The owner of Three Mile Island, site of the United States' worst commercial nuclear power accident, says it will shut down the plant in 2019 without a financial rescue from Pennsylvania.

Exelon Corp. said Monday's announcement comes after five years of losses on the power plant and its recent failure in an auction to sell Three Mile Island's power into the regional grid.

The Chicago-based energy company wants Pennsylvania to give nuclear power megawatts the kind of preferential treatment and premium payments that are given to renewable energies, such as wind and solar.

Nuclear power plants have been hammered by the natural gas boom that has slashed electricity prices in competitive markets.

Equipment failure and operator errors at Three Mile Island in 1979 led to partial core meltdown of a reactor. The plant's other reactor is still in use.