The disaster at the Chernobyl nuclear plant in the Ukraine has already provoked a lively debate about the future of nuclear power -- but the debate is taking place in Western Europe rather than the Soviet Bloc.

In the West, calls for more stringent safeguards against nuclear accidents have been interspersed with demands by ecologists and left-wing political parties for a freezing of plans for new nuclear plants. In the Soviet Union, the country that presumably has most to learn from the Chernobyl catastrophe, there has been virtually no public discussion about the dangers associated with nuclear power.

The contrasting reactions to what is widely believed to be the world's worst nuclear disaster reflect one of the fundamental differences between a communist society and a western society. Public opinion, which plays a key role in the decision-making process in the West, does not have the means to express itself in the Soviet Union, where power flows from the top.

A survey of West European capitals last week showed that public reaction to the nuclear disaster in the Ukraine has been particularly intense in Britain, West Germany and Scandinavia, where ecological movements are most developed. It has been somewhat less strong in France, the world's second-largest producer of nuclear energy after the United States. In France, all the major political parties are in favor of nuclear power.

In Eastern Europe, concern about the Chernobyl catastrophe has been voiced most openly in relatively liberal communist countries such as Poland and Hungary. In Czechoslovakia, East Germany and the Soviet Union itself, the primary concern of the mass media has been rebutting unfavorable publicity abroad.

"Communist governments do not have to contend with public opinion in the way a western government does," noted Jacques Rupnik, a researcher on Eastern Europe at the Political Science Institute in Paris. "If they tighten up at all, it won't be because of their own public opinion but because of the opinion of neighboring western countries. For the Russians, this means Scandinavia. For the East Germans, it means West Germany and Austria."

Rupnik cites the precedent of a leak of radioactivity from a plant at Jaslovenska Bohunice in Czechoslovakia in 1979, which was first reported by the underground Czechoslovak human rights group Charter 77. The accident did little to modify Czechoslovakia's nuclear program but it had an important political impact in Austria, where the government lost a referendum on nuclear power that has left it unable to use an expensive power plant it built.

The Chernobyl disaster is believed to have contributed to a retreat by Britain's Conservative government last week on its plans to dump radioactive waste in shallow sites. The government's retreat after months of debate was announced on the day that radioactive fallout from the Ukraine reached Britain.

The former left-wing energy minister, Tony Benn, echoed the position of many ecologists when he said that the real lesson to be drawn from Chernobyl was that Britain's nuclear power program should be ended as rapidly as possible.

While British government ministers have made clear that they continue to believe in nuclear energy, they have also conceded that the Chernobyl disaster will make it more difficult to combat pressure from environmental groups and political opponents against a major nuclear power expansion program now under way. The government is due to announce this summer whether it will go ahead with plans to build a pressurized water reactor east of London, the subject of an often bitter two-year public inquiry.

In West Germany too, the Chernobyl accident has rekindled concern about nuclear safety, reviving the political fortunes of the antinuclear coalition, which includes the Greens and left-wing Social Democrats. "Chernobyl is everywhere" has become the new rallying cry of an antinuclear movement that had become dispirited after losing struggles to halt the building of new power plants and the deployment of U.S. nuclear missiles.

Sensing a potential buildup of popular support, the Greens called mass demonstrations last weekend at the site of a planned nuclear reprocessing plant in Wackersdorf, Bavaria. West German commentators say that the Chernobyl accident could cause a new surge of dissent, forcing the government to alter plans for the station.

In Sweden, the Chernobyl disaster has increased political pressure on the government to respect the result of a referendum six years ago in which Swedes voted to close down all nuclear power plants by the year 2010. Social Democratic Prime Minister Ingvar Carlsson devoted a major portion of a May Day speech to promising that the pledge would be fulfilled despite the reservations of several party leaders.

Neither Norway nor Denmark has nuclear programs and both in the past have criticized Sweden's 12-reactor system, particularly those plants close to their borders.

In France, where nuclear power provides 65 percent of the electricity, public concern has largely been confined to calls for even more stringent safety standards. A minister in the former Socialist government, Haroun Tazieff, said France's disaster relief plan would be unable to cope with a disaster on the scale of Chernobyl.

The general tone of French press coverage since the disaster, however, has been one of self-congratulation that France is the only major nuclear country never to have experienced a nuclear accident. Officials of the French Atomic Energy Commission have insisted that a Chernobyl-type disaster is almost inconceivable in France because of more stringent safety standards.

The public comments from the Soviet Union suggest that the Kremlin has no intention of drastically revising its nuclear energy programs as a result of the Chernobyl accident. Analysts here say any significant change of plans is unlikely in view of tremendous economic costs and a lack of other energy resources in European Russia.

"The less the Soviets rely on nuclear energy, the more they will depend on their gas and oil reserves. That means less oil to sell to the West and less hard currency. For economic reasons, they will want to forget about Chernobyl as swiftly as possible," said Rupnik.