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Sakamoto, Atsushi; Kibe, Satoshi*; Kawanobe, Kazunori*; Fujisaku, Kazuhiko*; Sano, Yuichi; Takeuchi, Masayuki; Suzuki, Hideya*; Tsubata, Yasuhiro; Ban, Yasutoshi; Matsumura, Tatsuro
JAEA-Research 2021-003, 30 Pages, 2021/06
Japan Atomic Energy Agency has been developing a solvent extraction process called SELECT to recover minor actinides (MA) from spent nuclear fuel. In the SELECT process, TDdDGA, HONTA, and ADAAM are used as the extractants for MA + Ln corecovery, MA/Ln separation and Am/Cm separation, respectively. These extractants do not contain phosphorus (P), and consist of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). In this study, in order to give beneficial information for designing flowsheet, the mass transfer coefficients of Ln between HNO solution and TDdDGA or HONTA / n-dodecane solvent were evaluated by the single drop technique. Prior to the evaluation of mass transfer coefficient, we had optimized the structure of the single drop apparatus to improve accuracy of the measurement. Based on the mass transfer coefficients obtained in HNO / TDdDGA-n-dodecane system, Ln behaviors in the counter-current extraction and back-extraction using mixer-settlers and centrifugal contactors were estimated by simple calculation, and they had a good agreement with our previous experimental results. We also confirmed the mass transfer coefficients of Ln in HNO / HONTA - n-dodecane system are under 10 m/s.
Kibe, Satoshi; Fujisaku, Kazuhiko*; Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Suzuki, Hideya; Tsubata, Yasuhiro; Matsumura, Tatsuro
JAEA-Research 2016-024, 40 Pages, 2017/02
The Japan Atomic Energy Agency has been developing some flowsheets with TDdDGA (N,N,N,Ntetradodecyldiglycolamide) extractant to recover MA (minor actinide) from raffinate. In this study, countercurrent experiments with the improved flowsheet, e.g. the addition of alcohol into the solvent for preventing the precipitation, were performed using miniature centrifugal contactors in order to compare the extraction/stripping behavior of each element with the mixer-settler type. As a result, no entrainments were observed and sufficient phase separation was achieved by centrifugal contactors without any abnormal fluid behavior, such as overflow. The extraction and stripping of Ln(III) which show the similar tendencies as MA could be achieved successfully, especially their stripping proceeded more efficiently in centrifugal contactors. This might be due to the increase in stripping rates by improving the flowsheet and to superior phase separation performance of centrifugal contactors.
Kibe, Satoshi; Fujisaku, Kazuhiko*; Ambai, Hiromu; Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Suzuki, Hideya; Tsubata, Yasuhiro; Matsumura, Tatsuro
JAEA-Research 2015-021, 40 Pages, 2016/02
The flowsheet with TDdDGA extractant has been being developed for recovering MA from PUREX raffinate. In the previous study, the yields of MA and other elements in countercurrent extraction/stripping experiments using mixer-settlers were not enough for the target and it would be due to the insufficient phase (aqueous/organic) separation. In this study, we carried out countercurrent experiments with surrogate PUREX raffinate using centrifugal contactors which had superior phase separation ability, and evaluated the extraction/stripping behavior of each element. During the operation, abnormal fluid behavior, such as overflow and entrainment, was not observed, and sufficient phase separation was achieved by centrifugal contactors. Extraction behavior of lanthanides was similar to that in mixer-settlers, but their stripping efficiencies decreased. This would be due to shorter residence time in mixing zone.
Takeda, Seiichiro; ; ; ; Kato, Toshihiro*; *; Fujisaku, Kazuhiko*
JNC TN8400 2002-007, 135 Pages, 2001/12
Corrosion performance of materials used for nuclear fuel reprocessing plant was studied for the extension of their lifetime during in-service period. Research was performed focusing on characteristics of reprocessing solution which is very important corrosion factor on environmental side. In the first stage, fundamental corrosion behavior of several kinds of candidate materials such as 304ULC, 310Nb, Ti, Ti-5Ta and Zr was investigated in pure nitric acid solution. Then corrosion performance of such materials in reprocessing environment was made cleared by means of so-called hot test which is used actual reprocessing solution under radioactive conditions. The results are summarized as follows. (1) With regards to the effects of uranium and plutonium on corrosion, high valence plutonium (Pu(Ⅵ)) accelerated the corrosion of stainless steels in nitric acid, but uranium did not affect on them. It is caused by trans-passive dissolution based on the shift of corrosion potential to the noble position. It is thought that the potential shift is caused by increase of the cathodic current on the stainless steel surface due to the reduction of Pu(Ⅵ) to Pu(IV). (2) In fission product (FP) elements, ruthenium accelerated the corrosion of stainless steel in nitric acid when its concentration was comparatively high. Other FP's did not affect on them. The corrosion potential of stainless steel shifts toward noble region by adding ruthenium in nitric acid where high corrosion rates are exhibited. It is thought that the potential shift is caused by the enhancement of cathodic reactions on metal surface due to co-existence of ruthenium in nitric acid. (3) Ti, Ti-5Ta and Zr showed excellent corrosion resistance in nitric acid with and without Plutonium and ruthenium. Especially, Ti and Ti-5Ta showed the improvement of corrosion resistance by co-existing Plutonium or ruthenium. It was explained by chemical stability of surface oxide film due to plutonium or ruthenium oxidant.
; Fujisaku, Kazuhiko*; *; ; Koyama, Tomozo
JNC TN8410 2001-013, 255 Pages, 2001/05
Mock-ups of acid recovery evaporators which are made of Ti-5% Ta alloy and Zr were tested under inactive condition for forty thousands hours to improve a corrosion resistance of acid recovery evaporator in Tokai reprocessing plant (TRP). The mock-up unit was designed and produced referring to the specification of acid recovery evaporator in TRP and the evaporation performance of the mock-up was 1/27 of TRP. A long-term durability of both evaporators was demonstrated by results of operation data, evaporation performance and corrosion resistance. The mock-up unit did not suffer from any trouble during the running test and the operation data such as temperature, flow, concentrations of nitric acid and metal ions were fairly stable within standard condition. As for the corrosion resistance, cracks and local corrosion such as intergranular attack were not observed on both evaporators after the running test, and a corrosion of weld was not selective. The average corrosion rates at measuring points were less than 0.1mm/yr, respectively, however, thickness of the Ti-5% Ta alloy evaporator was slightly reduced at all points of vapor phase region. In addition, from the result by test coupon, it is found that both materials have low susceptibility to stress corrosion cracking in this environment. The destructive inspection showed that the mechanical properties of both materials were not degraded during the running test. Finally, the total running time of the mock-up unit is much more than a maximum running time of acid recovery evaporator made of stainless steel in TRP (nearly 15,000 hours). On the basis of the test results, an excellent durability of Ti-5% Ta alloy and Zr evaporators under was successfully demonstrated throughout the mock-up test from an engineering perspective.
Fujisaku, Kazuhiko*; Ishibashi, Yuzo; Takeda, Seiichiro; ; *
PNC TN8410 98-115, 50 Pages, 1998/09
None
; ; Ishibashi, Yuzo; Takeda, Seiichiro; *; Fujisaku, Kazuhiko*; *
PNC TN8410 98-116, 147 Pages, 1998/08
None
; ; Fujisaku, Kazuhiko*; Ishibashi, Yuzo; Takeda, Seiichiro
PNC TN8410 98-060, 74 Pages, 1998/03
None
Takeuchi, Masayuki; Onose, Tsutomu*; Fujisaku, Kazuhiko*; Arai, Yoichi; Washiya, Tadahiro; Kitajima, Takafumi; Koizumi, Tsutomu
no journal, ,
no abstracts in English
Arai, Yoichi; Fujisaku, Kazuhiko*; Koizumi, Satoshi*; Takeuchi, Masayuki; Washiya, Tadahiro; Kitajima, Takafumi; Koizumi, Tsutomu
no journal, ,
no abstracts in English
Arai, Yoichi; Ogino, Hideki; Onose, Tsutomu*; Koizumi, Satoshi*; Fujisaku, Kazuhiko*; Yokoyama, Yoshitomo*
no journal, ,
no abstracts in English
Ogino, Hideki; Okamura, Nobuo; Kase, Takeshi; Nakajima, Yasuo; Fujisaku, Kazuhiko*
no journal, ,
no abstracts in English
Arai, Yoichi; Fujisaku, Kazuhiko*; Koizumi, Satoshi*; Ogino, Hideki; Hirano, Hiroyasu
no journal, ,
no abstracts in English
Sakamoto, Atsushi; Ogino, Hideki; Fujisaku, Kazuhiko*; Koizumi, Satoshi*; Hirano, Hiroyasu
no journal, ,
no abstracts in English
Kibe, Satoshi; Fujisaku, Kazuhiko*; Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Suzuki, Hideya; Tsubata, Yasuhiro; Matsumura, Tatsuro
no journal, ,
no abstracts in English