HANFORD — The Columbia Generating Station here is undergoing its most expensive refueling and maintenance shutdown ever as the owner of the nuclear plant tries to improve its reliability and costs.
More than 1,700 electricians, steamfitters and other skilled-trade workers have swarmed this site 10 miles north of Richland. Besides the refueling done every two years to refresh and reposition rods containing uranium, they are replacing the generator rotor and a huge steam condenser that has caused repeated shutdowns.
The $152 million cost of the refueling and maintenance work will be paid by the Bonneville Power Administration and, eventually, the 3.5 million Northwest residents who get their electricity indirectly from the federal agency. Bonneville also sells the power generated at the 31 U.S. Bureau of Reclamation and Army Corps of Engineers dams in the Columbia River Basin.
Bonneville has proposed an 8 percent rate increase for its 2012-2013 fiscal year. BPA spokesman Michael Millstein said the cost of the Columbia plant upgrades accounts for some of the requested increase.
A decision on the rates will be made in July, he said.
A 2009 Bonneville study says Columbia Station’s operating and maintenance costs were exceeding those for the 31 dams combined. The dams generate 90 percent of Bonneville’s electricity. The reactor’s 1,150 megawatts constitute the remaining 10 percent.
Since 2004, the report said, service interruptions at Columbia Station had pushed the facility to a performance ranking among the worst for 104 reactors that generate electricity in the United States.
But that was before Columbia Station completed a 505-day period of uninterrupted operation, the best since its start-up in 1984.
Columbia Station officials acknowledged the past problems, and said Tuesday the condenser project in particular should significantly improve the plant’s reliability.
The condenser removes water from steam produced by uranium fuel rods that heat reactor water up to 900 degrees. The dry steam is then fed into four turbines spinning a generator at 1,800 rpm.
But the condenser tubes installed when the plant was built in the early 1980s are brass, said Carl Golightly, who analyzes plant shutdowns for the Columbia Generating Station. Some have burst due to corrosion, which has also caused contaminated water in the reactor.
Wednesday, workers were cutting those tube assemblies loose so they can be removed through a hole cut through thick concrete walls. They will be replaced with more reliable titanium tubes.
Energy Northwest, which owns Columbia Station, has asked the Nuclear Regulatory Commission to extend the plant’s operating license through 2043. The original 40-year license expires in 2024.
Golightly said projections of the plant’s operating life were extremely conservative when it was designed in the 1970s.
“When we get to 40 years, we easily have another 30 to 40 years,” he said.
Golightly, addressing concerns raised by the catastrophe at the nuclear plants at Fukushima Daiichi in Japan, also said the plant can probably withstand earthquakes stronger than the 7.3 magnitude estimate used in construction.
A new U.S. Geological Survey analysis found earthquake fault lines that extend across the Cascade Mountains eastward as far as Pasco.
Bonneville’s Millstein said that, despite Columbia Station’s problems, the agency supports its continued operation because it remains a major source of carbon-free generation in the Northwest.
“Our main goal is a reliable, cost-effective and safe operation,” he said. “We do see the plant as an important part of the system.”