DESIGN OF THE SEALEVEL SUSPENDED SOLIDS CONCENTRATION MONITORING SYSTEM; FINAL

The SEAlevel project between Science and Engineering Associates, Inc. (SEA) and the National Energy Technology Laboratory (NETL) in Morgantown, WV (contract DE-AC21-96MC33126) began in direct response to a need expressed by personnel involved with monitoring fluid levels in underground storage tanks at the Hanford Tank Farms. Hanford expressed a desire for an automated monitoring system that could be installed into tanks through liquid observation wells (LOWs). The LOWs are pipes that run from the surface above the tank to the bottom of the tank. The end of the LOW pipe in the tank waste is sealed. Therefore, the LOW provides a clean conduit through which sensors and monitors can be lowered into the tanks. When the SEAlevel project first began, it was understood that the LOWs would be of steel construction, because several existing LOWs at the time were steel pipes and the plans for all future LOW installations were to be with steel pipes. Based on this assumption the SEAlevel monitoring system was to be made using an array of acoustic sensors. However, during the course of the project it was learned that many existing LOWs are of fiberglass construction and that it was the desire of the Tanks Surveillance Group at Hanford to change plans so that all future LOW installations be of fiberglass construction. The Tanks Surveillance Group wanted fiberglass LOWs to allow for a wider range of sensors to be used in the pipes (i.e., sensors that use electromagnetic signals). In response to this, SEA pursued the development of other types of sensors to install in the LOWs in addition to the acoustic sensors that were being developed. It was determined that a capacitance type sensor was well suited for non-metallic LOW pipes. The results of the analysis, testing and design efforts that were undertaken to address the Hanford needs were detailed in a report submitted to the NETL on August 15, 1997, titled, The Sealevel Approach For Monitoring Liquid Levels In DOE Waste Storage and Processing Tanks