Flood Risk to Reactors Underestimated and Unaddressed

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Flood Risk to Reactors Underestimated and Unaddressed

Upstream Dam Failures May Cause Fukushima-Level Events at “Multiple” Plants

Washington, DC — Newly released documents indicate that several U.S. nuclear power plants are vulnerable to dam-induced flooding with catastrophic results, including core meltdown and massive public exposure to radiation byproducts, according to Public Employees for Environmental Responsibility (PEER). The Nuclear Regulatory Commission has been slow to recognize the risks but has yet to require plant operators to increase flood protections.

A document entitled “Screening Analysis Report for the Proposed Generic Issue on Flooding of Nuclear Power Plant Sites Following Upstream Dam Failures” (July 2011) prepared by NRC’s Division of Risk Analysis, which PEER obtained in a Freedom of Information Act suit, reaches some sobering conclusions:

  • “Failure of one or more dams upstream from a nuclear power plant may result in flood levels at a site that render essential safety systems inoperable.”;
  • “The totality of information analyzed in this report suggests that external flooding due to upstream dam failures poses a larger than expected risk to plants and public safety…”;
  • “This scenario is plausible at multiple nuclear power plants….” The report looks at 32 reactors at 20 sites across the country;
  • The danger of flooding has been largely unexamined by the NRC since “identification of flood-related issues resulted from particular scrutiny and analysis of flood protection preparations, assumptions and procedures. It is unlikely that concerns related to dam failure flooding …would have stood out based on the [NRC licensing] documents alone”; and
  • NRC does not even consider the combination of dam failure and extreme weather events, such as “wind-generated waves and runup.”

“The NRC has yet to come to grips with the very real danger of flood-induced core meltdowns,” stated PEER Counsel Kathryn Douglass. “This past week, Colorado experienced the combination of flooding, dam washouts and record rainfall which, if upstream of a reactor, could produce cataclysmic consequences.”

Another document NRC surrendered to PEER is a detailed letter from NRC Reliability and Risk Engineer Lawrence Criscione to the Commission Chair, dated September 18, 2012, outlining detailed concerns about the vulnerability of the three-reactor Oconee nuclear complex in South Carolina to failure of the upstream earthen Jocassee Lake Dam. Criscione’s letter outlines that:

  • In the event of dam failure, Oconee’s 5-foot floodwall could be swamped by over16 feet of water;
  • Even the reactor’s operator, Duke Energy, concedes that “When containment failure occurs, significant dose to the public would result”; and 
  • Despite knowing about the risk for 20 years, no protective steps have been taken. The NRC extended the original 2011 deadline for Duke to take any protective steps back to 2016.

“By postponing corrective action, the NRC is playing Russian roulette with public safety and the American economy, merely hoping the right disastrous combination of credible events does not line up,” Douglass added, noting that the NRC is still withholding portions of other documents on the issue. “Compounding the problem is that it required litigation before the NRC grudgingly but only partially confided anything about this continuing threat to the American public.”


View the NRC Screening Analysis Report

See the list of 32 reactors at 20 sites

Read the Criscione letter to the NRC Chair

Look at the PEER lawsuit

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