ML16183A139

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ASP Screening Analysis-Reject, April 2016 (LER: 325-2015-001-00)
ML16183A139
Person / Time
Site: Brunswick Duke Energy icon.png
Issue date: 04/01/2016
From: Chelliah E, Christopher Hunter
NRC/RES/DRA/PRB
To:
Chelliah E
References
IR 2015007, LER 15-001-00
Download: ML16183A139 (13)
v • d • e


Text

Precursor Screening Analysis - Reject Accident Sequence Precursor Program - Office of Nuclear Regulatory Research The operators found the High pressure coolant Brunswick Steam injection (HPCI) system to be inoperable during Electric Plant, Unit 1 a weekly TS-test due to a failure of the auxiliary oil pump.

Event Date: 02/12/2015 LER: 325-2015-001-00 IR: 05000325/2015007 Plant Type: GE, BWR-4 plant with Mark I containment Plant Operating Mode (Reactor Power Level): Mode 1 (100% Reactor Power)

Analyst: Reviewer: Contributors: BC Approved Date:

Erulappa Chelliah Christopher Hunter N/A 4/ /2016 Event Description.

At 1336 Eastern Standard Time, on February 12, 2015, the operators declared the High Pressure Coolant Injection (HPCI) System at Brunswick Steam Electric Plant (BSEP) Unit 1 to be inoperable due to an as-found failure of the HPCI auxiliary oil (AO) Pump.

During a technical specifications (TS)-required testing of the HPCI system, the operators started the HPCI-AO pump. The operators found a failure of the AO pump, including a HPCI system failure to start on test-demand. During the test, the HPCI system experienced a loss of discharge oil pressure.

The HPCI-AO pump provides hydraulic pressure required to open the HPCI-turbine stop valve and the HPCI turbine control valve during initial HPCI startup. A failure of the HPCI-AO pump prevents the HPCI system from performing its design safety function.

The HPCI system is an emergency core cooling system at BSEP Unit 1. The licensee reported this degraded condition, in a licensee event report (LER), in accordance with 10 CFR Part 50.73(a)(2)(v)(D), as an event or condition that could have prevented the fulfillment of the safety function of a system to mitigate an accident. (Reference-1)

After the as-found failure of the HPCI system, the operators realized that the HPCI-AO pump did not fail, and therefore, the HPCI system was successfully started during the last TS-test (2/5/2015).

Then, the operators safety-determined that, during the current TS-test, on 2/12/2015, the HPCI system failed to start due to a pre-existing failure of the HPCI-AO pump.

Therefore, the operators found the HPCI-system to be inoperable due to its unavailability at standby position for a condition period of 15-days (one test interval of 7 days + 8 days to provide a corrective action to fix the failed HPCI-AO pump). The licensee found a specific degraded condition period of the HPCI train to be from 2/5/2015 to 2/20/2015. Unit 1 was operating at power mode during this 15-days period.

Failure causes:

The licensee found the failure cause of the HPCI system inoperability to be a faulty magnetic motor contactor coil within the HPCI-turbine, auxiliary oil pump motor contactor. The licensee also determined a failure of the coil to be an equipment failure. Then, the licensee replaced the failed coil.

The operators returned the HPCI system to a functional state, on February 20, 2015.

1

Inspection findings:

Region II inspectors reviewed the LER information and other related information. Region II closed the LER [Reference-2].

Degraded condition-related failures:

The HPCI-AO pump was unavailable for a condition period of 15-days (02/05/2015 thru 02/20/2015).

Analysis Type. RES\DRA\PRB analyst conducted one condition risk analysis case [CRA-1 analysis case] in estimating increase in core damage probability [ICDP] due to an as-found inoperability of the HPCI system.

Analysis Rules. The ASP Program uses Significance Determination Process (SDP) result for degraded conditions when available. However, the ASP Program performs independent analyses for events where there are degraded conditions that exist simultaneously (i.e., are windowed within the same timeframe) when not explicitly assessed under the SDP. As such, an ASP analysis was performed for the conditions described in the referenced LERs.

Key Modeling Assumptions.

The CRA-1 analysis case found the inoperable condition-period of 15 days to be greater than the allowed outage time [AOT] of 14-days by the licensed TS. The CRA-1 analysis case estimated a condition period of 15 days, based on as-found 7-days inoperability period of the HPCI system and a subsequent 8-days period to fix the failed HPCI-AO pump.

1. BSEP Unit 1 did not automatically scram during the specific condition period [02/05/2015 thru 02/20/2015]. Also, the operators did not manually scram the Unit 1 reactor at power during this specific period of the HPCI system inoperability.
2. Neither the analyst nor the reviewer of RES\DRA\PRB identified any overlapping conditions and/or simultaneous failure conditions of other safety systems (other than the HPCI system) during the specific condition period of 15-days period.
3. The licensee would not have repaired or recovered the failed HPCI-AO pump in less than an 8-days period to mitigate a postulated transient or a LOCA event.

Logic model-changes to recent SPAR model of BSEP Unit 1.

Idaho National Laboratory published a recent plant probabilistic failures-model for Brunswick, Unit 1

[SPAR-Model No. 8.2, dated 07/29/2009].

Three fault trees of the HPCI system were reviewed with respect to the published HPCI system reliability study. CRA-1 analysis case found this SPAR model version to be adequate to conduct a condition risk analysis of the as-found HPCI inoperability (LER-325-2015-001).

Specifically, a new basic event, HE-HPCI-15D (A HOUSE EVENT TO TRIGEER A START OF INOPERABILITY), was created and was added to the top OR gate of the following fault trees:

- FAULT TREE, HCI

- FAULT TREE, HC1

- FAULT TREE, HCI-B Baseline value of new basic event, HE-HPCI-15D, was set to FALSE.

Basic Event Probability-changes.

2

Basic event, HE-HPCI-15D was set to TRUE trigger the start of the HPCI-inoperability condition for a period of 15-days. A degraded condition duration of 15 days was input to SAPHIRE-8 condition analysis option.

Rejection basis.

Analysis documented the results of a CRA of the HPCI train inoperability in Attachment-1 to this report:

Analysis estimated Increase in core damage probability of 6.36E-8 due to an as-found inoperable condition of the HPCI-AO pump for a specific period of 15-days (02/05/2015 thru 02/20/2015).

  • Analysis found contributing dominant sequences due to degraded condition-affected sequences of the grid-related loss of offsite power (LOOPGR) event tree.
  • Analysis estimated an increase in core damage probability of about 2.66E-8 due to the LOOPGR event tree.
  • Analysis found a condition-affected dominant sequence of the LOOPGR event tree, LOOPGR-
25. Analysis estimated an increase in core damage probability of about 2.44E-8 due to dominant sequence, LOOPGR-25.

In summary,

1. Under the CRA, the point estimate for the increase in core damage probability is 6.36x10-8 due to an as-found inoperable condition of the HPCI AO pump at power mode of the Brunswick Unit 1 reactor.

This point estimates is below 1x10-6 and therefore, the events described in LER-325-2015-001 does not meet ASP Program criteria to be defined as a precursor.

Therefore, the licensee-found inoperable condition of the HPCI system at Brunswick Steam Electric Plant Unit 1, on 02/12/2015, would not have resulted in a precursor event during the power operation-period of 15 days REFERENCES

1. Brunswick Steam Electric Plant Unit 1, High Pressure Coolant Injection (HPCI) System Inoperable due to Auxiliary Oil Pump Failure - Duke Energy, LER-325-2015-001-00, Event Date of February 12, 2015, dated April 10, 2015. ML15113A347.
2. U. S. Nuclear Regulatory Commission, Brunswick Steam Electric Plant, Unit 1 - NRC PROBLEM IDENTIFICATION AND RESOLUTION Inspection report, 05000325/2015007, DATED JULY 29, 2015.

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ATTACHMENT-1: SAPHIRE8 ANALYSIS REPORT- BRUNSWICK STEAM ELECTROC PLANT, UNIT 1, CONDITION RISK ANALYSIS OF LER-325-2015-001-00 Event Tree Dominant Results Only items contributing at least 1.0% to the total CCDP are displayed.

EVENT TREE CCDP CDP CDP DESCRIPTION LOOPGR 6.60E-8 3.94E-8 2.66E-8 BRUNSWICK 1 LOSS OF OFFSITE POWER - GRID RELATED LOIA 3.34E-8 1.49E-8 1.85E-8 BRUNSWICK 1 LOSS OF INSTRUMENT AIR SYSTEM LOOPWR 2.15E-8 1.45E-8 7.04E-9 BRUNSWICK 1 LOSS OF OFFSITE POWER - WEATHER LOOPSC 2.20E-8 1.59E-8 6.03E-9 BRUNSWICK 1 LOSS OF OFFSITE POWER - SWITCH YARD LODC1B2 1.05E-8 8.53E-9 1.96E-9 BRUNSWICK 1 LOSS OF DC BUS 1B2 LOAC-E1 2.93E-9 2.24E-9 6.88E-10 BRUNSWICK 1 LOSS OF AC BUS E1 Total 3.12E-7 2.48E-7 6.36E-8 Dominant Sequence Results Only items contributing at least 1.0% to the total CCDP are displayed.

EVENT TREE SEQUENCE CCDP CDP CDP FLAGSET DESCRIPTION LOOPGR 25 2.65E-8 2.07E-9 2.44E-8 ETF-LOOPGR /RPS, /EPS, /SRV, HPI, DEP LOIA 45 1.98E-8 1.55E-9 1.83E-8 ETF-LOIA /RPS, /SRV-O, /SRV, HPI, DEP LODC1B 32 1.47E-8 1.14E-9 1.35E-8 ETF-LODC1B /RPS, PCS, /SRV-O, /SRV, HPI,

/DEP, CDS, /LPI, SPC, SDC, CSS, PCSR, /CVS, LI LOOPWR 25 7.17E-9 5.61E-10 6.61E-9 ETF-LOOPWR /RPS, /EPS, /SRV, HPI, DEP LOOPSC 25 5.84E-9 4.81E-10 5.36E-9 ETF-LOOPSC /RPS, /EPS, /SRV, HPI, DEP LODC1B2 32 3.53E-9 2.69E-10 3.27E-9 ETF-LODC1B2 /RPS, PCS, /SRV-O, /SRV, HPI,

/DEP, CDS, /LPI, SPC, SDC, CSS, PCSR, /CVS, LI LOOPGR 28-35 3.08E-9 2.08E-10 2.87E-9 ETF-SBOGR /RPS, EPS, /SRV, /RPSL, RCI-B, HCI-B, OPR-30M, DGR-30M LODC1B 40 5.41E-9 3.06E-9 2.35E-9 ETF-LODC1B /RPS, PCS, /SRV-O, /SRV, HPI,

/DEP, CDS, LPI, VA LODC1B2 40 5.12E-9 3.03E-9 2.08E-9 ETF-LODC1B2 /RPS, PCS, /SRV-O, /SRV, HPI,

/DEP, CDS, LPI, VA LOOPWR 28-35 7.85E-10 4.21E-11 7.43E-10 ETF-SBOWR /RPS, EPS, /SRV, /RPSL, RCI-B, HCI-B, OPR-30M, DGR-30M LODC1B 41 1.43E-9 7.27E-10 6.99E-10 ETF-LODC1B /RPS, PCS, /SRV-O, /SRV, HPI, DEP LODC1B2 41 1.39E-9 6.92E-10 6.97E-10 ETF-LODC1B2 /RPS, PCS, /SRV-O, /SRV, HPI, DEP Total 3.12E-7 2.48E-7 6.36E-8 4

Referenced Fault Trees Fault Tree Description CDS CONDENSATE CSS CONTAINMENT SPRAY DEP MANUAL REACTOR DEPRESS DGR-30M DIESEL GENERATOR RECOVERYIN 30 MINS EPS EMERGENCY POWER HCI-B HPCI-SBO HPI HIGH PRESSURE INJECTION LI LONG-TERM LOW PRESS INJECTION LPI LOW PRESS COOLANT INJECTION (LCS or LPCI)

OPR-30M OFFSITE POWER RECOVERY IN 30 MINS PCS POWER CONVERSION SYSTEM PCSR POWER CONVERSION SYSTEM RECOVERY RCI-B RCIC-SBO SDC SHUTDOWN COOLING SPC SUPPRESSION POOL COOLING VA ALTERNATE LOW PRESS INJECTION 5

Cut Set Report - LOOPGR 25 Only items contributing at least 1% to the total are displayed.

  1. CASES PROB/FREQ TOTAL% CUT SET 6.44E-7 100 Displaying 43 Cut Sets. (43 Original) 1 C 3.96E-7 61.49 IE-LOOPGR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEGR,RCI-TDP-FR-TRAIN 2 C 1.09E-7 16.98 IE-LOOPGR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEGR,RCI-TDP-TM-TRAIN 3 C 6.48E-8 10.07 IE-LOOPGR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEGR,RCI-TDP-FS-TRAIN 4 C 2.99E-8 4.65 IE-LOOPGR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEGR,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 5 C 1.99E-8 3.09 IE-LOOPGR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEGR,RCI-MOV-FC-XFER,RCI-XHE-XL-XFER 6 C 9.98E-9 1.55 IE-LOOPGR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEGR,RCI-XHE-XO-ERROR 7 C 9.61E-9 1.49 IE-LOOPGR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEGR,RCI-MOV-CC-F013 Cut Set Report - LOIA 45 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 4.83E-7 100 Displaying 35 Cut Sets. (35 Original) 1 C 2.97E-7 61.52 IE-LOIA,ADS-XHE-XE-ADSBT,RCI-TDP-FR-TRAIN 2 C 8.20E-8 16.98 IE-LOIA,ADS-XHE-XE-ADSBT,RCI-TDP-TM-TRAIN 3 C 4.86E-8 10.07 IE-LOIA,ADS-XHE-XE-ADSBT,RCI-TDP-FS-TRAIN 4 C 2.25E-8 4.65 IE-LOIA,ADS-XHE-XE-ADSBT,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 5 C 1.49E-8 3.09 IE-LOIA,ADS-XHE-XE-ADSBT,RCI-MOV-FC-XFER,RCI-XHE-XL-XFER 6 C 7.49E-9 1.55 IE-LOIA,ADS-XHE-XE-ADSBT,RCI-XHE-XO-ERROR 7 C 7.21E-9 1.49 IE-LOIA,ADS-XHE-XE-ADSBT,RCI-MOV-CC-F013 Cut Set Report - LODC1B 32 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 3.57E-7 100 Displaying 65 Cut Sets. (65 Original) 1 C 2.44E-7 68.36 IE-TDC1B,DCP-XHE-XA-ALTDC1,NSW-MDP-FC-BRUN,NSW-MDP-TM-1A,PCS-XHE-XL-LODC1B 2 C 4.34E-8 12.16 IE-TDC1B,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B,RHR-SYS-TM-A 3 C 1.77E-8 4.97 IE-TDC1B,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B,RHR-MOV-CC-F007A 6
  1. CASES PROB/FREQ TOTAL% CUT SET 4 C 1.75E-8 4.91 IE-TDC1B,DCP-XHE-XA-ALTDC1,NSW-AOV-CC-V129,PCS-XHE-XL-LODC1B 5 C 1.25E-8 3.52 IE-TDC1B,DCP-XHE-XA-ALTDC1,NSW-MDP-FC-BRUN,NSW-MDP-FS-1A,PCS-XHE-XL-LODC1B 6 C 8.87E-9 2.49 IE-TDC1B,DCP-XHE-XA-ALTDC1,NSW-MDP-FC-BRUN,NSW-MOV-CC-1SWV19,PCS-XHE-XL-LODC1B Cut Set Report - LOOPWR 25 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 1.74E-7 100 Displaying 27 Cut Sets. (27 Original) 1 C 1.07E-7 61.50 IE-LOOPWR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEWR,RCI-TDP-FR-TRAIN 2 C 2.96E-8 16.98 IE-LOOPWR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEWR,RCI-TDP-TM-TRAIN 3 C 1.76E-8 10.07 IE-LOOPWR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEWR,RCI-TDP-FS-TRAIN 4 C 8.12E-9 4.65 IE-LOOPWR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEWR,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 5 C 5.39E-9 3.09 IE-LOOPWR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEWR,RCI-MOV-FC-XFER,RCI-XHE-XL-XFER 6 C 2.71E-9 1.55 IE-LOOPWR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEWR,RCI-XHE-XO-ERROR 7 C 2.61E-9 1.49 IE-LOOPWR,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITEWR,RCI-MOV-CC-F013 Cut Set Report - LOOPSC 25 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 1.42E-7 100 Displaying 35 Cut Sets. (35 Original) 1 C 8.70E-8 61.20 IE-LOOPSC,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITESC,RCI-TDP-FR-TRAIN 2 C 2.40E-8 16.90 IE-LOOPSC,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITESC,RCI-TDP-TM-TRAIN 3 C 1.42E-8 10.02 IE-LOOPSC,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITESC,RCI-TDP-FS-TRAIN 4 C 6.58E-9 4.63 IE-LOOPSC,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITESC,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 5 C 4.37E-9 3.07 IE-LOOPSC,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITESC,RCI-MOV-FC-XFER,RCI-XHE-XL-XFER 6 C 2.19E-9 1.54 IE-LOOPSC,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITESC,RCI-XHE-XO-ERROR 7 C 2.11E-9 1.49 IE-LOOPSC,ADS-XHE-XE-ADSBT,OEP-VCF-LP-SITESC,RCI-MOV-CC-F013 Cut Set Report - LODC1B2 32 7

Only items contributing at least 1% to the total are displayed.

  1. CASES PROB/FREQ TOTAL% CUT SET 8.60E-8 100 Displaying 35 Cut Sets. (35 Original) 1 C 4.34E-8 50.45 IE-TDC1B2,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B2,RHR-SYS-TM-A 2 C 1.77E-8 20.63 IE-TDC1B2,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B2,RHR-MOV-CC-F007A 3 C 1.75E-8 20.37 IE-TDC1B2,DCP-XHE-XA-ALTDC1,NSW-AOV-CC-V129,PCS-XHE-XL-LODC1B2 4 C 1.77E-9 2.06 IE-TDC1B2,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B2,RHR-MOV-OO-F048A,RHR-XHE-XM-NPSH 5 C 1.77E-9 2.06 IE-TDC1B2,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B2,RHR-XHE-XM-NPSH,RSW-MOV-CC-F068A 6 C 9.21E-10 1.07 IE-TDC1B2,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B2,RHR-XHE-XM-ERROR,RHR-XHE-XM-NPSH 7 C 9.02E-10 1.05 IE-TDC1B2,DCP-XHE-XA-ALTDC1,PCS-XHE-XL-LODC1B2,RHR-STR-PG-S1 Cut Set Report - LOOPGR 28-35 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 7.49E-8 100 Displaying 162 Cut Sets. (162 Original) 1 C 1.86E-8 24.82 IE-LOOPGR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,OEP-XHE-XX-NR30MGR0,RCI-TDP-FR-TRAIN 2 C 1.41E-8 18.83 IE-LOOPGR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-FR-TRAIN 3 C 5.14E-9 6.85 IE-LOOPGR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,OEP-XHE-XX-NR30MGR0,RCI-TDP-TM-TRAIN 4 C 4.69E-9 6.26 IE-LOOPGR,EPS-FAN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-FR-TRAIN 5 C 3.90E-9 5.20 IE-LOOPGR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-TM-TRAIN 6 C 3.05E-9 4.06 IE-LOOPGR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,OEP-XHE-XX-NR30MGR0,RCI-TDP-FS-TRAIN 7 C 2.31E-9 3.08 IE-LOOPGR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-FS-TRAIN 8 C 2.19E-9 2.93 IE-LOOPGR,ACP-CRB-CC-E1,ACP-CRB-CC-E2,EPS-XHE-XL-NR30M,OEP-XHE-XL-NR30MGR,RCI-TDP-FR-TRAIN 9 C 2.00E-9 2.67 IE-LOOPGR,EPS-SEQ-CF-DGS,EPS-XHE-XL-NR30M,EPS-XHE-XL-SEQ,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-FR-TRAIN 10 C 1.49E-9 1.99 IE-LOOPGR,EPS-DGN-CF-START4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-FR-TRAIN 11 C 1.41E-9 1.88 IE-LOOPGR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,OEP-XHE-XX-NR30MGR0,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 12 C 1.29E-9 1.73 IE-LOOPGR,EPS-FAN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-TM-TRAIN 8
  1. CASES PROB/FREQ TOTAL% CUT SET 13 C 1.07E-9 1.42 IE-LOOPGR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 14 C 9.55E-10 1.27 IE-LOOPGR,EPS-FAN-CF-START4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-FR-TRAIN 15 C 7.68E-10 1.02 IE-LOOPGR,EPS-FAN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEGR,OEP-XHE-XL-NR30MGR,RCI-TDP-FS-TRAIN Cut Set Report - LODC1B 40 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 1.32E-7 100 Displaying 96 Cut Sets. (96 Original) 1 C 4.41E-8 33.47 IE-TDC1B,ACP-CRB-CC-E1,DCP-XHE-XA-ALTDC1 2 C 3.13E-8 23.78 IE-TDC1B,DCP-XHE-XA-ALTDC1,LCS-ICC-FC-N031C 3 C 3.13E-8 23.78 IE-TDC1B,DCP-XHE-XA-ALTDC1,LCS-ICC-FC-N031A 4 C 4.09E-9 3.10 IE-TDC1B,ACP-BAC-LP-E1,CSW-MDP-FC-CSTBY 5 C 2.10E-9 1.59 IE-TDC1B,DCP-XHE-XA-ALTDC1,EPS-DGN-FR-DG1,OPR-XHE-XM-ALTUNITXC 6 C 1.74E-9 1.32 IE-TDC1B,DCP-XHE-XA-ALTDC1,LCS-MDP-TM-C001A,NSW-MDP-FC-BRUN,NSW-MDP-TM-1A 7 C 1.65E-9 1.25 IE-TDC1B,DCP-XHE-XA-ALTDC1,LCS-ICC-HI-N031ABCD Cut Set Report - LODC1B2 40 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 1.24E-7 100 Displaying 73 Cut Sets. (73 Original) 1 C 4.41E-8 35.40 IE-TDC1B2,ACP-CRB-CC-E1,DCP-XHE-XA-ALTDC1 2 C 3.13E-8 25.16 IE-TDC1B2,DCP-XHE-XA-ALTDC1,LCS-ICC-FC-N031A 3 C 3.13E-8 25.16 IE-TDC1B2,DCP-XHE-XA-ALTDC1,LCS-ICC-FC-N031C 4 C 2.10E-9 1.68 IE-TDC1B2,DCP-XHE-XA-ALTDC1,EPS-DGN-FR-DG1,OPR-XHE-XM-ALTUNITXC 5 C 1.65E-9 1.32 IE-TDC1B2,DCP-XHE-XA-ALTDC1,LCS-ICC-HI-N031ABCD 6 C 1.25E-9 1.01 IE-TDC1B2,ACP-CRB-OO-AG0,DCP-XHE-XA-ALTDC1,EPS-DGN-FR-DG1 7 C 1.25E-9 1.01 IE-TDC1B2,ACP-CRB-OO-AJ5,DCP-XHE-XA-ALTDC1,EPS-DGN-FR-DG1 Cut Set Report - LOOPWR 28-35 Only items contributing at least 1% to the total are displayed.

9

  1. CASES PROB/FREQ TOTAL% CUT SET 1.91E-8 100 Displaying 92 Cut Sets. (92 Original) 1 C 4.65E-9 24.34 IE-LOOPWR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,OEP-XHE-XX-NR30MWR0,RCI-TDP-FR-TRAIN 2 C 3.53E-9 18.46 IE-LOOPWR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-FR-TRAIN 3 C 1.28E-9 6.72 IE-LOOPWR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,OEP-XHE-XX-NR30MWR0,RCI-TDP-TM-TRAIN 4 C 1.17E-9 6.14 IE-LOOPWR,EPS-FAN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-FR-TRAIN 5 C 9.74E-10 5.10 IE-LOOPWR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-TM-TRAIN 6 C 7.61E-10 3.98 IE-LOOPWR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,OEP-XHE-XX-NR30MWR0,RCI-TDP-FS-TRAIN 7 C 6.48E-10 3.39 IE-LOOPWR,ACP-CRB-CC-E1,ACP-CRB-CC-E2,EPS-XHE-XL-NR30M,OEP-XHE-XL-NR30MWR,RCI-TDP-FR-TRAIN 8 C 5.77E-10 3.02 IE-LOOPWR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-FS-TRAIN 9 C 5.00E-10 2.62 IE-LOOPWR,EPS-SEQ-CF-DGS,EPS-XHE-XL-NR30M,EPS-XHE-XL-SEQ,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-FR-TRAIN 10 C 3.72E-10 1.95 IE-LOOPWR,EPS-DGN-CF-START4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-FR-TRAIN 11 C 3.52E-10 1.84 IE-LOOPWR,EPS-DGN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,OEP-XHE-XX-NR30MWR0,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 12 C 3.24E-10 1.69 IE-LOOPWR,EPS-FAN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-TM-TRAIN 13 C 2.67E-10 1.40 IE-LOOPWR,EPS-XHE-XL-NR30M,NSW-CKV-CF-EDGS,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-RESTART,RCI-TDP-FS-RSTRT,RCI-XHE-XL-RSTRT 14 C 2.39E-10 1.25 IE-LOOPWR,EPS-FAN-CF-START4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-FR-TRAIN 15 C 1.92E-10 1.00 IE-LOOPWR,EPS-FAN-CF-RUN4,EPS-XHE-XL-NR30M,OEP-VCF-LP-SITEWR,OEP-XHE-XL-NR30MWR,RCI-TDP-FS-TRAIN Cut Set Report - LODC1B 41 Only items contributing at least 1% to the total are displayed.
  1. CASES PROB/FREQ TOTAL% CUT SET 3.47E-8 100 Displaying 28 Cut Sets. (28 Original) 1 C 1.84E-8 53.13 IE-TDC1B,ADS-XHE-XE-ADSBT,DCP-XHE-XA-ALTDC1 2 C 5.18E-9 14.95 IE-TDC1B,DCP-BAT-LP-1A1 3 C 2.87E-9 8.29 IE-TDC1B,DCP-BCH-LP-1A1,DCP-XHE-XM-LOADSHED,FLAG-BATTERY-BANK1A 4 C 2.08E-9 5.99 IE-TDC1B,DCP-BDC-LP-1A1 5 C 2.08E-9 5.99 IE-TDC1B,DCP-BDC-LP-DP3A 6 C 1.87E-9 5.39 IE-TDC1B,DCP-CRB-CO-DP3A 7 C 6.35E-10 1.83 IE-TDC1B,ACP-CRB-CC-E1,DCP-XHE-XA-ALTDC1,DCP-XHE-XM-LOADSHED,EPS-XHE-XM-SAMG,FLAG-BATTERY-BANK1A Cut Set Report - LODC1B2 41 10

Only items contributing at least 1% to the total are displayed.

  1. CASES PROB/FREQ TOTAL% CUT SET 3.38E-8 100 Displaying 19 Cut Sets. (19 Original) 1 C 1.84E-8 54.47 IE-TDC1B2,ADS-XHE-XE-ADSBT,DCP-XHE-XA-ALTDC1 2 C 5.18E-9 15.32 IE-TDC1B2,DCP-BAT-LP-1A1 3 C 2.87E-9 8.50 IE-TDC1B2,DCP-BCH-LP-1A1,DCP-XHE-XM-LOADSHED,FLAG-BATTERY-BANK1A 4 C 2.08E-9 6.14 IE-TDC1B2,DCP-BDC-LP-1A1 5 C 2.08E-9 6.14 IE-TDC1B2,DCP-BDC-LP-DP3A 6 C 1.87E-9 5.52 IE-TDC1B2,DCP-CRB-CO-DP3A 11

Referenced Events Event Description Probability ACP-BAC-LP-E1 DIVISION E1 AC POWER BUSES FAIL 3.33E-5 ACP-CRB-CC-E1 FAILURE OF BUS E1 NORMAL FEED BREAKER TO OPEN 2.39E-3 ACP-CRB-CC-E2 FAILURE OF BUS E2 NORMAL FEED BREAKER TO OPEN 2.39E-3 ACP-CRB-OO-AG0 FAILURE OF BUS E1 ALTERNATE FEED BREAKER TO CLOSE 2.39E-3 ACP-CRB-OO-AJ5 FAILURE OF BUS E3 ALTERNATE FEED BREAKER TO CLOSE 2.39E-3 ADS-XHE-XE-ADSBT OPERATOR FAILS TO VALVE IN ADS NITROGEN BOTTLE BANK 1.00E-3 CSW-MDP-FC-CSTBY CSW PUMP C IS IN STANDBY 3.33E-1 DCP-BAT-LP-1A1 DIVISION I 125 VDC BATTERY 1A1 FAILS 1.41E-5 DCP-BCH-LP-1A1 FAILURE OF DIVISION 1 BATTERY CHARGER 1A1 6.50E-5 DCP-BDC-LP-1A1 DIVISION I 125/250 VDC BUS 1A1 IS UNAVAILABLE 5.64E-6 DCP-BDC-LP-DP3A FAILURE OF DISTRIBUTION PANEL 3A 5.64E-6 DCP-CRB-CO-DP3A DISTRIBUTION PANEL 3A SUPPLY BREAKER FAILS TO REMAIN CLOSED 5.07E-6 DCP-XHE-XA-ALTDC1 FAILURE TO ALIGN ALTERNATE DC SUPPLY 5.00E-2 DCP-XHE-XM- OPERATOR FAILS TO COMPLETE DC LOAD SHED 1.20E-1 LOADSHED EPS-DGN-CF-RUN4 COMMON CAUSE FAILURE OF ALL 4 DIESEL GENERATORS TO RUN 5.93E-5 EPS-DGN-CF-START4 COMMON CAUSE FAILURE OF ALL 4 DIESEL GENERATORS TO START 4.75E-6 EPS-DGN-FR-DG1 DIESEL GENERATOR 1 FAILS TO RUN 2.85E-2 EPS-FAN-CF-RUN4 FAILURE OF ALL FOUR DG EXHAUST FANS TO RUN 1.50E-5 EPS-FAN-CF-START4 FAILURE OF ALL FOUR DG EXHAUST FANS TO START 3.05E-6 EPS-SEQ-CF-DGS CCF OF DGS SEQUENCER FAILURESS 6.38E-6 EPS-XHE-XL-NR30M OPERATOR FAILS TO RECOVER EMERGENCY DIESEL IN 30 MINUTES 9.18E-1 EPS-XHE-XL-SEQ OPERATOR FAILS TO RECOVER DG LOAD SEQUENCERS 1.00E+0 EPS-XHE-XM-SAMG OPERATOR FAILS TO START AND ALIGN SAMG DG FOR 125VDC CHARGING 1.20E-1 FLAG-BATTERY- BATTERY BANK 1A DEPLETION FOLLOWING LOSS OF POWER FROM BATTERY 1.00E+0 BANK1A CHARGER IE-LOIA LOSS OF INSTRUMENT AIR SYSTEM 7.49E-3 IE-LOOPGR LOSS OF OFFSITE POWER INITIATOR (GRID-RELATED) 1.22E-2 IE-LOOPSC LOSS OF OFFSITE POWER INITIATOR (SWITCHYARD-CENTERED) 1.04E-2 IE-LOOPWR LOSS OF OFFSITE POWER INITIATOR (WEATHER-RELATED) 3.91E-3 IE-TDC1B LOSS OF VITAL DC BUS 1B 3.69E-4 IE-TDC1B2 LOSS OF VITAL DC BUS 3.69E-4 LCS-ICC-FC-N031A LEVEL TRANSMITTER B21-LT-N031A FAILS HIGH 1.70E-3 LCS-ICC-FC-N031C LEVEL TRANSMITTER B21-LT-N031C FAILS HIGH 1.70E-3 LCS-ICC-HI-N031ABCD LEVEL INSTRUMENTS N031-A,B,C,D FAIL HI (PSA) 8.93E-5 LCS-MDP-TM-C001A LCS MDP C001A UNAVAILABLE DUE TO TEST AND MAINTENANCE 7.12E-3 NSW-AOV-CC-V129 RHR RM A COOLER ISOLN VLV FAILS TO OPEN 9.51E-4 NSW-CKV-CF-EDGS CCF - ALL UNIT 1 & 2 DG SW SUPPLY CKVs FAIL TO OPEN (PSA Value) 4.50E-5 NSW-MDP-FC-BRUN NSW PUMP B IS RUNNING, PUMP A IS IN STANDBY 5.00E-1 NSW-MDP-FS-1A NSW MDP 1A FAILS TO START 1.36E-3 NSW-MDP-TM-1A NSW MDP 1A UNAVAILABLE DUE TO TEST AND MAINTENANCE 2.65E-2 NSW-MOV-CC-1SWV19 NSW MDP 1A DISCHARGE ISOL MOV SWS V-19 FAILS TO OPEN 9.63E-4 OEP-VCF-LP-SITEGR SITE LOOP (GRID-RELATED) 8.18E-1 OEP-VCF-LP-SITESC SITE LOOP (SWITCHYARD-RELATED) 2.11E-1 OEP-VCF-LP-SITEWR SITE LOOP (WEATHER-RELATED) 6.92E-1 OEP-XHE-XL-NR30MGR OPERATOR FAILS TO RECOVER OFFSITE POWER IN 30 MINUTES (GRID- 8.63E-1 RELATED)

OEP-XHE-XL-NR30MWR OPERATOR FAILS TO RECOVER OFFSITE POWER IN 30 MINUTES (WEATHER- 7.95E-1 RELATED)

OEP-XHE-XX- CONVOLUTION FACTOR FOR CCF-OPR (30MIN-GR Avail) 1.00E+0 NR30MGR0 OEP-XHE-XX- CONVOLUTION FACTOR FOR CCF-OPR (30MIN-WR Avail) 1.00E+0 NR30MWR0 12

OPR-XHE-XM- OPERATOR FAILS TO CROSS-TIE DIVISION BUSES (2 HRS) 4.00E-3 ALTUNITXC PCS-XHE-XL-LODC1B POWER CONVERSION SYSTEM RECOVERY FAILS DURING LODC1B 1.00E+0 PCS-XHE-XL-LODC1B2 POWER CONVERSION SYSTEM RECOVERY FAILS DURING LODC1B2 1.00E+0 RCI-MOV-CC-F013 RCIC INJECTION VALVE F013 CAUSES FAILURE TO START 9.63E-4 RCI-MOV-FC-XFER RCIC FAILS TO TRANSFER DURING RECIRCULATION 7.97E-3 RCI-RESTART RESTART OF RCIC IS REQUIRED 1.50E-1 RCI-TDP-FR-TRAIN RCIC PUMP FAILS TO RUN GIVEN THAT IT STARTED 3.97E-2 RCI-TDP-FS-RSTRT RCIC FAILS TO RESTART GIVEN START AND SHORT-TERM RUN 8.00E-2 RCI-TDP-FS-TRAIN RCIC PUMP FAILS TO START 6.49E-3 RCI-TDP-TM-TRAIN RCIC PUMP TRAIN IS UNAVAILABLE BECAUSE OF MAINTENANCE 1.09E-2 RCI-XHE-XL-RSTRT OPERATOR FAILS TO RECOVER RCIC FAILURE TO RESTART 2.50E-1 RCI-XHE-XL-XFER OPERATOR FAILS TO RECOVER SUCTN XFER FAILURE 2.50E-1 RCI-XHE-XO-ERROR OPERATOR FAILS TO START/CONTROL RCIC INJECTION 1.00E-3 RHR-MOV-CC-F007A RHR LOOP A MINFLOW VALVE F007A FAILS TO OPEN 9.63E-4 RHR-MOV-OO-F048A RHR HEAT EXCHANGER A BYPASS VALVE F048A FAILS TO CLOSE 9.63E-4 RHR-STR-PG-S1 RHR LOOP A SUPPRESSION POOL STRAINER S1 PLUGS 4.90E-5 RHR-SYS-TM-A RHR LOOP A UNAVAILABLE DUE TO TEST AND MAINTENANCE (PSA) 2.35E-3 RHR-XHE-XM-ERROR OPERATOR FAILS TO START/CONTROL RHR FUNCTIONS 5.00E-4 RHR-XHE-XM-NPSH FAILURE TO CONTROL LPCI OPERATION UNDER LOW NPSH CONDITIONS (PSA) 1.00E-1 RSW-MOV-CC-F068A RHR HX1A FLOW CONTROL MOV F068A FAILS TO OPEN 9.63E-4 13

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