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Journal Articles

Preventing nuclear fuel material adhesion on glove box components using nanoparticle coating

Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Tachihara, Joji; Takato, Kiyoto; Okita, Takatoshi; Satone, Hiroshi*; Suzuki, Michitaka*

Mechanical Engineering Journal (Internet), 8(3), p.21-00022_1 - 21-00022_9, 2021/06

https://doi.org/10.1299/mej.21-00022

To reduce the hold-up of the nuclear fuel materials in the glove box and the external exposure dose, the technology of the MOX powder adhesion prevention by the nanoparticle coating to the acrylic panels of the glove box has been developed. The surface analysis by means of atomic force microscopy (AFM) showed that the acrylic test piece surface coated with nanoparticles had a higher root mean square roughness value than that non-coated with nanoparticles. Due to the formation of nano-sized tiny rugged surface, the nanoparticle coating reduced the minimum adhesion force between the UO $_{2}$ particles and the acrylic test piece surface with the smallest particle size of about 5 m where desorption was observed, by about one-tenth. Moreover, the nanoparticle coating reduced the amount of the MOX powder adhering to the acrylic test piece to about one-tenth. In this study, it was found that applying the nanoparticle coating to the acrylic panels of glove box can prevent the adhesion of nuclear fuel materials. This method is effective for reducing the hold-up of the nuclear fuel materials in the glove box, the external exposure dose and improving the visibility of the acrylic panels.

Journal Articles

Preventing nuclear fuel material adhesion on glove box components using nanoparticle coating

Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Suzuki, Masahiro; Tachihara, Joji; Takato, Kiyoto; Okita, Takatoshi; Satone, Hiroshi*; Suzuki, Michitaka*

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

https://doi.org/10.1115/ICONE2020-16215

To reduce the hold-up of the nuclear fuel materials in the glove box and the external exposure dose, the technology of the MOX powder adhesion prevention by the nanoparticle coating to the acrylic panels of the glove box has been developed. Due to the formation of nano-sized tiny rugged surface, the nanoparticle coating reduced the minimum adhesion force between the UO $_{2}$ particles and the acrylic test piece surface with the smallest particle size of about 5 m where desorption was observed, by about one-tenth. Moreover, the nanoparticle coating reduced the amount of the MOX powder adhering to the acrylic test piece to about one-tenth. In this study, it was found that applying the nanoparticle coating to the acrylic panels of glove box can prevent the adhesion of nuclear fuel materials. This method is effective for reducing the hold-up of the nuclear fuel materials in the glove box, the external exposure dose and improving the visibility of the acrylic panels.

Journal Articles

-radiation and H $_{2}$ O $_{2}$ induced oxidative dissolution of uranium(IV) oxide in aqueous solution containing phthalic acid

Kumagai, Yuta; Jonsson, M.*

Dalton Transactions (Internet), 49(6), p.1907 - 1914, 2020/02

https://doi.org/10.1039/c9dt03952j

Times Cited Count：0 Percentile：0.01(Chemistry, Inorganic & Nuclear)

This study aims to reveal possible involvements of organic acids in the oxidative dissolution of UO $_{2}$ . Using phthalic acid as a model compound, we have measured adsorption on UO $_{2}$ and investigated effects on the reaction between H $_{2}$ O $_{2}$ and UO $_{2}$ and on oxidative dissolution induced by -irradiation. Significant adsorption of phthalic acid was observed even at neutral pH. However, the reaction between H $_{2}$ O $_{2}$ and UO $_{2}$ in phthalic acid solution induced oxidative dissolution of U(VI) similarly to aqueous bicarbonate solution. These results indicate that even though phthalic acid adsorbs on the UO $_{2}$ surface, it is not involved in the interfacial reaction by H $_{2}$ O $_{2}$ . In contrast, the dissolution of U by irradiation was inhibited in aqueous phthalic acid solution, whereas H $_{2}$ O $_{2}$ generated by radiolysis was consumed by UO $_{2}$ . The inhibition suggests that radical species derived from phthalic acid was involved in the redox reaction process of UO $_{2}$ .

Journal Articles

Effect of H $_{2}$ O $_{2}$ concentration on oxidative dissolution of U $_{2}$ O

Kumagai, Yuta

Hoshasen Kagaku (Internet), (107), p.77 - 78, 2019/04

Reaction of hydrogen peroxide (H $_{2}$ O $_{2}$ ) with uranium dioxide (UO $_{2}$ ) oxidizes U(IV) to water-soluble U(VI). In the concept of direct geological disposal of spent nuclear fuel, this reaction is expected to induce dissolution of UO $_{2}$ matrix of the spent fuel. This study investigate effect of H $_{2}$ O $_{2}$ concentration on the kinetics and the yield of U(VI) dissolution of this reaction. A series of experiments of the reaction of H $_{2}$ O $_{2}$ with UO $_{2}$ powder dispersed in water has been carried out. The experimental results reveal that increase in the H $_{2}$ O $_{2}$ concentration slows down the reaction and decreases the yield of U(VI) dissolution. This observation suggests that a reaction intermediate is generated in the course of the H $_{2}$ O $_{2}$ reaction on the surface of UO $_{2}$ .

Journal Articles

Impact of stoichiometry on the mechanism and kinetics of oxidative dissolution of UO $_{2}$ induced by H $_{2}$ O $_{2}$ and -irradiation

Kumagai, Yuta; Fidalgo, A. B.*; Jonsson, M.*

Journal of Physical Chemistry C, 123(15), p.9919 - 9925, 2019/04

https://doi.org/10.1021/acs.jpcc.9b00862

Times Cited Count：19 Percentile：62.54(Chemistry, Physical)

Radiation-induced oxidative dissolution of uranium dioxide (UO $_{2}$ ) is one of the most important chemical processes of U driven by redox reactions. We have examined the effect of UO $_{2}$ stoichiometry on the oxidative dissolution of UO $_{2}$ induced by hydrogen peroxide (H $_{2}$ O $_{2}$ ) and -ray irradiation. By comparing the reaction kinetics of H $_{2}$ O $_{2}$ between stoichiometric UO $_{2.0}$ and hyper-stoichiometric UO $_{2.3}$ , we observed a significant difference in reaction speed and U dissolution kinetics. The stoichiometric UO $_{2.0}$ reacted with H $_{2}$ O $_{2}$ much faster than the hyper-stoichiometric UO $_{2.3}$ . The U dissolution from UO $_{2.0}$ was initially much lower than that from UO $_{2.3}$ , but gradually increased as the oxidation by H $_{2}$ O $_{2}$ proceeded. The -ray irradiation induced the U dissolution that is analogous to the kinetics by the exposure to a low concentration (0.2 mM) of H $_{2}$ O $_{2}$ . The exposure to higher H $_{2}$ O $_{2}$ concentrations caused lower U dissolution and resulted in deviation from the U dissolution behavior by -ray irradiation.

Journal Articles

The Role of surface-bound hydroxyl radicals in the reaction between H $_{2}$ O $_{2}$ and UO $_{2}$

Fidalgo, A. B.*; Kumagai, Yuta; Jonsson, M.*

Journal of Coordination Chemistry, 71(11-13), p.1799 - 1807, 2018/07

https://doi.org/10.1080/00958972.2018.1466287

Times Cited Count：29 Percentile：88.5(Chemistry, Inorganic & Nuclear)

In this work, we have studied the reaction between H $_{2}$ O $_{2}$ and UO $_{2}$ with particular focus on the nature of the hydroxyl radical formed as an intermediate. Experiments were performed to study the kinetics of the reaction at different initial H $_{2}$ O $_{2}$ concentrations. The results show that the consumption rates at a given H $_{2}$ O $_{2}$ concentration are different depending on the initial H $_{2}$ O $_{2}$ concentration. This is attributed to an alteration of the reactive interface, likely caused by blocking of surface sites by oxidized U/surface-bound hydroxyl radicals. The U dissolution yield decreases with increasing initial H $_{2}$ O $_{2}$ concentration. This is expected from the mechanism of catalytic decomposition of H $_{2}$ O $_{2}$ on oxide surfaces. As the experiments were performed in solutions containing 10 mM and a strong concentration dependence was observed in the 0.2 - 2.0 mM H $_{2}$ O $_{2}$ concentration range, we conclude that the intermediate hydroxyl radical is surface bound rather than free.

JAEA Reports

SIMMER-III Analytic Equation-of-State Model

Morita, Koji; Tobita, Yoshiharu; kondo, Satoru; E.A.Fischer*

JNC TN9400 2000-005, 57 Pages, 1999/05

JNC-TN9400-2000-005.pdf:2.92MB

An improved analytic equation-of-state (EOS) model using flexible thermodynamic functions is developed for a reactor safety analysis code, SIMMER-III. The present EOS model is designed to have adequate accuracy in describing thermodynamic properties of reactor-core materials over wide temperature and pressure ranges and to consistently satisfy basic thermodynamic relationships without deterioration of the computing efficiency. The fluid-dynamic algorithm for pressure iteration consistently coupled with the EOS model is also described in the present report. The EOS data of the basic core materials, uranium dioxide, mixed-oxide fuel, stainless steel, and sodium, are developed up to the critical point by compiling the most up-to-date and reliable sources using basic thermodynamic relationships. The thermodynamic consistency and accuracy of the evaluated EOS data are also discussed by comparison with the available sources.

JAEA Reports

SIMMER-III Analytic Thermophysical Property Model

Morita, Koji; Tobita, Yoshiharu; kondo, Satoru; E.A.Fischer*

JNC TN9400 2000-004, 38 Pages, 1999/05

JNC-TN9400-2000-004.pdf:1.11MB

An analytic thermophysical property model using general function forms is developed for a reactor safety analysis code, SIMMER-III. The function forms arc designed to represent correct behavior of properties of reactor-core materials over wide temperature ranges, especially for the thermal conductivity and the viscosity near the critical point. The most up-to-date and reliable sources for uranium dioxide, mixed-oxide fuel, stainless stee1, and sodium available at present are used to determine parameters in the proposed functions. This model is also designed to be consistent with a SIMMER-III model on thermodynamic properties and equations of state for reactor-corc materials.

JAEA Reports