Corrosion rate of zircaloy-4 in deoxidized deionized water at 80-120C

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

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

https://doi.org/10.3327/taesj.J12.026

no abstracts in English

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, 10M, labeled with I, at controlled pH by boric acid-sodium hydroxide buffer, were -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 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.

Experiments on the release of gaseous iodine from -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

https://doi.org/10.3327/jnst.47.229

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 -irradiated (kGy/h, 2h) cesium iodide aqueous solution (1E-4M) containing methyl-isobuthyl-ketone (MIBK) was measured. The solution was buffered at pH7. 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.

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.

Corrosion behavior of zircaloy in deionized water at around 100C under anaerobic condition

Chiba, Noriaki; Maeda, Toshikatsu; Yamaguchi, Tetsuji

no journal, , 

no abstracts in English

Comparison between the hydrogen gas generation rate method and the weight gain measurement method through corrosion experiments of zircaloy at 180C

Chiba, Noriaki; Maeda, Toshikatsu; Yamaguchi, Tetsuji

no journal, , 

no abstracts in English

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 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 600C and 700C, respectively. We found decrease of K with Cs. Meanwhile, Ca and Cl increased with temperature. XRD analysis clarified that new peaks appeared above 500C and peaks of WB disappeared at 700C. 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.