Solidification treatment of simulated decontamination equipment sludge using alkali-activated materials

Matsuzawa, Kazuki*; Yamamoto, Takeshi*; Taniguchi, Takumi; Osugi, Takeshi

Konkurito Kogaku Rombunshu, 36, p.37 - 47, 2025/07

https://doi.org/10.3151/crt.36.37

To dispose the decontamination sludge made from contaminated water in Fukushima Daiichi Nuclear Power Station using alkali-activated materials (AAM), we solidified barium sulfate powder (BS) and potassium hexacyanocobalt(II)-ferrate(II) powder (FCN) with AAM and searched proper compositions corresponding to the standards. At first, we made solidified bodies controlling HO/base ratio, Si/Al molar ratio, and Na/Si molar ratio. When base materials consisted of metakaolin and blast-furnace slag, we found out some proper compositions and two applicable concentrations of solutions to make solidified bodies corresponding to the standards. Secondly, using solutions with the applicable concentrations, we made solidified bodies controlling the amounts of BS, BS+FCN, and HO. The maximum amount of BS+FCN at the proper compositions was larger than that of BS.

Effects of the low-oxygen gas-phase radiolysis on the corrosive environment in the liquid phase

Hata, Kuniki; Kimura, Atsushi*; Taguchi, Mitsumasa*; Sato, Tomonori; Kato, Chiaki; Watanabe, Yutaka*

Zairyo To Kankyo, 72(4), p.126 - 130, 2023/04

https://doi.org/10.3323/jcorr.72.126

Gamma-radiolysis experiments with gas-liquid coexistent samples were carried out to investigate effects of gas-phase radiolysis on corrosive environment for materials in solutions under irradiation. After gamma-ray irradiation, hydrogen peroxide, nitrate ion, nitrite ion were detected in the liquid phase. The production yields of nitrate ion and nitrite ion increased with increasing gas-phase volume and oxygen concentration. This result indicated that chemical reactions including oxygen and nitrogen in the gas phase were required for the production of nitrate ion and nitrite ion. To magnify the effects of gas-phase radiolysis in the gas-liquid coexistent samples, absorption dose rate in the liquid phase was reduced by one-hundredth using lead shield. The concentration of hydrogen peroxide and the pH in the shielded liquid phase were similar to those in the irradiated pure water, which did not contact with gas phase. This result indicated that the effects of nitrate ion and nitrite ion dissolved in the liquid phase on water radiolysis were not important in the current experimental system, in which the effects of gas-phase radiolysis were increased by 100-times.

Radiolysis effects, which should be taken into account for safe decommissioning of Fukushima-Daiichi Nuclear Power Station

Hata, Kuniki

Zairyo To Kankyo, 70(12), p.468 - 473, 2021/12

https://doi.org/10.3323/jcorr.70.468

In order to estimate corrosive environment in the contaminated water at Fukushima Daiichi Nuclear Power Station, effects of oxidants, such as HO, which were generated from water radiolysis, should be taken into account due to the irradiation field in the reactor building. The process of water radiolysis and the amounts of these oxidants can change depending on the conditions of water and types of radiation. After the accident, a variety of factors, which can affect water radiolysis, such as seawater constituents, surface of oxides, and -radionuclides, had been discussed. In this paper, these effects on radiolysis are reviewed for the better understanding of the corrosive environment in the contaminated water.

Lessons learned from the process focusing on achieving the state of cold shutdown of Fukushima Daiichi Nuclear Power Plant Accident

Yoshizawa, Atsufumi*; Oba, Kyoko; Kitamura, Masaharu*

Ningen Kogaku, 54(3), p.124 - 134, 2018/06

Fukushima Daiichi Nuclear Power Plant caused a severe accident which released a large amount of radioactivity triggered by the Great East Japan Earthquake. The existing investigation reports of the accident prepared by several institutions pay attention only to the process which caused the accident but not much to the accident mitigation or the recovery process. This study focused on Unit 3 of Fukushima Daiichi Nuclear Power Plant, including its recovery process from the accident. Based on the public data, the time sequences for the recovery process between the accident occurrence and the state of cold shutdown were classified. Then, the groups of actions were sorted out in terms of ergonomics viewpoint. The important responses in the recovery process were identified and analyzed referring to the m-SHEL model. As a result, new lessons were learned from the accident case regarding the actions required for recovering from the accident.

The Survey for the integrity of containers for secondary wastes generated from contaminated water treatment

Iida, Yoshihisa; Nakadoi, Yasumasa; Yamaguchi, Tetsuji

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(1), p.53 - 64, 2017/06

https://doi.org/10.3327/jnuce.24.1_53

The information on the contaminated water treatment in Fukushima Daiichi Nuclear Power Station announced by Tokyo Electric Power Co., Inc. (TEPCO) were summarized in terms of the management of the secondary wastes, for the purpose of accumulating technical knowledge for long-term storage of the wastes. Concerns for the long-term soundness of waste storage containers were pointed out as follows, corrosion of stainless steel containers exposed to radiation in the presence of chloride ions, corrosion of stainless steel containers under acidic conditions or in the presence of activated carbon, and radiation degradation of the high-performance container (HIC) in which slurry was stored.

The Hydrogen gas generation by electron-beam irradiation from ALPS adsorbents solidified by several inorganic materials

Sato, Junya; Suzuki, Shinji*; Kato, Jun; Sakakibara, Tetsuro; Meguro, Yoshihiro; Nakazawa, Osamu

QST-M-2; QST Takasaki Annual Report 2015, P. 87, 2017/03

https://repo.qst.go.jp/records/73804

no abstracts in English

Additional information to report on site tour of the Fukushima Daiichi Nuclear Power Station

Suto, Toshiyuki

Genshiryoku, hoshasen Bukaiho (Internet), (19), P. 15, 2016/12

The Tritiated Water Task Force under METI's Committee on Countermeasures for Contaminated Water Treatment for Fukushima Daiichi Nuclear Power Plant (1F) reported that the option of post-dilution offshore release could dispose the tritiated water at a smallest cost in the shortest amount of time. The amount of tritium in the contaminated water at 1F was compared with ones released from nuclear power plants and reprocessing plants as some help for grasping its level of magnitude.

Application to contaminated water management in the Fukushima Daiichi Nuclear Power Station using the plastic scintillation fiber

Sanada, Yukihisa; Yamada, Tsutomu*; Sato, Yoshiharu; Nishizawa, Yukiyasu; Ishibashi, Satoshi*; Watanabe, Masahisa; Torii, Tatsuo

JAEA-Research 2016-011, 52 Pages, 2016/09

JAEA-Research-2016-011.pdf:10.54MB

In the Tokyo Electric Power Co.,Inc. the Fukushima Dai-ichi Nuclear Power Station, management of the contaminated water becomes the social problem, and the situation that severe correspondence is necessary continues to prevent an outflow to the ocean. Plastic scintillation fiber (PSF) can apply as technique to direct measure the concentration of radioactive material in the water at a tank and drainage. In this paper, the results of fundamental test was summarized to apply for monitoring of leakage to the tank and monitoring of drainage in the Fukushima Dai-ichi Nuclear Power Station.

Experimental investigation of activities and tolerance of denitrifying bacteria under alkaline and reducing condition

Mine, Tatsuya*; Mihara, Morihiro;

JNC TN8430 2000-009, 35 Pages, 2000/07

JNC-TN8430-2000-009.pdf:0.88MB

In the geological disposal system of TRU wastes, nitrogen generation by denitrifying bacteria could provide significant impact on the assessment of this system, because nitrate contained in process concentrated liquid waste might be electron acceptor for denitrifying bacteria. In this study, the activities and tolerance of denitrifying bacteria under disposal condition were investigated. pseudomonas denitrificans as denitrifying bacteria was used. The results showed that Pseudomonas denitrificans had activity under reducing condition, but under high pH condition (PH9.5), the activity of Pseudomonas denitrificans was not detected. It is possible that the activity of Pseudomonas denitrificans would be low under disposal condition.

Characterization of secondary waste generated by Fukushima Daiichi Nuclear Power Station accident, 3; Analysis of slurry generated from multi-nuclide removal equipment

Fukuda, Yuhei; Suganuma, Takashi; Hinai, Hiroshi; Ikeda, Akira*; Obata, Masamichi*; Shibata, Atsuhiro; Nomura, Kazunori

no journal, , 

no abstracts in English