If federal officials hoped to reassure an anxious public about evacuation plans in the event of a radioactive release from the Indian Point nuclear reactors, some 35 miles north of Times Square, they picked a terrible way to do it. Late Friday afternoon, the Federal Emergency Management Agency released a two-page letter to Gov. George Pataki conveying its "reasonable assurance" that measures to protect residents within 10 miles of Indian Point would be "adequate." The Nuclear Regulatory Commission promptly followed with a one-page statement asserting that the emergency planning was "satisfactory" and should provide "adequate protection" for the public. And that was that. After months of criticism by local officials and antinuclear groups, federal regulators had responded with terse judgments that were too thinly supported to evoke confidence. It felt more like a thumb in the eye of the critics than a well-documented verdict.

We say that, despite our belief that the likelihood of a large release of radioactivity from Indian Point is very low, whether from an accident or from a terrorist attack. We also recognize that many of those who deride the evacuation plans are really looking for a backhanded way to shut the plant down entirely. Even so, the emergency plans should be as sound as possible, and the rationale for approving them should be explained in some detail.

Just a few months ago, a report prepared for the state by a consulting firm led by James Lee Witt, a former FEMA director, found substantial fault with emergency preparedness at Indian Point. It is by no means clear that Mr. Witt's concerns have been met. His report, for example, fretted that roads might be clogged if everyone tried to flee at once, particularly in the wake of a terrorist attack. By contrast, federal officials seem to have concluded that the authorities could simply evacuate those close to the plant and those downwind who might have radiation blown over them while everyone else would simply be prepared to take shelter in their homes.

Federal officials need to articulate more fully the reasoning behind their decision, either in a detailed report or, better yet, in public testimony. Senator Hillary Clinton has proposed oversight hearings in Congress. That would provide a useful forum to explore this contentious issue.