(FORTUNE Magazine) – America's best-known nuclear plant is on the block. A mere $600 million, and Three Mile Island can be yours. But you'd better hurry; a deal's in the works.

This isn't the infamous Unit 2 reactor at TMI, the one that made meltdown a dinner-table topic in 1979. That $1 billion monument to technological and human imperfection sits silently, awaiting the day sometime in the next century when it will be dismantled and most likely landfilled out West. A ton of melted fuel (the other 99 have been hauled away) still coats the guts of the padlocked reactor, too diffused--and too radioactive--to be removed now.

No, the FOR SALE sign is hanging on TMI Unit 1, the little reactor that just works...and works. A veritable Cal Ripken, according to owner GPU Inc., Unit 1 recently broke worldwide performance records and ranks No. 2 in the U.S. for efficiency over the past three years.

For those reasons and more, Three Mile Island, located south of Harrisburg, Pa., may be the first of the nation's 109 operating reactors to change hands. Experts predict two dozen others may also have new owners within a decade, as the utility industry restructures in the face of deregulation.

Who'd invest in a finicky power source that has driven owners into bankruptcy, has propelled electricity rates sky-high, and still faces questions about what to do with all that radioactive waste? Well, when reactors run properly, they produce lots of power relatively cheaply. And utilities that operate multiple reactors can conceivably achieve economies of scale not attainable by companies with just one or two, such as GPU. (GPU, based in Parsippany, N.J., is getting out of the power-generation business entirely to focus on transmitting electricity to its customers in Pennsylvania, New Jersey, Australia, and Britain.)

PECO Energy of Philadelphia, the most frequently mentioned potential buyer of TMI, produces 43% of its electricity from nuclear and has said it wants to dramatically enlarge its reactor stable. In September the company formed a joint venture with British Energy to acquire and operate U.S. nuclear power plants.

"Nuclear has a poor image with many people," says Dickinson M. Smith, CEO of the new company, AmerGen Energy. "But if we do acquisitions and demonstrate we can improve safety and performance, we will prove it can be a good business to be in."

Smith won't discuss AmerGen's interest in TMI. GPU, meanwhile, isn't identifying suitors. (Duke Power and Entergy Corp. also have been mentioned as possible buyers.) GPU does say a confidentiality agreement has been signed with somebody, and discussions are ongoing.

Whoever ends up with the plant may get a workhorse--but not an entirely worry-free one. On Oct. 9 the Nuclear Regulatory Commission socked GPU with a $210,000 fine for a string of safety violations at Three Mile Island Unit 1. Just a little reminder that this is, after all, a nuclear power plant.

--Susan Q. Stranahan

SUSAN Q. STRANAHAN is a staff writer for the Philadelphia Inquirer.