PPL Corp. said today it might someday want to form a joint venture to build a third nuclear reactor at its Susquehanna power plant near Berwick, Luzerne County.

To keep that option open, PPL has told the U.S. Nuclear Regulatory Commission that it intends to apply for a combined construction and operating license for a third unit.

Just going through the licensing phase would cost PPL an estimated $70 million.

But a decision on whether to actually build that reactor could be as long as four years away, the energy company said. PPL declined to estimate the cost of building the third unit.

At the same time, said PPL, it is looking at buying or building more capacity that generates electricity with coal, hydro, natural gas and renewable resources.

If the company goes with another nuclear unit, it will only do so with a partner, "given the market, construction and regulatory uncertainties, along with the large (cost)," said James H. Miller, PPL's chairman, president and chief executive officer.

Miller noted in a prepared statement that with growing demand for power and rising concern over global warming, "it absolutely makes sense to create this valuable option — for the electricity users in the mid-Atlantic region and for the shareowners of PPL."

Susquehanna is a 2,360-megawatt, two-unit power plant, PPL's largest. PPL said last October it will invest $240 million to add 205 megawatts to their combined capacity.

By filing a letter of intent with the NRC, PPL has ensured that it has a place in the licensing process and preserves the possibility of obtaining certain federal tax credits and loan guarantees.

PPL is among 16 companies to recently state that it may want to add a nuclear generating unit at an existing power plant.