The objectives of the project are to investigate the use of (1) ultrasonic diffraction grating spectroscopy (UDGS) for measuring the particle size of a slurry and (2) shear wave reflection techniques to measure the viscosity of a slurry. For the first topic, the basic principle is to extend the methods that have been successful in optics, called grating light reflection spectroscopy (GLRS), to ultrasonics. At the University of Washington, researchers are using GLRS to measure nanometer-sized particles and particles up to two microns in size in slurries. The goal of the research with ultrasonics is to measure particles in the range of a few microns to about 100 microns, which is the range of particle sizes for slurries in the radioactive waste tanks at U.S. Department of Energy (DOE) sites.