Word: reactors
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...century, is simple: food passes through a lead-shielded concrete chamber where radioactive cobalt 60 or cesium 137 bombards it with gamma rays, killing insects and bacteria and sometimes slowing ripening. The food does not become radioactive. "There's nothing in common at all between a nuclear reactor like Chernobyl and an irradiator," says Karl Abraham, a spokesman for the Nuclear Regulatory Commission (NRC). "It's like comparing bananas to tigers." Treated food "can be immediately eaten," says George Giddings, director of food irradiation at Isomedix...
...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...
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...