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JAEA Reports

Analysis of risk reduction effect of supposed steam condenser implementation as accident measure for accident of evaporation to dryness by boiling of reprocessed high level liquid waste

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

JAEA-Research 2021-013, 20 Pages, 2022/01

JAEA-Research-2021-013.pdf:2.35MB

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. An idea has been proposed to implement a steam condenser as an accident countermeasure. This measure is expected to prevent nitric acid steam diffusing in facility building and to increase gaseous Ru trapping ratio into condensed water. A simulation study has been carried out with a hypothetical typical facility building to analyze the efficiency of steam condenser. In this study, SCHERN computer code simulates chemical behaviors of Ru in nitrogen oxide, nitric acid and water mixed vapor based on the conditions obtained from simulation with thermal-hydraulic computer code MELCOR. The effectiveness of steam condenser has been analyzed quantitively in preventing mixed vapor diffusion and gaseous Ru trapping effect. Some issues to be solved in analytical model has been also clarified in this study.

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

Experimental study on transport behavior of cesium iodide in the reactor coolant system under LWR severe accident conditions

Miyahara, Naoya; Miwa, Shuhei; Gou$"e$llo, M.*; Imoto, Jumpei; Horiguchi, Naoki; Sato, Isamu*; Osaka, Masahiko

Journal of Nuclear Science and Technology, 57(12), p.1287 - 1296, 2020/12

 Times Cited Count:2 Percentile:62.87(Nuclear Science & Technology)

In order to clarify the cesium iodide (CsI) transport behavior with a focus on the mechanisms of gaseous iodine formation in the reactor coolant system of LWR under a severe accident condition, a reproductive experiment of CsI transport behavior was conducted using a facility equipped with a thermal gradient tube. Various analyses on deposits and airborne materials during transportation could elucidate two mechanisms for the gaseous iodine formation. One was the gaseous phase chemical reaction in Cs-I-O-H system at relatively high-temperature region, which led to gaseous iodine transport to the lower temperature region without any further changes in gas species due to the kinetics limitation effects. The other one was the chemical reactions related to condensed phase of CsI, namely those of CsI deposits on walls with surface of stainless steel to form Cs$$_{2}$$CrO$$_{4}$$ compound and CsI aerosol particles with steam, which were newly found in this study.

Journal Articles

Analysis of chemical behavior of nitrogen oxide formed by thermal decomposition of FP nitrates in accident of evaporation to dryness by boiling of reprocessed high-level liquid waste

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

Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(2), p.69 - 80, 2019/06

An accident of evaporation to dryness by boiling of high level liquid waste (HLLW) is postulated as one of the severe accidents 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 are also released formed by the thermal decomposition of metal nitrates of fission products (FP) in HLLW. It has been observed experimentally that nitrogen oxide affects strongly to the transport behavior of Ru. Chemical reactions of nitrogen oxide with water and nitric acid are also recognized as the complex phenomena to undergo simultaneously in the vapor and liquid phases. An analysis method has been developed with coupling two types of computer codes to simulate not only thermo-hydraulic behavior but also chemical reactions in the flow paths of carrier gases. A simulation study has been also carried out with a typical facility building.

Journal Articles

Chemical reaction kinetics dataset of Cs-I-B-Mo-O-H system for evaluation of fission product chemistry under LWR severe accident conditions

Miyahara, Naoya; Miwa, Shuhei; Horiguchi, Naoki; Sato, Isamu*; Osaka, Masahiko

Journal of Nuclear Science and Technology, 56(2), p.228 - 240, 2019/02

 Times Cited Count:4 Percentile:68.11(Nuclear Science & Technology)

In order to improve LWR source term under severe accident conditions, the first version of a fission product (FP) chemistry database named "ECUME" was developed. The ECUME is intended to include major chemical reactions and their effective kinetic constants for representative SA sequences. It is expected that the ECUME can serve as a fundamental basis from which FP chemical models in the SA analysis codes can be elaborated. The implemented chemical reactions in the first version were those for representative gas species in Cs-I-B-Mo-O-H system. The chemical reaction kinetic constants were evaluated from either literature data or calculated values using ab-initio calculations. The sample chemical reaction calculation using the presently constructed dataset showed meaningful kinetics effects at 1000 K. Comparison of the chemical equilibrium compositions by using the dataset with those by chemical equilibrium calculations has shown rather good consistency for the representative Cs-I-B-Mo-O-H species. From these results, it was concluded that the present dataset should be useful to evaluate FP chemistry in Cs-I-B-Mo-O-H system under LWA SA conditions.

Journal Articles

Development of experimental and analytical technologies for fission product chemistry under LWR severe accident condition

Miyahara, Naoya; Miwa, Shuhei; Nakajima, Kunihisa; Osaka, Masahiko

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 9 Pages, 2017/09

This paper presents the development of a reproductive experimental setup for FP release and transport and an analysis tool considering chemical reaction kinetics for the construction of the FP chemistry database. The performance test of the reproductive experimental setup TeRRa using CsI compounds show that TeRRa can reproduce well a FP chemistry-related behavior such as aerosol formation, growth and deposition behavior. An analytical tool has been developed based on the commercial ANSYS-FLUENT code. Some additional models was added to evaluate detailed FP chemistry during release and transport in this study. A test analysis simulating the CsI heating test in steam atmosphere was carried out to demonstrate the performance of the improved code. The result shows the appropriateness of the additional models.

Journal Articles

Radiochemical study of the kinematics of multi-nucleon transfer reactions in $$^{48}$$Ca + $$^{248}$$Cm collisions 10% above the Coulomb barrier

G$"o$tz, M.*; G$"o$tz, S.*; Kratz, J. V.*; D$"u$llmann, Ch. E.*; Mokry, Ch.*; Runke, J.*; Th$"o$rle-Pospiech, P.*; Wiehl, N.*; Sch$"a$del, M.; Ballof, J.*; et al.

Nuclear Physics A, 961, p.1 - 21, 2017/05

 Times Cited Count:6 Percentile:57.56(Physics, Nuclear)

The kinematics of multi-nucleon transfer reactions in the $$^{48}$$Ca + $$^{248}$$Cm collisions were investigated using a stacked-foil technique and radiochemical separations. In previous studies, isotopic distributions of the products of below-target isotopes were found to be broader than those of above-target isotopes, which had been interpreted as larger contributions of strongly dumped collisions in the productions of below-target isotopes than above-target ones. However, in the present study, the average total kinetic energy loss (TKEL), and thus, the average excitation energies were determined for both below-target and above-target isotopes, and they were found to be similar. This contradicts the previous interpretation, and thus, a new interpretation has been proposed; highly excited above-target products are lost by fission.

Journal Articles

IS process hydrogen production test for components and system made of industrial structural material, 1; Bunsen and HI concentration section

Tanaka, Nobuyuki; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Iwatsuki, Jin; Aita, Hideki; Kasahara, Seiji; Kubo, Shinji

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.1022 - 1028, 2016/11

Japan Atomic Energy Agency (JAEA) has manufactured 100 NL/h-H$$_2$$-scale hydrogen test apparatus. In advance to conduct the continuous operation, we investigated performance of the components in each section of the IS process. In this paper, the results of test of Bunsen and HI concentration sections was shown. In Bunsen reaction, section, we confirmed that outlet gas flow rate included no SO$$_{2}$$ gas, indicating that all the feed SO$$_{2}$$ gas was absorbed to the solution in the Bunsen reactor for the Bunsen reaction. On the basis of these results, we evaluated that Bunsen reactor was workable. In HI concentration section, HI concentration was conducted by EED stack. As a result, it can concentrate HI in HIx solution as theoretically predicted on the basis of the previous paper. Based on the results added to that shown in Series II, we have conducted a trial continuous operation and succeeded it for 8 hours.

Journal Articles

Formation and release of molecular iodine in aqueous phase chemistry during severe accident with seawater injection

Kido, Kentaro; Hata, Kuniki; Maruyama, Yu; Nishiyama, Yutaka; Hoshi, Harutaka*

NEA/CSNI/R(2016)5 (Internet), p.204 - 212, 2016/05

Journal Articles

Chemical reaction of lithium with room temperature atmosphere of various humidities

Furukawa, Tomohiro; Hirakawa, Yasushi; Kondo, Hiroo; Kanemura, Takuji; Wakai, Eiichi

Fusion Engineering and Design, 98-99, p.2138 - 2141, 2015/10

BB2014-0426.pdf:0.49MB

 Times Cited Count:5 Percentile:48.17(Nuclear Science & Technology)

In the International Fusion Materials Irradiation Facility (IFMIF), a back plate of the target assembly will be exchanged during the in-service period. During the works, the lithium components will react chemically with the surrounding atmosphere. In this research, the chemical reaction of lithium in air, oxygen and nitrogen containing variable humidity at room temperature has been investigated to estimate the chemical reaction during the exchange works.

Journal Articles

Development of fast reactor containment safety analysis code, CONTAIN-LMR, 3; Improvement of sodium-concrete reaction model

Kawaguchi, Munemichi; Doi, Daisuke; Seino, Hiroshi; Miyahara, Shinya

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

CONTAIN-LMR code is an integrated analysis tool to predict the consequence of severe accident in a liquid metal fast reactor. A sodium-concrete reaction is one of the most important phenomena, and Sodium-Limestone Concrete Ablation Model (SLAM) has been installed into the original CONTAIN code. The SLAM treats chemical reaction kinetics between the sodium and the concrete compositions mechanistically, the application is limited to the limestone concrete. In order to apply SLAM to the siliceous concrete which is an ordinary structural concrete in Japan, the chemical reaction kinetics model has been improved. The improved model was validated to analyze a series of sodium-concrete experiments which were conducted in Japan Atomic Energy Agency. It has been found that relatively good agreement between calculation and experimental results is obtained and the CONTAIN-LMR code has been validated with regard to the sodium-concrete reaction phenomena.

Journal Articles

Fabrication and electrochemical behavior of nitride fuel for future applications

Arai, Yasuo; Minato, Kazuo

Journal of Nuclear Materials, 344(1-3), p.180 - 185, 2005/09

 Times Cited Count:22 Percentile:82.13(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Simulation of chemical and electrochemical behavior of actinides and fission products in pyrochemical reprocessing

Minato, Kazuo; Hayashi, Hirokazu; Mizuguchi, Koji*; Sato, Takeyuki*; Amano, Osamu*; Miyamoto, Satoshi*

Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.778 - 781, 2003/11

The simulation technology for the pyrochemical reprocessing of oxide fuels was developed to analyze experimental data, to predict experimental results, and to propose adequate conditions and processes. The simulation method was based on calculations of chemical equilibrium and electrochemical reactions. Some model calculations to simulate the experimental results were made on the process of electro-codeposition of UO$$_{2}$$ and PuO$$_{2}$$. Although it was difficult to trace the experiments and compare the calculated results with the experimental results quantitatively due to the limitation of available data on the experimental conditions, the calculated results were consistent with the experimental results. The phenomena of the repeated oxidation-reduction reactions between Pu$$^{4+}$$ and Pu$$^{3+}$$ ions and those between Fe$$^{3+}$$ and Fe$$^{2+}$$ ions were theoretically analyzed,which caused the low current efficiency in the electro-codeposition process.

JAEA Reports

Production of $$^{139}$$Ce by the $$^{139}$$La(p,n)$$^{139}$$Ce reaction

Ishioka, Noriko; Izumo, Mishiroku; Hashimoto, Kazuyuki; Kobayashi, Katsutoshi; Matsuoka, Hiromitsu; Sekine, Toshiaki

JAERI-Tech 2001-095, 23 Pages, 2002/01

JAERI-Tech-2001-095.pdf:1.1MB

no abstracts in English

Journal Articles

Mechanisms and kinetics of hydrogen yield from polymers by irradiation

Seguchi, Tadao

Nuclear Instruments and Methods in Physics Research B, 185(1-4), p.43 - 49, 2001/12

 Times Cited Count:17 Percentile:48.84(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Distribution behavior of plutonium and americium in LiCl-KCl eutectic/liquid cadmium systems

Sakamura, Yoshiharu*; Shirai, Osamu; Iwai, Takashi; Suzuki, Yasufumi

Journal of Alloys and Compounds, 321(1), p.76 - 83, 2001/05

 Times Cited Count:53 Percentile:89.97(Chemistry, Physical)

no abstracts in English

Journal Articles

Airborne gaseous $$^{13}$$N species and noxious gases produced at the 12GeV proton synchrotron

Kanda, Yukio*; Oki, Yuichi*; Endo, Akira; Numajiri, Masaharu*; Kondo, Kenjiro*

Journal of Radioanalytical and Nuclear Chemistry, 247(1), p.25 - 31, 2001/01

 Times Cited Count:9 Percentile:57.68(Chemistry, Analytical)

no abstracts in English

Journal Articles

Evaluation of internal and external doses from $$^{11}$$C produced in the air in high energy proton accelerator tunnels

Endo, Akira; Oki, Yuichi*; Kanda, Yukio*; Oishi, Tetsuya; Kondo, Kenjiro*

Radiation Protection Dosimetry, 93(3), p.223 - 230, 2001/00

 Times Cited Count:6 Percentile:45.58(Environmental Sciences)

no abstracts in English

50 (Records 1-20 displayed on this page)