Self-powered neutron detectors (SPNDs) with cobalt emitters exhibited sensitivity to water density variations in the loss-of-fluid test large break transient simulations. Definite correlations were determined for both depressurization (decreasing water inventory) and core reflood (increasing water inventory) phases of the transients. The SPNDs were positioned in a radial array at the elevation corresponding to the maximum power in the core. The pre-experiment steady-state power density at the detector locations varied from a maximum of 39.3 kW/m (12.0 kW/ft) to a minimum value of 17.4 kW/m (5.3 kW/ft), inclusive of all locations and transient simulations. All of the SPND data exhibited good correlation to water density variations over this range of initial power densities. Water density fluctuations were measured by the SPNDs throughout these transients, and the fluctuations associated with the early corewide rewet and the gravity reflood flow oscillations are addressed in detail. Analytical investigation of the response of these detectors to water density variations long after reactor shutdown indicates that these detectors will remain sufficiently sensitive to have application in reactor vessel liquid level measurement in small break pressurized water reactor transients.