Transient Fuel Behavior and Failure Condition in the CABRI-2 Experiments

Sato, Ikkenn ; Lemoine, F.*; Struwe, D.*

In the CABRI-2 program, 12 tests were performed under various transient conditions covering a wide range of accident scenarios using two types of pre-irradiated Fast Breeder Reactor (FBR) fuel pins with different smear densities and burn-ups. For each fuel, a non-failure-transient test was performed and it provided basic information such as fuel thermal condition, fuel swelling and gas release. From the failure tests, information on failure mode, failure time and axial location was obtained. Based on this information, failure conditions such as fuel enthalpy and cladding temperature were evaluated. These failure conditions were compared with the CABRI-1 tests in which different fuels as well as different transient conditions were used. This comparison, together with supporting information available from existing in-pile and out-of-pile experiments, allowed an effective understanding on failure mechanisms depending on fuel and transient conditions. It is concluded that Pellet Cladding