Waste
Heat Treatment Facility North Anna Power Station
Cooling
Lagoons
North Anna Power Station uses water
from Lake Anna to condense steam back to water inside
the station. The water is returned to the lake slightly
warmer than when it was taken. The discharged water
cools in a series of private cooling lagoons, known
as the Waste Heat Treatment Facility (WHTF). When
North Anna is in full operation, approximately 2,000,000
gallons of water pass through the station per minute.
Reservoir
and WHTF Background
Lake
Anna was developed to provide cooling water
for North Anna.
It was originally timberland and
some farmland. When construction of North Anna began,
the area that would become the lake bottom was completely
cleared in 1968 before filling with water.
In 1972, the North Anna River was
impounded, forming Lake Anna and the adjacent Waste
Heat Treatment Facility.
Lake Anna is 17 miles long, 1 1/2
miles wide, and offers 200 miles of shoreline. There
are 9,600 acres in Lake Anna and 3,400 acres in the
private WHTF. In 1972, the Commonwealth of Virginia
stocked the lake with 5 1/2 million fish, and it
is restocked periodically. Some 33 species of fish
thrive in the lake, including largemouth bass, striped
bass and catfish.
By design, the temperature
of the discharge water is typically 14 degrees warmer than the intake
water. Intake temperatures can fluctuate with seasons or weather conditions.
View the current temperature of the discharge water
below as it initially leaves the station. ("Refresh"
your browser for the latest reading.)
Water Temperature - Station Discharge
Date
Time
Degrees F
May 12
415
83.3
May 12
400
83.3
May 12
345
83.4
May 12
330
83.4
May 12
315
83.5
May 12
300
83.5
May 12
245
83.5
Cooling System
The process of generating
electricity at North Anna begins with the fission, or splitting, of uranium
atoms in the reactor vessel. The vessel is filled with water (not from
the lake), which controls, or moderates, the fission process, and removes
heat from the reactor core. This water is kept under very high pressure,
which prevents it from boiling although it is heated to three times the
normal boiling temperature.
This hot, pressurized water is pumped to nearby steel
containers called steam generators. In the steam generators, the water
passes through thousands of small U-shaped tubes — about the
diameter of your little finger — transferring its heat to a second,
slightly cooler water system. This secondary water becomes steam, which
travels through large pipes to spin the turbines in the adjoining building.
Spinning at 1,800 RPM, the turbines drive a generator
that produces electricity. The steam then is condensed back to a liquid
by a third cooling system before it returns to the steam generator to
start the process again. The third cooling system's water comes from
Lake Anna, and flows through the private WHTF before returning to the
lake.
