Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
浜本 貴史*; 小池 彩華*; 石寺 孝充; 岩田 孟; 深津 勇太; 種市 やよい
NUMO-TR-24-03; 技術開発成果概要2023, p.85 - 86, 2024/10
地層処分事業の実施主体である原子力発電環境整備機構(NUMO)が、日本原子力研究開発機構(JAEA)をはじめとする関係研究機関及び大学との共同研究等により実施した2023年度の技術開発成果の概要を取りまとめ、報告する。本報告は、NUMOとJAEAの共同研究「ニアフィールドシステムの状態変遷に伴うバリア材及び核種の長期挙動評価のための研究」で2023年度に実施したサイト調査を反映した核種移行パラメータ設定の方法論の検討及びデータ拡充に関する成果についての概要をまとめたものである。
浜本 貴史*; 深津 勇太
NUMO-TR-24-01; 技術開発成果概要2022, p.95 - 97, 2024/05
地層処分事業の実施主体である原子力発電環境整備機構(NUMO)が、日本原子力研究開発機構(JAEA)をはじめとする関係研究機関及び大学との共同研究等により実施した2022年度の技術開発成果の概要を取りまとめ、報告する。本報告は、NUMOとJAEAの共同研究「ニアフィールドシステムの状態変遷に伴うバリア材及び核種の長期挙動評価のための研究」で2022年度に実施した割れ目が卓越した母岩中の核種移行モデルに関する原位置試験データを用いた妥当性確認に関する成果についての概要をまとめたものである。
Hu, Q.*; Wang, Q. M.*; Zhang, T.*; Zhao, C.*; Iltaf, K. H.*; Liu, S. Q.*; 深津 勇太
Energy Reports (Internet), 9, p.3661 - 3682, 2023/12
被引用回数：10 パーセンタイル：74.40(Energy & Fuels)This study evaluates petrophysical properties of representative geological rocks in the context of injectivity, storage space, and caprock integrity for effective utilization and long-term storage of carbon dioxide. A total of 10 geological rocks were selected as representative storage media for consideration as saline aquifers & depleted oil and gas reservoirs, basalts, and cap rocks, as well as utilization in organic-rich shale and coal seams. An integrated suite of laboratory tests, including liquid immersion porosimetry, gas expansion porosimetry, grain size distribution, mercury intrusion porosimetry, and gas diffusion, were performed on these various rock samples. The results exhibit a disparity of petrophysical properties among two broad groups of rocks: rocks selected for possible storage of CO
have porosities of 
10-25%, permeabilities of 10
-10
m
, 
m-sized pore-throat size distribution, and mostly good pore connectivity; in contrast, the potential caprocks have porosities of 0.5-5%, permeabilities of 10
-10
m, pore throat sizes of 
50 nm, and probably poorly connected pore networks. An understanding of the measured facets of pore structure and contribution of fractures is also critical in the context of different testing principles and data interpretation of petrophysical analyses, as well as observational scales in the laboratory and field, and therefore reliable confidence of CO storage and utilization performance. Our work further illustrates the controlling influence of grain size distribution and geological processes on pore size distribution and pore connectivity for a wide range of rock types and lithologies, and particularly presents the extent and behavior of CO gas diffusion with a custom-designed apparatus for a holistic understanding of various petrophysical attributes of widely different geological rocks.
Soler, J. M.*; Kek
linen, P.*; Pulkkanen, V.-M.*; Moreno, L.*; Iraola, A.*; Trinchero, P.*; Hokr, M.*; 
ha, J.*; Havlov
, V.*; Trpko
ov, D.*; et al.
Nuclear Technology, 209(11), p.1765 - 1784, 2023/11
被引用回数：3 パーセンタイル：70.15(Nuclear Science & Technology)The REPRO-TDE test was performed at a depth of about 400 m in the ONKALO underground research facility in Finland. Synthetic groundwater containing radionuclide tracers (HTO, Cl-36, Na-22, Ba-133, Cs-134) was circulated for about four years in a packed-off interval of the injection borehole. Tracer activities were additionally monitored in two observation boreholes. The test was the subject of a modelling exercise by the SKB GWFTS Task Force. Eleven teams participated in the exercise, using different model concepts and approaches. Predictive model calculations were based on laboratory-based information concerning porosities, diffusion coefficients and sorption partition coefficients. After the experimental results were made available, the teams were able to revise their models to reproduce the observations. General conclusions from these back-analysis calculations include the need for reduced effective diffusion coefficients for Cl-36 compared to those applicable to HTO (anion exclusion), the need to implement weaker sorption for Na-22, compared to results from laboratory batch-sorption experiments, and the observation of large differences between the theoretical initial concentrations for the strongly-sorbing Ba-133 and Cs-134 and the first measured values a few hours after tracer injection. Different teams applied different concepts, concerning mainly the implementation of isotropic vs. anisotropic diffusion, or the possible existence of Borehole Disturbed Zones around the different boreholes. The role of microstructure was also addressed in two of the models.
Yuan, X.*; Hu, Q.*; Lin, X.*; Zhao, C.*; Wang, Q.*; 舘 幸男; 深津 勇太; 濱本 昌一郎*; Siitari-Kauppi, M.*; Li, X.*
Journal of Hydrology, 618, p.129172_1 - 129172_15, 2023/03
被引用回数：4 パーセンタイル：49.61(Engineering, Civil)Mass transport in geomedia as influenced by the pore structure is an important phenomenon. Six rocks (granodiorite, limestone, two chalks, mudstone, and dolostone) with different extents of heterogeneity at six different particle sizes were studied to describe the effects of pore connectivity on mass transport. The multiple methods applied were porosity measurement, gas diffusion test, and batch sorption test of multiple ions. Porosity measurement results reveal that with decreasing particle sizes, the effective porosities for the "heterogenous" group (granodiorite and limestone) increase, whereas the porosities of "homogeneous" group (chalks, mudstone, and dolostone) roughly remain constant. Gas diffusion results show that the intraparticle gas diffusion coefficient among these two groups, varying in the magnitude of 10
to 10
m/s. The batch sorption work displays a different affinity of these rocks for tracers, which are related to their mineral components. For granodiorite, mudstone, and dolostone, the adsorption capacity increases as the particle size decreases, due to higher specific surface area in smaller particle-size. In general, this integrated research of grain size distribution, rock porosity, intraparticle diffusivity, and ionic sorption capacity gives insights into the pore connectivity effect on both gas diffusion and chemical transport behaviors for different lithologies and/or different particle sizes.
Cs NMR chemical shift of clay minerals via machine learning and DFT-GIPAW calculations大窪 貴洋*; 武井 滉洋*; 舘 幸男; 深津 勇太; 出口 健三*; 大木 忍*; 清水 禎*
Journal of Physical Chemistry A, 127(4), p.973 - 986, 2023/02
被引用回数：5 パーセンタイル：61.82(Chemistry, Physical)粘土鉱物へのCsの吸着サイトの特定は、環境化学の分野で研究されてきた。核磁気共鳴(NMR)実験によって、吸着されたCsの局所構造を直接観察することが可能である。固体NMR実験から得られたCsのNMRパラメータは、吸着されたCsの局所的な構造に敏感である。しかしながら、NMRデータだけからCsの吸着位置を決定することは困難であった。本研究では、機械学習と実験的に観察されたケミカルシフトを組み合わせることにより、粘土鉱物に吸着されたCsの吸着位置を特定するためのアプローチについて提示する。原子配置の記述子とNMRによるケミカルシフトの第一原理計算結果を関連付けて評価する機械学習の線形リッジ回帰モデルを構築した。これにより、原子配置の構造データからCsのケミカルシフトを高速で計算することが可能となった。機械学習モデルによって、実験的に観察された化学シフトから逆解析を行うことにより、Cs吸着位置を導き出すことが可能になる。
Soler, J. M.*; Keklinen, P.*; Pulkkanen, V.-M.*; Moreno, L.*; Iraola, A.*; Trinchero, P.*; Hokr, M.*; ha, J.*; Havlov, V.*; Trpkoov, D.*; et al.
SKB TR-21-09, 204 Pages, 2021/11
Task 9C of the SKB Task Force on Modelling of Groundwater Flow and Transport of Solutes (Task Force GWFTS) was the third subtask within Task 9 and focused on (1) predictive and (2) back-analysis modelling of experimental results from the REPRO-TDE in situ diffusion experiment. The test was performed at a depth of about 400 m in the ONKALO underground research facility in Finland. Synthetic groundwater containing radionuclide tracers (HTO, Cl-36, Na-22, Ba-133, Cs-134) was circulated for about four years in a packed-off interval of the so-called injection borehole. Tracer activities were additionally monitored in two observation boreholes arranged as a right-angled triangle and located at about 0.1 m wall-to-wall from the injection borehole. Eleven modelling teams participated in the modelling exercise, using different model concepts and approaches. Three main types of models were applied: (1) An analytical solution to the diffusion-retention equations, (2) continuum-porous-medium-type numerical models, and (3) microstructure-based models. The predictive model calculations were based on laboratory-based information concerning porosities, diffusion coefficients and sorption partition coefficients available in the task description. Microstructural characterisation of rock samples was also available and used by the teams using microstructure-based models.
Cs
, and 
I
in compacted Ca-montmorillonite; Experimental and modeling approaches深津 勇太; 四辻 健治*; 大窪 貴洋*; 舘 幸男
Applied Clay Science, 211, p.106176_1 - 106176_10, 2021/09
被引用回数：20 パーセンタイル：87.99(Chemistry, Physical)Mechanistic understanding and predictive modeling of radionuclide diffusion in Na- and Ca-montmorillonite are essential to evaluate the long-term evolution of the bentonite barrier and their impact on radionuclide migration during geological disposal of radioactive wastes. Thus, the diffusion behavior of Cs, I, and tritiated water (HTO) in compacted Ca-montmorillonite was investigated as a function of porewater salinity and dry density via both experiments and models. The effective diffusion coefficient (De) followed in the order of Cs 
HTO I. The De of Cs decreased with increasing salinity, whereas the dependence of De of I on salinity was uncertain. The cation excess and anion exclusion effects for Ca-montmorillonite were lower than those for Na-montmorillonite. The integrated sorption and diffusion (ISD) model, assuming the homogeneous pore structure and the electrical double layer (EDL) theory for 2:1 electrolyte (CaCl), could account for the observed trends for De in Ca-montmorillonite. The lower dependence of De on the porewater salinity in Ca-montmorillonite was caused by the reduction of the EDL thickness for divalent cations (Ca
) in comparison with that for monovalent cations (Na). The multipore model could improve the fit for De of I at low salinity due to the reduction of interlayer pore volumes and anion exclusion effect, however, the disparity at higher densities was considerably larger. From these results, cation diffusion for compacted Ca-montmorillonite could be mainly explained by the electrostatic interactions in the homogeneous pore model; in contrast, anion diffusion was sensitive to both electrostatic interactions and heterogeneous pore structures. The proposed ISD model is an effective tool to evaluate the radionuclide diffusion and sorption behavior in both compacted Ca-montmorillonite and Na-montmorillonite.
大窪 貴洋*; 山崎 秋雄*; 深津 勇太; 舘 幸男
Microporous and Mesoporous Materials, 313, p.110841_1 - 110841_11, 2021/01
被引用回数：9 パーセンタイル：45.03(Chemistry, Applied)Ca型モンモリロナイト中の間隙分布が、乾燥密度(0.8-1.6g/cm
),間隙水塩濃度(脱イオン水、0.1及び1M CaCl),温度(233-303K)の条件下で、
H NMR測定によって調査された。圧縮Ca型モンモリロナイト中の2層及び3層水和を含む層間間隙と層間外間隙の体積割合が、緩和時間
及び
分布の分析に基づくNMR緩和時間測定法によって定量評価され、さらに、NMR凍結間隙測定法及びX線回折法による結果と比較された。これらの分析によって、Na型モンモリロナイトと比較可能な、Ca型モンモリロナイト中の間隙分布の状態を把握することができた。圧縮Ca型及びNa型モンモリロナイト中の間隙分布に影響を及ぼす主要な因子は圧縮密度であり、間隙水塩濃度の影響は相対的に小さい結果となった。CaとNaの層間陽イオンの影響は高密度条件では小さいが、低密度ではその影響は顕著であった。
Hu, Q.*; Wang, Q.*; Zhao, C.*; Zhang, T.*; 舘 幸男; 深津 勇太
no journal, ,
Fine-grained and clay-rich mudrocks play an important role in the long-term performance of a geological repository for storing high-level nuclear wastes and petroleum production in shale formations. However, low-permeability mudrocks whose pores are poorly interconnected are known to have anomalous diffusion properties that strongly impact long-term net diffusion. The complex pore structure involving predominantly nano-sized pore space is related to compaction and diagenesis from the maturation process of organic matter-rich mudrocks at deep depths, leading to a much smaller effective porosity which could be further partitioned by water- or oil-wet pore networks. Working with shallow clayey sediments of Wakkanai formation around Horonobe underground research center in Hokkaido of Japan and Opalinus clay of Mt. Terri Underground Research Laboratory in Switzerland, as well as various deep shales (Barnett, Eagle Ford and Wolfcamp from Texas, Bakken from North Dakota), using a wide range of sample sizes, this multi-approach and -scale work utilizes a complementary suite of approaches for pore structure characterization (e.g., helium pycnometry, mercury intrusion porosimetry, small angle/X-ray neutron scattering, field emission-scanning electron microscopy), gas diffusion and liquid (including water-, oil-, and bi-wetting) imbibition involving custom-designed tracer recipe followed with micro-scale mapping with laser ablation-ICP-MS. The experimental results show that deep mudrocks has a much smaller effective porosity than the total porosity (as a result of poor pore connectivity) and associated diffusion coefficient, and the effective porosity and diffusion coefficients are also dependent upon the sample sizes used in the measurement.
武井 滉洋*; 大窪 貴洋*; 舘 幸男; 深津 勇太
no journal, ,
天然の岩石や土壌中の放射性核種の移行を評価するうえで、風化生成物として含まれる粘土鉱物への放射性核種の吸着・固定は重要な現象のひとつである。放射性廃棄物の地層処分の安全評価や福島の環境中へ放出された核種の挙動評価において、重要な放射性核種であるCsは、主に粘土鉱物によって吸着・固定化される。岩石や土壌に含まれる代表的な粘土鉱物であるバーミキュライトはCsを強く吸着することが知られておりCsの移動挙動を支配する物質の一つである。バーミキュライトへのCsの吸着・脱着試験より、バーミキュライトは複数のCs吸着サイトが存在することが示唆されているが、その詳細なメカニズムについては解明されていない。そこで本研究では、Csが吸着したバーミキュライトの133Cs固体NMR実験とモデル構造によるシフト計算により、バーミキュライトに吸着したCsのケミカルシフトと構造の関係を調べた。
Hu, Q.*; Wang, Q. M.*; Zhao, C.*; Zhang, T.*; Iltaf, H.*; 舘 幸男; 深津 勇太
no journal, ,
Fine-grained and clay-rich mudrocks play an important role in the long-term performance of a geological repository for storing high-level nuclear wastes and petroleum production in shale formations. However, low-permeability mudrocks whose pores are poorly interconnected are known to have anomalous diffusion properties that strongly impact long-term net diffusion. The complex pore structure involving predominantly nano-sized pore space is related to compaction and diagenesis from the maturation process of organic matter-rich mudrocks at deep depths, leading to a much smaller effective porosity. Working with various clay minerals, shallow clayey sediments of Wakkanai formation around Horonobe URL in Japan and Opalinus clay of Mt. Terri URL in Switzerland, as well as various deep shales (Barnett, Eagle Ford and Wolfcamp from Texas), using a wide range of sample sizes, this multi-approach and -scale work utilizes a complementary suite of techniques for pore structure characterization (e.g., mercury intrusion porosimetry, small angle X-ray/neutron scattering, scanning electron microscopy), gas diffusion, batch sorption and column transport. The experimental results show that deep mudrocks has a much poor pore connectivity than the shallow ones, and the effective porosity, diffusion coefficients, sorption coefficients are also dependent upon the sample sizes used in the measurement.
Hu, Q. H.*; Zhang, T.*; Shen, Y. Q.*; 舘 幸男; 深津 勇太; Borglin, S.*; Chang, C.*; Hampton, J.*
no journal, ,
In a deep geological repository of high-level nuclear wastes, the near-field systems consist of waste packages, buffer materials, and natural barrier systems. It is expected that the initial thermal loading after waste emplacement will last several hundred years. It is important to investigate the effects of this thermal loading on the near-field components under in situ stress conditions, in terms of thermal-hydrological-mechanical-chemical (THMC) processes and subsequent radionuclide retention and migration. Preliminary tests have been performed via integrated combinations of buffer materials and host rocks, at nm-dm scales, subjected to a range of elevated temperatures under true-triaxial conditions, which is complemented by a suite of nano-petrophysical characterization approaches such as small-angle neutron/X-ray scattering techniques to quantify total pore space and sample size-dependent effective porosity. For multiple-approach radionuclide retention and migration tests before- and after-THMC experiments, a complementary range of tests will include batch, column, and gas diffusion for granular samples, as well as gas/liquid diffusion and fractured core transport tests for intact rock samples under different temperature and pressure conditions.
深津 勇太; 赤木 洋介*; 佐藤 久夫*; 村山 翔太*; 石寺 孝充; 舘 幸男
no journal, ,
高レベル放射性廃棄物の地層処分において、岩盤中の割れ目は、放射性核種の主な移行経路として想定されている。割れ目中の核種は地下水の流れにより移行するが、割れ目の形状や性状が均一でないことから、その不均質性が移行挙動へ及ぼす影響の評価が課題である。これまでに原子力機構では、原位置試験場から採取した岩石の天然の割れ目を対象に、核種の移行挙動の理解及びモデル開発を進め、割れ目開口幅や割れ目表面近傍の変質層の重要性を示してきた。一方で、これまでに対象とした試料では数cm程度の移行評価にとどまり、より大きなスケールで想定される流路の選択性や連続性が移行挙動に及ぼす影響の評価が課題であった。本研究では、数十cm程度の移行距離を想定した大型の花崗閃緑岩の割れ目を対象に、トレーサー移行試験及びX線CT測定を実施した。それらの結果から、移行挙動に影響を及ぼすことが予想される割れ目の構造やトレーサーの流路の不均質性を調べた。
村山 翔太*; 深津 勇太; 石寺 孝充; 舘 幸男
no journal, ,
地層処分の安全評価において、岩盤中の放射性核種の移行挙動を予測するため、岩石の不均質性を考慮した核種移行の現象理解と移行モデルの開発は重要である。これまでに原子力機構では、スイスのグリムゼル花崗閃緑岩の割れ目を対象にした室内試験データを元に、割れ目表層からマトリクス部にかけて存在する変質層を考慮した移行モデルを構築し、変質層での収着と拡散の重要性を示してきた。本研究では、先行研究及び室内トレーサー試験の結果(本シリーズ発表1)に基づき、岩石割れ目の不均質性(割れ目中の充填物、割れ目表層の変質層、流路の制限)を考慮したモデルを構築して割れ目中の核種移行挙動を解析し、その不均質性が核種移行へ及ぼす影響を評価した。
Hou, L.*; 岡本 駿一*; 戸田 賀奈子*; 深津 勇太; 石寺 孝充; 斉藤 拓巳*
no journal, ,
This study examines pre-Neogene sedimentary rocks, prevalent in the Japanese basement and considered potential host rocks for high-level radioactive waste (HLW) repositories. These rocks, characterized by their block-in matrix structures, present unique challenges in understanding the diffusion behaviors of radionuclides. Given their lithofacies, vein patterns, and fracture characteristics, an approach is required to clarify diffusion behaviors, based on their structural characteristics. The research employs through-diffusion experiments with Cs, I, and HDO to address this. The obtained breakthrough curves are modeled with the help of X-ray Computed Tomography (X-ray CT) scanning data. These investigations are pivotal in assessing the barrier performance of pre-Neogene sedimentary rocks for effective long-term containment of HLW.
舘 幸男; 四辻 健治*; 深津 勇太; 杉浦 佑樹; 大窪 貴洋*
no journal, ,
放射性廃棄物の地層処分の安全評価において、ベントナイト緩衝材や岩石中に含まれる粘土鉱物中の核種移行現象の理解が重要となる。粘土鉱物中の核種移行モデルを構築するうえで、中核となるのは層状構造をもつ粘土鉱物によって形成される間隙構造と粘土鉱物表面での静電的な相互作用である。本報告では、セメント系材料の共存によるベントナイトの状態変遷(Na型からCa型への変化)の影響を評価するため、圧縮ベントナイト中の間隙構造と静電的な相互作用の双方の効果を考慮した核種の拡散・収着モデルの開発成果を報告する。
Hu, Q.*; Wang, Q.*; Zhao, C.*; 舘 幸男; 深津 勇太
no journal, ,
低透水粘土バリア材料中の低拡散性は、放射性廃棄物処分場の長期性能評価において、重要な安全機能と認識されている。間隙の連結性が低い低透水粘土材料は、特異な拡散特性を示し、このことが長期拡散挙動に影響を及ぼす可能性が報告されている。日本の幌延URLの稚内層の泥岩、スイスのモンテリURLのオパリナス粘土岩、さまざまな頁岩や粘土鉱物の関連研究において、間隙構造の評価手法(水銀圧入法や中性子小角散乱法など)と、レーザーアブレーションICP-MSによるマイクロスケールでの元素分布分析を組合せたトレーサー試験手法が適用された。これらの試験結果から、間隙の連続性と拡散挙動の特異性との関係が得られた。間隙のサイズは低い透水性や拡散性の主要な要因ではなく、特異な拡散挙動は間隙の連結性に起因していることを明らかにした。
舘 幸男; 伊藤 剛志*; 深津 勇太; 赤木 洋介*; 佐藤 久夫*; Hu, Q.*; Martin, A. J.*
no journal, ,
In order to develop a realistic model and reliable parameters for long-term safety assessments of geological disposal, it is necessary to understand and quantify the effects of heterogeneities found around the fractures on RN transport processes in fractured crystalline rocks. This paper presents a comprehensive approach developed for coupling laboratory tests, microscopic observations and modeling in order to understand and quantify tracer transport processes occurring in natural fracture, using different types of fractured granodiorite sample from the Grimsel Test Site (GTS), Switzerland. Laboratory tests including through-diffusion, batch sorption and flow-through tests using five tracers with different retention properties indicated that tracer retention was consistently in the sequence of HDO Se Cs Ni Eu. Microscale heterogeneities around the fracture were clarified and quantified by coupling X-ray computed tomography and electron probe microanalysis. Realistic model incorporating heterogeneities around the fracture and their properties provided a much better interpretation for breakthrough curves of all tracers.
深津 勇太; 舘 幸男
no journal, ,
Crystalline rocks such as granodiorites have been investigated as potential host rocks for the geological disposal of radioactive waste in many countries. Radionuclide transport in fractured crystalline rocks can be conceptualized by a dual-porosity model where radionuclides are transported by advective water flow through a fracture and are retarded by both diffusion and sorption into the surrounding rock matrix. Aperture variability within a fracture determines flow in a channel, whereas other areas of the fracture have almost stagnant water. The effect of different degrees of heterogeneity in fracture aperture distributions is critically important to quantify solute transport. In the present study, we identified flow channels and stagnant water zones in a fractured granodiorite by mean of a flow-through test, using imaging tracer coupled with micro X-ray CT measurements.
