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| issue date = 10/31/1988
| issue date = 10/31/1988
| title = Reduced Temp & Pressure Operation for Donald C. Cook Nuclear Plant Unit 1 Licensing Rept, Including FSAR mark-ups
| title = Reduced Temp & Pressure Operation for Donald C. Cook Nuclear Plant Unit 1 Licensing Rept, Including FSAR mark-ups
| author name = AUGUSTINE D B, CECCHETT D L
| author name = Augustine D, Cecchett D
| author affiliation = WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
| author affiliation = WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
| addressee name =  
| addressee name =  
Line 17: Line 17:


=Text=
=Text=
{{#Wiki_filter:MESTINGHOUSECLASSIIIHCAP-11902REDUCEDTEMPERATUREANOPRESSUREOPERATIONFORDONALDC.COOKNUCLEARPLANTUNIT1LICENSINGREPORT0.L.Cecchett0.B.AugustineOctober1988eWESTINGHOUSEELECTRICCORPORATIONEnergySystemsBusinessUnitP.O.Box355Pittsburgh,Pennsy1vania15230pop/g/'980a:1d/100588 cumulativefatigueusagefactorwascalculatedtobe0.69whichislessthanthe1.0Codelimit.Thisvalueincludesthethermalstressduetothenon-linearportionofthethermalgradientforconservatism.Asubstantialreductioninthemaximumrangeofstressintensitycouldbeachievedifthenon-linearthermalgradientcontributionwereneglectedaspermittedbytheASHECode.3.10.1.2ReactorVesselIntegrityAnevaluationoftheimpactofreratingonreactorvesselintegrityforneutronembrittlementwasperformed.Neutronfluencechangesforthereratingwerecalculated.Usingtheserevisedfluencesandthosefromotherrelevantsystemsparametersassociatedwiththererating,theassessmentincludedreviewofsurveillancecapsulewithdrawalschedules,thescheduleofapplicabilityoftheplantheatupandcooldownlimits,and10CFR50-~~~~~~~~~~~~AppendixGanalyses,includingaverificationofplantspecificmaterialproperties.ArevisiontothecalculationsusedinthesubmittaltotheNRCformeeting-therequirementsofthepressurizedthermalshock(PTS)rulewereperformed.Finally,aninitialevaluationoftheimpactofreratingonthePTSriskofvesselfailurewascarriedouttoconfirmtheapplicabilityofthescreeningcriteriainthePTSrulefortheCookNuclearPlantreactorvessels.ThereratingaffectsthePTStransientinitiatingtemperaturewhichislowerthanthatusedinthegenericPTSriskanalyseswhichsupportthescreeningcriteria.~Neutrontransportcalculationshavebeencompletedataconservativelyhighpowerlevelof3600HWt,andreducedtemperature/pressureconditionsforCookNuclearPlantUnit1.Resultsoftheseanalyseshaveindicatedthatinadditiontotheincreasedreactorpower,operationoftheunitswithreducedcoolanttemperatures,particularlyinthedowncomerregions,alsohasasignificantimpactonthefastneutronexposureratesincidentonthepressurevessel.Alsoimpactedaretherelationshipsamongtheneutronexposureratesatsurveillancecapsulelocationsandthoseatpositionswithinthepressurevesselwall;i.e.,capsuleleadfactors.Agd~~9tzpgQg78739a:1d/0929883.10-5  
{{#Wiki_filter:MESTINGHOUSE CLASS  III HCAP-11902 REDUCED TEMPERATURE ANO PRESSURE  OPERATION FOR DONALD  C. COOK NUCLEAR PLANT UNIT 1 LICENSING REPORT
~I Toprovideaboundingevaluationofthesevariouseffects,calculationswereperformedforthecurrentlicensedconditionsaswellasforupratedpowerwithbothmaximumandminimumdowncomertemperatures.TheresultsofthesestudiesaresummarizedinTables3.10.1-1and3.10.1-2.AnexaminationofTables3.10.1-1and3.10.1-2showsthattheimpactofhigherpoweroperationandchangedcoolanttemperaturesisgreaterontheabsolutemagnitudeoftheneutronexposureratethanontherelativebehaviorofneutronfluxdistributionsasreflectedincapsuleleadfactors.TwosetsofdatahavebeenprovidedtoestablishupperandlowerboundexposuresforCookNuclearPlantUnit1.Theupperlimitconditionsareconsistentwithassuminganupratingattheonsetofthenextfuelcyclewithcontinuedoperationataninlettemperatureof547'Fforunit1.Lowerboundfluenceestimateswerebasedonnoupratinginpowerlevel,butwithfutureoperationoccurringatreducedT;i.e.,theinlettemperaturewasassumedavg'obe512'F.Theselowerboundfluenceestimatesarelowerthanthoseatcurrentoperatingconditions.ReviewoftheheatupandcooldowncurvesthatwerepreviouslygeneratedbySouthwestResearchInstituteindicatethatthesecurvesweregeneratedinaccordancewithRegulatoryGuide1.99-Revision1.PerNRCGenericLetter88-11,datedJuly12,1988,allutilitiesmustsubmittotheNRCbyNovember1988theresultsoftheirtechnicalanalysisrelativetotheimplementationofRegulatoryGuide1.99-Revision2,whichwasofficiallyissuedinMay1988.Giventhisregulatorychange,theeffectofreratingshouldbeincorporatedIIintofuturecalculationsthatwillbeperformedforrevisingheatupandcooldowncurvesinaccordancewiththislatestrevisionofRegulatoryGuide1.99.Theeffectofthereratingisdeemedtonotbesignificant.Thechangesinthesystemsparametersassociatedwiththereratinghavebeenjudgedtonothaveanysignificantimpacton10CFRPart50-AppendixGanalysis.8139e:1d/0930883.10-6IZpa~+g7 S
: 0. L. Cecchett
TheCookNuclearPlantUnit1reactorvesselbeltlineregionmaterialpropertieswereverifiedagainstthelatestavailableinformationinvariousindustrydata.basesandsurveillancecapsulereports.ThepropertiesdefinedfromthelatestinformationareconsistentwiththoseusedinpriorutilitysubmittalstotheNRCrelativetomeetingtherequirementsofthePTSrule.SincethecoreloadingpatternwiIIbechangingasaresultofthererating,anupdatetothePTSsubmittalwillberequiredasstatedinthePTSRule.RevisedcalculationswereperformedforthereratingusingthecurrentPTSRulemethodologyandthelatestprocedurespecifiedbyRegulatoryGuide1.99-Revision2.AsstatedinNRCGenericLetter88-11,thestaffispresentlyconsideringanamendmenttothePTSRule,10CFR50.61,thatwillreplacetheequationsforRTptsgiveninparagraph(b)(2)withthecalculationprocedureinSectionC.lofRevision2toRegulatoryGuide1.99,buttheywillnotchangethescreeningcriteria.AlltheRTptsvaluesremainbelowtheNRCscreeningvaluesforPTSusingtheprojectedfluencevaluesthatarebaseduponreratedconditionsthroughthelicenseexpiration.ThehighestRTptsvalue(265'F)wascalculatedatthecircumferentialweldoftheCookNuclearPlantUnitIreactorvessel,usingthemethodologyofRegulatoryGuide1.99Revision2.OnthebasisofprobabilisticworkdescribedinthePTSRule,theNRCstaff'oncludedthatPHRvesselswithconservativelycalculatedvaluesofRTndt(i.e.,RTpts)lessthan270'Fforplatematerialandaxialwelds,andlessthan300'FforcircumferentialweldspresentanacceptablylowriskofvesselfailurefromPTSevents.Thisevaluation,however,didnottakeintoaccounttheimpactofrerating,whichcausespotentialPTStransientscenariostobeginfromalowersystemtemperature.81390:1d/0929883.10"7 Aninitialevaluationwasperformedtodeterminetheimpactofreratingonthe~~~~~~~applicabilityofthePTSscreeningcriteriaintermsofriskofvesselfailure.AprobabilisticfracturemechanicssensitivitystudyoflimitingPTStransientcharacteristics,startingfromaloweroperatingtemperature,showedthattheconditionalprobabilityofreactorvesselfailurewillnotbeadverselyaffected.Therefore,theoverallriskofvesselfailurewillnotbeadverselyimpactedmeaningthatthatthescreeningcriteriainthePTSRulearestillapplicablefortheCookNuclearPlantUnit1reactorvesselrelativetoreratedconditions.813S@:Id/0929883.10-8 TABLE3.10.1-1FASTNEUTRON(E>1.0MeV)FLUENCEPROJECTIONSFORCOOKNUCLEARPLANTUNIT1Unit122.89EFPYAllplates;Weld9-442Welds2-442B,2-442C,3-442A,3-442CUerBound1.84x101.19x10LowerBound1.55x101.01x10Weids2-442A,3-442B5.92x105.01x108139e:1d/0929883.10-9 I
: 0. B. Augustine October 1988 WESTINGHOUSE ELECTRIC CORPORATION Energy Systems Business Unit P.O. Box 355 Pittsburgh, Pennsy1vania 15230 e                                                pop    /g
TABLE3.1.0.1-2SURVEILLANCECAPSULELEADFACTORSFORCOOKNUCLEARPLANTUNIT14'aosules40'apsulesUnit1BaseCase(3250Wt,536'FDowncomer)1.34.2Unit1AtUpratedPower(3588HMt,547'FDowncomer)1.34.2Unit1AtUpratedPower(3588HMt,512'FDowncomer)1.34'8139e:1d/0929883.10"10pffQQIPNCJtjI2PV~<7 E
                                                              /'980a:1d/100588
TABLE4.1-1SYSTEMDESIGNANDOPERATINGPARAMETERSiPlantdesignlife,yearsNumberofheatcransferloopsDesignpressure,psigNominaloperatingpressure,psigTocalsystemvolumeincludingpressurizerandsurgeline(ambientconditions),ft(estimated)3Systemliquidvolume,includingpressurizerandsurgeline(ambientconditions),fcSystemliquidvolume,includingpressurizer3max.,guaranteedpower,fc(escimac'ed)TocalReactorheatoutput(100%power)Btu/hr402485223512,50011,89211,78011,089x10(Unit1)6(3250MVt)11,641x10(Unit2)6(3411HPt)Unit1BoundingConditionsforReracingLower/UpperUnit2Reactorvesselcoolanttemperatureatfullpower:Inlet,nominal,F0Outlet,nominal,F0Coolanttemperatureriseinvessel0acfullpower,avg.,FTotalcoolantflowrace,lb/hrx106Sceampressureacfullpo~er,psiaSteamTemp.Qfullpower,FTotalReactorCoolantVolumeatambientcondicions,ft3514.9/545.2579.1/607.564.2/62.3139.0/133.9618/820489'/521.112,438541.3606.464.8134.6820521.112,4704.1-25July1990}}
 
c umulative  fatigue  usage factor was  calculated to be 0.69 which  is less than the 1.0 Code    limit.
This value includes the thermal stress due to the non-linear portion of the thermal gradient for conservatism. A substantial reduction in the maximum range of stress intensity could be achieved        if  the non-linear thermal gradient contribution were neglected as permitted by the ASHE Code.
3.10.1.2      Reactor Vessel  Integrity An  evaluation of the impact of rerating on reactor vessel integrity for neutron embrittlement was performed. Neutron fluence changes for the rerating were calculated.       Using these revised fluences and those from other relevant systems parameters associated with the rerating, the assessment included review of surveillance capsule withdrawal schedules, the schedule of applicability of the plant heatup and cooldown limits, and 10 CFR 50-
            ~
Appendix G analyses, including a verification of plant specific material
                              ~                 ~     ~               ~ ~       ~
properties. A revision to the calculations used in the submittal to the NRC
                  ~
                          ~                     ~         ~
for meeting- the requirements of the pressurized thermal shock (PTS) rule were
                                                        ~
performed. Finally, an initial evaluation of the impact of rerating on the PTS risk of vessel failure was carried out to confirm the applicability of the screening criteria in the PTS rule for the Cook Nuclear Plant reactor vessels. The rerating affects the PTS transient initiating temperature which is lower than that used in the generic PTS risk analyses which support the screening criteria.
~
Neutron transport calculations have been completed at a conservatively high power level of 3600 HWt, and reduced temperature/pressure          conditions for Cook Nuclear Plant Unit 1. Results of these analyses have indicated that in addition to the increased reactor power, operation of the units with reduced coolant temperatures, particularly in the downcomer regions, also has a significant impact on the fast neutron exposure rates incident on the pressure vessel. Also impacted are the relationships among the neutron exposure rates at surveillance capsule locations and those at positions within the pressure vessel wall; i.e., capsule lead factors.
Agd~~         9  tz p  gQg7 8739a:1d/092988                            3.10-5
 
~ I To  provide  a bounding evaluation of these various    effects, calculations were performed for the current licensed conditions as well as for uprated power with both maximum and minimum downcomer temperatures. The results of these studies are summarized in Tables 3.10.1-1 and 3.10.1-2.
An  examination of Tables 3.10.1-1 and 3.10.1-2 shows that the impact of higher power operation and changed coolant temperatures is greater on the absolute magnitude of the neutron exposure rate than on the relative behavior of neutron flux distributions as reflected in capsule lead factors.
Two  sets of data have been provided to establish upper and lower bound exposures for Cook Nuclear Plant Unit 1. The upper limit conditions are consistent with assuming an uprating at the onset of the next fuel cycle with continued operation at an inlet temperature of 547'F for unit 1. Lower bound fluence estimates were based on no uprating in power level, but with future operation occurring at reduced T ; i.e., the inlet temperature was assumed avg'o be 512'F. These lower bound fluence estimates are lower than those at current operating conditions.
Review    of the heatup  and cooldown curves    that were previously generated by Southwest Research Institute indicate that these curves were generated in accordance with Regulatory Guide 1.99-Revision 1. Per NRC Generic Letter 88-11, dated July 12, 1988, all utilities must submit to the NRC by November 1988 the results of their technical analysis relative to the implementation of Regulatory Guide 1.99-Revision 2, which was officially issued in May 1988.
Given this regulatory change, the effect of rerating should be incorporated II into future calculations that will be performed for revising heatup and cooldown curves in accordance with this latest revision of Regulatory Guide 1.99. The effect of the rerating is deemed to not be significant.
The changes    in the systems parameters associated with the rerating have been judged to not have any significant impact on 10 CFR Part 50 - Appendix G analysis.
IZ pa~ +g 7 8139e:1d/093088                            3.10-6
 
S The Cook    Nuclear Plant Unit  1 reactor vessel beltline region material properties were verified against the latest available information in various industry data. bases and surveillance capsule reports. The properties defined from the latest information are consistent with those used in prior utility submittals to the NRC relative to meeting the requirements of the PTS rule.
Since the core loading pattern wi II be changing as a result of the rerating, an update to the PTS submittal will be required as stated in the PTS Rule.
Revised  calculations  were performed  for  the rerating using the current PTS Rule methodology and the latest procedure specified by Regulatory Guide 1.99-Revision 2. As stated in NRC Generic Letter 88-11, the staff is presently considering an amendment to the PTS Rule, 10 CFR 50.61, that will replace the equations for RTpts given in paragraph (b) (2) with the calculation procedure in Section C.l of Revision 2 to Regulatory Guide 1.99, but they will not change the screening criteria.
All the    RTpts values remain below the    NRC  screening values for PTS using the projected fluence values that are based upon rerated conditions through the license expiration. The highest RTpts value (265'F) was calculated at the circumferential weld of the Cook Nuclear Plant Unit I reactor vessel, using the methodology of Regulatory Guide 1.99 Revision 2.
On  the basis of probabi listic work described in the PTS Rule, the NRC staff that PHR vessels with conservatively calculated values of RTndt      'oncluded (i.e., RTpts) less than 270'F for plate material and axial welds, and less than 300'F for circumferential welds present an acceptably low risk of vessel failure    from PTS events. This evaluation, however, did not take into account the impact of rerating, which causes potential PTS transient scenarios to begin from a lower system temperature.
81390:1d/092988                            3.10"7
 
An  initial
        ~   ~ ~             ~
evaluation was  performed to determine the impact of rerating on the screening criteria in terms of risk of vessel
          ~     ~ ~
applicability of the PTS failure. A probabilistic fracture mechanics sensitivity study of limiting PTS transient characteristics, starting from a lower operating temperature, showed that the conditional probability of reactor vessel failure will not be adversely affected. Therefore, the overall risk of vessel failure will not be adversely impacted meaning that that the screening criteria in the PTS Rule are still applicable for the Cook Nuclear Plant Unit 1 reactor vessel relative to rerated conditions.
813S@: I d/092988                            3.10-8
 
TABLE 3.10.1-1 FAST NEUTRON (E > 1.0 MeV) FLUENCE PROJECTIONS  FOR COOK NUCLEAR PLANT  UNIT 1 Unit  1  22.89 EFPY                  U  er Bound        Lower Bound All plates;   Weld 9-442              1.84 x 10            1.55 x 10 Welds 2-442B, 2-442C,                 1.19 x 10            1.01 x 10 3-442A, 3-442C Weids 2-442A, 3-442B                    5.92 x 10            5.01 x 10 8139e:1d/092988                          3.10-9
 
I TABLE 3.1.0.1-2 SURVEILLANCE CAPSULE LEAD FACTORS FOR COOK NUCLEAR PLANT  UNIT 1 4'aosules        40'apsules Unit  1 Base Case                          1.3              4.2 (3250  Wt, 536'F  Downcomer)
Unit  1 At Uprated Power                    1.3              4.2 (3588 HMt, 547'F Downcomer)
Unit  1 At Uprated Power                    1.3              4' (3588 HMt, 512'F Downcomer) p ff QIPN Q      C Jt j I2 P  V~<7 8139e:1d/092988                            3.10"10
 
E TABLE  4.1-1 SYSTEM DESIGN AND OPERATING PARAMETERS Plant design life, years                                                40 Number of heat cransfer loops Design pressure, psig                                                2485 Nominal operating pressure, psig                                      2235 Tocal system volume including pressurizer and surge  line (ambient conditions), ft3 (estimated)           12,500 System liquid volume, including pressurizer and surge line (ambient conditions), fc                        11,892 System liquid volume, including pressurizer max.,guaranteed power, fc 3 (escimac'ed)                       11,780 6
Tocal Reactor heat output (100% power) Btu/hr                11,089 x 10      (Unit 1)
(3250 MVt) i                                                                            6 11,641 x 10 (Unit 2)
(3411 HPt)
Unit 1            Unit    2 Bounding Conditions for Reracing Lower/Upper Reactor vessel coolant temperature at full power:
Inlet, nominal, 0 F                        514.9/545.2            541. 3 Outlet, nominal, 0 F                      579.1/607.5            606.4 Coolant temperature rise in vessel ac full power, avg., 0 F                        64.2/62.3              64.8 Total coolant flow race, lb/hr x 10 6            139.0/133.9            134.6 Sceam pressure ac full po~er, psia                  618/820              820 Steam Temp. Q  full power,  F                  489 '/521.1            521.1 Total Reactor Coolant    Volume at a mbient condicions, ft3 12,438              12,470 4.1-25                          July    1990}}

Latest revision as of 06:48, 29 October 2019

Reduced Temp & Pressure Operation for Donald C. Cook Nuclear Plant Unit 1 Licensing Rept, Including FSAR mark-ups
ML17325A967
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 10/31/1988
From: Augustine D, Cecchett D
WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML17325A960 List:
References
WCAP-11902, NUDOCS 8810190409
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Text

MESTINGHOUSE CLASS III HCAP-11902 REDUCED TEMPERATURE ANO PRESSURE OPERATION FOR DONALD C. COOK NUCLEAR PLANT UNIT 1 LICENSING REPORT

0. L. Cecchett
0. B. Augustine October 1988 WESTINGHOUSE ELECTRIC CORPORATION Energy Systems Business Unit P.O. Box 355 Pittsburgh, Pennsy1vania 15230 e pop /g

/'980a:1d/100588

c umulative fatigue usage factor was calculated to be 0.69 which is less than the 1.0 Code limit.

This value includes the thermal stress due to the non-linear portion of the thermal gradient for conservatism. A substantial reduction in the maximum range of stress intensity could be achieved if the non-linear thermal gradient contribution were neglected as permitted by the ASHE Code.

3.10.1.2 Reactor Vessel Integrity An evaluation of the impact of rerating on reactor vessel integrity for neutron embrittlement was performed. Neutron fluence changes for the rerating were calculated. Using these revised fluences and those from other relevant systems parameters associated with the rerating, the assessment included review of surveillance capsule withdrawal schedules, the schedule of applicability of the plant heatup and cooldown limits, and 10 CFR 50-

~

Appendix G analyses, including a verification of plant specific material

~ ~ ~ ~ ~ ~

properties. A revision to the calculations used in the submittal to the NRC

~

~ ~ ~

for meeting- the requirements of the pressurized thermal shock (PTS) rule were

~

performed. Finally, an initial evaluation of the impact of rerating on the PTS risk of vessel failure was carried out to confirm the applicability of the screening criteria in the PTS rule for the Cook Nuclear Plant reactor vessels. The rerating affects the PTS transient initiating temperature which is lower than that used in the generic PTS risk analyses which support the screening criteria.

~

Neutron transport calculations have been completed at a conservatively high power level of 3600 HWt, and reduced temperature/pressure conditions for Cook Nuclear Plant Unit 1. Results of these analyses have indicated that in addition to the increased reactor power, operation of the units with reduced coolant temperatures, particularly in the downcomer regions, also has a significant impact on the fast neutron exposure rates incident on the pressure vessel. Also impacted are the relationships among the neutron exposure rates at surveillance capsule locations and those at positions within the pressure vessel wall; i.e., capsule lead factors.

Agd~~ 9 tz p gQg7 8739a:1d/092988 3.10-5

~ I To provide a bounding evaluation of these various effects, calculations were performed for the current licensed conditions as well as for uprated power with both maximum and minimum downcomer temperatures. The results of these studies are summarized in Tables 3.10.1-1 and 3.10.1-2.

An examination of Tables 3.10.1-1 and 3.10.1-2 shows that the impact of higher power operation and changed coolant temperatures is greater on the absolute magnitude of the neutron exposure rate than on the relative behavior of neutron flux distributions as reflected in capsule lead factors.

Two sets of data have been provided to establish upper and lower bound exposures for Cook Nuclear Plant Unit 1. The upper limit conditions are consistent with assuming an uprating at the onset of the next fuel cycle with continued operation at an inlet temperature of 547'F for unit 1. Lower bound fluence estimates were based on no uprating in power level, but with future operation occurring at reduced T ; i.e., the inlet temperature was assumed avg'o be 512'F. These lower bound fluence estimates are lower than those at current operating conditions.

Review of the heatup and cooldown curves that were previously generated by Southwest Research Institute indicate that these curves were generated in accordance with Regulatory Guide 1.99-Revision 1. Per NRC Generic Letter 88-11, dated July 12, 1988, all utilities must submit to the NRC by November 1988 the results of their technical analysis relative to the implementation of Regulatory Guide 1.99-Revision 2, which was officially issued in May 1988.

Given this regulatory change, the effect of rerating should be incorporated II into future calculations that will be performed for revising heatup and cooldown curves in accordance with this latest revision of Regulatory Guide 1.99. The effect of the rerating is deemed to not be significant.

The changes in the systems parameters associated with the rerating have been judged to not have any significant impact on 10 CFR Part 50 - Appendix G analysis.

IZ pa~ +g 7 8139e:1d/093088 3.10-6

S The Cook Nuclear Plant Unit 1 reactor vessel beltline region material properties were verified against the latest available information in various industry data. bases and surveillance capsule reports. The properties defined from the latest information are consistent with those used in prior utility submittals to the NRC relative to meeting the requirements of the PTS rule.

Since the core loading pattern wi II be changing as a result of the rerating, an update to the PTS submittal will be required as stated in the PTS Rule.

Revised calculations were performed for the rerating using the current PTS Rule methodology and the latest procedure specified by Regulatory Guide 1.99-Revision 2. As stated in NRC Generic Letter 88-11, the staff is presently considering an amendment to the PTS Rule, 10 CFR 50.61, that will replace the equations for RTpts given in paragraph (b) (2) with the calculation procedure in Section C.l of Revision 2 to Regulatory Guide 1.99, but they will not change the screening criteria.

All the RTpts values remain below the NRC screening values for PTS using the projected fluence values that are based upon rerated conditions through the license expiration. The highest RTpts value (265'F) was calculated at the circumferential weld of the Cook Nuclear Plant Unit I reactor vessel, using the methodology of Regulatory Guide 1.99 Revision 2.

On the basis of probabi listic work described in the PTS Rule, the NRC staff that PHR vessels with conservatively calculated values of RTndt 'oncluded (i.e., RTpts) less than 270'F for plate material and axial welds, and less than 300'F for circumferential welds present an acceptably low risk of vessel failure from PTS events. This evaluation, however, did not take into account the impact of rerating, which causes potential PTS transient scenarios to begin from a lower system temperature.

81390:1d/092988 3.10"7

An initial

~ ~ ~ ~

evaluation was performed to determine the impact of rerating on the screening criteria in terms of risk of vessel

~ ~ ~

applicability of the PTS failure. A probabilistic fracture mechanics sensitivity study of limiting PTS transient characteristics, starting from a lower operating temperature, showed that the conditional probability of reactor vessel failure will not be adversely affected. Therefore, the overall risk of vessel failure will not be adversely impacted meaning that that the screening criteria in the PTS Rule are still applicable for the Cook Nuclear Plant Unit 1 reactor vessel relative to rerated conditions.

813S@: I d/092988 3.10-8

TABLE 3.10.1-1 FAST NEUTRON (E > 1.0 MeV) FLUENCE PROJECTIONS FOR COOK NUCLEAR PLANT UNIT 1 Unit 1 22.89 EFPY U er Bound Lower Bound All plates; Weld 9-442 1.84 x 10 1.55 x 10 Welds 2-442B, 2-442C, 1.19 x 10 1.01 x 10 3-442A, 3-442C Weids 2-442A, 3-442B 5.92 x 10 5.01 x 10 8139e:1d/092988 3.10-9

I TABLE 3.1.0.1-2 SURVEILLANCE CAPSULE LEAD FACTORS FOR COOK NUCLEAR PLANT UNIT 1 4'aosules 40'apsules Unit 1 Base Case 1.3 4.2 (3250 Wt, 536'F Downcomer)

Unit 1 At Uprated Power 1.3 4.2 (3588 HMt, 547'F Downcomer)

Unit 1 At Uprated Power 1.3 4' (3588 HMt, 512'F Downcomer) p ff QIPN Q C Jt j I2 P V~<7 8139e:1d/092988 3.10"10

E TABLE 4.1-1 SYSTEM DESIGN AND OPERATING PARAMETERS Plant design life, years 40 Number of heat cransfer loops Design pressure, psig 2485 Nominal operating pressure, psig 2235 Tocal system volume including pressurizer and surge line (ambient conditions), ft3 (estimated) 12,500 System liquid volume, including pressurizer and surge line (ambient conditions), fc 11,892 System liquid volume, including pressurizer max.,guaranteed power, fc 3 (escimac'ed) 11,780 6

Tocal Reactor heat output (100% power) Btu/hr 11,089 x 10 (Unit 1)

(3250 MVt) i 6 11,641 x 10 (Unit 2)

(3411 HPt)

Unit 1 Unit 2 Bounding Conditions for Reracing Lower/Upper Reactor vessel coolant temperature at full power:

Inlet, nominal, 0 F 514.9/545.2 541. 3 Outlet, nominal, 0 F 579.1/607.5 606.4 Coolant temperature rise in vessel ac full power, avg., 0 F 64.2/62.3 64.8 Total coolant flow race, lb/hr x 10 6 139.0/133.9 134.6 Sceam pressure ac full po~er, psia 618/820 820 Steam Temp. Q full power, F 489 '/521.1 521.1 Total Reactor Coolant Volume at a mbient condicions, ft3 12,438 12,470 4.1-25 July 1990