The subcritical neutron multiplication factors k for two parallel, axially separated, flat cylindrical tanks separated up to 57.91 cm in air and containing enriched uranyl (93.1 wt% 235U) nitrate solution (71.6-cm-i.d. tanks, 8.91-cm solution thickness, 1.555 g/cm3 solution density, and 404 g U/ℓ uranium density) were measured by the 252Cf-source-driven noise analysis method with measured k values varying from 0.99 to 0.80. These measurements were performed at the Los Alamos National Laboratory (LANL) Critical Experiments Facility in 1989 and were part of the program of Westinghouse Idaho Nuclear Company (WINCO) to benchmark calculations for the design of the new storage system at Idaho National Engineering Laboratory. Initial subcriticality measurements by the source-jerk method at LANL had indicated that at a calculated neutron multiplication factor k = 0.95, the measured k was 0.975. This discrepancy was of concern to WINCO because the new storage facility was being designed with a k limit of 0.95, and thus, half of the criticality safety margin of the storage design was equal to the discrepancy between early measurements and calculations. The 252Cf-source-driven noise analysis measurements confirmed the validity of the calculational methods. In addition to providing the neutron multiplication factor from point-kinetics interpretation of the data, these measurements also provided the auto-power and crosspower spectral densities as a function of frequency, which can be calculated directly with recently developed Monte Carlo methods and thus could also be used to validate calculational methods and cross-section sets. As with previous measurements with loosely coupled systems, a modified point-kinetics interpretation was successfully used to obtain neutron multiplication factors for measurements with the californium source and detectors located on the same tank. Although the californium source is located on axis but asymmetrically in the system, the detectors adjacent to the radial surface were sufficiently far apart that the correlated information was from long fission chains, which are distributed throughout the system of two tanks. The subcritical neutron multiplication factors obtained from the break frequency noise analysis method agreed with those from the 252Cf-source-driven noise method. These measurements confirmed the criteria from previous experiments for location of the source and detectors to obtain the neutron multiplication factor by using a modified point-kinetics interpretation of the data and again verified the usefulness of this method for interacting systems.