IR 05000255/2001008
| ML20114E132 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/12/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Hunter C (301) 415-1394 | |
| References | |
| IR 2001008 | |
| Download: ML20114E132 (12) | |
Text
1
)LQDO Precursor Analysis Accident Sequence Precursor Program --- Office of Nuclear Regulatory Research Palisades Smoke detectors in cable spreading room not installed in accordance with code
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eptember 11, 2001
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50-255/01-08
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Condition Summary Descriptio Inspection report 50-255/01-08 (Ref. 1) indicated that the smoke detector in the northwest portion of the cable spreading room was not located and installed in accordance with the applicable National Fire Protection Association code, rendering it ineffectiv The detector was located near a ventilation exhaust that would draw smoke from a fire in equipment important to safety, delay smoke propagation to the detector, and result in delayed fire brigade respons The cable spreading room contains electrical cabinets and cabling for safety related division The electrical cabinets are arranged primarily in five rows that run most of the length of the roo The electrical cabinets contain transformers, inverters, battery chargers, and instrumentatio The cabinet rows are separated by distance for the safety-related train Two Load Centers, five motor control centers (MCCs) and two 125Vdc buses are located in the roo The cabling is primarily in raceway trays suspended in the overhea These trays are stacked four to five trays high above the electrical cabinet The cable spreading room contains a wet pipe sprinkler system for automatic suppressio However, because of the stacking of raceway trays and because of the number of cables in each tray, the sprinkler system could only be effective in extinguishing a fire in the upper cable tray The NRC Safety Evaluation Report (SER) allowed manual suppression capability as adequate means to suppress fires in lower trays that may be shielded from sprinkler system wate Essentially, the SER hinged the adequacy of fire protection in the area on the rapid detection of the fire and subsequent manual suppression (fire brigade) efforts.
Duratio Due to the fire detection capability being ineffective for more than one year, the maximum time of one year is used for the duration in a conditional assessmen However, this analysis was made as an initiating event assessment, with ineffective fire detection for 1 year, and a postulated fire occurring in the cable spreading room.
Caus The cause of this event is a design deficiency in the ineffective location of the smoke detector in the northwest portion of the cable spreading room adjacent to exhaust ventilation.
The proximity of the detector to the exhaust would delay the detection response.
Recovery opportunit A postulated fire in fire cable spreading room is assumed to cause loss of one train of safety-related equipment and control cables, but not to propagate to the other train. The following equipment is assumed to fail with no recovery:
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Power Conversion System (PCS): Condensate pumps, turbine-driven main feedwater pumps, atmospheric dump valves (ADVs), and turbine bypass valves (TBVs).
SENSITIVE - NOT FOR PUBLIC DISCLOSURE
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Auxiliary Feedwater (AFW) motor-driven AFW pump P-8A.
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High Pressure Safety Injection (HPI) pump P-66A.
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Pressurizer Power Operated Relief Valve (PORV) PRV-1042.
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Containment Spray (CS) pumps P-54A.
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Containment Air Cooler (CAC) fan VHX-Service Water system (SWS) pump P-7A.
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Batter Chargers: two (#2 and #4).
Analysis Results
Assumptions For this analysis, the fire is assumed to fail train A safety-related equipment and all power conversion equipment within the cable spreading roo
Importance The risk significance of portions of equipment and cable trains is determined by performing an initiating event assessment using the Standardized Plant Analysis Risk (SPAR) Model for Palisades, Revision 3 (Ref. 2) with the transient initiating event frequency replaced by the cable spreading room initiating fire frequenc The 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. 3). For this analysis, loss of one train of safety-related equipment, the resulting importance [mean increase in core damage probability (mean CDP) is 1.4 x 10-6). The Accident Sequence Precursor (ASP) Program acceptance threshold is an importance of 1 x 10-6.
Uncertainty The uncertainty about the mean is: 5% bound, 1.3 x 10-7 and 95% bound, 4.9 x 10-6.
Dominant sequence The events and important component failures in (FIRE TRANSIENT)TRANS Sequence 27 include:
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Successful Reactor Trips during transient,
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Failure of main feedwater system during transient,
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Failure of auxiliary feedwater, and
- Loss of bleed portion of feed and bleed cooling, resulting in core damag SENSITIVE - NOT FOR PUBLIC DISCLOSURE Modeling Assumptions
Assessment summary SPAR model used in the analysis The Revision 3 SPAR model (Ref. 2) was used for this assessmen For this fire-induced initiating event analysis none of these initiating events, except TRANS, are applicable to this analysis, as the postulated fire is not caused by these initiating events and, therefore, these frequencies are set to zer The transient initiating event (IE-TRANS) frequency is replaced by the fire frequency for the cable spreading room (see below for details of fire-Induced analysis considerations).
Fire-induced analysis methodology The fire-induced analysis is based on NUREG/CR-6544 (Ref. 3). For this analysis train A and C equipment and cables in the cable spreading room are assumed failed with no recover The product of the initiating fire frequency and the probability of nonsuppression replaces the transient event frequency in the initiating event 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 cable spreading room during the 1986-1999 period (Ref. 4), with fire event updates through 200 For the cable spreading room fire zone: that included train A and train C equipment, the fire frequency is 1.0E-3, based on:
Fi = (No. Of Severe Fires + Jeffreys Prior)
(No. pf cable spreading room fire zones x No. Power Operation Reactor-Years)
Fi = (2 + 0.5) = 1.0E-3 (2 x 1258)
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Probability of nonsuppression For this analysis, the fire is assumed to cause failure of one train of safety-related equipment due to the incorrect location of the smoke detector near the exhaust ventilation and the limited coverage of the water sprinklers to only the top trays of the multi-level cable trays, resulting in a delay of the assumed time of response by the fire brigad Since all equipment in the train is assumed failed, the probability of nonsuppression = 1.0.
Initiating event frequency changes For this analysis, the transient initiating event frequency (IE-TRANS) was replaced by the product of the initiating fire frequency for the cable spreading room and the probability of nonsuppression (1.0E-3 x 1.0 = 1.0E-3) as the current probabilit All other initiating event frequencies were set to zer SENSITIVE - NOT FOR PUBLIC DISCLOSURE
Basic event probability changes Table 4 provides the basic events that were modified to reflect the condition being analyze Other basic events that were included in the dominant cutsets, but not revised are also included in Table References 1.
EA-01-223, dated September 11, 2001, Palisades Triennial Fire Protection Baseline Inspection - NRC Inspection Report 50-255/01-08 and Preliminary White Finding (ADAMS Assession No. ML012560096).
2.
James K. Knudsen and Scott T. Beck, Standardized Plant Analysis Risk Model for Palisades (ASP PWR G), Revision 3, Idaho National Engineering and Environmental Laboratory, April 2002.
3.
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 200 Table Conditional probabilities associated with the highest probability sequences Event tree name Sequence no.
Conditional core damage probability (CCDP)
Core damage probability (CDP)
Importance (CCDP - CDP)1 TRANS
1.4E-006 Negligible 1.4E-006 Total (all sequences)2 Notes:
1. The importance value is essentially the same as the CCDP, because the CDP value is negligible.
2. Total CCDP and CDP includes all sequences (including those not shown in this table).
Table 2 Event tree sequence logic for dominant sequence Event tree name Sequence no.
Logic (/ denotes success; see Table 2b for top event names)
TRANS
/RT, MFW-T, AFW, BLEED Table 2 Definitions of fault trees listed in Table 2a
/RT Reactor trips successfully during transient MFW-T Failure of main feedwater system during transient AFW No or insufficient AFW flow BLEED Failure to provide bleed portion of feed and bleed Table Conditional cut sets for LDC11, Sequence 16 and LOOP Sequence221 CCDP Percent contribution Minimal cut sets1 Event Tree: TRANS, Sequence 27 7.9E-007 5 AFW-MDP-CF-START AFW-TDP-FR-8B 2.2E-007 13.8 AFW-MDP-CF-START AFW-TDP-TM-8B 1.9E-007 13.9 AFW-MDP-CF-START AFW-TDP-FS-8B 1.4E-061 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).
Table Definitions and probabilities for modified and dominant basic events Event name Description Probability/Fre quency Modified AFW-MDP-CF-START COMMON CAUSE FAILURE OF AFW MOTOR-DRIVEN PUMPS TO START 2.8E-02 YES1 AFW-MDP-FS-8A AFW MOTOR-DRIVEN PUMP 8A FAILS TO START TRUE YES1 AFW-AOV-CF-SGS CCF OF STEAM GENERATOR DISCHARGE VALVES 2.4E-05 NO AFW-TDP-FR-8B AFW TDP 8B FAILS TO RUN 2.8E-02 NO AFW-TDP-FS-8B AFW TDP 8B FAILS TO START 6.8E-03 NO AFW-TDP-TM-8B AFW TDP 8B UNAVAILABLE DUE TO TEST & MAINTENANCE 7.8E-03 NO AFW-MDP-FR-8C AFW MDP 8C FAILS TO RUN 7.6E-04 NO AFW-MDP-FS-8C AFW MDP 8C FAILS TO START 3.3E-03 NO AFW-MDP-TH-8C AFW MDP 8C UNAVAILABLE DUE TO TEST & MAINTENANCE 1.1E-03 NO AFW-XHE-XL-MDPFR OPERATOR FAILS TO RECOVER AFW MDP (FAILS TO RUN)
7.5E-01 NO AFW-XHE-XL-MDPFS OPERATOR FAILS TO RECOVER AFW MDP (FAILS TO START)2.1 2.1E-01 NO CAC-FAN-FS-VHX-1 DBA RATED CAC FAN VHX-1 FAILS TO START TRUE YES1 CAC-FAN-FR-VHX-1 DBA RATED CAC FAN VHX-1 FAILS TO RUN TRUE YES1 CSS-MDP-FS-54A CONTAINMENT SPRAY MOTOR-DRIVEN PUMP 54A FAILS TO START TRUE YES1 DCP-BCH-FC-CHR2 BATTERY CHARGER #2 FAILS TRUE YES1 DCP-BCH-FC-CHR4 BATTERY CHARGER #4 FAILS TRUE YES1 HPI-MDP-FS-P66A HPI MOTOR-DRIVEN PUMP P-66A FAILS TO START TRUE YES1 LPI-MDP-FS-P67A LOW PRESSURE INJECTION PUMP P-67A FAILS TO START TRUE YES1 MFW-SYS-UNAVAIL MAIN FEEDWATER UNAVAILABLE GIVEN TRANS IS LOMFW TRUE YES1 MFW-TDP-FR-1A FAILURE OF MFW TDP 1A TRUE YES1 MFW-XHE-NOREC OPERATOR FAILS TO RECOVER (RESTORE) MAIN FEEDWATER TRUE YES1 PCS-ADV-CC-0779 STEAM GENERATOR A ADV CV-0779 FAILS TO OPEN TRUE YES1 PCS-ADV-CC-0780 STEAM GENERATOR A ADV CV-0780 FAILS TO OPEN TRUE YES1 PPR-SRV-CC-1 PORV 1 (1042) FAILS TO OPEN ON DEMAND TRUE YES1 SWS-MDP-FR-7A SERVICE WATER PUMP 7A FAILS TO RUN TRUE YES1 SWS-MDP-FS-7A SERVICE WATER PUMP 7A FAILS TO START TRUE YES1 SWS-XHE-XL-SWSYS OPERATOR FAILS TO RECOVER FROM LOSS OF SERVICE WATER 2.0E-02 YES1 RPS-XHE-ERROR OPERATOR FAILS TO DE-ENERGIZE MG SETS 2.0E-02 YES4 RPS-XHE-SCRAM OPERATOR FAILS TO MANUALLY TRIP THE REACTOR 5.0E-04 YES4 IE-DHR-SUC-V DECAY HEAT REMOVAL SUCTION ISOLATION INITIATING EVENT 0.0+00 YES2 IE-HPI1-DIS-V HPI TRAIN 1 DISCHARGE ISLOCA INITIATING EVENT 0.0+00 YES2 IE-HPI2-DIS-V HPI TRAIN 2 DISCHARGE ISLOCA INITIATING EVENT 0.0+00 YES2 IE-LLOCA LARGE LOSS OF COOLANT ACCIDENT INITIATING EVENT 0.0+00 YES2 IE-LOCCW LOSS OF COMPONENT COOLING WATER INITIATING EVENT 0.0+00 YES2 IE-LODC21 LOSS OF DC POWER INITIATING EVENT 0.0+00 YES2 IE-LOOP LOSS OF OFFSITE POWER INITIATING EVENT 0.0+00 YES2 IE-LOSW LOSS OF SERVICE WATER INITIATING EVENT 0.0+00 YES2 IE-LPI-DIS-V LPI DISCHARGE ISLOCA IE (BASED ON TESTING MOVs)
0.0+00 YES2 IE-MLOCA MEDIUM LOSS OF COOLANT ACCIDENT INITIATING EVENT 0.0+00 YES2 IE-SGTR STEAM GENERATOR TUBE RUPTURE INITIATING EVENT 0.0+00 YES2
Event name Description Probability/Fre quency Modified
SENSITIVE - NOT FOR PUBLIC DISCLOSURE IE-SLOCA SMALL LOSS OF COOLANT ACCIDENT INITIATING EVENT 0.0+00 YES2 IE-TRANS TRANSIENT INITIATING EVENT 1.0E-03 YES3 Notes:
5.
Base events set to TRUE reflect the failed position for this analysis.
6.
Initiating event frequencies set to zero for this analysis.
7.
Transient initiating event frequency revised to reflect the product of the initiating fire frequency and the probability of nonsuppression.
Base event updates based on NRC/RES human factors analyses update HPR HIGH PRESSURE RECIRCULATION CSR CONTAINMENT COOLING DHR DECAY HEAT REMOVAL COOLDOWN SECONDARY SIDE RCS COOLDOWN SGCOOL SECONDARY COOLING RECOVERED HPI HIGH PRESSURE INJECTION BLEED BLEED PORTION OF F&B COOLING PORV-RES PORVs RESEAT PORV NO PORVs OPEN AFW AUXILIARY FEEDWATER SYSTEM MFW-T MAIN FEEDWATER SYSTEM RT REACTOR TRIP IE-FIRE FIRE TRANSIENT
END-ST 1 OK 2 OK 3 OK 4 OK 5 CD 6 CD 7 OK 8 CD 9 CD 10 CD 11 OK 12 OK 13 OK 14 OK 15 CD 16 CD 17 OK 18 CD 19 CD 20 CD 21 OK 22 OK 23 OK 24 CD 25 CD 26 CD 27 CD 28 T ATWS Figure 1 Fire Transient Sequence 27
RSP-F RPS-XHE-XL-RPS RPS-RSP-DS FAILURE OF REMORTE SHUTDOWN PANEL OPERATOR FAILS TO SHUTDOWN REACTOR USING RSP SHUDOWN PANEL FAILURE
Figure 2 - Fault Tree - Failure of Remote Shutdown Panel
HPI-MDPB HPI-MDP-FS-P66B HPI-MDP-FR-P66B HPI-MDP-TM-P66B HPI-XHE-XR-P66B HPI-CKV-CC-P66BD HVAC-ESFW DIV-11A-DC DIV-C-AC HPI-MDP-CF-ALL HPI-CKV-CF-MDPDIS CCW HPI-CKV-CC-P66BS HPI-CKV-CF-SUCT TRANSFER RSP-F HPI MDP P-66B TRAIN FAILS HPI MDP P-66B FAILS TO START HPI MDP P-66B FAILS TO RUN DIVISION 11A DC POWER FAILS DIVISION 1C AC POWER FAILS HPI MDP P-66B UNAVAILABLE DUE TO T&M O PERATOR FAILS TO RESTORE HPI MDP P-66B AFTER T&M HPI MDP P-66B DISCHARGE CHECK VALVE 3177 FAILS FAILURE OF COMPONENT COOLING W ATER ESF W EST ROOM COOLING FAILS COMMON CAUSE FAILURE OF HPI MDPs COMMON CAUSE FAILURE OF HPI DISCHARGE CKVs HPI MDP P-66B SUCTION CHECK VALVE 3168 FAILS CCF OF HPI MDP SUCTION CHECK VALVES FAILURE OF REMORTE SHUTDOWN PANEL Figure 3 - Fault Tree - HPI MDP P-66B Train Fails
EPS-SWMPC ACP-BAC-LP-1D EPS-MDPCFS-L DCP-BDC-LP-21 SWS-MDP-FS-P7C SWS-CKV-CC-MDPC SWS-MDP-CF-STRT SWS-MDP-FR-P7C SWS-MDP-CF-RUN SW S-CKV-CF-DISCH RSP-F FAILURE OF SW PUMP P-7C TO EDGs AC POWER BUS 1D FAILS DC POWER BUS 21 FAILS SERVICE WATER PUMP P-7C FAILS TO RUN COMMON CAUSE FAILURE OF SERVICE WATER PUMPS TO RUN CCF OF SWS MDPs DISCHARGE CHECK VALVES TO OPEN SWS MDP P-7C FAILS TO START SERVICE WATER PUMP P-7C FAILS TO START FAILURE OF SWS MDP P-7C DISCHARGE CHECK VALVE CCF OF SWS MDPs TO START FAILURE OF REMORTE SHUTDOWN PANEL Figure 4 - Failure of SW Pump P-7C EDG
AFW-TDP8B DIV-11A-DC AFW-TDP8B-FS AFW-XHE-XL-TDPFS AFW-TDP-FS-8B AFW-TDP-TM-8B AFW-TDP8B-FR AFW-TDP-FR-8B AFW-XHE-XL-TDPFR AFW-TDP8B-STDC-F AFW-TDP8B-DSS-F AFW-TDP8B-STRT-F DCP-BAT-LP-DSS DCP-BCH-FC-DSS AFW-CKV-CC-P8BD RSP-F AFW TURBINE DRIVEN PUMP 8B UNAVAILABLE DIVISION 11C DC POW ER FAILS FAILURE O F AFW TDP 8B TO START AFW MDP 8B FAILS TO START OPERATOR FAILS TO RECOVER AFW TDP (FAILS TO START)
AFW TDP 8B UNAVAILABLE DUE TO T&M FAILURE OF AFW TDP 8B TO RUN AFW TDP 8B FAILS TO RUN OPERATOR FAILS TO RECOVER AFW TDP (FAILS TO RUN)
FAILURE OF TURBINE DRIVEN PUMP 8B TO START FAILURE OF DC POW ER TO START AFW TDP 8B FAILURE OF DIVERSE START SYSTEM TO START AFW TDP FAILURE OF DIVERSE START SYSTEM BATTERY FAILURE OF DIVERSE START SYSTEM BATTERY CHARGER AFW TDP 8B DISCHARGE CHECK VALVE 8743 FAILS FAILURE OF REMORTE SHUTDOWN PANEL Figure 5 - AFW Turbine Driven Pump 8B Unavailable