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Journal Articles

The Current status on analysis of radioactive waste at Fukushima Daiichi Nuclear Power Station

Koma, Yoshikazu

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(2), p.133 - 136, 2019/12

At Fukushima Daiichi Nuclear Power Station, radioactive waste has been generated due to progress of decommissioning. This review outlines analysis of the waste at the site for R&D concerning waste management technologies.

Journal Articles

Effort for management of radioactive waste with unknown quality and amount

Koma, Yoshikazu; Niibori, Yuichi*

Nippon Kikai Gakkai-Shi, 122(1211), p.21 - 23, 2019/10

International Topical Workshop on Fukushima Decommissioning Research was held in March 2019 by the Japan Society of Mechanical Engineers and the Atomic Energy Society of Japan. Result of track for waste management technologies among 5 tracks is outlined.

Journal Articles

Development of calculation methodology for estimation of radionuclide composition in wastes generated at Fukushima Daiichi Nuclear Power Station

Sugiyama, Daisuke*; Nakabayashi, Ryo*; Koma, Yoshikazu; Takahatake, Yoko; Tsukamoto, Masaki*

Journal of Nuclear Science and Technology, 56(9-10), p.881 - 890, 2019/09

 Times Cited Count:1 Percentile:65.13(Nuclear Science & Technology)

Journal Articles

Contamination of Fukushima Daiichi Nuclear Power Station with actinide elements

Koma, Yoshikazu; Murakami, Erina

Radiochimica Acta, 107(9-11), p.965 - 977, 2019/09

 Times Cited Count:0 Percentile:100(Chemistry, Inorganic & Nuclear)

Fukushima Daiichi Nuclear Power Station, which is owned by Tokyo Electric Power Company, suffered from the great earthquake and Tsunami on 11 March 2011, and serious contamination with radioactive nuclides occurred. To investigate methodologies of waste management, contaminated materials have been radiochemically analyzed. This paper reviews the analytical data for actinide elements. Actinide nuclides are detected in the contaminated water. The contaminated water is chemically decontaminated, although actinide concentration does not decrease with time. This suggests that actinides come from the damaged fuel with slow dissolution. From the topsoil at the site, Pu, Am and Cm were detected and come from the damaged fuel, whereas U from natural. TRU would slowly move to deeper. Contamination of rubble is nonuniform and actinides are detected as well as fission products. For vegetation, TRU nuclides were found from fallen leaves near the reactor buildings.

Journal Articles

Investigation of the contamination on the operation floor of unit 2 based on the radiochemical analysis data

Takahatake, Yoko; Koma, Yoshikazu

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

JAEA Reports

Proceedings of the Fukushima Research Conference on Development of Analytical Techniques in Waste Management (FRCWM 2018); June 19th and 20th, Tomioka Town Art & Media Center, Tomioka, Futaba, Fukushima, Japan

Saegusa, Jun; Koma, Yoshikazu; Ashida, Takashi

JAEA-Review 2018-017, 259 Pages, 2018/12

JAEA-Review-2018-017.pdf:53.88MB

Collaborative Laboratories for Advanced Decommissioning Science (CLADS) is responsible to promote international cooperation in the R&D activities on the decommissioning of Fukushima Daiichi Nuclear Power Station and to develop the necessary human resources. CLADS held the Fukushima Research Conference on Development of Analytical Techniques in Waste Management (FRCWM 2018) on 19th and 20th June, 2018. This report compiles the abstracts and the presentation materials in the above conference.

Journal Articles

Control of fine particles accumulation in the extraction chromatography column system for minor actinide recovery

Watanabe, So; Goto, Ichiro; Sano, Yuichi; Nomura, Kazunori; Koma, Yoshikazu

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04

JAEA Reports

Analytical data on contaminated water, rubble and other collected at the Fukushima Daiichi Nuclear Power Station

Asami, Makoto*; Takahatake, Yoko; Myodo, Masato; Tobita, Takeshi; Kobayashi, Kiwami; Hayakawa, Misa; Usui, Yuka; Watahiki, Hiromi; Shibata, Atsuhiro; Nomura, Kazunori; et al.

JAEA-Data/Code 2017-001, 78 Pages, 2017/03

JAEA-Data-Code-2017-001.pdf:4.92MB
JAEA-Data-Code-2017-001-appendix(DVD-ROM).zip:818.06MB

At Fukushima Daiichi Nuclear Power Station owned by Tokyo Electric Power Company Holdings, Incorporated (TEPCO), contaminated water (accumulated, treated) secondary waste from water treatment, rubble and soil were collected and analyzed. The data already opened to public was collected as this report. The analytical data reported by TEPCO, Japan Atomic Energy Agency and International Research Institute for Nuclear Decommissioning until the end of March, 2016, was collected. Information on the samples and values of radioactive nuclide concentration and others were tabulated, besides figures, which show change in radioactive nuclide concentration for major nuclides, are contained. And, English translation and the collected data are provided as electric data.

Journal Articles

Radioactive contamination of several materials following the Fukushima Daiichi Nuclear Power Station accident

Koma, Yoshikazu; Shibata, Atsuhiro; Ashida, Takashi

Nuclear Materials and Energy (Internet), 10, p.35 - 41, 2017/01

 Times Cited Count:10 Percentile:12.74(Nuclear Science & Technology)

Due to the accident of Fukushima Daiichi Nuclear Power Station (NPS) of Tokyo Power Electric Co. in 2011, radioactive nuclides were released to environment and heavily contaminated the NPS site itself. Analytical concentration of radionuclides for contaminated materials including the accumulated water, rubble, soil and vegetation which already opened were utilized to discuss contamination behavior of some radionuclides. The concentration ratio of a radionuclide to that of $$^{137}$$Cs was normalized with composition of the damaged reactor fuels referred to as "transport ratio" to investigate elemental behavior. The transport ratio of Sr to rubble and soil compared with which was assumed to be via air was approximately 10$$^{-2}$$ to 10$$^{-3}$$, and the successive transport to the accumulated water was comparable to Cs except for the initial release. Transport of Pu, Am and Cm were scarce relative to Cs regardless of transport process by means of air and water, whereas those of iodine, selenium and tellurium were comparable or greater. Contamination with $$^{3H}$$ and $$^{14}$$C was independent of $$^{137}$$Cs, $$^{90}$$Sr and TRU nuclides and would be a result of different transport process.

Journal Articles

Estimation of the inventory of the radioactive wastes in Fukushima Daiichi NPS with a radionuclide transport model in the contaminated water

Shibata, Atsuhiro; Koma, Yoshikazu; Oi, Takao

Journal of Nuclear Science and Technology, 53(12), p.1933 - 1942, 2016/12

 Times Cited Count:8 Percentile:23.73(Nuclear Science & Technology)

Journal Articles

Inventory estimation for accident waste generated at the Fukushima Daiichi NPS

Koma, Yoshikazu; Sugiyama, Daisuke*; Ashida, Takashi

Proceedings of International Conference on the Safety of Radioactive Waste Management (Internet), p.153_1 - 153_4, 2016/11

To investigate accident waste management at the Fukushima Daiichi Nuclear Power Station, a methodology of inventory estimation for whole waste including those generated through D&D is indispensable and requires a calculation model. At early stage with insufficient analytical data of waste, a model should be developed by using knowledge of past experience from literature. Uncertainty in estimation shall be decreased based on analytical data available.

Journal Articles

Particle induced X-ray emission-computed tomography analysis of an adsorbent for extraction chromatography

Sato, Takahiro; Yokoyama, Akihito; Kitamura, Akane; Okubo, Takeru; Ishii, Yasuyuki; Takahatake, Yoko; Watanabe, So; Koma, Yoshikazu; Kada, Wataru*

Nuclear Instruments and Methods in Physics Research B, 371, p.419 - 423, 2016/03

 Times Cited Count:3 Percentile:59.43(Instruments & Instrumentation)

Journal Articles

Safety operation of chromatography column system with discharging hydrogen radiolytically generated

Watanabe, So; Sano, Yuichi; Nomura, Kazunori; Koma, Yoshikazu; Okamoto, Yoshihiro

European Physical Journal; Nuclear Sciences & Technologies (Internet), 1, p.9_1 - 9_8, 2015/12

Journal Articles

Safety operation of chromatography column system with discharging hydrogen radiolytically generated

Watanabe, So; Sano, Yuichi; Nomura, Kazunori; Koma, Yoshikazu; Okamoto, Yoshihiro

Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.2781 - 2788, 2015/05

Journal Articles

Transport behavior of radionuclides into the accumulated water at the Fukushima Daiichi NPS

Koma, Yoshikazu; Shibata, Atsuhiro

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

The radioactive contaminated water has been accumulated at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company (TEPCO). Radioactivity concentrations determined for the water was normalized with the fuel composition and divided by that for $$^{137}$$Cs in order to investigate behavior of some elements to contaminate the water. Transport of Sr was initially suppressed and gradually increased to the extent comparable to Cs until almost one year. Transport of $$^{3}$$He, I and Se were greater than that of Cs. Transport of Pu, Am, Cm and Eu were considerably small. Concerning activation product the extent of Co transport was significant than that of Ni.

JAEA Reports

Transfer of radionuclides to soil at Fukushima Daiichi Nuclear Power Station

Koma, Yoshikazu

JAEA-Data/Code 2014-015, 23 Pages, 2014/09

JAEA-Data-Code-2014-015.pdf:2.2MB

Due to the accident of Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company, Incorporated (TEPCO), radionuclides were released to the environment. TEPCO sampled soil around the reactors and analyzed. Transport ratios normalized to $$^{137}$$Cs were calculated using the measurement of soil and calculated fuel composition in the reactors.

Journal Articles

Co-processing of uranium and plutonium for sodium-cooled fast reactor fuel reprocessing by acid split method for plutonium partitioning without reductant

Nakahara, Masaumi; Koma, Yoshikazu; Nakajima, Yasuo

Journal of Nuclear Science and Technology, 50(11), p.1062 - 1070, 2013/11

 Times Cited Count:3 Percentile:68.66(Nuclear Science & Technology)

The acid split method for Pu partitioning without reductant was investigated for improving nuclear proliferation resistance, safety, and cost. A practical acid split flow sheet was configured using a extraction calculation code, and countercurrent experiment was carried out based on their calculation results. 0.15 mol/dm$$^{3}$$ HNO$$_{3}$$ was supplied at 21$$^{circ}$$C for the Pu stripping. The Pu content of the U/Pu product increased to 2.28 times larger than that of the feed solution. In addition, the Pu leakage to the U product was 0.47%. The experimental results indicate that the proposed flow sheet is effective for fast reactor fuel reprocessing.

Journal Articles

Plutonium partitioning in uranium and plutonium co-recovery system for fast reactor fuel recycling with enhanced nuclear proliferation resistance

Nakahara, Masaumi; Koma, Yoshikazu; Nakajima, Yasuo

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.539 - 542, 2013/09

In order to develop a fast reactor fuel reprocessing, countercurrent extraction experiments for Pu reduction partitioning method with hydroxylamine nitrate and acid split method without Pu reductant were carried out. In the Pu reduction method, a part of U was co-recovered with Pu because the U scrubbing part can be deleted in the Pu partitioning section. On the other hand, acid split method experimental results indicate that almost all Pu was recovered with U by supplying diluted HNO$$_{3}$$ solution in the Pu partitioning section. This study shows that not only Pu reduction partitioning but also acid split methods are effective for fast reactor fuel reprocessing.

Journal Articles

Research and development on waste management for the Fukushima Daiichi NPS by JAEA

Koma, Yoshikazu; Ashida, Takashi; Meguro, Yoshihiro; Miyamoto, Yasuaki; Sasaki, Toshiki; Yamagishi, Isao; Kameo, Yutaka; Terada, Atsuhiko; Hiyama, Toshiaki; Koyama, Tomozo; et al.

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.736 - 743, 2013/09

Fukushima Daiichi Nuclear Power Station (F1NPS), TEPCO, was severely damaged with the hydrogen explosions caused by losing their cooling functions due to the earthquake and the tsunami occurred on March 11, 2011. Radioactive wastes generated from the current FINPS and future their decommission and demolition are greater huge amount than those from general reactors and nuclear fuel facilities. Toward accomplishing safe and reasonable management of the wastes, great effort of R&Ds has been strongly required and performed in bringing together the knowledge and experience of all of Japan. This report outlines the current status of the R&Ds performed in JAEA.

Journal Articles

Decontamination of radioactive liquid waste with hexacyanoferrate(II)

Takahatake, Yoko; Watanabe, So; Shibata, Atsuhiro; Nomura, Kazunori; Koma, Yoshikazu

Procedia Chemistry, 7, p.610 - 615, 2012/00

 Times Cited Count:8 Percentile:5.36

162 (Records 1-20 displayed on this page)