Vol 121, No 5 (2017)

The main problems of the contamination of the Arctic seas by technogenic radionuclides are reviewed. The sources of contamination and assessments of their contribution to the current radiation conditions are examined. Attention is focused on the potential sources of contamination: ships decommissioned from the naval and ice-breaking fleets and nuclear vessels as well as the objects of their maintenance infrastructure (nuclear technological servicing vessels and shore-based technical facilities). The main results of the development and implementation of a strategic master plan for the comprehensive salvaging of objects of the nuclear fleet in the North-West region of the country are described. Sunken nuclear and radiation hazardous objects in the Arctic seas are examined separately. Assessments of their radiation characteristics are presented. Possible radioecological consequences of accidents and the prospects for making these objects safe are examined.

The multifunctional backup power system for the internal needs of nuclear power plants uses an added steam turbine. This approach makes it possible to increase the power capacity of NPP with water cooled reactors and at the same time maintain high safety and reliability. The reactor cools down in 72 h in the event of an accident with total blackout of NPP. The significant results of multifunctional backup are: positive economic impact, pay back of the added capital investments in the safety system, and higher technical and economic efficiency, safety, and competitiveness of NPP.

Heat removal during transient processes in nuclear power installations and bench loops cooled by lead and lead-bismuth coolant is studied. It is shown that low-pressure heat-exchange equipment is effective. The studies were conducted in a non-isothermal loop with circulating of lead coolant at 450–500°C, average speed in the narrow section of the gap in longitudinal flow over the heat-exchange surface 0.1–1.05 m/sec, Peclet number 300–3300, and the oxygen thermodynamic activity in lead 1–10^–3. The processes occurring in a non-isothermal liquid-metal loop with an experimental heat-exchange section model the dependence of the heat-exchange characteristics on impurity mass transfer in the loop.

The existing excimer lasers with pulse durations in the nanosecond range and high pulse and average power afford a unique possibility of influencing the surface of materials and developing new, efficient technologies. It is shown in this article that surface treatment with a periodic-pulse UV laser cleans surfaces by removing oxides, reduces roughness, and increases hardness. Different variants of pulsed laser deposition of aluminum and Al₂O₃ are used to form protective, composite, cermet layers that suppress surface corrosion of EP-823 steel fuel-element cladding in lead in contact with air at 650–720°C.

The conditions for the irradiation of ¹⁶⁸Yb-enriched samples in reactors for obtaining sources to be used in brachytherapy are examined. The optimum irradiation conditions in the SM-3 high-flux reactor are determined. The computational methods are compared with the measurements.

The results of a study of the electrophysical characteristics of the detector single crystals CdZnTe and CdTe obtained from the best domestic (Institute of Rare Metal Industry, Giredmet) and foreign (Acrorad (Japan) and Redlen (Canada)) producers are presented. The values of (μτ)_e in Redlen CdZnTe were 3·10^–3–2·10^–2 cm²/V. It is shown that the transport characteristics μτ of nonequilibrium charge carriers in domestic materials is 3–30 times lower than in the foreign samples. The spectrometric characteristics of the fabricated detectors were studied in the γ-ray energy range 30–662 keV using uncollimated γ-ray sources ¹³³Ba, ²⁴¹Am, ⁵⁷Co, and ¹³⁷Cs. The measured spectra of the amplitude distribution of the pulses from these sources are presented. The best energy resolution for quasi-hemispherical CdZnTe detectors in terms of the energy 662 keV ¹³⁷Cs was 1.7%. The results of these investigations are of interest for monitoring nuclear materials using compact devices with high energy resolution that do not require cooling.

The results of work on dismantling the graphite masonry and reactor structures of the RFT research reactor at the National Research Center Kurchatov Institute are presented. Remote-controlled technology and remote-sensing measurements of contamination levels were used to perform the operations of removing radioactive structures. Such methods have significantly reduced the impact of the radiation on the workers, the general public living in nearby urban areas, and the environment. The measurements of the dose rate in the masonry channels are presented and the total ¹³⁷Cs activity in the graphite is determined.