Commercial diving takes our human bodies to pretty extreme places and situations – and then packs on an hour or two of challenging physical work. One of these extreme spaces is the hush-hush world of nuclear diving. Nuclear power reactors generate electrical energy with steam from heating large tanks of water via atomic fission.
Commercial divers are often contracted to work on U.S. Naval vessels (cleaning, repairs, inspections), many of these vessels are nuclear powered. Divers must take adequate precautions when diving in areas near the reactor and follow strict guidelines set forth by the U.S. Navy and federal regulations.
These water tanks and their supply system of pipes and valves obviously need maintenance. Commercial divers can do any work that takes place underwater. With the public health risk it would incur, and heavy financial loss of over a million dollars a day, it makes financial and public health sense to send a few highly trained divers into the contaminated tanks instead of draining, working on and then refilling them. The tanks contain water for cooling the reactor, water for emergency cooling, and water that drives the turbines.
Most maintenance takes place during scheduled outages which happen about 18 months apart. Nuclear divers have to work hard conducting welding, electrical work and inspections in hot water, all while balancing speed and safety. When you’re around such sensitive material and it’s so costly to slow operations, there’s a lot at stake.
So safety is built into the very air you breathe inside a nuclear power plant. Everyone working at a reactor wears a dosimeter – and divers wear many – which measures the amount of radiation exposure to the specific body part to which it is attached. Safe and normal radiation exposure, from natural (i.e. non-man-made) sources – including the sun and interaction with other people – is estimated at 620 millirems per year, with 5,000 millirems a year set as the maximum allowed exposure for radiation workers, including nuclear divers. The amount of radiation received by divers is minimal when compared to the amount received during a person’s normal daily routine.
SInce water is a very effective shield against radiation, divers can work in tanks right next to the reactor core. Even so, divers’ levels of radiation exposure are monitored constantly and dives are aborted when even something small goes wrong. But the highest risk of nuclear diving lies in the outside work – in the powerful system of intake valves and pipes.
Power reactors have stiff PR policies and there is precious little public information about daily operations in nuclear reactors. Popular Science published an article about diving in a nuclear plant, not too long after the Fukushima disaster, perhaps in an effort to create a positive narrative about nuclear energy and nuclear plants. What is obvious is that nuclear divers have to be calm, practical and extremely competent, detail-oriented workers — this is not a job for the happy-go-lucky, slap-dash Homer Simpsons of the world!
Watch: The Design and Safe Operation of a Nuclear Reactor, Nuclear Energy Institute
Written for DIT by Londi Gamezde
American Nuclear Society, Radiation Dose Chart
Davenport, J. Dangerous Diving Jobs. scubadiving.com
Goodwillie, D. Swimming on the Hot Side. Popular Science. March 27, 2012.
Hancock, R. Underwater Welding In Nuclear Power Plants
Diving welders keep cool heads in hot water. American Welding Society.
Kranhold, K Why Some Divers Want to Work In Nuclear Reactors. Wall Street Journal. Jan. 18, 2007