Text

Final Accident Sequence Precursor Analysis for the April 17, 2013, Dual Unit Loss of Offsite Power
	ML15107A154
Person / Time
Site:	LaSalle
Issue date:	04/21/2015
From:	Blake Purnell; Plant Licensing Branch III
To:	Bryan Hanson; Exelon Generation Co
	Blake Purnell, NRR/DORL
References
	Download: ML15107A154 (3)
	v • d • e

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 f'Dr;l 21, 2015 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LASALLE COUNTY STATION, UNITS 1AND2 - FINAL ACCIDENT SEQUENCE PRECURSOR ANALYSIS FOR THE APRIL 17, 2013, DUAL UNIT LOSS OF OFFSITE POWER

Dear Mr. Hanson:

This letter provides the final results of an accident sequence precursor (ASP) analysis by U.S.

Nuclear Regulatory Commission (NRC or Commission) for the dual unit loss of offsite power that occurred at LaSalle County Station on April 17, 2013. This analysis has a final conditional core damage probability (CCDP) of 1x10-5 for Unit 1 and 2x 10-5 for Unit 2, which is less than the threshold for a significant precursor (i.e., CCDP greater than or equal to 1x10-3).

In accordance with NRC Regulatory Issue Summary 2006-24, "Revised Review and Transmittal Process for Accident Sequence Precursor Analyses," this analysis was not sent to you for formal review because the analysis had a preliminary CCDP of less than 1 x 10-4 . A response to this letter is not required; however, the NRC staff will review comments the licensee or other stakeholders choose to provide.

The ASP program continues to systematically review licensee event reports and other event reporting information for potential precursors, and to analyze those events which have the potential to be precursors. The complete summary of Fiscal Year 2013 ASP events was provided to the Commission in SECY-14-0107, "Status of the Accident Sequence Precursor Program and the Standardized Plant Analysis Risk Models," dated October 6, 2014.

B. Hanson If you have any questions regarding this matter, I may be reached at 301-415-1380.

Sincerely, Blake Purnell, Project Manager Plant Licensing 111-2 and Planning and Analysis Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374

Enclosure:

Final Precursor Analysis cc w/encl: Distribution via Listserv

Final Precursor Analysis Accident Sequence Precursor Program - Office of Nuclear Regulatory Research LaSalle County Station Dual Unit Loss of Offsite Power Due to Lightning Strike Unit 1 and Unit 2 Event Date: April 17, 2013 LER: 373/13-002 Unit 1: CCDP =1E-5 IR: 05000374/2013009 Unit 2: CCDP =2E-5 Plant Type: Boiling-Water Reactor (BWR), General Electric Type 5, Wet Mark II Containment Plant Operating Mode (Reactor Power Level): Mode 1 (100% Reactor Power)

Analyst: Dale Yeilding, 301-251-7577, Reviewers: David Aird, Contributors: Don Marksberry, Dale.Yeilding@nrc.gov Chris Hunter Song-hua Shen, Keith Tetter 1.0 EXECUTIVE

SUMMARY

On April 17, 2013 at 2:59 p.m. Central Standard Time (CST), LaSalle County Station Units 1 and 2 automatically scrammed from 100 percent power, in conjunction with a loss of offsite power (LOOP). The loss of offsite power occurred when the breakers in the main 345kV switchyard opened, shortly following a lightning strike in the adjacent 138kV switchyard during a thunderstorm. The station's five emergency diesel generators (EDGs) immediately started, successfully loaded onto their respective safety-related buses, and began supplying power to the buses to support operation of essential loads, as expected. Plant systems on both units responded as expected. All control rods fully inserted. The main steam isolation valves closed, with decay heat being removed via the safety relief valves. High Pressure Core Spray (HPCS) automatically started on both units on low reactor water level; Reactor Core Isolation Cooling (RCIC) was used for level control. The licensee declared a Notification of Unusual Event (NOUE) at 3:11 p.m. because of the LOOP. The licensee was able to restore offsite power and exited the NOUE at 8:14 a.m. the following day, April 18.

Following the scrams of both reactors, plant safety-related equipment responded as expected, with a few exceptions. The Unit 2 Residual Heat Removal (RHR) Pump 2C failed to start following an Engineered Safety Features (ESF) actuation signal based on high drywell pressure, and the Unit 1 Low Pressure Core Spray (LPCS) System Injection Valve (1 E21-F005) failed to open when control room operators attempted to manually open the valve using the control switch. Both failures had no significant effect on the ability of operators to respond to the event.

This event involved significant unexpected system interactions. Specifically, a lightning strike to a component of the 138kV electrical system in the switchyard resulted in the opening of all breakers in the 345kV electrical system ring bus and the loss of offsite power to both LaSalle Units. Section 8.2.3.2, "Adequacy of Offsite Power," and Section 8.1.2.5, "Unit Non-Class 1E DC [direct current] System" of the LaSalle County Station Updated Final Safety Analysis Report (UFSAR) indicates that this type of LOOP should not have occurred.

ASP Analysis LER 373/13-002 The lightning strike was coupled with a second event of a transformer failure which caused the opening of all 345kV breakers in the switchyard. The switchyard is designed against single failure, with the opening of all the breakers being unique to this LOOP event. The Special Inspection Team (SIT) report (Reference 5.4) identified four operator knowledge weaknesses regarding the event response, which did not have a significant contribution to risk for this event but could have affected risk if complications had developed.

1.1 Risk Insights The Accident Sequence Precursor (ASP) Program systematically evaluates U.S. nuclear power plant (NPP) operating experience to identify, document, and rank the operating events most likely to lead to inadequate core cooling and severe core damage (i.e., precursors). The Conditional Core Damage Probability (CCDP) for both Unit I (1 E-5) and Unit 2 (2E-5) qualify this LaSalle dual unit event as ASP Precursors as explained in Section 3 of this report. The RHR Pump 2C failure caused the higher CCDP for Unit 2. Typically, most LOOP events qualify as an ASP Precursor. The event CCDP for both units is not quantified near the 1E-3 threshold for a "significant" precursor. This analysis nor do others, try to further evaluate the event beyond the two categories of precursor and significant precursor.

The ASP Program evaluates the trend for all precursors as an input to the Industry Trends Program (ITP), which provides an input to the agency's safety performance measure of no significant adverse trend in industry safety performance. In the annual ASP report, the staff reviews events for risk-informed insights, looking at the systems causing the events, the dominant risk sequences, and the plant types affected by the events. A recent ITP report identified a trend of electrical failures similar to the LaSalle LOOP event not necessarily from a lighting strike, but resulting in losses of offsite power. Regulatory actions taken as a result of these electrical failure events include plant-specific SOP evaluations of the risk significance of the performance deficiencies associated with the events, information notices, and a bulletin.

A secondary objective of the ASP Program is to provide insights into the current state of practice in risk assessment. Past event analysis included an assessment of operator actions for the possibility of dependence described in section 4.6 of this report. After considering the potential modeling adjustments for Joint Human Event Probabilities (JHEP) and the resultant effect on the event CCDP, the ASP Program will no longer consider adjusting model failure probabilities when two human actions occur in the same cutset, until a sound technical basis can be established.

2.0 EVENT DETAILS At 2:59 p.m. Central Standard Time (CST), LaSalle County Station Units 1 and 2 automatically scrammed from 100 percent power, in conjunction with a loss of offsite power. The LOOP occurred when the breakers in the main 345kV switchyard opened, shortly following a lightning strike in the adjacent 138kV switchyard during a thunderstorm.

The station's five EDGs immediately started, successfully loaded onto their respective safety-related buses, and began supplying power to the buses to support operation of essential loads, as expected. Plant systems on both Units responded as expected. All control rods fully inserted. The main steam isolation valves closed, with decay heat being removed via the safety relief valves. HPCS automatically started on both Units on low reactor water level; RCIC was used for level control. The licensee was able to restore offsite power to the Unit 2 Station Auxiliary Transformer, TR-242 and begin unloading the EDGs at 19:24 on April 1ih approximately 4.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months after the LOOP. Three offsite power sources became available with 2

ASP Analysis LER 373/13-002 offsite power declared operable at 5: 10 a.m. on April 18, 2013 and the Licensee terminated the NOUE at 08:14 a.m. Additional information is provided in References 5.1, (LaSalle County Station Unit 1 and 2, LER 373/13-002 - Unusual Event Declared Due to Loss of Offsite Power and Dual Unit Reactor Scram) and 5.4, (U.S. Nuclear Regulatory Commission, LaSalle County Station, Units 1 and 2 - NRC Special Inspection Team (SIT) Inspection Report 05000373/2013009; 0500037 4/2013009).

2.1 Switchyard Performance after Lightning Strike The LOOP to both the 345-kV and 138kV switchyards was caused by a series of events initiated by a lightning strike in the 138kV switchyard. The root cause of the event was determined to be degradation of the 138kV switch yard grounding system that allowed a lightning induced fault to flash over onto the DC protective system. The degradation of the grounding system was due to poor workmanship during original construction. This degradation allowed a fault on the 138kV switchyard initiated by a lightning strike to damage the shared DC protection system. Another contributor to the event was inadequate lightning shielding of the 138kV switchyard.

Section 8.2.3.2, "Adequacy of Offsite Power," of the UFSAR stated, in part, that:

"The switchyard arrangement is such that offsite power to both units cannot be lost due to any single failure."

Additionally, UFSAR Section 8.1.2.5, "Unit Non-Class 1E DC System," stated, in part, that:

The design of the protective relay circuits for the 345-kV oil circuit breakers and the 345-kV transmission lines is such that the loss of either battery or the loss of both batteries and associated feeder cables will not cause the loss of offsite power sources."

The design of the switchyard and the consequences of this event were also evaluated by the licensee against the requirements of General Design Criteria (GDC) 17 (Reference 5.13) as part of the root cause investigation. This review concluded that the LaSalle Offsite Power System design is in compliance with the requirements of GDC 17. It was determined that the degraded ground connections in the 138kV yard were the cause of the flashover onto the DC system therefore the design of switchyard was not the cause of the failure. As the common DC power supply allowed the faults experienced on the 138kV switchyard to ultimately propagate to the 345kV switchyard, the 138kV protection equipment was disconnected from the DC protection system. This second fault was initiated when the Capacitance Coupled Voltage Transformer that had been damaged in the lightning strike and then subjected to line voltage for two minutes, failed. Thus, a single event did not cause the opening of all breakers on the 345kV switchyard and the resultant loss of offsite power.

2.2 Unit 2 RHR Pump On April 17, at about 4:27 p.m. CST, the Unit 2 RHR Pump 2C failed to start from an ESF actuation signal based on high drywell pressure after the 4.16-kV Safety Bus 242Y de-energized and subsequently reenergized during the event. Upon the ESF actuation signal, the breakers for RHR Pumps 28 and 2C closed, starting the LPCI system Trains 28 and 2C. Load shedding of the EOG 2A commenced per design. Approximately one second following the ESF signal, the RHR Pumps 28 and 2C tripped due to an under-voltage condition caused by the load shedding. The under-voltage condition cleared 0.157 seconds later when the EOG 2A output breaker reclosed onto Bus 242Y. Once Bus 242Y was reenergized, the RHR Pump 2C auto-start relay (K21) reenergized, giving a second LPCI system train actuation signal to Pumps 28 and 2C. The total amount of time from the first breaker closure for RHR Pump 2C to the second attempted closure (K21 relay energizing) was 1.606 seconds. This was not sufficient time for the breaker charging springs to fully charge.

3

ASP Analysis LER 373/13-002 The pump breaker anti-pumping circuit (Relay Y) was then left energized, which prevented the second closure of the breaker for RHR Pump 2C, (RHR Pump 2C Breaker Closing Circuit, Attachment G). The anti-pumping circuit contains a limit switch contact LSb whose actuation is based on the charge of the breaker charging coils. This contact will remain closed, therefore energizing a pump lockout relay (Relay Y) until the breaker charging springs are fully charged, roughly equal to three to five seconds. This circuit requires a manual reset and drop out of actuation Relay K21 after the springs are fully charged in order for the Anti-Pump Lockout Relay Y to de-energize. If the breaker were to reopen after closure, as during load shedding of an EDG, and ample time (three to five seconds) is not allowed for the charging springs to charge, the seal-in feature of the anti-pumping circuit (contact Ya whose position is determined by relay Y) will prevent energizing closing coil x and prevent the pump breaker closure and pump actuation. The system worked per design.

The same anti-pumping circuit exists for RHR Pump 2A and 2B. The EDG loading sequence (UFSAR Table 8.3-1) shows these pump's start signal are delayed 5 seconds. The RHR Pump 2C in the EOG loading sequence is started immediately. RHR Pump 2B operation was not affected since the LOCA signal was removed upon SI signal and EOG sequencing, due to a relay sensing bus undervoltage/degraded voltage. The removal of the LOCA signal dropped out Relay K21 and permitted the reset of the charging spring circuit. Attachment G, pages 1-3 explain the RHR pump starting circuit logic.

This same condition did not occur on Unit 1 due to operators placing the RHR Pump 1A and LPCS Pumps in "pull to lock" two minutes prior to the high drywell pressure ECCS signal in anticipation of the Division 1 AC power being de-energized.

The Unit 2 control room operators, however, did not understand how the pump breaker would indicate an apparent start failure due to the simultaneous signals and, therefore, they concluded that the RHR Pump 2C had failed to start. Since it was not needed at the time for LPCI system injection, operators declared the pump inoperable, placed the pump's control switch in pull-to-lock, and made no attempt to immediately restart it. Subsequently, during troubleshooting, the pump was able to start when operators manually reset the logic with the pump's control switch and then started the pump. The inspectors reviewed the electrical schematic diagrams for the RHR Pump 2C and schematic diagrams of the internal control circuit of the 4.16-kV circuit breaker and determined that the Emergency Core Cooling Systems (ECCS) were designed for a simultaneous LOOP and ESF actuation signal, not a LOOP followed by a loss of coolant accident (LOCA).

The NRC posts on its public website different scenarios regarding Generic Safety Issue (GSI) 171, Evaluation of LOCA with Delayed LOOP and LOOP with Delayed LOCA Accident Scenarios, (Reference 5.14), stating:

"Two utility reports identify another failure mechanism in which circuit breaker protective devices lock out the circuit breaker to protect it from potential damage resulting from repeated opening and closing (referred to as "pumping"). The operator actions required to reset the circuit breakers may be quite complicated and could result in a high probability of failure to recover."

2.3 Common EOG Overload All five EDGs started, and loaded on to their respective busses as designed. The common EDG auto started and repowered both Unit 1 Bus 141Y and Unit 2 Bus 241Y. By design, the common EDG (DGO) should only automatically repower the bus for one Unit. The common 4

Analysis

... ER 373/13-002 EOG Output Breakers 1413 and 2413 use 52S/b contacts (closed when opposite breaker is open I open when opposite breaker is closed) in their breaker closing logic to prevent the other unit's breaker from being closed while one breaker is already closed to ensure the swing EOG only supplies a single unit. When a loss of both Buses 141 Y and 241 Y occurs simultaneously, which occurred during the April 17th dual-Unit scram and LOOP, this interlock (52S/b contacts) did not prevent both breakers from closing in at the same moment. This occurred because the voltage and frequency permissive signals for closing both breakers were initiated and received at the same time. It is an unusual circumstance for simultaneous initiating signals to be sent to the EOG control logic; however, the design does not preclude this as the logic will not preferentially filter one Unit's relay over the other Unit's relay. LaSalle Calculation L-003364, "Auxiliary Power Analysis," Revision 1, verified that the total auto-connected loading on the swing EOG is within its continuous rating of 2600 kW when the EOG is connected to both Buses 141Y and 241Y when no LOCA has occurred.

2.4 Additional Details Additional details that did not have an effect of the analysis are described in Attachment F. The details are associated with HPCS and RCIC system leaks, LPCS Pump switch malfunction, subsequent scram from the secondary system and startup without RCIC operational.

3.0 ANALYSIS RES UL TS 3.1 Unit 2 CCDP The point estimate CCDP for Unit 2 is 1.5 E-5. The SAPHIRE Analysis report is in Attachment B.

The ASP Program acceptance threshold is a CCDP of 1E-6 or if higher, the CCDP equivalent of an uncomplicated reactor trip with a non-recoverable loss of secondary plant systems which for modeling purposes, is an initiating event for a Loss of Condenser Heat Sink (LOCHS) (7E-6 for LaSalle) and an initiating event of Loss of Main Feedwater (LOMFW) (5E-6 for LaSalle).

Selecting the highest failure probability from these conditions establishes the LaSalle acceptance precursor threshold for the ASP program at 7E-6 in lieu of 1E-6. This Unit 2 LOOP event analyzed with a CCDP of 2E-5 is thus considered an ASP Precursor since it is just greater than the threshold than what is considered a standard plant transient for LaSalle Unit 2. The agency ASP Program defines a significant precursor with a CCDP of 1E-3, which is almost two decades higher than the Unit 2 LOOP.

ASP Unit 2 ASP Significant Precursor LOMFW LOCHS LOOP Precursor

---1------------------1-------1------------1--1-----------------------------------1---------------------------------------1--

5 7 2 E-6 I E-5 E-4 E-3 Precursor Threshold 3.2 Unit 2 Dominant Sequence(s)

The Loss of Offsite Power, Switchyard Centered (LOOPSC) Event Tree (Attachment A) has 44 sequences without considering transfers to other trees (i.e. SBO, A TWS, etc.) Four sequences contributed 74% towards the total Conditional Core Damage Probability (CCDP).

5

ASP Analysis LER 373/13-002 Unit 2 Sequence("/" slash signifies system success) 24% LOOPSC-43-34-09 /RPS, EPS, P2, HCS-SBO, /RCl-SBO, OPR-01H, DGR-01H 24% LOOPSC-42-13 /RPS, /EPS, P2, HCS, LPI 16% LOOPSC-43-31 /RPS, EPS, /SRV, /RPSL, /HCS-SBO, RCl-SBO, OPR-30M, DGR-30M 10% LOOPSC-07 /RPS, /EPS, /SRV, /HCS, SPC, /DEP, SDC, CSS, CVS, LI03 74%

3.2.1 General - All four sequences began with:

/RPS - Success of the Reactor Protection System (RPS) to insert enough negative reactivity by the control rods to shut down the reactor.

3.2.2 Sequence LOOPSC-43-34 transfers from the LOOPSC event tree to the station black out event tree involving more than one SRV failing open coupled with the failure of high pressure injection along with the failure to recover AC power within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months .

EPS - Failure of the onsite Emergency Power System (EPS) with AC power not available on either the Division 1 or Division II bus.

P2 - Failure of more than one SRV to close or to remain closed.

HCS-SBO - Failure of the High Pressure Core Spray (HPCS) during a station black out.

HPCS involves automatic actuation and operation of the HPCS pump with initial pump suction from the Condensate Storage Tank (CST) and subsequent realignment of the pump suction to the suppression pool.

/RCl-SBO - Success of Reactor Core Isolation Cooling (RCIC) system during a station black out. RCIC involves automatic actuation and operation of the RCIC pump with initial pump suction from the CST and subsequent realignment of the pump suction to the suppression pool.

OPR-01 H - Failure of the operator to recover offsite power to the emergency busses within an hour. Success implies that offsite power has been recovered and all plant loads can be energized from their normal supplies.

DGR-01 H - Failure of operator to recover EOG power to the emergency busses to at least one emergency division within an hour.

3.2.3 Sequence LOOPSC-42 This sequence involves the failure of safety relief valves (SRVs) to close and failure to inject.

/EPS - Success of the onsite Emergency Power System (EPS) with AC power available on either the Division I or Division 11 bus.

P2 - Failure of more than one SRV to close or to remain closed.

HCS - Failure of the HPCS system with automatic actuation and operation of the HPCS pump with initial pump suction from the CST and subsequent realignment of the pump suction to the suppression pool.

6

ASP Analysis LER 373/13-002 LPI - Failure of the low pressure coolant injection system for any one RHR pump operation and injection through at least one low-pressure coolant injection line.

3.2.4 Sequence LOOPSC-43 This sequence involves the failure of emergency power, RCI to inject and failure of the operator to recovery of offsite power and an emergency power within 30 minutes.

EPS - Failure of the onsite Emergency Power System (EPS) with AC power not available on either the Division 1 or Division II bus.

/SRV - Success of the SRVs to open, relieves pressure, and recloses. The pressure relief function is assumed successful but failure to reclose is modeled with either one, or two or more SRVs having failed to reclose

/RPSL - Success of recirculation pump seal integrity. Success implies the recirculation pump seals do not fail during a station blackout.

/HCS-SBO - Success of the HPCS during a station black out. HPCS involves automatic actuation and operation of the HPCS pump with initial pump suction from the CST and subsequent realignment of the pump suction to the suppression pool.

RCl-SBO - Failure of RCIC system during a station black out. RCIC involves automatic actuation and operation of the RCIC pump with initial pump suction from the CST and subsequent realignment of the pump suction to the suppression pool.

OPR-30M - Failure of operator to recover offsite power to the emergency busses within 30 minutes. Success implies that offsite power has been recovered and all plant loads can be energized from their normal supplies.

DGR-30M - Failure of operator to recover EOG power to the emergency busses within 30 minutes to at least one emergency division.

3.2.5 Sequence LOOPSC This sequence involves the failure of SPC and SOC and a failure to spray and vent containment.

/EPS - Success of the onsite Emergency Power System (EPS) with AC power available on either the Division 1 or Division 11 bus.

/SRV - Success of the SRVs to open, relieve pressure, and reclose. The pressure relief function is assumed successful but failure to reclose is modeled with either one, or two or more SRVs having failed to reclose

/HCS - Success of the HPCS system with automatic actuation and operation of the high pressure core spray pump with initial pump suction from the CST and subsequent realignment of the pump suction to the suppression pool.

SPC - Failure of the Suppression Pool Cooling (SPC) mode of RHR without operation of any one of the RHR pumps and its associated heat exchanger and injection through at least one suppression pool cooling line.

7

"'::;p Analysis LER 373/13-002

/DEP - Success of reactor depressurization (DEP) for operators to manually depressurize the reactor when instructed by procedure.

SOC - Failure of the Shutdown Cooling (SOC) mode of RHR without operation of any one of the RHR pumps and its associated heat exchanger and injection through at least one shutdown cooling line.

CSS - Failure of the Containment Spray (CSS) mode of RHR without operation of any one of the RHR pumps and its associated heat exchanger and spray through at least one containment spray header.

CVS - Failure of the Containment Venting System (CVS) with a vent path opened.

LI03 - Failure of late injection.

3.3 Unit 1 Conditional Core Damage Probability The Unit 1 analysis is the same as Unit 2 with the Unit 2 RHR pump failure removed.

The point estimate conditional core damage probability (CCDP) for Unit 1 is 1.3 E-5. The SAPHIRE Analysis report is in Attachment E.

The ASP Program acceptance threshold is a CCDP of 1E-6 or if higher, the CCDP equivalent of an uncomplicated reactor trip with a non-recoverable loss of secondary plant systems which for modeling purposes, is an initiating event for a Loss of Condenser Heat Sink (LOCHS) (7E-6 for LaSalle) and an initiating event of Loss of Main Feedwater (LOMFW) (5E-6 for LaSalle).

Selecting the highest failure probability from these conditions establishes the LaSalle acceptance precursor threshold for the ASP program at 7E-6 in lieu of 1E-6. This Unit 1 LOOP event analyzed with a CCDP of 1.3E-5 is thus considered an ASP Precursor since it is just greater than the threshold than what is considered a standard plant transient for LaSalle Unit 1.

The agency ASP Program defines a significant precursor with a CCDP of 1E-3, which is almost two decades higher than the Unit 1 LOOP.

ASP Unit 1 ASP Significant Precursor LOMFW LOCHS LOOP Precursor

---1------------------1-------1------------1-1--------------------------------------1---------------------------------------1--

5 7 1 E-6 I E-5 E-4 E-3 Precursor Threshold 3.4 Unit 1 Dominant Sequence(s)

The LOOPSC event tree has 44 sequences (Attachment A) without considering transfers to other trees (i.e. SBO, ATWS, etc.) Four sequences contributed 71 % towards the total CCDP.

The sequences are the same as Unit 2 with LOOP-42-13 dropping in percentage contribution from 24% to 10%.

Unit 1 Sequence ("/" slash signifies system success) 29% LOOPSC-43-34-09 /RPS, EPS, P2, HCS-SBO, /RCl-SBO, OPR-01H, DGR-01H 20% LOOPSC-43-31 /RPS, EPS, /SRV, /RPSL, /HCS-SBO, RCl-SBO, OPR-30M, DGR-30M 8

ASP Analysis LER 373/13-002 12% LOOPSC-07: /RPS, /EPS, /SRV, /HCS, SPC, /DEP, SDC, CSS, CVS, LI03 10% LOOPSC-42-13 /RPS, /EPS, P2, HCS, LPI 71%

4.0 MODELING 4.1 Analysis Type The SAPHIRE software version 8.1.0 was used for this event analysis with the LaSalle Standardized Plant Analysis (SPAR) risk model version 8.24 (created in September 2014). This event was modeled as a switchyard-centered LOOP initiating event.

4.2 Analysis Rules The ASP program uses Significance Determination Process (SOP) results for degraded conditions when available. However, the ASP Program performs independent analysis for initiating events. The analysis was performed using Risk Assessment Standardization Project (RASP) Volume 1 (Internal Events) Appendix A, Road Map for Risk Analysis of Operational Events (Reference 5.10).

Scientific "E" notation will be used to reflect numbers less than zero in this report. The letter E will be used to represent times ten raised to the power of. For any two real numbers a and b, the usage of "a E b"would indicate the value of ax 10b. Because superscripted exponents are visibly small and extremely important when dealing with probability or CCDP orders of magnitude, E notation will be used in lieu of scientific notation. For example, 0.00022 is equal to 2.2 x10- 4 , and reflected in this analysis report as 2.2E-4. "E" notation is also the default notation for reports using the SAPHIRE software.

4.3 Key Modeling Assumptions The following modeling assumptions were made for the modeling of this event analysis:

4. 3.1 Several additional events that occurred from 22 hours2.546296e-4 days 0.00611 hours 3.637566e-5 weeks 8.371e-6 months to 10 days after the LOOP were reviewed and determined to not factor into this analysis. They are described in detail in Attachment F.

- Unit 2 HPCS pin hole leak

- Unit 1 LPCS switch malfunction

- Unit 2 scram from secondary system

- Unit 1 RCIC not operational per technical specifications

- Unit 1 RCIC steam leak 4.3.2 A switchyard-related LOOP causes a subsequent reactor trip.

4.3.3 Offsite power was not recovered to a safety bus until 4.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months after the LOOP occurred.

However, offsite power could have been restored within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months using Operating Abnormal Procedure LOA-AP-201, AC Power System Abnormal. The basis is that no lightning repairs were necessary to the 345kV switchyard since the lightning only struck the 138kV side of the switchyard. Inspection for 345kV component integrity and procedure steps could have been performed in 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months during a postulated station blackout (SBO) event, which if occurred, would have hastened the restoration of offsite power.

4.3.4 Several operator action basic events are modeled allowing for recovery of offsite power at times associated with other modeled mitigation functions, ranging from 30 minutes to 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

When the duration of the loss of offsite power is known, these recovery basic events can also 9

ASP Analysis LER 373/13-002 be adjusted. The offsite power recovery basic events with available times less than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months are set to TRUE (i.e., failed), since offsite power could not be recovered by then. Those offsite power recovery basic events with available time of greater than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months are adjusted using the Human Reliability Analysis (HRA) Worksheets (Attachment D) to adjust the nominal basic event failure probability using known performance shaping factors.

Basic events for Operator Fails to Recover Offsite Power in 30 minutes and 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months are set to TRUE/ (i.e., failed).

Basic events for Operator Fails to Recover Offsite Power in 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months , 7 hours8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months , and 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months are analyzed by HRA and set to a value determined by the conditions.

4.3.5 The CCDP for this LOOP initiating event is calculated for a single point in time which typically affects the probabilities for certain components to function within an established mission time, 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months in this case. When it is know that the mission time is actually less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , the reduced time will credit certain components, resulting in a lower probability of failure for those component basic events.

Mission times for EDGs and the RCIC turbine driven pump were set to 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . The EOG and TOP mission time is adjusted to lower values to differentiate between LOOPs of lesser duration.

Mission times for motor driven pumps because the mission time is for the PRA is 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

4.3.6 Licensee calculation L-003364, "Auxiliary Power Analysis," Revision 1, verified that the total auto-connected loading on the swing EOG is within its continuous rating of 2600 kW when the EOG is connected to both Unit 1 and Unit 2 Buses 141Y and 241Y with no LOCA. The swing EDGO was designed to supply only one unit but not both. After review of the probabilities for the most limiting LOCA, it was assumed that one or more SRV stuck-open events were most limiting. See section 4.4.8 of this report.

4.3.7 For Unit 2 only, the failure of Unit 2 RHR Pump 2C described in Section 2.2 of this report does not have common cause failure correlation to RHR Pumps 2A and 2B. The EOG loading sequence from UFSAR table 8.3-1 shows the RHR 2C pump starting immediately and the RHR Pump 2A and 2B delayed 5 seconds. The RHR Pump 2A and 2B circuit breaker anti-pumping circuit would not inhibit breaker reclosing since the EOG loading sequence delay allows sufficient time for the RHR pump breaker charging springs to recharge. It is assumed that the RHR Pump 2B, supplied from the same bus as RHR Pump 2C did not experience the same anti-pumping lock-out due to the operator performing a manual reset at the control switch (positioning to stop before start). The RHR Pump 2B was started and placed in suppression pool cooling mode of operation, 13 minutes after the lock-out of RHR Pump 2C. The failure of the RHR 2C pump was modeled with a new basic event such that common cause failure will not be considered as described by the fault tree modification in section 4.4.2 of this report.

4.3.8 An hour and a half into the event, Unit 1 operators placed the Division 1 electrically supplied RHR Pump 1A and LPCS Pump control switches in Pull-to-lock to secure pumps in anticipation of AC power being de-energized. Two minutes later, a Unit 2 high drywell pressure ESF actuation signal results in the common EDGO to transfer to Unit 2 causing Unit 1 to lose Division 1 power to the two pumps placed in Pull-to-lock. These two pumps are assumed to be operable and available with no modeling adjustments for this analysis, understanding that 10

ASP Analysis LER 373/13-002 operator action would be required to take the pump switch out of pull-to-lock and the swing EOG would need to transfer if pump operation was required.

4.4 Fault Tree Modification 4.4.1 The LaSalle swing Diesel Generator (DGO) fault tree (Attachment C) was modified to account for design anomaly that appeared during this event. The swing diesel generator (one of five at the site) was not designed to supply both units simultaneously. The simultaneous starting logic from this LOOP event resulted in the DGO loading onto both units as explained in Section 2.3 of this report. The licensee's load analysis and the Special Inspection Team report, identified the diesel can supply both units, except in the event of a LOCA. The most probable LOCA was determined to be one or more stuck open SRVs. The basic event EPS-DGN-DGO-LOCA was added to the DGO Fault Tree and set to "ignore" and also added to a flag set ETF-SORV and set to "true" and invoked with the rule below to fail the swing EOG when a failed SRV appears in a cutset.

The LOOPSC initiating event has two failure paths for the SRV fault tree, SRV[1] and SRV[2].

Fault tree P1 involves the failure of one SRV and fault tree P2 involves the failure of two or more SRVs. When either exists in a cut set, a flag set will trigger a basic event from "ignore to true" to fail the swing EDGO. The following linkage rule was added to the LOOPSC event tree logic:

LOOPSC linkage rule:

if SRV[1] + SRV{2] then eventree(LOOPSC) = Flag(ETF-SORV);

endif 4.4.2 For Unit 2 only, the RHR Pump 2C fault tree (Attachment C) was modified to account for the failure of the Unit 2 RHR Pump 2C to start in response to a LOOP followed by an ESF Actuation as explained in detail in Section 2.2 of this report. The failure of the pump breaker to close was due to inadequate time for the breaker charging springs to recharge and not associated with any internal component of the pump. Thus, the pump Fail-To-Start failure mode was not adjusted in the model since this would result in additional common cause failure probability adjustments for similar pumps. A new basic event (RHR-MDP-SEQUENCER) was added to the fault tree to fail RHR Pump 2C and avoid common cause failure adjustments to the other pumps not subject to this failure mode.

4.5 Basic Event Probability Changes Two separate analyses were performed for Unit 1 and Unit 2 with most of the changes indicated below related to both units except where indicated for Unit 2 only involving the RHR pumps.

The results are reported separately for each unit in Attachment B (Unit 2) and Attachment E (Unit 1). The following initiating event frequencies and basic event probabilities were modified for this event analysis:

4.5.1 This analysis models the April 17, 2013 reactor trip at LaSalle County Station as a switchyard-related LOOP initiating event.

The probability of switchyard-centered LOOP was set to 1.0; all other initiating event probabilities were set to zero.

Conditional Nominal IE LOOPSC (Loss of Offsite Power Initiator, Switchyard-Centered) 1.0 1.04E-2 11

ASP Analysis LER 373/13-002 4.5.2 For Unit 2 only, the RHR Pump 2C failed to start and the associated basic event was set to TRUE (i.e., failed).

Conditional Nominal RHR-MDP-Sequencer RHR Pump C Unavailable Due To Lack of Time Delay (EOG Sequencer) True Ignore 4.5.3 Offsite power was not considered recoverable until approximately 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after the LOOP occurred, considering a postulated SBO. The Recovery of Offsite Power fault tree (ROOP) is a special use fault tree that is used to credit the appropriate offsite power recovery period for each sequence on the LOOP event tree. The fault tree contains flags for 30-minutes, one-hour, four-hour, seven-hour and twelve-hour recovery periods. On any given LOOP sequence one flag will be set to TRUE and the others will remain FALSE. The basic event added to the sequence when a flag is set to TRUE indicates the AC recovery failure probability for the number of hours available on that sequence.

The following operator recovery basic events less than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months were set to True (i.e.,

failed).

Conditional Nominal OEP-XHE-XL-NR30MSC Operator Fails to Recover Offsite Power in 30 Minutes True 6.02E-1 OEP-XHE-XL-NR01 HSC Operator Fails to Recover Offsite Power in 1 Hour True 4.01E-1 4.5.4 Offsite power was not considered recoverable until approximately 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after the LOOP occurred. The following operator recovery basic events greater than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months were set to the HRA conditional failure probability (Attachment D).

Conditional Nominal OEP-XHE-XL-NR04HSC Operator Fails to Recover Offsite Power in 4 Hours 7E-3 1.02E-1 OEP-XHE-XL-NR07HSC Operator Fails to Recover Offsite Power in 7 Hours 7E-3 4.65E-2 OEP-XHE-XL-NR 12HSC Operator Fails to Recover Offsite Power in 12 Hours 7E-3 1.9E-2 4.5.5 The offsite power was not considered recoverable until 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after the LOOP occurred.

The overall fail-to-run mission time for certain components is calculated as a compound event with an early and late failure time and probability input. The early nominal time is 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months , which is less than the 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months postulated recovery, thus there is no need to make any adjustments.

The following early diesel generator template basic event was not changed for the "early" input to the compound events.

ZT-DGN-FR-E (Diesel Generator Fails to Load and Run - Early)

Which did not change the "early" input to the following compound basic events:

EPS-DGN-FR-DGO (Diesel Generator 0 Fails to Run)

EPS-DGN-FR-DG2A (Diesel Generator 2A Fails to Run) 12

ASP Analysis LER 373/13-002 EPS-DGN-FR-DG28 (Diesel Generator 28 Fails to Run)

EPS-DGN-FR-DG1A (Diesel Generator 1A Fails to Run)

EPS-DGN-FR-DG18 (Diesel Generator 18 Fails to Run)

The following early turbine driven pump template basic event was not changed for the "early" input to the compound events.

ZT-TDP-FR-E (Turbine Driven Pump Fails to Run - Early)

Which did not change the "early" input to the following compound basic event:

RGI-TOP-FR-TRAIN (RCIC Pump Fails to Run Given That It Started) 4.5.6 Offsite power was not considered recoverable until 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months after the LOOP occurred.

The overall fail-to-run mission time for certain components is calculated as a compound event with an early and late failure time and probability input. The 23 hour2.662037e-4 days 0.00639 hours 3.80291e-5 weeks 8.7515e-6 months "late" nominal time of certain basic events was then changed to 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months such that the sum of the "early" time plus the "late" time for each component would add up to the 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months postulated recovery time for this LOOP event in lieu of the typical 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time.

Modeling Note: The SAP HIRE process for making this change was performed outside of the Events and Conditions Assessment (ECA) SAPHIRE Workspace. The basic event ZT-DGN-FR-L was opened from a search where the template basic event mission time was temporarily changed from 23 hours2.662037e-4 days 0.00639 hours 3.80291e-5 weeks 8.7515e-6 months to one hour. The apply button was clicked to identify the calculated probability (1.086 E-3) which was recorded on paper for later entry while in the SAPHIRE ECA workspace.

The mission time was changed back to 23 hours2.662037e-4 days 0.00639 hours 3.80291e-5 weeks 8.7515e-6 months before exiting the basic event change screen.

This same procedure was performed for ZT-TDP-FR-L (1.559 E-3). The two recorded probabilities were then entered into the template ZT basic event(s) when using the ECA workspace. The reason for this procedure is that the ECA workspace requires the entry of a probability and not a time and many analysts prefer to only make changes in the ECA workspace and never make changes to actual basic events allowing for better administration and saving of the various sensitivity scenarios run on SAPHIRE.

The following template basic event was changed from 23 hours2.662037e-4 days 0.00639 hours 3.80291e-5 weeks 8.7515e-6 months to 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months (1.086E-3) for the "late" input to the compound event, giving credit for a shorter EOG mission time and lowering the probability for failure:

Conditional Nominal ZT-DGN-FR-L (Diesel Generator Fails to Load and Run-Late) 1.086E-3 2.47E-2 Which changed the "late" input to the following calculated compound basic events:

Conditional Nominal EPS-DGN-FR-DGO (Diesel Generator 0 Fails to Run), 6.61 E-3 3.01E-2 EPS-DGN-FR-DG2A (Diesel Generator 2A Fails to Run), 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG28 (Diesel Generator 28 Fails to Run), 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG1A (Diesel Generator 1A Fails to Run), 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG1 B (Diesel Generator 18 Fails to Run), 6.61 E-3 3.01 E-2 The following template basic event was set to 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months (1.559E-3) for the "late" input to the compound event, giving credit for a shorter pump mission time and lowering the probability for failure:

13

ASP Analysis LER 373/13-002 Conditional Nominal ZT-TDP-FR-L (Turbine Driven Pump Fails to Run - Late), 1.559E-3 3.52E-2 Which changed the "late" input to the following compound basic event:

Conditional Nominal RCl-TDP-FR-TRAIN (RCIC Pump Fails to Run Given That It Started), 5.97E-3 3.95E-2 4.5.7 The SPAR model was developed with a capability to analyze both a site LOOP where offsite power was lost to both units or a single unit LOOP where the other unit not being analyzed remained with offsite power to account for shared components between the units. The following basic events were changed to identify that offsite power was lost to both units.

Conditional Nominal OEP-VCF-LP-SITESC (Site LOOP-Switchyard Related) TRUE 2.11E-1 OEP-VCF-LP-SNGLSC (Single Unit LOOP-Switchyard Related) FALSE 8.06E-1 4.5.8 The SRV failure probability to close in the LOOP model was adjusted higher to reflect the total number of primary SRV demands that were observed during the transient. A binomial expansion of the nominal failure probability based on the number of demands was calculated.

There were 26 successful open/close cycles of the SRVs (on each unit) to limit pressure after the reactor scram.

The following binomial formula was used for calculating the revised failure probability of the SRVs where:

r (failures) = 1, N (demands)= 26, and p (nominal SRV failure probability) = 8.56E-4.

N!

P[r failures in N demandslP(failure) = p] = r.1 (N _ r.)' pr(1 - p)N-r P (new SRV conditional failure probability) = 2.2E-2 Therefore, the basic events which involve one or more SRVs failing to reclose need to be adjusted. The failure probability was changed to 2.2E-2 via binomial expansion to account for the increased probability that the valves could stick open.

Conditional Nominal PPR-SRV-00-1VLV (One SRV Fails to Close), 2.2E-2 8.56E-4 ZT-BWR-SRV-00-P1 (BWR ADSJSRV Fails to Reclose) 2.2E-2 8.56E-4 Which resulted in recalculation of the following basic events:

Conditional Nominal PPR-SRV-00-2VLVS (Two or more SRVs Fails to Close) 3.5E-3 1.36E-4 PPR-SRV-00-3VLVS (Three or more SRVs Fails to Close) 1.54E-3 5.5E-5 14

ASP Analysis LER 373/13-002 4.6 Dependency Dependence exists when the occurrence of one event involving human action affects the likelihood of a second event. Dependence arises from the knowledge or lack of knowledge of the performer of the second task about the occurrence or effect of a previous task. Specifically related to the LaSalle LOOP event analyzed in this report, there were no dependencies and required no model changes for human performance for the actual event. Some Joint Human Event Probability (JHEP) dependencies in model sequences not actually occurring in this event were identified but not analyzed and not adjusted for this report.

One JHEP in the SPAR model for LaSalle, was the operator failure to depressurize the reactor to facilitate low pressure injection, following two failures to high pressure inject with RCIC and HPCS. The NRC and industry have not reached consensus for the treatment of JHEP appearing together in a cutset and any associated minimum failure probability to assign. The industry has provided examples where applying a minimum 1E-5 failure probability to JHEPs would raise a plant's CDP several orders of magnitude. Hypothetically for this analysis, assigning a high dependency under SPAR-H rules to the failure-to-depressurize operator action raises the Basic Event failure probability from 1E-3 to 5E-1, bringing the cutset failure probability to the JHEP recommended minimum of 1E-5. No modeling adjustments were made for this analysis.

The NRC has recommended a minimum JHEP of 1E-5 in the RASP, Volume 1, Section 9.4 (Reference 5.10) and also in NU REG 1792, Section 5.3.3.6, Good Practice #6: Account for Dependencies Among Post-Initiator HF Es (Reference 5.11 ). The Electric Power Research Institute (EPRI) also provides guidance on the treatment of JHEPs in a report titled: Establishing Minimum Acceptable Values for Probabilities of Human Failure Events, (Reference 5.12). An initiative to undertake incorporating a minimum JHEP in the SPAR model used for this analysis and all other SPAR models is currently under discussion. Thus, for this analysis, any two human failure events occurring in the same cutset will not be adjusted for dependency until a sound technical basis can be established.

5.0 REFERENCES

5.1 LaSalle County Station Unit 1 and 2, "LER 373/13-002- Unusual Event Declared Due to Loss of Offsite Power and Dual Unit Reactor Scram," dated July 26, 2013 (ML13207A371 ).

5.2 LaSalle County Station, Unit 2, "LER 374-2013-001 - Pin Hole Leaks Identified in High Pressure Core Spray Piping", dated June 17, 2013(ML13168A576) 5.3 LaSalle County Station Unit 1, "LER 373/13-003- Low Pressure Core Spray System Declared Inoperable Due to Faulty Control Switch" dated June 17, 2013(ML13168A577).

5.4 U.S. Nuclear Regulatory Commission, "LaSalle County Station, Units 1 and 2 - NRC Special Inspection Team (SIT) Inspection Report 05000373/2013009; 05000374/2013009,"

dated July 18, 2013(ML13199A512).

5.5 Idaho National Laboratory, NUREG/CR-6883, "The SPAR-H Human Reliability Analysis Method," August 2005 (ML051950061).

5.6 Idaho National Laboratory, "INUEXT-10-18533, SPAR-H Step-by-Step Guidance," May 2011 (ML112060305).

15

ASP Analysis LER 373/13-002 5.7 LaSalle County Station Unit 1, "LER 373/13-004-, Reactor Pressure Exceeded 150 psig With Reactor Core Isolation Cooling Inoperable" dated June 21, 2013(ML13172AA402).

5.8 LaSalle County Station Unit 1, "LER 373/13-005- Technical Specification Required Shutdown Due to Pressure Boundary Leakage," dated June 26, 2013(ML13177A278).

5.9 LaSalle County Station, Unit 2, "LER 374-2013-002 - Manual Reactor Scram Following Trip of Circulating Water Pumps", dated June 24, 2013(ML13175A229) 5.10 Risk Assessment Standardization Project (RASP) Volume 1- Internal Events, Revision 2, dated January, 2013(ML13109A518) 5.11 Good Practices for Implementing Human Reliability Analysis, NUREG 1792, dated April, 2005. (ML051160213) 5.12 Establishing Minimum Acceptable Values for Probabilities of Human Failure Events, EPRI Product ID 1021081, dated October 2010.

(http://www. epri .com/abstracts/Pages/ProductAbstract.aspx?Productld=000000000001021081) 5.13 General Design Criteria 17, 10 CFR Part 50, Appendix A Criterion 17-Electric power systems. An onsite electric power system and an offsite electric power system shall be provided to permit functioning of structures, systems, and components important to safety. The safety function for each system (assuming the other system is not functioning) shall be to provide sufficient capacity and capability to assure that (1) specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents. The onsite electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure. Electric power from the transmission network to the onsite electric distribution system shall be supplied by two physically independent circuits (not necessarily on separate rights of way) designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions.

A switchyard common to both circuits is acceptable. Each of these circuits shall be designed to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuit, to assure that specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded. One of these circuits shall be designed to be available within a few seconds following a loss-of-coolant accident to assure that core cooling, containment integrity, and other vital safety functions are maintained. Provisions shall be included to minimize the probability of losing electric power from any of the remaining supplies as a result of, or coincident with, the loss of power generated by the nuclear power unit, the loss of power from the transmission network, or the loss of power from the onsite electric power supplies.

5.14 NUREG/CR-6538, Evaluation of LOCA With Delayed LOOP and LOOP with Delayed LOCA Accident Scenarios, technical Findings Related to GSl-171, "ESF Failure from LOOP Subsequent to LOCA, dated July 1997. [ML071630062]

6.0 ATTACHMENTS A Loss of Offsite Power - Switchyard Centered Event Tree B. Unit 2 SAPHIRE Analysis Report C. Fault Tree Modifications, Swing EOG and RHR Pump 2C D. Human Reliability Analysis Worksheets 16

,,~Analysis LER 373/13-002 E. Unit 1 SAPHIRE Analysis Report F. Additional Event Details - No Effect on the ASP Analysis G. RHR Pump Breaker Closing Circuit 17

,~~P Analysis Unit 1 and Unit 2 Attachment A LER 373/13-002 Loss Of Offsite Power - Switchyard Centered Event Tree 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

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1-LOOPSC initiating event 2-RPS 3-EPS 4-SRV (P1/P2 failures) 5-HPCS 6-RCIC 7-Manual Oepressurize 8-LPI 9-Alternate LPI 10-SPC 11-Manual Depressurize 12-Shutdown Cooling 13-Containment Spray 14-Containment Venting 15-Late Injection 18

ASP Analysis Unit 2 Attachment 8 LER 373/13-002 LaSalle Unit 2 SAPHIRE Analysis Report Initiating Event IE-LOOPSC CCDP 1.SOE-5 Summary of Conditional Event Changes Event Description Cond Nominal Value Value IE-LOOP SC LOSS OF OFFSITE POWER INITIATOR 1.00E+O 1.04E-2 (SWITCHYARD- CENTERED)

OEP-VCF-LP-SITESC SITE LOOP (SWITCHYARD-RELATED) True 2.11E-1 OEP-VCF-LP-SNGLSC SINGLE UNIT LOOP (SWITCHYARD- False 8.06E-1 RELATED)

OEP-XHE-XL-NR01 HSC OPERATOR FAILS TO RECOVER OFFSITE True 4.01E-1 POWER IN 1 HOUR (SWITCHYARD)

OEP-XHE-XL-NR04HSC OPERATOR FAILS TO RECOVER OFFSITE 7.00E-3 1.02E-1 POWER IN 4 HOURS (SWITCHYARD)

OEP-XHE-XL-NR07HSC OPERATOR FAILS TO RECOVER OFFSITE 7.00E-3 4.65E-2 POWER IN 7 HOURS (SWITCHYARD)

OEP-XHE-XL-NR12HSC OPERATOR FAILS TO RECOVER OFFSITE 7.00E-3 1.90E-2 POWER IN 12 HOURS (SWITCHYARD)

OEP-XHE-XL-NR30MSC OPERATOR FAILS TO RECOVER OFFSITE True 6.02E-1 POWER IN 30 MINUTES (SWITCHYARD)

PPR-SRV-00-1VLV ONE SRV FAILS TO CLOSE 2.20E-2 8.56E-4 RHR-MDP-SEQU ENC ER RHR PUMP C UNAVAILABLE DUE TO LACK True O.OOE+O OF TIME DELAY (EDG SEQUENCER)

ZT-BWR-SRV-00-P 1 BWR ADS/SRV Fails To Reclose 2.20E-2 8.56E-4 ZT-DGN-FR-L Diesel Generator Fails To Run 1.09E-3 2.47E-2 ZT-TDP-FR-L Turbine Driven Pump Fails To Run 1.56E-3 3.52E-2 PPR-SRV-00-2VLVS TWO OR MORE SRVS FAIL TO CLOSE 3.50E-3 1.36E-4 PPR-SRV-00-3VLVS THREE OR MORE SRVS FAIL TO CLOSE 1.54E-3 5.50E-5 EPS-DGN-FR-DGO DIESEL GENERATOR 0 FAILS TO RUN 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG2A DIESEL GENERATOR 2A FAILS TO RUN 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG2B DIESEL GENERATOR 28 FAILS TO RUN 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG1A DIESEL GENERATOR 1A FAILS TO RUN 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG1 B DIESEL GENERATOR 18 FAILS TO RUN 6.61 E-3 3.01 E-2 ZT-BWR-SRV-OO-P2 BWR TWO ADS/SRVS FAIL TO RECLOSE 3.50E-3 1.36E-4 ZT-BWR-SRV-OO-P3 BWR THREE OR MORE ADS/SRVS FAIL TO 1.54E-3 5.50E-5 REC LOSE RCl-TDP-FR-TRAIN RCIC PUMP FAILS TO RUN GIVEN THAT IT 5.97E-3 3.95E-2 STARTED Dominant Sequence Results Only items contributing at least 1.0% to the total CCDP are displayed.

Sequence % Description 43-34-09 24.3% /RPS, EPS, P2, HCS-SBO, /RCl-SBO, OPR-01 H, DGR-01 H 19

ASP Analysis Unit 2 Attachment B LER 373/13-002 Sequence % Description 42-13 24.2% /RPS, /EPS, P2, HCS, LPI 43-31 16.4% /RPS, EPS, /SRV, /RPSL, HCS-SBO, RCl-SBO, OPR-30M, DGR-30M 07 10.2% /RPS, /EPS, /SRV, /HCS, SPC, /DEP, SOC, CSS, CVS, LI-VENT-FAILURE 43-33-15 5.9% /RPS, EPS, P1, HCS-SBO, RCl-SBO 40 5.7% /RPS, /EPS, /SRV, HCS, RCI, DEP 42-12 3.7% /RPS, /EPS, P2, HCS, /LPI, SPC, CSS, CVS, LI-VENT-FAILURE 43-32-15 1.8% /RPS, EPS, /SRV, RPSL, HCS-SBO, RCl-SBO 43-34-10 1.4% /RPS, EPS, P2, HCS-SBO, RCl-SBO 39 1.3% /RPS, /EPS, /SRV, HCS, RCI, /DEP, LPI, VA 100.0%

Referenced Fault Trees Fault Tree Description css CONTAINMENT SPRAY CVS CONTAINMENT VENTING DEP MANUAL REACTOR DEPRESS DGR-01H DIESEL GENERATOR RECOVERY (1 HOUR)

DGR-30M DIESEL GENERATOR RECOVERY (30 MINUTES)

EPS EMERGENCY POWER HCS HPCS HCS-SBO HPCS LI-VENT-FAILURE LATE INJECTION FOLLOWING VENTILATION FAILURE LPI LOW PRESSURE INJECTION OPR-01H OFFSITE POWER RECOVERY (1 HOUR)

OPR-30M OFFSITE POWER RECOVERY (30 MINUTES)

P1 ONE SORV P2 TWO OR MORE SORVs RCI RCIC RCl-SBO RCIC FAILS DURING STATION BLACKOUT RPSL RECIRC PUMP SEAL INTEGRITY soc SHUTDOWN COOLING SPC SUPPRESSION POOL COOLING VA ALTERNATE LOW PRESS INJECTION Cut Set Report - LOOPSC 43-34-09 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 3.64E-6 100 Displaying 2104 Cut Sets. (2104 Original) 1 6.28E-7 17.26 IE-LOOPSC,EPS-DGN-TM-DG1 B,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01 H,PPR-SRV-00-2VLVS 2 2.89E-7 7.95 IE-LOOPSC,EPS-DGN-FR-DG2A,EPS-DGN-TM-DG1B,EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 3 2.89E-7 7.95 IE-LOOPSC, EPS-DGN-FR-DG1 B, EP S-DGN-TM-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 20

Analysis Unit 2 Attachment 8 1...ER 373/13-002

CCDP Total% Cut Set 4 2.76E-7 7.58 IE-LOOP SC, EPS-DGN-TM-DG18,EPS-DGN-TM-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 5 2.67E-7 7.33 IE-LOOP SC, EPS-DGN-FR-DG18, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS, SCW-MDP-TM-DG2A 6 1.33E-7 3.66 IE-LOOPSC, EPS-DGN-FR-DG18, EPS-DGN-FR-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 7 1.27E-7 3.49 IE-LOOPSC, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG 18, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 8 1.27E-7 3.49 IE-LOOPSC, EPS-DGN-FR-DG18, EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 9 1.27E-7 3.48 IE-LOOPSC, EPS-DGN-FS-DG2A, EPS-DGN-TM-DG18, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 10 1.27E-7 3.48 IE-LOOP SC, EPS-DGN-FS-DG18, EPS-DGN-TM-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 11 1.17E-7 3.22 IE-LOOPSC, EPS-DGN-FR-DG18,EPS-XHE-XL-NR01 H,PPR-SRV-00-3VLVS,SCW-MDP-TM-DG2A 12 1.17E-7 3.21 IE-LOOP SC, EPS-DGN-FS-DG18, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS, SCW-MDP-TM-DG2A 13 5.84E-8 1.61 I E-LOOPSC, EPS-DGN-FR-DG 18, EPS-DGN-FR-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 14 5.82E-8 1.60 I E-LOOPSC, EPS-DGN-FR-DG2A, EPS-DGN-FS-DG 18, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 15 5.82E-8 1.60 IE-LOOPSC,EPS-DGN-FR-DG18,EPS-DGN-FS-DG2A,EPS-XHE-XL-NR01H,PPR-SRV-00-2VLVS 16 5.55E-8 1.53 I E-LOOPSC, EPS-DGN-FS-DG2A, EPS-DGN-TM-DG 18, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 17 5.55E-8 1.53 IE-LOOP SC, EPS-DGN-FS-DG18, EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 18 5.12E-8 1.41 IE-LOOPSC, EPS-DGN-FS-DG18, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS, SCW-MDP-TM-DG2A 19 4.38E-8 1.20 IE-LOOPSC,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01 H,EPS-XHE-XR-DG1 B,PPR-SRV-00-2VLVS 20 4.15E-8 1.14 IE-LOOPSC, EPS-DGN-TM-DG18,EPS-XHE-XL-NR01 H,PPR-SRV-00-2VLVS,SCW-MDP-FS-DG2A 21 4.04E-8 1.11 IE-LOOPSC, EPS-XHE-XL-NR01 H, EPS-XHE-XR-DG18, PPR-SRV-00-2VLVS, SCW-MDP-TM-DG2A 22 3.96E-8 1.09 IE-LOOP SC, EPS-DGN-CF-R4, EPS-XH E-XL-NR01 H, PPR-SRV-00-2VLVS Cut Set Report - LOOPSC 42-13 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 3.62E-6 100 Displaying 2522 Cut Sets. (2522 Original) 1 2.84E-7 7.85 IE-LOOP SC, EPS-DGN-TM-DG18,PPR-SRV-00-2VLVS, RHR-MDP-TM-28 2 2.62E-7 7.24 IE-LOOP SC, PPR-SRV-00-2VL VS, RHR-MDP-TM-28,SCW-MDP-TM-21

. .J~ Analysis Unit 2 Attachment 8 LER 373/13-002 CCDP

Total% Cut Set DG28 3 1.35E-7 3.73 IE-LOOPSC, HCS-MDP-TM-HPCS, PPR-SRV-00-2VL VS, RHR-MDP-TM-28 4 1.25E-7 3.45 1E-LOOPSC,EPS-DGN-TM-DG18,PPR-SRV-00-3VLVS,RHR-MDP-TM-28 5 1.15E-7 3.18 IE-LOOP SC, PPR-SRV-00-3VL VS, RHR-MDP-TM-28, SCW-MDP-TM-DG28 6 1.00E-7 2.77 IE-LOOP SC, EPS-DGN-TM-DG 18,PPR-SRV-00-2VLVS,RHR-FAN-TM-BC 7 9.27E-8 2.56 IE-LOOPSC, PPR-SRV-00-2VLVS, RHR-F AN-TM-BC, SCW-MDP-TM-DG28 8 5.94E-8 1.64 IE-LOOPSC, HCS-MOV-FT-SUCTR, PPR-SRV-00-2VlVS, RHR-MDP-TM-28 9 5.93E-8 1.64 IE-LOOPSC, HCS-MDP-TM-HPCS, PPR-SRV-00-3VLVS, RHR-MDP-TM-28 10 5.73E-8 1.58 IE-LOOPSC, EPS-DGN-FS-DG1 B, PPR-SRV-00-2VLVS,RHR-MDP-TM-28 11 5.02E-8 1.39 IE-LOOP SC, EPS-DGN-TM-DG 18,PPR-SRV-00-2VLVS,SCW-XHE-TM-RHR8 12 4.84E-8 1.34 IE-LOOPSC, EPS-DGN-TM-DG 18, LCl-MOV-CC-42B, PPR-SRV 2VLVS 13 4.84E-8 1.34 IE-LOOPSC, EPS-DGN-TM-DG1 B,PPR-SRV-00-2VLVS, RHR-MOV-CC-MlNF8 14 4.77E-8 1.32 IE-LOOPSC, HCS-MDP-TM-HPCS, PPR-SRV-00-2VLVS, RHR-FAN-TM-BC 15 4.76E-8 1.31 IE-LOOP SC, EPS-DGN-TM-DG1 B, PPR-SRV-00-2VL VS, RHR-MDP-FS-2B 16 4.74E-8 1.31 IE-LOOPSC, HCS-CRB-00-MDP, PPR-SRV-00-2VL VS, RHR-MDP-TM-28 17 4.63E-8 1.28 IE-LOOPSC, PPR-SRV-00-2VL VS, SCW-MDP-TM-DG2B,SCW-XHE-TM-RHRB 18 4.46E-8 1.23 IE-LOOPSC, PPR-SRV-00-2VL VS, RHR-MOV-CC-MI NFB,SCW-MDP-TM-DG2B 19 4.46E-8 1.23 IE-LOOPSC, LCl-MOV-CC-428, PPR-SRV-00-2VL VS, SCW-MDP-TM-DG2B 20 4.41 E-8 1.22 IE-LOOPSC, EPS-DGN-TM-DG18, PPR-SRV-00-3VLVS, RHR-F AN-TM-BC 21 4.39E-8 1.21 IE-LOOPSC, PPR-SRV-00-2VL VS, RHR-MDP-FS-28, SCW-MDP-TM-DG28 22 4.23E-8 1.17 IE-LOOPSC,EPS-DGN-TM-DG18,PPR-SRV-00-2VLVS,RHR-FAN-FS-BC 23 4.07E-8 1.12 IE-LOOP SC, PPR-SRV-00-3VLVS, RHR-FAN-TM-BC,SCW-MDP-TM-DG28 24 3.96E-8 1.09 IE-LOOPSC,HCS-FAN-TM-ROOM, PPR-SRV-00-2VL VS, RHR-MDP-TM-2B 25 3.90E-8 1.08 IE-LOOPSC, PPR-SRV-00-2VL VS, RHR-FAN-FS-8C, SCW-MDP-TM-DG28 Cut Set Report - LOOPSC 43-31 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 2.46E-6 100 Displaying 30480 Cut Sets. (30480 Original) 22

ASP Analysis Unit 2 Attachment B LER 373/13-002

CCDP Total% Cut Set 1 2.38E-7 9.68 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-CF-R4,EPS-XHE-XL-NR30M 2 1.30E-7 5.30 IE-LOOPSC,EPS-DGN-CF-R4,EPS-XHE-XL-NR30M,RCl-TDP-TM-TRAIN 3 8.72E-8 3.55 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-CF-S4, EPS-XHE-XL-NR30M 4 7.73E-8 3.14 IE-LOOPSC,EPS-DGN-CF-R4,EPS-XHE-XL-NR30M,RCl-TDP-FS-TRAIN 5 7.11E-8 2.89 IE-LOOPSC,EPS-DGN-CF-R4,EPS-XHE-XL-NR30M,RCl-TDP-FR-TRAIN 6 4.77E-8 1.94 IE-LOOPSC,EPS-DGN-CF-S4,EPS-XHE-XL-NR30M,RCl-TDP-TM-TRAIN 7 4.25E-8 1.73 IE-LOOPSC,DCP-BAT-CF-ALL,EPS-XHE-XL-NR30M 8 3.57E-8 1.45 IE-LOOPSC, EPS-DGN-CF-R4, EPS-XH E-XL-NR30M, RC I-RESTART, RCI-TDP-FS-RSTRT,RCl-XHE-XL-RSTRT 9 2.83E-8 1.15 IE-LOOPSC, EPS-DGN-CF-S4, EPS-XH E-XL-NR30M, RCl-TDP-FS-TRAI N 10 2.60E-8 1.06 IE-LOOPSC, EPS-DGN-CF-S4, EPS-XHE-XL-N R30M, RCl-TDP-FR-TRAI N 11 2.50E-8 1.02 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DGO,EPS-DGN-TM-DG1 B, EPS-DGN-TM-DG2A,EPS-XHE-XL-NR30M 12 2.50E-8 1.02 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG1A,EPS-DGN-TM-DG1 B,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR30M 13 2.50E-8 1.02 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DG 1B, EPS-DGN-TM-DGO, EPS-DGN-TM-DG2A, EPS-XHE-XL-NR30M 14 2.50E-8 1.02 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG1 B,EPS-DGN-TM-DG1A,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR30M Cut Set Report - LOOPSC 07 Only items contributing at least 1% to the total are displayed.

CCDP Total% CutSet 1.52E-6 100 Displaying 30157 Cut Sets. (30157 Original) 6.45E-8 4.23 IE-LOOPSC,CRD-XHE-XM-PUMP,CTM-DW-BODY-FAILURE,CVS-MOV-TM-PURGE,RHR-XHE-XM-ERROR 2 4.89E-8 3.21 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DGO,OEP-XHE-XL-NR 12HSC, RHR-MDP-TM-28 3 2.24E-8 1.47 IE-LOOPSC,ACP-BAC-TM-241 Y, CTM-DW-BODY-FAILURE,SCW-MOV-TM-F068B 4 2.15E-8 1.41 IE-LOOPSC,CRD-XHE-XM-PUMP,CTM-DW-BODY-FAILURE,CVS-XHE-XM-VENT,RHR-XHE-XM-ERROR 5 2.03E-8 1.33 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DGO,OEP-XHE-XL-NR12HSC,RHR-HTX-TM-HTXB 6 1.88E-8 1.23 IE-LOOPSC,CTM-DW-BODY-FAILURE,OEP-XHE-XL-NR12HSC,RHR-HTX-TM-HTXB, SCW-MDP-TM-DGO 7 1.73E-8 1.13 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DGO,OEP-XHE-XL-NR12HSC,RHR-FAN-TM-BC 8 1.72E-8 1.13 IE-LOOPSC,ACP-BAC-TM-241Y,CTM-DW-BODY-FAILURE,SCW-XHE-TM-RH RB 9 1.70E-8 1.12 IE-LOOPSC,ACP-XH E-XM-DGO, CTM-DW-BODY-FAI LURE, FLAG-DGO-ALIGNED-AWAY,OEP-XHE-XL-NR12HSC,RHR-MDP-TM-2B 10 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-241Y,CTM-DW-BODY-FAILURE,RHR-MOV-CC-MINFB 23

ASP Analysis Unit 2 Attachment B LER 373/13-002

CCDP Total% Cut Set 11 1.66E-8 1.09 IE-LOOPSC,ACP-8AC-TM-241Y,CTM-DW-80DY-FAILURE,SCW-MOV-CC-688 12 1.66E-8 1.09 IE-LOOPSC,ACP-8AC-TM-241Y,CTM-DW-80DY-FAILURE,RHR-MOV-CC-F0038 13 1.66E-8 1.09 IE-LOOPSC,ACP-8AC-TM-241 Y, CTM-DW-80DY-FAI LURE, RHR-MOV-00-8YPS8 14 1.66E-8 1.09 IE-LOOPSC,ACP-8AC-TM-242Y, CTM-DW-80DY-FAI LURE, SCW-MOV-CC-68A 15 1.66E-8 1.09 IE-LOOPSC,ACP-8AC-TM-242Y, CTM-DW-80DY-FAI LU RE, RH R-MOV-CC-MINFA 16 1.66E-8 1.09 IE-LOOPSC,ACP-8AC-TM-242Y, CTM-DW-80DY-FAI LU RE, RHR-MOV-CC-F003A 17 1.66E-8 1.09 IE-LOOPSC,ACP-8AC-TM-242Y, CTM-DW-80DY-FAI LU RE, RH R-MOV-00-8YPSA 18 1.63E-8 1.07 IE-LOOPSC,ACP-8AC-TM-241Y,CTM-DW-80DY-FAILURE,RHR-MDP-FS-28 19 1.63E-8 1.07 IE-LOOPSC,ACP-8AC-TM-242Y,CTM-DW-80DY-FAILURE,RHR-MDP-FS-2A 20 1.62E-8 1.06 IE-LOOPSC,ACP-8AC-LP-241 Y, CTM-DW-80DY-FAI LURE, RH R-M DP-TM-28 21 1.62E-8 1.06 IE-LOOPSC,ACP-8AC-LP-242Y, CTM-DW-80DY-FAI LU RE, RHR-MDP-TM-2A 22 1.59E-8 1.05 IE-LOOPSC,CTM-DW-80DY-FAILURE,OEP-XHE-XL-NR12HSC,RHR-FAN-TM-8C,SCW-MDP-TM-DGO Cut Set Report - LOOPSC 43-33-15 Only items contributing at least 1% to the total are displayed.

CCDP Total% CutSet 8.88E-7 100 Displaying 6347 Cut Sets. (6347 Original) 9.06E-8 10.20 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-TM-DG18,EPS-DGN-TM-DG2A,PPR-SRV-00-1VLV 2 4.17E-8 4.70 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG18,PPR-SRV-00-1VLV 3 4.17E-8 4.70 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG18,EPS-DGN-TM-DG2A,PPR-SRV-00-1VLV 4 3.85E-8 4.33 IE-LOOP SC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG18, PPR-SRV-00-1VLV,SCW-MDP-TM-DG2A 5 2.94E-8 3.31 IE-LOOPSC, EPS-DGN-TM-DG18, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-FS-TRAIN 6 2.70E-8 3.04 IE-LOOPSC,EPS-DGN-TM-DG18,EPS-DGN-TM-DG2A,PPR-SRV-OO-1VLV,RCl-TDP-FR-TRAIN 7 2.28E-8 2.57 IE-LOOPSC, EPS-DGN-FR-DG18, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-TM-TRAIN 8 2.11 E-8 2.37 IE-LOOPSC,EPS-DGN-FR-DG18,PPR-SRV-00-1VLV,RCl-TDP-TM-TRAIN,SCW-MDP-TM-DG2A 9 1.92E-8 2.16 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG18,EPS-DGN-FR-DG2A, PPR-SRV-00-1 VLV 24

ASP Analysis Unit 2 Attachment B LER 373/13-002

CCDP Total% Cut Set 10 1.83E-8 2.06 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FS-DG2A, EP S-DGN-TM-DG1B,PPR-SRV-00-1VLV 11 1.83E-8 2.06 IE-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-FS-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-1 VLV 12 1.68E-8 1.90 IE-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-FS-DG1 B, PPR-SRV-00-1VLV,SCW-MDP-TM-DG2A 13 1.36E-8 1.53 IE-LOOPSC,EPS-DGN-TM-DG1B,EPS-DGN-TM-DG2A,PPR-SRV-OO-1VLV,RCl-RESTART,RCl-TDP-FS-RSTRT,RCl-XHE-XL-RSTRT 14 1.35E-8 1.52 IE-LOOPSC,EPS-DGN-FR-DG1B,EPS-DGN-TM-DG2A,PPR-SRV-OO-1VLV,RCl-TDP-FS-TRAIN 15 1.35E-8 1.52 IE-LOOPSC,EPS-DGN-FR-DG2A,EPS-DGN-TM-DG1B,PPR-SRV-OO-1VLV,RCl-TDP-FS-TRAIN 16 1.25E-8 1.41 IE-LOOP SC, EPS-DGN-FR-DG1 B, PPR-SRV-00-1 VLV, RCl-TDP-FS-TRAIN,SCW-MDP-TM-DG2A 17 1.24E-8 1.40 IE-LOOP SC, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-FR-TRAIN 18 1.24E-8 1.40 IE-LOOP SC, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG1 B, PPR-SRV 1VLV,RCl-TDP-FR-TRAIN 19 1.15E-8 1.29 IE-LOOP SC, EPS-DGN-FR-DG1 B, PPR-SRV-00-1VLV, RCl-TDP-FR-TRAIN,SCW-MDP-TM-DG2A 20 1.05E-8 1.18 IE-LOOPSC, EPS-DGN-FR-DG1 B, EPS-DGN-FR-DG2A, PPR-SRV 1VLV,RCl-TDP-TM-TRAIN 21 9.99E-9 1.13 IE-LOOPSC, EPS-DGN-FS-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-TM-TRAIN 22 9.22E-9 1.04 IE-LOOPSC, EPS-DGN-FS-DG1 B, PPR-SRV-00-1VLV, RC I-TOP-TM-TRAIN,SCW-MDP-TM-DG2A 23 9.02E-9 1.02 IE-LOOPSC,EPS-DGN-TM-DG1B,EPS-DGN-TM-DG2A,PPR-SRV-OO-1VLV, RCl-MOV-FC-XFER, RCl-XHE-XL-XFER Cut Set Report - LOOPSC 40 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 8.57E-7 100 Displaying 5616 Cut Sets. (5616 Original) 1 7.19E-8 8.38 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-XHE-XO-ERROR 1, RCl-XHE-XO-ERROR 2 4.66E-8 5.44 I E-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-TM-DG 1B, RCl-TDP-FS-TRAl N 3 4.30E-8 5. 02 I E-LOOPSC,ADS-XHE-XM-MDEPR, RCl-TDP-FS-TRAI N, SCW-MDP-TM-DG2B 4 4.28E-8 5.00 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-TM-DG1 B, RCl-TDP-FR-TRAIN 5 3.95E-8 4.61 I E-LOOPSC,ADS-XHE-XM-MDEPR, RCl-TDP-FR-TRAI N, SCW-MDP-TM-DG2B 6 3.62E-8 4.22 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FR-DG1 B, RCl-TDP-TM-TRAIN 7 2.21 E-8 2. 58 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-MDP-TM-HPCS, RCl-TDP-FS-TRAIN 25

.JI:" Analysis Unit 2 Attachment B LER 373/13-002

CCDP Total% Cut Set 8 2.15E-8 2.51 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-TM-DG 18, RCI-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 9 2.14E-8 2.50 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FR-DG18, RCl-TDP-FS-TRAIN 10 2.03E-8 2.37 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-MDP-TM-HPCS, RC I-TOP-FR-TRAIN 11 1.99E-8 2.32 IE-LOOPSC,ADS-XHE-XM-MDEPR, RCl-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT,SCW-MDP-TM-DG28 12 1.97E-8 2.30 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FR-DG 18, RCl-TDP-FR-TRAIN 13 1.64E-8 1.92 IE-LOOPSC,ADS-XHE-XM-MDEPR,HCS-MOV-FT-SUCTR,RCl-TDP-TM-TRAIN 14 1.58E-8 1.85 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FS-DG 18, RC I-TOP-TM-TRAIN 15 1.43E-8 1.67 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-TM-DG 18, RCl-MOV-FC-XFER,RCl-XHE-XL-XFER 16 1.32E-8 1.54 IE-LOOPSC,ADS-XHE-XM-MDEPR,RCl-MOV-FC-XFER,RCl-XHE-XL-XFER,SCW-MDP-TM-DG2B 17 1.31 E-8 1.53 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-CRB-00-MDP, RCl-TDP-TM-TRAIN 18 1.10E-8 1.28 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-FAN-TM-ROOM, RC I-TOP-TM-TRAIN 19 1.02E-8 1.19 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-MDP-TM-HPCS, RCI-REST ART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 20 9.91E-9 1.16 IE-LOOPSC ,ADS-XHE-XM-MDEPR, EPS-DGN-FR-DG 18, RCI-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 21 9.74E-9 1.14 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-MOV-FT-SUCTR, RCl-TDP-FS-TRAIN 22 9.39E-9 1.10 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FS-DG 1B, RCl-TDP-FS-TRAIN 23 8.95E-9 1.04 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-MOV-FT-SUCTR, RCl-TDP-FR-TRAIN 24 8.63E-9 1.01 IE-LOOPSC,ADS-XHE-XM-MDEPR,EPS-DGN-FS-DG1 B, RC I-TOP-FR-TRAIN Cut Set Report - LOOPSC 42-12 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 5.49E-7 100 Displaying 14851 Cut Sets. (14851 Original) 1 2.45E-8 4.46 IE-LOOPSC,CTM-DW-80DY-FAILURE, EPS-DGN-TM-DG1 B, PPR-SRV-00-2VL VS, RH R-MDP-TM-28 2 2.26E-8 4.11 IE-LOOPSC,CTM-DW-BODY-FAILURE,PPR-SRV-00-2VLVS,RHR-MDP-TM-28,SCW-MDP-TM-DG2B 3 1.16E-8 2.12 IE-LOOPSC, CTM-DW-80DY-FAI LURE, HCS-MDP-TM-HPCS, PPR-SRV-00-2VL VS, RHR-MDP-TM-28 4 1.07E-8 1.96 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DG18,PPR-SRV-00-3VLVS, RH R-MDP-TM-28 26

ASP Analysis Unit 2 Attachment B LER 373/13-002

CCDP Total% Cut Set 5 1.02E-8 1.85 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DG1B,PPR-SRV-00-2VLVS, RHR-HTX-TM-HTXB 6 9.90E-9 1.81 IE-LOOPSC,CTM-DW-BODY-FAILURE,PPR-SRV-00-3VLVS,RHR-MDP-TM-2B,SCW-MDP-TM-DG2B 7 9.39E-9 1.71 IE-LOOPSC,CTM-DW-BODY-FAILURE,PPR-SRV-00-2VLVS,RHR-HTX-TM-HTXB,SCW-MDP-TM-DG2B 8 5.62E-9 1.02 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DG18,PPR-SRV-00-2VLVS, SCW-MOV-TM-F068B Cut Set Report - LOOPSC 43-32-15 Only items contributing at least 1% to the total are displayed.

CC DP Total% Cut Set 2.67E-7 100 Displaying 13460 Cut Sets. (13460 Original) 1 2.59E-8 9.72 IE-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-CF-R4, RRS-MDP-LK-SEALS 2 1.42E-8 5.32 IE-LOOPSC,EPS-DGN-CF-R4,RCl-TDP-TM-TRAIN,RRS-MDP-LK-SEALS 3 9.50E-9 3.56 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-CF-S4, RRS-MDP-LK-SEALS 4 8.42E-9 3.16 I E-LOOPSC, EPS-DGN-*CF-R4, RCl-TDP-FS-TRAIN, RRS-MDP-LK-SEALS 5 7.74E-9 2.90 I E-LOOPSC, EPS-DGN-CF-R4, RCl-TDP-FR-TRAIN, RRS-MDP-LK-SEALS 6 5.20E-9 1.95 I E-LOOPSC, EPS-DGN-CF-S4, RCl-TDP-TM-TRAI N, RRS-MDP-LK-SEALS 7 4.63E-9 1.73 I E-LOOPSC, DCP-BAT-CF-ALL, RRS-MDP-LK-SEALS 8 3.89E-9 1.46 IE-LOOP SC, EPS-DGN-CF-R4, RGI-RESTART, RCl-TDP-FS-RSTRT, RCI-XHE-XL-RSTRT,RRS-MDP-LK-SEALS 9 3.08E-9 1.16 IE-LOOP SC, EPS-DGN-CF-84, RCl-TDP-FS-TRAIN, RRS-MDP-LK-SEALS 10 2.83E-9 1.06 IE-LOOPSC,EPS-DGN-CF-S4,RCl-TDP-FR-TRAIN,RRS-MDP-LK-SEALS 11 2.72E-9 1.02 IE-LOOP SC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG 1A, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, RRS-MDP-LK-SEALS 12 2.72E-9 1.02 I E-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DGO, EPS-DGN-TM-DG1 B, EPS-DGN-TM-DG2A,RRS-MDP-LK-SEALS 13 2.72E-9 1.02 IE-LOOP SC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DGO, EPS-DGN-TM-DG2A, RRS-MDP-LK-SEALS 14 2.72E-9 1.02 I E-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG 1A, EPS-DGN-TM-DG2A, RRS-MDP-LK-SEALS Cut Set Report - LOOP SC 43-34-10 Only items contributing at least 1% to the total are displayed.

CCDP Total% CutSet 2.03E-7 100 Displaying 6784 Cut Sets. (6784 Original) 1.44E-8 7.10 I E-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV-00-2VLVS 2 6.64E-9 3.27 IE-LOOP SC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-2VLVS 3 6.64E-9 3.27 IE-LOOP SC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG18, PPR-SRV-00-2VLVS 4 6.33E-9 3.12 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-TM-DG18,EPS-DGN-27

ASP Analysis Unit 2 Attachment B LER 373/13-002

CCDP Total% Cut Set TM-DG2A, PPR-SRV-00-3VLVS 5 6.12E-9 3.02 IE-LOOPSC, DC P-XHE-XM-STRI P30M, EPS-DGN-FR-DG 1B, PPR-SRV-00-2VL VS, SCW-MDP-TM-DG2A 6 4.68E-9 2.31 I E-LOOPSC, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV 2VLVS,RCl-TDP-FS-TRAIN 7 4.30E-9 2.12 IE-LOOPSC, EPS-DGN-TM-DG 1B, E PS-DGN-TM-DG2A, PPR-SRV 2VLVS,RCl-TDP-FR-TRAIN 8 3.63E-9 1.79 IE-LOOPSC,EPS-DGN-FR-DG1 B,EPS-DGN-TM-DG2A,PPR-SRV-OO-2VLVS,RCl-TDP-TM-TRAIN 9 3.35E-9 1.65 IE-LOOPSC,EPS-DGN-FR-DG1B,PPR-SRV-00-2VLVS,RCl-TDP-TM-TRAIN,SCW-MDP-TM-DG2A 10 3.05E-9 1.50 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG1 B,EPS-DGN-FR-DG2A, PPR-SRV-00-2VLVS 11 2.91 E-9 1.43 IE-LOOP SC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-3VLVS 12 2.91 E-9 1.43 I E-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG1 B, PPR-SRV-00-3VLVS 13 2.90E-9 1.43 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FS-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV-00-2VLVS 14 2.90E-9 1.43 I E-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FS-DG2A, EPS-DGN-TM-DG1 B,PPR-SRV-00-2VLVS 15 2.69E-9 1.32 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG1B,PPR-SRV-00-3VLVS,SCW-MDP-TM-DG2A 16 2.68E-9 1.32 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FS-DG1 B,PPR-SRV-00-2VL VS, SCW-M DP-TM-DG2A 17 2.16E-9 1.07 IE-LOOPSC,EPS-DGN-TM-DG1B,EPS-DGN-TM-DG2A,PPR-SRV-OO-2VLVS,RCl-RESTART,RCl-TDP-FS-RSTRT,RCl-XHE-XL-RSTRT 18 2.15E-9 1.06 I E-LOOPSC, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG 1B, PPR-SRV 2VL VS, RCl-TDP-FS-TRAI N 19 2.15E-9 1.06 IE-LOOPSC,EPS-DGN-FR-DG1B,EPS-DGN-TM-DG2A,PPR-SRV-OO-2VLVS,RCl-TDP-FS-TRAIN 20 2.05E-9 1.01 I E-LOOPSC, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV 3VL VS, RCl-TDP-FS-TRAI N Referenced Events Event Description Probability ACP-BAC-LP-241 Y 4160 V BUS 241Y HARDWARE FAILURES 3.33E-5 ACP-BAC-LP-242Y 4160 V BUS 242Y HARDWARE FAILURES 3.33E-5 ACP-BAC-TM-241 Y 4160 V BUS 241Y IN MAINTENANCE (PSA) 2.00E-4 ACP-BAC-TM-242Y 4160 V BUS 242Y IN MAINTENANCE (PSA) 2.00E-4 ACP-XHE-XM-DGO OPERATOR FAILS TO ALIGN DGO TO DIV-1BUS241Y 1.00E-2 ADS-XHE-XM-MDEPR OPERATOR FAILS TO DEPRESSURIZE THE REACTOR 5.00E-4 CRD-XHE-XM-PUMP OPERATOR FAILS TO START THE STANDBY PUMP 5.00E-1 CTM-DW-BODY-FAILURE CATASTROPHIC CONTAINMANT DW BODY FAILURE 8.60E-2 CAUSES LOSS OF INJECTION CVS-MOV-TM-PURGE CONTAINMENT VENT/PURGE SYSTEM IN 3.00E-3 MAINTENANCE (PSA) 28

ASP Analysis Unit 2 Attachment B LER 373/13-002 CVS-XHE-XM-VENT OPERATOR FAILS TO VENT CONTAINMENT 1.00E-3 DCP-BAT-CF-ALL CCF OF 125VDC BATTERYS (3) 4.63E-8 DCP-XHE-XM-STRIP30M OPERATOR FAILS TO SHED 125 voe NON-ESSENTIAL 2.00E-2 LOADS EPS-DGN-CF-R4 CCF OF FOUR DIESEL GENERATORS TO RUN 1.30E-5 EPS-DGN-CF-S4 CCF OF ALL FOUR DIESEL GENERATORS TO START 4.75E-6 EPS-DGN-FR-DGO DIESEL GENERATOR 0 FAILS TO RUN 6.61 E-3 EPS-DGN-FR-DG1A DIESEL GENERATOR 1A FAILS TO RUN 6.61 E-3 EPS-DGN-FR-DG1 B DIESEL GENERATOR 18 FAILS TO RUN 6.61 E-3 EPS-DGN-FR-DG2A DIESEL GENERATOR 2A FAILS TO RUN 6.61 E-3 EPS-DGN-FS-DG1 B DIESEL GENERATOR 1B FAILS TO START 2.89E-3 EPS-DGN-FS-DG2A DIESEL GENERATOR 2A FAILS TO START 2.89E-3 EPS-DGN-TM-DGO DIESEL GENERATOR 0 UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-DGN-TM-DG1A DIESEL GENERATOR 1A UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-DGN-TM-DG1 B DIESEL GENERATOR 1B UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-DGN-TM-DG2A DIESEL GENERATOR 2A UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-XHE-XL-NR01 H OPERATOR FAILS TO RECOVER EMERGENCY DIESEL 8.71 E-1 IN 1 HOUR EPS-XHE-XL-NR30M OPERATOR FAILS TO RECOVER EMERGENCY DIESEL 9.18E-1 IN 30 MINUTES EPS-XHE-XR-DG1 B OPERATOR FAILS TO RESTORE DG1 B AFTER 1.00E-3 MAINTENANCE FLAG-DGO-ALIGNED- DGO ALIGNED TO U1 INITIALLY 5.00E-1 AWAY HCS-CRB-00-MDP HCS MOP 4.1kV CBRKR FAILS TO CLOSE (PSA) 2.39E-3 HCS-FAN-TM-ROOM HPCS ROOM COOLER FAN UNAVAILABLE DUE TO T&M 2.00E-3 HCS-MDP-TM-HPCS HPCI TRAIN IS UNAVAILABLE BECAUSE OF 6.82E-3 MAINTENANCE HCS-MOV-FT-SUCTR HPCS SUCTION TRANSFER FAILS 3.00E-3 HCS-XHE-XO-ERROR 1 OPERATOR FAILS TO START/CONTROL HPCS 1.44E-1 INJECTION IE-LOOPSC LOSS OF OFFSITE POWER INITIATOR (SWITCHYARD- 1.00E+O CENTERED)

LCl-MOV-CC-42B LPCI INJECTION MOV 42B FAILS TO OPEN 9.63E-4 OEP-XHE-XL-NR12HSC OPERATOR FAILS TO RECOVER OFFSITE POWER IN 12 7.00E-3 HOURS (SWITCHYARD)

PPR-SRV-00-1VLV ONE SRV FAILS TO CLOSE 2.20E-2 PPR-SRV-00-2VLVS TWO OR MORE SRVS FAIL TO CLOSE 3.50E-3 PPR-SRV-00-3VLVS THREE OR MORE SRVS FAIL TO CLOSE 1.54E-3 RCl-MOV-FC-XFER RCIC FAILS TO TRANSFER DURING RECIRCULATION 7.97E-3 RGI-RESTART RESTART OF RCIC IS REQUIRED 1.50E-1 RCl-TDP-FR-TRAIN RCIC PUMP FAILS TO RUN GIVEN THAT IT STARTED 5.97E-3 RCl-TDP-FS-RSTRT RCIC FAILS TO RESTART GIVEN START AND SHORT- 8.00E-2 TERM RUN 29

,,r- Analysis Unit 2 Attachment B LER 373/13-002 RCl-TDP-FS-TRAIN RCIC PUMP FAILS TO START 6.49E-3 RCl-TDP-TM-TRAIN RCIC PUMP TRAIN IS UNAVAILABLE BECAUSE OF 1.10E-2 MAINTENANCE RCl-XHE-XL-RSTRT OPERATOR FAILS TO RECOVER RCIC FAILURE TO 2.50E-1 RESTART RCl-XHE-XL-XFER OPERATOR FAILS TO RECOVER RCIC FAILURE TO 2.50E-1 TRANSFER RCl-XHE-XO-ERROR OPERATOR FAILS TO START/CONTROL RCIC 1.00E-3 INJECTION RHR-FAN-FS-BC RHR MOP 2B/2C ROOM COOLER FAN FAILS TO START 8.42E-4 RHR-FAN-TM-BC RHR MOP 28/2C ROOM COOLER FAN UNAVAILABLE 2.00E-3 DUE TOT&M RHR-HTX-TM-HTXB RHR HTX-8 IN MAINTENANCE (PSA) 2.36E-3 RHR-MDP-FS-2A RHR TRAIN 2A FAILS TO START 9.47E-4 RHR-MDP-FS-2B RESIDUAL HEAT REMOVAL MOP 2B FAILS TO START 9.47E-4 RHR-MDP-TM-2A RHR MOP 2A IS UNAVAILABLE BECAUSE OF 5.66E-3 MAINTENANCE (PSA)

RHR-MDP-TM-2B RHR MOP 2B IS UNAVAILABLE BECAUSE OF 5.66E-3 MAINTENANCE (PSA)

RHR-MOV-CC-F003A RHR HTX A DISCHARGE MOV 3A FAILS TO OPEN 9.63E-4 RHR-MOV-CC-F003B RHR HTX B DISCHARGE MOV 38 FAILS TO OPEN 9.63E-4 RHR-MOV-CC-MINFA RHR TRAIN A MINFLOW MOV FAILS TO OPEN 9.63E-4 RHR-MOV-CC-MINFB RHR TRAIN B MINFLOW LINE MOV FAILS TO OPEN 9.63E-4 RHR-MOV-00-BYPSA RHR LOOP A HTX BYPASS MOV 48A FAILS TO CLOSE 9.63E-4 RHR-MOV-00-BYPSB RHR LOOP B HTX BYPASS MOV 488 FAILS TO CLOSE 9.63E-4 RHR-XHE-XM-ERROR OPERATOR FAILS TO START/CONTROL RHR 5.00E-4 RRS-MDP-LK-SEALS RECIRCULATION PUMP SEALS FAIL 1.00E-1 SCW-MDP-FS-DG2A STANDBY COOLING WATER MOP TO DG2A FAILS TO 9.47E-4 START SCW-MDP-TM-DGO sew PUMP TO DGO IS UNAVAILABLE BECAUSE OF 1.32E-2 MAINTENANCE SCW-MDP-TM-DG2A sew PUMP TO DG2A IS UNAVAILABLE BECAUSE OF 1.32E-2 MAINTENANCE SCW-MDP-TM-DG2B sew PUMP TO DG2B IS UNAVAILABLE BECAUSE OF 1.32E-2 MAINTENANCE SeW-MOV-CC-68A RHR HTX A DISCHARGE ISOLATION VALVE 68A FAILS 9.63E-4 TO OPEN SCW-MOV-CC-68B RHR HTX B DISCHARGE ISOLATION VALVE 688 FAILS 9.63E-4 TO OPEN SCW-MOV-TM-F068B sew MOV F068B IN MAINTENANCE (PSA) 1.30E-3 SCW-XHE-TM-RHRB OPERATOR FAILS TO ALIGN THE TRAIN B AFTER TM 1.00E-3 (PRA) 30

_..,,., Analysis Unit 1 and Unit 2 Attachment C LER 373/13-002 Swing Diesel Generator (DGO) Fault Tree Modification The LaSalle swing Diesel Generator (DGO) fault tree was modified to account for design anomaly that appeared during this event. The swing diesel generator (one of five at the site}

was not designed to supply both units simultaneously. The simultaneous starting logic from this LOOP event resulted in the DGO loading onto both Units as explained in section 2.3 of this report. The Licensee's load analysis and the Site Inspection Team report, identified the diesel can supply both units, except in the event of a LOCA. The most limiting LOCA was determined to be one or more stuck open SRVs. The basic event EPS-DGN-DGO-LOCA was added to the DGO Fault Tree and set to "ignore" as indicated in the chart below and invoked with a flag set and rule described in section 4.4 of this report to be set to "true" and fail the swing EOG when a failed SRV appears in a cutset.

.**..**** OlE~GEN?AAT~OGOoc: .* f'AIL(Jfte5 *or'b1e5tt<<~R.A:rol\. o *

. . ; $~P,l)P.T$ l"'.4U!-ts' >'.. ; , ,, . ;; f.,( ,, *'~'*'.;~: ~i~~~j ~:':'!,_' J>,,? _,,,

GENERATOR CUl\AVAIL.OBLE FOUR DIESEL GENERATOR~

TO -Es- AND MAimEIJAN::E TO RUN E!>S*t>G\1-TM-D:;o l. 43:-02 6.30E-C6 CICXL GCNCRATOR 0 fAILS T::> ccr ::>r ;.,LL rouR DIC~CL P.JN '.;;El\EP.ATO~.S -o START 4.75E-05

.. SEL GENERATOR 0 FAILS D DJESEL GENE=l.ATOR3 0 4ND ST.\RT lA T:::. RJN

CCF OF DESE_ GENERATORS 0 A

. 1.0 TO START 1.00E-03 31

ASP Analysis Unit 1 and Unit 2 Attachment C LER 373/13-002 RHR Pump 2C Fault Tree Modification For Unit 2 only, the RHR Pump 2C fault tree was modified to account for the failure of the Unit 2 C RHR pump to start in response to a LOOP followed by an ESF Actuation as explained in detail in Section 2.2 of this report. The failure of the pump breaker to close was due to inadequate time for the breaker charging springs to recharge and not associated with any internal component of the pump. Thus, the pump was not failed in the model since this would result in additional common cause failure probability adjustments for similar pumps. Other RHR pumps were not affected thus the new basic event (RHR-MDP-SEQUENCER) was added to the fault tree to fail RHR Pump 2C and avoid common cause failure adjustments.

, PlltiPTRAINS A,B,C COMMON

CAUSE FAlL TO START 9.ISE-06 iPCIPUMP TRAINS A,B,C COMMON CAUSE FAIL TO Rl.f.l LCJ-mP-0'-RUN 2.88E-06

<'.~MOP 2C DISCH CHECK VAL VE

>} ', 31C FAILS TO OPEN Rtit.O::V<C-03tC t.07E-05

' RHR flCP 2C 15 LNAVAILABLE eECAUSE OF MAINTENANCE

-tASAlt£ST#L)8YCOOl.JNG\l!AlER> !J~.QOtiitCOOUNG NOT REQUIRED

,,A:,(OC<;~),fAll.:S'~:', ,,. "PER TH ANALYSIS RtR*MDP-TM*2C 5.66E-03

/~HEAT REMOl/AL MOP 2C False

'"' FAILS TO START 2.00E*03

~-KlP-FS-2C 9.47E-04

~1$5Jb1JAL HEAT REMOVAL MOP 2C FAilSTORL.t.J 32

ASP Analysis Unit 1 and Unit 2 Attachment D LER 373/13-002 HRA Worksheets - SPAR-H Human Error Worksheet - Diagnosis Plant: LaSalle Unit 2 Initiating Event: LOOP Basic Event: OEP-XHE-XL-NR04HSC Basic Event Context: Evaluation of diagnosis/actions to recover with a postulated SBO Basic Event

Description:

Operator Fails to Recover Offsite Power in 4 Hours Does this task contain a significant amount of diagnosis activity? YES 181 (start with Part I-Diagnosis) NO D (skip Part I - Diagnosis; start with Part II -Action) Why? Complexity of the task considering conditions Part I. Evaluate Each PSF for Diagnosis A. Evaluate PSFs for the Diagnosis Portion of the Task, If Any.

Multiplier for Note specific reasons for PSF level PSFs PSF Levels Diagnosis selection in this column.

Inadequate time The operator would need less than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months

$~i~ly~~~q~~j~jii!l~ <~?!~ ~ ciC>t!iici~i) to diagnose this condition based upon Nominal time indicators. This basic event allows for 4 Available hours and is thus greater than twice Time Extr:a***1im*e***(beiween***1****anCi*2*xn.ominaiand

0 nominal and assigned "Expansive".

> thC111}Qri:ii11L *1 Expansive time (> 2 x nominal and > 30 0.01 ri:ii11L ....

Insufficient information Extreme ************mm******~************************************************i*

Stress/ High Due to a postulated Station Black Out Stressors Nominal 1 CI (SBO) stress is assigned "High".

1 D ljighlYC::C>f!JPIE!>C .... 5 Moderately complex Due to multiple equipment unavailabilities Complexity Nominal requiring concurrent actions from multiple procedures during a SBO, assigned "Moderately Complex".

~w 10 I&)

Nominal ********* 1 ..... [l .. Due to several operator knowledge Experience/ 1*

H* * * *i*'*******h*****************************************************************************************************************************************************************************1 . (( weaknesses related to: RHR pump failure, 0 05 Training LPCS failure, SRV operation and Swing Insufficient Information D EDG loading, identified in the SIT report

<Reference 5.4), assianed value of "Low".

Not available 111C::C>f!1PIE!tE! Operating Abnormal Procedure LOA-AP-Ay(lil(l~I~. ~l,ltPC>C>t 201 for the AC Power System permits Procedures assignment of "Nominal.

Nominal i::li~96()~ji~/~yt!IJ?fot!i ~d~cif~~

Insufficient Information fy'li~~i11gfty1i~IE!l:lclil1g .

Poor No event information is available to warrant Ergonomics Nominal a change from Nominal for this I HMI Performance Shaping Factor (PSF).

Good Insufficient Information Unfit P(failure) = 1.0 Fitness for PE!9rCi<:lE!<:l fi~11E!~~. . ********** 5******. .. . . . . .

D

((

No event information is available to warrant a change from Nominal for this Duty Nominal . .... .1... ..... CL . Performance Shaping Factor (PSF).

Insufficient Information 1 I&)

'-'-W.:....:o;..;..;rk~_ ____. . . .:P. . . o.~. oc,. r,..........................................................................................................................................................................: 2 ......... ......... D..

33

ASP Analysis Unit 1 and Unit 2 Attachment D LER 373/13-002 Processes 1

- - - - 0.8

t:r*******

D No event information is available to warrant a change from Nominal for this Insufficient Information IBf Performance Shaping Factor (PSF).

SPAR-H HUMAN ERROR WORKSHEET - DIAGNOSIS Plant: LaSalle Unit 2 Initiating Event: LOOP Basic Event: OEP-XHE-XL-NR04HSC Basic Event Context: Evaluation of diagnosis/actions to recover with a postulated SBO Basic Event

Description:

Operator Fails to Recover Offsite Power in 4 Hours

8. Calculate the Diagnosis Failure Probability.

(1) If all PSF ratings are nominal, then the Diagnosis Failure Probability= 1.0E-2 (2) Otherwise, the Diagnosis Failure Probability is the product of all the PSFs:

Complexit ExpfTrn Procedur Ergonomi Process Diag Diagnosti Nominal Time Stress Fitness c

v Q e c es HEP 1E-2 1E-2 2 2 1E1 1 1 1 1 4E-3 Diaonostic PSF Composite= 4E-1 3 or more negative PSF present? D No, (gJ Yes, Calculate Adjustment Factor C. Calculate the Adjustment Factor IF Negative Multiple (0?3) PSFs are Present.

When 3 or more negative PSF influences are present, in lieu of the equation above, you must compute a composite PSF score used in conjunction with the adjustment factor. Negative PSFs are present anytime a multiplier greater than 1 is selected. The Nominal HEP (NHEP) is 1.0E-2 for Diagnosis. The composite PSF score is computed by multiplying all the assigned PSF values. Then the adjustment factor below is applied to compute the HEP:

HEP= NHEP. PSFcompos1te =

( 1E-2 x 4E-1) I { [ 1E-2 x (4E-1 -1)) + 1} = 4.02E-3 NHEP*(PSFcomposue -1)+1 4.0E-3 Diagnosis HEP with Adjustment Factor=

D. Record Final Diagnosis HEP.

If no adjustment factor was applied, record the value from Part Bas your final diagnosis HEP. If an adjustment factor was applied, record the value from Part C.

4.0E-3 Final Diagnosis HEP =

34

'"'SP Analysis Unit 1 and Unit 2 Attachment D LER 373/13-002 SPAR-H HUMAN ERROR WORKSHEET - ACTION Plant: LaSalle Unit 2 Initiating Event: LOOP Basic Event: OEP-XHE-XL-NR04HSC Basic Event Context: Evaluation of diagnosis/actions to recover with a postulated SBO Basic Event

Description:

Operator Fails to Recover Offsite Power in 4 Hours Part II. EVALUATE EACH PSF FOR ACTION A. Evaluate PSFs for the Action Portion of the Task, If Anv.

Multiplier for Note specific reasons for PSF level PSFs PSF Levels Action selection in this column .

. . 1.ri.c:t.c:l£?9.l!c:l~.t:l. .!.ir.:r.i£?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "" .................. P(fc:i!!l!EE::i)==.:J,Q[:J Tir.:r.it:l c:i11~i1c:i~1'? i~ : thE::i tir.:r.i~ r.'?9l!ir.'?c:l . 1o D Sufficient time was available for the 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months 1

iTu.~i~.~ i~i~L~* ~§~ h~jir.Jl~i~9~*i ~ *.* *** * * * * * * * * * * * * ~ ~

1 Available action component of the recovery but not 5 Time times for the higher PSF and assigned

.***f . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.*.*.*.*.*.: "nominal" .

. . Ti.ri:i.~. . c:i11i:i .1c:it?l.£?..i.~.~.?.Q.~. t.h.E::l . .t!.ri:i.E::i. . r.~.9l!i.r£?.c:l . . . . . .

8.tm.*.*.*

Insufficient Information 0 Extreme Stress/ "Hi 9h. . . . . . The PSF was not determined to be a Stressors Nominal performance driver and assigned Insufficient Information "nominal".

fjigblyc;9111.plf::l~ .... s D Complexity fy'l()c:JE::lrc;ttf?ly c;gri:ipl~".' . 2.................... C:L The PSF was not determined to be a Nominal Insufficient Information ........................................................................... *

1 * * * * * * * . . . . . . . . . . . . . . . . Cf181 performance driver and assigned "nominal".

Low 3 181

~~~inal 6.*~ * * * * * * * * * * * * * *D* *

B*

Due to several operator knowledge gaps Experience/ related to: RHR pump failure, LPCS failure, Training .............. SRV operation and Swing EOG loading, Insufficient Information identified in the SIT report, assigned value of "Low".

Not available 50 CL The PSF was not determined to be a Procedures . . A11c;iilc;it:JI£?,

1ric::e>ri:iP1t:ltt:lpl)tp29r . ;o************************************************....*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*.*oo ....*.*.*.*.*.*.*.*.*.*.*.*.*.*.* performance driver and assigned Nominal

TnsuffiCient informaiion * *

1 1 ************* ***** ******* **** * * "" **** o181 "nominal".

Ergonomics

*Nominal

~ ;s;.rigtfyli ;l.t:l.?. c:li.rig. . . . . . . ~~ *********************** * * * * ******B*****

181 The PSF was not determined to be a performance driver and assigned I HMI "nominal".

Good ....................................................................... "Q,? CJ 1risuffident1rii0rmatian* 1 o Unfit ...................................................................................................... p(f;:iil\Jr.E::i) ==.: 1,QJJ 1

~~~r~: c:1Jilf1£?l3l3 ................................................................................ * * *~* * * * * * * * * * * * * **********************************~******

Fitness for The PSF was not determined to be a Duty performance driver and assigned Insufficient Information 1 (:'.f "nominal".

~~inal ~ * * * * * * * * * * * * * * * * * * * * * * * * * * * ~* * *

The PSF was not determined to be a Work Processes

~iE~aenilniOrmaiion**** ~*.? * * * * * * * * * * * * * * *

B performance driver and assigned "nominal".

35

ASP Analysis Unit 1 and Unit 2 Attachment D LER 373/13-002 SPAR-H HUMAN ERROR WORKSHEET - ACTION Plant: LaSalle Unit 2 Initiating Event: LOOP Basic Event: OEP-XHE-XL-NR04HSC Basic Event Context: Evaluation of diagnosis/actions to recover with a postulated SBO Basic Event

Description:

Operator Fails to Recover Offsite Power in 4 Hours

8. Calculate the Action Failure Probability.

(1) If all PSF ratings are nominal, then the Action Failure Probability = 1.0E-3 (2) Otherwise, the Action Failure Probability is:

St res Complexit Procedur Processe Nominal Time Exp!Trng Ergonomic Fitness Action HEP Action s y e s 1E-3 1 1 1 3 1 1 1 1 3E-3 Action PSF Composite= 3 3 or more negative PSF present? Im No, D Yes, Calculate Adjustment Factor C. Calculate the Adjustment Factor IF Negative Multiple (~3) PSFs are Present.

When 3 or more negative PSF influences are present, in lieu of the equation above, you must compute a composite PSF score used in conjunction with the adjustment factor. Negative PSFs are present anytime a multiplier greater than 1 is selected. The Nominal HEP (NHEP) is 1.0E-3 for Action. The composite PSF score is computed by multiplying all the assigned PSF values. Then the adjustment factor below is applied to compute the HEP:

HEP= NHEP. PSFcompos1/e NHEP. (PSFcomposite -1)+1 N/A Action HEP with Adjustment Factor=

D. Record Final Action HEP.

If no adjustment factor was applied, record the value from Part Bas your final action HEP. If an adjustment factor was applied, record the value from Part C.

3.0E-3 Final Action HEP =

36

...1t' Analysis Unit 1 and Unit 2 Attachment 0 LER 373/13-002 SPAR-H HUMAN ERROR WORKSHEET Plant: LaSalle Unit 2 Initiating Event: LOOP Basic Event: OEP-XHE-XL-NR04HSC Basic Event Context: Evaluation of diagnosis/actions to recover with a postulated SBO Basic Event

Description:

Operator Fails to Recover Offsite Power in 4 Hours PART 111. CALCULATE TASK FAILURE PROBABILITY WITHOUT FORMAL DEPENDENCE (Pw1oo)

Calculate the Task Failure Probability Without Formal Dependence (Pwtod) by adding the Diagnosis Failure Probability from Part I and the Action Failure Probability from Part II. In instances where an action is required without a diagnosis and there is no dependency, then this step is omitted.

Pwtod =Diagnosis HEP 4.0E-3 + Action HEP 3.0E-3 = I 7

.0E-3 Part IV. DEPENDENCY For all tasks, except the first task in the sequence, use the table and formulae below to calculate the Task Failure Probability With Formal Dependence (Pw1d). If there is a reason why failure on previous tasks should not be considered, such as it is impossible to take the current action unless the previous action has been properly performed, explain here: Dependency is not considered for this single basic event Final Basic Event HEP for OEP-XHE-XL-NR04HSC, Pwiod = Pw1d= 7.0E-3 37

ASP Analysis Unit 1 and Unit 2 Attachment D LER 373/13-002 HRA Worksheets SPAR-H HUMAN ERROR WORKSHEET Plant: LaSalle Unit 2 Initiating Event: LOOP Basic Event: OEP-XHE-XL-NR07HSC Basic Event Context: Evaluation of diagnosis/actions to recover with a postulated SBO Basic Event

Description:

Operator Fails to Recover Offsite Power in 7 Hours This HRA analysis for an operator recover in 7 hours8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months from a postulated SBO is identical to the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months recovery basic event OEP-XHE-XL-NR04HSC, since the additional time will not affect any performance shaping factors.

Final Basic Event HEP for OEP-XHE-XL-NR07HSC, Pwiod =Pwid =7.0E-3 SPAR-H HUMAN ERROR WORKSHEET Plant: LaSalle Unit 2 Initiating Event: LOOP Basic Event: OEP-XHE-XL-NR012HSC Basic Event Context: Evaluation of diagnosis/actions to recover with a postulated SBO Basic Event

Description:

Operator Fails to Recover Offsite Power in 12 Hours This HRA analysis for an operator recover in 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months from a postulated SBO is identical to the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months recovery basic event OEP-XHE-XL-NR04HSC, since the additional time will not affect any performance shaping factors.

Final Basic Event HEP for OEP-XHE-XL-NR012HSC, Pwiod =Pwid =7.0E-3 38

ASP Analysis Unit 1 Attachment E LER 373/13-002 LaSalle Unit 1 SAPHIRE Analysis Report Initiating Event IE-LOOPSC CCDP 1.25E-5 Summary of Conditional Event Changes Event Description Cond Nominal Value Value IE-LOOP SC LOSS OF OFFSITE POWER INITIATOR 1.00E+O 1.04E-2 (SWITCHYARD- CENTERED)

OEP-VCF-LP-SITESC SITE LOOP (SWITCHYARD-RELATED) True 2.11E-1 OEP-VCF-LP-SNGLSC SINGLE UNIT LOOP (SWITCHYARD- False 8.06E-1 RELATED)

OEP-XHE-XL-NR01 HSC OPERATOR FAILS TO RECOVER OFFSITE True 4.01 E-1 POWER IN 1 HOUR (SWITCHYARD)

OEP-XH E-XL-N R04HSC OPERATOR FAILS TO RECOVER OFFSITE 7.00E-3 1.02E-1 POWER IN 4 HOURS (SWITCHYARD)

OEP-XHE-XL-NR07HSC OPERATOR FAILS TO RECOVER OFFSITE 7.00E-3 4.65E-2 POWER IN 7 HOURS (SWITCHYARD)

OEP-XHE-XL-NR 12HSC OPERATOR FAILS TO RECOVER OFFSITE 7.00E-3 1.90E-2 POWER IN 12 HOURS (SWITCHYARD)

OEP-XHE-XL-NR30MSC OPERATOR FAILS TO RECOVER OFFSITE True 6.02E-1 POWER IN 30 MINUTES (SWITCHYARD)

PPR-SRV-00-1VLV ONE SRV FAILS TO CLOSE 2.20E-2 8.56E-4 ZT-BWR-SRV-OO-P1 BWR ADS/SRV Fails To Reclose 2.20E-2 8.56E-4 ZT-DGN-FR-L Diesel Generator Fails To Run 1.09E-3 2.47E-2 ZT-TDP-FR-L Turbine Driven Pump Fails To Run 1.56E-3 3.52E-2 PPR-SRV-00-2VLVS TWO OR MORE SRVS FAIL TO CLOSE 3.50E-3 1.36E-4 PPR-SRV-00-3VLVS THREE OR MORE SRVS FAIL TO CLOSE 1.54E-3 5.50E-5 EPS-DGN-FR-DGO DIESEL GENERATOR 0 FAILS TO RUN 6.61E-3 3.01 E-2 EPS-DGN-FR-DG2A DIESEL GENERATOR 2A FAILS TO RUN 6.61E-3 3.01 E-2 EPS-DGN-FR-DG2B DIESEL GENERATOR 28 FAILS TO RUN 6.61E-3 3.01 E-2 EPS-DGN-FR-DG1A DIESEL GENERATOR 1A FAILS TO RUN 6.61 E-3 3.01 E-2 EPS-DGN-FR-DG1 B DIESEL GENERATOR 18 FAILS TO RUN 6.61E-3 3.01 E-2 ZT-BWR-SRV-OO-P2 BWR TWO ADS/SRVS FAIL TO RECLOSE 3.50E-3 1.36E-4 ZT-BWR-SRV-OO-P3 BWR THREE OR MORE ADS/SRVS FAIL TO 1.54E-3 5.50E-5 REC LOSE RCl-TDP-FR-TRAIN RCIC PUMP FAILS TO RUN GIVEN THAT IT 5.97E-3 3.95E-2 STARTED Dominant Sequence Results Only items contributing at least 1.0% to the total CCDP are displayed.

Sequence % Description 43-34-09 29.1% /RPS, EPS, P2, HCS-SBO, /RCl-SBO, OPR-01H, DGR-01H 43-31 19.7% /RPS, EPS, /SRV, /RPSL, HCS-SBO, RCl-SBO, OPR-30M, DGR-30M 07 12.2% /RPS, /EPS, /SRV, /HCS, SPC, /DEP, SOC, CSS, CVS, LI-VENT-FAILURE 39

ASP Analysis Unit 1 Attachment E LER 373/13-002 Sequence % Description 42-13 9.9% /RPS, /EPS, P2, HCS, LPI 43-33-15 7.1% /RPS, EPS, P1, HCS-SBO, RCl-SBO 40 6.8% /RPS, /EPS, /SRV, HCS, RCI, DEP 42-12 4.4% /RPS, /EPS, P2, HCS, /LPI, SPC, CSS, CVS, LI-VENT-FAILURE 43-32-15 2.1% /RPS, EPS, /SRV, RPSL, HCS-SBO, RCl-SBO 43-34-10 1.6% /RPS, EPS, P2, HCS-SBO, RCl-SBO 31 1.1% /RPS, /EPS, /SRV, HCS, RCI, /DEP, /LPI, SPC, SOC, CSS, CVS, LI-VENT-FAILURE 100.0%

Referenced Fault Trees Fault Tree Description css CONTAINMENT SPRAY CVS CONTAINMENT VENTING DEP MANUAL REACTOR DEPRESS DGR-01H DIESEL GENERATOR RECOVERY (1 HOUR)

DGR-30M DIESEL GENERATOR RECOVERY (30 MINUTES)

EPS EMERGENCY POWER HCS HPCS HCS-SBO HPCS LI-VENT-FAILURE LATE INJECTION FOLLOWING VENTILATION FAILURE LPI LOW PRESSURE INJECTION OPR-01H OFFSITE POWER RECOVERY (1 HOUR)

OPR-30M OFFSITE POWER RECOVERY (30 MINUTES)

P1 ONE SORV P2 TWO OR MORE SORVs RCI RCIC RCl-SBO RCIC FAILS DURING STATION BLACKOUT RPSL RECIRC PUMP SEAL INTEGRITY soc SHUTDOWN COOLING SPC SUPPRESSION POOL COOLING Cut Set Report - LOOPSC 43-34-09 Only items contributing at least 1% to the total are displayed.

CCDP Total% CutSet 3.64E-6 100 Displaying 2104 Cut Sets. (2104 Original) 6.28E-7 17.26 IE-LOOPSC,EPS-DGN-TM-DG1 B,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 2 2.89E-7 7.95 IE-LOOPSC,EPS-DGN-FR-DG2A,EPS-DGN-TM-DG1 B,EPS-XHE-XL-NR01 H,PPR-SRV-00-2VLVS 3 2.89E-7 7.95 IE-LOOPSC,EPS-DGN-FR-DG1 B,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01 H,PPR-SRV-00-2VLVS 4 2.76E-7 7.57 IE-LOOPSC,EPS-DGN-TM-DG1 B,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 40

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set 5 2.67E-7 7.33 IE-LOOPSC,EPS-DGN-FR-DG1 B,EPS-XHE-XL-NR01 H,PPR-SRV 2VLVS,SCW-MDP-TM-DG2A 6 1.33E-7 3.66 IE-LOOPSC, EPS-DGN-FR-DG1 B, EPS-DGN-FR-DG2A,EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 7 1.27E-7 3.49 I E-LOOPSC, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG1 B, EPS-XHE-XL-NR01 H,PPR-SRV-00-3VLVS 8 1.27E-7 3.49 IE-LOOPSC, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 9 1.27E-7 3.48 IE-LOOP SC, EPS-DGN-FS-DG2A, EPS-DGN-TM-DG 1B, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 10 1.27E-7 3.48 IE-LOOPSC,EPS-DGN-FS-DG1 B, EPS-DGN-TM-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 11 1.17E-7 3.22 IE-LOOPSC, EPS-DGN-FR-DG1 B, EPS-XHE-XL-NR01 H,PPR-SRV 3VLVS,SCW-MDP-TM-DG2A 12 1.17E-7 3.21 IE-LOOPSC, EPS-DGN-FS-DG1 B, EPS-XHE-XL-NR01 H, PPR-SRV 2VL VS, SCW-MDP-TM-DG2A 13 5.85E-8 1.61 I E-LOOPSC, EPS-DGN-FR-DG 1B, EPS-DGN-FR-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 14 5.83E-8 1.60 IE-LOOPSC, EPS-DGN-FR-DG2A, EPS-DGN-FS-DG 1B, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 15 5.83E-8 1.60 IE-LOOP SC, EPS-DGN-FR-DG 1B, EPS-DGN-FS-DG2A, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS 16 5.55E-8 1.53 IE-LOOPSC, EPS-DGN-FS-DG2A,EPS-DGN-TM-DG1 B, EPS-XHE-XL-NR01 H, PPR-SRV-00-3VLVS 17 5.55E-8 1.53 I E-LOOPSC EPS-DGN-FS-DG 1B, EPS-DGN-TM-DG2A, EPS-XHE-XL-I NR01 H, PPR-SRV-00-3VLVS 18 5.12E-8 1.41 IE-LOOPSC,EPS-DGN-FS-DG1 B, EPS-XHE-XL-NR01 H,PPR-SRV 3VLVS,SCW-MDP-TM-DG2A 19 4.38E-8 1.20 IE-LOOPSC,EPS-DGN-TM-DG2A,EPS-XHE-XL-NR01H,EPS-XHE-XR-DG 1B, PPR-SRV-00-2VLVS 20 4.15E-8 1.14 IE-LOOPSC, EPS-DGN-TM-DG1 B,EPS-XHE-XL-NR01 H, PPR-SRV 2VL VS, SCW-MDP-FS-DG2A 21 4.04E-8 1.11 IE-LOOPSC,EPS-XHE-XL-NR01 H,EPS-XHE-XR-DG1 B,PPR-SRV 2VL VS, SCW-MDP-TM-DG2A 22 3.96E-8 1.09 IE-LOOP SC, EPS-DGN-CF-R4, EPS-XHE-XL-NR01 H, PPR-SRV-00-2VLVS Cut Set Report - LOOPSC 43-31 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 2.46E-6 100 Displaying 30480 Cut Sets. (30480 Original) 1 2.38E-7 9.68 I E-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-CF-R4, EPS-XHE-XL-NR30M 2 1.30E-7 5.30 IE-LOOPSC,EPS-DGN-CF-R4,EPS-XHE-XL-NR30M,RCl-TDP-TM-TRAIN 3 8.72E-8 3.54 IE-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-CF-S4, EPS-XHE-XL-NR30M 4 7.74E-8 3.14 IE-LOOPSC,EPS-DGN-CF-R4,EPS-XHE-XL-NR30M,RCl-TDP-FS-TRAIN 5 7.11E-8 2.89 I E-LOOPSC, EPS-DGN-CF-R4, EPS-XH E-XL-NR30M RCl-TDP-FR-TRAIN I

41

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set 6 4.77E-8 1.94 IE-LOOPSC,EPS-DGN-CF-S4,EPS-XHE-XL-NR30M,RCl-TDP-TM-TRAIN 7 4.25E-8 1.73 IE-LOOPSC, DCP-BAT-CF-ALL, EPS-XH E-XL-NR30M 8 3.57E-8 1.45 IE-LOOPSC, EPS-DGN-CF-R4, EPS-XH E-XL-NR30M, RC I-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 9 2.83E-8 1.15 IE-LOOPSC,EPS-DGN-CF-S4,EPS-XHE-XL-NR30M,RCl-TDP-FS-TRAIN 10 2.60E-8 1.06 IE-LOOPSC,EPS-DGN-CF-S4,EPS-XHE-XL-NR30M,RCl-TDP-FR-TRAIN 11 2.50E-8 1.02 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DGO, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, EPS-XH E-XL-N R30M 12 2.50E-8 1.02 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG1 A, EPS-DGN-TM-DG 1B,EPS-DGN-TM-DG2A, EPS-XHE-XL-NR30M 13 2.50E-8 1.02 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG 1B, EPS-DGN-TM-DGO, EPS-DGN-TM-DG2A, EPS-XH E-XL-NR30M 14 2.50E-8 1.02 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DG 1B, EPS-DGN-TM-DG 1A, EPS-DGN-TM-DG2A, EPS-XH E-XL-N R30M Cut Set Report - LOOPSC 07 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 1.52E-6 100 Displaying 30157 Cut Sets. (30157 Original) 6.45E-8 4.23 IE-LOOPSC,CRD-XHE-XM-PUMP,CTM-DW-BODY-FAILURE,CVS-MOV-TM-PURGE,RHR-XHE-XM-ERROR 2 4.89E-8 3.21 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DGO,OEP-XHE-XL-NR12HSC,RHR-MDP-TM-2B 3 2.24E-8 1.47 IE-LOOPSC,ACP-BAC-TM-241 Y, CTM-DW-BODY-FAI LU RE, SCW-MOV-TM-F068B 4 2.15E-8 1.41 IE-LOOPSC,CRD-XHE-XM-PUMP,CTM-DW-BODY-FAILURE,CVS-XHE-XM-VENT,RHR-XHE-XM-ERROR 5 2.03E-8 1.33 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DGO,OEP-XHE-XL-NR12HSC,RHR-HTX-TM-HTXB 6 1.88E-8 1.23 IE-LOOPSC,CTM-DW-BODY-FAILURE,OEP-XHE-XL-NR12HSC,RHR-HTX-TM-HTXB, SCW-MDP-TM-DGO 7 1.73E-8 1.13 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DGO,OEP-XHE-XL-NR12HSC,RHR-FAN-TM-BC 8 1.72E-8 1.13 IE-LOOPSC,ACP-BAC-TM-241Y,CTM-DW-BODY-FAILURE,SCW-XHE-TM-RH RB 9 1.70E-8 1.12 IE-LOOPSC,ACP-XH E-XM-DGO, CTM-DW-BODY-FAI LURE, FLAG-DGO-ALIGNED-AWAY,OEP-XHE-XL-NR12HSC,RHR-MDP-TM-2B 10 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-241Y,CTM-DW-BODY-FAILURE,RHR-MOV-CC-MINFB 11 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-241 Y, CTM-DW-BODY-FAI LURE, SCW-MOV-CC-688 12 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-241Y,CTM-DW-BODY-FAILURE,RHR-MOV-CC-F003B 13 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-241Y,CTM-DW-BODY-FAILURE,RHR-MOV-00-BYPSB 14 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-242Y, CTM-DW-BODY-FAI LU RE, SCW-MOV-CC-68A 42

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set 15 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-242Y,CTM-DW-BODY-FAILURE,RHR-MOV-CC-MINFA 16 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-242Y,CTM-DW-BODY-FAILURE,RHR-MOV-CC-F003A 17 1.66E-8 1.09 IE-LOOPSC,ACP-BAC-TM-242Y, CTM-DW-BODY-FAI LURE, RHR-MOV-00-BYPSA 18 1.63E-8 1.07 IE-LOOPSC,ACP-BAC-TM-241Y,CTM-DW-BODY-FAILURE,RHR-MDP-FS-2B 19 1.63E-8 1.07 IE-LOOPSC,ACP-BAC-TM-242Y, CTM-DW-BODY-FAI LURE, RHR-MDP-FS-2A 20 1.62E-8 1.06 IE-LOOPSC,ACP-BAC-LP-241 Y, CTM-DW-BODY-FAI LURE, RHR-MDP-TM-28 21 1.62E-8 1.06 IE-LOOPSC,ACP-BAC-LP-242Y, CTM-DW-BODY-FAI LURE, RHR-MDP-TM-2A 22 1.59E-8 1.05 IE-LOOPSC,CTM-DW-BODY-FAILURE,OEP-XHE-XL-NR12HSC,RHR-FAN-TM-BC, SCW-MDP-TM-DGO Cut Set Report - LOOPSC 42-13 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 1.24E-6 100 Displaying 3409 Cut Sets. (3409 Original)

1. OOE-7 8. 08 IE-LOOPSC, EPS-DGN-TM-DG 1B, PPR-SRV-00-2VL VS, RHR-FAN-TM-BC 2 9.27E-8 7.45 IE-LOOPSC,PPR-SRV-00-2VLVS,RHR-FAN-TM-BC,SCW-MDP-TM-DG2B 3 5.02E-8 4.04 IE-LOOPSC, EPS-DGN-TM-DG1 B, PPR-SRV-00-2VLVS,SCW-XHE-TM-RHRB 4 4.77E-8 3.84 IE-LOOP SC, HCS-MDP-TM-HPCS, PPR-SRV-00-2VL VS, RHR-FAN-TM-BC 5 4.63E-8 3.73 IE-LOOPSC, PPR-SRV-00-2VL VS, SCW-MDP-TM-DG2B, SCW-XHE-TM-RHRB 6 4.41 E-8 3.55 IE-LOOPSC, EPS-DGN-TM-DG 1B, PPR-SRV-00-3VL VS, RHR-FAN-TM-BC 7 4.23E-8 3.40 IE-LOOPSC, EPS-DGN-TM-DG 1B, PPR-SRV-00-2VL VS, RHR-FAN-FS-BC 8 4.07E-8 3.27 IE-LOOPSC,PPR-SRV-00-3VLVS,RHR-FAN-TM-BC,SCW-MDP-TM-DG2B 9 3.90E-8 3.14 IE-LOOPSC, PPR-SRV-00-2VLVS, RHR-FAN-FS-BC,SCW-MDP-TM-DG2B 10 2.39E-8 1.92 IE-LOOP SC, HCS-MDP-TM-HPCS, PPR-SRV-00-2VL VS, SCW-XHE-TM-RHRB 11 2.21 E-8 1.77 IE-LOOPSC, EPS-DGN-TM-DG 1B, PPR-SRV-00-3VL VS, SCW-XHE-TM-RHRB 12 2.10E-8 1.69 IE-LOOPSC, HCS-MOV-FT-SUCTR, PPR-SRV-00-2VLVS, RHR-FAN-TM-BC 13 2.10E-8 1.68 IE-LOOPSC, HCS-MDP-TM-HPCS, PPR-SRV-00-3VL VS, RHR-F AN-TM-BC 14 2.03E-8 1.64 IE-LOOPSC, PPR-SRV-00-3VL VS, SCW-MDP-TM-DG2B, SCW-XHE-TM-RHRB 15 2.02E-8 1.63 IE-LOOPSC, EPS-DGN-FS-DG1 B, PPR-SRV-00-2VLVS,RHR-FAN-TM-BC 43

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set 16 2.01 E-8 1.62 IE-LOOPSC,HCS-MDP-TM-HPCS,PPR-SRV-00-2VLVS,RHR-FAN-FS-BC 17 1.86E-8 1.49 IE-LOOP SC, EPS-DGN-TM-DG1 B, PPR-SRV-00-3VLVS, RHR-FAN-FS-BC 18 1.71E-8 1.38 IE-LOOPSC, PPR-SRV-00-3VLVS, RHR-F AN-FS-BC, SCW-MDP-TM-DG2B 19 1.67E-8 1.35 IE-LOOPSC,HCS-CRB-OO-MDP,PPR-SRV-00-2VLVS,RHR-FAN-TM-BC 20 1.51E-8 1.21 IE-LOOPSC, EPS-DGN-TM-DG1 B, PPR-SRV-00-2VLVS, SCW-STR-TM-TRNB 21 1.40E-8 1.13 IE-LOOPSC,HCS-FAN-TM-ROOM,PPR-SRV-00-2VLVS,RHR-FAN-TM-BC 22 1.39E-8 1.12 IE-LOOPSC, PPR-SRV-00-2VL VS, SCW-M DP-TM-DG2B, SCW-STR-TM-TRNB Cut Set Report - LOOPSC 43-33-15 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 8.89E-7 100 Displaying 6347 Cut Sets. (6347 Original) 1 9.06E-8 10.20 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV-00-1 VL V 2 4.17E-8 4.70 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG1 B,PPR-SRV-00-1VLV 3 4.17E-8 4.70 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG 1B, EPS-DGN-TM-DG2A,PPR-SRV-00-1VLV 4 3.85E-8 4.33 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG 1B, PPR-SRV-00-1VLV,SCW-MDP-TM-DG2A 5 2.94E-8 3.31 IE-LOOPSC, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-FS-TRAIN 6 2.70E-8 3.04 IE-LOOPSC, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-FR-TRAIN 7 2.28E-8 2.57 IE-LOOPSC, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-TM-TRAIN 8 2.11 E-8 2.37 IE-LOOPSC, EPS-DGN-FR-DG1 B, PPR-SRV-00-1VLV,RCl-TDP-TM-TRAIN ,SCW-MDP-TM-DG2A 9 1.92E-8 2.16 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DG 1B, EPS-DGN-FR-DG2A, PPR-SRV-00-1 VLV 10 1.83E-8 2.05 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FS-DG2A, EPS-DGN-TM-DG1 B,PPR-SRV-00-1VLV 11 1.83E-8 2.05 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FS-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-1 VL V 12 1.68E-8 1.90 IE-LOOP SC, DCP-XHE-XM-STRIP30M, EPS-DGN-FS-DG1 B, PPR-SRV-00-1VLV,SCW-MDP-TM-DG2A 13 1.36E-8 1.53 IE-LOOPSC, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV, RC I-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 14 1.35E-8 1.52 IE-LOOPSC,EPS-DGN-FR-DG1B,EPS-DGN-TM-DG2A,PPR-SRV-OO-1VLV,RCl-TDP-FS-TRAIN 15 1.35E-8 1.52 IE-LOOPSC, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG 1B, PPR-SRV 1VLV,RCl-TDP-FS-TRAIN 16 1.25E-8 1.41 IE-LOOPSC,EPS-DGN-FR-DG1B,PPR-SRV-00-1VLV,RCl-TDP-FS-44

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set TRAIN, SCW-MDP-TM-DG2A 17 1.25E-8 1.40 IE-LOOPSC, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-FR-TRAIN 18 1.25E-8 1.40 I E-LOOPSC, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG 1B, PPR-SRV 1VL V, RCl-TDP-FR-TRAIN 19 1.15E-8 1.29 IE-LOOP SC, EPS-DGN-FR-DG 1B, PPR-SRV-00-1 VLV, RCl-TDP-FR-TRAIN, SCW-MDP-TM-DG2A 20 1.05E-8 1.18 I E-LOOPSC, EPS-DGN-FR-DG 1B, EPS-DGN-FR-DG2A, PPR-SRV 1VL V, RCl-TDP-TM-TRAIN 21 9.99E-9 1.12 IE-LOOP SC, EPS-DGN-FS-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV 1VLV,RCl-TDP-TM-TRAIN 22 9.22E-9 1.04 IE-LOOPSC,EPS-DGN-FS-DG1B,PPR-SRV-00-1VLV,RCl-TDP-TM-TRAIN ,SCW-MDP-TM-DG2A 23 9.02E-9 1.02 IE-LOOPSC,EPS-DGN-TM-DG1B,EPS-DGN-TM-DG2A,PPR-SRV 1VLV, RCl-MOV-FC-XFER, RCl-XHE-XL-XFER Cut Set Report - LOOPSC 40 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 8.57E-7 100 Displaying 5616 Cut Sets. (5616 Original) 7.19E-8 8.38 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-XHE-XO-ERROR 1, RCl-XHE-XO-ERROR 2 4.66E-8 5.44 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-TM-DG1 B, RCl-TDP-FS-TRAIN 3 4.30E-8 5.01 IE-LOOPSC,ADS-XHE-XM-MDEPR, RCl-TDP-FS-TRAI N, SCW-MDP-TM-DG2B 4 4.28E-8 5.00 I E-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-TM-DG1 B, RCl-TDP-FR-TRAIN 5 3.95E-8 4.61 I E-LOOPSC ,ADS-XHE-XM-MDEPR, RC I-TOP-FR-TRAIN ,SCW-MDP-TM-DG2B 6 3.62E-8 4.22 I E-LOOPSC,ADS-XH E-XM-MDEPR, EPS-DGN-FR-DG1 B, RCl-TDP-TM-TRAIN 7 2.21 E-8 2.58 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-MDP-TM-HPCS, RCl-TDP-FS-TRAIN 8 2.15E-8 2.51 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-TM-DG 1B, RCI-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 9 2.15E-8 2.50 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FR-DG 1B, RCl-TDP-FS-TRAIN 10 2.04E-8 2.37 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-MDP-TM-HPCS, RCl-TDP-FR-TRAIN 11 1.99E-8 2.32 IE-LOOPSC,ADS-XHE-XM-MDEPR, RCl-RESTART, RCl-TDP-FS-RSTRT,RCl-XHE-XL-RSTRT,SCW-MDP-TM-DG2B 12 1.97E-8 2.30 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FR-DG 1B, RCl-TDP-FR-TRAIN 13 1.64E-8 1.92 IE-LOOPSC,ADS-XHE-XM-MDEPR,HCS-MOV-FT-SUCTR,RCl-TDP-TM-TRAIN 14 1.58E-8 1.85 I E-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FS-DG 1B, RC I-TOP-TM-45

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set TRAIN 15 1.43E-8 1.67 IE-LOOPSC,ADS-XHE-XM-MDEPR,EPS-DGN-TM-DG18,RCl-MOV-FC-XFER,RCl-XHE-XL-XFER 16 1.32E-8 1.54 IE-LOOPSC,ADS-XHE-XM-MDEPR, RCl-MOV-FC-XFER, RCl-XHE-XL-XFER,SCW-MDP-TM-DG2B 17 1.31E-8 1.53 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-CRB-00-MDP, RCl-TDP-TM-TRAIN 18 1.10E-8 1.28 IE-LOOPSC,ADS-XHE-XM-MDEPR, HCS-FAN-TM-ROOM, RCl-TDP-TM-TRAIN 19 1.02E-8 1.19 IE-LOOPSC,ADS-XHE-XM-MDEPR,HCS-MDP-TM-HPCS,RCI-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 20 9.91 E-9 1.16 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FR-DG 1B, RCI-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 21 9.74E-9 1.14 IE-LOOPSC,ADS-XHE-XM-MDEPR,HCS-MOV-FT-SUCTR,RCl-TDP-FS-TRAIN 22 9.39E-9 1.09 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FS-DG 1B, RCl-TDP-FS-TRAIN 23 8.95E-9 1.04 IE-LOOPSC,ADS-XH E-XM-MDEPR, HCS-MOV-FT-SUCTR, RCl-TDP-FR-TRAIN 24 8.63E-9 1.01 IE-LOOPSC,ADS-XHE-XM-MDEPR, EPS-DGN-FS-DG 18, RCl-TDP-FR-TRAIN Cut Set Report - LOOPSC 42-12 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 5.49E-7 100 Displaying 14851 Cut Sets. (14851 Original) 1 2.45E-8 4.46 IE-LOOP SC, CTM-DW-BODY-FAILURE, EPS-DGN-TM-DG18, PPR-SRV-00-2VL VS, RHR-MDP-TM-28 2 2.26E-8 4.11 IE-LOOP SC, CTM-DW-80DY-FAl LURE, PPR-SRV-00-2VLVS, RHR-MDP-TM-28,SCW-MDP-TM-DG28 3 1.16E-8 2.12 IE-LOOPSC, CTM-DW-80DY-FAI LURE, HCS-MDP-TM-HPCS, PPR-SRV-00-2VLVS, RHR-MDP-TM-28 4 1.07E-8 1.96 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DG18,PPR-SRV-00-3VLVS, RHR-MDP-TM-28 5 1.02E-8 1.85 IE-LOOPSC,CTM-DW-BODY-FAILURE,EPS-DGN-TM-DG18,PPR-SRV-00-2VLVS,RHR-HTX-TM-HTX8 6 9.90E-9 1.81 IE-LOOPSC,CTM-DW-80DY-FAILURE,PPR-SRV-00-3VLVS,RHR-MDP-TM-28,SCW-MDP-TM-DG2B 7 9.39E-9 1.71 IE-LOOPSC,CTM-DW-BODY-FAILURE,PPR-SRV-00-2VLVS,RHR-HTX-TM-HTX8,SCW-MDP-TM-DG2B 8 5.62E-9 1.02 IE-LOOPSC, CTM-DW-BODY-FAI LU RE, EPS-DGN-TM-DG 18, PPR-SRV-00-2VL VS, SCW-MOV-TM-F0688 Cut Set Report - LOOPSC 43-32-15 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 2.67E-7 100 Displaying 13464 Cut Sets. (13464 Original) 46

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set 1 2.60E-8 9.72 I E-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-CF-R4, RRS-MDP-LK-SEALS 2 1.42E-8 5.32 IE-LOOPSC,EPS-DGN-CF-R4,RCl-TDP-TM-TRAIN,RRS-MDP-LK-SEALS 3 9.50E-9 3.56 I E-LOOPSC IDCP-XHE-XM-STRI P30M I EPS-DGN-CF-S4, RRS-MDP-LK-SEALS 4 8.43E-9 3.16 I E-LOOPSC, EPS-DGN-CF-R4, RCl-TDP-FS-TRAI N, RRS-MDP-LK-SEALS 5 7.75E-9 2.90 IE-LOOPSC, EPS-DGN-CF-R4, RCl-TDP-FR-TRAI N, RRS-MDP-LK-SEALS 6 5.20E-9 1.95 I E-LOOPSC, EPS-DGN-CF-S4, RCl-TDP-TM-TRAI NI RRS-M DP-LK-SEALS 7 4.63E-9 1.73 IE-LOOPSC, DCP-BAT-CF-ALL, RRS-MDP-LK-SEALS 8 3.89E-9 1.46 IE-LOOP SC, EPS-DGN-CF-R4, RC I-RESTART, RCl-TDP-FS-RSTRT, RCI-XHE-XL-RSTRT,RRS-MDP-LK-SEALS 9 3.08E-9 1.15 I E-LOOPSC, EPS-DGN-CF-S4, RCl-TDP-FS-TRAI NI RRS-MDP-LK-SEALS 10 2.84E-9 1.06 IE-LOOPSC, EPS-DGN-CF-S4, RCl-TDP-FR-TRAI NI RRS-MDP-LK-SEALS 11 2.72E-9 1.02 I E-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG 1A, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, RRS-MDP-LK-SEALS 12 2.72E-9 1.02 I E-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DGO, EPS-DGN-TM-DG1 B, EPS-DGN-TM-DG2A, RRS-MDP-LK-SEALS 13 2.72E-9 1.02 IE-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DGO, EPS-DGN-TM-DG2A, RRS-MDP-LK-S EALS 14 2.72E-9 1.02 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG1 B,EPS-DGN-TM-DG1A,EPS-DGN-TM-DG2A,RRS-MDP-LK-SEALS Cut Set Report - LOOP SC 43-34-10 Only items contributing at least 1% to the total are displayed.

CCDP Total% Cut Set 2.03E-7 100 Displaying 6784 Cut Sets. (6784 Original) 1.44E-8 7.10 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-TM-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-2VL VS 2 6.64E-9 3.27 IE-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-2VLVS 3 6.64E-9 3.27 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG1 B, PPR-SRV-00-2VLVS 4 6.33E-9 3.12 IE-LOOPSC, DCP-XHE-XM-STRIP30M,EPS-DGN-TM-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-3VLVS 5 6.13E-9 3.02 I E-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG 1B, PPR-SRV-00-2VLVS, SCW-MDP-TM-DG2A 6 4.68E-9 2.30 IE-LOOP SC, EPS-DGN-TM-DG1 B,EPS-DGN-TM-DG2A, PPR-SRV 2VLVS, RCl-TDP-FS-TRAIN 7 4.30E-9 2.12 IE-LOOP SC, EPS-DGN-TM-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV 2VL VS, RCl-TDP-FR-TRAI N 8 3.64E-9 1.79 IE-LOOP SC, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV 2VLVS,RCl-TDP-TM-TRAIN 9 3.35E-9 1.65 IE-LOOPSC, EPS-DGN-FR-DG1 B, PPR-SRV-00-2VLVS, RCl-TDP-TM-TRAIN,SCW-MDP-TM-DG2A 10 3.06E-9 1.51 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG1B,EPS-DGN-FR-DG2A, PPR-SRV-00-2VLVS 47

ASP Analysis Unit 1 Attachment E LER 373/13-002

CCDP Total% Cut Set 11 2.91 E-9 1.44 IE-LOOPSC, DCP-XHE-XM-STRI P30M, EPS-DGN-FR-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-3VLVS 12 2.91 E-9 1.44 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FR-DG2A, EPS-DGN-TM-DG 1B,PPR-SRV-00-3VLVS 13 2.90E-9 1.43 IE-LOOPSC, DCP-XHE-XM-STRIP30M, EPS-DGN-FS-DG1 B, EPS-DGN-TM-DG2A, PPR-SRV-00-2VLVS 14 2.90E-9 1.43 IE-LOOPSC, DCP-XH E-XM-STRI P30M, EPS-DGN-FS-DG2A, EPS-DGN-TM-DG 1B, PP R-SRV-00-2VL VS 15 2.69E-9 1.32 IE-LOOPSC,DCP-XHE-XM-STRIP30M,EPS-DGN-FR-DG1 B,PPR-SRV-00-3VLVS,SCW-MDP-TM-DG2A 16 2.68E-9 1.32 IE-LOOPSC,DCP-XHE-XM-STRIP30M, EPS-DGN-FS-DG1 B, PPR-SRV-00-2VLVS, SCW-MDP-TM-DG2A 17 2.16E-9 1.06 IE-LOOPSC, EPS-DGN-TM-DG 1B, EPS-DGN-TM-DG2A, PPR-SRV 2VL VS, RCl-RESTART, RCl-TDP-FS-RSTRT, RCl-XHE-XL-RSTRT 18 2.16E-9 1.06 IE-LOOPSC,EPS-DGN-FR-DG2A,EPS-DGN-TM-DG1 B,PPR-SRV 2VLVS,RCl-TDP-FS-TRAIN 19 2.16E-9 1.06 IE-LOOPSC,EPS-DGN-FR-DG1 B,EPS-DGN-TM-DG2A,PPR-SRV 2VLVS,RCl-TDP-FS-TRAIN 20 2.05E-9 1.01 IE-LOOPSC,EPS-DGN-TM-DG1B,EPS-DGN-TM-DG2A,PPR-SRV 3VLVS,RCl-TDP-FS-TRAIN Referenced Events Event Description Probability ACP-BAC-LP-241 Y 4160 V BUS 241Y HARDWARE FAILURES 3.33E-5 ACP-BAC-LP-242Y 4160 V BUS 242Y HARDWARE FAILURES 3.33E-5 ACP-BAC-TM-241 Y 4160 V BUS 241Y IN MAINTENANCE (PSA) 2.00E-4 ACP-BAC-TM-242Y 4160 V BUS 242Y IN MAINTENANCE (PSA) 2.00E-4 ACP-XHE-XM-DGO OPERATOR FAILS TO ALIGN DGO TO DIV-1 BUS 241Y 1.00E-2 ADS-XHE-XM-MDEPR OPERATOR FAILS TO DEPRESSURIZE THE REACTOR 5.00E-4 CRD-XHE-XM-PUMP OPERATOR FAILS TO START THE STANDBY PUMP 5.00E-1 CTM-DW-BODY- CATASTROPHIC CONTAINMANT OW BODY FAILURE 8.60E-2 FAl LU RE CAUSES LOSS OF INJECTION CVS-MOV-TM-PURGE CONTAINMENT VENT/PURGE SYSTEM IN 3.00E-3 MAINTENANCE (PSA)

CVS-XHE-XM-VENT OPERATOR FAILS TO VENT CONTAINMENT 1.00E-3 DCP-BAT-CF-ALL CCF OF 125VDC BATTERYS (3) 4.63E-8 DCP-XHE-XM- OPERATOR FAILS TO SHED 125 voe NON-ESSENTIAL 2.00E-2 STRIP30M LOADS EPS-DGN-CF-R4 CCF OF FOUR DIESEL GENERATORS TO RUN 1.30E-5 EPS-DGN-CF-S4 CCF OF ALL FOUR DIESEL GENERATORS TO START 4.75E-6 EPS-DGN-FR-DGO DIESEL GENERATOR 0 FAILS TO RUN 6.61 E-3 EPS-DGN-FR-DG1A DIESEL GENERATOR 1A FAILS TO RUN 6.61 E-3 EPS-DGN-FR-DG1 B DIESEL GENERATOR 1B FAILS TO RUN 6.61 E-3 EPS-DGN-FR-DG2A DIESEL GENERATOR 2A FAILS TO RUN 6.61 E-3 EPS-DGN-FS-DG1 B DIESEL GENERATOR 1B FAILS TO START 2.89E-3 48

ASP Analysis Unit 1 Attachment E LER 373/13-002 EPS-DGN-FS-DG2A DIESEL GENERATOR 2A FAILS TO START 2.89E-3 EPS-DGN-TM-DGO DIESEL GENERATOR 0 UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-DGN-TM-DG1A DIESEL GENERATOR 1A UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-DGN-TM-DG1B DIESEL GENERATOR 1B UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-DGN-TM-DG2A DIESEL GENERATOR 2A UNAVAILABLE DUE TO TEST 1.43E-2 AND MAINTENANCE EPS-XHE-XL-NR01 H OPERATOR FAILS TO RECOVER EMERGENCY DIESEL 8.71 E-1 IN 1 HOUR EPS-XHE-XL-NR30M OPERATOR FAILS TO RECOVER EMERGENCY DIESEL 9.18E-1 IN 30 MINUTES EPS-XHE-XR-DG1 B OPERATOR FAILS TO RESTORE DG1B AFTER 1.00E-3 MAINTENANCE FLAG-DGO-ALIGNED- DGO ALIGNED TO U1 INITIALLY 5.00E-1 AWAY HCS-CRB-00-MDP HCS MDP 4.1 kV CBRKR FAILS TO CLOSE (PSA) 2.39E-3 HCS-FAN-TM-ROOM HPCS ROOM COOLER FAN UNAVAILABLE DUE TO T&M 2.00E-3 HCS-MDP-TM-HPCS HPCI TRAIN IS UNAVAILABLE BECAUSE OF 6.82E-3 MAINTENANCE HCS-MOV-FT-SUCTR HPCS SUCTION TRANSFER FAILS 3.00E-3 HCS-XHE-XO-ERROR 1 OPERATOR FAILS TO START/CONTROL HPCS 1.44E-1 INJECTION IE-LOOP SC LOSS OF OFFSITE POWER INITIATOR (SWITCHYARD- 1.00E+O CENTERED)

OEP-XHE-XL-NR12HSC OPERATOR FAILS TO RECOVER OFFSITE POWER IN 7.00E-3 12 HOURS (SWITCHYARD)

PPR-SRV-00-1VLV ONE SRV FAILS TO CLOSE 2.20E-2 PPR-SRV-00-2VLVS TWO OR MORE SRVS FAIL TO CLOSE 3.50E-3 PPR-SRV-00-3VLVS THREE OR MORE SRVS FAIL TO CLOSE 1.54E-3 RCl-MOV-FC-XFER RCIC FAILS TO TRANSFER DURING RECIRCULATION 7.97E-3 RC I-RESTART RESTART OF RCIC IS REQUIRED 1.50E-1 RCl-TDP-FR-TRAI N RCIC PUMP FAILS TO RUN GIVEN THAT IT STARTED 5.97E-3 RCl-TDP-FS-RSTRT RCIC FAILS TO RESTART GIVEN START AND SHORT- 8.00E-2 TERM RUN RCl-TDP-FS-TRAI N RCIC PUMP FAILS TO START 6.49E-3 RCl-TDP-TM-TRAIN RCIC PUMP TRAIN IS UNAVAILABLE BECAUSE OF 1.10E-2 MAINTENANCE RCl-XHE-XL-RSTRT OPERATOR FAILS TO RECOVER RCIC FAILURE TO 2.50E-1 RESTART RCl-XHE-XL-XFER OPERATOR FAILS TO RECOVER RCIC FAILURE TO 2.50E-1 TRANSFER RCl-XHE-XO-ERROR OPERATOR FAILS TO START/CONTROL RCIC 1.00E-3 INJECTION RHR-FAN-FS-BC RHR MDP 2B/2C ROOM COOLER FAN FAILS TO START 8.42E-4 RHR-FAN-TM-BC RHR MDP 2B/2C ROOM COOLER FAN UNAVAILABLE 2.00E-3 49

ASP Analysis Unit 1 Attachment E LER 373/13-002 DUE TOT&M RHR-HTX-TM-HTXB RHR HTX-B IN MAINTENANCE (PSA) 2.36E-3 RHR-MDP-FS-2A RHR TRAIN 2A FAILS TO START 9.47E-4 RHR-MDP-FS-2B RESIDUAL HEAT REMOVAL MOP 2B FAILS TO START 9.47E-4 RHR-MDP-TM-2A RHR MOP 2A IS UNAVAILABLE BECAUSE OF 5.66E-3 MAINTENANCE (PSA)

RHR-MDP-TM-2B RHR MOP 2B IS UNAVAILABLE BECAUSE OF 5.66E-3 MAINTENANCE (PSA)

RHR-MOV-CC-F003A RHR HTX A DISCHARGE MOV 3A FAILS TO OPEN 9.63E-4 RHR-MOV-CC-F003B RHR HTX B DISCHARGE MOV 3B FAILS TO OPEN 9.63E-4 RHR-MOV-CC-MINFA RHR TRAIN A MINFLOW MOV FAILS TO OPEN 9.63E-4 RHR-MOV-CC-MINFB RHR TRAIN B MINFLOW LINE MOV FAILS TO OPEN 9.63E-4 RHR-MOV-00-BYPSA RHR LOOP A HTX BYPASS MOV 48A FAILS TO CLOSE 9.63E-4 RH R-MOV-00-BYPSB RHR LOOP B HTX BYPASS MOV 48B FAILS TO CLOSE 9.63E-4 RHR-XHE-XM-ERROR OPERATOR FAILS TO START/CONTROL RHR 5.00E-4 RRS-MDP-LK-SEALS RECIRCULATION PUMP SEALS FAIL 1.00E-1 SCW-MDP-FS-DG2A STANDBY COOLING WATER MOP TO DG2A FAILS TO 9.47E-4 START SCW-MDP-TM-DGO sew PUMP TO DGO IS UNAVAILABLE BECAUSE OF 1.32E-2 MAINTENANCE SCW-MDP-TM-DG2A sew PUMP TO DG2A IS UNAVAILABLE BECAUSE OF 1.32E-2 MAINTENANCE SCW-MDP-TM-DG2B sew PUMP TO DG2B IS UNAVAILABLE BECAUSE OF 1.32E-2 MAINTENANCE SCW-MOV-CC-68A RHR HTX A DISCHARGE ISOLATION VALVE 68A FAILS 9.63E-4 TO OPEN SCW-MOV-CC-68B RHR HTX B DISCHARGE ISOLATION VALVE 68B FAILS 9.63E-4 TO OPEN SCW-MOV-TM-F068B sew MOV F068B IN MAINTENANCE (PSA) 1.30E-3 SCW-STR-TM-TRNB RHR SW TRAIN B STRAINER IN MAINTENANCE (PSA) 3.00E-4 SCW-XHE-TM-RHRB OPERATOR FAILS TO ALIGN THE TRAIN B AFTER TM 1.00E-3 (PRA) 50

ASP Analysis Unit 1 and Unit 2 Attachment F LER 373/13-002 Additional Details No Effect on the ASP Analysis F.1 Unit 2 HPCS Pinhole Leak As reported in LER 37 4-2013-001 (Reference 5.2), on April 18, 2013, at 2:00 p.m. CST (23 hours2.662037e-4 days 0.00639 hours 3.80291e-5 weeks 8.7515e-6 months after the LOOP), with the Unit in Mode 3, the licensee identified three grouped, pencil-sized, through-wall leaks on the first elbow downstream of a flow reducing orifice on the Unit 2 HPCS minimum flow line. The total leakage was estimated to be about Y2 gallon-per-minute.

Because of the location (i.e., just before the minimum flow line connection to the full flow test line and return to the suppression pool), the leaks were not isolable from the suppression pool and could have affected the operability of the HPCS system and primary containment.

Operators declared the Unit 2 HPCS system and primary containment inoperable and implemented the applicable Technical Specifications (TS) actions. Though declared inoperable, the Unit 2 HPCS system remained available for operation (i.e., the pump could have performed its safety function) until 9:00 a.m. on April 21st when the water leg pump was secured to support repair of the elbow. Therefore, since the HPCS pump was ran successfully during the event and would have successfully fulfilled its mission time, no modeling changes were necessary for this analysis.

F.2 Unit 1 LPCS Switch As reported in LER 373-2013-003 (Reference 5.3), on April 18,2013 at about 1:00 p.m. (22 hours2.546296e-4 days 0.00611 hours 3.637566e-5 weeks 8.371e-6 months after the LOOP). CST, with Unit 1 operating in Mode 3, control room operators were attempting to raise Unit 1 reactor vessel level with the LPCS system when they discovered that LPCS Injection Valve 1E21.,.F005 failed to open when the valve control switch was held in the "open" position. High resistance of control switch S2 Contact 1-1T may not allow sufficient voltage across the open contact coil for 1E21-F005. This would prevent manual opening of the valve from the control room, but does not prevent the automatic opening of 1E21-F005 when the switch is in the "AUTO" position because none of the contacts of S2 are used in the auto-opening circuit of the valve. Control Switch S2 isspring-returned to the "AUTO" position. On April 1th, the previous day during the 5.5 hour5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months LOOP the LPCS system would have functioned properly with the switch in the "AUTO" position, therefore, no modeling changes were necessary for this analysis.

F.3 Unit 2 Scram from Secondary System As reported in LER 374-2013-002 (Reference 5.9), on April 25, 2013 (8 days afterthe LOOP),

at 56 percent power, the circulating water pumps tripped on high condenser pit water level, requiring Unit 2 to be manually scrammed. While dewatering the east condenser waterbox an inlet isolation valve was moved past its closed position, which allowed flow from the running circulating water pumps to overflow the waterbox through the open upper manways. This event was screened out due to not meeting the prescribed criteria for the agency's Accident Sequence Precursor program as to having minimal risk significance.

F.4Unit1 RCIC Not Operational per Technical Specifications As reported in LER 373-2013-004 (Reference 5. 7), on April 22, 2013 (5 days after the LOOP),

at approximately 0723 hours0.00837 days 0.201 hours 0.0012 weeks 2.751015e-4 months CDT, while in Mode 2 (Startup), reactor pressure was increased above 150 psig with the RCIC system isolated and inoperable. Technical Specification requires RCIC to be operable in Mode 1, 2, & 3 with reactor steam dome pressure greater than 150 psig. This event was screened out due to not meeting the prescribed criteria for the agency's Accident Sequence Precursor program as to having minimal risk significance.

51

ASP Analysis Unit 1 and Unit 2 Attachment F LER 373/13-002 F .5 Unit 1 RCIC Steam Leak As reported in LER 373-2013-005 (Reference 5.8), on April 27, 2013 (10 days after the LOOP),

Unit 1 was in Mode 2 (Startup) following a forced outage. At 1800 hours0.0208 days 0.5 hours 0.00298 weeks 6.849e-4 months CDT, during a walk down of the drywell, a steam leak was observed coming from the RCIC Steam Supply Inboard Isolation Bypass/Warm up Valve (1 E51-F076), a normally-closed, one inch, motor operated valve. The leak was determined to be on the valve bonnet extension-to-bonnet upper seal weld. At 2124 hours0.0246 days 0.59 hours 0.00351 weeks 8.08182e-4 months CDT the leak was classified as reactor coolant pressure boundary. The apparent cause was a weld defect or discontinuity from the original weld construction (i.e.,

manufacturing, installation/construction errors, etc.) of the upper seal weld that propagated through wall as result of system loading and conditions (i.e., high pressure steam) during normal plant operations. This condition has no impact for the LOOP ASP analysis where the RCIC system functioned.

52

ASP Analysis Unit 2 Attachment G LER 373/13-002 RHR Pump 2C Breaker Closing Circuit (Page 1 of 3)

Circuit Breaker Closing Coil X is energized with a start signal from the control switch or an auto-start signal from relay K21 as long as the Circuit Breaker Closing Springs are fully charged as controlled by the Closing Springs Limit Switch LSa contact. As soon as the Circuit Breaker Closing Springs discharge to close the breaker, Closing Spring Limit Switch contact LSb, closes to energize the Anti-Pumping Relay Y. Simultaneously, Closing Spring Limit Switch contact LSa opens to deenergize the Circuit Breaker Closing Coil X since the breaker is now closed. The Anti-Pumping Relay Y remains energized through its own Ya contact until the circuit logic is manually reset or Relay K21 drops out from removal of the initiating signal or a low or degraded voltage condition, even after the 3-5 seconds it takes for the springs to recharge. Closing Coil X, thus cannot be reenergized a second time without these conditions, since the Anti-Pumping Circuit Relay Yb contact opens the circuit to the Circuit Breaker Closing Coil X. A manual reset occurs by placing the control switch in Stop to energize the Trip Coil TC and deenergize the Anti-Pumping Relay Y logic.

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ASP Analysis Unit 2 Attachment G LER 373/13-002 RHR Pump 2C Auto Start Relay K21 Logic (Page 2 of 3)

IHl!--Plll CC*?

H&l*P&Ol UU**O Relay K21 has contacts in the RHR Pump circuit breaker closing circuit (Attachment G, page 1 of 3) to close the breaker on high drywell pressure and reactor low level from relay K94B and inhibit the breaker closing on degraded voltage from relay K38 START' RHB PUMP *~

tE12*C002C (Drawing 1E-1-4220AL) 54

ASP Ana\ys\s Unit 2 u:.R 373/'\3~002 Rl'IR purnP 2c Auto start RelaV 1(38 and K948 1.-ogic with Degraded \/olta9e Inhibit (Page 3 of 3)

Rl-1R pumP 2c coo\JO\ relays 1(36 aod \<.94 ""'e contacts to control Relay 1<21 io the puma circuit brea circuit, (J>.ttacnmeot G page 2 ol 3). RelaY 1(946 is actuated 1rom \lig\l drywell pressure aod reactor \O' Relay 1(36 io\libita the pumP circuit brea1<er trom c\osiog wit\l \ow or degraded ,01tage from Relay 142 J>.P040X41SG snowo oo orawiog 1e-1-4oos1>.T 55

ML15107A154 OFFICE LPL3-2/PM LPL3-2/LA LPL3-2/BC LPL3-2/PM NAME BPurnell SRohrer TT ate BPurnell DATE 4/20/15 4/20/15 4/20/15 4/21/15

ML15107A154

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