Nuclear power is an important source of electricity in many parts of the world. With more than 500 reactors either in operation or under construction, nuclear power accounts for about 11% of the world’s electrical power generation. Although there are environmental concerns surrounding nuclear power, nuclear electricity generation produces no atmospheric carbon dioxide; as concerns about global warming become more acute, it is likely that this method of generating electricity is going to become more prevalent.
Nuclear power works by using the heat from a controlled nuclear reaction to boil water – in essence, an atomic power plant is a giant teakettle. The steam from the boiling water turns a turbine, which generates electricity. The steam is then recaptured, allowed to condense back into liquid water, and run back through the reactor system. Many reactors also use water to cool the operating machinery of the plant itself. All of this water, of course, must be piped and conveyed and stored. The hydraulic systems of a nuclear power plant are more complicated than the actual nuclear reaction machinery itself, and contain vast amounts of water. Of course, those hydraulic systems need inspection and repair work.
Unfortunately, however, the environment of a nuclear power plant’s cooling systems tend to be unfriendly to human beings, to put it mildly. Since the water is drawn into the plant and boiled, the water that discharges from the condensing system is still very hot. Radiation levels in the coolant system, while nowhere near what they would be in the containment chamber of the reactor, can be significantly higher than the background level. Finally, the conditions in the hydraulic systems tend to be cramped and constricted. All of these things make putting human divers into a plant’s hydraulic system a really bad idea. At the same time, the exceptionally clear water conditions inside the cooling system make visibility exceptionally good.
ROVs, while not immune to radiation (electronic devices can be damaged by high levels of ionizing radiation), can handle levels of radiation that would make a human being sick or increase their cancer risk without any problems. This allows plant operators to use ROVs to inspect cooling tanks for leaks, check the walls of reservoirs, test the condition of intake pipes and storage dams, and measure water conditions in holding tanks. The use of ROVs in hazardous areas eliminates the need to put human divers at risk and also eliminates the need to dewater areas of the plant (often necessitating an expensive and time-consuming shutdown of the plant) for visual inspections.
ROVs are also of use in decommissioning nuclear plants. When a nuclear plant reaches the end of its life, there is a great deal of inspection and demolition work that must go into decontaminating the site. ROVs can be used for visual surveys of underwater structures at the site, to conduct radiometric surveys of potentially contaminated areas, and even assist in demolishing contaminated areas underwater. Tethered ROVs actually perform very well in these areas, because the umbilical connection means that the need for sophisticated electronics on the ROV is reduced – more of the sensitive electronic components are safely away from the contaminated area, in the control console or PC being used to run the ROV. Combined sonar/radiologic surveys of contaminated areas reduce the cost of the physical demolition work, as workers have a perfect map of the area and know which spots are “hot”.
As nuclear power grows more important in providing our civilization’s energy needs, ROVs will play a major role in ensuring that this form of electrical generation is safe and economical.
Nuclear Power Plant Diagram By Tennessee Valley Authority (tva.com) [Public domain], via Wikimedia Commons