NRC hearing raises questions about safety at nuclear plants
A hearing of the Nuclear Regulatory Commission (NRC) pointed to apparent weaknesses in the regulation of nuclear plants.
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A safety task force staff told the five-member commission that America's nuclear plants were safe, but noted that:
• In many cases, older "vintage" plants that undergo relicensing examinations to operate an added 20 years are not required to bring those plants fully up to current safety standards
• NRC regulations have never formally recognized the possibility of an extreme event – like an earthquake or tornado – simultaneously knocking out both on-site and off-site power at a nuclear plant, as happened at the Fukushima Daiichi plant in Japan.
• The nation's nuclear plants have "different licensing bases and associated safety margins," with variations among the plants depending upon their age.
• "Hardened vents" installed to protect US boiling water reactors with the same design as the Fukushima plant were "not included in regulations" and, as a result, were not subject to regular inspections to ensure that they operate properly in an emergency.
• Key valves associated with the hardened vents "were not specifically designed for operation during a long-term station blackout" and therefore might be difficult to open in the event of a Fukushima like incident. [Editor's note: The original version misstated the task force's finding on this point.]
During his presentation, the team leader of the 90-day task force, Charlie Miller, noted multiple times that older power plants were not necessarily required to be upgraded or retrofitted to meet newer safety standards or a better understanding of environmental threats like earthquakes as knowledge about them grew.
"We just wanted to point to the fact that various vintage plants, based on what the knowledge was at the time, were licensed to those things," Dr. Miller said in his report. "The design basis for those plants were set at the time – at the time that they were licensed – and it's variable across the spectrum of the plants depending upon their vintage.
Later in the meeting, NRC Chairman Gregory Jaczko asked whether the task force had considered the possibility that the relicensing process that permits older plants to operate an added 20 years might need to be toughened.
"At license-extension time we have an opportunity, although the commission has not availed itself of that opportunity, to in a sense re-baseline everybody's design basis or licensing basis at this point," Dr. Jaczko said, "so everybody at that point has a consistent understanding of what is the definition of safety, what is the definition of external hazard? Is the task force looking at that at all as a specific way to address this?"