The Soviet Union's first major accident with a civilian reactor is a setback for the world's most ambitious nuclear power program. The current Soviet five-year plan has envisioned a doubling of nuclear power -- which today meets about 10 percent of the country's energy needs -- by 1990. Now one of the standard types of reactor on which that program depends is on fire at the four-reactor Chernobyl power station, north of Kiev. To judge from scanty information available at press time, the reactor's nuclear fuel has very likely melted.
This is an embarrassing, as well as tragic, mishap for a reactor of the so-called ``Leningrad'' class for which the Soviets have claimed an unusual degree of safety.
These RBMK-1000 reactors, to use their technical designation, have a uniquely Soviet design. It's basically a pile of graphite with hundreds of channels drilled through it for fuel and cooling water. The water produces steam for generating electricity.
The Soviets say the design combines high power output with flexibility and efficiency in fuel use and enhances safety.
However, Soviet nuclear power analyst William Kelly of Battelle Columbus Laboratories in Ohio says it may be an obsolete technology. As of June 1, 1985, RBMK reactors accounted for 14,500 of the Soviets' 25,390 megawatts of installed nuclear power. Plans to double that capacity by 1990 emphasize other reactor types, including a competing pressurized water reactor.
The Leningrad design is a direct descendent of the world's first nuclear power plant, built at Obninsk and tied into the Moscow grid June 27, 1954. From there, the design developed into units that deliver steam to produce 1,000 megawatts of electric power -- hence the term RBMK-1000.
The first two such units were commissioned in 1973 and '75 at the Leningrad power station. Chernobyl's four units came on line between 1977 and '83, with two additional reactors planned for the site. More have been built and are being built elsewhere. Engineers are pushing the Leningrad design even harder: The first 1,500-megawatt unit -- a RBMK-1500, the largest power reactor in the world -- is nearly finished at Ignalino in Lithuania.
Nuclear energy is important to the Soviet Union. Key officials, such as Mr. Semenov, have repeatedly pointed out that most of the Soviet Union's coal, oil, gas, and hyropower resources are in the eastern part of the country, while 75 percent of the population and most power-hungry industry is in the European region. So the government has designated nuclear power a key resource, especially for the western USSR.
Currently, the Soviets have something like 50 power reactors in operation, compared to about 100 for the United States. Doubling capacity in five years will be difficult, if not impossible.
Reports in the Soviet press and official statements of censure have denounced inefficiencies and delays in recent years. Three years ago, water from a nearby reservoir undermined foundations of the massive Atommash plant at Volgodonks in southern Russia, which turns out prefabricated RBMK reactors like prefab houses. The plant has yet to reach full production capacity.
Battelle's Dr. Kelly notes that relatively expensive but simpler RBMK technology may have helped make up for lack of capacity to build complete large reactor parts such as pressure vessels and transport them to a site. RBMK units can be put together in the field from prefab partial units turned out by Atommash.
Concerns about safety have also surfaced from time to time. Although these had been a peripheral issue in the USSR, where reactors had no containment vessels to trap leaks until 1980, Finland and Hungary insisted on this protection when they bought Soviet units. It is unclear whether any Chernobyl units are so protected.
Kelly, however, notes that after the US Three Mile Island accident, the Soviets have been quietly paying more attention to safety.
In sum, he says, the Chernobyl accident may be more a setback for RBMK proponents within Soviet industry, who want to keep their design alive, than it is for the country's nuclear power program as a whole.
``Basically,'' he says, ``it's a failing in a technology that is important today but may be fading tomorrtow.''
He also notes that the Soviets have never exported this type of reactor, which makes more plutonium than do the pressurized water reactors. The Soviets may have wanted to keep such potential weapons material at home, Kelly says.