Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Tonna, Ryutaro*; Sasaki, Takayuki*; Okamoto, Yoshihiro; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*
Journal of Nuclear Materials, 589, p.154862_1 - 154862_10, 2024/02
Times Cited Count：0 Percentile：0.01(Materials Science, Multidisciplinary)The dissolution behavior of FeUO
compounds formed by a high-temperature reaction of UO
with iron, a stainless-steel component of reactor structural materials, was investigated under atmospheric conditions. The compounds were prepared in an electric furnace using U
O
and FeO as starting materials, and their solid states were analyzed using X-ray diffraction, scanning electron microscopy energy dispersive X-ray spectroscopy, and X-ray absorption fine structure spectroscopy. The concentration of nuclides dissolved in water was examined by performing static leaching tests of FeUO compounds for up to three months. A redox reaction was proposed to occur between trivalent Fe and pentavalent U ions in the early stage of FeUO dissolution. It was thermodynamically deduced that the reduced divalent Fe ion was finally oxidized into a trivalent ion in the presence of dissolved oxygen, and iron hydroxide limited the solubility of Fe. Meanwhile, the concentration of hexavalent U (i.e., uranyl ion) was limited owing to the presence of secondary minerals such as metaschoepite and sodium uranate and subsequently decreased, possibly owing to sorption on Fe oxides, for example. The concentrations of multivalent ions of fission products, such as Ru and Ce, also decreased, likely for the reason above. By contrast, the concentration of soluble Cs ions did not decrease. The validity of this interpretation was supported by comparing the results with the dissolution behavior of a reference sample (Fe-free UO).
Kitagaki, Toru; Yoshida, Kenta*; Liu, P.*; Shobu, Takahisa
npj Materials Degradation (Internet), 6(1), p.13_1 - 13_8, 2022/02
Times Cited Count：1 Percentile：12.40(Materials Science, Multidisciplinary) to obtain the high U solutionSano, Yuichi; ; Sakurai, Koji*; ; Nomura, Kazunori;
JNC TN8400 2000-032, 98 Pages, 2000/12
JNC-TN8400-2000-032.pdf:1.94MB
Concerning the preparation of high U solution for the crystallization process and the application of UO powder dissolution to that, the effects of final U concentration, dissolution temperature, nitric acid concentration and powder size on the dissolution of UO powder in the nitric acid where the final U concentration was 
800g/L were investigated. The experimental results showed that the solubility of UO decreased with the increase of final UO concentration and powder size, and with the decrease of dissolution temperature and nitric acid concentration. It was also confirmed that in the condition where the final U concentration was sufficiently lower than the solubility of U, UO dissolution behavior in the high U solution could be estimated with the equation based on the fragmentation model which we had already reported. Based on these experimental results, the dissolution behavior of irradiated MOX fuel in high U solution was estimated and the possibility of supplying high U solution to the crystallization process was discussed. In the preparation of high U solution for the crystallization process, it was estimated that the present dissolution process (dissolution for fuel pieces of about 3cm long) needed a lot of time to obtain a high dissolution yield, but it was shorted drastically by the pulverization of fuel pieces. The burst of off-gas at the early in the dissolution of fuel powder seems to be avoidable with setting the appropriate dissolution condition, and it is important to optimize the dissolution condition with considering the capacity of off-gas treatment process.
Sano, Yuichi; Koyama, Tomozo; Funasaka, Hideyuki
JNC TN8400 2000-014, 78 Pages, 2000/03
JNC-TN8400-2000-014.pdf:2.13MB
We investigated the factors which affected the dissolution of U and Pu to the nitric acid solution with the fragmentation model, which was based on the results of dissolution experiments for the irradiated fast reactor fuels in the Chemical Processing Facility(CPF). The equation that gave the fuel dissolution rate was estimated with the condition of fabrication (Pu ratio (Pu/(U+Pu))), irradiation (burn-up) and dissolution (nitric acid concentration, solution temperature and U+Pu concentration) by evaluating these effects quantitatively. We also investigated the effects of fuel volume ratio to the solution in the dissolver, burn-up and flouring ratio of the fuel on the f-value (the parameter which shows the diffusion and osmosis of nitric acid to the fuel) in the fragmentation model. It was confirmed that the fuel dissolution rate calculated with this equation had better agreement with the results of dissolution experiments for the irradiated fast reactor fuels in the CPF than that estimated with the surface area model. In addition, the efficiency of this equation was recognized for the dissolution of unirradiated U pellet and high Pu enriched MOX fuel. It was shown that the dissolution rate of the fuel slowed down at the condition of the high U-Pu concentration dissolution by the calculation of the dissolution behavior with this equation. The dissolution of the fuel can be improved by increasing the nitric acid concentration and temperature, but from the viewpoint of lowering the corrosion of the dissolver materials, it is desirable that the f-value is increased by optimizing the condition of shearing and stirring for the improvement of dissolution.
JAERI-M 91-010, 187 Pages, 1991/02
no abstracts in English
Adachi, Takeo; ; ; ; ; Takeishi, Hideyo; Gunji, Katsubumi; Kimura, Takaumi; ; Nakahara, Yoshinori; et al.
Journal of Nuclear Materials, 174, p.60 - 71, 1990/00
Times Cited Count：40 Percentile：94.48(Materials Science, Multidisciplinary)no abstracts in English
Kitagaki, Toru; Yoshida, Kenta*; Suzuki, Tatsuya*
no journal, ,
In order to estimate the physical/chemical properties of the fuel debris remaining in 1F, it is important to estimate the environmental conditions in 1F, such as temperature or oxygen potential during Molten Core-Concrete Interaction (MCCI) in the molten pools. To this end, this study focuses on the degradation behavior of zircon minerals in different solution conditions were investigated. The SEM results indicate that needle-like crystals were formed on the zircon surface as a secondary product only when the mineral was soaked in aqueous NaOH. The relevant crystal structure was further confirmed with TEM.
-SUS system prepared by irradiation or tracer doping methodSasaki, Takayuki*; Tonna, Ryutaro*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Kumagai, Yuta; Kusaka, Ryoji; Watanabe, Masayuki
no journal, ,
Matsumura, Tatsuro; Ishii, Sho*; Suzuki, Akihiro*
no journal, ,
no abstracts in English
Matsumura, Tatsuro; Ishii, Sho*; Suzuki, Akihiro*
no journal, ,
no abstracts in English
Matsumura, Tatsuro; Suzuki, Akihiro*
no journal, ,
no abstracts in English
