Fuel-claddng mechanical interaction in fast reactor fuel rods

The major points are summarized below. In general, oxide fuels undergo less FCMI than helium-bonded carbide fuels during steady-state conditions whereas the opposite is true for overpower transient conditions. Most of the cladding damage in (U,Pu)O2 fuel rods is generated during overpower transients. (Th,Pu)O2 fuel rods generally show more FCMI and cladding damage than (U,Pu)O2 for both steady-state and transient conditions. FCMI stresses and cladding damage are generally higher in ThO2 blanket rods than in UO2, UC, or ThC blankets. the latter three blanket concepts undergo only little damage from FCMI. A detailed study revealed that while damage in (U,Pu)O2 fuel rods was significantly reduced when cladding thickness was increased in the range of 0.30 to 0.50 mm, helium-bonded (U,Pu)C fuel rods showed little or no benefit from increasing thickness. These results indicate that cladding thinner than currently considered can be utilized in helium-bonded carbide fuels