At about 2:45 a.m. on March 13, 2001, Employee #1 and Employee #2, two operators, and Employee #3, a maintenance mechanic, were assigned the task of cleaning out a waste vessel, KD 502A. The three employees were removing the flange to the pot, and had removed several of the 44 bolts holding the flange, when the pressure in the vessel was violently released, killing all three of the employees.