On June 27th, Fairewinds Associates nuclear engineer Arnie Gundersen stated in an email:
"It's not about the containment or the auxiliary building at Ft. Calhoun!
Everyone is looking at the wrong building ... look at the little building along the river ... it is the intake structure ... that is where the emergency service water pumps are located ... they provide the cooling water that runs through a heat exchanger that cools the nuclear core and the spent fuel pool ... how much more does the river have to rise before the emergency service water pumps flood? At Fukushima, the intake structures were destroyed and the reactors would not have been cooled even if the diesels had worked. This is called the "loss of the ultimate heat sink."
Also, note that some non-safety related buildings are flooding. Water has entered the lower levels of the turbine hall and is being pumped back out. While not safety significant, there could be an economic impact if electrical equipment in these areas gets wet.
Also, the ground under the foundations to these safety related structure are now saturated. There are numerous underground safety related electrical wires that are required to run those emergency service water pumps along the river. What does all that water do to settling of the buildings in the future or to the seismic analysis?
Finally, the unlikely event with the most serious consequences is the failure of an upstream dam. Barring the failure of one of the six upsteam dams on the Missouri, it is not likely that the water level will reach the containment's design basis flood height. Barring a failure of one out of six dams that are 50 years old and have never experienced these high flow conditions before .....".