ML092860281

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Final Accident Sequence Precursor Analysis of January 15, 2008 Event
ML092860281
Person / Time
Site: Point Beach  NextEra Energy icon.png
Issue date: 10/20/2009
From: Justin Poole
Plant Licensing Branch III
To: Meyer L
Florida Power & Light Energy Point Beach
Poole Justin/DORL/LPL3-1/ 301-415-2048
References
Download: ML092860281 (24)
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{{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 20, 2009 Mr. Larry Meyer Site Vice President FPL Energy Point Beach, LLC 6610 Nuclear Road Two Rivers, WI 54241-9516

SUBJECT:

POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 - FINAL ACCIDENT SEQUENCE PRECURSOR ANALYSIS OF JANUARY 15, 2008 EVENT

Dear Mr. Meyer:

The enclosed provides the final results of the Accident Sequence Precursor (ASP) analysis of an event which occurred at Point Beach Nuclear Plant (PBNP) as documented in Licensee Event Report No. 266/08-001, dated March 14, 2008. The subject event occurred on January 15, 2008, during which PBNP experienced a loss of transformer 1X04, low voltage station auxiliary transformer for Unit 1, resulting in the declaration an Unusual Event and performing a manual shutdown. The condition was documented in U.S. Nuclear Regulatory Commission (NRC) Inspection Report No. 05000266/2008007, dated April 1,2008. This is being issued as a final analysis since it is a non-controversial, lower-risk precursor for which the ASP results are consistent with the results of the final evaluation of the Significance Determination Process. Elimination of the review and comment resolution for this event will reduce the burden for the NRC staff and the licensee. Please contact me at (301) 415-2048 if you have any questions regarding the enclosure. Sincerely, Justin C. Poole, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-266 and 50-301

Enclosure:

As stated cc w/encl: Distribution via ListServ

Concurrent Loss of Station Auxiliary Transformer 1X-04 and Point Beach, Unit 1 480V Safeguards Bus 1B-04. LER: 266/2008-001 7x10-6 Event Date: 01/15/2008 I iJ.CDP= IR: 50-266/2008-07 EVENT

SUMMARY

Event Description. Unit 1 experienced a lockout and loss of Low Voltage Station Auxiliary Transformer 1X-04 (offsite power supply to the Unit 1 4.16 kV safeguards busses) at 1404, on January 15, 2008. The unit concurrently experienced a loss of 480V Safeguards Bus 1B-04. All four emergency diesel generators (EDGs) responded as designed. As a result of loss of Bus 1B-04, the normal letdown valve closed and the operator controlled the pressurizer level by aligning the excess letdown line and utilized minimum charging flow. Safeguards Bus 1B-04 was recovered approximately 6.5 hours after it was lost. On recovering Safeguards Bus 1B-04, normal letdown could not immediately be established, owing to difficulties with Letdown Isolation Valve 1CV-371A. In compliance with Technical Specification requirements, Unit 1 shutdown commenced on January 16, 2008 at 1549, and Unit 1 was in Mode 3 at 1948 on January 16, 2008. Further event information is provided in References 1 and 2. Cause. The licensee concluded that the cause of the cable failure from the 1X-04 Transformer to Buses 1A-03 and 1A-04 was a direct fault to ground of the 'B5' cable for the feed to Bus 1A 03 and that this fault was caused by long-term water induced degradation of the cable's outer jacket, shield, and insulation. The licensee's root cause team concluded that the organization failed to assign the appropriate prioritization to address the issue of submerged power cables. The spurious actuation of the 50G relay of Breaker 1A52-84 was likely due to high frequency transients caused by the repeated grounding of cabling associated with the low side of the 1X 04 Transformer. As a result, the licensee's root cause team concluded that the settings for this relay were too conservative. In addition, laboratory testing determined that the relay would actuate on primary current spike duration less than the existing time delay setting. Additional Event Details. The sequence of key events is provided in Appendix A. Recovery Opportunities. Safeguards Bus 'IB-04 was recovered at 2049 on January 15 (approximately 6.5 hours after it was lost). The 6.5 hour concurrent loss of Station Auxiliary Transformer 1X-04 and 480V Safeguards Bus 1B-04 is the event window for this analysis. Analysis Rules. The Accident Sequence Precursor (ASP) Program uses Significance Determination Process (SOP) results for degraded conditions when available. However, the ASP Program performs independent initiating event analysis when an initiator occurs and a condition analysis when there are no performance deficiencies identified for a particular event. In addition, the ASP Program analyzes separate degraded conditions that were present during 1

LER 266/08-001 the same period and similar degraded conditions on an individual system or component that had different performance deficiencies. Three GREEN findings have been identified for this event and are described in Reference 2. Since there was no plant trip and separate performance deficiencies were evaluated by the SOP, this analysis focuses solely on the risk due to concurrent loss of Station Auxiliary Transformer 1X-04 and 480V Safeguards Bus 1B-04. ANALYSIS RESULTS Importance 1 The importance for this event is 7x10-6. The results of an uncertainty assessment on the importance are summarized below. Point Beach 1 I 5% Mean 95% 1.3x10-6 6.5x 10-6 1.8x10-5 The ASP Program acceptance threshold is an importance of 1x10-6. Dominant Sequences The dominant accident sequences, TRANS Sequences 02-06-05,02-08-05, and 02-10-05, contribute to 63% (1.3x10-6 per sequence) of the total internal events' importance. The sequences involve a loss of reactor coolant pump seal cooling and subsequent seal loss of-coolant accident (LOCA), failure to rapidly depressurize the secondary, failure to depressurize the reactor coolant system, and failure of high-pressure recirculation. The dominant sequences are shown in Figures B-1 and B-2 of Appendix B. The events and important component failures in TRANS Sequences 02-06-05, 02-08-05, and 02-10-05 are: The reactor trips, auxiliary feedwater is successful, power-operated relief valves (PORV) correctly reseat (if opened), reactor coolant pump seal cooling is lost, operators successfully trip the RCPs, rapid secondary depressurization fails, reactor coolant pump seal LOCA initiates (o-ring extrusion of Stage 1 and/or Stage 2 seals), feedwater is successful, high-pressure injection is successful, secondary side cooldown is successful, reactor depressurization fails, and high-pressure recirculation fails. 1 For a conditional assessment, the parameter of interest is the measure of importance. This value is obtained subtracting the baseline core damage probability (COP) from the conditional core damage probability (CCDP). 2

LER 266/08-001 Results Tables The conditional probabilities for the dominant sequences are shown in Table 1. The event tree sequence logics for the dominant sequences are presented in Table 2a. Table 2b defines the nomenclature used in Table 2a. The most important cutsets for the dominant sequences are listed in Table 3. Definitions and probabilities for modified or dominant basic events are provided in Table 4. MODELING ASSUMPTIONS Analysis Type The Revision 3-Plus (Change 3.45) of the Point Beach 1 and 2 Standardized Plant Analysis Risk (SPAR) model [Ref. 3] created in June 2008 was used for this assessment. This event was modeled as a Unit 1 concurrent loss of Station Auxiliary Transformer 1X-04 and 480V Safeguards Bus 1B-04. Unique Design Features Point Beach has a somewhat unique dependence on instrument air and a unique dependence of AFW on operator action. Manual action (basic event AFW-XHE-XM MINGAG) is needed in order to preserve AFW function. This circumstance drives a relatively high SPAR model result for baseline CDF for this plant. Modeling Assumptions Summary Key Modeling Assumptions. This event is analyzed using the GEM module in SAPHIRE. The risk increase that this ASP analysis focuses is due to three event factors: (1) the increased probability of a reactor trip (i.e., failure of operators to initiate excess letdown and minimize charging flow, (2) the loss of Station Auxiliary Transformer 1X-04, and (3) concurrent loss of 480V Safeguards Bus 1B-04. The time window for this risk increase is 6.5 hours. This event analysis is conditional analysis; however, the GEM initiating event module was utilized because the conditional probability of reactor trip cannot be converted into a frequency. The base CDP for this short time window is considered negligible when compared the CCDP; therefore, the importance equals the CCDP for this analysis. Basic Event Probability Changes Table 4 provides all the basic events that were modified to reflect the best estimate of the conditions during the event. The basis for these changes is provided below: ACP-BAC-LP-1B04 set to TRUE. This basic event represents the Safeguards Bus 1B04 that failed during the event and was unavailable for 6.5 hours. This event was set to TRUE. ACP-TFM-FC-1X04 set to TRUE. This basic event represents the Station Auxiliary Transformer 1X04 that failed during the event; therefore, this event was set to TRUE. 3

LER 266/08-001 ACP-XHE-XM-B089 set to 0.65. This basic event represents operators failing to align power to Busses B08 and B09 per abnormal operating procedures. In many of dominant cutsets, this operator action would follow ACP-XHE-XM-2A031A03 (operators fail to transfer power from Bus 2A03 to Bus 1A03) in the postulated accident sequence. After a review of the applicable sequences and cutsets, the staff determined that dependency needed to be addressed for ACP-XHE-XM-B089. Based on the dependency matrix provided in Reference 4, it was determined that this event was highly dependent (same crew, close time, different locations) on ACP-XHE-XM 2A031A03. Therefore, the failure probability of ACP-XHE-XM-B089 was calculated to be 0.65 using the dependency formula [Ref. 4]. IE-TRANS set to 2x1U2* In this analysis, IE-TRANS does not represent the reactor trip frequency. Rather, it represents the conditional probability of operators failing to establish excess letdown and minimize charging to flow to control pressurizer level and preclude a trip. This probability was calculated using the SPAR-H method [Ref. 4] and details of this evaluation are provided in Appendix C. All other initiating event frequencies were set to zero due to their very small probabilities during this short time window (i.e., the 6.5 hours of concurrent unavailability of the Station Auxiliary Transformer 1X-04 and Safeguards Bus 1B-04). REFERENCES

1. LER 266/08-001 Rev. 0, "Manual Reactor Shutdown Required by Technical Specification LCO 3.8.1 AC Sources-Operating Not Met," March 16, 2008.
2. U.S. Nuclear Regulatory Commission, "Point Beach Nuclear Plant-NRC Special Inspection Report 05000266/2008007," April 21,2008.
3. Idaho National Laboratory, "Standardized Plant Analysis Risk Model for Point Beach 1 and 2," Revision 3 Plus (Change 3.45), June 2008.
4. Idaho National Laboratory, "The SPAR-H Human Reliability Analysis Method," I\\lUREG/CR 6883, August 2005.

4

LER 266/08-001 02-06-05 02-08-05 02-09-05 20 02-07-05 02-10-05 1.3E-006 13E-006 1.3E-006 7.5E-007 6.5E-007 6.5E-007 21.3 21.3 21.3 12.3 10.7 10.7 Total (all sequences)! 6.1E-006 100

1. Values arepointestimates.
2. Total CCDP includes all sequences (including thosenot shown in this table).

Table 2a. Event tree sequence louie for dominatinq sequences. RSD RSD IRCPT HPR IRCPT HPR 02-10-05 20 02-07-05 02-09-05 02-08-05 TRANS TRANS TRANS TRANS TRANS 02-06-05 IRPS IAFW IPORV LOSC IRCPT RSD IBP2 02 IFW IHPI ISSC PZR HPR IRPS IAFW IPORV LOSC IRCPT RSD IBP2 102 IFW IHPI ISSC PZR HPR IRPS IAFW IPORV LOSC IRCPT RSD IBP2 02 IFW IHPI ISSC PZR HPR IRPS AFW MFW FAB IRPS IAFW IPORV LOSC BP2 IFW IHPI ISSC PZR IRPS IAFW IPORV LOSC BP2 IFW IHPI ISSC PZR TRANS IBP1 IBP1 IBP1 IBP1 IBP1 01 101 101 01 01 Table 2b. Definitions of top events listed in Table 2a. TopEvent AFW BP1 BP2 FAB FW HPI HPR LOSC MFW 01 02 PORV PZR RCPT RPS RSD SSC I Definition AUXILIARY FEEDWATER RCP SEAL STAGE 1 INTEGRITY RCP SEAL STAGE 2 INTEGRITY FEED AND BLEED FEEDWATER (AFW or MFW) HIGH PRESSURE INJECTION HIGH PRESSURE RECIRCULATION LOSS OF SEAL COOLING MAIN FEEDWATER RCP SEAL STAGE 1 INTEGRITY RCP SEAL STAGE 2 INTEGRITY PORV/SRVs ARE CLOSED RCS DEPRESS FOR LPI/RHR REACTOR COOLANT PUMPS TRIPPED REACTOR TRIP RAPID SECONDARY DEPRESSURIZATION SECONDARY SIDE COOLDOWN 5

LER 266/08-001 T ble 3 Condi cutsets for t h a itiona e dorninant sequences. 3.4E-007 26.0 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 ACP-XHE-XM-B0809 IRCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 IRCS-MDP-LK-01 ACP-CRB-CC-57 7.8E-008 6.06 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 EPS-DGN-FR-G02 IRCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 IRCS-MDP-LK-01 EPS-DGN-FR-G01 7.8E-008 6.01 RCS-MDP-LK-BP1 RCS-MDP-LK-02 CVC-XHE-XM-112B IRCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 IRCS-MDP-LK-01 ACP-CRB-CC-57 6.5E-008 5.02 EPS-XHE-XM-G02-1A05 IRCS-MDP-LK-01 EPS-DGN-FR-G01 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 ACP-XHE-XM-B0809 IRCS-MDP-LK-BP2 ACP-XHE-XM-2A031 A03 5.8E-008 4.50 ACP-TFM-FC-1 X13 IRCS-MDP-LK-O1 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 IRCS-MDP-LK-BP2 ACP-XHE-XM-B0809 1.3E-006 I 100 I Total (all cutsets)' TRANS, Sequence 02-08-05 3.4E-007 26.0 IRCS-MDP-LK-BP1 IRCS-MDP-LK-02 ACP-XHE-XM-B0809 IRCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 RCS-MDP-LK-01 ACP-CRB-CC-57 7.8E-008 6.06 IRCS-MDP-LK-BP1 IRCS-MDP-LK-02 EPS-DGN-FR-G02 IRCS-MDP-LK-BP2 ACP-XH E-XM-2A031A03 ACP-XHE-XM-B0809 RCS-MDP-LK-01 EPS-DGN-FR-G01 7.8E-008 6.01 RCS-MDP-LK-BP1 IRCS-MDP-LK-02 CVC-XHE-XM-112B IRCS-MDP-LK-BP2 ACP-XH E-XM-2A031 A03 RCS-MDP-LK-01 ACP-CRB-CC-57 6.5E-008 5.02 EPS-XHE-XM-G02-1A05 RCS-MDP-LK-01 EPS-DGN-FR-G01 IRCS-MDP-LK-BP1 IRCS-MDP-LK-02 ACP-XHE-XM-B0809 IRCS-MDP-LK-BP2 ACP-XH E-XM-2A031 A03 5.8E-008 4.50 ACP-TFM-FC-1X13 RCS-MDP-LK-01 IRCS-MDP-LK-BP1 IRCS-MDP-LK-02 IRCS-MDP-LK-BP2 ACP-XHE-XM-B0809 1.3E-006 I 100 I Total (all outsets]" TRANS, Sequence 02-09-05 3.4E-007 26.0 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 ACP-XHE-XM-B0809 IRCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 RCS-MDP-LK-01 ACP-CRB-CC-57 7.8E-008 6.06 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 EPS-DGN-FR-G02 IRCS-MDP-LK-BP2 ACP-XH E-XM-2A031 A03 ACP-XHE-XM-B0809 RCS-MDP-LK-01 EPS-DGN-FR-G01 7.8E-008 6.01 RCS-MDP-LK-BP1 RCS-MDP-LK-02 CVC-XHE-XM-112B IRCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 RCS-MDP-LK-01 ACP-CRB-CC-57 6.5E-008 5.02 EPS-XHE-XM-G02-1A05 RCS-MDP-LK-01 EPS-DGN-FR-G01 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 ACP-XH E-XM-B0809 IRCS-MDP-LK-BP2 ACP-XH E-XM-2A031 A03 5.8E-008 4.50 ACP-TFM-FC-1X13 RCS-MDP-LK-01 IRCS-MDP-LK-BP1 RCS-MDP-LK-02 IRCS-MDP-LK-BP2 ACP-XHE-XM-B0809 1.3E-006 I 100 I Total (all cutsets)" ';T~J~;';~l............. l~t ~'\\:> MJnlmum.~tS*{df~ events) iC~~ TRANS, Sequence 02-06-05

1. Total CCDP Includes all cutsets (Including those not shown In this table).

6

LER 266/08-001 Min~(Of~~eWnts) "<,,>i>< TRANS, Sequence 20 1.1E-007 14.5 8.6E-008 11.5 5.3E-008 7.04 2.6E-008 3.52 7.5E-007 100 Total (all cutsets)" TRANS, Sequence 02-07-05 IAS-MDC-CF-K2AB3ABR AFW-XHE-XM-MINGAG IAS-MDC-FR-K2A AFW-XHE-XM-MINGAG IAS-MDC-FR-K2B IAS-MDC-FR-K3B ACP-XHE-XM-2A031A03 AFW-XHE-XM-MINGAG ACP-CRB-CC-57 FPS-EDP-TM-P35B ACP-XHE-XM-2A031A03 ACP-CRB-CC-57 1.7E-007 26.1 3.9E-008 6.06 3.9E-008 6.01 3.3E-008 5.03 2.9E-008 4.50 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 EPS-XHE-XM-G02-1A05 /RCS-MDP-LK-01 ACP-XHE-XM-B0809 ACP-TFM-FC-1X13 /RCS-MDP-LK-01 6.5E-007 100 Total (all cutsets)" TRANS, Sequence 02-10-05 1.7E-007 26.1 3.9E-008 6.06 3.9E-008 6.01 3.3E-008 5.03 2.9E-008 4.50 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 EPS-XHE-XM-G02-1A05 RCS-MDP-LK-O 1 ACP-XHE-XM-B0809 ACP-TFM-FC-1X13 RCS-MDP-LK-01 RCS-MDP-LK-BP2 ACP-CRB-CC-57 RCS-MDP-LK-BP2 EPS-DGN-FR-G01 RCS-MDP-LK-BP2 ACP-CRB-CC-57 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP1 ACP-XHE-XM-B0809 RCS-MDP-LK-BP2 ACP-CRB-CC-57 RCS-MDP-LK-BP2 EPS-DGN-FR-G01 RCS-MDP-LK-BP2 ACP-CRB-CC-57 /RCS-MDP-LK-BP1 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP1 ACP-XHE-XM-B0809 /RCS-MDP-LK-01 ACP-XHE-XM-B0809 /RCS-MDP-LK-01 EPS-DGN-FR-G02 /RCS-MDP-LK-01 CVC-XHE-XM-112B RCS-MDP-LK-BP2 EPS-DGN-FR-G01 RCS-MDP-LK-BP2 RCS-MDP-LK-01 ACP-XHE-XM-B0809 RCS-MDP-LK-01 EPS-DGN-FR-G02 RCS-MDP-LK-01 CVC-XHE-XM-112B RCS-MDP-LK-BP2 EPS-DGN-FR-G01 RCS-MDP-LK-BP2 6.5E-007 100 Total (all cutsets)"

1. Total CCDP includes all cutsets (including those not shown in this table).

7

LER 266/08-001 Table 4. Definitions and probabilities for modified and dominant basic events. Event Name Description Probability! Frequency (per year) ACP-BAC-LP-1 B04 ACP-CRB-CC-57 ACP-TFM-FC-1X04 ACP-TFM-FC-1X13 ACP-XH E-XM-2A031 A03 ACP-XHE-XM-B0809 AFW-XHE-XM-MINGAG CVC-XHE-XM-112B EPS-DGN-CF-RG0102 EPS-DGN-FR-G01 EPS-DGN-FR-G02 EPS-DGN-TM-G01 EPS-DGN-TM-G02 EPS-XHE-XM-G02-1A05 FPS-EDP-TM-P35B IAS-MDC-CF-K2AB3ABR IAS-MDC-FR-K2A IAS-MDC-FR-K2B IAS-MDC-FR-K3B IE-TRANS RCS-MDP-LK-BP1 RCS-MDP-LK-BP2 RCS-MDP-LK-01 RCS-MDP-LK-02 480 VAC BUS 1B-041S UNAVAILABLE XFR 1X04 SUPPLY BREAKER TO BUS 1A05 FAILS TO CLOSE 13.8 KV XFR 1X04 FAILS TRANSFORMER 1X13 FAILS DUE TO LOSS OF POWER OPERATOR FAILS TO TRANSFER POWER FROM 2A03 TO 1A03 OPERATOR FAILS TO ALIGN TO B08/ B09 PER AOP FAILURE TO GAG MINI RECIRC VALVE >1HR INTO EVENT OPERATORS FAILS TO MANUALLY OPEN CV-112B VALVE CCF OF DIESEL GENERATORS G01 AND G02 TO RUN DIESEL GENERATOR G01 FAILS TO RUN DIESEL GENERATOR G02 FAILS TO RUN DIESEL GENERATOR G01 UNAVAILABLE DUE TO T&M DIESEL GENERATOR G02 UNAVAILABLE DUE TO T&M OPERATOR FAILS TO ALIGN G-02 TO 1A-05 FP DIESEL DRIVEN PUMP 35B UNAVAILABLE DUE TO T&M CCF OF lAS COMPRESSORS K-2A, K-2B, K-3A & K-3 INSTRUMENT AIR COMPRESSOR K2A FAILS TO RUN INSTRUMENT AIR COMPRESSOR K2B FAILS TO RUN SERVICE AIR COMPRESSOR K-3B FAILS TO RUN REACTOR TRANSIENT RCP SEAL STAGE 1 INTEGRITY (BINDING/POPPING) RCP SEAL STAGE 2 INTEGRITY (BINDING/POPPING) RCP SEAL STAGE 1 INTEGRITY (O-RING EXTRUSION) RCP SEAL STAGE 2 INTEGRITY (O-RING EXTRUSION) TRUE 1 2.5E-003 TRUE 1 2.2E-005 5.0E-002 6.5E-001 2 2.0E-002 1.5E-001 4.2E-004 2.4E-002 2.4E-002 1.2E-002 1.2E-002 2.0E-002 1.0E-002 2.6E-004 5.9E-002 5.9E-002 5.9E-002 2.1E-0023 1.3E-002 2.0E-001 5.0E-001 5.0E-001

1.

Set the event to TRUE to account for the unavailability of the component. See the Basic Event Probability Section for further details.

2.

Adjusted the probability of the event to 0.65 to account for human error dependency.

3.

Set the event to a probability of 2.1 x10*2. All other initiating event frequencies were set to zero. See the Basic Event Probability Section for further details. 8

LER 281/06-002 APPENDIX A SEQUENCE OF KEY EVENTS Time Event 0146; Multiple reports of loud noise heard on the north side of the Extension Building. The source 1/15/08 was found to be Manhole Number 3 located on the east side of the G05 Building. 0230 Plant manager, operations manager, work-week manager, and duty call superintendent informed of noise heard in Manhole Number 3. 0505 NRC was informed of issue with manhole in vicinity of Transformer 1X-04. 0602 Manhole Number 3 was checked; water level about 1 foot and slowly rising. Cables were not in water. 0611 The operation control center is manned to support the reports of sounds coming from Manhole Number 3 area. 0708 Manhole Number 3 was checked; cables verified not to be in water although water level was slowly rising. 1015 Shift Manager implemented the quarantine procedure to control access to Manhole Number

3. Hourly inspections of the manhole were reduced to twice per shift per engineering direction.

1110 Manhole Number 3 was checked. Cables verified not to be in water although water level was slowly rising. 1150 Walk downs of all plant 4160V and 13.8kV buses completed; SAT and all indications are normal. 1354 Operations reported cables are submerged in Manhole Number 5. 1404 Loss of 1B-04, both units enter TSAC 3.8.9.A. 1X-04 Station Transformer is de-energized resulting is a loss of offsite power to 1A-05 and 1A-06 4160V Safeguards Buses. Unit 1 enters TSAC 3.8.1.C. Both units enter TSAC 3.8.1.0. All four EDGs started on a loss of offsite power to 1A-05 and 1A-06. EDG G01 immediately restored power to Bus 1A-05. EDG G-03 assumed load of Bus 1A-06. Unit 1 enters TSAC 3.8.1.B with required actions B.1 to restore 1X-04 Station Transformer to operable status within 24 hours. 1415 Classification made of an Unusual Event due to loss of offsite power to Unit 1. 1423 Unit 1 Pressurizer Level exceeded the parametric value of 48% due to the loss of CVCS letdown as a result of the 1X-04 Station Transformer lockout and loss of CVCS letdown. Minimum charging flow and excess letdown were established in response to the event. 1430 Control Room notified that 1-51N/X04, 1X-04 over-current neutral relay was found tripped in the 13.8 kV building. 1635 Z-65C manhole NO.3 was checked. Cables verified not to be in water although water level was slowly rising. 1815 Secured EDG G-04. 1828 NRC has entered "monitoring" phase of response related to the loss of Unit 1 1X-04 Low Voltage Station Auxiliary Transformer. 1830 1B-04 (480 Volt Bus) meggered. 1900 Maintenance reports that manhole NO.5 has been pumped out. 1905 Secured EDG G-02. 2032 1B-04 normal feed circuit breaker is shut. 2049 Commenced recovery of 1B-04, 480V AC Safeguards power supply. A-1

LER 266/08-001 Time 'Event 2111 While attempting to restore CVCS letdown on Unit 1, Valve 1CV-371A, Letdown Line Containment Isolation would not open. Both main control board and containment isolation panel status lights indicated the 1CV-371A was shut. 2200 NRC 4 hour event notification EN No. 43908 for the press release was made. 2229 While attempting to establish normal letdown 1CV-371A was taken to the open position. The valve did not move from the full shut position. 0714; Task created to megger between Buses 1A-04 and 1A-06 (between Breakers 54 and 57). 1/16/08 1716 Completed 4-hour event notification worksheet for Unit 1; TS required shutdown commenced. 1917 Tripped main turbine generator output breaker. 1920 Entered Mode 2. 1924 Tripped Main Turbine. 2148 Manhole Number 3 visual inspection is complete. Inspection results, no visual indication of damage of any type noted. 2320 Reactor shutdown completed. A-2

1 LER 281/06-002 APPENDIX B EVENT TREES CONTAINING DOMINANT SEQUENCES --L=c=:: I:: n co I ~"" ~'~CD ~~--~ ~_: Figure B-1. Point Beach 1 transient event tree. LOSS OF ALL SEAL COOLING Lose REACToR COOLANT PUMPS TRIPPED I RAPID SECONDARY DEPRESSURIZATION <<17',0 PSI IN 2 HR) nso "~ I 'C,,'~ STAGE 1 I~TE(;RITY (8INDING/POPPlr,G) (O-RING EXTRUSION) ot I rl,~ s ~-{oo I 10 500 0>00 I 10200 co t t 10>00 00125 --t I ta '.~"" ,m,,'" I cz I 1,,00 C L_ s END*STATE oc T SLOC/l. T SLOCA T '-1LOCA C, T srocs T SLOCA T SLOC/\\ T SLDCA T SLOCA T SLOCA T 5LOCA i.we< T MLOCI\\ I NOTES 21*GPMIRCP , 62*GPMlRCP 16*GPWRC D 480*GPhVRCP 21_GPM-"CP ',noPMlRCP 182_GPMlRCP G1*GPMlRCP ~OO_GPWRCP 300_GPIWI'lCP 7~-GPWRCP 300-GPMlRCP 480_GPWRCP 4B1J*GPlNRCP I Figure B-2. Point Beach 1 loss of Rep seal cooling event tree. B-1 I

LER 281/06-002 APPENDIX C SPAR HUMAN ERROR WORKSHEET Plant: Point Beach 1 Initiating Event: Transient Basic Event: IE-TRANS Basic Event Context: Failure of operators to diagnose loss of normal letdown, initiate excess letdown, and minimize charging flow will result in a scram due to high pressurizer level. Basic Event

Description:

Operator fails to control pressurizer level when let down valves have gone shut to prevent scram annunciation. Operator can only utilize excess let down line and operator charging pumps on a min flow. Does this task contain a significant amount of diagnosis activity? I:8J Yes (start with Part I-Diagnosis) o No (skip Part I-Diagnosis; start with Part II-Action) Why? N/A PART I. EVALUATE EACH PSF FOR DIAGNOSIS f Evaluate PSFs for the Diagnosis Portion 0 the Task, if an PSFs PSF Levels Multiplier for Diagnosis Please note specific reasons for PSF level selection in this column. Available Inadequate Time P(failure) =1.0 Time Barely Adequate Time (",2/3)(nominal) 10 0 Nominal Time 1 [8J Extra Time (between t-zxnormnat and> than 0.1 0 30 min) Expansive Time (> 2)(nominal and> 30 min) 0.01 0 Insufficient Information 1 0 Stress/ Extreme 5 0 Stressors High 2 0 Nominal 1 [8J Insufficient Information 1 0 I Complexity Highly Complex 5 0 Diagnosis considered Moderately Complex Nominal 2 1 [8J 0 moderately complex due to presence of multiple annunciators (e.g., loss of Obvious Diaonosis Insufficient Information 0.1 1 0 0 transformer and vital bus) alarming at the same time as the loss of letdown. Experience/ Low 10 0 Training Nominal 1 [8J High 0.5 0 Insufficient Information 1 0 C-1

LER 266/08-001 PSFs PSF Levels Procedures Not Available Incomplete Available, but Poor Nominal Diagnostic/Symptom Oriented Insufficient Information Ergonomics/ Missing/M isleading HMI Poor Nominal Good Insufficient Information Fitness for Unfit Duty Deqraded Fitness Nominal Insufficient Information Work Poor Processes Nominal Good Insufficient Information Multiplier for Diagnosis 50 0 20 0 5 0 1 [8J 0.5 0 1 0 50 0 10 0 1 [8J 0.5 0 1 0 P(failure) =1.0 5 0 1 [8J 1 0 2 0 1 [8J 0.8 0 1 0 Please note specific reasons for PSF level selection in this column. I Calculate the Diagnosis Failure Probability. (1) If all PSF ratings are nominal, then the Diagnosis Failure Probability = 1x10-2 (2) Otherwise, the Diagnosis Failure Probability = 1x 10-2 x Time x Stress or Stressors x Complexity x Experience or Training x Procedures x Ergonomics or HMI x Fitness for Duty x Processes Diagnosis HEP: 1x10-2 x 1 x 2 x 1 x 1 x 1 x 1 x 1 x1 = 2)(10-2 C-2

LER 266/08-001 PART II. EVALUATE EACH PSF FOR ACTION E I t PSFs for the Acion tl PortiIon 0 fthe Task Iof anv. va ua e I PSFs PSF Levels Multiplier for Diagnosis Please note specific reasons for PSF level selection in this column. Available Inadequate Time P(failure) = 1.0 Time Time available" Time Required Nominal Time Time available> 5x the time required 10 0 1 ~ 0.1 0 0.01 0 1 0 Time available is > 50x the time required Insufficient Information Stress/ Stressors Extreme High Nominal Insufficient Information 5 0 2 0 1 ~ 1 0 Complexity Highly Complex Moderately Complex Nominal Insufficient Information 5 0 2 0 1 ~ 1 0 Experience/ Training Low Nominal Hiqh Insufficient Information 3 0 1 ~ 0.5 0 1 0 Procedures Not Available Incomplete Available, but Poor Nominal Insufficient Information 50 0 20 0 5 0 1 ~ 1 0 Ergonomics/ HMI Missinq/Misleadinq Poor Nominal Good Insufficient Information 50 0 10 0 1 ~ 0.5 0 1 0 Fitness for Unfit P(failure) = 10 Duty Degraded Fitness Nominal Insufficient Information 5 0 1 ~ 1 0 Work Processes Poor Nominal Good Insufficient Information 5 0 1 ~ 0.5 0 1 0 C-3

LER 266/08-001 Calculate the Action Failure Probability. (1) If all PSF ratings are nominal, then the Action Failure Probability = 1x1 0-3 (2) Otherwise, the Action Failure Probability = 1x1 0-3 x Time x Stress or Stressors x Complexity x Experience or Training x Procedures x Ergonomics or HMI x Fitness for Duty x Processes Action HEP: 1x10-3 x 1 x 1 x 1 x 1 x 1 x 1 x 1 x1 =1)(10-3 PART III. CALCULATE TASK FAILURE PROBABILITY WITHOUT FORMAL DEPENDENCE (PWIOO) Calculate the Task Failure Probability without Formal Dependence (Pwfod) 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. PwfOd =Diagnosis HEP [2)(10-2] + Action HEP [1)(10-3] =~.1)(10*1 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 (Pwfd). 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: This event is the postulated event initiator; therefore, no dependence is considered. C-4

LER 281/06-002 APPENDIX D BEST ESTIMATE GEM RUN I NIT I A TIN G EVE N T ASS E SSM E N T Fam PBCH 3P User INEEL Ev ID: BEST-ESTIMATE Desc : Concurrent Loss Safeguards Bus Event Name ACP-BAC-LP-1B04 ACP-TFM-FC-1X04 ACP-XHE-XM-B0809 IE-FLB IE-ISL-HPI IE-ISL-LPI IE-ISL-RHR IE-LLOCA IE-LOCCW IE-LOCHS IE-LODCD01 IE-LODCD02 IE-LOlA IE-LOMFW IE-LOOP IE-LOSWS IE-MLOCA IE-RXVRUPT IE-SGTR IE-SLB IE-SLOCA IE-TRANS Code Ver : 7: 27 Model Ver : 2008/07/08 Init Event: IE-TRANS Total CCDP: 6.1E-006 of Station Auxiliary Transformer 1X-04 1B-04. BASIC EVENT CHANGES Description 480 VAC BUS 1B-04 IS UA 13.8 KV XFR 1X04 Fails OPERATOR FAILS TO ALIGN FEED/STEAM LINE BREAK ISLOCA IE HPI Interface ISLOCA IE LPI Interface RHR Pipe Ruptures LARGE LOCA Loss OF CCW LOSS OF CONDENSER HEAT SINK LOSS OF 125 VDC BUS DOl Loss OF 125 VDC BUS D02 LOSS OF INSTRUMENT AIR LOSS OF MAIN FEEDWATER LOSS OF OFFSITE POWER LOSS OF SERVICE WATER MEDIUM LOCA REACTOR VESSEL RUPTURE STEAM GENERATOR TUBE RUPTURE STEAM LINE BREAK SMALL LOCA TRANSIENT Base Prob 9.6E-006 2.2E-005 3.0E-001 3.0E-003 2.3E-006 2.0E-009 4.0E-006 2.5E-006 4.0E-004 8.0E-002 6.0E-004 6.0E-004 1.0E-002 1.0E-001 +O.OE+OOO 4.0E-004 2.0E-004 1.0E-007 4.0E-003 1.2E-002 6.0E-004 8.0E-001 and 480V Curr Prob Type 1.0E+000 TRUE 1.0E+000 TRUE 6.5E-001 +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO +O.OE+OOO 2.1E-002 SEQUENCE PROBABILITIES Truncation Cumulative 95.0% Individual

1. 0%

Event Tree Name Sequence Name CCDP TRANS TRANS TRANS TRANS TRANS TRANS 02-06-05 02-08-05 02-09-05 20 02-07-05 02-10-05

1. 3E- 006 1.3E-006 1.3E-006 7.5E-007 6.5E-007 6.5E-007 D-1

LER 266/08-001 SEQUENCE LOGIC Event Tree Sequence Name TRANS 02-06-05 TRANS 02-08-05 TRANS 02-09-05 TRANS 20 TRANS 02-07-05 TRANS 02-10-05 /RPS /PORV /RCPT /BP1 /BP2 /FW /SSC HPR /RPS /PORV /RCPT /BP1 /BP2 /FW /SSC HPR /RPS /PORV /RCPT /BP1 /BP2 /FW /SSC HPR /RPS MFW /RPS /PORV /RCPT /BP1 BP2 /HPI PZR /RPS /PORV /RCPT /BP1 BP2 /HPI PZR Logic /AFW LOSC RSD /01 02 /HPI PZR /AFW LOSC RSD 01 /02 /HPI PZR /AFW LOSC RSD 01 02 /HPI PZR AFW FAB /AFW LOSC RSD /01 /FW /SSC HPR /AFW LOSC RSD 01 /FW /SSC HPR D-2

LER 266/08-001 Fault Tree Name Description AFW BP1 BP2 FAB FW HPI HPR LOSC MFW 01 02 PORV PZR RCPT RPS RSD SSC SEQUENCE CUT SETS Truncation: Event Tree: TRANS Sequence: 02-06-05 CCDP % Cut Set 3.4E-007 26.05 7.8E-008 6.06 7.8E-008 6.01 6.5E-008 5.02 5.8E-008 4.50 5.6E-008 4.35 3.9E-008 3.01 AUXILIARY FEEDWATER RCP SEAL STAGE 1 INTEGRITY RCP SEAL STAGE 2 INTEGRITY FEED AND BLEED FEEDWATER (AFW or MFW) HIGH PRESSURE INJECTION HPR PRESSURE RECIRCULATION LOSS OF SEAL COOLING MAIN FEEDWATER RCP SEAL STAGE 1 INTEGRITY RCP SEAL STAGE 2 INTEGRITY PORV/SRVs ARE CLOSED RCS DEPRESS FOR LPI/RHR REACTOR COOLANT PUMPS TRIPPED REACTOR TRIP RAPID SECONDARY DEPRESS SECONDARY SIDE COOLDOWN Cumulative: 90.0% Individual: 2.5% CCDP:

1. 3E- 006 Cut Set Events

/RCS-MDP-LK-BP1 /RCS-MDP-LK-BP2 /RCS-MDP-LK-01 RCS-MDP-LK-02 ACP-XHE-XM-2A031A03 ACP-CRB-CC-57 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 /RCS-MDP-LK-BP2 /RCS-MDP-LK-01 RCS-MDP-LK-02 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G01 EPS-DGN-FR-G02 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 /RCS-MDP-LK-BP2 /RCS-MDP-LK-01 RCS-MDP-LK-02 ACP-XHE-XM-2A031A03 ACP-CRB-CC-57 CVC-XHE-XM-112B EPS-XHE-XM-G02-1A05 /RCS-MDP-LK-BP1 /RCS-MDP-LK-BP2 /RCS-MDP-LK-01 RCS-MDP-LK-02 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G01 ACP-XHE-XM-B0809 ACP-TFM-FC-1X13 /RCS-MDP-LK-BP1 /RCS-MDP-LK-BP2 /RCS-MDP-LK-01 RCS-MDP-LK-02 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 /RCS-MDP-LK-BP2 /RCS-MDP-LK-01 RCS-MDP-LK-02 EPS-DGN-CF-RG0102 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 /RCS-MDP-LK-BP2 /RCS-MDP-LK-01 RCS-MDP-LK-02 ACP-XHE-XM-2A031A03 EPS-DGN-TM-G01 0-3

LER 266/08-001 3.9E-00B 3.01 3.2E-00B 2.50 Event Tree: TRANS Sequence: 02-0B-05 CCDP % Cut Set 3.4E-007 26.05 7.BE-00B 6.06 7.BE-00B 6.01 6.5E-00B 5.02 5.8E-008 4.50 5.6E-008 4.35 3.9E-008 3.01 3.9E-00B 3.01 3.2E-00B 2.50 EPS-DGN-FR-G02 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G01 EPS-XHE-XM-G02-1A05 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 EPS-DGN-TM-G01 Cut /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 ACP-XHE-XM-BOB09 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 CVC-XHE-XM-112B EPS-XHE-XM-G02-1A05 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 EPS-DGN-FR-G01 ACP-TFM-FC-1X13 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 EPS-DGN-CF-RG0102 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G01 EPS-XHE-XM-G02-1A05 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 EPS-DGN-TM-G01 ACP-XHE-XM-BOB09 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 EPS-DGN-TM-G02 ACP-XHE-XM-BOB09 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 ACP-XHE-XM-BOB09 CCDP: 1.3E-006 Set Events /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 ACP-CRB-CC-57 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 EPS-DGN-FR-G01 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 ACP-CRB-CC-57 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 EPS-DGN-TM-G01 ACP-XHE-XM-BOB09 /RCS-MDP-LK-BP2 /RCS-MDP-LK-02 EPS-DGN-TM-G02 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 D-4

LER 266/08-001 Event Tree: TRANS Sequence: 02-09-05 Cut /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 CVC-XHE-XM-112B EPS-XHE-XM-G02-1A05 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 EPS-DGN-FR-G01 ACP-TFM-FC-1X13 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 EPS-DGN-CF-RG0102 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G01 EPS-XHE-XM-G02-1A05 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 EPS-DGN-TM-G01 Cut IAS-MDC-CF-K2AB3ABR IAS-MDC-FR-K2A AFW-XHE-XM-MINGAG ACP-XHE-XM-2A031A03 ACP-CRB-CC-57 FPS-EDP-TM-P35B ACP-CRB-CC-57 0-5 CCDP:

1. 3E- 006 Set Events

/RCS-MDP-LK-BP2 RCS-MDP-LK-02 ACP-CRB-CC-57 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 EPS-DGN-FR-G01 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 ACP-CRB-CC-57 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 EPS-DGN-TM-G01 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP2 RCS-MDP-LK-02 EPS-DGN-TM-G02 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 CCDP: 7.5E-007 Set Events AFW-XHE-XM-MINGAG IAS-MDC-FR-K2B IAS-MDC-FR-K3B AFW-XHE-XM-MINGAG ACP-XHE-XM-2A031A03 CCDP 3.4E-007 7.8E-008 7.8E-008 6.5E-008 5.8E-008 5.6E-008 3.9E-008 3.9E-008 3.2E-008 Event % Cut Set 26.05 6.06 6.01 5.02 4.50 4.35 3.01 3.01 2.50 Tree: TRANS Sequence: 20 CCDP % Cut Set 1.lE-007 8.6E-008 5.3E-008 2.6E-008 14.47 11.49 7.04 3.52

LER 266/08-001 Event Tree: TRANS Sequence: 02-07-05 CCDP % Cut Set 1.7E-007 3.9E-008 3.9E-008 3.3E-008 2.9E-008 2.8E-008 2.0E-008 2.0E-008 1.6E-008 26.05 6.06 6.01 5.03 4.50 4.35 3.02 3.02 2.50 Event Tree: TRANS Sequence: 02 05 CCDP % Cut Set

1. 7E- 007 3.9E-008 3.9E-008 3.3E-008 26.05 6.06 6.01 5.03 Cut

/RCS-MDP-LK-BP1 /RCS-MDP-LK-01 ACP-CRB-CC-57 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 EPS-DGN-FR-G01 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 ACP-CRB-CC-57 EPS-XHE-XM-G02-1A05 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 ACP-TFM-FC-1X13 RCS-MDP-LK-BP2 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 EPS-DGN-TM-G02 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 EPS-DGN-TM-G01 ACP-XHE-XM-B0809 EPS-XHE-XM-G02-1A05 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 Cut /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-CRB-CC-57 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 EPS-DGN-FR-G01 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-CRB-CC-57 EPS-XHE-XM-G02-1A05 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 D-6 CCDP: 6.5E-007 Set Events RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 CVC-XHE-XM-112B /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 EPS-DGN-FR-G01 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 RCS-MDP-LK-BP2 EPS-DGN-CF-RG0102 ACP-XHE-XM-B0809 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G01 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 /RCS-MDP-LK-BP1 /RCS-MDP-LK-01 EPS-DGN-TM-G01 CCDP: 6.5E-007 Set Events RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 CVC-XHE-XM-112B /RCS-MDP-LK-BP1 RCS-MDP-LK-01 EPS-DGN-FR-G01

LER 266/08-001 ACP-TFM-FC-1X13 RCS-MDP-LK-BP2 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 ACP-XHE-XM-2A031A03 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 EPS-DGN-TM-G02 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 EPS-DGN-TM-G01 ACP-XHE-XM-B0809 EPS-XHE-XM-G02-1A05 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 RCS-MDP-LK-BP2 EPS-DGN-CF-RG0102 ACP-XHE-XM-B0809 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G01 RCS-MDP-LK-BP2 ACP-XHE-XM-2A031A03 EPS-DGN-FR-G02 /RCS-MDP-LK-BP1 RCS-MDP-LK-01 EPS-DGN-TM-G01 2.9E-008 2.8E-008 2.0E-008 2.0E-008 1.6E-008 4.50 4.35 3.02 3.02 2.50 BASIC EVENTS Event Name ACP-CRB-CC-57 ACP-TFM-FC-1X13 ACP-XHE-XM-2A031A03 ACP-XHE-XM-B0809 AFW-XHE-XM-MINGAG CVC-XHE-XM-112B EPS-DGN-CF-RG0102 EPS-DGN-FR-G01 EPS-DGN-FR-G02 EPS-DGN-TM-G01 EPS-DGN-TM-G02 EPS-XHE-XM-G02-1A05 FPS-EDP-TM-P35B IAS-MDC-CF-K2AB3ABR IAS-MDC-FR-K2A IAS-MDC-FR-K2B IAS-MDC-FR-K3B RCS-MDP-LK-BP1 RCS-MDP-LK-BP2 RCS-MDP-LK-01 RCS-MDP-LK-02 (Cut Sets Only) Description XFR 1X04 SUPPLY BREAKER TO BUS lAOS FAILS TO TRANSFORMER 1X13 FAILS DUE TO LOSS OF POWER OPERATOR FAILS TO TRANSFER POWER FROM 2A03 TO OPERATOR FAILS TO ALIGN TO B08 / B09 PER AOP FAILURE TO GAG MINI RECIRC VALVE >lHR INTO EV OP. FAILS TO MAN. OPEN CV-112B VALVE (RWST TO CCF OF DIESEL GENERATORS G01 AND G02 TO RUN DIESEL GENERATOR G01 FAILS TO RUN DIESEL GENERATOR G02 FAILS TO RUN DIESEL GENERATOR G01 UNAVAILABLE DUE TO T&M DIESEL GENERATOR G02 UNAVAILABLE DUE TO T&M OPERATOR FAILS TO ALIGN G-02 TO 1A-05U1 ECA-O FP DIESEL DRIVEN PUMP 35B UNAVAILABLE DUE TO CCF OF lAS COMPRESSORS K-2A, K-2B, K-3A & K-3 INSTRUMENT AIR COMPRESSOR K2A FAILS TO RUN INSTRUMENT AIR COMPRESSOR K2B FAILS TO RUN SERVICE AIR COMPRESSOR K-3B FAILS TO RUN RCP SEAL STAGE 1 INTEGRITY (BINDING/POPPING 0 RCP SEAL STAGE 2 INTEGRITY (BINDING/POPPING 0 RCP SEAL STAGE 1 INTEGRITY (O-RING EXTRUSION) RCP SEAL STAGE 2 INTEGRITY (O-RING EXTRUSION) Curr Prob 2.5E-003 2.2E-005 5.0E-002 6.5E-001 2.0E-002 1.5E-001 4.2E-004 2.4E-002 2.4E-002 1.2E-002 1.2E-002 2.0E-002 1.0E-002 2.6E-004 5.9E-002 5.9E-002 5.9E-002 1.3E-002 2.0E-001 5.0E-001 5.0E-001 0-7

October 20, 2009 Mr. Larry Meyer Site Vice President FPL Energy Point Beach, LLC 6610 Nuclear Road Two Rivers, WI 54241-9516

SUBJECT:

POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 - FINAL ACCIDENT SEQUENCE PRECURSOR ANALYSIS OF JANUARY 15, 2008 EVENT

Dear Mr. Meyer:

The enclosed provides the final results of the Accident Sequence Precursor (ASP) analysis of an event which occurred at Point Beach Nuclear Plant (PBNP) as documented in Licensee Event Report No. 266/08-001, dated March 14, 2008. The subject event occurred on January 15, 2008, during which PBNP experienced a loss of transformer 1X04, low voltage station auxiliary transformer for Unit 1, resulting in the declaration an Unusual Event and performing a manual shutdown. The condition was documented in U.S. Nuclear Regulatory Commission (NRC) Inspection Report No. 05000266/2008007, dated April 1, 2008. This is being issued as a final analysis since it is a non-controversial, lower-risk precursor for which the ASP results are consistent with the results of the final evaluation of the Significance Determination Process. Elimination of the review and comment resolution for this event will reduce the burden for the NRC staff and the licensee. Please contact me at (301) 415-2048 if you have any questions regarding the enclosure. Sincerely, Ira! Justin C. Poole, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-266 and 50-301

Enclosure:

As stated cc w/encl: Distribution via ListServ DISTRIBUTION PUBLIC LPL3-1 rlf RidsNrrDorlLpl3-1 Resource RidsNrrPMPointBeachResource RidsNrrLATHarrisResource RidsAcrsAcnw_MailCTRResource RidsOgcRpResource RidsRgn3MailCenterResource RidsNrrDorlDprResource ADAMS Accession Number: ML092860281

  • 'per memo dated J une 19, 2009 OFFICE NAME DATE LPL3-1/PM LPL3-1/LA RES/DRAID THarris CLui*

10/15/09 6/19/09 LPL3-1/BC ~IPoole RPascarelli 10/19/09 10/20109 OFFICIAL RECORD COpy}}

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