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Toyokawa, Takuya; Usami, Koji; Shiina, Hidenori; Onozawa, Atsushi
Proceedings of 49th Conference on Hot Laboratories and Remote Handling (HOTLAB 2012) (Internet), 6 Pages, 2012/09
Matsui, Hiroki; Toyokawa, Takuya; Honda, Junichi; Harada, Akio; Kurosaki, Ken*; Konashi, Kenji*
no journal, ,
no abstracts in English
Sugiyama, Tomoyuki; Udagawa, Yutaka; Fukuda, Takuji; Nagase, Fumihisa; Murao, Hiroyuki; Toyokawa, Takuya
no journal, ,
no abstracts in English
Toyokawa, Takuya; Matsui, Hiroki; Honda, Junichi; Kikuchi, Hiroyuki
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no abstracts in English
Obata, Hiroki; Toyokawa, Takuya; Tomita, Takeshi; Kimura, Yasuhiko
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Hydrogen absorption to the fuel cladding is increase on the high burn-up fuel. The concentration of absorbed hydrogen causes the cladding embrittlement which might become the origination of fractures of the cladding. Therefore, it's important to measure the hydrogen volume in the cladding to estimate the safety margin of the irradiated cladding. In the previous method of hot vacuum extraction, the hydrogen is released and measured as the melting condition of the cladding. It cannot be evaluated the hydrogen volume only in the cladding metal phase. The hydrogen absorption in the cladding metal phase is strongly-correlated the cladding embrittlement. The two-step heating method has the benefit to measure the hydrogen in metal phase and oxide layer separately. The measuring method including the extraction temperature condition using unirradiated cladding will be reported.
Suzuki, Kazuhiro; Toyokawa, Takuya; Motooka, Takafumi; Tsukada, Takashi; Ueno, Fumiyoshi; Terakawa, Yuto; Suzuki, Miho; Ichise, Kenichi; Numata, Masami; Kikuchi, Hiroyuki
no journal, ,
no abstracts in English
Obata, Hiroki; Toyokawa, Takuya; Tomita, Takeshi; Kimura, Yasuhiko
no journal, ,
The amount of hydrogen absorbed to the fuel cladding increases by extended burnup fuel. The absorbed hydrogen that exceed solid solubility limit precipitates as the hydride phase. The high concentration of hydride causes the fuel cladding embrittlement which might become the origination of fractures of the cladding. Therefore, it is important to measure the hydrogen content in the cladding to estimate the safety margin of the irradiated cladding. Hydrogen is absorbed not only in the cladding metal phase, but in the oxide layer. To evaluate the embrittlement of the cladding, it is necessary to measure the hydrogen content in the cladding metal phase and oxide layer separately. Therefore, the two-step heating method can measure the amount of hydrogen in the metal phase and the oxide layer separately. This paper shows the technical review of measuring method including the technique for the determination of extraction temperature.
Motooka, Takafumi; Suzuki, Kazuhiro; Suzuki, Miho; Toyokawa, Takuya; Kimura, Yasuhiko
no journal, ,
Spent fuels were stored in the spent fuel pool (SFP) at the Fukushima Daiichi Nuclear Power Plant. Seawater was injected into SFP to cool spent fuels for emergency measure in the Fukushima Daiichi Nuclear Accident. Seawater can cause local corrosion. The purpose of this study is to investigate the effect of seawater on corrosion behavior and mechanical property of the spent fuel cladding. We immersed short spent fuel cladding tubes (50 GWd/t) in artificial seawater at 353 K for 300 h and conducted visual, metallographic and strength examinations of the tubes after immersion. Visual and metallographic examination indicated that warm seawater little affected the corrosion behavior of the spent fuel cladding. Black oxides formed on the surface of the cladding during the reactor operation were observed. No local corrosion and crack were observed. Ultimate tensile strength (UTS) and 0.2% yield strength (0.2%YS) of tubes with and without immersion in artificial seawater at 353 K for 300 h were measured. The strength of immersed tube was comparable to that of non-immersed tube. The results suggest that the seawater injection little affects on corrosion behavior and mechanical property of the spent fuel cladding.