Abstract: On November 12, 2019, at 3:30 p.m., a six-man crew that had been hired to perform a commercial diving job, installing an 18-inch blind flange on a pipe inside a Nuclear Power Plant service water tunnel, were involved in an incident resulting in the death of one of the divers. Employee #1, an in-water tender, entered the water service tunnel to set up a robust barrier to prevent other divers from entering the area where a pump was required to remain in operation. After Employee #1 reached the floor of the tunnel, he set down a pneumo tube, for recording the diving depth. He reported the depth to Employee # 2, the project manager. When Employee #2 attempted to verify the reading, he realized that the diver was unresponsive. He ordered the up-top tender to attempt communication by tugging on the line. The diver was still unresponsive. Employee #2 then ordered the primary diver, Employee #3 to enter the space to attempt rescue. Employee #1 was found trapped in the elbow of a 30-inch pipe. He suffered multiple blunt force trauma and was killed.