ML051190504
| ML051190504 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 03/25/2003 |
| From: | Eliezer Goldfeiz NRC/RES/DRAA/OERAB |
| To: | |
| References | |
| LER 2003-003-00 | |
| Download: ML051190504 (50) | |
Text
1 For the initiating event assessment, the parameter of interest is the measure of the conditional core damage probability (CCDP). This is the value obtained when calculating the probability of core damage for an initiating event with subsequent failure of one or more components following the initiating event.
1 Final Precursor Analysis Accident Sequence Precursor Program ---Office of Nuclear Regulatory Research Palisades Loss of shutdown cooling and emergency diesel generator start Event Date: March 25, 2003 LER: 255/03-003 CCDP1 = 3x10-6 March 15, 2005 Event Summary On March 25, 2003, plant maintenance workers were installing signposts in the parking lot to designate parking spaces. One of the signposts was driven into a conduit and damaged a cable which contained protective relay circuitry for all sources of offsite power. An Alert was declared due to the loss of offsite power combined with the loss of shutdown cooling.
The reported event, loss of offsite power, occurred during a refueling outage, when the reactor vessel head was open, and the cavity was flooded. The decay heat was being removed by DHR system. The event caused temporary disconnection of the AC power from the grid (switchyard power disconnect event) which stopped the running DHR train and auto-started emergency diesel generators. Shutdown cooling was restored after about 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
Cause. Workers were installing signposts in the parking lot. One of the signposts was driven into a conduit and damaged a cable which contained protective relay circuitry for all sources of offsite power.
Other conditions, failures, and unavailable equipment. No other significant conditions, failures, or unavailable equipment occurred during the event.
Recovery opportunities.
Multiple recovery opportunities exist and are credited in the event tree.
Analysis Results Conditional core damage probability (CCDP)
This event is modeled as a loss of AC power event leading to loss of RHR cooling during refueling conditions, with a 24-hour mission time. The conditional core damage probability of this event is 3E-06 (mean value). The acceptance threshold for the Accident Sequence Precursor Program is a CCDP of $ 1x10-6, therefore this condition is a precursor.
5%
Mean 95%
CCDP 2.6E-07 2.7E-06 8.2E-06 Dominant sequences The dominant sequence that contributes to event importance:
Sequence #5 of the event tree with a probability of 2.7E-06:
Emergency AC Power system is successful No or insufficient DHR flow Forced feed RCS Inventory makeup fails Gravity feed RCS inventory makeup fails Forced feed by firewater fails Core damage occurs.
Results tables The conditional probabilities of the sequences with the highest CCDPs are shown in Table 1.
The event tree sequence logic for the sequences with the highest CCDPs are provided in Tables 2a and 2b.
The conditional cut sets for the sequences with the highest CCDPs are provided in Table 3.
Definitions and probabilities for modified or dominant basic events are provided in Table 4.
Modeling Assumptions Assessment summary This event is modeled as a loss of AC power event leading to loss of RHR cooling during refueling conditions.
An event tree which contains top events for AC power recovery, restart of DHR, and the three recovery processes (see key modeling assumptions for the recovery processes) is used. The event tree is provided in Attachment C.
Modeling assumptions Key modeling assumptions. The key modeling assumptions are listed below and discussed in detail in the following sections. These assumptions are important contributors to the overall results.
1.
AC power to the plant can be readily restored by means of operator action per EOP Supplement 29.
If the EDGs were not available, closure of breaker 152-401 in the safeguards bus house would have restored AC power to the plant and the DHR system and its support systems. Then, the DHR and its support systems need to be restarted by operator actions. EOP Supplement 29, Section 1.0 would have directed the operator to close safeguards supply breaker 152-401 and then close the 2400V AC incoming breakers, successfully restoring power to the unit.
2.
Although not formally proceduralized, the following redundant and diverse methods to make up the water inventory in the containment sump, covering the core, exist if DHR recovery fails. These recoveries are credited with screening values to provide a reasonable upper-bound quantitative estimate of the risk incurred by this event:
Forced-feed containment sump inventory makeup by using the CSR system (F-FEED).
Gravity-feed inventory makeup form the SIRWT, with possible refilling of the SIRWT (G-FEED).
Forced-feed from fire water system, or from a fire truck (FW-FEED)
This assumption is needed for a reasonable estimation of event risk, since it provides the defense in depth and diversity to the already redundant DHR system. If these additional methods are not credited, the event risk estimate would solely rely on the reliability of the DHR system and its support systems. In that case, an elaborate repair model needs to be introduced to remove the conservatism.
Tthe water inventory in the accumulators can be dumped into the RCS to extend the time to uncovery. This buys a longer time window for repairs and implementation of operator actions. This is not credited in the current analysis.
3.
The time to boiling was estimated by the licensee as 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />; the time to core uncovery is also estimated, as 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> (Reference 2). This provides ample time for the plant personnel to restore original core cooling conditions, and additional cooling methods, if the original redundant DHR cooling fails by common cause.
Modifications to fault tree models The following modified or new fault tree models are used in the analysis:
AC Availability (EPS-R). EPS-R fault tree is made by using the EPS fault tree from the Palisades SPAR model for at-power events. Two recovery actions are AND-gated at the top of the FT with the EDG failures. These recovery actions are:
EP-XHE-AC-REC Operators restore AC power from the grid using EOP Supplement 29.
EP-DG-REC-SD Recovery of at least 1 EDG.
The fault tree is given by Figure C-2. The top cutsets of this fault tree are given in Table C-1.
DHR Restart (DHR-RESTART). The DHR-RESTART fault tree is made from the Palisades SPAR model for at-power events. The cutsets of this model are examined. The top four single-element cutsets corresponding to valves not opening are deemed not be applicable.
The FT sections corresponding to these valves are removed. More cutsets further down may also be removed, but this is not pursued since it does not affect the results.
The fault tree is given by Figure C-3. The top cutsets of this fault tree are given in Table C-2.
RCS makeup by forced feed (F-FEED). A fault tree is made for this recovery by using screening values for operator action and hardware failures. The fault tree is shown in Figure C-4 RCS makeup by gravity feed (F-FEED). A fault tree is made for this recovery by using screening values for operator action and hardware failures. The fault tree is shown in Figure C-5 RCS makeup by fire water (FW-FEED). A fault tree is made for this recovery by using screening values for operator action and hardware failures. The fault tree is shown in Figure C-6 Basic event probability changes The following new data is introduced:
Probability of failure to recover at least one DG (EP-DG-REC-SD). The value of this basic event failure probability is taken from the SPAR EDG recovery curve at 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> as 8.8E-02 (Reference 3).
Probability of failure to connect to offsite power (EP-XHE-AC-REC). This operator action discussed and its failure probability is calculated in Attachment A.
The next three basic events represent failure of operator actions to implement the corresponding recovery action for RCS inventory makeup, when DHR fails.
Probability of failure to implement forced feed (F-FEED-XHE). This operator action discussed and its failure probability is calculated in Attachment A.
Probability of failure to implement gravity feed (F-FEED-XHE). This operator action discussed and its failure probability is calculated in Attachment A.
Probability of failure to implement fire water feed (F-FEED-XHE). This operator action discussed and its failure probability is calculated in Attachment A.
These basic events are used under the event tree tops F-FEED, G-FEED, and FW-FEED which are for un-proceduralized operator actions, coupled with equipment failures, during
a time window of 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />. Since these actions are not proceduralized, a screening value of 0.1 is assigned to operator actions associated with implementing each of the methods.
The product of three such failures gives a credit of 1 E-03 for sequence 5.
Also, a screening failure probability of 0.01 is assigned to hardware failures of the equipment used for each method. This assumes a single train reliability, which is typically at the order of 0.01. The hardware failure basic events are:
Probability of hardware failure in forced feed (F-FEED-HARDWARE). This includes at least one pump train. Redundant trains may be available.
Probability of hardware failure in gravity feed (G-FEED-HARDWARE). This includes at least one valve train. Redundant trains may be available.
Probability of hardware failure in fire water feed (FW-FEED-HARDWARE). This includes at least one pump train, and/or fire truck.
Summary of new data Basic Event Failure Probability EP-DG-REC-SD 8.8E-02 EP-XHE-AC-REC 2.0E-05 F-FEED-XHE 1.0E-01 G-FEED-XHE 1.0E-01 FW-FEED-XHE 1.0E-01 F-FEED-HARDWARE 1.0E-02 FW-FEED-HARDWARE 1.0E-02 G-FEED-HARDWARE 1.0E-02 The following existing basic event failure probability is modified:
Probability of failure of operator action to start DHR (DHR-XHE-XM-SD). The probability of operator failing to restart DHR, given power recovery is calculated in Appendix A, as 1E-
- 05.
Sensitivity analyses Sensitivity analyses are made to examine the importance of modeling assumptions. These sensitivity analyses are documented in Attachment B, and are summarized below.
LOOP occurs during power operation.
A sensitivity analysis is made, considering that the post digging is independent of the plant operating state, and this event could have occurred during power operation, which is an order of magnitude more likely than a shutdown state during a calendar year. This sensitivity analysis shows that the event importance could have been as high as 4 E-05, even when credit is given for easy AC power recovery operator action in this particular case.
No credit for recovery.
The recovery actions F-FEED, G-FEED, and FW-FEED are not proceduralized, but highly credible to be implemented during the 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> period, they were credited in the model for a realistic estimate of this event importance. A sensitivity analysis is made, assuming that these recovery actions are not available. The event importance is calculated to be 9.9E-04.
This sensitivity shows that the event importance would be highly conservatively modeled if credible recovery actions are not included in the base case.
Dependence between operator actions.
If DHR restart fails, recovery actions provide a total of 0.001 factor of reduction for the dominant sequence through screening operator actions. If it is assumed that one of the recovery actions is totally dependent on the other two, then this credit is reduced by an order of magnitude. In that case, the event importance becomes 2.7E-05. As expected, the modeling of recovery actions is important to get a realistic estimate of event importance.
SPAR model updates Palisades SPAR model PALI_302 (zip file dated 05/07/2004 3:45pm) is used. No updates are performed on the model. The model is run with SAPHIRE/GEM version 6.8.
References 1.
LP/SD SPAR Model Template for PWRs, Rev. 1/3i, August 2002 2.
E-mail from J. Stang to S. Sancaktar containing utility responses to technical questions on the event. 8/16/2004.
3.
Emergency DG Recovery Curve used in SPAR Models, Revision 3.
4.
SERP Worksheet EA-03-180 dated 9/25/2003 (ML0327207361)
Table 1.
Conditional core damage probabilities associated with the highest probability sequences.
Event Sequence Importance Percent IE-LOOP-SD 5
2.7E-06 100%
IE-LOOP-SD 8
9.4E-11 0%
Sum =
2.7E-06 100%
Table 2a. Event tree sequence logic for top sequences.
Event Tree Sequence Importance Sequence Logic IE-LOOP-SD 5
2.7E-06 100%
/EPS-R DHR-RESTART F-FEED G-FEED FW-FEED IE-LOOP-SD 8
9.4E-11 0%
EPS-R G-FEED FW-FEED Table 2b. Definitions of top events listed in Table 2a.
Fault Tree Name Description DHR-RESTART No or Insufficient DHR Flow EPS-R Emergency AC Power System Failures F-FEED Forced Feed RCS Inventory Makeup FW -FEED Forced Feed by Firewater Fails G-FEED Gravity Feed RCS Inventory Makeup
LER 255/03-003 10 Table 3. Conditional cut sets for dominant sequences.
SEQUENCE CUT SETS Event Tree: IE-LOOP-SD Sequence: 5 CCDP: 2.7E-06 CCDP % Cut Set Cut Set Events 1.0E-006 37.8 RHR-AOV-OO-BYP G-FEED-XHE F-FEED-XHE FW-FEED-XHE 2.2E-007 8.2 G-FEED-XHE F-FEED-XHE FW-FEED-XHE LPI-MDP-CF-ALL 1.4E-007 5.2 G-FEED-XHE F-FEED-XHE FW-FEED-XHE CCW-HTX-PG-E54A 1.4E-007 5.2 G-FEED-XHE F-FEED-XHE FW-FEED-XHE CCW-HTX-PG-E54B 1.0E-007 3.8 DHR-MOV-CF-PSUC G-FEED-XHE F-FEED-XHE FW-FEED-XHE 1.0E-007 3.8 G-FEED-XHE F-FEED-XHE FW-FEED-XHE HPR-MOV-CF-SIRWT 1.0E-007 3.8 RHR-AOV-OO-BYP G-FEED-XHE F-FEED-XHE FW-FEED-HARDWARE 1.0E-007 3.8 RHR-AOV-OO-BYP G-FEED-XHE F-FEED-HARDWARE FW-FEED-XHE 1.0E-007 3.8 RHR-AOV-OO-BYP G-FEED-HARDWARE F-FEED-XHE FW-FEED-XHE 3.4E-008 1.3 G-FEED-XHE F-FEED-XHE FW-FEED-XHE SDC-HTX-CF-ALL Event Tree: IE-LOOP-SD Sequence: 8 CCDP: 9.4E-11 CCDP % Cut Set Cut Set Events 1.3E-011 14.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTR G-FEED-XHE FW-FEED-XHE 1.0E-011 10.9 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-12 EPS-DGN-TM-11 G-FEED-XHE FW-FEED-XHE 1.0E-011 10.9 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-TM-12 G-FEED-XHE FW-FEED-XHE 6.6E-012 7.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTS G-FEED-XHE FW-FEED-XHE 6.6E-012 7.0 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-12 EPS-DGN-TM-11 G-FEED-XHE FW-FEED-XHE 6.6E-012 7.0 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-TM-12 G-FEED-XHE FW-FEED-XHE 6.1E-012 6.5 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-FR-12 G-FEED-XHE FW-FEED-XHE 3.9E-012 4.2 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-FR-12 G-FEED-XHE FW-FEED-XHE 3.9E-012 4.2 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-12 EPS-DGN-FR-11 G-FEED-XHE FW-FEED-XHE 2.5E-012 2.7 EP-DG-REC-SD EP-XHE-AC-REC
LER 255/03-003 11 EPS-DGN-FS-11 EPS-DGN-FS-12 G-FEED-XHE FW-FEED-XHE 2.0E-012 2.2 EP-DG-REC-SD EP-XHE-AC-REC G-FEED-XHE FW-FEED-XHE SWS-MDP-CF-STRT 1.6E-012 1.7 ACP-BAC-LP-1D EP-DG-REC-SD EP-XHE-AC-REC G-FEED-XHE FW-FEED-XHE 1.6E-012 1.7 EP-DG-REC-SD EP-XHE-AC-REC G-FEED-XHE FW-FEED-XHE DCP-BDC-LP-21 1.3E-012 1.4 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTR G-FEED-XHE FW-FEED-HARDWARE 1.3E-012 1.4 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTR G-FEED-HARDWARE FW-FEED-XHE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-TM-12 G-FEED-HARDWARE FW-FEED-XHE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-12 EPS-DGN-TM-11 G-FEED-XHE FW-FEED-HARDWARE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-12 EPS-DGN-TM-11 G-FEED-HARDWARE FW-FEED-XHE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-TM-12 G-FEED-XHE FW-FEED-HARDWARE
LER 255/03-003 12 Table 4. Definitions and probabilities for modified or dominant basic events.
Event Name Description Prob ACP-BAC-LP-1D DIVISION 1D AC POWER 4160V BUS A12 FAILS 9.0E-005 CCW-HTX-PG-E54A FAILURE OF CCW HEAT EXCHANGER E-54A 1.4E-004 CCW-HTX-PG-E54B FAILURE OF CCW HEAT EXCHANGER E-54B 1.4E-004 DCP-BDC-LP-21 FAILURE OF DC POWER BUS 21D 9.0E-005 DHR-MOV-CF-PSUC CCF OF LPI/DHR PUMP SUCTION MOVS 1.0E-004 EP-DG-REC-SD EDG RECOVERY DURING SHUTDOWN 8.8E-002 New EP-XHE-AC-REC AC RECOVERY DURING SHUTDOWN 2.0E-005 New EPS-DGN-CF-FTR COMMON CAUSE FAILURE OF DGNS TO RUN 7.5E-004 EPS-DGN-CF-FTS COMMON CAUSE FAILURE OF DGNS TO START 3.8E-004 EPS-DGN-FR-11 DIESEL GENERATOR 11 FAILS TO RUN 1.9E-002 EPS-DGN-FR-12 DIESEL GENERATOR 12 FAILS TO RUN 1.9E-002 EPS-DGN-FS-11 DIESEL GENERATOR 11 FAILS TO START 1.2E-002 EPS-DGN-FS-12 DIESEL GENERATOR 12 FAILS TO START 1.2E-002 EPS-DGN-TM-11 DIESEL GENERATOR 11 UNAVAILABLE DUE TO T&M 3.1E-002 EPS-DGN-TM-12 DIESEL GENERATOR 12 UNAVAILABLE DUE TO T&M 3.1E-002 F-FEED-HARDWARE HARDWARE FAILURES OF FORCED FEED 1.0E-002 New F-FEED-XHE OPERATOR ACTION TO IMPLEMENT FORCED FEED FAIL 1.0E-001 New FW-FEED-HARDWARE HARDWARE FAILURES OF FORCED FEED BY FIRE WATE 1.0E-002 New FW-FEED-XHE OPERATOR ACTION TO IMPLEMENT FORCED FEED BY F 1.0E-001 New G-FEED-HARDWARE HARDWARE FAILURES OF GRAVITY FEED 1.0E-002 New G-FEED-XHE OPERATOR ACTION TO IMPLEMENT GRAVITY FEED FAILS1.0E-001 New HPR-MOV-CF-SIRWT RWST ISOLATION MOVS FAIL TO CLOSE 1.0E-004 LPI-MDP-CF-ALL COMMON CAUSE FAILURE OF LPI MDPS 2.2E-004 RHR-AOV-OO-BYP LPI ISOL DISCHARGE AOV FAILURES 1.0E-003 SDC-HTX-CF-ALL COMMON CAUSE FAILURE OF SDC HEAT EXCHANGERS 3.4E-005 SWS-MDP-CF-STRT CCF OF SWS MDPS TO START 1.2E-004 Note: Events marked as New were added to the model for this analysis, and are explained in the text.
LER 255/03-003 13 Attachment A Calculation of Human Error Probabilities (HEPs)
SPAR HRA worksheets for LP/SD and at Power are used in this section to quantify the HEPs.
A-1 Operator Actions at Shutdown The following new human error basic events are introduced in the model:
EP-XHE-AC-REC DHR-XHE-XM-SD F-FEED-XHE FW-FEED-XHE G-FEED-XHE In this attachment, the HEPs for these human errors are calculated.
Calculation of HEP for EP-XHE-AC-REC. If the EDGs were not available, closure of breaker 152-401 in the safeguards bus house would have restored AC power to the plant and the DHR system and its support systems. Then, the DHR and its support systems need to be restarted by operator actions. EOP Supplement 29, Section 1.0 would have directed the operator to close safeguards supply breaker 152-401 and then close the 2400V AC incoming breakers, successfully restoring power to the unit (EP-XHE-AC-REC). This action can be performed within minutes and up to 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> with multiple shifts is available to perform this task. The diagnosis failure is insignificant, since power loss and failure of AC power on emergency buses is immediately apparent in the control room, and locally. Performance shaping factors for high stress due to the event, and time available is greater than 50x are used to get a PSF factor of 0.02. The HEP is calculated to be 2E-05.
Calculation of HEP for DHR-XHE-XM-SD. This basic event represents the operator action to restart DHR, given that AC power is established, either from EDGs or from the grid. This is a well proceduralized and important operator action that is a focal point of the plant operation at this phase of the shutdown state. The diagnosis failure is insignificant since both the control room and the other plant personnel can identify lack of DHR cooling (leading to eventual boiling in the containment where plant crews are operating in this shutdown state). This action can be performed within minutes and up to 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> with multiple shifts is available to perform this task. Performance shaping factors for high stress due to the event, time available is greater than 50x, and experience/training high are used to get a PSF factor of 0.01. The HEP is calculated to be 1E-05.
Calculation of HEPs for F-FEED-XHE, G-FEED-XHE, FW-FEED-XHE. Screening values for these operator actions are used. A HEP of 0.1 is assigned to each operator action. These actions have available time windows of many hours, but are not proceduralized. The actions are simple and are aimed to adding water to the flooded containment.
In the base case, no dependence is postulated for these there actions. The maximum credit one can get from these actions in a single accident sequence is 0.001 (0.01 if power is not available).
Since these HEPs are action driven, but not diagnosis driven, apply to different systems, and can happen at different times in a long time window, no dependence is postulated. As a sensitivity analysis, the dependence is considered.
LER 255/03-003 14 A-2 Operator Actions at Power (for the sensitivity analysis)
Three AC power recovery actions are calculated in this section these are:
In the first sensitivity case, the power recovery HEPS for the basic events modeled in SPAR are too conservative for this situation, since the grid is not lost, and the power can be rapidly restored by a simple operator action, as discussed above in EP-XHE-AC-REC. The three power recovery basic events affected are:
ACP-XHE-NOREC-ST (base SPAR value 0.53; delta T = 0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />)
OEP-XHE-NOREC-SL (base SPAR value 0.324; delta T = 2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />)
ACP-XHE-NOREC-BD (base SPAR value 0.022; delta T = 6.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />)
These three failure probabilities are recalculated for the specific event being assessed:
Probability of operator fail to restore AC power - short term (ACP-XHE-NOREC-ST). This is a proceduralized event with nominal time available under extreme stress. Its failure is dominated by diagnosis (identify the fault and choose the applicable procedure). The PSF multiplier is 5. The HEP is 0.05.
Probability of operator fail to restore AC power - seal LOCA(ACP-XHE-NOREC-SL). This is a proceduralized event with expansive time available under extreme stress. For diagnosis the time is expansive (up to 2+ hours to restore AC); for action, the time is nominal (since most of the time window is already credited for the diagnosis phase). The PSF multiplier for diagnosis is 0.05 and for action is 5. The HEP is calculated to be 0.0005 + 0.005 = 0.0055.
Probability of operator fail to restore AC power - before battery depletion (ACP-XHE-NOREC-BD). This is a proceduralized event with nominal time available under extreme stress. Its failure is dominated by action (long time window up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />). The PSF multiplier is 5 for extreme stress, 0.1 for time available >5x. The HEP is 0.0005.
LER 255/03-003 15 Attachment B. Sensitivity Analyses B-1 LOOP occurs during power operation The digging activity that lead to the failure is independent of the plant operation mode; it could have as well occurred during power operation and lead to a reactor trip and LOOP. In fact, during a calendar year, the plant normally spends more time in power operation mode than in shutdown. The base conditional core damage probability of this plant given LOOP is 2.5E-04 and is dominated by SBO sequences. However, the power recovery in this event is highly likely since the power is available at the grid, and procedures exist for reestablishing power by simple operator action of breaker closure. In that case, the failure probabilities for power recovery in SBO sequences are improved. These failure probabilities are calculated in Appendix B as Probability of operator fail to restore AC power - short term (ACP-XHE-NOREC-ST). The HEP is 0.05.
Probability of operator fail to restore AC power - seal LOCA(ACP-XHE-NOREC-SL). The HEP is 0.0055.
Probability of operator fail to restore AC power - before battery depletion (ACP-XHE-NOREC-BD).
The HEP is 0.0005.
A sensitivity case is run with setting LOOP frequency to 1.0 and replacing the base AC recovery probabilities with the above values. The event importance, given LOOP, is calculated as 4.3 E-05.
The GEM run documenting the sensitivity case is given as Attachment D.
Note that this event importance is higher than that calculated in the SDP analysis (reference 4) since the SDP assumes that the LOOP initiating event frequency will increase randomly by 0.0311/yr, assuming one consequential digging in 32.1 years of plant operation.
B-2 No credit for recovery.
The recovery actions F-FEED, G-FEED, and FW-FEED are not proceduralized, but highly credible to be implemented during the 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> period, they were credited in the model for a realistic estimate of this event importance. A sensitivity analysis is made, assuming that these recovery actions are not available. For this purpose the three operator action probabilities are set to failure:
F-FEED-XHE FW-FEED-XHE G-FEED-XHE GEM code is run with these new values. The resulting cutsets show that the basic event RHR-AOV-OO-BYP : LPI ISOL DISCHARGE AOV FAILURE TO CLOSE
LER 255/03-003 16 dominates the results. This valve has been already closed since the DHR system was operating successfully moments before the event. To make the results more realistic, the probability of this basic event is set to success. A GEM run is made and the event importance is calculated to be 9.9E-04. The GEM output is given as Attachment E. The first dominant cutset is common cause failure of motor driven pumps.
This sensitivity shows that the event importance would be highly conservatively modeled if credible recovery actions are not included in the base case.
B-3 Dependence between operator actions.
The recovery actions provide a total of 0.001 factor of reduction for the dominant sequence through screening operator actions. If it is assumed that one of the recovery actions is totally dependent on the other two, then this credit is reduced by an order of magnitude. In that case, the event importance becomes 2.7E-05. As expected, the modeling of recovery actions is important to get a realistic estimate of event importance.
LER 255/03-003 17 Attachment C. Event Tree and Fault Tree Models Process The LP/SD SPAR Model template for PWRs (Reference 1) is examined and applicable logic is extracted to make an event tree for this case. This event tree is named LOOP Occurs During Refueling Operation. Applicable fault tree models for failure of EPS and DHR are taken and are modified to reflect the event-specific characteristics. Then, the event tree is quantified using the SAPPHIRE code, with the initiating event frequency set equal to 1.0. The resulting CCDP is reported.
Initiating Events The initiating event is defined as the loss of power during refueling operations (IE-LOOP-SD). The plant is in shutdown conditions for the last 245 hours0.00284 days <br />0.0681 hours <br />4.050926e-4 weeks <br />9.32225e-5 months <br />. The reactor vessel head is open, and the containment cavity is already flooded. The initiating event frequency is set equal to 1.0 Event Tree Model An event tree model is generated, referring to the LOOP event tree in Reference 1. The event tree model is given in Figure C-1. It contains 6 top events, and defines two core damage sequences (sequences 5 and 8). The open RCS configuration prevents taking credit for RCS cooling by the secondary cooling system, via SGs. In the nomenclature of Reference 1, this event corresponds to POS Group 3 and Time Window TW3. The fact that the containment sump is flooded helps increase the time to core uncovery and buys ample time for proceduralized and non-proceduralized methods to keep the core covered.
The diagnosis of the event is immediate (loss of power to running DHR train and its support systems; momentary loss of lights in the MCR, etc.) Thus, failure to diagnose the event is not further pursued in the modeling.
The success criteria is taken from SPAR models whenever available. Changes are discussed below.
Given a LOOP event while in refueling mode with the reactor vessel head is open, and the containment cavity is flooded, the event could be successfully mitigated if; S
Power is restored to emergency busses that support the safety related equipment; S
DHR and its support systems are manually started (heat being removed by CCW heat exchangers);
If DHR or one of its support systems fails, three methods to make up containment sump inventory may be credited (each of these three methods is non proceduralized but each is technically and
LER 255/03-003 18 time-window-wise feasible. Success of any one of these three methods avoids core uncovery during the mission time.
Forced-feed containment sump inventory makeup by using the CSR system.
Gravity-feed inventory makeup form the SIRWT, with possible refilling of the SIRWT.
Forced-feed from fire water system, or from a fire truck.
The failure of the above-defined success path leads to core damage sequence #5 in the event tree.
If power restoration fails, then either one of the following two methods of containment sump inventory makeup would constitute success (heat being removed by boiling):
S Gravity feeding from SIRWT S
Force feed from a fire truck If this success criteria fails, sequence #8 occurs.
Five event tree top events are modeled by fault trees. These fault trees are:
EPS-R Failure to establish onsite emergency AC power by EDGs, automatically; AND failure to restore AC power from the grid (operator action following EOP); AND failure to restore at least 1 EDG (recovery/repair action).
DHR-RESTART Failure of DHR to remove decay heat via sump water recirculation through CCW heat exchangers.
F-FEED Failure of forced feed RCS inventory makeup G-FEED Failure of gravity feed RCS inventory makeup FW-FEED Failure of forced feed by fire water The mission time is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Fault Tree Models:
The new or modified fault tree models are shown in Figure C-2 through C-6.
Human Error Probability Calculations Human error probability calculations are given in Attachment A.
Event Importance Calculations
LER 255/03-003 19 Event importance for one base case and three sensitivity cases are calculated. The gem output for base case is given as Attachment D. The sensitivity cases are discussed in Attachment B.
Uncertainty Analysis The uncertainty bounds for 5 and 95 % confidences are calculated by GEM code. The summary is displayed on Figure C-7.
LER 255/03-003 20 Figure C-1 IE-LOOP-SD Event Tree
LER 255/03-003 21 Figure C-2 EPS-R Fault Tree
LER 255/03-003 22 Figure C-3 RHR-R-SD Fault Tree
LER 255/03-003 23 Figure C-4 F-FEED Fault Tree
LER 255/03-003 24 Figure C-5 FW-FEED Fault Tree
LER 255/03-003 25 Figure C-6 G-FEED Fault Tree
LER 255/03-003 26 Figure C-7 Uncertainty Results Attachm ent D Gem
LER 255/03-003 27 Output for the Base Case 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 : 6:80 Fam : PALI_302 Model Ver : 1998/02/17 User : EG&G IDAHO, INC. (INEL) Init Event: IE-LOOP-SD Ev ID: IE-LOOP-SD2 Total CCDP: 2.7E-006 Desc : Initiating Event Assessment BASIC EVENT CHANGES Event Name Description Base Prob Curr Prob Type IE-DHR-SUC-V DECAY HEAT REMOVAL SUCTION I 1.0E-007 +0.0E+000 IE-HPI1-DIS-V HPI TRAIN 1 DISCHARGE ISLOCA 4.6E-004 +0.0E+000 IE-HPI2-DIS-V HPI TRAIN 2 DISCHARGE ISLOCA 4.6E-004 +0.0E+000 IE-LLOCA LARGE LOSS OF COOLANT ACCIDE 5.7E-010 +0.0E+000 IE-LOCCW LOSS OF COMPONENT COOLING WA 1.1E-007 +0.0E+000 IE-LODC21 LOSS OF DC POWER BUS INITIAT 2.4E-007 +0.0E+000 IE-LOOP LOSS OF OFFSITE POWER INITIA 5.2E-006 +0.0E+000 IE-LOOP-SD LOOP Occurs During Refueling 1.0E+000 1.0E+000 IE-LOSW LOSS OF SERVICE WATER INITIA 1.1E-007 +0.0E+000 IE-LPI-DIS-V LPI DISCHARGE ISLOCA IE (BAS 4.6E-004 +0.0E+000 IE-MLOCA MEDIUM LOSS OF COOLANT ACCID 4.6E-009 +0.0E+000 IE-SGTR STEAM GENERATOR TUBE RUPTURE 8.0E-007 +0.0E+000 IE-SLOCA SMALL LOSS OF COOLANT ACCIDE 5.7E-008 +0.0E+000 IE-TRANS TRANSIENTS INITIATING EVENT 1.4E-004 +0.0E+000 SEQUENCE PROBABILITIES Truncation : Cummulative : 100.0% Individual : 0.0%
Event Tree Name Sequence Name CCDP %Cont IE-LOOP-SD 5 2.7E-006 100.0 IE-LOOP-SD 8 9.4E-011 0.0 SEQUENCE LOGIC Event Tree Sequence Name Logic IE-LOOP-SD 5 /EPS-R DHR-RESTART F-FEED G-FEED FW-FEED IE-LOOP-SD 8 EPS-R G-FEED FW-FEED Fault Tree Name Description DHR-RESTART NO OR INSUFFICIENT DHR FLOW 2004/10/26 17:35:21 page 1
LER 255/03-003 28 EPS-R EMERGENCY POWER SYSTEM FAILURES F-FEED Forced Feed RCS Inventory Makeup FW-FEED Forced Feed by Firewater Fails G-FEED Gravity Feed RCS Inventory Makeup SEQUENCE CUT SETS Truncation: Cummulative: 100.0% Individual: 1.0%
Event Tree: IE-LOOP-SD CCDP: 2.7E-006 Sequence: 5 CCDP % Cut Set Cut Set Events 1.0E-006 37.8 RHR-AOV-OO-BYP G-FEED-XHE F-FEED-XHE FW-FEED-XHE 2.2E-007 8.2 G-FEED-XHE F-FEED-XHE FW-FEED-XHE LPI-MDP-CF-ALL 1.4E-007 5.2 G-FEED-XHE F-FEED-XHE FW-FEED-XHE CCW-HTX-PG-E54A 1.4E-007 5.2 G-FEED-XHE F-FEED-XHE FW-FEED-XHE CCW-HTX-PG-E54B 1.0E-007 3.8 DHR-MOV-CF-PSUC G-FEED-XHE F-FEED-XHE FW-FEED-XHE 1.0E-007 3.8 G-FEED-XHE F-FEED-XHE FW-FEED-XHE HPR-MOV-CF-SIRWT 1.0E-007 3.8 RHR-AOV-OO-BYP G-FEED-XHE F-FEED-XHE FW-FEED-HARDWARE 1.0E-007 3.8 RHR-AOV-OO-BYP G-FEED-XHE F-FEED-HARDWARE FW-FEED-XHE 1.0E-007 3.8 RHR-AOV-OO-BYP G-FEED-HARDWARE F-FEED-XHE FW-FEED-XHE 3.4E-008 1.3 G-FEED-XHE F-FEED-XHE FW-FEED-XHE SDC-HTX-CF-ALL Event Tree: IE-LOOP-SD CCDP: 9.4E-011 Sequence: 8 CCDP % Cut Set Cut Set Events 1.3E-011 14.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTR G-FEED-XHE FW-FEED-XHE 1.0E-011 10.9 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-12 EPS-DGN-TM-11 G-FEED-XHE FW-FEED-XHE 1.0E-011 10.9 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-TM-12 G-FEED-XHE FW-FEED-XHE 6.6E-012 7.1 EP-DG-REC-SD EP-XHE-AC-REC 2004/10/26 17:35:21 page 2
LER 255/03-003 29 EPS-DGN-CF-FTS G-FEED-XHE FW-FEED-XHE 6.6E-012 7.0 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-12 EPS-DGN-TM-11 G-FEED-XHE FW-FEED-XHE 6.6E-012 7.0 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-TM-12 G-FEED-XHE FW-FEED-XHE 6.1E-012 6.5 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-FR-12 G-FEED-XHE FW-FEED-XHE 3.9E-012 4.2 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-FR-12 G-FEED-XHE FW-FEED-XHE 3.9E-012 4.2 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-12 EPS-DGN-FR-11 G-FEED-XHE FW-FEED-XHE 2.5E-012 2.7 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-FS-12 G-FEED-XHE FW-FEED-XHE 2.0E-012 2.2 EP-DG-REC-SD EP-XHE-AC-REC G-FEED-XHE FW-FEED-XHE SWS-MDP-CF-STRT 1.6E-012 1.7 ACP-BAC-LP-1D EP-DG-REC-SD EP-XHE-AC-REC G-FEED-XHE FW-FEED-XHE 1.6E-012 1.7 EP-DG-REC-SD EP-XHE-AC-REC G-FEED-XHE FW-FEED-XHE DCP-BDC-LP-21 1.3E-012 1.4 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTR G-FEED-XHE FW-FEED-HARDWARE 1.3E-012 1.4 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTR G-FEED-HARDWARE FW-FEED-XHE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-TM-12 G-FEED-HARDWARE FW-FEED-XHE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-12 EPS-DGN-TM-11 G-FEED-XHE FW-FEED-HARDWARE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-12 EPS-DGN-TM-11 G-FEED-HARDWARE FW-FEED-XHE 1.0E-012 1.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-TM-12 G-FEED-XHE FW-FEED-HARDWARE 2004/10/26 17:35:21 page 3
LER 255/03-003 30 BASIC EVENTS (Cut Sets Only)
Event Name Description Curr Prob ACP-BAC-LP-1D DIVISION 1D AC POWER 4160V BUS A12 FAILS 9.0E-005 CCW-HTX-PG-E54A FAILURE OF CCW HEAT EXCHANGER E-54A 1.4E-004 CCW-HTX-PG-E54B FAILURE OF CCW HEAT EXCHANGER E-54B 1.4E-004 DCP-BDC-LP-21 FAILURE OF DC POWER BUS 21D 9.0E-005 DHR-MOV-CF-PSUC CCF OF LPI/DHR PUMP SUCTION MOVS 1.0E-004 EP-DG-REC-SD EDG RECOVERY DURING SHUTDOWN 8.8E-002 EP-XHE-AC-REC AC RECOVERY DURING SHUTDOWN 2.0E-005 EPS-DGN-CF-FTR COMMON CAUSE FAILURE OF DGNS TO RUN 7.5E-004 EPS-DGN-CF-FTS COMMON CAUSE FAILURE OF DGNS TO START 3.8E-004 EPS-DGN-FR-11 DIESEL GENERATOR 11 FAILS TO RUN 1.9E-002 EPS-DGN-FR-12 DIESEL GENERATOR 12 FAILS TO RUN 1.9E-002 EPS-DGN-FS-11 DIESEL GENERATOR 11 FAILS TO START 1.2E-002 EPS-DGN-FS-12 DIESEL GENERATOR 12 FAILS TO START 1.2E-002 EPS-DGN-TM-11 DIESEL GENERATOR 11 UNAVAILABLE DUE TO T&M 3.1E-002 EPS-DGN-TM-12 DIESEL GENERATOR 12 UNAVAILABLE DUE TO T&M 3.1E-002 F-FEED-HARDWARE HARDWARE FAILURES OF FORCED FEED 1.0E-002 F-FEED-XHE OPERATOR ACTION TO IMPLEMENT FORCED FEED FAIL 1.0E-001 FW-FEED-HARDWARE HARDWARE FAILURES OF FORCED FEED BY FIRE WATE 1.0E-002 FW-FEED-XHE OPERATOR ACTION TO IMPLEMENT FORCED FEED BY F 1.0E-001 G-FEED-HARDWARE HARDWARE FAILURES OF GRAVITY FEED 1.0E-002 G-FEED-XHE OPERATOR ACTION TO IMPLEMENT GRAVITY FEED FAI 1.0E-001 HPR-MOV-CF-SIRWT RWST ISOLATION MOVS FAIL TO CLOSE 1.0E-004 LPI-MDP-CF-ALL COMMON CAUSE FAILURE OF LPI MDPS 2.2E-004 RHR-AOV-OO-BYP LPI ISOL DISCHARGE AOV FAILURES 1.0E-003 SDC-HTX-CF-ALL COMMON CAUSE FAILURE OF SDC HEAT EXCHANGERS 3.4E-005 SWS-MDP-CF-STRT CCF OF SWS MDPS TO START 1.2E-004 2004/10/26 17:35:21 page 4
LER 255/03-003 31 Attachment E Gem Output for Sensitivity case 1: LOOP at Power 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 : 6:80 Fam : PALI_302 Model Ver : 1998/02/17 User : EG&G IDAHO, INC. (INEL) Init Event: IE-LOOP Ev ID: LOOP-SS Total CCDP: 4.3E-005 Desc : Initiating Event Assessment BASIC EVENT CHANGES Event Name Description Base Prob Curr Prob Type ACP-XHE-NOREC-BD OPERATOR FAILS TO RECOVER OF 2.2E-002 5.0E-004 ACP-XHE-NOREC-ST OPERATOR FAILS TO RECOVER OF 5.3E-001 5.0E-002 IE-DHR-SUC-V DECAY HEAT REMOVAL SUCTION I 1.0E-007 +0.0E+000 IE-HPI1-DIS-V HPI TRAIN 1 DISCHARGE ISLOCA 4.6E-004 +0.0E+000 IE-HPI2-DIS-V HPI TRAIN 2 DISCHARGE ISLOCA 4.6E-004 +0.0E+000 IE-LLOCA LARGE LOSS OF COOLANT ACCIDE 5.7E-010 +0.0E+000 IE-LOCCW LOSS OF COMPONENT COOLING WA 1.1E-007 +0.0E+000 IE-LODC21 LOSS OF DC POWER BUS INITIAT 2.4E-007 +0.0E+000 IE-LOOP LOSS OF OFFSITE POWER INITIA 5.2E-006 1.0E+000 IE-LOSW LOSS OF SERVICE WATER INITIA 1.1E-007 +0.0E+000 IE-LPI-DIS-V LPI DISCHARGE ISLOCA IE (BAS 4.6E-004 +0.0E+000 IE-MLOCA MEDIUM LOSS OF COOLANT ACCID 4.6E-009 +0.0E+000 IE-SGTR STEAM GENERATOR TUBE RUPTURE 8.0E-007 +0.0E+000 IE-SLOCA SMALL LOSS OF COOLANT ACCIDE 5.7E-008 +0.0E+000 IE-TRANS TRANSIENTS INITIATING EVENT 1.4E-004 +0.0E+000 OEP-XHE-NOREC-SL OPERATOR FAILS TO RECOVER OF 3.2E-001 5.5E-003 SEQUENCE PROBABILITIES Truncation : Cummulative : 100.0% Individual : 0.0%
Event Tree Name Sequence Name CCDP %Cont LOOP 23 1.8E-005 41.9 LOOP 24-26 8.7E-006 20.2 LOOP 13 5.5E-006 12.8 LOOP 12 3.7E-006 8.6 LOOP 24-02 1.4E-006 3.3 LOOP 08 1.3E-006 3.0 LOOP 24-24 1.3E-006 3.0 LOOP 25 1.2E-006 2.8 LOOP 24-13 8.1E-007 1.9 LOOP 11 5.3E-007 1.2 2004/10/26 17:48:20 page 1
LER 255/03-003 32 LOOP 24-10 2.4E-008 0.1 LOOP 24-08 2.2E-008 0.1 LOOP 22 1.6E-008 0.0 LOOP 24-21 1.4E-008 0.0 LOOP 24-19 1.3E-008 0.0 LOOP 20 9.2E-010 0.0 LOOP 09 8.6E-011 0.0 LOOP 17 1.1E-012 0.0 LOOP 21 1.5E-014 0.0 SEQUENCE LOGIC Event Tree Sequence Name Logic LOOP 23 /RT-L /EP AFW BLEED LOOP 24-26 /RT-L EP AFW ACP-ST LOOP 13 /RT-L /EP
/AFW PORV-L PORV-RES HPI-L LOOP 12 /RT-L /EP
/AFW PORV-L PORV-RES /HPI-L OP-2H CSR-L LOOP 24-02 /RT-L EP
/AFW /PORV-SBO
/SEALLOCA ACP-BD LOOP 08 /RT-L /EP
/AFW PORV-L PORV-RES /HPI-L
/OP-2H COOLDOWN
/AFW PORV-SBO PORV-RES ACP-ST LOOP 25 RT-L LOOP 24-13 /RT-L EP
/AFW PORV-SBO
/PORV-RES /SEALLOCA ACP-BD LOOP 11 /RT-L /EP
/AFW PORV-L PORV-RES /HPI-L 2004/10/26 17:48:20 page 2
LER 255/03-003 33 OP-2H /CSR-L HPR-L LOOP 24-11 /RT-L EP
/AFW /PORV-SBO SEALLOCA OP-SL LOOP 24-09 /RT-L EP
/AFW /PORV-SBO SEALLOCA /OP-SL
/HPI COOLDOWN CSR LOOP 24-22 /RT-L EP
/AFW PORV-SBO
/PORV-RES SEALLOCA OP-SL LOOP 24-20 /RT-L EP
/AFW PORV-SBO
/PORV-RES SEALLOCA
/OP-SL /HPI COOLDOWN CSR LOOP 16 /RT-L /EP AFW /BLEED
/HPI-L /OP-6H SGCOOL /CSR HPR LOOP 24-10 /RT-L EP
/AFW /PORV-SBO SEALLOCA /OP-SL HPI LOOP 24-08 /RT-L EP
/AFW /PORV-SBO SEALLOCA /OP-SL
/HPI COOLDOWN
/CSR HPR LOOP 22 /RT-L /EP AFW /BLEED HPI-L LOOP 24-21 /RT-L EP
/AFW PORV-SBO
/PORV-RES SEALLOCA
/OP-SL HPI LOOP 24-19 /RT-L EP
/AFW PORV-SBO 2004/10/26 17:48:20 page 3
/PORV-RES SEALLOCA
/OP-SL /HPI COOLDOWN /CSR HPR LOOP 20 /RT-L /EP AFW /BLEED
/HPI-L OP-6H SGCOOL-L /CSR-L HPR-L LOOP 09 /RT-L /EP
/AFW PORV-L PORV-RES /HPI-L
/OP-2H COOLDOWN CSR LOOP 17 /RT-L /EP AFW /BLEED
/HPI-L /OP-6H SGCOOL CSR LOOP 21 /RT-L /EP AFW /BLEED
/HPI-L OP-6H SGCOOL-L CSR-L Fault Tree Name Description ACP-BD OPERATOR FAILS TO RECOVER OFFSITE POWER BEFORE BATTER ACP-ST OFFSITE POWER RECOVERY IN SHORT TERM AFW NO OR INSUFFICIENT AFW FLOW BLEED FAILURE TO PROVIDE BLEED PORTION OF FEED & BLEED COOL COOLDOWN RCS COOLDOWN TO SDC PRESSURE USING TBVs, ETC.
CSR NO OR INSUFFICIENT CSR FLOW CSR-L NO OR INSUFFICIENT CSR FLOW DURING LOOP EP EMERGENCY POWER SYSTEM FAILURES HPI NO OR INSUFFICIENT HPI FLOW HPI-L NO OR INSUFFICIENT HPI FLOW DURING LOOP HPR NO OR INSUFFICIENT HPR FLOW HPR-L NO OR INSUFFICIENT HPR FLOW DURING LOOP OP-2H OPERATOR FAILS TO RECOVER OFFSITE POWER WITHIN 2 HRS OP-6H OPERATOR FAILS TO RECOVER OFFSITE POWER WITHIN 6 HRS OP-SL OPERATOR FAILS TO RECOVER OFFSITE POWER (SEAL LOCA)
PORV-L PORVs/SRVs OPEN DURING LOOP PORV-RES SRVs/PORVs AND BLOCK VALVES FAIL TO RESEAT PORV-SBO PORVs/SRVs OPEN DURING SBO RT-L REACTOR FAILS TO TRIP DURING LOOP SEALLOCA RCP SEALS FAIL DURING LOOP SGCOOL FAILURE OF SECONDARY COOLING SGCOOL-L FAILURE OF SECONDARY COOLING NO OFFSITE POWER 2004/10/26 17:48:20 page 4
LER 255/03-003 35 SEQUENCE CUT SETS Truncation: Cummulative: 100.0% Individual: 1.0%
Event Tree: LOOP CCDP: 1.8E-005 Sequence: 23 CCDP % Cut Set Cut Set Events 9.6E-007 5.4 EPS-DGN-TM-12 AFW-MDP-TM-8A AFW-TDP-FR-8B 7.5E-007 4.2 AFW-AOV-CF-SGS EPS-DGN-TM-11 7.5E-007 4.2 AFW-AOV-CF-SGS EPS-DGN-TM-12 6.1E-007 3.4 EPS-DGN-TM-12 AFW-MDP-FS-8A AFW-XHE-XL-MDPFS AFW-TDP-FR-8B 6.1E-007 3.4 EPS-DGN-TM-11 AFW-XHE-XL-MDPFS AFW-MDP-FS-8C AFW-TDP-FR-8B 5.8E-007 3.3 EPS-DGN-FR-12 AFW-MDP-TM-8A AFW-TDP-FR-8B 5.8E-007 3.3 EPS-DGN-FR-11 AFW-MDP-TM-8C AFW-TDP-FR-8B 5.0E-007 2.8 EPS-DGN-TM-12 AFW-MDP-FR-8A AFW-XHE-XL-MDPFR AFW-TDP-FR-8B 5.0E-007 2.8 EPS-DGN-TM-11 AFW-XHE-XL-MDPFR AFW-MDP-FR-8C AFW-TDP-FR-8B 4.8E-007 2.7 HPI-XHE-XM-FB AFW-AOV-CF-SGS 4.5E-007 2.5 AFW-AOV-CF-SGS EPS-DGN-FR-12 4.5E-007 2.5 AFW-AOV-CF-SGS EPS-DGN-FR-11 3.7E-007 2.1 EPS-DGN-FS-12 AFW-MDP-TM-8A AFW-TDP-FR-8B 3.7E-007 2.1 EPS-DGN-FS-11 AFW-MDP-TM-8C AFW-TDP-FR-8B 3.6E-007 2.1 EPS-DGN-FR-12 AFW-MDP-FS-8A AFW-XHE-XL-MDPFS AFW-TDP-FR-8B 3.6E-007 2.1 EPS-DGN-FR-11 AFW-XHE-XL-MDPFS AFW-MDP-FS-8C AFW-TDP-FR-8B 3.0E-007 1.7 EPS-DGN-FR-12 AFW-MDP-FR-8A AFW-XHE-XL-MDPFR AFW-TDP-FR-8B 3.0E-007 1.7 EPS-DGN-FR-11 AFW-XHE-XL-MDPFR AFW-MDP-FR-8C AFW-TDP-FR-8B 2.9E-007 1.6 AFW-AOV-CF-SGS EPS-DGN-FS-11 2.9E-007 1.6 AFW-AOV-CF-SGS EPS-DGN-FS-12 2.3E-007 1.3 EPS-DGN-FS-12 AFW-MDP-FS-8A AFW-XHE-XL-MDPFS AFW-TDP-FR-8B 2.3E-007 1.3 EPS-DGN-FS-11 AFW-XHE-XL-MDPFS AFW-MDP-FS-8C AFW-TDP-FR-8B 2.3E-007 1.3 EPS-DGN-TM-12 AFW-MDP-TM-8A AFW-TDP-FS-8B 1.9E-007 1.1 EPS-DGN-FS-12 AFW-MDP-FR-8A 2004/10/26 17:48:20 page 5
LER 255/03-003 36 AFW-XHE-XL-MDPFR AFW-TDP-FR-8B 1.9E-007 1.1 EPS-DGN-FS-11 AFW-XHE-XL-MDPFR AFW-MDP-FR-8C AFW-TDP-FR-8B 1.8E-007 1.0 AFW-CKV-CF-PMPS EPS-DGN-TM-11 1.8E-007 1.0 AFW-CKV-CF-PMPS EPS-DGN-TM-12 Event Tree: LOOP CCDP: 8.7E-006 Sequence: 24-26 CCDP % Cut Set Cut Set Events 1.1E-006 12.1 ACP-XHE-NOREC-ST EPS-DGN-CF-FTR AFW-TDP-FR-8B 8.1E-007 9.3 ACP-XHE-NOREC-ST EPS-DGN-FR-12 EPS-DGN-TM-11 AFW-TDP-FR-8B 8.1E-007 9.3 ACP-XHE-NOREC-ST EPS-DGN-FR-11 EPS-DGN-TM-12 AFW-TDP-FR-8B 5.3E-007 6.1 ACP-XHE-NOREC-ST EPS-DGN-CF-FTS AFW-TDP-FR-8B 5.2E-007 6.0 ACP-XHE-NOREC-ST EPS-DGN-FS-11 EPS-DGN-TM-12 AFW-TDP-FR-8B 5.2E-007 6.0 ACP-XHE-NOREC-ST EPS-DGN-FS-12 EPS-DGN-TM-11 AFW-TDP-FR-8B 4.9E-007 5.6 ACP-XHE-NOREC-ST EPS-DGN-FR-11 EPS-DGN-FR-12 AFW-TDP-FR-8B 3.2E-007 3.6 ACP-XHE-NOREC-ST EPS-DGN-FS-11 EPS-DGN-FR-12 AFW-TDP-FR-8B 3.2E-007 3.6 ACP-XHE-NOREC-ST EPS-DGN-FS-12 EPS-DGN-FR-11 AFW-TDP-FR-8B 2.9E-007 3.4 ACP-XHE-NOREC-ST EPS-DGN-CF-FTR AFW-TDP-TM-8B 2.6E-007 2.9 ACP-XHE-NOREC-ST EPS-DGN-CF-FTR AFW-TDP-FS-8B 2.0E-007 2.3 ACP-XHE-NOREC-ST EPS-DGN-FS-11 EPS-DGN-FS-12 AFW-TDP-FR-8B 2.0E-007 2.3 ACP-XHE-NOREC-ST EPS-DGN-FR-12 EPS-DGN-TM-11 AFW-TDP-FS-8B 2.0E-007 2.3 ACP-XHE-NOREC-ST EPS-DGN-FR-11 EPS-DGN-TM-12 AFW-TDP-FS-8B 1.6E-007 1.9 ACP-XHE-NOREC-ST SWS-MDP-CF-STRT AFW-TDP-FR-8B 1.5E-007 1.7 ACP-XHE-NOREC-ST EPS-DGN-CF-FTS AFW-TDP-TM-8B 1.4E-007 1.6 ACP-XHE-NOREC-ST EPS-DGN-FR-11 EPS-DGN-FR-12 AFW-TDP-TM-8B 1.3E-007 1.5 ACP-XHE-NOREC-ST EPS-DGN-CF-FTS AFW-TDP-FS-8B 1.3E-007 1.5 ACP-XHE-NOREC-ST EPS-DGN-FS-12 EPS-DGN-TM-11 AFW-TDP-FS-8B 1.3E-007 1.5 ACP-XHE-NOREC-ST EPS-DGN-FS-11 EPS-DGN-TM-12 AFW-TDP-FS-8B 1.3E-007 1.5 ACP-XHE-NOREC-ST DCP-BDC-LP-21 2004/10/26 17:48:20 page 6
LER 255/03-003 37 AFW-TDP-FR-8B 1.3E-007 1.5 ACP-BAC-LP-1D ACP-XHE-NOREC-ST AFW-TDP-FR-8B 1.2E-007 1.4 ACP-XHE-NOREC-ST EPS-DGN-FR-11 EPS-DGN-FR-12 AFW-TDP-FS-8B 8.7E-008 1.0 ACP-XHE-NOREC-ST EPS-DGN-FS-11 EPS-DGN-FR-12 AFW-TDP-TM-8B 8.7E-008 1.0 ACP-XHE-NOREC-ST EPS-DGN-FS-12 EPS-DGN-FR-11 AFW-TDP-TM-8B Event Tree: LOOP CCDP: 5.5E-006 Sequence: 13 CCDP % Cut Set Cut Set Events 7.5E-007 13.5 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 HPI-MDP-TM-P66B 7.5E-007 13.5 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-11 HPI-MDP-TM-P66A 5.6E-007 10.0 HPI-MDP-CF-ALL PPR-SRV-CO-L PPR-SRV-OO-SR1 4.5E-007 8.1 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-11 HPI-MDP-TM-P66A 4.5E-007 8.1 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-12 HPI-MDP-TM-P66B 2.9E-007 5.2 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-12 HPI-MDP-TM-P66B 2.9E-007 5.2 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-11 HPI-MDP-TM-P66A 2.4E-007 4.3 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-11 HPI-MDP-FS-P66A 2.4E-007 4.3 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 HPI-MDP-FS-P66B 1.4E-007 2.6 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-12 HPI-MDP-FS-P66B 1.4E-007 2.6 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-11 HPI-MDP-FS-P66A 9.2E-008 1.7 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-11 HPI-MDP-FS-P66A 9.2E-008 1.7 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-12 HPI-MDP-FS-P66B 7.9E-008 1.4 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 HPI-XHE-XR-P66B 7.9E-008 1.4 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-11 HPI-XHE-XR-P66A 7.3E-008 1.3 PPR-SRV-CO-L PPR-SRV-OO-SR1 HPI-MDP-FS-P66A HPI-MDP-TM-P66B 7.3E-008 1.3 PPR-SRV-CO-L PPR-SRV-OO-SR1 HPI-MDP-TM-P66A HPI-MDP-FS-P66B 5.7E-008 1.0 PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-11 HPI-MDP-FR-P66A 5.7E-008 1.0 PPR-SRV-CO-L PPR-SRV-OO-SR1 2004/10/26 17:48:20 page 7
LER 255/03-003 38 EPS-DGN-TM-12 HPI-MDP-FR-P66B Event Tree: LOOP CCDP: 3.7E-006 Sequence: 12 CCDP % Cut Set Cut Set Events 4.6E-007 12.5 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 FPS-DDP-FC-41 EPS-DGN-TM-12 4.6E-007 12.5 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 FPS-DDP-FC-9B 3.8E-007 10.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 SWS-XHE-XA-FIRESYS 2.8E-007 7.5 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 FPS-DDP-FC-41 EPS-DGN-FR-12 2.8E-007 7.5 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-12 FPS-DDP-FC-9B 2.3E-007 6.2 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-12 SWS-XHE-XA-FIRESYS 1.8E-007 4.9 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 FPS-DDP-FC-41 EPS-DGN-FS-12 1.8E-007 4.9 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-12 FPS-DDP-FC-9B 1.7E-007 4.7 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 FPS-MDP-TM-9A 1.5E-007 4.0 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-12 SWS-XHE-XA-FIRESYS 1.4E-007 3.8 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 FPS-DDP-TM-41 EPS-DGN-TM-12 1.4E-007 3.8 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 FPS-DDP-TM-9B 1.0E-007 2.8 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-12 FPS-MDP-TM-9A 8.5E-008 2.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-12 FPS-DDP-TM-9B 8.5E-008 2.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 FPS-DDP-TM-41 EPS-DGN-FR-12 2004/10/26 17:48:20 page 8
LER 255/03-003 39 6.6E-008 1.8 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-12 FPS-MDP-TM-9A 5.5E-008 1.5 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 FPS-DDP-TM-41 EPS-DGN-FS-12 5.5E-008 1.5 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-12 FPS-DDP-TM-9B Event Tree: LOOP CCDP: 1.4E-006 Sequence: 24-02 CCDP % Cut Set Cut Set Events 2.3E-007 17.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-CF-FTR 1.8E-007 13.2 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FR-12 EPS-DGN-TM-11 1.8E-007 13.2 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-TM-12 1.2E-007 8.6 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-CF-FTS 1.2E-007 8.5 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-TM-12 1.2E-007 8.5 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-TM-11 1.1E-007 7.9 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-FR-12 7.0E-008 5.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FR-12 7.0E-008 5.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-FR-11 4.5E-008 3.3 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FS-12 3.6E-008 2.6 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO SWS-MDP-CF-STRT 2.8E-008 2.1 ACP-BAC-LP-1D ACP-XHE-NOREC-BD
/RCS-MDP-LK-SEALS /PPR-SRV-CO-SBO 2.8E-008 2.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO DCP-BDC-LP-21 2004/10/26 17:48:20 page 9
LER 255/03-003 40 Event Tree: LOOP CCDP: 1.3E-006 Sequence: 08 CCDP % Cut Set Cut Set Events 2.3E-007 17.1 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CF-MNFLW 2.3E-007 17.1 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CF-SUMP 2.3E-007 17.1 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CF-SIRWT 1.1E-007 8.6 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-SMP-FC-SUMP 6.4E-008 4.8 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPA HPI-MDP-TM-P66B 6.4E-008 4.8 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-SIRWTB HPI-MDP-TM-P66A 6.4E-008 4.8 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-SIRWTA HPI-MDP-TM-P66B 6.4E-008 4.8 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB HPI-MDP-TM-P66A 2.3E-008 1.8 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-CKV-CF-SUMP 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPA HPR-MOV-OO-SIRWTB 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB HPR-MOV-OO-SIRWTA 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-SIRWTB HPI-MDP-FS-P66A 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-SIRWTA HPI-MDP-FS-P66B 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-SIRWTB HPR-MOV-OO-SIRWTA 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPA HPI-MDP-FS-P66B 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB HPI-MDP-FS-P66A 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB HPR-MOV-CC-SMPA 2004/10/26 17:48:20 page 10
LER 255/03-003 41 2.0E-008 1.5 /OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-MFLWA HPR-MOV-OO-MFLWB Event Tree: LOOP CCDP: 1.3E-006 Sequence: 24-24 CCDP % Cut Set Cut Set Events 2.2E-007 17.1 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-CF-FTR 1.7E-007 13.2 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FR-12 EPS-DGN-TM-11 1.7E-007 13.2 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-TM-12 1.1E-007 8.6 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-CF-FTS 1.1E-007 8.5 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-TM-12 1.1E-007 8.5 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-TM-11 1.0E-007 7.9 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-FR-12 6.6E-008 5.1 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FR-12 6.6E-008 5.1 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-FR-11 4.3E-008 3.3 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FS-12 3.4E-008 2.6 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO SWS-MDP-CF-STRT 2.7E-008 2.1 ACP-BAC-LP-1D ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO 2.7E-008 2.1 ACP-XHE-NOREC-ST PPR-SRV-OO-SR1 PPR-SRV-CO-SBO DCP-BDC-LP-21 Event Tree: LOOP CCDP: 1.2E-006 Sequence: 25 CCDP % Cut Set Cut Set Events 1.2E-006 100.0 RPS-VCF-FO-MECH 2004/10/26 17:48:20 page 11
LER 255/03-003 42 Event Tree: LOOP CCDP: 8.1E-007 Sequence: 24-13 CCDP % Cut Set Cut Set Events 1.4E-007 17.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-CF-FTR 1.1E-007 13.2 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FR-12 EPS-DGN-TM-11 1.1E-007 13.2 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-TM-12 6.9E-008 8.6 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-CF-FTS 6.8E-008 8.5 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-TM-12 6.8E-008 8.5 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-TM-11 6.4E-008 7.9 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-FR-12 4.1E-008 5.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FR-12 4.1E-008 5.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-FR-11 2.6E-008 3.3 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FS-12 2.1E-008 2.6 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO SWS-MDP-CF-STRT 1.7E-008 2.1 ACP-BAC-LP-1D ACP-XHE-NOREC-BD
/RCS-MDP-LK-SEALS PPR-SRV-CO-SBO 1.7E-008 2.1 ACP-XHE-NOREC-BD /RCS-MDP-LK-SEALS PPR-SRV-CO-SBO DCP-BDC-LP-21 Event Tree: LOOP CCDP: 5.3E-007 Sequence: 11 CCDP % Cut Set Cut Set Events 3.1E-008 5.9 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CF-SIRWT 3.1E-008 5.9 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CF-MNFLW 3.1E-008 5.9 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CF-SUMP 2004/10/26 17:48:20 page 12
LER 255/03-003 43 2.9E-008 5.4 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-MFLWB EPS-DGN-TM-11 2.9E-008 5.4 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-MFLWA EPS-DGN-TM-12 2.9E-008 5.4 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-11 HPR-MOV-OO-SIRWTA 2.9E-008 5.4 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB EPS-DGN-TM-12 2.9E-008 5.4 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-TM-12 HPR-MOV-OO-SIRWTB 2.9E-008 5.4 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPA EPS-DGN-TM-11 1.7E-008 3.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB EPS-DGN-FR-12 1.7E-008 3.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-11 HPR-MOV-OO-SIRWTA 1.7E-008 3.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FR-12 HPR-MOV-OO-SIRWTB 1.7E-008 3.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPA EPS-DGN-FR-11 1.7E-008 3.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-MFLWA EPS-DGN-FR-12 1.7E-008 3.3 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-MFLWB EPS-DGN-FR-11 1.5E-008 2.9 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-SMP-FC-SUMP 1.1E-008 2.1 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-MFLWA EPS-DGN-FS-12 1.1E-008 2.1 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-MFLWB EPS-DGN-FS-11 1.1E-008 2.1 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPA EPS-DGN-FS-11 1.1E-008 2.1 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB EPS-DGN-FS-12 1.1E-008 2.1 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-11 2004/10/26 17:48:20 page 13
LER 255/03-003 44 HPR-MOV-OO-SIRWTA 1.1E-008 2.1 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 EPS-DGN-FS-12 HPR-MOV-OO-SIRWTB 8.7E-009 1.7 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-SIRWTA HPI-MDP-TM-P66B 8.7E-009 1.7 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-OO-SIRWTB HPI-MDP-TM-P66A 8.7E-009 1.7 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPB HPI-MDP-TM-P66A 8.7E-009 1.7 OEP-XHE-NOREC-2H PPR-SRV-CO-L PPR-SRV-OO-SR1 HPR-MOV-CC-SMPA HPI-MDP-TM-P66B Event Tree: LOOP CCDP: 1.4E-007 Sequence: 24-11 CCDP % Cut Set Cut Set Events 2.3E-008 17.1 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-CF-FTR 1.8E-008 13.2 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FR-12 EPS-DGN-TM-11 1.8E-008 13.2 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-TM-12 1.2E-008 8.6 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-CF-FTS 1.2E-008 8.5 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-TM-12 1.2E-008 8.5 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-TM-11 1.1E-008 7.9 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FR-11 EPS-DGN-FR-12 6.9E-009 5.1 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FR-12 6.9E-009 5.1 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-12 EPS-DGN-FR-11 4.4E-009 3.3 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO EPS-DGN-FS-11 EPS-DGN-FS-12 3.6E-009 2.6 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO SWS-MDP-CF-STRT 2004/10/26 17:48:20 page 14
LER 255/03-003 45 2.8E-009 2.1 ACP-BAC-LP-1D OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS /PPR-SRV-CO-SBO 2.8E-009 2.1 OEP-XHE-NOREC-SL RCS-MDP-LK-SEALS
/PPR-SRV-CO-SBO DCP-BDC-LP-21 BASIC EVENTS (Cut Sets Only)
Event Name Description Curr Prob ACP-BAC-LP-1C DIVISION 1C AC POWER 4160V BUS A11 FAILS 9.0E-005 ACP-BAC-LP-1D DIVISION 1D AC POWER 4160V BUS A12 FAILS 9.0E-005 ACP-XHE-NOREC-BD OPERATOR FAILS TO RECOVER OFFSITE POWER BEFOR 5.0E-004 ACP-XHE-NOREC-ST OPERATOR FAILS TO RECOVER OFFSITE POWER IN SH 5.0E-002 AFW-AOV-CF-SGS CCF OF STEAM GENERATOR DISCHARGE AOVS 2.4E-005 AFW-CKV-CF-PMPS CCF OF AFW PUMP DISCHARGE CHECK VALVES 5.8E-006 AFW-CKV-CF-SGS CCF OF STEAM GENERATOR INLET CHECK VALVES 4.2E-006 AFW-MDP-CF-START COMMON CAUSE FAILURE OF AFW MDP TO START 9.2E-005 AFW-MDP-FR-8A AFW MDP 8A FAILS TO RUN 7.6E-004 AFW-MDP-FR-8C AFW MDP 8C FAILS TO RUN 7.6E-004 AFW-MDP-FS-8A AFW MDP 8A FAILS TO START 3.3E-003 AFW-MDP-FS-8C AFW MDP 8C FAILS TO START 3.3E-003 AFW-MDP-TM-8A AFW MDP 8A UNAVAILABLE DUE TO T&M 1.1E-003 AFW-MDP-TM-8C AFW MDP 8C UNAVAILABLE DUE TO T&M 1.1E-003 2004/10/26 17:48:20 page 26
LER 255/03-003 46 Event Name Description Curr Prob AFW-PMP-CF-ALL COMMON CAUSE FAILURE OF AFW PUMPS 1.4E-006 AFW-TDP-FR-8B AFW TDP 8B FAILS TO RUN 2.8E-002 AFW-TDP-FS-8B AFW MDP 8B FAILS TO START 6.8E-003 AFW-TDP-TM-8B AFW TDP 8B UNAVAILABLE DUE TO T&M 7.8E-003 AFW-TNK-FC-CST AFW CONDENSATE STORAGE TANK FAILURES 1.3E-006 AFW-TNK-FC-MKUP MAKUP TANK 939 UNAVAILABLE 1.3E-006 AFW-XHE-XL-MDPFR OPERATOR FAILS TO RECOVER AFW MDP (FAILS TO R 7.5E-001 AFW-XHE-XL-MDPFS OPERATOR FAILS TO RECOVER AFW MDP (FAILS TO S 2.1E-001 CAC-AOV-CC-VHX4S CAC VHX-4 SERVICE WATER INLET AOV 0869 FAILS 1.0E-003 CAC-CKV-CF-SWDIS CCF OF SWS DISCHARGE CHECK VALVES 4.2E-006 CAC-FAN-CF-RUN CCF OF CAC FANS TO RUN 3.1E-006 CAC-FAN-CF-START CCF OF CAC FANS TO START 7.2E-006 CAC-XHE-XA-CAC4 OPERATOR FAILS TO ALIGN CAC VHX-4 1.0E-003 CCW-HTX-PG-E54A FAILURE OF CCW HEAT EXCHANGER E-54A 1.4E-004 CCW-HTX-PG-E54B FAILURE OF CCW HEAT EXCHANGER E-54B 1.4E-004 CCW-MDP-TM-P52B CCW MDP P-52B UNAVAILABLE DUE TO T&M 1.1E-002 CSR-XHE-XM OPERATOR FAILS TO INITIATE THE CSR SYSTEM FOR 1.0E-003 CSS-MDP-CF-ALL COMMON CAUSE FAILURE OF CSS MDPS 1.3E-004 CSS-MDP-TM-54A CONTAINMENT SPRAY MDP 54A UNAVAILABLE DUE TO 6.2E-003 DCP-BDC-LP-21 FAILURE OF DC POWER BUS 21D 9.0E-005 EPS-DGN-CF-FTR COMMON CAUSE FAILURE OF DGNS TO RUN 7.5E-004 EPS-DGN-CF-FTS COMMON CAUSE FAILURE OF DGNS TO START 3.8E-004 EPS-DGN-FR-11 DIESEL GENERATOR 11 FAILS TO RUN 1.9E-002 EPS-DGN-FR-12 DIESEL GENERATOR 12 FAILS TO RUN 1.9E-002 EPS-DGN-FS-11 DIESEL GENERATOR 11 FAILS TO START 1.2E-002 EPS-DGN-FS-12 DIESEL GENERATOR 12 FAILS TO START 1.2E-002 EPS-DGN-TM-11 DIESEL GENERATOR 11 UNAVAILABLE DUE TO T&M 3.1E-002 EPS-DGN-TM-12 DIESEL GENERATOR 12 UNAVAILABLE DUE TO T&M 3.1E-002 FPS-DDP-FC-41 FIRE PROTECTION SYSTEM PUMP 41 FAILS TO FUNCT 4.8E-002 FPS-DDP-FC-9B FIRE PROTECTION SYSTEM PUMP 9B FAILS TO FUNCT 4.8E-002 FPS-DDP-TM-41 FPS PUMP 41 UNAVAILABLE DUE TO T&M 1.5E-002 FPS-DDP-TM-9B FPS PUMP 9B UNAVAILABLE DUE TO T&M 1.5E-002 FPS-MDP-FC-9A FIRE PROTECTION SYSTEM PUMP 9A FAILS TO FUNCT 3.7E-003 FPS-MDP-TM-9A FPS PUMP 9A UNAVAILABLE DUE TO T&M 1.8E-002 HPI-CKV-CF-MDPDIS COMMON CAUSE FAILURE OF HPI DISCHARGE CKVS 1.0E-005 HPI-CKV-CF-SUCT CCF OF HPI SUCTION CHECK VALVES 1.0E-005 HPI-MDP-CF-ALL COMMON CAUSE FAILURE OF HPI MDPS 2.2E-004 HPI-MDP-FR-P66A LPI MDP P-66A FAILS TO RUN 7.2E-004 HPI-MDP-FR-P66B HPI MDP P-66B FAILS TO RUN 7.2E-004 HPI-MDP-FS-P66A HPI MDP P-66A FAILS TO START 3.0E-003 HPI-MDP-FS-P66B HPI MDP P-66B FAILS TO START 3.0E-003 HPI-MDP-TM-P66A HPI MDP P-66A UNAVAILABLE DUE TO T&M 9.4E-003 HPI-MDP-TM-P66B HPI MDP P-66B UNAVAILABLE DUE TO T&M 9.4E-003 HPI-XHE-XM-FB OPERATOR FAILS TO INITIATE FEED AND BLEED COO 2.0E-002 HPI-XHE-XR-P66A OPERATOR FAILS TO RESTORE HPI MDP P-66A AFTER 1.0E-003 HPI-XHE-XR-P66B OPERATOR FAILS TO RESTORE HPI MDP P-66B AFTER 1.0E-003 HPR-CKV-CF-SUMP CCF OF SUMP ISOLATION CHECK VALVES 1.0E-005 HPR-MOV-CC-SMPA TRAIN A SUMP MOV FAILS 3.0E-003 HPR-MOV-CC-SMPB TRAIN B SUMP MOV FAILS 3.0E-003 HPR-MOV-CF-MNFLW CCF OF RWST MINFLOW MOVS 1.0E-004 2004/10/26 17:48:20 page 27
LER 255/03-003 47 Event Name Description Curr Prob HPR-MOV-CF-SIRWT CCF OF SIRWT ISOLATION MOVS TO CLOSE 1.0E-004 HPR-MOV-CF-SUMP CCF OF SUMP ISOLATION MOVS 1.0E-004 HPR-MOV-OO-MFLWA FAILURE OF MINFLOW MOV A 3.0E-003 HPR-MOV-OO-MFLWB FAILURE OF MINFLOW MOV B 3.0E-003 HPR-MOV-OO-SIRWTA SIRWT TRAIN A ISOLATION MOV 3057 FAILS TO CLO 3.0E-003 HPR-MOV-OO-SIRWTB SIRWT TRAIN B ISOLATION MOV 3031 FAILS TO CLO 3.0E-003 HPR-SMP-FC-SUMP CONTAINMENT RECIRCULATION SUMP FAILS 5.0E-005 OEP-XHE-NOREC-2H OPERATOR FAILS TO RECOVER OFFSITE POWER WITHI 1.2E-001 OEP-XHE-NOREC-6H OPERATOR FAILS TO RECOVER OFFSITE POWER WITHI 3.6E-002 OEP-XHE-NOREC-SL OPERATOR FAILS TO RECOVER OFFSITE POWER (SEAL 5.5E-003 PPR-SRV-CO-L PORVS/SRVS OPEN DURING LOOP 1.6E-001 PPR-SRV-CO-SBO PORVS/SRVS OPEN DURING SBO 3.7E-001 PPR-SRV-OO-SR1 FAILURE OF SRVS RECLOSE 1.6E-002 RCS-MDP-LK-SEALS RCP SEALS FAIL W/O COOLING AND INJECTION 8.9E-003 RPS-VCF-FO-MECH CONTROL ROD ASSEMBLIES FAIL TO INSERT 1.2E-006 SWS-CKV-CF-DISCH CCF OF CCW MDPS DISCHARGE CHECK VALVES 5.8E-006 SWS-MDP-CF-RUN COMMON CAUSE FAILURE OF SWS MDPS TO RUN 1.3E-005 SWS-MDP-CF-STRT CCF OF SWS MDPS TO START 1.2E-004 SWS-XHE-XA-FIRESYS OPERATOR FAILS TO ALIGN FIRE PROTECTION SYSTE 4.0E-002 2004/10/26 17:48:20 page 28
LER 255/03-003 48 Attachment F. Gem Output for sensitivity Case 2 - No Credit for Recovery 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 : 6:80 Fam : PALI_302 Model Ver : 1998/02/17 User : EG&G IDAHO, INC. (INEL) Init Event: IE-LOOP-SD Ev ID: IE-LOOP-SD-CASE 2 Total CCDP: 9.9E-004 Desc : Initiating Event Assessment BASIC EVENT CHANGES Event Name Description Base Prob Curr Prob Type F-FEED-XHE Operator Action to Implement 1.0E-001 1.0E+000 TRUE FW-FEED-XHE Operator Action to Implement 1.0E-001 1.0E+000 TRUE G-FEED-XHE Operator Action to Implement 1.0E-001 1.0E+000 TRUE IE-DHR-SUC-V DECAY HEAT REMOVAL SUCTION I 1.0E-007 +0.0E+000 IE-HPI1-DIS-V HPI TRAIN 1 DISCHARGE ISLOCA 4.6E-004 +0.0E+000 IE-HPI2-DIS-V HPI TRAIN 2 DISCHARGE ISLOCA 4.6E-004 +0.0E+000 IE-LLOCA LARGE LOSS OF COOLANT ACCIDE 5.7E-010 +0.0E+000 IE-LOCCW LOSS OF COMPONENT COOLING WA 1.1E-007 +0.0E+000 IE-LODC21 LOSS OF DC POWER BUS INITIAT 2.4E-007 +0.0E+000 IE-LOOP LOSS OF OFFSITE POWER INITIA 5.2E-006 +0.0E+000 IE-LOOP-SD LOOP Occurs During Refueling 1.0E+000 1.0E+000 IE-LOSW LOSS OF SERVICE WATER INITIA 1.1E-007 +0.0E+000 IE-LPI-DIS-V LPI DISCHARGE ISLOCA IE (BAS 4.6E-004 +0.0E+000 IE-MLOCA MEDIUM LOSS OF COOLANT ACCID 4.6E-009 +0.0E+000 IE-SGTR STEAM GENERATOR TUBE RUPTURE 8.0E-007 +0.0E+000 IE-SLOCA SMALL LOSS OF COOLANT ACCIDE 5.7E-008 +0.0E+000 IE-TRANS TRANSIENTS INITIATING EVENT 1.4E-004 +0.0E+000 RHR-AOV-OO-BYP LPI ISOL DISCHARGE AOV FAILU 1.0E-003 +0.0E+000 FALSE SEQUENCE PROBABILITIES Truncation : Cummulative : 100.0% Individual : 0.0%
Event Tree Name Sequence Name CCDP %Cont IE-LOOP-SD 5 9.9E-004 100.0 IE-LOOP-SD 8 7.7E-009 0.0 SEQUENCE LOGIC Event Tree Sequence Name Logic IE-LOOP-SD 5 /EPS-R DHR-RESTART F-FEED G-FEED FW-FEED IE-LOOP-SD 8 EPS-R G-FEED FW-FEED 2004/10/27 09:11:37 page 1
LER 255/03-003 49 Fault Tree Name Description DHR-RESTART NO OR INSUFFICIENT DHR FLOW EPS-R EMERGENCY POWER SYSTEM FAILURES F-FEED Forced Feed RCS Inventory Makeup FW-FEED Forced Feed by Firewater Fails G-FEED Gravity Feed RCS Inventory Makeup SEQUENCE CUT SETS Truncation: Cummulative: 100.0% Individual: 1.0%
Event Tree: IE-LOOP-SD CCDP: 9.9E-004 Sequence: 5 CCDP % Cut Set Cut Set Events 2.2E-004 22.0 LPI-MDP-CF-ALL 1.4E-004 13.9 CCW-HTX-PG-E54A 1.4E-004 13.9 CCW-HTX-PG-E54B 1.0E-004 10.2 HPR-MOV-CF-SIRWT 1.0E-004 10.2 DHR-MOV-CF-PSUC 3.4E-005 3.4 SDC-HTX-CF-ALL 1.3E-005 1.3 CCW-MDP-CF-RUN 1.0E-005 1.1 LPI-CKV-CF-MDPDIS 1.0E-005 1.0 DHR-XHE-XM-SD Event Tree: IE-LOOP-SD CCDP: 7.7E-009 Sequence: 8 CCDP % Cut Set Cut Set Events 1.3E-009 17.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTR 1.0E-009 13.2 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-12 EPS-DGN-TM-11 1.0E-009 13.2 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-TM-12 6.6E-010 8.6 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-CF-FTS 6.6E-010 8.5 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-TM-12 6.6E-010 8.5 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-12 EPS-DGN-TM-11 6.1E-010 7.9 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FR-11 EPS-DGN-FR-12 3.9E-010 5.1 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-FR-12 3.9E-010 5.1 EP-DG-REC-SD EP-XHE-AC-REC 2004/10/27 09:11:37 page 2
LER 255/03-003 50 EPS-DGN-FS-12 EPS-DGN-FR-11 2.5E-010 3.3 EP-DG-REC-SD EP-XHE-AC-REC EPS-DGN-FS-11 EPS-DGN-FS-12 2.0E-010 2.6 EP-DG-REC-SD EP-XHE-AC-REC SWS-MDP-CF-STRT 1.6E-010 2.1 ACP-BAC-LP-1D EP-DG-REC-SD EP-XHE-AC-REC 1.6E-010 2.1 EP-DG-REC-SD EP-XHE-AC-REC DCP-BDC-LP-21 BASIC EVENTS (Cut Sets Only)
Event Name Description Curr Prob ACP-BAC-LP-1D DIVISION 1D AC POWER 4160V BUS A12 FAILS 9.0E-005 CCW-HTX-PG-E54A FAILURE OF CCW HEAT EXCHANGER E-54A 1.4E-004 CCW-HTX-PG-E54B FAILURE OF CCW HEAT EXCHANGER E-54B 1.4E-004 CCW-MDP-CF-RUN COMMON CAUSE FAILURE OF CCW MDPS TO RUN 1.3E-005 DCP-BDC-LP-21 FAILURE OF DC POWER BUS 21D 9.0E-005 DHR-MOV-CF-PSUC CCF OF LPI/DHR PUMP SUCTION MOVS 1.0E-004 DHR-XHE-XM-SD OPERATOR FAILS TO RESTART DHR DURING REFUELIN 1.0E-005 EP-DG-REC-SD EDG RECOVERY DURING SHUTDOWN 8.8E-002 EP-XHE-AC-REC AC RECOVERY DURING SHUTDOWN 2.0E-005 EPS-DGN-CF-FTR COMMON CAUSE FAILURE OF DGNS TO RUN 7.5E-004 EPS-DGN-CF-FTS COMMON CAUSE FAILURE OF DGNS TO START 3.8E-004 EPS-DGN-FR-11 DIESEL GENERATOR 11 FAILS TO RUN 1.9E-002 EPS-DGN-FR-12 DIESEL GENERATOR 12 FAILS TO RUN 1.9E-002 EPS-DGN-FS-11 DIESEL GENERATOR 11 FAILS TO START 1.2E-002 EPS-DGN-FS-12 DIESEL GENERATOR 12 FAILS TO START 1.2E-002 EPS-DGN-TM-11 DIESEL GENERATOR 11 UNAVAILABLE DUE TO T&M 3.1E-002 EPS-DGN-TM-12 DIESEL GENERATOR 12 UNAVAILABLE DUE TO T&M 3.1E-002 HPR-MOV-CF-SIRWT RWST ISOLATION MOVS FAIL TO CLOSE 1.0E-004 LPI-CKV-CF-MDPDIS COMMON CAUSE FAILURE OF LPI DISCHARGE CKVS 1.0E-005 LPI-MDP-CF-ALL COMMON CAUSE FAILURE OF LPI MDPS 2.2E-004 SDC-HTX-CF-ALL COMMON CAUSE FAILURE OF SDC HEAT EXCHANGERS 3.4E-005 SWS-MDP-CF-STRT CCF OF SWS MDPS TO START 1.2E-004 2004/10/27 09:11:37 page 3