IR 05000400/2000009
| ML20114E210 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 05/12/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Hunter C (301) 415-1394 | |
| References | |
| IR 2000009 | |
| Download: ML20114E210 (14) | |
Text
SENSITIVE - NOT FOR PUBLIC DISCLOSURE Attachment 1
SENSITIVE - NOT FOR PUBLIC DISCLOSURE Final Precursor Analysis Accident Sequence Precursor Program --- Office of Nuclear Regulatory Research Shearon Harris Design Deficiency involving Inadequate Fire Protection and Suppression System for Switchgear Room B and Auxiliary Control Panel Room
Inspection Report Date:
12/18/2001 Inspection Report:
50-400/00-09
Condition Summary The inspection report 50-400/2000-09 (Ref. 1) indicated that the licensee stated that fire endurance testing demonstrated that the Thermo-Lag walls, which serve as part of the fire area separation barriers between Switchgear Room B and the Auxiliary Control Panel (ACP) room, would provide a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 48 minutes barrier for a 3-hour fire loading area with no automatic suppressio Further, the licensees fire brigade had not practiced in the area for over seven year Caus The cause of this event is changes made to the Updated Final Safety Analysis Report (UFSAR) under 10 CFR 50.59 to revise the fire rating of the Thermo-Lag fire barrier between the Switchgear Room B and ACP room from a Safety Evaluation Report (SER) approved 3-hour fire barrier to a lesser rated fire barrier without prior Commission approva This involved a change to the approved fire protection program. The change to the Thermo-Lag barrier fire rating represented a degradation (derating) of the margin of fire resistance from that established in the approved fire protection progra The fire barrier rating has been estimated to be as low as one hour by U.S. Nuclear Regulatory Commission (NRC) staff.
Recovery opportunit A postulated fire in fire Switchgear Room B is assumed to propagate to the ACP Room unless successfully suppressed by the fire brigade within one hour. In this case, all train B safety-related equipment and the AFW turbine-driven pump, including the steam generator B power operated relief valves (ADVs) and some train A power cables in the ACP room (for A and C steam generator ADVs, AFW motor-driven pump A, and the heating, ventilation and air conditioning (HVAC) system for train A equipment) are considered failed with no recover Recovery of failed HVAC system function is assumed by installation of portable fans to provide equipment cooling in Switchgear Room The Switchgear Room B area has no fixed suppression system, but does have a detection system that uses ionization smoke detector Response by the fire brigade may have been impaired throughout the years, as seen in several Condition Reports written concerning equipment and the lack of fire brigade training in the switchgear rooms.
In summary, the B train is lost completely due to a fire in Switchgear Room B and through propagation to ACP Room, the AFWMDPA pump and AFWTDP flow control portions of the A train are also los Equipment lost is as follows:
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE Switchgear Room B
B Train Motor-driven auxiliary feedwater (MDAFW) pump, suction valves from condensate storage tank (CST) & essential service water (ESW), and AFW discharge valves to steam generators (SGs).
- B Train charging/safety injection pumps (CSIPs), suction valves from the volume control tank (VCT), low pressure safety injection (LPSI) pump and refueling water storage tank (RWST) & discharge valves to the reactor vessel from high pressure safety injection pump (EIHP) and high pressure recirculation (HPR).
- B Train LPSI pumps, suction & discharge valves from the RWST and the containment sump [support train to HPR]
B Train component cooling water (CCW), a support train to HPR.
- Turbine-driven AFW pump steam inlet valve (train B power).
- B Train emergency diesel generator (EDG), emergency AC system (EAC).
Division 1B AC power
Division 1B 125VDC power ACP Room
Train A MDAFW pump.
AFWTDP steam inlet valve and flow control valves (recovered, see below).
- Although there are energetic 6.9kV switchgear and bus ducts in the switchgear room, there is greater than 50 feet separation between the closest 6.9kV bus duct and the fire barrier for the ACP room (see Figure 1).
Recovery of AFW Turbine-Driven (TDAFW) pump In order to operate the TDAFW pump with the loss of alternating current (AC) power and direct current (DC) control, the discharge SG motor-operated valve (MOV) must be opened and the flow control air-operated valve (AOV) fails full ope The flow control has been set via speed control and local control change to speed to speed control, can be used to throttle the flo SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE Analysis Results
Importance Base Case For the base case, the fire is assumed to be contained within the Switchgear Room B (see Fig. The risk significance of train B equipment and the TDAFW pump being unavailable for automatic initiation is determined by performing an conditional assessment using the 3i model for Shearon Harri For this case, the transient initiating event frequency replaced by the product of the Switchgear Room B initiating fire frequency and the probability of nonsuppressio For this case, current probability of the base events that are assumed failed (TRUE or FALSE, as applicable) are used in the analysi This method is outlined in NUREG/CR-6544, Development of a Methodology for Analyzing Precursors to Earthquake-Initiated or Fire-Initiated Accident Sequences, Section 3.7 (Ref. 2). The conditional core damage probability (CCDP) is 8.5x10-7.
Current Case For the current case, the fire is assumed to propagate to the ACP Room with a probability of nonsuppression of 0.5 (see Modeling Assumptions below for details). In addition to the equipment failed in the base case, the AFW MDP A pump is failed and the other steam inlet valve and flow control valves to the AFWTDP are failed, but recovere The current case CCDP is 6.5x10-6.
Increase in Core Damage Probability The increase in core damage probability ( CDP) is the difference between the current case and the base case: 6.5x10-6 - 8.5x 0-7 = 5.6x10-6.
The Accident Sequence Precursor (ASP) Program acceptance threshold is an importance ( CDP) of 1x 0-6.
Dominant sequence (Current Case)
The Fire Event tree includes the transfer of Fire initiating event to Transient Sequence 21 (see Figures 2).
TRANS (Sequence 21)
The events and important component failures in TRANS Sequence 21 include:
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE
-
Reactor trips successfully during transient
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Failure of AFW system
- Failure of main feedwater system during transient
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Failure to provide bleed portion of feed and bleed
Results tables
-
Table 1 provides the importance values for some dominant sequences.
Table 2a provides the event tree sequence logic for the dominant sequences.
Table 2b defines the nomenclature used in Table 2a.
Table 3 provides the conditional cut sets for the dominant sequence
Table 4 provides the definitions and probabilities for the modified and dominant basic events Modeling Assumptions
Assessment summary Condition duration. Due to the fire barrier being degraded for more than one year, a maximum time of one year is normally the duration in a conditional assessmen However, this analysis was made as an initiating event assessment, with degraded fire barriers for 1 year, with a postulated fire occurring in Switchgear Room B and propagating to the adjacent Auxiliary Control Panel (ACP) roo
SPAR model used in the analysis The Revision 3i of the Harris Standardized Plant Analysis Risk (SPAR) Model (Ref. 2) was used for this assessmen The SPAR Revision 3i model includes event trees for transients (TRANS), Loss of Offsite Power (LOOP), steam generator tube rupture (SGTR), and small Loss of coolant accident (SLOCA). For this conditional assessment all initiating events, other than TRANS are not applicabl Since the fire is not caused by these initiating events, therefore, these frequencies are set to zer The transient initiating event (IE-TRANS) frequency is replaced (see below for details of fire-Induced analysis considerations).
Recovery of TDAFW Pump Recovery of the TDAFW pump is assumed for this analysis (see fault tree, Fig. 3A).
Fire-induced analysis methodology The fire-induced analysis is based on NUREG/CR-6544 (Ref. 3), For this analysis, all equipment in Switchgear Room B (the fire zone) is assumed failed and the fire propagates
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE to the ACP room and causes failure to certain train A equipment cable The product of the initiating fire frequency and the probability of nonsuppression replaces the transient event frequency in the conditional assessmen Initiating Fire Frequency - The initiating fire frequency (Fi) was developed from NRC Report RES/OERAB/S02-01 power operation fire event data for severe fires (fires with duration greater than 5 minutes and were not self-extinguished) in the switchgear room during the 1986-1999 period (Ref. 4), with updated data for 2000-200 The Switchgear Room B fire frequency is 3.2E-3, based on:
Fi = (No. Of Severe Fires + Jeffreys Prior)
(No. Of Switchgear Rooms x No. Power Operation Reactor-Years)
Fi = (8 + 0.5) = 3.2E-3 (2 x 1311)
-
Probability of nonsuppression Fire Barrie The licensees position that the fire barrier rating of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 48 minutes was sufficient to meet the intent of the Appendix R requirement for a 3-hour fire barrier was challenged by NRC staff because the testing documentation was not substantiated in an exemption request or provided for NRC revie However, a best estimate of a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> fire rating was considered conservative for the fire analysis, based on discussion with NRC fire protection staff (NRR/DSSA/SPLB) and used in this analysis.
Manual Fire Suppressio Due to the several Condition Reports written concerning equipment and performance, the fire brigade was considered below optimum in performance. An earlier NRC Inspection Report documented NRC inspector observations that no fire drills were scheduled in the switchgear rooms and, no fire drill had been conducted in these areas for at least seven year For this analysis, the lesser trained fire brigade was assumed to be on station in 30 minutes ( 10 minutes later than nominal). For the current case, with an assumed one-hour fire barrier, this leaves 30 minutes for suppression of the fir and a probability of nonsuppression = 5E-1, based on the EPRI Fire Guid For the base case, the fire, does not propagate to the ACP room and the probability of nonsuppression is 1.0 within the Switchgear Room.
Modifications to fault trees For the current case, the recovery of the AFWTDP is added by base event AFW-XHE-XE-TDP1X (See Figure 3A).
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE For the current case, the probability of failure of AFWMDPA by propagation to the ACP Room is added by the base event FIRE-PROPAGATION-ACP (see Figure 3B),
Basic event probability changes Table 4 provides the basic events for the current case that were modified to reflect the event condition being analyze The bases for these changes are as follows:
Probability changes (Current Case)
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Division 1B AC Power 6.9kV Bus Fails (ACP-BAC-LP-1B). This value was set to TRUE..
-
AFW Motor Driven Pump 1B Fails to Run (AFW-MDP-FR-1B). The value was set to TRUE.
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AFW Motor Driven Pump 1B Fails to Start (AFW-MDP-FS-1B). The value was set to TRUE.
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Operator fails to Recover AFW Turbine Driven Pump (AFW-TDP-XHE-TDP1X).
This value was set to 4.0E-02.
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Operator Fails to Recover Motor-Driven Pump B (AFW-XHE-XL-MDPFSB). This value is set to TRUE.
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CCW MDP 1B Fails to Run (CCW-MDP-FR-1B). This value was set to TRUE.
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CCW MDP 1B Fails to Start (CCW-MDP-FS-1B). This value was set to TRUE.
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Division 1B 125VDC Bus DP-1B Fails (DCP-BDC-LP-1B). This value is TRUE.
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Diesel Generator B Fails to Run (EPS-DGN-FR-1B). The value was set to TRUE.
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Diesel Generator B Fails to Start (EPS-DGN-FS-1B). This value was set to TRU ESW MDP 1 B Fails to Run (ESW-MDP-FR-1B). This value was set to TRUE.
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ESW MDP 1 B Fails to Start (ESW-MDP-FS-1B). This value was set to TRUE.
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Probability that the Fire Propagates to the ACP (FIRE-PROPAGATION-ACP). This value was set to 5.0E-01.
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HPI MDP 1B Fails to Run (HPI-MDP-FR-1B). This value was set to TRUE.
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HPI MDP 1B Fails to Start (HPI-MDP-FS-1B). This value was set to TRUE.
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RHR MDP 1B Fails to Run (RHR-MDP-FR-1B). This value was set to TRUE.
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RHR MDP 1B Fails to Start (RHR-MDP-FS-1B). This value was set to TRUE.
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Transient Initiating Event (IE-TRANS). This value was set to the fire frequency value, 3.2E-3.
All other initiating events were set to zero.
Model update The SPAR model for Harris was not updated.
Differences with Licensees individual plant examination for external events (IPEEE)
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE The licensees IPEEE (Ref. 5.) assumed that a switchgear room fire would cause failure of all equipment within the room and resulted in a CDF for this scenario (same as base case) of 2.8E-The IPEEE assumed no barrier degradation and no propagation, while this analysis assumed propagation in the current cas This ASP analysis does not include external event References 1.
EA-00-022/EA-01-310, NRC Inspection Report 50-400/2000-09, dated 12/18/2001 K. Knudsen, et al., Standardized Plant Analysis Risk Model for Shearon Harris (ASP PWR B), Revision 31, Idaho National Engineering and Environmental Laboratory, October 2000.
3.
R. J. Budnitz, et al., Development of a Methodology for Analyzing Precursors to Earthquake-Induced and Fire-Induced Accident Sequences, NUREG/CR-6544, U.S.
Nuclear Regulatory Commission, Washington, DC, April 199.
J. R. Houghton and D. M. Rasmuson, NRC Report RES/OERAB/S02-01, Fire Events Update of U.S. Operating Experience. 1986-1999, U. S. Nuclear Regulatory Commission, Washington DC, January 2002.
5.
Carolina Power & Light letter to USNRC, Serial: HNP -95-01, Individual Plant Examination for External Events Submittal - Final Report, June 1995
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE Table Conditional Probabilities Associated with Highest Probability Sequences (Importance)
Event tree name Sequence Number Conditional core damage probability (CCDP)
TRANS
3.3E-006 Total (all sequences)
6.5E-006
Table 2 Event Tree Sequence Logic for Dominant Sequence Event tree name Sequence no.
Logic (/ denotes success; see Table 4b for top event names)
TRANS
/RT, AFW, MFW-T, BLEED Table 2 Definitions of Fault Trees Listed in Table 2a
/RT REACTOR Trips Successfully During Transient AFW No or insufficient AFW flow MFW-T Failure of Main Feedwater System During Transient BLEED Failure to provide bleed portion of fill and bleed Table Conditional cut sets for Dominant TRANS Sequence Event Tree: TRANS, Sequence 21 CCDP Percent contribution Minimal cut sets1 1.1E-006 3 AFW-MDP-CF-AB MFW-SYS-UNAVAIL MFW-XHE-NOREC FIRE-PROPAGATION-ACP AFW-XHE-XL-TDPFR AFW-TDP-FR-1X 9.0E-007 27.6 AFW-MDP-CF-AB MFW-SYS-TRIP FIRE-PROPAGATION-ACP AFW-XHE-XL-TDPFR MFW-XHE-ERROR MFW-SYS-UNAVAIL 3.3E-006 Total2 Notes:
1.
See Table 4 for definitions and probabilities for the basic events.
2.
Total CCDP includes all cut sets (including those not shown in this table).
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
SENSITIVE - NOT FOR PUBLIC DISCLOSURE Table Definitions and probabilities for modified and dominant basic events Event name Description Probabil ity/Freq uency Modifi ed ACP-BAC-LP-1A DIVISION 1B AC POWER 6.9KV BUS FAILURE PROB.
TRUE YES3 AFW-MDP-FR-1B AFW MDP 1B FAILS TO RUN FAILURE PROBABILITY TRUE YES1 AFW-MDP-FS-1B AFW MDP 1B FAILS TO START FAILURE PROBABILITY TRUE YES1 AFW-XHE-XE-TDP1X OPERATOR FAILS TO RECOVER AFW TDP 4.0E-02 YES2 AFW-xHE-XE-MDPFSB OPERATOR FAILS TO RECOVER AFW MDP B TRUE YES1 CCW-MDP-FR-1B CCW MDP 1B FAILS TO RUN TRUE YES1 CCW-MDP-FS-1B CCW MDP 1B FAILS TO START TRUE YES1 DCP-BDC-LP-1B DIVISION 1B 125VDC BUS DP-1B FAILS TRUE YES1 EPS-DGN-FR-1B DIESEL GENERATOR B FAILS TO RUN TRUE YES1 EPS-DGN-FS-1B DIESEL GENERATOR B FAILS TO START TRUE YES1 ESW-MDP-FR-1B ESW MDP 1B FAILS TO RUN TRUE YES1 ESW-MDP-FS-1B ESW MDP 1B FAILS TO START TRUE YES1 FIRE-PROPAGATION-ACP PROBABILITY THAT FIRE PROPAGATES TO ACP ROOM 5.0E-01 YES3 HPI-MDP-FR-1B HPI MDP 1B FAILS TO RUN TRUE YES1 HPI-MDP-FS-1B HPI MDP 1B FAILS TO START TRUE YES1 RHR-MDP-FR-1B RHR MDP 1B FAILS TO RUN TRUE YES1 RHR-MDP-FS-1B RHR MDP 1B FAILS TO START TRUE YES1 IE-LDCA Loss of DC POWER BUS 1A INITIATING EVENT 0.00 YES4 IE-LLOCA LARGE LOSS OF COOLANT ACCIDENT INITIAT. EVENT 0.00 YES4 IE-LOCCW LOSS OF COMPONENT COOLING WATER INITIAT. EVENT 0.00 YES4 IE-LOESW LOSS OF EMERGENCY COOLING WATER INITIAT. EVENT 0.00 YES4 IE-LOOP LOSS OF OFFSITE POWER INITIATING EVENT 0.00 YES4 IE-MLOCA MEDIUM LOSS OF COOLANT ACCIDENT INITIAT. EVENT 0.00 YES4 IE-RHR-DIS-V RHR DISCHARGE ISLOCA OCCURS 0.00 YES4 IE-RHR-HL-V RHR HOT LEG ISLOCA INITIATING EVENT 0.00 YES4 IE-RHR-SUC-V RHR SUCTION ISLOCA INITIATING EVENT 0.00 YES4 IE-SGTR STEAM GENERATOR TUBE RUPTURE INITIATING EVENT 0.00 YES4 IE-SI-CLDIS-V SI COLD LEG ISLOCA OCCURS 0.00 YES4 IE-SI-HLDIS-V SI HOT LEG ISLOCA OCCURS 0.00 YES4 IE-SLOCA SMALL LOSS OF COOLANT ACCIDENT INITIATING EVENT 0.00 YES4 IE-TRANS TRANSIENT INITIATING EVENT (FIRE)
3.2E-03 YES5 AFW-MDP-CF-AB CCF FAILURES OF AFW MDPS 9.9E-02 NO6 MFW-SYS-TRIP MAIN FEEDWATER SYSTEM UNAVAILABLE GIVEN REACTOR TRIPS 8.0E-01 NO6
SENSITIVE - NOT FOR PUBLIC DISCLOSURIR 50-400/00-09 Event name Description Probabil ity/Freq uency Modifi ed
SENSITIVE - NOT FOR PUBLIC DISCLOSURE
MFW-SYS-UNAVAIL MAIN FEEDWATER SYTEM UNAVAILABLE GIVEN AN ATWS EVENT 2.0e-01 NO6 MFW-XHE-NOREC OPERATOR FAILS TO RECOVER MAIN FEEDWATER 2.0E-01 NO6 MFW-XHE-ERROR OPERATOR FAILS TO RESTORE MAIN FEEDWATER FLOW 4.0E-02 NO6 Notes:
1.
Base events set to TRUE reflect the failed position, if applicable, for this analysis.
2.
The probability was determined from human factors work sheets.
3.
The probability for nonsuppression (cuurent case) was derived from the time for the fire brigade on station and the time available to suppress the fire given a one-hour fire barrier.
4.
Initiating event frequencies set to zero for this analysis.
5.
Transient initiating event frequency revised to reflect the product of the initiating fire frequency and the probability of nonsuppression.
6.
Identifies dominant sequence cutset base events that were not revise Figure1 Simplified Equipment Layout Switchgear Room B and ACP room 11 SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09 Figure removed during SUNSI review
HPR HIGH PRESSURE RECIRC RHR RESIDUAL HEAT REMOVAL COOLDOWN RCS COOLDOWN SGCOOL SECONDARY COOLING RECOVERED HPI HIGH PRESSURE INJECTION BLEED BLEED PORTION OF F&B COOLING PORV-RES PORVs CLOSE PORV NO PORVs OPEN MFW-T MAIN FEEDWATER DURING TRANSIENT AFW AUXILIARY FEEDWATER RT REACTOR TRIP IE-TRANS TRANSIENT
END-STATE F
OK
OK
OK
OK
CD
OK
CD
CD
OK 10 OK 11 OK 12 OK 13 CD 14 OK 15 CD 16 CD 17 OK 18 OK 19 CD 20 CD 21 CD 22 T ATWS PORV-1 Figure 2 Trans Sequence 21 12 SENSITIVE - NOT FOR PUBLIC DISCLOSURE SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
AFW-MDPA AFW-MDP-FS-1A AFW-MDP-FR-1A AFW-MDP-TM-1A AFW-XHE-XR-MDP1A DIV-A-DC DIV-A-AC AFW-CKV-CC-36 AFW-CKV-CC-16 AFW-HDV-OC-19 AFW-MDP-CF-AB AFW-MDPA-FR-F AFW-XHE-XL-MDPFRA AFW-MDPA-FS-F AFW-XHE-XL-MDPFSA AFW-MDPA-1 FIRE-PROPAGATION-ACP DIVISION 1A AC POWER F AILS AFW MDP TRAIN A FAILURES DIVISION 1A DC POWER BUS FAILS AFW MDP 1A DISCH HYDRAULIC VALVE 1AF-19 FAILS TO REMAIN OPEN AFW MDP 1A DISCHARGE CHECK VALVE 1AF-16 FAILS TO OPEN AFW MDP 1A SUCTION CHECK VALVE 1CE-36 FAILS TO OPEN OP FAILS TO RESTORE AFW MDP 1A AFTER T&M AFW MDP 1A UNAVAILABLE DUE TO TEST AND MAINTENANCE AFW MDP 1A FAILS TO RUN AFW MDP 1A FAILS TO START CCF FAILURE OF AFW MDPs FAILURE TO ST ART AFW MOTOR DRIVEN PUMP 1A OPERATOR FAILS TO RECOVER AFW MDP 1A (FAILS TO START)
FAILURE OF AFW MOTOR DRIVEN PUMP 1A TO RUN OPERATOR FAILS TO RECOVER AFW MDP 1A (FAILS TO RUN)
AFW MDP TRAIN A FAILURES PROBABILITY THAT FIRE PROPAGATE TO ACP Figure 3 A 13 SENSITIVE - NOT FOR PUBLIC DISCLOSURE SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09
AFW-TDPX AFW-TDP-FS-1X AFW-TDP-TM-1X AFW-XHE-XR-TDP1X AFW-TDP-FR-1X AFW-CKV-CC-56 AFW-CKV-CC-117 AFW-HDV-CC-G AFW-HDV-OC-T DIV-B-DC AFW-TDPX-FS-F AFW-XHE-XL-TDPFS AFW-TDPX-FR-F AFW-XHE-XL-TDPFR AFW-XHE-XE-TDP1X AFW-TDPX-1 AFW TDP 1X FAILURES AFW TDP 1X FAILS TO RUN AFW TDP 1X THROTTLE VALVE 1MS-T FAILS TO REMAIN OPEN AFW TDP 1X STEAM SUPPLY HYDRAULIC VALVE 1MS-G FAILS AFW TDP 1X DISCHARGE CHECK VALVE 1AF-117 FAILS TO OPEN AFW TDP 1X SUCTION CHECK VALVE 1CE-56 FAILS TO OPEN OP FAILS TO RESTORE AFW TDP 1X AFTER T&M AFW TDP 1X UNAVAILABLE DUE TO TEST AND MAINTENANCE AFW TDP 1X FAILS TO START DIVISION 1B DC POWER FAILS FAILURE TO START AFW TURBINE DRIVEN PUMP OPERATOR FAILS TO RECOVER AFW TDP (FAILS TO START)
FAILURE OF AFW TURBINE DRIVEN PUMP TO RUN OPERATOR FAILS TO RECOVER AFW TDP (FAILS TO RUN)
OP FAILS TO RECOVER AFW TDP 1X RECOVERY OF TDP Figure 3B 14 SENSITIVE - NOT FOR PUBLIC DISCLOSURE SENSITIVE - NOT FOR PUBLIC DISCLOSURE IR 50-400/00-09