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Journal Articles

Challenges for enhancing Fukushima environmental resilience, 4; Development of physical and heat treatment methods on aiming at decontamination, volume reduction and reuse of contaminated soil

Yaita, Tsuyoshi; Honda, Mitsunori; Shimoyama, Iwao; Ito, Kenichi*; Mampuku, Yuzo*; Tsuji, Takuya; Matsumura, Daiju

Nippon Genshiryoku Gakkai-Shi, 59(8), p.483 - 487, 2017/08

no abstracts in English

Journal Articles

Development of cesium-free mineralization for decontamination and reuse of radioactive contaminated soil in Fukushima

Shimoyama, Iwao; Honda, Mitsunori; Kogure, Toshihiro*; Baba, Yuji; Hirao, Norie*; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi

Photon Factory News, 35(1), p.17 - 22, 2017/05

We introduce Cs-free mineralization (CFM) for Cs removal and reuse of radioactive-contaminated soil in Fukushima and report recent work conducted in the BL27A beamline in Photon Factory. In this work, we investigated compositional and structural changes of Cs-sorbed weathered biotite (WB) before and after heating treatment with addition of NaCl-CaCl$$_{2}$$ salts under low-pressure condition, to study Cs desorption mechanism from clay minerals. X-ray fluorescence spectroscopy clarified that almost all Cs and K were removed with the salts at 700 $$^{circ}$$C. On the other hand, Ca increased with heating temperature. X-ray diffraction and transmission electron microscopy analysis clarified that phase transitions from WB to some Ca-rich silicate minerals, e.g., augite, were caused by the heating treatment with the salt. Based on these results, CFM is proposed for Cs removal utilizing the mechanism in which large monovalent cations are discharged with accompanying the phase transition. We also discuss the role of Cl in this reaction showing chemical bonding change of Cl observed using X-ray absorption spectroscopy in the early stage of the chemical reaction.

Journal Articles

Root endophytic bacteria of a $$^{137}$$Cs and Mn accumulator plant, ${{it Eleutherococcus sciadophylloides}}$, increase $$^{137}$$Cs and Mn desorption in the soil

Yamaji, Keiko*; Nagata, Satoshi*; Haruma, Toshikatsu*; Onuki, Toshihiko; Kozaki, Tamotsu*; Watanabe, Naoko*; Namba, Kenji*

Journal of Environmental Radioactivity, 153, p.112 - 119, 2016/03

 Times Cited Count:8 Percentile:45.8(Environmental Sciences)

Of the 463 strains that we isolated, 107 (23.1%) produced the siderophores. We found $$^{137}$$Cs and Mn desorption concomitant with Al and Fe desorption. These results suggest that root endophytes of $$^{137}$$Cs accumulator plant produce siderophores, resulting in the desorption of $$^{137}$$Cs from the contaminated soil collected at Fukushima, Japan.

Journal Articles

Demonstrative experiments on the migration of radiocesium from buried soil contaminated by the accident at Fukushima Daiichi Nuclear Power Station

Yamaguchi, Tetsuji; Shimada, Taro; Ishibashi, Makoto*; Akagi, Yosuke*; Kurosawa, Mitsuru*; Matsubara, Akiyoshi*; Matsuda, Yuki*; Sato, Shigeyoshi*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 22(2), p.21 - 28, 2015/12

It is predictable from previous studies that radiocesium hardly migrate into surrounding soils and groundwater from soils contaminated by the Fukushima Daiichi Nuclear Power Plant accident if they are buried and covered with indigenous soils. This study demonstrated the prediction by performing in-situ migration experiments over a year in a public park in Miho, Ibaraki prefecture and in two public parks in Misato, Saitama prefecture. Contaminated soils were buried at a depth range of 0.3 - 1.0 m or at 0.3 - 1.3 m and covered with indigenous soil layer of 0.3 m, and were sprinkled with water to accelerate the radiocesium migration. Migration of radiocesium was not observed from radiometric analyses of boring cores and soil water samples. Laboratory column and sorption experiments revealed that the radiocesium hardly leach out of the soil and even if they leach out from the contaminated soil, radiocesium is sorbed on surrounding soils and hardly migrate through the soli layer. Simulation of Cs-137 migration for 100 years by an advection-diffusion model showed that Cs-137 hardly migrate and decay out in the contaminated soil.

Journal Articles

Determination of environmental Pu-241 using liquid scintillation counting techniques

Amano, Hikaru; Watanabe, Miki*

The 5th Low Level Counting Conf. using Liquid Scintillation Analysis, 0, p.86 - 91, 1996/00

no abstracts in English

JAEA Reports

Radionuclide migration behavior at the low adsorption region on the aerated soil testing, the second report; Effect of inflow volume and migration analysis

Takebe, Shinichi; Mukai, Masayuki; Komiya, Tomokazu; Kamiyama, Hideo

JAERI-M 93-034, 15 Pages, 1993/02

JAERI-M-93-034.pdf:0.74MB

no abstracts in English

JAEA Reports

Radionuclide migration behavior at the low adsorption region on the aerated soil testing

Takebe, Shinichi; Mukai, Masayuki; Komiya, Tomokazu; Kamiyama, Hideo

JAERI-M 92-205, 19 Pages, 1993/01

JAERI-M-92-205.pdf:0.77MB

no abstracts in English

Oral presentation

Estimation of radioactive surface contamination on work clothing due to soil adhesion during decontamination activities

Tsujimura, Norio; Yoshida, Tadayoshi; Hoshi, Katsuya

no journal, , 

no abstracts in English

Oral presentation

Development of cesium-free mineralization for volume reduction and reuse of radioactive contaminated soil

Shimoyama, Iwao; Honda, Mitsunori; Kogure, Toshihiro*; Baba, Yuji; Hirao, Norie*; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi

no journal, , 

The decontamination method has not been established for soil contaminated with radioactive Cs. We adopted weathered biotite (WB) which sorbed non-radioactive $$^{133}$$Cs as a model contaminated soil and applied heating treatment to the WB at 700$$^{circ}$$C under a low pressure condition with CaCl$$_{2}$$ or KCl salt. X-ray fluorescence analysis showed that almost all Cs was removed after the heating at 700$$^{circ}$$C with CaCl$$_{2}$$ and Ca became dominant with temperature. X-ray diffraction and transmission electron microscopy analysis indicated some phase transition from WB after the heating treatment. These results suggest a model that Ca derived from the salt induced the formation of augite, and that Cs$$^{+}$$ were eliminated from the product as these large-size cations cannot constitute augite. Based on this model, we propose Cs free mineralization which can achieve decontamination and reuse of soil in Fukushima.

Oral presentation

Cs removal from weathered biotite in Fukushima by Cs free mineralization and influence of low pressure environment

Shimoyama, Iwao; Honda, Mitsunori; Kogure, Toshihiro*; Baba, Yuji; Okamoto, Yoshihiro; Chiba, Noriaki; Yaita, Tsuyoshi; Suzuki, Shinichi

no journal, , 

We have found that Cs can be largely removed from weathered biotite (WB) in Fukushima by low-pressure heating treatment with some alkaline salts, but the detail of the mechanism is still unclear. We analyze compositional and structural change of WB using XRF, XRD, TEM, and NEXAFS. NaCl-CaCl$$_{2}$$ mixed salt and WB were mixed in a weight ratio of 1/1 and heated in a low-pressure condition. Excess salt in the sample was removed by rinsing with distilled water. Cs/Si ratio decreased to 11% and 0 % by the treatment at 600$$^{circ}$$C and 700$$^{circ}$$C, respectively. We found decrease of K with Cs. Meanwhile, Ca and Cl increased with temperature. XRD analysis clarified that new peaks appeared above 500$$^{circ}$$C and peaks of WB disappeared at 700$$^{circ}$$C. TEM analysis clarified that augite and wadalite were dominant products after the heating treatment. NEXAFS analysis clarified that Ca and Cl have different chemical bonding depending on atmospheric and low pressures. Based on these results, we propose Cs free mineralization for decontamination of soil in Fukushima.

Oral presentation

Effect of CaCl$$_{2}$$ and KCl additives on soil decontamination by cesium-free mineralization

Shimoyama, Iwao; Honda, Mitsunori; Kogure, Toshihiro*; Baba, Yuji; Yaita, Tsuyoshi; Okamoto, Yoshihiro

no journal, , 

We examined decontamination of radioactively contaminated soil in Fukushima using cesium free mineralization (CFM) with CaCl$$_{2}$$ or KCl additives. We analyzed radioactive concentration and structural changes of the samples using a NaI detector and an X-ray diffractometer. In the case of CaCl$$_{2}$$, decontamination ratio R$$_{d}$$ showed similar tendency for both air and low-pressure heating, and R$$_{d}$$ reached to 97% after heating at 790$$^{circ}$$C. X-ray diffraction (XRD) showed that transformation from clay minerals to other silicate minerals occurred by the heat treatments and products depend on the pressure condition during the heating. In the case of KCl, R$$_{d}$$ was higher for low-pressure heating than for air heating and reached to 83% at 790$$^{circ}$$C. XRD showed that clay minerals remained after the heating treatment. These results indicate that CFM is effective for decontamination of actual Fukushima soil and different mechanisms of Cs removal from contaminated soil exist for heating treatments with KCl and CaCl$$_{2}$$.

Oral presentation

Decontamination of radioactive soil by cesium-free mineralization process

Kogure, Toshihiro*; Shimoyama, Iwao; Honda, Mitsunori; Baba, Yuji; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi

no journal, , 

no abstracts in English

12 (Records 1-12 displayed on this page)
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