NRC and FirstEnergy were in possession of this photo of Davis-Besse reactor vessel head taken during the April 2000 refueling and maintenance outage just prior to allowing the reactor restart for its operational run to the February 16, 2002 shutdown. Photo clearly indicates extensive corrosion occurring on vessel head.

A diagram showing the extent of severe corrosion through the entire reactor pressure vessel outer wall (nearly 7 inches) with only the stainless steel inner liner (3/16 of an inch in some places) remaining.  The inner liner was bulging out into cavity and cracking from extreme operational pressure of the reactor.

Looking down into the Davis-Besse reactor vessel’s corrosion cavity

The Davis-Besse nuclear generating site in Oak Harbor, Ohio near Toledo came as close a matter of weeks from having severe corrosion result in a rupture of its reactor pressure vessel and a potentially catastrophic nuclear accident in 2002.