Abstract: At 9:30 a.m. on November 12, 2021, an employee and two coworkers were sanitizing a polishing tank which is used to deionize water for site use. Around 8:30am they starting setting everything up so they could pump a 35% hydrogen peroxide solution in the tank. They ran a hose from a 55 gallon drum of hydrogen peroxide to the pump and then to the nitrogen intake valve at the top of the tank. Once the pump was set up, Coworker #2 left to work on something else while the employee and Coworker #1 stayed to observe progress. After about 30 minutes, approximately 75% of the 55 gallon drum had been transferred to the polishing tank. At this point, the employee and Coworker #1 turned off the pump and approached the polishing tank to open a side valve in case of pressure build up. As the employee was opening the valve, an explosion occurred killing him and injuring Coworker #1. The employee was burned and incurred multiple fractures in explosion.