Simulation of QUENCH-15 and Preliminary Pre-Test Predictions for QUENCH-19

Abstract

Iron chromium aluminum (FeCrAl) alloys have been developed at Oak Ridge National Laboratory for use as advanced fuel cladding for light water reactors (LWRs). In contrast to the zirconium-based alloys employed today, FeCrAl has slower oxidation kinetics and higher strength. A test (QUENCH-19) at Karlsruhe Institute of Technology's QUENCH facility is planned to examine and demonstrate the performance of FeCrAl cladding under postulated accident conditions. This test will replicate the previous QUENCH-15 test but will use FeCrAl instead of zirconium-based materials. During these tests, a small bundle of fuel rod simulators is electrically heated in a steam and argon environment. Temperature history, oxidation thickness, and in-situ hydrogen generation are the primary measurements of interest. The CORA boiling water reactor (BWR) code (CORA/BWR) was developed and used in the 1980s and 1990s to simulate BWR bundle degradation during the CORA test series. A modified version of the CORA/BWR code, named CORA/BWR-QUENCH, has been developed to model the QUENCH test facility. The CORA/BWR-QUENCH code was used to model the QUENCH-15 test, which tested zirconium-based materials. The code predictions and test data were found to be in good agreement. Using the same boundary conditions as the QUENCH-15 test, the code was then used to model the planned QUENCH-19 test using FeCrAl cladding, shroud, and spacer grids. The simulation predicts the peak cladding temperature to be 1,620 K (~1,347°C) for QUENCH-19, which is significantly lower than temperature observed during QUENCH-15 with the zirconium-based alloy. The predicted hydrogen generation is also significantly lower for the FeCrAl clad QUENCH-19 as compared to QUENCH-15: ~1.7 g versus ~48.8 g. These results align with expectations given the much slower oxidation kinetics of FeCrAl alloys.