The Seabrook Nuclear Power Plant circulating water intake and discharge tunnels

The Seabrook Nuclear Station's two unit design demanded 850,000 gpm of cooling water which was satisfied by once-through cooling which utilized the Atlantic Ocean for intake and discharge once-through cooling. Environmental considerations dictated the location of the intake and discharge ports to be over one mile off of the shore line. The mandated port location, additional environmental and public interface conditions and economic considerations were addressed satisfactorily with the use of a hard rock tunnel and shaft system. The tunnels were TBM bored at 22'-0 diameter for a combined length of 33,500 ft. Fourteen large diameter shafts were connected to the ocean with a safe dry-tap system. This paper outlines the design and construction experience associated with the successful completion of this project.