Monitoring of Aging U.S. Nuclear-Plant Parts Unfocused

The U.S. Nuclear Regulatory Commission’s monitoring of aging components in nuclear power plants is “not focused or coordinated,” raising concern that the some safety risks may go undiscovered, according to a watchdog report.

The Oct. 28 report from Stephen Dingbaum, the NRC’s assistant inspector general for audits, comes as some nuclear power plants seek extensions on their operating licenses beyond 40 years.

“Despite concerns of component aging in nuclear power plants that are growing older, the agency does not routinely collect and monitor instances of active component failures due to aging,” Dingbaum wrote.

The NRC “cannot be fully assured that it is effectively overseeing licensees’ management of aging active components,” Dingbaum said in the report.

So-called active components include power supplies, motors, diesel generators, cooling fans, batteries and switches, according to the report.

The NRC disputed the findings almost in their entirety, saying while there isn’t a program specifically directed at monitoring aging active components, any potential safety risks would be discovered in the broader monitoring program.

NRC Response

“Active component aging issues are effectively addressed through various aspects of the regulations and oversight programs,” said Michael Johnson, deputy executive director for reactor and preparedness programs at the NRC, in a written response included with the report.

Regulators, for example, require nuclear operators to report performance issues relating to aging equipment, Johnson said.

Dingbaum said the lack of information on aging equipment means regulators don’t know whether they’re effectively overseeing aging components.

The report points to an instance in 2012 when a failed switch that had been in service for more than 40 years led to an unexpected reactor power change and an automatic reactor shutdown.

“Components degraded due to aging have caused reactor shutdowns, failure of safety-related equipment, and reduction in the safety margin of operating nuclear power plants,” the report said. “Therefore, effective and proactive management of aging of components is a key element for safe and reliable nuclear power plant operation.”

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