ML20090B064
| ML20090B064 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/28/1992 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-PT21-92 PT21R-92-001, PT21R-92-1, TXX-92087, NUDOCS 9203030180 | |
| Download: ML20090B064 (6) | |
Text
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Log
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TU!!! ECTRIC february 28. 1992
)
William J. CaMil. Jr.
i Omr hva hw.ker U. 5. flucl.,ar Regul at ory Commi ssion A t t ti:
D'scument Control Dest Wa s hi rat on, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCLET NOS. 50-445 AND 50-440 SWING ARHS FOR BORG WARfiER CHECL VALVES 10CrR21 RLPORT P21R 92-001 REF:
1) f acsimile t ransmission and t elephone conversation between NRC Operations Center and TV Electric on January 14, 1992.
Gentlemen:
The NRC was notified of a reportable condition regarding a difierence between installed and replacement swing arms for borg Warner checf valves by reference 1.
A request for an extension to february 28, 1992, for submittal of the final report to allow additional evaluation on the subject issue was granted by Mr. L.
A. Yandell of NRC Region IV, Attached is the written report which satisfies the reporting requirements of 10CFR21.
The report has been formatted it' a manner that corresponds to the specific information requested by subparts (1) through (viii) of paragraph
- 21. 21 ( c )( 4 ) of the regulation.
This is exclusive of that portion of subpart (vi) regarding names and locations of other facilities which may be af fected, as this inf ormation is not known to 10 Electric, and subpart (viii) in its entirety regarding the advice that has been or will be given to other facilities.
Such advice wuuld be dependent on the facility specific use and operating / maintenance history of the subject components.
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4 TXX 92087 Page 2 of 2 A copy of this report will tie sent to BW/IP Inc.
4 05L,y &AH>>.
William J. Cahill, Jr.
i 4
By:
Roger 1 Walter Manager of Huclear Licensing 08/tg c - Mr. R. D. Hartin, Region IV Mr. L. A, Yandell Region IV Hr. T. A. Bergmen. NRR Mr. M. B. Fields, NRR BW/IP inc.
Resident inspectors, CPSES (2)
v Attachment to TXX*92087 Page 1 of 4 10CfR21 REPORTABLE CONDITION INVOLVING SWING ARMS FOR BORG WARNER CHECK VALVES (i)
Information supplied by:
William J. Cahill. Jr.
TU Liectric 400 North Olive Street. L. B. 81 Dallas, Texas 75201 (ii)
The facility is Comanche Peak Steam Electric Statich Units 1 and 2.
The-basic components are. swing arms on.Borg Warner check valves model number 75510 which are not completely interchangeable with the original parts.
(iii)- The swing arms stated in (ii) above were qualified and supplied to
'TU Electric by BW/IP Inc. previously known as Borg Warner / industrial Product, Inc.
-(iv)
Description The swing arm-is a machined steel casting attached via clevis and pivot pin to the valve bonnet (see sketch on page 4).
The bonnet provides a mounting point for the clevis.
The valve disc is attached to-the swing-arm vis a disc stud and a disc nut.
A ball bushing is located at the point'where the disc stud passes-through the swing arm.
The check valve is in the open or closed position depending on direction of flow through the valve body. When fully open, the arc of the swing arm and disc assembly is limited by contact between the-disc stud and a stop block mounted on the valve bonnet.
The disc is maintained in the open position when flow is in the required direction..-The disc is activated to the closed. position when flow is in the other than the required direction. The swing arm is part number 72543 on BW/IP valve model' number-75510.
This valve is a 3'
900# swing check valve.
Site SDecific SummLr_y, On November 10, 1991 during outage related inspection activities the internals of a 3'
- 900#-BW/IP swing check valve were removed and the old swing arm was replaced with the_new swing arm as part of a valve upgrade.
i-l l
Attachiaent to 1XX 90007 rage 2 of A An engineering evaluation prior to reinstallation of the reworked bonnet assembly with the new swing arm revealed several concerns 4
regarding the 9perability of the check valve with the nes swing arm installed, When the new swing arm is in the up position:
a)
An increase in the maximum are length of the disc stud increases the possibility of contact with the valve neck which coul
- possibly contribute to valve hang up or valve
- damage, a
b)
The disc may impact the swing arm which could lead to valve damage, and c)
The disc stud makes contact closer to the far edge of the stop block resulting in a possible hang up location, i
TV Clectric had previously performed the following modifications to tha valves which may have contributed to the observed problems:
a)
A modification was made in 1983 to replace tack welds which n
hold the disc stud to the disc with a f ull fillet weid, This modification was made because of the potential for volve_ internals to come opnrt during operation, at.d as a result of a recommendation by BW/lp inc.
b)
The ball bushings were modified, as specified by UW/IP Inc, to compensate for the fillet weld size and/or the axial clearance, c)
The 3/8 inch by 5/8 inch stepped disc stud was replaced, in Unit 1 only, with a 5/8 inch stud, Based on the above, TV Electric has concluded' that the replacement swing arms supplied and certified as lif e for like
-items, i.e.,
fit, form and function, are not interchangeable with the original swing arms in the valves modified by TV Electric, Use of the revised part as interchangeable with the original could~ provide a potential for failure of the valve to close, e.g., lodging open when the disc assembly is forced into an avverse configuration, Backleakage through the valve could lead to degradation or inoperability of associated safety related equipmentLor_ systems.
This condition is considered a defect 1
._ _ _ _ _ _ _ _ _ q l
Attachment to TXX 9T087 Page 3 of 4 J
11,f,g l egific imniic @ ni i
The auxiliary feedwater system was not in service when this def ect l
was discovered, The 3*
900ll class pressurwseal bonnet BW/IP checi valve swing arm design is a unique design unlike that in an other i
sizes or pressure classes of BW/IP check valves installed at CPSES.
This specific site / class of valve was only used in the Auxiliary l
Fredwater Pump miniflow recirculation lines downstream of the associated breakdown orifice.
There are three such valves per unit.
.[
The miniflow lines f rom all three pumps are connected by a common return line to the Condensate Storage Tank.
The consequences of a postulated bac6 flow incident involving any one of these chec6 valves would be-substantially mitigated by the flow restriction from the breakdown orifice.
The design basis of the systeni also assumes a single active f ailure which would encompass any one of these valves failing to close for any reason.
A TV Clectric-engineering report prepared in 1989 considered the potential for a common mode f ailure to-close of multiple check valves and determined that, for the subject 3' valves, there was no safety significance.
Therefore, if the bonnet assembly containing the new swing arm had been installed, and if the valve did fail to close, no safety significant consequences would have resulted.
However, no restriction had been placed on using the subject valves in other safety related applications.
Consequently.
even though the specific application did not result in a significant adverse condition, the potential 'or such condition did exist.
(v)
Information of the defect was obtained from the TV Electric evaluation which conc 1hded on January 14 1992. that'the deficiency was a defect.
i t
lvi )
As discussed in (vi) above TV Electric has a total of six (6) 3* - 900l/ class pressure seal bonnet BW/IP check valves.
I (vii) TV Clectric reinstalled the old swing arm.
A successful backflow test was performed on the subject valve.
TV Electric is evaluating the need to modify the valve to facilitate use of the replacement arms supplied by BW/IP Inc. in order to assure acceptable operation.
-(viii) Not applicable.
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it s
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Bonnet e
k 5
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3 Stop Block i
a)
Clevis i,
Swing Arm-I
-l7h' Di 6N xf-sc Stud i
Pivot Pin g
/l/,
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Disc Nut S
Y Ball Bushing 6
interfaces a) Disc stud to valve neck b) Disc to swing arm c) Disc stud to stop block BORG-WARNER CHECK VALVE INTERNALS
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