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Akagi, Yosuke*; Kato, Hiroyasu*; Tachi, Yukio; Sakamoto, Hiroyuki*
Progress in Nuclear Science and Technology (Internet), 5, p.233 - 236, 2018/11
A large amount of radioactive contaminated concrete will be generated from the decommissioning in the Fukushima Dai-ichi Nuclear Power Plant (NPP). For developing the plans of decommissioning and waste management including decontamination and disposal, it is important to estimate radionuclides inventory and concentration distribution in the concrete materials. In this study, effective diffusivities (De) and distribution coefficients (Kd) of HTO, Cs, I and U in OPC mortar were measured by through-diffusion and batch sorption experiments. De values derived were in the sequence of HTO, I, Cs, U, implying that cation exclusion effects may be important mechanisms in OPC mortar. Kd values derived by batch tests were higher by more than one order of magnitude than the diffusion-derived Kd values, indicating that crushing of samples had a strong influence on sorption. Diffusion and sorption mechanisms in OPC mortar were evaluated to predict the penetration behavior of these radionuclides.
Sakamoto, Hiroyuki*; Akagi, Yosuke*; Yamada, Kazuo*; Tachi, Yukio; Fukuda, Daisuke*; Ishimatsu, Koichi*; Matsuda, Mikiya*; Saito, Nozomi*; Uemura, Jitsuya*; Namihira, Takao*; et al.
Nihon Genshiryoku Gakkai Wabun Rombunshi, 17(2), p.57 - 66, 2018/05
Concrete debris contaminated with radioactive cesium and other nuclides have been generated from the accident in the Fukushima Dai-ichi Nuclear Power Plant and there will be generated due to the decommissioning of nuclear power plants in the future. Although conventional decontamination techniques are effective for flat concrete surfaces such as floors and walls, it is not clear what techniques to apply for decontaminating radioactive concrete debris. In this study, focusing on a pulsed power discharge technique, fundamental experimental works were carried out. Decontamination of concrete by applying the aggregate recycling technique using the pulsed power discharge technique was evaluated by measuring radioactivity of aggregate and sludge separated from the contaminated concrete. The results suggest that the separation into aggregate and sludge of the contaminated concrete debris could achieve decontamination and volume reduction of the radioactive concrete debris.
Arifi, E.*; Ishimatsu, Koichi*; Iizasa, Shinya*; Namihira, Takao*; Sakamoto, Hiroyuki*; Tachi, Yukio; Kato, Hiroyasu*; Shigeishi, Mitsuhiro*
Construction and Building Materials, 67(Part B), p.192 - 196, 2014/09
Times Cited Count：5 Percentile：25.81(Construction & Building Technology)The Fukushima Dai-ichi Nuclear Plant accident has resulted in a large amount of radioactively contaminated concrete. The possible application of the pulsed power discharge to reduce the amount of contaminated concrete as radioactive waste was investigated. The contaminated concrete was decontaminated by separating contaminated matrix from uncontaminated coarse aggregate under pulsed power discharge process. In this study, a stable Cs isotope was used to simulate radioactively contaminated concrete. As a result, while the volume of reclaimed aggregate from contaminated concrete could be reproduced was up to 60%, nevertheless Cs detected in the reclaimed aggregate was only approximately 3%. Thus most of the Cs were dissolved in water during the discharge process. It is expected that the pulsed power could reduce the contaminated concrete waste by reusing aggregate. Further investigations are requested to test the applicability of this method under the realistic conditions close to the actual waste.
Kawato, Yoshimi; Tomioka, Osamu; Takahashi, Kuniaki; Meguro, Yoshihiro; Sakamoto, Hiroyuki*; Haga, Kazuko*
JAEA-Technology 2010-013, 38 Pages, 2010/07
JAEA-Technology-2010-013.pdf:1.36MB
It is important to understand fundamental solidification characteristics of incinerated ashes of combustible and poorly combustible wastes generated by JAEA. Simulated solidified substances using incinerator fly ash were prepared under different conditions such as solidified materials, ash filling rates, amount of solidification retarders and so on. The compressive strength of the solidified substances prepared using a normal portland cement (OPC), a blast furnace slag cement (BB), and a low alkalinity cement (LAC) exceeded a standard value, 1.47 N/mm
. The compressive strength made from the BB was lower 1.47 N/mm when the filling rate of the incinerated ash was 40%. For the substances using the LAC, all the strengths were over 1.47 N/mm. Pb and Zn would behave as retardative substances for solidification. All substances showed the compressive strength with the BB or the LAC. As insolubilizers for heavy metals, ferrous sulfate and sodium sulfide prevented Cr from elution.
Chishiro, Etsuji; Kobayashi, Tetsuya; Yamazaki, Masayoshi*; Suzuki, Hiroyuki*; Hori, Toshihiko*; Sakamoto, Mitsunori*; Urakata, Hiroto*; Miyake, Setsuo*; Fukuda, Shigeki*; Anami, Shozo*
Proceedings of 21st International Linac Conference, p.455 - 457, 2003/00
In the lilac of the High-Intensity Proton Accelerator Facility, 972MHz klystrons are adopted as the RF source for the acceleration from 190MeV to 400MeV. The klystron is required the RF power of 2.5 MW to drive the ACS accelerator. A prototype klystron was produced, and was evaluated the RF characteristics at the test stand in the JAERI. At the first test, a saturation power of 2.1 MW was obtain on the cathode voltage of 104kV, and an unstable output power causing by a gun oscillation was observed.
Tanaka, Satoru*; Nagasaki, Shinya*; *; *; Muraoka, Susumu; *; *; *; *; *; et al.
Nihon Genshiryoku Gakkai-Shi, 39(12), p.1008 - 1018, 1997/00
Times Cited Count：3 Percentile：30.34(Nuclear Science & Technology)no abstracts in English
Tomioka, Osamu; Kawato, Yoshimi; Meguro, Yoshihiro; Haga, Kazuko*; Sakamoto, Hiroyuki*
no journal, ,
no abstracts in English
Haga, Kazuko*; Sakamoto, Hiroyuki*; Tomioka, Osamu; Kawato, Yoshimi; Meguro, Yoshihiro
no journal, ,
no abstracts in English
Akagi, Yosuke*; Shimoda, Satoko*; Kato, Hiroyasu*; Tachi, Yukio; Sakamoto, Hiroyuki*
no journal, ,
The Fukushima Dai-ichi Nuclear Power Plant accident has resulted in a large amount of radioactively contaminated concrete. As fundamental basis for developing the treatment and disposal concept for these wastes, migration behavior of radionuclides in concrete was investigated. Sorption and diffusion characteristics of tritiated water, cesium, iodine and uranium were measured at various conditions (concrete types, salinity, etc.).
Sakamoto, Hiroyuki*; Shimoda, Satoko*; Yamada, Kazuo*; Namihira, Takao*; Shigeishi, Mitsuhiro*; Tachi, Yukio
no journal, ,
The Fukushima Dai-ichi Nuclear Plant accident has resulted in a large amount of radioactively contaminated concrete. The possible application of the pulsed power discharge to reduce the amount of contaminated concrete debris as radioactive waste was investigated. This method could decontaminate and reduce the contaminated concrete wastes by separating contaminated matrix from uncontaminated coarse aggregate under pulsed power discharge process.
