Solubility of FeSe(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

https://doi.org/10.1080/00223131.2022.2159892

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 (), change in standard enthalpy change of formation (), standard molar entropy () and, heat capacity (), change in standard Gibbs free energy of reaction (), change in standard enthalpy change of reaction () and standard entropy change of reaction () as well as logarithm of equilibrium constant (log) 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 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.

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

https://doi.org/10.3327/jnuce.27.2_58

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.

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, 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.

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

https://doi.org/10.1093/ptep/ptz030

This paper introduces a new approach to measure the muon magnetic moment anomaly and the muon electric dipole moment (EDM) at the J-PARC muon facility. The goal of our experiment is to measure and 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 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 ecm.

Effect of ZrO addition on water durability of FeO-FeO-PO 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

https://doi.org/10.2109/jcersj2.18039

We studied compositional dependence of water durability of Zr(IV) containing FeO-FeO-PO 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 coexisting glasses without fracture. On the other hand, microcrystalline ZrPO was detected in the glass matrix when more than 1 mol% of ZrO incorporated. The effect of impregnated ZrPO crystal on the structure was discussed based on the phosphate structure analyzed by Raman spectra. Formation of Q and Q units, which contribute to water durability in the glass, are due to preferential precipitation of ZrPO crystal.

A Thermodynamic model for ZrO(am) solubility at 25C in the Ca-Na-H-Cl-OH-HO 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

https://doi.org/10.1007/s10953-018-0766-4

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(am). We have determined new/revised values for the formation constants of Zr(OH), Zr(OH)(aq), Zr(OH), Zr(OH) and CaZr(OH), and the solubility product for ZrO(am) after the critical review.

Effect of carbonate concentration on the dissolution rates of UO 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 mol dm, 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 and spent fuel has been reviewed.

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

https://doi.org/10.1080/00223131.2016.1255573

Zr solubility in the presence of gluconic acid (GLU) and isosaccharinic acid (ISA) was investigated as a function of hydrogen ion concentration (pH) and the total concentration of GLU or ISA. The dependence of the increase in Zr solubility on the pH and GLU concentration suggested the existence of Zr(OH)(GLU) in the neutral pH region and Zr(OH)(GLU)(GLU) in the alkaline pH region above pH 10 as the dominant species in the presence of 10 - 10 mol/dm (M) GLU. In the presence of ISA, the dominant species Zr(OH)(ISA) and Zr(OH)(ISA)(ISA) 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)(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.

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

https://doi.org/10.3327/jnuce.23.1_31

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.