he nuclear reactor known as Indian Point 2 sits beside the Hudson River about 30 miles north of New York City. It has the worst safety rating of all 103 nuclear reactors in the United States. And of all the U.S. reactors, it's located in the most densely populated region.

That is not a good combination of circumstances.

Concern over the plant's continuing safety problems has heightened since Sept. 11. Increasing numbers of residents and elected officials are coming to the conclusion that the possibility of a terrorist attack or a catastrophic accident at Indian Point is a risk that is not worth taking. They believe it is time for the Indian Point complex with its two reactors — Indian Point 2 and the less troublesome Indian Point 3 — to close.

In February 2000 an accident at Indian Point 2 resulted in the discharge of 20,000 gallons of radioactive water. Officials said the radiation released was not a threat to public health, but the reactor was closed for nearly a year. Last December, four of seven control room crews failed to pass their annual qualification exams. That same month the reactor shut down automatically after an electrical connection to the plant's turbine switched off unexpectedly. Leaks, malfunctions, human errors — it's always something at Indian Point.

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Casualties from a worst-case scenario at the complex would dwarf those of the attack on the World Trade Center. A 1982 study commissioned by the U.S. Nuclear Regulatory Commission found that a meltdown at Indian Point 2 could cause 46,000 fatalities and 141,000 injuries in the short term. The potential casualties from a meltdown at Indian Point 3 were even worse. Long-term, the deaths from cancer resulting from an Indian Point catastrophe would likely be horrendous.

The casualty estimates are conservative. The population in the region is greater now, and evacuation plans are pathetically inadequate.

I called the Nuclear Regulatory Commission this week to ask about the safety ratings at Indian Point 2. A spokeswoman, Diane Screnci, said the commission did not rank plants. But it does conduct inspections and issue findings that are graded using the colors green, white, yellow and red. Green is the safest category and red the least safe.

Indian Point 2 is "currently the only plant with a red finding," Ms. Screnci said. She characterized the red finding as highly significant and said Indian Point 2 continued to receive "increased N.R.C. attention."

A serious accident or even a terrorist attack is no guarantee that the worst will happen. But we all learned as the World Trade Center vanished on Sept. 11 that the worst can happen.

The vulnerability of nuclear power plants is made frighteningly clear when we consider that American Airlines Flight 11, as it flew south from Boston toward Lower Manhattan on Sept. 11, passed almost directly over the Indian Point complex. Then consider that President Bush reported in his State of the Union Message that Americans in Afghanistan had found diagrams of U.S. nuclear power plants, and that the nation's 103 nuclear reactors were never designed to withstand the impact of a commercial airliner.

Everyone within at least a 50-mile radius would be in danger if something terrible happened at Indian Point. That 50-mile radius contains more than 7 percent of the entire population of the United States — 20 million people. It includes all of New York City; the suburban New York counties of Westchester, Orange, Rockland and Putnam; Bergen County in New Jersey; and most of Fairfield County in Connecticut. There is no other nuclear plant in the country with anything close to Indian Point's potential for disaster.

Its chronic safety issues made Indian Point problematic before Sept. 11. Accidents happen. But since the attack on the World Trade Center, and with the awful proliferation of suicide bombers in the Middle East, the unthinkable is no longer unthinkable. Residents in the vast potential danger zone surrounding Indian Point have little trouble imagining an airliner diving toward the complex, or terrorists on the ground attempting to sabotage it.

Anxiety is very high, and opposition to the plant by residents and elected officials is intensifying. It may not be long before a consensus is reached that Indian Point is a problem the region can do without.