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Nakagawa, Akinori; Sasaki, Toshiki; Sakamoto, Yoshiaki
Radioactive Waste Management; Solutions for a Sustainable Future (Supplement) (Internet), 7 Pages, 2023/00
Japan Atomic Energy Agency (JAEA) has stored radioactive wastes generated from R&D activities related to nuclear science and technology. A part of these wastes contains compressed wastes without prior radiological, chemical or physical characterization assessed, as well as mixed wastes containing lead and mercury with little information about its contents. Pre-treatment and radiological characterization efforts for such problematic wastes are very time consuming and costly. In order to optimize the processing and disposal of the problematic wastes, a method to balance the processing work and disposal facility robustness was studied. Work analysis of waste processing showed bottleneck processes, such as radiological characterization and segregation of hazardous materials and combustibles. Establishment of a conservative scaling factor method and non-destructive gamma-ray measurement enable easier radiological characterization. Hazardous materials will be identified using records and nondestructive inspection. The waste identified as hazardous will be unpacked and segregated. Based on preliminary survey of about 1,000 drums, only 10 % of stored drums contain hazardous materials and need segregation. Regarding the separation of combustibles, total volume of the combustibles will be evaluated using nondestructive inspection technique such as high-energy X-ray CT and the waste that does not comply with the waste acceptance criteria should be mixed with waste containing a small amount of combustibles in order to satisfy the waste acceptance criteria on a disposal facility average. It was estimated that segregation throughput of compressed waste should be increased about 5 times more than conventional method by applying the countermeasures.
Nakagawa, Akinori; Oyokawa, Atsushi; Murakami, Masashi; Yoshida, Yukihiko; Sasaki, Toshiki; Okada, Shota; Nakata, Hisakazu; Sugaya, Toshikatsu; Sakai, Akihiro; Sakamoto, Yoshiaki
JAEA-Technology 2021-006, 186 Pages, 2021/06
JAEA-Technology-2021-006.pdf:54.45MB
Radioactive wastes generated from R&D activities have been stored in Japan Atomic Energy Agency. In order to reduce the risk of taking long time to process legacy wastes, countermeasures for acceleration of waste processing and disposal were studied. Work analysis of waste processing showed bottleneck processes, such as evaluation of radioactivity concentration, segregation of hazardous and combustibles materials. Concerning evaluation of radioactivity concentration, a radiological characterization method using a scaling factor and a nondestructive gamma-ray measurement should be developed. The number of radionuclides that are to be selected for the safety assessment of the trench type disposal facility can decrease using artificial barriers. Hazardous materials, will be identified using records and nondestructive inspection. The waste identified as hazardous will be unpacked and segregated. Preliminary calculations of waste acceptance criteria of hazardous material concentrations were conducted based on environmental standards in groundwater. The total volume of the combustibles will be evaluated using nondestructive inspection. The waste that does not comply with the waste acceptance criteria should be mixed with low combustible material waste such as dismantling concrete waste in order to satisfy the waste acceptance criteria on a disposal facility average. It was estimated that segregation throughput of compressed waste should be increased about 5 times more than conventional method by applying the countermeasures. Further study and technology development will be conducted to realize the plan.
Kato, Jun; Nakagawa, Akinori; Taniguchi, Takumi; Sakakibara, Tetsuro; Nakazawa, Osamu; Meguro, Yoshihiro
JAEA-Review 2017-015, 173 Pages, 2017/07
JAEA-Review-2017-015.pdf:6.67MB
Various radioactive wastes have been generated at the Fukushima Daiichi Nuclear Power Station (1F). To dispose of the wastes underground, it is necessary to make a suitable waste package by the volume reduction and solidification of the wastes. To plan the future decommissioning of 1F, it is also necessary to estimate feasibility of existing treatment technology for those wastes. Therefore the document survey has been performed about volume reduction and solidification technologies that have domestic or foreign experiences of practical treatment for radioactive wastes to assist selection of suitable treatment of the wastes. This report shows the arranged results. The 1F wastes are classified into two groups, homogeneous particulate and liquid wastes and heterogeneous solid wastes. The needful items for the feasibility study such as a technology name, a fundamental principle, treatment efficiency, and characteristic of solidified waste are summarized in each group.
Meguro, Yoshihiro; Nakagawa, Akinori; Kato, Jun; Sato, Junya; Nakazawa, Osamu; Ashida, Takashi
Proceedings of International Conference on the Safety of Radioactive Waste Management (Internet), p.139_1 - 139_4, 2016/11
A variety of radioactive wastes have been generated in decommissioning of Fukushima Daiichi Nuclear Power Station. It is necessary to evaluate feasibility of conditioning methods to these wastes, because the majority of such wastes have not been solidified in Japan. The authors investigated an approach for screening of conditioning methods for the Fukushima wastes on the basis of the findings of the existing methods and results of fundamental solidification tests using synthetic Fukushima wastes. Here five solidification methods were selected, and also 13 wastes with different chemical composition are solidified, and characteristics of the solidified form are studied. A screening flow was proposed, and evaluation criteria on each step in the flow was set up. In this presentation a trial result was opened for a waste and improvements of the screening flow found in the trial evaluation was described.
Irisawa, Keita; Nakagawa, Akinori; Onizawa, Takashi*; Kogawara, Takafumi*; Hanada, Keiji; Meguro, Yoshihiro
Proceedings of 15th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2013) (CD-ROM), 5 Pages, 2013/09
Times Cited Count：1 Percentile：60.76(Engineering, Environmental)Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi
Proceedings of International Waste Management Symposia 2011 (WM2011) (CD-ROM), 7 Pages, 2011/03
Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi
JAEA-Technology 2010-014, 46 Pages, 2010/06
JAEA-Technology-2010-014.pdf:1.76MB
Steam reforming treatment system was developed for volume reduction of Tri-n-butyl phosphate contaminated with uranium, which is difficult to treat with incineration, due to generation of corrosive compounds, a large amount of secondary waste, etc. This system consists of a steam reforming process in which organic waste is decomposed/gasified in steam atmosphere and a submerged combustion process in which vaporized waste is burned in water and has good features such as high volume reduction rate of waste, low secondary waste generation rate, etc. Results obtained this study were as follows: Volume reduction rate of waste was 99.6%. Uranium entrainment to off-gas was suppressed and the concentration of uranium in waste water was under 0.037mg/L. The concentration of CO and NOx in the off-gas were less than 100ppm and 250ppm respectively. Plugging and corrosion control technologies were developed and it was confirmed that the waste treatment system can run for long periods.
Sone, Tomoyuki; Nakagawa, Akinori; Koyama, Hayato; Gunji, Kiyoshi; Nonaka, Kazuharu; Sasaki, Toshiki; Tashiro, Kiyoshi; Yamashita, Toshiyuki
JAEA-Technology 2009-023, 33 Pages, 2009/06
JAEA-Technology-2009-023.pdf:8.11MB
Steam reforming (SR) method consists of the gasification process in which organics are vaporized and decomposed with superheated steam and the oxidation process in which vaporized organics are decomposed by oxidizing reaction with heated air. 2,500L of waste TBP/n-dodecane contaminated with uranium was treated using the demonstration scale steam reforming system to examine the performance of the system. Results obtained in this study show that the temperature in the SR system was controlled under the self-regulation temperature, the concentration of CO and NOx in the off-gas were controlled less than 100ppm and 250ppm respectively, the distribution ratio of uranium to off-gas treatment system was under 0.12% and the gasification ratio of waste TBP was more than 99%. This long-term waste treatment test has demonstrated that the SR system can safely and effectively reduce the volume of the waste.
Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi
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Aoyama, Yoshio; Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi
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Nakanishi, Yoshiki; Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi
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Nakanishi, Yoshiki; Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi
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Nakagawa, Akinori; Kogawara, Takafumi; Onizawa, Takashi; Meguro, Yoshihiro
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Engineering test of high concentrated sodium nitrate separation by electrodialysis with membrane was conducted. In this test, transferation efficiency, electric power consumption, ion selectivity and composition of separated solution were researched.
Meguro, Yoshihiro; Nakagawa, Akinori; Kogawara, Takafumi; Onizawa, Takashi
no journal, ,
Based on basic experiments of sodium nitrate separation by electrodialysis with membrane, an apparatus concept was established and an engineering scale equipment was built. A designed separation ability was showed in a performance test.
Nakagawa, Akinori; Hanada, Keiji; Meguro, Yoshihiro
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Nakagawa, Akinori; Kogawara, Takafumi; Onizawa, Takashi*; Hanada, Keiji; Nakayama, Takuya; Meguro, Yoshihiro
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Sato, Junya; Suzuki, Shinji; Nakagawa, Akinori; Kato, Jun; Sakakibara, Tetsuro; Nakazawa, Osamu; Yamashita, Masaaki; Sato, Fuminori; Sukegawa, Hirobumi; Meguro, Yoshihiro
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Sato, Junya; Suzuki, Shinji; Nakagawa, Akinori; Kato, Jun; Sakakibara, Tetsuro; Meguro, Yoshihiro; Nakazawa, Osamu
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irradiation for inorganic solidified samples containing simulated ALPS wastesSato, Junya; Suzuki, Shinji; Nakagawa, Akinori; Kato, Jun; Sakakibara, Tetsuro; Meguro, Yoshihiro; Nakazawa, Osamu
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Meguro, Yoshihiro; Sato, Junya; Kato, Jun; Nakagawa, Akinori; Koma, Yoshikazu; Ashida, Takashi
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A large quantity of contaminated water is accumulated in nuclear reactor buildings in Fukushima Daiichi Nuclear Power Station. Because various radionuclides are dissolved in the accumulated water, several decontamination devices based on deposition and adsorption are used for the decontamination. Therefore, several sludge and used adsorption materials are generated. These most are different from wastes caused by the operation of commercial nuclear power stations so far in properties, and these have not been disposed of commercially. As then feasibility of conventional solidification techniques to the wastes should be investigated prior to selection of solidification technique of the wastes. In this study as a first step of feasibility study, three types of sludge and three absorbents were solidified using cement materials and solidification behavior and properties of solidified material were investigated, and then feasibility of cementation to these wastes was evaluated.
