Government scientists believe that a nuclear accident in the Cheliabinsk Province of the Soviet Union more than 20 yeara ago released far more radio-activity to the air, land and water than did the Three Mile Island accident in Pennsylvania last March.

"The radioactivity reported in the Soviet scientific literature for what we think was an accident in 1957 or 1958 compares with the fallout from an atmospheric nuclear bomb test," Dr. Stanely I. Auerbach, director of the Environment Science Division of the Oak Ridge National Laboratory, told the Nuclear Regulatory Commission yesterday. "In fact, it's about 1,000 times higher than bomb fallout."

Auerbach said that the Soviet accident may have triggered the release of so much radioactive strontium-90 that it poisoned a large lake near the Ural Mountains for 300 years. Auerbach said theere could be as much as 1 million curies of radioactive strontium in the lake which would make it the most radioactive place known on the face of the earth.

"There's nothing else like it on earth, from what we can figure out," Auerbach said in an interview after he briefed the Nuclear Regulatory Commission. "The Soviets apparently have sealed off the lake from fishermen for years to come because the fish in the lake are so contaminated.

Called in by the NRC to explain what he and his collegues at Oak Ridge might know about the Soviet accident, Auerbach said he was talked exhaustively with exiled Soviet scientist Zhores Medvedev and analyzed the articles in 115 Soviet scientific journals to compile an accound of the Soviet accident.

Medvedev has long said the accident was triggered by an explosion that ruptured storage tanks built to hold military radioactive waste. Auerbach said he has no reason to doubt this, especially since the city Kasli in central Cheliabinsk is believed to be the center of Soviet plutonium production for nuclear weapons and a lot of waste tanks are located there.

In the 115 Soviet journals Auerbach persued, he said not one mention is made of an atomic accident in Cheliabinsk Province. He said he and his colleagues put together details of the accident and pinpointed its location from accounts of the contamination in the Soviet journals, what the Central Intelligence Agency publicly released about the accident in 1977 and what Medvedev told them when he visted Oak Ridge 18 months ago.

In 1960, Medvedev attended a clandestine meeting of Soviet biologists in a forest south of Kasli, Auerbach said. "They were driving north to Sverdlovsk and were about 100 kilometeres south to Sverdelovsk when they noticed deserted homes without chimneys.

"They were told the area was contaminated with radioactivity and they would have to move," Auerbach went on. "They inquiried about getting water to drink from a nearby reservoir and were told it was so contaminated that citizens were forbidden to fish there."

Among the possible causes of the accident, Auerbach said, is that a chemical explosion caused the release of the radioactive wasters in the storage tanks. He said the explosion could have been caused by nitrates or ethers involved in a primitive and possibly unsafe process used by the Soviets to extract plutonium from spent nuclea fuel.

Whateve the mechanism for the accident, Auerbach said the radioactive release that followed was the worst of its type since the Atomic Age dawned. He said the accident triggered a "massive movement of Soviet scientists into the area to take advantage of a unique study site" where air, land and water were highly contaminated.

Auerbach said the Soviet literature identifies three contaminated lakes in the province, one covering an area 20 square kilometers in size that he called "Il'Enko's Hot Lake" after the Soviet scientist who studied the contamination there.

"There are pike in that lake I would not want to eat," Auerbach said. "By this time, the fish almost surely have suffered genetic defects and chromosomal aberrations. It should be interesting to bear what the Russians scientists find.

"This accident scared the bejezus out of the Soviet technical community," Auerbach added. "I think it got them to see the light on nuclear safety."