These days, a worst-case scenario for this facility would be a natural gas explosion. Potentially deadly, yes, but a far cry from the days when this was a nuclear power plant.
Plans for Fort St. Vrain date back to the 1960s, and although its brief life as a nuclear reactor saw as many failures as successes, there are several firsts involved with the plant:
It was Colorado's first (and, to date, only) commercial nuclear power plant.
It was the first plant in the United States built as a high-temperature, gas-cooled commercial reactor. It used helium, rather than water, to cool its 1,400-degree core and transfer heat to the steam generators that powered turbines, which created electricity.
Its design was one of 81 reactor designs that were being tried by utilities around the U.S., and at the time, this design was touted as the safest in the nation.
After the plant was shut down by Public Service Co. of Colorado in 1989, the company, wanting to recoup some of its losses, submitted plans to recommission the facility as a natural gas-powered electricity plant, which is the way it operates today. It's believed to be the only U.S. commercial nuclear power plant to have been decommissioned and brought back to life as something else.
So while the images from Japan's Fukushima Daiichi nuclear plant are giving many people the shivers, those living among these bucolic rolling hills and pastures need have no fear that something similar could happen here.
And a couple of longtime residents say that even when Fort St. Vrain was a nuke plant, it didn't bother them too much.
"I was teaching (grade school) at the time, and the thing I remember most about it is they would come into our schools and put our children through paces," said Dorothy Brotemarkle, a Platteville resident who moved to the area in 1939.
She remembered one daylong drill in which all the students were "evacuated" by bus and taken to Fort Lupton, where they had to remain for a few hours.
She remembers the biggest challenge that day was keeping the kids quiet.
Weld County Commissioner Doug Rademacher's fourth-generation farm is about 4 to 5 miles from the Fort St. Vrain plant, and he remembers being a kid when it was under construction in the late 1960s.
"They gave us all these little radios, the alert radios, in case they did need to send out an alert," Rademacher remembered.
He and Brotemarkle -- who both said they still have their alert radios -- say they don't remember any pre-plant controversy. Public Service Co. routinely had meetings, they said, letting the neighbors know what was going on and what was being planned.
"People were not alarmed," Brotemarkle said. "They gave us literature and radios for every house. And, of course, it meant employment for people."
Added Rademacher, "My dad went to a lot of those meetings, and he was very outspoken, so if there was a problem, he would've spoken up."
So in 1973, PSC received its operating license for the 330-megawatt power plant. It finally got it up and running in 1976 -- sort of.
That was the year the first commercial electric power from the reactor was generated, but it wasn't until 1979 that commercial operation of the plant officially began.
Problems plagued the plant from the start. A website, fsvfolks.org, has a detailed history of the plant, from its earliest planning stages to its conversion to a natural gas plant.
Ted Borst started working for PSC in 1980 and now oversees the nearby facility where spent fuel from the reactor is stored.
"Most people didn't realize we made it to 100 percent power (capacity), but it only lasted a day or two and then we had to take it back down," Borst said, adding that the design of the plant -- which was 1960s technology -- was, in his words, a "little too delicate."
Mark Stutz -- a spokesman for Xcel Energy, which acquired PSC -- started with the company in 1988, a year before Fort St. Vrain was shut down. Before that, he covered the plant as a reporter for the Greeley Tribune.
"Fort St. Vrain was really like two entities -- the nuclear side and the non-nuclear side, the turbine generators," Stutz said.
"The secondary, non-nuclear side had all the problems," Borst added.
During the 10 years it was operational, Fort St. Vrain produced an average of only 14.6 percent of its capacity. By 1988, PSC had had enough, having invested some $240 million in the plant. Its board of directors announced a decision to shutter the plant in 1990.
They found their hand tipped earlier than that, however, when a routine inspection in August 1989 found a problem, which led to more inspections that found more problems. The PSC board pulled the plug on the plant on Aug. 29, 1989.
A new life
But PSC didn't want to just give up on the millions it had sunk into the plant's infrastructure.
Instead, it got permission from the federal government and the state's Public Utilities Commission to decommission the plant, clean it up and convert it to a natural gas-powered plant.
At a cost of $340 million, PSC had the 11-story concrete reactor, with its 15-foot-thick walls, removed. It shipped leftover reactor parts to a disposal site in Washington. The Nuclear Regulatory Commission studied the facility for a year, making sure no radioactive material was left.
Today, the reactor building sits empty, except for a half-million neon sticky notes on the walls, the ceiling, the floor -- everywhere -- indicating everything had been checked and was clean.
Even as it was decommissioning the nuke part of the plant, PSC already had plans for the fuel.
When the plant was first announced, PSC signed a contract to have spent fuel from Fort St. Vrain -- uranium and thorium -- sent to a government facility in Idaho. But Idaho was balking and tying the matter up in court.
So PSC spent $25 million to build the Independent Spent Fuel Storage Installation next to Fort St. Vrain. That building, with its 3-foot-thick concrete walls, today houses 822 kilograms of spent uranium-235 and 13,903 kilograms of spent thorium. The fuel mix is stored in 300-pound graphite blocks that are inside a steel containment area, according to Borst, who now works for the company the Department of Energy contracts with to protect and monitor the fuel.
DOE took over management of the building after PSC built it. It can withstand tornadoes, earthquakes, small planes, and -- thanks to an array of stationary barriers and on-site armed guards 24 hours a day, seven days a week -- attempted break-ins or sabotage.
Borst said the original lease for the storage facility ends in November but the DOE has asked for, and will likely get, a 20-year extension of that lease, to 2031.
The state of Colorado made the DOE sign an agreement long ago that called for fines of $15,000 a day for each day the fuel remained at the site past Jan. 1, 2035.
In the meantime, Borst said, that fuel isn't going anywhere. But given the difficulties Fort St. Vrain had while it was in operation, he said, only about 10 percent of the energy-producing capacity of the uranium was used.
"My hope is we can still recycle that," Borst said.
There have been only two high-temperature, gas-cooled commercial reactors built elsewhere in the world since Fort St. Vrain. They are similar, but not identical, in design to the one here, he said.
And as for the spent fuel-storage building, the ISFSI, it's a unique animal in itself.
"There's another one in Hungary, but those are the only two fuel-storage facilities of that design in the world," Borst said.