[en] In order to prepare a pure Pu(VI) solution, the oxidation of Pu(IV) to Pu(VI) by cerium(IV) was investigated with a UV-Visible spectrophotometer equipped with a 0.5 m liquid core waveguide. The degree of the oxidation of Pu(IV) was studied as function of the Ce(IV) concentration and the reaction time. The study showed that in 1 M HNO_3 solution, 1.2 × 10"-"3 M Ce(IV) can oxidize Pu(IV) with concentration of 4.3 × 10"-"5 M to Pu(VI) completely within 40 min, while 2.4 × 10"-"3 M Ce(IV) can do it within 15 min. The oxidation reaction of Pu(IV) by Ce(IV) is a first order process with respect to Pu(IV) according to the data analysis. From a thermodynamic point of view, the reaction can proceed almost completely provided that amount of the Ce(IV) is greater than stoichiometric amount. (author)

[en] A new method is developed for the determination of energy peak efficiency of 208 keV γ-ray of ²³⁷U based on ²⁴¹Pu/²³⁷U secular equilibrium. Plutonium solution was purified to remove Am with Dowex 1 × 2 anion exchange chromatography and the concentration of ²⁴¹Pu in the purified solution was determined using ²⁴²Pu isotope-dilution mass spectrometry on an inductively-coupled plasma mass spectrometry. The solution can be used as calibration source for the determination of energy peak efficiency of 208 keV γ-ray of ²³⁷U after 48 days. The method was validated for a planar HPGe detector at the 12 mm above the detector surface. The results showed that this is a simple and economic method for determining the energy peak efficiency of gamma detectors for 208 keV γ-ray of ²³⁷U. (author)

[en] The extraction behavior of Pu(III), Pu(IV), Np(IV) and Np(V) with di(chlorophenyl)-dithiophosphinic acid (DCPDTPA) in toluene from nitric acid solutions was studied systematically. In aqueous solution with high nitric acid concentration, the extraction capability (represented by distribution ratio D) for Pu and Np in different valences with DCPDTPA comes as D_Np(IV) > D_Pu(IV) > D_Np(V) > D_Pu(III). A new radiochemical procedure for Np/Pu separation based on DCPDTPA extraction was proposed and tested with simulated samples. The recoveries of Np and Pu are as high as 80 % after the whole separation procedure, with the decontamination factor of trivalent lanthanide fission product element (e.g. Eu) greater than 1.5 × 10⁴. The decontamination factor of Pu-Np is 2.0 × 103, while the decontamination factor of Np-Pu is greater than 4.8 × 10³ after additional purification. (author)

[en] The effect of China entering WTO on the food irradiation and the problem of food irradiation existed in Henan province were discussed