Friday, May 16, 2014

Trojan in Twilight: Cooling Tower

IMG_1768 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

The most dominant feature by far on the Trojan site was the cooling tower. For some reason, many people don't understand the function of a cooling tower, and some even think that the tower is the power plant itself, so I will try to give an explanation of what a cooling tower is and what it does.

IMG_1769 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

Most power plants, including those that burn coal, oil and natural gas as well as nuclear plants, simply heat water to produce steam which is used to turn a steam turbine connected to a generator. This steam is then cooled in condensers back into water to be reheated. The condenser itself is cooled by water from a separate supply, which in turn is cooled in a cooling tower and cycled back through the condenser. In some cases, these cooling towers are largely mechanical in nature, which keeps the size down in relation to the rest of the power plant, but requires more electricity. The other option is to use a much larger natural draft cooling tower.

IMG_1770 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

While the general public most often associates these towers with nuclear power plants, they can be found in other applications, including power plants using other fuels, and some nuclear plants use mechanical draft cooling towers instead of natural draft.

IMG_1771 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

Trojan used a 499-foot hyperbolic natural draft cooling tower to cool the water for the condensers. A natural draft cooling tower operates entirely on the basic principle that air rises as it heats up.

IMG_1818 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

Though a natural draft cooling tower is by far the most visually impressive component of a nuclear power plant, because there is two completely separate systems between the nuclear reactor in the Containment Building and the cooling water of the condensers, the cooling tower is never exposed to any nuclear radiation or radioactive material.

IMG_1819 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

The Virtual Nuclear Tourist has a good general explanation of Cooling Towers.

IMG_1820 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

For more information on how a nuclear power plant generates electricity, Click Here.

IMG_1824 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

Trojan's cooling tower was built over the top of a water basin with a capacity of 5 million gallons. The bottom of the tower is open, to allow cool air off the Columbia River to enter the tower. Inside the tower, hot water (about 112 degrees) from the condensers was sprayed from nozzles onto cooling fins. As the drops of water dripped off these fins, the heat from the water was transferred to the cool incoming air, cooling the water to about 75 degrees. As the cooled water collected in the basin, the air rose, picking up speed as it absorbed more heat. By the time the warm air exited the top of the tower it was moving upwards at about 10 miles per hour. This air movement sucked more cool air in at the bottom of the tower, continuing the process (natural draft). Not all the water from the condensers was reclaimed in the cooling process. About 11,000 gallons of water was lost to evaporation per minute, joining with the rising hot air as water vapor to form the cloud-like plume seen coming from the top of the tower when the plant was operating. Water from the Columbia River was taken in to make up for the water lost to evaporation.

IMG_1827 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

Trojan's cooling tower was completed in May 1972, and consisted of 41,000 tons of concrete and steel. The tower's hyperbolic shape was designed to provide structural strength and speed vertical airflow. The diameter at the base measured 385 feet and the walls were 45 inches thick. At the top of the 499-foot height, the diameter was 250 feet, and the walls were 18 inches thick. At the tower's narrowest point, about 2/3 of the way up, the diameter was 232 feet and the walls were 10 inches thick.

FH000015 Trojan Nuclear Power Plant Cooling Tower on April 22, 2006
Trojan Nuclear Power Plant Cooling Tower on April 22, 2006.

The cooling tower was 499 feet tall; if it were any taller, it would have had to be painted with red & white stripes. As it was, the tower had to have a number of lights in place. Red lights were placed at the top of the tower and at 3 other elevations spaced equally up the side of the tower. At each elevation, a light faced in each direction.  Starting at the bottom, the red lights at the first and third row were on constantly.

IMG_2060 Trojan Nuclear Power Plant Cooling Tower Lights on May 13, 2006
Trojan Nuclear Power Plant Cooling Tower Lights at night on May 13, 2006.

The red lights on the other two levels (the middle of the tower and the top) oscillated on and off, all at the same time, at a period of about every three seconds.

IMG_2062 Trojan Nuclear Power Plant Cooling Tower Lights on May 13, 2006
Trojan Nuclear Power Plant Cooling Tower Lights at night on May 13, 2006.

Additionally, white strobes were also mounted at the top of the tower, halfway between the red lights around the perimeter. The white strobes flashed about 40 times a minute, though they did not seem to be synchronized with the red lights in any way.

IMG_2061 Trojan Nuclear Power Plant Cooling Tower Lights on May 13, 2006
Trojan Nuclear Power Plant Cooling Tower Lights at night on May 13, 2006.

Trojan Nuclear Power Plant Cooling Tower Lights at Night

The cooling tower would have been the tallest building in Oregon when completed in May 1972, however Portland's 546-foot First National Bank Tower (now Wells Fargo Center) was completed the same month. Since then, Portland's 536-foot U.S. Bancorp Tower and 509-foot KOIN Center have also topped the cooling tower's height. The following table shows how Trojan's cooling tower compared to other tall structures locally and around the world.

Building

Location

Height

Astoria Column

Astoria, Oregon

125'

Union Station Clock Tower

Portland, Oregon

150'

Great Northern Railway Depot Clock Tower

Spokane, Washington

157'

Arc de Triomphe

Paris, France

165'

Leaning Tower of Pisa

Pisa, Italy

180'

Coit Tower

San Francisco, California

210'

King Street Station Clock Tower

Seattle, Washington

242'

Statue of Liberty (with pedestal & base)

New York City, New York

305'

Palace of Westminster Clock Tower (Big Ben)

London, England

316'

Lewis & Clark Bridge

Rainier, Oregon

340'

Fremont Bridge

Portland, Oregon

381'

St. John's Bridge Towers

Portland, Oregon

408'

Great Pyramid of Khufu

Giza, Egypt

481'

Trojan Nuclear Power Plant Cooling Tower

Rainier, Oregon

499'

KOIN Center

Portland, Oregon

509'

U.S. Bancorp Tower

Portland, Oregon

536'

Wells Fargo Center

Portland, Oregon

546'

Washington Monument

Washington, D.C.

555'

Space Needle

Seattle, Washington

605'

Gateway Arch

St. Louis, Missouri

630'

Golden Gate Bridge Towers

San Francisco, California

746'

TransAmerica Pyramid

San Francisco, California

853'

Eiffel Tower (with antenna)

Paris, France

1,058'

Empire State Building (with antenna)

New York City, New York

1,472'

Willis Tower (with antennas)

Chicago, Illinois

1,729'

CN Tower

Toronto, Canada

1,815'

Trojan's cooling tower was not the tallest in the world, or even in the United States (though it did become the largest in the world to ever be imploded). The world's tallest natural draft cooling tower is at the coal-fired Niederaussem Power Plant in Bergheim, Germany. It is 656 feet tall, 500 feet in diameter at its base, and 290 feet in diameter at its narrowest point. The Niederaussem cooling tower is as wide at its base as the Trojan tower was tall. Cooling towers in the United States that were taller than Trojan's include those at the Limerick Generating Station at Saratoga, Pennsylvania (507 feet), the Salem Nuclear Generating Station in Hancocks Bridge, New Jersey (512 feet), the Harris Nuclear Power Plant in New Hill, North Carolina (525 feet), and the Nine Mile Point Nuclear Generating Station at Scriba, New York (543 feet).

Continue to Cooling Tower Implosion Preparation

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