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News

Utilities Service Alliance fleet members rallied to support Columbia Generating Station repair options of a reactor feedwater valve in July. After Columbia’s refueling and maintenance outage, the plant was unable to return to full power due to one of the 24 inch feedwater discharge isolation gate valves remaining closed resulting from a stem-disc separation (Reactor Feedwater Valve 102A).

The Columbia team expanded to USA fleet members to research methods to open the valve without having to take it apart, all while keeping the unit on-line at just under 70 percent power.

“We were experiencing 100 plus degree temperatures in the Pacific Northwest so Bonneville Power Administration asked us to hold power during the heat wave. This gave us an opportunity to look for innovative ways to address the problem,” said Brad Sawatzke, chief operating officer.

After a few days reviewing the available options, the Columbia team selected a “hot tap” route where two holes would be drilled into the bottom of the valve (which is actually oriented pointing up) to accept two pushrods that would be utilized to unseat the wedge and open the valve.

A team of departments from across the site and various vendors began designing, fabricating and testing the device that would ultimately drill the two holes into the 4 inch thick valve and drive two 2-1/2 inch thick rods through the hot taps to push open the valve. This technology had been used before to open valves outside the industry, but never on a valve of this size. As such, the First of a Kind (FOAK) evolution received a great deal of scrutiny, challenges and detailed analysis prior to implementation.

On July 23, the team successfully unseated the 2,000 pound valve wedge, opened the valve and safely returned the plant to 100 percent power.

“The engagement of everyone throughout the station and the USA fleet helped us solve this unique problem,” said Grover Hettel, vice president of Operations.

Columbia Generating Station Mechanics Todd Parker and Jason Presnell conducted preparation work on a mock up reactor feedwater valve.