Nuclear Energy Activist Toolkit #20
Literally thousands of tests, inspections, and evaluations are performed at each nuclear power reactor operating in the United States every year. For example, operators compare equipment and plant parameters against expected values. Technicians test the initiating and control circuits for backup emergency systems to verify they will function as intended to mitigate transients and accidents (see NEAT #17 for a discussion of transients and accidents). Engineers review test and inspection results to determine if trends indicate safety margins are being eroded. The overwhelming majority of these tasks confirm that conditions are as expected. But what happens when a test or inspection or evaluation reveals a nonconforming condition?
Sometimes, the answer to this question is easy. For example, when the discovery involves a component within the technical specifications (see NEAT #5 for a discussion of technical specifications) that is clearly broken, the technical specifications explicitly define how long the reactor can continue operating and any compensatory measures that must be implemented. At other times, the answer to the question is not so clear-cut.
To help plant owners reach the right answers to the harder questions, the NRC has issued guidance documents. For example, on July 9, 1997, the NRC released Information Notice 97-48 on finding correct answers to fire protection system questions. This information notice referenced a portion of the NRC’s Inspection Manual outlining the agency’s expectations for evaluating nonconforming conditions.
For example, consider the discovery that a test of safety equipment supposed to be conducted every six months was not performed and that the test cannot be performed while the reactor is operating. If a review of past test results shows that the equipment always passes with ample margin and there’s no reason to suspect it would now fail the test if it could be performed, there would be justification for continued reactor operation.
But consider the discovery that an essential cooling system (such as the cooling for the room housing one of the emergency diesel generators) is impaired. Workers conduct a test of this cooling system in January when the outside ambient temperature is 18°F and the equipment inside the area is not running. Even if the test results indicate the impaired system is keeping the room temperature a degree or two below the acceptance value stated in the test procedure, the non-bounding conditions during the test would likely not support a conclusion that the impaired cooling system is still capable of fulfilling its intended safety mission. In that case, continued reactor operation would not be justified.
NRC inspectors take a keen interest when owners answer questions about nonconforming conditions at operating reactors, especially when those answers allow reactors to continue operating despite the impairments. It’s virtually guaranteed that NRC inspectors will review such answers. As documented in Chapter 3 of UCS’s report on nuclear power safety in 2010, NRC inspectors sometimes determine the answers were wrong. Our report described good catches by the NRC at the Oconee nuclear plant in South Carolina and the Browns Ferry nuclear plant in Alabama. In the Oconee case, NRC inspectors determined both that the initial answer for a problem found on one reactor was wrong and that the problem also affected the other two reactors at Oconee. In the Browns Ferry case, NRC inspectors determined that the initial answer did not cover all potential situations. The NRC inspectors efforts not only remedied the problem at Browns Ferry but prompted a recall of the detective part involved in the problem from other nuclear plants in the country.
Bottom Line
Some problems at nuclear power plants can be easily answered. A blazing fire in an electrical cabinet should be extinguished and its damaged fixed. A ruptured pipe flooding a basement with three feet of water should be replaced and the water removed.
Other problems have more elusive answers. The NRC has communicated its expectations to plant owners to help them not only find these answers, but to find the right answers.
And NRC inspectors review the answers found by plant owners and have not been shy about hitting the Gong for wrong answers.
The UCS Nuclear Energy Activist Toolkit (NEAT) is a series of post intended to help citizens understand nuclear technology and the Nuclear Regulatory Commission’s processes for overseeing nuclear plant safety.