"You have four reactors and you could easily have two or three approaches to decommissioning," says Kurt Kehler, vice president of decommissioning and demolition at engineering company CH2M HILL, whose company might bid for the job. "Some where the fuel melted, you entomb. [There are] some where you can extract it and go into safe store, and then some you could recover and keep operating."
Like many of the personnel operating the U.S. nuclear fleet, the name for the end-of-life process for a nuclear power plant got its start in the U.S. Navy—to decommission a reactor is to tear it down and restore its site to one of several conditions within 60 years.
"Ideally for most utilities the intent is to remove everything from the site and restore it to other uses than power generation," says John Hickman, project manager of the reactor decommissioning branch at the U.S. Nuclear Regulatory Commission (NRC). Removal targets radioactive contamination, be that the radioactive cobalt and cesium that typically seeps into the concrete as a result of normal operations or plumes of water contaminated with tritium—the radioactive form of hydrogen—that often leaks from such power plants over the course of decades. Even so, tearing apart a nuclear reactor does not mean undue exposure to radioactivity; many forms of shielding—from concrete to cooling water itself—remain to protect disassembly workers as well as specially designed tools, such as particle-containment boxes for sawing through radioactive metals.
Right now, at least five such nuclear site decommissions are underway in the U.S., ranging from Zion nuclear power plant in Illinois to the cleanup of a sprawling nuclear bomb–making site at Hanford in Washington State. In the case of Zion nuclear waste disposal company Energy Solutions has actually taken ownership of the former power plant, through a subsidiary, and will tear it down in its entirety and ship all of the resulting waste to Utah for disposal. Specially designated landfills, such as Energy Solution's site in western Utah or Barnwell nuclear dump in South Carolina, hold the radioactive remnants from such deconstructions. "The current estimate for the Zion facility—and the amount in the [decommissioning] trust fund—is $900 million for this two-unit site," Hickman says. "The volume of material is enormous compared to past decommissions."
Energy Solutions takeover is a response to prior decommissionings, such as Maine Yankee in the 1990s, which rapidly grew in expense as workers attempted to sort radioactive material from its nonradioactive counterparts. Like Zion, the Maine Yankee decommission aimed to restore the site to a pristine condition, one in which a farmer could live on the former nuclear power plant grounds, grow crops and eat them without an "unacceptable dose" from any remaining radioactive contamination, says NRC spokesman Scott Burnell.
There are other options, of course, such as Sacramento's former Rancho Seco nuclear power plant shut down in 1989, which has now been turned into a solar farm and natural gas–fired generator. "Our regulations require cleanup of the facility to the point that when they are done you can only be exposed to 25 millirems per year from [nuclear power] plant–generated materials," Hickman says of that option. (A rem is a dosage unit of x-ray and gamma-ray radiation exposure.) And, in the case of Three Mile Island (TMI), reactor No. 2 will sit dormant until reactor No. 1 finishes its useful life, in 2034, when both will be demolished. "The advantage of doing it at that time is that any residual radioactivity associated with TMI reactor No. 2 will have decayed quite a bit," says Wayne Johnson, division manager of the Earth Systems Science Division at Pacific Northwest National Laboratory.