Citrus: Crystal River power plant shuts down to refuel

Crystal River power plant shuts down to refuel

Plant workers take advantage of the planned shutdown to flush out radioactive grit and check the quality of the steam generators.

By JOSH ZIMMER

CRYSTAL RIVER -- In a matter of days, workers at Florida Power Corp.'s Crystal River 3 nuclear power plant will travel to the center of this 860-megawatt facility and begin performing a scientist's version of open-heart surgery on the reactor core.

Perched on a catwalk, technicians in full protective gear will mechanically lift highly radioactive fuel assemblies from their cozy bed beneath a pool of water. They will guide the 1,500-pound units through a tunnel in the water that connects to the company's spent fuel storage building.

When one-third of the reactor's innards are gone, they will be replaced with fresh fuel assemblies.

The reactor is the heart of the plant, and the fuel assemblies make it pump. They are sophisticated bundles consisting of metal frames, rods, springs and enriched uranium pellets. Grouped together by the dozens, the assemblies produce nuclear energy when tweaked by control rods, unleashing a chain reaction of neutrons within the uranium pellets.

Although two-thirds of the fuel assemblies remain fresh, that's not enough to sustain a quality nuclear reaction. So a reactor must shut down every time the plant refuels, which is typically every two years. Florida Power began powering down its reactor Oct. 1.

The utility has been performing other outage tasks since then, such as systems maintenance, cooling down the reactor and connecting a new emergency feed water pump. Company officials have a list of related projects they want to complete during the next five weeks, from flushing out radioactive grit collecting in thousands of feet of pipe to checking the quality of the plant's steam generators.

But the work is directly connected to the refueling, which Florida Power expects to cost $30-million.

"There's work going on literally all over the power plant," plant spokesman Mac Harris said. "Refueling in many ways sets the schedule for other things to occur."

The dangerous level of radioactivity emitted by the spent fuel assemblies -- and the care taken when handling them -- is a testament to the intensity of nuclear power. Until the new assemblies move in with their roommates in the reactor core, they are safe enough to be touched by human hands.

For example, workers handling uranium pellets wear cotton gloves, but that is done only to prevent their own skin oils from contaminating the charcoal-colored nuggets.

"We're not in white clothes or anything," said Elizabeth Stuckle, spokeswoman for the U.S. Enrichment Corp., the company that enriched the raw uranium for Florida Power. "The people in the pellet room wear gloves. There can be dust associated with the pellet, so we have a room sealed off. There's no radiation.

"I have stood by and touched a fuel assembly," she said.

But during the refueling workers cannot have contact with either the fuel assemblies or the pool of water in the reactor cavity. "They would experience a lethal level of radiation," Harris said.

The life of a fuel assembly starts in one of the world's many uranium mines. From there, uranium is transported to a processor -- in Florida Power's case, that is U.S. Enrichment Corp. in Bethesda, Md. -- where the uranium 235 content of the ore is raised from its natural level through a diffusion process, said Tom Wampler, project manager for fuel for Framatome Cogema Fuels.

FCF is a division of Framatome Technologies Group in Lynchburg, Va., the company that is servicing the Crystal River outage. The fuel assemblies were also constructed by Framatome, one of five companies around the country capable of doing such work, he said.

The enrichment "allows the chain reaction to go on," he said.

The enriched uranium destined for Florida Power traveled across the country to Siemens Power Corp. in Richland, Wa., where another chemical process converted it into a powder and pressed it into pellet form, spokesman Wayne Baker said. At that stage the pellets are green, but they darken and turn hard as they're heated in a furnace.

Once the pellets arrive, Wampler said, Framatome is ready to construct the fuel assemblies.

The pellets are stacked in long tubes with a spring at the end to allow the pellets to expand. The tubes are sealed, stacked vertically and bound. But they never touch each other. There has to be enough space between them for water to pass through and prevent contamination, he said.

"It's very sophisticated to get them to hold the fuel rods so they're not loose," Wampler said. "Everything has to fit just right."

Framatome, which services the entire nuclear industry, can produce two to three assemblies every day, he said.

Fuel assemblies, like other fresh fuel, do not pose a major containment issue, said Mindy Landau, spokeswoman for the Nuclear Regulatory Commission. Both the NRC and the Federal Department of Transportation monitor the shipments, but local authorities are not informed of passage routes until the trucks are transporting highly radioactive spent fuel, which is packaged in thicker, lead-lined steel containers, she said.

Framatome ships the fuel assemblies 12 at a time on a non-stop, 14-hour drive, Wampler said. The last delivery to Florida Power went out Oct. 1, he said.

Harris said the entire refueling -- the 11th since the plant opened in 1977 -- should take about one week. Once the old fuel assemblies in the spent fuel pool -- a concrete structure lined with stainless steel -- are reracked, there will be enough space to handle outages until 2016, a year before the plant's current license runs out. "We are in good shape," Harris said.