The Kinetics and mechanism of HO decomposition at the UO surface in bicarbonate solution

McGrady, J.; Kumagai, Yuta; Watanabe, Masayuki; Kirishima, Akira*; Akiyama, Daisuke*; Kitamura, Akira; Kimuro, Shingo

RSC Advances (Internet), 11(46), p.28940 - 28948, 2021/08

https://doi.org/10.1039/D1RA05580A

Upgrade in catalytic activity of hydrophobic platinum catalysts by irradiation with electron beams

Iwai, Yasunori

Fusion Engineering and Design, 98-99, p.1796 - 1799, 2015/10

https://doi.org/10.1016/j.fusengdes.2015.03.024

Hydrophobic platinum catalysts have been widely applied in the field of nuclear fusion for the exchange reactions of hydrogen isotopes between hydrogen and vapor in the water detritiation system, and for the oxidation of tritium on the atmospheric detritiation system. Hydrophobic platinum catalysts are hardly susceptible to water mist and water vapor. Hydrophobic platinum catalysts are produced by supporting platinum directly on hydrophobic polymer beads. For the hydrophobic polymer, styrene - divinyl benzene (SDB) has been applied in Japan. It can be pointed out that the upgrade in catalytic activity of hydrophobic catalyst is expected to downsize the catalytic reactor based on a hard look at a large increase in flow rate in future. The upgrade in catalytic activity of two types of commercial Pt/SDB catalysts was found when they were irradiated with electron beams. After irradiation with electron beams, the catalytic activity was evaluated by means of overall reaction rate constant for the oxidation of tritium. The overall reaction rate constant increased as increase in dose. The constant showed the peak value in the dose between 500 to 1000 kGy. After the peak, the constant decreased as increase in dose. The overall reaction rate constant at the peak was 6 times larger than that evaluated with unirradiated. The mechanical strength of irradiated Pt/SDB kept sound until 1500 kGy. The irradiation is a promising method to the upgrading in catalytic activity of Pt/SDB catalyst.

Actively controlled oxidation of Cu{001} with hyperthermal O molecular beam

Okada, Michio*; Moritani, Kosuke; Goto, Seishiro*; Kasai, Toshio*; Yoshigoe, Akitaka; Teraoka, Yuden

Journal of Chemical Physics, 119(14), p.6994 - 6997, 2003/10

https://doi.org/10.1063/1.1615961

The oxidation of Cu(001) with hyperthermal O molecular beams was investigated using X-ray photoemission spectroscopy in conjunction with a synchrotron light source. The efficiency of oxidation is higher than that with ambient thermal O. Further oxidation under oxygen coverage larger than 0.5 ML occurs rather inefficiently even for the 2.3 eV beam irradiation. We found such slow oxidation of Cu corresponding to the initial stage of the CuO formation can be interpreted in terms of a collision-induced-adsorption mechanism. The kinetics of the dissociative adsorption is well described using the first order kinetics in a simple Langmuir-type adsorption model.

Development of simulation code for MOX dissolution using silver-mediated electrochemical method (Contract research)

Kida, Takashi; Umeda, Miki; Sugikawa, Susumu

JAERI-Data/Code 2003-001, 29 Pages, 2003/03

JAERI-Data-Code-2003-001.pdf:6.34MB

MOX dissolution using silver-mediated electrochemical method will be employed for the preparation of plutonium nitrate solution in the criticality safety experiments in NUCEF. A simulation code for the MOX dissolution has been developed for the operating support. In this report an outline of the simulation code is proposed and a comparison with the experimental data and a parameter study on the MOX dissolution rate are described.The principle of this code is based on Zundelevich's model for PuO dissolution using Ag. The influence of nitrous acid on the material balance of Ag and the surface area of MOX powder on the basis of particle size distribution are taken into consideration in this model. A comparison with experimental data was carried out to confirm a validity of this model. It was confirmed that the behavior of MOX dissolution could adequately be simulated using the appropriate MOX dissolution rate constant. The parameters affecting the dissolution rate were studied, it was found that MOX particle size was major governing factor on the dissolution rate.

analysis using high resolution synchrotron radiation photoemission spectroscopy for initial oxidation of HO pre-adsorbed Si(001) surfaces induced by supersonic O molecular beams at room temperature

Yoshigoe, Akitaka; Teraoka, Yuden

Atomic Collision Research in Japan, No.28, p.105 - 107, 2002/00

The oxidation states up to Si states were formed when the translational kinetic energy of O was 3.0 eV. The time evolustions of each Si oxidation states were in situ measured by using the high resolution photoemission spectroscopy.The translational kinetic energy of 3.0eV randomly enhanced the oxidation on Si(001) surface up to the second layer Si backbonds. It was found that the Si was not observed, thus the dimer Si atoms at the top layer was not surrounded by four oxygen atoms at the initial oxidation stage.

Oxidation behavior of nuclear graphite and the improvement of corrosion resistance and thermal shock resistance of graphite materials by compositionally graded SiC coating

Fujii, Kimio

JAERI-Research 99-050, 99 Pages, 1999/08

JAERI-Research-99-050.pdf:5.37MB

no abstracts in English

Radiation Chemical Studies on the Treatment of Water

; ; ;

JAERI 1281, 36 Pages, 1982/10

JAERI-1281.pdf:0.97MB

no abstracts in English

Extent of Oxide Layer at the Inner Surface of Burst Cladding

; ; ; ;

JAERI-M 9475, 22 Pages, 1981/05

JAERI-M-9475.pdf:0.99MB

no abstracts in English

Zircaloy-System Reaction and Related Embrittlement for Zircaloy Cladding under a Simulated Loss-of Coolant Accident

; ; ;

JAERI-M 6601, 26 Pages, 1976/06

JAERI-M-6601.pdf:1.75MB

no abstracts in English

Application of thermodynamics for oxidation of Fe-Cr alloy in humid environment at a high temperature

Serizawa, Hiroyuki; Osawa, Takahito; Oishi, Yuji*; Nemoto, Yoshiyuki; Kondo, Keietsu; Shohoji, Nobumitsu*; Kaji, Yoshiyuki

no journal, , 

A new reaction model for evaluating the activity of oxygen and hydrogen atoms of HO molecules is proposed. The surprisingly high value of the activity implies that the production process of volatile metal hydroxides might be reconsidered.