Assessing impact of Chernobyl. Soviet secrecy, West's guesses complicate search for facts

The Soviet Union continues to keep a hammerlock on information about the Chernobyl nuclear accident. Tass, the official Soviet news agency, said yesterday that 18 people are in serious condition as a result of the disaster. But the latest announcement, like others before it, left many questions unanswered.

It asserted, for example, that radioactivity at the site ``dropped from 1.5 to 2 times'' as a result of decontamination efforts at the scene. But it did not say what those efforts were, or how high radiation levels were to begin with.

The statement, issued by the government's Council of Ministers, said that no foreign citizens were among those receiving medical treatment.

Yet, as other nations continued to press Moscow for more details on the disaster, the Soviet Union embarked on a four-day holiday weekend.

May Day, celebrating the achievements of Soviet labor, was observed with a festive Red Square celebration. Moscow traffic was snarled as city dwellers headed for weekend cottages to take advantage of clear blue skies and warm weather.

Travelers returning from Kiev, the city nearest the reactor site, reported similarly normal scenes in the Ukrainian capital.

One American returning from Kiev summed up the dichotomy:

``We are between two worlds,'' said Hank Birnbaum, an American tour guide who accompanied British students back from Kiev. ``The Soviets have been saying nothing. There's been a flood of information from the West -- some of it exaggerated.''

``We,'' he said, ``were in the middle.''

He has plenty of company, as the world struggles to piece together what happened at Chernobyl.

Yet it is in that broad middle ground that the truth about the Chernobyl disaster probably lies.

Virtually all accounts from Kiev hold that life in the city is normal, there is no panic, and nothing extraordinary is taking place.

The Soviets are claiming that Western news agencies have grossly exaggerated the extent of the disaster. A still picture of the plant, shown on Soviet television, indicated that the right upper half of the reactor building was destroyed. Yet the commentator said the picture proved that reports of massive destruction were untrue.

Diplomats from a number of European countries have been told that the reactor is under control, and that no nuclear chain reaction is now taking place.

Still, Moscow has come under stinging criticism for its handling of the situation. One diplomat here called it ``incredible'' that the Soviets are providing so little information.

In Bali, United States Secretary of State George Shultz said the Soviets have not ``provided as full and prompt information as they should have.'' Mr. Shultz said the US knows more from its own sources, presumably including satellite data, than it knows from the Soviets.

Soviet authorities, however, are determinedly hewing to routine, as if there is no cause for alarm. Soviet leader Mikhail Gorbachev reviewed the May Day parade from the top of the Lenin Mausoleum, flanked by other members of the ruling Communist Party Politburo. The only reference to nuclear matters was to the US nuclear weapons program -- not to any Soviet nuclear mishaps.

Meanwhile, radiation 10 times above normal was registered in the Yugoslav capital of Belgrade and in portions of eastern Switzerland. But radiation levels in Scandinavia dropped from previous highs. It remained unclear, however, whether that was strictly because of wind shifts or because of an actual decrease in radiation emissions from the plant.

As a precaution, passengers on flights from Moscow were being checked for radiation contamination at London's Heathrow Airport. Soviet officials also checked foreign students returning from Kiev for radiation. Although some contamination was detected, the officials said it was within safe standards.

The Soviets also went on a counterattack. Shortly after the announcement that 18 people were in serious condition as a result of the accident, Tass claimed that the US kept the public in the dark during the nuclear accident at Three Mile Island in 1979.

The Soviet news agency echoed charges that while the Three Mile Island plant was ``still spewing radiation and dumping contaminated water into the neighboring river,'' a US government official ``maintained that the situation was under control.''

That is, of course, exactly the same charge that is now being made against the Soviet Union.