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Journal Articles

Nuclear fuel cycle, nuclear non-proliferation and nuclear security in Japan, 3; Challenges on technologies for nuclear non-proliferation/nuclear security and progressing credibility

Mochiji, Toshiro; Senzaki, Masao*; Tamai, Hiroshi; Iwamoto, Tomonori*; Ishiguro, Yuzuru*; Kitade, Yuta; Sato, Heigo*; Suehiro, Rie*; Taniguchi, Tomihiro*; Fukasawa, Tetsuo*; et al.

Enerugi Rebyu, 40(8), p.56 - 57, 2020/07

Strict application of IAEA safeguards and nuclear security should be implemented for Japan's full-scale nuclear fuel cycle. Based on the knowledge and experience of research and development in the nuclear fuel cycle, nuclear material management, the effective and efficient promotion of new technologies should be promoted with scientific and demonstrative measures to strengthen the world's nuclear non-proliferation and nuclear security. Development or sophistication of new technologies, human resource development, and reinforcement of the international framework are future challenge in the international community.

Journal Articles

Nuclear fuel cycle, nuclear non-proliferation and nuclear security in Japan, 2; Significance of sustainable progress in plutonium-thermal policy and R&D of fast reactor

Mochiji, Toshiro; Senzaki, Masao*; Tamai, Hiroshi; Iwamoto, Tomonori*; Ishiguro, Yuzuru*; Kitade, Yuta; Sato, Heigo*; Suehiro, Rie*; Taniguchi, Tomihiro*; Fukasawa, Tetsuo*; et al.

Enerugi Rebyu, 40(7), p.58 - 59, 2020/06

Japan have promoted the peaceful use of plutonium with the nuclear non-proliferation commitment based on IAEA safeguards agreement and Japan-US nuclear cooperation agreement, as well as ensuring transparency of the policy that Japan has no plutonium without purpose of use. In promoting the nuclear fuel cycle, adherence to those measures and maintaining plutonium utilization by means of plutonium-thermal, and a fast reactor cycle to achieve large-scale and long-term energy supply and environmental improvement, therefore, further research and development is essential.

Journal Articles

Chapter 2, Peaceful use of nuclear energy and international relations, 2.3 Multi-national approach of nuclear material management / Chapter 5, Peaceful use of Plutonium and Nuclear Non-Proliferation, 5.1 Japan's policy on plutonium usage

Tamai, Hiroshi

Genshiryoku Heiwa Riyo To Kakufukakusan, Kakusekyuriti; NSA/Commentaries, No.25, p.62 - 68, 2020/06

On the viewpoint of strengthening nuclear non-proliferation and nuclear security, historical background and future issues in multi-national approach of nuclear material management are described.

Journal Articles

Chapter 8, Human resource development in nuclear non-proliferation and nuclear security; Education at the University of Tokyo

Tamai, Hiroshi; Demachi, Kazuyuki*

Genshiryoku Heiwa Riyo To Kakufukakusan, Kakusekyuriti; NSA/Commentaries, No.25, p.199 - 202, 2020/06

Education on nuclear non-proliferation and nuclear security in the University of Tokyo is provided at the Department of Nuclear Engineering and Management for master's course graduate students and at the Nuclear Professional School for career experts. In this paper, both the courses are introduced and their education contents on nuclear non-proliferation and nuclear security are briefly described.

Journal Articles

Chapter 7, Research and development and international cooperation on nuclear non-proliferation and nuclear security

Tomikawa, Hirofumi; Koizumi, Mitsuo; Tamai, Hiroshi

Genshiryoku Heiwa Riyo To Kakufukakusan, Kakusekyuriti; NSA/Commentaries, No.25, p.167 - 174, 2020/06

Japan's efforts for research and development on nuclear material detection and nuclear forensics and international cooperation are introduced focusing on the various aspects implemented in JAEA.

Journal Articles

Nuclear fuel cycle, nuclear non-proliferation and nuclear security in Japan, 1; Peaceful nuclear use and nuclear non-proliferation

Mochiji, Toshiro; Senzaki, Masao*; Tamai, Hiroshi; Iwamoto, Tomonori*; Ishiguro, Yuzuru*; Kitade, Yuta; Sato, Heigo*; Suehiro, Rie*; Taniguchi, Tomihiro*; Fukasawa, Tetsuo*; et al.

Enerugi Rebyu, 40(6), p.58 - 59, 2020/05

In order to promote the peaceful use of nuclear energy, it is important not only to ensure safety but also to ensure nuclear non-proliferation and nuclear security. Japan has contributed to the international community through strengthening nuclear non-proliferation and nuclear security capabilities with technical and human resource development. However, in the wake of the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, Japan's nuclear power plants have not restarted or plutonium use has not progressed smoothly. Concerns have been shown. Towards appropriate steps of Japan's nuclear fuel cycle policy, such concerns are examined and future efforts are summarized.

Journal Articles

Crystallization processes of quartz in a granitic magma; Cathodoluminescence zonation pattern controlled by temperature and titanium diffusivity

Yuguchi, Takashi*; Ogita, Yasuhiro; Kato, Takenori*; Yokota, Rintaro*; Sasao, Eiji; Nishiyama, Tadao*

Journal of Asian Earth Sciences, 192, p.104289_1 - 104289_16, 2020/05

 Times Cited Count:0 Percentile:100(Geosciences, Multidisciplinary)

Quartz from a granitic pluton is found to have formed through sequential growth events under different mechanisms and crystallization temperatures, which can provide new insights into magmatic processes of granitic magmas that were eventually consolidified into plutons. The events were identified using (1) the description of crystal shape and occurrence, (2) the study of the internal structure with cathodoluminescence (CL), and (3) derivation of the crystallization temperatures based on TitaniQ thermometry. The magmatic quartz crystals from the Toki granite, central Japan, are characterized as having the following internal structures: oscillatory zonation, no-oscillatory zonation with luminescence graduation (gradational zonation), and heterogeneous CL. The quartz crystals with oscillatory zonation were formed in the temperature range of about 800 $$^{circ}$$C to below 700 $$^{circ}$$C, which is referred to as oscillatory zoning temperature (OZT) conditions. The CL zonation pattern was controlled by the temperature conditions and titanium diffusivity in the melt (magma). The crystallization process of quartz within the Toki granite reveals the cooling processes of the granitic pluton; the lithofacies with a high frequency of oscillatory-zoned quartz underwent slower cooling under the OZT conditions than those in other lithofacies.

Journal Articles

Dynamics of atomic hydrogen in palladium probed by neutron spectroscopy

Kofu, Maiko; Yamamuro, Osamu*

Journal of the Physical Society of Japan, 89(5), p.051002_1 - 051002_12, 2020/05

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

The behavior of hydrogen in metals has attracted much attention in fundamental and applied research areas for many decades. Among metals, palladium is remarkable in that it can absorb large quantities of hydrogen, and hydrogen atoms are highly mobile in the fcc Pd lattice. The dynamics of hydrogen in Pd have been investigated by means of neutron spectroscopy which is the best tool to provide insights into microscopic dynamics of hydrogen atoms. In this article, we review recent and historical neutron scattering works to facilitate the latest understanding of the hydrogen dynamics in bulk and nanometer-sized Pd hydrides.

Journal Articles

Development of active neutron NDA system

Toh, Yosuke

JAEA-Conf 2019-001, p.47 - 52, 2019/11

no abstracts in English

Journal Articles

Research on factor analysis for achieving denuclearization, 5; Iran's nuclear program and Iran nuclear deal

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

Nihon Kaku Busshitsu Kanri Gakkai Dai-40-Kai Nenji Taikai Puroshidhingusu, p.97 - 99, 2019/11

Despite international accusations, Iran pursued uranium enrichment capacity. But through unprecedented strong economic sanctions, Iran accepted the restrictions on uranium enrichment capacity and agreed to accept the additional protocol. Nuclear program of Iran and nuclear deal are good precedents for denuclearization that has solved peacefully through multilateral negotiations, its process and lessons are compiled.

Journal Articles

Performance evaluation of differential die-away system in an integrated active neutron NDA system for nuclear non-proliferation and nuclear security

Ozu, Akira; Maeda, Makoto; Komeda, Masao; Toh, Yosuke

Proceedings of 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (IEEE NSS/MIC 2018) (Internet), 4 Pages, 2019/10

Journal Articles

Influence of applied load on oxidation in the vicinity of crack tips of stainless steel under high temperature water

Kasahara, Shigeki; Chimi, Yasuhiro; Hata, Kuniki; Hanawa, Satoshi

Zairyo To Kankyo, 68(9), p.240 - 247, 2019/09

In order to study environment assisted cracking mechanism of stainless steel under BWR primary coolant condition, effects of applied load on oxidation in the vicinity of crack tips of CT specimens were evaluated. Loaded CT specimens were immersed in an aqueous condition at 290$$^{circ}$$C as a simulated BWR coolant condition, and microstructural observation on oxide near the tips of pre-cracks was carried out. Oxide inner layers, which consisted of fine grain magnetite containing Fe and Cr were formed, and oxide outer layers consisting of large grains of Fe$$_{3}$$O$$_{4}$$ were observed to cover the inner layers. FEM analysis of stress and strain in the loaded CT specimen suggests that both of dislocations due to localized plastic deformation and elastic strain could play important roles to accelerate inner oxide formation in the vicinity of the crack tip of the specimens.

Journal Articles

Development of active neutron NDA system for radioactive nuclear materials

Toh, Yosuke; Ozu, Akira; Tsuchiya, Harufumi; Furutaka, Kazuyoshi; Kitatani, Fumito; Komeda, Masao; Maeda, Makoto; Koizumi, Mitsuo

Proceedings of INMM 60th Annual Meeting (Internet), 7 Pages, 2019/07

Journal Articles

Apparent diffusion coefficients of Cs and I in hardened cement paste using mineral admixtures

Mihara, Morihiro; Harasawa, Shuichi*; Torii, Kazuyuki*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.15 - 23, 2019/06

Hardened cement pastes (HCPs) of water/cement ratio (W/C) 50% and 30% using fly ash (FA), blast furnace slag (BFS) and silica fume (SF) for 28 days were prepared. Apparent diffusion coefficients (D$$_{a}$$) of Cs and I in HCPs were obtained using electron probe microanalysis. For Cs, BFS and SF contributed to a reduction of D$$_{a}$$ for W/C=50% and 30%, respectively. For I, BFS reduced D$$_{a}$$ for W/C=50%, however a significant reduction in D$$_{a}$$ for W/C=30% was not observed. Using SF enhanced sorption of Cs on HCP, and using BFS slightly improved sorption of Cs on HCP. It was also confirmed that the pore structures of HCP using SF and BFS were connected by fine pores. It was therefore considered that using SF and BFS contributes to the reduction of D$$_{a}$$ in HCP.

Journal Articles

Effect of nickel concentration on radiation-induced diffusion of point defects in high-nickel Fe-Cr-Ni model alloys during neutron and electron irradiation

Sekio, Yoshihiro; Sakaguchi, Norihito*

Materials Transactions, 60(5), p.678 - 687, 2019/05

The quantitative evaluation of vacancy migration energies in high nickel model alloy was conducted by analyzing the void denuded zone (VDZ) width formed near grain boundaries under neutron and electron irradiation. The microstructures of Fe-15Cr-xNi (x=15, 20, 25, 30 mass%) alloys that were neutron irradiated at 749 K and electron irradiated at 576 K-824 K were examined. The VDZ widths increased with increasing Ni content in both irradiation experiments, which implies an increase of the vacancy mobility. The vacancy migration energies were estimated from the temperature dependence of the VDZ widths, and the energies were 1.09, 0.97, 0.90, and 0.77 eV for the alloys containing 15, 20, 25, and 30 mass% Ni, respectively. From the obtained energies, the effective vacancy diffusivity and excess vacancy concentration were estimated using the analytical equation of the VDZ width, which quantitatively confirmed the increase of the vacancy mobility with increasing Ni content.

Journal Articles

Fukushima $$^{137}$$Cs releases dispersion modelling over the Pacific Ocean; Comparisons of models with water, sediment and biota data

Peri$'a$$~n$ez, R.*; Bezhenar, R.*; Brovchenko, I.*; Jung, K. T.*; Kamidaira, Yuki; Kim, K. O.*; Kobayashi, Takuya; Liptak, L.*; Maderich, V.*; Min, B. I.*; et al.

Journal of Environmental Radioactivity, 198, p.50 - 63, 2019/03

 Times Cited Count:2 Percentile:48.94(Environmental Sciences)

A number of marine radionuclide dispersion models were applied to simulate $$^{137}$$Cs releases from Fukushima Daiichi Nuclear Power Plant accident in 2011 over the northwest Pacific. Simulations extended over two years and both direct releases into the ocean and deposition of atmospheric releases on the ocean surface were considered. Dispersion models included an embedded biological uptake model (BUM). Three types of BUMs were used: equilibrium, dynamic and allometric. Model results were compared with $$^{137}$$Cs measurements in water, sediment and biota. A reasonable agreement in model/model and model/data comparisons was obtained.

Journal Articles

Summary of questions and answers part of the 2018 Japan Society of International Law (JSIL) Annual Conference's Session 1; The 50th Anniversary of the Adoption of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and Nuclear Disarmament

Nakanishi, Hiroaki; Nakasone, Suguru*

Kokusaiho Gaiko Zasshi, 117(3), p.642 - 643, 2018/11

Summary of questions and answers part of the 2018 Japan Society of International Law (JSIL) Annual Conference's Session 1: The 50th Anniversary of the Adoption of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and Nuclear Disarmament

Journal Articles

Study on current US views on bilateral civilian nuclear cooperation agreements

Tazaki, Makiko; Tamai, Hiroshi; Shimizu, Ryo; Kimura, Takashi; Kitade, Yuta; Nakanishi, Hiroaki; Suda, Kazunori

Nihon Kaku Busshitsu Kanri Gakkai Dai-39-Kai Nenji Taikai Rombunshu (Internet), 7 Pages, 2018/11

no abstracts in English

Journal Articles

Development of differential die-away technique in an integrated active neutron NDA system for nuclear non-proliferation and nuclear security

Ozu, Akira; Maeda, Makoto; Komeda, Masao; Toh, Yosuke; Koizumi, Mitsuo; Seya, Michio

Proceedings of 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) (Internet), 4 Pages, 2018/11

JAEA Reports

Activities on predictions of atmospheric dispersion of radionuclides for nuclear tests by North Korea

Ishizaki, Shuhei; Hayakawa, Tsuyoshi; Tsuzuki, Katsunori; Terada, Hiroaki; Togawa, Orihiko

JAEA-Technology 2018-007, 43 Pages, 2018/10

JAEA-Technology-2018-007.pdf:5.67MB

When North Korea has carried out a nuclear test, by a request from Nuclear Regulation Authority (NRA), Nuclear Emergency Assistance and Training Center (NEAT) predicts atmospheric dispersion of radionuclides by WSPEEDI-II system in cooperation with Nuclear Science and Engineering Center (NSEC), and submits the predicted results to NRA as the activity to assist responses by the Japanese Government. This report explains frameworks of the Japanese Government and Japan Atomic Energy Agency (JAEA) to cope with nuclear tests by North Korea, and describes a series of activities by NEAT regarding predictions of atmospheric dispersion of radionuclides in response to the 5th and 6th nuclear tests carried out by North Korea in September 2016 and September 2017. Future plans and issues to be solved for responses to nuclear tests are also described in this report, together with an outline of a computer program system used in the predictions.

844 (Records 1-20 displayed on this page)