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Journal Articles

Evaluation of thermodynamic model of Pd(II) complex formation with isosaccharinic acid

Kimuro, Shingo; Taneichi, Yayoi; Iwata, Hajime; Ishidera, Takamitsu; Kitamura, Akira; Tachi, Yukio; Tanaka, Takeru*; Hirano, Kana*; Hieda, Manami*; Miyabe, Shunsuke*; et al.

Journal of Solution Chemistry, 53(6), p.854 - 868, 2024/06

 Times Cited Count:0 Percentile:0.00(Chemistry, Physical)

Journal Articles

Solubility of FeSe$$_{2}$$(cr) at 318 K in the presence of iron

Yoshida, Yasushi*; Kitamura, Akira; Shibutani, Sanae*

Journal of Nuclear Science and Technology, 60(8), p.900 - 910, 2023/08

 Times Cited Count:0 Percentile:0.00(Nuclear Science & Technology)

Journal Articles

The Kinetics and mechanism of H$$_{2}$$O$$_{2}$$ decomposition at the U$$_{3}$$O$$_{8}$$ surface in bicarbonate solution

McGrady, J.; Kumagai, Yuta; Watanabe, Masayuki; Kirishima, Akira*; Akiyama, Daisuke*; Kitamura, Akira; Kimuro, Shingo

RSC Advances (Internet), 11(46), p.28940 - 28948, 2021/08

 Times Cited Count:5 Percentile:25.61(Chemistry, Multidisciplinary)

JAEA Reports

JAEA-TDB-RN in 2020; Update of JAEA's thermodynamic database for solubility and speciation of radionuclides for performance assessment of geological disposal of high-level and TRU wastes

Kitamura, Akira

JAEA-Data/Code 2020-020, 164 Pages, 2021/03

JAEA-Data-Code-2020-020.pdf:3.11MB
JAEA-Data-Code-2020-020-appendix(DVD-ROM).zip:0.56MB

Part of JAEA's Thermodynamic Database (JAEA-TDB) for solubility and speciation of radionuclides (JAEA-TDB-RN) for performance assessment of geological disposal of high-level radioactive and TRU wastes has been updated with subsuming the database for geochemical calculations (JAEA-TDB-GC). This report has focused to update JAEA-TDB-RN after selecting change in standard Gibbs free energy of formation ($$Delta_{rm r}$$$$G^{circ}_{rm m}$$), change in standard enthalpy change of formation ($$Delta$$$$H$$$$^{circ}$$$$_{rm m}$$), standard molar entropy ($$S^{circ}$$$$_{rm m}$$) and, heat capacity ($$C^{circ}_{rm p}$$), change in standard Gibbs free energy of reaction ($$Delta_{rm r}G^{circ}$$$$_{rm m}$$), change in standard enthalpy change of reaction ($$Delta$$$$_{rm r}$$$$H$$$$^{circ}$$$$_{rm m}$$) and standard entropy change of reaction ($$Delta_{rm r}S^{circ}_{rm m}$$) as well as logarithm of equilibrium constant (log$$_{10}$$$$K^{circ}$$) at standard state. The extent of selection of these thermodynamic data enables to evaluate solubility and speciation of radionuclides at temperatures other than 298.15 K. Furthermore, the latest thermodynamic data for iron which have been critically reviewed, selected and compiled by the Nuclear Energy Agency within Organisation for Economic Co-operation and Development (OECD/NEA) have been accepted. Most of previously selected log$$_{10}$$$$K^{circ}$$ have been refined to confirm internal consistency with JAEA-TDB-GC. Text files of the updated JAEA-TDB have been provided for geochemical calculation programs of PHREEQC and Geochemist's Workbench.

Journal Articles

Prediction of thermodynamic data for radium suitable for thermodynamic database for radioactive waste management using an electrostatic model and correlation with ionic radii among alkaline earth metals

Kitamura, Akira; Yoshida, Yasushi*

Journal of Radioanalytical and Nuclear Chemistry, 327(2), p.839 - 845, 2021/02

 Times Cited Count:3 Percentile:31.52(Chemistry, Analytical)

Thermodynamic data for radium for radioactive waste management have been predicted using an electrostatic model and correlation with the ionic radii of the alkaline earth metals. Estimation of the standard Gibbs free energy of formation and standard molar entropy of aqueous radium species and compounds has been based on such approaches as extrapolation of the thermodynamic properties of strontium and barium, and use of a model of ion pair formation. The predicted thermodynamic data for radium have been compared with previously reported values.

Journal Articles

Methodology development and determination of solubility-limiting solid phases for a performance assessment of geological disposal of high-level radioactive and TRU wastes

Kitamura, Akira; Yoshida, Yasushi*; Goto, Takahiro*; Shibutani, Sanae*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(2), p.58 - 71, 2020/12

Evaluation and estimation of solubility values are required for a performance assessment of geological disposal of high-level radioactive and TRU wastes. Selection of solubility-limiting solid phases (SSPs) that control the solubility of radionuclides is necessary for the evaluation and estimation of solubility values. The authors have developed a methodology for selection of the SSP through a calculation of saturation indices (SIs) using thermodynamic database to show a transparent procedure for the selection. Literature survey should be performed to confirm decision of the SSP from candidate SSPs which generally have larger SIs from realistic point of view for precipitation and solubility control. The authors have selected the SSPs for the elements of interest for the latest Japanese performance assessment in bentonite and cement porewaters after grouping various water compositions.

Journal Articles

Development methodology on determination of instant release fractions for generic safety assessment for direct disposal of spent nuclear fuel

Kitamura, Akira; Akahori, Kuniaki; Nagata, Masanobu*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(2), p.83 - 93, 2020/12

Direct disposal of spent nuclear fuel (SNF) in deep underground repositories (hereafter "direct disposal") is a concept that disposal canisters stored fuel assemblies dispose without reprocessing. Behavior of radionuclide release from SNF must be different from that from vitrified glass. The present study established a methodology on determination of instant release fraction (IRF) of radionuclides from SNF, which is the one of the parameters on radionuclide release based on the latest safety assessment reports in other countries, especially for IRF values proportional to a fission gas release ratio (FGR). Recommended and maximum values of FGR have been estimated using the fuel performance code FEMAXI-7 after collecting FGR values on Japanese SNFs. Furthermore, recommended and maximum values of IRF for Japanese SNFs used in a pressurized water reactor (PWR) have been estimated using the presently obtained FGR values and experimentally obtained IRF values on foreign SNFs. The recommended and maximum IRF values obtained in the present study have been compared with those of the latest safety assessment reports in other countries.

Journal Articles

Development of thermodynamic database for performance assessment of geological disposal of high-level radioactive waste and TRU waste

Kitamura, Akira

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 62(1), p.23 - 28, 2020/01

Thermodynamic databases (TDBs) for performance assessment of geological disposal of high-level waste and TRU waste have been developed to predict solubility and speciation of radionuclides in groundwater in some countries including Japan. The present manuscript briefly describes current status of development of the TDB organized by the Nuclear Energy Agency within the Organisation of Economic Co-operation and Development (OECD/NEA) and the TDBs in some countries including Japan.

Journal Articles

Thermodynamic interpretation of uranium(IV/VI) solubility in the presence of $$alpha$$-isosaccharinic acid

Kobayashi, Taishi*; Sasaki, Takayuki*; Kitamura, Akira

Journal of Chemical Thermodynamics, 138, p.151 - 158, 2019/11

 Times Cited Count:6 Percentile:23.95(Thermodynamics)

The effect of $$alpha$$-isosaccharinic acid (ISA) on the solubility and redox of tetravalent and hexavalent uranium (U(IV), U(VI)) was investigated in the hydrogen ion concentration (pH$$_{c}$$) range of 6$$sim$$13 and at total ISA concentration ([ISA]$$_{rm tot}$$) = 10$$^{-4}$$$$sim$$10$$^{-1.2}$$ mol/dm$$^{3}$$. The dependence of U(IV) solubility on pH$$_{c}$$ and [ISA]$$_{rm tot}$$ suggested the existence of U(OH)$$_{4}$$(ISA)$$_{2}$$$$^{2-}$$ as a dominant species within the investigated pH$$_{c}$$ range of 6$$sim$$12. For the U(VI)-ISA system, UO$$_{2}$$(OH)$$_{3}$$(ISA)$$_{2}$$$$^{2-}$$ was suggested as a dominant species at pH$$_{c}$$ 7$$sim$$13. The formation constants of the U(IV)-ISA and U(VI)-ISA complexes were determined by least-squares fitting of the solubility data. The solubility of U(IV) and U(VI) in the presence of ISA and its effect on the redox behavior were thermodynamically interpreted based on the obtained constants.

Journal Articles

A New approach for measuring the muon anomalous magnetic moment and electric dipole moment

Abe, Mitsushi*; Bae, S.*; Beer, G.*; Bunce, G.*; Choi, H.*; Choi, S.*; Chung, M.*; da Silva, W.*; Eidelman, S.*; Finger, M.*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(5), p.053C02_1 - 053C02_22, 2019/05

 Times Cited Count:156 Percentile:99.31(Physics, Multidisciplinary)

This paper introduces a new approach to measure the muon magnetic moment anomaly $$a_{mu}=(g-2)/2$$ and the muon electric dipole moment (EDM) $$d_{mu}$$ at the J-PARC muon facility. The goal of our experiment is to measure $$a_{mu}$$ and $$d_{mu}$$ using an independent method with a factor of 10 lower muon momentum, and a factor of 20 smaller diameter storage-ring solenoid compared with previous and ongoing muon g-2 experiments with unprecedented quality of the storage magnetic field. Additional significant differences from the present experimental method include a factor of 1000 smaller transverse emittance of the muon beam (reaccelerated thermal muon beam), its efficient vertical injection into the solenoid, and tracking each decay positron from muon decay to obtain its momentum vector. The precision goal for $$a_{mu}$$ is a statistical uncertainty of 450 parts per billion (ppb), similar to the present experimental uncertainty, and a systematic uncertainty less than 70 ppb. The goal for EDM is a sensitivity of $$1.5times10^{-21}$$ e$$cdot$$cm.

JAEA Reports

Update of JAEA-TDB; Update of thermodynamic data for zirconium and those for isosaccahrinate, tentative selection of thermodynamic data for ternary M$$^{2+}$$-UO$$_{2}$$$$^{2+}$$-CO$$_{3}$$$$^{2-}$$ system and integration with JAEA's thermodynamic database for geochemical calculations

Kitamura, Akira

JAEA-Data/Code 2018-018, 103 Pages, 2019/03

JAEA-Data-Code-2018-018.pdf:5.66MB
JAEA-Data-Code-2018-018-appendix1(DVD-ROM).zip:0.14MB
JAEA-Data-Code-2018-018-appendix2(DVD-ROM).zip:0.15MB
JAEA-Data-Code-2018-018-appendix3(DVD-ROM).zip:0.19MB

The latest available thermodynamic data were critically reviewed and the selected values were included into the JAEA-TDB for performance assessment of geological disposal of high-level radioactive and TRU wastes. This critical review specifically addressed thermodynamic data for (1) a zirconium-hydroxide system through comparison of thermodynamic data selected by the Nuclear Energy Agency within the Organisation for Economic Co-operation and Development (OECD/NEA), (2) complexation of metal ions with isosaccharinic acid based on the latest review papers. Furthermore, the author performed (3) tentative selection of thermodynamic data on ternary complexes among alkaline-earth metal, uranyl and carbonate ions, and (4) integration with the latest version of JAEA's thermodynamic database for geochemical calculations. The internal consistency of the selected data was checked by the author. Text files of the updated and integrated thermodynamic database have been prepared for geochemical calculation programs of PHREEQC and Geochemist's Workbench.

Journal Articles

Effect of ZrO$$_{2}$$ addition on water durability of FeO-Fe$$_{2}$$O$$_{3}$$-P$$_{2}$$O$$_{5}$$ glasses

Kitamura, Naoto*; Nomura, Akira*; Saito, Akira*; Kobayashi, Hidekazu; Amamoto, Ippei; Takebe, Hiromichi*

Journal of the Ceramic Society of Japan, 126(11), p.948 - 951, 2018/11

 Times Cited Count:6 Percentile:23.43(Materials Science, Ceramics)

We studied compositional dependence of water durability of Zr(IV) containing FeO-Fe$$_{2}$$O$$_{3}$$-P$$_{2}$$O$$_{5}$$ glasses systems, which can apply to immobilize nuclear waste of Zr isotope. Stabilized film with interference fringe on the surface improves better water durability after immersion tests for BaO and ZrO$$_{2}$$ coexisting glasses without fracture. On the other hand, microcrystalline ZrP$$_{2}$$O$$_{7}$$ was detected in the glass matrix when more than 1 mol% of ZrO$$_{2}$$ incorporated. The effect of impregnated ZrP$$_{2}$$O$$_{7}$$ crystal on the structure was discussed based on the phosphate structure analyzed by Raman spectra. Formation of Q$$^{1}$$ and Q$$^{0}$$ units, which contribute to water durability in the glass, are due to preferential precipitation of ZrP$$_{2}$$O$$_{7}$$ crystal.

Journal Articles

Thermodynamic data development; Solubility method and future research needs (PLENARY)

Rai, D.*; Yui, Mikazu; Kitamura, Akira

Progress in Nuclear Science and Technology (Internet), 5, p.19 - 26, 2018/11

The objectives of this presentation are (1) to describe the solubility method, (2) to list desirable criteria of the solubility method so that the reader can recognize which studies have been done in a way that yields quality information, (3) to present an example of how to use the evaluation criteria, and (4) to provide a few examples of future research needs where the solubility method is ideally suited and the other methods are unsuitable for these investigations.

Journal Articles

A Thermodynamic model for ZrO$$_{2}$$(am) solubility at 25$$^{circ}$$C in the Ca$$^{2+}$$-Na$$^{+}$$-H$$^{+}$$-Cl$$^{-}$$-OH$$^{-}$$-H$$_{2}$$O system; A Critical review

Rai, D.*; Kitamura, Akira; Altmaier, M.*; Rosso, K. M.*; Sasaki, Takayuki*; Kobayashi, Taishi*

Journal of Solution Chemistry, 47(5), p.855 - 891, 2018/05

 Times Cited Count:12 Percentile:10.04(Chemistry, Physical)

We have critically reviewed experimental data for Zr hydrolysis constant values for formation of several mononuclear and polynuclear species and a solubility product value for ZrO$$_{2}$$(am). We have determined new/revised values for the formation constants of Zr(OH)$$_{2}$$$$^{2+}$$, Zr(OH)$$_{4}$$(aq), Zr(OH)$$_{5}$$$$^{-}$$, Zr(OH)$$_{6}$$$$^{2-}$$ and Ca$$_{3}$$Zr(OH)$$_{6}$$$$^{4+}$$, and the solubility product for ZrO$$_{2}$$(am) after the critical review.

Journal Articles

Thermodynamic equilibrium constants for important isosaccharinate reactions; A Review

Rai, D.*; Kitamura, Akira

Journal of Chemical Thermodynamics, 114, p.135 - 143, 2017/11

 Times Cited Count:12 Percentile:20.78(Thermodynamics)

Isosaccharinic acid is a cellulose degradation product that can form in low-level nuclear waste repositories and is known to form strong complexes with many elements, including actinides, disposed of in these repositories. We (1) reviewed the available data for deprotonation and lactonisation constants of isosaccharinic acid, and the isosaccharinate binding constants for Ca, Fe(III), Th, U(IV), U(VI), Np(IV), Pu(IV), and Am(III), (2) summarized complexation constant values for predicting actinide behavior in geologic repositories in the presence of isosaccharinate, and (3) outlined additional studies to acquire reliable thermodynamic data where the available data are inadequate.

Journal Articles

Effect of carbonate concentration on the dissolution rates of UO$$_{2}$$ and spent fuel; A Review

Kitamura, Akira; Akahori, Kuniaki*

Advances in Materials Science for Environmental and Energy Technologies, 6, p.133 - 144, 2017/10

The Japanese geological disposal program has started researching disposal of spent nuclear fuel (SF) in deep geological strata as an alternative management option other reprocessing followed by vitrification and geological disposal of high-level radioactive waste. One of the key parameters for SF disposal other than the disposal of high-level radioactive waste is the fuel dissolution rate. Carbonate concentration in the simulated water composition with contact to SF after canister breaching in the Japanese SF disposal system is around 10$$^{-2}$$ mol dm$$^{-3}$$, which is one order of magnitude larger than those in some countries in Europe. The SF dissolution rate will be depend on carbonate concentration due to promoting oxidative dissolution of SF by formation of carbonate complexes of uranium(VI). For evaluation of reliable SF dissolution rate in the Japanese SF disposal system as an alternative management option, effect of carbonate concentration on dissolution rate of UO$$_{2}$$ and spent fuel has been reviewed.

Journal Articles

A Thermodynamic model for the solubility of HfO$$_{2}$$(am) in the aqueous K$$^{+}$$ - HCO$$_{3}$$$$^{-}$$ - CO$$_{3}$$$$^{2-}$$ - OH$$^{-}$$ - H$$_{2}$$O system

Rai, D.*; Kitamura, Akira; Rosso, K.*

Radiochimica Acta, 105(8), p.637 - 647, 2017/08

 Times Cited Count:4 Percentile:32.88(Chemistry, Inorganic & Nuclear)

Solubility of HfO$$_{2}$$(am) was determined as a function of KHCO$$_{3}$$ concentrations ranging from 0.001 mol.kg$$^{-1}$$ to 0.1 mol.kg$$^{-1}$$. The solubility of HfO$$_{2}$$(am) increased dramatically with the increase in KHCO$$_{3}$$ concentrations, indicating that Hf(IV) makes strong complexes with carbonate. Thermodynamic equilibrium constants for the formation of Hf-carbonate complexes were determined using both the Pitzer and SIT models. The dramatic increase in Hf concentrations with the increase in KHCO$$_{3}$$ concentrations can best be described by the formation of Hf(OH-)$$_{2}$$(CO$$_{3}$$)$$_{2}$$$$^{2-}$$ and Hf(CO$$_{3}$$)$$_{5}$$$$^{6-}$$. The log$$_{10}$$ K$$^{0}$$ values for the reactions [Hf$$^{4+}$$ + 2 CO$$_{3}$$$$^{2-}$$ +2 OH$$^{-}$$ $$leftrightarrow $$ Hf(OH)$$_{2}$$(CO$$_{3}$$)$$_{2}$$$$^{2-}$$] and [Hf$$^{4+}$$ + 5 CO$$_{3}$$$$^{2-}$$ $$leftrightarrow $$ Hf(CO$$_{3}$$)$$_{5}$$$$^{6-}$$], based on the SIT model, were determined to be 44.53 $$pm$$ 0.46 and 41.53 $$pm$$ 0.46, respectively.

Journal Articles

Thermodynamic model for Zr solubility in the presence of gluconic acid and isosaccharinic acid

Kobayashi, Taishi*; Teshima, Takeshi*; Sasaki, Takayuki*; Kitamura, Akira

Journal of Nuclear Science and Technology, 54(2), p.233 - 241, 2017/02

 Times Cited Count:9 Percentile:60.50(Nuclear Science & Technology)

Zr solubility in the presence of gluconic acid (GLU) and isosaccharinic acid (ISA) was investigated as a function of hydrogen ion concentration (pH$$_{rm c}$$) and the total concentration of GLU or ISA. The dependence of the increase in Zr solubility on the pH$$_{rm c}$$ and GLU concentration suggested the existence of Zr(OH)$$_{4}$$(GLU)$$_{2}$$$$^{2-}$$ in the neutral pH region and Zr(OH)$$_{4}$$(GLU)(GLU$$_{rm -H}$$)$$^{3-}$$ in the alkaline pH region above pH$$_{rm c}$$ 10 as the dominant species in the presence of 10$$^{-3}$$ - 10$$^{-1}$$ mol/dm$$^{3}$$ (M) GLU. In the presence of ISA, the dominant species Zr(OH)$$_{4}$$(ISA)$$_{2}$$$$^{2-}$$ and Zr(OH)$$_{4}$$(ISA)(ISA$$_{rm -H}$$)$$^{3-}$$ were proposed to occur in the neutral and alkaline pH regions, similar to those found in the presence of GLU. From X-ray diffraction analysis, the solubility-limiting solid phase in the presence of GLU and ISA was considered to be Zr(OH)$$_{4}$$(am). The formation constants of the Zr gluconate and isosaccharinate complexes were determined by least squares fitting analysis of the solubility data, and the obtained values were discussed in comparison with those of tetravalent actinides.

Journal Articles

Issues concerning the determination of solubility products of sparingly soluble crystalline solids; Solubility of HfO$$_{2}$$(cr)

Rai, D.*; Kitamura, Akira; Rosso, K. M.*; Sasaki, Takayuki*; Kobayashi, Taishi*

Radiochimica Acta, 104(8), p.583 - 592, 2016/08

 Times Cited Count:6 Percentile:45.30(Chemistry, Inorganic & Nuclear)

Solubility studies were conducted with HfO$$_{2}$$(cr) solid as a function of acid concentrations. These studies involved (1) using two different amounts of the solid phase, (2) acid washing the bulk solid phase, (3) preheating the solid phase to 1400 $$^{circ}$$C, and (4) heating amorphous HfO$$_{2}$$(am) suspensions to 90 $$^{circ}$$C to ascertain whether the HfO$$_{2}$$(am) converts to HfO$$_{2}$$(cr) and to determine the solubility from the oversaturation direction. Based on the results of these treatments it is concluded that the HfO$$_{2}$$(cr) contains a small fraction of less crystalline, but not amorphous, material [HfO$$_{2}$$(lcr)] and this, rather than the HfO$$_{2}$$(cr), is the solubility-controlling phase in the range of experimental variables investigated in this study. The solubility data are interpreted using both the Pitzer and SIT models. The log$$_{10}$$ of the solubility product of HfO$$_{2}$$(cr) is estimated. The observation of a small fraction of less crystalline higher solubility material is consistent with the general picture that mineral surfaces are often structurally and/or imperfect leading to a higher solubility than the bulk crystalline solid. This study stresses the urgent need, during interpretation of solubility data, of taking precautions to make certain that the observed solubility behavior for sparingly-soluble solids is assigned to the proper solid phase.

Journal Articles

Evaluation of source term parameters for spent fuel disposal in foreign countries, 1; Instant release fraction from spent fuel matrices and composition materials for fuel assemblies

Nagata, Masanobu; Chikazawa, Takahiro*; Akahori, Kuniaki*; Kitamura, Akira; Tachi, Yukio

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 23(1), p.31 - 54, 2016/06

Although spent nuclear fuel is planned to be disposed after reprocessing and vitrification of high-level radioactive waste (HLW), feasibility study on direct disposal of spent nuclear fuel (SF) has been started as an alternative option to flexibly apply change of future energy situation in Japan. Radionuclide inventories and their release behavior after breaching spent fuel container should be assessed to confirm safety of the SF disposal. However, these detailed studies have not been performed in Japan. Therefore, we investigated some foreign safety assessment reports on direct disposal of spent nuclear fuel by focusing on the source term of the fast release of radionuclides (i.e. instant release fraction; IRF) for the purpose of contributing to the safety assessment of Japanese SF disposal system. As a result of comparison between the safety assessment reports in foreign countries, although some fundamental data have been referred to the reports in common, the final source term dataset (IRF) was seen differences between countries in the result of taking into account the national circumstances (Reactor type and burnup, etc.). We also found the difference of assignment of uncertainties among the investigated reports; a report selected pessimistic values and another report selected mean values and their deviations. It is expected that these findings are useful as fundamental information for determination of the release rates for the safety assessment of Japanese SF disposal system.

173 (Records 1-20 displayed on this page)