Measurement of Flow Patterns Using GPS Drogues

摘要

This paper describes a GPS drogue developed and used by TVA to measure flow patterns inrnintake withdrawal zones for thermal power plants. The specific application for the drogues is atrnthe Browns Ferry Nuclear Plant, located on the Tennessee River in northern Alabama. Coolingrnwater for the plant is withdrawn and returned to the river by intake and discharge structuresrnlocated immediately upstream and downstream of the plant. Due to the importance of coolingrnwater for power production, the operation of the plant is greatly affected by the patterns of flowrnin the withdrawal and mixing zones created by these structures. Optimal operation requiresrnknowledge of these patterns and the processes that influence their behavior. At Browns Ferry,rnknowledge of the patterns is especially important in regard to the accumulation of aquaticrnvegetation and other floating debris at the plant intake. Such accumulations are a chronicrnproblem and can threaten reliable operation of the plant. The development of remedialrnalternatives for managing accumulations required the measurement of the flow patterns in thernriver throughout the withdrawal and mixing zones. To better understand the dynamic processesrnby which the floating debris are either trapped or flushed downstream, the flow patterns neededrnto be measured at low and high flow conditions in the river. The GPS drogue was consideredrnbest for assessing near-surface velocity fields because of the limited accuracy of other boatmountedrnprobes for low flow conditions. The GPS drogue was fabricated at a low cost and wasrneasily deployed, retrieved, and interrogated in large numbers over a wide area within a shortrnperiod of time. Described herein are the design of the GPS drogue, procedures for field testing,rnand selected results of the measured flow patterns at Browns Ferry Nuclear Plant. Conclusionsrnand recommendations are given regarding the overall performance of the drogues, potentialrnimprovements, and applications for related field measurements.