Estimating burnup uncertainties in KSU TRIGA Mark II reactor and their impact on reactor safety

Safety analysis was conducted for the KSU TRIGA Mark-II reactor to assess the safety impact of loading enriched fuel in the reactor core. This analysis was performed using a representative single channel conservative model in the best estimate thermal-hydraulic code RELAP5/MOD3.3. However the effects of epistemic uncertainties on the safety calculations and sensitivity of the model towards these uncertainties can play a critical role in decision-making. One of the major uncertainties in the input parameters for RELAP model can be in the axial power peaking factors attributed to uncertainties in burnup estimates. The uncertainty propagation through different models and sensitivity analysis were studied with the help of established tools such as MCNP and RELAP5/MOD3.3. The results of these sensitivity studies due to uncertainties in the burnup values were compared with the sensitivity to uncertainties within the thermal-hydraulic model.