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Journal Articles

A Coupled modeling simulator for near-field processes in cement engineered barrier systems for radioactive waste disposal

Benbow, S. J.*; Kawama, Daisuke*; Takase, Hiroyasu*; Shimizu, Hiroyuki*; Oda, Chie; Hirano, Fumio; Takayama, Yusuke; Mihara, Morihiro; Honda, Akira

Crystals (Internet), 10(9), p.767_1 - 767_33, 2020/09

 Times Cited Count:1 Percentile:42.94(Crystallography)

Details are presented of the development of a coupled modeling simulator for assessing the evolution in the near-field of a geological repository for radioactive waste disposal where concrete is used as a backfill. The simulator uses OpenMI, a standard for exchanging data between simulation software programs at run-time, to form a coupled chemical-mechanical-hydrogeological model of the system. The approach combines a tunnel scale stress analysis finite element model, a discrete element model for accurately modeling the patterns of emerging cracks in the concrete, and a finite element and finite volume model of the chemical processes and alteration in the porous matrix and cracks in the concrete, to produce a fully coupled model of the system. Combining existing detailed simulation software in this way with OpenMI has the benefit of not relying on simplifications that might be necessary to combine all of the modeled processes in a single piece of software.

JAEA Reports

Collection of measurement data from in-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory (until March, 2018)

Nakayama, Masashi; Ono, Hirokazu; Nakayama, Mariko*; Kobayashi, Masato*

JAEA-Data/Code 2019-003, 57 Pages, 2019/03


The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, Geoscientific Research and Research and Development on Geological Disposal Technologies, and proceeds in 3 overlapping phases, Phase I: Surface-based investigations, Phase II: Investigations during tunnel excavation and Phase III: Investigations in the URL, over a period of around 20 years. Phase III investigation was started in 2010 FY. The in-situ experiment for performance confirmation of engineered barrier system had been prepared from 2013 to 2014 FY at GL-350 m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with THMC coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report summarizes the measurement data acquired from the experiment from December, 2014 to March, 2018. The summarized data of the EBS experiment will be published periodically.

Journal Articles

Utilization of the knowledge of excavated archaeological artifacts for research and development of geological disposal

Mitsui, Seiichiro

Maizo Bunkazai Nyusu, (171), p.10 - 17, 2018/03

As part of research and development of geological disposal, "natural analogues" have been applied to validate concept of models and evaluation methodologies for performance assessment. By introducing domestic and overseas research results on natural analogues, this paper presents how we have utilized knowledge of excavated archaeological artifacts for geological disposal studies.

Journal Articles

A Study of excavation damaged zone induced around the modeled disposal pit in Horonobe Underground Research Center

Aoyagi, Kazuhei; Ishii, Eiichi; Nakayama, Masashi; Fujita, Tomo

Nippon Zairyo Gakkai Dai-65-Ki Tsujo Sokai, Gakujutsu Koenkai Rombunshu (USB Flash Drive), p.19 - 20, 2016/05

no abstracts in English

Journal Articles

Analysis of radionuclide migration with consideration of spatial and temporal change of migration parameters due to uplift and denudation

Shimada, Taro; Takeda, Seiji; Mukai, Masayuki; Munakata, Masahiro; Tanaka, Tadao

Materials Research Society Symposium Proceedings, Vol.1744, p.229 - 234, 2015/04

Integrated safety assessment methodology which analyzes radionuclide migration reflecting the spatial and temporal changes of disposal systems was developed for a geological disposal site with uplift and denudation, and then some case analyses for an assumed site with sedimentary rocks were carried out. The combination of uniform uplift and denudation has the most effect on the radionuclide migration because the groundwater flow velocity increases with decreasing the depth from the ground surface. In the case without denudation, tilted uplift has more effect than uniform uplift because flow velocity in tilted uplift increase with increasing hydraulic gradient. The long-term change of the geological structures including the uplift and denudation, the hydraulic conditions, and the recharge and outlet of the groundwater around a candidate site should be carefully investigated to determine the appropriate the place,depth and layout of the repository.

Journal Articles

R&D on geological disposal technology at Horonobe

Fujita, Tomo

Kisoko, 43(1), p.81 - 83, 2015/01

no abstracts in English

Journal Articles

Nuclear engineering and radiation effect; Radiation effects in reprocessing and geological disposal

Nagaishi, Ryuji

Genshiryoku, Ryoshi, Kakuyugo Jiten, 4, p.106 - 107, 2014/12

no abstracts in English

Journal Articles

Field tests on migration of TRU-nuclide, 1; General introduction

Ogawa, Hiromichi; Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Munakata, Masahiro; Matsumoto, Junko; Bamba, Tsunetaka; Li, S.*; Wang, Z.*; Li, Z.*; et al.

Nippon Genshiryoku Gakkai Wabun Rombunshi, 2(3), p.332 - 335, 2003/09

The filed migration test using TRU nuclide was carried out as a cooperative research project between JAERI and CIRP (China Institute for Radiation Protection). This report introduced the outline of the filed migration test and described the outline of the special number of Field Test on Migration of TRU-nuclide and main results as a summary report.

Journal Articles

Field tests on migration of TRU-nuclide, 5; Validation study of safety assessment code system of shallow land disposal (GSA-GCL)

Munakata, Masahiro; Kimura, Hideo; Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Ogawa, Hiromichi

Nippon Genshiryoku Gakkai Wabun Rombunshi, 2(3), p.361 - 367, 2003/09

no abstracts in English

JAEA Reports

The Planning of future research program of underground laboratories in overseas

*; Tanai, Kenji; *

JNC-TN8420 2001-007, 86 Pages, 2002/02


The objectives of this study is to identify the research issues, which are to be conducted in the future underground research laboratory, about operation and logistics systems for the planning of future research and development program. The research programs and experiments,etc. were investigated for the geological disposal projects in overseas sedimentary rocks and coastal geological environments aiming to reflect in the future underground research facility plan in Japan. In the investigation, information on the engineered-barrier performance, design and construction of underground facilities, tunnel support, transportation and emplacement, and backfilling technology, etc. were collected. Based on these informations, the purpose, the content, and the result of each investigations and tests were arranged. The strategy and the aim in the entire underground research facility, and the flow of investigations and tests, etc. were also arranged from the purpose, the relations and the sequence of each investigation and experiment, and the usage of results, etc.

JAEA Reports

A study on long term stability of bentonite; The preliminary study on the bentonite stability in the groundwater influenced by cementitious material

*; Mihara, Morihiro;

JNC-TN8430 2001-007, 56 Pages, 2002/01


In the geological disposal concept of radioactive wastes, a kind of clay with sorption ability and low permeability, called bentonite, is envisaged as an engineered barrier system in the geological repository. Also, the cemetitious material is envisaged as the backfill material in the vaults and the structure material of the vaults. The groundwater in contact with the cementitious material will promote hyperalkaline conditions in the repository environment and these conditions will affect the performance of the bentonite. Therefore, it is necessary to investigate the interaction between the cementitious material and the bentonite for the evaluation of long term stability of the disposal system. In this study, for the identification and the investigation of the secondary minerals, the batch immersion experiments of the powder bentonite were carried out using synthetic cement leachates (pH=7, 12.5, 14) at 200$$^{circ}$$C. As the results, it was confirmed that Na as exchangeable cations in the bentonite can exchange relatively easily with Ca in the solution from the experiment results. And the ratio of cation exchange was estimated to be about 25% based on the amount of exchangeable cations Ca$$^{2+}$$ between layers. Furthermore, it was concretely shown that the generation of analcime might be affected by the Na concentration from results of the solution analyses and a stability analysis of analcime using the chemical equilibrium model, in addition to the pH in the solution.

JAEA Reports



JNC-TN1440 2000-009, 150 Pages, 2000/11


no abstracts in English

JAEA Reports


; ; Shimizu, Kazuhiko; Miyahara, Kaname; ; Seo, Toshihiro; Fujita, Tomo

JNC-TN1410 2000-008, 100 Pages, 2000/10


no abstracts in English

JAEA Reports

Degradation studies on granite in alkaline solution

Owada, Hitoshi*; Mihara, Morihiro; *; *

JNC-TN8400 2000-027, 19 Pages, 2000/08


Bactch leaching experiments of granite with the artifitial cement leachate and the leachate of low-alkalinity-cement (LW) were carried out to evaluate the effect of the hiperalkaline plume on the environment of the high-level and TRU radioactive waste repository. Dissolution of Si and Al from feldspar included in the granite and precipitation of C-S-H were confirmed from the results of the leaching experiments with artifitial cement leachate. From this result it was found that the composition of sorrounding rock changed. It also suggested that the retardation factor of migration of radionuclides would change. On the contrary, only decrease of concentrations in Si, Al and Ca in the leachate was observed in the experiment with LW. This result might indicate that C-S-H and/or C-A-S-H precipitated as secondary minerals in the LW case. From these results, it was considered that the hiperalkaline plume from the cementitious leachate might caused the change of disposal conditions such as the change in distribution coefficients of rock by precipitation of the secondary mineral and the increase in hydraulic conductivity by the dissolution of rock. On the other hand, the influences of the LW would be comparatively small, because LW and granite might equilibrate in short time.

JAEA Reports

Experimental investigation of activities and tolerance of denitrifying bacteria under alkaline and reducing condition

Mine, Tatsuya*; Mihara, Morihiro;

JNC-TN8430 2000-009, 35 Pages, 2000/07


In the geological disposal system of TRU wastes, nitrogen generation by denitrifying bacteria could provide significant impact on the assessment of this system, because nitrate contained in process concentrated liquid waste might be electron acceptor for denitrifying bacteria. In this study, the activities and tolerance of denitrifying bacteria under disposal condition were investigated. pseudomonas denitrificans as denitrifying bacteria was used. The results showed that Pseudomonas denitrificans had activity under reducing condition, but under high pH condition (PH$$>$$9.5), the activity of Pseudomonas denitrificans was not detected. It is possible that the activity of Pseudomonas denitrificans would be low under disposal condition.

JAEA Reports

Reliability evaluation for radionuclide transport analysis code MATRICS

*; Ijiri, Yuji*; *; *

JNC-TN8400 2000-021, 66 Pages, 2000/04


A reliability evaluation for radionuclide transport analysis code, MATRICS, used in radionuclide transport analysis in the natural barrier system PA in H12 report has been carried out. Sensitivity analysis to radionuclide transport parameter in MATRICS and analytical solution has been performed, and the results of each analysis have been compared. Additionally sensitivity analysis using Talbot Method, Crump method and Hosono method has been carried out, and the results of each inverse Laplace transform method has been compared. The conclusions obtained from the results of the evaluation are summarized as follows, (1)In case of the infinite matrix diffusion distance, an error among the results of each calculation is maximum about 0.4% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 5.5% in the range of transmissivity from 1.0$$times$$10$$^{-10}$$ to 1.0$$times$$10$$^{-5}$$(m$$^{2}$$/s). (2)In case of the finite matrix diffusion distance (0.03$$sim$$1.0(m)), an error among the results of each calculation is maximum about 0.7% in the range of Pe number from 1.0 to 100. And, an error among the results of each calculation is maximum about 2.4% in the range of transmissivity from 1.0$$times$$10$$^{-10}$$ to 1.0$$times$$10$$^{-5}$$(m$$^{2}$$/s). 3)By comparing Talbot method with other inverse Laplace transform method, Talbot method is confirmed to give similar results with other inverse Laplace transform method in the range of Pe number from 5.0$$times$$10$$^{-1}$$ to 2.0$$times$$10$$^{3}$$, and that of transmissivity below 1.0$$times$$10$$^{-7}$$(m$$^{2}$$/s). Therefore, it is concluded that the reliability of MATRICS are confirmed by conducting sensitivity analysis in the range of Pe number and transmissivity coefficient used in H12 report.

JAEA Reports

Raman spectroscopic measurements of porewater in bentonite

; ; *

JNC-TN8400 2000-020, 25 Pages, 2000/04


Nature of porewater in bentonite plays important roles on the mass transport in the compacted bentonite used as a physical and chemical buffer material of the multi-barrier system in the high level radioactive waste manegement Higher activation energies of diffusion in the compacted bentonite than those in the aqueous solution is due probably to change in molecular structure of water in the porewater. The Raman spectroscopy was applied to studying the structure of porewater in bentonite at room temperature. Bentonite (Kunipia F, 98-99wt% of Na-smectite) was mixed with ion-exchanged water by water content of 75, 80, 90, 95 and 98wt% of water or with 0.5M NaCl aqueous solution by 75 and 80wt% of NaCl solution. Intensity maxima of the spectra of ion exchanged water, NaCl solution and their porewater were observed near 3200 to 3250, 3400, 3630cm$$^{-1}$$. These bands can be attributed to water molecules forming stronger hydrogen bond in this manner. Ratio of intensity, 3250cm$$^{-1}$$/3400cm$$^{-1}$$, increased from 0.97 to 1.1 with a decrease in water content of 100wt% (water) to 75wt%. On the other hand, intensity ratio of 3400cm$$^{-1}$$/3250cm$$^{-1}$$ of NaCl aqueous solution, 80wt%and 75wt% were 0.92, 1.2 and 1.3, respectively. Since the Raman scattering near 3250cm$$^{-1}$$ was attributed to water molecule forming the strongest hydrogen bonding in the three bands, those changes in intensity ratio suggests an increase in number of water molecule forming strong hydrogen bond in porewater of the bentonite. The constrained porewater possibly results in the high activation energy of diffusion in the compacted bentonite.

JAEA Reports

Experimental study of pyrite oxidation in compacted sodium bentonite

JNC-TN8400 2000-012, 33 Pages, 2000/04


The redox condition of near-field is expected to affect the performance of engineered barrier system. Especially, the oxygen initially existing in the pore space of compacted bentonites strongly affects the redox condition of the near-field. For assessing the influence of the oxygen, the transport parameters of it in the compacted bentonite and consumption process should be known. Therefore, following researches were conducted. In order to understand the diffusion of dissolved oxygen (DO) in compacted bentonite and to predict the effect of DO, the effective diffusion coefficients of DO in compacted sodium bentonite were measured by electrochemistry. As the results, the following relationship between the dry density of compacted sodium bentonite and the effective diffusion coefficient of DO in compacted sodium bentonite was derived: De=1.53$$pm$$0.13$$times$$10$$^{-9}$$exp(-2.15$$pm$$0.24$$times$$10$$^{-3}$$p) where De is the effective diffusion coefficient (m$$^{2}$$s$$^{-1}$$) of DO in compacted sodium bentonite and $$rho$$ is the dry density (kg m$$^{-3}$$) of compacted sodium bentonite. The oxygen concentration in the bentonite is expected to be controlled by oxidation of pyrite as impurity in the bentonite. In order to investigate the above idea, the rates of pyrite oxidation by DO in compacted sodium bentonite were estimated from the experimental data on pyrite-bentonite systems usig the obtained effective diffusion coefficient of DO. The results show that the averages of the rate constants of pyrite oxidation by DO in the bentonite for dry densities of 0.8, 0.9, 1.0, 1.1 and 1.2$$times$$10$$^{3}$$kgm$$^{3}$$ were 1.38$$pm$$0.32$$times$$10$$^{-8}$$, 1.10$$pm$$0.24$$times$$10$$^{-8}$$, 1.16$$pm$$0.35$$times$$10$$^{-8}$$, 9.36$$pm$$2.23$$times$$10$$^{-9}$$ and 7.48$$pm$$1.92$$times$$10$$^{-9}$$ms$$^{-1}$$, respectively. The relationship between the dry density ($$rho$$) and the rate constant (k') was expressed as follows: k'=3.94$$pm$$1.06$$times$$10$$^{-8}$$exp(-1.33$$pm$$0.28$$times$$10$$^{-3}$$$$rho$$) ...

JAEA Reports


Federation of Electric Power Companies of Japan*

JNC-TY1400 2000-001, 464 Pages, 2000/03



JAEA Reports

An Investigation of cementitious materials for radioactive waste repository; Mechanical properties of law alkalinity cementitious materials

Owada, Hitoshi*; Mihara, Morihiro; Iriya, Keishiro*; *

JNC-TN8400 99-057, 43 Pages, 2000/03


Cementitious materials are considered as candidate materials for the geological disposal of high-level radioactive waste and TRU waste. As the pH and the Ca content of leachate from the cementitious materials are high, the host rock and the buffer-material would be degraded by the leachate in the long-term. Therefore, transport properties and parameters such as solubilities and distribution coefficients of radionuclides would be changed and affect the performance of the repository. In order to dissolve this "High pH plobrem", the use of a low alkalinity cement is considered for the disposal. In this study, we summarized the necessity of the low alkalinity cement, and developed the approach of the low alkalinization of cement. And, the following were carried out in this study : A leaching test of cement paste, a fluid test of the mortar and a installation test of the concrete to the trial structure. From the leaching test using the cement paste, we confirmed that we were able to obtain the low alkalinity cement (HFSC) by addition of pozzolanic materials such as silica-fume and flyash. From the result of the fluid test of the mortar, we chose the cement for the practicability evaluation. The practicability of low alkalinity concrete was evaluated by installation test to the trial structure.As a result of these examinations, we proved that the pH value of the leachate from the cementitious material was reduced by adding SF and FA to Portland cement. Simultaneously, SF and FA had to be added in order to obtain the good workability. In addition, workability and mechanical strength of the cement which SF and FA were added are almost equivalent to the ordinary Portland cement. The results shows that the HFSC has high practicability.

268 (Records 1-20 displayed on this page)