PCMI effect study in the fuel rod of a PWR reactor type subjected to power ramps

PWR reactor type, when subjected to the power ramp regime, a mechanical interaction between the cladding and the UO₂ pellet (PCMI) may occur in the fuel rod. To investigate this phenomenon were used two software, the first was a modified fuel performance code to verify the behavior of fuel rod with steel cladding and another to analyze structural mechanical behavior. The fuel performance code results show that there is no contact between the pellet and the cladding in the fuel rod, considering the estimated burning under normal conditions of reactor operation. Thus, it was adopted the hypothesis of the interaction pellet-cladding occurrence, generated by pellet fragmentation and relocation, and power ramp simulation conditions independent of the ramp time. The simulations results show that the fuel rod maintains its integrity under the conditions of the adopted hypothesis. (author)