better protection of groundwater close to the Chernobyl plant site. Data from confined and unconfined aquifers, as well as rivers, evidence low radiological risks from groundwater contamination both outside the CEZ and to onsite "self-settlers". Though several groundwater contamination "hot spots" remain in the vicinity of Unit 4, "Red Forest" waste trenches and surface water bodies with contaminated bottom sediments, the findings of this study support a monitored natural attenuation approach to groundwater management in the CEZ.

Key performance indicators of Russian universities for 2015-2018: Dataset and Benchmarking Data.

This article presents a performance dataset of 93 Russian universities, collected from 2015 to 2018 and evaluated according to 24 indicators. These data were gathered from materials, published in the process of monitoring the effectiveness of higher education institutions by the Ministry of Science and Higher Education of the Russian Federation, Web of Science (citation-based research analytics tool InCites) and Scopus (citation-based research analytics tool SciVal) databases, and information from international ranking agencies QS, THE, ARWU. The dataset comprises the assessments of university performances according to the most important indicators used in socio-economic studies of comparative analysis of higher education system development levels in different countries: educational, scientific and research, international, financial and economic performance and international public recognition (university positions in leading international rankings). Evaluated universities are grouped pursuant to their missions: Federal Universities (FU), National Research Universities (NRU), Flagship Universities (FlU) and university-participants of the Russian Academic Excellence Project (Project 5-100). The indicators for the comparative analysis are aggregated by the type of activities and analyzed based on the calculation of median values and Displaced Ideal Method. The dataset can be helpful to researchers, university administration, specialists of higher education system, etc. Data processing can be executed using data mining methods, machine learning, and pattern analysis for the development of intellectual structures, applicable for university performance assessment in different educational systems. Presented data allows us to assert that the implementation of targeted support for leading Russian universities has a positive impact on the development of Russian higher education increasing its role on the international academic arena. Leading national research university-participants of the Project 5-100 had the greatest influence on increasing the competitiveness of Russian education in the world.

Multilayer corrosion-resistant material based on iron-carbon alloys.

In this study, the architecture of a multilayer metallic material of iron-carbon alloys with an internal protector was developed based on theoretical studies. The operability of the proposed architecture was experimentally verified using gravimetry and electrochemical analysis. The internal position of the protector enabled the modification of the mechanism of corrosion. The stages of corrosion of the multilayer material were revealed; the material was observed as useable until the third layer was perforated. To demonstrate the obtained results, the authors conducted a set of experiments using X-ray microscopy and scanning electron microscopy with an electron probe analysis of the chemical composition. The cost of the developed material is within the same range as widely used corrosion-resistant stainless austenite steels; and in terms of corrosion resistance, this material is comparable to palladium, molybdenum, nickel, and Hastelloy.

Measuring corrosion rate and protector effectiveness of advanced multilayer metallic materials by newly developed methods.

The paper estimates corrosion resistance of new multilayer metallic materials with internal protector against pitting. Using an electron microscope method, the mechanism of the layers' corrosive destruction has been experimentally substantiated. The authors have suggested chemical and electrochemical methods of accelerated corrosion tests allowing for determining the corrosion destruction rate. The electrochemical method reveals the limiting stage of the process and allows calculating the mass corrosion index and substantiating the choice of protector for the specific corrosive medium. The chemical method allows for quantitative assessment of the internal protector's effectiveness and for defining the multilayer/monometallic material corrosion resistance ratio.

Environmental radiation monitoring in the Chernobyl exclusion zone--history and results 25 years after.

This paper describes results of the radiation environmental monitoring performed in the Chernobyl Exclusion Zone (ChEZ) during the period following the 1986 Chernobyl Nuclear Power Plant accident. This article presents a brief overview of five comprehensive reports generated under Contract No. DE-AC09-96SR18500 (Washington Savannah River Company LLC, Subcontract No. AC55559N, SOW No. ON8778) and summarizes characteristics of the ChEZ and its post-accident status. The history of development of the radiation monitoring research in the ChEZ is described also. This paper addresses the characteristics of radiation monitoring in the ChEZ, its major goals and objectives, and changes in these goals and objectives in the course of time, depending on the tasks associated with the phase of mitigation of the ChNPP accident consequences. The results of the radiation monitoring in the ChEZ during the last 25 years are also provided.