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Journal Articles

Corrosion rate of zircaloy-4 in deoxidized deionized water at 80-120$$^{circ}$$C

Maeda, Toshikatsu; Chiba, Noriaki; Tateishi, Tsuyoshi*; Yamaguchi, Tetsuji

Nihon Genshiryoku Gakkai Wabun Rombunshi, 12(2), p.158 - 164, 2013/06

no abstracts in English

Journal Articles

Laser therapy for twin-to-twin transfusion syndrome; Today and near-future

Yamashita, Hiromasa*; Oka, Kiyoshi; Yamanaka, Noriaki*; Seki, Takeshi; Kim, K.*; Kuwana, Kenta*; Masamune, Ken*; Naganawa, Akihiro*; Dohi, Takeyoshi*; Chiba, Toshio*

Nihon Reza Igakkai-Shi, 33(2), p.122 - 130, 2012/08

no abstracts in English

JAEA Reports

Experiment on the gaseous iodine release from irradiated cesium iodide solutions (Contract research)

Moriyama, Kiyofumi; Tashiro, Shinsuke; Chiba, Noriaki; Maruyama, Yu; Nakamura, Hideo; Watanabe, Atsushi*

JAEA-Research 2011-016, 125 Pages, 2011/06

JAEA-Research-2011-016.pdf:2.71MB

The volatile iodine production due to radiation chemical effects in the containment vessel of light water reactors (LWRs) during severe accidents was investigated by experiments in small scale and with well controlled conditions. Cesium iodide solutions, 10$$^{-4}$$M, labeled with $$^{131}$$I, at controlled pH by boric acid-sodium hydroxide buffer, were $$gamma$$-irradiated and swept with a constant gas flow rate. The gaseous iodine released from the solution was collected by species selective filters and quantified separately for I$$_2$$ and organic iodines. The influences of pH, temperature, inorganic and organic impurities, oxygen and hydrogen concentrations in the cover gas on the iodine release behavior were examined. Data including time dependent gaseous iodine release fractions, comparison of the final iodine release fractions in terms of the parameter effects, as well as the initial, boundary and interface conditions necessary for simulating the experiments by computer codes are provided.

Journal Articles

Experiment and modeling for solvent leaching from paint matrix considering equilibrium

Moriyama, Kiyofumi; Chiba, Noriaki; Tashiro, Shinsuke; Maruyama, Yu; Nakamura, Hideo; Watanabe, Atsushi*

Journal of Nuclear Science and Technology, 48(6), p.885 - 891, 2011/06

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The leach of remaining solvent in an epoxy paint coating when it is submerged in water was experimentally studied. A leach kinetics model considering the equilibrium of the solvent concentration in the paint matrix and in water was developed. Three model parameters, equilibrium constant $$K$$, leaching rate $$k_d$$, and initial concentration of the solvent in the paint $$C_p^0$$ were evaluated based on the experimental results, and empirical correlation equations for them were obtained. The model showed good qualitative and quantitative agreement with the observed evolution of the leached solvent mass in the present experiment. Also the model showed consistency with experimental data by Ball et al. (2003).

Journal Articles

Experiments on the release of gaseous iodine from $$gamma$$-irradiated aqueous CsI solution and influence of oxygen and Methyl Isobutyl Ketone (MIBK)

Moriyama, Kiyofumi; Tashiro, Shinsuke; Chiba, Noriaki; Hirayama, Fumio*; Maruyama, Yu; Nakamura, Hideo; Watanabe, Atsushi*

Journal of Nuclear Science and Technology, 47(3), p.229 - 237, 2010/03

 Times Cited Count:13 Percentile:69.89(Nuclear Science & Technology)

The volatile iodine production due to radiation chemistry is an important uncertainty source in the source term evaluation for LWRs. The gaseous release of molecular iodine and organic iodine from $$gamma$$-irradiated ($$sim 7$$kGy/h, 2h) cesium iodide aqueous solution (1E-4M) containing methyl-isobuthyl-ketone (MIBK) was measured. The solution was buffered at pH$$sim$$7. The concentration of MIBK (up to 1E-3M) and oxygen were changed as parameters. The total iodine release fraction and the fraction released as organic iodine were 2-47% and 0.02-1.5%, respectively, at the end of the irradiation. With the same cover gas condition, the total iodine release decreased and the organic iodine release increased when the MIBK concentration increased. This behavior can be explained by branching of the reaction path of organic degradation depending on availability of dissolved oxygen and competition between iodine and organic compounds on the consumption of radicals.

Oral presentation

Source term evaluation in containment vessel during late phase of severe accident, 12; Experiments on iodine chemistry under irradiation, 3

Moriyama, Kiyofumi; Tashiro, Shinsuke; Chiba, Noriaki; Nakamura, Hideo; Nakamura, Koichi*

no journal, , 

Experiments were performed to measure the gaseous iodine release from aqueous CsI solution irradiated by Co-60 $$gamma$$-ray, to clarify the gaseous iodine behavior in the containment of light water reactors during severe accidents (SA). The influence of organic compounds with various oxygen concentrations in the gas phase were examined with pH$$sim$$7 at room temperature.

Oral presentation

Source term evaluation in containment vessel during late phase of severe accident, 18; Experiment on organic leach from paint in the containment vessel

Moriyama, Kiyofumi; Chiba, Noriaki; Tashiro, Shinsuke; Nakamura, Hideo; Nakamura, Koichi*

no journal, , 

Regarding the organic iodine production during a severe accident of light water reactors, the organic solvent leaching from paints has drawn attention as an important organic source. We measured the amount of organic solvent leaching from epoxy paint as time series data and examined its dependence on temperature, paint thickness and age. We developed also a leach behavior model considering equilibrium between the concentrations in the paint matrix and in the solution.

Oral presentation

Source term evaluation in containment vessel during late phase of severe accident, 20; Modeling of organic iodide production in the containment

Moriyama, Kiyofumi; Chiba, Noriaki; Tashiro, Shinsuke; Nakamura, Hideo; Nakamura, Koichi*

no journal, , 

no abstracts in English

Oral presentation

Corrosion behavior of zircaloy in deionized water at around 100$$^{circ}$$C under anaerobic condition

Chiba, Noriaki; Maeda, Toshikatsu; Yamaguchi, Tetsuji

no journal, , 

no abstracts in English

Oral presentation

Corrosion behavior of zircaloy at low temperature

Chiba, Noriaki; Maeda, Toshikatsu; Yamaguchi, Tetsuji

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Corrosion experiments of zircaloy-4 at 100$$^{circ}$$C; Study on corrosion mechanisms using isotope effects in hydrogen generation process

Chiba, Noriaki; Yamaguchi, Tetsuji; Maeda, Toshikatsu

no journal, , 

no abstracts in English

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.

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