THE worst is, nobody knows. Ten years after a reactor fire at the Chernobyl nuclear power station spewed radiation over much of Europe, scientists remain unsure how long its lethal effects may be felt.
The catastrophe's effects have carried even further than the poisonous winds. The explosion on April 26, 1986, not only cast a new light on the global debate over nuclear energy, it helped blow a hole in Soviet secrecy that eventually destroyed the Soviet system itself.
While the world's nuclear industry drew lessons from the radiation leak, nowhere were those lessons more relevant than in the former Soviet Union. A decade into post-Chernobyl history, however, some still have not been learned and others are already being forgotten, scientists and environmentalists complain.
Yet there is no doubt that Russian nuclear power stations are safer than they were before the world's worst reactor accident. Operators have been obliged to put safety first to obey new rules and avoid another catastrophe.
Chernobyl itself, whose name has become synonymous with ecological disaster, has naturally had to be in the forefront of this effort, spending over $300 million on safety over the past 10 years to keep the two remaining reactors open. Today, says station director Sergei Parashin, "safety is our first priority, before any other business. Once, output was the top priority - now it is safety."
At the 15 Chernobyl-style, graphite-moderated RMBK nuclear reactors still in operation around the former Soviet Union, new safety mechanisms and procedures have been introduced to rectify the design fault that made the 1986 accident possible. Plans for more such reactors were scrapped.
But these steps have by no means eradicated the dangers, officials acknowledge. "Taking into account the numerous problems associated with the use of nuclear power and nuclear material, which are being solved too slowly, without an appropriate legal basis, the general state of nuclear safety in the Russian Federation cannot be considered satisfactory," concluded a report last year by the State Nuclear Regulatory Commission.
"The general lesson of Chernobyl is that our existing nuclear industry is not safe enough," says Alexei Yablokov, Russian President Boris Yeltsin's top environmental adviser. With Russia's abundant natural gas supplies, he reckons it now would be cheaper and safer to steer clear of nuclear energy. "The tragedy is that if we want to reach Western levels of safety we would have to spend $20 billion, but that we could replace all our nuclear plants with gas turbines for only $7 billion."
One fundamental problem with Soviet reactors is that "the technology we use now was not optimized for energy generation, but for weapons and isotope production," explains Yevgeny Adamov, a top nuclear physicist based in Moscow.
"We cannot create technology that depends so much on the human factor," he adds. (Using complex technologies always involves risk; see story below.)
Politically, the accident showed that "it is not so good if you don't have public opposition. It is not the same as scientific opposition, which is not enough to prevent such a great catastrophe," says Professor Adamov, who heads the design bureau responsible for the RMBK reactor.
Chernobyl provided an early impetus to glasnost, the policy of official openness introduced by former Soviet leader Mikhail Gorbachev. The Soviet government said nothing publicly about the accident for nearly three days, but was obliged to do so when the Swedes discovered radiation levels in their air. Afterward, the Soviet leadership found it more difficult to keep secrets - not least because people realized that the lack of early information was one of the biggest problems in containing Chernobyl.
Yet this benefit of political openness is fading in Russia, worries Mr. Yablokov. For the past two years, official secrecy in Moscow has been on the rise again, he says. "Every month we have evidence that the shroud of secrecy covers more and more topics."
Meanwhile, at Chernobyl itself, many troubling questions about the station's future hang unanswered in the air. What is to be done with the ruined reactor, for example, entombed in a concrete and steel sarcophagus designed to last only 20 more years? How much longer will the still-functioning reactors go on working?
To build a second sarcophagus over the existing structure would cost $636 million, according to European Union estimates. And to further dismantle the reactor core, disposing of its deadly mixture of concrete, graphite, and nuclear fuel could take 30 years and cost as much as $5 billion, station officials say.
Ukraine, which relies on the remaining reactors at Chernobyl for 6 percent of its energy, is resisting pressure from the Group of Seven major industrialized nations to close the station - unless the West comes up with a great deal of money.
It would cost $4 billion to compensate Ukraine for lost energy production from Chernobyl and to construct replacement facilities, says station director Parashin. "We are not asking for foreign aid," he told reporters recently. "We are just saying that if Chernobyl is shut down on somebody else's initiative, this is what it would cost Ukraine. It should be compensated."
But the former Soviet republics cannot afford the safety upgrades, and Western offers don't cover the cost of needed repairs. "Priorities have been set," says Adamov, the physicist. "But we delay carrying them out because we haven't got the money."