The US Department of Energy's Morgantown Energy Technology Center (METC) has been developing instrumentation for improved monitoring of fluidized-bed operational parameters. This report describes the electronic system being developed to provide a real-time two-dimensional map of the bed material density with a resolution of 1 inch or better and with a map update rate of about 100 updates per second. This two-dimensional system is the major step in the development of the desired three-dimensional density mapping system. The density monitoring system uses a 6-inch inside diameter (ID) by 2-feet long plastic pipe as the fluidized-bed vessel. At a point halfway between the ends of the pipe, 16 1-inch x 1-inch metal electrodes are mounted on the inner surface of the pipe. With the pipe in a vertical position and holding 1/8-inch plastic spheres, air can be introduced at the bottom of the pipe to fluidize the spheres. By measuring the displacement currents between electrodes, equations relating the measured currents to bed density values are formed. Solving the equations produces the density values at 49 designated areas covering the bed cross section. Preliminary tests of the system have shown that single bubbles passing through the monitored bed cross section can be seen crossing the monitored region and can be located at n particular positions at times t1, t2, ..., t/sub n/ by solving the developed equations using the electrode displacement current values at times t1, t2, ..., t/sub n/. Further development is necessary to refine the computation of density values at each of the 49 designated areas and to extend the system's capability to three-dimensional, real-time bed density mapping. 5 refs., 13 figs., 7 tabs.