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Journal Articles

Analytical study on removal mechanisms of cesium aerosol from a noble gas bubble rising through liquid sodium pool, 2; Effects of particle size distribution and agglomeration in aerosols

Miyahara, Shinya*; Kawaguchi, Munemichi; Seino, Hiroshi; Atsumi, Takuto*; Uno, Masayoshi*

Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (ICONE 28) (Internet), 6 Pages, 2021/08

In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released from the failed pin as an aerosol such as cesium iodide and/or cesium oxide together with a fission product noble gas such as xenon and krypton. As the result, the xenon and krypton released with cesium aerosol into the sodium coolant as bubbles have an influence on the removal of cesium aerosol by the sodium pool in a period of bubble rising to the pool surface. In this study, cesium aerosol removal behavior due to inertial deposition, sedimentation and diffusion from a noble gas bubble rising through liquid sodium pool was analyzed by a computer program which deals with the expansion and the deformation of the bubble together with the aerosol absorption considering the effects of particle size distribution and agglomeration in aerosols. In the analysis, initial bubble diameter, sodium pool depth and temperature, aerosol particle diameter and density, initial aerosol concentration in the bubble were changed as parameter, and the results for the sensitivities of these parameters on decontamination factor (DF) of cesium aerosol were compared with the results of the previous study in which the effects of particle size distribution and agglomeration in aerosols were not considered. From the results, it was concluded that the sensitivities of initial bubble diameter, the aerosol particle diameter and density to the DF became significant due to the inertial deposition of agglomerated aerosols. To validate these analysis results, the simulation experiments have been conducted using a simulant particles of cesium aerosol under the condition of room temperature in water pool and air bubble systems. The experimental results were compared with the analysis results calculated under the same condition.

JAEA Reports

Basic study for on-line monitoring of tiny particles including alpha emitters by aerosol time-of-flight mass spectroscopy (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*

JAEA-Review 2020-050, 69 Pages, 2021/01

JAEA-Review-2020-050.pdf:3.79MB

JAEA/CLADS had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project in FY2019. Among the adopted proposals in FY2019, this report summarizes the research results of the "Basic study for On-Line Monitoring of Tiny Particles including Alpha Emitters by Aerosol Time-Of-Flight Mass Spectroscopy" conducted in FY2019.

JAEA Reports

Development of the technology for preventing radioactive particles' dispersion during the fuel debris retrieval (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

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

JAEA-Review 2020-043, 116 Pages, 2021/01

JAEA-Review-2020-043.pdf:7.74MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of the technology for preventing radioactive particles' dispersion during the fuel debris retrieval" conducted in FY2019. In this study, a technique to effectively suppress the scattering of fine particles has been developed, and as a result of experiments, a method of spraying with water mist was found to be an effective and applicable method for improving aerosol removal efficiency and removal rate. As a method of solidifying fuel debris to suppress fine particle scattering during cutting, geopolymer was evaluated for its strength, thermal conductivity and cutting powder. In addition, flow status of geopolymer and the temperature distribution inside RPV covered by geopolymer were simulated.

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

Analytical study on removal mechanisms of cesium aerosol from a noble gas bubble rising through liquid sodium pool

Miyahara, Shinya*; Kawaguchi, Munemichi; Seino, Hiroshi

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

In a postulated accident of fuel pin failure of sodium cooled fast reactor, a fission product cesium will be released as an aerosol such as cesium iodide and/or oxide together with xenon and/or krypton. In this study, cesium aerosol removal behavior due to inertial deposition, sedimentation and diffusion was analyzed by a computer program which deals with the expansion and the deformation of the bubble together with the aerosol absorption. Initial bubble diameter, sodium pool depth and temperature, aerosol particle diameter and density, initial aerosol concentration were changed as parameter. From the results, it was concluded that the initial bubble diameter was most sensitive parameter to the decontamination factor (DF). It was found that the sodium pool depth, the aerosol particle diameter and density have also important effect on the DF, but the sodium temperature has a marginal effect. To meet these results, the experiments are under planning to validate the results.

Journal Articles

Observation of aerosol particle capturing behavior near gas-liquid interface

Uesawa, Shinichiro; Yoshida, Hiroyuki

Mechanical Engineering Journal (Internet), 7(3), p.19-00539_1 - 19-00539_9, 2020/06

JAEA Reports

Development of technology to prevent scattering of radioactive materials in fuel debris retrieval (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

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

JAEA-Review 2019-037, 90 Pages, 2020/03

JAEA-Review-2019-037.pdf:7.0MB

JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Technology to Prevent Scattering of Radioactive Materials in Fuel Debris Retrieval". The objective of the present study is to clarify the behavior of microparticles in gas and liquid phases in order to steadily confine radioactive microparticles at the time of debris retrieval in Fukushima Daiichi Nuclear Power Station. In addition, as measures to prevent scattering, we will evaluate and develop methods by experiments and simulation as to; (1) a method to suppress the scattering with minimum amount of water utilizing water spray etc., and (2) a method to suppress the scattering by solidifying fuel debris.

Journal Articles

Development of evaluation method for aerosol particle deposition in a reactor building based on CFD

Horiguchi, Naoki; Miyahara, Naoya; Uesawa, Shinichiro; Yoshida, Hiroyuki; Osaka, Masahiko

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

For source term evaluation from reactor buildings (RBs) in LWR severe accidents, we have launched to develop an evaluation method of FP aerosol particle deposition onto surfaces of internal structures in an RB based on computational fluid dynamics (CFD). This paper describes development of a CFD simulation tool as the base part of the evaluation method. A preliminary simulation for a representative RB under a representative flow condition was conducted to confirm the tool performance by roughly grasping the deposition behaviors of FP aerosol particle and decontamination factor (DF) in the RB. Calculation results showed that most of aerosol particles were deposited along with gas flow formed by the internal structures in the RB, demonstrating the advantageous feature of the present CFD tool. The DFs from 4 to 14 were obtained with increase of the particle diameters from 0.1 to 10 $$mu$$m as expected in terms of the particle movement equation.

Journal Articles

Observation of aerosol particle behavior near gas-liquid interface

Uesawa, Shinichiro; Miyahara, Naoya; Horiguchi, Naoki; Yoshida, Hiroyuki; Osaka, Masahiko

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 5 Pages, 2019/05

Journal Articles

Thermal-hydraulic safety research on nuclear containment vessel at JAEA

Shibamoto, Yasuteru; Yonomoto, Taisuke; Hotta, Akitoshi*

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 58(9), p.553 - 557, 2016/09

no abstracts in English

Journal Articles

State-of-the-art report on nuclear aerosols

Allelein, H.-J.*; Auvinen, A.*; Ball, J.*; G$"u$ntay, S.*; Herranz, L. E.*; Hidaka, Akihide; Jones, A. V.*; Kissane, M.*; Powers, D.*; Weber, G.*

NEA/CSNI/R(2009)5, 388 Pages, 2009/12

Journal Articles

Characterization of radionuclides formed by high-energy neutron irradiation

Yokoyama, Sumi; Sato, Kaoru; Noguchi, Hiroshi; Tanaka, Susumu; Iida, Takao*; Furuichi, Shinya*; Kanda, Yukio*; Oki, Yuichi*; Kaneto, Taihei*

Radiation Protection Dosimetry, 116(1-4), p.401 - 405, 2005/12

 Times Cited Count:1 Percentile:11.17(Environmental Sciences)

The physicochemical property of radionuclides suspended in the air is an important parameter to evaluate internal doses due to the inhalation of the airborne radionuclides and to develop the air monitoring system in high-energy proton accelerator facilities. This study focuses on the property of radioactive airborne chlorine ($$^{38}$$Cl and $$^{39}$$Cl) and sulfur ($$^{38}$$S) formed from Ar gas by irradiation with high-energy neutrons. As a result of the irradiation to a mixture of Ar gas and dry air, $$^{38}$$Cl and $$^{39}$$Cl existed as non-acidic gas and $$^{38}$$S was present as acidic gas. Further, it was found that in the high-energy neutron irradiation to aerosol containing-Ar gas, the higher the amount of radioactive aerosols becomes, the lower that of radioactive acidic gas becomes.

Journal Articles

Seasonal characteristics of chemical compositions of the atmospheric aerosols collected in urban seaside area at Tokaimura, eastern central Japan

Fu, F.; Watanabe, Kazuo; Yabuki, Sadayo*; Akagi, Tasuku*

Journal of Geophysical Research, 109(20), p.D20212_1 - D20212_9, 2004/10

Size-separated aerosol samples were collected at Tokaimura urban seaside area of Japan using an Andersen type sampler during July 2002 to July 2003. The size-separated aerosols were divided into water-soluble and insoluble fractions, and chemical compositions (Na$$^{+}$$, Cl$$^{-}$$, NH$$_{3}$$$$^{+}$$, NO$$_{3}$$$$^{-}$$, SO$$_{4}$$$$^{2-}$$, Al, Ca, Mg, Fe, Pb, Th and U) in both water-soluble and insoluble fractions were analyzed. Then, the seasonal variations and the size-distribution in mass concentration and chemical composition have been investigated in detail. Our results showed that the atmospheric aerosol in Tokaimura was obviously affected by dust storm in China, and that sea-salt particles were bigger than those in the Antarctic and were deficient in chlorine.

Journal Articles

The Use of Si carriers for aerosol particle collection and subsequent elemental analysis by total-reflection X-ray fluorescence spectrometry

Esaka, Fumitaka; Watanabe, Kazuo; Onodera, Takashi; Taguchi, Takuji; Magara, Masaaki; Usuda, Shigekazu

Spectrochimica Acta, Part B, 58(12), p.2145 - 2155, 2003/12

 Times Cited Count:18 Percentile:59.65(Spectroscopy)

In order to improve the sensitivity of elemental analysis for aerosol particles by total-reflection X-ray fluorescence spectrometry (TXRF), silicon wafer carriers with diameters of 25 mm were selected and prepared for direct impact collection and subsequent analysis. The detection limits of elements on the carrier were determined and found to be superior to those on glassy carbon and quartz glass carriers used in previous studies. By using the silicon wafer carriers, aerosol particles with the sizes of $$>$$2.0 $$mu$$m, 0.3-2.0 $$mu$$m and 0.05-0.3 $$mu$$m were collected at Ibaraki in Japan from January to August 2002 and analyzed by TXRF. Selenium Consequently, the elements with the concentration of ng/m$$^{3}$$ &8211; pg/m$$^{3}$$ in the particles were successfully detected. The results revealed that K, V, Zn, Br and Pb were concentrated in fine particles, which is presumed to arise from anthropogenic sources. In contrast, Ca, Ti and Fe were contained in coarse particles, which is presumed to arise from soil.

Journal Articles

Extraction of europium(III) into W/O microemulsion containing aerosol OT and a bulky diamide, 1; Cooperative effect

Suzuki, Hideya*; Naganawa, Hirochika; Tachimori, Shoichi

Solvent Extraction and Ion Exchange, 21(4), p.527 - 546, 2003/03

 Times Cited Count:12 Percentile:46.24(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Particle size analysis of radioactive aerosols formed by irradiation of argon using 65MeV quasi-monoenergetic neutrons

Endo, Akira; Noguchi, Hiroshi; Tanaka, Susumu; Kanda, Yukio*; Oki, Yuichi*; Iida, Takao*; Sato, Kaoru; Tsuda, Shuichi

Applied Radiation and Isotopes, 56(4), p.615 - 620, 2002/04

 Times Cited Count:3 Percentile:24.34(Chemistry, Inorganic & Nuclear)

Formation mechanism and size distribution of radioactive aerosol particles generated in a high-energy neutron field were studied in order to evaluate a particle size parameter for internal dose evaluation in high-energy accelerator facilities. Argon gas containing DOP aerosols was irradiated by a 65MeV quasi-monoenergetic neutron beam of TIARA. The number size distribution of the DOP aerosols and the activity-weighted size distribution of $$^{38}$$Cl and $$^{39}$$Cl aerosols, formed from the (n, 2np) and (n, np) reactions of $$^{40}$$Ar, were measured using an electrical low-pressure impactor. The activity-weighted size distribution of the radioactive aerosols was well explained by the simple attachment model of the radioactive atoms to the DOP aerosols.

Journal Articles

Revaporization of CsI aerosol in a horizontal straight pipe in a severe accident condition

Shibazaki, Hiroaki*; Maruyama, Yu; Kudo, Tamotsu; Hashimoto, Kazuichiro*; Maeda, Akio*; Harada, Yuhei*; Hidaka, Akihide; Sugimoto, Jun

Nuclear Technology, 134(1), p.62 - 70, 2001/04

 Times Cited Count:3 Percentile:28.03(Nuclear Science & Technology)

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

Journal Articles

Characterization of individual particles including lead by combination of SIMS and EPMA

Esaka, Fumitaka; Watanabe, Kazuo; Magara, Masaaki; Hanzawa, Yukiko; Usuda, Shigekazu; Gunji, Katsubumi; Nishimura, Hideo; Adachi, Takeo

Proceedings of 12th International Conference on Secondary Ion Mass Spectrometry (SIMS 12), p.977 - 980, 2000/00

no abstracts in English

70 (Records 1-20 displayed on this page)