The response of neutron logging tools used for uranium exploration to variations in tool design, borehole parameters, and rock matrix properties has been studied using discrete ordinates and Monte Carlo radiation transport methods. The logging techniques that have been analyzed include the measurement of signal radiation due to delayed fission neutrons and prompt fission neutrons generated in uranium ore by pulsed 14-MeV and iso topic 252Cf neutron sources. The effect of variations in the following parameters has been studied: source-detector separation, tool casing, borehole diameter, mudcake thickness, mud filtrate invasion, tool eccentricity, borehole casing, rock matrix composition, matrix moisture content, formation water composition, neutron poisons, thin ore beds, ore bed dipping angle, and ore grade. “Noise” radiation from fast fission in thorium ore and delayed oxygen neutrons has also been computed and compared to the signal radiation as a function of uranium and thorium ore grades, borehole size, and rock moisture concentration. Evaluation models have been produced to aid in calibration of the logging tools for uranium assay.