A significant number of older nuclear power plants are approaching the end of their useful lives and must be decommissioned, a process with profound environmental consequences, because the innards of reactors become radioactive during decades of operation. The central questions in decommissioning involve how clean the sites are going to be and how to dispose of the radioactive waste.

Tens of billions of dollars are at stake, because the standards apply to some 70 nuclear power plant and waste disposal sites. Under present rules, some decommissioning funds that utilities have been required by law to put in anticipatory escrow over the years may be adequate or have some surpluses. Others may fall far short. Under more lax standards, plant owners could pocket hundreds of millions of these saved funds were regulators to allow it.

It is therefore no accident that we have heard the champions of the nuclear industry pooh-poohing the dangers of low levels of radiation, saying that a little bit of radiation doesn't hurt people or that one would get a larger dose by moving from Washington to Denver (because of the higher altitude) than by living next to a nuclear dump, etc. In this view, the public has an irrational phobia about radiation that could cost society billions in needless expenditures.

Electricity deregulation is adding to the pressure for looser standards. The prospect of deregulation has led some utilities to opt out of nuclear power. Power plants that cost a billion dollars or more to build are being sold for about $100 million or less. The plants come complete with decommissioning funds of hundreds of millions of dollars. Lax standards could result in a handsome return on investment.

The Department of Energy (DOE), which owns the U.S. nuclear weapons complex, also has an interest in easing standards to minimize cleanup costs. In 1996 the DOE undermined the process to create national cleanup standards; then it proposed to leave 40 times more plutonium in the soil after cleanup at its Rocky Flats plant near Denver than its own guidelines allowed for areas in the Marshall Islands contaminated by nuclear testing. (It backed down under intense public pressure.)

Current radiation protection standards are not too strict. Indeed, studies show that radiation may be more dangerous than assumed in present regulations. Further, current rules are made for "standard man"--a 154-pound male--and therefore are not as protective of, say, children or developing fetuses for some kinds of water contamination.

Some studies do show no damage at low radiation doses. They provide the basis for the view that present standards should be relaxed.

For several reasons, science has so far been unable to resolve the controversy. First, cancer is a common disease, with a variety of causative and contributory factors, such as genetic vulnerability, diet, smoking and exposure to natural and artificial radioactivity and toxins. It is often impossible to extricate the effects of any particular exposure from this complex mix.

In 1990 the National Academy of Sciences (NAS), after reviewing a large number of human and animal studies, recommended models according to which every new exposure, no matter how small, creates some increase in cancer risk.

Industry talk brushes this aside as outdated. The NAS is undertaking a new review, due to be completed in three years. It is becoming one of the arenas for the controversy.

Second, many radiation exposure records are deeply flawed, vitiating risk studies and making it difficult to separate the good studies from the bad.

Third, the government and its nuclear weapons contractors have, under the guise of national security, sometimes covered up and even lied about radiation exposure, as The Post's recent reporting on the Paducah, Ky., uranium-enrichment plant has shown. Paducah is not a solitary case. Obtaining the best extant data in the face of such behavior generally has not been feasible. This makes some independent studies less reliable than they might otherwise be.

Public fears of radiation are not irrational. Rather, they are a reasonable response of people who, in the face of notoriously inexact science, have chosen not to trust those who have egregiously and frequently betrayed them. Before considering a relaxation of radiation protection standards, policymakers should discuss how they might restore public trust.

The writer is president of the Institute for Energy and Environmental Research.