The past several days have been yet another reminder that the hubris of modern engineering can be brought low by the extreme power of mother nature.
The Nuclear Regulatory Commission said it was monitoring the Browns Ferry nuclear power plant near Athens in north Alabama, after it lost offsite power Wednesday night due to the storms. While there was no direct hit from a tornado at the plant, the storms did take down the transmission lines from the plant causing the three units at the plant to shut down automatically when power was lost.
According to the Tennessee Valley Authority, which operates the plant, one of the plant’s diesel generators was out of service for maintenance, but the other seven started to power the units’ emergency loads that provide cooling for the reactors. No radiation was released as a result to the shutdown and the plant remains in a “safe” shutdown mode (you know, like Fukushima Dai-ichi’s units 4 thru 6). Plant operators and Tennessee Valley Authority line crews are working to restore offsite power to all three units but the plant is expected to be down for days and possibly weeks while repairs to the transmission lines are made.
Meanwhile, less than two weeks ago, the Surry nuclear power plant lost offsite power early in the evening, of April 16th when a tornado touched down in an electrical switchyard next to the plant.
The two units at the Surry plant automatically shut down and four of the plant’s diesel generators started to power the units’ emergency loads. As of this writing, NRC’s website shows Surry 1 back online, but Surry 2 is still offline.
Tuscaloosa, Alabama, only 100 miles south of the Browns Ferry nuclear plant, was devastated by an estimated EF-4 tornado over a mile wide that stayed on the ground for 2 hours, leaving behind a shocking landscape of twisted wreckage for seven miles. In light of the devastation wrought by this storm, we should count ourselves very fortunate that these nuclear plants were only the victims of downed transmission lines and damaged adjacent switching yards. While the reactor containment might be able to withstand a tornado of this magnitude, we don’t know how vulnerable the backup systems would be.
One of the lessons we should take away from Fukushima should be – never underestimate the power of mother nature or overestimate our ability to engineer things to withstand the extremes that nature can throw at us.