The company has used high-definition camera technology for examination inside of the building’s walls through a series of inspection ports – or core bores.
This camera provides greater clarity and mobility compared to the previous available equipment.
FENOC had examined 43 of the shield building’s 82 core bores since the start of inspection operations. Meanwhile the remaining examinations expected to be complete in the next several weeks.
The camera had discovered three very tight, subsurface pre-existing cracks in the building that were not visible with earlier inspection technology.
These inspections also have found that in three locations, cracks initially identified in 2011 appear to have propagated a small amount.
Davis-Besse site vice president Ray Lieb said, "Analysis of all inspection results to date confirms the 2011 conclusion that the shield building’s structural integrity is not impacted by the presence of these tight cracks.
"The robust building continues to function safely and reliably. Long-term safe, reliable operation of the plant is our number one goal."
In October 2011, the initial cracks in the shield building were found when the building was opened to install a new reactor head.
As per analysis conducted at the time determined that the building’s structural integrity was not affected.
Later on the shield building was painted with a protective coating and a long-term inspection program was established to ensure continued safe operation of the building.
