Elba Sanchez Santiago
Materials Engineering Inspector
NRC Region III
Elba Sanchez Santiago is a
Materials Engineering Inspector in the
NRC's Region III.
There
has been a lot of interest lately in the flaws that were recently found
in the control rod drive mechanism (CRDM) housings at the
Palisades nuclear plant, near South Haven, Mich. I want to share my direct experience with the NRC’s thorough and independent evaluation of this issue.
First,
some background. The control rod drive mechanism moves control rods
inside the reactor to control the level of nuclear chain reaction. The
housing is a metal tube around the control rod drive mechanism, which is
connected to the control rod and prevents leakage of reactor water into
containment.
According
to a commitment made in 2012, the plant conducted inspections of 45
CRDM housings in this reactor and found flaws in 17 of them. Palisades
committed to these inspections after the discovery of a crack in one of
the housings resulted in a plant shutdown in 2012.
Because
of my expertise as a materials engineering inspector, I was dispatched
to Palisades after it shut down in 2012. I was to evaluate the plant’s
response to the discovery of the through-wall crack. As a member of a
special inspection team that further evaluated this issue, I
reviewed
the plant’s testing of eight additional CRDM housings and their
corrective actions. Even though no other cracks were found, the plant
committed to further evaluate the condition of the housings during the
2014 refueling outage.
I
came to Palisades before the current outage started to evaluate the
site’s inspection methodology, work procedures, tooling and personnel
qualifications. When the examinations started, I observed some of the
actual testing and evaluated the results. To date, there is no evidence
of leakage resulting from the flaws. I will remain onsite providing
oversight over the plant’s actions until the issue is resolved.
Since the issue first came to light in
2012, I
have been working with a team of other inspectors and specialists in
Region III and the headquarters office in Rockville, Md., to make sure
we ask the necessary questions to understand the plant’s methodology and
assessments, and independently verify the conclusions.
Our
in-depth independent reviews will continue until the plant completes
the necessary repairs and takes proper actions to make sure the CRDM
housing flaws do not lead to a significant safety concern. The results
of our inspections will be documented in a publicly available inspection
report.
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