[en] Neptunium distribution during back extraction from organic solution of the composition 30% TBP - diluent (n-paraffins, CCl₄) is studied. It is shown that regardless of diluent type the presence of DBPA in organic phase results in the decrease of back extraction efficiency owing to neptunium retention in organic phase in the form of dibutylphosphate complex. The saturation of organic phase with uranium (≥5g/l) increases the efficiency of back extraction due to competing ability of uranyl-nitrate to form dibutylphosphate complex. The efficiency of certain reextracting solutions for neptunium extraction from organic phase, containing DBPA, is tested. High efficiency of alkaline-peroxide and carbonate solutions is shown

[en] Data on neptunium sorption from perchloric- and nitric acid solutions on the surface of the 12Kh18N10T stainless steel are presented. It is ascertained that decrease of the value of neptunium ion sorption from nitric acid solutions with the growth of nitric acid concentration is explained by neptunium complexing with nitrate-ions. Stability constants of neptunium nitrate complexes (NpNO₃³⁺ and NpNO₃⁺), which constituted 1.96±0.16 and 0.13±0.20 respectively, are calculated

[en] All stages of the nuclear fuel cycle in France from the uranium mining up to the irradiated fuel radiochemical reprocessing are described. Special attention is paid to the cycle finite stage and the Cogema company role. All the achievements of France in developing nuclear engineering are based on the decision of the government, adopted in 1973 during the first oil crisis. The government developed a wide-scale program on constructing NPPs and NFC enterprises, which is successfully accomplished less than in 20 years. Currently the nuclear engineering become the leading industrial branch in France and the experience, accumulated in the nuclear technique area, greatly benefits the economy of the country

[en] Neptunium and plutonium coprecipitation with precipitates of dibutyl phosphates of some elements significant for radiochemical technology is studied. By the ability to coprecipitation of actinides with precipitates of dibutyl phosphates the cations may be arranged in the series Fe > Al > La > ≥ Zr ≥ Th. The composition of neptunium and plutonium mixed precipitates on the basis of iron dibutyl phosphates corresponding to the formula (Me(NO₃)₂Al₂)_n^x · FeA₃, where Me-neptunium or plutonium, A-anion of dibutyl phosphoric acid, n=1-4, is determined. Solubility of mixed precipitations in nitric acid and carbonate solutions is studied. Mixed precipitations on the basis of iron dibutyl phosphates are found to have the least solubility, their solubility being lower than that of individual compounds of dibutyl phoshates. The mechanism of formation of mixed precipitates is suggested and discussed

[en] Sorbent on a basis of aluminium oxide impregnated by silver nitrate salt was used for the ¹²⁹I capture during reprocessing of spent nuclear fuel at the RT-1 plant. Using adsorption columns decreased ¹²⁹I discharge to the level of sensitivity of analysis. Industrial service of the iodine purification system at the RT-1 plant provided support for validity of the method and reliability of the chosen apparatus for the ¹²⁹I capture

[en] The process of radiocarbon separation from irradiated aluminium nitride through the method of thermal oxidation in the oxygen flux is studies. Kinetic curves of the studied process are obtained for pellets of various diameter and thickness. After the pellets hold time in the oxygen flux during 1 hour at the temperature of 125 deg C it was possible to separate 80-90 % of the source carbon. Logarithmic dependence of the carbon separation rate from the aluminium nitride briskets on the hold time in the oxygen flux at the temperature of 1250 deg C was identified through the regression method. The process mechanism is proposed in accordance with which the solid phase ions diffuse through the oxide layer on the brickets surface and interact with oxygen. The carbon separation rate is determined through the diffusion rate, which may be impeded by microvoids inside the brickets

[en] It has been suggested to use foam compositions with film-forming substances for the increasing safety of personnel and decreasing aerosol wastes under disassembly of contaminated equipment and nuclear facility decommissioning. Application of localizing foams allows simplification of the protective coatings applying process under high radiation fields and not easily accessible places. Regularities of localizing stainless steels films formation from foams on the basis of pva and surfactant OP-10 were revealed as well as insulating properties of surfaces contaminated by fission products were estimated

No abstract available

[en] The process of aluminium nitride pelletizing for preparation of targets for ¹⁴ C production is studied. The methods for pressing aluminium nitride without additions of plasticizing agents such as paraffin and metal aluminium are investigated. It is shown that the best results are achieved during pressing the mixture of aluminium nitride (90 mass % ) and the PA-4 powder of metal aluminium (10 mass %) with following reaction sintering of the pellets produced in nitrogen atmosphere at 1000-1200 deg C for 1 hour

No abstract available