Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
ACCESSION #: 9512280312
Commonwealth Edison Company
Quad Cities Generating Station
22710 206th Avenue North
Cordova, IL 61242-9740
Tel 309-654-2241
ESK 95-223 ComEd
December 21, 1995
Mr. William T. Russell, Director
Office of Nuclear Reactor Regulation
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555
Attention: Document Control Desk
Subject: Commonwealth Edison 10CFR Part 21 Final Report (File 95-15)
Binding of Anchor Darling Valves with Cavitation Trim
Dear Mr. Russell:
The purpose of this letter is to notify the NRC Staff of a defect with
the Residual Heat Removal Service Water (RHRSW) outlet valve MO 2-1001-
5B. This valve throttles the RHRSW system pressure and flow. An
identical valve is installed on the "A" loop (MO 2-1001-5A). Unit 1 does
not have this valve installed.
The nature of the defect is that Anchor Darling designed and manufactured
the valve with a combination of plug/trim clearance and plug eccentricity
that did not provide sufficient protection against galling and eventual
valve seizure.
It has been determined that this created a potential substantial safety
hazard because the simultaneous loss of this valve on both loops would
eliminate the ability of RHR containment cooling modes and shutdown
cooling mode to perform their intended function.
Anchor Darling proposed corrective action was to send guidance to
increase the clearance between the valve plug and the trim to
approximately 0.018 inches and make the stem/plug true. This has been
accomplished for the original "B" loop valve. As an interim corrective
action Quad Cities will perform monthly testing of running loads on the
"A" loop valve until it is modified.
These control valves used custom trim designed for this particular
application, thus, Quad Cities Unit 2 is the only plant affected by this
problem.
A Unicom Company
ESK-95-223
December 21, 1995
Page 2
Provided as an attachment to this letter is ComEd's notification in
accordance with the requirements of 10CFR Part 21, Section 21.1(b),
21.3a(3), and 21.3d(4).
If there are any questions regarding this notification, please direct
them to Steve Killian at (309) 654-2241 extension 2613.
Respectfully,
Edward S. Kraft, Jr.
Site Vice President
Quad Cities Station
Attachment: 10CFR Part 21 Final Report
cc: H. J. Martin, Regional Administrator - R III,
C. G. Miller, Senior Resident Inspector - Quad Cities
R.A. Capra, Directorate HI-2 Director, NRR
R. M. Pulsifer, Quad Cities Project Manager, NRR
Office of Nuclear Facility Safety - IDNS
Commonwealth Edison Company EXHIBIT A
Nuclear Operations Division NEP-10-02
Revision 0
1 of 2
10CFR PART 21 EVALUATION CHECKLIST
10CFR Part 21 Notification
Binding of Anchor Darling Valves with Cavitation Trim
Quad Cities Station
Part 21 File # 9515
Applicability
This notification is submitted in accordance with the requirements of
10CFR Part 21, Section 21.1(b), 21.3a(3), and 21.3d(4).
Identification of Facility and Component
This notification concerns the binding of the Residual Heat Removal
Service Water (RHRSW) outlet valve MO 2-1001-5B at Quad Cities Station,
Unit 2. The valve is a 12 inch 300 lb. welded end carbon steel globe
valve with anti-cavitation trim and an SMB-0 Limitorque Actuator. The
valve throttles the RHRSW system pressure and flow. It is the outlet
valve from the 2B RHR Heat Exchanger. An identical valve is also
installed on the A loop (MO 2-1001-5A). The valve is not installed on
Unit 1.
High Pressure Coolant Injection (HPCI) valves MO 1(2)-2301-10 are of
similar design.
These control valves used custom trim designed for this particular
application. The defect would apply only to valves of similar plug size
and trim package. Other ComEd plants do not have these valves.
Identification of Component Manufacturer
Anchor Darling Valve Company
701 1st Street
Williamsport, PA. 17701
Nature of Defect
This valve locked up at the 60% open position during a surveillance.
When the valve was subsequently disassembled, severe galling between the
valve plug and the valve trim was observed. The engineering drawings for
this valve specify a clearance of 0.004 to 0.007 inches between the plug
and the trim. Anchor/Darling admits that the specification for the
clearance is too small and that a more appropriate clearance would be
0.010 to 0.018 inches. In addition, runout (eccentricity) of 0.006
inches was measured on the valve plug. The center line of the plug was
offset by 0.006 inches from the center line of the stem. Stem runout was
measured to be insignificant, less than 0.0005 inches. Similar valve
plug/stem/trim clearance and eccentricity were also measured on the two
spare Anchor/Darling valves that are scheduled to be installed in Unit 1
during Q1R14. The galling had probably initiated during the previous
event on this valve when the anti-rotation device slipped on the valve
shaft and became cocked, locking up the stem. The lateral loads applied
to the stem allowed galling to start since the clearance between the
valve plug and trim was minimal. Once galling had initiated, each stroke
of the valve increased the friction between the valve
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Commonwealth Edison Company EXHIBIT A
Nuclear Operations Division NEP-10-02
Revision 0
1 of 2
10CFR PART 21 EVALUATION CHECKLIST
plug and trim.
The nature of the defect is that Anchor Darling designed and manufactured
the valve with a combination of plug/trim clearance and plug eccentricity
that did not provide sufficient protection against galling and eventual
valve seizure.
Safety Significance
Simultaneous loss of this valve on both loops would eliminate the
capability of RHR containment cooling modes and shutdown cooling mode to
perform their function.
At the time of discovery, Unit 2 was shut down and Containment Cooling
was not required to be operable. Redundancy in the Shutdown Cooling mode
was provided by valve MO 2-1001-5A. Although this valve also has the
same defect, testing has revealed no sign of the onset of galling in this
valve. In addition, several alternate methods of decay heat removal were
available, including the Reactor Water Cleanup System (RWCU).
Time of Discovery
On August 28, 1995, with Unit 2 in cold shutdown, and while performing
QCOS 1000-4, valve MO 2-1001-5B stuck at approximately 60% open. The NSO
was unable to open or close the valve from that position. An RHRSW Pump
was started in an attempt to flush any possible debris that may have been
caught internally in the valve. The NSO was still unable to throttle the
position of MO 2-1001-5B. The discharge pressure and flow in the B Loop
of RHRSW was therefore unable to be adjusted. The NSO then shutdown the
RHRSW pump. With no RHRSW pumps running, RHRSW system logic sends a
CLOSE signal to MO 2-1001-5B. The valve still would not move. The 2B
Loop of Containment Cooling was declared inoperable. It was determined
that a defect existed per the requirements of 10CFR21 on November 14,
1995 and the vendor was contacted to make the Part 21 notification. On
the week of December 11, 1995, the vendor informed the station that it
was not going to make a Part 21 notification. Thus the station is making
the Part 21 notification.
Corrective Actions
Guidance was received from Anchor/Darling to increase the clearance
between the valve plug and the trim to approximately 0.018 inches and to
make the stem/plug true. This was done by machining the plug from a
spare valve that was scheduled to be installed in Unit 1 during Q1R14.
The new stem, plug, upper trim, lower trim, valve yoke, and bonnet from
the spare valve was installed in valve MO 2-1001-5B. The valve was
successfully VOTES tested on September 1, 1995. No excessive running
loads were observed.
To address MO 2-1001-5A, since it has the same clearance/runout as MO 2-
1001-5B originally had, a "Packing N-Forcer" test was performed on both
MO 2-1001-5A and 5B. This VOTES type equipment is much more sensitive at
measuring running loads and would be capable of detecting rubbing that
could lead to galling. Similar traces were received on both MO 2-1001-5A
and 5B. The "Packing N-Forcer" test will be run on MO 2-1001-5A on a
monthly basis to determine if galling is starting on this valve. The
"Packing N-
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Commonwealth Edison Company EXHIBIT A
Nuclear Operations Division NEP-10-02
Revision 0
1 of 2
10CFR PART 21 EVALUATION CHECKLIST
Forcer" test was repeated on September 28 with the same running loads
observed. This testing will continue monthly until the modified plug is
installed on this valve.
Valves of similar design and original clearance specifications are also
installed in valves MO 1(2)-2301-10 on the High Pressure Coolant
Injection (HPCI) system. These valves were installed approximately four
years ago and no problems have been observed. These valves are different
from the RHRSW valves in several significant respects. The plug on the
HPCI valves has nickel-chrome hardfacing, which makes them less
susceptible to galling. The HPCI valves are 900 lb. valves with smaller
diameter plugs, i.e. 4.6 in. as compared to 6.6 in. for the RHRSW valves.
Therefore the specified clearances for the HPCI valves are effectively
larger than for the RHRSW valves. Finally, the HPCI system is a
condensate grade water system. It has been concluded that the HPCI
valves are adequate and that no changes are needed to their design.
The remaining portions of the spare valves that are scheduled to be
installed in Unit 1 will be sent to Anchor/Darling for refurbishment and
machining for the proper clearances. Anchor/Darling has committed to
correct and return both valves on-site prior to Q1R14.
Number and Location of All Defective Components
These valves were custom designed for the Quad Cities Station and
therefore affect no other plants.
Commonwealth Edison Company EXHIBIT A
Nuclear Operations Division NEP-10-02
Revision 0
1 of 2
10CFR PART 21 EVALUATION CHECKLIST
Contacts
Questions pertaining to this notification should be addressed to:
Stephen D. Killian
Quad Cities Nuclear Power Station
ComEd
22710 206th Ave. North
Cordova, IL. 61242
(309) 654-2241 x2613
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