MOSCOW, April 28, 1986 (UPI) - A nuclear accident damaged a reactor at a giant atomic power plant in the Ukraine, the Soviet Union said Monday, sending a radioactive cloud more than 1,000 miles to Scandinavia. Western diplomats feared a high death toll at the accident site.
Moscow also said there were injuries in the accident at the restricted Chernobyl nuclear power plant, 80 miles north of the Ukrainian capital of Kiev, the nation's third most populous city with 2.3 million people in the western Soviet Union.
It was impossible to immediately assess the number of casualties independently.
An unprecedented statement acknowledging the accident was issued by the official Tass news agency after Sweden, Finland, Norway and Denmark reported higher than normal levels of radioactivity believed to be from a nuclear accident in the Soviet Union, where many nuclear plants to not have radiation containment walls as are required in the United States.
Scandinavian officials said the radiation levels carried by wind currents 1,000 miles from the site of the accident -- believed to have occurred during the weekend -- were low enough that they were not believed to pose any immediate threat to their citizens. The levels were expected to return to normal over the next few days, the officials said.
The cloud could reach the U.S. West Coast within a week on a route over the North Polar region, then south to western North America, the Environmental Protection Agency said.
''Normally we've seen it as early as three days in cases like this, sometimes as late as 14 days,'' said Charlie Porter of the EPA's Radiation Alert Network in Montgomery, Ala. ''Everything depends on the altitude of the debris.''
Porter said there is no way of knowing if people in the United States will be affected by the fallout until the agency gets a radiation level reading.
White House spokesman Larry Speakes said the United States apparently was not notified through diplomatic channels of the accident. ''We understand there is no danger to the United States,'' he said.
The Tass announcement on the incident said, ''An accident has occurred at the Chernobyl atomic power plant as one of the atomic reactors was damaged. Measures have been undertaken to eliminate the consequences of the accident.
''Aid is being given to those affected,'' Tass said. ''A government commission has been set up.''
The announcement marked the first time the Soviet Union has acknowledged a nuclear accident, causing Western diplomats to speculate that the accident was a major one. A Western diplomat said the statement ''almost certainly indicated that the death toll was high.''
A second Western diplomat said, ''The wording of the announcement indicated this was a very serious accident. It is not unreasonable to speculate about deaths.''
Residents of Kiev, reached by telephone from Moscow, said early Tuesday that all bus service in the city had been stopped so the vehicles could be used to evacuate those in the disaster area.
''They're bringing (evacuees) to Kiev, but we haven't seen anyone yet,'' a Kiev university student said by telephone. ''We didn't see or hear any explosion.''
''Most people weren't aware of it until the TV news,'' a special education teacher said. ''I hope we know more tomorrow.''
Tass said the accident ''is the first one in the Soviet Union.'' But a 1957 accident at a remote plutonium processing plant in the central Soviet Union reportedly killed or injured thousands and contaminated a wide area.
The brief statement from the Soviet Council of Ministers was read on the nightly television news program, Vremya, watched by millions of people, in a further indication that casualties were extensive. No further details were provided.
Residents of the Soviet Union's second most populous city, Leningrad, also could be affected by the radioactive fallout, diplomats said. Muscovites expressed concern over the health of Ukrainians, but said they did not worry about their own health.
The Soviet Union has 50 nuclear plants, including 28 of the graphite-moderated reactor types such as at the Chernobyl facility, U.S. nuclear industry experts said. Graphite technology is an older method of controlling the speed of nuclear reaction. There is no similar plant in the United States.
Olof Hermander, chief of the Swedish nuclear inspection board, said the discharge probably resulted from a Soviet reactor overheating to let radioactive material escape into the atmosphere, a process he said can lead to reactor meltdown.
Western diplomats and nuclear experts said the Chernobyl plant had four or five 1,000-megawatt reactors. The plant went into operation in 1977, and the fourth reactor went on line in 1984.
''It obviously must be harmful. It sounds harmful to people in Kiev, but there is no way to measure the the levels of radioactivity,'' one Western diplomat said. ''I cannot confirm that it is a major accident; there is the possibility they were releasing pressure.
''The fact that they said anything at all is a big step forward for the Soviet Union,'' he said. ''It could say something about the level or significance of the accident.''
The accident first came to light after a worker at the Swedish Forsmark nuclear power plant set off an alarm Monday morning when his clothes registered unusually high radiation levels. Authorities quickly evacuated 600 employees, but experts could not explain the occurrence until radiation readings were taken in other parts of Sweden.
''The radiation was measured to some millirem per hour, a dose unharmful for people, but clearly unallowable,'' said Swedish energy board spokesman Olle Blomqvist. ''Analysis showed it came from a nuclear power plant.''
''We have registered radioactivity just about everywhere we have looked,'' said Ragnar Boge of the Swedish Radioactive Institute. ''They have found unusual concentrations in Denmark, and (Sunday) they found even higher concentrations in Finland.''
In its statement, Tass said 2,300 accidents, breakdowns, and other faults have been reported in the United States because of poor quality of reactors and other types of equipment, unsatisfactory control over technical conditions and non-observance of safety regulations.
The worst U.S. commercial nuclear accident occurred March 28, 1979, when a small amount of radiation was released from the Three Mile Island nuclear power plant near Harrisburg, Pa. About 144,000 people evacuated during the crisis, which later was blamed on human and mechanical failures. No one was injured.
U.S. experts said the Chernobyl plant probably did not have a radiation containment structure, required at U.S. plants and considered crucial for safety.
''The odds are pretty good they did not have them,'' said Scott Peters, a spokesman at the Atomic Industrial Forum, a non-profit international trade association.
''The Soviets didn't start putting containment vessels on until 1979, and two of those Chernobyl reactors were put on line before 1979,'' he said. ''I think it's very likely those reactors were too far along to change things.''
Paul Leventhal of the Nuclear Control Institute, a non-profit organization that studies nuclear proliferation questions, said: ''Without containment vessels ... the consequences could be catastrophic.''
James MacKenzie, a physicist and senior staff scientist with the Washington-based Union of Concerned Scientists, said he believed the nuclear accident was very serious, possibly a meltdown, based on news reports and the amounts of radiation in Stockholm.
''You better believe it (is serious),'' he said. ''I would guess a fuel meltdown. I don't know what else it could be.''