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Risk-based assessments slow aging process for nuclear plants

By Craig Ranson, for Electric Light & Power

Oct 11, 2017

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In the United States, 99 nuclear reactors provide nearly 20 percent of the country’s electricity. However, the average age of these reactors is approximately 36 years old.

Due to rigorous maintenance and safety standards, many plant operators expect to continue safely running their nuclear energy plants for another 25 to 40 years, extending plant operating periods to between 60 and 80 years in total.

Risk-based assessment depends on data gathered during regular component inspections. New inspection techniques such as phased array ultrasonic testing allow utilities to uncover aging-related issues early. These techniques allow inspectors to identify even the smallest indications on a component and get encoded data outputs that map the exact location of the issue. Then, that data is fed into 3-D software that allows the engineering team to get a detailed picture of what is happening to the component.

For example, a careful ultrasonic inspection of a plant’s cables could reveal some degradation of the cable casing. However, if caught early enough, plants can avoid a full-scale, expensive cable replacement and instead simply inject a new cable lining to encase the small signal and high voltage cables inside the plant.

One example of a risk-based assessment that plant operators can apply is probabilistic structural analysis. This approach allows utilities to understand the uncertainty present in a future state of the plant, in turn allowing them to more effectively plan what needs to be done during scheduled maintenance outages. Using probabilistic structural analysis, utilities can develop statistical confidence in an asset management plan for replacing certain structures, systems and components, including various quality assurance and maintenance parts.

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