Flooding Sources and Protection

On this page Potential Flooding Sources Plant Protection Options

Potential Flooding Sources

• Storm Surge: An increase in water levels greater than that normally associated with tides.  Typically associated with a hurricane, storm surge occurs when the storm's winds push ocean water onshore. High tides during a hurricane's landfall can enhance storm surge effects
• Dam Failure: The failure of an upstream dam, releasing the reservoir contents.
• Heavy Rainfall: An unusually high precipitation event from a storm over a particular drainage area. Can impact the site directly or through the flooding of a nearby river.
• Tsunami: The sudden displacement of a body of water (such as from an undersea earthquake) that generates an unusually large amplitude wave that becomes even larger when reaching land.
• Seiche: A rise in water levels created by wind-action or similar weather effects acting on an enclosed or semi-enclosed body.  The water level rises when the water surface oscillates, or sloshes, in response to wind.
• Ice Dam: Naturally-occurring dams appearing on rivers and streams adjacent to a site can cause flooding in two ways:  (1) a collapsing upstream ice dam can cause floodwaters at a site; or (2) a downstream ice dam can permit surface water to collect and back up onto the site.

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Plant Protection Options

• Sandbags and/or Inflatable berms: Temporary watertight barriers that would be installed in advance of a flood, designed to keep the site dry.
• Pumps: Both temporary and permanent pumps can alleviate the effects of flooding by removing water from the site.
• Site Drainage: A site's design can reduce or even prevent flooding by directing floodwaters away from vital power plant areas. Drainage systems can be either man-made (drains) or natural (grading).
• Permanent Flood Walls: Man-made structures primarily designed to prevent floodwaters from entering a power plant site. These walls, built from engineered and / or natural materials, can also reduce flood effects associated with erosion, wave action, and debris flow.
• Plant Elevation: Permanently increasing the elevation of a power plant's site during construction helps to ensure potential flooding sources are less likely to affect the site.
• Watertight Doors: Specially-designed doors, similar to those found in submarines, to keep floodwaters away from vital reactor systems and equipment, such as emergency diesel generators.

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