Richland nuclear plant powers down temporarily for routine refueling and maintenance

Lights and appliances in the Northwest are not being partly powered as usual by the nuclear power plant near Richland.

The Columbia Generating Station disconnected from the electric grid on Saturday for a 40-day refueling and maintenance outage.

About 1,350 workers have been hired locally and nationally for the outage, many of them working for the last month with the plant’s 1,100 permanent employees to prepare for the outage.

Refueling of the reactor is planned every two years to coincide with the spring snow melt and runoff that maximizes power output from the region’s hydroelectric system. It also falls between the times when electric use for heating and cooling is highest.

The Columbia Generating Station is the third-largest generator of electricity in Washington state, with its output sold at cost to the Bonneville Power Administration for distribution to Northwest utilities.

This year 272 of the plant’s 764 nuclear fuel assemblies in the reactor core will be replaced. They include four fuel assemblies taken out of service but left in the core when pinhole leaks were discovered in November.

Other maintenance and improvements are planned that are difficult to perform while the plant is operating.

Installation will be completed of a hardened containment vent to meet new requirements of the Nuclear Regulatory Commission in response to 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.

In addition, a new low-pressure turbine rotor will be installed as part of a multi-year, $32 million project to refurbish three low-pressure turbines to satisfy requirements of the plant’s license extension to 2043.

A metal ingot forged in Japan was shipped through the Panama Canal to be machined in North Carolina. The rotor, which will weigh 275,000 pounds when assembled, was shipped by train across the nation for a total distance travelled of more than 14,000 miles.

The total budget of the outage is about $135 million, including equipment purchases.

This story was originally published May 13, 2017 at 5:42 PM with the headline "Richland nuclear plant powers down temporarily for routine refueling and maintenance."