b'modeled using as-run neutronics data and projected powers for cycles yet to be irradiated with control pins (75% smear density, sodium bonded, solid pins in HT9). The modeling was done to make comparisons between thermal and irradiation effects on the cladding and how these two phenomena independently affect the perfor-mance of the FAST fuel system experiments. To this end, EBR-II irradiation data was taken from the Fuels Irradiation & Physics Database to match the conditions of the FAST experiments. The neutronics data was then taken and applied to the FAST experi-ment models so that the burnup behavior of the fuel would match the irradiation conditions of the EBR-II experiments. This compar-ison is shown in Figure 2. This exercise also revealed deficiencies in the Bison performance models. There is an issue with the fuel creep calculation where the solid geometry pins are diverging from a solution and not completing the simulations. This leads to the solid fuel pins needing to be simulated while excluding the fuel creep from the inelastic stress calculations. The annular pins can be simulated while including the fuel creep calculation. The cause of this issue with the fuel creep for solid pin geometries is still under investigation. In spite of these deficiencies, the models were still informative. Preliminary results show that the burnup is consistently underpredicted when compared to the Monte CarloTable 1. This table provides a brief summary of FAST and EBR-II pins with burnup, N-Particle as run simulations.cladding fluence, and cladding dpa. For the EBR-II pins, the databases provide a summary fluence for the assembly but not specific fluence or dose for individual The strain is overpredicted in thepins. EBR-II pins are listed by sub-assembly and pin number with the parenthesis region where the fuel is locatedcapturing the cycle and location (Z/l) for the comparative local conditions2023|AFC ACCOMPLISHMENTS 191'