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JAEA Reports

Study on the System Development for evaluating Long-term Alteration of Hydraulic Field in Near Field (IV) (Summary)

Okutsu, Kazuo*; Morikawa, Seiji*; Shimbo, Hiroshi*; Kuroyanagi, Mikio*; Sahara, Fumihiro*; Murakami, Takeshi*; Aoyama, Yuji*

JNC TJ8400 2005-013, 117 Pages, 2005/02

JNC-TJ8400-2005-013.pdf:3.24MB

To integrate the system for evaluation of long-term hydraulic condition in near field of TRU waste disposal, the engineered barrier, which consists of bentonite buffer and cementitious materials, was employed in the series of laboratory tests. On the bentonite buffer, with the aim of investigating of the effect of (i) interlayer cation in bentonite, (ii) content of siliceous sand and (iii) the ionic strength of ground water on its mechanical and hydraulic properties, series of laboratory tests were conducted. The same lot of bentonite was used in the series of tests to obtain consistent data. In addition, the swelling test of the laminated bentonite with caliumization front was conducted for verification of the proposed constitutive model. On cementitious materials, the altered specimen that produced immersing was investigated the water permeation and also characteristics. The hardened cement paste specimens with W/C=40 to 105% were immersed into deionized water and alteration behavior under diffusion condition was investigated.

JAEA Reports

Study on the System Development for evaluating Long-term Alteration of Hydraulic Field in Near Field (IV)

Okutsu, Kazuo*; Morikawa, Seiji*; Shimbo, Hiroshi*; Kuroyanagi, Mikio*; Sahara, Fumihiro*; Murakami, Takeshi*; Aoyama, Yuji*

JNC TJ8400 2005-012, 272 Pages, 2005/02

JNC-TJ8400-2005-012.pdf:7.05MB

To integrate the system for evaluation of long-term hydraulic condition in near field of TRU waste disposal, the engineered barrier, which consists of bentonite buffer and cementitious materials, was employed in the series of laboratory tests.On the bentonite buffer, with the aim of investigating of the effect of (i)interlayer cation in bentonite, (ii)content of siliceous sand and (iii)the ionic strength of ground water on its mechanical and hydraulic properties, series of laboratory tests were conducted. The same lot of bentonite was used in the series of tests to obtain consistent data. In addition, the swelling test of the laminated bentonite with caliumization front was conducted for verification of the proposed constitutive model.On cementitious materials, the altered specimen that produced immersing was investigated the water permeation and also characteristics. The hardened cement paste specimens with W/C=40 to 105% were immersed into deionized water and alteration behavior under diffusion condition was investigated.

JAEA Reports

Study on the System Development for Evaluating Long-Term Alteration of Hydraulic Field in Near Field, 3 (Summary)

Okutsu, Kazuo*; Morikawa, Seiji*; Taguchi, Katsunori*; Kuroyanagi, Mikio*; Sahara, Fumihiro*; Takase, Hiroyasu*; Aoyama, Yuji*

JNC TJ8400 2003-087, 199 Pages, 2004/02

JNC-TJ8400-2003-087.pdf:4.82MB

The system development for evaluating the long-term alteration of hydraulic field in near field was examined. The "Evidential Support Logic" for ensuring the long-term stability of the repository was developed and evaluated. Furthermore, the developed chemical/mechanical alteration action analysis system was verified and improved. The system was coupled for the long-term alteration evaluation analysis.

JAEA Reports

Study on the System Development for Evaluating Long-Term Alteration of Hydraulic Field in Near Field, 3

Okutsu, Kazuo*; Morikawa, Seiji*; Taguchi, Katsunori*; Kuroyanagi, Mikio*; Sahara, Fumihiro*; Takase, Hiroyasu*; Aoyama, Yuji*

JNC TJ8400 2003-086, 426 Pages, 2004/02

JNC-TJ8400-2003-086.pdf:11.01MB

The system development for evaluating the long-term alteration of hydraulic field in near field was examined. The "Evidential Support Logic" for ensuring the long-term stability of the repository was developed and evaluated. Furthermore, the developed chemical/mechanical alteration analysis system was verified and improved. The system was coupled for the long-term alteration evaluation analysis.

JAEA Reports

Study on the System Development for Evaluating Long-Term Alteration of Hydraulic Field in Near Field II (Summary)

Okutsu, Kazuo*; Morikawa, Seiji*; Takamura, Hisashi*; Hane, Koji*; Tabei, Kazuto*; Sahara, Fumihiro*; Murakami, Takeshi*

JNC TJ8400 2003-050, 140 Pages, 2003/02

JNC-TJ8400-2003-050.pdf:3.13MB

The system development for evaluating long-term alteration of hydraulic field in Near Field was examined.

JAEA Reports

Study on the System Development for Evaluating Long-Term Alteration of Hydraulic Field in Near Field II

Okutsu, Kazuo*; Morikawa, Seiji*; Takamura, Hisashi*; Hane, Koji*; Tabei, Kazuto*; Sahara, Fumihiro*; Murakami, Takeshi*

JNC TJ8400 2003-049, 265 Pages, 2003/02

JNC-TJ8400-2003-049.pdf:7.88MB

The system development for evaluating long-term alteration of hydraulic field in Near Field was examined.

JAEA Reports

Full-scale Demonstration of Sealing Technique in Geological Disposal(III)

Toida, Masaru*; Shiogama, Yukihiro*; Atsumi, Hiroyuki*; Suyama, Yasuhiro*; Kawabata, Junichi*; Ito, Keijiro*; Okutsu, Kazuo*

JNC TJ8400 2003-023, 60 Pages, 2003/01

JNC-TJ8400-2003-023.pdf:2.48MB

To establish sealing technique suitable for geological environmental conditions of Japan, it is necessary to obtain data related with this sealing function through laboratory tests and in-situ tests. It also is necessary to put these data to practical use and to establish the estimating method of the sealing technique. This report deals with the sealing function tests under heating condition of supplying water, following the pressurized tests of supplying water at the AECL in Canada until last year. These test results are reported here together with the data, interpretation and analysis of tracer test results. Information arrangement for the establishment of estimation method of sealing function is also performed.

JAEA Reports

Full-scale Demonstration of Sealing Technique in Geological Disposal(III)

Toida, Masaru*; Shiogama, Yukihiro*; Atsumi, Hiroyuki*; Suyama, Yasuhiro*; Kawabata, Junichi*; Ito, Keijiro*; Okutsu, Kazuo*

JNC TJ8400 2003-022, 213 Pages, 2003/01

JNC-TJ8400-2003-022.pdf:13.05MB

To establish sealing technique suitable for geological environmental conditions of Japan, it is necessary to obtain data related with this sealing function through laboratory tests and in-situ tests. It also is necessary to put these data to practical use and to establish the estimating method of the sealing technique. This report deals with the sealing function tests under heating condition of supplying water, following the pressurized tests of supplying water at the AECL in Canada until last year. These test results are reported here together with the data, interpretation and analysis of tracer test results. Information arrangement for the establishment of estimation method of sealing function is also performed.

JAEA Reports

Study on the system development for evaluating long-term alteration of hydraulic field in Near Field

Okutsu, Kazuo*; *; Takamura, Hisashi*; Hane, Koji*; Takase, Hiroyasu*; DAVID SAVAGE*; Inagaki, Manabu*

JNC TJ8400 2002-032, 115 Pages, 2002/02

JNC-TJ8400-2002-032.pdf:1.28MB

For the high performance evaluation of reliability of TRU waste repository, the system development for evaluating long-term alteration in consideration of the changes action of barrier materials of hydraulic field in Near Field is required. In this research, system development for evaluating long-term alteration of hydraulic field in Near Field was examined. Examination of the basic specification of chemical/dynamic alteration action analysis system used as the composition element of this system and a whole system were performed. The research result of this year is shown below. (1)The system by which the chemical changes happened by Near Field as influence of the exudation liquid from cement material are evaluated was examined. In this year, document investigation about the various processes about chemical alteration and extraction of a choice, presentation of the uncertainty about a model or data, preliminary modeling, a simple analysis tool creation and sensitivity analysis, extraction of the process which should be taken into consideration in a system valuation modeling and a phenomenon analysis model, and a corresponding mathematics model, optimization of the software composition for development of a system valuation modeling, the exercise by the preliminary system analysis model, the experiment plan for the corroboration of a model were shown. (2)In consideration of change of the physical characteristic accompanying chemical alteration of bentonite material and cement material, the system by which the dynamic changes action of repository is evaluated was examined. In this year, arrangement of the dynamics action of repository for long-term were shown. Extraction of a phenomenon made applicable to evaluation was shown. And the dynamic models were investigated and the prototype of the dynamics model that can take into consideration the characteristic of bentonite material was shown. And the basic composition of a dynamic changes action analysis system was shown.

JAEA Reports

Study on the system development for evaluating long-term alteration of hydraulic field in Near Field

Okutsu, Kazuo*; *; Takamura, Hisashi*; Hane, Koji*; Takase, Hiroyasu*; DAVID SAVAGE*; Inagaki, Manabu*

JNC TJ8400 2002-031, 354 Pages, 2002/02

JNC-TJ8400-2002-031.pdf:5.13MB

For the high performance evaluation of reliability of TRU waste repository, the system development for evaluating long-term alteration in consideration of the changes action of barrier materials of hydraulic field in Near Field is required. In this research, system development for evaluating long-term alteration of hydraulic field in Near Field was examined. Examination of the basic specification of chemical/dynamic alteration action analysis system used as the composition element of this system and a whole system were performed. The research result of this year is shown below. (1)The system by which the chemical changes happened by Near Field as influence of the exudation liquid from cement material are evaluated was examined. In this year, document investigation about the various processes about chemical alteration and extraction of a choice, presentation of the uncertainty about a model or data, preliminary modeling, a simple analysis tool creation and sensitivity analysis, extraction of the process which should be taken into consideration in a system valuation modeling and a phenomenon analysis model, and a corresponding mathematics model, optimization of the software composition for development of a system valuation modeling, the exercise by the preliminary system analysis model, the experiment plan for the corroboration of a model were shown. (2)In consideration of change of the physical characteristic accompanying chemical alteration of bentonite material and cement material, the system by which the dynamic changes action of repository is evaluated was examined. In this year, arrangement of the dynamics action of repository for long-term were shown. Extraction of a phenomenon made applicable to evaluation was shown. And the dynamic models were investigated and the prototype of the dynamics model that can take into consideration the characteristic of bentonite material was shown. And the basic composition of a dynamic changes action analysis system was shown.

JAEA Reports

Long-term effect of creep displacement of host-rock on stability of engineered barrier system for TRU waste; Two-dimensional analysis by the non-linear viscoelasticity model

Aoyagi, Takayoshi*; *; Mihara, Morihiro; Okutsu, Kazuo*; Maeda, Munehiro*

JNC TN8400 2001-024, 103 Pages, 2001/06

JNC-TN8400-2001-024.pdf:8.84MB

In the disposal concept of TRU waste, concentrated disposal of wastes forms in large cross-section underground cavities is envisaged, because most of TRU waste is no-heat producing in spite of large generated volume as compared with HLW. In the design of engineered barrier system based on large cross-section cavities, it is necessary to consider the long-term mechanical process such as creep displacement of the host rock from the viewpoint of the stability of engineered barrier system. In this study, the long-term creep displacement of the host rock was calculated using the non-linear viscoelasticity model and the effects on the stability of engineered barrier system was evaluated. As a result, in the disposal concept of crystalline rock, no creep displacement occurred at the time after 1 milion year. On the other hand, in the disposal concept of sedimentary rock, creep displacement of 80$$sim$$90mm occurred at the time after 1 milion year. Also, in this calculation, a maximum reduction of 45mm concerned with the thickness of buffer material was estimated. But these values resulted within allowance of design values. Therefore, these results show that the effects of the creep displacement on the stability of engieered barrier system would not be significant.

JAEA Reports

Research about the long-term stability of TRU waste disposal system

Tanaka, M.*; Fujisawa, O.*; Okutsu, Kazuo*; Takamura, Hisashi*; Aoyagi, Takayoshi*

JNC TJ8400 2001-031, 70 Pages, 2001/02

JNC-TJ8400-2001-031.pdf:6.27MB

no abstracts in English

JAEA Reports

Research about the long-term stability of TRU waste disposal system

Tanaka, M.*; Fujisawa, O.*; Okutsu, Kazuo*; Takamura, Hisashi*; Aoyagi, Takayoshi*

JNC TJ8400 2001-030, 82 Pages, 2001/02

JNC-TJ8400-2001-030.pdf:13.47MB

This research arranged the relation with the events (the events which happen to each part grade of disposal institution and change) produced to the characteristic in connection with low permeability and the disposal system of barrier material, such as permeability. The important events which can affect the long stability of the performance which barrier material has by that cause, and its relation were extracted. And, the physical-properties data acquisition of bentonite supposing the events considered to be generated to a disposal system in the future was carried out. The research result of this year is shown below. (1)About the events considered to affect permeability, "the present knowledge and the reseach result" and the "view of a design about a event" were arranged. And it divided and arranged the time of construction and operation, and after closure. Consequently, the subject required in order to check the long stability of TRU waste disposal system was able to be extracted. (2)In order for the research in the last year to estimate the self-seal nature of a bentonite, swelling pressure and the permeability at the time of the bentonite which generated the maximum swelling pressure under the restricted condition for Na-bentonite and Ca-bentonite 100% material re-swelling to the space produced after that were acquired. About this result, the view of effective bentonite dryness density was applied, and the self-seal performance of the assumed material (bentonite 70%, silica 30%) examined in TRU waste disposal concept examination document was evaluated. In order to check the validity of the evaluation in the last year, the self-seal performance check experiment was conducted about the silica mixture bentonite. Consequently, the soundness of a barrier system was able to be checked by the specification of H12 TRU report.

JAEA Reports

A Study of disposal concept for TRU waste, 5; A Study on the mechanical properties of engineered barrier materials

Tanaka, M.*; Yamamoto, H.*; Fujisawa, O.*; Okutsu, Kazuo*; Miura, K.*; Takamura, Hisashi*

JNC TJ8400 2000-036, 196 Pages, 2000/02

JNC-TJ8400-2000-036.pdf:23.76MB

TRU waste should be isolated from biosphere for a long period of time as it includes long lived nuclides. In this study, (1) data were conected on the mechanical properties of engineered barrier materials, (2) affection on the mechanical properties of Na bentonito by salt water was studied and (3) soundness of the disposal system against changes in the volume of engineered banier was evaluated, to examine critical events related to the long-term soundness of the disposal system. Described below are the results of the studies. (1) The swelling pressure, swelling amount and permeability were obtained for a material consisting of NaCa-exchanged bentonito and silica sand with a relative weight of 30% (with a dry density of 1.6 Mgm$$^{-3}$$) by supplying saturated calcium hydroxide aqeous solution. As a result, it was confirmed that the swelling pressure and permeability were approximately estimated from the relation between these properties and the effective dry density of bentonito. (2) The swelling pressure, swelling amount and permeability were obtained for a material consisting of salty Na bentonito and silica sand with a relative weight of 30% (with a dry density of 1.6 Mgm$$^{-3}$$) by supplying artifical salt water. As a result, it was confirmed that these properties were approximately these properties of NaCa-bentonito. (3) Tests were conducted as a part of the evaluation of system soundness against changes in the volume of engineered barrier. Development of a void around bentonito was assumed. Self sealing of Na and NaCa-exchanged bentonito, and theirs water cut-off capability and swelling pressure were investigated.As a result, it was confirmed that the change of permeability and swelling pressure under self sealing of bentonito. Based on the test results (i.e. the both relations between the swelling pressure and dry density, and the permeability and dry density), soundness of the system was verified against changes of the volume of engineered barrier materials.

JAEA Reports

A Study of disposal concept for TRU waste, 5; Adtudy on the mechanical properties of engineered barrier materials

Tanaka, M.*; Yamamoto, H.*; Fujisawa, O.*; Okutsu, Kazuo*; Miura, K.*; Takamura, Hisashi*

JNC TJ8400 2000-035, 59 Pages, 2000/02

JNC-TJ8400-2000-035.pdf:8.87MB

no abstracts in English

JAEA Reports

Design research about geological disposal facility (II)

Horita, M.*; *; Okutsu, Kazuo*; Yamamoto, Takuya*; Amemiya, Kiyoshi*

JNC TJ8400 2000-022, 303 Pages, 2000/02

JNC-TJ8400-2000-022.pdf:10.42MB

This report gives supplementary information and discussions on issues of the high-level waste geological disposal study. The following subjects are discussed ; (1)Evaluation of the effects of coefficient of lateral pressure to the specifications of disposal facilities (2)Functional development of remote operational machinery (3)Arrangement of basic data on cost estimation for disposal (4)Understanding of engineering countermeasures to potential phenomena deep under the ground (5)Selection of construction technologies (6)Establishment of the disposal concept under the coasts. For the coefficient of lateral pressure equal to 2, the cross section of disposal drift, the disposal drift spacing, the waste package pitch in the disposal drift and the specification of supporting system are designed. They are compared with those for the case of coefficient of lateral pressure equal to 1. In the case of coefficient of lateral pressure equal to 2, total length of drifts is 1.5 times, and total excavation volume is 1.8 times larger than later case. For the sealing, transportation and emplacement equipment for waste, technology of the fundamental function, remote operation, accidental events and countermeasures are discussed. The plan for developments on those items is proposed. The item of the cost for the construction, operation, and backfilling are discussed. The surface facilities, and, worker arrangement plan are proposed. For the potential phenomena encountered deep under the ground, the countermeasures are investigated form the construction experience, and the future research subjects are discussed for the underground research laboratory. For the construction technologies, the experience of construction management for the tunnel is investigated, and, the research subjects are proposed. For the disposal concept under coasts, rock condition, design condition, construction management, and quality control are compared with the disposal concept under the ground. The ...

JAEA Reports

Investigation on sealing technique in geological disposal

Toida, Masaru*; Masumoto, Kazuhiko*; *; Okutsu, Kazuo*; *

JNC TJ8400 2000-020, 68 Pages, 2000/02

JNC-TJ8400-2000-020.pdf:9.45MB

For the geological disposal of high level radioactive wastes, after placement of the wastes, it is necessary to close off (to be called "sealing" hereafter) the underground potential passages (disposal pits, disposal tunnels, main and connecting tunnels and access tunnels) with an effective combination of engineered barriers such as buffers, backfiling materials, plugs and grout. It is necessary to ensure the long-term durability to isolate disposed wastes in the system. The results of the research works this year are as follows ; (1)The objectives are to discuss the design of tunnel sealing experiments at URL site. The results of research were about (a)tracer experiment and numerical analysis (b)evaporation measurement (c)presentation at the coordination meeting. (2)The discussion was about the equipment of inclined compaction methods and bearing capacity of rock against pressures for the concrete plugs.

JAEA Reports

System evaluation for the volume change of the engineered barrier

Aoyagi, Takayoshi*; Mihara, Morihiro; Tanaka, M.*; Okutsu, Kazuo*

JNC TN8400 99-058, 55 Pages, 1999/11

JNC-TN8400-99-058.pdf:6.84MB

For the emplaced waste in TRU waste disposal facility, it may have the void for waste bodies it. And, generating void which accompanies those component elution in concrete pit and filler in which the cement material becomes the candidate material is assumed. It is considered that the security of the diffusion control in the bentonite is not done when these voids collapsed, and when it generated the volume change inside the buffer material (bentonite). The imperfect blockage of the void by not obtaining, the sufficient swelling pameability swelling bentonite is a cause on this. Then, volume change of the bentonite inside is analyzed in this study under the conservative estimation. And the following are tested: Self-sealing, maximum swelling rate, density distribution change of the batonite. Evaluation of the engineered barrier system for volume change from the result was carried out. Prior to the evaluation, generating void was calculated based on the conservative estimation. The density of the buffer material as it assumed the blocking by buffer material uniformly awelling using this calculated data, was obtained. By the permeability got from existing research result which shows the relationship between density and permeability of the bentonite, it was confirmed to become diffusion control in the buffer material inside, in existing engineered barrier specification. Next, it was tested, when the conservative void of the superscription was assumed, in order to confirm whether it does the security, as permeability necessaly for maintaining diffusion control, puts it for the swelling of actual bentonite. As the result, it was possible to confirm sufficient swelling performance in order to do the security of the diffusion control in Na-bentonite. However, the swelling performance greatly lowered by comparing Na-bentonite in Ca-bentonite with under 1/6. The increase of the permeability not do the security of the diffusion control, when it was based on void quantity ...

JAEA Reports

Study on construction technology for repository

Tanai, Kenji; Iwasa, Kengo; Hasegawa, Hiroshi; Miura, K.*; Okutsu, Kazuo*; Kobayashi, Masaaki*

JNC TN8400 99-046, 177 Pages, 1999/11

JNC-TN8400-99-046.pdf:6.03MB

For the construction of underground facilities comprising access tunnels, connecting tunnels, main tunnels and disposal tunnels, a large number of tunnels will be excavated in deep rock formations. These excavations will extend hundreds kilometers in total length. Therefore, special attention must be paid, to transporting large volume of debris, ventilation, emergency escape routes in case of accident, and other factors. In addition, special attention must also paid to potential accidents which might in underground excavations, including unstable facing phenomena (such as collapse and swelling of facing at weak layer sections), spring water flow resulting collapse of rock, gas eruption, and rock burst. While considering these factors to be emphasized during the construction of geological disposal facilities, the investigation reviewed the existing working methods on individual construction technologies of access tunnels, main tunnels, connecting tunnels, disposal tunnels, and disposal pit, based on the recognition that the present state deals with a wide range of geological environments, and conducted investigation about the construction methods for each tunnel on the basis current technologies, and described the outline of these methods. Furthermore, for the items to be particulaly emphasized on site characterization koko and siting data such as ground pressure and spring water, the investigation reviewed the current countermeasure works, and made survey on the phenomena appeared during actual tunnel construction works and their countermeasres, and carried out a study on effectiveness of these countermeasures. This constructing of disposal site in deep geological formations is basically possible by applying, or confirming, current excavation technologies for tunnels and underground facilities, A systematic construction system combines separate technologies relating to construction, (excavation technology, tunnel support work method, etc.). Such systems ...

JAEA Reports

Backfilling of the underground facilities on a disposal site

Sugita, Yutaka; Fujita, Tomoo; Tanai, Kenji; Hasegawa, Hiroshi; Furuichi, Mitsuaki*; Okutsu, Kazuo*; Miura, K.*

JNC TN8400 99-039, 58 Pages, 1999/11

JNC-TN8400-99-039.pdf:3.19MB

Regarding disposal techniques of high-level radioactive waste (HLW), the HLW is vitrified and then stored for cooling for a period of 30 to 50 years. After cooling, the HLW is isolated in the deep underground. The concept of geological disposal is based on the requirement to enclose the HLW in the deep underground for the long-term durability of the human's environmental safety. Backfilling of a repository is a unique activity on the geological disposal. If underground tunnels excavated to construct the repository are left, they may have significant influences on the barrier performance of an entire repository, such as: the mechanical stability of a tunnel may be damaged by rock stresses and a tunnel may provide a fast pathway for ground water flow. Therefore, the underground facilities are expected to be backfilled with a backfilling material after emplacement of the HLW and a buffer material. The material for the backfilling of the underground facilities is backfilling material. In this report, bentonite-aggregate mixture is considered, as one of the candidate materials for the backfilling material. Aggregate imitates the muck that is generated during construction phase of the underground facilities. The combination of backfilling, plugging and grouting is considered in some underground situations. Plug is composed of concrete material or clay-based one. Grouting material is concrete material or clay-based one, too. In this report, the concept of the backfilling, mechanical and hydrological characteristics of the bentonite-aggregate mixture, the function, work methods and a schedule of the backfilling materials, plugging and grouting are considered, and items of quality control for the bentonite-aggregate mixture, concrete material and grouting are listed.

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