RS-13-227, Response to NRC HELB Audit Request for Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate

Response to NRC HELB Audit Request for Information Supporting Request for License Amendment Regarding Measurement Uncertainty Recapture Power Uprate

ML13248A519
Person / Time
Site:	Byron, Braidwood
Issue date:	09/05/2013
From:	Gullott D Exelon Generation Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
RS-13-227, TAC ME6587, TAC ME6588, TAC ME6589, TAC ME6590
Download: ML13248A519 (8)

Text

1 Genera ti RS-13-227 RS-13-227 10 10 CFR CFR 50.90 50.90 September 5, September 5, 2013 U. S. Nuclear Regulatory U. Regulatory Commission Commission ATTN: Document Document Control Control Desk Washington,DC Washington, DC 20555-0001 Braidwood Station, Units 11 and 2 Braidwood Facility Operating Facility Operating License License Nos.

Nos. NPF-72 and NPF-77 NRC Docket Nos.

NRC Nos. STN 50-456 and STN 50-457 Byron Station, Byron Station, Units 1 and 2 FacilityOperating Facility Operating License License Nos.

Nos. NPF-37 and NPF-66 NPF-66 NRC Docket NRC Docket Nos.Nos. STN STN 50-454 and STN STN 50-455 50-455

Subject:

Response to NRC HELB Audit Request for Information

Response

Supporting Supporting Request for tor License Amendment Regarding Measurement Measurement Uncertainty Recapture Uncertainty Recapture Power Uprate

References:

1. Letter Letter from from Craig Craig Lambert Lambert (Exelon (Exelon Generation Generation Company, Company, LLC) LLC) to U. S. NRC, U. NRC, "Request "Request for License Amendment Amendment Regarding Regarding Measurement Uncertainty Uncertainty Recapture Power Power Uprate,"

Uprate," dated June 23,23, 2011 2011[ML1 1 1 790030]

[ML111790030]

2. Letter fromJ.J. S.

Letter from S. Wiebe (U.

(U. S. NRC)

NRC) to M. M. J. Pacilio (Exelon (Exelon Generation Company, LLC), "Byron Station, Unit Unit Nos.

Nos. 1 and 2, and and Braidwood Station, Units 11 and Braidwood and 22 --Request Requestfor forAdditional AdditionalInformation Information Suspension of and Suspension of Review Review of of License LicenseAmendment Amendment Request Requestfor for Power Power Uprate (TAC Nos. ME6587, ME6588, ME6589, ME6589, and and ME6590),"

ME6590)," dated December December 6, 2012 [ML12271A308]

6,2012 [ML12271A308]

3. Letter from David Letter from David M.M. Gullott Gullott(Exelon (Exelon Generation Generation Company, Company, LLC) to

u. S. NRC, U. NRC, "Additional InformationSupporting "Additional Information SupportingRequest Request for for License License Amendment Regarding Measurement Uncertainty Regarding Measurement Uncertainty Recapture Power Power Uprate," dated July Uprate," dated July5,2013 5, 2013 [RS 13-13-189] [ML13186A178]

189] [ML13186A178]

4. E-Mail from J.S.Wiebe(U.

E-Mail from J. S. Wiebe (U. S. NRC)NRC) to David David M.

M. Gullott Gullott (Exelon (Exelon Generation Company, Company, LLC), "Preliminary "Preliminary RAI RAI Regarding TB TB Bldg Bldg HELB,"

HELB," dateddatedAugust August 29, 29, 2013 2013 In Reference 1,1 , Exelon Generation Company, LLC (EGC)requested LLC (EGC) requested an amendment amendment to to Facility Operating License Nos. NPF-72, NPF-77, Facility Operating NPF-77, NPF-37 NPF-37 and andNPF-66 NPF-66for for Braidwood Braidwood Station, Units 1 and 2, andand Byron Byron Station, Units Units 11 and and 2, 2, respectively.

respectively. Specifically, Specifically,thethe proposed changes changesrevise revisethetheOperating OperatingLicense Licenseand andTechnical Technical Specifications Specifications to to implement an increase increase in in rated rated thermal thermal power power of of approximately 1.63% based based on on increased feedwater flow measurement increased feedwater flow measurement accuracy. accuracy.

In Reference Reference 2,2, the theNRC NRCrequested requestedadditional additionalinformation information(RAI)

(RAI)pertaining pertainingtotothetheHigh High Energy Line Line Break (HELB) analysis and an audit (HELB) analysis audit toto complete complete their their detailed detailedreview review ofof the the

September 5, September 5, 2013 2013 U.S. Nuclear U.S. Nuclear Regulatory Regulatory Commission Commission Page 22 Page power uprate.

power uprate. The The response responseto tothis thisRAI RAI was was provided provided in in Reference 3. On On July July 17 17 and and 18, 2013 18, 2013 the NRC NRC conducted the audit. audit. As Asfollow-up follow-up to to this audit, audit, in in Reference Reference 44 the the NRC requested NRC requested additional information information regarding the the assumed assumedTurbineTurbineBuilding BuildingHELB HELB break locations.

break locations. The response responseto tothis thisrequest requestisisprovided provided in in the the Attachment.

Attachment.

EGC has EGC has reviewed the the information information supporting aa findingfinding of no significant hazards hazards consideration and the the environmenta environmentall consideration consideration provided provided to to the the NRC NRC in in Reference Reference1.1.

The additional The additional information informationprovided providedininthisthissubmittal submittaldoes does not not affect affectthe the bases bases for concluding that concluding that the the proposed license amendment amendmentdoes doesnotnotinvolve involve aasignificant significant hazards hazards consideration. Furthermore, consideration. Furthermore,the theadditional additionalinformation information provided provided in in this submittal does does not affect not affect the the bases bases for concluding concluding that neither an environmenta environmentall impact statement impact statement nor nor an environmenta an environmentall assessment assessment needsneedsto to be beprepared preparedininconnection connection with with the proposed amendment.

There are no regulatory commitments contained in in this letter.

letter.

Should youyou have any questions questions concerning concerning thisthis letter, letter, please pleasecontact contactLeslie E. Holden Leslie E. Holden at at (630) 657-3316.

(630)

II declare declare under penalty of perjury perjury that that the the foregoing foregoing isis true true and and correct. Executed on correct. Executed on the the 51hth day 5 day ofofSeptember September 2013.

Respectfully, David M. Gullott Gullott Manager -

Manager - Licensing Licensing

Attachment:

Response

ResponsetotoNRC NRCRequest Requestfor forAdditional AdditionalInformation Information (Non-Propriet (Non-Proprietary)ary)

ATTACHMENT RESPONSE TO RESPONSE TO NRC NRC REQUEST FOR FOR ADDITIONAL INFORMATION 5, 2013 September 5,2013 (NON-PROPRIETARY)

Braidwood/Byron Braidwood/Byron Stations Stations MURMUR LARLAR Response to Response to RAI RAI September September 5, 5, 2013 2013 Attachment, Attachment, page page 1 NRC Request NRC Request According to Byron According Byron and Braidwood (BIB) UFSAR Section 3.6, piping piping failures failures postulated postulated inin BIB B/B include include high high energy energy (HE) line breaks (HELBs), HE line cracks (HELCs) and and moderate energy moderate energy lineline cracks (MELCs).

(MELCs).

Withregard With regardtotopostulated postulatedpiping pipingfailures, failures,BIB-UFSAR B/B-UFSARSection Section3.6 3.6states states that:

that.

The effects The effects ofof high high energy energy line line breaks breaks in in the the turbine turbine building have been evaluated with respect with respect to to potential potential impact impact on on safety-related safety-related equipment equipment located in in adjoining auxiliary building rooms.

auxiliary and that:

and that.

The possible The possible effects effects associated associated with with the the postulated postulated break of piping considered are loads due structural loads due to to pressurization, pressurization, increases in pressure and and temperature which which could affect environmental could environmental qualification of equipment, and and damage due to to pipe pipe whip whip and jet impingement.

B/B-UFSAR Section 3.6.1, Postulated Piping Failures in Fluid BIB-UFSAR Fluid Systems Outside Outside the the Containment, provides the criteria for postulating locations of Containment, of piping failures (HELBs, HELCs and MELCs) MELes) outside containment.

Describe in detail the postulatedpostulated piping piping failures failures andand their locations utilized their locations utilized for the analyses of analyses ofM&E release from piping located M&E release located in in the the turbine turbine building building thatthat could could affect affect safety-related equipment located safety-related located in in adjoining adjoining auxiliary auxiliary building rooms rooms and andhowhowthisthis information was used to provide input input to to the the Gothic Gothic analysis.

analysis. ifIf bounding bounding conditions conditions have been been utilized utilized for thesethese analyses analysesidentifyidentifythe thepiping pipingfailures failuresutilized, utilized,their their bounding bounding M&E M&E and andthethebounding boundinglocations locations thatthat would wouldenvelop envelop the the resulting effects effects on on the the safety safety--

related equipment located located in in adjoining adjoining auxiliary auxiliary building rooms. In Inaddition, addition,justify justifyhowhow this/ these M&Es this/these M&Es and andlocation(s) location(s) bound bound others.

others. This This justification should should include, include, but but is not not limited to, consideration considerationof ofaaHE HErelease releasenear nearaaHELBHELB damperdamperthat that would wouldallow allow pressurization of of a room while the damper is closing while is closing while another another room is not not yet pressurizing pressurizing because becauseits itsdamper damperisisfarther fartheraway awayfrom from thethe HEHE release, thereby creating aa thereby creating differential pressure across differential pressure across thethe wall wall that separates separates the the two two rooms.

Response

As As discussed discussedon onJuly July17, 2013 during 17,2013 duringthe theaudit, audit,the theTurbine Turbine Building Building(TB)(TB)HighHighEnergy EnergyLine Line Break (HELB) mitigationstrategy (HELB) mitigation strategyandand associated associated methodologies methodologies were wererevised, revised,and andaanewnewTB TB HELB analysis was performed HELB analysis performed to to address addressthe theAuxiliary AuxiliaryBuilding Building (AB) rooms/areas impacted (AS) rooms/areas impactedby by TB TB HELBs.

HELBs. However, However, the the overall overall equipment equipment qualification qualification design bases baseswereweremaintained maintained(i.e.,(i.e.,

the the qualification qualification of Class Class 11E electrical electrical equipment in the identified identified AB rooms/areas are AB rooms/areas arenot not adversely adverselyimpacted impactedby byaaTB TBHELB).

HELB). The Thenew newTB TBHELB HELBanalysis analysisconfirms confirmsthat thatthe theadjacent adjacentAB AB rooms/areas rooms/areasare aremaintained maintainedasasmild mildEnvironmental EnvironmentalQualification Qualification(EQ) (EQ) environments environmentsbased basedon on the thebounding boundingTB TBHELBs.

HELBs.

The The Byron Byron andand Braidwood Braidwood UpdatedUpdatedFinal FinalSafety SafetyAnalysis AnalysisReportReport(UFSAR)

(UFSAR)does doesnotnotexplicitly explicitly identify identify or discuss the the locations locations of of the the TBTB HELBs HELBs that need need to to be be considered consideredororanalyzed analyzedfor for their their environmental environmental impacts on the safety-related safety-related equipment equipment in in the the adjacent adjacentAB AB rooms/areas.

rooms/areas.

As As part part of of our efforts to to evaluate and resolveresolve thethe non-conformances non-conformancesassociated associatedwith withthe theexisting existing TB TB HELB HELB analysis, EGC reviewed the existing existing analysis analysis and anddetermined determinedthat thatadditional additionalline line breaks breaksshould shouldbe beconsidered consideredfor forconservatism conservatismand andtotoverify verifythat thatthethepostulated postulatedbreaksbreaksininthethe new new TBTB HELB HELB analysis would would be bounding. For ForthethenewnewTB TBHELB HELB analysis, analysis, breaks breakswerewere chosen chosenbasedbasedon onthetheresulting resultingseverity severityof ofthe thebreak break(i.e.,

(i.e.,highest highestenergy energyrelease) release)and andnotnotthe the

Braidwood/Byron Braidwood/Byron Stations MUR LAR Response to RAI

Response

September 5, 2013 September Attachment, page Attachment, page 2 potential of potential ofthe the pipe pipetoto break break (Le.,

(i.e., piping pipinganalysis analysisresultsresultswerewere not not used used to to determine determine break locations).

locations) .

In order In order to to determine determine and and verify verify that that the the bounding bounding conditions conditions have have been properly properly identified, identified, aa broader spectrum of line broader line breaks than previously considered were postulated for each elevation, elevation, conservative mass conservative mass andand energy energy(M&E) releases were (M&E) releases were determined determined for for the postulated postulated line line breaks, breaks, and evaluations were performed to determine how the postulated breaks breaks would would impact impact the environmental parameters environmental parameters in in the the adjacent AB AB rooms/areas.

rooms/areas. Consideration Consideration of this this broader spectrum of TB TB pipe pipe breaks, along with with maximizing maximizing the the M&E M&Ereleases, releases, provides provides assurance assurance that that the most challenging environments environments for for the safety-related safety-related equipment equipment in in the the adjacent adjacentAB AB rooms/areas are are determined.

determined. The Themethods methodsemployedemployedare arebriefly briefly discussed discussedbelow. below.

Postulated Bounding Line Breaks The new TB HELBanalysis TB HELB analysis considered considered a broad spectrum spectrum of of main main steam steam(MS) (MS) lineline breaks breaksand and high energy liquid high linebreaks liquid line breaks in in the the TB.TB. The breaksbreaks specifically specifically analyzed analyzed resulted resulted in in the thehighest highest combination of combination of mass mass flow rates and enthalpies, flow rates enthalpies, which which in in turn resulted in in the highest highest temperatures in temperatures in the TB and adjacent AB rooms/areas. The AB rooms/areas. The bounding bounding line line breaks breaks used usedin in the the new TB HELB HELB analysis analysis areare shown shown in in Table TableA.1. A.1.

fullyassess To fully assess what breaksbreaks would would be bounding,bounding, MS MS breaks from from the largest to the smallest smallest line line size were considered considered for for each each elevation elevation of of the TB.TB. The Thelargest largestMS MS line line break break sizesize analyzed analyzedwas was limited to limited to 1.4 1.4 ft2 ft2due duetotothe theintegral integralflow flowrestrictors restrictorsininthe thesteam steamgenerators.

generators. The smallest smallest MS MS line break line break size analyzed was 0.3 0.3 ft2,ft2 , since since the massmass flow flow rates for for this this break break represent the lowest mass mass flow flow rates for for the smallest smallest steam line and liquid line breaks considered steam line and liquid line breaks consideredininthe theTB. TB.

Additionally, Additionally, the the 0.3 0.3 ft2 ft2break breakisisthe the smallest smallest MS MS line line break break that that would would result result inin an an automatic reactor trip that requires actuation of of the safety-related safety-related equipment equipment in in adjacent adjacentAB AB rooms/areas.

rooms/areas.

Intermediate break sizes sizes werewereconsidered consideredand anda abreak breaksize sizeofof0.50.5ft2feconcurrent concurrentwith withaalosslossofof offsite power power (LOOP)

(LOOP)was was determined determined to be the limiting intermediate break.

limiting intermediate break. ThisThis break break size size results in in the maximum maximum TB pressure pressure occurringoccurring as as thetheAB AB rooms rooms fans fans attempt attemptto tostart startwhen whenthe the EDG EDG starts, resulting in a high differential differential trip. trip. This This scenario scenario represents representsthe thehighest highestM&E M&E release release associated associatedwith withthe thelongest longesttime timethat thatthetheAB ABroomroomventilation ventilation is is not not operating, operating, whichwhich in in turn leads to to the the highest highest roomroom temperatures.

temperatures.

These These three three MS MS main main steam steam lineline breaks breaks are are postulated postulated to to occur occur on on each eachTB TB elevation elevation that communicates with with an adjacent adjacent AB AB room/area (401', 426' and 451' elevations). elevations).

The liquid lines breaks liquid lines breaks evaluated represent represent the the liquid liquid lines on each each elevation elevation that that produce produce the the highest combination of of mass flow flow ratesrates and enthalpies. Although Although these thesebreaksbreaksdo donot notresult resultinin higher enthalpies enthalpies than than the theMS MS lineline breaks, breaks,they theymay mayresultresultininhigher highermass massflow flowrates, rates,which whichinin some some cases casesresultresultininfaster fasterinitial initial temperature temperature increasesincreasesininthe theTB TBandandadjacent adjacentAB AB rooms/areas.

M&E Releases Releases to to Maximize Maximize TB TB Environmental EnvironmentalConditions Conditions For each each MS MS line line break break analyzed analyzed in in the the new newTB TB HELBHELB analysis, the transient transient M&E releases M&E releases consistent consistent with with Westinghouse Westinghouse WCAP-10961, WCAP-10961 , "Steamline "Steam line Break Break Mass/Energy Mass/Energy Releases Releasesfor for Equipment Environment Qualification Environment Qualification Outside Containment," (Reference (Reference A.1) A.1) were used.

used.

Specifically, the Westinghouse Westinghouse transient transientM&E M&E releases releasesinvolve involveprogressively progressivelyincreasing increasing enthalpies enthalpies with with progressively progressively decreasing decreasingmass massflow flowrates ratesand andconservatively conservativelymaximize maximize enthalpies enthalpiesto tomaximize maximize the theeffect effectof of M&E releases on M&E releases onenvironmental environmentalqualification qualification of of equipment equipment

Braidwood/Byron Braidwood/Byron Stations MUR LAR

Response

Response to to RAI RAI September September 5, 5, 2013 2013 Attachment, Attachment, page page 33 located outside located outside containment.

containment. Westinghouse Westinghouse transient transient M&E M&Ereleases releases werewere developed developed to to bound bound Byron and Braidwood Stations, Units 1 and 2, and include Byron and Braidwood Stations, Units 1 and 2, and include additional conservatisms. additional conservatisms. The Westinghouse approach has Westinghouse has been beenapproved approvedfor forByron Byron andand Braidwood Braidwood Stations Stations by by the the NRCNRC for for maximizingthe maximizing the effect effect of ofM&E M&Ereleases releases on on environmental qualification of equipment equipment located located outside containment (References outside (References A.2, A.2, p. p. 3-4 3-4 and and A.3,A.3, p.p. 3-18).

3-18).

For each For each liquid liquid line linebreak breakevaluated, evaluated, constant constant M&E M&Ereleases releases based based on the choked choked mass massflow flow rate (Henry-Fauske Critical rate Critical FlowFlow Model)

Model)and and initial initialenthalpy enthalpywerewere used used with with one one exception; pump runout pump runout was credited for for the the FW FW lineline breaks.

breaks. Additionally, Additionally, enthalpies were conservatively conservatively maximized. Table A.1 maximized. A.1 shows the constant constant M&E releases used M&E releases usedforfor the the bounding bounding breaks.

breaks.

Specifically, ititshows Specifically, shows the the portion portion of of the the break break M&EM&Ereleasesreleases that flash to steam steamininthe theTB TB environment and environment and werewere analyzed for for the the effects effects on on the adjacent AB areas.

AB areas.

Differential Pressure Between AB Rooms Differential divisional block The divisional block walls walls (e.g.,

(e.g., walls walls between between the DivisionDivision 11 11(21)

(21) and Division 12(22) ESF Division 12(22) equipment), between the the ABAB rooms adjacent adjacent to to the the TB, TB, have havebeenbeenevaluated evaluatedfor forthe thedifferential differential pressure that pressure that may mayexistexistfollowing following a TB HELB. HELB. The The two two divisional divisional ABAB rooms are adjacent adjacentto to each other other and and each eachpairpairof of rooms roomscommunicates communicateswith withthethesame sameTB TBelevation elevationHELB HELB environment. FollowingFollowing aa TB TS HELB, HELS, the the TB TB pressurizes, pressurizes, drives drivesflow flow into into the AB AB rooms, and and pressurizes the pressurizes the ABAB rooms for for a short short time time until HELBdampers until HELB dampers between the the TB TB and and AB AB rooms close. By By applying applying the the lumped-parameter lumped-parameter (i.e., (i.e., lumped lumped volume) volume) modeling modeling in in the the GOTHIC GOTHIC analysis, the the pressurization pressurizationof ofthe theTBTB elevation elevationisisuniform; uniform; therefore thereforethe theTB TBHELBHELB environment environment outside eacheach of of the AB rooms was calculated to be the same.

AB rooms same.However, However,differential differential pressurization was calculated between between the the AB AB rooms due due toto variations variations in in the closure characteristics characteristics of of the the HELB dampers, as HELB dampers, aswell well as asdifferences differencesininAB ABroomroomvolumes volumesand andflow flow paths.

paths. InInparticular, particular,the theclosure closuretimetimeofofthe theHELB HELBdamper damperofofthe theABABroomroomfor forone onedivision divisionwas was maximized, while the closure time of the HELB damper to the AB room closure time of the HELB damper to the AB room for other division was for other division was minimized.

minimized. This results in in one one ABAB room roomreaching reachingaahigher higherpeak peak pressure pressure than the adjacent room, creating a differential pressure across differential pressure acrossthe thedivisional divisional block block wall.

wall. TheTheloadloaddueduetotothisthis differential pressure has differential pressure has been beenaccounted accountedfor forininthe thenew newdesigns designstotoreinforce reinforcethe thedivisional divisionalblockblock walls.

IfIf one divisional divisional AS AB roomroom werewere postulated postulated to to experience higher higher TB pressure pressureoutsideoutsidethe theroom, room, the the higher higher TBTS pressure pressure wouldwould result result inin higher higher differential pressure across differential pressure acrossthe theHELB HELSdamper.

damper.

The dampers dampers are are designed designedto toclose closefaster fasterwithwith increasing increasing differential pressure. The differential pressure. Thepeakpeak pressure pressure in in the the AB room would AS room wouldbe be expected expected to to be be thethe same as as analyzed analyzed due dueto tothe thefaster faster damper damper closure closure time.

time. Therefore, Therefore, basedbasedon onengineering engineeringjudgment, judgment,the theimpact impactof of aapostulated postulated higher pressure pressure outside outside one one AB AB room would would be be encompassed encompassed by by the the HELB HELB damper response response times analyzed, analyzed, (i.e.,(Le., one damper damper closes closesat atthe theminimum minimum time verses verses the the other other damper dampercloses closesatat the the maximum maximumtime). time).

Braidwood/Byron Braidwood/Byron Stations Stations MUR MUR LAR

Response

Response to to RAI September September 5,2013 5, 2013 Attachment, Attachment, page page 4

REFERENCES:

A.1 A.1 Westinghouse Report No. WCAP-10961, Westinghouse WCAP-10961, "Steamline "Steamline Break Break Mass/Energy Mass/Energy Releases Releases for Equipment Environment Equipment Environment Qualification QualificationOutside Outside Containment,"

Containment," Rev.

Rev. 1, October 1985 1985 A.2 A.2 NRC Report NRC Report No.

No. NUREG-76, NUREG-76, Supplement Supplement No. 7, "Safety Evaluation Report related No.7, related to to the the operation of Byron Station, Units operation of Byron Station, Units 1 and 2, Docket Nos. STN 50-454 and STN 50-455,"

Docket Nos. STN 50-454 and STN 50-455,"

November 1986 November A.3 NRC Report NRC Report No.

No. NUREG-1002, NUREG-1002, Supplement Supplement No. 2, "Safety No.2, "Safety Evaluation Evaluation Report Report related related toto the operation of Braidwood Station, Units Braidwood Station, Units 1 and 2, Docket Nos. 50-456 and 50-457,"

50-457,"

October 1986

Braidwood/Byron Braidwood/Byron Stations MU R LAR Stations MUR LAR Response to RAI Response to RAI September 5,2013 September 5, 2013 Attachment, Attachment, page 5 TableA.1:

Table Al: Bounding Turbine Bounding Turbine Building Building HELBs HELBs Initial Mass Initial Mass Flow Flow Rates Rates and and Enthalpies Initial Initial Initial Initial Steam Steam Initial Initial Steam Steam Line Line Enthalpy Enthalpy Mass Mass Flow Rate TBB ine Line Enthalpy' Enthalpyf inTB in TB inTB in TB EL. Type El. Ty p e inett Line (Btu/Ibm)

(Btu/Ibm) (Btullbm)

Btu/lbm (Ibm/sec)

Ibm/sec 451 Steam 451 Steam 1.4 te 1.4 ft 2 MS MS 1199.3 1199.3 1199.3 1199.3 2,730 0.5 ft 2 MS 0.5 ft~ MS 1199.3 1199.3 1199.3 1199.3 1,027 1,027 0.3 ft~

0.3 MS ft MS 1199.3 1199.3 1199.3 1199.3 621.7 Liquid 26" HD 353.8 1149.8 5,154 2

426 Steam 1.4 tt ft2 MS 1199.3 1199.3 2,730 ft 2 MS 0.5 ft~ 1199.3 1199.3 1,027 ft2 MS 0.3 ft2 1199.3 1199.3 621.7 Liquid 20" HD 352.4 1149.8 2,949 401 Steam 1.4 1.4 ft~ MS ft MS 1199.3 1199.3 2,730 ft2 0.5 tt 2 MS 1199.3 1199.3 1,027 0.3 ft2 MS 1199.3 1199.3 621.7 Liquid 30"FW 430.0 1149.8 1149.8 2,398 conservatism, the enthalpies

• For conservatism, enthalpies for for steam steam line line breaks breaks are are increased by -0.78%

-0.78% toto reflect reflect Westinghous Westinghouse NSSS design e NSSS design parameters.

ft Acronyms:

MS - Main Steam Steam HD - Heater Heater drain drain Feedwater FW - Feedwater