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Duke Energy Downplays Flooding Risk at Oconee Nuclear Plant

By John Daly | Fri, 16 November 2012 21:50 | 2

Of the 34 nuclear facilities from South Carolina to Vermont in Hurricane Sandy's path, 24 continued to operate safely and generate electricity throughout the event. Seven were already shut down for refueling or inspection, and three in New Jersey or New York safely shut down, as designed, because of storm conditions or grid disturbances.

Nuclear Energy Institute president and Chief Executive Officer Marvin S. Fertel said, "Hurricane Sandy once again demonstrates the robust construction of nuclear energy facilities, which are built to withstand extreme flooding and hurricane-force winds that are beyond that historically reported for each area. Beyond the physical strength of these nuclear power plants, the professional crews that operate and maintain them take exacting precautions as significant storms approach. They also coordinate with local, state and federal emergency response officials.

Our facilities' ability to weather the strongest Atlantic tropical storm on record is due to rigorous precautions taken in advance of the storm. In the days prior to Sandy storming the Atlantic coast, nuclear plant operators took a series of actions outlined in their emergency preparedness plans. These include securing or moving any equipment that could possibly become airborne due to high winds and verifying that weather-tight doors and water intakes are prepared. Each plant site also has numerous emergency backup diesel generators that are tested and ready to provide electricity for critical operations if electric power from the grid is lost. Actions taken by companies operating reactors in the mid-Atlantic and Northeast once again demonstrate that nuclear energy facilities are well protected against extreme natural events."

Or are they?

The issue is not insignificant, as North and South Carolina together supply 11.5 percent of the entire nation's nuclear energy electrical output.

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According to the July 2011 the NRC Office of Nuclear Regulatory Research Division of Risk Analysis report, “Screening Analysis Report for the Proposed Generic Issue on Flooding of Nuclear Power Plant Sites Following Upstream Dam Failures,” Fertel’s optimism might be misplaced, at least in the case of South Carolina’s Oconee Nuclear Station. The report, incidentally, is labeled “Not for Public Release.”

The report indicates that the NRC has known for a decade or longer that failure of a dam upriver from the Oconee Nuclear Power Plant (NPP) in South Carolina would cause floodwaters from a sustained rainfall to possibly overwhelm the NPP’s three reactors and their cooling equipment, creating a situation like in 2011, when tsunami waters caused Japan’s Fukushima Dai-chi six reactor NPP facility to fail after floodwaters destroyed both power facilities and drowned backup generators. As a measure of the NRC’s concerns, the Oconee NPP is mentioned 43 times in the 45 page report.

The report notes, “With regard to Oconee Nuclear Station, recent estimates of the resulting flood levels from failure of the upstream dam have increased substantially relative to previous estimates, and the site is theorized to enter station blackout due to loss of offsite and station power (ONS 1995, p. 5-23) and the final remaining power source in the Standby Shutdown Facility as it is overcome by high water levels (Duke 2008, att. 2, p.10).”

In another unsettling passage, the NRC report adds, “The current licensing basis for Oconee Nuclear Station did not consider the impact of failure of Jocassee Dam when calculating potential flood levels at the site. Based on a letter written by Duke Energy in 2008, failure of Jocassee Dam has been considered a beyond design basis event and managed as a risk assessment issue (Duke 2008, att. 1, p. 7).”

Duke Energy (NYSE: DUK) operates both the Oconee NPP and the upstream Jocassee Dam. Perhaps the most unsettling statement in the NRC report is, “A more recent NRC letter (USNRC 2009) indicates that the NRC staff’s position is that a Jocassee Dam failure is a credible event and needs to be addressed deterministically. In the same letter, NRC staff expressed concerns that Duke has not demonstrated that the Oconee Nuclear Station units will be adequately protected.”

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But Duke Energy's Preston Gillespie, the site vice president at Oconee, said the Jocassee Dam was designed, stating that since Fukushima, every U.S. NPP had reassessed risks and that Duke Energy had already increased the heights of barriers around critical equipment, noting "We had a head start because of work our engineers had done," while John Boska, the project manager in the federal Office of Nuclear Reactor Regulation, said Duke has been addressing flood risk at Oconee "for years."

NRC spokesman Scott Burnell was less sanguine, noting that a taller wall to divert a flash flood from Jocassee Lake down the Keowee River basin to Hartwell Lake was among the possibilities, but "The long-term effect you want is to keep water away from the plant. At the same time, if you don't plan that properly, you could divert water somewhere where it does more harm or, depending on whether it's planned properly, the diversion wall could present other issues for the plant. If you put the wall in the wrong place, you could hold water in."

And the Nuclear Regulatory Commission risk analysis engineer Richard Perkins has written to the NRC’s inspector general that the NRC “has been in possession of relevant, notable and derogatory safety information for an extended period but failed to properly act on it.”

The divergent views of various NRC personnel are hardly a cause for optimism, and only the most obtuse would deny that Hurricane Sandy was an minor event, as according to Jeff Masters, a former flight meteorologist "hurricane hunter" with the National Oceanic and Atmospheric Administration, Sandy is the largest such storm to make landfall on the Atlantic seaboard since the government began keeping records in 1988.

But obviously, given the factionalism in the NRC and the bland assurances from Duke Energy, Palmetto State residents are apparently just going to have to sit the next big one out.

By. John C.K. Daly of Oilprice.com

Leave a comment

  • David B. Benson on November 18 2012 said:
    There are divergent opinions with NRC of this matter because?

    I assume that various water flow computer models show different outcomes? Or perhaps NRC staff lack sufficient expertise on hydrological matters? Or possibly, just possibly, failure of the dam is not a credible threat.

    Ordinarily in the design of a dam there is ample provision for spilling flood waters once the reservoir is at capacity. Modern dam failure in the US is exceedingly rare.
  • ellie on November 21 2012 said:
    And it's not just Okonee that's staring a nuclear disaster in the face. There's serious concern around Europe as well (particularly pertinent case: http://www.pressdisplay.com/pressdisplay/showlink.aspx?bookmarkid=J3HL2E1REN28&preview=article&linkid=e906891c-c188-498e-8431-d87295eb4991&pdaffid=ZVFwBG5jk4Kvl9OaBJc5+g==). Even though economically the best fuel source, perhaps these past events leave something to consider.

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