M –UO 2+ –CO 2- System and Integration 2 3 with …JAEA-Data/Code 2018-018 JAEA-TDB の更新：ジルコニウムおよびイソサッカリン酸錯体の熱力学データの更新，

JAEA-Data/Code

2018-018

日本原子力研究開発機構

March 2019

Japan Atomic Energy Agency

DOI:10.11484/jaea-data-code-2018-018

Akira KITAMURA

Update of JAEA-TDB: Update of Thermodynamic Data for Zirconium and Those

for Isosaccahrinate, Tentative Selection of Thermodynamic Data for Ternary

M2+–UO22+–CO3

2- System and Integration

with JAEA’s Thermodynamic Database for Geochemical Calculations

Radioactive Waste Processing and Disposal Research Department Nuclear Backend Technology Center

Nuclear Fuel Cycle Engineering LaboratoriesSector of Nuclear Fuel, Decommissioning and Waste Management Technology Development

本レポートは国立研究開発法人日本原子力研究開発機構が不定期に発行する成果報告書です。

本レポートの入手並びに著作権利用に関するお問い合わせは、下記あてにお問い合わせ下さい。

なお、本レポートの全文は日本原子力研究開発機構ホームページ（https://www.jaea.go.jp）より発信されています。

This report is issued irregularly by Japan Atomic Energy Agency.Inquiries about availability and/or copyright of this report should be addressed toInstitutional Repository Section,Intellectual Resources Management and R&D Collaboration Department,Japan Atomic Energy Agency.2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 JapanTel +81-29-282-6387, Fax +81-29-282-5920, E-mail:[email protected]

© Japan Atomic Energy Agency, 2019

国立研究開発法人日本原子力研究開発機構研究連携成果展開部研究成果管理課

〒319-1195 茨城県那珂郡東海村大字白方 2 番地4電話 029-282-6387, Fax 029-282-5920, E-mail:[email protected]

JAEA-Data/Code 2018-018

Update of JAEA-TDB: Update of Thermodynamic Data for Zirconium and Those for Isosaccahrinate,

Tentative Selection of Thermodynamic Data for Ternary M2+–UO22+–CO32- System and Integration

with JAEA’s Thermodynamic Database for Geochemical Calculations

Akira KITAMURA

Radioactive Waste Processing and Disposal Research Department,

Nuclear Backend Technology Center

Nuclear Fuel Cycle Engineering Laboratories

Sector of Nuclear Fuel, Decommissioning and Waste Management Technology Development

Japan Atomic Energy Agency

Tokai-mura, Naka-gun, Ibaraki-ken

(Received December 13, 2018)

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 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.

Keywords: Geological Disposal, High-level Radioactive Waste, TRU Waste, Thermodynamic Database,

Update of JAEA-TDB, Zirconium, Isosaccharinate, Uranium(VI), Geochemical Calculation

i



JAEA-TDB の更新：ジルコニウムおよびイソサッカリン酸錯体の熱力学データの更新，

アルカリ土類金属-ウラン(VI)-炭酸三元錯体の熱力学データの暫定採用および

地球化学計算用熱力学データベースの統合

日本原子力研究開発機構

核燃料・バックエンド研究開発部門

核燃料サイクル工学研究所

環境技術開発センター

基盤技術研究開発部

北村暁

（2018 年 12 月 13 日受理）

最新の熱力学データのレビューを行い，選定された値を高レベル放射性廃棄物および TRU

廃棄物の地層処分の性能評価に用いるための熱力学データベース（JAEA-TDB）に収録した。

今回のレビューでは，1) ジルコニウムの水酸化物および加水分解種の熱力学データについて，

経済協力開発機構原子力機関（OECD/NEA）が公開した熱力学データベースと比較しつつ熱

力学データを選定した。また，2) 金属イオンのイソサッカリン酸錯体の熱力学データについ

ては，最新のレビュー論文を基に，選定値のレビューと内部整合性の確認を行ったうえで採

用した。さらに，3) アルカリ土類元素，ウラン（VI）イオンおよび炭酸イオンから構成され

る三元錯体の熱力学データについて，文献情報を暫定的に追加した。そして，4) 地球化学計

算用に整備された熱力学データベースとの統合を実現させた。選定値の内部整合性は著者が

確認した。更新した JAEA-TDB を有効活用するために，PHREEQC および Geochemist’s

Workbench といった地球化学計算コード用フォーマットを整備した。

核燃料サイクル工学研究所：〒319-1194 茨城県那珂郡東海村村松 4-33

ii


Contents

1. Introduction ........................................................................................................................... 1

2. Brief Summary on Development of JAEA-TDB ................................................................... 3

2.1 Selection of Thermodynamic Data ............................................................................... 3

2.2 Calculation of Equilibrium Constant from Gibbs Free Energy of Formation .............. 4

3. Additional Selection or Revision of Thermodynamic Data ................................................... 6

3.1 Zirconium ..................................................................................................................... 6

3.2 Isosaccharinates ............................................................................................................ 9

3.3 Tentative Selection for Ternary Metal(II)-Uranium(VI)-Carbonate Complexes ........ 12

3.4 Replacement of Thermodynamic Data for Geochemical Calculations ...................... 13

3.5 Other Refinements ...................................................................................................... 13

3.5.1 Change Secondary Master Species of C(IV) .................................................... 13

3.5.2 Dettachment of Thermodynamic Data for Geochemical Calculations

Selected in Previous Update ............................................................................. 13

3.6 Preparation of Text Files for Geochemical Calculation Programs ............................. 13

4. Preliminary Calculation of Solubility of Radionuclides in Groundwaters and Bentonite

Porewaters Modeled in the H12 Project ............................................................................... 14

4.1 Simulated Groundwater and Bentonite Porewater Compositions for H12 ................. 14

4.2 Solubility of Radionuclides Predicted in FRHP and SRHP type Bentonite

Porewaters ................................................................................................................ 18

5 Conclusions ......................................................................................................................... 29

Acknowledgements ...................................................................................................................... 29

References .................................................................................................................................... 30

Appendix 1 Updated Thermodynamic Data Compiled for JAEA-TDB ................................... 35

Appendix 2 Text Files of JAEA-TDB for Geochemical Calculation Programs ..................... 103

iii


目次

1. 緒言 ....................................................................................................................................... 1

2. JAEA-TDB 整備の概要 ....................................................................................................... 3

2.1 熱力学データの選定 .................................................................................................. 3

2.2 ギブズ標準自由エネルギーを用いた平衡定数の計算 .......................................... 4

3. 熱力学データの追加選定および改訂 ............................................................................... 6

3.1 ジルコニウム .............................................................................................................. 6

3.2 イソサッカリン酸系 .................................................................................................. 9

3.3 金属（II）–ウラン（VI）–炭酸系の暫定採用 ..................................................... 12

3.4 地球化学計算用熱力学データの入れ替え ............................................................ 13

3.5 その他の修正 ............................................................................................................ 13

3.5.1 炭素（IV）の主化学種の変更 ...................................................................... 13

3.5.2 従前の地球化学計算用熱力学データの分離 .............................................. 13

3.6 地球化学計算コード用フォーマットの整備 ........................................................ 13

4. 地層処分研究開発第 2 次取りまとめで設定した地下水，緩衝材間隙水および

核種溶解度の試計算 .......................................................................................................... 14

4.1 モデル地下水および緩衝材間隙水組成 ................................................................ 14

4.2 FRHP および SRHP 緩衝材間隙水中の核種溶解度 ............................................. 18

5. 結言 ..................................................................................................................................... 29

謝辞 ............................................................................................................................................. 29

参考文献 ...................................................................................................................................... 30

付録 1 更新した JAEA-TDB 熱力学データ一覧 .................................................................. 35

付録 2 JAEA-TDB の地球化学計算プログラム用ファイル ............................................. 103

iv


Content of Tables

Table 1 Selected thermodynamic data for Zr with comparing the previous update (JAEA-2014) ...... 8

Table 2 Ion interaction coefficients (ε) for zirconium selected in the updated JAEA-TDB ................ 8

Table 3 Selected thermodynamic data on ISA system with comparing the previous update

(JAEA-2014) ......................................................................................................................... 10

Table 4 Ion interaction coefficients (ε) for ISA system tentatively selected with assumption of

charge or chemical analogy in the updated JAEA-TDB ....................................................... 11

Table 5 Supplementally selected thermodynamic data on the M2+-UO22+-CO32- system

by Thoenen et al. ................................................................................................................... 12

Table 6 Thermodynamic data used for calculating groundwater compositions simulated in H12 .... 15

Table 7 Predicted groundwater (GW) compositions simulated in H12 ............................................. 17

Table 8 Predicted bentonite porewater (PW) compositions simulated in H12 .................................. 17

Table 9 Predicted solubility of ZrO2(am) (Zr(OH)4(am,fresh) in JAEA-2014) with showing

contribution of aqueous species in FRHP type bentonite porewater..................................... 20


contribution of aqueous species in SRHP type bentonite porewater..................................... 20

Table 11 Predicted solubility of UO2(am) with showing contribution of aqueous species in FRHP

type bentonite porewater ....................................................................................................... 20 Table 12 Predicted solubility of UO2(am) with showing contribution of aqueous species in SRHP

type bentonite porewater ....................................................................................................... 21

Table 13 Predicted solubility of β-Co(OH)2 with showing contribution of aqueous species in FRHP


Table 14 Predicted solubility of β-Co(OH)2 with showing contribution of aqueous species in SRHP


Table 15 Predicted solubility of β-Ni(OH)2 with showing contribution of aqueous species in FRHP

type bentonite porewater ....................................................................................................... 21 Table 16 Predicted solubility of β-Ni(OH)2 with showing contribution of aqueous species in SRHP


Table 17 Predicted solubility of FeSe2(cr) with showing contribution of aqueous species in FRHP


Table 18 Predicted solubility of FeSe2(cr) with showing contribution of aqueous species in SRHP


Table 19 Predicted solubility of SrCO3(strontianite) with showing contribution of aqueous species

in FRHP type bentonite porewater ........................................................................................ 22

v


Table 20 Predicted solubility of SrCO3(strontianite) with showing contribution of aqueous species

in SRHP type bentonite porewater ........................................................................................ 22

Table 21 Predicted solubility of Nb2O5(s) with showing contribution of aqueous species in FRHP


Table 22 Predicted solubility of Nb2O5(s) with showing contribution of aqueous species in SRHP


Table 23 Predicted solubility of CaMoO4(cr) with showing contribution of aqueous species


Table 24 Predicted solubility of CaMoO4(cr) with showing contribution of aqueous species


Table 25 Predicted solubility of TcO2·1.6H2O(s) with showing contribution of aqueous species in

FRHP type bentonite porewater ............................................................................................ 23


SRHP type bentonite porewater ............................................................................................ 24

Table 27 Predicted solubility of Pd(OH)2(am) with showing contribution of aqueous species


Table 28 Predicted solubility of Pd(OH)2(am) with showing contribution of aqueous species


Table 29 Predicted solubility of SnO2(am) with showing contribution of aqueous species in FRHP


Table 30 Predicted solubility of SnO2(am) with showing contribution of aqueous species in SRHP


Table 31 Predicted solubility of PbCO3(cerrusite) with showing contribution of aqueous species in

FRHP type bentonite porewater ............................................................................................ 25

Table 32 Predicted solubility of PbCO3(cerrusite) with showing contribution of aqueous species


Table 33 Predicted solubility of RaCO3(cr) with showing contribution of aqueous species in FRHP


Table 34 Predicted solubility of RaCO3(cr) with showing contribution of aqueous species in SRHP


Table 35 Predicted solubility of AcCO3OH(am) with showing contribution of aqueous species in

FRHP type bentonite porewater ............................................................................................ 25 Table 36 Predicted solubility of AcCO3OH(am) with showing contribution of aqueous species in


Table 37 Predicted solubility of MCO3OH·0.5H2O(cr) (M: Sm, Am, Cm) with showing

vi


contribution of aqueous species in FRHP type bentonite porewater..................................... 26

Table 38 Predicted solubility of MCO3OH·0.5H2O(cr) (M: Sm, Am, Cm) with showing

contribution of aqueous species in SRHP type bentonite porewater..................................... 26

Table 39 Predicted solubility of ThO2(am,aged) with showing contribution of aqueous species in

FRHP type bentonite porewater ............................................................................................ 26 Table 40 Predicted solubility of ThO2(am,aged) with showing contribution of aqueous species in


Table 41 Predicted solubility of Pa2O5(s) with showing contribution of aqueous species in FRHP type

bentonite porewater ............................................................................................................... 27

Table 42 Predicted solubility of Pa2O5(s) with showing contribution of aqueous species in SRHP type

bentonite porewater ............................................................................................................... 27

Table 43 Predicted solubility of NpO2(am) with showing contribution of aqueous species in FRHP


Table 44 Predicted solubility of NpO2(am) with showing contribution of aqueous species in SRHP


Table 45 Predicted solubility of PuO2(am) with showing contribution of aqueous species in FRHP


Table 46 Predicted solubility of PuO2(am) with showing contribution of aqueous species in SRHP


Table A1 Selected equilibrium constants of aqueous species for JAEA-TDB ready to use for the

geochemical calculation programs (revised from Table A1 in the previous TDB report) .... 36

Table A2 Selected equilibrium constants of solid phases for JAEA-TDB ready to use for the


Table A3 Selected equilibrium constants of gaseous phases for JAEA-TDB ready to use for the


Table A4 Correspondence among file name, TDB type and geochemical calculation program ........ 103

vii


Content of Figures

Figure 1 Evaluated and predicted solubility values of amorphous zirconium hydroxide

(Zr(OH)4(am)) in Ca2+-Zr4+-OH- system ................................................................................. 7

Figure 2 Predicted pH and Eh (vs. SHE) values on (a) groundwater and (b) bentonite porewater

compositions simulated in H12 using the JAEA-TDBs before (JAEA-2014) and after

(present) updating ................................................................................................................. 16

Figure 3 Predicted solubility values for important elements on HLW and TRU waste disposal in the

FRHP type bentonite porewater using three stages of JAEA-TDB (see text for detail) ....... 19


SRHP type bentonite porewater using three stages of JAEA-TDB (see text for detail) ....... 20

viii


1. Introduction

Many radionuclides are contained in high-level radioactive waste (HLW) and are part of TRU

waste packages, and some of them have long half-lives (more than 104 years). It is necessary to estimate

the solubility of the radionuclides in groundwaters and bentonite porewaters in an engineered barrier

system for performance assessment of geological disposal of HLW and TRU wastes. Thermodynamic

data (e.g., the equilibrium constant of solubility limiting solids at standard state, i.e. 298.15 K and ionic

strength of zero) are needed to estimate the solubility and aqueous species in the groundwater and

bentonite porewater. These data are also needed to estimate sorption and diffusion behavior of chemical

species on/in engineered barriers and host rocks. Therefore, the most reliable thermodynamic data

should be compiled to carry out the reliable performance assessment by an implementation and

regulatory organization.

The author and his colleagues have developed and updated the JAEA’s thermodynamic database

(JAEA-TDB) (JAEA is the acronym of Japan Atomic Energy Agency) for the performance assessment

of geological disposal of radioactive waste 1-4). Main part of the thermodynamic data in JAEA-TDB

were selected and estimated by JAEA, however, some were taken from the data selected in the NEA

Thermochemical Data Base Project (NEA-TDB) organized by the Nuclear Energy Agency (NEA)

within the Organisation for Economic Co-operation and Development (OECD) 5) and those selected in

JNC-TDB 6) (JNC is the acronym of Japan Nuclear Cycle Development Institute which is one of the

predecessor of JAEA). The thermodynamic data were compiled and converted to be available for use in

geochemical calculation programs, e.g., PHREEQC 7), EQ3/6 8) and Geochemist’s Workbench (GWB) 9).

In the present update of JAEA-TDB from “the previous update published in 2014” (JAEA-2014) 4),

the author has focused four systems; 1) a zirconium-hydroxide system, 2) complexation of metal ions

with isosaccharinic acid (ISA), 3) ternary complexes among alkaline-earth metal, uranyl and carbonate

ions, and 4) thermodynamic data for geochemical calculations.

Significant discrepancies on solubility have been appeared between experimental data 12,13) and

thermodynamically calculated data using the JAEA-2014 although a critical review of thermodynamic

data for zirconium was performed by Brown et al. 14). The selected equilibrium constants for

hypothetical polynuclear hydrolysis species (e.g., Zr4(OH)16(aq)) make solubility values much larger

than those obtained from experimental studies. Therefore Rai et al. 10) critically reviewed all

experimental data reviewed by the Brown et al. 14), and re-selected equilibrium constants for Zr-OH

system without assuming poly nuclear species. The author has accepted the re-selected values.

Furthermore, the author has also accepted the paper on Zr4+-CO32- system 15) which has been critically

reviewd by the author.

Thermodynamic data for complexation of trivalent and tetravalent actinides with ISA and

- 1 -


gluconic acid (GLU) were reviewed by Gaona et al.16) and accepted in JAEA-2014 4). Rai and Kitamura

have published two review papers on critical review on thermodynamic data for ISAs; one is on

deprotonation and lactonisation of α-D-isosaccharinic acid 17), and the other is for complexation of metal

ions with ISA 11) using the selected deprotonation and lactonisation constants. The author has accepted

the selected values by Rai and Kitamura 11,17) because of more comprehensiveness than those by Gaona

et al. 16). Furthermore, the author has also accepted two reliable papers on ISA system; one is for Ni2+ 18)

and the other is for Zr4+ 19).

On the other hand, JNC developed and updated another “thermodynamic database for

geochemical calculations” (A-TDB) 20,21) while the older compiled databases developed by Müller 24)

and “Robie and Hemingway” 25) have been used for the “TDB for geochemical calculations in JAEA-

2014” 4) (Y-TDB). The A-TDB was developed for use of SUPRCT92, a software package for calculating

the standard molal thermodynamic properties of minerals, gases, aqueous species and reactions 26). The

A-TDB was more comprehensively than the older databases, including those for cementitious materials,

with confirming internal consistency in the database. “The latest version of the A-TDB” (W-TDB) has

been published in 2018 22, 23).

Considering the above circumstances, the author has decided to update the JAEA-2014 with

selecting the recently reviewed data and to replace the thermodynamic data for geochemical calculations

to those of the W-TDB. Since simulated groundwater compositions 27) and porewater compositions 28)

after passing the groundwater in the compacted bentonite for H12 (the second progress report on

geological disposal of HLW in Japan) 29) have been established using the thermodynamic data for

geochemical calculations in JAEA-2014 4), the expired part of the database has been decided to store in

another text for checking the validity of the groundwater and bentonite porewater compositions. The

author has also decided to provide text files of updated and expired TDB for use of the geochemical

calculation programs of PHREEQC 7) and GWB 9), while the preparation of text file for EQ3/6 8) has

been withdrawn because of no provision in development of the W-TDB.

- 2 -


2. Brief Summary on Development of JAEA-TDB

2.1 Selection of Thermodynamic Data

Selection of thermodynamic data for JAEA-TDB was performed on the basis of the fundamental

plan 1) briefly described below.

This fundamental plan required the selection of equilibrium constants of different reactions at

standard state (Kº) and also recommended the selection of values for other thermodynamic parameters

such as enthalpy, entropy and heat capacity. Phase designators, (cr), (am), (s), (l), (aq) and (g),

accompanying compounds/species denote crystalline, amorphous, undefined-solid, pure liquid,

uncharged aqueous species and gaseous species, respectively.

Thermodynamic data for chemical compounds and species for radioelements with naturally

occurring elements (e.g., halogens, oxygen, carbon, nitrogen, sulfur, phosphorus) and some organic

ligands were selected. Other needed thermodynamic data for basal species that either form compexes or

compounds with radioelements were selected from the “Auxiliary Data” reported in NEA-TDB 5).

Review and selection of thermodynamic values obtained from experimental data should be based

on the “TDB-1” guideline by Wanner 30). Thermodynamic values or databases selected in NEA-TDB 5)

and Lothenbach et al. 31), which were based on the “TDB-1” guideline 30), could be selected to the JAEA-

TDB after surveying the latest literature and checking consistency of the value in the database.

Otherwise review and selection of thermodynamic values should be performed after surveying the

literature to collect proposed thermodynamic data.

Application of chemical analogues and models should be considered to obtain thermodynamic

values for some species for which there has been no published experimental data. Some unreliable

thermodynamic values, which are important for the performance assessment of geological disposal of

radioactive wastes, may be selected as tentative values while specifying their reliability and the need for

these values.

All thermodynamic values should be standardized to 298.15 K and zero ionic strength using the

Brønsted-Guggenheim-Scatchard Model (usually called the “specific ion interaction theory (SIT)”)

based on the “TDB-2” guidleline in NEA-TDB 32) for correction of ionic strength. In the model, the

activity coefficient γj of an ion j of charge zj in the electrolyte solution of molarity mk (mol kg-1) and

ionic strength Im (mol kg-1) is assumed as follows:

log 𝛾𝛾𝑗𝑗 = −𝑧𝑧𝑗𝑗2𝐷𝐷 + ∑ 𝜀𝜀(𝑗𝑗,𝑘𝑘,𝐼𝐼𝑚𝑚)𝑚𝑚𝑘𝑘𝑘𝑘

, (1)

where D denotes the Debye-Hückel term as defined as a function of Im as shown in the following

equation; 𝜀𝜀(𝑗𝑗,𝑘𝑘,𝐼𝐼𝑚𝑚) denotes the ion interaction coefficient of ion j against the counterion(s) k at a certain

- 3 -


Im:

m

m

I.

I.D

511

5090

. (2)

The ionic strength Im equals the molarity mk in case of 1:1 electrolyte (e.g. NaCl, NaClO4). The ion

interaction coefficients 𝜀𝜀(𝑗𝑗,𝑘𝑘,𝐼𝐼𝑚𝑚) are assumed to be zero for ions of the same charge sign and for uncharged species (e.g. UO2(OH)2(aq)).

2.2 Calculation of Equilibrium Constant from Gibbs Free Energy of Formation

There are some compounds/species for which equilibrium constants have not been selected and

only Gibbs free energies of formation are available. The equilibrium constants are required for use in

some geochemical calculation programs such as PHREEQC 7). Therefore some equilibrium constants

were determined from the Gibbs free energy of formation using the following calculation.

Using the Hess’s law, change in Gibbs free energy of reaction (ΔrG°m) for some arbitrary reaction,

e.g.,

a A + b B ⇄ c C + d D , (3) where A, B, C and D are substances involving the reaction, and a, b, c and d are coefficients of

the substances A, B, C and D, respectively,

is expressed using change in Gibbs free energy of formation (ΔfG°m(X) for species or compound X) as

follows:

ΔrG°m = c ΔfG°m(C) + d ΔfG°m(D) – a ΔfG°m(A) – b ΔfG°m(B) . (4)

Logarithm of equilibrium constant at standard state (log10 K°) is derived from ΔrG°m using the following

equation:

ΔrG°m = –RT loge K° (5)

where R is the gas constant (8.31451070 J·K-1·mol-1) and T is absolute temperature (which for 25 °C is

298.15 K) (NEA). Therefore at 298.15 K, log10 K° = -(ΔrG°m)/(5.708) .

Uncertainty (σ) of ΔrG°m and log10 K° is obtained from error propagation of ΔfG°m(X) as follows:

- 4 -


σ(ΔrG°m) = (c σ(ΔfG°m(C))2 + d σ(ΔfG°m(D))2 + a σ(ΔfG°m(A))2 + b σ(ΔfG°m(B))2)1/2 (6)

σ(log10 K°) = σ(ΔrG°m)/5.708. (7)

The uncertainty in equilibrium constant (σ(log10 K°)) calculated using reactions (6) and (7) is usually

larger than that obtained experimentally. The smallest of the uncertainty values have been selectated on

the basis of either the experimental data or calculations.

For use with geochemical calculation programs, dissociation reactions are defined for all compounds

and gaseous species, i.e., the objective compounds and species are put on the left-hand side and aqueous

master species of the objective elements are put on right-hand side in their reactions.

- 5 -


3. Additional Selection or Revision of Thermodynamic Data

3.1 Zirconium

Zirconium (Zr) is one of the components of fuel cladding materials. Zirconium-93 is one of the

significant radionuclides for performance assessment of geological disposal of HLW29). Thermodynamic

database of Zr has been developed by Brown et al. 14), and the selected data by Brown et al. 14) has been

accepted in JAEA-2014. The calculated solubility values in Zr4+-OH- system, however, are sometimes

much larger than the experimental values 13) as shown in Figure 1. This discrepancy arises from

overestimation of contribution of Zr hydrolysis species, especially for neutral species (Zr(OH)4(aq) and

Zr4(OH)16(aq)). Furthermore, several polynuclear hydrolysis species (Zr3(OH)93+, Zr4(OH)15+ and

Zr4(OH)16(aq)) are hypothetical to fit to some experimental data by Brown et al. 14). Unfortunately, recent

solubility data in (Ca2+-)Zr4+-OH- system by Sasaki et al. 12) and Altmaier et al. 33) was not on the review

because the paper was published after closing the review processes.

Therefore, Rai et al. 10) performed a critical review thermodynamic data in the Ca2+-Na+-H+-Cl--

OH--H2O system; not only the recent papers (e.g., Sasaki et al. 12), Altmaier et al. 33)) but also the

publications which have been reviewed by Brown et al. 14). Rai et al. 10) also performed quantum

mechanical calculations to evaluate the energy required to construct the polynuclear species to check

thermodynamic faborability of hydrolytic polymerization of Zr. The calculations suggested that

polynuclear Zr species would be unlikely to form from its component monomeric species under dilute

conditions. Thus Rai et al. 10) concluded that the model based on mononuclear Zr species provides

reliable Zr solubility predictions over a large range of H+ concentrations (-log [H+] from 1 to 15.4).

Finally, Rai et al. 10) selected equilibrium constants for ZrO2(am) (equivalent to Zr(OH)4(am)),

Zr(OH)22+, Zr(OH)4(aq), Zr(OH)5-, Zr(OH)62- and Ca3Zr(OH)64+, and accepted that for ZrOH3+ selected

by Brown et al. 14).

Furthermore, the author has accepted to the latest equilibrium constants for carbonate 15) and

isosaccharinate 19) complexes of Zr after conducting a critical review.

It has been concluded that the author has selected equilibrium constants for 5 new species,

eliminated those for 5 (polynuclear) species, and updated those for 6 aqueous species and a solid phase,

as shown in Table 1. The selected ion interaction coefficients (ε(j,k)) accompanied with log K° values for zirconium are shown in Table 2.

- 6 -


Figure 1 Evaluated and predicted solubility values of amorphous zirconium hydroxide

(Zr(OH)4(am)) in Ca2+-Zr4+-OH- system

The plots are experimental values with varying aqueous calcium concentrations

(quantification limit: 10-8 M) 13) and the lines are preducted values using the TDB of (a)

JAEA-2014 4) and (b) the present update with PHREEQC 7) assuming no aquous calcium

concentration ([Ca] = 0 mM).

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

[Ca] = 0 mM[Ca] = 0.03 mM[Ca] = 0.1 mM[Ca] = 0.3 mM[Ca] = 1 mM

Zr c

once

ntra

tion

(M)

Zr(total)Zr4(OH)16(aq)

Zr(OH)4(aq)

Zr(OH)62-

(a) JAEA-2014

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

8 9 10 11 12 13 14

[Ca] = 0 mM[Ca] = 0.03 mM[Ca] = 0.1 mM[Ca] = 0.3 mM[Ca] = 1 mM

Zr c

once

ntra

tion

(M)

pHc

Zr(total)

Zr(OH)5-

Zr(OH)4(aq)

Zr(OH)62-

(b) present

belowquantification

limit

belowquantification

limit

- 7 -


Table 1 Selected thermodynamic data for Zr with comparing the previous update (JAEA-2014)

Revised values are shown in bold letters.

Reaction log10 K° present JAEA- 2014 4)Zr4+ + H2O(l) ⇄ ZrOH3+ + H+ 0.320 ± 0.220 0.320 ± 0.220 Zr4+ + 2 H2O(l) ⇄ ZrOH)22+ + 2 H+ ≤ -2.302 0.980 ± 1.060 Zr4+ + 4 H2O(l) ⇄ Zr(OH)4(aq) + 4 H+ < -9.924 -2.190 ± 1.700 Zr4+ + 5 H2O(l) ⇄ Zr(OH)5- + 5 H+ -19.655 ± 0.242 -- Zr4+ + 6 H2O(l) ⇄ Zr(OH)62- + 6 H+ -33.286 ± 0.256 -29.000 ± 0.700 3 Zr4+ + 4 H2O(l) ⇄ Zr3(OH)48+ + 4 H+ -- 0.400 ± 0.300 3 Zr4+ + 9 H2O(l) ⇄ Zr3(OH)93+ + 9 H+ -- 12.190 ± 0.080 4 Zr4+ + 8 H2O(l) ⇄ Zr4(OH)88+ + 8 H+ -- 6.520 ± 0.650 4 Zr4+ + 15 H2O(l) ⇄ Zr4(OH)15+ + 15 H+ -- 12.580 ± 0.240 4 Zr4+ + 16 H2O(l) ⇄ Zr4(OH)16(aq) + 16 H+ -- 8.390 ± 0.800 Zr4+ + 4 CO32- ⇄ Zr(CO3)44- 41.650 ± 0.120 42.900 ± 1.000 Zr4+ + 5 CO32- ⇄ Zr(CO3)56- 40.850 ± 0.211 -- Zr4+ + 2 CO32- + 2 H2O(l) ⇄Zr(CO3)2(OH)22- + 2 H+ 18.148 ± 0.124 -- Zr4+ + 2 Ca2++ 6 H2O(l) ⇄ Ca2[Zr(OH)6]2+ + 6 H+ -25.660 ± 0.335 -22.606 ± 0.313 Zr4+ + 3 Ca2++ 6 H2O(l) ⇄ Ca3[Zr(OH)6]4+ + 6 H+ -27.006 ± 0.238 -23.206 ± 0.313 Zr4+ + (ox)2- ⇄ Zr(ox)2+ 7.466 10.520 Zr4+ + 2 (ox)2- ⇄ Zr(ox)2 15.096 18.150 Zr4+ + (cit)3- ⇄ Zr(cit)+ 10.216 13.270 Zr4+ + H+ + (cit)3- ⇄ ZrH(cit)2+ 11.826 14.880 Zr4+ + 4 H2O(l) + 2 (isa)- ⇄ Zr(OH)4(isa)22- + 4 H+ -2.554 ± 0.135 -- Zr4+ + 5 H2O(l) + 2 (isa)- ⇄ Zr(OH)4(isa)(isa-H)3- + 5 H+ -15.155 ± 0.142 -- ZrO2(mono) + 4 H+ ⇄ Zr4+ + 4 H2O(l) -7.000 ± 1.600 -7.000 ± 1.600 Zr(OH)4(am,fresh) + 4 H+ ⇄ Zr4+ + 4 H2O(l) -0.186 ± 0.067 -3.240 ± 0.100

Table 2 Ion interaction coefficients (ε) for ziconium selected in the updated JAEA-TDB

species ε (kg mol-1) reference

Zr4+, Cl- 0.33 ± 0.09 14

ZrOH3+, Cl- 0.22 ± 0.11 33

Na+, Zr(OH)5- 0.03 ± 0.01 present

Na+, Zr(OH)62- 0.068 ± 0.01 present

Ca3[Zr(OH)6]4+, Cl- 0.51 present

Zr(CO3)44- 0.64 ± 0.06 15

Zr(CO3)56- 0.95 ± 0.18 15

Zr(CO3)2(OH)22- - 0.01 ± 0.04 15

Zr(OH)4(isa)22- 0* 19

Zr(OH)4(isa)(isa-H)3- 0* 19 *Assumed.

- 8 -


3.2 Isosaccharinates

Isosaccharinic acid (ISA) is a cellulose degradation product that can form in TRU waste

repositories and is known to form strong complexes with many elements, including actinides, disposed

of in these repositories. Although a critical review on ISA has been performed by Hummel et al. 34) with

accepting the importance of its thermodynamic data, there are only a few data selected, e.g. dissociation

constant and solubility product of Ca(ISA)2, which would not be useful for performance assessment of

geological disposal of TRU waste. The reasons why most of thermodynamic data on ISA system were

not selected are 1) solubility of radionuclides in the presence of ISA in earlier literature was not strictry

thermodynamic solubilities, 2) measured maximum concentration of an element was over a solubility-

limiting solid phase, and 3) solid phase was seldom well identified and the final oxidation state of the

element in the solution was uncertain 34). Considering above, thermodynamic data on ISA have been

selected through reviewing the previous review by Gaona et al. 16) and tentatively using a linear free

energy relationship (LFER) between thermodynamic data on ISA and those on GLU 35).

The latest review on ISA system has been performed because it has past more than 10 years since

Gaona et al.16) have been published and some recent experimental studies on solubility of radionuclides

in the presence of ISA, e.g. Rai et al. 36,37), have been published. Rai and Kitamura 17) has selected

equilibrium constants for deprotonation and lactonisation of ISA through a critical review of

experimental data. Since then, Rai and Kitamura 11) has also selected equilibrium constants of metal ions

in the presence of ISA through a comprehensive review of experimental data. Furthermore, the author

found a paper on Ni-ISA system 18) and concluded that the paper is reliable through a critical review. In

contrast, the tentatively selected data obtained from LFER in JAEA-2014 4) have been eliminated due

to low reliability.

It has been concluded that the author has selected equilibrium constants for 27 new species,

eliminated those for 5 species, and updated those for 5 aqueous species and a solid phase, as shown in

Table 3. The tentatively selected ion interaction coefficients (ε(j,k)) accompanied with log K° values for ISA system are shown in Table 4. All the ε(j,k) values have been estimated using either two analogies;

one is the charge analogy that is calculation of average values of species with same net electric charge

and with same counterions (e.g. ε(FeISA+, ClO4-) based on the average of M2+ with ClO4- reported by

the NEA 37)); the other is the chemical analogy that is taking the ε(j,k) values from other species with

same counterions assuming chemical similarities (e.g. ε(Na+, Th(OH)3(ISA)2-) from ε(Na+, ISA-) 36)).

- 9 -


Table 3 Selected thermodynamic data on ISA system with comparing the previous update (JAEA-2014) 4) Revised values are shown in bold letters.

Reaction log10 K° present JAEA- 2014 4) H+ + (isa)- ⇄ H(isa)(aq) 3.270 ± 0.010 4.000 ± 0.500 H(isa)(aq) ⇄ (isl)(aq) + H2O(l) 0.490 ± 0.090 -- (isl)(aq) +H2O(l) ⇄ (isa)- + H+ -3.760 ± 0.090 -- Ca2+ + isa- ⇄ Ca(isa)+ 1.700 ± 0.090 1.700 ± 0.300 Mg2+ + (isa)- ⇄ Mg(isa)+ -- 0.600 Sr2+ + (isa)- ⇄ Sr(isa)+ -- 0.910 Fe2+ + (isa)- ⇄ Fe(isa)+ -- 0.940 Fe3+ + (isa)- ⇄ Fe(isa)2+ 6.200 -- Fe3+ + 2 (isa)- ⇄ Fe(isa)2+ 10.410 -- Fe3+ + 3 (isa)- ⇄ Fe(isa)3(aq) 13.100 -- Fe3+ + 3 (isa)- ⇄ Fe(isa)4- 15.090 -- Fe3+ + (isa)- + 2 H2O(l) ⇄ Fe(OH)2(isa)(aq) + 2 H+ 1.900 ± 0.900 -- Fe3+ + 2 (isa)- + 3 H2O(l) ⇄ Fe(OH)3(isa)22- + 3 H+ -3.270 ± 0.320 -- Ni2+ + (isa)- ⇄ Ni(isa)+ -- 2.200 Ni2+ + H2O(l) + (isa)- ⇄ NiOH(isa)(aq) + H+ -6.50 ± 0.30 -- Ni2+ + 2 H2O(l) + (isa)- ⇄ Ni(OH)2(isa)- + 2 H+ -17.60 ± 0.50 -- Ni2+ + 3 H2O(l) + (isa)- ⇄ Ni(OH)3(isa)2- + 3 H+ -31.00 ± 0.70 -- Sr2+ + (isa)- ⇄ Sr(isa)+ -- 0.910 Zr4+ + 4 H2O(l) + 2 (isa)- ⇄ Zr(OH)4(isa)22- + 4 H+ -2.554 ± 0.135 -- Zr4+ + 5 H2O(l) + 2 (isa)- ⇄ Zr(OH)4(isa)(isa-H)3- + 5 H+ -15.155 ± 0.142 -- Sm3+ + 3 H2O(l) + (isa)- ⇄ Sm(OH)3(isa)- + 3 H+ -21.400 ± 2.000 * -21.400 ± 1.000 Sm3+ + (isa)- ⇄ Sm(isa)2+ 4.030 ± 0.560* -- Sm3+ + 2 (isa)- ⇄ Sm(isa)2+ 7.640 ± 0.260* -- Pb2+ + (isa)- ⇄ Pb(isa)+ -- 2.440 Ac3+ + 3 H2O(l) + (isa)- ⇄ Ac(OH)3(isa)- + 3 H+ -21.400 ± 2.000 * -21.400 ± 1.000 Ac3+ + (isa)- ⇄ Ac(isa)2+ 4.030 ± 0.560 * -- Ac3+ + 2 (isa)- ⇄ Ac(isa)2+ 7.640 ± 0.260 * -- Th4+ + H2O(l) + (isa)- ⇄ ThOH(isa)2+ + H+ 3.200 ± 0.500 3.200 ± 0.500 Th4+ + 3 H2O(l) + 2 (isa)- ⇄ Th(OH)3(isa)2- + 3 H+ -4.900 ± 0.500 -4.900 ± 0.500 Th4+ + 4 H2O(l) + 2 (isa)- ⇄ Th(OH)4(isa)22- + 4 H+ -12.500 ± 0.500 -12.500 ± 0.500 U4+ + 4 H2O(l) + (isa)- ⇄ U(OH)4(isa)- + 4 H+ -- -6.800 ± 0.900 U4+ + 4 H2O(l) + 2 (isa)- ⇄ U(OH)4(isa)22- + 4 H+ -3.500 ± 1.200 -4.900 ± 1.000 UO22+ + (isa)- ⇄ UO2(isa)+ 3.670 ± 0.190 -- UO22+ + 2 (isa)- ⇄ UO2(isa)2(aq) 6.400 ± 0.080 -- UO22+ + 3 (isa)- ⇄ UO2(isa)3- 8.280 ± 0.200 -- Np4+ + 3 H2O(l) + (isa)- ⇄ Np(OH)3(isa)(aq) + 3 H+ 3.270 ± 0.620 -- Np4+ + 3 H2O(l) + 2 (isa)- ⇄ Np(OH)3(isa)2- + 3 H+ 5.380 ± 0.620 -- Np4+ + 4 H2O(l) + (isa)- ⇄ Np(OH)4(isa)- + 4 H+ -4.060 ± 0.620 -4.060 ± 0.620 Np4+ + 4 H2O(l) + 2 (isa)- ⇄ Np(OH)4(isa)22- + 4 H+ -2.200 ± 0.620 -2.200 ± 0.620 Pu3+ + 3 H2O(l) + (isa)- ⇄ Pu(OH)3(isa)- + 3 H+ -21.400 ± 2.000 * -21.400 ± 1.000 Pu3+ + (isa)- ⇄ Pu(isa)2+ 4.030 ± 0.560 * -- Pu3+ + 2 (isa)- ⇄ Pu(isa)2+ 7.640 ± 0.260 * -- Pu4+ + 4 H2O(l) + (isa)- ⇄ Pu(OH)4(isa)- + 4 H+ -0.690 ± 0.430 -1.474 ± 1.588 Pu4+ + 4 H2O(l) + 2 (isa)- ⇄ Pu(OH)4(isa)22- + 4 H+ 3.150 ± 0.430 2.726 ± 1.127 Am3+ + 3 H2O(l) + (isa)- ⇄ Am(OH)3(isa)- + 3 H+ -21.400 ± 2.000 -21.400 ± 1.000 Am3+ + (isa)- ⇄ Am(isa)2+ 4.030 ± 0.560 -- Am3+ + 2 (isa)- ⇄ Am(isa)2+ 7.640 ± 0.260 -- Cm3+ + 3 H2O(l) + (isa)- ⇄ Cm(OH)3(isa)- + 3 H+ -21.400 ± 2.000 * -21.400 ± 1.000 Cm3+ + (isa)- ⇄ Cm(isa)2+ 4.030 ± 0.560* -- Cm3+ + 2 (isa)- ⇄ Cm(isa)2+ 7.640 ± 0.260* -- Ca(isa)2(cr) ⇄ Ca2+ + 2 (isa)- -6.400 ± 0.090 -6.4 ± 0.200

*Use of a chemical similarity to Am.

- 10 -


Table 4 Ion interaction coefficients (ε) for ISA system tentatively selected with assumption of charge

or chemical analogy in the updated JAEA-TDB

species ε (kg mol-1) reference

Na+, (isa)- -0.07 34

Fe(isa)2+, ClO4- 0.40 37

Fe(isa)2+, ClO4- 0.27 37

Na+, Fe(isa)4- 0.07 37

Na+, Fe(OH)3(isa)22- -0.125 37

Na+, Ni(OH)2(isa)- -0.05 ± 0.10 18

Na+, Ni(OH)3(isa)2- -0.10 ± 0.10 18

Na+, Zr(OH)4(isa)22- 0.00 19

Na+, Zr(OH)4(isa)(isa-H)3- 0.00 19

Am(isa)2+, ClO4- 0.33 11

Am(isa)2+, ClO4- 0.15 11

M(isa)2+, ClO4- * 0.33 present

M(isa)2+, ClO4- * 0.15 present

Na+, ThOH(isa)2+ 0.40 present

Na+, Th(OH)3(isa)2- -0.07 37

Na+, Th(OH)4(isa)22- -0.125 37

Na+, U(OH)4(isa)22- -0.12 11

UO2(isa)+, ClO4- 0.15 11

Na+, Np(OH)3(isa)2- -0.07 37

Na+, Np(OH)4(isa)- -0.07 37

Na+, Np(OH)4(isa)22- -0.125 37

Na+, Pu(OH)4(isa)- -0.07 11

Na+, Pu(OH)4(isa)22- -0.12 11 *M: Sm, Ac, Pu(III) and Cm

- 11 -


3.3 Tentative Selection for Ternary Metal(II)-Uranium(VI)-Carbonate Complexes

Thermodynamic data on ternary metal(II)-uranium(VI)-carbonate (M2+-UO22+-CO32-) complexes

was first derived by Bernhard et al. 38), have been proposed by several research groups 39-45), and have

been used for speciation of uranium in some environments. The proposed reactions are as follows:

p M2+ + q UO22+ + r CO32- ⇄ Mp(UO2)q(CO3)r2(r-p-q)- (8) (M: Mg, Ca, Sr and Ba) .

Most of studies on determination of equilibrium constants on the M2+-UO22+-CO32- system have been

performed using spectroscopic methods 38-41,44,45); only Dong and Brooks 42-43) has adopted an anion

exchange method.

Thermodynamic data on the Ca2+-UO22+-CO32- system published until 2001 38-41) were critically

reviewed by Guillaumont et al. 50), but were not accepted due to a large inconsistency on ionic strength

correction and lack of strong support for the formation of calcium bonding. Guillaumont et al. 50),

however, recognized the reviewed papers provided additional evidence for the complex formation

between UO2(CO3)34- and cations; this, itself, was an important observation.

After publishing additional thermodynamic data on the M2+-UO22+-CO32- system 42-45), Thoenen

et al. 51) has critically reviewed the papers and supplementally selected thermodynamic data on this

system as shown in Table 5.

Since the author agrees with Thoenen et al. 51) and has not found any other thermodynamic data

on this system, the selected data by Thoenen et al. 51) have been tentatively selected in the update of

JAEA-TDB. Therefore, 6 thermodynamic data have been newly added.

Table 5 Supplementally selected thermodynamic data on the M2+-UO22+-CO32- system by

Thoenen et al. 51)

M MUO2(CO3)32- MUO2(CO3)3(aq)

Mg 26.11 ± 0.50 ––

Ca 27.18 ± 0.50 29.22 ± 0.25

Sr 26.86 ± 0.50 ––

Ba 26.68 ± 0.50 29.75 ± 0.50

- 12 -


3.4 Replacement of Thermodynamic Data for Geochemical Calculations

As mentioned above, thermodynamic data for geochemical calculations selected in JAEA-2014

(Y-TDB) 4) have been replaced to those selected in W-TDB 22, 23) except for nickel species and

compounds to avoid duplications with JAEA-2014 4). Many thermodynamic data for geochemical

calculations have been newly added. The replacement enables establishment of more realistic

groundwater compositions due to critically reviewed and selected thermodynamic data on not only

naturally occurring minerals but also artificially synthesizing compounds such as cementitious materials.

It has been concluded that the author has newly selected equilibrium constants for 370 compounds

and minerals, eliminated those for 45 compounds and minerals, and updated those for 79 and 30

compounds and minerals without and with changing their stoichiometry, respectively. Detail of the

update is shown in Appendix 1.

3.5 Other Refinements

3.5.1 Change Secondary Master Species of C(IV)

The author has changed the secondary master species of tetravalent carbon (C(IV)) from CO32- to

HCO3- because W-TDB 22, 23) uses HCO3- as the secondary master species of C(IV). All reactions and

their thermodynamic data including CO32- have been replaced to those including HCO3- for unifying the

secondary master species of C(IV) through using the following reaction and the equilibrium constant:

CO32- + H+ ⇄ HCO3- log K° = 10.329 ± 0.020 (9)

3.5.2 Dettachment of Thermodynamic Data for Geochemical Calculations Selected in Previous

Update

The author recognizes the importance of replaced thermodynamic data selected in JAEA-2014

(Y-TDB) 4) due to confirming past geochemical calculations such as H12 29). Therefore the author has

decided to establish an indivisual TDB (Y-TDB including related thermodynamic data on aqueous and

gaseous reactions) for use of geochemical calculation programs.

3.6 Preparation of Text Files for Geochemical Calculation Programs

The author has prepared text files of the updated JAEA-TDB and Y-TDB (including related

thermodynamic data on aqueous and gaseous reactions) for geochemical calculation programs of

PHREEQC 7) and GWB 9) in the enclosed CD-ROM. See detail in Appendix 2. These files will be

uploaded in the Website on thermodynamic, sorption and diffusion databases

(https://migrationdb.jaea.go.jp/). In contrast, the preparation of text file for EQ3/6 8) has been withdrawn

because of no provision in development of the W-TDB 22, 23).

- 13 -


4. Preliminary Calculation of Solubility of Radionuclides in Groundwaters and Bentonite Porewaters

Modeled in the H12 Project

4.1 Simulated Groundwater and Bentonite Porewater Compositions for H12

The author has calculated 5 types of chemical compositions of groundwaters simulated in H12 29)

as follows:

– Fresh-reducing-high-pH (FRHP) type,

– Fresh-reducing-low-pH (FRLP) type,

– Saline-reducing-high-pH (SRHP) type,

– Saline-reducing-low-pH (SRLP) type, and

– Mixing-reducing-neutral-pH (MRNP) type.

Equilibrium constants used for calculations at mineral/water interface are listed in Table 6. There are

significant discrepancies on some equilibrium constants between JAEA-2014 4) and the present update,

e.g. CaMg(CO3)2(dolomite), Al2Si2O5(OH)4(kaolinite), Fe3O4(magnetite), KAlSi3O8 (microcline) and

FeS2(pyrite).

The predicted pH and redox potential (Eh; versus standard hydrogen electrode (SHE)) values on

groundwater and bentonite porewater compositions simulated in H12 29) using the JAEA-TDBs before

(JAEA-2014) and after (present) updating are shown in Figure 2. It is found that the obtained pH and

redox potential (Eh; against standard hydrogen electrode) have been changed through using the different

TDBs, especially for groundwater compositions.

Discrepancies of equilibrium constants between JAEA-2014 4) and the present update would cause

the difference of chemical compositions; e.g. Al2Si2O5(OH)4(kaolinite) for calculation of FRHP type

groundwater, KAlSi3O8(microcline) for calculation of SRHP type groundwater. Furthermore, logarithm of

the equilibrium constant of aqueous methane (CH4(aq)) has been replaced from -141.418 (calculated by the

author using the equilibrium constants related ) to -144.1441 ± 0.9 for the following reactions after updating

the TDB:

H2O(l) + H+ + HCO3- ⇄ CH4(aq) + 2 O2(aq) . (10)

The decrease of the equilibrium constant leads the increase of contribution of carbonates (H2CO3(aq),

HCO3- and CO32-) and the increase of Eh values, especially for SRHP type groundwater, and the

contribution of carbonate complexes of radionuclides. In contrast, the defference of the obtained values

using JAEA-2014 4) and the present update is less than that in groundwater compsitions because the

- 14 -


modeling of porewater chemistry 32) used in the calculation is mainly constrained by dissolution of

calcite (CaCO3). See Oda et al. 28) for detail of the modeling.

Detail of the predicted groundwater compositions are listed in Tables 7 and 8, respectively.

Table 6 Thermodynamic data used for calculating groundwater compositions simulated in H12 29)

mineral used for gourndwater equilibration

reaction log10 K°

FRHP SRHP FRLP SRLP MRNP JAEA-2014 4) present

albite NaAlSi3O8(albite) + 4 H2O(l) + 4 H+

⇄ Na+ + Al3+ + 3 H4SiO4(aq) 3.540 3.513

calcite CaCO3(calcite) ⇄ Ca2+ + CO32- -8.460 -8.480

chalcedony SiO2(chalcedony) + 2 H2O(l) ⇄ H4SiO4(aq) -3.490 -3.521

dolomite CaMg(CO3)2(dolomite) ⇄ Ca2+ + Mg2+ + 2 CO32- -17.090 -18.145

kaolinite Al2Si2O5(OH)4(kaolinite) + 6 H+

⇄ + 2 H4SiO4(aq) + 2 Al3+ + H2O(l) 9.080 5.291

magnetite Fe3O4(magnetite) + 8 H+ + 2 e-

⇄ 3 Fe2+ + 4 H2O(l) 30.650 36.498

microcline KAlSi3O8(microcline) + 4 H2O(l) + 4 H+

⇄ Al3+ +3 H4SiO4(aq) + K+ 1.780 0.302

muscovite KAl2(AlSi3O10)(OH)2(muscovite) + H+

⇄ 3 Al3+ + 3 H4SiO4(aq) + K+ 14.600 14.799

pyrite FeS2(pyrite) + 8 H2O(l) ⇄ 2 SO42- + Fe2+ + 16 H+ + 14 e- -85.950 -83.616

- 15 -


Figure 2 Predicted pH and Eh (vs. SHE) values on (a) groundwater and (b) bentonite porewater

compositions simulated in H12 29) using the JAEA-TDBs before (JAEA-2014 4)) and after

(present) updating

-500

-400

-300

-200

-100

5 6 7 8 9 10 11

E h v

s. S

HE

(mV)

pH

(b) Bentonite porewater

-400

-300

-200

-100

0

FRHP(JAEA-2014)FRHP(present)SRHP(JAEA-2014)SRHP(present)FRLP(JAEA-2014)

FRLP(present)SRLP(JAEA-2014)SRLP(present)MRNP(JAEA-2014)MRNP(present)

Eh

vs. S

HE

(mV)

(a) Groundwater

- 16 -


Table 7 Predicted groundwater (GW) compositions simulated in H12 29) using the JAEA-TDBs

before (JAEA-2014) and after (present) updating

FRHP-GW SRHP-GW FRLP-GW SRLP-GW MRNP-GW

JAEA-2014 4) presentJAEA-2014 4) present

JAEA-2014 4) present



pH 8.5 10.1 7.9 7.2 5.7 6.1 5.9 5.9 7.0 5.9 Eh (mV) -282 -410 -304 -278 -157 -200 -156 -161 -242 -194

Al 3.5 10-7 2.9 10-7 3.1 10-9 6.6 10-9 2.2 10-5 1.5 10-6 3.3 10-8 3.3 10-10 6.2 10-10 3.0 10-9

B 2.9 10-4 2.9 10-4 1.7 10-3 1.7 10-3 2.9 10-4 2.9 10-4 1.7 10-3 1.7 10-3 1.7 10-3 1.7 10-3

Br –– –– 5.3 10-4 5.3 10-4 –– –– 5.3 10-4 5.3 10-4 5.3 10-4 5.3 10-4C 3.5 10-3 3.8 10-3 3.5 10-2 3.7 10-2 3.6 10-2 3.6 10-2 4.1 10-2 4.2 10-2 2.2 10-1 2.3 10-1

Ca 1.1 10-4 1.1E-05 3.1 10-4 2.4E-03 1.0 10-4 1.1 10-5 2.8 10-2 4.6 10-2 3.7 10-4 1.2 10-2Cl 1.0 10-10 1.0 10-10 5.9 10-1 5.9 10-1 1.0 10-10 –– 5.9 10-1 5.9 10-1 3.0 10-1 3.0 10-1F 5.4 10-5 5.4 10-5 1.0 10-4 1.0 10-4 5.4 10-5 5.4 10-5 1.0 10-4 1.0 10-4 1.0 10-4 1.0 10-4

Fe 9.6 10-10 1.5 10-9 3.9 10-8 3.9 10-8 3.1 10-8 2.0 10-7 3.9 10-8 3.9 10-8 2.0 10-8 2.0 10-8

I –– –– 2.0 10-4 2.0 10-4 –– –– 2.0 10-4 2.0 10-4 2.0 10-4 2.0 10-4

K 6.1 10-5 4.0 10-6 1.1 10-2 3.9 10-4 5.9 10-5 4.0 10-6 1.1 10-2 1.1 10-2 8.8 10-2 7.1 10-3Mg 5.0 10-5 5.0 10-5 2.1 10-4 1.2 10-4 5.0 10-5 5.0 10-5 1.9 10-2 2.3 10-3 2.5 10-4 6.2 10-4

N 2.3 10-5 2.3 10-5 5.2 10-3 5.2 10-3 2.3 10-5 2.3 10-5 5.2 10-3 5.2 10-3 5.2 10-3 5.2 10-3Na 3.5 10-3 6.8 10-3 6.2 10-1 6.2 10-1 3.5 10-3 6.8 10-3 5.0 10-1 5.0 10-1 3.1 10-1 3.1 10-1P 2.9 10-6 2.9 10-6 2.6 10-7 2.6 10-7 2.9 10-6 2.9 10-6 2.6 10-7 2.6 10-7 2.6 10-7 2.6 10-7

S 1.1 10-4 1.4 10-4 3.0 10-2 3.0 10-2 6.3 10-8 4.1 10-7 3.0 10-2 3.0 10-2 1.5 10-2 1.5 10-2Si 3.4 10-4 1.2 10-3 2.7 10-4 2.6 10-4 3.2 10-4 3.0 10-4 2.7 10-4 2.5 10-4 2.9 10-4 2.7 10-4

Unit of aqueous concentration: mol kg-1.

Table 8 Predicted bentonite porewater (PW) compositions simulated in H12 29) using the JAEA-

TDBs before (JAEA-2014) and after (present) updating

FRHP-PW SRHP-PW FRLP-PW SRLP-PW MRNP-PW

JAEA-2014 4) presentJAEA-2014 4) present




pH 8.4 8.5 7.8 7.5 7.6 7.7 6.1 6.4 6.3 6.3 Eh (mV) -277 -285 -310 -303 -276 -302 -176 -215 -199 -217

Al 3.5 10-7 2.9 10-7 3.1 10-9 6.6 10-9 2.2 10-5 1.5 10-6 3.2 10-8 3.2 10-10 6.2 10-10 3.0 10-9

B 2.9 10-4 2.9 10-4 1.7 10-3 1.7 10-3 2.9 10-4 2.9 10-4 1.7 10-3 1.7 10-3 1.7 10-3 1.7 10-3Br –– –– 5.3 10-4 5.3 10-4 –– –– 5.3 10-4 5.3 10-4 5.3 10-4 5.3 10-4

C 1.6 10-2 1.4 10-2 2.3 10-2 2.4 10-2 5.6 10-2 5.4 10-2 3.3 10-2 2.0 10-2 1.9 10-1 2.1 10-1Ca 4.3 10-5 4.6 10-5 1.4 10-2 1.4 10-2 1.3 10-4 1.3 10-4 1.9 10-2 1.8 10-2 3.9 10-3 4.3 10-3

Cl 1.0 10-10 1.0 10-10 5.9 10-1 5.9 10-1 1.0 10-10 –– 5.9 10-1 5.9 10-1 3.0 10-1 3.0 10-1F 5.4 10-5 5.4 10-5 1.0 10-4 1.0 10-4 5.4 10-5 5.4 10-5 1.0 10-4 1.0 10-4 1.0 10-4 1.0 10-4

Fe 2.0 10-9 1.2 10-7 2.1 10-7 2.0 10-4 2.5 10-7 2.7 10-5 2.6 10-4 1.4 10-2 1.3 10-4 2.4 10-2

I –– –– 2.0 10-4 2.0 10-4 –– –– 2.0 10-4 2.0 10-4 2.0 10-4 2.0 10-4

K 1.2 10-4 1.2 10-4 3.4 10-3 2.1 10-3 1.9 10-4 1.8 10-4 3.4 10-3 3.4 10-3 8.0 10-3 1.6 10-3

Mg 3.9 10-6 3.5 10-6 1.5 10-3 1.2 10-3 1.0 10-5 9.7 10-6 4.5 10-3 1.4 10-3 5.7 10-4 4.0 10-4

N 2.3 10-5 2.3 10-5 5.1 10-3 5.1 10-3 2.3 10-5 2.3 10-5 5.1 10-3 5.1 10-3 5.1 10-3 5.1 10-3

Na 2.9 10-2 2.7 10-2 5.7 10-1 5.6 10-1 4.5 10-2 4.4 10-2 5.4 10-1 5.2 10-1 3.1 10-1 2.9 10-1

P 2.9 10-6 2.9 10-6 2.6 10-7 2.6 10-7 2.9 10-6 2.9 10-6 2.6 10-7 2.6 10-7 2.6 10-7 2.6 10-7S 1.1 10-4 1.4 10-4 7.5 10-9 9.2 10-9 2.6 10-9 8.2 10-9 3.3 10-10 1.2 10-9 5.0 10-10 1.4 10-9

Si 3.4 10-4 3.3 10-4 2.7 10-4 2.6 10-4 3.2 10-4 3.0 10-4 2.7 10-4 2.5 10-4 2.9 10-4 2.7 10-4

Unit of aqueous concentration: mol kg-1.

- 17 -


4.2 Solubility of Radionuclides Predicted in FRHP and SRHP type Bentonite Porewaters

Predicted solubility values for important elements for performance assessment of HLW and TRU

waste disposal in the FRHP and SRHP type porewater are shown in Figures 3 and 4, respectively. The

author used three stages of JAEA-TDB for the prediction; 1) JAEA-2014 (including Y-TDB for

geochemical calculations) 4), 2) update from JAEA-2014 only for the important elements (zirconium,

ISA complexes and M2+-UO22+-CO32- complexes) (RNs update) for comparison of dominant species,

and 3) the present update (both RNs and GC update). Total aqueous concentration (i.e. concentration

limit) and mainly contributed species (more than 1 mol% in total concentration) are listed in the tables.

The contribution of ISA has not been checked in the calculation because there are no ISA in the bentonite

porewaters.

Detail of solubility of the important elements and contribution of major aqueous species predicted

in FRHP and SRHP type groundwaters using the three stages of JAEA-TDB with PHREEQC 7) has been

listed in Tables 9 - 46. The author have found some significant change of predicted solubility values as

follows.

– Solubility of zirconium has been decreased after RNs update as shown in Tables 9 and 10.

Contribution of polynuclear hydrolysis species (Zr4(OH)16(aq)) has been disappeared and that of

neutral-mononuclear hydrolysis species (Zr(OH)4(aq)) has been decreased. On the other hand,

contribution of carbonate and mixed carbonate-hydoxo complexes (Zr(CO3)44- and Zr(CO3)2(OH)22-,

respectively) has been arised. Therefore, decrease of zirconium solubility in FRHP type bentonite

porewater (shown in Table 9) has been suppressed around two order of magnitude due to aqueous

carbonate concentration. In contrast, solubility of zirconium in SRHP type bentonite porewater has

been drastically decreased when only RNs update due to low carbonate concentration, but

moderately decreased when both RNs and GC update due to the increase of carbonate contributions

as shown in Table 10.

– Solubility of uranium in FRHP type bentonite porewater is shown in Table 11. It is found that the

predicted solubility has been slightly increased due to additional contribution of CaUO2(CO3)32-. In

contrast, predicted solubility of uranium in SRHP type bentonite porewater has not been chanted

due to less contribution of carbonate complexes, but drastically increased when both RNs and GC

update due to the increase of carbonate contributions (similar to that for zirconium) as shown in

Table 12.

– The contribution of silicate complexes for trivalent actinides and samarium (MSiO(OH)32+; M: Sm,

Ac, Pu, Am and Cm) has been drastically decreased due to the newly added contribution of silicate

complex NaH3SiO4(aq) in the present update, especially for the SRHP type bentonite porewater, as

shown in Tables 36 and 38.

- 18 -


– The increase of carbonate contributions in the SRHP type groundwater as mentioned above

increases the contribution of carbonate complexes in the SRHP type bentonite porewater for

strontium; actinium; samarium, americium and curium; thorium; neptunium and plutonium as

shown in Tables 20; 36; 38; 40; 44 and 46, respectively, as well as for zirconium and uranium.

– The redox potential (Eh) for prediction of Pd(OH)2(am) in the SRHP type bentonite porewater has

been significantly chanted due to changing converged pH and Eh values. The discrepancies of these

values, however, are significant in the previous calculations (JAEA-2014 and “JAEA-2014 + RNs

update”); therefore the present (both RNs and GC update) calculation are more reasonable.

Other solubility values have not been significantly changed among the calculations 1) through 3)

due to no significant updates on thermodynamic data.

10-10

10-8

10-6

10-4

10-2

100

Co Ni Se Sr Zr Nb Mo Tc Pd Sn Sm Pb Ra Ac Th Pa U Np Pu AmCm

JAEA-2014only RNs updatepresent (both RNs and GC update)

solu

bilit

y [m

ol.l-

1 ]


FRHP type bentonite porewater using three stages of JAEA-TDB (see text for detail)

- 19 -


10-10

10-8

10-6

10-4

10-2

100

Co Ni Se Sr Zr Nb Mo Tc Pd Sn Sm Pb Ra Ac Th Pa U Np Pu AmCm

JAEA-2014only RNs updatepresent (both RNs and GC update)

solu

bilit

y [m

ol.l-

1 ]


SRHP type bentonite porewater using three stages of JAEA-TDB (see text for detail)


contribution of aqueous species in FRHP type bentonite porewater

1) JAEA-2014 4) 2) JAEA-2014 + RNs update 3) present (both RNs and GC update)species c (mol/kg) species c (mol/kg) species c (mol/kg)

Zr(total) 1.1 10-4 Zr(total) 1.1 10-6 Zr(total) 1.0 10-6 Zr4(OH)16(aq) 2.7 10-5 Zr(CO3)2(OH)22- 6.3 10-7 Zr(CO3)2(OH)22- 6.2 10-7 Zr(OH)4(aq) 3.7 10-6 Zr(CO3)44- 4.4 10-7 Zr(CO3)44- 4.2 10-7


contribution of aqueous species in SRHP type bentonite porewater


Zr(total) 1.1 10-4 Zr(total) 6.7 10-10 Zr(total) 2.6 10-6 Zr4(OH)16(aq) 2.7 10-5 Zr(CO3)2(OH)22- 5.9 10-10 Zr(CO3)44- 1.9 10-6 Zr(OH)4(aq) 3.7 10-6 Zr(OH)4(aq) 7.8 10-11 Zr(CO3)2(OH)22- 6.9 10-7

Table 11 Predicted solubility of UO2(am) with showing contribution of aqueous species in FRHP type

bentonite porewater


U(total) 4.5 10-6 U(total) 8.0 10-6 U(total) 8.1 10-6 UO2(CO3)34- 4.4 10-6 CaUO2(CO3)32- 4.1 10-6 UO2(CO3)34- 4.3 10-6 UO2(CO3)34- 3.8 10-6 CaUO2(CO3)32- 3.7 10-6

- 20 -


Table 12 Predicted solubility of UO2(am) with showing contribution of aqueous species in SRHP type

bentonite porewater


U(total) 3.2 10-9 U(total) 3.3 10-9 U(total) 4.0 10-6 U(OH)4(aq) 3.1 10-9 U(OH)4(aq) 3.1 10-9 CaUO2(CO3)32- 3.4 10-6 UO2+ 5.3 10-11 CaUO2(CO3)32- 7.6 10-11 Ca2UO2(CO3)3(aq) 3.1 10-7 UO2+ 5.3 10-11 UO2(CO3)34- 1.9 10-7 MgUO2(CO3)32- 4.1 10-8

Table 13 Predicted solubility of β-Co(OH)2 with showing contribution of aqueous species in FRHP

type bentonite porewater


Co(total) 1.8 10-4 Co(total) 1.8 10-4 Co(total) 1.8 10-4 CoCO3(aq) 1.2 10-4 CoCO3(aq) 1.2 10-4 CoCO3(aq) 1.2 10-4 Co2+ 4.1 10-5 Co2+ 4.1 10-5 Co2+ 4.1 10-5 CoHCO3+ 8.7 10-6 CoHCO3+ 8.7 10-6 CoHCO3+ 8.6 10-6 CoOH+ 3.1 10-6 CoOH+ 3.1 10-6 CoOH+ 3.1 10-6

Table 14 Predicted solubility of β-Co(OH)2 with showing contribution of aqueous species in SRHP



Co(total) 3.3 10-4 Co(total) 3.3 10-4 Co(total) 8.3 10-4 CoCl+ 1.6 10-4 CoCl+ 1.6 10-4 Co2+ 3.2 10-4 Co2+ 1.4 10-4 Co2+ 1.4 10-4 CoCl+ 3.0 10-4 CoNH32+ 1.6 10-5 CoNH32+ 1.6 10-5 CoCO3(aq) 1.6 10-4 CoOH+ 5.4 10-6 CoOH+ 5.4 10-6 CoHCO3+ 3.1 10-5

Table 15 Predicted solubility of β-Ni(OH)2 with showing contribution of aqueous species in FRHP



Ni(total) 9.0 10-6 Ni(total) 9.0 10-6 Ni(total) 9.1 10-6 NiCO3(aq) 4.5 10-6 NiCO3(aq) 4.5 10-6 NiCO3(aq) 4.4 10-6 Ni2+ 3.4 10-6 Ni2+ 3.4 10-6 Ni2+ 3.5 10-6 NiHCO3+ 7.8 10-7 NiHCO3+ 7.8 10-7 NiHCO3+ 7.7 10-7 NiOH+ 1.5 10-7 NiOH+ 1.5 10-7 NiOH+ 1.5 10-7

- 21 -


Table 16 Predicted solubility of β-Ni(OH)2 with showing contribution of aqueous species in SRHP



Ni(total) 5.9 10-5 Ni(total) 5.9 10-5 Ni(total) 9.1 10-5 Ni2+ 4.8 10-5 Ni2+ 4.8 10-5 Ni2+ 6.2 10-5 NiCl+ 8.2 10-6 NiCl+ 8.2 10-6 NiCl+ 1.1 10-5 NiNH32+ 1.9 10-6 NiNH32+ 1.9 10-6 NiCO3(aq) 9.2 10-6 NiHCO3+ 6.5 10-6

Table 17 Predicted solubility of FeSe2(cr) with showing contribution of aqueous species in FRHP type

bentonite porewater


Se(total) 9.2 10-9 Se(total) 9.2 10-9 Se(total) 9.4 10-9 HSe- 9.2 10-9 HSe- 9.2 10-9 HSe- 9.4 10-9

Table 18 Predicted solubility of FeSe2(cr) with showing contribution of aqueous species in SRHP type

bentonite porewater


Se(total) 4.3 10-8 Se(total) 4.3 10-8 Se(total) 3.4 10-8 HSe- 4.3 10-8 HSe- 4.3 10-8 HSe- 3.4 10-8

Table 19 Predicted solubility of SrCO3(strontianite) with showing contribution of aqueous species in

FRHP type bentonite porewater


Sr(total) 6.9 10-6 Sr(total) 6.9 10-6 Sr(total) 7.2 10-6 Sr2+ 6.9 10-6 Sr2+ 6.9 10-6 Sr2+ 6.8 10-6 SrCO3(aq) 4.0 10-7

Table 20 Predicted solubility of SrCO3(strontianite) with showing contribution of aqueous species in

SRHP type bentonite porewater


Sr(total) 5.7 10-4 Sr(total) 5.7 10-4 Sr(total) 8.1 10-5 Sr2+ 5.7 10-4 Sr2+ 5.7 10-4 Sr2+ 7.6 10-5 SrCl+ 4.9 10-6

- 22 -


Table 21 Predicted solubility of Nb2O5(s) with showing contribution of aqueous species in FRHP type

bentonite porewater


Nb(total) 9.4 10-7 Nb(total) 9.4 10-7 Nb(total) 9.4 10-7 Nb(OH)6- 9.2 10-7 Nb(OH)6- 9.2 10-7 Nb(OH)6- 9.2 10-7 Nb(OH)5(aq) 2.0 10-8 Nb(OH)5(aq) 2.0 10-8 Nb(OH)5(aq) 2.0 10-8

Table 22 Predicted solubility of Nb2O5(s) with showing contribution of aqueous species in SRHP type

bentonite porewater


Nb(total) 3.9 10-7 Nb(total) 3.9 10-7 Nb(total) 3.1 10-7 Nb(OH)6- 3.7 10-7 Nb(OH)6- 3.7 10-7 Nb(OH)6- 3.0 10-7 Nb(OH)5(aq) 1.9 10-8 Nb(OH)5(aq) 1.9 10-8 Nb(OH)5(aq) 1.7 10-8

Table 23 Predicted solubility of CaMoO4(cr) with showing contribution of aqueous species in FRHP



Mo(total) 1.7 10-4 Mo(total) 1.7 10-4 Mo(total) 1.8 10-4 MoO42- 1.7 10-4 MoO42- 1.7 10-4 MoO42- 1.8 10-4

Table 24 Predicted solubility of CaMoO4(cr) with showing contribution of aqueous species in SRHP



Mo(total) 2.0 10-5 Mo(total) 2.0 10-5 Mo(total) 1.2 10-5 MoO42- 2.0 10-5 MoO42- 2.0 10-5 MoO42- 1.2 10-5




Tc(total) 4.3 10-9 Tc(total) 4.3 10-9 Tc(total) 4.3 10-9 TcO(OH)2(aq) 3.8 10-9 TcO(OH)2(aq) 3.8 10-9 TcO(OH)2(aq) 3.8 10-9 TcCO3(OH)3- 2.5 10-10 TcCO3(OH)3- 2.5 10-10 TcCO3(OH)3- 2.5 10-10 TcCO3(OH)2(aq) 1.9 10-10 TcCO3(OH)2(aq) 1.9 10-10 TcCO3(OH)2(aq) 1.8 10-10

- 23 -





Tc(total) 3.9 10-9 Tc(total) 3.9 10-9 Tc(total) 4.1 10-9 TcO(OH)2(aq) 3.9 10-9 TcO(OH)2(aq) 3.9 10-9 TcO(OH)2(aq) 3.4 10-9

TcCO3(OH)2 4.3 10-10 TcCO3(OH)3- 2.2 10-10

Table 27 Predicted solubility of Pd(OH)2(am) with showing contribution of aqueous species in FRHP



Pd(total) 8.5 10-8 Pd(total) 8.5 10-8 Pd(total) 8.5 10-8 Pd(OH)2(aq) 8.5 10-8 Pd(OH)2(aq) 8.5 10-8 Pd(OH)2(aq) 8.5 10-8

Table 28 Predicted solubility of Pd(OH)2(am) with showing contribution of aqueous species in SRHP



Pd(total) 1.9 10-4 Pd(total) 1.9 10-4 Pd(total) 5.2 10-4 Pd(NH3)42+ 1.7 10-4 Pd(NH3)42+ 1.7 10-4 Pd(NH3)42+ 5.2 10-4 PdCl42- 1.9 10-5 PdCl42- 1.9 10-5 Pd(NH3)32+ 3.3 10-6 Pd(NH3)32+ 3.3 10-6

Table 29 Predicted solubility of SnO2(am) with showing contribution of aqueous species in FRHP type

bentonite porewater


Sn(total) 6.5 10-7 Sn(total) 6.5 10-7 Sn(total) 6.5 10-7 Sn(OH)4(aq) 3.8 10-7 Sn(OH)4(aq) 3.8 10-7 Sn(OH)4(aq) 3.8 10-7 Sn(OH)5- 2.7 10-7 Sn(OH)5- 2.7 10-7 Sn(OH)5- 2.7 10-7

Table 30 Predicted solubility of SnO2(am) with showing contribution of aqueous species in SRHP type

bentonite porewater


Sn(total) 4.7 10-7 Sn(total) 4.7 10-7 Sn(total) 4.1 10-7 Sn(OH)4(aq) 3.7 10-7 Sn(OH)4(aq) 3.7 10-7 Sn(OH)4(aq) 3.2 10-7 Sn(OH)5- 9.8 10-8 Sn(OH)5- 9.8 10-8 Sn(OH)5- 8.7 10-8

- 24 -





Pb(total) 1.4 10-6 Pb(total) 1.4 10-6 Pb(total) 1.4 10-6 PbCO3(aq) 1.2 10-6 PbCO3(aq) 1.2 10-6 PbCO3(aq) 1.2 10-6 Pb(CO3)22- 2.0 10-7 Pb(CO3)22- 2.0 10-7 Pb(CO3)22- 2.0 10-7




Pb(total) 6.6 10-6 Pb(total) 6.6 10-6 Pb(total) 1.2 10-6 PbCl2(aq) 1.5 10-6 PbCl2(aq) 1.5 10-6 PbCO3(aq) 1.0 10-6 PbCl+ 1.5 10-6 PbCl+ 1.5 10-6 Pb(CO3)22- 8.4 10-8 PbCO3(aq) 1.2 10-6 PbCO3(aq) 1.2 10-6 PbCl+ 2.7 10-8 PbOH+ 1.0 10-6 PbOH+ 1.0 10-6 PbCl2(aq) 2.5 10-8

Table 33 Predicted solubility of RaCO3(cr) with showing contribution of aqueous species in FRHP



Ra(total) 3.4 10-5 Ra(total) 3.4 10-5 Ra(total) 3.5 10-5 Ra2+ 3.4 10-5 Ra2+ 3.4 10-5 Ra2+ 3.4 10-5 RaSO4(aq) 5.6 10-5 RaSO4(aq) 5.6 10-5 RaSO4(aq) 5.4 10-7

Table 34 Predicted solubility of RaCO3(cr) with showing contribution of aqueous species in SRHP



Ra(total) 1.1 10-3 Ra(total) 1.1 10-3 Ra(total) 2.5 10-4 Ra2+ 1.1 10-3 Ra2+ 1.1 10-3 Ra2+ 2.5 10-4




Ac(total) 4.2 10-6 Ac(total) 4.2 10-6 Ac(total) 4.1 10-6 Ac(CO3)2- 3.6 10-6 Ac(CO3)2- 3.6 10-6 Ac(CO3)2- 3.6 10-6 AcCO3+ 3.2 10-7 AcCO3+ 3.2 10-7 AcCO3+ 3.2 10-7 Ac(CO3)33- 2.1 10-7 Ac(CO3)33- 2.1 10-7 Ac(CO3)33- 2.0 10-7 AcSiO(OH)32+ 5.4 10-8 AcSiO(OH)32+ 5.4 10-8 AcSiO(OH)32+ 5.3 10-8

- 25 -





Ac(total) 2.4 10-5 Ac(total) 2.4 10-5 Ac(total) 5.1 10-6 AcSiO(OH)32+ 2.2 10-5 AcSiO(OH)32+ 2.2 10-5 Ac(CO3)2- 3.2 10-6 AcCO3+ 1.3 10-6 AcCO3+ 1.3 10-6 AcCO3+ 1.3 10-6 Ac3+ 3.5 10-7 Ac3+ 3.5 10-7 AcSiO(OH)32+ 4.0 10-7 AcOH2+ 2.8 10-8 AcOH2+ 2.8 10-8 Ac(CO3)33- 1.4 10-7

Table 37 Predicted solubility of MCO3OH·0.5H2O(cr) (M: Sm, Am, Cm) with showing contribution

of aqueous species in FRHP type bentonite porewater


M(total) 2.7 10-8 M(total) 2.7 10-8 M(total) 2.6 10-8 M(CO3)2- 2.3 10-8 M(CO3)2- 2.3 10-8 M(CO3)2- 2.3 10-8 MCO3+ 2.0 10-9 MCO3+ 2.0 10-9 MCO3+ 2.0 10-9 M(CO3)33- 1.3 10-9 M(CO3)33- 1.3 10-9 M(CO3)33- 1.3 10-9 MSiO(OH)32+ 3.4 10-10 MSiO(OH)32+ 3.4 10-10 MSiO(OH)32+ 3.4 10-10

Table 38 Predicted solubility of MCO3OH·0.5H2O(cr) (M: Sm, Am, Cm) with showing contribution

of aqueous species in SRHP type bentonite porewater


M(total) 1.9 10-7 M(total) 1.9 10-7 M(total) 3.2 10-8 MSiO(OH)32+ 1.7 10-7 MSiO(OH)32+ 1.7 10-7 M(CO3)2- 2.1 10-8 MCO3+ 9.2 10-9 MCO3+ 9.2 10-9 MCO3+ 8.2 10-9 M3+ 2.8 10-9 M3+ 2.8 10-9 MSiO(OH)32+ 2.5 10-9 MOH2+ 2.0 10-9 MOH2+ 2.0 10-9 M(CO3)33- 9.1 10-10




Th(total) 1.4 10-7 Th(total) 1.4 10-7 Th(total) 1.4 10-7 Th(CO3)2(OH)22- 1.4 10-7 Th(CO3)2(OH)22- 1.4 10-7 Th(CO3)2(OH)22- 1.3 10-7 Th(CO3)4OH5- 1.6 10-9 Th(CO3)4OH5- 1.6 10-9 Th(CO3)4OH5- 1.5 10-9

- 26 -





Th(total) 1.4 10-9 Th(total) 1.4 10-9 Th(total) 1.5 10-7 Th(OH)4(aq) 1.2 10-9 Th(OH)4(aq) 1.2 10-9 Th(CO3)2(OH)22- 1.5 10-7 Th(CO3)2(OH)22- 1.4 10-10 Th(CO3)2(OH)22- 1.4 10-10 Th(CO3)4OH5- 7.8 10-9

Table 41 Predicted solubility of Pa2O5(s) with showing contribution of aqueous species in FRHP type

bentonite porewater


Pa(total) 9.8 10-10 Pa(total) 9.8 10-10 Pa(total) 9.8 10-10 Pa(OH)5(aq) 9.3 10-10 Pa(OH)5(aq) 9.3 10-10 Pa(OH)5(aq) 9.3 10-10 PaO(OH)2+ 5.0 10-11 PaO(OH)2+ 5.0 10-11 PaO(OH)2+ 5.0 10-11

Table 42 Predicted solubility of Pa2O5(s) with showing contribution of aqueous species in SRHP type

bentonite porewater


Pa(total) 1.1 10-9 Pa(total) 1.1 10-9 Pa(total) 9.7 10-10 Pa(OH)5(aq) 8.9 10-10 Pa(OH)5(aq) 8.9 10-10 Pa(OH)5(aq) 7.7 10-10 PaO(OH)2+ 2.2 10-10 PaO(OH)2+ 2.2 10-10 PaO(OH)2+ 2.0 10-10

Table 43 Predicted solubility of NpO2(am) with showing contribution of aqueous species in FRHP



Np(total) 6.9 10-8 Np(total) 6.9 10-8 Np(total) 6.7 10-8 Np(CO3)2(OH)22- 6.8 10-8 Np(CO3)2(OH)22- 6.8 10-8 Np(CO3)2(OH)22- 6.6 10-8 Np(OH)4(aq) 1.0 10-9 Np(OH)4(aq) 1.0 10-9 Np(OH)4(aq) 1.0 10-9

Table 44 Predicted solubility of NpO2(am) with showing contribution of aqueous species in SRHP



Np(total) 1.0 10-9 Np(total) 1.0 10-9 Np(total) 7.3 10-8 Np(OH)4(aq) 9.7 10-10 Np(OH)4(aq) 9.7 10-10 Np(CO3)2(OH)22- 7.1 10-8 Np(CO3)2(OH)22- 6.0 10-11 Np(CO3)2(OH)22- 6.0 10-11 Np(CO3)44- 1.0 10-9 Np(OH)4(aq) 8.4 10-10

- 27 -


Table 45 Predicted solubility of PuO2(am) with showing contribution of aqueous species in FRHP type

bentonite porewater


Pu(total) 5.7 10-8 Pu(total) 5.7 10-8 Pu(total) 5.6 10-8 Pu(CO3)2(OH)22- 4.9 10-8 Pu(CO3)2(OH)22- 4.9 10-8 Pu(CO3)2(OH)22- 4.8 10-8 Pu(CO3)2- 7.0 10-9 Pu(CO3)2- 7.0 10-9 Pu(CO3)2- 7.0 10-9 PuCO3+ 6.2 10-10 PuCO3+ 6.2 10-10 PuCO3+ 6.3 10-10

Table 46 Predicted solubility of PuO2(am) with showing contribution of aqueous species in SRHP type

bentonite porewater


Pu(total) 4.2 10-8 Pu(total) 4.2 10-8 Pu(total) 3.7 10-7 PuSiO(OH)32+ 3.8 10-8 PuSiO(OH)32+ 3.8 10-8 Pu(CO3)2- 2.0 10-7 PuCO3+ 2.0 10-9 PuCO3+ 2.0 10-9 PuCO3+ 8.0 10-8 Pu3+ 6.2 10-10 Pu3+ 6.2 10-10 PuSiO(OH)32+ 2.5 10-8 PuOH2+ 4.5 10-10 PuOH2+ 4.5 10-10 Pu(CO3)33- 8.9 10-9

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5. Conclusions

The author has completed the integration of two JAEA-TDB; one is a successor of JNC-TDB

used for H12 report, and the other is the TDB for geochemical calculations for use of SUPCRT92

software package. The integration enables to provide more realistic water compositions, especially in

the presence of cementitious materials. Prediction of solubility of zirconium, uranium and some metal

ions in the presence of isosaccharinic acid could be more realistic after the update of thermodynamic

data.

It has been concluded that the author has newly selected equilibrium constants for 408 aqueous

species, compounds and minerals; eliminated those for 55 aqueous species, compounds and minerals;

updated those for 120 aqueous species, compounds and minerals.

Acknowledgements

The author acknowledges Dr. Yasushi Yoshida, NESI Inc., for supporting preparation of text files

on JAEA-TDB and preliminary calculation of chemical composition of groundwaters, bentonite

porewaters and solubility of important elements on HLW and TRU waste disposal in these waters.

- 29 -


References

1. A. Kitamura, K. Fujiwara, R. Doi, Y. Yoshida, M. Mihara, M. Terashima and M. Yui: “JAEA

thermodynamic database for performance assessment of geological disposal of high-level

radioactive and TRU wastes”, JAEA-Data/Code 2009-024, 84 p. (2010).

2. A. Kitamura and Y. Yoshida: “Preparation of Text Files of JAEA-TDB for Geochemical Calculation

Programs”, JAEA-Data/Code 2010-011, 37 p. (2010).

3. A. Kitamura, K. Fujiwara, R. Doi, Y. Yoshida: “Update of JAEA-TDB: Additional selection of

thermodynamic data for solid and gaseous phases on nickel, selenium, zirconium, technetium,

thorium, uranium, neptunium plutonium and americium, update of thermodynamic data on iodine,

and some modifications”, JAEA-Data/Code 2012-006, 65 p. (2012).

4. A. Kitamura, R.

Documents

M –UO 2+ –CO 2- System and Integration 2 3 with …JAEA-Data/Code 2018-018 JAEA-TDB の更新：ジルコニウムおよびイソサッカリン酸錯体の熱力学データの更新，