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Thermal-Hydraulics | |
Fuel |
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Post-test analysis of WWER ballooning experiments
Cs. Győri, Z. Hózer, L. Maróti KFKI Atomic Energy Research Institute H-1525 Budapest, P.O.Box 49, Hungary
Extended Abstract
At the KFKI-AEKI an experimental series was performed with Zircaloy and Zr1%Nb cladding materials in order to compare their mechanical behaviour and strength under transient conditions. Near 100 biaxial tests were carried out providing linear pressure increase in 5 cm long samples under isothermal condition. The mechanical deformation of the samples was observed and the rupture conditions were analysed. The comparison of WWER and PWR materials indicated that their behaviour in ballooning processes is different. The effects of temperature, oxidation and iodine on burst pressure were investigated as well. Numerical post-test analyses have been performed with the US fuel
behaviour code FRAP-T6 and with the stand alone fuel module of the
French thermohydraulic system code CATHARE. Beyond the conclusions of
the ballooning experiments the paper presents the results of the
calculations for both Zircaloy and Zr1%Nb claddings, describes the
modifications needed for WWER cladding simulation and explains the
importance of
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transition model
for fuel failure handling.