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What caused the cracks in the shield building at the
Davis-Besse nuclear plant and
what needs to be done to ensure the building’s long-term safety? The
NRC’s current inspection is focused on making sure we are satisfied with
FirstEnergy’s answers to these questions.
We’ve
previously written about the NRC’s exhaustive efforts to ensure the
cracks found in the shield building around the Davis-Besse nuclear power
plant’s containment structure are not compromising current safety. We
will continue to take the necessary steps during the current inspection
to make sure that the reasons for these cracks are well understood and
FirstEnergy’s proposed actions to ensure the building’s long-term safety
will accomplish this goal.
First,
we studied the initial review done by the plant’s owner – FirstEnergy –
in their root cause analysis to gain a better understanding of how the
company arrived at its conclusions.
Then,
a team of four NRC inspectors went to the plant with about 80 questions
associated with this initial review. They recently finished a week-long
inspection verifying the initial information and questioning the
company’s conclusions. While at the plant, the NRC inspectors also
reexamined the condition of the shield building.
By
the time the company submitted the root-cause report to the NRC on
February 28, in accordance with the plant’s commitment to the agency,
our inspectors had already completed observations and verification of
the company’s shield building testing. Months before, NRC inspectors had
traveled to laboratories in California and Colorado to directly observe
tests of concrete samples removed from the Davis-Besse shield building.
These tests are a key component of the cracking analysis and NRC
inspectors need to have confidence in their quality.
The NRC’s actions to accomplish an in-depth review of FirstEnergy’s root cause submittal involve further actions:
•
examining key aspects of the analyses performed by the company’s
contractor to support the FirstEnergy’s root cause conclusions;
•
making sure First Energy considered all possible causes of cracking
based on inputs from multiple sources such as the industry’s and the
company’s operating experience; and
•
thoroughly evaluating the company’s proposed corrective actions to make
sure they are sufficient to maintain the long-term safety of shield
building.
The
NRC’s independent inspection will continue to challenge the company’s
the root cause report and planned corrective actions until we have
confidence in their thoroughness and accuracy.
The
NRC will discuss its conclusions on the adequacy of FirstEnergy’s root
cause analysis and proposed corrective actions at a public meeting to be
scheduled after we complete our inspection. The details of this
inspection will be outlined in a publically available report.
Background
information on the discovery of the shield building cracks in October
2011 and the NRC’s response to the issue can be found in the following
blog posts:
Viktoria Mitlyng
Public Affairs Officer, Region III
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