Validation of a Pin-Based Screening Methodology for the Investigation of Pellet-Clad Interaction during Load-Follow Operation

摘要

In this work we investigated the effect of PWR loadfollowoperation on fuel failure risk. PWR1, an unnamedcommercial reactor which performed load-follow power maneuversin cycle 21, was modeled using VERA-CS. The linearheat rate and coolant temperature calculated by VERA-CSduring the maneuvers were used as boundary conditions forBISON fuel performance calculations. Using the maximumhoop stress as the indicator of fuel failure risk, the differentload-follow power maneuvers were compared to the initialstart-up ramp. In order to determine the eect load-followoperation has on the fuel failure risk, dierent characteristicsof the maneuvers were compared, e.g the magnitude of the decreasein power, hold period, and the presence of intermediatepower steps. No correlations were observed between thecharacteristics and the resulting maximum clad hoop stress.In order to reduce the number of fuel performance calculationsrequired to determine the safety of subsequent loadfollowpower maneuver, a pin-based screening method wasdeveloped. By selecting the top 1000 fuel rods selected duringthe screening process, the BISON predicted limiting fuelpin for each maneuver was captured.