Abstract: A germanium detector measures an energy spectrum of a gamma ray flux. The detector includes a cooling layer continuous over a periphery of the columnar germanium crystal. The cooling layer reduces current leakage induced by heat, so that high energy gamma rays can be precisely detected. A combination of a plurality of germanium crystal bodies connected one another to form the germanium crystal of at least 20 cm leads to a more precise detection of high energy gamma rays. A method for determining a photonuclear reaction cross section using the germanium detector enables measurement of the energy dependence of a photonuclear reaction cross section at high resolution. The method employs a white gamma ray flux radiated to a nuclide. The germanium detector measures the spectrum of a transmission gamma ray flux transmitted through the nuclide. Peaks are specified in the obtained spectrum. An atomic nucleus can be transformed using a monochromatic gamma ray flux having an energy level corresponding to the peak.

Abstract: A method for regenerating a spent solvent generated from a nuclear fuel cycle and containing a higher hydrocarbon (n-dodecane), tributyl phosphate and degradation products thereof. The spent solvent is brought into contact with a methanol/water mixture having a water concentration of 100 to 750 g/l and the resulting mixture is subjected to phase separation to form a non-methanol/water phase and a methanol/water phase. The degradation products such as DBP in the spent solvent selectively migrate into the methanol/water phase and n-dodecane and TBP can be recovered as the non-methanol/water phase.