It will probably be years before agreement is reached on the rest of the issues.
The settlement - involving radioactive leaks from spent fuel pools at the Indian Point plant - came just before the start of federal hearings on whether the plant deserves licenses for 20 more years of operation.
For the people who want to shut down the plant, the hearings have been a long time coming. Blocking the licenses has long been the focus of environmentalists and politicians - including Gov. Andrew Cuomo - who have campaigned against the plant, on the Hudson River in Buchanan, 35 miles north of Manhattan.
Anxiety climbed after the 9/11 attacks, when one of the hijacked planes flew right over the nuclear plant on its way to the World Trade Center, and again after the 2011 quake-and-tsunami nuclear disaster in Japan.
Opponents have argued that the threat of terrorism or accident is too great at a nuclear plant so close to the nation's largest city.
"My point has always been safety first, and the reward doesn't justify the risk," Cuomo said last year.
The Nuclear Regulatory Commission has found repeatedly that Indian Point operates safely, and its staff has issued reports favoring the license application.
But the state and two environmental groups challenged the renewals on 10 issues, of which nine remain after the settlement announced Monday. Under the agreement between the environmental groups and plant owner Entergy Nuclear, Entergy will establish a third sampling station in the Hudson River and post sampling data on a public website.
The agreement has to be approved by the three hearing judges from the Atomic Safety and Licensing Board.
The first issue before them Monday is whether corrosion in pipes and elsewhere can be safely managed for 20 more years.
Other issues include decontamination after an accident, the cost of human exposure to radiation and property values.
Not on the agenda are plant security and the difficulty of evacuating such a densely populated area - "the issues people really care about," says Phillip Musegaas, a program director at the environmental group Riverkeeper. The NRC says those topics are continually studied and are not germane to relicensing.
Nevertheless, the challengers have high hopes, although the NRC has never refused a plant's renewal license.
"I think this really spells the end of Indian Point," said Robert F. Kennedy, chief prosecuting attorney for Riverkeeper, one of the groups challenging the licenses. "The noose is closing."
Entergy is confident the licenses will be approved.
"These are issues that we're pleased to have a chance to discuss in this administrative setting," spokesman Jerry Nappi said. "We feel we have a sound technical basis on each issue."
Besides Indian Point, eight other plants with 11 reactors are currently seeking renewals. They include the Davis-Besse plant near Toledo, Ohio, which was shut down for two years because of what the NRC called the most extensive corrosion ever found at a U.S. nuclear reactor.
Last year, the NRC approved a new license for the Vermont Yankee plant in Vernon, also owned by Entergy. The state tried to shut it down, but a federal judge ruled for the company. Vermont is appealing.
The two reactors at issue in New York - Indian Point 2 and Indian Point 3 (Indian Point 1 was mothballed in the 1970s) - have 30-year licenses that expire in 2013 and 2015, respectively. But both sides agree that the first date, and possibly the second, will come and go before the new licenses are settled.
That's because these hearings will stretch into next year, judges usually take months to rule, appeals are inevitable and the NRC declared in June that it will make no final decisions on licenses until after a two-year study of its nuclear waste rules.
"You can just do the math and see that this is not going to be a matter of months," NRC spokesman Neil Sheehan said.
Musegaas said: "We hold no illusions about closing Indian Point in 2013. To us this is the beginning of the end of a long process."
No matter how long it takes, under NRC regulations, Indian Point can keep running until there's a final decision, expired licenses or not.
The plant's opponents have a kind of ace in the hole unrelated to the federal hearings. The state has denied Indian Point a water quality permit, saying that by drawing in Hudson River water for cooling, it kills billions of fish and eggs.
Although nuclear plants are regulated by the federal government, not the states, the NRC has said it cannot issue a new license unless Indian Point has the water permit. Entergy says the alternative, building cooling towers, would cost it $1.5 billion. It is appealing the state decision.
The potential closing of Indian Point, which provides about a quarter of the power used in New York City and Westchester County, has fostered a succession of studies on how its 2,000 megawatts would be replaced.
The industry warns of brownouts, pollution, job cuts and higher electric bills. Environmentalists see an opportunity for turning to renewable sources. Cuomo said: "We can retrofit old plants, we can site new plants, we can improve transmission lines. So if we want to find replacement power, we can."
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