Human Error Blamed for Soviet Disaster

The chief designer of the Chernobyl atomic plant said Monday that he believes human error and not a technical failure led to the worst disaster in the history of the nuclear power industry.

Ivan Y. Yemelyanov, a non-voting member of the Soviet Academy of Sciences, also said in an interview with Western reporters that the Soviet Union does not build containment domes over its reactors because they do not guarantee safety and can lead to a false sense of security.

Yemelyanov, 72, said a government commission investigating the Chernobyl tragedy will provide the final verdict on the cause of the accident. But he made it clear that he believes that someone at the nuclear plant 60 miles north of Kiev in the Ukraine violated the safety rules for the 1,000 megawatt reactor, overriding the systems that are built in to avoid a nuclear accident.

Yemelyanov did not specify what the human error was, but he insisted that the plant had built-in systems to control the release of radiation if procedures were followed properly.

A “crucial question,” he said, was why one of the hundreds of pipes cooling off the reactor suddenly burst at 1:23 a.m. April 26, triggering a chemical explosion that blew the roof off Chernobyl Reactor No. 4.

Operating at 6% of Capacity

Re-creating the scene at Chernobyl before the pipe burst, Yemelyanov said the ill-fated Reactor No. 4 was operating at 6% of its capacity during a pre-scheduled shutdown when the accident occured.

Suddenly, in less than 10 seconds, he said, a power surge increased the reactor’s output to 50% of capacity, triggering emergency systems that shut it down completely.

But he said he could not explain why there was a power surge, a question that he said will be answered by the government commission.

A 1986 textbook on the operation of Soviet nuclear reactors indicates that plants such as Chernobyl are designed to handle sudden surges in power or a failure of the cooling system.

The power surge during the accident, however, apparently was far larger and far more sudden than designers ever anticipated. Yemelyanov said the systems were designed to handle a power surge of up to 16% of capacity within 10 seconds.

Workers Under Pressure

Experts have speculated that workers, under pressure to complete the maintenance more quickly, may have lowered fuel rods into the reactor at too fast a pace, triggering the increase in power output.

After the ensuing explosion, Yemelyanov said, “the safety system simply couldn’t cope with the total amount of radioactive vapor.”

Two plant workers died in the initial explosion and so far 11 other people, plant workers as well as firemen sent in to fight the ensuing fires, have died of radiation exposure. Another 24 patients received severe exposure, and Western doctors who helped to treat them afterwards have said that there will be more deaths. In all, 299 people were hospitalized, Soviet authorities have said.

Despite the accident, Yemelyanov said there was no sign that the Soviet Union would reconsider its policy of locating atomic plants near centers of population. He also rejected the practice, widely used in the West, of building reinforced concrete containment domes to limit the release of radioactive substances in case of a nuclear accident.

Most Soviet plants, he said, have “airtight boxes” to contain radioactive gases and vapor that might escape from a damaged reactor. These “boxes” enclose components of the reaction, but not the entire reactor itself, as is the practice in the United States and other Western countries.

‘No Guarantee of Safety’

“Containment domes do not guarantee complete safety,” the scientist said. “Experience shows that containment domes in the West cannot stand very high pressure and can be ruptured.

“Containment domes can be counterproductive if personnel are lulled into a false sense of security and place all hopes in the containment dome rather than trying to prevent accidents,” he said.

Containment domes, with which all but nine U.S. reactors are equipped, have been recommended strongly by the International Atomic Energy Agency as an essential safeguard against the spread of radiation after a nuclear accident. Most reactors in the Soviet Union do not have them, however.

In Washington, two prominent opponents of nuclear power plants said that containment domes on many U.S. reactors are not effective shields against radiation and accused the American nuclear industry of misleading the public on the issue.

“The typical U.S. containment building has between 60 and 100 electrical conduits penetrating” the walls and as many as 200 pipes, Daniel Ford, former executive director of the Union of Concerned Scientists, said.

‘Look Like a Pincushion’

“The reality is they look like a pincushion,” he said, adding that records of the Nuclear Regulatory Commission showed that plants had operated on as many as 3,000 occasions between 1965 and 1983 with the containment not intact.

Ford and Robert Pollard, a former staff member of the regulatory commission who now is nuclear safety engineer for the Union of Concerned Scientists, said 39 U.S. nuclear plants built by General Electric have defective containment and suppression systems.

They said the company persuaded U.S. authorities not to publicize criticism of the design, according to NRC documents.

GE spokesman Hugh Huxamer at San Jose, Calif., charged that the remarks by Ford and Pollard were “a blatant attempt to exploit this (Chernobyl) tragedy for their own ends.”

He added: “GE designs are safe and bear no resemblance to the reactor at Chernobyl.”