The Canadian pressure-tube supercritical-water-cooled reactor is an advanced Generation IV reactor concept that uses water above its thermodynamic critical pressure as its coolant. The higher operating pressure dictates changes in the design and configuration of the reactor core and fuel assemblies as compared with existing CANDU designs. In addition, the reference Canadian design considers a plutonium-driven thorium fuel with high-pressure light-water coolant and a separate low-pressure heavy-water moderator. The salient features of this core design include a vertically orientated re-entrant channel where the coolant passes from an inlet plenum above the core downwards through the internal annulus flow tubes in each fuel assembly, then through a 180° bend, then upwards through the fuel region of the assembly where it absorbs thermal energy, and finally into the outlet plenum located above the core. Given the multiple flow paths through a fuel assembly, the significant coolant property variations along the fuel channel caused by transitions through the pseudo-critical temperature, the external low-pressure moderator, and the Pu–Th fuel composition, the lattice physics phenomena are significantly different from those in conventional CANDU power plants. In this paper, the changes in lattice physics phenomena are identified and analyzed through sensitivity and uncertainty analyses using the lattice physics modules in standardized computer analysis for licensing evaluation.