[en] Submerged semiconductor α-detectors based on silicon developed for transuranium element determination in solutions of spent nuclear fuel during its radiochemical processing are described. Sensitive surface of the detectors contacts directly the analyzed solution. On the basis of protatype specimens of the detection units pilot specimens of detection units for α-radiometers (UDZhA-1K) and α-spectrometers (UDEA-1K) are manufactured. The devices are produced according to a unified design. The basic characteristics of the devices are given. Sensitivity tawards α-radiation reduced to the detector surface of 100 mm² equals (3-6)x10^-10Bq¹¹xs^-1xm³. 2 figs

[en] Semiconductor surface-barrier detectors for measuring α-radioactivity of electrically conducting liquids are described; the detectors are fabricated from single-crystal p-Si. The sensing surface of the detectors is in direct contact with the measured liquid, and the perimeter of the crystal is made vacuum-tight by welding it into a glass tube. Detectors having a sensing-surface area ranging from 0.25 to 5 cm² allow measurement of the α-activity of liquids in the 3x10^-9-3x10^-3 Ci/cm³ range

[en] Extraction equilibria are studied for aqueous (UO₂)(NO₃)₂-Pu(NO₃)₄-HNO₃ and 20% and 30% TBP in n-dodecane at 25 and 60 degrees C. Data are obtained for the stable two-phase systems. Regions near the critical point [formation of a second organic phase at high Pu(NO₃)₄ concentration] are also investigated. The behavior of Pa in the system is studied

[en] The paper describes an immersion surface-barrier ionizing radiation alpha detector using n-type monocrystalline silicon. One end of the detector is open and makes contact with the conducting solution under investigation, while the other end is sealed into a glass ampoule and connected to the source of bias voltage. In order to provide continuous measurement of solution activity, and increase sensitivity and the accuracy of measurement, silicon with a specific resistance of 100-500 ohm/cm is used. The detector works stably with a steady back bias of 1-4 V and does not require a direct bias supply with a special commuting device to restore the signal amplitude. In addition, no noticeable sorption of the α-irradiator takes place on the sensitive surface of the detector; as a result the sensitivity of the detector is 20 times as great for the same sensitive surface area. A linear dependance of the counting rate on the concentration of alph-irradiators over a wide range of concentrations is typical of the detector. For each measured concentration the counting rate hardly changes, regardless of the duration of the measurement. The detector can be used to measure concentrations of alpha irradiators and also for U, Np, Pu and Am in nitric acid solutions. (author)

[en] A one-cycle scheme for extractive reprocessing of spent breeder-reactor fuel with co-extraction of U and Pu at elevated temperature is modeled mathematically. The optimal configuration of the processing scheme with the most stable regime is found. The prospects and possibilities of automated design for reprocessing fuel with a high Pu content are demonstrated

[en] Several types of submerged Si detectors with the sensitive surface from 1 to 1000 mm² have been developed for determining remotedly specific alpha-activity of conductive aqueous solutions without preparation of dry specimens. The sensitive surface of the detectors is in a direct contact with a solution under investigation. Designs and operation parameters of several alpha detectors which are based on both n-and p-type Si are described. The measuring procedure is also described. The specific alpha activity of a solution is shown to be directly correlated to the counting rate of a detector, alpha particle energy, solution density and mean atomic number of solution constituents. The problems of matching parameters of the detectors and pulse amplifiers, radiation resource of the detectors and the effect of a β-radiation large background are also discussed. The submerged detectors allow to measure alpha-activity with accuracy of 5-20%

[en] Short note