The Chernobyl atomic disaster has presented Soviet leader Mikhail Gorbachev with one of his biggest challenges. It is a challenge to live up to the vow he made only two months ago to promote public openness in Soviet society. ``It is fundamental for us to increase public openness,'' Mr. Gorbachev told the Communist Party Congress in a policy-setting speech on Feb. 25. ``Sometimes, when it is a question of public openness, one hears calls for greater caution in talking about our shortcomings and deficiencies. There can be only one answer to this: Communists always need the truth.'' He went on in this vein, returning to the topic at three different times in the speech and winning prolonged applause.
Yet, when fire in a reactor at the Chernobyl nuclear power plant spread radiation last week, the Gorbachev regime first concealed the news for two days. Then, after the fallout was detected in Scandinavia and elsewhere in Europe, alerting the outside world, Gorbachev's spokesmen minimized the damage and evaded inquiries.
The cover-up has forfeited prestige abroad. If Gorbachev continues to evade disclosure of the extent of the disaster -- and as facts about the calamity begin to seep in from Western sources and rumor magnifies them -- he risks a more dangerous erosion of faith among his followers at home.
However, if Gorbachev tries belatedly to live up to his advocacy of openness, he confronts likely resistance from colleagues in his 12-man Politburo. Although he heads this ruling body, he does not necessarily control it.
As at Three Mile Island, local bureaucrats and power industry officials may have been responsible for withholding information in the very beginning, perhaps from the leadership itself.
But the decision to cover up or to report the facts could be made only at the level of the Politburo. That a majority of this body initially voted against disclosure was evident from the cover-up. No one outside the Kremlin knows whether Gorbachev approved of that decision or was outvoted.
Behind the cover-up decision lie a long tradition of secrecy and several specific considerations that can only be guessed.
The prospect of casting a pall over the May 1 national holiday was one probable consideration. The festivities had been planned long in advance.
Beyond concerns about turning the jubilant holiday into a scene of gloom, stood a deep-seated belief that the Western news media would use any admission of serious trouble to embarrass the regime.
Add, too, the possibility of panic among a people unaccustomed to candor about national disasters.
Fear of panic has been repeatedly evident in Kremlin behavior. When the Nazis invaded the Soviet Union in 1941, the Kremlin hesitated to telling the public until eight hours after the attack. When Joseph Stalin died in 1953, his successors' first act was to warn against ``panic and disorder.'' The picture of the mushroom cloud and the story of the atom bomb were banned until the Soviet Union acquired its own atomic weapon in 1949.
In 1956, when Nikita Khrushchev disclosed Stalin's crimes, he did so in a ``secret'' speech to a closed party meeting. Only afterward was it leaked to the public at large in diluted form over a period of many weeks, so as to cushion the shock. At least three times -- under Stalin, Khrushchev, and Leonid Brezhnev -- rumors of currency reform set off panic buying. When the Soviets shot down the South Korean airliner in 1983, it was six days before Moscow admitted the fact.
Each time it could, the Kremlin used delay to prepare the public for bad news or provide justification. Before currency reforms, Soviet media dwelt on foreign inflation. During day delay in announcing the Korean airliner shooting, the media raised accusations of airliner espionage.
Last week, along with the first announcement of the Chernobyl fire, the official Soviet news agency Tass released a list of atomic accidents that have occurred elsewhere throughout the world and dwelt on dangers in the Western disposal of atomic waste.
If the purpose of withholding the bad news was to prevent panic at home, the result was to create anxiety abroad.
The habit of soft-pedaling bad news has often backfired at home as well. One effect has been to send many Soviets to their shortwave radios to listen to foreign broadcasts whenever anything untoward seems to be taking place. Another effect was to give rise to rumor, readily exaggerated as it spread. The rumor mill has been dubbed ``the OBS news service,'' OBS standing for the initials of a Russian phrase meaning ``an old lady told me.''
In a country which has had censorship for 400 years, the pattern of official concealment has become traditional.
At times, Czarist censorship was lax. But Lenin's Soviet government clamped down, and Stalin tightened control of information to a fantastic degree. A 1947 decree set the seal on this.
It introduced the stiffest penalties, including execution, for disclosing anything not officially permitted -- but gave no indication what was permitted.
In Stalin's time, a widely-circulated story goes, a momentous development at the UN sent reporters scurrying to the phones to transmit the news. Only the correspondent for Pravda, the official party organ, strolled the corridor idly.
``Aren't you going to file anything?'' a Western correspondent asked.
``First I have to find out what Moscow thinks about it,'' the Pravda man answered.
``But the news -- shouldn't you at least send the facts?''
``Oh that,'' replied the Russian. ``It isn't news anyway, until it appears in Pravda.''
Khrushchev relaxed the censorship. Among his first acts, on taking power, was to call in the leading editors and scold them for ignoring their readers and addressing themselves only to the party officialdom.
He placed his son-in-law, Alexei Adjubei, in charge of Izvestia, the government newspaper. Mr. Adjubei jazzed up that dull newspaper with features and lively headlines -- always within the confines of the censorship. Although Khrushchev abolished censorship of foreign correspondents' outgoing dispatches in 1961, he retained domestic Soviet censorship.
But neither Khrushchev's brief burst of openness nor Khrushchev himself lasted long.
Meanwhile, however, Western radio acquired a Soviet audience despite jamming of airwaves.
Now, with his appeal for ``openness,'' Gorbachev is repeating the Khrushchev call for loosening the reins on information. The Chernobyl disaster is his first test.
That he may break the silence about Chernobyl seems indicated by the appointment of a government commission to investigate the accident.
As the Three Mile Island atomic accident and the Challenger shuttle explosion showed, however, such a commission may take a long time to sift the facts and report. The question will be how soon or how slowly the Soviet commission will disclose the basic facts about Chernobyl and its aftermath.
The answer to that question could reveal as much about Gorbachev's credibility and about his power within the Politburo as about the atomic disaster itself.
Leo Gruliow is editor emeritus of The Current Digest of the Soviet Press and a former Moscow correspondent of the Monitor.