INTRODUCTION 



The Millstone Nuclear Power Station (MNPS) is located on the north shore of Long Island Sound 

 (L,IS) in Waterford, Connecticut. The station consists of three units located on a peninsula bounded by 

 Jordan Cove on the east and by Niantic Bay on the west (Fig. 1). Millstone Unit 1, which commenced 

 commercial operation November 29, 1970 is a 652-MWe boiling water reactor (BWR). Unit 2, an 

 870-MWe pressurized water reactor (PWR), began operating October 17, 1975. Construction of Unit 3, 

 a 1,150-MWe PWR, began in August 1974; commercial operation began April 23, 1986. 



Niantic Boy 

 Figure 1 . Site plan of the Millstone Nuclear Power Station. 



All three units use once-through condenser cooling water systems. The rated circulating flows for 

 Units 1, 2 and 3 are 935, 1,220 and 2,000 cfs, respectively. Cooling water is drawn from depths greater 

 than four feet below mean sea level by separate shoreline intakes located on Niantic Bay. The intake 

 stRictures, typical of shoreline installations, have course bar racks and traveling screens. The cooling water, 

 heated to 17 "C above ambient, flows from discharge structures through an abandoned granite quarry and 

 exits into LIS through two channels equipped with fish barriers. Cooling water flow rates from 1976 

 througli 1985 are presented in Figure 2 for Units 1 and 2. Flow rates for Units 1 and 2 prior to 1976 are 

 provided in Appendices on file at Northeast Utilities Fnvironmental Laboratory (NULL). Ambient water 

 temperatures and AT for the same period are presented in Figure 3. 



