IR 05000395/2005006
| ML050880440 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 01/14/2005 |
| From: | Casto C Division of Reactor Safety II |
| To: | Archie J South Carolina Electric & Gas Co |
| References | |
| IR-05-006 EA-05-008 | |
| Download: ML050880440 (22) | |
Text
ary 14, 2005
SUBJECT:
VIRGIL C. SUMMER NUCLEAR STATION - NRC INSPECTION REPORT 05000395/2005006; PRELIMINARY WHITE FINDING
Dear Mr. Archie:
This letter and the enclosed supporting documentation discuss a finding that appears to have low to moderate safety significance [White]. Section 4OA5.2.1.1 of NRC Inspection Report 05000395/2004009, issued on December 22, 2004, identified this finding [Unresolved Item (URI) 05000395/2004009-01] which concerned inadequacies in your corrective actions associated with a deficiency in the design of the emergency feedwater (EFW) system flow control valves. This deficiency could have resulted in a common mode failure of the EFW system as a result of plugging of the valves by tubercles and debris in the service water system.
This item was unresolved pending the NRCs determination of the safety significance.
This finding was assessed based on the best available information, including influential assumptions, using the applicable Significance Determination Process (SDP) and was preliminarily determined to be a White finding (i.e., a finding with some increased importance to safety, which may require additional NRC inspection).
As indicated in the enclosed SDP Phase III Analysis, the issue appears to have a low to moderate safety significance due to the importance of continued EFW system availability, when supplied by the service water suction source, during events which deplete or render the condensate storage tank inoperable. However, the risk associated with this deficiency was somewhat mitigated by the fact that the finding only affected the alternate suction source for the EFW system and did not impact normal EFW system operation. Additionally, other core cooling mechanisms, such as use of the main feedwater system or primary system feed and bleed were not affected.
This finding does not present an immediate safety concern because you instituted compensatory measures including operator actions to install temporary hoses to bypass the EFW flow control valves if they become plugged.
SCE&G 2 Two apparent violations (AV) of 10 CFR 50, Appendix B were identified regarding this finding.
The first, an apparent violation of Criterion III, Design Control, is identified as AV 05000395/2005006-01: EFW Flow Control Valves Are Susceptible to Plugging by Tubercles and Other Debris from Service Water. The second, an apparent violation of Criterion XVI, Corrective Actions, is identified as AV 05000395/2005006-02: Inadequate Corrective Actions in Response to Potential EFW Control Valve Plugging. These apparent violations are being considered for escalated enforcement action in accordance with the "General Statement of Policy and Procedure for NRC Enforcement Actions (Enforcement Policy), NUREG-1600.
The current Enforcement Policy is included on the NRCs website at http://www.nrc.gov/what-we-do/regulatory/enforcement/enforce-pol.html. Accordingly, for administrative purposes, URI 05000395/2004009-01, is considered closed.
Before we make a final decision on this matter, we are providing you an opportunity (1) to present to the NRC your perspectives on the facts and assumptions, used by the NRC to arrive at the finding and its significance, at a Regulatory Conference or (2) submit your position on the finding to the NRC in writing. If you request a Regulatory Conference, it should be held within 30 days of the receipt of this letter and we encourage you to submit supporting documentation at least one week prior to the conference in an effort to make the conference more efficient and effective. If a Regulatory Conference is held, it will be open for public observation and the NRC will issue a press release to announce the conference. If you decide to submit only a written response, such submittal should be sent to the NRC within 30 days of the receipt of this letter.
Please contact Mr. Charles R. Ogle at (404) 562-4605 within seven days of the date of this letter to notify the NRC of your intentions regarding the regulatory conference for the preliminary White finding. If we have not heard from you within 10 days, we will continue with our significance determination and associated enforcement processes on this finding, and you will be advised by separate correspondence of the results of our deliberations on this matter.
Since the NRC has not made a final determination in this matter, no Notice of Violation is being issued for the inspection finding at this time. In addition, please be advised that the number and characterization of the apparent violations may change as a result of further NRC review.
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its enclosure and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of NRCs document system (ADAMS). ADAMS is accessible from the NRC web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
SCE&G 3 If you have any questions regarding this letter, please contact me at (404) 562-4600.
Sincerely,
/RA By R. Haag For/
Charles A. Casto, Director Division of Reactor Safety Docket No.: 50-395 License No.: NPF-12 Enclosure: SDP Phase III Analysis w/Attachments cc w/encl.:
R. J. White Ronald B. Clary, Manager Nuclear Coordinator (Mail Code 802) Nuclear Licensing (Mail Code 830)
S.C. Public Service Authority South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station Virgil C. Summer Nuclear Station Electronic Mail Distribution Electronic Mail Distribution Kathryn M. Sutton, Esq.
Winston and Strawn Electronic Mail Distribution Henry J. Porter, Director Division of Radioactive Waste Mgmt.
Dept. of Health and Environmental Control Electronic Mail Distribution R. Mike Gandy Division of Radioactive Waste Mgmt.
S.C. Department of Health and Environmental Control Electronic Mail Distribution Thomas D. Gatlin, General Manager Nuclear Plant Operations (Mail Code 303)
South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station Electronic Mail Distribution Distribution w/encl.:
SCE&G 4 K. Cotton, NRR L. Slack, RII RIDSNRRDIPMIIPB PUBLIC OEMail S. Sparks, RII
- For Previous Concurrence See Attached Copy OFFICE RII:DRS RII:DRS RII:DRS RII:DRP RII:EICS SIGNATURE CRO JHM2 RPS KDL CFE NAME COgle JMoorman BSchin KLandis CEvans DATE 1/13/2005 1/13/2005 1/13/2005 1/13/2005 1/13/2005 E-MAIL COPY? YES NO YES NO YES NO YES NO YES NO YES NO YES NO PUBLIC DOCUMENT YES NO YES NO YES NO YES NO YES NO YES NO YES NO OFFICIAL RECORD COPY DOCUMENT NAME: E:\Filenet\ML050880440.wpd
SRA Analysis Number: SUM0403 Analysis Type: SDP Phase III Inspection Report # : 2005006 Plant Name: V. C. Summer Unit Number: 1 Enforcement Action #: EA-05-008 I. Background - At V.C. Summer the Condensate Storage Tank (CST) is the normal suction supply for the Emergency Feedwater System (standard Westinghouse design -
two motor driven and one turbine driven prime movers). Since the CST is not design to withstand tornados, an alternate supply from the Service Water System was provided.
The piping interconnecting the two systems contains stagnant service water.
Microbiological tubercles are growing and have been growing for many years on the inside diameter of these stagnant pipe segments.
The most flow-restricting passages in the system are in the flow control valves (IFV-3531-EF, IFV-3541-EF, IFV-3551-EF, IFV-3536-EF, IFV-3546-EF, and IFV-3556-EF).
The flow control valves contain a cylindrical trim with several hundred orifices through which the EFW flow to each steam generator passes. Based upon observing a spare flow control valve trim, the orifices are widened with a countersink to about 0.125 inches in diameter on the flow entry side and narrow to 0.049 inches in diameter on the flow exit side. The total flow area of the orifices in a single valve trim is about 0.91 square inches. There are no strainers in the EFW system that would prevent particles larger than the these flow-restricting passages from entering the system. The NRC team physically agitated samples of tubercles by rapidly shaking them in a container, to simulate turbulent flow through an EFW pump, and found that most of the tubercle pieces did not pulverize but instead broke into small solid pieces approximately 0.125 to 0.25 inches in diameter. The tubercle pieces were larger than the orifices and therefore could potentially plug the orifices. The team calculated that, with an operating differential pressure across a flow control valve of about 100 pounds per square inch, the differential pressure across each orifice would be about 0.2 pounds. The team found that the sample tubercle pieces were resistant to compressive forces, so that if they became wedged into the orifices, they would likely be able to withstand much more than 0.2 pounds of compressive forces without breaking up.
The original purchase specification for the EFW flow control valves (SP-620-044461-000, dated October 16, 1974) had identified the process fluid as "cold condensate."
Therefore, these EFW valves had been specified for use with clean condensate water and not for use with comparatively unclean SW which could contain silt and other debris from the SW pond plus clam shells, tubercles, and other debris from the SW piping.
This mis-application of the purchased EFW flow control valves, which were designed for clean condensate, to handle unclean SW in the plant represented inadequate design control.
The licensee became aware of this potential blockage issue in 1986 and has had other opportunities to identify the significance of this design vulnerability since that time.
Licensee corrective actions have been inadequate to resolve this design vulnerability.
Enclosure
Performance Deficiency - The licensees corrective actions in response to a deficiency in the design of the EFW flow control valves was inadequate.
Specifically, the licensees design control failed to specify that the EFW flow control valves were required to be able to handle relatively unclean SW without plugging.
Instead, the EFW flow control valves were specified to handle a process fluid of clean cold condensate. Tubercles as well as other debris in the service water system could plug the valves thereby resulting in a common mode failure of the EFW system.
Despite multiple opportunities, the licensees corrective action program failed to correct the condition in a timely manner.
Exposure Time - 1 year Date of Occurrence - Condition has existed for numerous years II. Safety Impact: WHITE III. Risk Analysis/Considerations Assumptions 1. Upon transfer of the Emergency Feedwater System (EFW) suction to the Service Water System (SWS) the tubercles will plug the FCVs stopping sufficient flow to any Steam Generator.
2. Failure of the CST as the suction source for the Emergency Feedwater System will cause a reactor trip during the ensuing plant shutdown. The failure of the CST is estimated at 1E-7 failure/hour * 8760 hour0.101 days <br />2.433 hours <br />0.0145 weeks <br />0.00333 months <br />s/yr = 8.76E-4/yr. {INEEL telecon of database search for equipment failure}
3. For every reactor trip recovery of Main Feedwater is assumed to occur 90% of the time. This is the estimate from the Phase 2 Screening Sheets due to plant modifications that allow this. These modifications are not reflected in the licensees full scope model.
4. In the absence of the tubercles the failure of the Service Water System as a suction for the Emergency Feedwater System is estimated at 1E-3 (a multi-train system). Therefore, the non-conforming condition will be assumed to be the delta CDF since the conforming case CDF is <<. (Unless specifically quantified by computer models)
Enclosure
5. Recovery of the Emergency Feedwater System, once transferred to the SWS suction source will not be considered. The FCV cages are assumed to be plugged to the point of insufficient flow to the Steam Generators. Operators would be able to recognize that insufficient flow was going to the Steam Generators.
6. However, there would be no procedure direction, training or experience that allow the operators to unplug the FCVs or provide a bypass around the plugged valves. Also, there would be no equipment available to accomplish such a task.
7. The CST function will be assumed to be lost at the medium wind speed/intensity of a F2 tornado (135 mph). The frequency of all tornadoes of this intensity or higher striking the site is estimated to be 6E-5/yr as extrapolated from Figure 3-2 Tornado Hazard Curve - Exceedance (page 3-6) contained in the June 1995 IPEEE High Winds Evaluation in response to Generic Letter 88-20, Supplement 4. All tornadoes assumed to cause loss of the CST function will also cause Loss of Offsite Power without recovery.
8. The critical piping segment from CST to EFW is estimated at 30 yards in length with 10 welds. Failure consideration will be by Design and Construction Defects (D&C) and Corrosion Attack (COR) mechanisms. From Table A-33, Pipe failure Rates for Westinghouse Feedwater and Condensate Systems, of EPRI TR-111880, Piping System Failure Rates and Rupture Frequencies for Use In Risk Informed In-service Inspection Applications, the per foot or per weld failure probability is:
COR = 8.47E-8 failure/yr/ft * 90 ft = 7.6E-6 failure/yr D&C = 6.89E-7 failure/yr/weld * 10 welds = 6.89E-6 failure/yr Total = 6.89E-6 + 7.6E-6 = 1.45E-5 failure/yr 9. Based upon a review of the licensees safe shutdown strategy procedures following a fire, it is assumed that when operators remain in the Main Control Room (MCR), the train used for safe shutdown is assumed to be fully protected either by 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> barrier, 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> barrier with suppression or a separation of 20 feet between trains. Those procedures presently indicate that the CST would be the suction source for the protected EFW train unless the CST was expended.
Consequently, fire effects causing actuation of the alternate EFW suction source (SWS) could only happen to the unprotected train. For the unprotected train to affect the protected EFW train it would require a significant number of spurious actuations, including pump start and two suction valves to open before the protected train would be impacted. This is screened as not credible.
Enclosure
Premature transfer of the protected train suction to SWS will be considered credible due to random events and a fully developed fire in the 7.2KV Switchgear Room (Train A) will be used as the surrogate for this situation.
Possible spurious actuation of the SWS valves to the EFW suction source caused by the fire will be considered for those cases where alternate shutdown (shutdown from outside the MCR) is used. The fire in the Main Control Room will be used as the surrogate to screen this situation. Also, in all fire accident sequences it is assumed the licensee will execute a plant shutdown to cold shutdown before the CST volume is expended.
PRA Model used for basis of the risk analysis: Combination of hand calculation, modified Phase 2 Screening Sheet and SPAR run in the GEM mode.
Significant Influence Factor(s) [if any]: The failure of the SWS to EFW function is always lost when called upon and the tornado severity at which the CST function as a suction source to EFW is lost.
IV. Calculations BASE CASE - N/A NON-CONFORMING CASE a. Internal Events In the non-conforming case two broad conditions will be analyzed. First the full demand spectrum from all initiating events normally included in an internal events model will be considered. In this case the normal EFW suction path fails upon demand. The SPAR model is used to calculate the delta CDF by setting the basic event EFW-XHE-XA-SWS, OPERATOR FAILS TO ALIGN SW TO EFW, to always fail (TRUE). The model quantification details are provided in Attachment 2. Summarizing the delta CDF was 4.7E-8/yr. Due to its small contribution it will be excluded from the quantification.
Second there is a special case not explicitly covered by the internals event model that must be included. This involves the special case where the normal EFW suction source is known to be out of service and requires plant shutdown with an ensuing reactor trip.
The failure of the CST and the failure the piping segments from the CST to EFW pump suctions will be quantified to estimate this initiating event. As indicated in the assumptions section, tank failure is set at 8.76E-4 and the piping segment failure is set at 1.45E-5. The collective loss of the CST function is estimated at 8.9E-4/yr. This represents the Initiating Event frequency.
Enclosure
To acquire the CCDP portion of the CDF the SPAR model in the GEM mode was solved for the transient initiating event with:
EFW-TNK-FC-CST1 set to TRUE - this sets the CST to always fail this will later be substituted with the new initiating event frequency that correlates to tank loss.
EFW-XHE-XA-SWS set to TRUE - this sets the Service Water System supply to the EFW pumps to always fail - the performance deficiency.
MFW-XHE-XL-TRANS & MFW-XHE-XL-TRIP set to 0.1 - this provides a possible site- specific use of MFW as a viable secondary side heat removal mechanism (consistent with assumption 3).
The details of the computer run is provided as Attachment 3. In summary the derived CCDP was 6.2E-3. The non-conforming CDF is 8.9E-4/yr * 6.2E-3 = 5.5E-6 Correlation with the Phase 2 Screening Sheets - The Phase 2 Screening Sheet for Transients is solved using the 8.9E-4 IEL converted to a 3 and the EFW function set to zero. The accident sequences are shown in Attachment 4 and result in a 6,6 & 7 or White. This is consistent with the computerized calculation.
b. External Events Earthquake - Based upon the licensees IPEEE (page 13-2) estimated that the High Confidence of Low Probability of Failure (HCLPF) for the Service Water Pond Dam was 0.22g while the CST was estimated at > 0.3g. Therefore, Service Water is estimated to fail before the CST due to earthquake and will be excluded from quantification.
Fire - Fully developed fire with operators shutting down from the MCR - Compartment 1DA is the surrogate and considered the dominant fire since there are almost 40 ignition sources capable of causing a fully developed fire and the compartment does not contain a fixed suppression system. A fire of 16 minutes duration will be postulated to cause operators to enact the mitigation strategy which includes inducing a Station Blackout and re-establishing power to the B train via the B Emergency Diesel Generator.
Therefore, MFW recovery will not be considered. From 0609, Appendix F page F8-6 the non-suppression probability of an electrical fire is 0.15. Possible mechanisms that could cause EFW suction transference to SWS are spurious valve operations, spurious failure of 2 of the 4 level transmitters or tank failure. For purposes of scoping only a single valve or level transmitter failure will be quantified at 5E-7/hr for the valve (NUREG 4550)
+ 5E-6/hr for an instrument + 1E-7/hr for tank failure over a 24 hr mission time yields 1E-4. A conservative scoping quantification would be:
The fully developed fire frequency would be 2.3E-3 (fire frequency) * 1.5E-1 (suppression failure Pr) * 1E-4 (EFW transfer to SWS) = 3E-8 Enclosure
Fully developed fire with operators shutting down from outside the MCR. Use the MCR fire as the screen. From SDP Appendix F, MCR fire frequency is 8E-3. Assuming a fire of approximately 16 minutes would be needed to cause spurious operation of the applicable valves, the manual suppression failure probability is estimated to be 0.02 (Appendix F page F8-6).
Partitioning the MCR into the critical panel portion that could impact these valves to be 1/4 of the MCR panels would provide an addition 0.25 reduction factor. Two valves in the train to be used for shutdown from outside the MCR would have to change state in this critical portion of the MCR panel. Appendix F page F-48 estimates a spurious operation of 0.6. Calculating 8E-3 * 2E-2 * 2.5E-1 * 6E-1 * 6E-1 = 1.4E-5. This would be a fully developed fire requiring MCR evacuation with subsequent failure of the EFW System due to transferring onto the SWS suction source. However, even though not procedurialized there would be adequate time to establish feed & bleed as a mitigation strategy. Using a 2E-2 failure probability as representative of this strategy failing (1E-2 for the F&B portion and 1E-2 for the HPR portion), the CDF would screen at 3E-7.
These two scoping quantifications provide the perspective that the fire initiating event would not be a major risk contributor for this performance deficiency.
Tornado - The CST was not designed to withstand a tornado or the effects of a tornado.
Using the exceedence probability for wind speeds at an F2 median frequency as the initiating event, yields 6E-5/yr. SPAR was run in the GEM mode with:
the LOSP initiating event for severe weather set at 6E-5 EFW-TNK-FC-CST1 set to TRUE - this sets the CST to always fail due to a tornado EFW-XHE-XA-SWS set to TRUE - this sets the Service Water System supply to the EFW pumps to always fail - the performance deficiency The non-conforming CDF result was 1.4E-6. See Attachment 5 for th details of the computer run.
As a sensitivity analysis for tornado wind speeds in excess of 150 mph (the upper end of the F2 scale) correlates to a 1E-6 CDF..
Correlation with the Phase 2 Screening Sheets - The surrogate for external events is LOSP. By altering the LOOP Screening Sheet from the Phase 2 Notebook to 6E-5 for the initiating event correlates to a 4 for the IEL, the EFW function is set to zero and the REC functions are set to zero. The accident sequences are shown in Attachment 6 and resulted in a 6, 6, 7 & 7 or White and consistent with the computerized calculation.
Enclosure
External Events Summary - The external events analysis was to ascertain whether the White result of the internal events is altered by the external events. Evaluation of the external events contribution indicates that the risk significance is not sufficient to increase internal events results.
DELTA CDF FOR EXPOSURE TIME Since the exposure time is for one year there is no alteration of the delta CDF from the previous section.
LERF CONSIDERATION The dominant accident sequences involving this performance deficiency do not include SGTR or ISLOCA as the initiating event. Therefore, the LERF contribution is considered not to exceed the CDF risk bands.
V. Conclusions/Recommendations - Risk increase over the base case was >1E-6 but <1E-5.
VI. Attachments 1. Phase I Screening Sheets 2. Sws to efw.wpd *
3. CCDP for Loss of CST as Initiating Event 4. Phase 2 Screening Sheet - Trans Initiating Event 5. Tornado SWS to EFW.wpd 6. Phase 2 Screening Sheet - LOOP Initiating Event Analyst: W. Rogers Date: 12/22/04 Reviewed By: R. Bernhard Date: 12/22/04 M. Franovich Date: 12/29/04 per telecon Enclosure
SWS TO EFW.WPD CONDITION ASSESSMENT Code Version: 7:22 Model Version : 2004/12/10 Project : SUMM_3 Duration (hrs) : 8.8E+003 User Name : IDAHO NATIONAL LABORATORY (INL) Total CCDP : 1.4E-005 Event ID : SWS-TO-EFW-OOS Total CDP : 1.4E-005 Importance : 4.7E-008 Description : Condition Assessment sws to efw failed for one year BASIC EVENT CHANGES Event Name Description Base Prob Curr Prob Type
---------------------------- --------- --------- ------
EFW-XHE-XA-SWS OPERATOR FAILS TO ALIGN SW T 1.0E-003 1.0E+000 TRUE
________________________________________________________________________________
SEQUENCE PROBABILITIES Truncation : Cummulative : 100.0% Individual : 1.0%
Event Tree Name Sequence Name CCDP CDP Importance
------------------------ --------- --------- ----------
TRANS 17 4.5E-007 4.1E-007 3.4E-008 LDCA 20 7.8E-007 7.7E-007 6.0E-009 TRANS 16 5.0E-008 4.6E-008 3.7E-009 LOOP 17 3.3E-008 3.1E-008 1.6E-009 NOTE: Percent contribution to total Importance.
SEQUENCE LOGIC Event Tree Sequence Name Logic
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TRANS 17 /RPS EFW MFW FAB LDCA 20 /RPS EFW FAB TRANS 16 /RPS EFW MFW /FAB HPR LOOP 17 /RPS /EPS EFW-L FAB-L Fault Tree Name Description
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EFW EMERGENCY FEEDWATER EFW-L SUMMER PWR B EMERGENCY FEEDWATER SYSTEM DURING LOOP 2004/12/21 11:10:02 page 1
Attachment 2 EPS EMERGENCY POWER FAB FEED AND BLEED FAB-L FEED AND BLEED DURING LOOP HPR HPR PRESSURE RECIRCULATION MFW MAIN FEEDWATER SYSTEM RPS REACTOR TRIP
________________________________________________________________________________
SEQUENCE CUT SETS Truncation: Cummulative: 100.0% Individual: 1.0%
Event Tree: TRANS CCDF: 4.5E-007 Sequence: 17 CCDF % Cut Set Cut Set Events
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1.6E-007 36.04 EFW-MDP-CF-FRAB EFW-TDP-FR MFW-SYS-FC-TRIP HPI-XHE-XM-FB 4.1E-008 9.22 EFW-MDP-CF-FRAB EFW-TDP-TM MFW-SYS-FC-TRIP HPI-XHE-XM-FB 4.0E-008 9.01 EFW-MDP-CF-FRAB EFW-TDP-FR MFW-SYS-FC-TRANS HPI-XHE-XM-FB 3.4E-008 7.68 EFW-MDP-CF-FRAB EFW-TDP-FS-1 MFW-SYS-FC-TRIP HPI-XHE-XM-FB 2.7E-008 6.04 EFW-TNK-FC-CST1 MFW-SYS-FC-TRIP HPI-XHE-XM-FB 2.5E-008 5.62 EFW-MDP-CF-FSAB EFW-TDP-FR MFW-SYS-FC-TRIP HPI-XHE-XM-FB 1.0E-008 2.30 EFW-MDP-CF-FRAB EFW-TDP-TM MFW-SYS-FC-TRANS HPI-XHE-XM-FB 8.6E-009 1.92 EFW-MDP-CF-FRAB EFW-TDP-FS-1 MFW-SYS-FC-TRANS HPI-XHE-XM-FB 7.6E-009 1.70 EFW-CKV-CF-DIS MFW-SYS-FC-TRIP HPI-XHE-XM-FB 7.6E-009 1.70 EFW-CKV-CF-SUCT MFW-SYS-FC-TRIP HPI-XHE-XM-FB 7.6E-009 1.70 EFW-CKV-CF-SGS MFW-SYS-FC-TRIP HPI-XHE-XM-FB 7.4E-009 1.66 EFW-PMP-CF-ALL MFW-SYS-FC-TRIP HPI-XHE-XM-FB 6.7E-009 1.51 EFW-TNK-FC-CST1 MFW-SYS-FC-TRANS HPI-XHE-XM-FB 6.4E-009 1.44 EFW-MDP-CF-FSAB EFW-TDP-TM MFW-SYS-FC-TRIP HPI-XHE-XM-FB 6.3E-009 1.40 EFW-MDP-CF-FSAB EFW-TDP-FR MFW-SYS-FC-TRANS HPI-XHE-XM-FB 5.7E-009 1.28 EFW-MDP-CF-FRAB EFW-XHE-XR-TDP1 MFW-SYS-FC-TRIP HPI-XHE-XM-FB 5.3E-009 1.20 EFW-MDP-CF-FSAB EFW-TDP-FS-1 MFW-SYS-FC-TRIP HPI-XHE-XM-FB 2004/12/21 11:10:02 page 2 Attachment 2
Event Tree: LDCA CCDF: 7.8E-007 Sequence: 20 CCDF % Cut Set Cut Set Events
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3.5E-007 45.34 EFW-MDP-TM-1B EFW-TDP-FR 7.5E-008 9.66 EFW-MDP-TM-1B EFW-TDP-FS-1 7.0E-008 9.07 EFW-TDP-FR EFW-XHE-XR-MDP1B 3.6E-008 4.62 EFW-MDP-CF-FRAB EFW-TDP-FR 2.8E-008 3.63 EFW-PMP-FR-1A EFW-TDP-FR 2.7E-008 3.50 EFW-MDP-FR-1B EFW-TDP-FR EFW-XHE-XL-MDPFRB 1.8E-008 2.32 EFW-TDP-TM EFW-XHE-XR-MDP1B 1.8E-008 2.29 EFW-MDP-FS-1B EFW-TDP-FR EFW-XHE-XL-MDPFSB 1.5E-008 1.93 EFW-TDP-FS-1 EFW-XHE-XR-MDP1B 1.3E-008 1.61 EFW-MDP-TM-1B EFW-XHE-XR-TDP1 1.2E-008 1.55 DCP-BDC-LP-1B 9.2E-009 1.18 EFW-MDP-CF-FRAB EFW-TDP-TM Event Tree: TRANS CCDF: 5.0E-008 Sequence: 16 CCDF % Cut Set Cut Set Events
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1.6E-008 32.19 HPR-XHE-XM EFW-MDP-CF-FRAB EFW-TDP-FR MFW-SYS-FC-TRIP 4.1E-009 8.23 HPR-XHE-XM EFW-MDP-CF-FRAB EFW-TDP-TM MFW-SYS-FC-TRIP 4.0E-009 8.05 HPR-XHE-XM EFW-MDP-CF-FRAB EFW-TDP-FR MFW-SYS-FC-TRANS 3.4E-009 6.86 HPR-XHE-XM EFW-MDP-CF-FRAB EFW-TDP-FS-1 MFW-SYS-FC-TRIP 2.7E-009 5.39 HPR-XHE-XM EFW-TNK-FC-CST1 MFW-SYS-FC-TRIP 2.5E-009 5.02 HPR-XHE-XM EFW-MDP-CF-FSAB EFW-TDP-FR MFW-SYS-FC-TRIP 1.0E-009 2.06 HPR-XHE-XM EFW-MDP-CF-FRAB EFW-TDP-TM MFW-SYS-FC-TRANS 8.6E-010 1.72 HPR-XHE-XM EFW-MDP-CF-FRAB EFW-TDP-FS-1 MFW-SYS-FC-TRANS 7.6E-010 1.52 HPR-XHE-XM EFW-CKV-CF-SGS MFW-SYS-FC-TRIP 7.6E-010 1.52 HPR-XHE-XM EFW-CKV-CF-DIS MFW-SYS-FC-TRIP 7.6E-010 1.52 HPR-XHE-XM EFW-CKV-CF-SUCT MFW-SYS-FC-TRIP 7.4E-010 1.49 HPR-XHE-XM EFW-PMP-CF-ALL MFW-SYS-FC-TRIP 6.7E-010 1.35 HPR-XHE-XM EFW-TNK-FC-CST1 MFW-SYS-FC-TRANS 2004/12/21 11:10:02 page 3 Attachment 2
6.4E-010 1.28 HPR-XHE-XM EFW-MDP-CF-FSAB EFW-TDP-TM MFW-SYS-FC-TRIP 6.3E-010 1.25 HPR-XHE-XM EFW-MDP-CF-FSAB EFW-TDP-FR MFW-SYS-FC-TRANS 5.7E-010 1.14 HPR-XHE-XM EFW-MDP-CF-FRAB EFW-XHE-XR-TDP1 MFW-SYS-FC-TRIP 5.3E-010 1.07 HPR-XHE-XM EFW-MDP-CF-FSAB EFW-TDP-FS-1 MFW-SYS-FC-TRIP Event Tree: LOOP CCDF: 3.3E-008 Sequence: 17 CCDF % Cut Set Cut Set Events
--------- ----------------------------------------------------
9.5E-009 29.09 EFW-MDP-CF-FRAB EFW-TDP-FR HPI-XHE-XM-FB 2.4E-009 7.44 EFW-MDP-CF-FRAB EFW-TDP-TM HPI-XHE-XM-FB 2.0E-009 6.20 EFW-MDP-CF-FRAB EFW-TDP-FS-1 HPI-XHE-XM-FB 2.0E-009 6.05 EFW-MDP-TM-1B EFW-TDP-FR EPS-DGN-FR-1A HPI-XHE-XM-FB 2.0E-009 6.05 EFW-MDP-TM-1A EFW-TDP-FR EPS-DGN-FR-1B HPI-XHE-XM-FB 1.6E-009 4.87 EFW-TNK-FC-CST1 HPI-XHE-XM-FB 1.5E-009 4.53 EFW-MDP-CF-FSAB EFW-TDP-FR HPI-XHE-XM-FB 4.5E-010 1.37 EFW-CKV-CF-SUCT HPI-XHE-XM-FB 4.5E-010 1.37 EFW-CKV-CF-DIS HPI-XHE-XM-FB 4.5E-010 1.37 EFW-CKV-CF-SGS HPI-XHE-XM-FB 4.4E-010 1.34 EFW-PMP-CF-ALL HPI-XHE-XM-FB 4.2E-010 1.29 EFW-MDP-TM-1B EFW-TDP-FS-1 EPS-DGN-FR-1A HPI-XHE-XM-FB 4.2E-010 1.29 EFW-MDP-TM-1A EFW-TDP-FS-1 EPS-DGN-FR-1B HPI-XHE-XM-FB 4.0E-010 1.21 EFW-TDP-FR EFW-XHE-XR-MDP1B EPS-DGN-FR-1A HPI-XHE-XM-FB 4.0E-010 1.21 EFW-TDP-FR EFW-XHE-XR-MDP1A EPS-DGN-FR-1B HPI-XHE-XM-FB 3.8E-010 1.16 EFW-MDP-CF-FSAB EFW-TDP-TM HPI-XHE-XM-FB 3.7E-010 1.14 EFW-MDP-TM-1B EFW-TDP-FR EPS-DGN-FS-1A HPI-XHE-XM-FB 3.7E-010 1.14 EFW-MDP-TM-1A EFW-TDP-FR EPS-DGN-FS-1B HPI-XHE-XM-FB 3.4E-010 1.03 EFW-MDP-CF-FRAB EFW-XHE-XR-TDP1 HPI-XHE-XM-FB
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2004/12/21 11:10:02 page 4 Attachment 2
BASIC EVENTS (Cut Sets Only)
Event Name Description Curr Prob
--------------------------------------------- ---------
DCP-BDC-LP-1B DIVISION 1B 125VDC BUS DP-1B ED FAILS 4.8E-006 EFW-CKV-CF-DIS COMMON CAUSE FAILURE OF EFW PUMPS DISCHARGE C 6.8E-007 EFW-CKV-CF-SGS COMMON CAUSE FAILURE OF SGS EFW CHECK VALVES 6.8E-007 EFW-CKV-CF-SUCT COMMON CAUSE FAILURE OF EFW PUMPS SUCTION CHE 6.8E-007 EFW-MDP-CF-FRAB CCF FAILURE OF EFW MDPS TO RUN 5.1E-004 EFW-MDP-CF-FSAB CCF EFW MDP FAIL TO START 7.9E-005 EFW-MDP-FR-1B EFW MDP 1B FAILS TO RUN 5.2E-004 EFW-MDP-FS-1B EFW MDP 1B FAILS TO START 1.2E-003 EFW-MDP-TM-1A EFW MDP 1A UNAVAILABLE DUE TO TEST AND MAINTE 5.0E-003 EFW-MDP-TM-1B EFW MDP 1B UNAVAILABLE DUE TO TEST AND MAINTE 5.0E-003 EFW-PMP-CF-ALL COMMON CAUSE FAILURE OF EFW PUMPS 6.6E-007 EFW-PMP-FR-1A FAILURE OF EFW PUMP 1A TO RUN (PUMP UNIT ONLY 4.0E-004 EFW-TDP-FR EFW TDP FAILS TO RUN 2.8E-002 EFW-TDP-FS-1 EFW TDP FAILS TO START 6.0E-003 EFW-TDP-TM EFW TDP UNAVAILABLE DUE TO TEST AND MAINTENAN 7.2E-003 EFW-TNK-FC-CST1 FAILURE OF CONDENSATE STORAGE TANK 2.4E-006 EFW-XHE-XL-MDPFRB OPERATOR FAILS TO RECOVER EFW MDP 1B (FAILS T 7.5E-001 EFW-XHE-XL-MDPFSB OPERATOR FAILS TO RECOVER EFW MDP 1B (FAILS T 2.1E-001 EFW-XHE-XR-MDP1A OP FAILS TO RESTORE EFW MDP 1A AFTER T&M 1.0E-003 EFW-XHE-XR-MDP1B OP FAILS TO RESTORE EFW MDP 1B 1.0E-003 EFW-XHE-XR-TDP1 OP FAILS TO RESTORE EFW TDP AFTER T&M 1.0E-003 EPS-DGN-FR-1A DIESEL GENERATOR A FAILS TO RUN 2.1E-002 EPS-DGN-FR-1B DIESEL GENERATOR B FAILS TO RUN 2.1E-002 EPS-DGN-FS-1A DIESEL GENERATOR A FAILS TO START 4.0E-003 EPS-DGN-FS-1B DIESEL GENERATOR B FAILS TO START 4.0E-003 HPI-XHE-XM-FB OPERATOR FAILS TO INITIATE FEED AND BLEED COO 2.0E-002 HPR-XHE-XM OPERTATOR FAILS TO INITIATE HPR 2.0E-003 MFW-SYS-FC-TRANS MFW IS UNAVAILABLE (TRANSIENT INTIATOR) 2.0E-001 MFW-SYS-FC-TRIP MFW IS UNAVAILABLE (TRANSIENT INTIATOR) 8.0E-001 2004/12/21 11:10:02 page 5 Attachment 2
CCDP FOR LOSS OF CST FUNCTION AS THE INITIATING EVENT INITIATING EVENT ASSESSMENT Code Ver : 7:22 Fam : SUMM_3 Model Ver : 2004/12/10 User : IDAHO NATIONAL LABORATORY (INL) Init Event: IE-TRANS Ev ID: TRANS-W-O-CST--SWAFW Total CCDP: 6.2E-003 Desc : Initiating Event Assessment BASIC EVENT CHANGES Event Name Description Base Prob Curr Prob Type
---------------------------- --------- --------- ------
EFW-TNK-FC-CST1 FAILURE OF CONDENSATE STORAG 2.4E-006 1.0E+000 TRUE EFW-XHE-XA-SWS OPERATOR FAILS TO ALIGN SW T 1.0E-003 1.0E+000 TRUE IE-LDCA LOSS OF DC POWER BUS 1A INIT 2.5E-003 +0.0E+000 IE-LLOCA LARGE LOSS OF COOLANT ACCIDE 5.0E-006 +0.0E+000 IE-LOCCW LOSS OF COMPONENT COOLING WA 2.0E-004 +0.0E+000 IE-LOOP LOSS OF OFFSITE POWER 3.3E-002 +0.0E+000 IE-LOSW LOSS OF SERVICE WATER INITIA 4.0E-004 +0.0E+000 IE-MLOCA MEDIUM LOSS OF COOLANT ACCID 4.0E-005 +0.0E+000 IE-RHR-CLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-RHR-HLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-RHR-SUC-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-SGTR STEAM GENERATOR TUBE RUPTURE 4.0E-003 +0.0E+000 IE-SI-CLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-SI-HLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-SLOCA SMALL LOSS OF COOLANT ACCIDE 4.0E-004 +0.0E+000 IE-TRANS TRANSIENT 7.0E-001 1.0E+000 MFW-XHE-XL-TRANS OPERATOR FAILS TO RECOVER MF 1.0E+000 1.0E-001 MFW-XHE-XL-TRIP OPERATOR FAILS TO RECOVER MF 1.0E+000 1.0E-001
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SEQUENCE PROBABILITIES Truncation : Cummulative : 100.0% Individual : 1.0%
Event Tree Name Sequence Name CCDP %Cont
------------------------ --------- -----
TRANS 17 5.9E-003 TRANS 16 2.3E-004 SEQUENCE LOGIC Event Tree Sequence Name Logic
------------- ---------------------------------------------------
TRANS 17 /RPS EFW MFW FAB TRANS 16 /RPS EFW MFW /FAB HPR 2004/12/21 10:06:37 page 1 Attachment 3
Fault Tree Name Description
------------------------------------------------------
EFW EMERGENCY FEEDWATER FAB FEED AND BLEED HPR HPR PRESSURE RECIRCULATION MFW MAIN FEEDWATER SYSTEM RPS REACTOR TRIP
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SEQUENCE CUT SETS Truncation: Cummulative: 100.0% Individual: 1.0%
Event Tree: TRANS CCDP: 5.9E-003 Sequence: 17 CCDP % Cut Set Cut Set Events
--------- ----------------------------------------------------
5.5E-003 92.92 MFW-SYS-FC-TRIP MFW-XHE-XL-TRIP HPI-XHE-XM-FB1 4.0E-004 6.73 MFW-SYS-FC-TRANS MFW-XHE-XL-TRANS HPI-XHE-XM-FB Event Tree: TRANS CCDP: 2.3E-004 Sequence: 16 CCDP % Cut Set Cut Set Events
--------- ----------------------------------------------------
1.6E-004 71.03 HPR-XHE-XM MFW-SYS-FC-TRIP MFW-XHE-XL-TRIP 4.0E-005 17.76 HPR-XHE-XM MFW-SYS-FC-TRANS MFW-XHE-XL-TRANS 4.3E-006 1.92 MFW-SYS-FC-TRIP MFW-XHE-XL-TRIP RHR-MDP-CF-FSAB
________________________________________________________________________________
BASIC EVENTS (Cut Sets Only)
Event Name Description Curr Prob
--------------------------------------------- ---------
HPI-XHE-XM-FB OPERATOR FAILS TO INITIATE FEED AND BLEED COO 2.0E-002 HPI-XHE-XM-FB1 OPERATOR FAILS TO INITIATE FEED AND BLEED COO 6.9E-002 HPR-XHE-XM OPERTATOR FAILS TO INITIATE HPR 2.0E-003 MFW-SYS-FC-TRANS MFW IS UNAVAILABLE (TRANSIENT INTIATOR) 2.0E-001 MFW-SYS-FC-TRIP MFW IS UNAVAILABLE (TRANSIENT INTIATOR) 8.0E-001 MFW-XHE-XL-TRANS OPERATOR FAILS TO RECOVER MFW (TRANSIENT INIT 1.0E-001 MFW-XHE-XL-TRIP OPERATOR FAILS TO RECOVER MFW (TRANSIENT INIT 1.0E-001 RHR-MDP-CF-FSAB COMMON CAUSE FAILURE OF RHR MDPS TO START 5.4E-005 2004/12/21 10:06:37 page 2 Attachment 3
TORNADO TO SWS TO EFW.WPD I N I T I A T I N G E V E N T A S S E S S M E N T Code Ver : 7:22 Fam : SUMM_3 Model Ver : 2004/12/10 User : IDAHO NATIONAL LABORATORY (INL) Init Event: IE-LOOP Ev ID: LOOP-SEVERE-TEST Total CCDP: 1.4E-006 Desc : Initiating Event Assessment BASIC EVENT CHANGES Event Name Description Base Prob Curr Prob Type
---------------------------- --------- --------- ------
EFW-TNK-FC-CST1 FAILURE OF CONDENSATE STORAG 2.4E-006 1.0E+000 TRUE EFW-XHE-XA-SWS OPERATOR FAILS TO ALIGN SW T 1.0E-003 1.0E+000 TRUE IE-LDCA LOSS OF DC POWER BUS 1A INIT 2.5E-003 +0.0E+000 IE-LLOCA LARGE LOSS OF COOLANT ACCIDE 5.0E-006 +0.0E+000 IE-LOCCW LOSS OF COMPONENT COOLING WA 2.0E-004 +0.0E+000 IE-LOOP LOSS OF OFFSITE POWER 3.3E-002 6.0E-005 IE-LOSW LOSS OF SERVICE WATER INITIA 4.0E-004 +0.0E+000 IE-MLOCA MEDIUM LOSS OF COOLANT ACCID 4.0E-005 +0.0E+000 IE-RHR-CLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-RHR-HLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-RHR-SUC-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-SGTR STEAM GENERATOR TUBE RUPTURE 4.0E-003 +0.0E+000 IE-SI-CLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-SI-HLDIS-V ISLOCA OCCURS WITH REACTOR A 1.0E+000 +0.0E+000 IE-SLOCA SMALL LOSS OF COOLANT ACCIDE 4.0E-004 +0.0E+000 IE-TRANS TRANSIENT 7.0E-001 +0.0E+000 OEP-XHE-XL-NR01H OPERATOR FAILS TO RECOVER OF 5.3E-001 4.6E-001 OEP-XHE-XL-NR02H OPERATOR FAILS TO RECOVER OF 3.7E-001 3.6E-001 OEP-XHE-XL-NR03H OPERATOR FAILS TO RECOVER OF 2.8E-001 3.0E-001 OEP-XHE-XL-NR04H OPERATOR FAILS TO RECOVER OF 2.2E-001 2.5E-001 OEP-XHE-XL-NR05H OPERATOR FAILS TO RECOVER OF 1.9E-001 2.2E-001 OEP-XHE-XL-NR06H OPERATOR FAILS TO RECOVER OF 1.6E-001 2.0E-001 OEP-XHE-XL-NR07H OPERATOR FAILS TO RECOVER OF 1.4E-001 1.8E-001 OEP-XHE-XL-NR08H OPERATOR FAILS TO RECOVER OF 1.2E-001 1.6E-001 OEP-XHE-XL-NR09H OPERATOR FAILS TO RECOVER OF 1.1E-001 1.4E-001 OEP-XHE-XL-NR10H OPERATOR FAILS TO RECOVER OF 1.0E-001 1.3E-001 OEP-XHE-XL-NR10H2 OPERATOR FAILS TO RECOVER OF 2.7E-001 3.7E-001 OEP-XHE-XL-NR10H4 OPERATOR FAILS TO RECOVER OF 4.5E-001 5.2E-001 OEP-XHE-XL-NR11H OPERATOR FAILS TO RECOVER OF 9.5E-002 1.2E-001 OEP-XHE-XL-NR12H OPERATOR FAILS TO RECOVER OF 8.9E-002 1.1E-001 OEP-XHE-XL-NR13H OPERATOR FAILS TO RECOVER OF 8.5E-002 1.0E-001 OEP-XHE-XL-NR14H OPERATOR FAILS TO RECOVER OF 8.2E-002 9.7E-002 OEP-XHE-XL-NR15H OPERATOR FAILS TO RECOVER OF 7.9E-002 9.0E-002 OEP-XHE-XL-NR16H OPERATOR FAILS TO RECOVER OF 7.6E-002 8.4E-002 OEP-XHE-XL-NR17H OPERATOR FAILS TO RECOVER OF 7.4E-002 7.9E-002 OEP-XHE-XL-NR18H OPERATOR FAILS TO RECOVER OF 7.2E-002 7.4E-002 OEP-XHE-XL-NR19H OPERATOR FAILS TO RECOVER OF 7.1E-002 7.0E-002 OEP-XHE-XL-NR20H OPERATOR FAILS TO RECOVER OF 6.9E-002 6.6E-002 OEP-XHE-XL-NR21H OPERATOR FAILS TO RECOVER OF 6.8E-002 6.2E-002 OEP-XHE-XL-NR22H OPERATOR FAILS TO RECOVER OF 6.7E-002 5.9E-002 2004/12/21 16:57:15 page 1 Attachment 5
OEP-XHE-XL-NR23H OPERATOR FAILS TO RECOVER OF 6.6E-002 5.6E-002 OEP-XHE-XL-NR24H OPERATOR FAILS TO RECOVER OF 6.5E-002 5.3E-002 OEP-XHE-XL-NR30M OPERATOR FAILS TO RECOVER OF 6.6E-001 5.6E-001 OEP-XHE-XL-NR90M OPERATOR FAILS TO RECOVER OF 4.4E-001 4.0E-001 ZV-LOOP-EW-LAMBDA EXTREME WEATHER RELATED LOSS 2.3E-003 +0.0E+000 ZV-LOOP-GR-LAMBDA GRID RELATED LOSS OF OFFSITE 1.7E-002 +0.0E+000 ZV-LOOP-PC-LAMBDA PLANT CENTERED LOSS OF OFFSI 2.4E-003 +0.0E+000 ZV-LOOP-SC-LAMBDA SWITCHYARD CENTERED LOSS OF 8.7E-003 +0.0E+000 ZV-LOOP-SW-LAMBDA SEVERE WEATHER RELATED LOSS 3.0E-003 1.0E+000 SEQUENCE PROBABILITIES Truncation : Cummulative : 100.0% Individual : 1.0%
Event Tree Name Sequence Name CCDP %Cont
------------------------ --------- -----
LOOP 17 1.2E-006 LOOP 14 1.1E-007 LOOP 18-45 4.3E-008 LOOP 16 3.8E-008 SEQUENCE LOGIC Event Tree Sequence Name Logic
------------- ---------------------------------------------------
LOOP 17 /RPS /EPS EFW-L FAB-L LOOP 14 /RPS /EPS EFW-L /FAB-L
/OPR-06H HPR LOOP 18-45 /RPS EPS EFW-B OPR-01H DGR-01H LOOP 16 /RPS /EPS EFW-L /FAB-L OPR-06H HPR-L Fault Tree Name Description
------------------------------------------------------
DGR-01H OPERATOR FAILS TO RECOVER EMERGENCY DIESEL IN 1 HOUR EFW-B SUMMER PWR B EMERGENCY FEEDWATER SYSTEM DURING SBO EFW-L SUMMER PWR B EMERGENCY FEEDWATER SYSTEM DURING LOOP EPS EMERGENCY POWER FAB-L FEED AND BLEED DURING LOOP HPR HIGH PRESSURE RECIRC HPR-L HIGH PRESSURE RECIRC OPR-01H OPERATOR FAILS TO RECOVER OFFSITE POWER IN 1 HOUR 2004/12/21 16:57:15 page 2 Attachment 5
OPR-06H OFFSITE POWER RECOVERY IN 6 HRS RPS REACTOR SHUTDOWN
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SEQUENCE CUT SETS Truncation: Cummulative: 100.0% Individual: 1.0%
Event Tree: LOOP CCDP: 1.2E-006 Sequence: 17 CCDP % Cut Set Cut Set Events
--------- ----------------------------------------------------
1.2E-006 98.00 HPI-XHE-XM-FB Event Tree: LOOP CCDP: 1.1E-007 Sequence: 14 CCDP % Cut Set Cut Set Events
--------- ----------------------------------------------------
9.7E-008 89.00 HPR-XHE-XM /OEP-XHE-XL-NR06H 2.6E-009 2.41 /OEP-XHE-XL-NR06H RHR-MDP-CF-FSAB Event Tree: LOOP CCDP: 4.3E-008 Sequence: 18-45 CCDP % Cut Set Cut Set Events
--------- ----------------------------------------------------
1.4E-008 32.02 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-CF-FRAB 1.1E-008 24.48 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-FR-1A EPS-DGN-FR-1B 4.5E-009 10.41 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-TM-1A EPS-DGN-FR-1B 4.5E-009 10.41 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-TM-1B EPS-DGN-FR-1A 2.0E-009 4.62 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-FS-1A EPS-DGN-FR-1B 2.0E-009 4.62 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-FS-1B EPS-DGN-FR-1A 2.0E-009 4.57 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-CF-FSAB 8.4E-010 1.97 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-TM-1B EPS-DGN-FS-1A 8.4E-010 1.97 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-DGN-TM-1A EPS-DGN-FS-1B 5.0E-010 1.16 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-XHE-XR-DGN1A EPS-DGN-FR-1B 5.0E-010 1.16 EPS-XHE-XL-NR01H OEP-XHE-XL-NR01H EPS-XHE-XR-DGN1B EPS-DGN-FR-1A 2004/12/21 16:57:15 page 3 Attachment 5
Event Tree: LOOP CCDP: 3.8E-008 Sequence: 16 CCDP % Cut Set Cut Set Events
--------- ----------------------------------------------------
2.3E-008 61.34 HPR-XHE-XM OEP-XHE-XL-NR06H 1.5E-009 3.90 OEP-XHE-XL-NR06H EPS-DGN-FR-1A RHR-MDP-TM-1B 1.5E-009 3.90 OEP-XHE-XL-NR06H EPS-DGN-FR-1B RHR-MDP-TM-1A 6.3E-010 1.66 OEP-XHE-XL-NR06H RHR-MDP-CF-FSAB 6.2E-010 1.62 OEP-XHE-XL-NR06H EPS-DGN-FR-1A CCW-HTX-TM-1B
________________________________________________________________________________
BASIC EVENTS (Cut Sets Only)
Event Name Description Curr Prob
--------------------------------------------- ---------
CCW-HTX-TM-1B CCW HTX 1B UNAVAILABLE DUE TO T&M 2.5E-003 EPS-DGN-CF-FRAB DIESEL GENERATOR COMMON CAUSE FAILS TO RUN 5.9E-004 EPS-DGN-CF-FSAB DIESEL GENERATOR COMMON CAUSE FAILS TO START 8.4E-005 EPS-DGN-FR-1A DIESEL GENERATOR A FAILS TO RUN 2.1E-002 EPS-DGN-FR-1B DIESEL GENERATOR B FAILS TO RUN 2.1E-002 EPS-DGN-FS-1A DIESEL GENERATOR A FAILS TO START 4.0E-003 EPS-DGN-FS-1B DIESEL GENERATOR B FAILS TO START 4.0E-003 EPS-DGN-TM-1A DIESEL GENERATOR 1A UNAVAILABLE DUE TO T&M 9.0E-003 EPS-DGN-TM-1B DIESEL GENERATOR 1B UNAVAILABLE DUE TO T&M 9.0E-003 EPS-XHE-XL-NR01H OPERATOR FAILS TO RECOVER EMERGENCY DIESEL IN 8.4E-001 EPS-XHE-XR-DGN1A OPERATOR FAILS TO RESTORE DIESEL GENERATOR A 1.0E-003 EPS-XHE-XR-DGN1B OPERATOR FAILS TO RESTORE DIESEL GENERATOR B 1.0E-003 HPI-XHE-XM-FB OPERATOR FAILS TO INITIATE FEED AND BLEED COO 2.0E-002 HPR-XHE-XM OPERTATOR FAILS TO INITIATE HPR 2.0E-003 OEP-XHE-XL-NR01H OPERATOR FAILS TO RECOVER OFFSITE POWER IN 1 4.6E-001 OEP-XHE-XL-NR06H OPERATOR FAILS TO RECOVER OFFSITE POWER IN 6 2.0E-001 RHR-MDP-CF-FSAB COMMON CAUSE FAILURE OF RHR MDPS TO START 5.4E-005 RHR-MDP-TM-1A RHR MDP 1A UNAVAILABLE DUE TO TEST AND MAINTE 6.0E-003 RHR-MDP-TM-1B RHR MDP 1B UNAVAILABLE DUE TO TEST AND MAINTE 6.0E-003 2004/12/21 16:57:15 page 4 Attachment 5