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Uehara, Akihiro*; Akiyama, Daisuke*; Ikeda, Atsushi; Numako, Chiya*; Terada, Yasuko*; Nitta, Kiyofumi*; Ina, Toshiaki*; Takeda-Homma, Shino*; Kirishima, Akira*; Sato, Nobuaki*
Journal of Nuclear Materials, 559, p.153422_1 - 153422_11, 2022/02
Times Cited Count：3 Percentile：50.96(Materials Science, Multidisciplinary)Sudo, Ayako; Takano, Masahide; Watanabe, Daisuke*
no journal, ,
The simulated wastes, which simulates the completely melted state near the melting front between molten corium and concrete, were prepared and provided for the fluorination tests. As simulated wastes, (U,Zr)O
, Zr, SUS316L, GdO
, and concrete powders were pressed into tablets. The tablets with two compositions with varying Zr metal content were prepared (Zr-rich reducing condition: sample A and Zr-lower oxidizing condition: sample B). The tablets were melted and solidified by arc melting method. Cross-sections of solidified samples were observed and elemental analyzed. The cross-sectional image of sample A showed white metal and gray oxide. The main component of oxide was (U,Zr)O, where a small amount of Ca, Al, and Gd dissolved. As for metal, a part of Si, U, and Al were reduced from oxide materials and consequently rodlike (Fe,Cr,Ni)-Si-Zr and (Fe,Cr,Ni)-Si-Al-Mo-(Zr,U) alloy phase were observed. On the other hand, oxide of sample B showed that (U,Zr)O was precipitated in the silicate glass phase. As for metal, an alloy phase that has Cr,Fe-lower SUS component was observed because all of Zr and a part of Cr and Fe were oxidized. The phase relationships during MCCI is considered to be significantly affected by Zr metal content in metallic melt.
-Zr-SS systemAkiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Sasaki, Takayuki*; Watanabe, Masayuki; Kumagai, Yuta; Kusaka, Ryoji
no journal, ,
In the accident at TEPCO's Fukushima Daiichi Nuclear Power Station, it is considered that the molten fuel reacted with zircaloy of the cladding tube and alloys containing iron as the main component, such as stainless steel, at high temperatures to generate fuel debris. For the removal, processing, and disposal of the debris in the future, it will be important to predict the properties of the debris. Therefore, in this study, simulated fuel debris containing Zr or ZrO and the constituent elements of stainless steel was prepared, and structural analysis was performed using XRD and SEM-EDX. We also evaluated the solid phase state after immersing the simulated debris in pure water or seawater.
Takano, Masahide; Sudo, Ayako; Watanabe, Daisuke*
no journal, ,
To provide specimens for the fluorination experiment, the simulated MCCI product was prepared from core materials placed on a concrete piece by light-concentrating heating technique under temperature gradient. As a result of analysis on the cross-section, we confirmed that (1) (U, Zr)O contained small amount of Fe, Cr, Ca and Al, (2) Cr and most part of Fe in stainless steel were oxidized by dehydration of concrete to precipitate as FeCrO
spinel in the silicate glass.
Oba, Hironori; Akaoka, Katsuaki; Wakaida, Ikuo
no journal, ,
no abstracts in English
Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Wakaida, Ikuo; Tamura, Koji*; Nakanishi, Ryuzo*; Sakamoto, Kan*; Taira, Takunori*
no journal, ,
Development of remote inspection and elemental analysis methods in a harsh radiation environment is required, such as inspection of the nuclear fuel debris at the bottom of the post-accident nuclear reactor (Tokyo Electric Power Company, Fukushima Daiichi Nuclear Power Plant). Laser-induced breakdown spectroscopy (LIBS) has been utilized as an effective qualitative and quantitative analytical method for elemental analysis. Inspecting the damaged reactor vessels requires a longer fiber-optic (FO) cable, which significantly attenuates the delivered laser energy by absorption and scattering in the fiber. We report on the first trial of our FO-LIBS system using the microchip laser (MCL) to identify and quantify elements in surrogate nuclear fuel debris under gamma irradiation, the results of trials on surrogate debris analysis, containing uranium oxide, using the MCL, and the results of 100 m-long fiber-delivered LIBS.
Batsaikhan, M.; Oba, Hironori; Wakaida, Ikuo
no journal, ,
Oba, Hironori; Akaoka, Katsuaki; Karino, Takahiro; Wakaida, Ikuo; Ouchi, Atsushi*; Miura, Yusuke*; Eto, Yoshinori*; Sakamoto, Kan*
no journal, ,
no abstracts in English
