Abstract: At 10:00 a.m. on August 11, 2021, the plant was shut down for maintenance activities, including the replacement of a knife gate. Employee #1, initially in the control room, proceeded to the ground level to open a valve on the reactor slurry line to prevent solidification. However, an operator in the control room mistakenly turned on the steam in the line. As Employee #1 attempted to rod out the valve, the material broke loose due to steam pressure, spraying hot reactor slurry containing phosphoric acid and ammonia in the area and on the employee. Employee #1 sustained burns to his arms and was hospitalized for treatment.