NSD-NRC-97-5304, Responds to RAI Re AP600 H Diffusion Flame Sensitivity & Importance Analyses

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Responds to RAI Re AP600 H Diffusion Flame Sensitivity & Importance Analyses
ML20216D239
Person / Time
Site: 05200003
Issue date: 08/29/1997
From: Mcintyre B
WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To: Quay T
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NSD-NRC-97-5304, NUDOCS 9709090259
Download: ML20216D239 (20)
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  • 1573 " 355 DCP/NRC1016 NSD NRC 97 5304 Docket No.: 52 003 August 29,1997 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 A1TIINTION: T. R. QUAY SUlul'CT:

AP600 llYDROGEN DIFFUSION FLAME SENSITIVITY AND IMPOR FANCl! ' ANALYSIS

Dear Mr. Quay:

During a telecon on July 17,1997, between Westinghouse and the NRC, to open issues on the AP600 Level 2 PRA and severe accident topics, the staff requested that Westinghouse perform additional Level 2 PRA sensitivity and importance analyses assuming that a hydrogen diffusion Hame attaches to the containment wall. Westinghouse provided the staff with the AP600 Ilydrogen DifTusion Flame Assessment report (Westinghouse letter DCP/NRC0843, dated May 1,1997) which provides details to why a diffusion name is not expected to attach to tle containment wall. The staff requested during the July _17 telecon 3 that Westinghouse provide additional Level 2 PRA sensitivity and importance analyses. Specincally, the NRC requested that Westinghouse perform the same sensitivity and importance analyses as were documented in PRA Chapter 50, section 50.6, but assuming the diffusion Game attaches to the containment wall with a probability of 1.0. It was agreed during the telecon that this additional sensitivity and importance analyses would be provided via a letter report. Enclosed is the Westinghouse response to the NRC request. Specincally, the requested sensitivity and importance analyses are provided. The enclosed report closes, from the Westinghouse perspective, the telecon open item which is recorded in OITS as #5717. The Westinghouse status column in the OITS will be changed to " Action N." The NRC should review the enclosure and inform Westinghouse of the status to be designated in the "NRC Status" column of the OITS. DY k ll 9709090259 97 PDR ADOCK 05 3 A; PDR u m... E~ i

T { + c DCI'/NitC1016 NSD NitC 97 5304 2 August 29,1997 l' lease contact Cynthia 1,. Ilaag on (412) 374 4277 if you have any questions concerning this transmittal. / .A., / p lirlan A. McIntyre, Manager Advanced Plant Safety and I.icensing jml linclosure cc: J. Sebrosky, NitC (linclosure) N. J.1.iparulo, Westinghouse (w/o Enclosure) ne.s t. 1

e-s' l I 4 yn< Enclosure to Westinghouse Letter DCP/NRC1016 August 29,1997 31624 wpf A

m e HYDROGEN DIFFUSION FLAME FAILURE SENSITIVITY CASE / IMPORTANCE AND SENSITIVITY ANALYSIS 1.0 Large Release Frequency Sensitivity and importance Analyses For flydrogen Diffusion Flame Failure Sensitivity Case The AP600 large release frequency for intemal initiating events at-power for the hydrogen diffusion flame failure case is calculated to be 2.6E-08 events per year. The discussions that follow include two terms, large release frequency and containment effectiveness (C )- en Large release frequency is defined to be the frequency of containment failure plus the frequency of the containment bypass sequences. That is, the release sequences that do not l result in the IC (intact containment) category. Containment effectiveness is defined to be the ratio of the frequency of core damage sequences resulting in the IC category to the core damage frequency. It is a convenient way of measuung the ability of the containment to mitigate the consequences of the assudied severe accident. The containment effectiveness is related to the conditional containment failure probability, which is the ratio of the large release frequency to the core ' damage frequency, or 1 - C,,. The sensitivity and importance analyses that pertain to the Level 2 at power PRA are presented in this paper. 2.0 Importance Analyses For Large Release Frequency importance analyses for the hydrogen diffusion flame failure case containment event tree (CET) nodes, initiating events, components (basic events), and operator actions are discussed in this section. 2.1 Ilydrogen DitYusion Flame Failure Sensitivity Case Containment Event Tree Node Importance Analysis There are 11 event nodes on the containment event tree, which is discussed in AP600 PRA (Reference 1) Chapter 35. He importance of each of the 11 containment event tree nodes is calculated by setting the failure probability of the node to 1.0. The results are summarized in Table 1. The importance of each containment event tree node is also a sensitivity, because it looks at the potential of assuming failure for the phenomenon represented at the event tree node. DP Node The DP node (reactor coolant system depressurization) in the containment event tree represents the post-core damage depressurization of the reactor coolant system. Setting the failure probability of this node to 1.0 for the high-pressure accidents (accident classes l A, I AP,3A, and 6) shows the importance of this action relative to the mitigation of large releases. I h2 sem wpf i..

O t The resulting large release frequency is 3.67E 08 events per year, and the containment t effectiveness is reduced to 78 percent. This is a decrease of approximately 7 percent in the containment effectiveness from the base case, Since successful recovery from a steam generator tube rupture event that has progressed to the assumption of core damage tequires depressurization of the reactor coolant system, the increase in the large release frequency shown in this sensitivity is expected. A sensitivity that investigates the effect of depressurization on the steam generator tube rupture event is presented in subsection 3.1. IS Node Setting the failure probability of the IS node (containment isolation) to 1.0 assumes that containment isolation is never successful. In this sensitivity, the large release frequency is 1.7E-07 events per year, the same as the core damage frequency. As expected in this case, all of the fission products that are produced by the severe accident could escape the { containment to the environment through the open containment penetrations. IR Node l If the failure probability at the IR node (cavity flooding) is set to 1.0, flooding of the reactor cavity is assumed to always fail for those accident classes where the cavity is not Gooded by the nature of the accident. Vessel failure is assumed to eventually result for a, l severe accident when the cavity is not flooded. The vessel failure is assumed to be a direct cause of containment failure in cases where the cavity flooding fails. The large release frequency resulting from this sensitivity is 9.87E 08 events per year, and the containment effectiveness is reduced to 41.7 percent from the base case value of 84.5 percent. This is a reduction in the containment effectiveness. Since the 3BE accident class is among the dominant large release frequency sequences, reducing the ability to mitigate this accident class by failure of cavity flooding has an effect on the large release frequency. RFL Node This sensitivity assumes that the ability to reflood the core in a severe accident (node RFL) always fails. Setting this node to 1.0 for the 3BE accident class has no appreciable effect on the large release frequency. The outcome at this node is not a dominant effect in the large release frequency because of the function of the hydrogen igniters. The igniters maintain the hydrogen concentrations in the containment at the lower flammability limit, and mitigate the effect of any additional hydrogen produced by the reflood. VF Node This sensitivity investigates the effect of the core relocation probability (node VF) for accident class 3C on the large release frequency. If the vessel failure initiating event is always assumed to result in a relocation of the core out of the vessel, then containment failure would always result for the 3C accident class. The results of this sensitivity show 2 h2.sens.wpf

e the resulting large release frequency would be 3.5E-08 events per year, and the containment effectiveness would be 79 percent. There is a small effect on the large release frequency, PC Node The PC node models the success or failure of the passive containment cooling system (PCS). If the air How in the containment annular spaces is blocked, preventing the passive containment cooling system from cooling the containment shell, the containment will eventually fail from overpressurization. Assuming the containment always fails makes the large release frequency the same as the core damage frequency,1.7E-07 events per year. l IG Node The IG node models the reliability of the hydrogen control (hydrogen igniters). If the hydrogen igniters are assumed to fail, the potential for a hydrogen combustion event that could fail the containment is increased. (Hydrogen detonation events are assumed to fail the containment.) The result shows the large release frequency becomes 4.96E-08 events per year, and the containment effectiveness is 71 percent. This shows that the operation of the hydrogen igniters is important to maintaining a low release frequency. An investigation of other (non zero) values of the reliability of the hydrogen control system is discussed later. DF Node I The sensitivity case presented in this report is defined as failure of DF node. DTE Node The DTE node models the failure of the containment from an early hydrogen detonation event. If the occurrence of an early hydrogen detonation event is assumed to fail the containment, the large release frequency is 2.65E-08 events per year and the containment effectiveness is 84 percent. This is essentially the same as the baseline case because the potential for early hydrogen detonation events is very low in the AP600 containment with the hydrogen igniters functioning. DFG Node The DFG node models the potential for containment failure due to a hydrogen deflagration event. This sensitivity assumes that all hydrogen deflagration events result in an intermediate containment failure, and the resulting large release frequency is 2.65E-08 events per year, with a containment effectiveness of 84 percent. 'Ihis is essentially the same as the base case because the potential for hydrogen deflagration events or the progression of a hydrogen deflagration event into a hydrogen detonation event is very low in the AP600 containment with the hydrogen igniters functioning. 3 h2*ntwpf

T. ~ --- - -~ t 7 DTI Node ~ The DTI node models the potential for containment failure due to an hydrogen deflagration to-detonation event. This sensitivity assumes that all hydrogen burns transition from deflagration-to-detonation and result in an intermediate containment failure. De resulting large release frequency is 2.65E-08 events per year, with a containment effectiveness of 84 percent. This is essentially the same as the base case, because the -{ potential for hydrogen deflagration events or the progression of a hydrogen deflagration I event into a hydrogen detonation event is very low in the AP600 containment with the hydrogen igniters functioning. 2,2 flydrogen Dinusion Flame Failure Sensitivity Case Initiating Event importances for Large Release Frequency The contribution of at-power initiating events to the large release frequency is shown in Table 2. Table 3 shows the containment effectiveness (C,n) and the containment failure probability (CCFP) for the dominant initiating events. He C,n for a loss-of-coolant accident is over 90 percent. His reflects the ability of the ~ containment to mitigate the effects of a serious accident. A loss-of-coolant accident is a rare event with serious potential consequences. In fact, the core damage frequency is l dominated by loss of-coolant accident sequences. In the u fikely event that a loss-of-l coolant accident results in core damage, the containment is designed to prevent a large i release. ~ For transients, the C,y is relatively low. The core damage frequency from transients is small. But, if a transient does result in core damage, it is most likely as a result of a common cause failure of the instrument and control systems. His is also a rare event. Conservatively, no recovery action is modeled in the PRA for such failures. These recovery actions, such as finding attemative ways to actuate the automatic depressurization system would certainly be undertaken by the operators. Also, if a transient does result in core damage, it sometimes results in a high-pressure event. These events are assumed to lead to a failure of the reactor coolant system pressure boundary, which is assumed to fail the containment. These are conservative assumptions in the PRA models for transients. 2.3 Hydrogen DiNusion Flame Failure Sensitivity Case Component importances for Large Release Frequency The component imponances for large release frequency are summarized in Tables 4 and 5. In general, large release frequency component importances follow the same pattem as for the core damage frequency. The risk-important failures include common cause failure of software, common cause failure of ADS stage 4 squib valves, common cause failure of IRWST valves, common cause failure of IRWST line (screens) plugging, and common cause failure of transmitters / sensors. Additional failures contributing to risk-decrease imponance are ATWS-related operator actions. 4 h2mm wpf st5f&

r 2.4 Ilydrogen Diffusion Flame Failure Sensitivity Case importance of Operator Actions 7 in Large Release Frequency For the Level 2 analysis, various operator actions are defined, in addition to the ones defined for the Level 1 analysis. The operator actions defined specifically for the Level 2 PRA are the following: ( LPM REC 01 + ADN REC 01 For containment event tree DP node: diagnose and actuate l the automatic depressurization system after core damage. I PDS6-MANADS For containment event tree DP node: diagnose and actuate the automatic depressurization system after core damage for a steam generator tube rupture event only. 1 CIC MAN 01 For containment event tree Cl node: manually actuate containment isolation if automatic actuation fails. CMN REC 01 Manually actuate core makeup tanks if automatic actuation fails. REN-MANO3 For containment event tree node IR: fail to open recirculation valves to Good the cavity after core damage. i PCN-MAN 01 Manually actuate passive containment cooling system if automatic actuation fails. VLN MAN 01 Manually actuate the hydrogen ignitors. Note that for the Level 2 analysis, automatic depressurization system, cavity reflooding, and hydrogen ignitor actuations are solely manual. Actuation of containment isolation, core makeup tanks, and passive containment cooling system is modeled with manual actuation if automatic actuation fails. In component importance Table 4 REN MANO3, the operator action to open the valves to flood the cavity after core damage is risk important. Failure of this operator action fails cavity Gooding, which is assumed to fail the vessel, which in tum fails the containment. The importance for the hydrogen igniter node (subsection 2.1) shows that this manually actuated system has importance in the large release frequency; thus the operator action to actuate it (VLN-MAN 01) has also risk increase importance. Thus, if the operators always fail to actuate the hydrogen igniters when they are needed, the large release frequency would increase to 4.96E-08 events per year. The importance for the reactor coolant system depressurization node shows that this manually actuated system also has some importance in the large release frequency; thus the operator action to diagnose and actuate the automatic depressurization system when needed also has some importance in the release frequency. Thus, if the operators fail to depressurize the reactor coolant system when needed after core damage, the large release frequency would increase to 3.67E-08 events per year. 5 h24cns wpf

0 / . 3.0 ~ Additional Sensitivity Analyses For Large Release Frequency Assuming llydrogen Diffusion Flame Failure De sensitivity studies performed for the large release frequency are discussed in this subsection. 3.1 No Credit Taken for DP Node (RCS depressurization) for Accident Class 6 For this sensitivity, the failure probability of node DP is set to 1.0 only for accident class 6, steam generator tube rupture. In this case, the large release frequency becomes 3.lE-08 events per year, with a containment effectiveness of 81.8 percent. This is a small increase in the base case large l release frequency. 3.2 Increase Failure Probabiity for Containment Isolation For tilis sensitivity, the failure probability of node IS (containment isolation) is set to 0.01 i l for all accident classes, except l A,3D, and 6. For accident classes I A,3D, and 6, the failure probability of node IS is set to 0.1. De containment isolation failure probability is 1.6E-03, in the base case, and the conditional failure probabilities for the various accident classes range from.about IE-03 to IE 02. In this case, the large release frequency becomes 2.79E-08 events per year, with a containment effectiveness of 83.5 percent. This large release frequency increase is very small. 3.3 increase Failure Probability for Hydrogen Ignitors The failure probability of node IG is set to 0.01 for all accident classes for this sensitivity. The base case failure probability for the hydrogen control system is 1.15E-03. The large release frequency becomes 2.64E-08 event. per year and the containment effectiveness is 84.4 percent for this case. The large release frequency increase from the base case is insignincant. Another sensitivity on the hydrogen igniter reliability is also done. For this case, the failure probability is set to 0.I, a factor of 10 higher. In this case, the containment effectiveness is 83.5 percent and the large release frequency becomes 2.8E-08 events per year. Rese sensitivities and the discussion'in subsection 2.1 indicate the importance of the operation of the hydrogen igniters to the low release frequency. They also show it is not - as important to have a highly reliable hydrogen control system. That is, the hydrogen control system reliability can be signincantly reduced (possibly by failures of redundant igniters or of redundant power supplies), and the risk (measured by the large release frequency) is not significantly degraded. 6 h2cawpr

.. j These sensitivities also show that an improvement in the reliability of the hydrogen control M system will not result in lesser risk (lower release frequency value).- 3.4 Increase Failure Probability for Passive Containment Cooling System ~ Re failure probability of node PC is set to 0.001 wherever applicable in the containment-event tree. De base case failure probability is 9.9E-05. This sensitivity increases the failure probability by approximately a factor of 10. In this case, the large release frequency becomes 2.64E-08 events per year, the i containment effectiveness is 84.4 percent. The large release frequency increase from the j-base case is insignificant. 3.5 -- Effect on the Focused PRA Sensitivity Study ne hydrogen diffusion flame sensitivity analysis is performed on the AP600 focused PRA sensitivity study model for internal events at-power by setting the diffusion flame failure probability to 1.0 in accident classes 1 AP and 3D/ID. The large release frequency changes from 5.5E-07 per year to 5.9E-07 per year, and the containment effectiveness j changes from 92.9 percent to 92.3 percent. I 4.0 References 1 1. AP600 Probabilistic Risk Assessment, Revision 10, June 30,1997. 7 - h2*nsspr

a. r l Table 1 ^ ^ CONTAINMENT EVENT TREE NODE IMPORTANCES FOR DIFFUSION FLAME FAILURE SENSITIVITY CASE CET Node Sensitivity Conditional Accident Class Where CET ) Result LRF Containment Node Set = 1.0 J (per > car) Failure Prob (CCFP) (%)/ Containment Effectiveness (%) Base LRF (with hydrogen 2.6E-08 14.5 / 84.5 N/A diffusion flame failure) l DP (RCS Depressuritation) 3.7E-08 21.7 / 78.3 I A, I AP, 3 A, and 6 l IS (Containment Isolation) 1.7E-07 100 / 0 All i IR (Cavity Flooding) 9.9E-08 58.3 / 41.7 3BE and 3D RFL (Core Reflooding) 2.6E 08 15.5 / 84.5 3BE VF (Vessel Failure) 3.5E-08 20.9 /79.1 3C PC (PCS Failure) i.7E-07 100 /0 All JG (Hydrogen Ignitor 5.0E-08 29.4 / 70.6 All Failure) DF (Diffusion Flame) Same as base N/A N/A case DTE (Early DDT) 2.7E-08 15.7 / 84.3 All but I AP and 3D DFG (Hydrogen 2.7E 08 15.7 / 84.3 All but I AP and 3D Deflagration) ~ DTI (Intermediate DDT) 2.7E-08 15.7 / 84.3 All but l AP and 3D 8 h2.unsspf

0 e ,[ Table 2 w

  • CONTRIBUTION OF INITIATING EVENTS TO LARGE RELEASE FREQUENCY FOR DIFFUSION FLAME FAILURE SENSITIVITY CASE IMPORTANC INITIATING NUMBER LRF E 9r EVENT OF CONTRIBUTION INITI4 TING EVENT DESCRil'IlON DLCREASE FREQUENCY CUTSETS I

4 SE 09 INTFRMEDI ATE LOCA 17 4 7 7EM 2963 2 4 3E 09 SAFETY INJECTION LINE BREAK 16 5 i OEM 1538 3 3 BE-09 LARGE LOCA 14 6 i OE& 1508 4 34Eo9 STEAM GENERATOR TUBE RUI'TURE 12 9 5 2E 01 500 5 3 3E 09 ATWS PRECURSOR WITH NO MFW 12.7 4 8E-Ol* 280 6

1. l E-09 TRANSIENT WITH MFW 4I I 4E410 237 l

l 7 10E 09 REACTOR VESSEL RUI'TURE 39 i DE 08 33 l 8

7. lE-10 ATWS PRECURSOR WITH MFW AVAILABLE 2.7 l 2E410' 4

9 5 6E 10 MEDIUM LOCA 2.2 16EN 1307 10 53E10 RCS LLAK 20 1.2E42 1423 11 5 IE 10 SM ALL LOCA 1.9 1.0Ea 1177 12 4 IE-10 CMT LINE BREAK l6 8 9E 05 1048 13 3 IE 10 LOSS OF OFFSITE POWER I.2 l.2E41 244 le 29E10 LOSS OF CONDENSER I.I 1.l E-01 138 15 2.7E 10 LOSS OF MAIN FEEDWATER I.0 3 4E 01 101 16 2.6E 10 CORE POWER EACUR$10N IO 4 5E-03 Sol 17 1.7E 10 LOSS OF MFW TO ONE SO 06 I 9E 01 64 18 I 6E-10 PA5SIVE RHR TUBE RUITURE 06 2.5E 04 362 19 l.4E-10 ATWS PRECURSOR WITH SI SIGNAL 0.5 2.lE 02* 85 20 1 lE 10 LOSS OF CCS/SWS 04 14E-01 116 21 1.0E 10 M AIN STEAM LINE STUCK OPEN SV O4 1-2E 03 lot 22 5 3E ll STEAM LINE UPSTREAM OF MSiv 02 3.7Em 60 23 5 0E il INTERFACING SYSTEMS LOCA 02 5.0E Il i 24 44Eil LOSS OF COMPRESSED AIR 02 3.5 E-02 84 23 12E-Il LOSS OF RSC FLOW 0.1 18E-02 8 26 92E12 STEAM LINE BREAK DOWNSTREAM OF M51V 00 6 0Ea 13 2.6E 08 TOTALS 10110

2. 4'"

13896 h2111 1 The ATWS precursor frequencies (denoted with an *) are already accounted for in other categories. 9 h2-sens.wpf ^

n e y Table 3 INITIATING EVENT VS CONTAINMENT EFFECTIVENESS (C,n) FOR DIFFUSION FLAME FAILURE SENSITIVITY CASE ) initiating Esent Descripuon CCFP(%) C (%) Large LOCA 7 62 92 4 Steam Generator Tube Rupture 55 5 44 5 ATWS Precursor with no Mfv 37 2 62 8 Intermediate LOCA 14 4 85 6 Transents with MFW 93 6 64 Reactor Venc! Rupture 10.3 89 7 Safety injection une Break 11.3 88 7 ATWS Precursor with MIM AsaiNe 100 0 00 RCS Leak 23 3 76 7 Less of Offute Power 30 R 69.2 Loss of Condenser 27.6 72.4 Loss of MFW 90 0 10 0 f Medium LOCA 90 91.0 Loss of MFW to One Steam Generator 94 9 5.1 CMT Une Break i 1.7 88 3 Core Power Excuruon 14 0 86.0 Main Steam Une Stud Open SV 21.6 78 4 Steam Une Upstream of MSIV 43.2 56 8 Steam Une Downstream of MSiv 97 0 30 Lon of Compressed Air 25 4 74 6 PRHR Rube Rupture 28 4 71.7 ATWS Precursor with St Signal 37.3 62 7 Loss of CCS/SWS 89 0 Ii 0 Loss of RCS Flow 95 2 48 Interfacing Systems LOCA 100 0 00 Small LOCA 12.6 87.5 CCFP = Conditional Containnent Failure Probabihty 10 h2-sens wpf

  • . C7 q

Table 4 UASIC EVENT IMPORTANCES FOR DlITUSION FLAME FAILURE SENSITIVITY CASE SORTED BY RISK INCREASE l 2.620E-08 LRF = IMPORTANCE 8ASIC EV.

  1. OF INCREASE BASIC EVENT

% INCREASE PROBABILITY CUTSETS IN TOTAL DESCRIPTION 1 1.9E-03 (CX-SFTW COMMON CAUSE FAILURE OF PMS AND pts SOFTWARE 7.2E+06 1.2E-06 191 2 2.7E-04 CCX-PMXMOO1-SW COpO40N CAUSE F AILURE OF PMS ESF OUTPUT LOGIC SOFTWARE 1.OE+06 1.1E-05 212 3 2.7E-04 CCX-EP-SAM COMMON CAUSE FAILURE OF OUTPUT DRIVERS 1.OE+06 8.6E-06 185 4 1.9E-04 ADX-EV-SA COnO40N CAUSE FAILURE OF 4TH STAGE ADS SQUIB VALVES TO OPERATE 7.2E+05 3.OE-05 3174 5 1.9E-04 IWX-FL-GP cop 940N CAUSE FAILURE OF STRAINERS IN IRWST TANK 7.1E+05 1.2E-05 1264 6 1.4E-05 IWX-EV4-SA CO*940N CAUSE FAILURE OF 4 SQUIS VALVES IN RECIRC LINES 5.5E+04 2.6E-05 704 7 8.7E-06 IWX-CV-AO COMMON CAUSE FAILURE OF 4 IRWST INJECTION CHECK VALVES 3.3E+04 3.OE-05 1782 8 8.6E-06 IWX-EV-SA COpp40N CAUSE FAILURE OF 4 IRWS1 IN)ECTION SQUIB VALVES 3.3E+04 2.6E-05 1554 9 8.4E-06 CCX-XMT't COMMON CAUSE FAILURE OF SENSORS IN HIGH PRESSURE ENVIROMENT 3.2E+04. 4.8E-04 146 10 8.3E-06 CCx-XMYR195 COD 940N CAUSE FAILURE OF PZR LEVEL SENSORS 3.2E+04 4.8E-04 134 11 7.8E-06 ALL-INO-FAIL FAILURE OF PMS, PLS ANO DAS INDICATION FOR OPERATOR ACTIONS 3.0E+04 1.0E-06 80 12 5.3E-06 REX-FL-GP COPO40N CAUSE FAILURE OF RECIRC LINES DUE TO SUMP SCREEN PLUGGING 2.0E+04 1.2E-05 277 13 5.3E-06 CMx-VS-FA COD 940N CAUSE FAILURE OF CMT/ SUMP LEVEL HEATED RTD SENSORS 2.0E+04 3.8E-05 271 14 5.1E-06 CCX-AV-LA CODNON CAUSE FAILURE OF 4 AOVS TO GPEN 1.9E+0d 6.1E-05 118 15 4.7E % CCX-INPUT-LOGIC COpMON CAUSE FAILURE OF PMS ESF INPUT LOGIC GROUPS (HARDWARE) 1.8E+04 1.0E-04 402 16 4.5E-06 CMX-CV-GO COMMON CAUSE FAILURE OF 4 CMT CHECK VALVES TO OPEN 1.7E+04 5.1E-05 246 17 4.3E-06 CCX-IN-LOGIC-SW cop 940N CAUSE FAILURE OF PMS ESF INPUT LOGIC SOFTWARE 1.6E+04 1.1E-05 128 18 4.3E-06 (CX-PMXMOD2-SW CODNON CAUSE FAILURE OF PMS ESF ACTUATION LOGIC SOFTWARE 1.6E+04 1.1E-05 128 19 4.1E-06 RPX-C8-GO COh040N CAUSE FAILURE OF RCP BREAKERS FAIL TO OPEN 1.6E+04 4.2E-04 181 20 3.4E-06 CCX-PMXMOD4-SW COMMON CAUSE FAILURE OF PMS ESF MANUAL INPUT MULTIPLEXER SOrTWA. 1.3E+04 1.1E-05 89 21 3.3E-06 ED3MOOO7 EDS3 EA 1 DISTR. PANEL FAILURE OR T8M (DAS/PLS CABINET SUPPLY) 1.3E+04 3.0E -04 261 22 3.2E-06 CMX-TK-AF COm940N CAUSE FAILURE OF CMT TANKS 1.2E+04 1.2E-07 14 23 2.8E-06 IWA-PLUG IWRST DISCHARGE LINE "A" STRAINER PLUGGED 1.1E+04 2.4E-04 348 24 1.8E-06 RCX-RS-FA COpNON (AUSE FAILURE OF REACTOR TRIP BREAKERS 6.9E+03 8.1E-06 110 25 1.6E-06 CCX-BY-PN COfNON CAUSE FAILURE OF CLASS 1E BATTERIES 6.0E +03 4.7E-05 292 26 1.OE-06 IWX-EV1-SA COMMON CAUSE FAILURE OF 2 IRWST INJEC. SQUIBS IN 1 LINE TO OPEN 4.0E+03 1.0E -05 64 27 1.0E-06 IWX-CV1-AO CO*#40N CAUSE FAILURE OF IRWST INJECTION CVS IN 1 LINE TO OPEN 3.9E+03 5.4E-07 12 28 8.7E-07 CCX-PMS-HARDWARE COMMON CAUSE FAILURE OF PMS REACTOR TRIP SYSTEM HARDWARE 3.3E+03 7.9E-05 188 29 5.7E-07 CCX-EP-SA COD 940N CAUSE FAILURE OF PLS OUTPUT DRIVER (EPO) 80ARDS 2.2E+03 8.6E-06 10 30 5.4E-07 ADN-MAN 01 OPERATOR FAILS TO MANUALLt ACTUATE ADS 2.1E+03 3.0E-03 772 31 S.4E-07 IWX-XMTR Cone 40N CAUSE FAILURE OF TAhK LEVEL TRANSMITTERS (IRWST, BAT) 2.0E+03 4.8E-04 250 32 5.1E-07 CMA-PLUG CMT FLOW TUNING ORIFICE PLUGS 1.9E+03 7.3E-04 202 33 4.3E-07 LPM-MANO2 OPFRATOR FAILS TO RECOGNIZE NEED FOR RCS DEPR. (MLOCA) 1.6E+03

3. 3E -0 3 5%

34 4.3E-07 ACX-CV-GO COMMON CAUSE FAILURE OF 2 ACCUMULATOR CHECK VALVES 1.6E+03 5.1E-05 61 35 3.6E-07 CMX-AV-LA CODNON CAUSE FAILURE OF 2 CMT AOVS TO OPEN 1.4E+03 9.6E-05 62 36 3.4E-07 CMA-CV CMT CHECK VALVES V016A/017A FAIL TO OPEN 1.3E+03 2.OE-06 8 37 3.4E-07 CMATK002AF CMT TANK T002A RUPTURES 1.3E+03 2.4E-06 8 38 3.4E-07 CMAOR001EB CAT FLOW TUNING ORIFICE RUPTURES 1.3E+03

7. 7E -07 4

39 3.1E-07 CCX-BC-SA COMMON CAUSE FAILURE OF CLASS 1E BATTERY CHARGERS

1. 2E+03 8.4E-06 9

40 2.3E-07 PXX-AV-LA COPO40N CAUSE FAILURE OF PRHR AOVS 8.8E+02 9.6E-05 315 41 2.0E-07 MOAS FAILURE OF MANUAL DAS HARDWARE 7.8E+02 1.0E-02 850 42 1.9E-07 REC-MANDAS OPERATOR FAILS TO ACTUATE A SYSTfM USING DAS OeAY 7.1E+02 1.2E-02 202 43 1.5E-07 ACX-TK-AF cop 940N CAUSE FAILURE 6 ACCUn9JLATOR TANKS 5.8E+02 1.2E-07 3 44 1.5E-07 CIX-AV-LA cop 940N CAUSE FAILURE OF ALL CI AOVS TO CLOSE 5.6E+02 7.7E-04 777 45 1.5E-07 CCX-XMTR1 COMMON CAUSE FAILURE OF CONT P2R XMTRS AFTER ACCIDENT 5.5E+02 4.8E-04 626 46 1.4E-07 ATW-MANOS OPERATOR FAILS TO MANUALLY TRIP REACTOR VIA PMS 5.2E+02 5.2E-03 4 47 1.2E-07 LPM-MAN 01 OPERATOR FAILS TO RECOGNIZE NEED FOR RCS DEPR. (SLOCA/TRANSILNT) 4.7E+02 1.3E-03 126 48 1.2E-07 CCX-TT-UF COMMON CAUSE FAILURE OF TE*4P SENSORS 4.6E+02 1.2E-04 43 49 1.1E-07 IDOSSDOITM BUS UNAVAILABLE DUE TO TEST OR CORRECTIVE MAINTENANCE 4.2E+02 3.0E-04 193 50 1.1E-07 IDDeSOSITM BUS UNAVAILABLE OUE TO TEST OR CORRECTIVE MAINTENANCE 4.2E+02 3.0E-04 193 51 9.9E-08 CIS-MAN 00 OPERATOR FAILS TO DIAGNOSE SGTR EVENT 3.8E+02 1.8E-03 52 52 9.2E-08 IOASSOO1rM BUS UNAVAILA8LE DUE TO TEST OR CORRECTIVE MAINTENANCE 3.5E+02 3.0E-04 200 Ii h2-sens.wpf 1 t

y 53 9.2E-08 IDA85051TM 8US UNAVAILA8LE DUE TO TEST OR CORRECTIVE MAINTENANCE 3.5E+02 3.OE-04 200 54 9.2E-08 IDA85DK1TM BUS UNAVAILABLE DUE TO TEST OR CORRECTIVE MAINTENANCE 3.5E+02 3.0E-04 188 ' )' 55 8.7E-08 DAS FAILURE OF AUTOMATIC DAS FUNCTION 3.3E+02 1.OE-02 208 1 56 8.3E-08 CCX-PMAM001 COMMON CAUSE FAILURE OF OUTPUT LOGIC I/Os 3.2E+02 1.4E-04 181 ~ l 1 57 8.3E-08 CCX-PMA030 COMMON CAUSE FAILURE OF OUTPUT LOGIC GROUPS' 3.2E+02 9.7E-05 150 58 8.OE-08 OTH-5GTR CONSEQUENTIAL SGTR OCCURS 3.1E+02 1.0E-02 534 59 7.9E-08 REN-MANO3 OPERATOR FAILS TO OPEN IRWST VALVES TO FLOOD REACTOR CAVITY 3.0E+02 3.4E-03. 887 60 7.9E-08 IWX-MV-GO COs940N CAUSE FAILURE OF RECIRC MOVs TO OPEN 3.0E+02 4.4E-03 1145 61 7.8E-08 CCX-RM-UF FAILURE OF CONTANINMENT RADIATION MONITOR 5 3.OE+02 7.6E-05 129 62 7.7E-08 CCX-PMAM004 COD 940N CAUSE FAILURE OF MUN LOGIC GROUPS 2.9E+02 5.OE-05 56 63 7.5E-08 IWX-EV2-5A COpO90N CAUSE FAILURE OF RECIRC SQUIS VALVES 118A/8 2.8E+02 1.0E-05 42 64 7.5E-08 IDAFD003RQ FUSE DISCONNECT SWITCH (FD3) SPURIOUSLY OPENS 2.8E+02 1.2E-05 16 65 7.5E-08 IDAF0004RQ FUSE DISCONNECT SWITCH (FD4) SPURIOUSLY OPENS 2.8E+02 1.2E-05 16 66 7.3E-08 IDA85001LF SUS IDSA-OD-1 FAILS (ALL MODES) 2.8E+02 4.8E-06 12. - 67 7.3E-08 IDA85DKILF SUS IDSA-DK-1 FAILS (ALL MODES) 2.8E+02 4.8E-06 12 68 7.3E-08 IDABSDSILF BUS IDSA-DS-1 FAILS (ALL MODES) 2.8E+02 4.8E-06 12 2.8E+02 4.0E-06 11 69 7.3E-08 CCX-PMAEHO COMMON CAUSE FAILURE OF MUX TRANSMITTERS 2.7E+02 2.4E-04 90 70 7.2E-08 RE8-PLUG SUMP SCREEN 8 PLUGS AND PREVENTS FLOW 71 7.0E-08 IDSB5001TM SUS UNAVAILABLE DUE TO TEST OR CORRECTIVE MAINTENANCE 2.7E+02 3.OE-04 245 72 7.0E-08 IDSBSDSITM SUS UNAVAILABLE DUE TO TEST OR CORRECTIVE MAINTENANCE 2.7E+02 3.OE-04 245 73 7.OE-08 IDD850K1TM SUS UNAVAILABLE DUE TO TEST OR CORRECTIVE MAINTENANCE 2.7E+02 3.0E-04 94 74 6.8E-08 IW8-fLUG IWRST DISCHARGE LINE ~B" STRAINER PLUGGED 2.6E+02 2.4E-04 162 75 6.3E-08 ATW-MANO3 OPERATOR FAILS TO MANUALLY TRIP REACTOR VIA PMS 2.4E+02 5.2E-02 255 76 6.2E-08 RN11M003 HARDWARE FAILURE OF NORMAL RHR ISOLATION MOV 011 2.4E+02 1.4E-02 603 77 6.2E-08 RN22M004 HARDWARE FAILURE OF N-RHR MOV V022 FTO/C8 FTC/ RELAY FTC 2.4E+02 1.4E-02 603 78 6.2E-08 RN23 MODS HARDWARE FAILURE OF N-RHR MOV VO?3 FTO/C8 FTC/ RELAY FTC 2.4E+02 1.4E-02 603 79 6.1E-08 CIS-MAN 01 OPERATOR FAILS TO CLOSE MSIV FOR FAILED SG 2.3E+02 1.3E-0 3 50 80 6.1E-08 RNX-KV1-GO COB 940N CAUSE FAILURE OF N-RHR STOP CHECK VALVES v015A/S TO OPEN 2.3E+02 4.9E-03 321 81 6.1E-08 CCX-PMDMOD1 COMMON CAUSE FAILURE OF OUTPUT LOGIC I/Os 2.3E+02 1.4E-04 56 82 5.1E-08 CCX-PMD030 cob 940N CAUSE FAILURE OF OUTPUT LOGIC GROUPS 2.3E+02 9.7E-05 41 83 6.0E-08-RHN-MAN 01 OPERATOR FAILS TO ALIGN AND ACTUATE NORMAN RHR 2.3E+02 2.9E-03 224 84 6.0E-08 CCX-PMDM004 COMMDN CAUSE FAILURE OF 84UX LOGIC GROUPS 2.3E+02 5.OE-05 27 85 6.OE-08 RNNCV013GO N-RHR CHECK VALVE v013 FAILURE TO OPEN 2.3E+02 1.8E-03 189 86 5.8E-08 SGBAv040LA AOV MSIV v0408 FAILS TO CLOSE 2.2E+02 1.1E-03 49 87 5.8E-08 RNX-PM-F5 COMMON CAUSE FAILURE OF N-RHR PUMPS TO START 2.2E+02 7.7E-04 115 88 5.8E-08 IDDrD019RQ FUSE DISCONNECT SWITCH (FD19) SPURIOUSLY OPENS 2.2E+02 1.2E-05 28 89 - 5.7E-08 RNX-KV-GO COMMON CAUSE FAILURE OF N-RHR STOP CHECK VALVES v007A/B TO OPEN 2.2E+02 6.1E-04 104 90 5.6E-08 CCX-TRNSM COMMON CAUSE FAILURE OF SENSORS IN LOW PRESSURE ENVIRONMENT 2.2E+02 4.8E-04 121 91 5.2E-08 IDCBSDO1TM SUS UNAVAILABLE DUE TO TEST OR CORRECTIVE MAINTENANCE 2.0E+02 3.0E-04 101 92 5.2E-08 IDCBSDSITM BUS UNAVAILASLE DUE TO TEST OR CORRECTIVE MAINTENANCE 2.0t+02 3.0E-04 101 93 5.1E-08 IDo85DOILF BUS IDSo-oD-1 FAILS (ALL MODES) 2.OE+02 4.8E-06 16 94 5.1E-08 IDDBSOSILF BUS IDSD-DS-1 FAILS (ALL MODES) 2.0E+02 4.8E-06 16 95 5.OE-08 RNAEPO225A FAILURE OF OUTPUT DRIVER 1.9E+02 1.7E-04 45 96 5.0E-08 RN8EP0115A FAILURE OF OUTPUT DRIVER 1.9E+02 1.7E-04 45 97 5.0E-08 RNDEP0235A rAILURE OF OUTPUT DRIVER 1.9E+02 1.7E-04 45 98 5 OE-08 CCX-PL4 MOD 1 CO8940N CAUSE FAILURE OF OUTPUT LOGIC I/Os 1.9E*02 1.4E-04 43 99 5.0E-08 CCX-PLMM004 COe4 MON CAUSE FAILURE OF e4UX LOGIC GROUPS 1.9E+02 5.OE-05 25 100 5.0E-08 CCX-PL403 coa 940N CAUSE FAILURE OF OUTPUT LOGIC GROUPS 1.9t+02 9.7E-05 33 101 5.0E-08 RNX-CV-GO COMMON CAUSE FAILURE OF N-RHR CHECK VALVES V017A/8 TO OPEN 1.9E+02 5.1E-05 19 102 4.9E-08 IDSF0013RQ FUSE OI5 CONNECT SWITCH (FD13) SPURIOUSLY OPENS 1.9E+02 1.2E-05 40 103 4.9E-08 RNX-PM-ER COPO40N CAUSE FAILURE OF N-RHR PUMPS TO RUN 1.9E+02 1.6E-05 15 104 4.9E-08 IDOFD020RQ FUSE DISCONNECT SWITCH (FD20) SPURIOUSLY OPENS 1.9E+02 1.2E-05 12 105 4.9E-08 CCX-PL4M001*SW COMMON CAUSE FAILURE OF SOFTWARE FOR OUTPUT LOGIC GROUPS 1.9E+02 1.1E-05 11 106 4.9E-08 CCx-PL MM004-5W COB 940N CAUSE FAILURE OF SOFTWARE FOR MUX GROUPS 1.9E+02 1.1E-05 11 107 4.9E-08 IWX-EV3-SA coa 940N CAUSE FAILURE OF RECIRC SQUIB VALVES 1188 & 1208 1.9E+02 1.0E-05 11 108 4.7E-08 CCX-PL4EHO COpO40N CAUSE FAILURE OF MUX TRANSMITTERS 1.8E+02 4.OE-06 8 109 4.7E-08 CCX-FeOEHO COMMON CAUSE FAILURE OF MUX TRANSMITTERS 1.8t+02 4.0E-06 8 110 4.7E-08 ID08SDKILF BUS IDSD-DK-1 FAILS (ALL MODES) 1.8E+02 4.8E-06 8 111 3.9E-08 IDCFD007RQ FUSE DISCONNECT SWITCH (FD7) SPURIOUSLY OPENS 1.5E+02 1.2E-05 19 112 3.7E-08 CCX-VS-FA COMMON CAUSE FAILURE OF CONTAINp4ENT Sup4P LEVEL XMTRS 1.4E+02 3.8E-05 15 113 3.5E-08 CVMODO4 CVS DISCHARGE LINE FAILURE 1.3E+02 7.4E-04 105 114 3.4E-08 OTH-SDMAN OPERATOR FAILS TO PERFORM CONTROLLED SHUTDOWN (RTN-MAN 01) 1.3E+02 7.7E-04 102 115 3.3E-08 CVN-MAN 00 OPERATOR FAILS TO ACTUATE CVS IN AUX SPRAY MODE IN SGTR EVENT 1.3E+02 3.1E-03 5 116 3.3E-08 EC185001TM UNAVAILABILITY OF SUS ECS ES 1 DUE TO UNSCHEDUL e4AINTENANCE 1.2E+02 2.7E-03 725 117 3.1E-08 IWNTKOO1AF FAILURE OF P-RHR DUE TO IRWS TANK FAILURE 1.2E+02 2.4E-06 6 12 h2wns*pf

s 118 1.1E-08 PCNHR001ML PtUG/ LEAK OF PRHR HEAT EXCHANGER 1.2E+02 2.4E-06 6 119 3.1E-08 CVMooO1 CVS SUCTION FOM BORIC ACID TANK FAILURE 1.2E+02 2.ZE-04 48 120 3.1E-08 ADX-MV-GO COMmN CAUSE FAILURE OF 4/4 STAGE 2 & 3 LINE MOVs TO OPEN 1.2E+02 1.1E-03 13 121 3.0E-08 ECOMOD01 MAIN GEN. SKR ES 01 FAILS TO OPEN [# 12] 1.2E+02 5.1E-03 973 122 2.8E-08 CCX-PL3M001 COMMON CAUSE FAILURE OF OUTPUT LOGIC I/Os 1.1E+02 1.4E-04 56 123 2.6E-08 IWAR51188FA RELAY FAILS TO OPERATE 1.0E+02 8.8E-04 142 124 2.6E-08 1RwMOD11 HARDWARE FAILURE OF IRwST 50018 VALVE 1188 1.0E+02 1.5E-03 110 125 2.6E-08 RE8 tov 117TM MOV 1178 tmAVAIL DUE TO TEST AND UNSCHEDULED MAINTENANCE 1.0E+02 5.0E-04 102 126 2.6E-08 IRWMOOO3 HARDWARE FAILURE CAUSES RECIRC MOV 1178 FAILS TO OPEN 1.OE+02 1.2E-02 629 127 2.6E-08 IR8EP11785A FAILURE OF OsJTPUT DRIVER 1.0E+02 1.7E-04 52 128 2.6E-08 IRDEP11885A FAILURE OF OUTPUT DRIVER 1.0E+02 1.7E-04 52 129 2.5E-08 OTH-PRSOV FAILURE OF EITHER PZR SV FAILS TO RECLOSE 9.6E+01 1.OE-02 504 130 2.1E-08 OTN-5L50V1 FAILURE OF A SECONDARY SIDE RELIEF VALVE TO CLOSE ($V/PORV) 8.2E+01 2.1E-02 275 ] 131 2.1E-08 EC185012TM SUS UNAVAILA8LE DUE TO UNSCHEDULED MAINTENANCE 8.0E+01 2.7E-01 244 132 2.1E-08* REA-PLUG SUMP SCREEN A PLUGS AND PREVENTS FLOW 7.9E+01 2.4E-04 34 133 1.9E-08 CCX-Pt303 CONNON CAUSE FAILURE OF OUTPUT LOGIC GROUPS 7.2E+01 9.7E-05 38 j 134 1.7E-08 EC285002TM UNAVAILASILITY OF SUS ECS ES 2 DUE TO UNSCHEDUL MAINTENANCE 6.6E+01 2.7E-03 367 135 1.7E-08 REN-MAN 04 OPERATOR FAIL 5 TO ACTUATE CONT. SUMP RECIR. (LEVEL SIGNAL FAILS) 6.5E+01 1.0E-02 200 136 1.6E-08 OTH-SL50V FAILURE OF A SECONDARY SIDE RELIEF VALVE TO CLOSE (SV/PORV) 6.2E+01 1.1E-02 162 137 1.6E-08 OTH-5L50V3 FAILURE OF SG PORV & 1 SG SV ON RUPTURED SG TO CLOSE 6.2E+01 5.4E-03 109 138 1.6E-08 CANTP011RI FAILURE OF AIR COMPRESSOR TRANSMITTER 6.2E+01 5.2E-03 90 139 1.6E-08 RCIC8051GO PUMP A FAILS TO TRIP - BREAKER FAILS TO OPEN 6.1E+01 4.2E-03 84 140 1.6E-08 RCIC8052GO PUMP A FAILS TO TRIP - BRE AKER FAILS TO OPEN 6.1E+01 4.2E-03 84 141 1.6E-08 RC1C8053GO PUMP A FAILS TO TRIP - BREAKER FAILS TO OPEN 6.1E+01 4.2E-03 84 142 1.6E-08 RCIC8054GO PUMP A FAILS TO TRIP - BREAKER FAILS TO OPEN 6.1E+01

4. 7E-0 3 84 143 1.6E-08 RCIC8061GO PUMP 8 FAILS TO TRIP - BREANER FAILS TO OPEN 6.1E+01 4.2E-03 84 144 1.6E-08 RCICB062GO PUMP 8 FAILS TO TRIP - BREAKER FAILS TO OPEN 6.1E+01 4.2E-0 3 84 145 1.6E-08 RCIC8063GO PUMP 8 FAILS TO TRIP - BREAKER FAILS TO OPEN 6.1E+01 4.2E-03 84 146 1.6E-08 RC1C8064GO PUMP 8 FAILS TO TRIP - 8REAKER FAILS TO OPEN 6.1E+01 4.2E-03 84 147 1.5E-08 RPTMOD01 COMPONENTS FAILURE 5.7E+01 8.8E-04 34 148 1.5E-08 RPTMOD02 COMPONENTS FAILURE 5.7E+01 8.8E-04 34 149 1.5E-OS RPTmOO3 COMPONENTS FAILURE 5.7E+01 8.8E-04 34 150 1.5E-08 RPTM0004 COMPONENTS FAILURE 5.7E+01 8.8E-04 34 151 1.5E-08 RPTM0005 COMPONENTS FAILURE 5.7E+01 8.8E-04 34 152 1.5E-08 RPTM0006 COMPONENTS FAILURE 5.7E+01 8.8E-04 34 153 1.5E-08 RPTMOOO7 COMPOhENTS FAILURE 5.7E+01 8.8E-04 34 154 1.5E-08 RPTMOOO8 COMPONENTS FAILURE 5.7E+01 8.8E-04 34 155 1.4E-08 OTH-NSET FAILURE OF CONTROL ROD MG SETS TO TRIP SY DAS 5.3E+01
1. 8 E--0 3 57 156 1.3E-08 MSX-AV-FA COMMON CAUSE FAILURE OF STEAM DUMP VALVES TO OPEN 4.9E+01
1. 5E-03 11 157 1.3E-08 VLX-HI-5A COMMON CAUSE FAILURE OF HYDROGEN IGNITERS 4.9E+01 3.2E-04 84 158 1.3E-08 EDSM0001 FAILURE OF THE 12 VAC DISTR 8N PANEL 4.9E+01 3.0E-04 83 159 1.2E-08 VLX-ANLY2 CO>NON CAUSE FAILURE OF ANALYZERS OF H2 CONCENTRATION 4.8E+01 7.6E-05 37 160 1.2E-OS ED4 MOD 11 FIXED COMPONENTS FAILURE 4.5E+01 3.2E-04 95 161 1.20-08 ED4M00112 FIXED COMPONENTS FAILURE 4.5E+01 3.2E-04 95 162 1.2E-08 (CX-IV-XR CO MON CAUSE FAILURE OF CLASS 15 INVERTERS 4.4E+01 2.4E-05 47 163 1.1E-08 ED485D51TM BUS ED54 05 1 UNAVAILABLE CUE TO CORRECTIVE MAINTENANCE 4.2E+01 3.0E-04 82 164 1.0E-08 OTH-CNB FAILURE OF CONTAINMENT ISOLATION DUE TO RV RUPTURE 3.8E+01 1.0E -0 3 1

165 9.7E-09 ID885001LF BUS ID58-DO-1 FAILS (ALL MODES) 3.7E+01 4.8E-06 13 166 9.7E-09 ID885D51LF SUS ID58-DS-1 FAILS (ALL MODES) 3.7E+01 4.8E-06 13 167 9.5E-09 CONDVACUUM FAILURE OF MAIN COND. EVACUATION SYST. TO PROVIDE VACUUM 3.6E+01 1.0E-03 10 168 9.2E-09 ED185D51TM SUS ED51 DS 1 UNAVAILASLE DOE TO CORRECTIVE MAINTENANCE 3.5E+01 3.0E-04 89 169 9.0E-09 VF-FAILS VF-FAILS 3.4E +01 1.0E-01 1 170-8.9E-09 CCX-PLSMOD6 COMMON CAUSE FAILURE OF SIGNAL SELECTOR GROUPS-LOGIC SI/Os 3.4E+01 2.5E-04 9 171 8.4E-09 SWAM 00097 OPERATING 8 LOWER FAN HARDWARE FAILURE 3.2E+01 2.5E-04 7 172 8.4E-09 20X-PD-E5 COMMON CAUSE FAILURE TO START OF ENGINE-DRIVEN FUEL PUMP 5 3.2E+01 2.0E-03 113 173 8.0E-09 ECX-CS-GC COMMON CAUSE FAILURE 4KV SREAKER TO CLOSE 3.1E+01 7.3E-04 62 174 8.0E-09 ZOX-DG-DR COMMON CAUSE FAILURE OF STAND 8V DG TO RUN 3.1E+01 4.4E-04 49 175 8.0E-09 ECX-CB-GO Com0N CAUSE FAILURE 4KV EREAKERS TO OPEN 3.0E+01 4.2E-04 48 176-7.4E-09 EC185013TM BUS UNAVAILABLE DUE TO UNSCHEDULED MAINTENANCE 2.8E+01 2.7E-03 310 177 7.2E-09 CONTF018RI TRANSMITTER FAILURE 2.7E+01 5.2E-03 21 178 6.9E-09 MSAEPSDISA FAItuRE OF OUTPUT DRIVER M55-001 2.6E+0! 1.7E-04 3 179 6.9E-09 MSAEPSD25A FAILURE OF OUTPUT DRIVER M55-002 2.6E +01 1.7E-04 3 180 6.9E-09 MSAE PSD35A FAILURE OF OUTPUT DRIVER M55-003 2.6E+01 1.7E-04 3 181 6.9E-09 MSAEP5045A FAILURE OF OUTPUT DRIVER M55-004 2.6E+01 1.7E-04 3 182 6.9E-09 MSAEPSDSSA FAILURE OF OUTPUT DRIVER M55-005 2.6E +01 1.7E-04 3 e 13 h2 c m m pf

b .e A 183 6.9E-09 teSAEPSD6SA FAILURE OF OUTPUT DRIVER MSS-006 2.6E+01-1.7E-04 3 184. 6.9E-09 ' MSAEPSDISA - FAILURE OF OUTPUT DRIVER 8855-007-2.6E+01 1.7E 3 185 ~ 6.9E-09 MSAEPSDSSA FAltuRE OF OUTPUT DRIVER MSS-008 2.6E+01 1.7E-04 .3 186 6.7E-09l CCx-PL9 MOD 1 COMNON CAUSE FAILURE OF OUTPUT LOGIC I/Os 2.5E+01 1.4E-04 4 187 6.6E-09 ' ED1MDD03 sATTERY Del UNAVAILASLE' ' 2.5E+01 2.7E-03 183-188 6.6E-09..CCx-PLAM001-Comes0N CAUSE FAILURE OF OUTPUT LOGIC I/Os 2.5E+01 1.4E-04 3 -189 6.4E-09'CCx-PLMOD3: COsequN CAUSE FAILURE OF INPUT LOGIC GROUPS 2.AE+01 1.OE-04 4 .2.4E+01 3.3E-04 40. NO POWER FROM PREFERRED SRC DUE TO MECHMs.' SYSTEM' FAILURE (#10} 2.4E+01 8.4E-05, 18 OPERATOR FAILS TO ACTUATE HYDROGEN CONTROL 190 6.3E-09 VLN-tenN01 191 6.3E-091 ZANMOD01 192 6.0E-09 2Ite4CV124AO-IRwST CHECK VALVE 124A FAILS TO OPEN 2.3E+01 1.8E-03 .179 193 6.0E-09 EC2eS022TM BUS UNAVAILAeLE DUE TO UNSCHEDULED seAINTEMMcCE 2.3E+01 2.7E-03 116 194 6.OE-09 IRese0006 HARDWARF FAILURE OF IRwST VALVE 125A 2.3E+01 1.5E-0 3 167 195 5.9E-09 ' CAx-CM-Et Copse 0N CAUSE FAILURE OF COMPRESSORS TO RUN

2. 3E+01 1.2E-04 3

196 '5.9E-09. IwpRS125AFA RELAY F AILS TO OPERATE 2.?E+01 8.8E-04 129 197 5.8E-09:CCx-PL903 C08840N CAUSE FAILURE OF OUTPUT LOGIC GROUPS 2.2E+01 9.7E-05 -2 198 5.8E-09 CCx-PLA03 COMMON CAUSE FAILURE OF OUTPUT LOGIC GROUPS 2.2E+01 9.7E-05 2 199 5.7E-09 EC2sS023rM nUS UseAVAILASLE DUE TO UNSCHEDULED seAINTEfeMcCE 2.2E+01' 2.7E-03 215 200 -5.3E-09 EC2e5021TM -. SUS UNAVAILABLE DUE TO UNSCHEDULED se4INTEsenseCE 2.0E+01 2.7E-03 30 201 5.3E-09 EC255211TM" BUS UNAVAILASLE DUE TO UNSCHEDULED seAINTEfemfeCE - 2.0E +01 - 2.7E-03 15 202 4.9E-09 'IwACV122AO IRwST CHECK VALVE 122A FAILS TO OPEN 1.9E+01 1.8E '135" 203 4.9E-09 IRWM0005 HARossARE FAILURE OF IRWST VALVE 123A '1.9E+01 1.5E-03 122 204-4.9E-09 ' FuseOD028 SFw seDV V028 FAILS TO OPEN 1.9E+0'. 1.4E-02 60 - 205 4.8E-09 IweRS123AFA ~ RELAY FAILS TO OPERATE 1.8E+01 8.8E-04 97 206 4.6E-09 ED2pe0011 125 VDC PAfeEL EDS2 05 11 COpePONENT FAILURES 1.8E+01 3.2E-04 43 207 4.6E-09 ED2SSDSITM BUS EDS2 DS 1 UseAVAILASLE DUE TO CORRECTIVE seAINTEfe4NCE 1.8E+01 3.OE-04 37 208 4.6E-09 ED3 MOD 01 FIXED COMPONENT FAILS: CKY 90LR. INVERTER. OR STATIC xFER Sw 1.8E+01 5.0E-04 33 209 4.6E-09 CCx-PL3M005 COsWe0N CAUSE FAILURE OF MODULATING GROUPS - LOGIC & 1/Os 1.7E+01 7.0E-05 3 210 4.3E-09 DUseP-senfs01 OPERATOR FAILS TO CONTROL STERAss DUseP VALVES IN A SGTR EVENT ' 1.6E+01 . 1. 3E.-03 4 ' 211 4.2E-09 ECIM0012 FIXED COpePONENT FAULTS 1.6E+01

4. 8E -05 7

212 4.2E-09 OTH-SLSOV2 FAILURE OF A SECOseDARY SIDE RELIEF VALVE-TO CLOSE (SV) 1.6E+01 1.OE-02 42 213 4.0E-09 CCx-PLDs0001 COsee0N CAUSE FAILURE OF OUTPUT LOGIC I/Os 1.5E+01 1.4E-04 1' 214 4.0E-09 CCx-PLD03-COsoq0N CAUSE FAILURE OF OUTPUT LOGIC GROUPS 1.5E+01 9.7E-05 1 215 = 4.0E-09. CCx-PL2*e005 COpoe0N CAUSE FAILURE OF N00ULATI98G GROUPS - LOGIC & I/Os 1.5E+01 7.0E-05 1 216 '4.0E-09 OTH-SGTR1 SINGLE CONSEQUENTIAL SGTR OCCURS

1. 5E+01 6.7E-03 29 217 4.0E-09 ' Fuse 00067A

- SFw MOV V067A FAILS TO OPEN 1.5E+01-1.4E-02 26 .218 3.7E-09 ED18e0011 FIXED COMPONENTS FAILURE 1.4E+01 3.2E-04 39 219 3.7E-09 ED18e00113 ' FIXED CUMPONENTS FAILURE 1.4E+01 3.2E-04 39 220 3.6E-09 ECisS011TM BUS UNAVAILABLE DUE TO UNSCHEDULED 9eAINTEDIAfeCE 1.4E+01 2.7E-03 198 -221 3.6E-09 EDIMOD13 FIXED COMPO8sENTS FAILURE-1.4E+01 3.2E-04 58 222 3.6E-09 EDlpe0007 . EDS1 EA 1 DISTR. P98L FAILURE Ost TSN 1 4E+01 3.0E-04 54 223-3.5E-09 CANAV014LA AOV VO14 FAILS TO CLOSE

1. 3E+01 8.8E-03:

352 '224 3.4E-09 ED19e0001 FIXED COMPOS 0ENT FAILURES:'CKT SKR. INVERTR. OR STATIC xFER Sw

1. 3E +01 5.0E-04 55 225 3.3E-09 CIAEP0145A FAILURE OF OUTPUT DRIVER 1.3E+01 1.7E-04 60 226 3.3E-09 ' REC-pe4NDASC COND. PROS. OF REC-MAfsDAS (FAILURE OF penssUAL DAS ACT.)

1.2E +01 5.1E-01 811. .227 3.3E-09 MSHTP001RI-TURsIseE ItePULSE PRESSURE TRANSMITTER 001 (DAS TRIP PERMISSIVE) 1.2E+01 5.2E-03 61 228 3.3E-09 MSHTPOO2RI TuReIseE IsePULSE PRESSURE'TRANSSSITTER 002 (DAS TRIP PEReeISSIVE) 1.2E+01-3.2E-03 61 229 3.2E-03 PLase0041 FAILURE OF mux LOGIC GROUP 1 1.2E+01 6.4E-04 59 230 3.0E-09 ATw-senn 04C COseD.-PROE. OF ATw-teAfe04 (OPER. FAILS TO TRIP REACTOR) 1.2E+01

5. 3E-01 154 231 3.0E-09 EC1ss121TM

-SUS UNAVAILABLE DUE TO UNSCHEDULED feAINTEfeApeCE 1.1E+01 2.7E 127 232 2.9E-09 EC2eS221Tes BUS UseAVAILASLE DUE TO UNSCHEDULED seAINTEseAfeCE 1.1E+01 2.7E-03 112 233 2.9E-09' RNAM0009 HMtDWARE FAILURE OF N-RHR VALVES Ost DVI LIneE A (v 015A & 017A) 1.1E+01 5.1E-02 220 234 2.9E-09 RNOMOD10 HARDesMtE FAILUltE OF N-RHR VALVES 00E DVI LIteE S (V 015e & 017s) 1.1E+01 5.1E-02 220 235.2.8E-09 2Ox-DG-OS COsWe0N CAUSE FAILuftE OF STANDBY DG TO S1'Astr 1.1E +01 _ 2.8E-04 27 236 2.5E-09 RoseM0007 N-RHR PUMP Ole FAILS /ST CK V007s/cm FTC/RE FTC/CS ECS221 SPO 9.6E+00 3.4E-02 413 237 2.5E-09 CMB-PLUG CMT FLON TUNIteG ORIFICE PLUGS 9.5E+00 7.3E-04 23 238 '2.5E-09 ZOx-PD-ER copse 0N CAUSE FAILURE TO RUN OF ENGIfsE-DRIVEN FUEL PUsePS ' 9.4E+00 1.3E-04 13 239

2. 3E-09 ~ stseAM0006 N-RHet PUMP 01A FAILS /ST' CK v007A/Ca FTC/RE FTC/CS ECS122 SPO.

8.7E+00 3.4E-02 338 240 2.1E-09 ADN-RECD 1 OPERATOft FAILS TO 944feUALLY ACTUATE ADS AFTER CORE 04senGE 8.ZE+00 5.0E-02 179 241 .2.1E-09 LPee-REC 01 OPERATOR FAILS TO RECOGNIZE 9eEED FOst ACS DEPR. AFTER COstE men 8.2E+00 5.OE-02' 179 242 2.0E-09 Cvu0007 CVS seECHAfsICAL FAILustE OF AOV VOS1 FAILS TO CLOSE .7.5E+00 2.7E-02 26 243 1.9E-09 CvuoD05 CVS teECHAfdICAL FAILustE OF AOV V084 AfsD CV VOSS TO OPEN 7.4E+00 .2.9E-02 26 244 1.9E-09' BSIZE LLOCA BREAK SIZE -LOWER END OF SREAK SIZE 7.3E+00 5.OE-01 705 245 '1.9E-09 SSIZE-LARGE LLOCA SREAK SIZE - UPPER END OF SREAK SIZE 7.3E+00 5.OE-01 705 7.1E+00 1.OE-01 6 246 1.9E-091 POS6-seenADS P056-MANADS. 7.1E+00 - 1.7E-04 21 247 1.9E-09J RNAEP01eSA FAILURE OF OUTPUT DetIVER 14 h2-sens2pf = - _ - _ - _ - _ _

<N+; J 244 -1.8E-09: ECIM0013' ' FIXED COMPONENT FAULTS . 7.1E+00 4.8E-05 13 249 1.8E-09 -RNAEP01ASA FAILURE OF OUTPUT DRIVER 7.1E+00. ~1.7E-04 . 20 250 1.8E-09 EC2 MOD 23 FIXED COMPONENT FAULTS 6.8E+00 4.8E-05 12 6.4E+00 2.4E-02 784 251 1.7E-09 CANCv015GC INSIDE COhTAIN. CV v015 FAIL 5'TO CLOSE 5.9E+00 8.8E-0 3 - 11 '252 '1.6E-09. SGaAv074LA ' 'AOV v074s FAILS TO CLOSE 5.9E+00 8.8E-03 11 253 1.6E-09 5GSAvo75LA - AOV vo758 FAILS TO CLOSE 5.5E+00 4.6E-02 354 254 1.4E-09 ZO2DG002TM-STANOBY DG UnkVAILASLE DUE TO TEST AND MAINTENANCE 255 1.3E-09 ~202M0001 OG FAILS TO START & RUN OR SKR 202 FAILS TO CLOSE 5.1E+00 2.0E-02 198 256 1.3E-09 CCx-PMmMOD1'. comeq0N CAUSE FAILURE OF OUTPUT LOGIC I/Os . 5.0E+00 1.4E-04 43 .257-1.2E-09 'WLIAv004LA-

INSIDE CONTA18R4 AOV v004 FAILS TO CLOSE 4.8E+00 8.8E-03

,240 258 1.2E-09 wtIAvo55LA AOV VALVE v055 FAILS TO CLOSE 4.8E+00 .8.8E-03 240 259 1.2E-09 wtOAv006LA OUTSIDE CONTAIN. AOV v006 VALVE FAILS TO CLOSE - 4.8E+00 8.8E-03 240 260 1.2E-09 WLOAv057tA' ADV VALVE v057 FAILS TO CLOSE '4.8E+00 8.8E-03' 240 261 1.2E-09 Twx-Mv2-GO. Cones 0N CAUSE FAILURE OF SFw MOvs v028, v013Ai v0138 TO OPEN 4.7E+00-5.5E-04 5 262 ~ 1.2E-09 FwX-FM2-F5 .CopequN CAUSE FAILURE OF SFw PUMPS TO START 4.7E+00 5.4E-04 5' 263 '1.2E-09 SG21F50ARI. TRANSMITTER FAILURE ' 4.7E+00; 5.2E 3-264 1.1E-09 ECle5001LF MECHANICAL FAULT ON BUS ECS ES 1. 4.2E+00 - 4.8E-06 '2 265 1.1E-09 EC285002LF MECHANICAL FAULT ON BUS ECS ES 2 - 4.2E+00 4.8E-06 2 266 1.1E-09 ED185D51LF EDS1 DS 1 SMITCHGEAR FAILURE 4.2E+00 4.8E-06 2 267 1.1E-09 ED2BSDSILF ED52 05 1 SWITCHGEAR FAILURE 4.2E+00

4.8E 2 268

'1.0E-09 FwSSEDD11A FAILURE OF ELECTRICAL SUPPORT HARDWARE FOR seFW WO57A 4.0E+00 3.3E-04 1 269 1.0E-09 Fwese00118 FAILURE OF ELECTRICAL SUPPORT HARDWARE FOR MFw v057A 4.0E+00 3.3E-04 1 270 1.0E-09.EcleS111TM BUS UNAVAILASLE DUE TO UNSCHEDULED MAINTENANCE 3.9E+00 2.7E-03 98 ' 271 1.OE-09: EC2Cs200v0 sREAKER 200 FAILS TO OPEN [83.5] 3.9E+00 4.2E-03 55 e 15 h2*ns.wpf

}; .o,, WI T..'.'4 Table 5 m BASIC EVENT IMPORTANCES FOR DIFFUSION FLAME FAILURE SENSITIVITY CASE SORTED BY RISK DECREASE LRF = 2.620E-08 DECREASE 8ASIC EVENT .IMPORTANCE SASIC EV.

  1. OF -

IN TOTAL DESCRIPTION % DECREASE PROSABILITY CUTSETS 1 8.1E-09~DF-FAILS DF-FAILS 30.% 1.OE+00 2593 2 5.7E-09' ADX-EV-SA COMMON CAUSE FAILURE OF 4TH STAGE ADS SQUIB VALVES TO OPERATE 21.70 3.0E-05 3174 3 4.0E-09 CCX-XHTR COMMON CAUSE FAILURE CF SENSORS IN HIGH PRESSURE ENVIROMENT 15.25 4.8E 146 4 4.OE-09 CCX-XMTR195 COMMON CAUSE FAILURE OF PZR LEVEL SENSORS 15.13 4.8E-04 134. 5 3.5E-09 ATW-MANO3 OPERATOR FAILS TO MANUALLY TRIP REACTOR VIA PMS 13.23 5.2E-02 255 6 3.4E-09 ATW-MAN 04C COND. PROS. OF ATW-MAN 04 (OPER. FAILS TO TRIP REACTOR) 12.86 5.3E-01 154 7 3.3E-09 REC-MANDASC CONO. PROS. OF REC-MANDAS (FAILURE OF MANUAL OAS ACT.) 12.78 5.1E-01 811 8-2.9E-09 (CX-PMXMOol-SW cop # EON CAUSE FAILURE OF PMS ESF OUTPUT LOGIC SOFTWARE 11.21 1.1E-05 212 9-2.3E-09 CCX-EP-SAM Cope 90N CAUSE FAILURE OF OUTPUT DRIVERS 8.78 8.6E-06 185 10 2.3E-09 CCX-SFTW COMMON CAUSE FAILURE OF PMS AND PLS SOFTWARE 8.64 1.2E-06 191 11 2.2E-09 IwX-FL-GP COMMON CAUSE FAILURE OF STRAINER $ IN IRwST TANK 8.51 1.2E-05 1264 12 2.2E-09 REC-MANDAS OPERATOR FAILS TO ACTUATE A SYSTEM USING DAS ONLY' 8.33 1.2E-02 202 13 2.1E-09 IR-SUCCESSFUL IR-SUCCESSFUL 8.18 1.0E+00 539 14 2.1E-09 SUCCESS-DP/IS SUCCESS-DP/IS 8.18 9.0E-01 539 15 2.1E-09 MDAS FAILURE OF MANUAL DAS HARDWARE 7.86 1.OE-02 850 16 1.9E-09 SSIZE LLOCA RREAK SIZE -LOWER END OF BREAK SIZE 7.27 5.OE-01 705 17 1.9E-09 BSIZE-LARGE LLOCA BREAK SIZE - UPPER END OF BREAK SIZE 7.27 5.OE-01 705' 18 1.7E-09 RPX-CR-GO COpoq0N CAUSE FAILURE OF RCP SREAKERS FAIL TO OPEN 6.58 4.2E-04 181 19 1.6E-09 ADN-MAN 01 OPERATOR FAILS TO MANUALLY ACTUATE ADS 6.24 3.0E-03 772 20 1.4 E-09 LPM-MAN 02 OPERATOR FAILS TO RECOGNIZE NEED FOR RCS DEPR.'(MLOCA) 5.45 3.3E-03 596 21 1.0E-09 ED3MOOO7 EDS3 EA 1 DISTR. PANEL FAILURE OR TAM (DAS/PLS CABINET SUPPLY) 3.89 3.0E-04 261 22 1.0E-09 VF-FAILS VF-FAILS 3.82 1.OE-01 1 23 8.8E-10 RN11 MOD 3 HARDWARE FAILURE OF NORMAL RHR ISOLATION MOV 011 3.36 1.4E-02 603 24 8.8E-10 RN22 MOD 4 HARDWARE FAILURE OF N-RHR MOV V022 FTO/C8 FTC/ RELAY FTC 3.36 1.4E-02 603 25 8.8E-10 RN23 MOO 5 HARDWARE FAILURE OF N-RHR MOV V023 FTO/C8 FTC/ RELAY FTC 3.36 1.4E-02 603 26 8.7E-10 DAS FAILURE OF AUTOMATIC DAS FUNCTION 3.34 1.0E-02 208 27 6.1E-10 OTH-SGTR CONSEQUENTIAL SGTR OCCURS 3.09 1.OE 534 28 7.1E-10 ATW-MANOS OPERATOR FAILS TO MANUALLY TRIP REACTOR VIA PMS 2.72 5.2E-03 4 29 7.0E-10 ATW-MAN 06C COND. PROB.' OF ATW-MAN 06 (OPER. FAILS TO TRIP REACTOR VIA DAS) 2.65 5.0E-01 1 30 6.7E-10 IWA-PLUG IWRST DISCHARGE LINE "A" STRAINER PLUGGED 2.57 2.4E-04 348 31 4.9E-10. CCX-INPUT-LOGIC COpeeON CAUSE FAILURE OF PMS ESF INPUT LOGIC GROUPS (HARDWARE) 1.85 1.OE-04 402 32 4.6E-10 OTH-SLSOV1 FAILURE OF A SECONDARY SIDE RELIEF VALVE TO CLOSE (SV/PORV) 1.76 2.1E-02 -275 33 3.7E-10 IWX-EV4-SA COpeeON CAUSE FAILURE OF 4 SQUIB VALVES IN RECIRC LINES 1.42 2.6E-05 704 34 3.7E-10 CMA-PLUG CMT FLOW TUNING ORIFICE PLUGS 1.41 7.3E-04 202 35 3.5E-10 IWX-MV-GO COMMON CAUSE FAILURE OF RECIRC MOVs TO OPEN 1.33 4.4E-03 1145 36 3.2E-10 IRWMOo03 HARDWARE FAILURE CAUSES RECIRC MOV 1178 FAILS TO OPEN 1.22 1.2E-02 629 37 3.1E-10 'OTH-ROS FAILURE TO RECOVER OFFSITE AC POWER IN 30 MINUTES 1.18 7.OE-01 244 38 3.1E-10 CCX-AV-LA COpeeON CAUSE FAILURE OF 4 AOVS TO OPEN 1.18 6.1E-05 318 39 3.0E-10 RNX-KV1-GO COpeeON CAUSE FAILURE OF N-RH4 STOP CHECK VALVES V015A/s TO OPEN 1.15 4.9E-03 321 40 2.7E-10 REN-MANO3 OPERATOR FAILS TO OPEN IRWST VALVES TO FLOOD REACTOR CAVITY 1.03 3.4E-03 887 41 2.6E-10 IwX-CV-AO COpeeON CAUSE FAILURE OF 4 IRwST IN3ECTION CHECK VALVES 1.00 3.0E-05 1782 42 2.6E-10 IWX-XMTR COpesON CAUSE FAILURE OF TANK LEVEL TRANSMITTERS (IRwST. BAT) 0.98 4.8E-04 250 43 2.5E-10 OTH-PRSOV FAILURE OF EITHER PZR SV FAILS TO RECLOSE O.97 1.0E-02 504 44 2.3E-10 CMX-CV-GO COBOEON CAUSE FAILURE OF 4 CMT CHECK VALVES TO OPEN 0.87 5.1E-05 246 45 2.2E-10 ADN-MAN 01C COND. PROB. OF ADN-MAN 01(OPER. FAILS TO ACT. ADS) 0.86 5.OE-01 4 46 2.2E-10 IwX-EV-SA COpesON CAUSE FAILURE OF 4 IRWST IN?ECTION SQUIB VALVES 0.85 2.6E-05 1554 47 2.2E-10 REC-MANDAS1 REC-MANDAS1 0.85 1.OE+00 124 48 2.2E-10 ADF-MAN 01 OPERATOR FAILS TO MANUALLY ACTUATE ADS (SGTR IF PRZ SPR FAILS) 0.83 5.0E-01 57 49 2.1E-10 POS6-MANADS PDS6-MANADS 0.79 1.OE-01 6 50 2.0E-10 EMX-VS-FA COMMON CAUSE FAILURE OF CMT/ SUMP LEVEL HEATED RTD SENSORS 0.77 3.8E-05 271 51 1.8E-10 CIB-MANDO OPERATOR FAILS TO OIAGNOSE SGTR EVENT 0.70 1.8E-03 52 52 1.8E-10 OTH-SLSOV FAILURE OF A SECONDAstY SIDE RELIEF VALVE TO CLOSE (SV/PORV) 0.69 1.1E-02 162 16 h2-sens wpf

D t Q' +.. g- +: ' ;e.; ' 53 - '1.8E-10 RHN-MAN 01' OPERATOR FAILS TO ALIGN AND ACTUATE NOReent RHR - . 0.67 ' :.2.9E 224 0.66 ~ 1.0E-02 .200 .54 1.7E-10. WEN-MAN 04. OPERATOR FAILS TO ACTUATE CONT. SUNP RECIA. (LEVEL SIGNAL FAILS). ' O.62 1.3E-03; 126 55 1.6E-10 fLPw-MnM01~ OPERATOR FAILS TO RECOGNIZE NEED FOR RCS DEPR. (SLOCA/ TRANSIENT) - '56 1.6E-10' RHM-844N01C " COND PROS. OF RMN-MAN 01 (FAILURE OF NORNAL RHR ACTUATION) O.61-5.0E-01 '. 75 / 7 57 .1.6E-10 RNAfeD09- - HARONARE FAILURE OF N-RHR VALVES ON DVI LINE A (V 015A & 017A) ~ 0.60 .5.1E-02 220 0.60 5.1E-02 220 58 1.6E-10 RNmMnO10 - HARONARE FAILURE OF N-RHR VALVES ON DVI LINE e (V 015s & 017s) - 0.59 5.1E-OI 973 59 1.6E-10 ! ECOM0001 - MAIN GEN. sER ES 01 FAILS TO OPEN [# 12] 60 1.1E-10 ADN-REC 01-OPERATOR FAILS TO MANUALLY ACTUATE ADS AFTER CDRE DAMAGE 0.43 '5.0E-02 .179 61 1.1E-10 LPet-REC 01 OPERATOR FAILS TO RECOGNIZE NEED FOR SCS DEPR AFTER CORE DAMAGE 0.43 5.0E-02 '179 '. 62 1.1E-10 CIX-AV-LA.. - COMMON CAUSE FAILURE OF ALL CI AOVS TO CLOSE 0.43 7.7E-04 ~ 777 - 63 1.1E-10 =RMNCV013GO ' N-RHR CHECK VALVE v013 FAILURE TO OPEN 0.40 - 1.8E-03 .189 64 1.0E-10 CVN-044M00 OPERATOR FAILS TO ACTUATE CVS IN Aux. SPRAY M00E IN SGTR EVENT 0.40 3.1E-03 p -- 5 e 4 _ 17 h2.sens opf -..}}

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