Design Considerations, Construction, and Performance of an Extensive Sea Water Conveyance System


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Title: Design Considerations, Construction, and Performance of an Extensive Sea Water Conveyance System

Author(s): A. J. Hulshizer and A. Kodal

Publication: Special Publication

Volume: 109


Appears on pages(s): 677-704

Keywords: coatings; concrete construction; concrete durability; corrosion; marine atmospheres; nickel; performance; reinforcing steels; sea water; structural design; underwater structures; General

Date: 8/1/1988

The ocean-cooling water supply and return system for the Seabrook Nuclear Power Plant is a vital link in the operation of the multibillion dollar facility. The water conveyance system is comprised of three main concrete construction components, each representing different construction techniques and somewhat different corrosion problems and approaches to promoting durability. Concrete intake heads, weighing 227 tons each, were precast off site and utilized nickel-coated reinforcement as a special means to preclude corrosion which otherwise would be accelerated by the presence of a 90-10 copper-nickel anti-fouling cladding. Prefabricated 1.52 and 2.87 m diameter vertical ocean shafts have their steel outer casings protected against corrosion by a mesh reinforced, spin cast, low water-cement ratio, mortar lining. Over 10 km of 5.8 meter diameter tunnels and the vertical land shafts were constructed of conventional cast-in-place, reinforced concrete. The subsea location of the structures and the depth of the tunnels demand that the concrete perform virtually maintenance free for the 40 year design life of the plant. Paper discusses the initial design considerations, construction experiences, and observations from the underwater inspection conducted on the various concrete components, after having been submerged for as much as 7 years at the time of inspection.