For nuclear power stations, water is an essential, multi-purpose tool used to generate nearly 20 percent of the nation’s electricity needs. Acting in many roles, water is a barrier against radiation emitted from nuclear fuel. It is also a coolant that reduces high temperatures. Water, in the form of steam, acts as energy that drives the turbine to spin incredibly fast, and also helps condense that steam back into its liquid state.
In a nuclear power station, where there is water, there is always work to do. But, how do you work in water?
In swims nuclear divers.
Nuclear divers are professional, commercial divers who assist nuclear power plants throughout the year with inspections, preventative maintenance and emergent issues.
Jeremy Roach, a Reactor Services technician with Duke Energy’s Oconee Nuclear Station, said his team works with nuclear divers mostly in the spent fuel pools; those pools store spent nuclear fuel for several years before they are moved to a permanent storage location on site. Spent fuel pools are connected to the reactor through an underwater transfer tube.
“They have performed work on our spent fuel valves that close water off to the reactor,” Roach said. “They can also help us with the transfer system ‘up-ender’ that allows fuel to be sent back and forth from the reactor to the pool – divers are essential in order to perform preventative maintenance or when a problem occurs.”
Most recently, Roach said, Oconee partnered with divers to install new components for the fuel transfer system upgrade.
Although divers do sometimes swim in the reactor building itself, Roach said it’s rare.
“It’s not a normal occurrence for divers to be in the reactor building,” he said. “That is typically only for emergent issues.”
While divers are needed in critical fuel storage areas, they are also just as important in other water systems, such as the stations’ condenser cooling water (CCW) structures. At Oconee, the CCW system uses Lake Keowee to pump millions of gallons of water every minute into large pipes that help cool steam back into its liquid state.
Oconee’s Maintenance outage coordinator Jeremy Moore said divers go into the CCW system before each planned refueling outage.
“Divers will dive down to see the structures inside the CCW pump bay,” Moore said. “They’ll look for indications of water levels and make repairs when needed. Of course, the pump is isolated while inspections occur.”
Moore said that divers will also swim on the other side of the intake structure – in the waters of Lake Keowee – to inspect structural concrete and the stainless mesh screens that keep debris out of the intake.
Tom Eason, vice president of operations for Eason Diving and Marine Contractors in Charleston, SC, and his team provide diving services for all of Duke Energy’s nuclear plants, in addition to other nuclear plants and non-nuclear facilities across the Southeast.
“Our main concern when working in nuclear plants is water temperature and radiation,” Eason said. “We wear heavy rubber dry-suits to protect against radiation; that suit can be very hot when you add warmer water temperatures. We wear cooling vests and have specialized equipment to keep us cool when necessary.”
Eason said his team stays busy year-round providing support for nuclear plants, as well as other industries. Eason Diving has provided support to Duke Energy since the 1980s.
“We have good relationships with good people,” he said.