Yamada, Tomonori; Takebe, Toshihiko*; Ishizuka, Ippei*; Daido, Hiroyuki*; Hanari, Toshihide; Shibata, Takuya; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; et al.
Journal of Nuclear Science and Technology, 56(12), p.1171 - 1179, 2019/12
We describe a new chipping technique combined with a water-jet technique as one of the candidate techniques for the retrieval of fuel debris and support structures as part of the decommissioning of the Fukushima Daiichi Nuclear Power Station. We performed proof-of-principle experiments to demonstrate the removal capability of metal parts, where we focused on the observation of removal processes from a metallic sample using a 5.5-kW continuous wave fiber laser combined with continuous and pulsed water jets.
Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.
Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12
The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.
Deguchi, Akira*; Umeki, Hiroyuki*; Ueda, Hiroyoshi*; Miyamoto, Yoichi; Shibata, Masahiro; Naito, Morimasa; Tanaka, Toshihiko*
LBNL-1006984 (Internet), p.12_1 - 12_22, 2016/12
The H12 report demonstrated the feasibility of safe and technically reliable geological disposal in 1999. The Government of Japan re-evaluated the geological disposal program in terms of technical feasibility based on state-of-the-art geosciences and implementation process, because more than 10 years have passed from H12 and the Great Earthquake and nuclear accident have increased public concern regarding nuclear issues and natural hazards to cause accidents at nuclear facilities. Following the re-evaluation, the Government concluded further to promote geological disposal program, and thus the Basic Policy for Final Disposal was revised in 2015 including a new approach to siting process with identification of "Scientifically Preferable Areas". NUMO and relevant research organizations such as JAEA have been carrying out R and D activities to increase technical reliability for geological disposal. NUMO has started to develop a generic safety case.
Goto, Takahiro*; Mitsui, Seiichiro; Takase, Hiroyasu*; Kurosawa, Susumu*; Inagaki, Manabu*; Shibata, Masahiro; Ishiguro, Katsuhiko*
MRS Advances (Internet), 1(63-64), p.4239 - 4245, 2016/00
NUMO and JAEA have conducted a joint research since FY2011, which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation stage for deep geological disposal of radioactive waste. As a part of this joint research, we have been developing glass dissolution models which consider various processes in EBS, such as precipitation of Fe-silicates associated with iron overpack corrosion, and Si transport through corrosion products in the cracked overpack. The objectives of the modeling work are to evaluate relative importance of relevant processes and to identify further R&D issues towards development of a convincing safety case. Sensitivity analyses suggested that predicted glass dissolution time ranges from 110 to 110 years or more due to uncertainties in the current understanding of the key processes, namely precipitation of Fe-silicates and transport characteristics of the altered glass layer.
Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Kashiwagi, Mieko; Grisham, L. R.*; Hatayama, Akiyoshi*; Shibata, Takanori*; Yamamoto, Takashi*; Akino, Noboru; Endo, Yasuei; et al.
Fusion Engineering and Design, 96-97, p.616 - 619, 2015/10
In JT-60 Super Advanced for the fusion experiment, 22A, 100s negative ions are designed to be extracted from the world largest ion extraction area of 450 mm 1100 mm. One of the key issues for producing such as high current beams is to improve non-uniform production of the negative ions. In order to improve the uniformity of the negative ions, a tent-shaped magnetic filter has newly been developed and tested for JT-60SA negative ion source. The original tent-shaped filter significantly improved the logitudunal uniformity of the extracted H ion beams. The logitudinal uniform areas within a 10 deviation of the beam intensity were improved from 45% to 70% of the ion extraction area. However, this improvement degrades a horizontal uniformity. For this, the uniform areas was no more than 55% of the total ion extraction area. In order to improve the horizontal uniformity, the filter strength has been reduced from 660 Gasuscm to 400 Gasuscm. This reduction improved the horizontal uniform area from 75% to 90% without degrading the logitudinal uniformity. This resulted in the improvement of the uniform area from 45% of the total ion extraction areas. This improvement of the uniform area leads to the production of a 22A H ion beam from 450 mm 1100 mm with a small amount increase of electron current of 10%. The obtained beam current fulfills the requirement for JT-60SA.
Osaki, Hirotaka; Shimazaki, Yosuke; Sumita, Junya; Shibata, Taiju; Konishi, Takashi; Ishihara, Masahiro
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05
For the design on the VHTR graphite components, it is desirable to employ graphite material with higher strength. IG-430 graphite has been developed as an advanced candidate for VHTR. However, the new developed IG-430 does not have enough databases for the design of HTGR. In this paper, the compressive strength (Cs) of IG-430, one of important strengths for design data, is statistically evaluated. The component reliability is evaluated based on the safety factors defined by the graphite design code, and the applicability as the VHTR graphite material is discussed. It was found that IG-430 has higher strength (about 11%) and lower standard deviation (about 27%) than IG-110 which is one of traditional graphites used for HTGR, because the crack in IG-430 would not easy to propagate rather than IG-110. Since fracture probability for IG-430 is low, the higher reliability of core-component will be achieved using IG-430. It is expected that IG-430 is applicable for VHTR graphite material.
Shibata, Masahiro; Kamei, Gento
Nippon Genshiryoku Gakkai-Shi, 57(4), p.271 - 275, 2015/04
no abstracts in English
Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.
JAEA-Research 2014-030, 457 Pages, 2015/03
JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.
Ebashi, Takeshi; Kawamura, Makoto*; Inagaki, Manabu*; Koo, Shigeru*; Shibata, Masahiro; Itazu, Toru; Nakajima, Kunihiko*; Miyahara, Kaname; Apted, M. J.*
Materials Research Society Symposium Proceedings, Vol.1665, p.39 - 45, 2014/07
In Japan, the likelihood of uplift/erosion on repository performance and waste isolation can be typically greatly reduced or excluded by careful siting, however, the inability to completely exclude the uplift/erosion scenario may require an analysis of the consequences of such a scenario. For this purpose, an assessment approach has been developed to more realistically treat the effect of uplift/erosion for a hypothetical repository located in sedimentary host rock. A key advantage to this approach is the extrapolation of the geohistory of modern analogue sites to develop credible initial inputs for future volunteer sites that may be poorly characterized at the initial stages of site investigation. In addition, the approach provides a systematic basis for bounding the range of possible evolution in thermal-hydrological-mechanical-chemical conditions of a repository experiencing different uplift/ erosion rates.
Hatanaka, Koichiro; Shibata, Masahiro
Tekisuto "Kakunenryo Saikuru" (Internet), 6 Pages, 2014/06
no abstracts in English
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
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.
Shimemoto, Hidenori; Yamaguchi, Masaaki; Wakasugi, Keiichiro; Shibata, Masahiro
JAEA-Research 2013-012, 35 Pages, 2013/10
In this study, we focus on uplift and erosion and climatic and sea-level changes among natural phenomena and pick up fluvial erosion is main and means large velocity between different type of erosion in Japan, and developed conceptual modeling of geomorphic change due to fluvial erosion with respect to fluvial erosion and sedimentation system, to evaluate the potential impact of exposure case of high level radioactive waste to land surface. Conceptual modeling of geomorphic change caused by fluvial erosion is developed with riverhead and downriver, such catchment areas are not treated until now, by conceptualization of geomorphic change on river due to uplift and denudation and climatic and sea-level changes for about last hundred and twenty thousand years. Furthermore, we analysis the depth and width of deepening and lateral erosion around river channel using the data of alluvium and show an example of the setup method concerning dimension on conceptual model to estimate the erosion volume contribute to the evaluation as to high level radioactive waste exposure process to land surface. We illustrate by an example the dimension as to valley within the central Japanese mountains using DEM data on conceptual model at riverhead. We develop conceptual modeling of geomorphic change on the basis of the feature on fluvial erosion in Japan and set basic intelligence to evaluate the potential impact of repository exposure to land surface caused by fluvial erosion, based on above study.
Wakasugi, Keiichiro; Nakajima, Kunihiko*; Shimemoto, Hidenori; Shibata, Masahiro; Yamaguchi, Masaaki
Proceedings of 21st International Conference on Nuclear Engineering (ICONE-21) (DVD-ROM), 9 Pages, 2013/07
In Japan, uplift and erosion scenarios must be analysed since this natural phenomena would be inevitable at most sites in Japan. It's increasingly important to enhance the confidence of the assessment for the uplift and erosion scenarios, as no assessment cut-off times have yet been defined. In this context, this study carried out bounding analysis to find out parameter conditions to satisfy hypothetical dose criteria. The results show that there are no cases that satisfy 10 microSv/y. However, all cases are below 300 microSv/y. The discussion also implies that to accelerate the release from the EBS for minimising the dose in later phase is inadequate and ineffective at all, due to multiple barriers and multiple safety functions. In principal, the influence of uplift and erosion should be reduced by appropriate site selection and design as much as possible to ensure the sufficient nuclides decay while the repository is staying at the deep underground.
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 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.
Inagaki, Manabu*; Tanaka, Tatsuya*; Hashimoto, Shuji*; Maekawa, Keisuke; Shibata, Masahiro
JAEA-Research 2011-056, 37 Pages, 2012/03
In Japan, a step-wise approach is applied in the site selection process for the geologic disposal site. Preliminary surface-based investigations will be followed by detailed investigations. The basic repository concept, including underground design and layout, will be discussed at the end of surface-based investigations. The repository concept will depend on the spatial extent of the candidate rock formation(s) and their barrier performance. However, information obtained from the surface is limited and includes uncertainties. It is thus important to assess host rock performance considering uncertainties. In this study, methodology for evaluation of geological conditions has been developed that focuses on determining the usable volume of host rock with specific performance characteristics. Initially, multiple performance indices have been discussed and defined from the viewpoint of barrier performance. Then the evaluation procedure is illustrated by using the dataset obtained from the Horonobe Underground Research Laboratory Project. Finally the proposed procedure is reviewed and future challenges are extracted.
Wakasugi, Keiichiro; Koo, Shigeru*; Shibata, Masahiro
JAEA-Research 2011-006, 31 Pages, 2011/06
Although confirmation of the long-term safety of the constructed geological disposal system has been conducted by using scenario, model and data according to the internationally agreed methodology, there were a few researches that focused on individual safety functions and their relationships. This is because multiple safety functions are a fundamental concept for ensuring the safety of the geological disposal, and the long-term safety is accomplished by the whole system. Therefore, we developed a methodology to identify performance of the individual safety functions and their relationships considering the characteristic of the multiple safety functions, and examined the safety functions in the engineered barrier system based on this methodology. The results from this study are useful for constructing design requirements for the system components of the geological disposal as well as developing repository concept.
Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06
Transverse momentum distributions and yields for , and in collisions at = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different collisions. We also present the scaling properties such as and scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.
Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.
Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04
Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.
Miyahara, Kaname; Tachi, Yukio; Kitamura, Akira; Mitsui, Seiichiro; Sawada, Atsushi; Shibata, Masahiro; Neall, F.*; McKinley, I. G.*
Proceedings of 2011 International High-Level Radioactive Waste Management Conference (IHLRWMC 2011) (CD-ROM), p.292 - 298, 2011/04
As the Japanese deep geological disposal programme prepares for milestones at which volunteer sites need to be compared, it is critical that any supporting post-closure safety assessment is done as realistically as possible. Because of the subtle system understanding needed to integrate diverse theoretical, laboratory, field and analogue models, data and observations into the high-level parameters that are incorporated into performance assessment models, normal QA procedures tend to fail completely. This problem is discussed further in this paper and solutions outlined, which build on recent developments of supporting knowledge engineering tools.
Fujita, Tomoo; Taniguchi, Naoki; Matsui, Hiroya; Tanai, Kenji; Maekawa, Keisuke; Sawada, Atsushi; Makino, Hitoshi; Sasamoto, Hiroshi; Yoshikawa, Hideki; Shibata, Masahiro; et al.
JAEA-Research 2011-001, 193 Pages, 2011/03
This report summarizes the progress of research and development on geological disposal during the surface-based investigation phase (2001-2005) in the Horonobe Underground Research Laboratory project, of which aims are to apply the design methods of geological disposal and mass transport analysis to actual geological conditions obtained from the surface-based investigations in the Horonobe Underground Research Laboratory project as an example of actual geological environment.