ML110750426
| ML110750426 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/15/2011 |
| From: | David Bice Entergy Operations |
| To: | Plant Licensing Branch IV |
| Kalyanam N, NRR/DLPM, 415-1480 | |
| References | |
| TAC ME5759 | |
| Download: ML110750426 (25) | |
Text
SWS Room Cooling Required ActionSWS Room Cooling Required Action 1
INTRODUCTION INTRODUCTION
- The ANO The ANO--1 Technical Specifications (TSs) do not 1 Technical Specifications (TSs) do not specifically address room cooling support specifically address room cooling support features for TS features for TS--supported equipment supported equipmentSWS Room Cooling Required Action SWS Room Cooling Required Action
- ANO ANO--1 received a non1 received a non--cited violation for not cited violation for not entering supported equipment TSs when a entering supported equipment TSs when a single cooling subsystem was inoperable single cooling subsystem was inoperable
- Lack of guidance in this matter results in Lack of guidance in this matter results in conservatively entering TSs associated with the conservatively entering TSs associated with the supported electrical equipment supported electrical equipment (8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time).(8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time).
2 PURPOSE PURPOSEDetermine or develop appropriate actions Determine or develop appropriate actions that will address time periods when a that will address time periods when a SWS Room Cooling Required Action SWS Room Cooling Required Action p
p non non--TS room cooling subsystem is TS room cooling subsystem is out out--of of--service considering its impact on service considering its impact on TS TS--required equipment required equipment 3
OUTLINE OUTLINE*
- Brief History
Brief History
- Configuration Assessment
Configuration AssessmentFtifthSiWtSt(SWS)
FtifthSiWtSt(SWS)SWS Room Cooling Required Action SWS Room Cooling Required Action
- F unc ti on o f th e S erv i ce W a t er S ys t em (SWS)F unc ti on o f th e S erv i ce W a t er S ys t em (SWS)*
- Normal Room Cooling
Normal Room Cooling
- Emergency Room Cooling
Emergency Room Cooling
- Impact on Electrical Equipment Impact on Electrical Equipment
- Proposed Options
Proposed Options
- Conclusion
Conclusion 4
REGULATORY HISTORYREGULATORY HISTORY
- Following initial startup in the 1970s, a Following initial startup in the 1970s, a lack of an emergency cooling subsystem lack of an emergency cooling subsystem forANO forANO-
-1electricalbusareaswas 1electricalbusareaswasSWS Room Cooling Required Action SWS Room Cooling Required Action for ANO for ANO 1 electrical bus areas was 1 electrical bus areas was identified identified
- Vital powered, non Vital powered, non--Q VUC Q VUC--13A/B installed 13A/B installed at ANO at ANO--1 in interim. Q1 in interim. Q--emergency cooling emergency cooling subsystem installed soon thereafter subsystem installed soon thereafter consisting of Service Water (SW) cooled consisting of Service Water (SW) cooled VCH VCH--4A/B chillers and associated room 4A/B chillers and associated room coolers VUC coolers VUC--14A/B/C/D and VUC14A/B/C/D and VUC-
-2B/D 2B/D 5 REGULATORY HISTORYREGULATORY HISTORY
- ANO ANO--1 established proceduralized 1 established proceduralized compensatory measures and analysis to compensatory measures and analysis to support maintenance on one subsystem support maintenance on one subsystem SWS Room Cooling Required Action SWS Room Cooling Required Actiontrain while maintaining operability of train while maintaining operability of TS TS--supported electrical equipmentsupported electrical equipment
- Compensatory measures included Compensatory measures included reliance on remaining SW train and reliance on remaining SW train and chiller subsystem, reliance on nonchiller subsystem, reliance on non--Q vital Q vital powered VUC powered VUC--13A/B, and/or convection 13A/B, and/or convection cooling via compensatory measurescooling via compensatory measures 6
REGULATORY HISTORYREGULATORY HISTORY
- Recently, the validity of these evaluations Recently, the validity of these evaluations and analysis had been challenged and and analysis had been challenged and AN O AN O--1 received a non 1 received a non--cited violation for cited violation for SWS Room Cooling Required Action SWS Room Cooling Required Actionfailing to enter supported system TSs failing to enter supported system TSs when one cooling subsystem was when one cooling subsystem was inoperable inoperable 7
- Adequate cooling for both trains of electrical Adequate cooling for both trains of electrical equipment can be provided through equipment can be provided through established compensatory measures, established compensatory measures, SWS Room Cooling Required ActionSWS Room Cooling Required ActionCONFIGURATION ASSESSMENT CONFIGURATION ASSESSMENTassuming either the remaining operable assuming either the remaining operable VCH VCH--4A/B chiller or the vital powered non4A/B chiller or the vital powered non--Q Q VUC VUC--13A/B coolers are available. However, 13A/B coolers are available. However, the non the non--Q VUC Q VUC--13A/B coolers are not credited 13A/B coolers are not credited in the current analysis.in the current analysis.
- Station risk verified to be acceptable when Station risk verified to be acceptable when one room cooling subsystem train inoperableone room cooling subsystem train inoperable 8
An evaluation of risk associated with one train of An evaluation of risk associated with one train of the emergency room cooling subsystem was the emergency room cooling subsystem was performed over a 7performed over a 7--day period and found to be day period and found to be acceptable
acceptableSWS Room Cooling Required Action SWS Room Cooling Required ActionCONFIGURATION ASSESSMENT CONFIGURATION ASSESSMENT
- Incremental core damage probability (ICCDP) = 5.22E Incremental core damage probability (ICCDP) = 5.22E-
-08 08**Incremental conditional large early release probability Incremental conditional large early release probability conservatively taken as 5.22E conservatively taken as 5.22E-
-09 09**Sensitivity analysis of common cause failure modes Sensitivity analysis of common cause failure modes results in ICCDP = 5.70Eresults in ICCDP = 5.70E-
-08 08**External event ICCDP = 1.04E External event ICCDP = 1.04E-
-07 07 acceptable
.acceptable
.9
- ANO initiated action to determine what TSs, if ANO initiated action to determine what TSs, if any, should be applied when one room cooling any, should be applied when one room cooling subsystem was inoperable subsystem was inoperableSWS Room Cooling Required Action SWS Room Cooling Required ActionCONFIGURATION ASSESSMENT CONFIGURATION ASSESSMENT
- Based on industry input a nd that SW provides the Based on industry input a nd that SW provides the ultimate support needed to cool the areas, ANO ultimate support needed to cool the areas, ANO believes that the SW TS should be applied believes that the SW TS should be applied 10
- The 72 The 72--hour Completion Time provides a reasonable period hour Completion Time provides a reasonable period torestorethesupportfunctionforsupportedequipmentnot torestorethesupportfunctionforsupportedequipmentnotSWS Room Cooling Required Action SWS Room Cooling Required ActionCONFIGURATION ASSESSMENT CONFIGURATION ASSESSMENT to restore the support function for supported equipment not to restore the support function for supported equipment not immediately challenged by a loss of a SWS loop and is based immediately challenged by a loss of a SWS loop and is based on the redundant capabilities afforded by the operable loop on the redundant capabilities afforded by the operable loop and systems, and the low probability of an accident during and systems, and the low probability of an accident during this periodthis period
- It is not unusual for support system restoration periods to be It is not unusual for support system restoration periods to be longer than the supported system (i.e., 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to restore longer than the supported system (i.e., 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to restore inverters while the respective bus must be restored in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />)inverters while the respective bus must be restored in 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />)
Major safety related components supported by the SWS include:
- Decay Heat Removal (DHR) Heat Exchangers Decay Heat Removal (DHR) Heat Exchangers
- DHR (L ow Pressure I n j ec ti on) P ump J ac k e t / B ear ings C oo l ers DHR (L ow Pressure I n j ec ti on) P ump J ac k e t / B ear ings C oo l ers**Emergency Diesel Generator (EDG) Cooling Emergency Diesel Generator (EDG) Cooling
- Emergency Switchgear Room Chillers (discussed below)
Emergency Switchgear Room Chillers (discussed below) 12 FUNCTION OF THE SWSFUNCTION OF THE SWSThe SWS does not mitigate accidents in and of The SWS does not mitigate accidents in and of itself, but is a support systemitself, but is a support systemTheSWSsupportstheremovalofpost TheSWSsupportstheremovalofpost
-
-accident accidentSWS Room Cooling Required Action SWS Room Cooling Required Action The SWS supports the removal of post The SWS supports the removal of post accident accident residual heat from the reactor core and cooling the residual heat from the reactor core and cooling the Reactor Building atmosphereReactor Building atmosphereMost SWS room cooling subsystems provide heat Most SWS room cooling subsystems provide heat removal support for equipment located in a single removal support for equipment located in a single room. However, switchgear room cooling involves room. However, switchgear room cooling involves several different rooms housing various TSseveral different rooms housing various TS-
-required equipment required equipment 13 NORMAL ROOM COOLINGNORMAL ROOM COOLING
- Normal Auxiliary Building ventilation VSF Normal Auxiliary Building ventilation VSF-
-7A/B, 7A/B, VEF VEF-
-8A/B 8A/B Available cooling sources:
Available cooling sources: (see drawing)
(see drawing)SWS Room Cooling Required Action SWS Room Cooling Required Action VEF VEF 8A/B 8A/B*
- Normal vital powered switchgear room coolers
Normal vital powered switchgear room coolers VUC VUC--2A/C and non2A/C and non--Q cooler VSF Q cooler VSF-
-10 10**Vital powered, self Vital powered, self--contained coolers VUCcontained coolers VUC-
-13A/B 13A/B**Self Self--contained cooler VUCcontained cooler VUC--11 11**Room exhaust fans
Room exhaust fans 14 SWS Room Cooling Required ActionSWS Room Cooling Required Action 149D01D13B61VUC14BSouth Electrical Equipment RoomBattery Charger RoomAB Vent VSF7BNOTES:1.All areas approximate El. 368' and approximate scale unless otherwise stated.2.VUC-11, VUC-13A, and VUC-13B are self-contained chilled water units.
VUC-13A and VUC-13B are energized from vital power.3.VUC-2A, VUC-2B, and VSF-10 require chilledwatersupplyforcooling(ACWUpper North Electrical Penetration Room El. 386'Pen Rm Exhaust VEF38A/BNormal Switchgear Room CoolingAB Vent VSF7A 15 109 110 99 98 100 104 95 98C187C186C539C511C513B52 B3C579D15B21B51 VUC 14DVUC-11 VUC 2B VUC 2A VUC 2C VUC 2DD06 A3 B5 X5X6CB57 Y3Y26VCH4B A4 B6 X6Y28B63B56 Y4Y24Y25VCH4A VUC 13B VUC 14CD07D07D03BY13Y11D03AY15D17VEF 33D01D16VUC13AD11 VUC 14AD02D04BD04AD21D14D06VEF34Loop 1 SWSLoop 2 SWSControl Room Chilled Water4160V/480VSwitchgear RoomsBattery Charger RoomBattery RoomBattery RoomCorridorchilled water supply for cooling (ACW supply) which is initially lost upon a ES Actuation.VSF10 EMERGENCY ROOM COOLINGEMERGENCY ROOM COOLING
- Coolers VUC
Coolers VUC--14A/B/C/D and VUC14A/B/C/D and VUC-
-2B/D supplied 2B/D supplied b y SW S b y SW S--cooled chillers VCHcooled chillers VCH
-
-4A/B 4A/B Available cooling sources:
Available cooling sources: (see drawing)
(see drawing)SWS Room Cooling Required Action SWS Room Cooling Required Action y
y*
- Vital powered, self Vital powered, self--contained coolers VUCcontained coolers VUC-
-13A/B 13A/B should remain availableshould remain available
- TS TS--required Penetration Room ventilation required Penetration Room ventilation VEF VEF--38A/B (forced air exhaust only)38A/B (forced air exhaust only)
- Vital powered room exhaust fans should remain Vital powered room exhaust fans should remain available available 16 SWS Room Cooling Required ActionSWS Room Cooling Required Action 149D01D13B61VUC14BSouth Electrical Equipment RoomBattery Charger RoomAB Vent VSF7BUpper North Electrical Penetration Room El. 386'Pen Rm Exhaust VEF38A/BNOTES:1.All areas approximate El. 368' and approximate scale unless otherwise stated.2.VUC-11, VUC-13A, and VUC-13B are self-contained chilled water units.
VUC-13A and VUC-13B are energized from vital power.3.VUC-2A, VUC-2B, and VSF-10 require chilledwatersupplyforcooling(ACWEmergency Switchgear Room CoolingAB Vent VSF7A 109 110 99 98 100 104 95 98C187C186C539C511C513B52 B3C579D15B21B51 VUC 14DVUC-11 VUC 2B VUC 2A VUC 2C VUC 2DD06 A3 B5 X5X6CB57 Y3Y26VCH4B A4 B6 X6Y28B63B56 Y4Y24Y25VCH4A VUC 13B VUC 14CD07D07D03BY13Y11D03AY15D17VEF 33D01D16VUC13AD11 VUC 14AD02D04BD04AD21D14D06VEF34Loop 1 SWSLoop 2 SWSControl Room Chilled Water4160V/480VSwitchgear RoomsBattery Charger RoomBattery RoomBattery RoomCorridorVSF10 17chilled water supply for cooling (ACW supply) which is initially lost upon a ES Actuation.
IMPACT TO ELECTRICAL EQUIPMENTIMPACT TO ELECTRICAL EQUIPMENTCurrent procedural guidance requires Current procedural guidance requires implementation of compensatory measures to implementation of compensatory measures to limit equipment impact when one train of the limit equipment impact when one train of the libtiiblAtih libtiiblAtihSWS Room Cooling Required Action SWS Room Cooling Required Action
- Pre Pre--determined doors are opened to enhance convection determined doors are opened to enhance convection cooling cooling**Unnecessary loads are reduced Unnecessary loads are reduced
- Other ventilation (Q & non Other ventilation (Q & non--Q) is verified in operation or availableQ) is verified in operation or available
- Increased monitoring Increased monitoring coo li ng su b sys t em i s i nopera ble. A c ti ons h ave coo li ng su b sys t em i s i nopera ble. A c ti ons h ave been evaluated against resources and timing, been evaluated against resources and timing, and found to be acceptable.and found to be acceptable.
18 IMPACT TO ELECTRICAL EQUIPMENTIMPACT TO ELECTRICAL EQUIPMENTNo impact to equipment during normal No impact to equipment during normal operations.
operations.Liitditt Liitdittidt idtSWS Room Cooling Required Action SWS Room Cooling Required Action
- No vital battery or inverter impact during the No vital battery or inverter impact during the respective 2 respective 2--hour post hour post--accident mission time accident mission time
- Analysis currently underway to determine
Analysis currently underway to determine impact on associated rooms with no chillers impact on associated rooms with no chillers available crediting c onvection cooling only available crediting c onvection cooling only using refined techniques using refined techniques Li m it e d i mpac t pos t Li m it e d i mpac t pos t-
-acc id en t: acc id en t: 19 Cooling sources expected to be available postCooling sources expected to be available post-
-accident assuming one train of the emergency accident assuming one train of the emergency room cooling subsystem previously out of room cooling subsystem previously out of serviceand serviceandoffsitepowerislost offsitepowerislost
- SWS Room Cooling Required Action SWS Room Cooling Required ActionIMPACT TO ELECTRICAL EQUIPMENT IMPACT TO ELECTRICAL EQUIPMENT
- Coolers VUC
Coolers VUC--14A/B and VUC14A/B and VUC--2D supplied by SWS2D supplied by SWS-
-cooled chiller VCHcooled chiller VCH--4A 4A OR OR Coolers VUC
Coolers VUC--14C/D and 14C/D and VUC VUC--2B supplied by SWS2B supplied by SWS--cooled chiller VCHcooled chiller VCH-
-4B.4B.**Vital powered, self Vital powered, self--contained coolers VUCcontained coolers VUC-
-13A/B 13A/B**Various room exhaust fans should remain available Various room exhaust fans should remain available
- Convection cooling via compensatory measures Convection cooling via compensatory measures service and service and offsite power is lostoffsite power is lost:
- 20 If offsite power remains available, additional cooling If offsite power remains available, additional cooling and ventilation sources are expected to be available and ventilation sources are expected to be available post post--accident assuming one train of the emergency accident assuming one train of the emergency roomcoolingsubsystemwaspreviouslyoutof roomcoolingsubsystemwaspreviouslyoutofSWS Room Cooling Required Action SWS Room Cooling Required ActionIMPACT TO ELECTRICAL EQUIPMENT IMPACT TO ELECTRICAL EQUIPMENT
- Auxiliary Building supply/exhaust *VSF Auxiliary Building supply/exhaust *VSF--7A/B, VEF 7A/B, VEF-
-8A/B 8A/B**Normal vital powered switchgear room coolers Normal vital powered switchgear room coolers
- VUC*VUC--2A/C, and non 2A/C, and non--vital/non vital/non--Q cooler *VSFQ cooler *VSF-
-10 10**Self Self--contained cooler VUCcontained cooler VUC--11 11 room cooling subsystem was previously out of room cooling subsystem was previously out of service: service:*requires Auxiliary Cooling Water to be restored if more than forced air *requires Auxiliary Cooling Water to be restored if more than forced air is neededis needed 21 PROPOSED OPTIONSPROPOSED OPTIONS
- Using Part 9900 guidance, further evaluate the effects Using Part 9900 guidance, further evaluate the effects of a loss of both emergency room cooling subsystem of a loss of both emergency room cooling subsystem The following options are under consideration by ANO:The following options are under consideration by ANO:SWS Room Cooling Required Action SWS Room Cooling Required Actiontrains (unlikely to validate design temperature limits trains (unlikely to validate design temperature limits not exceeded in all rooms under all ambient not exceeded in all rooms under all ambient conditions) conditions)
- Develop new separate TS for these subsystems (this Develop new separate TS for these subsystems (this would be a significant deviation from Standard TSs)would be a significant deviation from Standard TSs)
- Add action to SW TS (see next page)
Add action to SW TS (see next page) 22 PROPOSED OPTIONSPROPOSED OPTIONSA.One SWS loop inoperable for reasons other than Condition B.A.1 -----------------------------------NOTES--------------------------------1. Enter applicable Conditions and Required Actionsof LCO 3.8.1, "ACSources -Operating," for dieselgenerator made inoperable by SWS.2.EnterApplicableConditionsandRequiredActionsSWS Room Cooling Required ActionSWS Room Cooling Required Action 23 2. Enter Applicable Conditions and Required Actionsof LCO 3.4.6, "RCS Loops -MODE 4," for decayheat removal made inoperable by SWS-----------------------------------------------------------------------------
Restore SWS loop to OPERABLE status.72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />sB.Required SWS room/
area cooling subsystem(s) associated with a single SWS loop inoperable.B.1Restore required SWS room/area cooling subsystem(s) to OPERABLE status.72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> C.Required Action s and associated Completion Time snot met. C.1Be in Mode 3.AND C.2 Be in Mode 5.6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />s36 hours CONCLUSION CONCLUSIONANO proposes entry into SWS TS Condition A in its current ANO proposes entry into SWS TS Condition A in its current form. The SWS TS addresses the room cooling function of form. The SWS TS addresses the room cooling function of required room coolers. The SWS LCO provides reasonable required room coolers. The SWS LCO provides reasonable actions considerin g the im pact of the potential conditions.
actions considerin g the im pact of the potential conditions. SWS Room Cooling Required Action SWS Room Cooling Required Actiongpp gppLBDs and procedures would be revised accordingly in LBDs and procedures would be revised accordingly in accordance with 10 CFR 50.59.accordance with 10 CFR 50.59.If necessary, ANO can propose a change to the SWS TS If necessary, ANO can propose a change to the SWS TS specifying a Required Action for the room cooling function specifying a Required Action for the room cooling function of required room coolers. Prompt review of the change of required room coolers. Prompt review of the change would be desired to avoid the potential for unnecessary would be desired to avoid the potential for unnecessary plant maneuvering resulting from current interpretations, or plant maneuvering resulting from current interpretations, or a request for a Notice of Enforcement Discretion.a request for a Notice of Enforcement Discretion.
24 OPENDISCUSSION OPEN DISCUSSION 25