FINAL REPORT 

 HYDROTHERMAL SURVEY 

 iILLSTONE NUCLEAR PO^JER STATION 

 WATERFORD, CONNECTICUT 



1.0 INTRODUCTION 



During the period 21-25 August 1987, Ocean Surveys, Inc. 

 (OSI) performed hydrographic and dye tracer surveys for 

 Northeast Utilities Environmental Laboratory (NUEL) at the 

 Millstone Nuclear Power Station, Waterford, Connecticut 

 (Figure 1). This work was undertaken to provide NUEL with 

 contoured delta-T isotherm maps of the generating station's 

 thermal plume during four phases of a complete tidal cycle. 

 NUEL assisted OSI in executing this project by supplying 

 personnel, equipment and facilities for equipment monitoring 

 and offshore surveying. 



Rhodamine WT dye was injected into the Unit 3 discharge 

 waters. Dye concentration and water temperature data were 

 collected along 41 transects and 27 vertical profile stations 

 in and around the thermal plume during the times of low 

 slack, maximum flood, high slack, and maximum ebb tides. 

 These data were analyzed to determine the positions of the 

 1.5 ,4,6 and 8 F delta-T isotherms. The contoured 

 isotherms are presented by tidal phase in Figures 10 through 

 13 of this report . 



Dye concentration and temperacure data were additionally 

 collected at the Unit 1 discharge well to monitor for the 

 recirculation of power station cooling water and are 

 presented in Figure 9 of this report. 



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