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Regional News
| Article published Saturday, March 29, 2003
DAVIS-BESSE
Design
flaws slow plant restart
FirstEnergy
needs to address NRC concerns with 2 pumps
By TOM
HENRY
BLADE STAFF WRITER
OAK HARBOR, Ohio - FirstEnergy Corp. has been
dealt a major setback that could keep Davis-Besse idle weeks longer
than anticipated, possibly well into the summer.
A senior
Nuclear Regulatory Commission official yesterday told The Blade that
design flaws have recently been discovered in two pumps that would
be used to cool Davis-Besse’s reactor core in the event of a nuclear
accident.
Jack Grobe, NRC oversight panel chairman, said the
agency questions the operability of the plant’s two high-pressure
injection pumps. Those pumps would be called into action in a
worst-case scenario to re-circulate water containing boric acid
through the reactor in order to get the hot core under control in
the event of an emergency.
The injection pumps are a separate
and independent issue from the plant’s four reactor coolant pumps,
which have been the focus of a federal whistleblower complaint, NRC
scrutiny, and several recent stories in The Blade. The reactor
coolant pumps are in operation when the plant operates and are used
to circulate coolant water through the reactor during normal
operation, officials have said.
"There’s a question regarding
those [high-pressure injection] pumps," Mr. Grobe said. "It’s the
design in the bearings in the high-pressure
injection."
Officials have no doubt the high-pressure
injection pumps would work in the first few minutes of a so-called
"loss of coolant" emergency, when they would be moving purified
coolant water from an emergency storage tank to cool the reactor
core.
It’s what could happen next that has NRC officials
concerned. The approximately 400,000 gallons of purified water from
the emergency tank would eventually be expended in about 30 minutes
or less. At that point, the plant’s design calls for the
high-pressure injection pumps to begin recirculating the used,
unpurified water collected from sump pumps in the floor below the
reactor.
The NRC is concerned that small pieces of debris
that could settle in the water in the sumps may cause bearings to
fail within the high-pressure injection pumps as they recirculate
that unclean water to cool the reactor.
"There’s a point in
time in which you have to switch over and go to recirculation mode,"
Mr. Grobe said. "Water in the sump wouldn’t be as
clean."
"It’s a question: Are these adequate for sump water?"
he said.
The problem was brought to the NRC’s attention by
FirstEnergy officials as part of the plant’s overall system health
review process that began in the late fall and ended in February,
Mr. Grobe said.
Mr. Grobe said the review of the emergency
coolant system occurred because of Davis-Besse’s extended outage,
which began Feb. 16, 2002, and has continued because of the
discovery of a hole from extensive corrosion of the reactor head or
lid.
In addition to replacing the reactor lid, the utility
has been dealing with a number of other equipment problems at the
aging plant.
FirstEnergy has narrowed its list of options for
dealing with the high-pressure injection pumps to three possible
courses of action: replace the pumps, rebuild them, or install a
more efficient filter system to screen debris from getting into the
pumps. A decision is expected late next week, said company spokesman
Richard Wilkins.
Replacement is the most expensive option,
with an estimated price tag of $2 million to $3 million. But it
could end up being the most practical, depending on the company
analysis, he said.
Mr. Wilkins declined to provide an
estimate on how long any of the options would take, except to say
the project is clearly one that cannot be accomplished in a day or
two.
The matter is expected to come before FirstEnergy’s
board of directors at a meeting in April, he said.
NRC
officials said projects such as these occur so infrequently that
there is not an industry standard to gauge the potential time delays
for each of the options specified.
"If they replace them,
that’s going to be a matter of weeks," according to an NRC official
who asked not to be identified.
Whatever option is chosen,
the work will be done in parallel with other remaining projects
under way to lessen the plant’s down time as much as possible, Mr.
Wilkins said.
He said the company now has pushed back plans
for testing the strength of the reactor’s steel containment shell,
as well as the concrete containment building that encapsulates it,
to mid- to late-April.
Both the containment shell and the
containment building need to be tested because they were cut open so
the company could replace the damaged lid with a never-used one
acquired from a mothballed plant in Midland, Mich.
Mr.
Wilkins said plans for a week-long pressure test of the reactor
itself have been delayed indefinitely. The plant has to be running
for that test, except all control rods will be inserted into the
core so no nuclear fission occurs.
The pressure test is one
of the biggest involved with the plant’s restart and has been
ordered, in part, to see if the bottom of the reactor has any leaks
like those that ultimately corroded the reactor
head.
For earlier Davis-Besse stories, go to
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