Sundance area residents will hear an environmental samplings report from Ellsworth Air Force Base in South Dakota tonight, regarding radioactive contamination from an old nuclear-powered radar site on Warren Mountain.

The public information meeting is at 7 p.m. at the Crook County Courthouse.

A water tank connected to a portable nuclear reactor once used to power the Air Force radar station near Sundance during the Cold War apparently leaked radioactive material, and officials have taken numerous soil samples to see if the site must be cleaned up.

Under the Army's Nuclear Power Program, portable nuclear reactors were developed and installed in remote locations, including Camp Century, Greenland; McMurdo Station, Antarctica; Fort Greely, Alaska; the Panama Canal Zone and seven miles north by northwest of Sundance.

County Commissioner Floyd Canfield said he and his fellow commissioners have received extensive briefings and he foresees no environmental problem with the site.

"There's only a minor trace of radioactivity," he said.

Air Force officials compare the site's radioactive emissions to the natural radioactive emission of a Coleman lantern's mantle. "We're confident that it is safe," Canfield said.

Tim Pavek, a cleanup expert based at Ellsworth Air Force Base, said in a January interview that the Warren Peak radar base was one of 100 or so stations lined along the northern tier of states in the 1950s and 1960s. It was designed to detect missiles that might someday come over the North Pole from the Soviet Union.

Pavek explained that during the operation of the reactor, between 1962 and 1968, a 12,000-gallon tank holding contaminated water sprung a leak, washing cesium-137 downhill to the northwest.

"We've tracked it horizontally and after a few hundred feet, it disappears and can't be distinguished from the background level of natural radiation," he said.

The reactor and tank were removed in 1968.