ML12229A119

Attachment 4, PVNGS Engineering Study 13-ES-A037, Revision 0, Fault Tree Analysis and Reliability Evaluation for Low Pressure Safety Injection (LPSI) Pump Trip at the Recirculation Actuation Signal (RAS)

ML12229A119
Person / Time
Site:	Palo Verde
Issue date:	08/03/2012
From:	Arizona Public Service Co
To:	Office of Nuclear Reactor Regulation
References
13-ES-A037, Rev 0
Download: ML12229A119 (33)

Text

Enclosure Response to Request for Additional Information, Review of Single Failure Analysis of Low Pressure Safety Injection Pumps for Minimum Required Refueling Water Tank Transfer Volume Attachment 4 PVNGS Engineering Study 13-ES-A037, Revision 0 Fault Tree Analysis and Reliability Evaluation for Low Pressure Safety Injection (LPSI) Pump Trip at the Recirculation Actuation Signal (RAS)

DOCUMENT NUMBER 13-ES-A037 Q QAG NQR X PALO VERDE NUCLEAR GENERATING STATION DOCUMENT TITLE SHEET Title /

Description:

Fault Tree Analysis and Reliability Evaluation for Low Pressure Safety Injection (LPSI)Pump Trip at the Recirculation Actuation Signal (RAS)(DMWO 2938489, Revision 1)Applicability Determination:

This Engineering Study is to support DMWO 2938489 Revision 1 and clearly indicates so. The requirement for performing a Screening and/or Evaluation is defined in procedure 81DP-OEE1O, Plant Modifications.

No further 50.59 review is required per procedure 93DP-OLC17 R4, paragraph 2.1.6.Applicability Determination performed by W. Butler.V -Y -V V V Original Issue ' Butlerf Wesley ToIa rfJenny Hook, Thomas Abbate, Adrian Hartg, Allan A(Z18905) (z05640) G(Z0688) H(ZA$148)

W(Z43619)~ N/A (560 ,(Z ,,-. N/A N/A ( " A.P. Mierisch zo .., , 9/210 Document Electronically Available N Yes E- No+ 4 + + 4 4 1'Preparer (Exponent)

RE Checker Mech.PRA Elec.I&C Independent Verification Approver (l&C Design)RE NýO.REVISION DESCRIPTION 4 4 4- + + 4 Date Date Date Date Date Date Date Date Date U .0 4 0- +/- .0.CROSS DISCIPLINE REVIEW PV-E0076 Ver. 7 81TD-OEEIO i I Palo Verde Nuclear Generating Statio , Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 Page 2 of32 EXECUTIVE

SUMMARY

This report documents the work performed for the fault tree analysis and reliability evaluation of the Low Pressure Safety Injection (LPSI) pump trip circuit in response to the Recirculation Actuation Signal (RAS) at the Palo Verde Nuclear Generation Station (PVNGS). The purpose of the study was to determine the probability that LPSI Pumps A or B for Units 1, 2, and 3 would fail to shut down upon RAS.The failure rates for components that are necessary for the successful operation of the LPSI RAS pump trip control circuits are obtained from PVNGS Document Number 13-NS-B063 Revision 9, PVNGS, "At-Power PRA Study for Generic and Bayesian Updated Reliability Data Analysis", which is summarized in Table 3-1. The calculation of the probability of failure for each component upon activation of RAS is summarized in Table 3-2 and discussed in Section 3.0. The final fault tree models for LPSI Pump A and LPSI Pump B are shown in Figures 7 and 8 of Sections 4.1 and 4.2. The probabilities of the failure of the LPSI Pump A and LPSI Pump B Trip Circuits of Units 1, 2, and 3 at PVNGS upon activation of RAS are shown in Table 4-1 and were determined to be 1.17x10-3 (0.117%) and 1.2x10 3 (0.120%) for LPSI Pump A and B, respectively.

An uncertainty analysis was performed for the fault tree models developed.

The failure data fitted to a log-normal distribution is represented by mean value and error factor. The 95% values for Failure to trip LPSI Pump A and B upon RAS were determined to be 2.98x10-0 3 (0.298%)and 3.13x10-0 3 (0.313%) for LPSI Pump A and B, respectively.

". ý, 42 e Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 3 of 32 LIST OF EFFECTIVE PAGES Pages Revision All 0 -Original Issue

\ý i i Palo Verde Nuclear Generating Statior Engineering Study No. 13-ES-A037 Units 1, 2 & 3 _ _ _.. Revision 0 Page 4 of 32 TABLE OF CONTENTS Section Page EXECUTIVE

SUMMARY

.......................................................................................................

2 LIST OF EFFECTIVE PAGES ...................................................................................................

3 TABLE OF CONTENTS .........................................................................................................

4 L IST O F T A B L E S ..........................................................................................................................

5 L IST O F F IG U R E S ........................................................................................................................

5

1.0 INTRODUCTION

AND PURPOSE ..........................................................................

6 1.1 S cop e ................................................................................................................................

6 1.2 System Overview ..........................................................................................................

6 2.0 FAULT TREE ANALYSIS .......................................................................................

13 2 .1 A ssum ptions ...................................................................................................................

13 2.2 Top Level Failure Modes ............................................................................................

13 2.3 Lower Level Failure Modes Involving Failure of Breaker Trip Coil 52/TC to Energize/Transfer

.....................................................................................................

14 2.4 Fault Tree Models .....................................................................................................

15 3.0 RELIABILITY EVALUATION

..............................................................................

17 4.0 RESULTS AND CONCLUSIONS

.........................................................................

23 4.1 FTA Top Event: Failure to trip LPSI Pump A upon RAS .........................................

24 4.2 FTA Top Event: Failure to trip LPSI Pump B upon RAS ....................

25 4.3 Uncertainty Analysis .................................................................................................

27 4.4 Margin Evaluation

......................................................................................................

30

5.0 REFERENCES

..........................................................................................................

31 Palo Verde Nuclear Generating Statiolll Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 Page 5 of 32 LIST OF TABLES Table 3-1: Failure Rates from PVNGS Document 13-NS-B063 Rev 9 ..........................

20 Table 3-2: Component Failure Rate Summary .......................................................

21 Table 4-1: FTA Results (TOP Events) .................................................................

23 Table 4-2: Uncertainty Analysis Inputs ................................................................

27 Table 4-3: Uncertainty Analysis Inputs (95 % Computations)

.....................................

28 Table 4-4: Uncertainty Analysis Results .............................................................

30 LIST OF FIGURES Figure 1: Equivalent Circuit for LPSI RAS-Pump-A Trip .......................................................

7 Figure 2: Equivalent Circuit for LPSI RAS-Pump-B Trip .........................................................

8 Figure 3: Class 1E 4.16kV AC Circuit Breaker 752 ...................................................................

8 Figure 4: Equivalent Circuit for OR2 HFA Relay Terminals 13 & 14 .....................................

9 Figure 5: Equivalent Circuit for K104 Relay ............................................................................

10 Figure 6: Fault Tree Model Diagram ........................................................................................

16 Figure 7: LPSI RAS Pump A Trip Fault Tree Diagram .........................................................

24 Figure 8: LPSI RAS Pump B Trip Fault Tree Diagram .........................................................

25 Figure 9: Dominant Contributors (Shown for Pump B) ............................................

26 Figure 10: Monte Carlo Simulation Results ..........................................................

29 Palo Verde Nuclear Generating Statio., Engineering Study No. 13-ES-A037 Units 1,2 & 3 Revision 0 Page 6 of 32

1.0 INTRODUCTION

AND PURPOSE This report documents the work performed for the fault tree analysis and reliability evaluation of the Low Pressure Safety Injection pump trip circuit in response to the Recirculation Actuation Signal (RAS) at the Palo Verde Nuclear Generation Station (PVNGS).1.1 Scope The scope of work performed for this study includes the following tasks: 1.1.1 Review of the most recent version of all applicable PVNGS documents for the intended study of the LPSI pumps' response to the RAS.1.1.2 Based on the operation of only certain portions of the electrical system pertaining to the shutdown of the LPSI pumps in response to the RAS, a fault tree was developed for Fault Tree Analysis (FTA) that included all events or combination of events (including those in the operating environment) that could result in the failure mode in which one or more of the LPSI pumps fails to power down when the RAS is received.1.1.3 A review of PVNGS reliability data and additional reliability data was conducted for all electronic and electrical components related to the LPSI pumps and RAS in order to calculate the probabilities of various component failures.1.1.4 The calculated failure probabilities were utilized to determine the likelihood of each scenario identified that could possibly lead to the failure of the LPSI RAS pump-trip circuitry.

1.1.5 The constructed fault tree was then utilized to perform all appropriate Fault Tree Analyses and reliability evaluations of the LPSI RAS pump trip circuitry.

1.2 System Overview Palo Verde Nuclear Generating Station Units 1, 2, and 3 each have two Low Pressure Safety Injection pumps (LPSI pumps A and B). The LPSI pumps function as a part of the Emergency Core Cooling System (ECCS) to inject large quantities of borated water into the Reactor Coolant System in the event of a large pipe rupture. The pumps are normally in standby and automatically start upon receipt of the Safety Injection Actuation Signal (SIAS). During ECCS injection, the borated water source for the injection pumps is the Refueling Water Tank (RWT).When RWT inventory is reduced to approximately the 10% level, a Recirculation Actuation Signal (RAS) is initiated and will result in a shutdown of both running LPSI pumps if all components in the LPSI pump trip circuitry are operating satisfactorily.

The LPSI RAS pump trip circuits for pumps A and B are the same for each unit, with the only exception being that pump B has an additional control switch (Control Switch 3) and associated contacts (all CS-3 Contacts);

this is discussed in more detail later in this section. An equivalent circuit diagram for these circuits is shown in Figure 1, Figure 2, Figure 3, Figure 4, and Figure 5 as an aid to the reader in understanding this system overview without having to refer to the Palo Verde Nuclear Generating Stati: Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 7 of 32 complete control circuit diagrams (References 5.8 through 5.11). Each component referred to in the subsequent discussion has its location in the complete control circuit diagrams given in parentheses.

The following description of the trip circuitry applies to both of the LPSI RAS pump trip circuits, with the exception that the discussion of Control Switch 3 and its associated contacts (all CS-3 contacts) only applies to LPSI pump B for each of the three units.Reference 5.9 FU-2/35 Connection Points 3 & 4 FU-3/10 Connection Points 1 & 2 3 4 1 2 OR2 Contact Connection Points 5 and 6 V 125 Volt DC Supply 5t 6 M K104-1 Contact Connectio Points L and M 1 FU 2/35 Connection Points 1 & 2 2 10 ACB Trip Circuit 52/TC Breaker Trip 52 Auxiliary Drawout Switch 52 Auxiliary Drawout Switch'Coil Connection Contacts Connection Contacts Connection Points 1 and 2 Points 4 & 4C Points 2 & 2C 1 2 4C 4 2C R.........................................................................................................................................................

7 -R f r n e 5 1 Figure 1: Equivalent Circuit for LPSI RAS-Pump-A Trip Palo Verde Nuclear Generating Statiol Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 8 of 32 r-Reference 5.9 FU-2/35 Connection Points 3 & 4 FU-3/10 Connection Points 1 & 2 CS-3 Contact Connection Points 2 & 2T 3 4 1 2 125 Volt DC Supply 1 FU 2/35 Connection Points 1 & 2 2 ACB Trip Circuit 2T I I- 2 OR2 Contact Connection Points 5 and 6 K104-1 Contact Connection Points L and M CS-3 Contact Connection Points 4 & 4T 5 6 L M 4T I 52/TC Breaker Trip 52 Auxiliary Drawout Switch 52 Auxiliary Drawout Switch.4 10 Points 1 and 2 Points 4 & 4C Points 2 & 2C-~ 9 1 2 4C '4 2 2C Reference 5.10 Figure 2: Equivalent Circuit for LPSI RAS-Pump-B Trip Reference 5.8 752 1 3 4 8 9 10 11 12 13 14 15 16 CLOSING TRIP CKT CKT FOR INTERNALS SEE DWG 01 -E-PBO-006 Figure 3: Class 1E 4.16kV AC Circuit Breaker 752

ý i i , Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 9 of 32 P 9C ,eference 5.9 CS-2 Contact Connection Points 9 & 9C 1 CS-3 Contact Connection Points 1 & 1T 1T OR2 Contact Connection Points 1 and 22- T 9 H K104 12T 3 FU-3/10 Connection Points 3 & 4 4 3 FU-1/15 Connection Points 3 & 4 CS-3 Con-1 Contact Connection Points H & J Contact Connection Points 12 & 12T OR2 HFA Relay iection Points 13 & 14 4 13 125 Volt DC Supply 14 FU-1/15 Connection Points 1 & 2 1 2 Figure 4: Equivalent Circuit for OR2 HFA Relay Terminals 13 & 14

ýý W-', Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 10 of 32 PPS Channel 1 and 3 Contacts PPS Channel 2 and 4 Contacts Reference 5.11 TB 73 36V DC Power Supply Figure 5: Equivalent Circuit for K104 Relay The components of interest for determining the reliability of the LPSI RAS Pump B trip circuitry are connected in series as shown in Figure 2. If any of these components operate in a manner different than designed, then the associated LPSI pump will fail to trip upon initiation of the RAS signal. The series connected components of interest are FU-2/35 Connection Points 3 and 41 (Sheet 2, Zone 7H of Reference 5.9), FU-3/10 Connection Points 1 and 2 (Sheet 2, Zone 5H of Reference 5.9), CS-3 Contact Connection Points 2 and 2T (Sheet 2, Zone 5H of Reference 5.9), OR2 Contact Connection Points 5 and 6 (Sheet 2, Zone 5G of Reference 5.9), K104-1 Contact Connection Points L and M (Sheet 2, Zone 5G of Reference 5.9), CS-3 Contact Connection Points 4 and 4T (Sheet 2, Zone 5F of Reference 5.9), the ACB Trip Circuit (Sheet 2, Zone 5E of Reference 5.9; Consists of 52 Auxiliary Switch Drawout Contacts and 52/TC Breaker Trip Coil Connection Pointsl and 2), and FU-2/35 Connection Points 1 and 2 (Sheet 2, Zone 7E of Reference 5.9). The power supply for this trip circuit is the 125 Volt DC supply at the 4.16 kV Switchgear (Sheet 2, Zone 7F of Reference 5.9).1.2.1 FU-2/35 Connection Points 3 & 4, FU-3/10 Connection Points 1 & 2, and FU-2/35 Connection Points 1 & 2 During normal operations, these fuses are expected to maintain continuity as long as there have been no over current conditions introduced into the system that would cause the fuse elements to fail open. However, there is also a possibility these fuses could fail open during normal use.1 The term 'connection points' refers to a specific circuit location as identified in Reference 5.9.

Palo Verde Nuclear Generating Statio Engineering Study No. 13-ES-A037 Units 1,2 & 3 Revision 0 Page 11 of 32 1.2.2 CS-3 Contact Connection Points 2 and 2T and Connection Points 4 and 4T The position of Control Switch 3 determines whether its contacts are open or closed. The two positions for Control Switch 3 are "Local" or "Remote and Local". When Control Switch 3 is in the Local position, LPSI pump B can only be manually started/stopped using the local breaker control switch (Control Switch 1) at the 4.16 kV Switchgear.

When Control Switch 3 is in the Remote and Local position, LPSI pump B can be manually started/stopped using the local breaker control switch (Control Switch 1), or the control switch at the main control board (Control Switch 2). The normal and expected position for Control Switch 3 is Local and Remote as indicated on Sheet 2, Zone 5C of Reference 5.9. If Control Switch 3 is in the Local position, an alarm in the control room will be activated, warning the control room operators that Control Switch 3 is out of its normal position.

When Control Switch 3 is in the Remote and Local position, the CS-3 contacts are expected to be closed across connection points 2 and 2T and connection points 4 and 4T. When Control Switch 3 is in the Local position, both sets of contacts are expected to be open. There is also the possibility that the contacts could fail in a state different than the expected state.1.2.3 OR2 Contact Connection Points 5 and 6 The position of the OR2 Contact Connection Points 5 and 6 is determined by the OR2 HFA Relay Connection Points 13 and 14 (Sheet 2, Zone 2E of Reference 5.9). The equivalent circuit diagram that illustrates how OR2 HFA Relay Connection Points 13 and 14 can be energized is presented in Figure 4. When the OR2 HFA Relay is normally de-energized, its contacts are normally closed across contact connection Points 5 and 6. These OR2 contacts can prevent operation of the RAS trip circuit if they fail open with the HFA relay de-energized or if the HFA relay is energized.

There are two series connected paths that can result in the energizing of the OR2 HFA relay. Both paths include the K104-1 Contact Connection Points H and J (Sheet 2, Zone 2F of Reference 5.9) and CS-3 Contact Connection Points 12 and 12T (Sheet 2, Zone 2E of Reference 5.9). There are two ways for a series connection to be completed and energize the OR2 HFA relay. The first alternative involves the closing of CS-2 Contact Connection Points 9 and 9C (Sheet 2, Zone 2G of Reference 5.9), which when operating as expected corresponds to the momentary positioning of Control Switch 2 to the stop position.

The second alternative to complete the energizing of the OR2 HFA relay would include the closing of OR2 Contact Connection Points 1 and 2 (Sheet 2, Zone 2G of Reference 5.9). These contacts normally act as a lock-in feature since they close when the OR2 HFA relay is energized.

There is also a possibility that these contacts could fail closed with the OR2 HFA relay initially de-energized.

1.2.4 K104-1 Contact Connection Points L and M The position of K104-1 Contact Connection Points L and M are determined by the status of the K104 relay (Zone 5F of Reference 5.11.1) as shown in Figure 5. When the relay is energized, the contacts are expected to be open and when it is de-energized, the contacts are normally closed. The K104 relay is normally energized by two dual DC power supplies.

The first dual power supply is provided by TB73 (Zone 8F of Reference 5.11.1) and TB83 (Zone 8C of Reference 5.11.1). The second dual power supply is provided by TB53 (Zone 8F of Reference Palo Verde Nuclear Generating Statiop , Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 Page 12 of 32 5.11.2) and TB63 (Zone 8C of Reference 5.11.2). In order for the K104 relay to de-energize, both dual DC power supplies must be disconnected from the relay. The first dual power supply is disconnected when the Plant Protection System trip channel 1 or 3 contacts located in TB 75 (Zone 6F of Reference 5.11.1) or TB 85 (Zone 6F of Reference 5.11.1) open. The second dual power supply is disconnected when the Plant Protection System trip channel 2 or 4 contacts located in TB 55 (Zone 6F of Reference 5.11.2) or TB 65 (Zone 6F of Reference 5.11.2) open.The other relays associated with the initiation of the RAS signal are K405, K312 and K309 (Zone 4F of Reference 5.11.2). These relays are also powered by the same set of dual DC power supplies that energize the K104 relay. When trip paths (1 or 3) and (2 or 4) are tripped open, power is removed from relays K405, K312 and K309 and results in the initiation of the RAS signal. The tripping of paths (1 or 3) and (2 or 4) results in the loss of power to energize the K104 relay.1.2.5 ACB Trip Circuit The Air Circuit Breaker (ACB) trip circuit (Zone 7G of Reference 5.10) is shown in the bottom of Figure 1 and Figure 2. The 52 Auxiliary Drawout Switch Contacts Connection Points 2 and 2C and Connection Points 4 and 4C are normally closed contacts.

They open when Breaker 752 (Zone 8H of Reference 5.9) opens to remove the main 4.16 kV power supply from the LPSI pump. If they fail open prior to the opening of the breaker, the LPSI RAS trip circuit will fail to trip the pump upon initiation of a RAS signal. The 52/TC Breaker Trip Coil is a solenoid that will energize when all other series components of the RAS trip circuitry operate as expected with the initiation of the RAS signal to actuate the trip mechanism for Breaker 752, resulting in the trip of the LPSI pump.1.2.6 Breaker 752 Breaker 752 (Zone 8H of Reference 5.9) opens to remove the main 4.16 kV power supply from the LPSI pump. As can be seen in Figure 2 (Zone E3 of Reference 5.8), Breaker 752 includes an internal ACB trip circuit (Zone 7G of Reference 5.10) shown on the bottom of Figure 1 and Figure 2 which includes the 52 Auxiliary Drawout Switch Contacts Connection Points 2 and 2C and Connection Points 4 and 4C as well as the 52/TC Breaker Trip Coil.1.2.7 125 Volt DC Power Supply The connection of the 125 Volt DC Power Supply (Sheet 2, Zones 7H and 7E of Reference 5.9)to the LPSI RAS pump trip circuitry is illustrated in Figure 1. Since this is the power supply that shuts the LPSI Pump Breaker 752 upon initiation of SIAS and there is a relatively short amount of time between the initiation of SIAS and RAS, it is highly unlikely that this power supply would not be available upon initiation of RAS.

l~ i Palo Verde Nuclear Generating Statio) Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 Page 13 of 32 2.0 FAULT TREE ANALYSIS The fault trees used to estimate the reliability of LPSI Pumps A and B for all three units are identical, with the only difference being that Control Switch 3 and its associated CS-3 contacts are not present in the RAS trip circuitry for pump A. The fault tree development for LPSI Pump B will be discussed below in Sections 2.1 through 2.3 and illustrated in Section 2.4, with the understanding that the same logic will apply to LPSI Pump A with the exception of the discussion of Control Switch 3 and its associated contacts, since they are not present in the pump A control circuitry.

2.1 Assumptions In developing the fault tree for LPSI Pump B, the following assumptions were made: 2.1.1 The 125 Volt DC power supply is available for the pump trip circuitry upon initiation of the RAS signal. Based on the fact that this power supply is necessary for the 752 breaker closing circuitry upon initiation of the SIAS signal and the short amount of time between the SIAS signal and the RAS signal, it is highly unlikely that this power supply will become unavailable when the RAS signal is initiated.

2.1.2 The RAS signal is successfully initiated when the RWT tank level reaches the 10% level.With this assumption, it can also be assumed that the ESFAS (Engineered Safety Features Actuation System) K104 relay is de-energized since successful initiation of the RAS signal indicates that relays K104, K309, K405 and K312 (Reference 5.12) associated with the RAS signal in the ESFAS auxiliary relay cabinet have been de-energized.

2.1.3 Control Switches 1 and 2 will remain in the normal position between the initiations of the SIAS and RAS signals.2.1.4 Control switch 3 will remain in the remote and local position between the initiations of the SIAS and RAS signals. This assumption can be made since LPSI pump B would be unable to start upon initiation of the SIAS signal if control switch 3 were not in the remote and local position and the relatively short amount of time between initiations of the SIAS and RAS signals.2.1.5 Once LPSI Pump B trips successfully after initiation of the RAS signal, no attempt will be made to restart the pump.2.2 Top Level 'Failure Modes As discussed in the system overview section, the LPSI Pump B RAS trip circuit can be analyzed as a series circuit with 125 Volt DC Supply at the 4.16 kV Switchgear as the power supply in series with Fuse 2/35 Connection Points 3 and 4, Fuse 3/10 Connection Points 1 and 2, CS-3 Connection Points 2 and 2T Contact, OR2 Connection Points 5 and 6 Contact, K104-1 Connection Points L and M Contact, CS-3 Connection Points 4 and 4T Contact, Auxiliary Drawout Switch Connection Points 2 and 2C Contact 52, Auxiliary Drawout Switch Connection Points 4 and 4C Contact 52, Breaker Trip Coil 52/TC Connection Points 1 and 2, and Fuse 2/35 Palo Verde Nuclear Generating Statio r Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 Page 14 of 32 Connection Points 1 and 2. Upon successful initiation of a RAS signal, all of these series connected components should act as a continuous circuit to enable Breaker Trip Coil 52/TC to energize and open Breaker 752. The LPSI Pump B RAS trip circuitry will fail to successfully trip the pump upon initiation of a RAS signal if one of the following two conditions occurs: 2.2.1 Breaker Trip Coil 52/TC is successfully energized, but Breaker 752 fails to open.2.2.2 Breaker Trip Coil 52/TC is not energized.

If any of these series connected components act as open connections upon initiation of the RAS signal, Breaker Trip Coil 52/TC will not be energized.

The possible failure modes of the series connected components are discussed below.2.3 Lower Level Failure Modes Involving Failure of Breaker Trip Coil 52/TC to Energize/Transfer 2.3.1 Failure of Fuse 2/35 Connection Points 1 and 2, Fuse 2/35 Connection Points 3 and 4, and Fuse 3/10 Connection Points 1 and 2 The purpose of these components is to protect the pump trip circuitry from potential damage due to overcurrent conditions.

They are expected to remain continuous during normal operation of the pump control circuitry.

These fuses would cause failure of the RAS pump trip circuitry upon initiation of the RAS signal if they have failed open during normal wear or the presence of a previously undetected over current condition.

2.3.2 Failure of OR2 Connection Points 5 and 6 Contact This normally closed contact is associated with the OR2 HFA Relay Connection Points 13 and 14. When the RAS signal is initiated, the relay is expected to remain de-energized and the contact should remain normally closed. There are two modes of failure that can be associated with this contact. The first involves the relay remaining de-energized and the contact failing open. The second involves the relay, being energized, resulting in the contact opening. The second mode of failure and its associated fault tree component require further discussion.

There are two ways that the OR2 HFA relay could inadvertently energize.

The first requires the CS-3 Connection Points 12 and 12T Contact to be closed (expected due to Control Switch 3 position assumption), K104-1 Connection Points H and J Contact to be closed (expected due to presence of RAS signal), and OR2 Connection Points 1 and 2 Contacts to fail closed. The second requires the CS-3 Connection Points 12 and 12T Contact to be closed (expected due to Control Switch 3 position assumption), K104-1 Connection Points H and J Contact to be closed (expected due to presence of RAS signal), and CS-2 Connection Points 9 and 9C Contact to become closed. With the assumption that Control Switch 2 will remain in the normal position, this failure could occur only if the CS-2 Connection Points 9 and 9C Contact fails closed.

Palo Verde Nuclear Generating Engineering Study No. 13-ES-A037 Units 1,2 & 3 Revision 0 Page 15 of 32 2.3.3 Failure of CS-3 Connection Points 2 and 2T and CS-3 Connection Points 4 and 4T Contacts Based on the assumption that Control Switch 3 will remain in the remote and local position, these contacts are expected to be in the closed position upon initiation of the RAS signal. There is a possibility that these contacts could fail open during normal wear.2.3.4 Failure of K104-1 Connection Points L and M Contact The expected operation of this contact upon initiation of a RAS signal is for the contact to close when power is removed from the K104 relay. There are two modes of failure associated with this contact failing open upon initiation of a RAS signal. The first involves the K104 relay failing to transfer/dropout when power is removed from it. The second mode of failure is that the contacts fail open when the K104 relay successfully transfers/drops out.2.3.5 Failure of 52/TC Trip Coil Relay Connection Points 1 & 2 There are two modes of failure associated with this component.

The first mode involves the coil failing as an open connection due to deterioration or damage to it. The second mode involves the coil energizing successfully, but some failure occurring in the transfer mechanism between the relay and Breaker 752 that would prevent the breaker from opening.2.3.6 Failure of Auxiliary Drawout Switch 52 Connection Points 2 and 2C Contact and 4 and 4C Contact These contacts are normally closed contacts.

They open when Breaker 752 opens to remove the main 4.16 kV power supply from the LPSI pump. The failure mode for these components involve them failing open prior to the opening of the breaker, which would prevent the LPSI RAS trip circuit from tripping the pump upon initiation of a RAS signal.2.4 Fault Tree Models The Fault Tree Model constructed to incorporate the above listed failure scenarios are presented in Figure 6, which model the analyzed fault-tree TOP Event (failure of LPSI Pump to trip upon initiation of the RAS signal). The depicted FTA model is for Pump B. The model for Pump A is identical, with the exception that all of the failure modes associated with Control Switch 3 and its associated CS-3 contacts will be deleted.

Palo Verde Nuclear Generating Statio Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 16 of 32............R/2 Connection Points S-2 Connection1 Poits 9&9C R-2,Connection-PoinCs IA&2 cittsfitoremainclsect 3otat fil to remain o'e. ctacit fil sý.po eranqnpn'Cortact'5-'6 Fail.; 006n.;. .:Cntact M-C Fails CI6~ed Conitat1-

,2 Fails.Closed, Figure 6: Fault Tree Model Diagram

\i d Palo Verde Nuclear Generating Stati Engineering Study No. 13-ES-A037 Units 1,2 & 3 Revision 0 Ut 1Page 17 of 32 3.0 RELIABILITY EVALUATION The reliability rates utilized for all fault tree analyses in this study were obtained from PVNGS Document Number 13-NS-B063 Revision 9, PVNGS At-Power PRA Study for Generic and Bayesian Updated Reliability Data Analysis, Reference 5.1. These reliability rates are listed in Table 3-1: Failure Rates from PVNGS Document 13-NS-B063 Rev 9. The ID code determined by the above mentioned PVNGS study are also listed in Table 3-1 to aid the reader in following the calculations used to determine the probability of the failure modes given in the fault trees that were utilized for this study. These reliability rates were based on a thorough review of PVNGS operating experience, other plants' operating experience, and all relevant nuclear power plant component reliability studies. The probability of failure calculations for the component involved in the LPSI RAS pump trip circuitry are summarized in the discussion below and in Table 3- 1: Failure Rates from PVNGS Document 13-NS-B063 Rev 9.When converting the reliability rates in column 3 of Table 3-1 from failures per hour to failure probability upon initiation of a RAS signal, a few factors come into play. These factors are the component test interval (T), mission time (t), the failure rate determined for the component to change to the necessary position, and the failure rate determined for the component to remain in the necessary state. For a component that is required to change state the probability of failure upon initiation of a RAS signal or demand is: P (Failure Upon Initiation of RAS Signal)= (.5 x (Mean Failure Rate To Change To Desired State) x T)+ ((Mean Failure Rate To Remain In Desired State) x t)The first half of the equation accounts for the component switching to a failed state while in standby (elapsed time since the component was verified to be operating properly and when the RAS signal is initiated).

The second half of the equation accounts for failure of the component when the RAS signal creates a new demand that is placed on the contact that requires it to change state. Rule 6 of Reference 5.2 states "If the relay has been identified as having a "fail-to-energize" or "fail-to-deenergize" mode and has a long exposure time, greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> then do not model the contacts with the "fail-to-remain-open" and the "fail-to-remain-closed".

These failure modes are considered insignificant contributors to the total failure rate." During this study, in accordance with Rule 6 of Reference 5.2, the second half of the equation was disregarded when the test interval (T) was determined to be greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.If the component of concern is not required to change state upon initiation of a RAS signal, then the probability of failure upon initiation of a RAS signal only needs to account for the possibility of failure while the component is in standby and can be calculated as follows: P (Failure Upon Initiation of RAS Signal) =(.5 x (Mean Failure Rate To Remain In Desired State) x T)

Palo Verde Nuclear Generating Statlo Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 Page 18 of 32 Rule 14 of Reference 5.2 states "If there is indication in the Control Room, SEIS, or on the AO Rounds of the failure of a component do not include the component failure. Examples are fuses and power disconnect breakers for standby equipment.

These failures are not included in the analysis if their spurious open would cause loss of indication lights." During this study, in accordance with Rule 14 of Reference 5.2, standby failures of components whose failure would result in an indication in the control room were disregarded in the fault tree analysis conducted for this study.The component test intervals listed in Table 3-2 are based on the periodicity of maintenance procedures that verify proper operation of components associated with the LPSI RAS pump trip circuitry.

Every quarter each LPSI pump is shut down manually which verifies the proper operation of all components associated with the RAS pump trip circuitry with the exception of OR2 Connection Points 5 and 6 Contact, K104-1 Connection Points L and M Contact, and the K104 relay. Every 18 months procedure 36-ST-9SA03

/ 04 tests that Breaker 752 opens when the RAS signal is initiated, which verifies proper operation of the three components that are not verified when the pump is shut down manually.The following components found in Figure 1 and Figure 2 are not included in Table 3-2 for this analysis because: " Fuse 2/35 Connection Points 3&4: Failure of this fuse results in 762T Relay Connection Points LI and L2 (Zone 5E of Reference 5.9) becoming de-energized.

When the 762T Relay de-energizes, the 762T Contact Connection Points 5 and 3 (Zone 4D of Reference 5.9) opens. This 762T Contact is part of the Safety Equipment Inoperable Status (SEIS) circuitry and when it is open results in indication in the control room. Operations will know immediately if Fuse 2/35 fails open. Reference 5.2, Rule 14." Fuse 3/10 Connection Points 1&2: Failure of this fuse results in 762T Relay Connection Points Li and L2 (Zone 5E of Reference 5.9) becoming de-energized.

When the 762T Relay de-energizes, the 762T Contact Connection Points 5 and 3 (Zone 4D of Reference 5.9) opens. This 762T Contact is part of the Safety Equipment Inoperable Status (SEIS) circuitry and when it is open results in indication in the control room. Operations will know immediately if Fuse 3/10 fails open. Reference 5.2, Rule 14" Aux. Drawout Switch Contact 52 Connection Points 2&2C: This component is considered part of the 752 breaker and its contribution to breaker faults has already been incorporated.

Reference 5.2, Rule 13, which states "For Air Circuit Breakers (ACBs), the control circuit components located on the breakers themselves are considered part of the breakers and their contribution to breaker faults is already accounted for in the breaker local fault events in the fault trees."" Aux. Drawout Switch Contact 52 Connection Points 4&4C: This component is considered part of the 752 breaker and its contribution to breaker faults has already been incorporated.

Reference 5.2, Rule 13 i Palo Verde Nuclear Generating Statio Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 0 'Page 19 of 32" 52/TC Coil Relay: This component is considered part of the 752 breaker and its contribution to breaker faults has already been incorporated.

Reference 5.2, Rule 13" Fuse 2/35 Connection Points 1&2: Failure of this fuse results in 762T Relay Connection Points LI and L2 (Zone 5E of Reference 5.9) becoming de-energized.

When the 762T Relay de-energizes, the 762T Contact Connection Points 5 and 3 (Zone 4D of Reference 5.9) opens. This 762T Contact is part of the Safety Equipment Inoperable Status (SEIS) circuitry and when it is open results in indication in the control room. Operations will know immediately if Fuse 2/35 fails open. Reference 5.2, Rule 14 The following components found in Figure 4 are not included in Table 3-2 for this analysis because failure of these expected shut contacts, fuses and relay will not produce a failure of the system: " FU-1/15 Connection Points 3 and 4" FU-3/10 Connection Points 3 and 4" CS-3 Connection Points 1 & IT Contact" K104-1 Connection Points H & J Contact* CS-3 Connection Points 12 & 12T Contact" OR2 HFA Relay Connection Points 13 & 14" FU-1/15 Connection Points 1 and 2 In determining the failure rate value of the K104-1 Connection Point L&M Contact in Table 3-2 only failure mode RXAFT (ESFAS Actuation (K###) Relay Failure To Transfer) from Table 3-1 was utilized in accordance with Rule 8 of Reference 5.2 which states, "If the contacts are associated with protection relays and the analyst has identified those relays with a failure mode of improper operation the contacts are not counted because the failure data for protection relays is all inclusive." It was determined for this study that the RXAFT failure mode accounted for both the failure of the relay to transfer properly and its associated contacts to change state accordingly.

Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 20 of 32 Table 3- 1: Failure Rates from PVNGS Document 13-NS-B063 Rev 9 Circuit Breaker Failure To Open Mean -6.49E-4/D Error Factor -5 (CB-FO)ESFAS Failure To Mean -5.OE-8/H Actuation TransError Factor -9 (K###) Relay (RXAFT)Mean 1.OE-8/H Relay Contacts Failure To Remain Error Factor 3 Closed Or Open (CP-RC And CP-RO)

". i ! , Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 21 of 32 Table 3- 2: Component Failure Rate Summary K104-1 Connection Points L&M Contact Procedure 36-ST-9SA03/04 18 Months (13140 Hours)K104 Relay Fails To Transfer/Dropout When Power Is Removed Due To Standby Failure (RXAFT)0.5 x (RXAFT) x T 3.29E-04 Contact Fails To Remain OR2 18 Closed Due To Standby Connection Procedure Months Failure (CP-RC).36-ST- 0.5 x (CP-RC) x T 6.57E-05 Points 5&6 95A03/04 (13140 No demand is placed on this Contact Hours) component upon initiation of RAS.Contact Fails To Remain CS-3 3 Months Closed Due To Standby Connection Procedure 3 Failure (CP-RC).Points 2&2T 73ST-9SI11 (2160 No demand is placed on this 0.5 x (CP-RC) x T 1.08E-05 Contact component upon initiation of RAS.Contact Fails To Remain CS-3 3 Months Closed Due To Standby Connection Procedure 3 Failure (CP-RC).Points 4&4T 73ST-9SI11 (2160 No demand is placed on this Contact Hours) component upon initiation of RAS.Mechanical Procedure 3 Months Breaker Fails To Open Upon:Breaker 752 73ST-9SI11 Demand (CB-FO). CB-FO 6.49E-04 Hours)

Palo Verde Nuclear Generating Statio Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 22 of 32 Table 3- 2: Component Failure Rate Summary (continued)

CS-2 Connection Points 9&9C Contact Procedure 36-ST-9SA03/04 18 Months (13140 Hours)Contact Fails To Remain Open Due To Standby Failure (CP-RO).No demand is placed on this component upon initiation of RAS.0.5 x (CP-RO) x T 6.57E-05 Contact Fails To Remain OR2 Procedure 18 Open Due To Standby Connection Poeue Months Failure (CP-RO).36-ST- 0.5 x (CP-RO) x T 6.57E-05 Points 1&2 95A03/04 (13140 No demand is placed on this Contact Hours) component upon initiation I_ I I of RAS.

\ý I I Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 23 of 32 4.0 RESULTS AND CONCLUSIONS Fault Tree Models were constructed per the discussions outlined in Section 2. They were subsequently quantified per the reliability evaluations as outlined in Section 3. The FTA results are presented in this section.Two Fault Tree Models were quantified during this evaluation.

Figure 7 illustrates the fault tree model for LPSI Pump A and Figure 8 illustrates the fault tree model for LPSI Pump B.Both of these fault tree models (for LPSI Pump A and B) are identical (in structure) with the only exception being that all of the failure modes associated with Control Switch 3 and its associated CS-3 contacts apply only to LPSI Pump B. These Control Switch 3 and its associated CS-3 contacts failures do not apply to LPSI Pump A.The computed FTA results are summarized in Table 4-1. The FTA results for both LPSI pumps are similar. The differences between the two LPSI Pump configurations do not have a significant impact on the overall FTA result.Table 4- 1: FTA Results (TOP Events)LPSi Pump A I 1.171-3 LPSI Pump B 1.20E-3 The FTA details are presented in following sub-sections:

v kI , Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 24 of 32 4.1 FTA Top Event: Failure to trip LPSI Pump A upon RAS Figure 7 presents the details of the FTA analysis for Pump A.Figure 7: LPSI RAS Pump A Trip Fault Tree Diagram Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 25 of 32 tr 4.2 FTA Top Event: Failure to trip LPSI Pump B upon RAS Figure 8 presents the details of FTA analysis for Pump B.Figure 8: LPSI RAS Pump B Trip Fault Tree Diagram Palo Verde Nuclear Generating Statio: Units 1, 2 & 3 Engineering Study No. 1.3-ES-A037 Revision 0 Page 26 of 32 The dominant contributors for the LPSI Pump Failure to Trip (upon RAS) are presented in Figure 9.~0.000649 000 0.0003 0.0005ý0.00043 *~ 00O 0. 00iK 0.00021 0.0000 LI 1 a .Figure 9: Dominant Contributors (Shown for Pump B)As can be seen from Figure 9, the dominant contributor of the Pump Failure 2 to trip upon RAS (Breaker 752 does not open) is Breaker 752 sticks closed This single failure accounts for about 54% of the overall FTA result.LPSI Pump A dominant contributors are the same as LPSI Pump B.

)tk I Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 27 of 32 4.3 Uncertainty Analysis An uncertainty analysis was performed for the Fault Tree models developed.

The input failure data was fitted to a log-normal distribution is represented by mean value and error factor. The table below shows the various input distributions and associated 95% Upper bound values assumed for the input parameters.

Table 4-2: Uncertainty Analysis Inputs Circuit Breaker Failure To Open Mean -6.49E-4/D Error Factor -5 (CB-FO)6.49E-04 5 0.97838171 1 2.01E-03 ESFAS Failure To Mean -5.OE-8/H Actuation Error Factor -9 5.OOE-08 9 1.33569883 1.84E-07 (K###) Relay (RXAFT)Failure To Failue To Mean 1.0E-B/H Relay RemainMen1E8H Conac CedaOr Error Factor 3 1.OOE-08 3 0.66784942 2.40E-08 Contacts Closed Or (CP-RC And CP-RO)Open Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 28 of 32 Table 4-3: Uncertainty Analysis Inputs (95% Computations)

K104-1 Connection Points L &M Contact Procedure 36-ST-9SA03/04 18 Months (13140 Hours)0.5 x (RXAFT) x T 3.29E-04 1.21E-03 OR2 Connection Procedure 36-ST- 18 Months Pont 56 SA304 (114 Hur) 0.5 x (CP-RC) x T 6.57 E-05 1.58E-04 Points 5&6 9SA03/04 (13140 Hours)Contact CS-3 Connection Procedure 73ST- 3 Months (2160 Points 911 Hours) 0.5 x (CP-RC) x T 1.08E-05 1.99E-04 2&2T Contact CS-3 Connection Procedure 73ST- 3 Months (2160 Points 90.5 x (CP-RC) x T 1.08E-05 1.99E-04 4&4T Contact Mechanical Breaker Procedure 73ST- 3 Months (2160 CB-FO 6.49E-04 2.01E-03 729S11l Hours)752 CS-2 Connection ConectonProcedure 36-ST- 18 Months Points 9PA03/04 (13140 Hours) 0.5 x (CP-RO) x T 6.57E-05 1.58E-04 9&9C Contact OR2 Connection Procedure 36-ST- 18 Months 0.5 x (CPRO) x T 6.57E05 1.58E-04 Points 1&2 9SA03/04 (13140 Hours)Contact A Monte Carlo simulation was performed to get an estimate of the 95% value of the resultant FTA top event being modeled. The Monte Carlo Simulation results for Failure to trip LPSI Pump A and B upon RAS are presented below.

\, Ai..Palo Verde Nuclear Generating Static Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 29 of 32 r Forecast:

Pump A Frequency Chart 10,000 Trials.026 1-0 L 0..019.013.006 9,735 Displayed-259...............

194.2...............

129.5 .64.75 U 0 F 3.95E.4 1.17E-3 1.95E-3 2.72E -3 3.50E-3 Forecast PumpB FrequencyChart 1 ý00 Tials.019.014 0 L 9,750 Displa~ed 186...... 139.5-rI-11............

93............

46.5 A 0.009 4.78E-4 1.32E-3 216E-3 3.C0E-3 3.85E-3 Figure 10: Monte Carlo Simulation Results Palo Verde Nuclear Generating Statio: Units 1, 2 & 3 Engineering Study No. 13-ES-A037 Revision 0 Page 30 of 32 t, The table below lists the 95% values for failure to trip LPSI Pump A and B upon RAS Table 4- 4: Uncertainty Analysis Results~4Pu mp -F Pe rcje nt I~ e Vlue7 A 95.0% 2.98x10°3 B 95.0% 3.13x10-0 3 4.4 Margin Evaluation The purpose of this study is to determine the probability that LPSI Pumps A or B for Units 1, 2, and 3 would fail to shut down upon RAS and the concept of margin does not apply. (Procedure 81DP-4CC03, Section 3.22, Step 7, Part d)

Palo Verde Nuclear Generating Statio, Engineering Study No. 13-ES-A037 Units 1, 2 & 3 Revision 0 Page 31 of 32

5.0 REFERENCES

5.1 Document 13-NS-B063, PVNGS at-Power PRA Study for Generic and Bayesian Updated Reliability Data Analysis, Rev. 9, January 2009 5.2 Document 13-NS-B084, At-Power PRA Control Circuit Analysis, Rev. 6, January 2009 5.3 NUREG-0492, Fault Tree Handbook, W.E. Vesely, et al, Systems and Reliability Research Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission, January 1981.5.4 NUREG/CR-6823, Handbook of Parameter Estimation for Probabilistic Risk Assessment, C.L. Atwood, et al, Sandia National Laboratories, September 2003.5.5 NUREG/CR-6928, Industry-Average Performance for Components and Initiating Events at U.S. Commercial Nuclear Power Plants, S.A. Eide, et al, Idaho National Laboratory, February 2007.5.6 EGG-SSRE-8875, Generic Component Failure Data Base for Light Water and Liquid Sodium Reactor PRAs, Eide, et al, EG&G Idaho, Inc., February 1990.5.7 PVNGS UPDATED FSAR, Sections 5, 6, 7, and 9, Revisions 11, 12, & 14, June 2001, June 2003, & June 2007.5.8 5.8.1 Control Wiring Diagram, Safety Injection

& Shutdown CLG System, LP Safety Injection Pumps 1M-SIA-PO1 and 1M-SIB-P01, Drawing No 01-E-SIF-002, Rev. 2.5.8.2 Control Wiring Diagram, Safety Injection

& Shutdown CLG System, LP Safety Injection Pumps 2M-SIA-P01 and 2M-SIB-P01, Drawing No 02-E-SIF-002, Rev. 2.5.8.3 Control Wiring Diagram, Safety Injection

& Shutdown CLG System, LP Safety Injection Pumps 3M-SIA-P01 and 3M-SIB-P01, Drawing No 03-E-SIF-002, Rev. 2.5.9 5.9.1 Elementary Diagram, Safety Injection

& Shutdown CLG System, LP Safety Injection Pumps 1M-SIA-P01 and IM-SIB-PO1, Drawing No 01-E-SIB-002, Rev. 6.5.9.2 Elementary Diagram, Safety Injection

& Shutdown CLG System, LP safety Injection Pumps 2M-SIA-PO1 and 2M-SIB-PO1, Drawing No 02-E-SIB-002, Rev.5.5.9.3 Elementary Diagram, Safety Injection

& Shutdown CLG System, LP safety Injection Pumps 3M-SIA-PO1

& 3M-SIB-P01, Drawing No 03-E-SIB-002, Rev. 3.

Palo Verde Nuclear Generating Statior Engineering Study No. 13-ES-A037 Units 1,2 & 3 Revision 0 Page 32 of 32 5.10 5.10.1 Elementary Diagram, 4.16 kV Class 1E & non-lE Power System, ACB Internal Mechanism

& SWGR Space Heaters & Blower Circuits, Drawing No 01-E-PBB-006, Rev. 1.5.10.2 Elementary Diagram, 4.16 kV Class 1E & non-lE Power System, ACB Internal Mechanism

& SWGR Space Heaters & Blower Circuits, Drawing No 02-E-PBB-006, Rev. 1.5.10.3 Elementary Diagram, 4.16 kV Class 1E & non-lE Power System, ACB Internal Mechanism

& SWGR Space Heaters & Blower Circuits, Drawing No 03-E-PBB-006, Rev. 1.5.11 5.11.1 ESFAS Auxiliary Relay Cabinet, Electrical Schematics, Drawing No N001-13.06-161, Rev. 4.5.11.2 ESFAS Auxiliary Relay Cabinet, Electrical Schematics, Drawing No N001-13.06-162, Rev. 5.5.12 5.12.1 ESFAS Train A Actuated Devices, Drawing No 13-J-SAS-001, Rev. 16.5.12.2 ESFAS Train B Actuated Devices, Drawing No 13-J-SAS-002, Rev. 17.5.13 FW: Additional topics for pre-brief call at 2:30 p.m. today, Email Communication from Allan Hartwig, APS, dated August 4, 2009.5.14 RE: Follow up questions, Email Communication from Allan Hartwig, APS, dated August 6, 2009.