Soviet Union "We Are Still Not Satisfied"

By Michael S. Serrill

On the surface, relations among the nearly 600 delegates to last week's symposium on the nuclear accident at Chernobyl were cordial, detached and scientific. After all, the Soviets had agreed to the extraordinary 62-nation conference, sponsored by the International Atomic Energy Agency (IAEA), in a spirit of international cooperation. Said Chief Soviet Delegate Valeri Legasov: "All our experts understood that the events that happened (at Chernobyl) concerned not just the Soviet Union but the whole world."

As discussions at the Vienna International Center opened, however, the amiable, and often impenetrable, dialogue was marred by doubts and mistrust. Some Western experts complained that the Soviets were too stingy with vital technical data about the April 26 disaster, and too reluctant to admit to design flaws in their reactors. The Soviets insisted that their designs were basically safe, and that "gross" human error had caused history's worst nuclear power catastrophe. Said one Canadian expert: "They seem to be saying, 'You can criticize our operators but not our machines.' "

The debate was as much about the future of atomic power everywhere as it was about a single plant in the Ukraine. In the months since the Chernobyl blast sent clouds of radioactive debris into the air, 31 Soviet citizens have died and thousands of acres of prime land have been rendered useless. A major goal of the conference was to understand the accident well enough to prevent a recurrence.

Yet the conferees were unable to agree on even so basic a question as how many human lives the Chernobyl accident may claim. Morris Rosen, director of nuclear safety for IAEA, and Dan Beninson, chairman of the International Commission on Radiological Protection, initially predicted that radiation from the disaster would cause as many as 24,000 cancer deaths over the next 70 years. They later reduced their estimate by more than half after further studying the Soviet data. The revision stirred charges that the scientists were bowing to the nuclear power industry. Thomas Cochran, senior scientist at the New York City-based Natural Resources Defense Council, contended that the initial 24,000 figure was probably far too low. While the experts argued, workers labored to restore the land around Chernobyl. A newspaper in Soviet Estonia reported that military reservists from that Baltic republic were being forced to participate in the Chernobyl cleanup. The men were said to be working 14-hour days washing down buildings and trees and digging up contaminated topsoil. "They are like squirrels in a running wheel," wrote Journalist Tonis Avikson. He noted that the reservists staged work stoppages when their Chernobyl tour of duty was extended from two months to six, and the "air was filled with strong words, words fueled by disappointment, indignation, despair." Despite this harsh picture, the reporting was apparently an officially approved effort to squelch false rumors about even worse conditions.

The painstaking and dangerous cleanup operation provided a grim backdrop for the Vienna talks. Throughout the week, the Soviets stuck to the assertion in their written report that the accident could easily have been avoided. In a five-hour presentation, Legasov explained that the operators of the Chernobyl reactor, while testing a turbine generator, had systematically disconnected all safety systems. That left nothing to prevent the accident after a huge power surge shot through the facility, setting off explosions and fires. Said Legasov: "The defect of the system was that the designers did not foresee the awkward and silly actions by the operators."

Still, the Soviets announced that they have shut down and are modifying about half of the country's 14 RBMK-1000 Chernobyl-type reactors. Legasov said the overhaul will include the addition of more control rods to slow down nuclear fission in the water-cooled reactor core. Operators will have only limited ability to withdraw the rods, and a safer blend of uranium fuel is being developed.

Even with new measures, experts doubted the RBMK reactor would meet Western safety standards. Said a member of the 21-person U.S. delegation: "The Soviets have taken some initial steps, the more obvious ones, but we are still not satisfied." Other Western specialists maintained that the RBMK units are obsolete. Their main disadvantage, said British Delegate Lord Walter Marshall, is that they are moderated, or controlled, by blocks of graphite. That substance can ignite under the extreme heat of an accident in a water- cooled reactor, causing a damaged unit to burn out of control.

Western nuclear engineers have avoided graphite-moderated reactors since a 1957 British accident damaged such a unit. Only one American commercial reactor, near Plateville, Colo., uses graphite. It is gas-cooled, however, and has a protective containment system of concrete, ceramic and steel.

The Soviets responded indignantly to charges that their reactors are inherently dangerous. Armen Abagyan, director of Moscow's Nuclear Power Station Institute, called the modifications an "absolute guarantee" against accidents. "These reactors are situated in our country," Abagyan said, "where our children and grandchildren are going to live. Do you really think we will allow the operation of reactors that can repeat the same story?"

By week's end some of the early conference rancor had melted away. Said U.S. Delegation Leader Richard Kennedy, who had initially declared himself "disappointed" with the amount of Soviet information: "Our objectives have been met. We came to learn as much as we could. This does not mean we know everything. But the Soviet experts don't know everything either." While some understandings were reached during the five-day session, few if any minds were changed.

With reporting by John Kohan/Vienna