For North Anna, the CW (circulating water ) system does not transport the ultimate heat sink flow and therefore
was mostly not concluded to be in scope. The inspectors agreed with this conclusion.
The North Anna Power Station lake Intake Structure contains the CW intake tunnel header,
Auxiliary SW Pump House, Fire Pump House, and Intake Structure Control House. The Intake
Structure is located on the shore of the North Anna reservoir (Lake Anna). Circulating water is
withdrawn from the Lake Anna into the Intake Structure to provide cooling water for the main
condensers for Units 1 and 2. Backup, auxiliary SW for Units 1 and 2 and make-up water for
the separate, SW spray pond, the ultimate heat sink, is also provided from the Intake Structure,
through separate water lines. The Intake Structure is an eight-bay (four bays per unit)
reinforced concrete structure that serves both units. There is a total of eight trash racks, but
only the two trash racks associated with the safety related auxiliary SW Pump House and one
trash rack associated with the auxiliary fire pump are within the scope of license renewal.
With its different configuration, the North Anna site has in scope two auxiliary SW pumps that
are installed in the main circulating water intake structure on Lake Anna and four main SW
pumps at the SW reservoir pump house. SW is normally recirculated through the plant via the
main pumps and back to the spray pond. The auxiliary pumps are able to provide an alternate
supply of water to the SW supply headers. An alternate return path is also provided to the
Circulating Water discharge tunnel from the SW return headers. The auxiliary pumps or the notin-scope screen wash pumps can make up to maintain the level of the SW reservoir
www.nrc.gov