CARROLL TOWNSHIP -- Even as FirstEnergy officials introduced
industry-leading ideas Tuesday afternoon, they are still faced with
major hurdles in upcoming reviews of technical issues at the
Davis-Besse Nuclear Power Station.
Those technical reviews pose such a potential for problems that
the utility has tentatively scheduled a meeting with the Nuclear
Regulatory Commission to touch on only those issues.
The NRC met with FirstEnergy officials Tuesday as part of a
monthly progress report on the Davis-Besse plant, which has been
off-line since February. Workers in March found an unprecedented
amount of corrosion on the reactor head from boric acid leakage.
Jack Grobe, head of the NRC review panel watching the progress at
Davis-Besse, said during the regular meeting that workers have only
begun to identify technical issues regarding calculations involving
critical safety equipment.
The calculations may or may not affect system operations at the
beleaguered plant, but Grobe said he would like to hear greater
detail into the reviews at a meeting tentatively scheduled for Dec.
23.
"The standard that we need to come to as we approach restart is
that all systems are operating correctly," Grobe said. "We need to
know that before we recommend restart."
Grobe did, however, offer compliments by the way of saying
officials have shown steady progress since the last meeting. He
tempered that praise, though, by adding that he and his panel
members would like to see more proof that management is trying to
change the safety culture at the plant.
And while officials said they were still working on that aspect
-- probably one of the largest tasks they have -- they also talked
about three actions that would make Davis-Besse an industry-wide
leader in leak detection and emergency systems.
Those three actions are:
*Modifying the containment sump, which floods the containment
area with coolant water and recycles it in case of a loss of coolant
accident. The modification would expand the square footage of a
screen that sits on top of the sump from 50 square feet to 1,200
square feet.
That is expected to be completed before the plant restarts.
*Implementing a leak rate program to catch even the smallest
leaks as they occur, establishing a new industry standard.
*Installing a leakage detection system called Flus Sensors, which
originated in Europe. The system detects moisture content in the
air, which could be an indicator for a leak.
That system is expected to be installed before the plant restarts
as well.
Those improvements will help in the future, but Davis-Besse
officials are still investigating the cause of boron deposits on the
bottom of the reactor head found in October.
When workers found the initial corrosion in March, it was on top
of the reactor head, and was caused by cracks in nozzles there.
Plant officials believe some of that leakage may have dribbled down
the side of the reactor and pooled at nozzles on the bottom.
However, they have not completely ruled out leakage from bottom
nozzles, although officials said Tuesday the bottom nozzles are not
nearly as susceptible to cracking as the top ones.
FirstEnergy official Jim Powers also offered an alternate
explanation. He said during refueling, temporary seals are placed on
the reactor while flowing coolant water in. It is possible those
seals leaked, causing the deposits on the bottom of the head.
There are "flow trails" to the bottom of the head, but
FirstEnergy official Bob Schrauder added that some nozzles had
deposits on them that were not in the flow path.
Samples have been taken from those nozzles, as well as other
parts of the reactor head. And officials want to reheat the plant
without a nuclear reaction for seven days to inspect the nozzles for
leakage.
That could take place at the end of January.
Originally published Wednesday, December 11, 2002
