Nuclear power stations are designed, built, operated and guarded with multiple, redundant layers of safety and security to ensure that nothing will go wrong – and that in the event of an unlikely mishap, the system will shut down immediately and the consequences will be completely contained.
From Safe to Safer
Dominion Energy’s three nuclear stations serve the largest segment of the company’s electrical customers. The Millstone, North Anna and Surry nuclear stations are the workhorses of the company because they run 24 hours a day, seven days a week over 18-month fuel cycles to provide safe and reliable electricity with virtually no greenhouse gas emissions.
While nuclear energy is one of the safest electrical production technologies in the world, the accident at Japan’s Fukushima Daiichi power station in 2011 led to many changes across the nuclear industry. The Nuclear Energy Institute, the Institute of Nuclear Power Operations and the Electric Power Research Institute formed the Fukushima Response Steering Committee to coordinate and oversee industry response activities. The industry’s “Way Forward” strategy constitutes a coordinated approach that integrates all industry parties’ response to the Fukushima incident.
The nuclear energy industry’s primary and constant goal is to make safe nuclear facilities even safer. Nuclear stations are designed with multiple and redundant safety systems that back one another up in the event that any one system or piece of equipment fails. This is known as “defense in depth.” The various levels of protection are not only redundant, they also are independent of one another. So if one fails, the others can continue protecting the plant, its workers, and the general public.
Inside the Plant
Nuclear stations are built with safety in mind.
Here’s how that works:
The nuclear reactor is used to fission uranium atoms. The heat from this process is transferred in the reactor coolant system to a set of steam generators, which convert water in a secondary system into steam to spin the turbines to generate electricity. Water from a nearby water source — the Long Island Sound for Millstone, Lake Anna for North Anna, and the James River for Surry — is used to condense the steam back into water, to be reheated in a continuous steam cycle. The water used to condense the steam does not mingle with the water used in the steam cycle. Each nuclear unit is designed so that the reactor coolant system continually re-circulates water used to cool the nuclear fuel in the reactor, preventing any radioactive materials from entering outside environment.
America’s nuclear facilities are designed and built to withstand extreme natural forces, from hurricanes to earthquakes, and the added safety margins have paid off. In 2011, a 5.8-magnitude earthquake struck a region of Virginia 11 miles away from Dominion Energy’s North Anna nuclear facility. Both reactors shut down automatically, and emergency equipment safely cooled both reactors, as it was designed to do. The fuel in a nuclear power plant is enriched to a concentration level so low that it cannot explode. In the unlikely event of an accident, the containment building housing the reactor is designed to prevent any radioactive material from escaping into the environment. Incidents like the one at Chernobyl cannot occur in the United States. The Chernobyl plant did not have containment barriers, which are now required throughout the world. The 1986 disaster in the former Soviet Union was the product of a severely flawed reactor design and serious mistakes made by the plant operators, who violated procedures intended to ensure safe operation of the plant.
A severe nuclear power plant emergency, while highly unlikely, would most likely not be a sudden event. It probably would take hours or days to develop. In such a situation, if all redundant safety systems failed to maintain the station in a safe condition, Dominion Energy has a separate set of equipment — including portable electric generators, water pumps and hoses — that can be put in place to keep the station safe. This "FLEX" equipment was installed at every nuclear station in the U.S. following the Fukushima Daiichi accident in Japan. State and local officials would have ample time, in a coordinated effort with Dominion Energy, to take any actions necessary to protect the public.
Training and Oversight
Nuclear stations are run by professionals licensed by the U.S. Nuclear Regulatory Commission (NRC). Highly trained, heavily armed security officers protect the facilities from external threats. Employees are thoroughly vetted through background checks, drug and alcohol screening, psychological screening, a review of education records, interviews with former employers and credit-history reviews. The company has a program to ensure employees are fit for duty on the job. At least half of employees are subject to random drug and alcohol testing each year.
The Nuclear Training Department at each site and company management ensure that operators maintain high levels of safety and proficiency. The Training organization also brings to the operators’ attention any industry operating experience that might have affected nuclear units at other sites around the nation and the world. Operators are expected to internalize the lessons from these episodes to avoid repeating the same experience. They are accountable to the federal government for the safe operation of each station. They spend 20 percent of their time — the equivalent of one day out of every work week — in classroom and simulator training. In addition, they undergo testing throughout their careers to maintain their qualifications to run the units.
Dominion Energy is subject to the oversight not only of the NRC, but also of the Institute of Nuclear Power Operations (INPO), an organization dedicated to the safe, efficient, and excellent operation of nuclear stations. While the NRC’s sole charge is to ensure that nuclear units are operated safely and provides the public with an ongoing, Web-based assessment of each unit’s performance based on a series of safety metrics, INPO’s oversight program is geared toward ensuring that employees engaged in nuclear operations are proficient at their work and exemplary in their performance, so that nuclear operating standards are maintained at very high levels of safety and excellence.