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Journal Articles

Study of rational safeguards for the treatment of radioactive waste containing nuclear materials

Nakatani, Takayoshi; Shimizu, Ryo; Tazaki, Makiko; Kimura, Takashi; Tamai, Hiroshi; Suda, Kazunori

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11

Currently, JAEA is in the advancing of decommissioning own nuclear facilities, and some facilities have been handling nuclear materials. In decommissioning, it is necessary to consider rational methods while keeping nuclear non-proliferation and transparency, including treatment of radioactive waste generated from these facilities and methods for terminating safeguards. In this study, we considered the above issues regarding waste treatment with reference to the guidance of Safeguards by Design (SBD) published by the International Atomic Energy Agency (IAEA).

Journal Articles

Investigation and consideration of the requirements and issues from the viewpoint of the IAEA safeguards for the decommissioning of nuclear facilities

Kimura, Takashi; Fukui, Yasuhito; Tazaki, Makiko; Nakatani, Takayoshi; Shimizu, Ryo; Suda, Kazunori

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11

no abstracts in English

Journal Articles

Research on factor analysis for achieving denuclearization, 10; Summary of research; Analysis of denuclearization factors of target countries and lessons learned from the analysis

Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Nakatani, Takayoshi; Tamai, Hiroshi; Suda, Kazunori

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11

no abstracts in English

Journal Articles

Research on factor analysis for achieving denuclearization, 11; Concept of the disabling nuclear facilities in denuclearization

Shimizu, Ryo; Tazaki, Makiko; Kimura, Takashi; Nakatani, Takayoshi; Suda, Kazunori

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2021/11

no abstracts in English

Journal Articles

Three-dimensional bulk Fermi surfaces and Weyl crossings of Co$$_2$$MnGa thin films underneath a protection layer

Kono, Takashi*; Kakoki, Masaaki*; Yoshikawa, Tomoki*; Wang, X.*; Sumida, Kazuki; Muro, Takayuki*; Goto, Kazuki*; Sakuraba, Yuya*; Umetsu, Rie*; Kimura, Akio*

Physical Review B, 104(19), p.195112_1 - 195112_8, 2021/11

Angle-resolved photoelectron spectroscopy utilizing soft X-ray synchrotron radiation was applied to Heusler-type Co$$_2$$MnGa thin films that have a 1-nm Al capping layer. The bulk Fermi surfaces and band structures varied along the out-of-plane momentum, stemming from the three-dimensional crystal structure, in the absence of any in situ surface treatment. In addition, there were characteristic intersecting bands (Weyl cones), with crossing points near the Fermi level, which were consistent with computed results. The Weyl cones are of bulk origin and are responsible for the high anomalous Nernst and the anomalous Hall coefficients. A close comparison of the experimental band structures in Co$$_2$$MnGe and Co$$_2$$MnGa indicated that the rigid band picture is valid in both alloys and that fine carrier tuning is possible by replacing Ga with Ge to improve the anomalous conductivity.

Journal Articles

Analysis on essential factors for successful denuclearization

Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Tamai, Hiroshi; Nakatani, Takayoshi; Suda, Kazunori

Proceedings of INMM & ESARDA Joint Annual Meeting (Internet), 10 Pages, 2021/08

Journal Articles

Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$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

 Times Cited Count:10 Percentile:98.7(Physics, Multidisciplinary)

A quasifree ($$p$$,$$pn$$) experiment was performed to study the structure of the Borromean nucleus $$^{17}$$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 $$1s_{1/2}$$ and $$0d_{5/2}$$ orbitals, and a surprisingly small percentage of 9(2)% was determined for $$1s_{1/2}$$. Our finding of such a small $$1s_{1/2}$$ 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 $$^{17}$$B. The present work gives the smallest $$s$$- or $$p$$-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of $$s$$ or $$p$$ orbitals is not a prerequisite for the occurrence of a neutron halo.

Journal Articles

Dating of buried wood logs and fragments for high resolution reconstruction of landslide histories; Case studies in the Japanese Alps region in the historical times

Yamada, Ryuji*; Kimura, Takashi*; Kariya, Yoshihiko*; Sano, Masaki*; Tsushima, Akane*; Li, Z.*; Nakatsuka, Takeshi*; Kokubu, Yoko; Inoue, Kimio*

Sabo Gakkai-Shi, 73(5), p.3 - 14, 2021/01

We discuss the applicability of dating methods for determining landslide chronologies in relation to the type of samples and the sampling location. Case studies are carried out with fossil wood samples buried in the colluvial soil of large-scale landslides occurred in two areas of the Japanese Alps region. Ages are determined by accelerator mass spectrometry radiocarbon dating and dendrochronological analysis using the oxygen isotope composition of tree ring cellulose. Most of ages for Dondokosawa rock avalanche are concordant with the period of AD 887 Ninna (Goki-Shichido) earthquake. Ages for Ohtsukigawa debris avalanche are not concentrated in a specific period. In order to obtain accurate age of large-scale landslide, utilizing buried large diameter tree trunk or branches with the good preservation condition has a lot of advantages because it allows us to compare the landslide chronology with historical records of heavy rainfall and large earthquakes.

Journal Articles

Spin-polarized Weyl cones and giant anomalous Nernst effect in ferromagnetic Heusler films

Sumida, Kazuki; Sakuraba, Yuya*; Masuda, Keisuke*; Kono, Takashi*; Kakoki, Masaaki*; Goto, Kazuki*; Zhou, W.*; Miyamoto, Koji*; Miura, Yoshio*; Okuda, Taiichi*; et al.

Communications Materials (Internet), 1, p.89_1 - 89_9, 2020/11

Journal Articles

Research on factor analysis for achieving denuclearization, 9; DPRK's denuclearization

Shimizu, Ryo; Kimura, Takashi; Tazaki, Makiko; Nakatani, Takayoshi; Tamai, Hiroshi; Suda, Kazunori

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2020/11

Efforts to denuclearize North Korea have been made by neighboring countries and related countries, but they have not abandoned North Korea's nuclear development. In this report, we will analyze the North Korean denuclearization negotiations that have been carried out so far, and report on the elements necessary for the realization of North Korea's denuclearization obtained from the past history.

Journal Articles

Research on factor analysis for achieving denuclearization, 6; Denuclearization of former republics of the Soviet Union

Kimura, Takashi; Tazaki, Makiko; Nakatani, Takayoshi; Shimizu, Ryo; Tamai, Hiroshi; Suda, Kazunori

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2020/11

Following the collapse of the Soviet Union in 1991, Ukraine, Kazakhstan, and Belarus (the former three Soviet Union countries) unintentionally deployed nuclear weapons within their territory. The former three Soviet Union countries achieved denuclearization by transferring the deployed warheads and the delivery system of the nuclear weapons to Russia for disposal. This report gives our analysis of the success factors for achieving denuclearization by investigating the efforts towards denuclearization of such countries, the relevant frameworks such as the Treaty on the Reduction of Strategic Arms, etc.

Journal Articles

Research on factor analysis for achieving denuclearization, 8; International frameworks for denuclearization and roles of the US, 1; Denuclearization of Iraq, Libya and Iran

Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Tamai, Hiroshi; Nakatani, Takayoshi; Suda, Kazunori

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2020/11

no abstracts in English

Journal Articles

Research on factor analysis for achieving denuclearization, 7; Framework on the non-proliferation of weapons scientists and engineers

Suda, Kazunori; Kimura, Takashi; Nakatani, Takayoshi; Shimizu, Ryo; Tazaki, Makiko; Tamai, Hiroshi

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2020/11

The disintegration of central control in the former Soviet Union (FSU) prompted concerns among western countries that weapons scientists and engineers would flee to countries to acquire know-hows of weapons of mass destruction. To reduce this threat, the International Science and Technology Center (ISTC) was established at Moscow aimed at engaging weapons scientists and engineers from the FSU in peaceful use of nuclear technologies. In order to contribute the denuclearization study, it was discussed on contributions and good practice of the ISTC including non-proliferation measures of weapons scientists and engineers, deploying research results.

Journal Articles

Unveiling spin-dependent unoccupied electronic states of Co$$_{2}$$MnGe (Ga) film via Ge (Ga) $$L_{2,3}$$ absorption spectroscopy

Yoshikawa, Tomoki*; Antonov, V. N.*; Kono, Takashi*; Kakoki, Masaaki*; Sumida, Kazuki; Miyamoto, Koji*; Takeda, Yukiharu; Saito, Yuji; Goto, Kazuki*; Sakuraba, Yuya*; et al.

Physical Review B, 102(6), p.064428_1 - 064428_7, 2020/08

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Introduction to nuclear security, 2; Efforts to strengthen nuclear security

Suda, Kazunori; Kimura, Takashi

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 62(6), p.334 - 338, 2020/06

Amid growing concerns about potential nuclear terrorism, discussions have been conducted internationally to strengthen the nuclear security. In this series, we will explain the efforts of the international community to strengthen the nuclear security and the reflection of the treaty for the nuclear security and the IAEA nuclear security recommendations in the domestic laws.

Journal Articles

Manipulation of saturation magnetization and perpendicular magnetic anisotropy in epitaxial Co$$_{x}$$Mn$$_{4-x}$$N films with ferrimagnetic compensation

Ito, Keita*; Yasutomi, Yoko*; Zhu, S.*; Nurmamat, M.*; Tahara, Masaki*; Toko, Kaoru*; Akiyama, Ryota*; Takeda, Yukiharu; Saito, Yuji; Oguchi, Tamio*; et al.

Physical Review B, 101(10), p.104401_1 - 104401_8, 2020/03

 Times Cited Count:3 Percentile:44.66(Materials Science, Multidisciplinary)

Journal Articles

Measurement of the angular distribution of $$gamma$$-rays after neutron capture by $$^{139}$$La for a T-violation search

Okudaira, Takuya; Shimizu, Hirohiko*; Kitaguchi, Masaaki*; Hirota, Katsuya*; Haddock, C. C.*; Ito, Ikuya*; Yamamoto, Tomoki*; Endo, Shunsuke*; Ishizaki, Kohei*; Sato, Takumi*; et al.

EPJ Web of Conferences, 219, p.09001_1 - 09001_6, 2019/12

Parity violating effects enhanced by up to 10$$^6$$ times have been observed in several neutron induced compound nuclei. There is a theoretical prediction that time reversal (T) violating effects can also be enhanced in these nuclei implying that T-violation can be searched for by making very sensitive measurements. However, the enhancement factor has not yet been measured in all nuclei. The angular distribution of the (n,$$gamma$$) reaction was measured with $$^{139}$$La by using a germanium detector assembly at J-PARC, and the enhancement factor was obtained. From the result, the measurement time to achieve the most sensitive T-violation search was estimated as 1.4 days, and a 40% polarized $$^{139}$$La target and a 70% polarized $$^3$$He spin filter whose thickness is 70 atm$$cdot$$cm are needed. Therefore high quality $$^3$$He spin filter is developed in JAEA. The measurement result of the (n,$$gamma$$) reaction at J-PARC and the development status of the $$^3$$He spin filter will be presented.

Journal Articles

Research on factor analysis for achieving denuclearization, 2; South Africa: Denuclearization and verification methods

Kimura, Takashi; Tazaki, Makiko; Shimizu, Ryo; Tamai, Hiroshi; Nakatani, Takayoshi; Suda, Kazunori

Nihon Kaku Busshitsu Kanri Gakkai Dai-40-Kai Nenji Taikai Puroshidhingusushu, p.85 - 88, 2019/11

This is the summary of research result of methods for denuclearization and IAEA verification after the denuclearization in South Africa. South Africa had developed and possessed nuclear weapons, and dismantled them including the related facilities and equipment etc. by itself secretly in the past. The method for the denuclearization and the verification is unique in the world. This report could give us the lessons to investigate how to denuclearize and to verify them.

Journal Articles

Research on factor analysis for achieving denuclearisation, 3; Denuclearisation at Libya: Process and success factors

Tamai, Hiroshi; Shimizu, Ryo; Tazaki, Makiko; Kimura, Takashi; Nakatani, Takayoshi; Suda, Kazunori

Nihon Kaku Busshitsu Kanri Gakkai Dai-40-Kai Nenji Taikai Puroshidhingusushu, p.89 - 92, 2019/11

Libya's denuclearisation, named "the Libya model", is regarded as one of good practices in cooperation of the international community and measures that have a sense of speed with the countries and institutions involved. Success factors of the denuclearisation are the Libya's relatively low technological progress despite the procurement of extensive nuclear materials and components due to the delay of detecting the nuclear programme, prompt implementation with the close collaboration of countries concerned, and Libya's cooperation facing to the economic sanctions and the regime collapse by the Iraq war. Precious lessons will be learned towards the prevention and the denuclearisation in other countries.

Journal Articles

Research on factor analysis for achieving denuclearization, 4; Iraq: Characteristics of Iraq's denuclearization

Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Tamai, Hiroshi; Nakatani, Takayoshi; Suda, Kazunori

Nihon Kaku Busshitsu Kanri Gakkai Dai-40-Kai Nenji Taikai Puroshidhingusushu, p.93 - 96, 2019/11

Iraq, defeated by the Gulf War, had to accept denuclearization under UN Security Council Resolution (UNSCR) 687, but did not immediately and accurately report all its past nuclear activities to the IAEA. IAEA, as an internationally authorized nuclear inspection and verification organization to Iraqi denuclearization by the UNSCR 687, gradually revealed existence and the whole picture of Iraqi clandestine nuclear activities and verified destruction of weapon related facilities and equipment as well as removal of nuclear materials outside Iraq. Analyzing Iraq's characteristics of denuclearization could serve as a good reference for not only preventing nuclear weapons development but also considering their denuclearization in current and future states.

303 (Records 1-20 displayed on this page)