Quasifree neutron knockout reaction reveals a small -Orbital component in the Borromean nucleus B

Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

AA2020-0819.pdf:1.29MB

https://doi.org/10.1103/PhysRevLett.126.082501

A quasifree (,) experiment was performed to study the structure of the Borromean nucleus B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for and orbitals, and a surprisingly small percentage of 9(2)% was determined for . Our finding of such a small component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B. The present work gives the smallest - or -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of or orbitals is not a prerequisite for the occurrence of a neutron halo.

On-line diffusion tracing in Li ionic conductors by the short-lived radioactive beam of Li

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Watanabe, Yutaka*; Ishiyama, Hironobu*; Imai, Nobuaki*; Hirayama, Yoshikazu*; Miyatake, Hiroari; Sataka, Masao; Sugai, Hiroyuki; et al.

Japanese Journal of Applied Physics, 47(8), p.6413 - 6415, 2008/08

https://doi.org/10.1143/JJAP.47.6413

A non-destructive and on-line diffusion tracing in Li ionic conductors has been demonstrated. As a tracer, pulsed beam of Li was implanted into LiGa. By analyzing the time dependent yield of the -particles decaying from Li, diffusion coefficients were extracted with a high accuracy. The ordering of Li vacancies in the Li-deficient phase of LiGa was observed for the first time in terms of the Li diffusion.

The Japanese approach to developing clay-based repository concepts; An Example of design studies for the assessment of sealing strategies

Sugita, Yutaka; Fujita, Tomoo; Takahashi, Yoshiaki*; Kawakami, Susumu; Umeki, Hiroyuki; Yui, Mikazu; Uragami, Manabu*; Kitayama, Kazumi*

Physics and Chemistry of the Earth, 32(1-7), p.32 - 41, 2007/00

https://doi.org/10.1016/j.pce.2006.04.029

The H12 repository concept for vitrified high-level radioactive waste was developed based on a multi-barrier system with the emphasis on robust engineered barrier performance to ensure its feasibility for a wide range of geological conditions typically observed in Japan. The buffer is clay-based and plays a very important role in the engineered barrier system (EBS). The decision to use a volunteer siting process requires maximum flexibility of the repository concept to allow it to be adapted to potential sites and hence a wide range of variants of the basic H12 repository design has been developed. In order to evaluate the feasibility and the applicability of different repository options to specific siting environments, NUMO has established a set of "design factors" which classify the aspects that need to be considered when evaluating the pros and cons of different repository options. A Na-type bentonite from Japan is used as the reference material for all clay-based repository components (buffer, backfill, clay plug, etc.). The characteristics of this bentonite (thermal, mechanical, chemical, hydraulic) have been examined with consideration of various practical constraints (limitation on the repository footprint, the influence of saline water, the interaction of hyperalkaline leachates and practical working environment, etc.). Clay-based seals, which close off the tunnels after emplacement of the EBS, may also be key components for assessment of the repository. Full analyses considering all engineered barrier components (buffer, backfill, clay plug, concrete lining, tunnel, concrete plug, host rock) that may be used in a repository will be an essential future task. As a first step towards this goal, a numerical analysis focusing on hydraulic behaviour at the intersections of the disposal tunnels and the main tunnel is presented to illustrate how the design requirements of clay-based seals can be determined.

The Study plan on applicability to actual geological environment conditions of the engineering technology for geological disposal of high level nuclear-waste through the second phases in Horonobe Underground Research Project

Aoyanagi, Shigeo; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Fujita, Tomoo; Taniguchi, Naoki; Shibata, Masahiro; Konishi, Kazuhiro; Nishimura, Mayuka; Kikuchi, Hirohito*; et al.

JAEA-Review 2006-014, 61 Pages, 2006/03

JAEA-Review-2006-014.pdf:5.03MB

no abstracts in English

Engineering technology research on the performance guarantee for the Engineered Barrier System (EBS)

Kawakami, Susumu; Fujita, Tomoo; Sugita, Yutaka

Hoshasei Haikibutsu Anzen Kenkyu Nenji Keikaku (Heisei-13-NendoHeisei-17-Nendo) Kenkyu Seika Hokokushu, p.216 - 223, 2006/03

no abstracts in English

Studies on design of the engineered barrier system and mechanical stability of rock based on surfaced-based investigation of the Horonobe URL project

Aoyagi, Shigeo; Tanai, Kenji; Matsui, Hiroya; Kawakami, Susumu; Yui, Mikazu

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

This paper presents the design of the disposal design based on surface-based investigations in Horonobe URL project with a focus on the engineered barrier system (EBS) and the estimation of mechanical stability of rock. The purpose of this study is as follows.[1]Establishment of the overall design methodology on engineered barrier system and repository based on the results of surface-based investigation in sedimentary rock.][2]Extraction of issues to be solved in the construction phase of URL through studies based on surface-based investigation.]The applied methods on this study are based on the second progress report (H12)(1999) published by JNC. As results of this study,the design flow shown in H12 report is revised under the consideration of correlation with each field. The typical specification of buffer and overpack (iron) in the geological environment in Horonobe are the same specification as H12 report. The rock around a dry pit at the depth of 450m in Horonobe is expected more stable in long-term than SR-C in H12 report.

Estimation of the applicability on the disposal technology under real geological environment

Matsui, Hiroya; Tanai, Kenji; Kawakami, Susumu; Sato, Toshinori; Yui, Mikazu

JNC TN5400 2005-004, 250 Pages, 2005/09

JNC-TN5400-2005-004.pdf:41.57MB

Japan Nuclear Fuel Development Institute (JNC) published the possibility of the geological disposal independent geological environment in Japan and its scientific basis in H12 progress report. The overall research and development on geological disposal after FY2000 were planned based on the review results of H12 report and initiated the two major goals ; - Demonstration of applicability of disposal technology to specific geological environments - Further understanding of long-term system behaviorThe approach to the first goal for the R&D program from FY2000 to FY2005 is to establish the methodology integrated with disposal technology and geoscitentfic research by the application of the technology developed until FY 2000 on geological environment understood in surface based investigation phase in URL project.This report is described the applicability and future subject derived from the results to apply the design methods of geological disposal developed until FY2000 to

Hydrogen Evolution Behavior in the Corrosion of Carbon Steel in Contact with Magnetite

Taniguchi, Naoki; Tateishi, Tsuyoshi*; Fukudome, Kazuyuki*; Nishimura, Tsutomu*; Kawakami, Susumu

JNC TN8400 2005-014, 36 Pages, 2005/07

JNC-TN8400-2005-014.pdf:0.44MB

It has been reported that the corrosion of carbon steel is accelerated by a contact with magnetite, which is a representative corrosion product in low oxygen environment. It is important to clear the corrosion mechanism in the presence of magnetite for long term prediction of overpack corrosion. There are two possible cathodic reactions in the presence of magnetite coupled with anodic reaction. One is reduction of Fe(III) in magnetite, and the other is hydrogen evolution reaction. If the former dominate the cathodic reaction, corrosion acceleration will be stopped with the consumption of Fe(III). While, if the latter is the main cathodic reaction, corrosion acceleration is possible to be continued for a long time. In this study, corrosion rate and hydrogen evolution behavior were investigated by the immersion test of carbon steel in contact with dummy corrosion product to contribute to understanding the corrosion mechanism.

Material test data of 316FR Steel (IX)

Odaka, Susumu; Kato, Shoichi; Yoshida, Eiichi; Kawakami, Tomohiro*; Suzuki, Takaichi*; Kawashima, Seiichi*; Ishigami, Katsuo*

JNC TN9450 2005-001, 196 Pages, 2005/03

JNC-TN9450-2005-001.pdf:6.7MB

Material test of 316FR steel, which was used for structure material of fast breeder reactor (FBR) has been preformed in New Technology Development Group. In this report, the result of test obtained up to this time was collected. Many valuable data that long time test more than 40000 hours including sodium environment test data in this report will be use for material examination of FBR in the future.Contents of the data sheet are as follows; (1) Material: 316FR Steel, (2) Test environment: In air,in sodium, (3) Test emperature: Room temperature to 800, (4) Test method: According to JIS and FBR metallic materials test manual (Revised edition), (5) Number of data:Tensile tests 234, Creep tests 408, Fatigue tests 201, Creep-fatigue tests 47, Relaxation tests 6,Total 896 This report consists of the printouts fromthe structural material data processing system, SMAT.

Status of Assessment Tools of Corrosion Behavior for Performance Guarantee on Overpacks

Taniguchi, Naoki; Kawakami, Susumu; Jintoku, Takashi; Yui, Mikazu

JNC TN8400 2005-002, 29 Pages, 2005/03

JNC-TN8400-2005-002.pdf:36.7MB

In order to contribute to the safety standards and guidelines for overpacks on which the administration decides, the tools for performance guarantee on overpacks were studied based on the present research products for overpack corrosion. The corrosion modes that should to be considered in repository environments were extracted, and then the assessment methods and examples for each mode was summarized based on current understandings of corrosion behavior of overpacks.The passivation, general corrosion, localized corrosion (pitting corrosion, crevice corrosion, and stress corrosion cracking) and hydrogen embrittlement were extracted and the experimental methods to evaluate the initiation and propagation behavior were presented. The assessment examples based on research products such as second progress report (H12 report) were given.