ML20211P927
| ML20211P927 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 05/14/1986 |
| From: | Nauman D SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-85-003, IEB-85-3, NUDOCS 8607230436 | |
| Download: ML20211P927 (18) | |
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May 14,1986 3)ba D
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Dr. J. Nelson Grace Regional Administrator ii U.S. Nuclear Regulatory Commission Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323 l
Subject:
Virgil C. Summer Nucl. ear Station Docket No.50/395 83 Operating License No.:NPF-12 IE Bulletin 85-03," Motor Operated Valve Common Mode Failures During PlantTransients Due To improper Switch Settings" l
Dear Dr. Grace:
This report is provided in response to IE Bulletin #85-03, " Motor Operated Valve Common Mode Failures During Plant Transients Due To improper Switch Settings,"
(
dated November 15,1985. The Licensee has complied with the required action as follows:
' Attachment 1 represents the response to Action item e.(1).
- Attachment 2 represents the response to Action item e.(2).
If you have questions or comments after your review of the attached information, please contact us at your earliest convenience. The undersigned affirms that the statements and matters set forth in this letter are true and correct to the best of my knowledge,information, and belief.
ly ours, an MDB: DAN:tdh c: see page two 8607230436 860514
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Dr. J. Nelson Grace Page Two May 14,1986 c: J. A. Warren O. W. Dixon, Jr/T. C. Nichols, J r.
E. H. Crews, Jr.
E. C. Roberts D. A. Nauman J. G. Connelly, Jr.
W. A. Williams, Jr.
Group Managers O. S. Bradham D. R. Moore C. A. Price W. T. Frady(NSRC)
C. L. Ligon R. M. Campbell K. E. Nodland R. A..Stough G. O. Percival R. L. Prevatte J. B. Knotts, Jr.
l&E Washington Document Management Branch NPCF File
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Attachment I Page 1 cf 15 The selection of inotor operated valves for this program in both the Emergency Feedwater and the High Pressure Safety injection Systems is based upon the initial Design Basis Accident for short term cooling. These valves are presently tested for operational readirjess in accordance with 10CFR50.55 a(g).
Definitions Condensate Storage Tank CST Design Basis Accident DBA Differential Pressure AP Emergency Feedwater EFW gallons per minute gpm pounds per square inch - gage psig Reactor Coolant System RCS RHR Residual Heat Removal Refueling Water Storage Tank RWST Safety injection 51 SW Service Water Volume ControlTank VCT NOTE:
' Line loss and losses associated with flow path components are neglected in maximum differential pressure development. Thus, the maximum differential pressures calculated result in conservative values.
Pag? 2 cf 15 Valve Tag No':
XVG-8107,8108 CS Valve
Description:
Normal Charging Path isolation Valves Normal Position:
Open Valve Type:
3 Gate, Flexible wedge, Class 2A, Active
- 1) Valve Design Basis These valves are insta' ed in series in the normal charging path to the RCS. They are normally open and rr si be operated from the main control board with each valve having its own selector switch. The valves will fail in the "as is" position on loss of power.
Both valves will close on an 51 signal. The 8107 valve closes on A channel signal; the 8108 valve closes on B channel signal, and both will remain closed until the 51 signal clears. The 8107 valve is powered from A train bus and the 8108 valve is powered from B train bus.
The valves are paired to ensure isolation of the normal charging path. Since one valve's signal and power to close comes from one train and the other valve's signal and power to close comes from the other train, no single active electrical failure should compromise isolation of the normal charging path header. No other single active failures willimpact on these valves' maximum AP determination.
Line losses c nd losses associated with flow path components are negiected in maximum AP development. Also, the charging pumps are assumed to be at shut off head concurrent with lowest possible RCS back pressure, inadvertent closure by the operator will not result in a safety hazard. The plant can be safely shut down and maintained without these valves in service.
- 2) Design Conditions Valve Operation Max 6P/Temo Opening 2750 psig/650*F Closing 2750 psig/650 F
- 3) Operating Conditions Normal Operating Abnormal Operating Valve Operation Max AP/ Temp Max AP/ Temp Opening 100psig/130*F N/A Closing N/A 2200psig/130 F
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I Attachmenti I
Page 3 cf 15 I
l Valve Tag No:
XVG-8107,8108-C5
- 4) CurrentOperatorSwitch Settings Device in Circuit for Control Circuit Device in Circuit for Abno Device Normal Operation Ope at o Torque Switch No No Torque Switch No No Bypass No No-Opening) Limit Switch (1 Closing Limit Switch Yes Yes (2)
Overcurrent Device Yes No NOTES:
(1) Contact opens when valve reaches full open sosition.
(2) Contact opens when valve reaches full closec position.
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Attachmenti Pag 24 cf 15 Valve Tag No:
XVG-8801 A,B-SI Valve
Description:
High Head Safety injection isolation Valves Normal Position:
Closed Valve Type:
3" Gate, Flexible wedge, Class 2A, Active
- 1) Valve Desigo B. asis These valves are installed in parallel in the 51 path to the RCS and isolate the charging pumps discharge from the cold leg injection points of the RCS. Upon receipt of an 51 signal,these valves will open. The A valve is actuated and powered from the A train, and the B valve is actuated and powered from the B train. The valves may be operated from the main control board.
These valves are paired to ensure a high head injection path into the RCS. Since one valve's signal and power to open comes from one train and the other valve's signal and power to open comes from the other train, no single active electrical failure should com promise the high head injection path. No other single active failure will impact on these valves' maximum AP determination.
1 1.ine losses and losses associated with flow path components are neglected in maximum AP determination. Also,the charging pumps are assumed to be at shutoff head concurrent with lowest possible RCS system back pressure. Other motor operated valves (XVG-8132 A,B-C5 and XVG-8133 A,B-CS) could be operated but would tend to reduce AP since the charging pump would then become isolated from the 8801 valves. In addition, the active check valves downstream of the 8801 valves could fail to open which would tend to reduce maximum AP.
Inadvertent opening by the operator will not result in a safety hazard; the plant can be safely shut down. The valves should close since the closure loads will be much less than the opening loads.
- 2) Design Conditions Valve Operation Max AP/ Temp Opening 2750 psig/650 F Closing 2750 psig/650 F
- 3) Operating Conditions Normal Operating Abnormal Operating Valve Operation Max AP/ Temp Max AP/ Temp l
Opening N/A 2200psig/130 F Closing N/A N/A
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Attachmenti Pcg2 5 cf 15' Valve Tag No:
XVG-8801 A,B-SI
- 4) Current Operator Switch Settings Device in Circuit for Control Circuit Device in Circuit for Abn Device Normal Operation Ope at o Torque Switch Yes Yes
~ Torque Switch Yes Yes Bypass (3)
Opening Limit Yes Yes Switch (1)
Closing Limit Switch No No (2)
Overcurrent Device Yes No NOTES:
(1) Contact opens when valve reaches full open sosition.
(2) Contact opens when valve reaches full closec position.
(3) Bypass contact remains closed to initiate valve travel, then opens to allow the torque switch to interrupt travel when full valve displacement is reached.
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AttachmentI Pag? 6 of 15 l
Valve Tag No:
LCV-115 B, D-C5 Valve
Description:
Refueling Water Storage Tank to Charging Pump Suction isolation Valves i
Normal Position:
Closed Valve Type:
8" Gate, Flexible Wedge, Class 2A, Active
- 1) Valve Design Basis These valves are installed in parallel flow paths to the suction of the charging pumps. They are normally closed and may be operated from the main control board with each valve having its own switch. These valves will fail "as is" on loss of power and are interlocked to open on a low-low VCT level and also on an 51 signal. LCV-115 B is actuated and powered from the A train, and LCV-115 D is actuated and powered from the B train.
These valves are paired to ensure a suction path to the charging pumps from the i
RWST. Since one valve's signal and power to open comes from one train and the other valve's signal and power to open comes from the other train, no single active electrical failure should compromise their function to align the charging pump suction to the RWST.
The valve XVT-8104-CS could be inadvertently opened during the 51 phase when LCV 115 B, D-CS must open. This could subject the charging pump header to 100 psig pressure if the charging pumps were not operating. Since, for Si conditions, the charging pumps would be at runout and the flow rate is 650 gpm, the Boric Acid Transfer pumps delivery at 75 gpm would run these pumps out on the operating curve where 100 psig pressure would no longer be available. The Boric Acid Transfer pumps would fail and be of no consequence for addition of AP to LCV-115 B,D-CS. The valves XVG-8706 A, B-RH could be inadvertently opened, but the suction of the charging pumps would be still be aligned to the RWST via the RHR pumps, which are also taking suction from the RWST. The 8706 valves are designed to be opened during the recirculation phase following the 51 phase of the DB A. The AP across valves LCV-115 B,D-CS in this case would be 100 psig or greater depending on the time at which one looks at the accident since the RWST level will be dropping due to the removal of water.
Therefore, there is no other single active failure that would impact on the maximum AP for valves LCV-115 B,D-CS. Several inadvertent valve actuations could impact but are of either very short duration or of no consequence. Inadvertent opening of valves LCV-115 B,D-CS by the operator will not result in a safety hazard; the plant can be safely shut down and maintained shutdown without these valves in service.
- 2) Design Conditions Valve Operation Max AP/ Temp Opening 200 psig/250 F Closing 200 psig/250'F 9
Attachm:nt I P g2 7 cf 15
=
1 Valve Tag No:
LCV-115 B, D-CS
- 3) Operating Conditions Operating Conditions Normal Operating Abnormal Operating Valve Operation Max APRemp Max APRemp Opening N/A 33 psig/130 F Closing N/A N/A
- 4) Current Operator Switch Settings Device in Circuit for Control Circuit Device in Circuit for
^bn Device Normal Operation Ope at o Torque Switch Yes Yes Torque Switch Yes Yes Bypass (3)
Opening Limit Yes Yes Switch (1) l Closing Limit Switch No No I
(2)
Overcurrent Device Yes No NOTES:
)
(1) Contact opens when valve reaches full open sosition.
(2) Contact opens when valve reaches full closec position.
(3) Bypass contact remains closed to initiate valve travel, then opens to allow the torque switch to interrupt travel when full valve displacement is reached.
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AttachmentI Page 8 cf 15 Valve Tag No:
LCV-115 C, E-CS Valve
Description:
Volume Control Tank isolation Valves Normal Position!
Open Valve Type:
4 Gate, Flexible wedge, Class 2A, Active
- 1) Valve Design Basis These valves are installed in series in the suction line to the charging pumps from the VCT. They are normally open and may be operated from the main control board with each valve having its own switch. These valves will fail "as is" on loss of power and are interlocked to close on a low-low VCT level and also on an 51 signal. LCV-115 C is actuated and powered from the A train and LCV-115 E is actuated and powered from the B train.
These valves are paired in series to isolate the VCT from the suction of the charging pumps. The VCT s vapor gas space is protected by relief valve, XVR-8120-CS, which is of sufficient capacity to preclude overpressurization of the VCT.
Since one valve's signal and power to close comes from one train and the other valve's signal and power to close comes from the other train, no single active electrical failure should compromise their function to isolate the VCT from the suction of the charging pumps.
There is no other single active failure that would impact on the maximum AP for valves LCV-115 C, E. For reasons similar to the previous discussion of valves LCV-115 B, D, several inadvertent valve actuations could impact maximum AP but are of either very short duration or of no consec uence. Inadvertent closing of LCV-115 C, E by the operator will not result in a safety lazard; the plant can be safely shut down and maintained shutdown without these valves in service.
- 2) Design Conditions Valve Operation Max AP/Temo Opening 200 psig/250 F Closing 200 psig/250 F l
- 3) Operating Conditions Normal Operating Abnormal Operating Valve Operation Max AP/Temo Max AP/Temo Opening 60 psig/130 F N/A Closing N/A 96 psig/130 F
Attachment I Page 9ef 15 Valve Tag No; LCV-115 C, E-CS
- 4) Current Operator Switch Settings Device in Circuit for Control Circuit Device in Circuit for
- bno Device Normal Operation 0p9 at o Torque Switch Yes Yes Torque Switch Yes Yes Bypass (3)
No No
, Opening) Limit Switch (1 Closing Limit Switch No Yes (2)
No Overcurrent Device Yes i
NOTES:
(1) Contact opens when valve reaches full open sosition.
(2) Contact opens when valve reaches full closec position.
(3) Bypass contact remains closed to initiate valve travel, then opens to allow the torque switch to interrupt travel when full valve displacement is reached.
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Attachmenti Pag 210 cf 15 4
Valve Tag No:
XVG-1001 A, B-EF Valve
Description:
Isolation of A&B Train Service Water Supply to Electric Driven Emergency Feedwater Pumps XPP-21 A,21B-EF, respectively Normal Position:
Closed Valve Type:
6" Gate, Flexible wedge, Class 28, Active
~
- 1) Valve Design Basis These valves isolate the suction of the electric driven EFW pumps from the SW backup supply. These valves are installed to allow use of the SW system water should the normal safety grade water source for the EFW system be unavailable.
XVG-1001 A,B-EF are closed for all modes of plant operation. The valves fail "as is" in loss of power and may be actuated from the main control board. Valve XVG-1001 A is actuated and powered from A train and valve XVG-1001 B is actuated and powered from B train. Automatic actuation occurs on a 2 of 4 low pressure indication in the EFW suction header.
Inadvertent opening by the operator will not result in a plant safety hazard. It is possible that out of chemistry specification water could be introduced into the steam generator and/or the CST. This phenomenon could only occur if the backup supply valves from the SW system were opened and the CST suction header backflo.w prevention check valve leaks excessively. Valves XVG-1001 A, B can be reclosed from the main control board since AP's under these conditions are less than design conditions.
Both valves are installed to ensure a safety grade water source backup to the EFW system should the CST be lost to a natural phenomenon such as a tornado. There are no inadvertent valve closures in the SW or EFW system which would result in greater AP's across these valves; hence, there is no single active failure that would impact the maximum AP for the valves.
- 2) Design Conditions Valve Operation Max AP/ Temp Opening 150 psig/120 F Closing 150 psig/120 F
- 3) Operating Conditions Normal Operating Abnormal Operating Valve Operation Max AP/ Temp Max AP/ Temp Opening N/A 60 psig/95 F Closing N/A N/A 4
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Attachmenti Page 11 cf 15 Valve Tag No:
XVG-1001 A,B-EF
- 4) CurrentDperatorSwitch Settings l
Device in Circuit for Con ~tr61 Circuit Device in Circuit for j
A Operat n (3)
Device Normal Operation Torque Switch Yes Yes l
Torque Switch Yes Yes Bypass (4)
Yes Yes Opening) Limit Switch (1 Closing Limit Switch No No (2)
Overcurrent Device Yes No NOTES:
(1) Contact opens when valve reaches full open sosition.
(2) Contact opens when valve reaches full closec position.
(3) Valve opens automatically on low pressure signal from CST.
(4) Bypass contact remains closed to initiate valve travel, then opens to allow the torque switch to interrupt travel when full valve displacement is reached.
I
Attachm:ntI Page 12 of 15 Valve Tag No:
XVG-1002,1008 EF -
Valve
Description:
Isolation of A&B Train Service Water Supply to the Steam Driven Emergency Feedwater Pump, XPP 8-EF Normal Position:
Closed Valve Type:
8" Gate, Flexible wedge, Class 28, Active
- 1) Valve Design Basis These valves isolate the suction of the steam driven EFW pump from the SW backup supply. These valves are installed to allow use of the SW system water should the normal safety grade water source for the EFW system be unavailable.
XVG-1002,1008 are closed for all modes of plant operation. The valves fail "as is" on loss of power and may be actuated from the main control board. Valve XVG-1002 is actuated and powered from B train, and valve XVG-1008 is actuated and powered from Atrain. Automatic actuation occurs on a 2 of 4 low pressure indication in the EFW suction header.
Inadvertent opening by the operator will not result in a plant safety hazard. It is possible that out of chemistry specification water could be introduced into the steam generator and/or the CST. This phenomenon could only occur if the backup supply valves from the SW system were opened and the CST suction header backflow prevention check valve leaks excessively. Valves XVG-1002,1008 can be reclosed from the main control board since AP's under these conditions are less than design conditions.
Both valves are installed to ensure a safety grade water source backup to the EFW system should the CST be lost to a natural phenomenon such as a tornado. There are no inadvertent valve closures in the SW or EFW system which would result in greater AP's across these valves; hence, there is no single active failure that would impact the maximum AP for the valves.
- 2) Design Conditions Valve Operation Max AP/ Temp Opening 150 psig/120 F Closing 150 psig/120 F l
- 3) Operating Conditions Normal Operating Abnormal Operating Valve Operation Max AP/ Temp Max AP/Temo Opening N/A 60 psig/95 F Closing N/A N/A l
l
AttachmentI Pag 213 cf 15 Valve Tag No:
XVG-1002,1008-EF.
- 4) CurrentOperatorSwitch Settinas Device in Circuit for Control Circuit Device in Circuit for
^
Device Normal Operation Operat n (3)
Torque Switch Yes Yes Torque Switch Yes Yes Bypass (4)
Opening Limit Yes Yes Switch (1)
Closing Limit Switch No No (2)
Overcurrent Device Yes No NOTES:
(1) Contact opens when valve reaches full open sosition.
(2) Contact opens when valve reaches full closec position.
(3) Valve opens automatically on low pressure signal from CST.
(4) Bypass contact remains closed to initiate valve travel, then opens to allow the torque switch to interrupt travel when full valve displacement is reached.
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Page 14 cf 15 Valve Tag No:
XVG-1037 A, B EF Valve
Description:
Isolation of A&B Train Backup Supply from Service Water to Emergency Feedwater System Normal Position:
Closed Valve Type:
- - 8" Gate, Flexible wedge, Class 2B, Active
- 1) Valve Design Basis These valves supply water from a safety clrade system to the EFW suction header should the normal safety grade source or water for the EFW system be unavailable.
XVG-1037 A,B are closed for all modes of plant operation. The valves fail "as is" on loss of power and may be actuated from the main control board. Valve XVG-1037 A is actuated and powered from A train, and XVG-1037 B is actuated and powered from B train. Automatic actuation occurs on 2 of 4 low pressure indication in the EFW suction header.
Inadvertent opening by the operator will not result in a plant safety hazard. It is possible that out of chemistry specification water could be introduced into the steam generator and/or the CST. This phenomenon could only occur if the suction valves on each EFW pump are open and the CST suction header backflow prevention check valve leaks excessively. Forward feed to the steam generators is only possible.
if the EFW pumps are running. Valves XVG-1037 A,B can be reclosed from the main control board since AP's under these conditions are less than design conditions.
Both valves are installed to ensure a safety grade water source backup to the EFW system shculd the CST be lost to a natural phenomenon such as a tornado. There are no inadvertent valve closures in the SW or EFW system which would result in greater AP's across these valves; hence, there is no single active failure that would impact the maximum AP for the valves.
- 2) Design Conditions Valve Operation Max AP/ Temp Opening 150 psig/120 F Closing 150 psig/120 F
- 3) Operating Conditions Normal Operating Abnormal Operating Valve Operation Max AP/ Temp Max AP/ Temp Opening N/A 60 psig/95 F Closing N/A N/A
Attachmenti Pag 215 cf 15 Valve Tag No:
XVG-1037 A,B-EF
- 4) CurrentOperatorSwitch Settinos Control Circuit Device in Circuit for Device in, Circuit for A to Device Normal Operation Operat on (3)
Torque Switch Yes Yes-Torque Switch Yes Yes Bypass (4)
Openin Limit Yes
.Yes Switch
)
Closing Limit Switch No No (2)
Overcurrent Device Yes No NOTES:
(1) Contact opens when valve reaches full open sosition.
(2) Contact opens when valve reaches full closec position.
(3) Valve opens automatically on low pressure signal from CST.
(4) Bypass contact remains closed to initiate valve travel, then opens to allow the torque switch to interrupt travel when full valve displacement is reached.
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ATTACHMENT ll The followin '
ovides the program and schedule for the determination of motor
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operator swi c settings,in-situ valve testinc, and the review of procedures to verify that correct switch settings are maintained t 1roughout the life of the plant.
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Item B Correct switch settings coincident with stem thrust values shall be verified through valve and/or operator manufacturers.
Item C Switch settings shall be changed as appropriate in accordance with the results obtained for item B. Valves shall be demonstrated operable by either stroke testing at full differential pressures or justification will be provided where testing at full AP's cannot be practically performed. The justification provided willinclude the alternative to full AP testing to verify the correct switch settings.
Item D SCE&G has current plant procedures in effect for documenting operator switch parameters. These procedures shall be reviewed for adequacy and appropriate revisions shall be instituted if required.
Schedule for items B, C, D The schedule for the completion of the activities provided in this Attachment is currently under detailed review. A schedule will be provided when the evaluation of the various valve operability demonstration methods has been completed.
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