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Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 18(3), p.111 - 118, 2019/08
Cooling rate of molten core materials during solidification significantly affects the segregation of major constituents of fuel debris. To understand general tendency of the segregation, liquefaction/solidification tests of simulated corium (UO
, ZrO, FeO, B
C and sim-FP oxides) were performed. Simulated corium was heated up to 2600
C under Ar atmosphere and then cooled down with two different cooling processes; furnace cooling (average cooling rate is approximately 744C/min) and slow cooling (cooling rate in 2600C
2300C is 5C/min and in 2300C1120C is approximately 788C/min). Element analysis detected three oxide phases with different composition and one metal phase in both solidified samples. Solubility of FeO in these oxide phases was mostly fixed to be 12
5at% in both samples, which is in reasonable accordance with the value estimated from UO-ZrO-FeO phase diagrams. However, a significant grain-growth of one oxide phase, rich in Zr-oxide, was detected only in the slowly cooled sample. The composition of this particular oxide phase is comparable to the initial average composition. The condensation is considered to be caused by the connection of remaining liquid agglomerates during slow solidification.
Morihira, Masayuki; Mizusako, Fumiki*; Tsuboi, Yasushi*
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 6 Pages, 2011/12
Cladding inner corrosion is one of the life controlling factors of FBR MOX fuels and it depends on the oxygen potential in a fuel element. Oxygen potential increases with extension of burn-up due to the cumulated excess oxygen during fission. The oxygen getter method is idea way to locate metal fragments in a fuel element as an excess oxygen absorber. Since almost nothing has been reported concerning the application of an oxygen getter in pellet type fuels, conceptual development of the oxygen getter for pellet type MOX fuel and a feasibility study were done. For getter material, titanium was mainly evaluated in this study except for compatibility tests carried out for titanium and zirconium. Concerning the location of getter material in a fuel element, the pellet-cladding gap and axial blanket region are potential options to avoid melting of titanium or obtaining a eutectic solution with MOX fuel. At the same time, an adequate temperature for oxidation as well as compatibilities with cladding material and fuel must be realized. Three options were proposed for titanium and their potentials were evaluated from this viewpoint. As a result, locating the titanium pellets in the upper axial blanket region of the fuel element was identified as the most promising option and it could provide the required low smear density titanium pellet.
Morihira, Masayuki; Segawa, Tomoomi; Namekawa, Takashi; Matsuyama, Shinichiro*; Yuda, Ryoichi*; Mizusako, Fumiki*
no journal, ,
Investigation of oxygen getter option is in progress for FBR MOX fuel to restrain the cladding inner surface corrosion at the high burn-up of 150 GWd/t. Evaluation of the requirement for the oxygen getter materials showed that Zr and Ti were promising candidate materials. Method of loading getter materials into a fuel element was also investigated. Their oxygen uptake ability and restructuring behavior during the oxidation were evaluated by the heating at 1573 K for 10 h under the controlled oxygen potential. As a result, it was shown that both Zr and Ti were available as an oxygen absorber but Ti was superior from the geometrical stability.
and FMSSegawa, Tomoomi; Morihira, Masayuki; Namekawa, Takashi; Matsuyama, Shinichiro*; Yuda, Ryoichi*; Mizusako, Fumiki*
no journal, ,
Heating tests were carried out for the disc pares of Zr-FMS, Ti-FMS, Zr-UO and Ti-UO to evaluate the compatibility of the candidate materials of oxygen getter with UO and FMS, and the interfaces of each disc were investigated. No reaction was observed between Zr and UO also FMS in the test conditions. For Ti and FMS, Ti-Fe-O phase with the maximum thickness of 14 
m was formed in the Ti disc at 700C for 100 h but no penetration of Ti into FMS disc was observed. For Ti and UO, Ti-U or Ti-U-O phase were formed near the surface of the Ti disc but these were limited in Ti disc side. No penetration of Ti into UO disc was observed. As a result, it is considered that no harmful influence is expected for Zr and Ti on the integrity of UO and FMS cladding.
Morihira, Masayuki; Mizusako, Fumiki*; Tsuboi, Yasushi*
no journal, ,
A feasibility study for oxygen getter options is conducted in JAEA to reduce cladding inner corrosion of FBR MOX fuels to attain high burn-up. Investigation of oxygen getter loading options for pellet type MOX fuels as well as evaluation results of oxidation behavior of the candidate materials are reported.
Morihira, Masayuki; Mizusako, Fumiki*; Nagata, Akito*; Takayasu, Teruki*
no journal, ,
Cladding inner corrosion is one of the life controlling factors of FBR MOX fuels and it depends on the oxygen potential in a fuel element. The oxygen getter method is idea way to locate metal fragments in a fuel element as an excess oxygen absorber. Since almost nothing has been reported concerning the application of an oxygen getter in pellet type fuels, conceptual development of the oxygen getter for pellet type MOX fuel and a feasibility study has been conducted. In the previous study, titanium was chosen as the most promising candidate material. Concerning the method to install the getter material in a fuel element, an option to locate titanium pellets in the upper axial blanket region was proposed. In this case, it is necessary to reduce the smear density. To realize it, the titanium roll pellet option was proposed. In this study, producibility of titanium roll pellets and their oxidation behavior were evaluated. Additional oxidation data for titanium was also obtained.
Suzuki, Akihiro*; Mizusako, Fumiki*; Inagaki, Yaohiro*; Arima, Tatsumi*; Fukasawa, Tetsuo*; Hoshino, Kuniyoshi*; Muroya, Yusa*; Matsumura, Tatsuro
no journal, ,
no abstracts in English
Matsumura, Tatsuro; Ishii, Sho*; Suzuki, Akihiro*; Mizusako, Fumiki*
no journal, ,
no abstracts in English
Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
no journal, ,
Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
no journal, ,
no abstracts in English
Akaoka, Katsuaki; Oba, Hironori; Wakaida, Ikuo; Ouchi, Atsushi*; Mizusako, Fumiki*; Eto, Yoshinori*; Torimaru, Tadahiko*
no journal, ,
For measurement of the fuel debris from the Fukushima Daiichi Nuclear Power Station accident, we analyzed the LIBS spectrum of the mixed simulated fuel debris of U, Zr and Fe, using the least-squares method. We present the results of the calibration curve and analysis spectrum.
Oba, Hironori; Akaoka, Katsuaki; Wakaida, Ikuo; Ouchi, Atsushi*; Mizusako, Fumiki*; Eto, Yoshinori*; Torimaru, Tadahiko*
no journal, ,
no abstracts in English
Sudo, Ayako; Mizusako, Fumiki*; Hoshino, Kuniyoshi*; Sato, Takumi; Nagae, Yuji; Kurata, Masaki
no journal, ,
