COLORADO--Federal marshals arrested at least 150 anti-nuclear activists trained in civil disobedience Sunday when the protesters marched in front of the Rocky Flats nuclear weapons plant about 16 miles northwest of Denver. Rocky Flats is the nation's only producer of plutonium "triggers" for nuclear weapons.

About 300 Colorado protesters, led by Daniel Ellsberg '52, had trained for weeks in a plan to blockade three entrances to the plant. However, about two dozen federal marshals and security guards from Rockwell International were waiting to greet them at the plant's east and west gates and at a railroad spur leading into the facility. Ellsberg was arrested at the railroad tracks, just as he had been while protesting against the plant exactly a year ago.

Big Steps

While their fellow protesters cheered from across the road, the demonstrators walked into the Denver County Sheriff's department bus. Magistrates were standing by to receive the demonstrators at a makeshift booking station at the U.S. Geological Survey headquarters in Lakewood, a Denver suburb. Six attorneys accompanied the demonstrators and offered free counsel.

The confrontation was a militant follow-up to a mass rally at the weapons plant. On Saturday, more than 10,000 demonstrators, three times more than the organizers expected, assembled in damp, chilly weather to sing, hear speeches, and demand that the plant be shut down or converted to non-military use.

Other anti-nuclear demonstrations were staged over the weekend at a ski slope in Vermont, on a farm in Arkansas, on the banks of the Hudson River in New York, and on a Navajo reservation in New Mexico.