The Columbia Generating Station ended its fiscal year in June tallying up the second-highest generation since it began operating in 1984, despite its most challenging 12 months in recent years.
The nuclear power plant near Richland, operated by Energy Northwest, generated 9.6 million megawatt hours of electricity, just short of the 9.7 million megawatt hours generated two years ago.
The refueling outage that started in May 2015 was a primary contributor to the near-record production year, said Brad Sawatzke, Energy Northwest chief nuclear officer.
Not only was a third of the plant’s fuel replaced, as is done every other year, but workers used the shutdown of the plant to install a new feedwater flow meter, which measures the amount of water flowing through the reactor core. The more water that can be used, the greater potential power output.
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Over time, the calibration of the previous flow meter degraded and water flow was limited to make sure it remained with new limits.
Being able to allow more water flow to the reactor core has increased output by about 28 megawatts.
40,000 number of additional homes Columbia Generating Station can produce electricity to serve
“Those are megawatts we will have for the rest of the plant life,” Sawatzke said.
Add to that the 20 megawatts gained when the main steam condenser and other projects were completed in the 2011 refueling outage, and the plant is capable of putting enough electricity on the the grid to serve about 40,000 more homes.
Unfortunately, the plant was offline more than planned in the fiscal year just ended. First, the refueling outage lasted several days longer than planned. Then it operated at only partial power for about three weeks while a stuck, 27-inch valve was freed.
In November, two pinhole leaks were found in fuel, with the cause not yet determined. The plant was able to continue operating safely, but the pinholes will result in a slight reduction in reactor power just before the next scheduled refueling outage in May 2017, according to Energy Northwest.
The next two months, December and January, the plant set production records.
But then in March, the plant had its first scram, or unplanned shutdown, in more than six years. A valve being tested had not been properly isolated and the control room received an indication that a system used to cool large pumps and other equipment had lost power.
We saw more challenges than in previous years, but the ability to manage these challenges and still have the second-best ever year is a testament to how strong our team is.
Brad Sawatzke, Energy Northwest chief nuclear officer
Scrams are not uncommon. The nation’s nuclear power plants average a little more than one scram per plant every two years. But the scram did reduce the year’s generation.
“We saw more challenges than in previous years, but the ability to manage these challenges and still have the second-best ever year is a testament to how strong our team is,” Sawatzke said.
Jason Simmons, a maintenance manager at the Columbia Generating Station, says he’s seen improved teamwork at the plant in the last five or so years.
Recent changes have been made to better manage maintenance projects that come up in addition to regularly scheduled maintenance, he said.
After each 12 weeks of planned maintenance work, the next week is used to address the maintenance backlog, with engineering and maintenance divisions working together to come up with a list of those that are most important to address first.
“It shows in our performance,” Simmons said. “It is one of the things that has improved equipment reliability.”
It also has contributed to quality of life for employees like Simmons. “When the plant is running good, we are not out there every weekend,” he said.
It also was a good year related to limiting radiation exposure, with workers using good practices, said Denise Brandon, an engineering manager. The fiscal year set a record for the lowest collective radiation exposure at the plant.
The fiscal year just started includes a refueling outage next May, so it will not set a new generation record. But the year holds promise to set a new generation record for a refueling year, Sawatzke said.