FEMAXI-6 Code Verification with MOX Fuels Irradiated in Halden Reactor

The advanced reactor concept innovative water reactor for flexible fuel cycle (FLWR) is being studied to achieve effective and flexible utilization of uranium and plutonium resources based on well-developed light water reactor (LWR) technology. In order to design and evaluate FLWR fuel rod behavior, uncertainties in FEMAXI-6 calculations and key models and parameters for predicting LWR MOX fuel rod behavior need to be evaluated. In this study, the test fuel data bases (TFDBs) obtained from the Halden reactor experiments (IFA-597.4 rod-10, rod-11, and IFA-514 rod-1) were used for the evaluations. The maximum discharge burnup was about 40 GWd/tMOX (IFA-514 rod-1). Based on the evaluation results, fission gas release (FGR), pellet densification, swelling, and relocation models were found to be particularly important. The FGR model has a relatively large uncertainty for predicting MOX fuel rod behavior. However, the uncertainties in the other models are within the range expected by the property variations of MOX fuels. Hence, the densification, swelling, and relocation models of FEMAXI-6 can be applied to MOX fuel analyses.