The relative power distribution in the TSF-SNAP reactor was determined by scanning individual fuel elements for fission-product gamma rays, and the absolute fission rate was determined from uranium-foil activation. Numerical integration of the fission density over the core volume gave an absolute power calibration for detectors and foils external to the core. Calculations of both the axial and radial power distributions by Monte Carlo and discrete ordinates methods were in excellent agreement with the measured distributions.