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Usui, Takahiro*; Sawada, Akihiko; Amaya, Masaki; Suzuki, Akihiro*; Chikada, Takumi*; Terai, Takayuki*
Journal of Nuclear Science and Technology, 52(10), p.1318 - 1322, 2015/10
Times Cited Count：48 Percentile：97.39(Nuclear Science & Technology)SiC coating is one of countermeasures for the prevention of oxidation and hydrogen embrittlement of fuel claddings because SiC has high resistance of oxidation and hydrogen permeation. Hydrogen permeation and oxidation experiments for the cladding materials with SiC coatings were conducted in unirradiated conditions. The sputtering method was employed to make SiC coatings. In the hydrogen permeation experiment, SUS316 was used as a base material of the coating. SUS316 with SiC coatings showed hydrogen permeation reduction by one order of magnitude. In the oxidation experiments, Zry-4 and SUS316 were used as base materials of the coatings. The weight gain of the Zry-4 specimens with a SiC coating decreased by about one-fifth compared to the uncoated ones. This phenomenon was observed for SUS316 at 750 
C as well. The peel-off of the coating was observed in some experiments, and it is considered that the peel-off was caused by the difference of the thermal expansions between coatings and base materials. Thicker coatings showed better oxidation resistance, but thinner coatings showed more tolerance of peel-off.
Tokushima, Kazuyuki; Shibata, Hiroki; Kurata, Masaki; Sawada, Akihiko*; Sakamoto, Kan*
Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2015), Conference Proceedings, Poster (Internet), p.478 - 485, 2015/00
Two type tests were performed to examine the prevention effect of the oxide layers to liquefaction interaction between Zircaloy and core component materials. The oxide layer of Zircaloy was clearly confirmed to prevent the liquefaction interaction under the temperature of melting point of stainless steel even if the oxide layer on Zircaloy of approximately 30 micro meters, which is thinner than it is predicted to be formed under typical accident condition. The oxide layers were able to be formed even in the region where the gas flow is significantly limited by narrow arrangement. Although the oxide layers at the inner position of upper end plug was hard to form, the prevention effect of the oxide layers was sufficiently observed. The axial variation of the thickness of the oxide layers was observed. It suggested that variation of partial pressure of H
O should be considered to evaluate the growth rate of the oxide layers for detail.
Kim, J.*; Fujiwara, Akihiko*; Sawada, Tomohiro*; Kim, Y.*; Sugimoto, Kunihisa*; Kato, Kenichi*; Tanaka, Hiroshi*; Ishikado, Motoyuki*; Shamoto, Shinichi; Takata, Masaki*
IUCrJ, 1(3), p.155 - 159, 2014/05
Times Cited Count：2 Percentile：21.49(Chemistry, Multidisciplinary)Using a charge density analysis based on synchrotron radiation X-ray powder diffraction data, we found that the charge carriers only accumulated in the iron layer of the superconducting phase of LaFeAsO
F
at low temperatures. Analysis of the electrostatic potential distribution revealed the concerted enhancement of the electronic polarization of the As ions and the carrier redistribution.
Sawada, Akihiko; Amaya, Masaki
no journal, ,
no abstracts in English
Usui, Takahiro; Sawada, Akihiko; Amaya, Masaki; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Coating on cladding material is one of the candidate as "Accident Toralent Fuel". In this study, SiC coating was fabricated on SUS316 substrate and performed oxdation experiment under LOCA condition. Oxidation of iron decreased in the specimen with coating. The specimen coated for 1 hour showed the best integrity of oxidation.
Usui, Takahiro*; Sawada, Akihiko; Amaya, Masaki; Suzuki, Akihiro*; Chikada, Takumi*; Terai, Takayuki*
no journal, ,
SiC coatings were fabricated on SUS316 and Zircaloy-4 substrate. Hydrogen permeation experiment and oxidation experiment were performed. From hydrogen permeation experiment to SiC coated specimen on SUS316 subsrate, permeability of specimen was smaller in one order in magnitude than that of uncoated. From oxidation experiment on Zircaloy-4 substrate, weight gain and thickness of oxide film decreased. Specimens with thicker coating has less weight gain than that with thinner coating, however, thicker coating was peeled off more than thinner coating after oxidized in 1200C.
