ML17334B426

DC Cook Unit 1 Reactor Vessel Rt PTS Evaluations.

ML17334B426
Person / Time
Site:	Cook
Issue date:	03/31/1990
From:	CHICOTTS J M, MEYER T A, RAY N K WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
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ML17329A566	List: ML17329A565 ML17329A567 ML17334B426
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NUDOCS 9207280271
Download: ML17334B426 (21)

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APPROVED"IN GENERAL" MECHANICAL ENGINEERING DIVISION AMERICAN ELECTRIC POWER SERVICE CORP-PER DATES C PP4'.C.COOK UNIT 1 REACTOR VESSEL RTPTS EVALUATIONS gy~<3nenF~5 J.M.Chicotts N.K.Ray MARCH 1990 work performed under Shop Order No.AOZP-108 Approved: T.A.Meyer, M ager Structural Materials and Reliability Technology Prepared by Mestinghouse Electric Corporation for the American Electric Power Company 4111si031290:10 REST INGHOUSE ELECTRIC CORPORATION Nuclear and Advanced Technology Oivision P.O.8ox 2728 Pittsburgh, Pennsylvania 15230 (920728027i 920713 PDR ADOCN 050003i5 P PDR TABLE OF CONTENTS Section TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES Title~Pa e

SUMMARY

OF RESULTS PRESSURIZED THERMAL SHOCK 2-1 The Pressurized Thermal Shock Rule 2-1 2-2 Methods for Calculation of RTPTS 2-3 2-3 Determination of RTPTS Values for All Beltline Region Materials 2-5 2-4 Status of Reactor Vessel integrity in Terms of RTP TS Versus Fluence Resul ts 2-6 REFERENCES 3-1et T Eel031290:10 LIST OF TABLES Table Title~Pa e 2-1 0, C.Cook Unit 1 Reactor Vessel Beltline Region Material Properties 2-8 2-2 Summary of Fluence (E>1.0 MeV)Used for the Evaluation of RTPTS 2-9 2-3 RTP TS Va1 ues Per PTS Rul e for 0~C~Cook Uni t 1 2"10 RTPTS Values Per Regulatory Guide 1.99, Revi sion 2 for 0.C.Cook Unit 1 2-11 4I I I el03 I 290: IO 11 j

LIST OF FIGURES~Fi ere Ti tie~Pa e 2-1 2-2 2-3 Identification"and-Location of Heltline Region Material for the..D..C.Cook Unit 1 Reactor Vessel RTPTS vs~Fluence per PTS Rule-Cook Uni t 1, RT>>~vs.Fluence per Regulatory Guide 1.99, Rekilion 2, Cook Unit 1, 2-7 2-11 2"12 i111sl031290:10 SECT10N 1

SUMMARY

OF RESULTS The Pressurized thermal shock evaluations were performed for D.C.Cook Unit 1 Reactor Vessel Belt line region materials and resulted the following conclusion:

o Using PTS rule: The limiting material is found to be the circumferential weld (Table 2-3).RTPTS values are 200'F and 216'F for life up to 23 and 32 EFPY respectively.

These values are below the screening criteria of 300'F for circumferential weld.o Using Regulatory Guide 1.99, Revision 2 The limiting material is found to be the circumferential weld (Table 2-4).RTPTS values are 221'F and 238 F for life up to 23 and 32 EFPY respectively.

These values are below the screening criteria of 300'F for circumferential weld.ll 1 le/0312QO:lO SECTION 2 PRESSURIZED THERMAL SHOCK 2-1.THE PRESSURIZED THERMAL SHOCK RULE The Pressurized Thermal Shock (PTS)Rule was approved by the U.S.Nuclear I:1]Regulatory Commissioners on June 20, 1985, and appeared in the Federal Register on July 23, 1985.The date that the Rule was published in the Federal Register is the date that the Rule became a regulatory requirement.

1 The Rule outlines regulations to address the potential for PTS events on pressurized water reactor (PHR)vessels in nuclear power plants that are operated with a license from the United States Nuclear Regulatory Commission (USNRC).PTS events have been shown from operating experience to be transients that result in a rapid and severe cooldown in the primary system coincident with a high or increasing primary system pressure.The PTS concern~~~~~arises if one of these transients acts on the beltline region of a reactor vessel where a reduced fracture resistance exists because of neutron irradiation.

Such an event may produce the propagation of fTaws postulated to exist near the inner wall surface, thereby potent'ially affecting the integrity of the vessel.The Rule establishes the following requirements for all domestic, operating PMRs:*The RT~7~(measure of fracture resistance)

Screening Criterion for the reh0'tor vessel beltline region is 270'F for plates, forgings, axial welds 300'F for circumferential weld materials 4111@/031290;10 2-1 6 Months From Oate of Rule: All plants submitted their present RT>>~values (per the prescribed methodology) and projected RT>>~values at the expiration date of the operating license.The dat4 that this submittal had to be received by the NRC for plants with operating licenses was January 23, 1986.9 Months From Oate of Rule: Plants projected to exceed the PTS Screening Criterion had to submit an analysis and a schedule for implementation of such flux reduction programs as are reasonably practicable to avoid reaching the Screening Criterion.

The date for this submittal had to be received by the NRC for plants with'operating licenses by April 23, 1986.*Plant-specific PTS safety analyses are required before a plant is within 3 years of reaching the Screening Criterion, including analyses of alternat,ives to minimize the PTS concern.*NRC approval for operation beyond the Screening Criterion is required.For applicants of operating licenses, values of the projected RTpTS are to be provided in the Final Safety Analysis Report.This requirement is added as part of 10CFR Part 50.34.0 In the Rule, the NRC provides guidance regarding the calculation of the toughness state of the reactor vessel materials-the"reference temperature for nil-ductility transition" (RTNOT).For purposes of the Rule, RTNOT is now defined as"the reference temperature for pressurized thermal shock" (RTPTS)and calculated as prescribed by 10 CFR 50.61(b)of the Rule.Each USNRC licensed PMR was required to submit a projection of RTpTS values from the time of the submittal to the license expiration date.This assessment was required to be submitted within 6 months after the effective date of the Rule, on January 23, 1986, with updates whenever changes occur affecting projected values.The calculation must be made for each weld and plate, or forging, in the reactor vessel beltline.'411 1 s>031290:10 2-2 Calculations were carried out using the latest plant specific material~~~~~~~properties in accordance with both the current PTS rule and Regulatory I:1l Guide 1.99-Revision 2 , which was recently issued as the latest regulatory method for predicting irradiation embrittlement of reactor vessel materials.

The NRC plans to incorporate Revision 2 of Regulatory Guide 1.99 into the PTS rule without changing the PTS screening criteria per NRC Generic Letter 88-11.The RTPTS results for all Cook, Unit 1 reactor vessel beltline[3l region materials are presented following a description of these two regulatory cal culational methodologies.

2 2 METHODS FOR CALCULATION OF RTPTS 2-2.1 PTS Rule Methodolo ln the PTS Rule, the NRC Staff has selected a conservative and uniform method for determining plant-specific values of RTPTS at a given time.The prescribed equations in the PTS rule for calculating RTPTS are actually one of several ways to calculate RTNOT.For the purpose of comparison with the Screening Criterion, the value of RTPTS for the reactor vessel must be calculated for each weld and plate, or forging in the beltline region as given below.For each material, RTPTS is the lower of the results given by Equations 1 and 2.Equation 1: RTp TS I+M+[10+470(Cu)+350(Cu)(Nl)]f Equation 2: RT=I+M+283 f0'194 PTS (2)4111giOQ~%0.10 2-3 where I=the initial reference transition temperature of the unirradiated material measured as defined in the ASHE Code, NS-331, If a measured value is not available, the following generic mean values must be used: O'F for welds made with Linde 80 flux, and-56'F for welds made with Linde 0091, 1092 and 124 and ARCOS 8-5 weld fluxes.H=the margin to be added to cover uncertainties in the values of initial RTNp T copper and ni eke 1 content, f 1 uence, and ca 1 cul ati on procedures

~In Equation 1, M=48'F if a measured value of I was used, and M=59'F if the generic mean value of I was used.In Equation 2, M=O'F if a measured value of I was used, and M=34'F if the generic mean value of I was used.Cu and Ni=the best estimate weight percent of copper and nickel in the material.f=the maximum neutron fluence, in units of 10 n/cm (E greater than or 19 2 equal to 1 MeV), at the clad-base-metal interface on the inside surface of the vessel at the location where the material in question receives the highest fluence for the period of service in question.Note that the chemistry values given in equations 1 and 2 are best estimate mean values.The margin, M, increases the RTPTS values to be upper bound predictions.

Thus, the mean material chemistry values are to be used when available so as not to compound conservatism.

2-2.2 Reoulator Guide 1.99 Revision 2 Hethodolo Revision 2 to Regulatory Guide 1.99 was issued in May 1988.The Adjusted l2]Reference Temperature (ART), based on the methods of Regulatory Guide 1.99 Revision 2, can be compactly described by the sequence of equations listed below: 4'Ills>071290;>0 2-4 ART=Initial RTNpy+ARTNDT+Margin dRT=(CF]F(0.28

-0.10 LOG f)NDT w ere, (3)(4)f=Neutron fluence, n/cm (E>1 MeV), divided by 10 CF=Chemistry factor from tables for welds and for base metal (plates and forgings)(if no data use 0.35%Cu and 1.0%Ni)Margin=2[ol+a<]'here, 2 (5)aI standard deviation of initial RTNpy If the initial RTNpy i s measur ed, oI i s to be estimated fr om the precision of the test method;otherwise, aI is obtained from the same set of data that is used to get initial RTNpy.o<=Standard deviation of LRTNDT, 28'F for welds and 17'F for base metal[a>need not exceed 1/2 times ARTNDT surface]The value of ART will be assumed to be the RTPTS value for use with the PTS rule.2 3 DETERMINATION OF RTp TS.VALUES FOR ALL BELTL INE REG ION MATERIALS For the RTPTS calculation, the best estimate copper and nickel chemical composition of the reactor vessel beltline material is necessary.

The beltline region is de'fined by the Rule]to be"the region of the reactor vessel (shell material including welds, heat affected zones, and plates or forgings)that directly surrounds the effective height of the active core and adjacent regions of the reactor vessel that are predicted to~~~~~~~~~~~~~~~~~~~~experience sufficient neutron irradiation damage to be considered in the selection of the most limiting material with regard to radiation damage." Figure 2-1 identifies the location of all beltline region materials for the reactor vessel.t 1 I 1 s/all 200: l 0 2-5 A summary of the pertinent chemical and mechanical properties of the beltline region plate and weld materials and the initial RTNDT values of the Cook Unit 1 reactor vessel are reproduced in Table 2-1 (Reference 4, Table A-l).Also a summary of fluence (E>1.0 MeV)values used for the evaluation of RTP TS is provided in Table 2-2 (Reference 4, Table 6-14).Using the methodology prescribed before and the material properties

'discussed in this section, the RTPTS values for D.C.Cook Unit L can be determined.

2 4 STATUS OF REACTOR VESSEL INTEGRITY IN TERMS OF RTpTS VERSUS FLUENCE RESULTS Using the prescribed PTS Rule methodology, RTPTS values were generated for all beltline region materials of the D.C.Cook Unit 1 reactor vessel as a function of pertinent vessel lifetimes.

The tabulated results from this~~~evaluation are presented in Table 2-3 and 2-4 for all beltline region materials.

Figures 2-2 and 2-3 present the RTPTS versus fluence for the beltline.material of the Cook Unit 1 vessel using PTS rule and Regulatory Guide 1.99, Revision 2, respectively, The curves in these figures can be used to provide guidance to evaluate fuel reload options in relation to the NRC RTPTS Screening Criterion for PTS, if this would ever become necessary.

That is, RTPTS values can be readily projected for any options under consideration, provided that fluence is known.il 11@/031290:10 2-6

~0 Ll fl C ID NIT 1 GIE 1 NTEfSKD1ATE SHELL 0 CL 5 ID ID~e Cl h~Ql n ao~0 n 0 lQ 0 CL C I 0 wo h rt'X7 ID O h 0 CXl 5 ID Ol Cll ID ID ID u3 0~o o CA Cl TABLE 2-1~~D.C.UNIT 1 REACTOR VESSEL BELTLINE REGION MATERIAL PROPERTIES Plate Cu Ni Initial Component No.(Wtl.)(Wtl.)RTNDT('F)Intermediate Shell Plate 84406-1.12.52 Intermediate Shell Plate B4406-2.15.50 33 Intermediate Shell Plate B4406-3 ,15.49 40 Lower Shell Plate 84407-1.14.55 28Lower Shel 1 Plate B4407-2.12.59-12 Lower Shell Plate B4407-3.14.50 38 Longitudinal fields.28.74-56 Circumferential fields.28.74-56 il 1 1 s/0311SO;10 2-8 TABLE 2-2~~

SUMMARY

OF FLUENCE (E>1.0 MeV)VALUES USED FOR THE EVALUATION OF RTP TS Component 23 EFPY 32 EFPY Intermediate Shell Plate, 84406-1 1,05 1.41 Intermediate Shell Plate, 84406-2 Intermediate Shell Plate, 84406-3 1.05 1.05 1.41 1.41 Lower Shell Plate, 84407-1 1.05 1.41 Lower Shell Plate, 84407-2 1.05 1.41 Lower Shell Plate, 84407-3 1.05 1.41 Longitudinal Weld 0.714 0.95 Circumferential Weld 1.05 1.41 Fluences are in 10 n/cm (E>1.0 MeV)19 4131 s/032790:10 2-9 TABLE 2-3 RTp TS VALUES PER PTS RULE FOR 0~C~COOK UNIT 1 RTPTS Values ('F)Location Vessel Material 23 EFPY SCREENING 32 EFPY CRITERIA Intermediate shell plate B4406-1 122 128 270 2 Intermediate shell plate B4406-2 169 176 270 3 Intermediate shell plate B4406-3 175 183 270 Lower shell plate B4407-1 160 167 270 Lower shell plate B4407-2 108 114 270 6 Lower shell plate B4407-3 167 174 270 7 Most Limiting Longitudinal weld 180 195 270 Circumferential weld 200 300 41 I I sx001700: TO 2-10 TABLE 2-4 RTP TS VALUES PER REGULATORY GUIDE 1 99 REVISION 2 FOR D.C.COOK UNIT 1 RTPTS Values ('F)Location Vessel Material 23 EFPY SCREENING 32 EFPY CRITEREA 1 Intermediate shell plate 84406-1, 121 128 270 2 Intermediate shell plate B4406-2 173 182 270 Intermediate shell plate B4406-3 179 188 270 4 Lower shell plate 84407-1 161 169 270 5 Lower shell plate B4407-2 106 113 270 6 Lower shell plate 84407-3 169 177 270 Most Limiting Longitudinal weld 199 215 270 8 Circumferential weld 221 238 300 4111slO'322SO:10 280 270 260 250 240 230 220 210 200 190 180 170 160 a 150 140 130 120 110 100 90 sa 70 Q1 03 05 Q7 09 11 13 15 17 19 Fluence (x 10E19)n/cm 2 TELOS+84406-3~+84406-2~84407-3 84407-1<84406-1 4 84407-2 il I ls/07llQO.IO Figure 2-2.RTPTS vs.Fluence per PTS Rule-Cook Unit 1 280 270 260 250 240 230 220 21Q 20Q 19a 180 170 160 150 140 13Q 12Q 11Q 100 90 80 7Q al Q3 05 07 09 11 13 15 17 19 Fluence (x 10619)n/cm 2 TELOS 84406-3 84406-2 84407-3 84407-1 0-84406-1~84407-2 4111s/031290 10 Figure 2-3.RTpT>vs.Fluence per Regulatory Guide 1.99, Revision 2-Cook Unit 1 SECTION 3 REFERENCES

[1]"Analysis of Potential Pressurized Thermal Shock Events," 10 CFR part 50, Final Rule, July 23, 1985.[2]Regulatory Guide 1.99, Revision 2,"Radiation Embrittlement of Reactor Vessel Materials," U.S.Nuclear Regulatory Commission, May, 1988.[3]NRC Generic letter 88-11,"NRC Position on Radiation Embrittlement of Reactor Vessel Materials and its Impact on Plant Operations", July 12, 1988.[4]E.Terek, S, L.Anderson, L.Albertin, N.K.Ray,"Analysis of Capsule U from the American Electric Power Company D.C.Cook Unit 1 Reactor Vessel Radiation Surveillance Program."~1~i<llis/031290:l0 3-1 a'~\Qe SECTION 3 REFERENCES

[1]"Analysis of Potential Pressurized Thermal Shock Events," 10 CFR part 50, Final Rule, July 23, 1985.[2]Regulatory Guide 1.99, Revision 2,"Radiation Embrittlement of Reactor Vessel Haterials," U.S.Nuclear Regulatory Commission, May, 1988.[3]NRC Generic letter 88-11,"NRC Position on Radiation Embrittlement of Reactor Vessel Materials and its Impact on Plant Operations", July 12, 1988.[4]E.Terek, S.L.Anderson, L.Albertin, N.K.Ray,"Analysis of Capsule U from the American Electric Power Company D.C.Cook Unit 1 Reactor Vessel Radiation Surveillance Program." i)ills/03l290:10 3-1