SEATTLE, April 29, 1986 (UPI) - There is little likelihood a plutonium-producing reactor at Hanford, Wash., would ever suffer an accident like the one that crippled a Soviet power plant because the two reactors are notably different, a U.S. Department of Energy official said Tuesday.
Mike Lawrence, who oversees the Energy Department's Hanford Nuclear Reservation, said the only real similarity between the two plants is that both contain graphite cores.
''What we know is that the N Reactor has operated safely for 23 years and we think that safe operating history attests to its design,'' Lawrence said by telephone. ''We've never had a major accident at N Reactor.''
Lawrence acknowledged that the N Reactor at Hanford has no containment shield, but it does have what is called a confinement system designed to prevent radiation from escaping the reactor under most circumstances.
Unlike a containment building used in most commercial nuclear power plants to withstand high pressures in the event of an accident, the confinement system at the N Reactor requires that excess pressure be vented.
''The way you prevent radiation from leaking is you vent the pressure through filters,'' Lawrence said. ''We also have a spray system that would take any particulates out of the air before they get to the filter.''
A nuclear energy watchdog group demanded the shutdown of the N Reactor because of its basic similarity to the crippled Chernobyl power plant near Kiev, U.S.S.R., whose graphite core was believed to be still burning on Tuesday after a weekend nuclear accident.
Besides the similarity in the use of a graphite core, the Coalition for Safe Power in Portland, Ore., expressed concern about the N Reactor's lack of containment.
''There definitely is the threat of a similar accident,'' said Eugene Rosolie, who heads the group. ''When you don't have a containment vessel, you're always running into problems of not being able to control the releases.''
Robert Albrecht, a University of Washington nuclear engineering professor, supported Lawrence by complaining it would be unfair to compare the Hanford N Reactor to the Soviet reactor.
''Only in the most general sense and grossest sense are they comparable,'' Albrecht said, ''and when it comes to nuclear engineering, details matter a lot. It's unfair to make comparisons.''
The N Reactor, which is owned by the Department of Energy, primarily produces plutonium for nuclear warheads. Steam given off as a byproduct is used at an adjoining 860-megawatt power plant.
The N Reactor has been plagued in recent years by periodic failure of some of its 16,000 fuel elements, but there has never been a serious problem reported at the dual-purpose facility.
Lawrence said one key difference between the N Reactor and the crippled Chernobyl plant is the Soviets ''burn'' uranium fuel an estimated 18 times longer than their counterparts at Hanford, greatly increasing the chance of an accident.
Another difference, Lawrence said, is that the N Reactor operates at a lower temperature -- about 600 degrees Fahrenheit -- and the hottest the reactor core would ever get is 1,000 degrees. He said graphite needs to be heated to 2,200 degrees before it burns.
''N Reactor has some other features that make a graphite fire or release of radiation material unlikely,'' Lawrence said.
He said the N Reactor features an independent graphite cooling system, and in the event of a problem the reactor core can be flooded either with water or an inert gas, such as helium.
''There are so many differences in so many critical areas it's like comparing a Mack Truck to a compact,'' Lawrence said.