So the probabilities of hitting a point structure like a power plant with a tornado drop precipitously compared to a hurricane, and the designbasis for power plants varies accordingly.
"It would either make them think twice about building on flood plain land or it would make them change the designbasis upon which they're built, " he told BBC Radio 4's Money Box.
The NRC determined that the design-basis tornado wind speeds for new reactors should correspond to the exceedance frequency of one-in-ten-million per year.