The Prairie Island nuclear plant is big. This one plant, on an island in the Mississippi River near Red Wing, supplies one-fifth of the electricity used by Xcel's customers.
It's protected by layers and layers of security. Some of them were added after Sept. 11. There's a thorough search of the car, concrete barriers to slow the approach to the plant, and inside, it's like airport security, with an extra thrill. This metal detector booth blasts a jet of air at you; it helps detect explosives.
The main buildings are grouped together on the bank of the river. One building is connected to two silos approximately the height of a six-story building. That's where the two reactors are. Four long rows of cooling towers send wisps of water vapor into the blue sky. Right in front of us there's a gigantic tower with electric lines at the top.
"This is unit two, this is where the power comes out of the generator..."
Xcel manager Scott Northard is going to show us around.
"...it goes through that transformer and we step the power up to 345,000 volts, and the 345,000 thousand-volt power goes out to the grid through our substation."
It all starts in the reactors, where uranium atoms are split in a controlled reaction. That produces a huge amount of heat, which boils water and turns it to steam. The steam spins turbines, which run generators, which produce all that electricity. Enough for more than a third of the homes in Minnesota.
Each generator is about the size of a railroad car. The furious work going on inside is hidden by a steel housing painted bright orange.
"You can see the shaft rotating: it rotates at 1,800 revolutions per minute," says Northard. "There's actually 3 turbines in a row all connected together to spin this large generator, and this generator weighs about 200 tons. It takes a lot of work to keep this turning 24 hours a day, 365 days a year."
At the heart of all this work is the control room.
Computer monitors show what's happening with the various components of the plant.
One wall is covered, floor to ceiling, with mint-green metal cabinets full of gauges, meters, dials, buttons and switches.
A half-dozen people are watching the computers and testing equipment that's out of service at the moment.
"We are always doing preventative maintenance to make sure that everything is running the way it should," Northard says. "And that all requires testing, just to verify that."
I ask, only half-joking, "So nobody goes to sleep here?"
Northard says no, not even at 3:00 in the morning.
Among other things, the computers monitor the pumps that pump the cooling water.
There are three separate water loops. One cools the fuel rods, another is the steam that runs the turbine. And the third pumps water from the Mississippi River to cool the steam.
Last week, one of the pumps shut down automatically when it sensed an electrical problem. That caused the reactor to shut down. It's an example of the safety mechanisms built into in the system.
Xcel says the plant is safe. But like all the nuclear power plants in the country, Prairie Island routinely releases small amounts of radioactive materials.
Both Xcel and the Minnesota Department of Health monitor the air and the Mississippi River near the plant. The Health Department also tests well water, and milk at a nearby farm. They find very small amounts of radiation -- not significantly different from the background radiation we're all exposed to.
The federal government has yet to figure out what to do with the waste from the country's 104 nuclear power plants. If Prairie Island is to go on operating, it needs a place to put its spent fuel.
Xcel wants to add more casks to the 24 it already has sitting on a concrete pad near the plant. The Minnesota Legislature approved this storage site back in 1994, after a huge battle. At the same time, it prohibited new nuclear plants in the state.
The steel casks are surrounded by three tall chain link fences topped with barbed wire, and an earthen berm 20-feet high.
Xcel's manager of nuclear regulatory policy, Terry Pickens, says the casks are filled with helium.
"We have a continuous monitoring system on the seals on those casks, that's looking at the pressure of the helium, to ensure that there's no leakage occurring from the casks, so we know that those casks are sealed all the time."
Pickens says Xcel regularly inspects the casks for signs of aging. He says with proper maintenance they should last indefinitely.
Back in the early 70s, when the plant was built, it wasn't set down in the middle of nowhere. There was a community here then, and there still is now.
Just four blocks from the plant, modest homes sit in the shadow of the giant towers holding up the high voltage power line that stretches off to the horizon.
Four hundred members of the Prairie Island Indian Community live here.
The tribe fought hard against storing nuclear waste in their backyard in the 1990s. But they lost. And now they're opposed to adding more casks.
Some tribal members talk about moving away. But Posie Johnson says she'll never move.
She lives right across the street from a tower that looks like an erector set on steroids. She's afraid someday it could come crashing down on her house.
"When it's windy, you can just hear it squeaking and rattling, and I always lay in bed, [thinking] 'God, I hope the wind blows away from the house,'" she says. "So I'm glad when the wind comes from the north or the west, because then it's going to go that way and not this way. It's on my mind a lot."
Johnson and other tribal members say they're not notified when anything goes wrong at the plant, and they feel vulnerable. Xcel says it follows government rules for community notification, and tries to let community leaders know about noteworthy events.
"They always say there's an escape route, but we got only one route out of here, and it's this road here," she says. "And if there was a train going by, forget it. We'd be stuck here."
Xcel has funded a feasibility study for an overpass over the railroad tracks.
Freeman Johnson delivered supplies to the plant when it was under construction. Now, he worries about his family's safety, and the tribe's livelihood. It depends heavily on visitors to the Treasure Island Casino.
"It probably is a safe place right now, but when you buy a new car, and you drive it 20 years, it's done after 20 years, right?" Johnson says. "We're saying that even though they may have upgraded internal equipment, the outside equipment which protects us from whatever they got, has to deteriorate somewhat."
Johnson and other tribal members say more people are getting cancer now. The Minnesota Department of Health says the population is so small, it's impossible to measure any trends.
The Indian community will be watching closely as state and federal regulators study Xcel's applications to extend the life of the power plant, produce more power, and store more waste.