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JAEA Reports

Basic policy for rational measures of radioactive waste processing and disposal; Results of studies for acceleration of waste processing

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.

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

JAEA Reports

Development of waste management system

Mitsuda, Motoyuki; Sasaki, Toshiki

JAEA-Technology 2015-013, 29 Pages, 2015/06

JAEA-Technology-2015-013.pdf:0.96MB

For implementation of disposal of the radioactive waste generated from Japan Atomic Energy Agency, Waste Management System which manages all of the waste data has been developed. We surveyed the kinds of data needed for the waste management at each site, and we set the standard waste management data items. We developed conceptual design for the waste management system and established the system for major sites, Nuclear Science Research Institute, Ningyo-toge Environmental Engineering Center, Fugen Decommissioning Engineering Center, Oarai Research and Development Center, Nuclear Fuel Cycle Engineering Laboratories. For other small sites, we accumulate waste data to the common waste storage database. Therefore, we have developed the system which manages the quality assurance waste data depending on waste treatment situation in JAEA.

Journal Articles

Research and development activities for cleanup of the Fukushima Daiichi Nuclear Power Station

Sasaki, Toshiki; Kaminishi, Shuji*; Miyamoto, Yasuaki; Funasaka, Hideyuki

Materials Research Society Symposium Proceedings, Vol.1518, p.257 - 268, 2013/10

BB2012-2567.pdf:1.85MB

The Fukushima Daiichi Nuclear Power Station accident and restoration works have produced significant volume of radioactive waste. The waste has very different characteristics from usual radioactive waste produced in nuclear power stations and it requires extensive research and development for management of the waste. R&D works such as radionuclide analysis of the waste, hydrogen generation/diffusion analysis of a storage vessel, corrosion evaluation of storage vessels, etc. have been performed for characterization and safe storage of the waste. The detailed R&D plan for processing and disposal waste will be established by the end of FY2012.

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

Performance of steam reforming technology in a long term treatment of waste TBP/dodecane

Nakagawa, Akinori; Sone, Tomoyuki; Sasaki, Toshiki; Nakazawa, Osamu; Tashiro, Kiyoshi

Proceedings of International Waste Management Symposia 2011 (WM 2011) (CD-ROM), 7 Pages, 2011/03

JAEA Reports

Treatment technology development of uranium contaminated spent TBP/n-dodecane solvent by steam reforming

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.

JAEA Reports

Long term treatment of waste TBP/n-dodecane with steam reforming system

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.

JAEA Reports

Thermal treatment for TRU waste sorting

Sasaki, Toshiki; Aoyama, Yoshio; Yamashita, Toshiyuki

JAEA-Technology 2009-001, 33 Pages, 2009/03

JAEA-Technology-2009-001.pdf:2.92MB

A thermal treatment that can automatically unpack TRU waste and remove hazardous materials has been developed to reduce the risk of radiation exposure and save operation cost. The thermal treatment is a process of removing plastic wrapping and hazardous material from TRU waste by heating waste at 500 to 700 $$^{circ}$$C. Plastic wrappings of simulated wastes were removed using a laboratory scale thermal treatment system. Celluloses and isoprene rubbers that must be removed from waste for disposal were pyrolyzed by the treatment. Although the thermal treatment can separate lead and aluminum from the waste, a further technical development is needed to separate lead and aluminum. Future technology development subjects for the TRU waste thermal treatment system are summarized.

Journal Articles

Steam-assisted pyrolysis system for decontamination and volume reduction of radioactive organic waste

Sasaki, Toshiki; Sone, Tomoyuki; Koyama, Hayato; Yamaguchi, Hiromi

Journal of Nuclear Science and Technology, 46(3), p.232 - 238, 2009/03

 Times Cited Count:7 Percentile:49.38(Nuclear Science & Technology)

A demonstration scale steam reforming treatment system was tested for the treatment of waste tri-n-butyl phosphate/n-dodecane contaminated uranium and simulated halogenated organic wastes stored in the Japan Atomic Energy Agency. The steam reforming treatment system was designed for the organic waste which produced a lot of acidic compounds by incineration and gave severe damage to incinerators. The system comprises a gasification process for decontamination by pyrolysis and steam reforming in a gasification chamber and a destruction process by oxidation with heated air in a submerged combustion type reactor for corrosion prevention. Wastes were reduced by 98 to 99.4% in weight during the treatment without any trouble by the acidic compounds. Almost all uranium was retained in the gasification chamber and uranium concentration of secondary waste water was very low that can permit the discharge of the neutralized waste water in the river.

JAEA Reports

Research and development for treatment and disposal technologies of TRU waste; JFY 2007 annual report

Kamei, Gento; Honda, Akira; Mihara, Morihiro; Oda, Chie; Murakami, Hiroshi; Masuda, Kenta; Yamaguchi, Kohei; Matsuda, Setsuro; Ichige, Satoru; Takahashi, Kuniaki; et al.

JAEA-Research 2008-082, 84 Pages, 2008/11

JAEA-Research-2008-082.pdf:2.52MB
JAEA-Research-2008-082(errata).pdf:0.15MB

Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H19 (2007) fiscal year, which are (1) treatment and packaging of TRU waste including applicability of calcination for unpacking and sorting of wastes, characterization and inspection methodology of TRU waste, (2) mechanical assessment for the near-field structure including model development and preparation, introduction of hostrock creep model and coupling analysis of deformation of hostrock and engineered barrier. (3) performance assessment of the disposal system including data acquisition and preparation on radionuclides migration, cementitious material alteration, bentonite and hostrock alteration with alkaline solution and nitrate effect, and (4) alternative technology development including decomposition of nitrate.

JAEA Reports

Stabilization of simulated radioactive lead waste and simulated low level radioactive liquid waste using reformed sulfur (Joint research)

Sone, Tomoyuki; Sasaki, Toshiki; Miyamoto, Yasuaki; Yamaguchi, Hiromi; Inoue, Haruka*; Kihara, Tsuyoshi*; Takei, Yoshihisa*; Tatekawa, Takaiki*; Fukaya, Masaaki*; Iriya, Keishiro*; et al.

JAEA-Technology 2008-032, 25 Pages, 2008/03

JAEA-Technology-2008-032.pdf:5.54MB

Reformed sulfur (RS) is superior in water interception and acid resistance compared with cement. Therefore solidified wastes with RS should have the high resistance to leaching. Unconfined compressive strength test and leaching test using solidified simulated wastes containing lead contaminated with radioactive nuclides (Lead waste) with RS and solidified simulated low level radioactive liquid waste (LLLW) with RS were conducted to examine the applicability of reformed sulfur solidification method (RSSM) as solidification technique of Lead waste and LLLW. The results of these studies show that RSSM is effective technique for stabilization of lead compared with cement solidification method because solidified lead with RS has much stronger resistance to leaching of lead than solidified lead with cement. It also show that the applicability of RSSM as solidification technique of the waste containing lead oxide and LLLW is low because the resistance to leaching of solidified lead oxide with RS and of solidified simulated LLLW with RS were equal to or lower than those of solidified products with cement respectively.

JAEA Reports

Treatment of waste TBP/n-dodecane with steam reforming system

Sone, Tomoyuki; Nonaka, Kazuharu; Sasaki, Toshiki; Yamaguchi, Hiromi

JAEA-Technology 2008-006, 23 Pages, 2008/03

JAEA-Technology-2008-006.pdf:3.54MB

Steam reforming method consists of the gasification process (GP) in which organics are vaporized and decomposed with superheated steam and the oxidation process in which vaporized organics are decomposed with heated air. Experimental study in which waste TBP/n-dodecane (WTBP) containing uranium was used was conducted with the steam reforming system (SRS) to examine the distribution ratio of uranium in the system, the feasibility of treatment of WTBP and the effect of treatment with SRS on the volume reduction of WTBP. The results of these studies are as follows: (1) Most of uranium compounds in WTBP are separated from organics in GP. (2) Only the solid waste remained in GP is the radioactive secondary waste from the treatment of WTBP with SRS. (3) The maintenance operation of the equipments installed downstream of GP become easy to perform. (4) The volume of secondary solid wastes is very small because more than 99% of the WTBP were evaporated in GP. (5) It was estimated that the effect of treatment with SRS on the volume reduction of WTBP is 30 times more than that of pyrolysis method. These results show that SRS can achieve high volume reduction of WTBP.

JAEA Reports

Heat calculation for gasification chamber of steam reformer

Okanuma, Hiroshi; Sasaki, Toshiki; Yamaguchi, Hiromi

JAEA-Research 2007-090, 46 Pages, 2008/02

JAEA-Research-2007-090.pdf:2.57MB

JAEA has many kinds of low level radioactive wastes and some of them are difficult to be decomposed by an incinerator. Steam reforming as treatment technology for low level radioactive wastes has been developed for decomposition and mineralization of the wastes in waste management department of JAEA, which contributes to appropriate disposal of the wastes. In this report, a heat calculation model for the gasification chamber of the steam reformer has been developed for estimation what samples can be treated or not, and effective and efficient improvement of operation. The following two cases have been calculated by the heat calculation model and it has been verified by comparing the results of calculation with the experimental data which were obtained in the latter half of fiscal year 2006. One calculation case is concerned with the operation of gasification chamber without sample feed. The other is concerned with the operation of gasification chamber with sample feed. The results of heat calculation without sample feed are in agreement with the experimental data relatively, but those of with sample are more different from the experimental data than those of without sample. This shows that the heat calculation model we have developed is feasible in terms of gas heating, but has problems in terms of physical and chemical changes of the sample in the gasification chamber. We need to modify the model in the part of physical and chemical changes of the sample in it.

JAEA Reports

Treatment of simulated waste TBP/n-dodecan and halogenated oils with steam reforming system

Sone, Tomoyuki; Nonaka, Kazuharu; Sasaki, Toshiki; Yamaguchi, Hiromi

JAEA-Technology 2007-063, 42 Pages, 2008/01

JAEA-Technology-2007-063.pdf:2.17MB

Steam reforming method has been developed for the treatment of organic wastes which are not suitable materials (tributyl phosphate, halogenated oil) for the incineration due to large quantities of secondary wastes generation. Process demonstration tests were conducted with the demonstration scale steam reforming system to examine the feasibility of treatment of simulated waste solvent (TBP and n-dodecane mixture) and simulated waste oils (halogenated oils and mineral oil mixture). These tests were also conducted to optimize the process conditions. The results of these studies are as follows: (1)More than 98wt% of the simulated wastes were evaporated in the gasification process. Solid residues removed from the gasification process as secondary wastes were inorganic compounds. (2)While the simulated waste oils were treated, the stacking of the filter is reduced by increasing the feed rate of steam from 1.5 kg/h to 3.0 kg/h. (3)Most of phosphoric acids produced by thermal decomposition of TBP were vaporized in the gasification process at 600$$sim$$650$$^{circ}$$C. This result shows that volume of radioactive secondary waste can be effectively reduced.

Journal Articles

Thermal pretreatment for TRU waste sorting

Sasaki, Toshiki; Aoyama, Yoshio; Miyamoto, Yasuaki; Yamaguchi, Hiromi

Proceedings of International Waste Management Symposium 2008 (WM '08) (CD-ROM), 8 Pages, 2008/00

Japan Atomic Energy Agency conducted a study on thermal treatment of TRU waste to develop a removal technology for materials that are forbidden to dispose of. The thermal pretreatment in which hot nitrogen and/or air is introduced to the waste is a process of removing combustibles, liquids, and low melting point metals from PVC wrapped TRU waste. In this study, thermal pretreatment of simulated waste was conducted using a desktop thermal treatment vessel and a laboratory scale thermal pretreatment system. Combustibles such as papers, PVC, oil, etc. were removed and low melting point metals such as zinc, lead, and aluminum were separated from the simulated waste by the thermal pretreatment.

Journal Articles

Reduction of radioactive secondary waste with steam reforming in treatment of waste TBP/dodecane

Sone, Tomoyuki; Sasaki, Toshiki; Yamaguchi, Hiromi

Proceedings of 11th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '07) (CD-ROM), 5 Pages, 2007/00

We have stored waste TBP/dodecane generated from R&D activities on recycle of nuclear fuel. Those wastes can be incinerated, however a large quantity of contaminated phosphorous compounds generate. The objective of this study is to reduce the generation of radioactive secondary waste by the treatment of those wastes using steam reforming system. We conducted process demonstration tests using waste TBP/dodecane with 0.07g/L of uranium. We studied the temperature dependence of the gasification ratio of inorganic phosphorus compounds and removal of uranium by the filter. As the results, more than 95% of phosphorus compounds were gasified at temperature of 600$$^{circ}$$C or more, and more than 98% of uranium compounds were separated from the vaporized waste. The separated phosphorus compounds can be disposed of as the liquid wastes of which concentration of uranium is under the regulatory level. These results show the steam reforming system is effective in the reduction of radioactive secondary waste in the treatment of TBP/dodecane.

Journal Articles

Treatment of Waste TBP/n-Dodecane and Halogenated Oils by Steam Reforming

Suto, Makoto; Masakazu, Takai,; Sasaki, Toshiki; Nakazawa, Osamu; Fukumoto, Masahiro

Proceedings of International Waste Management Symposium 2005 (WM 2005), 0 Pages, 2005/03

None

Journal Articles

Stabilization of Lead in Low-Level Radioactive Waste Form Using Low-Alkalinity Cements

Sasaki, Toshiki; Miyamoto, Yasuaki; Fukumoto, Masahiro

Waste Management symposium 2005, Poster Session, 19b, 0 Pages, 2005/03

None

Journal Articles

Treatment of Waste TBP/n-Dodecane and Halogenated Oils by Steam Reforming

Suto, Makoto; Masakazu, Takai,; Sasaki, Toshiki; Nakazawa, Osamu; Fukumoto, Masahiro

Waste Management 2005 Proceeding, CD-ROM, 6p., 6 Pages, 2005/00

Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.

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