WASHINGTON (September 12, 2018)—At least two nuclear power plants may be in harm’s way when Hurricane Florence hits the East Coast later this week: Brunswick near Wilmington, North Carolina, and Surry near Williamsburg, Virginia. Both are vulnerable to hurricane-force winds and flooding, according to the Union of Concerned Scientists (UCS), but just how vulnerable is difficult to say.
There is not a clear picture of either plant’s vulnerabilities because the Nuclear Regulatory Commission has withheld key flood protection preparedness reports it required in the wake of the 2011 Fukushima disaster, where flooding caused three reactor core meltdowns. However, both Brunswick and Surry have had potentially serious problems that their owners may or may not have fixed.
Brunswick owner Duke Energy reported to the Nuclear Regulatory Commission (NRC) in November 2012 that there were hundreds of missing or degraded flood barriers at the plant. The company’s follow-up flood hazard reevaluation report, which it sent to the NRC in March 2015, is not publicly available, so there is no way to confirm that Duke replaced or repaired the barriers.
The NRC’s March 2017 summary assessment of Duke’s 2015 flood hazard reevaluation report states that the company underestimated the potential peak flood height from storm surge at the plant’s safety related buildings, including the buildings housing the plant’s two reactors, by nearly 8 feet.
Finally, a March 2018 NRC flood-related document states that Duke planned to install “cliff edge barriers” at targeted areas on the Brunswick site one to two days before a hurricane landfall. Given there is no other public information about these barriers, it is not assured they will adequately protect the plant.
Surry, meanwhile, was not designed to withstand flooding from heavy rainfall. The key document that is publicly available, plant owner Dominion’s November 2015 flood hazard reevaluation report, indicates that heavy rainfall could cause flooding that overwhelms the plant’s protection barriers.
Although Brunswick and Surry are the most threatened, other East Coast nuclear plants could be at risk from heavy rainfall and flash flooding that is expected even in inland areas.
Besides flooding, wind could be a major factor. Standard industry practices call for plant owners to shut down reactors if wind speeds are higher than 75 mph at the site or are forecast to exceed that speed. Shutting down a reactor does not make it safe, but it provides plant operators more time to deploy contingency measures if the storm disables emergency systems.
Regulations require nuclear plants to be designed to withstand likely hazards, such as hurricanes and earthquakes, without suffering reactor core damage. Based on past meteorological and geological history, plant designers take into account their estimates of the maximum credible hurricane force, earthquake magnitude and rainfall when constructing such protective features as flood walls and seals for doors and other wall openings.
“Nuclear plants are safe from flooding if plant operators properly install protective measures and designers accurately forecast flooding hazards,” said Edwin Lyman, a senior scientist in the UCS Global Security Program and an expert in nuclear plant design. “Falling short on either requirement would make a nuclear plant more vulnerable to floods, which could lead to a meltdown.”
Following the March 2011 Fukushima disaster, the NRC required US plant owners to analyze the effectiveness of their plant’s flood protection features in what the agency called a “walkdown” report, and then reevaluate their facilities’ vulnerabilities to more severe flooding events, including extreme precipitation and hurricanes. When hazards exceeded protections, owners were supposed to close the gap or convince the NRC that the potential hazard would not endanger the plant.
The NRC’s post-Fukushima initiatives were intended to make US nuclear plants less vulnerable to flooding, and the walkdown reports did identify shortcomings in existing flood protection measures, Lochbaum said. But there is at least one instance where a walkdown report was grossly inaccurate. In 2012, Florida Power & Light told the NRC that flood protection measures at its St. Lucie plant were adequate. Two years later, heavy rainfall flooded St. Lucie’s Unit 1 reactor auxiliary building with 50,000 gallons that flowed through flood barriers that had been missing since at least 1982.
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For more on the Brunswick plant: The NRC created a webpage for each nuclear plant listing the reports received from the owners and reviewed by the NRC. The NRC’s webpage for Brunswick is here. Duke Energy’s flooding walkdown report is here. Duke submitted its flood hazard reevaluation report on March 11, 2015, but the NRC has not yet made it publicly available. Most owner reports are publicly available, but the NRC has thus far withheld the one for Brunswick. The NRC’s 2014 assessment of Duke’s flooding walkdown report is here. The NRC’s April 2018 assessment of Duke’s withheld flood hazard reevaluation report is here. Duke’s flooding walkdown report and the NRC’s assessment reports indicate that missing or degraded flood barriers were identified at Brunswick. The reports do not indicate that all the known shortcomings have been remedied.
For more on the Surry plant: The NRC’s webpage for Surry is here. Dominion submitted its flooding walkdown report for Surry to the NRC, but the agency has thus far withheld it from the public. Dominion’s flood hazard reevaluation report is here. The NRC’s assessment of Dominion’s flood hazard reevaluation report is here.