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JAEA Reports

Production of the minor actinide sources using the electrodeposition method

Nakamura, Satoshi; Kimura, Takahiro; Ban, Yasutoshi; Tsubata, Yasuhiro; Matsumura, Tatsuro

JAEA-Technology 2020-009, 22 Pages, 2020/08

JAEA-Technology-2020-009.pdf:2.92MB

Partitioning and transmutation technology division is planning to measure fission rate ratios that contribute to validate nuclear data of minor actinides (MA). For this purpose, MA sources for fission chambers were prepared using electrodeposition method. The radioactivity of each MA source was quantified, and its uncertainty was evaluated. Seven types of MA sources with different radioactivity were prepared using four nuclides of $$^{237}$$Np, $$^{241}$$Am, $$^{243}$$Am, and $$^{244}$$Cm. A $$^{244}$$Cm source solution of which radioactivity was quantified by isotope dilution method was used to prepare working standard sources of $$^{244}$$Cm. The radioactivities were quantified as 1461 Bq, 2179 Bq, and 2938 Bq for $$^{237}$$Np sources, 1.428 MBq for $$^{241}$$Am source, 370.5 kBq and 89.57 kBq for $$^{243}$$Am sources, and 2.327 MBq for $$^{244}$$Cm source with, the uncertainty of 0.35% (1$$sigma$$). This report summarizes the method for preparation and quantification of MA sources, and uncertainty evaluation.

Journal Articles

Effects of diluents on the separation of minor actinides from lanthanides with tetradodecyl-1,10-phenanthroline-2,9-diamide from nitric acid medium

Tsutsui, Nao; Ban, Yasutoshi; Suzuki, Hideya*; Nakase, Masahiko*; Ito, Sayumi*; Inaba, Yusuke*; Matsumura, Tatsuro; Takeshita, Kenji*

Analytical Sciences, 36(2), p.241 - 246, 2020/02

 Times Cited Count:1 Percentile:31.22(Chemistry, Analytical)

To investigate the effective separation of actinides (Ans) from lanthanides (Lns), single-stage batch extraction experiments were performed with a novel extractant, tetradodecyl-1,10-phenanthroline-2,9-diamide (TDdPTDA) with various diluents such as 3-nitrobenzotrifluoride (F-3), nitrobenzene, and ${it n}$-dodecane for Am, Cm, and Lns. The extraction kinetics with TDdPTDA was rapid enough to perform the actual extraction flow sheet. The slopes of the distribution ratio versus TDdPTDA concentration and the distribution ratio versus nitric acid concentration were similar for F-3 and nitrobenzene systems but different from ${it n}$-dodecane system. These differences were attributed to the characteristics of the diluents. This study reveals high distribution ratios of Am (${it D}$ $$_{Am}$$) and Cm (${it D}$ $$_{Cm}$$) for TDdPTDA, with the high separation factors (${it SF}$s) of Am from Lns enough for their separation.

Journal Articles

Preliminary study on separation of Dy and Nd by multi-step extraction using TDdDGA

Sasaki, Yuji; Ban, Yasutoshi; Morita, Keisuke; Matsumiya, Masahiko*; Ono, Ryoma*; Shiroishi, Hidenobu*

Solvent Extraction Research and Development, Japan, 27(1), p.63 - 67, 2020/00

Mutual separation technique of Dy and Nd in Nd magnet is studied. Dy is more valuable than Nd, then Dy might be isolated and reused. Lanthanide elements can be extracted thoroughly by diglycolamide (DGA) extractants, we use this reagent for the recovery and isolation of Dy. Tetradodecyl-DGA (TDdDGA) has relatively high separation factors(SF) between Dy and Nd (SF=17-18) in HNO$$_{3}$$ extraction system, counter-current extraction using TDdDGA was applied for their mutual separation. From the present study, using the condition, four extraction stages, organic phase: 0.1M TDdDGA in n-dodecane, aqueous phase: 0.3M HNO$$_{3}$$, 92% Dy can be recovered with 0.7% co-extraction of Nd.

Journal Articles

Minor actinides separation by ${it N,N,N',N',N'',N''}$-hexaoctyl nitrilotriacetamide (HONTA) using mixer-settler extractors in a hot cell

Ban, Yasutoshi; Suzuki, Hideya*; Hotoku, Shinobu; Tsutsui, Nao; Tsubata, Yasuhiro; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 37(7), p.489 - 499, 2019/11

 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

A continuous counter-current experiment to separate minor actinides (MAs: Am and Cm) was performed with ${it N,N,N',N',N'',N''}$-hexaochyl nitrilotriacetamide (HONTA) as an extractant. Nitric acid of 0.08 M (mol/dm$$^{3}$$) containing MAs and rare earths (REs) recovered from high-level waste was used as the Feed, and the experiment was conducted for 14 h. The ratios of Am and Cm recovered into the MA fraction measured 94.9% and 78.9%, respectively. HONTA hardly extracted Y, La, and Eu in the Feed (99.9% for Y, 99.9% for La, and 96.7% for Eu), most of which were distributed to the RE fraction. A portion of Nd was extracted by HONTA, and consequently the ratio of Nd in the RE fraction was 83.5%. The concentrations of MAs and some REs in each stage were calculated using a simulation code, and the results are consistent with the experimental values. This code indicates that the ratios of MAs in the MA fraction and REs in the RE fraction could be $$geq$$99% by optimizing separation conditions.

Journal Articles

Design of accelerator-driven system consistent to partitioning technology

Sugawara, Takanori; Ban, Yasutoshi; Katano, Ryota; Tateno, Haruka; Nishihara, Kenji

Proceedings of International Conference on the Management of Spent Fuel from Nuclear Power Reactors 2019 (Internet), 9 Pages, 2019/06

The JAEA has proposed the double-strata strategy which will introduce a dedicated minor actinide (MA) transmutation cycle using an accelerator-driven system (ADS). In the previous study, the ideal fuel condition was supposed in the neutronics design of the ADS. For example, impurities such as rare earth (RE) nuclides which would accompany with MA, were not assumed. However, these nuclides would accompany with the ADS fuel and the capture reaction of these nuclides deteriorates the neutron economy of the ADS core. This study investigates a new fuel composition based on the SELECT (Solvent Extraction from Liquid-waste using Extractants of CHON-type for Transmutation) process proposed by JAEA. By performing the neutronics calculation of the ADS with the new fuel composition, a feasibility of the new fuel composition will be investigated.

Journal Articles

Effect of re-oxidation rate of additive cations on corrosion rate of stainless steel in boiling nitric acid solution

Irisawa, Eriko; Yamamoto, Masahiro; Kato, Chiaki; Motooka, Takafumi; Ban, Yasutoshi

Journal of Nuclear Science and Technology, 56(4), p.337 - 344, 2019/04

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Extraction of trivalent rare earths and minor actinides from nitric acid with ${it N,N,N',N'}$-tetradodecyldiglycolamide (TDdDGA) by using mixer-settler extractors in a hot cell

Ban, Yasutoshi; Suzuki, Hideya; Hotoku, Shinobu; Kawasaki, Tomohiro*; Sagawa, Hiroshi*; Tsutsui, Nao; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 37(1), p.27 - 37, 2019/00

 Times Cited Count:6 Percentile:35.76(Chemistry, Multidisciplinary)

A continuous counter-current experiment using TDdDGA was performed using mixer-settler extractors installed in a hot cell. Nitric acid containing minor actinides (MAs: Am and Cm), rare earths (REs: Y, La, Nd, and Eu), and other fission products (Sr, Cs, Zr, Mo, Ru, Rh, and Pd) was fed to the extractor. TDdDGA effectively extracted MAs and REs from the feed, while other fission products were barely extracted. The extracted MAs and REs were back-extracted by bringing them in contact with 0.02 mol/dm$$^{3}$$ nitric acid, and they were collected as the MA-RE fraction. The proportions of MA and RE in the MA-RE fraction were $$>$$ 98% and $$>$$ 86%, respectively. These results demonstrated the applicability of TDdDGA as an extractant for MAs and REs.

Journal Articles

Solvent extraction of uranium with ${it N}$,${it N}$-di(2-ethylhexyl)octanamide from nitric acid medium

Tsutsui, Nao; Ban, Yasutoshi; Sagawa, Hiroshi; Ishii, Sho; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 35(6), p.439 - 449, 2017/08

 Times Cited Count:3 Percentile:76.63(Chemistry, Multidisciplinary)

Solvent extraction of uranium from a nitric acid medium was performed with ${it N}$,${it N}$-di(2-ethylhexyl)octanamide (DEHOA) by a single-stage batch method, and the distribution ratio equation of U(VI) was derived as $${it D}_{rm U}$$ = 1.1$$[rm NO^{-}_{3}]^{1.6}_{rm aq}[{rm DEHOA}]^{2}_{rm org}$$. Furthermore, the nitric acid distribution was also evaluated, and the distribution ratio equation $${it D}_{rm H}$$ = 0.12$$[rm H^{+}]^{0.76}_{rm aq}[{rm DEHOA_{rm Free}}]_{rm H}$$ was obtained. Batch experiments to evaluate the time dependence of U(VI) extraction and the U(VI) loading capacity of DEHOA were also performed. It was revealed that U(VI) extraction by DEHOA reached an equilibrium state within a few minutes, and the loading capacity was 0.71 mol/dm$$^{3}$$ (M) when the concentrations of DEHOA and nitric acid were 1.5 and 3.0 M, respectively.

Journal Articles

Uranium and plutonium extraction by ${it N,N}$-dialkylamides using multistage mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Tsubata, Yasuhiro; Matsumura, Tatsuro

Procedia Chemistry, 21, p.156 - 161, 2016/12

 Times Cited Count:1 Percentile:25.7

A continuous counter-current experiment was carried out to demonstrate the validity of a process using ${it N,N}$-dialkylamides for recovering U and Pu. This process consisted of two cycles, and the 1st cycle and the 2nd cycle employed ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide and ${it N,N}$-di(2-ethylhexyl)butanamide as extractants, respectively. The feed solution for the 1st cycle was 5.1 mol/dm$$^{3}$$ (M) nitric acid containing 0.92 M U, 1.6 mM Pu, and 0.6 mM Np. The raffinate collected in the 1st cycle was used as the feed for the 2nd cycle. The ratios of U recovered in the U fraction and U-Pu fraction were 99.1% and 0.8%, respectively. The ratio of Pu recovered in the U-Pu fraction was 99.7%. The concentration ratio of U with respect to Pu in the U-Pu fraction was 9, and this indicated that Pu was not isolated. The decontamination factor of U with respect to Pu in the U fraction was obtained as 4.5$$times$$10$$^{5}$$. These results supported the validity of the proposed process.

Journal Articles

Evaluation of two-phase separation in ${it N}$,${it N}$-di(2-ethylhexyl)butanamide-nitric acid systems using turbidity measurements

Tsutsui, Nao; Ban, Yasutoshi; Hakamatsuka, Yasuyuki; Matsumura, Tatsuro

Separation Science and Technology, 51(6), p.961 - 967, 2016/02

 Times Cited Count:1 Percentile:92.22(Chemistry, Multidisciplinary)

Quantitative evaluation of the two-phase separation between ${it N}$,${it N}$-di(2-ethylhexyl)butanamide (DEHBA) and tri-${it n}$-butyl phosphate (TBP) diluted with ${it n}$-dodecane and uranyl nitrate solution in nitric acid medium was achieved using turbidity measurements. The turbidities of DEHBA were relatively high, particularly at high DEHBA concentrations, while that of TBP rapidly decreased irrespective of nitric acid concentration. A high concentration of DEHBA, nitric acid, and uranium increased the turbidities in the organic phase, which could be ascribed to the increase in viscosity. Distribution ratios of uranium were also measured, and it was indicated that turbidity did not have a critical effect on the distribution ratio when the turbidity was below a certain value.

Journal Articles

Distribution behavior of neptunium by extraction with ${it N,N}$-dialkylamides (DEHDMPA and DEHBA) in mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsutsui, Nao; Tsubata, Yasuhiro; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 34(1), p.37 - 47, 2016/01

 Times Cited Count:5 Percentile:74.7(Chemistry, Multidisciplinary)

The extraction properties of ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) and ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) for Np(V) and Np(VI) were studied by a batch method using various nitrate ion concentrations. The distribution ratios of Np(VI) obtained with DEHDMPA and DEHBA exceeded unity when the nitrate ion concentration was $$>$$3 mol/L. DEHDMPA and DEHBA barely extracted Np(V), and the maximum distribution ratios were 0.4 and 0.2 when DEHDMPA and DEHBA were used as extractants, respectively. A continuous counter-current experiment was performed to evaluate the behavior of Np in a process comprising two cycles. The ratio of Np recovered to the U fraction and U-Pu fraction were 63.7% and 29.1%, respectively. The behavior of Np suggested that the valence state of Np changed from Np(V) to Np(IV) or Np(VI) after the 1st experimental cycle. The recoveries of U and Pu to the U fraction stream and the U-Pu fraction stream were 99.9% and 99.8%, respectively.

Journal Articles

A Study on the application of ${it N,N}$-dialkylamides as extractants for U and Pu by continuous counter-current extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsubata, Yasuhiro; Tsutsui, Nao; Matsumura, Tatsuro

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1147 - 1152, 2015/09

Extraction properties of ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA), ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA), and some of their degradation products for the metal elements Zr, Mo, Ru, Rh, and Pd were studied using a single-stage batch method, and the results showed that the degradation products barely extracted these metal elements. Furthermore, separation performance of DEHDMPA and DEHBA for U and Pu in a continuous counter-current process was evaluated using a calculation code, and it was confirmed that the calculated values of U concentration in the U fraction and U and Pu concentrations in the U-Pu fraction were similar to those measured experimentally. These results supported the applicability of DEHDMPA and DEHBA as extractants for separation processes and the validity of the calculation code for estimating the separation performance of the process.

Journal Articles

Application of turbidity measurement for evaluation of two-phase separation in ${it N}$,${it N}$-dialkylamides-nitric acid systems

Tsutsui, Nao; Ban, Yasutoshi; Hakamatsuka, Yasuyuki; Urabe, Shunichi; Matsumura, Tatsuro

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1153 - 1157, 2015/09

${it N}$,${it N}$-Dialkylamides are promising alternative extractants to tri-${it n}$-butyl phosphate in the reprocessing of spent nuclear fuels, but the two-phase separation between their organic and aqueous phases has not been evaluated quantitatively. ${it N}$,${it N}$-Di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) in ${it n}$-dodecane were agitated with uranyl nitrate-containing nitric acid, and their turbidities and their uranium distribution ratios were measured with respect to the time for the quantitative evaluation. Increasing DEHDMPA, uranium, and nitric acid concentrations enhanced turbidities. Although turbidities decreased with respect to the time, uranium distribution ratios slightly changed, indicating the observed turbidities did not affect these uranium distribution ratios significantly. Therefore, DEHDMPA may act as suitable extractant for uranium in nitric acid from two-phase separation viewpoint, and turbidity may be an indicator for extractant performance evaluation.

Journal Articles

Extraction separation of U and Pu by ${it N,N}$-di(2-$$ethylhexyl$$)-2,2-dimethylpropanamide (DEHDMPA) and ${it N,N}$-di(2-$$ethylhexyl$$)butanamide (DEHBA) using mixer-settlers in the presence of degradation products of DEHDMPA and DEHBA

Ban, Yasutoshi; Hotoku, Shinobu; Tsubata, Yasuhiro; Tsutsui, Nao; Matsumura, Tatsuro

Solvent Extraction Research and Development, Japan, 22(1), p.47 - 55, 2015/00

Two sets of continuous counter-current experiments using mixer-setters were performed for evaluating extraction properties of ${it N,N}$-dialkylamides toward U and Pu in the presence of their degradation products. The 1st cycle employed ${it N,N}$-di(2-$$ethylhexyl$$)-2,2-dimethylpropanamide (DEHDMPA) for selective extraction of U(VI), and the 2nd cycle employed ${it N,N}$-di(2-$$ethylhexyl$$)butanamide (DEHDBA) for co-extraction of U(VI) and Pu(IV). Degradation products were added to the organic phase of each cycle. Most of U was effectively extracted by DEHDMPA, and the ratio of U recovered to the U fraction was 99.57%. DEHDMPA barely extracted Pu, and the decontamination factor of U with respect to Pu in the U fraction was 1.1 $$times$$ 10$$^{4}$$. The raffinate of the 1st cycle was used as the feed in the 2nd cycle, and the residual U and almost all Pu were effectively extracted by DEHBA. The degradation products had no detrimental effects on the two-phase separation and the operation of mixer-settlers.

Journal Articles

Spectroscopic study of Np(V) oxidation to Np(VI) in 3 mol/dm$$^{3}$$ nitric acid at elevated temperatures

Ban, Yasutoshi; Hakamatsuka, Yasuyuki; Tsutsui, Nao; Urabe, Shunichi; Hagiya, Hiromichi; Matsumura, Tatsuro

Radiochimica Acta, 102(9), p.775 - 780, 2014/09

 Times Cited Count:3 Percentile:68.08(Chemistry, Inorganic & Nuclear)

Optical absorption spectra of Np in 3 mol/dm$$^{3}$$ nitric acid at elevated temperatures were measured using an optical glass cell with a water jacket having a light path of 1 cm, and molar extinction coefficients of Np(VI), $$varepsilon$$$$_{T}$$, were obtained at various temperature. The values of $$varepsilon$$$$_{T}$$ was found to decrease with increasing the temperature, and could be described by the equation $$varepsilon$$$$_{T}$$ = -0.14${it T}$+85.5, where ${it T}$ is the temperature. Oxidation of Np(V) to Np(VI) in 3 mol/dm$$^{3}$$ nitric acid at elevated temperatures was observed using the optical glass cell. Oxidation of Np(V) proceeded as pseudo-first order with respect to Np(V) concentration. The rate equation in the temperature range of 336-362 K was obtained as follows: -d[Np(V)]$$_{t}$$/dt = 2.2$$times$$10$$^{7}$$ exp[-65$$times$$10$$^{3}$$/(${it RT}$)][Np(V)]$$_{t}$$, where ${it R}$ and [Np(V)]$$_{t}$$ indicate the gas constant and Np(V) concentration at time ${it t}$, respectively.

Journal Articles

Uranium and plutonium extraction from nitric acid by ${it N,N}$-di(2-ethylhexyl)-2,2-dimetnylpropanamide (DEHDMPA) and ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) using mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsubata, Yasuhiro; Morita, Yasuji

Solvent Extraction and Ion Exchange, 32(4), p.348 - 364, 2014/05

 Times Cited Count:5 Percentile:74.44(Chemistry, Multidisciplinary)

Extraction properties of ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) for nitric acid, U(VI), and Pu(IV) were studied, and the distribution ratio equations were derived for each chemical species. A continuous counter-current experiment was performed using mixer-settler extractors with two types of monoamides, DEHDMPA and ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA), as extractants. DEHDMPA exclusively extracted U from the feed, and the ratio of U recovered in the U fraction stream was 99.93%. Almost all Pu were extracted by DEHBA, and the recovery of Pu in the U-Pu fraction stream was 99.94%. Concentrations of U and Pu in mixer-settlers were calculated using a simulation code, which confirmed that the calculation was effective for estimating the U concentration in the U fraction stream, and the U and Pu concentrations in the U-Pu fraction stream.

Journal Articles

Recovery of U and Pu from nitric acid using ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) in mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsubata, Yasuhiro; Morita, Yasuji

Solvent Extraction and Ion Exchange, 31(6), p.590 - 603, 2013/09

 Times Cited Count:8 Percentile:61.06(Chemistry, Multidisciplinary)

The recovery of U and Pu from nitric acid using the monoamide extractant ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) in mixer-settler extractors was calculated using a simulation code, and a continuous counter-current experiment using mixer-settler extractors was performed. The flow rate, stage number, and nitric acid concentration were chosen as the parameters for the calculation, and the appropriate experimental conditions for separating U from Pu were determined. The results of the continuous counter-current experiment showed that the percentages of U and Pu extracted using 1.5 mol/dm$$^{3}$$ (M) DEHBA from 4 M nitric acid were $$>$$99.9% and 97.84%, respectively.

Journal Articles

Effects of oxidation states of Np on polarization curve of stainless steel in boiling 3M-HNO$$_{3}$$

Kato, Chiaki; Ueno, Fumiyoshi; Yamamoto, Masahiro; Ban, Yasutoshi; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

ECS Transactions, 53(21), p.45 - 55, 2013/05

 Times Cited Count:2 Percentile:17.42

Neptunium ion contained as one of the fission products in reprocessing solutions is known as a corrosion accelerator of the stainless steel. But it is not clear why remarkable acceleration of corrosion is caused by a slight amount of the Np ion in boiling nitric acid solution. Neptunium has several oxidation states in nitric acid solution. These changeable oxidation states of Np in nitric acid solution are regarded as the cause. Therefore an evaluation of the electrochemical behaviors on stainless steel in nitric acid solution related to the oxidation state of Np is required in order to understand the corrosion acceleration mechanism. A specially designed electrochemical test cell integrated with optical cell for spectroscopic analysis was used for this purpose. From results of electrochemical tests, cathodic reaction on stainless steel was activated by Np ions. Np(VI) ion made the corrosion potential shift nobler than Np(V) and nobler corrosion potential causes increasing corrosion current and accelerating corrosion of stainless steel in nitric acid solution. Np(V) was easily oxidized to Np(VI) in nitric acid solution and Np(VI) was the stable state in boiling 3M-HNO$$_{3}$$. It was considered that role of Np ions was that of mediator to accelerate corrosion due to activating cathodic reaction and re-oxidizing cycle in boiling 3M-HNO$$_{3}$$.

Journal Articles

Spectroscopic study of Pu(IV) oxidation to Pu(VI) in 3 mol/dm$$^{3}$$ nitric acid at 373 K

Ban, Yasutoshi; Morita, Yasuji

Radiochimica Acta, 100(12), p.879 - 883, 2012/12

 Times Cited Count:2 Percentile:77.87(Chemistry, Inorganic & Nuclear)

Optical absorption spectra of Pu(IV) in 3 mol/dm$$^{3}$$ (M) nitric acid at 373 K were measured using an optical quartz cell equipped with a thin-film heater. Pu(IV) was oxidized to Pu(VI) by heating at 373 K, and the concentrations of Pu(IV) and Pu(VI) gradually decreased and increased, respectively, with the heating time. The ratio of Pu(IV) oxidized to Pu(VI) was 37% at a heating time of 394 min, and no Pu(III) or Pu(V) characteristic peaks were observed throughout the experiment. The oxidation rate of Pu(IV) in 3 M nitric acid at 373 K could be described by the equation -d[Pu(IV)]$$_{t}$$/d$$t$$ =$$k_{1}^{'}$$[Pu(IV)]$$_{t}$$-$$k_{2}^{'}$$[Pu(VI)]$$_{t}$$, where [Pu(IV)]$$_{t}$$ and [Pu(VI)]$$_{t}$$ were the concentrations of Pu(IV) and Pu(VI) at a heating time of t min. The apparent rate constants for Pu(IV) oxidation ($$k_{1}^{'}$$) and Pu(VI) reduction ($$k_{2}^{'}$$) at 373 K were calculated to be 2.3$$times$$10$$^{-3}$$min$$^{-1}$$ and 3.4$$times$$10$$^{-3}$$min$$^{-1}$$, respectively.

Journal Articles

Application of ${it N,N}$-di(2-ethylhexyl)butanamide for mutual separation of U(VI) and Pu(IV) by continuous counter-current extraction with mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Morita, Yasuji

Journal of Nuclear Science and Technology, 49(6), p.588 - 594, 2012/06

 Times Cited Count:9 Percentile:34.41(Nuclear Science & Technology)

Continuous counter-current extraction using ${it N,N}$-di(2-ethylhexyl)- butanamide (DEHBA) as an extractant was performed with mixer-settler type extractors consisting of U-Pu extraction, scrub, U recovery, Pu back-extraction, and U back-extraction steps. The feed solution used in the continuous counter-current extraction was 3 mol/dm$$^{3}$$ (M) nitric acid containing U(VI), Pu(IV), and simulated fission products. More than 99.9% of U(VI) and Pu(IV) in the feed was extracted by 1.9 M DEHBA at the U-Pu extraction step. The extracted Pu(IV) was back-extracted via contact with 0.3 M nitric acid in the Pu back-extraction step, and the ratio of Pu(IV) distributed to the Pu fraction stream was $$sim$$ 82%. It was confirmed that 1.9 M DEHBA effectively recovered U(VI) in the U recovery step, and the ratio of U(VI) in the Pu fraction stream was less than 1%. The extracted U(VI) was back-extracted in the U back-extraction step, and more than 98% of U(VI) was recovered in the U fraction stream.

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