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NUCLEAR PLANT GETS FUEL, FIXES

October 1, 2008 12:15 am

By RUSTY DENNEN

Inside North Anna Power Station, technicians remotely monitor the activities of workers wearing white protective suits in what looks like an enormous equipment-filled cave.

A crew works inside the reinforced-concrete dome, or containment area, that houses Unit 2's nuclear reactor on Lake Anna in Louisa County.

Except for certain times such as this, it's off-limits to workers.

Peering at a bank of video screens, Trey Perrin and Mark Detrick keep track of those in the vicinity of the reactor and other radiation sources.

The scene is but one dimension of refueling--a routine but critical task at North Anna and the rest of the nation's 104 commercial nuclear power plants.

Like the family car, nuclear reactors must be refueled. Every nine months, one of North Anna's two 921-megawatt reactors is shut down for that purpose, while other maintenance and repairs are done.

Unit 2's outage began Sept. 15, and the refueling process won't be completed until mid-October.

This refueling is all the more complicated because a massive generator is also being replaced on Unit 2, which began operation in 1980.

ORCHESTRATED EFFORT

Eric Hendrixson, the plant's director of station safety and licensing, says refueling has changed little since the first reactor went online here in 1978, but that technology is making it faster and more efficient.

"You still need to refuel; physics is physics," Hendrixson said. "Rotating equipment still wears out"

The refueling and generator project will take the same amount of time as a typical refueling.

"It's well-planned and orchestrated. It's not something we wake up one morning and say, 'Hey, let's have a refueling outage,'" he said.

"You're laying out large pieces of it, saying, 'OK, we're replacing a generator or turbine, or upgrading components, and we slowly work our way through."

The outage is a window of opportunity for equipment maintenance and testing that can't be done when the reactor is running.

For each refueling, "We bring in anywhere from 1,000 to 1,200 supplemental contract employees"--mechanics, electricians, welders, scaffold builders, for example--who do specialized work, he said. Many travel from one refueling to another throughout the country.

That's in addition to about 850 employees who typically work at North Anna.

Labor accounts for about 60 percent of the overall cost. "The fuel itself is pretty insignificant," Hendrixson says.

SEASONAL OUTAGES

Dominion plans its refueling outages for the spring and fall--when electricity demand is lowest. That way it doesn't need to produce electricity from more expensive fuels such as natural gas or oil.

Hendrixson says there are two goals: "Keeping in our time frame, and making sure we've done the maintenance and testing" to ensure Unit 2 will stay online until the next refueling.

"The worst thing you can do is be here on a January day when it's 12 degrees outside with everybody's heat pump going, and somebody didn't assemble a pump right and it takes the [unit] offline costing customers more money."

Page Kemp, a nuclear engineering supervisor at North Anna, said all work--whether in the reactor containment dome, or on a valve or steam pipe component--is carefully performed and monitored.

"We have highly qualified staff to ensure it's done properly so we don't end up with parts on the table when it's over."

FREQUENT INSPECTIONS

Each of Dominion power's four nuclear plants--North Anna, Surry on the James River, Millstone in Connecticut, and Kewaunee in Michigan--have in-house inspectors monitoring the process. And each plant has two Nuclear Regulatory Commission resident inspectors.

Scott Burnell, a spokesman for the NRC, said there are frequent inspections and "outages are a very good time to do those because more of the plant is accessible During the course of operations you notice things" that need to be refurbished or repaired, "and it's a perfect time to go through that list of getting things back to shipshape."

A serious problem at the Davis-Besse plant in Ohio was uncovered during a refueling outage in 2002. Boric acid from a leaking nozzle had corroded the reactor lid, prompting lid replacements across the country--including at North Anna.

Burnell said a major component replacement--such as a generator--draws extra attention from NRC inspectors because overall plant safety could be affected.

Hendrixson said the generator and its three turbines take the most time to maintain because they are large components with exacting tolerances. The turbines and generator for Units 1 and 2 take up an entire building in the plant.

Unit 2's generator, consisting of a stator and rotor and weighing about 1.5 million pounds, is being replaced for the first time.

"You do this about once every 30 years," Hendrixson said. The old one will be refurbished and installed in Unit 1.

Among thousands of items on the outage check list: "Periodically you have to take the [turbine] blades out and have them refurbished or replaced. You have a plethora of valves that need to be reworked, and a nuclear power plant has to do a lot of testing."

Said Hendrixson, "We want everything done as efficiently as possible, but we also want to make sure [Unit 2] runs 17 months without a hiccup."

Rusty Dennen: 540/374-5431
Email: rdennen@freelancestar.com