Flooding at the Nuclear Plant: Disaster by Design/Safety by Intent #1 via All Things Nuclear

Disaster by Design

The March 2011 disaster at the Fukushima Daiichi nuclear plant in Japan did not reveal flooding to be a nuclear safety hazard; it reminded us of this well-known threat. Flooding from internal sources (e.g., broken pipes and failed storage tanks) and from external sources (e.g., heavy rainfall and swollen rivers) had long been recognized as a risk to be managed with an array of flood protection measures. As the following summaries—an abridged sampling among many such events—indicate, there were numerous reminders before Fukushima.


LaSalle (Illinois): Fission Stories #113 described the May 13, 1985, event where one of the circulating water pumps that sent cooling water from the lake through the plant stopped running. A worker dispatched to the pump house to investigate the problem discovered the building filling with water through a broken rubber expansion joint. The pump house flooded to a depth of 15 feet, disabling all the circulating water and service water pumps for both reactors.


The summaries indicate that adequate flood protection relies on (1) preventing water from entering areas housing vital equipment, (2) locating vital equipment in diverse locations to lessen the chances for a flood to disable it all, (3) draining areas containing vital equipment faster than then can flood, and (4) detecting a flooding condition as soon as possible to maximize the time available to successfully intervene.

Flooding is but one of many risks to be managed at a nuclear plant. Properly managing a single risk factor would be relatively simple. Properly managing multiple risk factors, often at odds with one another, complicates the task quite a bit. For example, installing fire headers and fire sprinklers within a nuclear power plant decreases the fire risk. But it increases the flooding risk. It’s not a matter of choosing which risk to manage and which to neglect; it’s a matter of understanding all the risks and developing designs and procedures that effectively manage them.

Read more at Flooding at the Nuclear Plant: Disaster by Design/Safety by Intent #1

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