ML102010678

2010/07/16 Watts Bar 2 OL - 7-16-10__Response to NRC RAI on WBN U2 Fire Protection Program

ML102010678
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1 WBN2Public Resource From: Hamill, Carol L [clhamill@tva.gov]

Sent: Friday, July 16, 2010 12:14 PM To: Wiebe, Joel; Raghavan, Rags; Milano, Patrick; Campbell, Stephen Cc: Arent, Gordon; Crouch, William D; Knue ttel, Edward Terry; Boyd, Desiree L

Subject:

7-16-10__Response to NRC RAI on WBN U2 Fire Protection Program Attachments:

image001.png; 7-16-10__Response to NRC RAI on WB N U2 Fire Protection Program.pdf Please see attached letter that was submitted to NRC today.

Carol L. HamillLicensing/QualityAssuranceWBNUnit2Project,EQB1BWBN423 365 3177 423 3653833c c l l h h a a m m i i l l l l@@t t v v a a..g g o o v v Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 46 Mail Envelope Properties (25547F570B005144A141ECCA95DA1AB20CEDA0E3)

Subject:

7-16-10__Response to NRC RAI on WBN U2 Fire Protection Program Sent Date: 7/16/2010 12:14:02 PM Received Date: 7/16/2010 12:14:36 PM From: Hamill, Carol L Created By: clhamill@tva.gov Recipients: "Arent, Gordon" <garent@tva.gov>

Tracking Status: None "Crouch, William D" <wdcrouch@tva.gov> Tracking Status: None "Knuettel, Edward Terry" <etknuettel@tva.gov> Tracking Status: None "Boyd, Desiree L" <dlboyd@tva.gov> Tracking Status: None "Wiebe, Joel" <Joel.Wiebe@nrc.gov>

Tracking Status: None "Raghavan, Rags" <Rags.Raghavan@nrc.gov> Tracking Status: None "Milano, Patrick" <Patrick.Milano@nrc.gov> Tracking Status: None "Campbell, Stephen" <Stephen.Campbell@nrc.gov>

Tracking Status: None Post Office: TVACOCXVS2.main.tva.gov Files Size Date & Time MESSAGE 225 7/16/2010 12:14:36 PM image001.png 6804 7-16-10__Response to NRC RAI on WBN U2 Fire Protection Program.pdf 173832

Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: Recipients Received:

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 July 16, 2010 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop: OWFN P1-35 Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 10 CFR 50.4 NRC Docket No. 50-391

Subject:

WATTS BAR NUCLEAR PLANT (WBN) UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING FIRE PROTECTION PROGRAM (TAC NO. ME0853)

Reference:

NRC letter dated June 11, 2010, Watts Bar Nuclear Plant, Unit 2 - Request for Additional Information Regarding Fire Protection Program (TAC NO. ME0853 The purpose of this letter is to provide additional information as requested by NRC (Reference) in support of its review of the Fire Protection Program for WBN Unit 2. The following provides TVA responses to NRC requests for additional information:

NRC Request

The NRC staff requests that TVA submit the following information in order for the staff to complete its review of the fire protection system for WBN Unit 2:

1. WBN Fire Protection Reporta. The proposed revision of the WBN Unit 2 portion of the Fire Protection Report, with notation of all changes made after the last approval of the report by the NRC. b. The proposed revision of the common portions of the WBN Fire Protection Report, with notation of all changes made after the last approval of the report by the NRC. c. For each change that was previously approved by the NRC: (i) Provide detail concerning the approval, (ii) A reference to the approving document, and (iii) An excerpt documenting the approval. d. For each change that was not previously approved by the NRC: (i) Provide a sumary description of the evaluation, and (ii) TVAs justification for the acceptability of the change.

U.S. Nuclear Regulatory Commission Page 2 July 16, 2010 TVA Response

1. a. and b.The current Unit 1/2 Fire Protection Report addresses both units; however, it requires updating to address, among other things, the dual unit safe shutdown analysis, Unit 2 fire analysis volumes, and Unit 2 specific Operator Manual Actions (OMAs). The current version of the report will be updated by adding information to account for the current design of Unit 2. Portions of the report address programmatic aspects (e.g., fire brigades, fire watches, etc.) that are not affected by the operation of Unit 2. These parts will be submitted to the NRC by August 6, 2010. As discussed below, TVA is performing modifications related to fire protection. Additionally, TVA is issuing modifications to address other unrelated issues. Since there is a potential for these other modifications to impact the Fire Protection Report, TVA is conducting a fire protection review of the entire set of design changes issued for Unit 2. TVA is in the process of finalizing the Fire Protection Report to address both the fire protection-related modifications and the other modifications. This

review will be completed in December, 2010. TVA will submit the complete Unit 1/2 Fire Protection Report by December 17, 2010.

1.c.The Unit 1/2 Fire Protection Report, Revision 5, was approved by the NRC. NRC approval of the Fire Protection Report was documented in Supplemental Safety Evaluation Reports (SSERs) 18 and 19, Section 9.5.1 and Appendix FF. The report is currently at Revision 40. The changes between Revision 5 and 40 have been evaluated under the License Condition

and have not received explicit NRC approval.

1.d.The changes to the Fire Protection Report between Revision 5 and Revision 40 are not marked explicitly in the current revision; therefore, TVA will provide a separate markup, description, and justification of the changes made since NRC approved the report. This information will be provided by August 30, 2010. 2. Multiple Spurious ActuationsRegarding TVAs review of multiple spurious actuation scenarios that could affect post-fire safe shutdown, provide: a. A description of the method TVA used to systematically identify possible multiple spurious actuation scenarios that could affect safe shutdown, b. A description of each of the scenarios identified by the analysis, including how post-fire safe shutdown is ensured for each scenario.

U.S. Nuclear Regulatory Commission Page 3 July 16, 2010 TVA Response

2 .a.The WBN Fire Protection Report contains the programmatic requirements which apply to both Unit 1 and Unit 2 and the safe shutdown analysis results for Unit 1. The report will be enhanced to include the results of the Unit 2 safe shutdown analysis. Recently, WBN developed the Unit 1 Multiple Spurious Operation (MSO) list using the guidance of Regulatory Guide 1.189 Revision 2 and NEI-00-01 Revision 2. The WBN Unit 1 MSO scenario list was prepared using the expert panel review process described in NEI-00-01, Revision 2. The Unit 2 evaluation of MSOs will utilize the same methodology. Since WBN Unit 2 is essentially identical to WBN Unit 1 and very similar to its sister plant, Sequoyah Units 1 and 2, the plant specific list of MSO scenarios prepared for WBN Unit 1 is being used for developing the WBN Unit 2 MSO scenarios. Additionally the Sequoyah plant-specific MSO scenario list was reviewed for possible scenarios resulting from dual unit operation as opposed to the WBN Unit 1 single unit list. No additional scenarios were identified.

2.b.The Table in Enclosure 1 to this letter provides a description of the dual unit MSO scenarios identified by the above described analysis. TVA will provide a description of how safe shutdown is ensured for each scenario by August 20, 2010.

3. Operator Manual ActionsFor all OMAs needed to assure post-fire safe shutdown when redundant trains are in the same fire area outside of primary containment, provide: a. A description of the method that TVA used to evaluate OMAs, b. A description of, and a schedule for, completing plant modifications that are being performed to reduce OMAs, c. A list of OMAs that could not be resolved through modifications,

d. The plan and schedule for submitting a request for NRC approval of the OMAs that could not be resolved through modifications.

TVA Response

3.a.The WBN Unit 2 OMAs were developed starting with the Unit 1 post fire safe shutdown analysis and OMAs which were approved in NRC SSER 18. The OMAs were previously demonstrated for Unit 1 to be feasible and reliable. Unit 2 isperforming modifications to reduce the number of time critical (<60 minutes) OMAs. The Unit 2 OMAs will either be the same as Unit 1 or slightly different (i.e., similar) due to the modifications being performed to reduce the number/complexity of OMAs. For example, in Unit 1 the action may involve tripping a breaker or removing fuses, whereas in Unit 2 the action may be to operate a local U.S. Nuclear Regulatory Commission Page 4 July 16, 2010 switch. Either action will accomplish the same result and are thus similar. This is described as same/similar in the discussion below. The OMA fall into four categories: 1) Control Bay - The control building is an alternative shutdown area per Appendix R, III.G.3. OMAs the same/similar as Unit 1 will be utilized for Unit 2. 2) Hot Shutdown Greater Than 60 Minutes - OMAs that are the same/similar as Unit 1 will be utilized for Unit 2. 3) Hot Shutdown Less Than 60 Minutes - Modifications will be used to eliminate OMAs or reduce the number of fire zones which rely on the OMAs. Remaining OMAs will be the same/similar as Unit 1. See item 3c below for further information. 4) Cold Shutdown - OMAs the same/similar as Unit 1 will be utilized for Unit 2.

3.b.OMA reduction modifications are integrated into system modification packages and are thus not tracked separately from other modifications. The modifications for each system will be completed prior to system turnover. The types of modifications performed to reduce reliance on OMAs include: a. Cable rerouting to provide separation between redundant shutdown paths. b. Circuit modifications to prevent spurious actuation of components. c. Application of Electrical Raceway Fire Barrier Systems (ERFBS) to protect cables from fire damage.3.c.The baseline list of additional OMAs added for Unit 2 operation reflects the OMA reduction modifications described above but will be revised as described above to reflect the impact of other non-fire protection related modifications. The baseline list of OMAs is expected to require only very minor revisions due to the other non-fire protection related modifications.

TVA will provide the baseline list by August 6, 2010.

3.d.As discussed above, TVA will finalize the Fire Protection Report to address both the fire protection related modifications and the other modifications in December, 2010. TVA will submit the complete Fire Protection Report containing a listing of the final OMAs by analysis volume for NRC approval by December 17, 2010.

U.S. Nuclear Regulatory Commission Page 6 July 16, 2010 bcc (Enclosures): Lakshminarasimh Raghavan U.S. Nuclear Regulatory Commission MS 08H4A One White Flint North 11555 Rockville Pike

Rockville, Maryland 20852-2738 Stephen Campbell U.S. Nuclear Regulatory Commission

MS 08H4A One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 Patrick D. Milano, Senior Project Manager U.S. Nuclear Regulatory Commission MS 08H4 One White Flint North 11555 Rockville Pike

Rockville, Maryland 20852-2738 Loren R. Plisco, Deputy Regional Administrator for Construction U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 E1-1 ENCLOSURE 1 Table Watts Bar Nuclear Plant Dual Unit Multiple Spurious Operation Scenarios PWROG ScenarioNumber Safety Function / Scenario Scenario Description 1Primary Inventory Control -

Loss of all reactor coolant pump (RCP) seal cooling due to spurious closure of RCP seal injection header valve(s) concurrent with spurious isolation of component cooling water (CCW) to the thermal barrier heat exchangerSpurious isolation of RCPs seal injection header flow AND Spurious isolation of CCW to the thermal barrier heat exchanger 2Primary Inventory Control -

Loss of all RCP seal cooling due to charging flow diversion concurrent with spurious isolation of CCW to the thermal barrier heat exchangerSpurious opening of charging injection valve(s) causing diversion flow away from seals ANDSpurious isolation of CCW to the thermal barrier heat exchanger 3Primary Inventory Control -

Spurious re-initiation of RCP seal injection/thermal barrier cooling results in failure of the RCP seals due to thermal shockLoss of all seal cooling to RCP(s) (see Pressurizer Water Reactor Owners Group [PWROG] scenarios #1 and #2) ANDSpurious re-initiation of seal injection OR spurious re-initiation of CCW to the thermal barrier heat exchanger 4Primary Inventory Control - Catastrophic RCP Seal FailureLoss of all seal cooling to RCP(s) (see PWROG scenarios #1 and #2) ANDFire prevents tripping the RCPs ORspurious start of an RCP(s)

E1-2 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 5Primary Inventory Control -

Loss of all RCP seal cooling concurrent with spurious operation of the number 1 seal leakoff valve results in failure of RCP seal number 2Loss of all seal cooling to RCP(s) (see PWROG scenarios #1 and #2) ANDSpurious isolation of the number 1 seal leakoff valve 6Primary Inventory Control -

Failure to isolate / spurious opening of normal letdown active isolation valvesSpurious opening of (or failure to close) letdown isolation valve(s) AND Spurious opening of (or failure to close) letdown orifice valve(s) 7Primary Inventory Control - Normal letdown fails to isolate and inventory is lost to the pressurizer relief tankLetdown fails to isolate (see scenario #6) AND Spurious closure of downstream containment isolation valve 8Primary Inventory Control - Excess letdown fails to isolateSpurious opening of (or failure to close) multiple in-series excess letdown isolation valves 9Primary Inventory Control - Spurious valve operation results in loss of all high head reactor coolant system (RCS) makeup flow pathsSpurious isolation of RCP seal injection flow path AND / OR Spurious isolation of normal charging flow path AND / OR Spurious isolation of charging injection flow path 10 Primary Inventory Control - Spurious isolation of Makeup Tank (MUT)/Volume Control Tank (VCT) outlet valve(s) concurrent with spurious isolation of suction valves to the refueling water storage tank (RWST) results in damage to charging pump(s) when they are in normal operation (aligned to the MUT/VCT)Spurious isolation of suction from the MUT/VCT to running charging pump(s) when the charging pump(s) is aligned to the

VCTAND Spurious isolation of (or failure to open) suction from the RWST to the running charging pump(s)

E1-3 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 11 Primary Inventory Control - Spurious isolation of two parallel RWST suction valves results in failure of running charging pump(s) when the charging pump(s) is aligned to the RWSTInitial condition is charging pump running and drawing suction from the RWST. Spurious isolation of two parallel RWST outlet valves. 12 Primary Inventory Control - Spurious opening (or failure to close) of multiple series VCT outlet valvesSpurious opening (or failure to close) of multiple in-series VCT outlet valves 13 Primary Inventory Control -

Failure to isolate / spurious opening of normal letdown active isolation valves concurrent with spurious isolation of CCW to the letdown heat exchanger results in failure of charging pump(s)Letdown fails to isolate (see PWROG scenario #66) ANDSpurious isolation of CCW to the letdown heat exchanger 13a Charging Pump Runout Note: PWROG Rev. 1 (6/5/09) Scenario No. 14 and 52 (partial)Scenario causes charging pump runout and failure. Pump(s) must be running when RCS is at a depressurized condition.

Unintentional RCS depressurization could occur due to spurious opening of pressurizer power-operated relief valve(s)

(PORV), for example. Charging pump(s) can spuriously start if they are not already running. Scenario may also require failure of other components (e.g., charging flow control valve, etc.). 14 Primary Inventory Control - Spurious opening of Containment sump motor operated isolation valves (including residual heat removal [RHR] and CS suction valves) results in gravity draining of RWST/borated water storage tank (BWST) inventory to the Containment sump Note: PWROG Rev. 1 (6/5/09) Scenario No. 15Spurious opening of multiple in-series containment sump valves E1-4 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 15 Primary Inventory Control -

Spurious start of containment spray pump(s) concurrent with spurious opening of associated pump discharge valve results in transferring RWST/BWST inventory to the Containment sump Note: PWROG Rev. 1 (6/5/09) Scenario No. 16Spurious starting of containment spray pump(s) ANDSpurious opening of the associate pump discharge valve(s) AND/OR containment spray header valve(s) 15a Primary Inventory Control -

Spurious start of residual heat removal (RHR/shutdown cooling (SDC)/low pressure safety injection (LPSI) pump(s) concurrent with spurious opening of containment spray header valve(s) results in transferring RWST/BWST inventory to the Containment sump Note: PWROG Rev. 1 (6/5/09) Scenario No. 16Spurious starting of RHR/SDC/LPSI pump(s) ANDSpurious opening of the associate pump discharge valve(s) AND/ORContainment spray header valve(s) 16 Primary Inventory Control - Spurious opening of shutdown cooling suction line isolation valves (interfacing systems loss of coolant accident) Note: PWROG Rev. 1 (6/5/09) Scenario No. 17Spurious opening of multiple in-series RHR suction valves from the RCS 17 Primary Inventory Control - Spurious operation of pressurizer PORV(s)/PORV block valve(s) given that the associated PORV block valve is open Note: PWROG Rev. 1 (6/5/09) Scenario No. 18Spurious opening of multiple (two or three) pressurizer PORVs with corresponding block valves in their normal, open position 18 Primary Inventory Control - Spurious operation of pressurizer PORV(s) / PORV block valve(s) given that the associated PORV block valve is closed Note: PWROG Rev. 1 (6/5/09) Scenario No. 19Spurious opening of pressurizer PORV(s) ANDSpurious opening of pressurizer PORV block valve(s) after the block valve(s) has been closed E1-5 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 19 Primary Inventory Control - Spurious operation of reactor vessel head vent valvesNote: PWROG Rev. 1 (6/5/09) Scenario No. 20Spurious opening of multiple reactor head vent valves Note: PWROG Rev. 1 (6/5/09) Scenario No. 20 19a Primary Inventory Control - Spurious operation of hot leg high point vent valves Note: PWROG Rev. 1 (6/5/09) Scenario No. 20Spurious opening of hot leg high point vent valves (B&W plants) 20 Primary Inventory Control - Spurious operation of high head charging pumps challenges pressurizer safety valves Note: PWROG Rev. 1 (6/5/09) Scenario No. 21Spurious starting of additional high head charging pump(s) ANDSpurious opening of additional RCS makeup flow paths (i.e., charging injection) 21 Primary Inventory Control - Spurious opening of active valves in primary sample linesNote: PWROG Rev. 1 (6/5/09) Scenario No. 22Spurious opening of RCS sample valve(s) (i.e., hot leg, pressurizer liquid space, pressurizer steam space, etc.) ANDSpurious opening of inside containment isolation valve ANDSpurious opening of outside containment isolation valve ANDSpurious opening of downstream sample valve(s) 22 Decay Heat Removal - Spurious opening of atmospheric relief valve(s) upstream of the main steam isolation valves (MSIVs) Note: PWROG Rev. 1 (6/5/09) Scenario No. 23Spurious opening of atmospheric relief valve(s) (also sometimes called atmospheric dump valves) upstream of the MSIVs E1-6 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 23 Decay Heat Removal - Failure to close or spurious opening of MSIVs with concurrent failure of downstream steam relief valve(s) to close Note: PWROG Rev. 1 (6/5/09) Scenario No. 24MSIV(s) spuriously open OR fail to close ANDValve(s) for downstream steam load(s) (e.g., condenser steam dumps, turbine inlet valves, some atmospheric relief/dump valves, etc.) spuriously open OR fail to close 24 Decay Heat Removal - Failure to close or spurious opening of MSIVs bypass valves with concurrent failure of downstream steam relief valve(s) to close Note: PWROG Rev. 1 (6/5/09) Scenario No. 25MSIV(s) bypass valves spuriously open OR fail to close ANDValve(s) for downstream steam load(s) (e.g., condenser steam dumps, turbine inlet valves, some atmospheric relief/dump valves, etc.) spuriously open OR fail to close 25 Decay Heat Removal - Spurious operation of main steam header drain valve(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 26Spurious operation of main steam header drain valve(s) 26 Decay Heat Removal - Spurious operation/failure to operate of active steam supply valves fails the turbine-driven auxiliary (emergency) feedwater (AFW/EFW) pump Note: PWROG Rev. 1 (6/5/09) Scenario No. 27Spurious isolation of redundant steam supply valves to turbine-driven AFW pump 26a Decay Heat Removal - Spurious operation/failure to isolate steam to non-credited turbine-driven AFW pump Note: PWROG Rev. 1 (6/5/09) Scenario No. 26 (partial)27 Decay Heat Removal - Spurious closure of (AFW/EFW) pump active discharge

valve(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 28Spurious closure of multiple valves in AFW pump discharge flow path(s)

E1-7 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 28 Decay Heat Removal - Spurious operation/failure to operate of active steam supply valves fails the turbine-driven AFW/EFW concurrent with spurious isolation of the AFW/EFW discharge flow path Note: PWROG Rev. 1 (6/5/09) Scenario No. 29Spurious closure of steam supply valve(s) to turbine-driven AFW/EFW pump AND Spurious isolation of AFW/EFW pump discharge flow path(s) 29 Decay Heat Removal - AFW/EFW flow diversion to non-credited steam generator(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 30Combination of spurious valve operations in the AFW/EFW pump discharge flowpaths to the steam generators 30 Decay Heat Removal - AFW/EFW pump failure due to runout following spurious full opening of multiple AFW / EFW flow control and / or isolation valves Note: PWROG Rev. 1 (6/5/09) Scenario No. 31Spurious full opening of multiple EFW/AFW flow control and/or isolation valves 31 Decay Heat Removal - Spurious opening of condenser hotwell makeup control valve results in gravity draining condensate storage tank (CST) inventory to the hotwell Note: PWROG Rev. 1 (6/5/09) Scenario No. 32 Spurious opening of valves between the CST and condenser hotwell 32 Decay Heat Removal - Spurious pump(s) operation/failure to trip pump(s) results in steam generator(s) overfill/overcoolingNote: PWROG Rev. 1 (6/5/09) Scenario No. 33Scenario can occur due to various combinations of spurious AFW/EFW pump starts, spurious opening (or failure to close) of valves in AFW/EFW pump discharge flowpaths and spurious opening of main feedwater (MFW) isolation valves with MFW pump(s) running.

E1-8 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 33 Decay Heat Removal - Spurious operation of steam generator blowdown valves with subsequent loss of steam generator(s) inventory Note: PWROG Rev. 1 (6/5/09) Scenario No. 34Spurious opening of, or failure to close, multiple series steam generator blowdown valves34 Decay Heat Removal - Spurious opening of active valves in secondary sampling system(s) causes loss of steam generator(s) inventory Note: PWROG Rev. 1 (6/5/09) Scenario No. 35Spurious opening of steam generator sample valve(s) inside containment ANDSpurious opening of isolation valve(s) outside containment ANDSpurious opening of downstream sample valve(s) 35 Primary Pressure Control - Spurious operation of active normal pressurizer spray valves concurrent with inability to trip operating RCPs from the Control Room Note: PWROG Rev. 1 (6/5/09) Scenario No. 36Spurious opening of normal pressurizer spray valve(s) ANDInability to trip/failure to trip, or spurious operation of, RCP(s) ANDInoperability of pressurizer heater(s) 35a Primary Pressure Control - Spurious operation of auxiliary pressurizer spray valves with charging pumps in operations Note: PWROG Rev. 1 (6/5/09) Scenario No. 36Spurious opening of auxiliary pressurizer spray valve(s) ANDInoperability of pressurizer heater(s) 36 Primary Pressure Control - Spurious operation of multiple pressurizer heater banks Note: PWROG Rev. 1 (6/5/09) Scenario No. 37Spurious operation of multiple pressurizer heatersANDInoperability of pressurizer spray and auxiliary spray E1-9 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 37 Reactivity Control - Inadvertent injection of undiluted makeup water/inadvertent injection of makeup water with very low boron concentration Note: PWROG Rev. 1 (6/5/09) Scenario No. 38 Unborated water supply to the RCS can occur due to combinations of the following: - Spurious start of reactor makeup pump(s) (supplies unborated water to the VCT), - Spurious opening of valves between reactor makeup pump(s) and VCT, - Spurious full opening of the reactor makeup flow control valve, - Spurious closure of the boric acid flow control valve 38 Reactivity Control - Fire prevents reactor tripNote: PWROG Rev. 1 (6/5/09) Scenario No. 39Fire damage to the reactor protection system (RPS) may prevent reactor trip. For example, hot shorts may prevent tripping of the RPS motor generator sets. 39 Support Systems -

Spurious loss of CCW either as an entire system or to individual headers (including potential water hammer

events)Note: PWROG Rev. 1 (6/5/09) Scenario No. 40CCW flow can be isolated via several combinations of spurious valve closures.

Pertinent valves include: -CCW pump discharge valves, -CCW pump crosstie valves,

-CCW heat exchanger inlet valves, -CCW heat exchanger outlet valves, -CCW heat exchanger crosstie valves,

-etc. 40 Support Systems -

Spurious loss of CCW to individual critical loads (including potential water hammer events) Note: PWROG Rev. 1 (6/5/09) Scenario No. 41Spurious isolation of CCW cooling to individual redundant loads including lube oil coolers, RHR heat exchangers, etc.

E1-10 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 41 Support Systems - CCW flow diversion to non-credited loop(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 42Flow diversion can occur via several combinations of spurious valve operations in the CCW pump discharge and CCW loop crosstie flowpaths. Review piping and instrumentation diagrams (P&IDs) to identify relevant combinations. 42 Support Systems -

Spurious loss of safety-related service water (SW) either as an entire system or to individual headers (including potential water hammer events) Note: PWROG Rev. 1 (6/5/09) Scenario No. 43Safety-related SW (sometimes called "essential" SW) flow to credited loads can be isolated via several combinations of spurious valve closures.

Pertinent valves include: -SW pump discharge valves,

-SW pump crosstie valves, -SW heat exchanger inlet valves, -SW heat exchanger outlet valves,

-SW heat exchanger crosstie valves, -etc. Review P&IDs to identify relevant combinations. 43 Support Systems -

Spurious loss of safety-related SW to individual critical loads (including potential water hammer events) Note: PWROG Rev. 1 (6/5/09) Scenario No. 44Spurious isolation of safety-related SW cooling to redundant loads including CCW heat exchangers and emergency diesel generator (EDG) cooling 44 Support Systems -

Safety-related SW flow diversion to non-credited loops/loads Note: PWROG Rev. 1 (6/5/09) Scenario No. 45Flow diversion can occur via several combinations of spurious valve operations in the SW pump discharge and loop crosstie flowpaths. Review P&IDs to identify relevant combinations. 45 Support Systems -

Non-criticalcomponents inadvertently loaded onto credited EDGs Note: PWROG Rev. 1 (6/5/09) Scenario No. 46 Additional components load onto credited diesel generator E1-11 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 46 Support Systems - EDGs overloading Note: PWROG Rev. 1 (6/5/09) Scenario No. 47EDG overloading 47 Support Systems -

Spurious start of an EDG(s) with concurrent failure to provide required cooling Note: PWROG Rev. 1 (6/5/09) Scenario No. 48Fire spuriously starts an EDG(s) ANDMotor-operated valves (MOVs) providing required cooling water to the EDG(s) either fail to open or spuriously close 48 Support Systems - Non-synchronous paralleling of EDGs with on-site and off-site sources through spurious circuit breaker

operations Note: PWROG Rev. 1 (6/5/09) Scenario No. 49Non-synchronous paralleling of EDGs with on-site and off-site sources through spurious circuit breaker operations 49 Other Scenarios - Spurious isolation of various combinations of pump(s) suction valve(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 50 Note: Spurious operation of powered (i.e., MOVs, air-operated valves [AOVs], solenoid-operated valves [SOVs]) pump(s) suction valve(s) is most likely already included in the probabilistic risk assessment (PRA) logic and the safe shutdown cable analysis.50 Other Scenarios - Spurious isolation of various combinations of pump(s) discharge valve(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 51 Note: Spurious operation of powered (i.e., MOVs, AOVs, SOVs) pump(s) discharge valve(s) are most likely already included in the PRA logic and the safe shutdown cable analysis.51 Other Scenarios -

Pump failure due to spurious closure of discharge valve(s) concurrent with failure to open or spurious closure of required minimum recirculation flow path(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 51-E1-12 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 51a Other Scenarios -

Spurious start of high head charging pump(s) concurrent with closing of required minimum flow path valve(s) results in failure of the pump(s)High head charging pump(s) spuriously starts ANDRecirculation flow path valve(s) fails to open OR transfers closed 51b Other Scenarios -

Spurious start of high pressure safety injection pump(s) concurrent with closing of required minimum flow path valve(s) results in failure

of the pump(s)High pressure safety injection pump(s) spuriously starts ANDRecirculation flow path valve(s) fails to open OR transfers closed 51cOther Scenarios - Spurious operation of RHR shutdown cooling (SDC)/low pressure safety injection pump(s) concurrent with failure of associated minimum flow path valve(s) to open results in failure of the pump(s)RHR/SDC/low pressure safety injection pump(s) spuriously starts ANDRecirculation flow path valve(s) fails to open OR transfers closed 52 Other Scenarios - Loss of credited heating, ventilation and air conditioning (HVAC) to component(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 54Spurious isolation of HVAC to credited loads 53 Other Scenarios - Spurious MOV operation concurrent with fire-induced failure of torque and/or limit switches Note: PWROG Rev. 1 (6/5/09) Scenario No. 55Spurious MOV operation ANDWire-to-wire short(s) bypass torque and limit switches 54 Other Scenarios - Spurious engineered safeguards actuation signal (ESFAS) Note: PWROG Rev. 1 (6/5/09) Scenario No. 56Fire induced spurious ESFAS signal E1-13 PWROG ScenarioNumber Safety Function / Scenario Scenario Description 54a Other Scenarios -

Spurious start of makeup/injection pump(s) due to a spurious safety injection signal with concurrent spurious isolation of pump suction valve(s) Note: PWROG Rev. 1 (6/5/09) Scenario No. 56aSpurious safety injection signal AND Spurious isolation of makeup pump suction 54b Other Scenarios - Spurious isolation of RCP(s) thermal barrier cooling due to a spurious containment isolation signal with a concurrent isolation of seal injection Note: PWROG Rev. 1 (6/5/09) Scenario No. 56c (similar)Spurious containment isolation signal isolates CCW to the thermal barrier heat exchangers for all RCPs AND Spurious isolation of seal injection header flow 54cOther Scenarios - Spurious isolation of RCP(s) thermal barrier cooling due to a spurious containment isolation signal with a concurrent isolation of charging Note: PWROG Rev. 1 (6/5/09) Scenario No. 56cSpurious containment isolation signal isolates CCW to the thermal barrier heat exchangers for all RCPs AND Spurious opening of charging injection valve(s) causing insufficient flow to seals 54d Other Scenarios -

Spurious start of containment spray pump(s) due to a spurious containment spray signal Note: PWROG Rev. 1 (6/5/09) Scenario No. 56dSpurious high containment pressure on multiple channels causing spurious containment spray signal 54e Other Scenarios - Spurious opening of PORV(s) due to spurious high pressurizer pressure signals on multiple channels Note: PWROG Rev. 1 (6/5/09) Scenario No. 56eSpurious high pressurizer pressure on multiple channels causes high pressurizer pressure signal 54fOther Scenarios - Spurious Recirculation Actuation Signal (RAS) starting and aligning pumps to a dry containment sump.Added on 6/5/09 NEI 00-01 Rev 2 list (Item 56f)Spurious RAS starting and aligning pumps to a dry containment sump.

E2-1ENCLOSURE 2 List of Commitments 1. TVA is in the process of finalizing the Fire Protection Report to address both the fire protection related modifications and the other modifications. This review will be completed in December, 2010. TVA will submit the complete Unit 1/2 Fire Protection Report by December 17, 2010. 2. TVA will provide a separate markup, description, and justification of the changes made since NRC approved the report. This information will be provided by August 30, 2010. 3. Portions of the report address programmatic aspects (e.g., fire brigades, fire watches, etc.) that are not affected by the operation of Unit 2. These parts will be submitted to the NRC by August 6, 2010. 4. Table 1 provides a description of the dual unit MSO scenarios identified by the above described analysis. TVA will provide a description of how safe shutdown is ensured for each scenario by August 20, 2010. 5. The baseline list of OMAs is expected to require only very minor revisions due to the other non-fire protection related modifications. TVA will provide the baseline list by August 6, 2010.