ASHINGTON Despite all the talk about nuclear power as the environmentally clean response to electricity shortages and global warming, many Americans are understandably wary. The Bush administration's energy task force announces its report today, and President Bush would do well to note the public's concerns about the combination of human fallibility and mechanical failure that can set off catastrophic accidents at nuclear plants and about the link between nuclear waste and nuclear weapons.

The nuclear industry's safety and security claims are often misleading. Its spokesmen still insist that the Three Mile Island accident demonstrated that the core of a light water reactor is far more resistant to a meltdown than had been previously thought. They don't acknowledge that the core at the Three Mile Island plant was within hours of an uncontrolled melt with Chernobyl-like consequences when a new shift supervisor came on duty in a panicked control room and finally figured out that thousands of gallons of cooling water had poured undetected from a valve that was stuck open. Advanced designs for presumably safer light water reactors and simpler pebble-bed reactors still have not made it off the drawing boards.

Though the nuclear industry claims it is being crippled by overregulation, its powerful friends on Capitol Hill have threatened budget cuts to make the Nuclear Regulatory Commission compliant. The N.R.C. has begun a process of granting life extension to America's aging supply of 104 power reactors, for example, despite a rash of forced shutdowns due to equipment failures caused by aging. There have been at least eight such shutdowns over the past 16 months, according to an analysis of N.R.C. data by the Union of Concerned Scientists.

And the agency has decided not to take enforcement action against weak security at nuclear plants: guards at half the nation's nuclear power plants have failed to repel mock attackers in N.R.C.-supervised exercises that test the protection of reactor safety systems against sabotage. Instead, it is in the process of weakening the rules of the "game" used in the mock attacks.

A push for nuclear power, which Mr. Bush supports, isn't the way to meet America's urgent energy needs. New plants could not be brought on line quickly enough to offset present electricity shortages, which many experts believe are caused primarily by lack of capacity for transmission, not production. Nor could using nuclear plants make a big dent in global warming. Two-thirds of the emissions of carbon dioxide, a major greenhouse gas, are from transportation or other sources not related to power generation. And worldwide, it would take 3,000 nuclear plants a tenfold increase to replace all coal plants; yet that increase would reduce carbon emissions by only 20 percent, while enormously expanding risks that materials from nuclear power plants would be applied to making weapons. And since reserves of uranium ore are limited, millions of kilograms of plutonium, equivalent to hundreds of thousands of bombs, would have to be separated from wastes each year to help fuel so many reactors in the future.

There are better alternatives. Energy efficiency measures, like using the best available existing technology for air conditioning, lighting and electric motors, could offset the need to build any new nuclear plants. Renewable energy sources and other alternative energy systems, including hydrogen recovered from fossil fuels after removing carbon, could provide new, clean ways to generate power.

A rapid expansion of nuclear power would compound the existing dangers of nuclear weapons proliferation. International inspections of nuclear facilities provide uncertain protection; Iran, for example, has pledged to put the reactors it will build under inspection but is still suspected of using civilian nuclear power as a cover for a nascent nuclear weapons program.

George Perkovich, in his book "India's Nuclear Bomb," reports that a bomb tested by India in 1998 was made from the grade of plutonium produced in its 10 uninspected power reactors.

Is it reasonable to assume that millions of kilograms of plutonium, separated from reactor wastes, can be kept secure, down to amounts of less than eight kilograms, which is all that is needed for an atomic bomb that terrorists and radical states could make? This is the ultimate question requiring an answer before nuclear power is looked to as the solution to climate and energy worries.

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Paul L. Leventhal, president of the Nuclear Control Institute, was codirector of the Senate investigation of the Three Mile Island nuclear accident.