United States Nuclear Regulatory Commission - Protecting People and the Environment


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-



                                 page 15                   g:\10-02_0.wpf



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



*** END OF DOCUMENT ***



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