An explosion early yesterday at a natural gas processing facility two miles from the Calvert Cliffs nuclear power plant in southern Maryland killed one man and severely burned another, officials reported.

A spokesman for the National Transportation Safety Board, which is investigating the incident, said the blast posed no danger to the power plant but shut down the Columbia LNG Corp., a liquefied natural gas facility at Cove Point, Md., that pumps several hundred million cubic feet of gas a day to the Washington metropolitan area.

The two-year-old Cove Point terminal, which unloads liquefied gas from insulated tankers that keep it cooled below minus 260 degrees Fahrenheit, has been the subject of a long controversy between energy companies and environmentalists.

Environmental groups have warned that a spill of LNG from one of the great tankers or a major accident at the storage area could touch off an explosion and fire of disastrous proportions. Industry supporters discount the risks, claiming it is safer than oil.

Columbia LNG spokesman Bruce Quayle said the shutdown, expected to last about a week, would not affect deliveries because gas would be routed here from other pipelines.

The explosion ripped through the cinder block electrical substation at 3:30 a.m., killing Charles Bromley, the 31-year-old plant operator. Henry Hunter, 30, a coworker, was flown by helicopter to the burn unit at Washington Hospital Center where he was reported in serious condition with burns over 25 to 30 percent of his body.

Robert King, an investigator for the federal safety panel that investigates accidents involving pipelines, said the cause of the explosion had not been determined late yesterday.