The Energy Northwest nuclear power plant near Richland was disconnected from the electric grid at midnight Friday for refueling.
Two hours later early Saturday morning, control rods had been fully inserted into the reactor core, shutting it down.
Columbia Generating Station could be producing electricity again in mid June, with the planned outage expected to last no more than 40 days.
Every other May the plant shuts down to load in new nuclear fuel assemblies and also uses the refueling to conduct maintenance that can best be done when the plant is not operating.
The plant has staffed up with about 1,200 temporary workers hired from the Tri-Cities area and across the country to support maintenance work.
The added workers are in addition to about 1,000 permanent employees at the plant.
The current outage is budgeted to cost $127 million for refueling, maintenance and capital purchases.
“We came out of our recent refuelings producing more megawatts, more reliably and at a lower cost,” said Grover Hettel, Energy Northwest chief nuclear officer. “I anticipate that trend will continue.”
Refueling planned for spring snow melt
Columbia Generating Station produced more than 9.7 million megawatt-hours of electricity during 2018, a record in its 34-year operating history.
It has the capacity to produce 1,207 megawatts, which is about as much energy as is needed to power Seattle and part of its metro area.
The refueling is planned to coincide with the spring snow melt and runoff that maximizes power output from the region’s hydroelectric dams to minimize the impact of not having the nuclear plant sending electricity to the grid.
Nuclear and hydro are the region’s only full-time clean energy resources, says Energy Northwest.
The Bonneville Power Administration markets wholesale electric power from the nuclear power plant, the only one in the Pacific Northwest, and from 31 hydroelectric projects in the Northwest.
This spring crews will replace 260 of the nuclear plant’s 764 nuclear fuel assemblies in the reactor core.
Fuel stays in the reactor core about six years, with about a third of the fuel removed in each refueling outage. The fuel that is removed is placed in a used fuel pool and will eventually be moved to dry cask storage.
Maintenance will include robotics work
“Our Energy Northwest team put forth a tremendous amount of effort to plan, set goals and prepare for a successful refueling,” Hettel said.
Planning starts years in advance of each planned outage, with an increased focus two years before the start of each refueling.
This year workers will install a 34-foot, 133-ton refurbished low-pressure turbine rotor. It’s part of the life-cycle plan to satisfy the plant’s license extension to 2043. The plant began delivering power to the region in 1984.
Workers also will use robotics to perform a generator inspection and upgrade the plant fire detection system.
In all, regular and temporary employees will complete 1,300 worker orders with more than 7,500 tasks, according to Energy Northwest.