RS-13-189, Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainly Recapture Power Uprate

Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainly Recapture Power Uprate

ML13186A178
Person / Time
Site:	Byron, Braidwood
Issue date:	07/05/2013
From:	Gullott D Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-13-189
Download: ML13186A178 (27)

Text

1 4300 Winfield Road W rrenville , IL 60555 Exelon Generation l~J 630657 2000 Office RS-13-189 10 CFR 50.90 July 5,2013 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk 4300 Winfield Road IAW-Washington, DC 20555-0001 Warrenville, IL 60555 Exe onBraidwood GenStation, eratUnits ion1 and 2 630 657 2000 Office Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 RS-13-189 Byron Station, Units 1 and 2 Facility Operating Ucense Nos. NPF-37 and NPF-66 10 CFR 50.90 NRC Docket Nos. STN 50-454 and STN 50-455 July 5, 2013

Subject:

Additional Information Supporting Request for Llcense Amendment Regarding Measurement Uncertainty Recapture Power Uprate U U. S. Nuclear Regulatory Commission ATTN: Documen

References:

1. t Control Desk Letter from Craig Lambert (Exelon Generation Company, LLC) to Washington, DC 20555-00 U. S. NRC, 01 II Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate," dated June 23, Braidwoo 2011 d Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77

2. Letter NRC Docketfrom Nicholas J. DiFrancesco (U. S. NRC) to M. J. Pacilio Nos. STN 50-456 and STN 50-457 (Exelon Generation Company, LLC), "Braidwood Station, Units 1 and Byron 2, and Byron Station, Units Nos. 1 and 2 - Acceptance Review of Station, Units 1 and 2 license Amendment Request (LAR) Re'. Measurement Uncertainty Facility Operating License Nos. NPF -37 and NPF-66 NRCRecapture Docket Nos. (MUR) Power Uprate (TAC Nos. ME6587, ME6588, STN 50-454 and STN 50-455 ME6589, and ME6590)," dated September 19, 2011 [ML112231574J

Subject:

Additiona

3. Letterl fromInformat J. S.ion Wiebe (U. S.gNRC)

Supportin forJ.License to M.

Request PacilioAmendm (Exelon ent Regardin g Measurem Generation Company, LLC), ~Byron ent Uncertain Station, ty Recaptur Unit Nos.

e Power Uprate 1 and 2, and Braidwood Station, Units 1 and 2 - Request for Additional Information

References:

1 . Letter from Craigof and Suspension Lambert Review(Exelon of License Amendment Generatio n CompanyRequest , LLC) fortoPower UUprate U. S. NRC, "Request

{TAC Nos. ME6587, for License ME6588, ME6589, Amendm and ME6590),"

ent Regardin g dated Measurem Decemberent Uncertain 6,2012 ty Recapture Power Uprate," dated June 23,

[ML12271A308]

2011

4. Letter from Kevin F. Borton (Exelon Generation Company, LLC) to U.

2. Letter S. NRC,from Nicholas J. DiFrance nSupplemental Information Supporting sco (U

• S. NRC)Request to M. J. Paciliofor License (Exelon Generati Amendment Regarding on Company , LLC), "Braidwo Measurement Uncertainty Recapture od Station, UnitsPower 1 and 2,Uprate and Byron

," dated Station, AugustUnits Nos. [RS 25, 2011 1 and11-137] [ML11255A332]

2 - Acceptan ce Review of License Amendment Request (LAR) Re-- Measurement Uncertainty Letter from Kevin F. Borton (Exelon Generation Company, LLC) to u.

5. Recaptur e (MUR) Power Uprate (TAC Nos.

S. NRC, "Additional Information SupportingME6587, ME6589, Request ME6588, for License and ME6590)," dated September 19, 2011Recapture

[ML112231574]

Amendment Regarding Measurement Uncertainty Power

3. Letter from Uprate," J. S.April dated Wiebe 27,(U. S. NRC) 2012 [RS12-o47]

to M. J.[ML 12121(Exelon Pacilio A496J Generation Company, LLC), `Byron Station, Unit Nos. 1 and 2, and Braidwood Station, Units 1 and 2 - Request for Additional Information and Suspension of Review of License Amendment Request for Power Uprate (TAC Nos

• ME6587, ME6588, ME6589, and ME6590)," dated December 6, 2012 [ML12271A308]

4. Letter from K

July 5,2013 U.S. Nuclear Regulatory Commission Page 2 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Facility Operating License Nos. NPF-72, NPF-77, NPF-37 and NPF-66 for Braidwood Station, Units 1 and 2, and Byron Station, Units 1 and 2, respectively. Specifically, the proposed changes revise the Operating License and Technical Specifications to implement an increase in rated thermal power of approximately 1 .63% based on increased feedwater flow measurement accuracy.

In Reference 2, the NRC staff indicated that the satisfactory disposition of the known nonconformance with turbine high-energy line break (HELB) would be required prior to implementation. In Reference 3, the NRC requested additional information (RAI) to support resolution of the HELB nonconformance to complete their detailed review of the July 5, 2013 power uprate application. The response to this RAI is provided in the Attachment to this U.S. Nuclear Regulatory Commission letter.

Page 2 As previously indicated in Reference 4, EGC has maintained the design basis for the Turbine In Reference Building HELB Generation 1, Exelon (Le., the qualification Company,ofLLC Class (EGC)1E electrical requested equipment an amendmentin the to identified auxiliary building Facility Operating rooms License Nos. are notNPF-77, NPF-72, adversely impacted NPF-37 andby a TB HELB)

NPF-66 and for Braidwood confirmed Station, that 1the Units andconclusions 2, and Byron stated in the Station, MUR Units Power 1 and Uprate LAR HELB 2, respectively. analyses Specifically, the remain valid.

proposed As stated changes reviseinthe Reference Operating 5, License no new and high Technical or moderate Specifications to were energy systems added implement as aan result of evaluation increase at MUR power of in rated thermal uprate condITions,1.63%

approximately and nobased new onhigh energy increased linefeedwater break or moderate energy line flow measurement crack locations were identified.

accuracy.

EGC In has reviewed Reference 2, the the NRCinformation supporting staff indicated that thea satisfactory finding of nodisposition significant of hazards the known consideration andwith nonconformance the turbine environmental consideration provided to high-energy line break (HELB) would be requiredthe NRC in Reference prior to1.

The additional information provided in this submittal does not implementation. In Reference 3, the NRC requested additional information (RAI) to affect the bases for concluding support that theofproposed resolution the HELB license amendmenttodoes nonconformance not involve complete a significant their detailed review hazards of the consideration.

power Furthermore, uprate application. Thethe additional response information to this providedininthe RAI is provided thisAttachment submittal does to this not affect the bases for concluding that neither an environmental impact statement nor letter.

an environmental assessment needs to be prepared in connection with the proposed As previously indicated in Reference 4, EGC has maintained the design basis for the amendment.

Turbine Building HELB (i.e., the qualification of Class 1 E electrical equipment in the There areauxiliary identified no regulatory buildingcommitments rooms are not contained adverselyin this letter. by a TB HELB) and impacted confirmed that the conclusions stated in the Should you have any questions concerning this letter, pleaseMUR Power Uprate LAR HELB contact Leslie analyses E. Holden at remain valid.

(630) 657-3316. As stated in Reference 5, no new high or moderate energy systems were added as a result of evaluation at MUR power uprate conditions, and no new high energy I declareline break under or moderate penalty of perjuryenergy that line crack locations the foregoing is truewere and identified.

correct. Executed on the th 5 day EGC ofreviewed has July 2013. the information supporting a finding of no significant hazards consideration and the environmental consideration provided to the NRC in Reference 1.

Respectfully, The additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. Furthermore, the additional information provided in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed David M. Gullott amendment.

Manager - licenSing There are no regulatory commitments contained in this letter.

Should you have any questions concerning this letter, please contact Leslie E. Holden at Attachment*.

(630) 657-3316. Response to Request for Additional Information (Non-Proprietary)

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 5"' day of July 2013.

Respectfully,

ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION NRC Letter dated December 6,2012

[M L 12271 A308]

(NON-PROPRIETARY)

ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION NRC Letter dated December 6, 2012

[ML12271A308]

(NON-PROPRIETARY)

Attachment - Response to Request for Additional Information (Non-Proprietary)

NRC Request

1. Provide a summary of the results of your extent-of-condition review related to the high energy line break (HELB) non-conformance.

Response

In 2011 and 2012, Exelon Generation Company (EGC) identified some design non-conformances associated with the Braidwood and Byron Turbine Building (TB) High Energy Une Break (HELB) analyses. The TB HELB analyses address HELBs in the T8 where safety related equipment in adjoining Auxiliary Building rooms could be impacted.

The TB HELB non-conformances were determined to be:

Attachment - Response to Request for Additional Information (Non-Proprietary)

• Inadequacy in the design of HELB barriers credited to maintain the designated environment, and NRC

• Request HELB structural loadings were not appropriately applied.

As a result of these non-conformances, the TB HELB mitigation strategy and associated

1. Provide a summary methodologies were revised, of the andresults of your were new analyses extent-of-condition performed to addressreviewtherelated to Auxiliary the high energy line break (HELB) non-conformance.

Building areas impacted by the TB HELBs. While the mitigation strategy changed and some different methodologies were applied, the overall success criterion was maintained

Response

such that the adjoining Auxiliary Building areas are maintained as mild environments following In 2011 and a TB HELB.

2012, ExelonTheGeneration response toCompanyRequest(EGC) 3 provides a discussion identified of thenon-some design mitigation strategy conformancesand methodologies, associated withas thewell as a d1scussion Braidwood and Byronof the plant Building Turbine modifications (TB) performed High to support Energy theBreak Line revised strategy.

(HELB) The development analyses. The TB HELB of these analysesnew TB HELB address HELBsanalyses in the TB included resolution of the identified inadequate HELB barriers and where safety related equipment in adjoining Auxiliary Building rooms could be impacted. inappropriate application of HELB structural loadings.

The TB HELB non-conformances were determined to be:

As a* result of these in Inadequacy non-conformances the design of HELB identified barrierswith the TB credited toHELB maintainanalyses, EGC has the designated performed extensive environment, and reviews to identify the extent-of-condition of these specific non-conformances within the other Braidwood and

• HELB structural loadings were not appropriately applied. Byron Station HELB analyses. This extent-ot-condition review initially involved identifying the plant areas that contained high As a result energy linesofand these non-conformances, required a HELB analysis. the TB HELB mitigation strategy and associated methodologies were revised, and new analyses were performed to address the Auxiliary To support Building the impacted areas extent-ot-condition by the TBreview, HELBs.EGC performed While a detailed the mitigation review strategy the HELB changed and analyses some of other different plant structures methodologies were containing high-energy applied, the lines that overall success could was criterion impact safety maintained related such that equipment.

the adjoining TheAuxiliary structures reviewed Building were:

areas are maintained as mild environments following a TB HELB.

• Auxiliary Building The response (other than to Request those 3 impacted areas provides aby discussion of the mitigation the TB HELBs),

strategy and methodologies, as well as a discussion of

• Main Steam Isolation Valve (MSIV) Room/Main Steam (MS) Tunnel, andthe plant modifications performed to support the revised

• Containment Building strategy. The development of these new TB HELB analyses included resolution of the identified inadequate HELB barriers and inappropriate The extent-of-condition application of HELB structuralreviewloadings.

determined that the HELB analyses supporting these structures have been performed consistent with the current Braidwood and Byron As a result of these non-conformances identified with the TB HELB analyses, EGC has licensing basis. Based on this extent-of-condttion review, EGC concluded that the performed extensive reviews to identify the extent-of-condition of these specific non-supporting HELB analyses for the above identified structures were not impacted by the conformances within the other Braidwood and Byron Station HELB analyses. This non-conformances identified in the TB HELB analyses. The details of this review are extent-of-condition review initially involved identifying the plant areas that contained high provided in the response to Request 2.

energy lines and required a HELB analysis.

To support the extent-of-condition review, EGC performed a detailed review the HELB analyses of other plant structures containing high-energy lines that could impact safety related equipment. The structures reviewed were:

• Auxiliary Building (other than those areas impacted by the TB HELBs),

• Main Steam Isolation Valve (MSIV) Room/Main Steam (MS) Tunnel, and

• Containment Building The extent-of-condition review determined that the HELB analyses supporting these structures have been performed consistent with the current Braidwood and Byron licensing basis. Based on this extent-of-condition review, EGC concluded that the supporting HELB analyses for the above identified structures were not impacted by the

Attachment - Response to Request for Additional Information (Non-Proprietary)

NRC Request

2. For those HELB analyses that were not affected by the non-conformance:

a. Identify the HELB area(s) that is the subject of the analysis.

Response

As stated in Response 1, the structures included in the HELB extent-of-condition review were the Auxiliary Building (other than those areas impacted by the TB HELBs), MSIV Room/MS Tunnel, and the Containment Buildlng. A summary of the review of these structures is provided below.

NRCAttachment Request - Response to Request for Additional Information (Non-Proprietary)

b. Provide confirmation that:

NRC Request

i. The analyses of record are in conformance with the licensing and

2. For those design HELB basis of thethat analyses plant. were not affected by the non-conformance:

Response

a. Identify the HELB area(s) that is the subject of the analysis.

The extent-of-condition review confirmed that the current HELB analyses of record

Response

(AORs) supporting the Auxiliary Building (other than those areas impacted by the TB HELBs),

As stated MSIV RoomlMS in Response Tunnel, 1, the and included structures the Containment Building in the HELB conform with thereview extent-of-condition current Braidwood and Byron Itcensing basis. This conclusion ls were the Auxiliary Building (other than those areas impacted by the TB HELBs), MSIV based on the application of the methodology summarized below.

Room/MS Tunnel, and the Containment Building. A summary of the review of these structures The initial is provided step involved below.

reviewing the Updated Final Safety Analysis Report (UFSAR),

NRC Safety Evaluatlon Reports (SEAs) and supplements, and referenced regulatory NRC guidance Request(Le., Standard Aeview Plans (SRPs) and Regulatory Guides (RGs)) to identify the b.documents Providethat define the that:

confirmation Braidwood and Byron HELB licensing basis requirements and associated NRC approved analysis methodologies. In parallel, a detai/ed search

i. The to was perlormed compile of analyses a comprehensive list of the Auxiliary record are in conformance Building, with the licensingMSIVand RoomlMS Tunnel, anddesign Containmentbasis of the plant.

Building AORs. A copy of each of the AORs was then obtained for further review.

Response

Using The the criteria identified extent-of-condition reviewin the current licensing confirmed basis each that the current HELB HELB AORofwas analyses reviewed record with the goal of identifying gaps where the applied methodologies (AORs) supporting the Auxiliary Building (other than those areas impacted by the TB were not consistent with the licensing HELBs), MSIV Room/MS basis. The specific Tunnel, anddesign considerations the Containment assessed Building conform forwith this the review current were jet impingement, pipe whip, flooding, and environmental Braidwood and Byron licensing basis. This conclusion Ls based on the application of the conditions.

methodology This review was summarized performedbelow. as follows:

The* Ifinitial the AOR step referenced involved reviewing or documentedthe Updated one of Final the Safety licensingAnalysis Report (UFSAR),

basis documents NRC Safety Evaluation previously identified,Reports the AOR(SERB) and supplements, was reviewed to determine andif referenced the licensing regulatory bases guidance document (i.e., was StandardappliedReview Plans (SRPs) appropriately . and Regulatory Guides (RGs)) to identify the* documents If the AOR that did not define the Braidwood reference one of the and Byron HELB licensing licensing basis basis documents requirements previously and identified, associatedthe NRC approved analysis methodologies. In parallel, AOR was reviewed to determine the basis for the inputs, assumption. a detailed search was andperformed methodology used. The inputs, assumptions, and methods were then Room/MS to compile a comprehensive list of the Auxiliary Building, MSIV reviewed Tunnel, and Containment to determine Building if the proper licensingAORs.

basesA copy of each ofwere requirements the AORs applied.was then obtained for further review.

The review using this approach determined that the HELB analyses reviewed for the Using Auxiliary theBuilding.

criteria identified Containmentin theBuilding, current licensing and MSIVbasis each HELB Rooms/MS AORwere Tunnels was found reviewed to with be inthe goal of identifying compliance gaps where with the current the applied licensing basis as methodologies approved by the were not consistent NRC. Therefore, with the licensing basis.found the non-conformances The specific in the TB design HELBconsiderations analysis do notassessed exist for for the this review structures were jet evaluated. impingement, pipe whip, flooding, and environmental conditions.

This review was performed as follows:

• If the AOR referenced or documented one 2 of the licensing basis documents previously identified, the AOR was reviewed to determine if the licensing bases document was applied appropriately.

• If the AOR did not reference one of the licensing basis documents previously

Attachment - Response to Request for Additional Information (Non-Proprietary)

NRC Request ii. The analyses of record either have been previously approved by the NRC or were conducted using methods or processes that were previously approved by the NRC.

Response

The references and methodologies identified in the HELB AORs were compared to the methods or processes previously approved by the NRC. The review concluded that the identified references and methodologies in HELB AORs were either in compliance with methods or processes previously approved by the NRC, or the actual Byron/Braidwood HELB analyses had been previously approved by the NRC.

Attachment - Response to Request for Additional Information (Non-Proprietary)

NRC Request NRC Request

c. Confirm that the equipment environmental qualification parameters ii. The analyses continue of record either have been previously approved by the to be bounded.

NRC or were conducted using methods or processes that were Response previously approved by the NRC.

EGC has concluded that the Auxiliary Building, MSIV RoomsiMS Tunnels, and

Response

Containment Building HELB AORs are consistent with the current licensing basis and The references were performedand methodologies in accordance withidentified approvedinmethodologies, the HELB AORs andwere do notcompared containtothe the methods or processes previously approved non-conformances identified in the TB HELBbyanalyses. the NRC.Therefore, The review theconcluded that the envkonmental identified references qualification parameters and previously methodologies in HELB evaluated have AORs were either not changed andinthecompliance conclusionswithof methods or processes previously approved by the NRC, or the actual the MUR Power Uprate submittal(s) (References A-1, A-2, A-3, and A-4) related to the Byron/Braidwood HELB analyses equipment had been previously environmental approved qualifications by from resulting the NRC.

a postulated HELB continue to be valid.

NRC Note, Request during the course of this extent-of-condition review, some gaps or document deficiencies were identified. These gaps and deficiencies, summarized below, have beenc. entered Confirm intothat the the equipment Braidwood and environmental Byron Correctivequalification Action Program parameters for evaluation continue to be bounded.

and disposition. These deficiencies do not impact the extent-of-condition conclusions or

Response

the conclusions of the MUR analyses related to equipment environmental qualifications.

EGC* hasHigh concluded EnergythatLeakage Crack evaluations the Auxiliary Building, MSIVwere Rooms/MS not performed duringand Tunnels, original plant Containment designBuilding HELB AORs arebetween due to inconsistencies consistentthewith design and licensing basis the current licensing basis and were performed in accordance requirements. Corrective Actions with approved(Byron IR 1311582 and methodologies, and Braidwood do not containIR the non-conformance 1312365) sare identified in the TB HELB analyses. Therefore, the environmental in prog ress to add ress this condition. Con sid eri ng that the general qualification designparameters approach previously for HELB was based have evaluated on analyzing the plant not changed in terms and the of conclusions of the MUR Power Uprate submittal(s) compartments/hazard zones(References and the effectsA-1,ofA-2, HELB in and A-3, eachA-4) related to the equipment environmental qualifications compartmenVzones resulting evaluated were conservatively by worstHELB from a postulated case continue scenario toor be valid . total loss of the equipment in the particular compartmentihazard zone, the less severe impact of a high energy leakage crack generally is expected to be Note, during the course of this extent-of-condition review, some gaps or document bounded by the HELB considerations.

deficiencies were identified. These gaps and deficiencies, summarized below, have been* entered Design into the Braidwood analysis supportingandUFSAR Byron Corrective statementsAction Program regard'lf1g the insignificant for evaluation and disposition. These effects environmental deficiencies from adopostulated not impactChemical the extent-of-conditio Volume and Control Systemor n conclusions the conclusions of the MUR analyses (CVCS) letdown line break in related to equipment the Auxiliary Buildingenvironmental Containment Piping qualifications.

Penetration area and an Auxiliary Steam (AS) line break in the Auxiliary Building

• High Energy Leakage Crack evaluations were not performed during original plant General Area (401' elevation) could not be located. Actions are in place to design due to inconsistencies between the design and licensing basis requirements. Corrective Actions (Byron IR 1311582 and Braidwood IR IR develop these analyses (CVCS Issue, Byron IR 1531404, and Braidwood 1532142), (AS Issue, Byron IR 1532225 and Braidwood IR 1532130). There is 1312365) are in progress to address this condition. Considering that the general no evidence that the UFSAR qualitative disposition is invalid.

design approach for HELB was based on analyzing the plant in terms of compartments/hazard zones and the effects 3 of HELB in each compartment/zones were conservatively evaluated by worst case scenario or total loss of the equipment in the particular compartment/hazard zone, the less severe impact of a high energy leakage crack generally is expected to be bounded by the HELB considerations.

Attachment - Response to Request for Additional Information (Non-Proprietary)

• Design analysis for MSIV Room (also referred to as the MS Safety Valve Room) pressurization is being revised to apply a refined mass and energy release, more accurately reflect the configuration of the MSIV rooms and vent paths, and to use state of the art software. This update is in progress to address a condition indentified prior to the HELB issue. Actions are in place to track completion (Byron IR 1531420, Braidwood IR 792215).

Attachment - Response to Request for Additional Information (Non-Proprietary)

• Design analysis for MSIV Room (also referred to as the MS Safety Valve Room) pressurization is being revised to apply a refined mass and energy release, more accurately reflect the configuration of the MSIV rooms and vent paths, and to use state of the art software. This update is in progress to address a condition indentified prior to the HELB issue. Actions are in place to track completion (Byron IR 1531420, Braidwood IR 792215).

4

Attachment - Response to Request for Additional Information (Non-Proprietary)

NRC Reauest

3. For those HELB area(s) that were affected by the non-conformance:

Response

B/B StaflOns are implementing a revised HELB mitigation strategy to better protect against the consequences of a HELB in the Turbine Building. In summary this strategy involves:

• Keeping the TB HELB environment out of the adjacent rooms/areas with safety-related equipment.

Auxiliary Building (AB) rooms/areas by installing single-failure proof HELB dampers in the ventilation openings and HELB-resistant doors to the rooms.

Attachment - Response to Request for Additional Information (Non-Proprietary)

Main Control Room by installing a HELB sensor to prevent make-up air being taken from TB following HELB.

NRC Request

• Keeping the adjacent AB rooms within their design basis temperature limits following

3. aForTBthose HELBHELB by: area(s) that were affected by the non-conformance:

Response Automatically restart the AB room ventilation fans, and B/B- Stations Configuring the fire dampers are implementing to close a revised HELB only in the event mitigation of a to strategy firebetter (maintains protect ventilation exhaust path following HELB).

against the consequences of a HELB in the Turbine Building. In summary this strategy involves:

• Performing a new TB HELB analysis to better predict environmental conditions

• following Keeping the theTB HELB.

HELB environment out of the adjacent rooms/areas with safety-related equipment.IC thermal-hydraulic event analysis Use of GOTH Maximized

- Auxiliary enthalpy Building (AB)release rooms/areas by installing single-failure proof HELB dampers Considered in the ventilation larger spectrum openings and HELB-resistant doors to the rooms.

of line breaks

- Main Control Added Room bytoinstalling rooms/areas the analysisa HELB sensor to prevent make-up air being taken from TB following HELB.

Included new HELB modifications (see Response 3.i)

• Keeping the adjacent

• HELB dampers ABandroomsdoorswithin their design basis temperature limits following a TB* HELB by: restoration of room cooling Automatic

• Divisionalrestart

- Automatically block thewallABmodifications room ventilation fans, and Additional details on

- Configuring thethefirerevised dampers TBtoHELB closestrategy only in theare event provided of ainfire response 3.1. The (maintains ventilation new analysis and exhaust path following modifications that supportHELB).

the revised HELB mitigation strategy will be reviewed and implemented in accordance with 10 CFR 50.59.

• Performing a new TB HELB analysis to better predict environmental conditions Thefollowing Turbine Building the HELB. also contains safety-related equipment such as limit switches on the -turbine Use ofthrottle GOTHvalves, pressure switches IC thermal-hydraulic eventon analysis the turbine electro-hydraulic control system, and pressure transmitters

- Maximized enthalpy release that sense turbine impulse pressure. These components provide inputs into the Solid State Protection System. In addition, there are

- Considered solenoids larger spectrum which actuate of line breaks to initiate feedwater isolation signals. These components,

- Added however, arerooms/areas not required to to establish the analysis and maintain a safe shutdown condition following a HELB and are new

- Included not impacted by the non-conformance.

HELB modifications (see Response 3.i)

• HELB dampers and doors NRC Request

• Automatic restoration of room cooling

a. *Identify Divisional block area(s) the HELB wall modifications that is the subject of the analysis.

Additional Response details on the revised TB HELB strategy are provided in response 3.f. The new analysis and modifications that support the revised HELB mitigation strategy will be The new analysis reviewed and revised and implemented TB HELB mitigation in accordance with 10 CFR strategy focuses on the impact of a 50.59.

HE LB originating on th e 40 1', 426', and 451' Elevations in the TB on th e following The Turbine Building rooms/areas of concern also contains within safety-related the Auxiliary equipment such as limit switches on Building:

the turbine throttle valves, pressure switches on the turbine electro-hydraulic control system, and pressure transmitters that sense5 turbine impulse pressure. These components provide inputs into the Solid State Protection System. In addition, there are solenoids which actuate to initiate feedwater isolation signals. These components, however, are not required to establish and maintain a safe shutdown condition following a HELB and are not impacted by the non-conformance

Attachment - Response to Request for Additional Information (Non-Proprietary) 373'-6" Elevation:

- Diesel Oil Storage Tank Rooms (DOST) 1A, 1 B, 2A, and 2B1 401' Elevation:

Emergency Diesel Generator (EDG) Rooms 1A, 1B, 2A, and 2B

- Braidwood Only - Auxiliary Buildtlg General Area (in the vicinity of the TB/AB pressure balancing damper) 1 415' Elevation:

- Unit 1 and Unit 2 Electrical Pipe Tunnels 1 426' Elevation:

-Attachment Division 11, - Response 12,21, andto Request for Additional 22 Englneered SafeguardsInformation Feature (Non-Proprietary)

(ESF) Switchgear Rooms 439' Elevation:

373'-6" Elevation:

- Diesel Oil12 Division and 22Tank Storage Lower Cable Rooms Spreading (DOST) 1 A, 1Rooms B, 2A, 1and 2131 451' Elevation:

401' Elevation:

- Division Emergency 11, Diesel 12,21,Generator and 22 Miscellaneous (EDG) Rooms Electrical 1A, 1B, Equipment 2A, and 2BRooms (MEER)

- Braidwood Only - Auxiliary Building General Area (in theSwitchgear Unit 1 and Unlt 2 Non-ESF Switchgear Rooms (6.9 KV Rooms) vicinity of the TB/AB 1 pressure balancing damper)'

415' NRCElevation:

Request

- Unit

b. 1 and Identify theUnit 2 Electrical important Pipe Tunnels' analysis inputs and assumptions (including their values), and explicitly identify those that changed as a result of the 426' Elevation:

resolution

- Division 11,of12, the21,nonconformance.

and 22 Engineered Safeguards Feature (ESF) Switchgear Response Rooms 439' A new Elevation.,,

analysis was performed to model and evaluate the plant response to a TB HELB and -theDivision resulting12environmental and 22 Lowerparameters for the Rooms' Cable Spreading areas listed above using the GOTHIC computer program. This analysis considers and bounds MUR uprate 451' Elevation:

condrtions.

- Division 11, 12, 21, and 22 Miscellaneous Electrical Equipment Rooms (MEER)

The -new Unitanalysis 1 and includes the following Unit 2 Non-ESF key changes Switchgear Rooms in inputs (6.9 and assumptions KV Switchgear Rooms) from the previous analyses of record:

• Instead of four separate KITIY models, as used in the existing analyses of record, NRC aRequest single GOTHIC model has been developed that combines the MEER, ESF Switchgear

b. Identify the Room, EDG Room important TB Elevations and inputs analysis 369', 401', (including and assumptions 426', and 451'.

theirThe values), and explicitly identify those that changed as a result of the the single GOTHIC model also integrates the initial response to the HELB and subsequent resolutionroom of theheat-up. The GOTHIC model has been expanded to include the nonconformance.

identified Turbine Building Elevations and flow paths to more accurately model Responsepressurization throughout the Turbine Building following a HELB. The GOTHIC A newmodelanalysishaswas alsoperformed been expanded to modelto include both ESF and evaluate divisions the plant of Auxiliary response to a TBBuilding HELB and the rooms and other resulting Auxiliary Building environmental parametersareas foras thelisted areasinlisted the response above usingto question the 3.a.

The integrated nature of the GOTHI C model permits GOTHIC computer program. This analysis considers and bounds MUR uprate determining differential pressures across the walls separating the rooms and areas such that the structural conditions.

impact from a HELB may be evaluated.

The new analysis includes the following key changes in inputs and assumptions from the previous analyses of record n Instead of four separate KITTY models, as used in the existing analyses of record, 1 Thesea single GOTHIC rooms/areas were model has been not previously developed addressed in the TB that combines HELB analysis the MEER, but have beenESF included in new TB HELBRoom, the Switchgear analysis.EDG Room and TB Elevations 369', 401', 426', and 451'. The single GOTHIC model also integrates the 6 initial response to the HELB and the subsequent room heat-up. The GOTHIC model has been expanded to include the identified Turbine Building Elevations and flow paths to more accurately model pressurization throughout the Turbine Building following a HELB. The GOTHIC

Attachment - Response to Request for Additional Information (Non-Proprietary)

• The new analysis incorporates the modifications discussed in the response to question 3.i that implement the revised TB HELB mitigation strategy.

• Consideration of a broader spectrum of breaks (size and location) for conservatism. This includes small breaks that could result in an extended pressurization of the Turbine Building.

• For main steam line breaks, the use of transient mass and energy releases that maximize superheat, instead of using constant mass and energy releases based on initial conditions.

• For liquid line breaks, the use of mass and energy releases that maximize enthalpy, instead of minimize enthalpy. Maximizing enthalpy is conservative Attachment - Response steam because it maximizes to Request qualityforatAdditional atmospheric Information pressure,(Non-Proprietary) which in turn maximizes the liquid break mass flow that flashes to steam in the Turbine Building.

• • Control The newvolume analysis and flowpath modeling incorporates improvements the modifications were in discussed incorporated the response such to that the computer question model 3.i that in the new implement analysis the revised TBprovides a very accurate HELB mitigation strategy.representation of the plant physical layout, and therefore provides a more accurate prediction of the

• Consideration plant responseof toaabroader TB HELB spectrum event. of breaks (size and location) for conservatism. This includes small breaks that could result in an extended

• Initial room temperatures pressurization of the Turbine andBuilding.

heat loads have been conservatively applied to the additional rooms evaluated in the new analysis (as indicated in response 3.a).

For main steam line breaks, the use of transient mass and energy releases that NRC Request superheat, instead of using constant mass and energy releases based maximize on initial conditions.

c. Confirm that the equipment environmental qualification parameters

• For liquid line continue breaks, to be bounded. the use of mass and energy releases that maximize enthalpy, instead of minimize enthalpy. Maximizing enthalpy is conservative Responsebecause it maximizes steam quality at atmospheric pressure, which in turn The new maximizes analysisthe liquid break that demonstrates massthe flow that flashes to environmental steam in the parameters Turbine within theseBuilding.

zones will

• remain mild. The new analysis credits the modifications Control volume and flowpath modeling improvements were incorporated such that installed (see response to 3.i) tothe support the revised computer model in TBthe HELBnewmitigation strategy aand analysis provides very results accuratein lower peak representation of temperatures and much shorter durations than determined in the plant physical layout, and therefore provides a more accurate prediction of the the previous analyses.

plant response As discussed furthertoinaresponse TB HELB3.h, event.

the new analysis results in transient temperature nprofiles that room Initial are consistent temperatures with andthe requirements heat loads have of Technical Requirements been conservatively Manual applied to the (TRM)additional 3.7.d for theroomsaffected rooms/areas.

evaluated in the new Temperatures analysis (as approach indicated innormal responseoperating 3.a).

Iimits 2 within a few minutes of the HELB event and do not exceed the temperature limits in NRC TRM 3.7.d by more than the 30°F action level requirement. 3 Request NRC Confirm that the equipment environmental qualification parameters

c. Request continue to be bounded.

d. Identify the methodologies used to perform the analyses, and describe any Response changes in those methodologies.

The new analysis demonstrates that the environmental parameters within these zones

Response

will remain mild. The new analysis credits the modifications installed (see response to The to 3.i) previous supportanalyses the revised perlormed TB HELB to mitigation determine strategy the environmental and results parameters in lower peak currently presented in the temperatures andUFSAR for the durations much shorter ESF Switchgear Rooms, the than determined MEERs, in the for the EDG and analyses.

previous Rooms are essentially two-part analyses. The first part determines the HELB event in As discussed further in response 3.h, the new analysis results in transient temperature profiles that are consistent with the requirements of Technical Requirements Manual 2(TRM) 3.7.d for Even though the the affected ElectricaJ rooms/areas.

Pipe Tunnel temperature Temperatures approach Ilm'lt IS not included in the normal TAM it canoperating be assumed that a reasonable temperature limit similar to the TRM limits for the limits2 within a few minutes of the HELB event and do not exceed the temperature limitsDivision 1 and 2 ESF SWitchgear Rooms (108°F) would be applicable since they are physically connected, in TRM 3.7.d by more than the 30°F action level requirement.3 3 TAM 3.7 ,d allows the temperature to be greater than the limit for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> as long as the temperature is <30°F above that limit, NRC Request 7

d. Identify the methodologies used to perform the analyses, and describe any changes in those methodologies.

Response

Attachment - Response to Request for Additional Information (Non-Proprietary) the Turbine Building and rooms of interest until the fire dampers are credited to close.

Following this, the second part is analyzed as a loss-of-HVAC event in each room of interest for a two-hour time period. The analysis is based on a limited number of line breaks in the Turbine Building, the mass and energy releases are analyzed in a way that does not maximize enthalpy, and the analysis utilizes a proprietary software program.

For steam line breaks, the previous analysis used constant mass and energy releases based on initial conditions for steam-line breaks. The new HELB analysis uses transient mass and energy releases consistent with Westinghouse WCAP-1 0961, "Steam line Break Mass/Energy Releases for Equipment Environment Qualification Outside Containment." (Reference A-5) that maximizes superheat. Speciiically, WCAP-1 0961 transient mass and energy releases maximize superheat by progressively increasing Attachment enthalpies - Response todecreasing with progressively Request formass Additional Information flow rates. (Non-Proprietary)

Maximizing enthalpies maximizes Turbine Building environmental temperatures, which in turn maximizes the environmental temperatures in the Auxiliary Building rooms of interest. The use of the Turbine Building WCAP-10961 mass and and energy rooms of interestisuntil releases the firewlth conslstent dampers are credited the current licensingto close.

basis for Following this, the second part is analyzed as a loss-of-HVAC analyzing the environmental effects of HELBs outside containment as discussed inof event in each room interest Byron SSER for a 7two-hour time period.

and Braidwood SSER The analysis is based 2 (References A- 6 onanda A-7, limited number of line respectively).

breaks in the Turbine Building, the mass and energy releases are analyzed in a way that Additionally.

does liquid line not maximize mass and enthalpy, energy and the releases analysis utilizeswere analyzed tosoftware a proprietary maximize enthalpy, program.

instead of minimize enthalpy. Maximizing enthalpy maximizes steam quality at For steam line atmospheric breaks, which pressure, the previous in turn analysis maximizes used theconstant liquid break massflow andthat energy flashesreleases to based on initial conditions steam in the Turbine Building. for steam-line breaks. The new HELB analysis uses transient mass and energy releases consistent with Westinghouse WCAP-1 0961, "Steamline In order Break to determineReleases Mass/Energy the environmental for Equipment profiles for the new Environment TB HELB mitigation Qualification Outside strategy, a larger Containment," spectrumA-5)

(Reference of line breaks is considered, mass that maximizes superheat. Specifically, and energy releases are WCAP-10961 analyzed mass transient in a way that maximizes enthalpy, and the thermal-hydraulic and energy releases maximize superheat by progressively increasing event is analyzed enthalpies with progressively decreasing mass flow rates. Maximizing enthalpies are utilizing GOTHIC. The modeijng improvements incorporated in 1he new analysis conservative maximizes and improve Turbine Building theenvironmental accuracy of the predicted plant temperatures, whichresponse to the transient in turn maximizes the consistent with the capabilities of the GOTHIC program.

environmental temperatures in the Auxiliary Building rooms of interest. The use of WCAP-10961 The revised analysis mass and did energy not alter releases is consLstent the overall Licensingwith Basis themethodology.

current licensing As basis for analyzing the environmental effects described in BIB UFSAR (Reference A- 8), Section of HELBs outside containment 3.6.1 as discussed

.1.2, the criteria in for protection Byron againstSSER 7 and Braidwood the dynamic SSER 2 (References effects associated with postulated A- 6pipeand breaks A-7, respectively).

is NRC Regulatory Guide 1.46, "Protection Additionally, liquid line Against mass andPipe Whip energy Inside were releases Containmenf' analyzed (Reference to maximizeA-enthalpy,9) and the NRC's letter instead from A. enthalpy.

of minimize Giambusso, dated December Maximizing enthalpy 1972 (Reference maximizes A-1 0),

steam quality at for designs inside and outside atmospheric pressure,thewhich containment, respectively.

in turn maximizes the Based on theflow liquid break Byron thatand Braidwood flashes to Construction steam Permit date, in the Turbine Building. the above guidance constitutes the minimum requirements for HELB design and analysis. Additional criteria, including the NRC's letter from J.F.

In order to O'Leary determineA-11),

(Reference the environmental and Branch profiles Technical forPositions the new TB HELB3-1 APCSB mitigation (Reference A-strategy, a larger spectrum of line breaks is considered,

12) and MEB 3-1 (Reference A-13), have been employed to the extent possible mass and energy releasesandare analyzed practical. in a way that maximizes enthalpy, and the thermal-hydraulic event is analyzed utilizing GOTHIC. The mode4ng improvements incorporated in the new analysis are conservative NRC Request and improve the accuracy of the predicted plant response to the transient consistent with the capabilities of the GOTHIC program.

e. Confirm that the analyses were performed in accordance with any The revised analysisand limitations did restrictions not alter the overall included Licensing in the NRC's Basis methodology.

approval of the As described in B/B methodology. UFSAR (Reference A- 8), Section 3.6.1.1.2, the criteria for protection against the dynamic effects associated with postulated pipe breaks is NRC Regulatory

Response

Guide 1.46, "Protection Against Pipe Whip Inside Containment" (Reference A- 9) and the NRC's GOTHIC letter is afrom A. Giambusso, computer program that dated December has been used 1972 (Reference for industry-wide A-10), for designs contalnment inside and outside the containment, respectively.

temperature and pressure analysis. It is capable of modeling Based on the bi-directional Byron and Braidwood flow due to Construction Permit date, the above guidance constitutes the temperature-driven buoyancy-induced flow through wall openings. Applications of the minimum requirements for HELB design and analysis. Additional criteria, including GOTHIC code have been previously approved by the NRC for determining the NBC's letter from J.F.

O'Leary (Reference A-11), and Branch Technical Positions APCSB 3-1 (Reference A-

12) and MEB 3-1 (Reference A-13), have been 8 employed to the extent possible and practical.

NRC Request

Attachment - Response to Request for Additional Information (Non-Proprietary) environmental conditions following HELBs inside and outside containment including for Turbine Buildings. GOTHIC underwent an extensive verification and benchmarking process against both analytic solutions and special effects and integral heat transfer and containment data. It is subject to 10 CFR Part 50, Appendix Band 10 CFR Part 21 req uirements.

Point Beach submitted a License Amendment Request for an Extended Power Uprate and received an SER (Reference A-14) which describes the use of GOTHIC for evaluating the effect of various HELBs, including HELBs within the Turbine Building.

The use of the GOTH Ie code for analyzing HELBs in the Turbine Building for B/B Stations has been verified to be consistent with the GOTHIC User Manual in terms of its limitations and restrictions. No user-controlled enhancements available in GOTHIC VersionAttachment 7.2a were - Response to Requestwith utilized, consistent for the Additional mannerInformation applied by (Non-Proprietary)

Point Beach as noted by the NRC in the SER. Additionally, the GOTHIC model developed for B/B is "plant-ll specific in terms of geometry, flow paths, etc., and thereby meets the provisions of 10 environmental CFR conditions following 50.49, "Environmental HELBs Qualification of inside and Electric outside containment, Equipment Important toincluding Safety forfor Turbine Buildings. GOTHIC underwent an extensive verification Nuclear Power Plants" (Reference A-15) and Regulatory Guide 1,89, "Environmental and benchmarking process Qualificationagainst both analytic of Certaln Electric solutions Equipment and Important special effects and integral to Safety for Nuclear heatPower transfer and Plants" containment data. It is subject to 10 CFR Part 50, Appendix B (Reference A-16) for the use of a plant-specific model for environmental qualification of and 10 CFR Part 21 requirements.

equipment outside containment. Evaluation of the attached rooms resutting from the conditions Point Beach in submitted the Turb*ine Building Amendment a License follows in a like manner Request for to anthat for thePower Extended previous Uprate

analysis, and received with antheSERrooms of interest (Reference being A-14) exposed which to thethe describes TBuseHELB conditionsfor of GOTHIC for a shorter evaluating duration (in the the effect prev'lOus of various analysis, HELBs, the rooms including HELBs of interest within the were exposed Turbine to the Building.

The use of the GOTHIC code for analyzing HELBs in the Turbine Building for B/B the Turbine Building conditions until the fire dampers closed, while in the new analysis, HELB dampers Stations has beenclose rapidly) verified to beand with theis GOTHIC the ventilation consistent restored significantly User Manualfaster (in the in terms of its previous analysis the safety-related room ventilation systems limitations and restrictions. No user-controlled enhancements available in GOTHIC were not cred'lted to be manuaHy7.2a Version restarted for two hours, were utilized, in the whilewith consistent thenew analysis manner the by applied ventilation Point Beach is autoas noted restarted.)

by the NRC in the SER. Additionally, the GOTHIC model developed for B/B is "plant -

specific" Therefore,inthe terms newofanalysis geometry, was flow paths, etc.,

performed and therebywith in accordance meets any thelimitations provisions andof 10 CFR 50.49, included restrictions "Environmental Qualification in the NRC's previous of approval Electric Equipment of the GOTHIC Important to Safety0961 and WCAP-1 for Nuclear Power Plants" (Reference methodologies for HELBs outside containment. A-15) and Regulatory Guide 1.89, "Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants" (Reference NRC Request A-16) for the use of a plant-specific model for environmental qualification of equipment outside containment. Evaluation of the attached rooms resulting from the

f. Describe conditions the sequence in the Turbine Buildingof eventsinand follows explicitly a like manner to identify that forthose that changed the previous analysis,aswith a result of theofresolution the rooms interest being of the nonconformance.

exposed to the TB HELB conditions for a shorter Response duration ('in the previous analysis, the rooms of interest were exposed to the Turbine Building conditions until the fire dampers closed, while in the new analysis, the The HELB previous dampers TBclose HELB mitigation rapidly) strategy and the involved:

ventilation is restored significantly faster (in the

• Allowing previous analysisthe theTB HELB environment safety-related into the affected room ventilation systemsAuxiliary were notBuilding creditedrooms to be for manually a short period restarted foroftwotime (no HELB hours, while in dampers the newinanalysis the ventilation intake/exhaust the ventilation is auto opening to the Turbine Building),

restarted.)

• Isolating Therefore, the newtheanalysis affectedwas rooms with theinactuation performed accordanceof the withfire anydamper in theand limitations ventilation exhaust opening, restrictions included in the NRC's previous approval of the GOTHIC and WCAP-10961

• Room cooling methodologies for HELBs manually outside restored in two hours by operator action (fans trip due to containment.

isolation of the flowpath, with subsequent loss of- ventilation), and NRC

• Request Thermal-hydraulic event analyzed to predict room temperature conditions (vendor proprietary

f. Describe the sequence software with mass of events and and energyidentify explicitly releasesthose determined for the that changed assumed line breaks) as a result of the resolution of the nonconformance.

The revised HELB mitigation strategy that is being implemented is one that involves:

Response

The previous TB HELB mitigation strategy involved:

9

• Allowing the TB HELB environment into the affected Auxiliary Building rooms for a short period of time (no HELB dampers in the ventilation intake/exhaust opening to the Turbine Building),

• Isolating the aff ected rooms with the actuation of the fire damper in the ventilation

Attachment - Response to Request for Additional Information (Non~Proprietary)

• Keeping the TB HELB environment out of the Auxiliary Building rooms (isolating the rooms by means of new normally open, reverse flow HELB dampers)and the Main Control Room (installing HELB sensor that prevents make~up air being taken in subsequent to a TB HELB),

• Conftguring the fire dampers to close only in the event of a fire,

• Room ventilation automatically restored (auto-restart of the room ventilation fans to keep the rooms within their design basis temperature limits), and

• Performing a new analysis of the thermal~hydraulic event to predict room environmental conditions following the HELB (GOTHIC analysis with updated mass and energy releases, and additional line breaks considered).

NRCAttachment Request - Response to Request for Additional Information (Non-Proprietary)

g. Describe and justify the chosen single-failure assumption.

Response Keeping the TB HELB environment out of the Auxiliary Building rooms (isolating the rooms by means of new normally open, reverse flow HELB dampers)and the Each ofMain the modifications Control Roomthat implement (installing HELBthesensor new TB HELB that mitigation prevents make-up strategy, as air being discussed in the Response 3.i, taken in subsequent to a TB HELB), includes consideration for single failures.

• The new HELB Configuring the damper fire dampers assemblies to closeinclude only intwo the normally event of aopen fire, backdraftlreverse

• Room ventilation automatically restored (auto-restart of the of flow dampers arranged in series with the allowed direction roomair flow from the ventilation fans room to the TB. A failure of a single HELB damper to keep the rooms within their design basis temperature limits), and to close will not prevent

\solation of the flow path dur'tlg a HELB. The opposlte train of ESF equipment

• Performing a new analysis of the thermal-hydraulic event to predict room would also remain available if the either of the HELB dampers, or the fire environmental conditions following the HELB (GOTHIC analysis with updated damper, in the assembly failed closed preventing the ventilation fan auto restart.

mass and energy releases, and additional line breaks considered).

• The failure of a high differential pressure trip time delay relay for a single ventilation system train will not prevent the opposite ESF train from supporting NRC Request the safe shutdown of the unit.

g. Describe and justify the chosen single-failure assumption.

• The failure of instrumentation for the automatic high room temperature auto start Response feature for a single EDG Room supply fan will not prevent the opposite ESF train Each offrom supporting thethat the modifications safe shutdownthe implement of new the unit.

TB HELB mitigation strategy, as

• The discussed inmodification the Response for3.i, theincludes Control consideration Room Emergency Make-Up for single HELB sensors failures.

• The new HELB damper assemblies include two normally open Building.

includes fail safe logic for the intake damper from the Turbine In backdraft/reverse flow dampers arranged in series with the allowed direction of air flow from the addition, a single failure of a Control Room ventilation train will not impact the ability room to to the support TB. Aestablishing failure of a safesingleshutdown.

HELB damper to close will not prevent

• Isolation A failure of of the the instrumentation flow path duringfor the DOST a HELB. Theexhaust oppositefan tripofon train ESFhigh Turbine equipment Building would alsotemperature remain availablemodification will also if the either onlyHELB of the impact a singleor dampers, train.

the fire

• Thedamper, in the modifications structural assembly failed closed divisional preserve preventingseparation the ventilation and the fanstructural auto restart.

• Theintegrity failure of the of arooms affected bypressure high differential a TB HELB.

trip time delay relay for a single ventilation system train will not prevent the opposite ESF train from supporting From an analytical standpoint, the new thermal-hydraulic analysis considers, the safe shutdown of the unit.

• The failure of a MSIV for steam line breaks to maxlmize the overall mass and

• The failure of instrumentation for the automatic high room temperature auto start energy release.

feature for a single EDG Room supply fan will not prevent the opposite ESF train

• fromFor asupporting feedwater the line safe break, there isof shutdown nothesingle unit.failure that will prevent the isolation of the feedwater system or the functioning of the reactor protection system (Le.,

• The modification for the Control Room Emergency Make-Up HELB sensors single failure evaluations have previously been performed for these systems).

includes fail safe logic for the intake damper from the Turbine Building. In

• addition, For heater dra~ Une a single breaks, failure all available of a Control Roomwater volumetrain ventilation is assumed to be the will not impact discharged ability into the to support Turbine Bulld'flg establishing such that no equipment is credited with safe shutdown.

limiting the mass and energy release from that system.

• A failure of the instrumentation for the DOST exhaust fan trip on high Turbine Building temperature modification will also only impact a single train.

• The structural modifications preserve10divisional separation and the structural integrity of the rooms affected by a TB HELB.

From an analytical standpoint, the new thermal-hydraulic analysis considers,

• The failure of a MSIV for steam line breaks to max1mize the overall mass and

Attachment* Response to Request for Additional Information (Non-Proprietary)

NRC Request

h. Provide plots of important parameters and explicitly identify those that changed as a result of the resolution of the nonconformance.

Response

The operability evaluations that address the non-conformances only address the transient temperature conditions in the EDG Rooms, the ESF Switchgear Rooms, and the MEER. A comparison is provided for the transient temperature profiles for these rooms under the previous analyses and the analyses which 'Implement the revised TB HELB mitigation strategy.

In the previous analysis, the initial temperature increases rapidly in the rooms until the Attachment - Response to Request for Additional Information (Non-Proprietary) fire dampers are assumed to close, once the fire damper is assumed closed the rooms continue to heat up due to the loss of ventilation but at a slower rate until the ventilation is assumed NRC Request to be manually restored after 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The temperature profile for the EDG Rooms (Figure 3-1a) rapidly increases to approximately 158°F until the fire damper

h. then closes Provide plots trends the room of important to 167°Fparameters and is until ventilation explicitly restoredidentify those that (Figure 3-1b). The changed temperature profileasfor a result the ESF of Switchgear the resolution rooms of the nonconformance.

(Figure 3-3a) rapidly increases to approximately Response 165°F until the fire damper closes then the room trends to 160°F until ventilation is restored (Figure 3-3b). The temperature profile for the MEER rapidly The operability increases evaluations 175°F to approximately that address for thethe non-conformances Division 11 room and to only address the 140°F approximately transient for the Division 12 room (Figure 3-5a) until the fire damper closes then theRooms, temperature conditions in the EDG Rooms, the ESF Switchgear Division and11 the MEER. A comparison is provided for the transient temperature room trends to 128 F (Fig ure 3-5b) and the Division 12 room trends to 132 F (Fig ure 3-0 profiles 0 for these rooms 5c) untilunder the previous ventilation analyses and the analyses which implement the revised TB is restored.

HELB mitigation strategy.

The new analysis credits the backdraftlreverse flow dampers and other modifications In the previous installed analysis, to implement thethe initial TB revised temperature increases HELB mitigation rapidly in strategy. the rooms These changes until the fire dampers minimize the are assumedoftohot introduction close, oncesteam air and the fire intodamper the roomsis assumed and permit closed the the rooms rapid continue automatictorestoration heat up dueoftoventilation the loss oftoventilation restore room buttemperatures.

at a slower rateThe untilresulting the ventilation worst is assumed to be manually restored after 2 hours. The case temperature profiles for the EDG Rooms, ESF Switchgear Rooms, and MEER temperature profile for the EDG are Rooms (Figure 3-1 a) rapidly increases to approximately 158°F provided in Figures 3-2,3-4 and 3-6, respectively. These temperature profiles indicate until the fire damper closes that thethen peak thetemperatures room trends to are167°F until ventilation consistent is restored (Figure with the requirements 3-1 b). The of Technical temperature profile for the ESF Switchgear rooms (Figure Requirements Manual (TRM) 3.7.d (as shown in Table 3-1), in that the temperatures 3-3a) rapidly increases to are approximately 165°F until the fire damper closes then the room rapidly restored to below the Operating Limit well within the allowed 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> specified in trends to 160°F until ventilation the TRM, and is restored remain (Figure well below 3-3b).

the The TRMtemperature Operating Limit profile for the MEER rapidly

+30°F.

increases to approximately 175°F for the Division 11 room and to approximately 140°F for the Division In addition to the12EDGroomRooms, (FigureESF 3-5a)Switchgear until the fire damper Rooms, andcloses MEER. thenthethenew Division 11 analysis room trends to 128°F (Figure 3-5b) and the Division 12 room also includes the DOST Rooms. the Electrical Pipe Tunnel Temperatures. and Division trends to 132°F (Figure 3-5c) until ventilation is restored.

12122 Lower Cable Spreading Room. Worst case temperature profiles for these rooms are provided The new analysis in Figures credits3-8 thethrough 10.

backdraft/reverse flow dampers and other modifications installed to implement the revised TB HELB mitigation strategy. These changes Comparisonofofhot Table 3-1: the introduction minimize Peakair Room Temperatures and steam into the roomsto Operating and permit Limits the rapid automatic restoration of ventilation to PeakHElB restore room temperatures. TRM The resulting worst case temperature profiles for the EDGTemperature Rooms, ESF Switchgear Operating Rooms, Limit and MEER are providedEDG in Figures Rooms3-2, 3-4 and 3-6, respectively. 150°FThese temperature 132°Fprofiles indicate that the peak temperatures are consistent with the requirements of108°F ESF Switchgear Rooms 131°F Technical MEER Manual (TRM) 3.7.d (as shown114°F Requirements in Table 3-1), in that 108°Fthe temperatures are Division to rapidly restored 12122 below Lower the Cable Operating Limit well 112°F within the allowed 108°F 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> specified in the TRM,Spreading and remain Room well below the TRM Operating Limit +30°F.

DOST 140°F _ !_~~oE_

In addition to the EDG Rooms, ESF Switchgear Rooms, and MEER, the new analysis also includes the DOST Rooms, the Electrical Pipe Tunnel Temperatures, and Division 12/22 Lower Cable Spreading Room. Worst case temperature profiles for these rooms 11 are provided in Figures 3-8 through 10.

Table 3-1: Comparison of Peak Room Temperatures to Operating Limits Peak HELB TRM

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-1 a: Previous Analysis - EDG Temperature Profile - To Fire Damper Closure o to O.5sec: 98.7ES. h: 11914 DG Room Temp - Steam Break (MS4) on 401' 0*5 to 10see: SOE6. h"1191.4 Roll-up Door, Windows, and Louvers Closed 10 to 15sac: RELAP5 Histogram 165.0  !

I I I

160.0 j

~

I 155.0

~

Damper I Closure I 150.0 I Attachment - Response to Request for Additional 145-0 ~ Information (Non-Proprietary)

I I

~

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~ 1410

~

I I

_I

~ 135 .0 ,

Figure 3-1a: Previous Analysis - EDG Temperature Profile - To Fire Damper Closure f

!. 131 .0 - - - - -- / I I

I

~

I- 125.0

/ I f\

"v'

/" DG Room Temp - Steam Break (MS4) on 401' 0 to 0.5sec: 98.7E6. h=11914 I 0,5 to 10sec: SOE6, h-1191.4 I I

Roll-up Door, Windows, and Louvers Closed 10 to 15sec: RELAP5 Histogram I 115.0 I

165.0 -^-^ I 110-0 I I

160.0 105*0 I

(

155.0 l!lO{)

Damper 00 2*0 40 6 .0 a *~ 100 12.D 14.u Closure 150.0 7i27/11 9 :OOam Time (sec) 145.0

,.., 1470 Figure P 3.. 1b: Previous Analysis - EDG Temperature Profile - 2 Hour Profile 135,0 a

a13'0-Rlll Un'baIOG RoOm lemp - 15cr'F 125.0, DG Heatup Model- DG Room Temp Rlll 2 : WtaIOG RoOm Temp =1 70°F I

120-0 175 115-0 1

170 1----------------------------------------------------------------------~

110-0 105x) 070 - -^

00

~5+---------------_ 2 ,~-. 40

- ---- 60 ---.-~=~8.t 100 12.1 146 r

7.2711 9:'"dam Time (sec)

Figure 3- 1 b: Previous Analysis - EDG Temperature Profile - 2 Hour Profile

~~ ~--------------------------------------------------------------------~

Rur 1: In to IDG Room Ternp 15p'F OG Heatup Model - DG Room Temp Run 2 InirsIDG Room Temp =170-F 1~

175 +_--------------------------------------------------------------------~

45+-----~------~----~------~----~~----~------~----~------~----~

170 0-0 0 *2 0.4 0.6 oe 10 1.4 1.6 1.8 2.0 Time (tu)

'65 12

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3- 2: New Analysis - EDG Room Temperatures - Worst Case Following 0.5 fe MS Break on TB 401' Elevation 160 I

150 -----------------------1---- :-----1-----------7-----------

, I I I I

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _  !.. - ~!: ~"'-""'::::: .".", ~,:,{,-~___________ .l. __________ _

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- Response to Request for Additional Information (Non-Proprietary)

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I E- Figure 120 2:

- - - - - - - - - - - ;- -  ; ;- - - - - - - - r - - - - - - - - - - - r - - - - - - - - - - - T - - - - - - - - - - -

New Analysis - EDG Room Temperatures - Worst Case

, ,, ;, ,.,,., I I I Following 0.5 ft2 MS Break on TB 401' Elevation Of' ,

110 ----------------- -----------T----------- T-----------

160 r 100 150 ---------------------

0 30 60 90 120 150 Time (sec) i -DGA ---DGBi 130 ---------------- ------ ----

c.

H 120 ---------------

100 0 30 60 90 120 150 Time (sec)

-DGA ---DGB 13

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-3a: Previous Analysis - ESF Switchgear Temperature Profile -

To Fire Damper Closure ESF SWGR Room Temp - Liquid Break (H03) on 428' Roll-up Door, Windows, and Louvers Closed 200.0 - -

I I

1 190.0 I

I I

170.0 l ~

Attachment - Response to Request for Additional Information (Non-Proprietary)

/ ,oamper Closure E160.0 e

I Figure

/ 1 iii 150 *0 3-3a: Previous Analysis - ESF Switchgear Temperature Profile -

~

~

E 140*0

/ I To Fire Damper Closure 130.0

/ I I

I ESF SWGR Room Temp - Liquid Break (HD3) on 426' Roll-up Door, Windows, and Louvers Closed I

I I

I  :

200.0 I 110.0 190.0 f

f I I

I 1

I 100.0 1800 00 10*0 200 3'*0 400 I

7127 111 1O:~;rn Time (sec) 170.0 Damper Closure a 160.0 Figure m 3-3b: Previous Analysis - ESF Switchgear Temperature Profile -

io 150.0 E Temperature VS. Time for SWGR Rm (Elevation 426 feetl F 140-0 - - - - - - - -

180 130.0 I

175 120.0 170 I.- --IniInitialtial Tompemture 155 FI Temperoture 135 F I I

110.0 1  !-lniliaJ Tempero\Ure 175 F I 100.0 00 \ 100 200 3310 400 60.0

\

7,27 1 1 10.-3'0 fm Time (sec)

~- -

Figure 3-3b: Previous """" Analysis - ESF Switchgear Temperature Profile -

/

I I

140 ,

/ Temperature vs. Time for SWGR Rm (Elevation 426 feet)

I I 10V ----

135 175 130 I I , .

Initial Temperature 1F-I I  ;

170-o 0_2 0.4 0_6 OR 1.4

-Initial Temperature 135 F 1.6 1.8 2 InAW Temperature 175 F 165 160 14 155 150-

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-4: New Analysis - ESF Switchgear Room Temperatures - Worst Case Following 0.5 if MS Break on TB 426' Elevation 135 130 - - - - - - - - -- ~

I 1

j

~~ ;- - - -'-,: ; - - - - ,. -

"" .... ' , 1

- - ~

l "J' ~,

1 1 " 1 ,

125 - - - - - - - -- ~- -- - - - - - -  ;- - - - - ,-/~ - - ~ - - - - - ,- - ~ ,,-, - - - --~ - - - - - -- --

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I-< 120 - - - - - - - - - 1- - - - - - - - - ; ',- - - - - - - - - - - - -'1,- - - - - - - - -

I 1 " I I "

~

Attachment - Response to Request for Additional Information (Non-Proprietary)

(\:I

~ I /

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d) 0.. 115 _________ ~--- ?L----~--- -----~-------- - } ---------f-- --~ ~ ~

E " 1

~ 3-4:

I ,," I I / I Figure New Analysis - ESF Switchgear Room Temperatures - WorstI Case 110 ------- ~ 7 , ---

Following 0.5 ft2 MS Break on TB 426' Elevation I

I

,l ---------,---------.---------

L I

I I

, I 105 - ------- - , -------- r- --------r---------T-------------------

~ J ,

135 100 o 20 40 60 80 100 120 Time (sec)

I-SWGRDiv 1 ---SWGRDiv21 105' -

100 t 0 20 40 60 80 100 120 Time (sec)

-SWGR Div 1 --- SWGR Div 2 15

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-5a: Previous Analysis - MEER Temperature Profile - To Fire Damper Closure MEER Temperature. Liquid Break (HD1) on 451' RolI..up Door, Windows, and L.ouvers Closed 180 1 I I

/  :  : Mecc ~;.,.

~ R Oiv . 1 1 I

/  : I 11 Damper I Closure I

I

/  :

I I

Attachment - Response / ~

to Request for Additional Information (Non-Proprietary) WEER Div. 12 J

/ /

Figure 3-5a: Previous Analysis - MEER Temperature Profile - To Fire Damper Closure I

/ /

MEER Div* ;

t2~r :

Cbsure r, MEER Temperature - Liquid Break (H D1) on 451' I W

Roll-up Door, I Windows, and Louvers Closed 1

1 11t I I

I I

100 I

MEER Div 11 I

o.() 5." 1A.1l 15.0 200 25.0 30G 350 400 45.0 SO.O 55*0 SO.O Tlma(sec)

Figure 3-5b: Previous Analysis - MEER Division 11 Temperature Profile - 2 Hour Profile MEI!R11 Heat-Up (el. 451') MEER Div 12 190 180 I

'2 I

170 - - - Original Calc (MEER1 1 - 117"F)

I 310 1 I

I- =

New Temps (MEER 11 151"F)

- - - New Temps (MEER 11 "'- 1aO"F) 160 .11 100I r r r T 00 1 50 10.s 150 200 25C 300 350 400 450 500 550 6D0 7/27 I 11 4-or1Pm TEtna (sec )

\

\

Figure 3-5b:\\ Previous Analysis - MEER Division 11 Temperature Profile - 2 Hour Profile 130 J\ , MEER11 Heat -Up (el. 451')  :

~

120 ~~--------------------------------------------------------------------

110+-----------------------------------------------------------------------

- - - Original Calc (MEER11 =I 17*F)

- New Temps (MEER11 = 151'F)

~O +------,------.------.------~------.------.------.------.------.------.

- - - New Temps (MEER11 = 180'F) o 02 0.4 0_6 0 .8 1.2 1.4 1.6 1 .8 2 Time (hours.)

a 16 130-

Attachment - Response to Request Tor Additional Information (Non-Proprietary)

Figure 3-Sc: Previous Analysis - MEER Division 12 Temperature Profiles - 2 Hour Profile

~ER12 Heat.Up (el. 451')

150 40 I

\

II I

I

\

\

.. *

• Origin01I C4lic (MEER12 =11rF)

I  :- NewTemps (MEER12 =121'F)

\ j- - - New Temps (MEER12:: 1~SF)

__ 135 Attachment

\

, - Response to Request for Additional Information (Non-Proprietary) f \ -.J;

~ \

f 13() \ - - ~

D 3-5c:"Previous Analysis - MEER Division 12 Temperature Profiles -2 Hour Profile Q. ~

~

E Figure D

t- ~5 I V~ MEER12 Heat-Up (el. 451')

ou

~ ,

45 -

115 1 40 110 Original C-Ac (MEER12 =117°F1

() 02 0.4 0.6 0.8 12 1.4 New Temps (MEER12 1.8= 121-F) 2 35 Time (hou~) - - New Temps (MEER12 145-F) 30 25 20 15 1n 0 0.2 C.4 C6 0.8 1 1-2 1 4 1,8 2 Time (hours) 17

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-6: New Analysis - MEER Temperatures - Worst Case Following 26" HD Break on TB 451' Elevation 116 I I 114 ---------~-------------------~-------------------~---------

I 1 ..-' I

",,-' I "  !

I I ' , _ I

_________ L _________ ~ ~~

",4""

____ ~ _________ l_- _____ -_

112 j ,.,, "'.,1 I G:' t ",'"

I I ......

0

'-'" 110 --------, : ~ 7~ - -----~---------r---------~-~ ~ ~ ,

e:::sAttachment - Response/.~

I to Request for Additional Information (Non-Proprietary)

I I I

............ I

....... ...... 1 e~

108 --------~---------~---------~---------~---------~-,,- - ----

t i I

l I

l ....

0.. I E 106 .~ - - - - - - - - - ;-I - - - - - - - - - -I - - - - - - - - - Ij - - - - - - - - - *

~ - - - - - - - - - -j - - - - - - - - -

~

Figure 3-6: New Analysis - MEER Temperatures - Worst Case 104 Following 26" HD Break on TB 451' Elevation

---

r -------------------r--------- ---------T---------

102 ----------~---------~---------~---------~---------~---------

I I 100 114 ----------- ------------------- ----------

20 40 60 80 100 120 112 r------------------- ---' -------------- ' --------

Time (sec) w 110 ---------

I-MEERDiv I --- MEER Div 2 I co 108 ----------------- = -------- -------------------

106  :------------------------------------------------------------

104 ----------

102 -- - - - - - - - - - I- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - x - - - - - - - - - a 100 1 20 40 60 80 100 120 Time (sec)

-MEER Div I ---MEER Div 2 18

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-7: New Analysis - Braidwood 401' Auxiliary Bldg. Temperatures - Worst Case Following 0.3 fe MS Break on TB 401' Elevation 145 ~- - - - - I - ~ - - - - I L

- - - - - - ~- - - - - - -,- - - - - -

, I I I  : 1 I I 140 E ------~--- -- --~------~-------~------~-------:------~---- ---

135 ~ . ------~-

I

---

- (--

1 \ 1

--~-------~------~--- -- --~------ ~ -------

1 I \

L 1 1

~~~~~~_J-~_~-~:t:::: ~- ::~--:::[::---_j_--::::t:-----~ --:::::

~

0 130

~

4l

.... 125

s ~ 1 1  : L I I

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~.

- Response to Request for Additional Information (Non-Proprietary)

I 0.. 120 ~

I

- - - - - - I- - - - - - - -: -

I

- - - - - ...j - - - - - - - 1- -

- - - - - -+ - - - - - - -

E ~ I I 4l ,L:

~

Figure 115 ~New 3-7:

-- - -- , -------r------ , -- -- --- ~ ------,-------r------ ~ -------

Analysis - Braidwood 401' Auxiliary Bldg. Temperatures - Worst Case Following 0.3 ft2 MS Break on TB 401' Elevation I l ) I  !

110 -----,------ -- ------l------- ~ ------ -------~------ ~ -------

1 I I I "

I I I I I 1 1 I 105 145 ------~------- r ------l- -- ----~------1-------r----- ------

I 100 140 -------'------

• I *

• 1 * , L ,

• I *

• 1 , I

. I o

r1 I 900 1800 2700 3600 4500 5400 6300 7200 Time (sec)

!-AB4011 105 ^ -------------- -------------- I --------------- ------_.-------

1 100 Y . . , . . . , 1 ,

0 900 1800 2700 3600 4500 5400 6300 7200 Time (sec)

- AB 401 19

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-8: New Analysis - Diesel Oil Storage Tank Room Temperatures - Worst Case Following 1.4 If MS Break on TB 401' Elevation 145 I I

1 1 '

140 1

- - ,' .......- - - - - - - -,- - - - - - - - - - - -I - - - - - - - - - - - I - - - - - - ~ ~ - - - 'I - - - - - - - - - - -

- I"

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- -l - _.....;,.,. _ - - .. 1.- _ _ _ _ _ _ _ _ _ _ 1 ___________ J ___________ I. _ _ _ _ _ _ _ _ _ _ _

135 I ' I 1 1 I I ' .....  ! I

~ 130 j - - - - - - - ~~-, - - - - - - - - - - -" - - - - - - - - - - - ~ - - - - - - - - - - - ~ - - - - - - - - - - -

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~ 125 _I ________ _ ,_____ '

E , I C1:S Attachment - Response to Request for Additional Information (Non-Proprietary)

I ...... ...

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4..)

120 E - - - - - - - - - -:- - - - - - - - -- - :-...---~ -- -- - - - - - - -'.- -- - -- -- - - - -

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_ - _ - _ - - ___ ;_ - - __ - - - - - - -: - - - - - - _ - - - - J.. - - ~ - - - - - - ~-~---~-:..- - _

1----__--- t f-i 115 Figure 3-8: New Analysis - Diesel Oil Storage Tank Room Temperatures - Worst c. :..-:.,.-_ -

Case Following 1.4 ft2 MS Break on TB 401' Elevation

___________ __________ ..J _ _ _ _ _ _ _ _ _ _ _ 1 ___________ l- _ _ _ _ _ _ _ _ _ _ ._

110

\~

1 I

___________ 1 ___________ ....! _ _ _ _ _ _ _ _ _ _ _ ..L ___________ L.. _ _ _ _ _ _ _ _ _ _ ...

105 145

.100' --

140 --------------------------- ---- -----------------------

o 300 600 900 1200 1500 135 ---- ------ ---- ---------- L - - - - - - - - - - -

I \ \

Time (sec) w 130 -' _ - - - - - - - - - - L - - - - - - - - - - -

!-.-DOST A - -- DOSTB I 125 Figure 3-9: New Analysis - Electrical Pipe Tunnel Temperatures - Worst Case 0 120 Following 0.5 ft2 MS Break on TB 401' Elevation H 115 ^1---- --------------------------------------

114 112 -------- - - - - - - -

I 1

-I - - - - - - - - -

1 "I - - - - - - - - -

-~__ 1 inn110 -- ----1 - ---

---+-

-~ ,~. -.~

I

-J - - ---- - - --

~

.a e

0 108

--- ~ 300

,600

_ 1-I Time (see) 900 1200 1500

8. 106

_ __ __ ~ _ _ _ t I

~ _ _______ ________ _ I _

-I DOST A ---i DOST B,

\~ ..... _ .-- _ _ _ _ _ -.J _ _ _ _ _

1

~ _ _ _ .J _ _ _ _ _ _ _ _ _

I E

4..)

~ I _ _ _ _ _ _ _ _ _ ---' _ _ _ _ _ _ _ _ _ -J _

Figure 3-9: 104 New Analysis - Electrical Pipe Tunnel Temperatures - Worst Case

___________ 1 _ _________ i __________ _______ _

Following 0.5 ft2 MS Break on TB 401' Elevation I

102 - - - - - - - - - - - - - - - - - -

1

- - - - - - - - - - - - - - - -i -

1 114 r 100 112 --------- -- - --------- ---------

o 20 40 60 80-------------------- 100 120 110--

Time (sec) -------

o 108 ----------------------------- ---------

106 ..... . ......... .. 20 ---- ---- -

E 104 -- ------ --------- --------- --------- --------- ---------* I ^

Attachment - Response to Request for Additional Information (Non-Proprietary)

Figure 3-10: New Analysis - Division 12122 Lower Cable Spreading Room Temperatures-Worst Case Following 0.5 fe MS Break on TB 401' Elevation 114 I I I I I 112 ---------~------------------~---------~---------1---------

I , I I I --.~ I

, I ~ I 110 -- - - - - _,' - - - - - - - - - -: - - - - - "'""-----..:::._- ~ - - - - - - - ~ -

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108

~ ~

~

~

Attachment - Response to Request for Additional Information (Non-Proprietary)

~

106 -----'- ---------' - ---------: --------- --------- -------j

~

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~ _ _ ,

_ _ _ _ _ _ _ I _ _ .- _ _ _ _ _ _ _ 1_ _ _ _ _____ I_ _ _ _ _ _ _ _ _ ...J _ _ _ _ _ _ _ _ _ ...I .... _ _ _ _ _ _ _ _ _  !

104 New Analysis - Division 12/22 Lower Cable Spreading Room Temperatures -

Figure 3-10:

~

I I I (

Worst Case Following 0.5 ft2 MS Break on TB 401' Elevation 102 - - - - - - - - - I - - - ~ - - - - - 1

- - - - - - - - - J-I I

- _______ --i _ _ _ _ _ _ _ _ _

I 114 t 100 112 -------- ----------- -------------------;--

0 20 40 60 _J- 80 I 100 I 120 110 Time (sec)

Z, 4

j-csl 12 108 --------- - --- ------ - - --------------

U 106 -------------

104 r---------------------------- - ----------------------------

102 100 0 20 40 60 80 100 120 Time (sec)

---

Cs 21

Attachment - Response to Request for Additional Information (Non-Proprietary)

NRC Reguest

i. Discuss any plant modifications required to support the analysis.

Response

The standalone modifications supporting the revised TB HELB mitigation strategy are those that

1) Install a single-failure proof HELB damper and fire damper assembly in place of the fire damper in the ventilation exhaust openings from the EDG Rooms, the Electrical Cable Tunnel, the ESF Switchgear Rooms, the Division 12122 Lower Cable Spreading Rooms, the MEERs and the non-ESF Switchgear Rooms.

Attachment - Response to Request for Additional Information (Non-Proprietary)

2) Change the fire damper links for the fire dampers in the ventilation exhaust opening to the Turbine Building for the EDG rooms, the ESF Switchgear rooms, and the Division 12122 Cable Spreading rooms to a higher temperature link, such NRC Request that the dampers will only close in the event of a fire and not as a result of a HELB

i. in Discuss the Turbine anyBuilding.

plant modifications required to support the analysis.

3) Install relays that will allow the ventilation fans serving the EDG Rooms, the

Response

Electrical Cable Tunnel, the ESF Switchgear Rooms, the Division 12122 Cable The standalone Spreadingmodifications Rooms, and the supporting MEERsthe thatrevised TB HELB mitigation will automatically re-start thestrategy are a fans after those suitable that: period of time following a trip on high fan differential pressure.

1)

4) Install Install ana single-failure automatic high proof roomHELB damper and temperature startfire damper feature for assembly in place the ventilation of the supply fire fansdamper servinginthe theEDG ventilation Rooms.exhaust openings from the EDG Rooms, the Electrical Cable Tunnel, the ESF Switchgear Rooms, the Division 12/22 Lower Cable

5) Spreading Install a HELB Rooms,sensorthe to prevent MEERs andthethe Control non-ESFRoom emergency Switchgear make-up air Rooms.

filtration unit Turbine Building intake from opening in the event of a TB HELB.

2) Change the fire damper links for the fire dampers in the ventilation exhaust

6) opening Install a toHELB sensor to the Turbine automatlcally Building for the shut-off EDG rooms,the DOSTthe ESF Room exhaustrooms, Switchgear fans.

During normal operation, the DOST Room exhaust fans and the Division 12/22 Cable Spreading rooms to a higher temperature link, draw air into the rooms such from the Turbine Building and shutting down the fans limits the that the dampers will only close in the event of a fire and not as a result of a HELB introduction of hot airthe in and steamBuilding.

Turbine following a HELB. The DOST Rooms do not require HELB dampers to maintain acceptable environmental conditions in the rooms.

3) Install relays that will allow the ventilation fans serving the EDG Rooms, the

7) Electrical ImplementCable modifications Tunnel, theto the ESFdivisional Switchgear separation Rooms, walls to withstand the Division 12/22theCable Spreading Rooms, and the MEERs that will automatically re-start theHELB additional loading of a small HELB-induced load resulting from the fans after a environment suitable periodentering of time the rooms aprior following to the trip on highHELB dampers closing.

fan differential pressure.

8) Install

4) Implement modifications an automatic to affected high room L-row wall temperature startdoors feature to for withstand the maximum the ventilation supply H ELB pressure. This fans serving the EDG Rooms. includes reinforcing existing doors or creating protected alcoves to existing doors. Access to the new alcoves is through HELB resistant

5) Install doors. a HELB sensor to prevent the Control Room emergency make-up air filtration unit Turbine Building intake from opening in the event of a TB HELB.

9) Install jet impingement shields to protect the Control Room HVAC purge exhaust

6) Install dampers. a HELB sensor to automatically shut-off the DOST Room exhaust fans.

During normal operation, the DOST Room exhaust fans draw air into the rooms 10)from Re-routing the Turbine Station Heating Building andsystem shuttinglines downtotheminimize the potential fans limits for the of the introduction failure hot of these lines to impact the HELB dampers air and steam following a HELB. The DOST Rooms do not require HELB dampers to maintain acceptable environmental conditions in the rooms.

7) Implement modifications to the divisional separation walls to withstand the additional loading of a small HELB-induced load resulting from the HELB environment entering the rooms prior to the HELB dampers closing.

8) Implement modifications to affected L-row wall doors to withstand the maximum HELB pressure. This includes reinforcing existing doors or creating protected alcoves to existing doors. Access to the 22new alcoves is through HELB resistant doors.

9) Install jet impingement shields to protect the Control Room HVAC purge exhaust dampers.

Attachment - Response to Request for Additional Information (Non-Proprietary)

NRC Request

j. Discuss the results and acceptance criteria for the analysis, including any changes from the previous analysis.

Response

The acceptance criterion for the TB HELB design has been and remains to prevent exposing the safety-related equipment and components in the adjacent auxiliary building rooms from an environment that could chaMenge its ability to perform its safety function.

The overall design objective of the rev*lSed TB riB-B mitigation strategy is to keep the Turbine Building environment out of the Auxil"l8ry Building Rooms, to provide a mechanism to rapidly restore cooling to the rooms, to minimize the temperature peak, and to Attachment minimize the - Response time thattotheRequest for Additional are room temperatures Information elevated;(Non-Proprietary) this objective is demonstrated in the new analysis. In this respect, the design criterion is no different from that of the previous analysis.

NRC Request The new analysis credits the modifications installed to support the revised T8 HELB

j. Discuss mitigation strategytheand results resultsand acceptance in lower criteriaand temperatures for much the analysis, including any shorter exposure changes from the previous analysis.

durations than determined'" the prevlous analysis for the subject areas. The revised analysis Response demonstrates that the environmental parameters within these areas would not be significantly more severe than the envlronment that would occur during normal plant The acceptance criterion for the TB HELB design has been and remains to prevent operation.

exposing the safety-related equipment and components in the adjacent auxiliary building rooms from an environment that could challenge its ability to perform its safety function.

NRC Request The overall design objective of the revised TB HELB mitigation strategy ts to keep the

4. Provide Turbine confirmation Building environment that outyou areAuxiliary of the ready for an NRCRooms, Building staff audit to confirm to provide a that your resolution of the HELB non-conformance has restored mechanism to rapidly restore cooling to the rooms, to minimize the temperature peak, the licensing and and desIgn basisthe to minimize oftime the plants that theandroom bound operation temperatures arestelevated; the uprsted power level.

this objective is The auditin demonstrated is the expected to include new analysis. an extent-of-condition review, In this respect, the design criterion is no analyses, differentand frominstalled that of themodifications.

previous analysis.

Response

The new analysis credits the modifications installed to support the revised TB HELB mitigation EGC is ready strategy and results to support an NRC in lower temperatures staff audit at Cantera andand much bothshorter exposure Braidwood and Byron durations than Station on or afterdetermined July 15, In the previous 2013. analysishas This timeframe forpreviously the subjectbeen areas. The revised discussed with the analysis NRC Projectdemonstrates Manager.that the environmental parameters within these areas would not be significantly more severe than the environment that would occur during normal plant operation.

NRC Request

4. Provide confirmation that you are ready for an NRC staff audit to confirm that your resolution of the HELB non-conformance has restored the licensing and design basis of the plants and bound operation at the uprated power level.

The audit is expected to include an extent-of-condition review, analyses, and installed modifications.

Response

EGC is ready to support an NRC staff audit at Cantera and both Braidwood and Byron Station on or after July 15, 2013. This timeframe has previously been discussed with the NRC Project Manager.

23

Attachment - Response to Request for Additional Information (Non-Proprietary)

REFERENCES A-1 Letter from Craig Lambert (Exelon Generation Company, LLC) to u. S, NRC, IIRequest for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate," dated June 23,2011 A-2 Letter from Kevin F. Borton (Exelon Generation Company, LLC) to u. S. NRC, II Additional Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate,lI dated November 1,2011

[RS 11-169]

A-3 Letter from Kevin F. Borton (Exelon Generation Company, LLC) to u. S. NRC, II Additional Information Attachment - Response to Supporting Request Request for for License Additional Amendment Information Regarding (Non-Proprietary)

Measurement Uncertainty Recapture Power Uprate,1I dated December 9,2011

[RS 11-178] [ML113430811]

REFERENCES A-4 Letter from Kevin F. Borton (Exelon Generation Company. LLC) to u. S. NRC, IIAdditionallnformation Supporting Request for License Amendment Regardng A-1 Measurement Letter from Craig Lambert Recapture Uncertainty (Exelon Generation Company, Power Uprate,lI LLC) dated Apr'llto27,2012 U. S. NRC, "Request for License

[RS 12-047] [ML12121A496] Amendment Regarding Measurement Uncertainty Recapture Power Uprate," dated June 23, 2011 A-5 WCAP-10961 Revision 1, Steamline Break Mass/Energy Releases for Equlpment A-2 Environment Letter from Kevin F. Borton Qualification (Exelon Outside Generation Company, Containment, LLC) to U. S. NRC, "

October 1985 Additional Information Supporting Request for License Amendment Regarding A-6 Byron SSER 7, NRC Report No. NUREG-76, Supplement No.7, Safety Evaluation Measurement Uncertainty Recapture Power Uprate," dated November 1, 2011 Report related to the operation of Byron Station, Units 1 and 2, Docket Nos. STN

[RS 11-169]

50-454 and STN 50-455, November 1986 A-3 A-7 Letter fromSSER Braidwood Kevin2,F.NRC Borton (Exelon Report No. Generation NUREG-1002, Company, LLC) to Supplement U. S.Safety No.2, NRC, "

Additional Information Supporting Request for License Amendment Evaluation Report related to the operation of Braidwood Station, Units 1 and 2,Regarding Measurement Docket Uncertainty Nos. 50-456 Recapture and 50-457, Power October Uprate," dated December 9, 2011 1986.

[RS 11-178] [ML113430811 ]

A-8 Byron/Braidwood Updated Final Safety Analysis Report (UFSAR). Revision 14, A-4 Letter from2011 December Kevin F. Borton (Exelon Generation Company, LLC) to U. S. NRC, "Additional Information Supporting Request for License Amendment Regarding A-9 Regulatory Measurement Guide 1.46, "Protection Uncertainty RecaptureAgainst PowerPipe Whip dated Uprate," InsideApril Containment" 27, 2012 A-10 A.[RS 12-047] [ML12121A496]

Giambusso Letter, December 1972 A-5 A-11 WCAP-10961 NRC's letter fromRevision 1, Steamline J.F. O'Leary, datedBreak Mass /Energy Releases for Equipment July 1973 Environment Qualification Outside Containment, October 1985 A-12 BTP APCSB 3-1, "ProtecflOn Aga'inst Postulated Piping Failures in Fluid System A-6 Byron SSER 7, NRC Report No. NUREG -76, Supplement No. 7, Safety Evaluation Outside Containmenf' Report related to the operation of Byron Station, Units 1 and 2, Docket Nos. STN A-13 50-454 BTP MEB and3-1, STN"Postulated Rupture Locations 50-455, November 1986 in Fluid System Piping Inside and A-7 Outside Containment" Braidwood SSER 2, NRC Report No. NUREG-1002, Supplement No. 2, Safety Evaluation A-14 Point BeachReport related SER, Point to theNuclear Beach operation of Braidwood Plant Station, (PBNP), Units 1 and Units 1 and 2, of 2 -Issuance Docket Nos. 50-456 and 50-457, October 1986.

License Amendments Regarding Extended Power Uprate, dated May 3,2011 A-8 A-15 Byron/

10 CFR Braidwood Updated FinalQualification 50.49, "Environmental Safety Analysis ReportEquipment of Electric (UFSAR), Important Revision 14, to December 2011 Safety for NUClear Power Plants" A-9 A-16 Regulatory Regulatory Guide Guide 1.46, 1.89, "Protection Against "Environmental Pipe WhipofInside Qualification Containment" Certain Electric Equipment Important to Safety for Nuclear A-10 A. Giambusso Letter, December 1972 Power Plants" A-11 N RC's letter from J.F. O'Leary, dated July 1973 A-12 BTP APCSB 3-1, "Protection Aga'mst Postulated Piping Failures in Fluid System Outside Containment" A-13 BTP MEB 3-1, "Postulated Rupture Locations in Fluid System Piping Inside and Outside Containment" 24 A-14 Point Beach SER, Point Beach Nuclear Plant (PBNP), Units 1 and 2 - Issuance of License Amendments Regarding Extended Power Uprate, dated May 3, 2011