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Editor's Note: This article originally appeared in the March 2003 issue of Scientific American.
In a tidy office in the city hall in Wiscasset, Me., right around the corner from the town clerk, Judy Foss touts the virtues of an 820-acre industrial site that she plans to have available for redevelopment soon. It offers easy access by road, rail and barge and has plenty of cooling water. It is already on the high-voltage electric grid. It is just a mile from the municipal airport, the local government is stable, and the natives are friendly.
There is a catch, though. It’s radioactive. And parts of it will stay that way until at least 2023 and probably a lot longer.
The site, 40 miles northeast of Portland, is the home of Maine Yankee, one of the first large commercial nuclear power–generating stations built in this country and one of the first to close. It will also be among the first of this group to be decommissioned, an unglamorous task that was not fully thought through during the era when plants were being constructed.
Foss, a consultant, was brought in to find a replacement for the Maine Yankee plant, which, like nearly all power reactors, was the keystone of its local economy. When the plant was running, from 1972 until the end of 1996, it paid 90 percent of Wiscasset’s property taxes and provided most of the high-paying jobs. Vital as such sites generally are to their host communities, Maine Yankee, as a pioneer in decommissioning, is particularly crucial to the nuclear industry’s hopes for revival. No new technologies need to be developed to make decommissioning work. But the public and policy makers have scientific questions to weigh, including how much engineering work needs to be done and how clean is clean enough. (Whereas other countries rely more heavily on nuclear power, the American program is older, and thus decommissioning is more advanced here.)
The U.S. has 123 large commercial-scale power reactors that have ever operated, including the 103 currently open. Several companies that run them have talked about building new ones, a notion that has garnered recent national attention [see “Next-Generation Nuclear Power,” by James A. Lake, Ralph G. Bennett and John F. Kotek]. If the industry is not, in fact, dead (a debatable point, because no plants have been ordered since 1973 except those that were later canceled), then among the hurdles that must be overcome before building new plants is successfully decommissioning the old ones. The industry has to show that the acreage that once housed a plant is not a permanent industrial sacrifice zone and that it can be returned to the clean, “green-field” status essential for most kinds of redevelopment.
Decontamination in Action As it turns out, “decommissioning” does not mean “neutralizing”; it means moving radioactive material from one place to another. At Maine Yankee, that means 233 million pounds of waste, of which 150 million pounds is concrete. A little more than half the waste, 130 million pounds, is radioactive. Younger plants have 50 percent more generating capacity than older ones, and their debris volume will be somewhat larger.
There was a plan to sharply cut the amount of waste to be moved around. Originally, Maine Yankee’s owners wanted to “rubbleize” the concrete and dump it into the building’s foundation, then pour in more concrete to make a monolith. But local law blocks such burials of nuclear waste without a statewide referendum. (The Nuclear Regulatory Commission, or NRC, still considers on-site burial a useful option, but so far no civilian facility has tried it.) So instead the plant is literally going away, at a rate of about a trainload a week. In doing so, it is demonstrating both the pitfalls and the ease of decommissioning.
At the site, on a saltwater peninsula south of town where herons nest on power pylons, giant earth-moving equipment has torn up the nonnuclear buildings and loaded the concrete and metal onto railcars. The open gondolas are headed for nuclear dumps in South Carolina or Utah or for a nonnuclear landfill for construction debris in Niagara County, New York.
The anatomy of the plant is laid out a bit like that of a frog being dissected in a high school biology lab. During this visit the massive containment dome stands at the edge of a tangle of wreckage that used to be the turbine hall, where the energy in nuclear-heated steam was converted into torque for an electric generator. The path through which the reactor’s product once traveled is plainly visible. Three pipes, each about the size of a water main, emerge from the containment building wall. They conveyed 500-degree-Fahrenheit steam to the turbines at more than 1,000 pounds per square inch of pressure. Underneath each pipe is a larger one that carried water back again for reheating. These were once monitored intensely for signs of radioactive contamination or fluctuations in temperature or flow. Now they sit open to the breeze, waiting their turn to move into the gondolas.
The dome is a tougher challenge. It is a typical containment for a large nuclear plant, big enough to enclose a high school gymnasium. It is four feet thick at the bottom, tapering to two feet at the top, with concentric layers of steel reinforcing bars. It weighs about 62 million pounds.
To get the major components out of the dome, workers used a diamond saw. The concrete on the outside surface of the dome has the texture of a driveway. But where blocks have been removed, it feels as smooth as a lacquered coffee table. “Making the first few cuts into a nuclear-related safety system was very difficult to do, knowing it would never come back,” says Michael J. Meisner, the chief nuclear officer on the project. In what was designed to be airtight even at 50 pounds per square inch of overpressure, a rough plywood door, fastened shut with a padlock, gives a little in the occasional breezes.
Although it seems counterintuitive, one of the easiest tasks thus far has been removing the main nuclear components, such as the reactor vessel and the three steam generators at the heart of the plant. They were taken out whole. In the case of the reactor vessel, a giant carbon-steel pot with a stainless-steel liner, the “internals”—the metal frame that held the core and channeled the water on its serpentine path—were chopped up with water jets and cutting tools. The work was done by remote control and underwater. (Tellingly, the American reactor industry did not survive the full life cycle of the first big plants; a French company, Framatome ANP, provided the technology for slicing apart the big metal components.)
Then the reactor core was filled with cement, or “grouted” in industry parlance, to reduce the possibility of parts loosening in coming centuries. The vessel was lifted out in preparation for a barge trip to a low-level-waste dump in Barnwell, S.C. Less active material goes to Envirocare in Clive, Utah, about 85 miles west of Salt Lake City. A third dump, on the federal government’s Hanford nuclear reservation in south-central Washington State, has also been used for some decommissionings. The environmental benefit to moving the material is that it is easier to guard and monitor in a central location.