The Environmental Protection Agency set a limit yesterday on the amount of radiation the nuclear power industry may release in the general population.

The standard is the first legally enforceable federal restriction on low-level radiation in the environment. It will affect people living near nuclear plants, uranium mills, chemicals conversion plants, enrichment facilities and fuel fabrication and reprocessing operations.

"These standards establish an important precedent in radiation protection because they consider the long-term potential buildup of radiation in the enviroment," said EPA administrator Russell E. Train.

Train said the new standard is important "because long-lived radionucleides [radioactive elements] in the environment represent an irreversible exposure to future generations."

The new EPA standard replaces a current federal "radiation guide" which, according to an EPA spokesman, was "advisory and not enforceable like a standard.,

The guide suggested a limit of 500 millirems to the whole body and 1,500 to the thyroid gland, whereas the new standard forbids any dosage over 25 millirems to the whole body, and 75 to the thyroid.

A milirem is a basic unit used to measure radiation dosage.

A person living on the Colorado plateau - where there is much radioactivity in the earth - absorbs from 75 to n140 millirems a year of radiation from the ground as well as another 50 to 75 millirems from cosmic rays in the skies. People all over the world get some radiation from these sources.

But scientists concerned with human safety consider that all added radiation will cause an inevitable extra risk of cancer environmental issue over several years althought it has not been as publicized as controversy over the risk of nuclear accidents, and the question of where to store nuclear wastes.

The nuclear power industry maintains that radiation from nuclear installations is neglible. However, some scientists says radiation can cause canser and genetic mutation even at extremely low levels.

The standard issued yesterday applies only to planned release - radiation that occurs in the normal operation of nuclear facilities. "It does not deal with the possibility of a major nuclear accident such as loss of coolant and core melt-down at a reactor," an EPA spokesman said.

The agency said that most nuclear power plants already conform to the new standard, but that milling and other fuel supply and reprocessing operations must be upgraded.

Milling operations are located mainly in Texas, Washington state, Colorado, Utah, New Mexico and Wyoming.

In addition to limiting the radiation dosage for individuals, the new standard restricts the amount of long-lived radioactive materials - including plutonium, kypton 85 and iodine 129 - that may be released into the environment by nuclear power plants.

The new standard means that the allowable emissions of krypton-85, a long-lived pollutant, would be one-tenth of current leveis by 1983, the EPA spokesman said. "This standard has world-wide implications, because krypton is distributed evenly throughout the world's atmosphere within a year after its release.

"It is expected that by the year 2000, only 30 per cent of the world's krypton will be produced by the United States. The agency hopes its limitation here will encourage similar limitation by other countries," the spokesman said.

The new standard will be implemented by the Nuclear Regulatory Commission which will control radiation from individual facilities. The NRC has the power to grant temporary exceptions to the rule.

Dr. Terry Lash, a scientist with the Natural Resources Defense Council, a New York-based group which has followed the development of the standard, praised it as "a step in the right direction." However, he criticized the standard for not applying to nuclear industry workers.

Gus Speth, a council attorney here, said the standard "represents at least a beginning of EPA's presence in an area previously reserved for the NRC which is strongly influenced by the nuclear industry."