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Regional News
| Article published Thursday, June 26, 2003
Besse faces new problem with pumps
By TAD VEZNER
BLADE STAFF WRITER
Davis-Besse’s pressure-pump problems have hit
what plant officials are calling another "tiny" snag.
In
theory, a tear the size of a fingertip could overheat the two
high-pressure emergency injection pumps that flush the plant’s
reactor core with water during emergencies.
Davis-Besse is
being refurbished after a football-sized hole was found in the
carbon steel of the reactor head while the reactor was shut down for
routine refueling in February, 2002. The corrosion left only a
stainless-steel lining less than three-eighths of an inch thick to
prevent a high-pressure rupture.
Davis-Besse has had problems
with the emergency pumps before.
FirstEnergy Corp., the
plant’s owner, is spending a little over $3 million to fix a prior
flaw relating to the possibility that the pumps’ bearings could be
damaged by debris during high-pressure usage. A pair of extremely
fine "strainers" are being installed to filter debris and keep the
bearings protected.
Now there’s another hitch. According a
report by an NRC inspection team that FirstEnergy reviewed and
agreed with, the emergency pumps could overheat if one of the pipes
carrying water to the core - pipes the pumps are responsible for
servicing - were to tear to a very small degree: a half-inch or
less.
The difference in temperature between the heated
reactor core and cool water coming through the tear could create a
counter-pressure that could cause the pumps to overheat. "It’s a
very unlikely scenario; we’re not sure it would ever actually
happen, even in extreme situations," said FirstEnergy spokesman
Richard Wilkins. "But we’re fixing it."
To correct the
problem, engineers at the plant will connect two-inch-wide emergency
valves to the core ends of the pipes serviced by the emergency pumps
- in effect, a set of emergency valves for the emergency
pumps.
If one of the emergency pumps has the type of pressure
plant officials fear would make it overheat, the valve on the bottom
end of the line would open to relieve the counter-pressure on the
pump.
Fixing the new design flaw should "only cost a couple
of thousand dollars" and "only take a couple of weeks," Mr. Wilkins
said.
"The big test will be our ‘full-pressure test’ in
mid-July," Mr. Wilkins said. During that test, plant engineers will
increase water pressure in the pump system to its operational
capacity of over 2,000 pounds per square inch for several days, then
shut it down for final inspections. "That’s when we’ll know how we
really stand," he said.
But Viktoria Mitlyng, an NCR
spokesman, said regardless of FirstEnergy’s hopes, the NRC’s
emphasis is on safety, not schedules. "In addition to the pump
system, there are other major issues that need to be addressed
before the plant goes online," she said.
Of primary concern
to the NRC are issues connected with a "safety-conscious work
environment" - in other words, workers feeling free to bring up
problems at the plant and having their concerns heard.
"The
problem with the plant’s safety culture is one of the things that
brought about the reactor head degradation in the first place," Ms.
Mitlyng said. Still, she said FirstEnergy has made some progress and
is heading in the right direction.
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