.

NRC EXAMINING POTENTIAL IMPACT ON NUCLEAR PLANT SAFETY

FROM UPSTREAM DAM FAILURE

The Nuclear Regulatory Commission has started a formal evaluation of potential generic 

safety implications for dam failures upstream of U.S. commercial nuclear power plants. The 

NRC began examining this issue after inspection findings at two plants and recently completed 

an initial screening assessment.

While this screening did not identify any immediate safety concerns, inspections or other 

reviews at individual plants have led to those plants taking appropriate actions regarding 

flooding scenarios. Based on the screening, the NRC staff has recommended that flooding from 

upstream dam failure be further evaluated as part of implementing recommendations from the 

agency’s Japan Near-Term Task Force.

While the Task Force used preliminary information from the screening and mentioned 

flooding in its July 2011 report, the upstream dam issue came to the staff’s attention long before 

the current interest in natural disasters raised by the Japan earthquake/tsunami and reactor 

accident. New sources of information on this issue have accumulated over the past few years. 

This information includes inspections of flood protection and related procedures, as well as

recent re-evaluations of dam failure frequencies and possible flood heights at some U.S. nuclear 

power plants, suggesting that flooding effects in some cases may be greater than previously 

expected. 

The staff is also using the NRC’s Generic Issue Program to consider the effects of 

upstream dam failure on independent spent fuel storage installations. Similarly, a Generic Issue 

has been proposed on the effects of failure of downstream dams on nuclear power plants. The 

NRC’s Office of Nuclear Regulatory Research manages the Generic Issues Program. The effects 

of flooding on fuel cycle facilities are addressed through existing regulations and inspections 

being conducted by the NRC’s Office of Nuclear Material Safety and Safeguards.

 The Task Force’s review of the Fukushima accident led to recommendations regarding 

the potential for flooding at operating reactors. Assessing flooding from upstream dam failure at 

operating reactors will be merged with NRC’s actions on the Task Force recommendations, since

the recommended actions encompass the scope of the new issue.

NRC NEWS

U.S. NUCLEAR REGULATORY COMMISSION

Office of Public Affairs Telephone: 301/415-8200

Washington, D.C. 20555-0001

E-mail: opa.resource@nrc.gov Site: www.nrc.gov

Blog: http://public-blog.nrc-gateway.gov

No. 12-021 March 6, 2012
Nuclear power plant designs include protection against serious but very rare flooding 

events, including flooding from dam failure scenarios. Dam failures can occur as a consequence 

of earthquakes, overflow, and other mechanisms such as internal erosion and operational 

failures. A dam failure could potentially cause flooding at a nuclear power plant site depending 

on a number of factors including the location of the dam, reservoir volume, dam properties, flood 

routing, and site characteristics.

The NRC’s screening assessment of potential nuclear plant safety issues from upstream 

dam failures will be available in ADAMS under ML113500495. 

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