Friction coefficient measurementsn and analysis of local stress/strain in Zircaloy-2 cladding

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立花 利道; 中江 延男*; 金子 洋光; 本田 裕*

Tachibana, Toshimichi; not registered; Kaneko, Hiromitsu; Honda, Yutaka*

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In the present study, the friction coefficient between UO pellet and Zry-2 cladding was successfully measured by out-of-pile experiments. The friction coefficient under a condition of hard contact was about 0.5 at temperature region of 300-400 C celsius. Using the results, calculation was performed to obtain the local stress/strain distributions in Zry- 2 cladding when a radially cracked pellet expanded out wardly after contact with the cladding. The calculation was carried out by finite element code in which a system of friction between pellet and cladding was introduced. Local strain concentrations appeared not only at the position just facing pellet's crack but also at the position apart from the cracks when the friction coefficient became larger than 1.0. From the analysis it was concluded that keeping the friction coefficient below 0.5 in fuel rod must be one of measures which prevent PCI-induced SCC failure.