The 23-year old N reactor at the Hanford nuclear reservation in Richland, WA automatically shut down Dec. 28, 1986, when a water-flow monitor gave a false reading. A spokesman for UNC Nuclear Industries, operator of the reactor, said workers believe that a device that controls the monitor malfunctioned, causing the shutdown. A dozen reviews of the reactor's safety and design have called for extensive modifications in the plant's radiation confinement system, remedies to possible hydrogen buildup after an accident, and other corrections. The N reactor is the only American reactor that resembles the reactor at Chernobyl (which exploded on Apr. 26, 1986) in that it has a graphite-moderated core, water cooling and no containment dome. Every major plutonium-producing facility on the Hanford Reservation is now closed for safety reasons.
--Peter Montague, Ph.D.

Descriptor terms: hanford; wa; unc nuclear industries; shutdowns; radiation; chernobyl; nuclear power; federal; accidents; nuclear weapons;