Fukushima:

The Devil is in the Details

As the accident at the Fukushima nuclear power station continues to unfold, one question on everyone's mind is: Can such an accident happen elsewhere?

The question has several parts. One is the conditions that led to the accident. Clearly, most nuclear power plants are not located in earthquake zones, but some are. Even though the initial evidence is that the tsunami was the main cause of the problems, the earthquake could have been a contributing factor.

Clearly, also, most plants are not located in places where there could possibly be tsunamis, but some are. But are there other natural phenomena that could damage several units--flooding, perhaps, or hurricanes or typhoons?

The other part relates to the plant itself. I've seen a number of articles pointing a finger at plants in the United States that are similar in design to the ones at Fukushima--that is Mark 1 General Electric Boiling Water Reactors (BWRs). Some of these US plants happen to be ones that have been under attack anyway by groups wanting to see the plants shut down. The fact that a plant of similar design has suffered such an accident seems, on its surface, to help justify their arguments to close these other plants.

Those of us in the field know that all these plants are not truly identical, but it has been difficult to get information on the differences, and difficult to explain this point to people whose concerns about nuclear power plant safety have just been ratcheted up by the events in Japan. Indeed it is still unclear which of the many NRC-mandated upgrades to the Mark 1 design over the past decades were implemented in the Japanese units.

TVA Browns Ferry Nuclear Plant
Thus, I was pleased to see an excellent article by Matthew Wald in today's NY Times that lays out some of the probable plant design differences for the Tennessee Valley Authority (TVA) Browns Ferry nuclear power plant. Kudos to TVA for opening their plant to the public eye and helping explain some of these differences.

The article also makes it clear that the TVA personnel are not complacent. Truly, the Fukushima accident has been an eye opener for everyone. We will need to confirm which of the upgrades Fukushima actually implemented and which they did not. Every plant in the world will have to be examined in light of this event, and in some cases, changes will have to be made.

In the meantime, it is very helpful to have a good explanation for some of the differences at other plants that might have helped make a difference at Fukushima--and that would likely make a difference if there were a similarly large external event at another plant.

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