ML20236Y088
| ML20236Y088 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 08/07/1998 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9808110163 | |
| Download: ML20236Y088 (20) | |
Text
,Daye Morey South:rn Nuclear g
- Mce President Op: rating Company b .. Farley Preject . P.O. Box 1295 Birrningham. Alabama 35201 Tel 205.992.5131 August 7, 1998 SOUTHERN h COMPANY Energy to Serve YourWorld" Docket Nos.: 50-348 10 CFR 50.55a 50-364 U. S. Nuclear Regulatory Commission ATTN.: Document Control Desk Washington, DC 20555 Joseph M. Farley Nuclear Plant inservice Testing (IST) Program j Response to NRC Questions / Comments on IST Relief Requests j Submitted as Part of the 10 Year IST Uodate Ladies and Gentlemen:
l On July 3,1997, Southern Nuclear Company (SNC) submitted updated JST programs for Joseph M. Farley Nuclear Plant (FNP) Units 1 and 2, in accordance with the requirements of 10CFR50.55a(f)(4)(ii). The updated programs contained pump and valve inservice test relief requests which SNC submitted for approval. The NRC and SNC have discussed these relief request on several dates including November 18,1997. December 17,1997 and April 28,1998.
SNC responded to NRC questions and comments raised during the November 18, and December 17,1997 phone calls by letter dated January 22,1998. [SNC submitted additional relief requests i by letter dated April 6,1998.]
Additional NRC questions and comments were received during the April 28,1998 phone call. ,
These additional questions and comments are summarized below and are addressed in Enclosure 1. l SNC relief request Q1(2)P16-RR-V-4 sought to establish a valve group consisting of Units 1 and 2 l check valves V564 and V565 (diesel generator service water outlet check valves) for a sample - )'
disassembly and inspection plan. The NRC indicated that an SER dated April 1,1991 denied the grouping of these check valves for the previous 10 year interval because the valve service conditions were different not meeting the requirements of GL 89-04 Staff Position 2. Additional
. justification for the relief was requested. In addition, the NRC indicated that additional - i justification relative to service conditions would be necessary for relief request Q1(2)P16-RR-V-3 l to allow the grouping of Units I and 2 check valves V659, V660 and V661 (diesel ge,crator g i service water inlet check valves). \ !
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U. S. Nuclear Regulatory Commission Page 2 The SNC request for a sampling plan for the valves addressed by Q1(2)P16-RR-V-3 and RR-V-4 has been supplemented with additionaljustification based on consideration ofincreased risk to the core. This additionaljustification has been added to the subject relief requests in Enclosures 2 and
- 3. The sampling plan addressed by Q1(2)P16-RR-V-3 has also been resised due to risk considerations.
SNC has determined that a gross leakage test can be performed to determine reverse flow closure for Units I and 2 check valves V206A, B, C, D (service water to containment cooler check valves).
Therefore, relief request Q1(2)P16-RR-V-2, is withdrawn.
It is the SNC staff understanding that all of the NRC concerns have been addressed by this and previous conununications and that there are no other outstanding issues which need to be resolved prior to NRC final approval of the 10 year updated IST relief requests.
Should you have any questions please contact this office.
Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY N
Dave Morey AJP:maf/ ISTRR. doc Enclosures cc. Mr. L. A. Reyes, Region II Administrator Mr. J. I. Zinunerman, NRR Project Manager Mr. T. M. Ross, Plant Sr. Resident Inspector i
, e' 4 g ENCLOSURE 1 NRC OUESTIONS/ COMMENTS - SNC RESPONSES BY RELIEF REOUEST l
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Relief Reauest OH2)P16-RR-V-4 The NRC indicated that an SER dated April 1,1991 denied the grouping of check valves V564 and V565 (diesel generator outlet check valves) as currently requested by relief request Q1(2)P16-RR-V-4 for purposes of sampling disassembly and inspection. The stated reason being that the valve service conditions were considered to be significantly different such that the requirements of Generic Letter 89-04, Staff Position 2 were not satisfid.
SNC Response o Generic Letter 89-04, Staff Position 2 requirements for valve grouping include valves that are the same design (manufacturer, size, model number, and materials of construction) and have the same service conditions including valve orientation. " Service conditions" is understood to mean valves in the same system, with the same process fluid, temperature and pressure. Reasonable variations in flow through otherwise identical valves would not be considered significant in this definition especially when backed up with a strong history of satisfactory disassembles and inspections. The disassembly and inspection history for the subject valves shows no unsatisfactory conditions for i either of these valves in either unit.
The diesel generator SW system design and use does n6t support the concern of significantly different service conditions for these valves as discussed below.
Section 3.11.3,1.2 of the TER states:
"The licensee has grouped these valves in a sampling program for disassembly and inspection. These valves serve components in two different units and one valve passes cooling flow for three diesel generators, therefore, their service conditions are not the same l as required for grouping by Generic Letter 89-04, Attachment 1, Item 2. Further, failure of cne of these valves in the closed position has a considerable safety significance because l
.. it could disable up to three diesel generators. Therefore, the use ofa sample programfor
, these valves is not considered to be appropriate."
- The reasons cited by the NRC for the valve grouping being " inappropriate" are summarized as
- 1) The valves have different service conditions as follows:
a) he valves serve components in different units b) - One valve serves 3 diesel generators, one valve serves 2 diesel generators c) The flow rates through the valves are significantly different (stated by the NRC reviewer)
- 2) Valves have different safety significance because failure of one valve (V564) can disable 3 diesel generators El-1
Each of these concerns is addressed below:
Concern In: Valves serve components in different units.
It should be noted that the NUREG guidance on valve grouping allows grouping of components from different units. Since all of the shared diesel generators have redundant service water supply and return valves, the failure of any one check valve to open will not cause the loss of diesel generator power supplying both units. Therefore the fact that these valves supply shared diesel generators is not considered to be significant from a safety standpoint.
Concern Ib: One valve serves 3 eenerators. one valve serves 2 eenerators.
The table below illustrates which valves supply each diesel generator. Each check valve serves only two generators and therefore, this is not a significant concern.
Diesel Generator Number and Service Water Cooling Flow Rate in GPM(1) 2C IB 2B IC 1-2A Total Flow Valve Shared Unit 1 Unit 2 Shared Shared Through Number Valve, GPM Station Blackout B Train B Train A Train A Train UI V564 488 1458 - - -
1946 UI V565 - - -
522 817 1339 U2 V564 488 -
1319 - - 1807 U2 V565 - - - 522 817 1339 (1) Assumes total flow through shared generators is supplied equally from each unit l
Concern le: Significant flow differences between valves.
The table above shows that for Unit 1, normal total flow through V564 is 1946 gpm .apared to 1339 gpm for V565. This difference is seen to be inconsequential in terms of the potential for valve degradation since these flows are well below the calculated 6600 gpm flow required to fully open these valves. The excellent disassembly and inspection history of these valves supports the conclusion that this de Mrf diffese in flowrates is not significant from a valve degradation potential standpoint.
Concern 2: Valves have different safety significance because failure of one valve can disable 3 1 eencrators.
As explained above, this valve only serves two generators. Additionally, failure of a check valve to open will not cause a loss of SW to a DG since the opposite unit redundant valve will allow full design flow.
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Summary:
Considering the design of the system, the redundant service water supply and return valves and the excellent disassembly and inspection history of these valves, the grouping of each unit's V564 and V565 valves for the purposes of a sample disassembly and inspection plan should be considered appropriate.
Relief Reauest Action: No change to the relief request is required relative to the specific NRC comments but as stated in the cozer letter, this relief request has been supplemented with additional justification for the sampling disassembly and inspection plan based on maintenance rub considerations ofincreased risk to the core versus preventative maintenance activities.
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. Relief Reauest 01(2)P16-RR-V-3 The NRC indicated that the same concerns expressed above for Relief Request Q1(2)P16-RR-V-4 also applied to the Unit I and 2 diesel generator service water inlet check valves i 059, V660 and V661 under Relief Request Q1(2)P16-RR-V-3.
SNC Response Generic Letter 89-04, Staff Position 2 requirements for valve grouping include valves that are the same design (manufacturer, size, model number, and materials of construction) and have the same service conditions including valve orientation. " Service conditions"is understood to mean valves in the same system, with the same process fluid, temperature and pressure. Reasonable variations in flow through otherwise identical valves would not be considered significant especially when backed up with a strong history of satisfactory disassembles and inspections. The disassembly and inspection history for the subject valves shows no unsatisfactory conditions for any of these valves in either unit.
The diesel generator SW system design and use does not support the concern of significantly different service conditions for these valves as discussed below.
The table below illustrates that all of the valves serve generators shared between Units 1 and 2, have flowrates which can be considered similar in terms of the valve degradation potential and each valve has a redundant counterpart in the other unit which prevents a failure of any one valve to disable any generator. The excellent disassembly and inspection history of the<e valves support the conclusion that any differences in the valve service conditions are not affecting ulve performance and should not be a factor in preventing the grouping of each unit's V659, V660 and V661 check valves for the purpose of a sample disassembly and inspection plan. The difference in flow between V661 and the other two valves is further minimized in terms of degradation potential because the V661 valve is 8" whereas the other two valves are 6". This size difference is noted in the relief request.
Diesel Generator Number and Service Water Cooling Flow Rate in GPM (1) 2C IB 2B IC 1-2A Total Flow Valve Shared Unit 1 Unit 2 Shared Shared Through Number Valve, GPM Station ;
Blackout B Train B Train A Train A Train i UI V659 488 - - - - 488 UI V660 - - - 522 - 522 ;
UI V661 - - - - 817 817 j U2 V659 488 - - - - 488 U2 V660 -- - - 522 - 522 U2 V661 - - - - 817 817 (1) Assumes total flow through shared generators is supplied equally from each unit.
Relief Reauest Action: No change to the relief request is required relative to the specific NRC comments but as stated in the cover letter, this relief request has been supplemented with additional justification for the sampling disassembly and inspection plan based on maintenance rule considerations ofincreased risk to the core verses preventative maintenance actisities.
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Relief Reauest OH2)P16-RR-V-2 The NRC questioned if a gross leakage test could be performed to determine by employing reverse flow closure for each unit's V206A, B, C, D check valves (service water to containment cooler check valves) instead of performing a sample disassembly and inspection plan.
SNC Response A gross leakage test can be performed on these valves. Since the valves are inside containment the leakage test can only be performed at refueling outages. The OM code allows deferring such tests until refueling outages without relief therefore the relief request for each unit is not needed. The basis for the deferral will be documented in the IST program.
Relief Recesst Action:
Relief Request Q1(2)P16-RR-V-2 is hereby withdrawn.
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ENCLOSURE 2 UNIT 1 REVISED RELIEF REOUESTS l
I RELIEF REQUEST Q1 P16-RR-V-2 1
This relief request has been withdrawn.
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o l RELIEF REQUEST l QlP16-RR V-3 l
Valve: QV659, QV660, QV661
_ Dr wing / Coo d: 170119 Sht. 3/C-3, C-8, C-10 System: Service Water (P16)
Category: C Class: 3 Function: Unit 1 Service Water Supply To DG 2C,1C,1-2A.
- OM Code Test - Disassemble each check valve every refueling outage in accordance with ISTC Requirements: 4.5.4(c).
Basis for There are no system design provisions to verify valve reverse flow closure quarterly, Relief: at cold shutdown or refueling outage. Therefore, per ISTC 4.5.4(c) these valves will be disassembled during refueling outages to verify operability. No reliefis required for the above per OM ISTC 4.5.4(c) if each valve is disassembled every refueling outage.
These valves are the same design (manufacturer, size (with exception stated below),
model number and material of construction) and have the same sersice conditions including valve orientation, thus they meet the guidance of NRC Generic Letter 89-04, Position 2 for ' valve grouping for purposes of ~ implementing a disassembly / inspection sampling plan. Valve QV661 is an 8 inch valve while the remaining valves in the group are 6 inch. Since these valves are identical in all other respects and are installed in the same system, the size difference is inconsequential.
The burden justification for the proposed attemate testing sampling plan is detailed below.
The inspection. history of these valves suggests there is no need for disassembly / inspection of all three valves each outage, thus any additional expense in doing so would be an unnecessary burden. The past nineteen inspections of these valves (total both units) dating back to 1984 have not detected any unsatisfactory conditions, On average, the disassembly / inspection of these valves requires 6 man-hours. Additional costs associated with' planning, scheduling, supervision, documentation, etc. are also required for this task.
. Without a sampling disassembly and inspection plan, FNP will be required to remove each train of diesel power each outage. This will cause the unavailability of the diesel train and hence the risk to the core to be twice that which would be required with grouping. In light of the good inspection history of these valves, FNP will be increasing risk to the core without a commensurate gain in the reliability of the valves. This is counter to the philosophy of 10CFR50.65 of balancing reliability and availability which states that " Adjustments shall be made where tweessary to ensure g that the objective of preventing failures of structures, systems and components through maintenance is appropriately balanced against the objective of minimizing unavailability of structures, systems and components due to monitoring or preventive maintenance."
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. . i Alternate Testing: h alternate testing described below is based on GL 89-04 guidance for valve grouping and check valve disassembly.
The valves will be disassembled and manually full stroke exercised each refueling outage on a staggered train related basis. Valves V660 and V661 will be inspected l together every other outage and V659 will be inspected on the alternating outages.
The valve internals will be verified to be structurally sound (no loose or corroded parts) and the disk will be manually exercised to verify full stroke capability. Ifthe
- disassembled valve is not capable of being full stroke exercised or there is binding or i
- failure of valve internals, the remaining valves in the group will also be disassembled, l
inspected and manually full stroke exercised during the same outage. The valve will l be part stroked with flow after reassembly. He necessary valve operator movement, 1 verifying part stroke exercising, will be confirmed by changes in system pressure, l flow rate, level, temperature, seat leakage testing or other positive means or through ]
the use of ultrasonic (or similar) flow measuring devices.
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RELIEF REQUEST Q1P16-RR-V-4 Valve: QV564, QV565 Other Valve No: NA Drawing /Coord: D-170119 Sht.3/G-2 System: Service Water (P16)
Category: C Class: 3 Function: Unit 1 Diesel Generator Service Water Train Return Check Valves OM Code Test Disassemble each check valve every refueling outage in accordance with ISTC 4.5.4(c).
Requirements:
Basis for Here are no system design provisions to verify valve full forward flow qu: rterly, at Relief: cold shutdown or refueling outage. Therefore, per ISTC 4.5.4(c) these valves will be disassembled during refueling outages to verify operability No reliefis required for the above per OM ISTC 4.5.4(c) if each valve is disassembled every refueling outage.
These valves are the same design (manufacturer, size, model number and material of construction) and have the same service conditions including valve orientation, thus .
they meet the guidance of NRC Generic Letter 89-04, Position 2 for valve grouping for purposes ofimplementing a disassembly / inspection sampling plan. The burden justification for the proposed alternate testing sampling plan is detailed below. 1
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The inspection history of these valves suggests there is no need for disassembly / inspection of both valves each outage, thus any additional expense in doing so would be an unnecessary burden. The past twelve inspections of these valves (total both units) dating back to 1989 have not detected any unsatisfactory conditions. On average, the disassembly / inspection of these valves requires 13 man-house. Additional costs associated with planning, scheduling, supenision, documentation, etc. are also required for this task.
Withort a sampling disassembly and inspection plan, FNP will be required to remove each train of diesel power each outage. His will cause the unavailability of the ;
diesel train and hence the risk to the core to be twice that which would be required )
with grouping. In light of the good inspection history of these valves, FNP will be l increasing risk to the core without a commensurate gain in the reliability of the j valves. This is counter to the philosophy of 10CFR50.65 of balancing reliability and ;
availability which states that " Adjustments shall be made where necessary to ensure that the objective of preventing failures of structures, systems and components through maintenance is appropriately balanced against the objective of minimizing unavailability of structures, systems and components due to monitoring or preventive maintenance."
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Ahernate Testing: The alternate testing described below is based on GL 89-04 guidance for valve
. grouping and check valve disassembly.
One valve will be disassembled and manually full stroke exercised each refueling outage on a staggered basis. The valve internals will be verified to be structurally sound (no loose or corroded parts) and the disk will be manually exercised to verify full stroke capability. If the disassembled valve is not capable of being full stroke exercised or there is binding or failure of valve internals, the remaining valve in the group will also be disassembled, inspected and manually full stroke exercised during the same outage. The valve will be part stroked with flow after reassembly. The necessary valve operator movement, verifying past stroke exercising, will be confirmed by changes in system pressure, flow rate, level, temperature, seat leakage testing or other positive means or through the use of ultrasonic (or similar) flow measuring desices.
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$ g ENCLOSURE 3 UNIT 2 REVISED RELIEF REOUESTS i
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RELIEF REQUEST Q2P16-RR-V-2 This relief request has been withdrawn.
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RELIEF REQUEST Q2P16-RR-V-3 Valve: QV659, QV660, QV661 Other Valve No: NA Drawing /Coord: D-200013 Sht. 3/C-3, C-10, C-12 System: Service Water (P16)
Category: C Class: 3 Function: Unit 2 Service Water Supply To DG 2C, IC,1-2A.
OM Code Test Disassemble each check valve every refueling outage in accordance with ISTC Requirements: 4.5.4(c).
Basis for There are no system design provisions to verify valve reverse flow closure quarterly, Relief: at cold shutdown or refueling outage. Therefore, per ISTC 4.5.4(c) these valves will be disassembled during refueling outages to verify operability. No reliefis required for the above per OM ISTC 4.5.4(c) if each valve is disassembled every refueling outage.
These valves are the same design (manufacturer, size (with exception stated below),
model number and material of construction) and have the same ser ice conditions including valve orientation, thus they meet the guidance of NRC Generic Letter 89-04, Position 2 for valve grouping for purposes of implementing a disassembly / inspection sampling plan. Valve QV661 is an 8 inch valve while the remaining valves in the group are 6 inch. Since these valves are identical in all other respects and are installed in the same system, the size difference is inconsequential.
'Ihe burden justification for the proposed alternate testing sampling plan is detailed below.
The inspection . history of these valves suggests there - is no need for disassembly / inspection of all three valves each outage, thus any additional expense in doing so would be an unnecessary burden. 'Ihe past nineteen inspections of these valves (total both units) dating back to 1984 have not detected any unsatisfactory conditions. On average, the disassembly / inspection of these valves requires 6 man-hours. - Additional costs associated with planning, scheduling, supervision, documentation, etc. are also required for this task.
Without a sampling disassembly and inspection plan, FNP will be required to remove cach train of diesel power each outage. This will cause the unavailability of the diesel train and hence the risk to the core to be twice that which would be required
' with grouping. In light of the good inspection history of these valves, FNP will be l increasing risk to the core without a commensurate gain in the reliability of the i L valves. This is counter to the philosophy of 10CFR50.65 of balancing reliability and availability which states that " Adjustments shall be made where necessary to ensure that the objective of preventing failures of structures, systems and components through maintenance is appropriately balanced against the objective of minimizing unavailability of structures, systems and components due to monitoring or preventive
- 7. maintenance "
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Alternate Testing: The alternate testing de cribed below is based on GL 89-04 guidance for valve grouping and check valve disassembly.
The valves will be disassembled and manually full stroke exercised each refueling outage on a staggered train related basis. Valves V660 and V661 will be inspected together every other outage and V659 will be inspected on tiu: alternating outages.
The valve internals will be verified to be structurally sound (no loose or corroded parts) and the disk will be manually exercised to verify full stroke capability. If the disassembled valve is not capable of being full stroke exercised or there is binding or failure of valve internals, the remaining valves in the group will also be disassembled, inspected and manually full stroke exercised during the same outage. The valve will ~ l l
be part stroked with flow after reassembly. The necessary valve operator movement, verifying part stroke exercising, will be confirmed by changes in system pressure, flow rate, level, temperature, seat leakage testing or other positive means or through -
the use of ultrasonic (or sindlar) flow measuring devices.
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RELIEF REQUEST Q2P16-RR-V-4 Valve: QV564, QV565 l
Other Valve No: NA Drawing /Coord: D-200013 Sht.3/G-2 System: Service Water (P16)
Category: C
! Class: 3 l Function: Unit 2 Diesel Generator Service Water Train Return Check Valves OM Code Test Disassemble each check valve every refueling outage in accordance with ISTC g Requirements: 4.5.4(c).
Basis for There are no system design provisions to verify valve full forward flow quarterly, at Relief: cold shutdown or refueling outage. Therefore, per ISTC 4.5.4(c) these valves will be disassembled during refueling outages to verify operability. No reliefis required for the above per OM ISTC 4.5.4(c) if each valve is disassembled every refueling outage.
These valves are the same design (manufacturer, size, model number and material of
,. construction) and have the same service conditions including valve orientation,'thus they meet the guidance of NRC Generic Letter 89-04, Position 2 for valve grouping for purposes ofimplementing a disassembly / inspection sampling plan. The burden
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. justification for the proposed alternate testing sampling pbn is detailed below.
l- The inspection history of these valves suggests there is no need for disassembly / inspection of both valves each outage, thus any additional expense in doing so_ would be an unnecessary burden. The past twelve inspections of these valves (total both units) dating back to 1989 have not detected any unsatisfactory conditions. On average, the disassembly / inspection of these valves requires 13 man-hours. Additional costs associated with planning, scheduling, supervision,
. documentation, etc. are also required for this task, s~
Without a sampling d!sessembly and inspection plan, Nr will be required to remove each train of diesel power each outage. This will cause tim unavailability of the diesel train and hence the risk to the core to be twice that which would be required with grouping. In light of the good inspection history of these valves, FNP will be increasing risk to the core without a commensurate gain in the reliability of the valves. This is counter to the philosophy of 10CFR50.65 of balancing reliability and availability which states that " Adjustments shall be made where necessary to ensure that the objective of preventing failures of structures, systems and components through maintenance is appropriately balanced against the objective of minimizing unavailability of structures, systems and components due to monitoring or preventive maintenance "
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Alternate Testing: The alternate testing described below is based on GL 89-04 guidance for valve grouping and check valve disassembly.
One valve will be disassembled and manually full stroke exeicised each refueling outage on a staggered basis. The valve internals will be verifbd to be structurally sound (no loose or corroded parts) and the disk will be manually exercised to verify full stroke capability. If the disassembled valve is not capable of being full stroke exercised or there is binding or failure of valve internals, the remaining valve in the group will also be disassembled, inspected and manually full stioke exercised during the same outage. The valve will be part stroked with flow after:rcassembly. The necessary valve operator movement, verifying part stroke exercising, will be confinned by changes in system pressure, flow rate, level, temperature, seat leakage testing or other positive means or through the use of ultrasonic (or similar) flow measuring devices.
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