The Nuclear Regulatory Commission said last week it had launched a special inspection at the Browns Ferry nuclear power plant to determine how and why a diver received a dose rate alarm during underwater work in the Unit 1 equipment pit.
The plant, operated by the Tennessee Valley Authority, is located near Athens, Ala., about 32 miles west of Huntsville.
The agency said a diver working on an underwater steam dryer system received an electronic dose rate alarm when he approached the equipment pit wall to manipulate a cable. Upon receiving the alarm, the diver immediately left the pit and his unintended dose did not exceed regulatory limits.
The licensee later determined that a basket of used filters had been moved from the spent fuel pool into a position near the equipment wall and this was not communicated to the next shift. NRC’s two-person inspection team will identify the circumstances surrounding the event, review the licensee’s immediate response to the alarm, evaluate their corrective actions and causal analysis, and assess the program for diving, work control, radiological surveys and movement of highly radioactive material. The onsite portion of the inspection is expected to take several days. A report documenting the results of the inspection is expected to be issued within 45 days of its completion.
The event in question occurred Nov. 7, the NRC said.
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Was the diver in the flooded up dryer seperator pit on the refuel floor?
It’s a dose rate alarm not a dose alarm. It is a tool for exactly this type of incident. The diver encountered the alarm and immediately exited the area notifying HP so they could conduct a survey to determine why. The ED (electronic dosimeter) worked exactly as it was suppose to. It alarmed a person in a area that had higher dose rates then what he was briefed on and what the ED was programmed to, which in turn saved the diver from a possible over exposure. The ED is a tool. When a worker gets a dose rate alarm they are to back away from that area, the alarm will stop (If it was a dose alarm the alarm will not stop). notify co-workers so they stay away from the area he got an alarm at, leave the area, and then notify HP in the case of either alarm. HP will then conduct a survey to determine the cause of the alarm.