Tri-Cities nuclear power plant back on the grid early

The commercial nuclear power plant near Richland reconnected to the electric grid at 1:43 p.m. Monday, completing its planned refueling and maintenance outage more than two days early.

“The tremendous amount of planning that went into this outage paid off for everyone,” said Brad Sawatzke, chief nuclear officer for Energy Northwest, which operates the Columbia Generating Station.

Workers at the plant more than doubled with an additional 1,350 temporary workers. Some were local residents and others came temporarily to the Tri-Cities from across the nation for weeks or months, filling RV parks and motels and boosting business at local restaurants and stores.

During the 37.5 day outage, workers installed a new low-pressure turbine rotor, part of a $32 million project to refurbish the three low pressure turbines to satisfy conditions of the nuclear power plant’s license extension to 2043.

The 275,000-pound rotor will be sent to North Carolina through the Panama Canal on a 14,000-mile round-trip to be refurbished. It will replace another rotor during the plant’s next refueling outage in two years.

The final work was completed to install a hardened containment vent to meet new requirements of the Nuclear Regulatory Commission after the Fukushima, Japan, nuclear disaster.

The system will allow a direct means of venting an area of the Columbia Generating Station to an outside containment structure in the event of an accident beyond what the plant was built to withstand. “Hardened” means the vents can withstand the pressure and temperature of the steam generated early in an accident, or possible fires or small explosions if they are used to release hydrogen later in an accident.

Workers also switched out 272 of the plant’s 764 nuclear fuel assemblies during the outage and took out two defective fuel assemblies. Pinhole leaks were discovered in the fuel in 2015, likely because of a small amount of foreign material in the cooling water in the reactor core.

Equipment replacements, refurbishments and upgrades between 2010 and 2015 increased the plant’s gross generation capacity from 1,150 megawatts to 1,190 megawatts, roughly the electricity needed for a city the size of Seattle.

The capacity should increase again because of recent approval to operate closer to regulatory limits because technology installed in 2015 allows more precise measurements of power levels, according to Energy Northwest.

The plant will take several days to reach full power as systems are tested and started up.

Electricity from the plant is sold at cost to the Bonneville Power Administration, which distributes it to 92 Northwest utilities, including Tri-City utilities.

This story was originally published June 19, 2017 at 6:48 PM with the headline "Tri-Cities nuclear power plant back on the grid early."