PITTSBURGH--The Soviet official responsible for the decontamination of the stricken Chernobyl nuclear power plant has acknowledged for the first time that his country was forced to abandon mechanical solutions and resort to human labor to complete the cleanup. Innovative robotics equipment from the United States that could have reduced the human toll was not used, he noted, because of bureaucratic ineptness and the lack of any cooperative agreement between the two countries.
In short and measured sentences, Yuri Semiolenko told a recent conference of robotics scientists gathered at Carnegie Mellon University how Soviet hazardous waste experts spent an estimated $2 billion on the cleanup and threw everything from converted moon rovers to radio-controlled bulldozers at the demolished reactor. But innovation after innovation succumbed to radiation, moisture, and debris. Faced with a ruin that was still emitting 1,000 rads of radiation an hour, the Soviets resorted to manpower.
"The challenge was to clear 100 tons of highly radioactive debris from the roof" of the Chernobyl reactor, Semiolenko said, speaking through a translator. "Unfortunately, we were not able to decontaminate the roof without using mostly manual labor." Over an eight-month period following the April 1986 accident, thousands of so-called volunteers - actually, conscripted workers - finally buried Chernobyl with hand tools and muscle power. Some of them surpassed safe radiation limits within their first 20 seconds at the plant.
"The most eye-opening thing is the cold fact that much of the Soviet enterprise was undertaken with human force, where it was clearly within the capability of robotics," says William ("Red") Whittaker, a Carnegie Mellon robotics researcher who heads the university's Field Robotics Center and advised the Soviets through some of the Chernobyl cleanup. "It's not like they needed magic or technology that was beyond the reach of what we were doing. It was really a matter of bringing that technology to bear." Although the Soviets did use some West German and Japanese robots with limited success, no U.S. machines took part in the cleanup.
The Soviets used about 60 remote-controlled robots, most of them manufactured domestically within the U.S.S.R. Although several designs were eventually able to contribute to the cleanup, most of the robots quickly succumbed to the effects of high levels of radiation on delicate electronics. Even those machines that could operate in high-radiation environments often failed after being doused with water in an effort to decontaminate them.
But while the Soviets were discarding automation in favor of manpower, scientists at Carnegie Mellon had already perfected working prototypes of several robots that would likely have solved many of the problems at Chernobyl. Unfortunately, the machines were not available. The working prototypes were committed to the cleanup of the Three Mile Island nuclear plant - itself shut down seven years earlier after a partial meltdown - and U.S. scientists were discouraged from designing special machines for the Soviets by regulations meant to prevent sensitive technology from being passed along to countries considered a threat to the U.S.
Semiolenko's speech was the first public admission that the Soviet use of robots at Chernobyl had been anything less than successful. In late 1986, Moscow's Literaturnaya Gazeta (Nov. 19, 1986, page 10) wrote glowingly on the triumph of the Central Scientific Research Institute of Robotics and Technical Cybernetics at Leningrad's Kalinin Polytechnical Institute in designing and building robots for Chernobyl. The article, entitled "Work for Robots: How it took two months, instead of two years, to significantly improve the effectiveness of designs, bypassing foreign firms," uses Chernobyl as an example of Soviet scientific success under duress. "When life really puts on the pressure, we are capable of miracles," the article concludes.
Painting an entirely different picture, Semiolenko told U.S. researchers that it was bureaucratic bungling rather than any desire for efficiency that restricted the use of foreign robots. "The officials who purchased the robots didn't understand our situation. We would have wholeheartedly taken robots from [the U.S.]," he said. Indeed, he said, his visit to Carnegie Mellon this past November to speak at a conference was in part to sow the seeds of new cooperation.
The videotape Semiolenko had brought with him chronicled a cleanup based on shoveling radioactive debris through the large hole the accident had left in the roof of the power plant, and then down into the melted reactor core. After the loose radioactive material was contained within the core, Soviet engineers enclosed the reactor in a concrete sarcophagus, where it still awaits its final burial.
But Semiolenko's videotape also graphically demonstrated what happens to basic robotic technology in the face of mountains of reactor wreckage. For the first time U.S. scientists saw disabled Soviet robots being rescued with winches and chains by teams of workers - men forced to expose themselves to heavy radiation because Soviet officials, like their U.S. counterparts before Three Mile Island, had not anticipated a disaster such as Chernobyl.
Reacting to Semiolenko's unprecedented disclosures, Whittaker says that glasnost is not the only explanation for the new openness and reaching-out. "Chernobyl has left deep scars. It's hard to overestimate the impact it has had on the Soviet way of thinking," he says. Since Chernobyl, a fire at a Lithuanian reactor and damage to nuclear plants during the 1988 Armenian earthquake have stimulated growing Soviet research programs on hazardous-environment automation and nuclear accident control.
While the Soviet program has come far since the early days of Chernobyl, it still has far to go, Semiolenko said. Despite a round-the-clock development effort after the disaster, only three Soviet robots achieved much success in the cleanup. The IMR-2D, a bulldozer-like machine built on the chassis of a heavy tank, was used on the contaminated grounds surrounding the plant. On the roof, where the initial explosion threw over 200 tons of radioactive graphite and nuclear fuel, Soviet experts used a machine known as an STR-1. The six-wheeled robot was based on a lunar rover that was used in the Soviet lunar explorations of the 1960s. Perhaps the most successful robot - the Mobot - was a small, wheeled machine equipped with a bulldozer-like blade and a "manipulator arm." But the only Mobot prototype was destroyed when it was accidentally dropped 200 meters by a helicopter carrying it to the roof.
Ten percent of the cleanup of Chernobyl's heavily contaminated roof was done by robots, saving 500 people from exposure, Semiolenko said. The rest of the work was done by 5,000 other workers, who absorbed a total of 125,000 rem of radiation. The maximum permitted dose for any one worker was 25 rem, five times normal yearly standards. In total, 31 workers died at Chernobyl, 237 had confirmed cases of acute radiation sickness, and many more are likely to eventually suffer adverse effects from their exposure.
Had the Soviets been more prepared, the human toll might have been far less, said Semiolenko. At the time of the accident, the country had no established methods for dealing with nuclear accidents and the Soviet robot technology was primitive, he explained. Adds Whittaker, "They were reaching all over the world for help. The only machines they had to use that worked had been developed for other purposes. They had not seen much of the literature in the area [of robotics], even the popular literature or videotapes that might convey the capability [of modern robots.]"
Although no formal collaborations between U.S. and Soviet robotic researchers currently exist, negotiations are under way on an agreement with U.S. researchers to develop robots that will be able to largely replace humans in radioactive disasters such as Chernobyl, Whittaker says. Although some economic hurdles - like the Soviets' dearth of hard currency - remain in the way of full cooperation, no one disputes the need for such a project. As the last pictures of Soviet workers in lead suits faded from the screen showing Semiolenko's videotape, the Soviet official paused briefly before turning to his attentive audience. "Now I think you can understand what robotics can save us from," he said.