[en] A theoretical study has been made of nuclear reactivity of a set of extractors under varying profiles of uranium and plutonium concentration in transient processes (Purex processes). Using mathematical modelling, a calculation is made of the concentration profile variation with time. The calculations employed Monte Carlo method KEHO-II with the use of 16-group capture cross sections of Hansen-Rokh. The data analysis has shown that at a certain conditions of the process an increase in nuclear reactivity of a set of extractors may occur, resulting in criticality. This is also confirmed by conclusions drawn in papers of the Soviet authors. The results obtained may be used when designing extraction facilities and also for the process control

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[en] Hydrodynamic studies are presented of internal devices of steam-and-water separating drums (SD) for the RBMK-1000 reactors installed at the Leningrad-, Kursk-, and Chernobyl'skaya NPPs. The reconstruction of the SD hydraulic seal (decrease in the drain slit height by way of increasing the height of the submerged perforated sheet rim) permits, as shown by testing, to obtain, at the power unit nominal rating, the steam humidity less than 0.1%, and to increase the operative water reserve in the SD

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[en] The main tasks are considered in the scope of the Central Scientific-Research Institute for Information and Technological and Economic Studies on Nuclear Science and Technology. (TsNIIAtominform). The institute coordinates scientific research and information activity of information agencies of all the USSR organizations engaged in nuclear science and technology, excercises a centralized completion of their libraries, develops and puts into practice the most progressive methods for the information servicing. The institute is a national INIS center of the USSR. Here a system for the automatic information dissemination has been successfully elaborated and employed. Much of the institute activity is given to the estimation and analysis of information and to the determination of tendencies in the nuclear science and technology development. A conclusion is drawn to the effect that TsNIIAtominform, within 15 years of its existence, has formed as a center ensuring functioning of the system of scientific and technical information on nuclear science and technology

[en] Oxidation kinetics of pellets of uranium and plutonium mononitrides and monocarbides in oxygen and in the air is investigated. Temperature of the initial and final stages of the oxidation process is determiend. Nitrogen protoxide-oxide is the final product in all the cases. It is shown that mixed nitride uranium-plutonium fuel should be preferably oxidized in the 325-350 deg C temperature range in the air, and mixed carbide uranium-plutonium fuel - in the 350-400 deg C temperature range. The final oxidation products are (U, Pu)³O⁸ and (U,Pu)Osub(2+x). The effect of oxidation conditions on granulometric composition of powders is studied. Imposition of vibration in the process of pellet oxidation noticeably increases the yield of fine powder fractions. A mechanism of oxidation of oxygen-free ceramical fuel compositions is suggested on the base of the experimental data analysis

[en] Dosimetric characteristics of radiolyoluminescence (RLL) and electrion paramagnetic resonance (EPR) of samples of human hair and cloth used for production of protective and everyday clothes are investiagted. Optimal conditions of hair RLL detection in sodium sulphide solution and cloth in sulfuric acid solution are chosen. The EPR method has been used to investigate the formation of free radicals under ionized irradiation of cotton, woollen and synthetic cloth. Data on the dependence of RLL and EPR intensity on the sample mass and radiation dose, drop of intensity with time after irradiation are presented. These dosimetric methods are for the first time applied for dose measurement at accidental irradiation of personnel at accelerators

[en] The method of electron microscopy has been applied to investigate the effect of preliminary neutron irradiation on the OKh16N15M3B steel blistering under irradiation by 20 keV helium ions with (1-10)x10₂₁ ion/m₂ doses at the temperature below 373 K. It is shown that neutron irradiation shifts critical doses of blister formation and intense scaling towards higher doses. But after the incubation period the erosion of steel preliminary neutron irradiated grows with the increase of helium ion dose above 7x10₂₁ ion/m₂. Short-term heating of neutron irradiated samples during 15 min at 1173 K does not practically affect the beginning of intense scaling of the surface