Interpretations of results from hydraulic modeling of thermal outfall diffusers for the San Onofre Nuclear Power Plant

摘要

This report presents and interpretation of results obtained during the hydraulic model study previously documented in "Hydraulic Modeling of Thermal Outfall Diffusers for the San Onofre Nuclear Power Plant" which described the hydraulic laboratory studies conducted to investigate outfall configurations for the thermal discharge from proposed Units 2 and 3 at the San Onofre Nuclear Generating Station, jointly owned by the Southern California Edison Company and San Diego Gas and Electric Company. ududA number of different experimental investigations were performed to develop the conceptual design for the new Units 2 and 3 discharge diffusers. The primary reason for the investigations was the new California thermal standards (essentially ambient temperature increment less than 4°F), which in effect precluded the use of shoreline or single outlet discharges for new units and necessitated the use of multiport diffusers. ududThe result of the investigations of different diffuser concepts was the establishment of a preliminary design for the discharge structures for Units 2 and 3, each consisting of a diffuser 2500 ft long containing 76 discharge nozzles with a nominal discharge velocity of 13 ft/sec. This preliminary design was later modified somewhat by the engineers of the Southern California Edison Company (SCE) in consideration of other factors such as structural requirements, cost, construction problems, and more accurate bathymetric details at the site. As a result the final design for each diffuser contains 63 discharge ports of diameters varying from 21.85 to 23.9 inches. The discharge ports are nozzle-riser assemblies at alternate angles of ±25° with respect to the longitudinal axis of the diffuser and 20° up from horizontal. The nozzles are positioned approximately 6 ft from the ocean bottom. The diffusers are aligned perpendicular to shore and extend from approximately 3500 ft to 8500 ft offshore. ududThe performance of the final diffuser design was evaluated in a series of confirming tests. The major results will be summarized and discussed in section 3 of this report. ududSections 3 and 4 will also include projections and elaborations on several aspects of the diffuser performance to be expected in the prototype. The possible interactions of the proposed diffuser operation with existing site factors such as ocean currents, water temperature, heat losses, and the existing power plant (Unit 1) will also be discussed in section 4.