U.S. Study Shows Fatal 3-Mile Zone : Soviet Official Says Plant Is Too Dangerous to Enter

A new government analysis of the Chernobyl nuclear power plant disaster made public Friday portrayed an irradiated trail of potential death extending as much as three miles downwind of the Soviet facility’s destroyed reactor.

Government experts on radiation and nuclear power have pieced together the limited data reaching Western monitoring points to form that assessment of the accident’s likely impact in the immediate area of the blast in the Ukraine.

The Reagan Administration’s description of the accident’s seriousness appeared to be confirmed to some degree by the Moscow Communist Party chief, Boris N. Yeltsin.

In a broadcast carried Friday by West German television, Yeltsin, who is also a candidate member of the ruling Soviet Politburo-- said that the zone around the Chernobyl nuclear plant is too dangerously radioactive to enter and that local drinking water reservoirs have been contaminated.

Human Error Blamed

Yeltsin, in Hamburg for a West German Communist Party congress, was quoted as saying that human error is responsible for the disaster. He also said that lead, sand and the neutron-absorbing element boron were being dropped from helicopters onto the site to prevent the spread of radioactivity.

Yeltsin told the German television network that radioactivity around Chernobyl is about 200 roentgens--a measure of radioactivity referred to in the United States as a rem--a level that could be fatal.

The impact of the Chernobyl explosion, said Lee M. Thomas, administrator of the Environmental Protection Agency, “included the possibility of life-threatening doses (of radiation) two to three miles from the site; significant health effects occurring out to five to seven miles from the site.”

However, in a marked departure from U.S. casualty assessments resulting from what is believed to be the worst accident in the history of nuclear power, Harold Denton, a member of the government task force monitoring the disaster and its impact, said, “I guess I wouldn’t be surprised” if the official Soviet death toll of two were proved accurate.

Since that toll was reported earlier in the week, Administration officials had repeatedly scoffed at the figures, saying they were most likely much higher. But the United States has received no information about the number of people at Chernobyl when the radioactive air mass was released.

“Whether anyone was actually under that plume depends on how much warning they had and whether or not they were able to evacuate,” Denton said.

A senior Administration official said that the workers’ village of Pripyat, near the plant, appears to have been evacuated, although the timing of the departure is not known.

Also, the long-term effects remain a key point of debate. Radiation exposure at certain levels is known to cause cancer, said Denton, director of nuclear reactor regulation at the Nuclear Regulatory Commission, who pointed out at a news conference that some health effects would not occur immediately.

Four days after initial word of the accident reached Washington, Vice President George Bush presided Friday over a Cabinet review of the disaster and said later that--although the Soviets have responded to some U.S. requests for information--their answers have been “sparse, at best.”

A senior Reagan Administration official noted that, while Soviet assertions that the reactor fire had been extinguished were plausible, he and a participant in the Cabinet meeting said the fire appeared only to be diminished.

“There is still vapor coming out; there’s still something going on,” said one official, speaking on the condition that he not be identified. Although radiation emissions could not be firmly established from afar, another source said, it was assumed that they continued, but also at a diminished level.

Temporary Shutdown

A senior Administration official said preliminary intelligence information indicates the Soviets have at least temporarily shut down more than a dozen nuclear power plants similar to the Chernobyl facility, but he was not entirely certain that such a step had been taken.

The official also said that, while the Chernobyl plant was believed to have the capacity to produce material for nuclear weapons, every indication has been that the site was used “solely for electrical power generation.”

Government scientists, lacking specific data, have used satellite photographs and air samples to construct a theory about the events that apparently began April 25, with a malfunction in the fourth of four nuclear power reactors at the Chernobyl complex and culminated in a reactor meltdown, a huge explosion and an uncontrolled release of radiation over two days.

The government task force said the radioactivity released by the plant covered much of Europe and a large part of the Soviet Union. A patch of radioactivity detected by an airplane at an altitude of 5,000 feet about 400 miles west of northern Norway is believed to have headed west and then turned south, or, possibly, toward the southeast to return toward Europe.

Second Toward Austria

In addition, Norris Smith, a spokesman for the Lawrence Livermore National Laboratory in California, said a second cloud was believed to be heading southwest from the Soviet Union, toward Austria.

Smith said said that about half of the volatile products of nuclear fission that could be released in such a nuclear accident have been detected at monitoring points beyond the Soviet borders. Among them are the radioactive elements iodine-131 and cesium-137.

The EPA’s Thomas said it may be “significantly later” than Monday before detectable levels of radiation move over North America--if they show up at all. For the United States, he said, “there is no public health or environmental consequences predicted.”

By reconstructing weather patterns and radiation levels detected in the Stockholm area for April 28-30--three to five days after the disaster began--the federal task force estimated that exposure levels at the nuclear plant would have been in the range of from 20 rem to hundreds of rem, during the two-day period when most of the radiation is believed to have been released. Ninety to 100 millirem is considered normal annual radiation exposure in the United States. A millirem is 1/1,000 of a rem. However, officials cautioned that these figures represented estimates.

Times staff writers Marlene Cimons, Michael Wines and Lou Fintor contributed to this story.

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