PNNL

Abstract

The U.S. Department of Energy (DOE) Office of River Protection’s Waste Treatment Plant (WTP) will process and treat radioactive waste that is stored in underground tanks at the Hanford Site. Pulse jet mixer (PJM) technology was selected for mixing the contents of many of the process vessels. Several of the tanks are expected to contain concentrated slurries that exhibit a non-Newtonian rheology and the understanding required to apply this technology to mobilize the non-Newtonian slurries was not mature. Consequently, an experimental testing effort was undertaken to investigate PJM performance in several scaled versions of WTP vessels and to develop mixing system configurations that met WTP requirements. This effort evolved into a large, multifaceted test program involving many different test facilities. Elements of the test program included theoretical analysis, development and characterization of simulants, development of instrumentation and measurement techniques, hundreds of tests at various scales in numerous test stands, and data analysis and application. This program provided the technical basis for the selection of pulse jet mixers along with air spargers and steady jets generated by recirculation pumps to provide mixing systems for several of the vessels with non-Newtonian slurries. This paper provides an overview of the testing program and a summary of the key technical results that formed the technical basis of the final mixing system configurations to be used in the WTP.