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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 Puroshidhingusu, 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 Puroshidhingusu, 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 Puroshidhingusu, 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.

Journal Articles

Research on factor analysis for achieving denuclearization, 1; South Africa: Motivations for nuclear weapons development, incentives for denuclearization and characteristics of its denuclearization

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

Nihon Kaku Busshitsu Kanri Gakkai Dai-40-Kai Nenji Taikai Puroshidhingusu, p.81 - 84, 2019/11

South Africa had developed, manufactured, and possessed nuclear weapons, but later dismantled them all together with related facilities and equipment. After joining Treaty on the Non-Proliferation of Nuclear Weapons as a non-nuclear weapon state and concluding a Comprehensive Safeguards Agreement with the Atomic Energy Agency (IAEA), it started peaceful use of nuclear energy. In that sense, South Africa's denuclearization is one of good examples of past denuclearization in the world, although the South Africa's specific policy of apartheid had been deeply connected with its nuclear weapons development and denuclearization. Analysing South Africa's motivations for nuclear weapons development, incentives for denuclearization, and characteristics of its denuclearization could serve as a good reference for not only preventing nuclear weapons development but also considering their denuclearization in current and future states.

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.

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in radioactive waste generated from the dismantling of research reactors

Murakami, Masashi; Hoshino, Yuzuru; Nakatani, Takayoshi; Sugaya, Toshikatsu; Fukumura, Nobuo*; Sanda, Toshio*; Sakai, Akihiro

JAEA-Technology 2019-003, 50 Pages, 2019/06

JAEA-Technology-2019-003.pdf:4.42MB

Toward the establishment of a common approach to determine the radioactivity concentrations in dismantling wastes arising from research reactors, radionuclide concentrations in the reactor structure materials of aluminum, carbon steel, shield concrete, and graphite of TRIGA Mark II reactor at Rikkyo University, Japan, were evaluated with both radiochemical analysis and theoretical calculation. The measured nuclides by the radiochemical analysis were $$^{3}$$H, $$^{60}$$Co, and $$^{63}$$Ni in aluminum, $$^{3}$$H, $$^{60}$$Co, $$^{63}$$Ni, and $$^{152}$$Eu in carbon steel, $$^{3}$$H, $$^{60}$$Co, and $$^{152}$$Eu in shield concrete, and $$^{3}$$H, $$^{14}$$C, $$^{60}$$Co, $$^{63}$$Ni, and $$^{152}$$Eu in graphite. Neutron-flux distributions and neutron-induced activities were computed with DORT and ORIGEN-ARP codes, respectively. Using the results of material composition analysis, radioactivity concentrations were conservatively predicted with good accuracy except for graphite material.

Journal Articles

Stroboscopic time-of-flight neutron diffraction during cyclic testing using the event data recording system at J-PARC

Kawasaki, Takuro; Inamura, Yasuhiro; Ito, Takayoshi*; Nakatani, Takeshi; Harjo, S.; Gong, W.*; Aizawa, Kazuya

Journal of Applied Crystallography, 51(3), p.630 - 634, 2018/06

 Times Cited Count:2 Percentile:53.01(Chemistry, Multidisciplinary)

JAEA Reports

Corrosion test of Fugen pressure tube (Zr-2.5wt%Nb alloy) under the sub-surface disposal environment, 2; Examination of long-term corrosion rate by 5 years keeping sample

Sugaya, Toshikatsu; Nakatani, Takayoshi; Sakai, Akihiro

JAEA-Technology 2017-032, 21 Pages, 2018/01

[The article has been found to have a problem about reliability of the corrosion data acquisition, and thus it is unavailable to download the full text in accordance with authors' intentions to retract the report.] For the purpose of the setting of the rate of nuclide elution necessary to safety assessment, we planned the gas-accumulating type corrosion test on Zr-2.5wt%Nb alloy in order to obtain long-term corrosion rate under low temperature, low oxygen and alkaline conditions assuming the disposal environment. A corrosion rate over a testing period of 5 years is acquired with the aim to grasp a long-term corrosion rate behavior in this report. This corrosion rate is compared with the same data that was previously acquired over a testing period of 2 years. As a result, it is confirmed that an evaluation method that is proportional to the minus cubic root of corrosion time squared can be applicable to the corrosion rate behavior acquired this time over a testing period of 5 years, which is the same result in evaluating the corrosion rate behavior acquired over a testing period of 2 years.

Journal Articles

Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex, 3; Neutron devices and computational and sample environments

Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.

Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09

Neutron devices such as neutron detectors, optical devices including supermirror devices and $$^{3}$$He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.

JAEA Reports

Technological study about a disposal measures of low-level radioactive waste including uranium and long-half-life radionuclides

Sugaya, Toshikatsu; Nakatani, Takayoshi; Sasaki, Toshihisa*; Nakamura, Yasuo*; Sakai, Akihiro; Sakamoto, Yoshiaki

JAEA-Technology 2016-036, 126 Pages, 2017/02

JAEA-Technology-2016-036.pdf:7.28MB

At the Radioactive Waste Management and Disposal Project Department Sector of Decommissioning and Radioactive Waste Management, we performed the technological study about the disposal measures of the low-level radioactive waste targeted for uranium-bearing waste and intermediate depth disposal-based waste occurring from the process of the nuclear fuel cycle.

JAEA Reports

Calculation of the dose equivalent rate based on the unit concentration of contaminated soil in a flexible container

Sugaya, Toshikatsu; Abe, Daichi; Takebe, Shinichi; Nakatani, Takayoshi; Sakai, Akihiro

JAEA-Technology 2016-018, 20 Pages, 2016/09

JAEA-Technology-2016-018.pdf:2.41MB

Decontamination to the pollution which occurred with an accident of a nuclear power plant with Tohoku-district Pacific offing earthquake has been performed. The contaminated soil which occurred in decontamination stores it in the flexible container back, and is the kept situation. To presume concentration of radioactivity of contents from the dose of the flexible container, the 1cm dose equivalent rate per the unit concentration of radioactivity was calculated with QAD-CGGP2R.

JAEA Reports

The User's manual of "Manyo Library" data reduction software framework at MLF, J-PARC

Inamura, Yasuhiro; Ito, Takayoshi*; Suzuki, Jiro*; Nakatani, Takeshi

JAEA-Testing 2016-001, 91 Pages, 2016/06

JAEA-Testing-2016-001.pdf:2.38MB

Manyo Library is a software framework for developing analysis software of neutron scattering data produced at MLF, J-PARC. This software framework is required to work on many instruments in MLF and to include base functions applied to various scientific purposes at beam lines. This framework mainly consists of data containers, which enable to store 1, 2 and 3 dimensional axes data for neutron scattering. Data containers have many functions to calculate four arithmetic operations with errors distribution between containers, to store the meta-data about measurements and to read or write text file. Since Manyo Library is built in C++ language, we' ve introduced the technology to call C++ function from Python environment into the framework. As results, we have already developed a lot of software for data reduction, analysis and visualization, which are utilized widely in beam lines at MLF. This document is the manual for the beginner to touch this framework.

Journal Articles

Estimation of corrosion rate of Zr-2.5wt%Nb alloy (Fugen pressure tube) under low-temperature, low-oxygen, and high-pH conditions

Sakatani, Keiichi; Nakatani, Takayoshi; Funabashi, Hideyuki

Nippon Genshiryoku Gakkai Wabun Rombunshi, 14(4), p.261 - 267, 2015/12

The safety assessment of the sub-surface disposal system should ensure that calculated dose rate will be lower than the dose rate assigned to the scenario in question over the whole evaluation period. For activated metal wastes which are the reactor structural materials classified as one of the subject wastes, the rate of nuclide elution under the disposal environment is an important parameter in safety assessment. Some reports have shown that nuclides in a metal matrix are released with corrosion congruently. However, the corrosion rate under low temperature, low oxygen and high pH conditions assuming the disposal environment is not reported about Zr-2.5wt%Nb alloy, which is used in the pressure tube of Fugen (ATR). The gas-accumulating type corrosion test on Zr-2.5wt%Nb alloy was conducted in order to obtain corrosion rate. The corrosion rate after 1 month, 3 months, 6 months, 12 months and 24 months was obtained during the test period.

JAEA Reports

Sensitivity of radioactive nuclide leaching rate under the sub-surface disposal

Tsuji, Tomoyuki; Nakamura, Yasuo; Nakatani, Takayoshi

JAEA-Technology 2015-014, 34 Pages, 2015/06

[The article has been found to have a problem about reliability of the corrosion data acquisition, and thus it is unavailable to download the full text in accordance with authors' intentions to retract the report.] In order to dispose of radioactive wastes for sub-surface disposal, JAEA has studied the safety assessment for likely scenario and less-likely scenario. Radioactive nuclide leaching rate under the sub-surface disposal is important parameter in the safety assessment because radioactive nuclides in activated metal wastes are released with its corrosion. In this report, sensitivity of radioactive nuclide leaching rate is studied for the safety assessment. As the result, it is confirmed that Cl-36 which is dominant for the safety assessment in groundwater scenario is sensitive to radioactive nuclide leaching rate, but Nb-94 which is dominant in tunnel excavation scenario is not sensitive to radioactive nuclide leaching rate but to distribution coefficients in engineered barrier.

JAEA Reports

Environmental impact of nitrate nitrogen in sub-surface disposal system on surface water and sensitivity analysis of distribution coefficient of nitrate ion and porosity of waste layer on the environmental safety assessments

Nakamura, Yasuo; Nakatani, Takayoshi

JAEA-Technology 2014-048, 18 Pages, 2015/03

JAEA-Technology-2014-048.pdf:7.75MB

Sodium nitrate is included bituminized waste generating from the reprocessing plant of spent fuel which is disposed of in sub-surface disposal facility. Because the sodium nitrate is soluble material in surface water, it is a concern impact on surface water. Such as non-radioactive materials are not strictly regulated by "the Law for the Regulations of Nuclear Source Material, Nuclear Fuel Material and Reactors", but should be considered by related laws and regulations according to former basic policy. Because it is regulated as nitrate nitrogen by "The Basic Environment Law", the valuation of the environmental impact on general sub-surface disposal system was carried out. As the results, the concentration of nitrate nitrogen in river water whose annual quantity of water is rather than 1$$times$$10$$^{5}$$m$$^{3}$$/y is below the regulated value at the small scale surface waters as evaluation point.

JAEA Reports

Development of the assessment tool for has migration scenario concerning sub-surface disposal

Sakatani, Keiichi; Nakamura, Yasuo; Tsuji, Tomoyuki; Nakatani, Takayoshi

JAEA-Data/Code 2014-020, 38 Pages, 2014/11

JAEA-Data-Code-2014-020.pdf:30.04MB

The safety assessment for sub-surface disposal of radioactive wastes should ensure that calculated dose will be lower than the dose assigned to the scenario in question over the whole evaluation period of hundreds of thousands years. We have developed several assessment tools for the safe disposal of radioactive wastes on the GoldSim platform, and calculated doses since JFY 2008. These assessment tools have been improved reflecting the last view of assessment. In addition, we have developed an assessment tool for the gas migration scenario. This report describes concept of assessment model and structure of tool for the gas migration scenario.

JAEA Reports

Development of the assessment tools for land use scenarios concerning sub-surface disposal

Sakatani, Keiichi; Sugaya, Toshikatsu; Nakatani, Takayoshi; Funabashi, Hideyuki

JAEA-Data/Code 2014-008, 53 Pages, 2014/06

JAEA-Data-Code-2014-008.pdf:39.9MB

The safety assessment of the sub-surface disposal system should ensure that calculated dose will be lower than the dose assigned to the scenario in question during the period from now to future. In order to realize the safety disposal, we have developed several assessment tools on the GoldSim platform and calculated doses since 2008, and these assessment tools have been improved reflecting the last view of assessment. This report describes idea of assessment models and structure of assessment tools for land use scenarios.

JAEA Reports

Development of the assessment tool for groundwater scenario concerning sub-surface disposal

Sakatani, Keiichi; Sugaya, Toshikatsu; Nakatani, Takayoshi; Funabashi, Hideyuki

JAEA-Data/Code 2013-015, 63 Pages, 2013/11

JAEA-Data-Code-2013-015.pdf:8.75MB

The safety assessment of the sub-surface disposal system should ensure that calculated dose will be lower than the dose assigned to the scenario in question during the period from now to future. In order to realize the safety disposal, we have developed several assessment tools on the GoldSim platform and calculated doses since 2008, and these assessment tools have been improved reflecting the last view of assessment. This report describes safety functions of the disposal system, idea of nuclide migration, formulas for nuclides migration, formulas of exposure dose and structure of assessment tool for groundwater scenario.

JAEA Reports

Corrosion test of Fugen pressure tube (Zr-2.5wt%Nb alloy) under the sub-surface disposal environment; Examination of processable method for specimen and confirmation of optimal test conditions

Sakatani, Keiichi; Nakatani, Takayoshi; Funabashi, Hideyuki

JAEA-Technology 2012-034, 20 Pages, 2012/12

JAEA-Technology-2012-034.pdf:10.22MB

We planned the gas-accumulating type corrosion test on Zr-2.5wt%Nb alloy which is used in the pressure tube of Fugen (ATR) in order to obtain long-term corrosion rate data under the low oxygen and alkaline conditions assuming the disposal environment. Before starting the test, we examined the specimen machining method and confirmed the corrosion test conditions.

Journal Articles

Current status of a new polarized neutron reflectometer at the intense pulsed neutron source of the Materials and Life Science Experimental Facility (MLF) of J-PARC

Takeda, Masayasu; Yamazaki, Dai; Soyama, Kazuhiko; Maruyama, Ryuji; Hayashida, Hirotoshi; Asaoka, Hidehito; Yamazaki, Tatsuya; Kubota, Masato; Aizawa, Kazuya; Arai, Masatoshi; et al.

Chinese Journal of Physics, 50(2), p.161 - 170, 2012/04

102 (Records 1-20 displayed on this page)