The odds of a meltdown at the Davis-Besse
nuclear power plant were higher than people were led to believe
prior to the plant’s shutdown last year, the Nuclear Regulatory
Commission said yesterday.
The NRC said the risk posed by the
faulty design of the plant’s original high-pressure injection pumps
is no doubt higher than the agency’s baseline "green" rating for
safety significance.
The agency said it needs more
information from FirstEnergy Nuclear Energy Co. before it can make a
final determination as to the degree of risk.
Davis-Besse has
been idle for 20 months, after management and performance issues
that emerged since the discovery of a near-hole in the plant’s
reactor head in March, 2002.
The rust problem is the worst of
its kind in U.S. nuclear history.
The NRC rates certain
problems on a color-coded scale for safety significance, starting
with green for very low significance. White, yellow, and red colors
are used for moderate to extreme risks, with red being the most
dangerous.
The agency gave FirstEnergy a red finding on Feb.
25 for letting Davis-Besse’s reactor head become so thinned by rust
that it nearly burst and allowed radioactive steam into the
containment building. A replacement head has been
installed.
On Wednesday, the NRC formalized its safety
assessment of Davis-Besse’s containment sump flaw as
yellow.
Officials have said the only reason the utility did
not get a red finding was because it’s possible the sump would have
worked in accidents that involved only a small loss of
coolant.
The sump, which has been rebuilt, was prone to
clogging if coolant losses were medium or heavy.
The sump is
designed to work in conjunction with Davis-Besse’s pair of
high-pressure injection pumps if a major accident occurred. Those
pumps would be used to inject coolant water forcibly over the
reactor if the plant lost off-site power.
At some point, the
high-pressure injection pumps likely would be spraying recirculated
sump water, which likely would have bits of debris collected off the
floor. Company officials have found that debris could make the pumps
overheat, vibrate, or otherwise fail. That would render them useless
at a critical time, officials have said.
FirstEnergy is in
the process of testing its plan for rebuilding Davis-Besse’s
high-pressure pumps at an Alabama laboratory. A lab spokesman told
The Blade yesterday preliminary test results are
encouraging.
In addition, Richard Wilkins, a FirstEnergy
spokesman, said the company is pleased by results so far. Rebuilt
pumps have operated in the lab for more than a month without
clogging, Mr. Wilkins said.
Jack Grobe, chairman of the NRC
panel overseeing Davis-Besse restart efforts, said in a letter sent
Wednesday to Lew Myers, FENOC chief operating officer, that
"escalated enforcement action" is being considered as a result of
the agency’s latest finding.
The NRC believes FirstEnergy has
violated a federal regulation by failing to make sure the pump would
have worked years ago, the letter said.
For more
information on Davis-Besse, go to
www.toledoblade.com/davisbesse.
