ML17299A577

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Rev 0 to 10CFR50,App R Safe Shutdown Evaluation,Outside Control Room Fire Spurious Actuation Study.
ML17299A577
Person / Time
Site: Palo Verde Arizona Public Service icon.png
Issue date: 08/30/1985
From:
ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:
Shared Package
ML17299A576 List:
References
02-NS-110, 02-NS-110-R00, 2-NS-110, 2-NS-110-R, TAC-59247, NUDOCS 8509050207
Download: ML17299A577 (21)
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Text

PVNGS 02-NS-110 10CFR50, APPENDIX R SAFE SHUTDOWN EVALUATION OUTSIDE CONTROL ROON FIRE SPURIOUS ACTUATION STUDY FOR THE PALO VERDE NUCLEAR GENERATING STATION UNIT 2 STUDY 02-NS-110 REVISION 0

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Table of Contents

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1. INTRODUCTION 1.1 Scope 1.2 Objective
2.

SUMMARY

3. CONCLUSIONS AND RECOMMENDATIONS 3.1 General Operational Considerations 8 3.2 Fire Zone: 1 8 3.3 Fire Zone: 2 9 3.4 Fire Zone: 3A 9 3.5 Fire Zone: 3B 10
4. Outside Control Room Fire Spurious Actuation 10 Evaluation Ground Rules 4.1 NRC Requirements 10 4.2 Assumptions and Bases ll
5. Outside Control Room Fire Spurious Actuation 14 Evaluation Logic LIST OF TABLES Table No. Title Fire Event Safe Shutdown Systems 3-1 Outside Control Room Fire Evaluated Fire Zones Figures Fi ure No. Title NS-110-1 Outside Control Room Fire Spurious Actuation Evaluation Logic

PVNGS 02-NS-110

l. INTRODUCTION 1.1 SCOPE Evaluate the impact of fixe-induced hot shorts, open circuits and shorts to ground in electrical circuitry which are routed different from Unit 1 for each fire zone outside the control room on the ability to safely shut down the plant using the safe shutdown (SSD) systems listed in Table l-l, both with and without offsite power.

1.2 OBJECTIVE The objective of this evaluation is to define any necessary special operating, procedure requirements and/or design changes to ensure safe shutdown capability within the operational time constraints.

2.

SUMMARY

Fire-induced hot shorts, open circuits and shorts to ground in electrical circuitx'y can result in the spurious actuation and/or inability to control components, which can impact the capability to achieve safe (cold) shutdown.

To assess the extent of the potential fire damage on safe shutdown, the electrical circuitry in each of the fire zones identified in Table 3-1 has been evaluated. The conclusions and recommendations derived for Unit 1 are applicable for Unit 2; additional Unit 2 specific findings are presented in section 3.

3. CONCLUSIONS AND RECOMMENDATIONS For postulated fires outside the control room, Table 3-1 lists all fire zones evaluated. Only those that were found to impact the ability to achieve SSD have been included in this section.

For each fire zone, this s'ummary identifies:

o Evaluation Findings Potential undesirable spurious control actions/inactions of Unit 2 systems which are different from Unit l.

o Key Monitorable Parametexs (functional)

Those available parameters which enable the operator to identify and mitigate the consequences of spurious control action/inactions, and to reach and maintain a safe (cold) shutdown are listed. These parameters are electrically and physically independent of the fire being evaluated.

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PVNGS 02-NS-110

~ Time Constraints Critical time constraints for system or components operation are quantified.

Operational Considerations The necessary action(s) required to prevent the adverse effects of the spurious control action/inactions summarized in the evaluation findings're detailed.

Compensatory Measures The recommendations to accomplish each of the operational considerations are presented. These compensatory measures vill be available to the plant operators for post-fire shutdown.

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4 PVNGS 02-NS-110 TABLE l-l FIRE EVENT SAFE SHUTDOWN SYSTEMS System

~Sstem AF Auxiliary Feedwater CH Chemical and Volume Control CT Condensate Storage and Transfer DF Diesel Fuel Oil Storage and Transfer DG Diesel Generator EC Essential Chilled Water Essential Cooling Water HVAC - Auxiliary Building HD HVAC Diesel Generator Building HJ HVAC Control Building HS HVAC - Ancillary Building (Spray Pond Pump House)

PB 4160V-ac Class 1E Power PE Class lE Standby Generating System PG 480V-ac Class 1E Power PH 480V-ac Class 1E Power PK 125V-dc Class lE Power PN 120V-ac Class lE Power RC Reactor Coolant System SG Main Steam SI Safety Injection and Shutdown Cooling SP Essential Spray Pond 3146r

PVNGS 02-NS-110 TABLE 3-1 (Sheet 1 of 4)

OUTSIDE CONTROL ROOM FIRE EVALUATED PIRE ZONES SSD TRAIN SSD TRAIN SUBJECT TO BE USED FIRE ZONE~ TO DAMAGE FOR FIRE NOTES'ire CONTROL BUILDING Area 1<a>

1 A See findings 3A A See findings 4A A No findings SA A No findings 6A A No findings 7A A No findings 8A A No findings 9A A No findings 10A A No findings llA A No findings 15A A No findings 18A A No findings 20 A No findings 86A A No findings

, Fire Area II 2 B See findings 3B B A See findings 4B B A No findings 5B B A No findings 6B B No findings 7B B A No findings 8B B A No findings 9B B A No findings 10B B A No findings llB B No findings 12 Neither A No findings 13 Neither A No findings 14 B A No findings 15B Neither A No findings 18B Neither A No findings 19 Neither A No findings 86B B A No findings

~~No safety-related raceway in the zone.

>Fire areas and zones are defined in PSAR Appendix 9B.

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PVNGS 02-NS-110 TABLE 3-1 (Sheet 2 of 4)

OUTSIDE CONTROL ROOM FIRE EVALUATED FIRE ZONES SSD TRAIN SSD TRAIN SUBJECT TO BE USED FIRE ZONE( TO DAMAGE FOR FIRE NOTES:

MAIN STEAM SUPPORT STRUCTURE Fire Area XII 72 A No findings 73 B No findings 74A A No findings 74B B No findings AUXILIARY BUILDING Fire Area XIII 30A No findings 31A No findings 32A No findings Fire Area XIV 30B No findings 31B No findings 32B No findings Fire Area XV 33A Neither B <<No findings 33B Neither A "No findings 87A A B No findings 87B Neither A <<<<No findings 89 iQeither A <<<<No findings 90 Neither B <<<<No findings 88A Neither B <<No findings 88B B A No findings 34A A B No findings 34B B A ,No findxngs 3SA A B No findings 35B B A No findings 36 Neither B <<<<No findings 37A A B No findings

<<No raceway in the zone.

<<No safety-related raceway in the zone.

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PVNGS 02-NS-110 TABLE 3-1 (Sheet 3 of 4)

SSD TRAIN SSD TRAIN SUBJECT TO BE USED FIRE ZONE<<> TO DAMAGE FOR FIRE NOTES:

37B B No findings 37C A B No findings 37D B A No findings 37E Neither A <<<<No findings 39A Neither B No findings 39B B A No findings 42C B A No findings 42D B No findings 43 Neither B No findings 44 A B No findings 45 Neither B <<<<No findings 46A A B No findings 46B B A No findings 46E Neither No findings 48 B A No findings 49A Neither B <<No findings 49B Neither B <<No findings 49C Neither B <<No findings 49D Neither B <<No findings 49E Neither B <<No findings 49F Neither B <<No findings 49G Neither B <<No findings 49H Neither B <<<<No findings 50A B A No findings 50B Neither A <<<<No findings 51A Neither A <<<<No findings 51B B A No findings 52A A B No findings 52D B A No findings 53 B A No findings 54 B A No findings 55A Neither B <<<<No findings 55C iNeither B No findings 55E Neither B No findings 56A Neither B No findings 56B A B No findings 56C A B No findings 57A Neither B <<<<No findings 57B A B No findings 57C Neither B <<<<No findings

<<No raceway in the zone

<<<<No safety-related raceway in the zone.

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PVNGS 02-NS-110 TABLE 3-1 (Sheet 4 of 4)

SSD TRAIN SSD TRAIN SUBJECT TO BE USED FIRE ZONE<<> TO DAMAGE FOR FIRE NOTES'7D Neither <~No findings 57E Neither 'k'@No findings 57F Neither ~~No findings 57G Neither +~No findings 57H Neither >+No findings 57I A No findings 57J A No findings 57K Neither +~No findings 57L Neither ><No findings 57M Neither 4'O'No findings 57N A No findings 57P A No findings Fire Area XVI 42A No findings 47A No findings Fire Area XVII 42B A No findings 47B A No findings

<~No safety-related raceway in the zone.

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PVNGS 02-NS-110 3.1 GENERAL OPERATIONAL CONSIDERATIONS

1. For a fire in any given fire zone, safe shutdown is to be accomplished using the Table 3-1 identified safe shutdown systems for that specific fire zone.
2. Isolate the control room HVAC by manual initiation of CRVIAS upon indication of a control building fire outside the control room, In addition, for a fire in Fire Zone 1, override and stop essential AHU M-HJA-F04 and for a fire in Fire Zone 2, override and stop essential AHU M-HJB-F04.
3. To preclude intolerable spurious concerns for outside the control room fires, the pending plant changes/operational considerations must be implemented:

place the breaker for SDC suction valves J-SIC-UV-653 and J-SID-UV-654 in the open condition during normal plant operating conditions when RCS pressure is greater than the SDC system suction isolation interlock setpoint.

~ To prevent a fire in Fire Zone 42C from disabling all charging pumps, the Train A charging pump low suction pressure switch (J-CHA-PSL-216) separation concerns are to be resolved as part of the Appendix R separation review efforts.

~ The atmospheric dump valve (ADV) nitrogen supply must remain operable.

4. To ensure availability of a borated water source to the charging pumps, the RWT gravity feed flow path through air-operated valve J-CHN-HV-32 (fails open) and motor-operated valve J-CHE-HV-536 is designated as Train A while the RWT gravity feed flow path through motor-operated valve J-CHB-HV-530 and manual valves CHV327, and CHV755 (Train A charging pump) or CHV756 (Train B charging pump) is designated as Train B. The train defined to be used for safe shutdown in the event of a specific fire identified in Table 3-1 along with the evaluation findings for that fire zone will ensure proper charging .pump suction alignment. (The basis for designating the flow paths as Train A or Train B is the physical location of the valves.)

3.2 FIRE ZONE: 1 (for a fire in this zone, use SSD Train B)

1. Evaluation Findin  :

Loss of pressurizer pressure control may occur due to spurious opening of pressurizer spray valve J-CHA-HV-205

2. Ke Monitorable Parameters (Functional)

Pressurizer pressure 3146r

PVNGS 02-NS-110

3. Time Constraints:

Not applicable (see compensatory measures)

4. 0 erational Considerations:

Stop pressurizer auxiliary spray flow to prevent uncontrolled RCS depressurization.

5. Com ensator Neasures:

To overcome spurious uncontrolled RCS depressurization, stop charging flow and open disconnect switch DS-09-07 at auxiliary relay cabinet E-Zhh-C03 to close J-CHA-HV-205 3.3 Fire Zone: 2 (For a fire in this zone, use SSD Train h)

l. Evaluation Findin  :

Loss of pressurizer pressure control may occur due to spurious opening of pressurized spray valve J-CHB-HV-203

2. Ke Nonitorable Parameters (Functional)

Pressurizer pressure

3. Time Constraints:

Not applicable (see compensatory measures)

4. 0 erational Considerations:

Stop pressurized auxiliary spray flow to prevent uncontrolled RCS depressurization

5. Com ensator Measures:

To overcome spurious uncontrolled RCS depressurizations, stops charging, flow and open disconnect switch DS-09-12 at auxiliary relay cabinet E-ZhB-C03 to close J-CHB-HV-203 3.4 FIRE ZONE: 3h (for a fire in this zone, use SSD Train B)

l. Evaluation Findin  :

Loss of pressurizer pressure control may occur,due to spurious opening, of pressurizer spray valve J-CHh-HV-205

2. Ke Nonitorable Parameters (Functional)

Pressurizer pressure 3146r

PVNGS 02-NS-110

3. Time Constraints:

Not applicable (see compensatory measures)

4. 0 erational Considerations:

Stop pressurizer auxiliary spray flow to prevent uncontrolled RCS depressurization

5. Com ensator ?measures:

To overcome spurious uncontrolled RCS depressurization, stop charging flow and open disconnect switch DS-09-07 at auxiliary relay cabinet E-Zhh-C03 to close J-CHh-HV-205.

3.5 FIRE ZONE: 3B (for a fire in this zone, use SSD train h)

l. Evaluation Findin Loss of pressurizer pressure control may occur due to spurious opening of pressurizer spray valve J-CHB-HV-203
2. Ke Honitorable Parameters (Functional)

Pressurizer pressure

3. Time Constraints:

Not applicable (see compensatory measures)

4. 0 erational Considerations:

Stop pressurizer auxiliary spray flow to prevent uncontrolled RCS depressurization.

5. Com ensator Measures:

To overcome spurious uncontrolled RCS depressurization, stop charging flow and open disconnect switch DS-09-12 at auxiliary relay cabinet E-ZhB-C03 to close J-CHB-HV-203 4.0 OUTSIDE CONTROL ROON FIRE SPURIOUS hCTUhTION EVhLUhTION GROUND RULES

l. No accidents are assumed concurrent with the fire.
2. Cold shutdown must be achieved and maintained with and without offsite power.
3. hs the consequence of the fire, hot shorts, open circuits, or shorts to ground must be considered.

3146r 4, Where hi/low pressure interface is involved (RCS only), any number of fire-induced actions/inactions must be postulated.

4.2 ASSUMPTIONS AND BASES 1~ Either the Train A or the Train B fire event safe shutdown components and monitorable parameters identified in FSAR Table 9B.1-4 will be operable following any fire event.

Basis:

Appendix R train separation is provided for the FSAR Table 9B.1-4 components.

2 ~ The worst case combination of spurious actuation of the device under consideration and fire damage to circuits of other components in the fire zone will be evaluated. In addition, the effects of hot shorts, shorts to ground and opens on ESFAS initiating and power supply circuits shall be evaluated.

Basis:

This assumption considers that a fire will damage more than one circuit in the fire zone but not necessarily all circuits. No other components with circuits in the same fire zone can be used to mitigate the effects of the spurious actuation under consideration; conversely, the action/inaction of these components combined with the spurious actuation may preclude safe shutdown.

3. A spurious control signal action/inaction shall be defined as being caused by a single hot short, open circuit, or short to ground, impacting a single component.

Basis:

Each electrically-operated component has its own unique control circuits, which may be affected by the single hot short, open circuit, or short to ground.

4~ Fire-induced failures in three-phase power cables can only result in a loss of power to, or the inability to supply power to, the component.

Basis:

Hot shorts in three-phase power circuits resulting in maintained contact are not considered credible.

5. The conditions stated in Assumption 2 can be assumed to occur at any time following the onset of the fire event, until action is taken to defeat or preclude the action/inaction from occurring.

3146r PVNGS 02-NS-110 Basis:

Because of the Appendix R mandate to achieve and maintain cold shutdown, the plant can be in any of its normal operating modes (i.e., Modes 1-6) at the initiation of the fire event.

6. For offsite power available, all equipment not affected by the fire will remain in its refire condition( i.e., condition during normal plant operation for the assumed mode). For loss of offsite power, all equipment goes to its loss of offsite power design failure position. (NOTE: One strategy may be to selectively shed power from equipment/buses to minimize adverse spurious action/inaction impact.)

Basis:

The basis for this assumption is simply that the components/systems will function as designed, with the exception of the single spurious actuation.

7. The analysis of fire damage will be performed on a fire zone basis and only components in safety-related systems will be considered.

Basis Generic Letter 81-12 allows for the choice of evaluating spurious actuation on a fire area or systems basis. The security system monitoring of plant fire detection systems identifies fire situations on a fire zone basis and alerts the operators of an incipient fire. Using the result of a fire zone analysis, the operators can take immediate action for the affected zone and anticipate safe shutdown system alignment needs for the possibility of fire spreading to adjacent zones. The inherent plant design is such that the safe shutdown equipment listed in FSAR Table 9B.1-4 can overcome any effects by nonsafety-related systems on the capability to achieve safe shutdown. The fire event safe shutdown systems are identified in Table 1-1.

8. There will be some time interval between the onset of the fire event (time t=O) and that time when the operator can reasonably be expected to be able to counter the adverse effects of the spurious action/inaction. (This time interval should be quantified.)

Basis:

This assumption is intended to reflect the "real world" situation an operator may face as a result of a fire. The evaluation will define necessary operational considerations and applicable time constraints necessary to aid an operator in assessing overall plant conditions and controlling the plant.

9. Protection of nonsafe shutdown equipment is not a priority item of this evaluation.

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PVNGS 02-NS-110 Basis:

The Appendix R mandate is to achieve and maintain cold shutdown to protect the health and safety of the public.

10. All plant operating modes except refueling will be evaluated (i,e.,

Modes 1, 2, 3, 4 and 5).

Basis:

There is sufficient time during the refueling mode (Mode 6) for an operator to assess plant status and respond to conditions without jeopardizing reactivity control or fission product boundary integrity.

ll. Only systems and components which can affect (positive or negative impact) safe shutdown are subject to evaluation.

Basis:

Appendix R requires being able to achieve and maintain cold shutdown. Any systems/components not impacting safe shutdown are not within the scope of this evaluation.

12. Turbine trip does not necessarily result in an LOP condition.

Basis:

Given a turbine trip, it may be more conservative to assume that an LOP condition does not occur. The turbine trip circuitry is subject to the single hot short, open circuit, or short to ground.

13. No single (including common mode) failures in addition to the spurious action/inaction will be evaluated.

Basis:

Appendix R's scope does not consider any failures other than those caused by the fire.

14. Evaluation drawings will be Bechtel-controlled project documents.

Examples are:

PAID's 13-M-XKP-XXX Elementaries 13-E-XKB-XXX Loop Diagrams 13-J-XXE-XXX One-Line Diagrams 13-E-XXA-XXX Controlled Vendor Prints FSAR Chapter 9 Appendix 9B Basis:

The identification of the control drawings defines the source material used for the evaluation and aids in traceability and reproducibility of results.

3146r PVNGS 02-NS-110

15. Postulated fires in each FSAR Table 9B fire zone of the Auxiliary Building Control Building and Main Steam Support Structure will be evaluated for their impact on the ability to achieve SSD.

Basis:

The Turbine Building and Radwaste Building are excluded since no safety-related equipment is housed in these areas. The Fuel Handling Building is excluded since it does not house safe shutdown components. The Diesel Generator Building is excluded because it complies with Appendix R with no deviations. The Containment Building is excluded because it is addressed by the deviation from

.the separation requirements of Appendix R for components and circuits located inside containment.

16. Deleted.
17. Simultaneous failures of both power supplies to one of the BOP ESFAS cabinets (FBEVAS, CREFAS, CPIAS, Load Shed, CRVIAS, DGSS, Load Sequencer ) cannot prevent the ability to achieve safe (cold) shutdown.

Basis:

Simultaneous failures of both power supplies to a BOP ESFAS cabinet can result in activation of both trains of sequencer activated devices associated with FBEVAS, CREFAS, and CPIAS. This is not a significant concern since actuation of these devices (essential chilled water, cooling water, spray pond, etc.) has no negative impact on the ability to achieve safe shutdown. NSSS components (LPSI, HPSI and containment spray pumps) will start only in the affected tr'ain but system operation will not occur (i.e., valves will not align) without simultaneous NSSS ESFAS present.

5.0 OUTSIDE CONTROL ROOM FIRE SPURIOUS ACTUATION EVALUATION LOGIC Figure NS-110-1 details the logic used in evaluating the outside control room fires.

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Palo Verde Itueleor CeneratinE Slalion loef Ilao. AttsssNs n Ssls Ahssassss lsslssliss OUTSIOE CONTROL ROON FIRE SPUR IOIS ACTUATIOM EVALUATION IAXIIC Figure MS-ll0-1

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