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TRU廃棄物や高レベル放射性廃棄物の地層処分を対象とした性能評価において、人工バリアであるセメントやベントナイト、天然バリアである岩石中での核種の収着現象は、核種の移行遅延を支配する重要な現象の一つである。収着の程度は一般的に収着分配係数(Kd)によって表され、バリア材や環境条件に応じて大きく変動するため、それぞれの条件でのKdデータを取得し、性能評価解析では関連する不確実性も考慮して収着パラメータ値を設定する必要がある。TRU廃棄物の処分システムでは、高レベル放射性廃棄物で検討されるベントナイトや岩石に加えて、バリア材として利用されるセメント系材料への収着や、一部の廃棄物に含まれる硝酸塩等の化学物質が地下水に溶解して収着に影響を及ぼすことなどを考慮する必要が生じる。本報告書では、このようなTRU廃棄物の処分において考慮すべきバリア材料や、硝酸塩等の影響物質、評価対象核種の組み合わせを対象として、Kdデータをバッチ式収着試験により取得した結果を報告する。バリア材としては、普通ポルトランドセメント硬化体、通水で劣化させた普通ポルトランドセメント硬化体、凝灰岩を対象とし、液性については、蒸留水や模擬海水とバリア材料との平衡液に加え、硝酸塩やアンモニウム塩を含む液性条件を対象とした。元素は、C(有機形態),C(無機形態),Cl,I,Cs,Ni,Se,Sr,Sn,Nb,Am,Thを対象とした。ここで報告する収着データの一部は、TRU廃棄物処分技術検討書の性能評価における核種移行解析に用いたパラメータである核種移行データセット(RAMDA: Radionuclide Migration Datasets)の一部として取得・報告されているものであり、ここでは、これらのデータ取得の方法, 条件, 結果の詳細を報告する。, Sorption of radionuclides in cement and bentonite as engineered barrier materials, and rocks as natural barrier is the one of key processes in the performance assessment of geological disposal of TRU and high-level waste. The magnitude of sorption, expressed normally by a distribution coefficient (Kd), needs to be measured and determined taking into account the properties of barrier materials and geochemical conditions and associated uncertainty in the performance assessment. The basic concept for TRU waste disposal contains cementitious materials as an engineered barrier materials, in addition to bentonite and rock. It is therefore needed to consider the effects of the cement degradation and co-existing substances such as nitrates on radionuclide sorption. This report focused on data acquisition of distribution coefficient (Kd) by batch sorption experiments for the systems coupling barrier material-chemical condition-radionuclides that are needed to consider for the performance assessment of geological disposal of TRU waste. The barrier materials considered are ordinary Portland cement (OPC), degraded OPC and tuff rock. The chemical conditions are distilled water and synthetic seawater equilibrated with OPC and those containing nitrates and ammonium salts, etc. The radionuclides considered are organic carbon, inorganic carbon, Cl, I, Cs, Ni, Se, Sr, Sn, Nb, Am and Th. Although Kd values have been partly reported previously as RAMDA (Radionuclide Migration Datasets) for the performance assessment in the TRU-2 report, these results and addition Kd data are reported with the details of experimental methods and conditions., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2019-021

Sorption behavior of radionuclides (RNs) in buffer materials, rocks and cementitious materials is one of the key processes in a safe geological disposal. This report focuses on updating of JAEA sorption database (JAEA-SDB) as a basis of integrated approach for the performance assessment (PA)-related distribution coefficient (Kd) setting and development of mechanistic sorption models. Kd data and their quality assurance (QA) results were updated by focusing on the following systems as potential needs extracted from our recent activities on the Kd setting and development of mechanistic models, i.e., clay minerals, sedimentary rocks and cementitious materials. As a result, 6,702 Kd data from 60 references were added and the total number of Kd values in JAEA-SDB reached 69,679. The QA/classified Kd data reached about 72% for all Kd data in JAEA-SDB., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2019-022

現在、原子力発電環境整備機構(NUMO)と原子力機構(JAEA)の双方で、地層処分の安全評価手法の開発を進めている。これら安全評価に資するため、国内外の最新の知見を踏まえたパラメータ設定手法の構築を、NUMOとJAEAで共同研究として実施している。本報では、この共同研究の一環として実施した、収着・拡散データベースの拡充のための国内外の最新の収着・拡散データの調査と信頼度評価の結果を報告する。今回の調査では、堆積岩とセメント系材料を中心に調査と信頼度評価を行い、収着データとしては、文献数19件、データ数1、746件、拡散データとしては、文献数25件、データ数593件分について、収着・拡散データベースの中で利用可能な形式でデータを整備した。, NUMO and JAEA have developed the methodology of post-closure safety assessment for the geological disposal. For this purpose, NUMO and JAEA have conducted a collaborative research project for developing the safety assessment methodology based on international state of the art knowledge. The present report focuses on investigation of sorption and diffusion data reported and their QA evaluation for updating sorption and diffusion database (SDB and DDB) as the collaborative research project between NUMO and JAEA. This report includes sorption and diffusion data for mainly sedimentary rocks and cement materials. As a result, 1,746 sorption data from 19 references and 593 diffusion data from 25 references were extracted and prepared in the datasheet of SDB and DDB., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2017-014

Sorption and diffusion of radionuclides in buffer materials (bentonites), rocks and cementitious materials are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in these barrier materials is expected to be diffusion-controlled and retarded by sorption processes. It is therefore necessary to understand the sorption and diffusion processes and develop databases compiling reliable data and mechanistic/predictive models, so that reliable parameters can be set under a variety of geochemical conditions relevant to performance assessment (PA). The present report focuses on updating of the sorption database (JAEA-SDB) as basis of integrated approach for PA-related Kd setting and mechanistic sorption model development. This includes an overview of database structure and contents. Kd data and their QA results are updated by focusing our recent activities on the Kd setting and mechanistic model development. As a result, 4,256 Kd data from 30 references were added, total number of Kd values in the JAEA-SDB reached about 63,000. The QA/classified Kd data reached about 69% for all Kd data in JAEA-SDB. The updated JAEA-SDB is expected to make it possible to obtain quick overview of the available data, and to have suitable access to the respective data for PA-related Kd setting in effective, traceable and transparent manner., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2017-016

放射性廃棄物地層処分の性能評価において、放射性核種の緩衝材(ベントナイト)及び岩石中での収着・拡散現象は、その移行遅延を支配する重要な現象である。日本原子力研究開発機構では、ベントナイト及び岩石を対象として、収着・拡散パラメータに関するデータベース開発を進めている。本報告は、今後の性能評価における最新の知見に基づく拡散パラメータ設定に資するため、拡散データベース(JAEA-DDB)に対する最新データの導入・更新について報告する。はじめにJAEA-DDBの現状として、データベースの構造、これまでに拡充してきたデータの分析評価に係る機能拡充等の概要をまとめる。今回の更新において、主にベントナイト, 花崗岩, 泥岩系を中心とした国内外の221の文献から約3,500件の拡散データ(De, Da)が追加され、JAEA-DDBに含まれる拡散データは約5,000件となった。今回更新されたJAEA-DDBによって、国内外の最新の拡散データを含む実測データ群から、拡散パラメータ設定の際に参照すべきデータの適切な選定が、一層の効率性, 追跡性, 透明性をもって可能となると考えられる。, Sorption and diffusion of radionuclides in buffer materials (bentonite) and rocks are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in these barrier materials is expected to be diffusion-controlled and retarded by sorption processes. Japan Atomic Energy Agency (JAEA) has developed databases of sorption and diffusion parameters in bentonites and rocks. The present report focuses on updating of the diffusion database (JAEA-DDB) as basis of PA-related parameter setting. This includes an overview of database structure, contents and functions including additional data evaluation function. The diffusion data are updated by focusing on bentonites, granites and mudstones related to our recent PA activities. As a result, about 3,500 data from 221 references were added, total number of diffusion data in the JAEA-DDB reached about 5,000. The updated JAEA-DDB is expected to make it possible to obtain quick overview of the available data, and to have suitable access to the respective data for PA-related diffusion parameter setting in effective, traceable and transparent manner., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2015-027

Sorption and diffusion of radionuclides in buffer materials and rocks are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in this barrier is expected to be diffusion-controlled and retarded by sorption processes. For this purpose, Japan Atomic Energy Agency has developed databases of sorption and diffusion parameters in buffer materials and rocks. The present report focuses on developing and updating of the sorption database as basis of integrated approach for PA-related Kd setting and mechanistic sorption model development. This includes an overview of database structure, contents and functions including additional data evaluation function focusing on multi-parameter dependence, operating method, PA-related applications of the web-based JAEA-SDB. Kd data and their QA results are updated by focusing our recent activities on the Kd setting and mechanistic model development. As a result, 11,206 Kd data from 81 references are added, total Kd values in the JAEA-SDB are about 58,000. The QA/classified Kd data are about 39% for all Kd data in JAEA-SDB. The updated JAEA-SDB is expected to make it possible to obtain quick overview of the available data, and to have suitable access to the respective data for PA-related Kd setting in effective, traceable and transparent manner., Sorption and diffusion of radionuclides in buffer materials and rocks are the key processes in the safe geological disposal of radioactive waste, because migration of radionuclides in this barrier is expected to be diffusion-controlled and retarded by sorption processes. For this purpose, Japan Atomic Energy Agency has developed databases of sorption and diffusion parameters in buffer materials and rocks. The present report focuses on developing and updating of the sorption database as basis of integrated approach for PA-related Kd setting and mechanistic sorption model development. This includes an overview of database structure, contents and functions including additional data evaluation function focusing on multi-parameter dependence, operating method, PA-related applications of the web-based JAEA-SDB. Kd data and their QA results are updated by focusing our recent activities on the Kd setting and mechanistic model development. As a result, 11,206 Kd data from 81 references are added, total Kd values in the JAEA-SDB are about 58,000. The QA/classified Kd data are about 39% for all Kd data in JAEA-SDB. The updated JAEA-SDB is expected to make it possible to obtain quick overview of the available data, and to have suitable access to the respective data for PA-related Kd setting in effective, traceable and transparent manner., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2015-028

原子力機構(JAEA)がこれまで蓄積してきた技術やノウハウを、原子力発電環境整備機構(NUMO)が今後行う精密調査地区の選定等の処分事業に適用できるよう、実施主体の視点に沿って実用化を図っていくための具体的な考え方と進め方を策定すること等を目的として、2011年度よりJAEAとNUMOは以下の3つのテーマについて共同研究を進めている。(1)水理の観点からみた母岩の適性を評価する方法に関する検討: 水理地質構造モデル構築手法の事例調査に基づいて、得られた知見を評価ツリーとして整理し、モデルの不確実性やそれらの評価項目への影響等についての検討を行った。(2)シナリオの構築方法に関する検討: 状態設定手順を実務的な観点から、さらに見直すとともに、セメント影響とガラス溶解挙動について、知見の体系的な整理と不確実性の影響について解析的検討を行った。(3)核種移行パラメータの設定方法に関する検討: 母岩の分配係数を対象に、国内外の事例調査をもとに複数の設定手法を整理し、堆積岩及び花崗岩への適用を通じ妥当性や課題を確認した。溶解度について、溶解度制限固相の決定を含む設定手法を検討し、主要核種への適用を通じ妥当性や課題を確認した。, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2014-030

JAEA has developed the setting approaches of sorption parameter (Kd) for site-specific conditions, to derive reliable parameter for performance assessment (PA) of geological disposal. These approaches include any transferring procedures from experimental conditions to PA conditions through expert judgments, semi-quantitative estimation procedures and thermodynamic sorption models (TSMs). The present report focused on illustrating a range of example calculations regarding the derivation of Kd values and their uncertainties based on semi-quantitative estimation procedures and TSMs. The Kd values of four key radionuclides, Cs, Ni, Am and Th were derived for Horonobe mudstone systems. These Kd-setting exercises allowed to estimate the magnitude of sorption under the site-specific conditions, and to identify some critical gaps in the existing data and process understanding. The possibilities of extending such approaches to further rock types including granitic rocks were also discussed., JAEA has developed the setting approaches of sorption parameter (Kd) for site-specific conditions, to derive reliable parameter for performance assessment (PA) of geological disposal. These approaches include any transferring procedures from experimental conditions to PA conditions through expert judgments, semi-quantitative estimation procedures and thermodynamic sorption models (TSMs). The present report focused on illustrating a range of example calculations regarding the derivation of Kd values and their uncertainties based on semi-quantitative estimation procedures and TSMs. The Kd values of four key radionuclides, Cs, Ni, Am and Th were derived for Horonobe mudstone systems. These Kd-setting exercises allowed to estimate the magnitude of sorption under the site-specific conditions, and to identify some critical gaps in the existing data and process understanding. The possibilities of extending such approaches to further rock types including granitic rocks were also discussed., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2012-044

本報告では、TRU廃棄物等を含む多様な低レベル放射性廃棄物の処分、さらには今般の福島第一原子力発電所の事故にも関連した表層環境中の核種移行評価への活用も念頭に、セメント材料系,土壌系の分配係数データを中心にデータの拡充を行った。セメント系と土壌系については既往のデータベースも活用しつつ、JAEA-SDBのデータベース構造に整合させつつ導入を図った。また、ベントナイト系,粘土鉱物系や岩石系など、従来より進めているパラメータ設定やモデル開発と関連する最新データの拡充も併せて行った。今回の更新において、334の文献から約16,000件のKdデータを追加し、JAEA-SDBに含まれる文献数は684, Kdデータ数は約46,000件となった。今回更新されたJAEA-SDBによって、より多様な放射性廃棄物等の処分検討において、有効なデータの抽出や核種移行パラメータの設定が可能となると考えられる。, The present report focuses on updating of the sorption database (JAEA-SDB) by adding Kd data for various systems including soil and cement systems, to apply JAEA-SDB for the PA-related Kd setting for disposal of low level radioactive wastes including TRU wastes and the evaluation of radionuclide transport in surface soil systems. The updated data includes Kd data for soil and cement systems extracted from mainly previous published database, and Kd data related to our recent activities on the Kd setting and mechanistic model development. As a result, 16,000 Kd data from 334 references are added, total Kd values in the JAEA-SDB are about 46,000. The updated JAEA-SDB is expected to make it possible to obtain quick overview of the available data, and to have suitable access to the respective data for the performance assessment of various types of radioactive waste., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2011-022

Sorption of radionuclides in bentonites and rocks is one of the key processes in the safe geological disposal of radioactive waste. JAEA has developed sorption database (JAEA-SDB) which includes extensive compilation of sorption Kd data. JAEA has been continuing to update the SDB in view of potential future data needs, focusing on assuring the quality level and practical applications to Kd-setting for the geological environment. In this report, the QA/classification of selected entries in the JAEA-SDB, focusing on key radionuclides (Th, Np, Am, Se and Cs) sorption on tuff existing widely in geological environment, was done following the approach/guideline defined in our previous report. As a result, the reliability of 560 Kd values was evaluated and classified. This classification scheme is expected to make it possible to obtain quick overview of the available data from the SDB, and to have suitable access to the respective data for Kd-setting in PA., Sorption of radionuclides in bentonites and rocks is one of the key processes in the safe geological disposal of radioactive waste. JAEA has developed sorption database (JAEA-SDB) which includes extensive compilation of sorption Kd data. JAEA has been continuing to update the SDB in view of potential future data needs, focusing on assuring the quality level and practical applications to Kd-setting for the geological environment. In this report, the QA/classification of selected entries in the JAEA-SDB, focusing on key radionuclides (Th, Np, Am, Se and Cs) sorption on tuff existing widely in geological environment, was done following the approach/guideline defined in our previous report. As a result, the reliability of 560 Kd values was evaluated and classified. This classification scheme is expected to make it possible to obtain quick overview of the available data from the SDB, and to have suitable access to the respective data for Kd-setting in PA., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2010-026

For reliable parameter setting in performance assessment of geological disposal, JAEA has developed the integrated sorption and diffusion (ISD) model/database in bentonite systems. The main goal of the mechanistic model/database development is to provide a tool for a consistent explanation, prediction, and uncertainty assessment. This report focuses on developing the thermodynamic sorption model (TSM) including selection of model design and surface species, and on the quantification and handling of model uncertainties, based on illustrating by example of Ni sorption on montmorillonite/bentonite. Two fundamentally different approaches are presented and compared for representing TSM uncertainties: (1) TSM parameter uncertainties based on optimization routines and statistical procedure, (2) overall error estimated by direct comparison of modeled and experimental Kd values. The overall error in Kd is viewed as the best representation of model uncertainty in ISD model/database development., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2010-052

JAEA has developed sorption database (SDB) compiling Kd data in buffer material and rock, which is key parameter for performance assessment (PA) of the geological disposal. The present report focuses on developing and updating of the JAEA-SDB as basis of integrated approach for PA-related Kd setting. This includes an overview of database structure, contents and functions including additional data evaluation function focusing on multi-parameter dependence, operating method, PA-related applications of the web-based SDB. Kd data and their QA results are updated by focusing our recent activities on the Kd setting and mechanistic model development. As a result, total Kd values in the SDB are about 28,540, and QA/classified Kd data are about 39 % for all Kd data. The updated JAEA-SDB is expected to make it possible to obtain quick overview of the available data, and to have suitable access to the respective data for PA-related Kd setting in effective, traceable and transparent manner., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2010-031

地層処分安全評価に資することを目的とした、ベントナイト/モンモリロナイトを対象とした統合収着・拡散モデル及びデータベースのプロトタイプ(ISD2009)を構築した。熱力学的収着モデルは、1サイト表面錯体(拡散層)モデルと1サイトイオン交換モデルを組合せた比較的単純なモデルを適用し、表面化学及び核種収着に関するモデルパラメータを、pH,塩濃度,炭酸等の主要な環境条件の依存性を含む信頼性の高い既往文献データに基づき、一貫性のある方法で構築した。さらに、均質な間隙構造と電気二重層に基づく拡散モデル,収着モデルとの統合化モデルを構築し、圧縮モンモリロナイト中の塩濃度や炭酸影響を含む信頼性の高い収着・拡散データへ適用することで検証を行った。収着/拡散/統合モデルのそれぞれにおいて、随伴鉱物の溶解反応等を含むベントナイト間隙水化学モデルを考慮しつつ、モンモリロナイト系で構築したモデル/パラメータをベントナイト系へ適用し、その妥当性を確認した。ここで検討対象としたCs, Np(V), Ni, Am等の核種に対する一連のモデル/パラメータを、ISD2009データベース/評価ツールとして構築し、今後の安全評価における活用法を提示した。, This report presents the prototype model/database for integrated sorption and diffusion (ISD2009) in bentonite systems as basis for performance assessment (PA) of geological disposal. The sorption model is based on a relatively simple 1-site surface complexation/diffuse layer model in combination with 1-site ion exchange model. The model parameters for surface chemistry/sorption are evaluated based on existing datasets for Na-montmorillonite, which covers key geochemical conditions, in consistent way. The diffusion model based on homogeneous pore structure and electrical double layer theory was developed and coupled with batch-based sorption model, then was validated by using data in compacted montmorillonite. The sorption and diffusion models were also tested by applying data in bentonite systems. The model and related parameters developed for key radionuclides such as Cs, Np(V), Ni, Am, etc. are integrated to ISD2009 database, which could be useful in future PA exercise., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2009-069

Sorption of radionuclides in bentonites and rocks is one of the key processes in the safe geological disposal of radioactive waste. Japan Atomic Energy Agency (JAEA) has developed sorption database (JAEA-SDB) which includes extensive compilation of sorption Kd data by batch experiments, extracted from published literatures. In this report, the QA/classification of selected entries in the JAEA-SDB, focusing granite rocks which are related to reference systems in H12 PA and possible applications in the context of URL activities, and Fe-oxide/hydroxide, Al-oxide/hydroxide existing widely in geological environment, was done following the approach/guideline defined in our previous report. As a result, the reliability of 1,373 Kd values was evaluated and classified. This classification scheme is expected to make it possible to obtain quick overview of the available data from the SDB, and to have suitable access to the respective data for Kd-setting in PA., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2009-021

地層処分の安全評価において、人工バリアである緩衝材や天然バリアである岩石中での核種移行を評価するうえで重要となる収着分配係数及び拡散係数データについて、データ信頼度情報の活用,パラメータ設定へのデータベースの効果的な適用などを念頭に、これまで整備してきた収着及び拡散データベースを発展させ、Webアプリケーションによる収着・拡散データベースシステム(JAEA-SDB/DDB)を構築した。新たに整備した収着・拡散データベースシステムの活用法について、今回拡充した信頼度情報,パラメータ推定等の機能の例示をしつつ、パラメータ設定等への効果的なデータベースの活用法を提示した。この収着・拡散データベースによって、今後の性能評価における核種移行パラメータ設定の際の、関連するデータの全体像の把握,参照すべき信頼性の高いデータの効率的な抽出,現象論的モデル化の効果的検討などが、一層の効率性,追跡性及び透明性のある形で可能となる。, Japan Atomic Energy Agency (JAEA) has been developing databases of sorption and diffusion parameters in buffer material and rock, which are key parameters for safety assessment of the geological disposal. The new web-based sorption and diffusion database system (JAEA-SDB/DDB) has been developed to utilize quality assuring procedure and to allow effective application for parameter setting, based on the existing database. In the present report, practical examples were illustrated regarding the applicability of the database system to the parameter setting by using additional functions such as QA information and parameter estimation. This database system is expected to make it possible to obtain quick overview of the available data from the database, and to have suitable access to the respective data for parameter-setting for performance assessment and parameter-deriving for mechanistic modeling in traceable and transparence manner., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2008-034

鉄とベントナイト(スメクタイト)の相互作用にかかわる知見を拡充するため、約10年間、室温で、蒸留水を用いて鉄粉とクニピアFを重量比1の条件で静置されていた試験試料を対象に、試験後の固相分析を行い、スメクタイトの変質の有無を調査した。主な結果を以下にまとめる。(1)試験後のベントナイトは、鉄との相互作用に伴い、灰緑色あるいは灰黒色に変色した。また試験溶液のpH, Ehは、試験前に比べて、アルカリ性,還元性に変化した(pH11.5程度,Eh -284mV vs.SHE)。(2)試験後固相(灰緑色及び灰黒色試料)のXRD分析,SEM及びTEM観察の結果、スメクタイトの変質を示唆する傾向は認められず、試験前のNa型スメクタイトが残存していると推定された。(3)これまでに考えられている鉄共存下におけるスメクタイトの変質メカニズムを参照しつつ、今回の分析結果について考察し、スメクタイトに著しい変化が生じなかった要因を検討した。また、試験後溶液の分析結果をもとに、変質生成物の安定性にかかわる熱力学的な検討を試みた。, For the better understanding of phenomena caused by iron-bentonite(smectite) interactions, experimental samples conducted over a period of 10 years at room temperature with mixture of distilled water, iron and bentonite (an iron/bentonite mass ratio of 1) were analyzed to identify the alteration behavior of smectite. Major results are summarized below. (1)The color of bentonite changed to grey-green or grey-black with interaction of iron material. The pH and Eh values of solution after the experiment also changed to more alkaline and reducing (pH around 11.5, Eh -284 mV vs. SHE) comparing with the initial condition. (2)Results of X-ray diffraction (XRD) analysis, Scanning Electron Microphotograph (SEM) and Transmission Electron Microphotograph (TEM) observation suggested that no alteration was occurred and the initial Na-type smectite would be remained., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2009-039

これまで鉄-ベントナイト相互作用に関して、緩衝材の長期安定性には顕著な影響を与えないと評価されてきた。しかし近年、80circCにおける鉄粉と混合したスメクタイトが非膨潤性粘土鉱物に変質するという、緩衝材長期安定性に影響を与える可能性がある現象が報告された。また、これまでの処分概念よりも人工バリア中で使用される鉄の量が多い代替処分概念も検討されており、緩衝材の長期安定性に及ぼす鉄の影響が大きくなる可能性が出てきた。そこで、本報告書では鉄-ベントナイト相互作用のうち、処分環境で発生する可能性のある現象として、イオン型の変化(Fe2+型化),鉱物学的変質,腐食生成物によるセメンテーションについて、最新の知見をふまえて緩衝材の長期安定性に与える影響について再評価を行った。, The iron-bentonite interaction was assessed no significant effect for long term stability of buffer material. But recently, smectite alteration for non-swelling mineral such as berthierin at iron-rich environment was reported. This report wraps up the recent study and assess for the effect of iron-bentonite interaction for long term stability of buffer materials. In this report processes for candidate under repository condition were considered following three phenomena, ion-type changing from Na+-type bentonite to Fe2+-type, mineralogical alteration for non-swelling minerals and cementation caused by corrosion products., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2008-073

圧縮ベントナイト中での炭素鋼の長期的な腐食挙動を評価するため、窒素雰囲気下において人工海水及び人工地下水を用い、50circC及び80circCでの10年間に渡る浸漬試験が行われた。本調査では、この浸漬試験後の圧縮ベントナイトを対象とし、鉄-ベントナイト相互作用によるベントナイトの変質挙動を調査した。これまでに、鉄共存下でのベントナイトの変質挙動を把握するため、温度,溶液条件及び試験期間等を変え、バッチ系での試験を実施してきた。それらの結果では、初期のNa型スメクタイトのFe型化や微量の非膨潤性粘土鉱物への変化など、何らかの変化が認められた。しかしながら、今回調査を行った圧縮系での試験後試料では、圧縮ベントナイトへの鉄の移行は確認されたものの、初期のNa型スメクタイトに変化は生じていないと推定された。したがって、処分環境のような圧縮系における鉄-ベントナイト相互作用による影響を評価するうえでは、バッチ系での試験結果をそのまま適用するのではなく、圧縮系で生ずる現象を十分に理解したうえで評価することが重要である。, To evaluate long term corrosion behavior of carbon steel in compacted bentonite, experiment was carried out using artificial seawater and groundwater at 50circC and 80circC for 10 years. In this study, alteration behavior of bentonite for Fe-bentonite interaction was investigated for compacted bentonite after this experiment. Until now, batch experiment carried out to change temperature, solution and period to understand behavior of altered bentonite contacted with iron. These result showed a change for Fe-type smectite and alteration of non-expandable clay mineral. But, in this study, initial Na-type smectite did not exchange after experiment, while it was confirmed that iron permeated in compacted bentonite. Therefore, for estimation of influence that is interaction of Fe-bentonite on compacted condition like a repository, it is important to estimate sufficiently understanding phenomenon for compacted bentonite, not to adapt directly to batch experimental results., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2008-007

雰囲気制御グローブボックス(酸素濃度1ppm以下,N2雰囲気)内において、Na型ベントナイト(クニピアF)にFeCl2溶液を混合することによりあらかじめ鉄型化したベントナイトを温度制御した条件(150circC)において、長期間(1年及び1年8か月(20か月))静置させ、鉄型化スメクタイトの長期挙動を把握するための実験を実施した。その結果、Fe型化したスメクタイトが溶解することにより、膨潤を妨げる物質が生成してスメクタイトに付着するものの、スメクタイトの構造(2:1型の2-八面体構造)や特性(膨潤特性及び陽イオン交換能)は維持されていたことを確認した。250circCにおける試験で同定された非膨潤性粘土鉱物の生成は、XRD分析等では確認されなかった。, A present study was carried out to understand the long-term behavior of Fe-smectite. The starting material (i.e., Fe-bentonite) was prepared by mixing Na-bentonite (Kunipia-F) with FeCl2 solution in a controlled-atmosphere glove box (O2<1ppm, N2). The experiments were conducted for 1 year and 20 months at 150circC. As the results, it was suggested that a dissolution of Fe-smectite and a generation of secondary material which might precipitate on the layer surface of smectite. However the original smectite structure (i.e., 2:1 type octahedral structure) and the initial characteristic of bentonite (e.g., swelling capacity, ion exchange capacity) were maintained. The generation of non-swelling clay mineral which was observed in the similar experiment at 250circC was not identified in the present study by XRD analysis., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2007-018

核燃料サイクル開発機構は、これまでに高レベル放射性廃棄物地層処分研究開発の第2次取りまとめにおいて、人工バリア及び天然バリアでの遅延能力を評価するうえで重要な放射性核種のベントナイトや岩石への分配係数(Kd)を収着データベース(JNC-SDB)として整備した(澁谷ほか、1999)。また、同整備以降の1998sim2003年の間に公開された文献をもとにデータを追加した(陶山,笹本、2004)。今回、日本原子力研究開発機構(以下、JAEA)として、JNC-SDBを拡充・更新するため、過去に公開された文献を広く再調査・データ収集を行い、Kdデータを追加した。また、使用者の利便性を考慮して、JNC-SDBの機能を改良した。さらに、今回、「収着データベースを用いた収着分配係数の信頼性評価」作業に基づきデータベースを見直し、データの再入力を行った。今回の更新作業により、全体で23元素に対し、3,205件のKdデータが増加した。また、一部の元素については、これまでより分配係数の頻度分布がより明確になり、データの分布を把握しやすくなった。, Japan Nuclear Cycle Development Institute (JNC) has developed the sorption database (JNC-SDB) for bentonite and rocks in order to estimating a retardation capacity of important radioactive elements on natural barrier and engineered barrier in the H12 report. The database includes distribution coefficient (Kd) of important radionuclides. And JNC collected the sorption data from 1998 to 2003. In this report, Japan Atomic Energy Agency (JAEA) widely collected the sorption data in order to extend and update the sorption database. The updated database includes the published data which are not registered in the sorption database. In this updated JNC-SDB, 3,205 sorption data for 23 elements, which are important for performance assessment were included. The frequency of Kd for some elements was clearly shown by addition of the sorption data., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Data/Code 2007-014

処分システムの長期挙動の把握の一つとして炭素鋼腐食生成物-ベントナイト相互作用の理解は重要である。既往の研究から鉄と接触したベントナイトは層間に鉄を取り込み鉄型化することがわかっている。しかしながら、それ以上の変化は現在のところ明確ではない。したがって、本試験では鉄型化スメクタイトを出発物質として、その後に発生する鉱物学的変化を確認することを目的とした実験を実施した。雰囲気制御グローブボックス(酸素濃度1ppm以下,Ar雰囲気)内において、Na型ベントナイト(クニピアF)にFeCl2溶液を混合することにより鉄型化ベントナイトを作成した。この鉄型化ベントナイトと蒸留水を金チューブに入れて、オートクレーブを用いて反応を加速することを目的として処分環境で想定されている温度より高い温度(250circC)で各任意期間(1か月及び6か月)静置した。その結果、250circCで6か月間静置した試料においては7{AAに非膨張粘土鉱物(バーチェリン)と思われるピークが確認できた。さらに、試料250circCで6か月間静置した粉末試料に1MのNaCl溶液を加えることによりベントナイトの再調整を行った。この試料の湿度制御条件下でのX線回折分析結果は、Na型ベントナイトに戻った結果となったことから、250circCで6か月間静置した試料の大部分は単にスメクタイト層間の陽イオン交換反応に留まり、大きなスメクタイト構造の変化や特性の変化までは至っていないことが確認できた。, In previous experiment, we studied about interaction bentonite and Fe by the laboratory experiment that bentonite mixed with iron powder was kept for 6 years at room temperature in the glove box (O2 < 1 ppm). It was shown that bentonite was not influenced about its property, but change to Fe-bentonite. In this experiment, it is aimed to confirm mineralogical change of start substance, which is Fe-bentonite changed from Na-bentonite beforehand, by accelerating reactions on high temperature. Fe-bentonite was prepared by mixing Na-bentonite (Kunipia F) and FeCl2 solution in the glove box (Ar, O2 < 1 ppm). Fe-bentonite samples were put into Au-tubes, and they were kept at 250circC in autoclave for 1 month and 6 months. 6 months sample was confirmed the peak of a iron-containing 7AA non-expandable clay mineral (i.e. berthierin). For the confirmation of reversibility of ion-exchange, 6 months sample was mixed with 1M-NaCl solution. XRD analysis for the treated sample under humidity controlled condition showed a same result with that of Na-bentonite. This means that a change of the sample was only ion-exchange reaction in the bentonite inter-layer, and bentonite properties was not changed., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2006-064