The LWR-PROTEUS Phase II experimental program was conducted at the Proteus research reactor at the Paul Scherrer Institute (PSI) in the early 2000s. One of its purposes was to gain more insight into the reactivity changes caused by fuel burnup and to develop a sense of confidence in modern codes’ ability to predict these changes. The presented project reexamines the experimental campaign using SHARK-X. SHARK-X is a set of Perl-based tools developed at PSI and built around the lattice physics code CASMO-5. It is used to perform sensitivity analysis (SA), uncertainty quantification (UQ), and representativity analysis (RA). This report discusses how SHARK-X was used to quantify the effect of input uncertainties when modeling the LWR-PROTEUS Phase II experiments and to evaluate the representativity of the experiments to a spent fuel pool of the nuclear power plant Gösgen (KKG).