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
)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 50-255/01-08
Condition Summary Description. 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 ineffective. 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 response. The cable spreading room contains electrical cabinets and cabling for safety related divisions. The electrical cabinets are arranged primarily in five rows that run most of the length of the room. The electrical cabinets contain transformers, inverters, battery chargers, and instrumentation. The cabinet rows are separated by distance for the safety-related trains. Two Load Centers, five motor control centers (MCCs) and two 125Vdc buses are located in the room. The cabling is primarily in raceway trays suspended in the overhead. These trays are stacked four to five trays high above the electrical cabinets. The cable spreading room contains a wet pipe sprinkler system for automatic suppression. 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 trays. 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 water. 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.
Duration. 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 assessment. 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.
Cause. 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 opportunity. 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:
- Power Conversion System (PCS): Condensate pumps, turbine-driven main feedwater pumps, atmospheric dump valves (ADVs), and turbine bypass valves (TBVs).
- Auxiliary Feedwater (AFW) motor-driven AFW pump P-8 High Pressure Safety Injection (HPI) pump P-66 Pressurizer Power Operated Relief Valve (PORV) PRV-104 Containment Spray (CS) pumps P-54 Containment Air Cooler (CAC) fan VHX- Service Water system (SWS) pump P-7 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 room.
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 frequency. The current probability of the base events that are assumed failed (TRUE or FALSE, as applicable)
are used in the analysis. 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:
- Successful Reactor Trips during transient,
- Failure of main feedwater system during transient,
- 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 assessment. 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 zero. 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 recovery. 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 2001. 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)
- 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 brigade. 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 probability. 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 analyzed. Other basic events that were included in the dominant cutsets, but not revised are also included in Table 4.
References 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). 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. 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 1998. 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 SENSITIVE - NOT FOR PUBLIC DISCLOSURE
Table 1. Conditional probabilities associated with the highest probability sequences Conditional core Core damage Event tree Sequence damage probability probability Importance name n (CCDP) (CDP) (CCDP - CDP)1 TRANS 27 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 2a. Event tree sequence logic for dominant sequence Event tree Sequence Logic name n (/ denotes success; see Table 2b for top event names)
TRANS 27 /RT, MFW-T, AFW, BLEED Table 2b. 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 3. Conditional cut sets for LDC11, Sequence 16 and LOOP Sequence221 CCDP Percent Minimal cut sets1 contribution Event Tree: TRANS, Sequence 27 7.9E-007 5 AFW-MDP-CF-START AFW-TDP-FR-8B 2.2E-007 1 AFW-MDP-CF-START AFW-TDP-TM-8B 1.9E-007 1 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 4. Definitions and probabilities for modified and dominant basic events Probability/Fre Event name Description Modified quency AFW-MDP-CF-START COMMON CAUSE FAILURE OF AFW MOTOR-DRIVEN PUMPS TO 2.8E-02 YES1 START 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) .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
Probability/Fre Event name Description Modified quency IE-SLOCA SMALL LOSS OF COOLANT ACCIDENT INITIATING EVENT 0.0+00 YES2 IE-TRANS TRANSIENT INITIATING EVENT 1.0E-03 YES3 Notes: Base events set to TRUE reflect the failed position for this analysis. Initiating event frequencies set to zero for this analysis. Transient initiating event frequency revised to reflect the product of the initiating fire frequency and the probability of nonsuppression.
4 Base event updates based on NRC/RES human factors analyses update SENSITIVE - NOT FOR PUBLIC DISCLOSURE
FIRE REACTOR MAIN AUXILIARY NO PORVs BLEED HIG H SECONDARY SECONDARY DECAY CONTAINMENT HIG H TRANSIENT TRIP F EEDWATER FEEDWATER PORVs RESEAT PORTION PRESSURE COOLING SIDE RCS HEAT COOLING PRESSURE SYSTEM SYSTEM OPEN OF F&B INJ ECTIO N RECO VERED COOLDO WN REMOVAL RECIRCULATIO N COO LING IE-FIRE RT MF W-T AF W PORV PORV-RES BLEED HPI SGCOOL COOLDOWN DH R CSR HPR # END -ST 1 OK 2 OK 3 OK 4 OK 5 CD 6 CD 7 OK 8 CD 9 CD 10 CD 11 O K 12 O K 13 O K 14 O K 15 CD 16 CD 17 O K 18 CD 19 CD 20 CD 21 O K 22 O K 23 O K 24 CD 25 CD 26 CD 27 CD 28 TATWS Figure 1 Fire Transient Sequence 27
FAILURE OF REMORTE SHUTDOWN PANEL RSP-F OPERATOR FAILS TO SHUDOWN PANEL SHUTDOWN REACTOR FAILURE USING RSP RPS-XHE-XL-RPS RPS-RSP-DS Figure 2 - Fault Tree - Failure of Remote Shutdown Panel
HPI M DP P-66B TRAIN FAILS HPI-MDPB HPI M DP P-66B HPI M DP P-66B HPI MDP P-66B HPI M DP P-66B CCF OF HPI ESF W EST ROOM FAI LS TO UNAVAILABLE SUCT ION CHECK VALVE DISCHARGE CHECK M DP SUCTION CO OLING F AILS RUN DUE TO T &M 3168 FAILS VALVE 3177 FAILS CHECK VALVES TRANSFER HPI-MDP-FR-P66B HPI-MDP-TM-P66B HPI-CKV-CC-P66BS HPI-CKV-CC-P66BD HPI-CKV-CF-SUCT HVAC-ESFW DIVISION 11A DIVI SION 1C O PERATOR F AILS COMMON CAUSE COMM ON CAUSE FAILURE OF DC POWER AC POWER TO RESTORE HPI F AI LURE OF HPI FAILURE OF HPI CO MPONENT COOLING F AILS FAILS MDP P-66B AFTER T&M MDPs DISCHARGE CKVs W ATER DIV-11A-DC DIV-C-AC HPI-XHE-XR-P66B HPI-MDP-CF-ALL HPI-CKV-CF-MDPDIS CCW HPI MDP P-66B FAILURE OF F AILS TO REMORT E SHUTDOWN START PANEL HPI-MDP-FS-P66B RSP-F Figure 3 - Fault Tree - HPI MDP P-66B Train Fails
FAILURE OF SW PUMP P-7C TO EDGs EPS-SWMPC AC POWER SERVICE WATER SWS MDP P-7C COMMON CAUSE FAILURE CCF OF SWS BUS 1D PUMP P-7C FAILS FAILS TO OF SERVICE WATER MDPs DISCHARGE FAILS TO RUN START PUMPS TO RUN CHECK VALVES TO OPEN ACP-BAC-LP-1D SWS-MDP-FR-P7C EPS-MDPCFS-L SWS-MDP-CF-RUN SW S-CKV-CF-DISCH FAILURE OF DC POWER SERVICE WATER FAILURE OF SWS CCF OF SWS REMORTE SHUTDOWN BUS 21 PUMP P-7C FAILS MDP P-7C DISCHARGE MDPs TO PANEL FAILS TO START CHECK VALVE START RSP-F DCP-BDC-LP-21 SWS-MDP-FS-P7C SWS-CKV-CC-MDPC SWS-MDP-CF-STRT Figure 4 - Failure of SW Pump P-7C EDG
AFW TURBINE DRIVEN PUMP 8B UNAVAILA BLE AFW-TDP8B FAILURE OF TURBINE A FW TDP 8B AFW TDP 8B FAILURE OF AFW DRIVE N PUMP 8B DISCHA RGE CHE CK UNAVA IL ABL E TDP 8B TO TO START VALVE 87 43 FAILS DUE TO T& M RUN AFW-TDP8B-STRT-F AFW-CKV-CC-P8BD AFW-TDP-TM-8B AFW-TDP8B-FR FAIL URE OF DC FAILURE O F AFW AFW TDP 8 B OPERATOR FA ILS TO POW ER TO START TDP 8B TO FAILS TO RE COVE R AFW TDP AFW TDP 8B S TA RT RUN (FAILS TO RUN)
AFW-TDP8B-STDC-F AFW-TDP8B-FS AFW-TDP-FR-8B AFW-XHE-XL-TDPFR FAILURE OF DIVERSE DIV IS ION 11C AFW MDP 8B OP ERA TOR FAILS TO FA ILURE OF START SYSTEM TO DC POW ER FAILS TO RECOVER A FW TDP REM ORTE SHUTDOWN START A FW TDP FAILS START (FAILS TO START) PANEL AFW-TDP8B-DSS-F DIV-11A-DC AFW-TDP-FS-8B AFW-XHE-XL-TDPFS RSP-F FAIL URE OF DIVERSE FAILURE OF DIV ERSE START SYS TE M S TA RT SYSTEM B ATTE RY BA TTERY CHARGER DCP-BAT-LP-DSS DCP-BCH-FC-DSS Figure 5 - AFW Turbine Driven Pump 8B Unavailable 12