Nuclear data uncertainties are propagated from basic theory to a full core model of the Kalimer-600 Korean type Sodium Fast Reactor (SFR) using the TALYS nuclear code system, the "Total Monte Carlo" (TMC) approach and perturbation methods developed at NRG. Nuclear data uncertainties from sodium, iron, and some actinides will be presented together with their impact on parameters such as the sodium void coefficient and k(eff). One of the advantages of the TMC method is that it avoids approximations used in perturbation theories, by applying an exact uncertainty propagation approach. Additionally, full nuclear data uncertainties (cross sections, nu-bar as well as single and double differential data) can be considered.