Abstract: At approximately 8:15 a.m. on September 3, 1991, maintenance employees were attempting to repair and replace a leaking hydraulic line in the process room of the main plant. During the repair operation, the incoming hydraulic line separated from its coupling at a point approximately 60 inches above the concrete floor and began to discharge hydraulic fluid at high pressure (800 to 1,200 psi). This high pressure and subsequent flow resulted in hydraulic fluid being sprayed against the floor and onto the nearby natural gas-fueled cooker, which was fully operational. The cooker's normal operating temperature was at least 350 degrees. No lockout/tagout procedures were being followed during the repair. Fire and smoke were produced when the hydraulic fluid contacted the cooker, resulting in the rapid dispersal of combustion products throughout most of the plant. Employees #1 through #24 were killed. (Employee #25 was also killed, but should be referenced in inspection #18552208.) All other employees (#26 through #88) were hospitalized for their injuries except Employees #67, #68, #78, #79, #80, #81, #82, #84, #85, #86, #87, and #88, who were treated and released. Employee evacuation from the building was hindered by locked exterior doors and inadequate means of egress.