Sept 20 Small cracks in the shield building at
the Davis-Besse nuclear power plant in Ohio pose no danger to
the integrity or ability of the structure to operate, the
plant's owner FirstEnergy Corp said on Friday.
During routine inspections, the company said it identified
three "very tight, subsurface pre-existing cracks" in the
building that were invisible to previous inspection technology.
The company also said cracks initially identified in 2011
appear to have grown slightly in three locations.
"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,"
Davis-Besse Site Vice President Ray Lieb said in a statement.
The 894-megawatt plant, located in Oak Harbor, about 120
miles (193 km) north of Columbus, was the site of what the U.S.
Nuclear Regulatory Commission (NRC) has called one of the most
dangerous nuclear incidents in the United States.
In 2002 workers discovered corrosion had eaten a hole in the
plant's reactor vessel head, the repair of which kept the unit
shut until 2004.
The NRC fined FirstEnergy more than $5 million for the
actions that led to the corrosion.
The initial cracks in the shield building were discovered in
October 2011 when the building was opened to install a new
The reinforced concrete shield building provides protection
from threats such as wind and tornadoes. The building surrounds
a carbon steel vessel containing the reactor, FirstEnergy said.
In a move supported by the NRC, the company applied a
protective coating to the shield building and established a
long-term inspection program.
In the most recent inspection, FirstEnergy said it used
high-definition cameras to examine the interior of the
building's walls through a series of inspection ports - or core
The company said it has examined 43 of the 82 core bores and
expects to complete the checks in the next several weeks.