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Journal Articles

Structural characterization by X-ray analytical techniques of calcium aluminate cement modified with sodium polyphosphate containing cesium chloride

Takahatake, Yoko; Watanabe, So; Irisawa, Keita; Shiwaku, Hideaki; Watanabe, Masayuki

Journal of Nuclear Materials, 556, p.153170_1 - 153170_7, 2021/12

Journal Articles

Modelling concrete degradation by coupled non-linear processes

Oda, Chie; Kawama, Daisuke*; Shimizu, Hiroyuki*; Benbow, S. J.*; Hirano, Fumio; Takayama, Yusuke; Takase, Hiroyasu*; Mihara, Morihiro; Honda, Akira

Journal of Advanced Concrete Technology, 19(10), p.1075 - 1087, 2021/10

Concrete in a transuranic (TRU) waste repository is considered a suitable material to ensure safety, provide structural integrity and retard radionuclide migration after the waste containers fail. In the current study, coupling between chemical, mass-transport and mechanical, so-called non-linear processes that control concrete degradation and crack development were investigated by coupled numerical models. Application of such coupled numerical models allows identification of the dominant non-linear processes that will control long-term concrete degradation and crack development in a TRU waste repository.

JAEA Reports

Analysis of behavior of Ru with nitrogen oxide chemical behavior in accident of evaporation to dryness by boiling of reprocessed high level liquid waste

Yoshida, Kazuo; Tamaki, Hitoshi; Hiyama, Mina*

JAEA-Research 2021-005, 25 Pages, 2021/08

JAEA-Research-2021-005.pdf:2.91MB

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into atmosphere. Accurate quantitative estimation of released Ru is one of the important issues for risk assessment of those facilities. To resolve this issue, an empirical correlation equation of Ru mass transfer coefficient across the vapor-liquid surface, which can be useful for quantitative simulation of Ru mitigating behavior, has been obtained from data analyses of small-scale experiments conducted to clarify gaseous Ru migrating behavior under steam-condensing condition. A simulation study has been also carried out with a hypothetical typical facility building successfully to demonstrate the feasibility of quantitative estimation of amount of Ru migrating in the facility using the obtained correlation equation implemented in SCHERN computer code which simulates chemical behaviors of nitrogen oxide based on the condition also simulated thermal-hydraulic computer code.

JAEA Reports

SCHERN-V2: Technical guide of computer program for chemical behavior in accident of evaporation to dryness by boiling of reprocessed high level liquid waste in Fuel Reprocessing Facilities

Yoshida, Kazuo; Tamaki, Hitoshi; Hiyama, Mina*

JAEA-Data/Code 2021-008, 35 Pages, 2021/08

JAEA-Data-Code-2021-008.pdf:3.68MB

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into atmosphere. In addition to this, nitrogen oxides (NO$$_{rm x}$$) are also released formed by the thermal decomposition of metal nitrates of fission products (FP) in HLLW. It has been observed experimentally that NOx affects to the migration behavior of Ru at the anticipated atmosphere condition in cells and/or compartments of the facility building. Chemical reactions of NO$$_{rm x}$$ with water and nitric acid are also recognized as the complex phenomena to undergo simultaneously in the vapor and liquid phases. The analysis program, SCHERN has been under developed to simulate chemical behavior including Ru coupled with the thermo-hydraulic condition in the flow paths in the facility building. This technical guide for SCHERN-V2 presents the overview of covered accident, analytical models including newly developed models, differential equations for numerical solution, and user instructions.

Journal Articles

Nuclear data processing code FRENDY; A Verification with HTTR criticality benchmark experiments

Fujimoto, Nozomu*; Tada, Kenichi; Ho, H. Q.; Hamamoto, Shimpei; Nagasumi, Satoru; Ishitsuka, Etsuo

Annals of Nuclear Energy, 158, p.108270_1 - 108270_8, 2021/08

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Fabrication, permeation, and corrosion stability measurements of silica membranes for HI decomposition in the thermochemical iodine-sulfur process

Myagmarjav, O.; Shibata, Ai*; Tanaka, Nobuyuki; Noguchi, Hiroki; Kubo, Shinji; Nomura, Mikihiro*; Takegami, Hiroaki

International Journal of Hydrogen Energy, 46(56), p.28435 - 28449, 2021/08

 Times Cited Count:0 Percentile:0.01(Chemistry, Physical)

JAEA Reports

Preparation of carbonate slurry simulating chemical composition of slurry in overflowed high integrity container and evaluation of its characteristics

Horita, Takuma; Yamagishi, Isao; Nagaishi, Ryuji; Kashiwaya, Ryunosuke*

JAEA-Technology 2021-012, 34 Pages, 2021/07

JAEA-Technology-2021-012.pdf:2.1MB
JAEA-Technology-2021-012(errata).pdf:0.15MB

Waste mainly consisting of carbonate precipitates (carbonate slurry) from the Advanced Liquid Processing System (ALPS) and the improved ALPS at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Holdings, Inc. have been storing in the High Integrity Container (HIC). The supernatant solution of carbonate slurry contained in some of HICs were overflowed in April of 2015. The all of level of liquid in the HICs were investigated; however, almost of the HICs were under the level of overflow. The mechanism of overflow suggested to be depending on the difference of the properties of the carbonate slurry such as the retention/release characteristics of the bubbles. Therefore, in order to clarify the mechanism of leakage, the repeatability experiment was carried out by using simulated carbonate slurry. The simulated carbonate slurry was perpetrated by using the same cross-flow filter system of the actual ALPS. Moreover, the preparative conditions for the simulated carbonate slurry were the same as Mg/Ca concentration ratio in inlet water of the ALPS (raw water) and the ALPS operating conditions. The chemical characteristics of simulated carbonate slurries were revealed by ICP-AES, pH meter, etc. The density of the settled slurry layer tended to increase depending on the calcium concentration in the raw water. The bubble injection test was conducted in order to investigate the bubble retention/release behavior in the simulated carbonate slurry layer. The simulated carbonate slurry with high settling density, which was generated by high calcium concentration solution was revealed to retain the injected bubbles. Since the ratio of concentration calcium and magnesium during the carbonate slurry generation is assumed to affect the retention of bubbles in the slurry layer, the information on the composition of raw water is one of important factor for overflow of HICs.

Journal Articles

Thermal-hydraulics to risk assessment; Roles of thermal-hydraulics simulation to risk assessment

Maruyama, Yu; Yoshida, Kazuo

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 63(7), p.517 - 522, 2021/07

no abstracts in English

Journal Articles

Hydrogen production using thermochemical water-splitting iodine-sulfur process test facility made of industrial structural materials; Engineering solutions to prevent iodine precipitation

Noguchi, Hiroki; Kamiji, Yu; Tanaka, Nobuyuki; Takegami, Hiroaki; Iwatsuki, Jin; Kasahara, Seiji; Myagmarjav, O.; Imai, Yoshiyuki; Kubo, Shinji

International Journal of Hydrogen Energy, 46(43), p.22328 - 22343, 2021/06

An iodine-sulfur process offers the potential for mass producing hydrogen with high-efficiency, and it uses high-temperature heat sources, including HTGR, solar heat, and waste heat of industries. R&D tasks are essential to confirm the integrity of the components that are made of industrial materials and the stability of hydrogen production in harsh working conditions. A test facility for producing hydrogen was constructed from corrosion-resistant components made of industrial materials. For stable hydrogen production, technical issues for instrumental improvements (i.e., stable pumping of the HIx solution, improving the quality control of glass-lined steel, prevention of I$$_{2}$$ precipitation using a water removal technique in a Bunsen reactor) were solved. The entire process was successfully operated for 150 h at the rate of 30 L/h. The integrity of components and the operational stability of the hydrogen production facility in harsh working conditions were demonstrated.

Journal Articles

$$^{60}$$Fe and $$^{244}$$Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

Wallner, A.*; Froehlich, M. B.*; Hotchkis, M. A. C.*; Kinoshita, N.*; Paul, M.*; Martschini, M.*; Pavetich, S.*; Tims, S. G.*; Kivel, N.*; Schumann, D.*; et al.

Science, 372(6543), p.742 - 745, 2021/05

 Times Cited Count:1 Percentile:63.46(Multidisciplinary Sciences)

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust-iron-60 ($$^{60}$$Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and $$^{244}$$Pu (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of $$^{60}$$Fe to Earth in the last 10 million years and accompanying lower quantities of $$^{244}$$Pu. The $$^{244}$$Pu/$$^{60}$$Fe influx ratios are similar for both events. The $$^{244}$$Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

Journal Articles

Iodine-129 in the Tokai Reprocessing Plant and the environment

Nakano, Masanao

Hoken Butsuri (Internet), 56(1), p.17 - 25, 2021/03

The Tokai Reprocessing Plant is the first reprocessing plant in Japan which started hot test in 1977, and had reprocessed 1140 tons of spent nuclear fuel by May 2007. The gaseous and liquid radioactive wastes has been discharged to the environment. Since iodine-129 ($$^{129}$$I) is one of the most important nuclides for environmental impact assessment. Therefore, $$^{129}$$I in the exhaust and effluent has been controlled, and a precise analysis method of $$^{129}$$I in the environmental samples was developed, and the concentration of 129I in the environment was investigated. This report presents an overview of these activities. Not limited to $$^{129}$$I on reprocessing facilities, it is essential for nuclear operators to reduce the amount released to the environment in the spirit of ALARA, and to continuously develop the further upgrading environmental monitoring methods and evaluation methods in order to foster a sense of safety and security among residents living in the vicinity of the facilities.

Journal Articles

Restraint effect of coexisting nitrite ion in simulated high level liquid waste on releasing volatile ruthenium under boiling condition

Yoshida, Ryoichiro; Amano, Yuki; Yoshida, Naoki; Abe, Hitoshi

Journal of Nuclear Science and Technology, 58(2), p.145 - 150, 2021/02

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In the "evaporation and dryness due to the loss of cooling functions" which is one of the severe accidents at reprocessing plants in Japan, ruthenium (Ru) is possible to be released much more than other elements to the environment. This cause is considered that the volatile Ru compound can be released from high level liquid waste (HLLW) as gaseous compound in adding to the release by entrainment. It was expected that the release of the volatile Ru compound from the HLLW may be able to be restrained by coexisting nitrite ion because of its reduction power. To confirm the effect of nitrite ion on the release behavior of the volatile Ru compound, four experiments of heating the simulated HLLW (SHLLW) with setting the concentration of nitrite ion in the SHLLW as a parameter ware carried out. As a result, the release of the volatile Ru compound was seemed to be restrained by adding nitrite sodium as a source of nitrite ion under certain boiling condition. This result may contribute to improve source term analysis in the evaporation and dryness due to the loss of cooling functions.

JAEA Reports

Analysis of microparticles generated by laser processing and development of a methodology for their nuclear identification (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2020-031, 69 Pages, 2021/01

JAEA-Review-2020-031.pdf:4.22MB

JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2018, this report summarizes the research results of the "Analysis of microparticles generated by laser processing and development of a methodology for their nuclear identification" conducted in FY2019.

Journal Articles

Radiation-induced effects on the extraction properties of hexa-$$n$$-octylnitrilo-triacetamide (HONTA) complexes of americium and europium

Toigawa, Tomohiro; Peterman, D. R.*; Meeker, D. S.*; Grimes, T. S.*; Zalupski, P. R.*; Mezyk, S. P.*; Cook, A. R.*; Yamashita, Shinichi*; Kumagai, Yuta; Matsumura, Tatsuro; et al.

Physical Chemistry Chemical Physics, 23(2), p.1343 - 1351, 2021/01

 Times Cited Count:1 Percentile:70.6(Chemistry, Physical)

The candidate An(III)/Ln(III) separation ligand hexa-$$n$$-octylnitrilo-triacetamide (HONTA) was irradiated under envisioned SELECT (Solvent Extraction from Liquid waste using Extractants of CHON-type for Transmutation) process conditions using a solvent test loop in conjunction with cobalt-60 gamma irradiation. We demonstrate that HONTA undergoes exponential decay with increasing gamma dose to produce a range of degradation products which have been identified and quantified by HPLC-ESI-MS/MS techniques. The combination of HONTA destruction and degradation product ingrowth, particularly dioctylamine, negatively impacts the extraction and back-extraction of both americium and europium ions. The loss of HONTA was attributed to its reaction with the solvent (${it n}$-dodecane) radical cation of ${it k}$(HONTA + R$$^{.+}$$) = (7.61 $$pm$$ 0.82) $$times$$ 10$$^{9}$$ M$$^{-1}$$ s$$^{-1}$$ obtained by pulse radiolysis techniques. However, when this ligand is bound to either americium or europium ions, the observed ${it n}$-dodecane radical cation kinetics increase by over an order of magnitude. This large reactivity increase to additional reaction pathways occurring upon metal-ion binding. Lastly nanosecond time-resolved measurements showed that both direct and indirect HONTA radiolysis yielded the short-lived ($$<$$100 ns) HONTA radical cation as well as a longer-lived ($$mu$$s) HONTA triplet excited state. These HONTA species are important precursors to the suite of HONTA degradation products observed.

JAEA Reports

Analysis of debris samples of Tokyo Electric Power Company Holdings Fukushima Daiichi Nuclear Power Station (Translated document)

Task Force on Research Strategy for Debris of Fukushima Daiichi Nuclear Power Station

JAEA-Review 2020-055, 171 Pages, 2020/12

JAEA-Review-2020-055.pdf:5.66MB

Design, planning and control of debris-related processes, namely retrieval, storage management, processing and disposal of the debris, are required for the safe and steady decommissioning of Fukushima Daiichi Nuclear Power Station (1F). Status inside primary containment vessel of 1F must be known by the PCV investigation and fuel debris sample analysis. Continuous updating and improvement of the process design are important through ascertainment of the cause of the accident. The roadmap for the 1F decommissioning have shown the milestone of commencement of trial retrieval of fuels debris within 2021, which indicates the analysis of fuel debris sample begin in earnest. This report recommends required debris analysis in relation with issues for the retrieval, storage management, processing and disposal, and ascertainment of the cause of the 1F accident. Practical analysis plan is expected to be prepared based on this report.

Journal Articles

Study on the mechanism of radiolytic degradation of an extractant for minor actinides separation

Toigawa, Tomohiro; Murayama, Rin*; Kumagai, Yuta; Yamashita, Shinichi*; Suzuki, Hideya; Ban, Yasutoshi; Matsumura, Tatsuro

UTNL-R-0501, p.24 - 25, 2020/12

This report summarizes the results obtained in FY2019 at Electron Linac Facility of University of Tokyo. The radiolysis process of a diglycolamide extractant, which is expected to be used in the separation process of minor actinides (MA), in dodecane and octanol solutions was investigated by pulse radiolysis. As a result, it was suggested that by adding alcohol, the decomposition process of the diglycolamide extractant was different from the decomposition processes in the single solvent of dodecane considered that the decomposition occurred via a radical cation species of the extractant.

Journal Articles

Frontline of R&D for decommissioning and waste disposal, 1; R&D for processing and disposal of low-level radioactive waste and closure of uranium mine

Tsuji, Tomoyuki; Sugitsue, Noritake; Sato, Fuminori; Matsushima, Ryotatsu; Kataoka, Shoji; Okada, Shota; Sasaki, Toshiki; Inoue, Junya

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 62(11), p.658 - 663, 2020/11

no abstracts in English

Journal Articles

Phase-field model for crystallization in alkali disilicate glasses; Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$

Kawaguchi, Munemichi; Uno, Masayoshi*

Journal of the Ceramic Society of Japan, 128(10), p.832 - 838, 2020/10

 Times Cited Count:0 Percentile:0.01(Materials Science, Ceramics)

This study developed phase-field method (PFM) technique in oxide melt system by using a new mobility coefficient ($$L$$). The crystal growth rates ($$v_0$$) obtained by the PFM calculation with the constant $$L$$ were comparable to the thermodynamic driving force in normal growth model. The temperature dependence of the $$L$$ was determined from the experimental crystal growth rates and the $$v_0$$. Using the determined $$L$$, the crystal growth rates ($$v$$) in alkali disilicate glasses, Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$ were simulated. The temperature dependence of the $$v$$ was qualitatively and quantitatively so similar that the PFM calculation results demonstrated the validity of the $$L$$. Especially, the $$v$$ obtained by the PFM calculation appeared the rapid increase just below the thermodynamic melting point ($$T_{rm m}$$) and the steep peak at around $$T_{rm m}$$-100 K. Additionally, as the temperature decreased, the $$v$$ apparently approached zero ms$$^-1$$, which is limited by the $$L$$ representing the interface jump process. Furthermore, we implemented the PFM calculation for the variation of the parameter $$B$$ in the $$L$$. As the $$B$$ increased from zero to two, the peak of the $$v$$ became steeper and the peak temperature of the $$v$$ shifted to the high temperature side. The parameters $$A$$ and $$B$$ in the $$L$$ increased exponentially and decreased linearly as the atomic number of the alkali metal increased due to the ionic potential, respectively. This calculation revealed that the $$A$$ and $$B$$ in the $$L$$ were close and reasonable for each other.

JAEA Reports

Critical mass evaluation of minor actinides in aqueous solution; Data for criticality safety assessment of separation process

Morita, Yasuji; Fukushima, Masahiro; Kashima, Takao*; Tsubata, Yasuhiro

JAEA-Data/Code 2020-013, 38 Pages, 2020/09

JAEA-Data-Code-2020-013.pdf:1.94MB

Critical Masses of Cm, Am and the mixture were calculated in metal-water mixtures with water reflector as a basic data for criticality safety assessment of minor actinide separation process. In the mixture of Cm-244 and Cm-245, higher ratio of Cm-245 gives smaller critical mass, but the amount of Cm-245 in the critical mass can be obtained by concentration of Cm-245 in the Cm mixture without depending on the Cm-245 ratio. Critical mass of Cm isotope mixture with 30% Cm-245 was smaller than that of Pu isotope mixture in the practical reprocessing (71% Pu-239 + 17% Pu-240 + 12% Pu-241). When Cm is separated from other element including Am and the solution is concentrated, measure for the critical accident has to be taken. Critical mass of Am-242m is smaller than that of Cm-245, but the ratio of Am-242m in the Am contained in practical spent fuel is small enough, about several percent, and therefore the critical accident by Am does not have to be considered. That by the mixture of Am and Cm does not either.

JAEA Reports

Assessment report on research and development activities in FY2019; Activity "Research and development on high temperature gas-cooled reactor and related heat application technology" (Interim report)

Sector of Fast Reactor and Advanced Reactor Research and Development

JAEA-Evaluation 2020-001, 128 Pages, 2020/08

JAEA-Evaluation-2020-001.pdf:7.44MB

Japan Atomic Energy Agency consulted with the "Evaluation Committee of Research Activities for High Temperature Gas-cooled Reactor (hereinafter referred to as "HTGR") and Related Hydrogen Production Technology" (hereinafter referred to as "Evaluation Committee"), which consists of specialists in the fields of the evaluation subjects of high temperature gas-cooled reactor and related heat application technology, for interim assessment in the 3rd Mid-and Long-Term Plan about the relevance of the management and research activities of the HTGR and related application technology during the period from April 2017 to March 2020. As a result, three members of the Evaluation Committee concluded a score of "S", and seven members of the Evaluation Committee concluded a score of "A". The interim assessment to research and development activities from April 2017 to March 2020 was concluded a score of "A". In addition, the Evaluation Committee recommended that the judgement to move to the construction phase of the HTTR-heat utilization test plant be made after 2 years, after the HTTR will be restarted and the thermal load fluctuation tests using HTTR will be carried out. This report lists the members of the Evaluation Committee and outlines the assessment item and the review process for procedure of the assessment. The assessment report which was issued by the Evaluation Committee is attached.

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