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Journal Articles

Recent status of radiochemical analysis of irradiated trans-uranium targets

Koyama, Shinichi; Osaka, Masahiko; Mitsugashira, Toshiaki

Czechoslovak Journal of Physics, 56(Suppl.D), p.D571 - D578, 2006/12

We have developed a sequential radiochemical separation method (SRCS) in order to isolate each trans-uranium element (TRU) contained in a TRU target (or fuel) irradiated in the experimental fast reactor JOYO. The chemical separation procedures for SRCS consist of the following steps. (1) Target dissolution with a 8M of HNO $_{3}$ solution including hydrogen peroxides as a valence control reagents for Pu and Np to their tetravalent states. (2) Sequential elution of main fission products (FPs) including trivalent actinides (An(III)) and lanthanides (Ln(III)) by washing the anion exchange resin column with 8M HNO $_{3}$ . (3) Elution of U(VI) from the same column with 8M HNO $_{3}$ and the change the effluent to 11.6M HCl. (4) Elution of Pu(III) from the same column by reducing Pu(IV) to Pu(III) with 11.6M HCl-0.1M NH $_{4}$ I solution. (5) Group separation for Ln(III) and An(III) by using tertiary pyridine-type anion exchange resin embedded in silica bead. (6) Mutual separation of Am(III) and Cm(III), also for each lanthanide, by anion exchange resin. For the step 5 and 6, the effluent used was 3/7(v/v) mixture of methanol and HCl and 9/1(v/v) mixture of methanol and 0.013M HNO $_{3}$ , respectively. The decontamination factor of Pu for the isolated Np was much higher than 10 $^{6}$ . The isotopic composition of isolated trans-uranium was determined mainly by thermal ionization mass spectroscopy. The SRCS sheet was applied to the analyses of MOX fuels irradiated in the experimental fast reactor JOYO. On the basis of isotope analysis, the transmutation and incineration behavior (T-I behavior) of trans-uranium nuclides were elucidated.

Journal Articles

Innovative separation method for advanced spent fuel reprocessing based on tertiary pyridine resin

Ozawa, Masaki; Koyama, Shinichi; Suzuki, Tatsuya*; Fujii, Yasuhiko*

Czechoslovak Journal of Physics, 56(Suppl.D), p.D579 - D587, 2006/12

Radiochemical separation experiments have been performed in order to realize a novel reprocessing method based on ion-exchange technique. The newly synthesized soft-donor type tertiary pyridine resin was dedicated to the experiments, where highly irradiated mixed oxide fuel from the experimental fast reactor JOYO was used as a reference spent fuel. With a 3 step separation, pure Am and Cm were individually obtained as MA products, and $^{106}$ Ru group, Lns with $^{137}$ Cs (HLLW group) and Pu group were fractionated, respectively. The decontamination factor of $^{137}$ Cs and trivalent lanthanides ( $^{155}$ Eu, $^{144}$ Ce) in the Am product exceeded 39,000 and 100,000, respectively. The decontamination factor for the mutual separation of $^{243}$ Cm and $^{241}$ Am was larger than 2200 for the Am product. Moreover, the content of $^{137}$ Cs, trivalent lanthanides and $^{243}$ Cm in Am product did not exceed 2 ppm. The tertiary pyridine resin method suggests a reality as a candidate separation system for an "advanced ORIENT process", where total separation, transmutation and utilization of An, LLFP and rare metal fission product (RMFP) were oriented.

Journal Articles

Transactinide nuclear chemistry at JAERI

Nagame, Yuichiro; Haba, Hiromitsu; Tsukada, Kazuaki; Asai, Masato; Akiyama, Kazuhiko; Hirata, Masaru; Nishinaka, Ichiro; Ichikawa, Shinichi; Nakahara, Hiromichi; Goto, Shinichi*; et al.

Czechoslovak Journal of Physics, 53, p.A299 - A304, 2003/00