The effort involved in determining the location and quantity of reactor fuel remaining in the nuclear auxiliary systems of the auxiliary/fuel handling building at Three Mile Island Unit 2 is discussed. The overall approach identifying the most likely locations for reactor fuel, the gamma-ray spectrometry system used, and the radiation transport computer codes and numerical analysis techniques used is also discussed. The results of the measurements show that a very small quantity of reactor fuel remains in the makeup and purification and the waste disposal liquid systems.