Production of a critical ingredient for solid rocket fuel resumed Monday at a Kerr-McGee Corp. plant, five weeks after explosions destroyed the only other plant making the chemical a mile away.

Workers began production of the chemical, ammonium perchlorate, which provides the oxygen necessary to burn solid fuel in the booster rockets on the space shuttle and in some military rockets.

Plant spokeswoman Annita Bridges said workers will be on the job around the clock in three shifts as the plant in nearby Henderson gears up to operate at its capacity of 36 million pounds of the chemical a year.