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Kato, Tomoko; Fukaya, Yukiko*; Sugiyama, Takeshi*; Nakai, Kunihiro*; Oda, Chie; Oi, Takao
JAEA-Data/Code 2019-002, 162 Pages, 2019/03
JAEA-Data-Code-2019-002.pdf:2.78MB
The radioactive waste generated from Fukushima Daiichi nuclear power station (FDNPS) accident have features such as wide range of radioactivity level (from low to high) and huge amount etc. It would be necessary for the waste from the FDNPS accident to develop suitable disposal concept and to be disposed safely and reasonably. When considering such appropriate disposal concepts in site-generic phase, it is necessary to appropriately develop models and parameters depending on the disposal concepts, such as disposal depth and specification of engineered barrier. In addition, it is desirable to evaluate the safety of repository with common models and parameters independent on the disposal concepts. In the safety assessment of disposal, it is useful to show the difference in performance of repository with "dose" as an indicator of safety assessment. Biosphere model and parameter set and flux-to-dose conversion factors calculated using them are originally dependent on the disposal concepts. However, the biosphere models and the parameter set in safety assessment of near-surface disposal, sub-surface disposal and geological disposal are prepared in each case, and are different according to the age and purpose of the discussion. In this study, an example of biosphere model and parameter-set of groundwater sceinario commonly applicable to various disposal concepts were shown, to calculate flux-to-dose conversion factors, as common indicators independent to disposal concept. And, a set of flux-to-dose conversion factors was also calculated by using the commonly available biosphere model and parameter set. By applying the flux-to-dose conversion factors, it is possible to compare the performance of disposal concepts to the waste generated from FDNPS accident, focusing on the parts depending on the disposal concepts.
Shibata, Atsuhiro; Koma, Yoshikazu; Oi, Takao
Journal of Nuclear Science and Technology, 53(12), p.1933 - 1942, 2016/12
Times Cited Count：19 Percentile：86.61(Nuclear Science & Technology)Asami, Makoto; Watahiki, Hiromi; Oi, Takao; Shibata, Atsuhiro; Ashida, Takashi
JAEA-Data/Code 2015-020, 80 Pages, 2015/11
JAEA-Data-Code-2015-020.pdf:45.07MB
JAEA-Data-Code-2015-020-appendix(DVD-ROM).zip:602.44MB
FY2014 edition of the analysis results on contaminated water in the circulating system and on rubbles/soils of Fukushima Daiichi Nuclear Power Station (1F NPS) was compiled. This technical report shows the function of the electronic file of the FY2014 edition of the analysis results on contaminated water and on rubbles/soils and presents the user manual with example and gives the electronic file by appendix CD.
Asami, Makoto; Watahiki, Hiromi; Oi, Takao; Makino, Hitoshi; Shibata, Atsuhiro; Kameo, Yutaka; Meguro, Yoshihiro; Ashida, Takashi
JAEA-Data/Code 2014-016, 37 Pages, 2014/09
JAEA-Data-Code-2014-016.pdf:37.04MBJAEA-Data-Code-2014-016-appendix(CD-ROM).zip:60.46MB
A database on the analyses of samples obtained from contaminated water in the circulating system of Fukushima Daiichi Nuclear Power Station was built. This database contains the analyses of 25 samples of JAEA and 313 samples of TEPCO which have been published in FY 2011 to FY 2013. Also, as well as the analyses on contaminated water, the information on the stored and treated amount in accumulated water and the amount of produced waste, which has been published by TEPCO and which might be required in order to estimate the inventory of secondary waste (sludge, used vessels) generated by treatment of contaminated water are contained in this database. This technical report shows the function of this database and user manual with example and presents the FY2013 edition of database by appendix CD.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Hayano, Akira; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2013-037, 455 Pages, 2013/12
JAEA-Research-2013-037.pdf:42.0MB
Following FY2011, JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, the tree diagram of methodology of groundwater travel time has been extended for crystalline rock, in addition, tree diagram for sedimentary rock newly has been organized. With regard to (2) study on scenario development, the existing approach has been improved in terms of a practical task, and applied and tested for near field focusing on the buffer. In addition, the uncertainty of some important processes and its impact on safety functions are discussed though analysis. With regard to (3) study on setting radionuclide migration parameters, the approaches for parameter setting have been developed for sorption for rocks and solubility, and applied and tested through parameter setting exercises for key radionuclides.
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.
JAEA-Research 2012-032, 298 Pages, 2012/09
JAEA-Research-2012-032.pdf:33.68MB
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.
Hasegawa, Makoto; Kondo, Hitoshi; Kamei, Gento; Hirano, Fumio; Mihara, Morihiro; Takahashi, Kuniaki; Funabashi, Hideyuki; Kawatsuma, Shinji; Ueda, Hiroyoshi*; Oi, Takao*; et al.
JAEA-Research 2011-003, 47 Pages, 2011/02
JAEA-Research-2011-003.pdf:3.99MB
In 2009, NUMO and JAEA set up a technical commission to investigate the reasonable TRU waste disposal following a cooperation agreement between these two organizations. In this report, the calculation result of radionuclide transport for a TRU waste geological disposal system was described, by using the TIGER code and the GoldSim code at identical terms. Comparing the calculation result, a big difference was not seen. Therefore, the reliability of both codes was able to be confirmed. Moreover, the influence on the disposal site design (Disposal capacity: 19,000 m
) was examined when 10% of the amount of TRU waste increased. As a result, it was confirmed that the influence of the site design was very little based on the concept of the Second Progress Report on Research and Development for TRU Waste Disposal in Japan.
Kawamura, Makoto; Ebashi, Takeshi; Makino, Hitoshi; Niizato, Tadafumi; Yasue, Kenichi; Inagaki, Manabu; Oi, Takao
Oyo Chishitsu, 51(5), p.229 - 240, 2010/12
Uplift, subsidence, denudation, and sedimentation are phenomena over long-term in a regional scale. It is difficult to ignore the impacts of those phenomena on a disposal system completely in long-term. Therefore, type and extent of the impacts on geological and disposal environmental conditions, and disposal systems need to be evaluated quantitatively in order to develop perturbation scenarios. We have been developing a systematic methodology to develop perturbation scenarios based on the appropriate understanding of those phenomena. The variety of the change of geological environment and evolution pattern of the environment, which are caused by the variation of the uplift, subsidence, denudation, sedimentation phenomena and those rates, are understood by arranging the information in the framework of the thermal-hydrological-mechanical-chemical-geometrical (T-H-M-C-G) system, and the impacts of those environmental change to the performance of the repository system are also examined by using the T-H-M-C-G system. In this study, firstly, the potential changes of the geological environment were identified by examination of possible combinations of the uplift/denudation and subsidence/ sedimentation. The effects of the initial environmental condition are also considered. Geohistorical information and View of Modern analogue theory should be used in this stage. This procedure is essential to set up the scenarios regarding uplift/denudation and subsidence/sedimentation, to clarify the trend and/or range of the change of the geological environmental conditions. Then, the phenomena which give the large impacts to a disposal system were extracted based on the T-H-M-C-G system. By applying the developed framework which deals with the impacts on the HLW disposal system realistic view and builds evaluation scenarios and models based on step wise manner, we acquired the prospect that realistic uplift and denudation scenario could be built to this examination procedure.
Kawamura, Makoto; Ebashi, Takeshi; Makino, Hitoshi; Niizato, Tadafumi; Yasue, Kenichi; Oi, Takao
JAEA-Research 2008-119, 32 Pages, 2009/03
JAEA-Research-2008-119.pdf:8.06MB
Uplift, subsidence, denudation, and sedimentation are phenomena over long-term in a regional scale. It is difficult to ignore the impacts of those phenomena on a disposal system completely in long-term. Therefore, type and extent of the impacts on geological and disposal environmental conditions, and disposal systems need to be evaluated quantitatively in order to develop perturbation scenarios. JAEA has been developing a systematic methodology to develop perturbation scenarios based on the appropriate understanding of those phenomena. The variety of the change of geological environment and evolution pattern of the environment, which are caused by the variation of the uplift, subsidence, denudation, sedimentation phenomena and those rates, are understood by arranging the information in the framework of the thermal-hydrological-mechanical-chemical-geometrical (T-H-M-C-G) system, and the impacts of those environmental change to the performance of the repository system are also examined by using the T-H-M-C-G system. In this study, firstly, the potential changes of the geological environment were identified by examination of possible combinations of the uplift/denudation and subsidence/ sedimentation. The effects of the initial environmental condition are also considered. Geohistorical information and Modern analogue theory should be used in this stage. This procedure is essential to set up the scenarios regarding uplift/denudation and subsidence/sedimentation, to clarify the trend and/or range of the change of the geological environmental conditions. Then, the phenomena which give the large impacts to a disposal system were extracted based on the T-H-M-C-G system. By applying the developed framework which deals with the impacts on the HLW disposal system realistic view and builds evaluation scenarios and models based on step wise manner, we acquired the prospect that realistic uplift and denudation scenario could be built to this examination procedure.
Oi, Takao; Inagaki, Manabu; Kawamura, Makoto; Ebashi, Takeshi
JAEA-Research 2008-111, 32 Pages, 2009/03
JAEA-Research-2008-111.pdf:3.95MB
A demonstration of the usefulness of the systematic approach to evaluate the importance of concerns affecting the geological disposal of radioactive wastes.
Ebashi, Takeshi; Koo, Shigeru*; Oi, Takao
Genshiryoku Bakkuendo Kenkyu, 15(2), p.99 - 115, 2009/03
In order to demonstrate the robustness of the design of a high-level waste (HLW) disposal system, an important measure is to preliminarily set parameter values, which take into account safety margins for an acceptable dose. In evaluating the safety margin, it is necessary to estimate a range of parameters for an acceptable dose by a sensitivity analysis based on the appropriate conditions for each scenario. In this study, the comprehensive sensitivity analysis method was applied to performance assessment of a HLW disposal system. This paper presents the approach to assess a safety margin for parameters. As a result, safety margins for the parameters of the engineered barrier system (glass dissolution rate, overpack failure time, buffer thickness) were illustrated under conservative conditions of the natural barrier. Such an approach will provide useful information for scenario analysis and offer insights into the design and construction of a robust system for HLW disposal concept.
Kato, Tomoko; Suzuki, Yuji*; Oi, Takao
Hoken Butsuri, 44(1), p.72 - 79, 2009/03
It is difficult to acquire all of biosphere parameters at the repository site because we have to deal with several hundreds of the parameters in one calculation case of the biosphere assessment. Before site-specific activities, it is important to develop the data acquisition methodology of biosphere parameters applicable to any proposed repository site. In this study, we developed the methodology for identification of the priority of the parameters for the effective data acquisition of biosphere parameters at the site. First of all, flow diagram was constructed to evaluate the availability of the existing generic biosphere dataset. We found that it was effective for the data acquisition at the site to focus on the element-specific parameters with the existing dataset. Secondly, we identified the priority of the data acquisition for element-specific parameters at the site, with considering the variation of radiation dose by combining the significant element-specific parameters. As a result, we identified the availability of the existing generic biosphere dataset and the priority on data acquisition of the element-specific parameters of key radionuclides in the safety assessment of geological disposal that should be acquired at the site. This priority list would be useful for effective data acquisition at the site.
Oi, Takao; Inagaki, Manabu; Kawamura, Makoto; Ebashi, Takeshi
Materials Research Society Symposium Proceedings, Vol.1124, p.407 - 412, 2009/00
In the safety assessment of geological disposal system of radioactive waste, diverse apprehensions have been extracted from the viewpoint of the impact on the safety and the researches relating to those have been carried out strenuously. However, systematical investigation for presenting the relative importance of those has so far scarcely been conducted. The demonstration of the importance is critical issue to contribute the improvement of reliability of safety assessment. In this study, the following investigations were carried out with the goal of developing the systematic approach which can present the relative importance of the apprehensions: (1) Establishment of Total Assessment Work Frame [TAWF], (2) Establishment of the organaization procedure for evaluating the relative importance.
Ebashi, Takeshi; Hwang, Y.-S.*; Lee, Y.-M.*; Oi, Takao; Koo, Shigeru*
Journal of Nuclear Science and Technology, 45(11), p.1138 - 1149, 2008/11
Times Cited Count：11 Percentile：59.06(Nuclear Science & Technology)In this study, as a part of the joint research between JAEA and KAERI, the comprehensive sensitivity analysis method developed by JAEA was applied to a Korean HLW disposal concept that spent fuel will be directly disposed in a rock. The purpose of this study was to confirm whether the threshold values of near-filed parameters yielding a "successful condition" where maximum dose does not exceed a target value can be extracted with regard to direct disposal concept of spent fuel. As a result, the successful conditions composed of near-field parameters were illustrated under different conservative conditions of the natural barrier. In conclusion, the comprehensive sensitivity analysis method can be applied to extraction of a successful condition composed of near-field parameters for direct disposal concept of spent fuel. Such an approach will provide useful information for scenario analysis and offer insights into construction of a robust system for direct disposal concept of spent fuel.
Kawamura, Makoto; Yasue, Kenichi; Niizato, Tadafumi; Tokiwa, Tetsuya; Ebashi, Takeshi; Oi, Takao; Makino, Hitoshi; Ishimaru, Tsuneari; Umeda, Koji
Proceedings of 2008 East Asia Forum on Radwaste Management Conference (2008 EAFORM 2nd Conference) (USB Flash Drive), 6 Pages, 2008/10
Japan Atomic Energy Agency (JAEA) had developed a framework to assess the potential impact of natural phenomena (uplift and denudation/climatic and sea-level changes; earthquakes and faulting; volcanism) on a high level radioactive waste (HLW) disposal system as a part of the total system performance assessment. The framework is focused on identifying key T-H-M-C-G (Thermal-Hydrological-Mechanical-Chemical-Geometrical) process associated with potential changes of the geological environment caused by natural phenomena. By using the framework, we could grasp the relationship between characteristic of natural phenomena and geological environmental conditions (T-H-M-C-G) quantitatively, and grasp the relationship between T-H-M-C-G condition and parameters of performance assessment efficiently. In this paper, we tried to develop perturbation scenarios of uplift and denudation by using the framework. As a result, by applying this framework, we could not only grasp the impacts on the geological environmental conditions (T-H-M-C-G) quantitatively, but the excess and deficiency of information resulting from uplift and denudation.
Oi, Takao; Inagaki, Manabu; Kawamura, Makoto
JAEA-Research 2008-023, 23 Pages, 2008/03
JAEA-Research-2008-023.pdf:4.68MB
In this study, a new concept of the scenario development method to be able to represent the importance of a scenario on geological disposal of HLW in an understandable way was examined with considering the versatility. By the carrying out the scenario development using this method, the information relation to the confidence building such as "the reason why the scenario is important scenario", "the argument which is able to claim completely the safety by the assessment according to the scenario" would be represented in the easy-understand format. Furthermore, the useful information for total performance assessment of geological disposal would be given with the role of each study and the relationship between the studies in the assessment.
Ebashi, Takeshi; Koo, Shigeru*; Oi, Takao
JAEA-Research 2008-019, 142 Pages, 2008/03
JAEA-Research-2008-019.pdf:22.97MB
In this study, comprehensive sensitivity analysis method was applied to HLW geological disposal concept. In this application, level of importance and successful condition for intended parameters on one barrier were extracted under conservative conditions of parameters on the other barrier, taking into account diverse uncertainties on initial stage of stepwise approach. We achieved analysis results with level of importance and successful condition for intended parameters. In conclusion, the comprehensive sensitivity analysis method can be applied to extraction of sensitivity characteristics on each barrier, under conservative conditions. Such study on the applicability of method and the extracted sensitivity characteristics will contribute to construction of a robust barrier and a scenario analysis for initial stage of stepwise approach.
Kawamura, Makoto; Oi, Takao; Niizato, Tadafumi; Yasue, Kenichi; Tokiwa, Tetsuya; Niwa, Masakazu; Shimada, Koji; Kurosawa, Hideki; Asamori, Koichi; Kawachi, Susumu; et al.
JAEA-Research 2008-018, 47 Pages, 2008/03
JAEA-Research-2008-018.pdf:24.18MB
In this report, we sophisticated the framework as a part of the total system performance assessment for two purposes: the first one is quantification of relationship of characteristic of natural phenomena between geological environmental conditions (THMCG), and the other one is quantification of relationship of THMCG condition between parameters of performance assessment. On the other hand, we applied the sophisticated framework to all natural phenomena. As a result, to apply the sophisticated framework, we could show that information integration could carry out efficiently. Moreover, we have checked that the framework was applicable to all phenomena. Furthermore, we could show that suitable scenarios might be chosen by information integration.
Oi, Takao; Kato, Tomoko; Kawachi, Susumu; Kawamura, Makoto
JAEA-Research 2008-014, 14 Pages, 2008/03
JAEA-Research-2008-014.pdf:2.93MB
The method contributing to the improvement of confidence and the systematization of the various information and knowledge under the responsibility of each researcher has examined. As a result, "a systematic compilation method to exhibit the level of the confidence on the assessments" has been developed based on the approach of the international quality management system. It is possible to manifest the aims, intention, contents, approach and process of the study by compiling and presenting the results of the studies using this method. In addition, transparency and traceability would be shown and the adequacy of the obtained result would be claimed by researcher through the conformity assessment for the result of the study. These results would contribute the understanding of reader and improvement of confidence.
Kawachi, Susumu; Oi, Takao; Kawamura, Makoto; Ishihara, Yoshinao*; Ebina, Takanori*
JAEA-Data/Code 2008-006, 55 Pages, 2008/03
JAEA-Data-Code-2008-006.pdf:4.17MB
The investigation and studies of site-specific geological conditions provide much information and data. A system for managing and integrating the technical information was developed (JGIS: JAEA Geological Disposal Information Integration System). In this study we built the conceptual design in order to implement the function of quality management and project management to JGIS. We considered that researchers could access the portal site of the research projects which were set as the WBS (Work Breakdown Structure) items and could confirm which WBS item the research project belonged to in the whole plan. We also considered that the research projects could be managed by using the conformity sheets which were adopted in the quality management system.
