ML20138L169
| ML20138L169 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 02/13/1997 |
| From: | Boyle D WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML20138L167 | List: |
| References | |
| WCAP-14784, WCAP-14784-R02, WCAP-14784-R2, NUDOCS 9702210125 | |
| Download: ML20138L169 (27) | |
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Westinghouse Non-Proprietary Class 3 , l WCAP-14784
++++++++ Rev.2 i EVALUATION OF l PRESSURIZED THERMAL SHOCK l
FOR BEAVER VALLEY . UNIT 2 I Wes tinghouse Energy Sys tems (
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I WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-14784 Revision 2 l l Evaluation of Pressurized Thermal Shock for 1 Beaver Valley Unit 2 l l l T. J. Laubham l February,1997 Work Performed Under Shop Order D6AP-139 Prepared by Westinghouse Electric Corporation for the Duquesne Light Company Approved . b/ j D. E. Royle, Managpf Reactor Equipmenr& Materials Engineering WESTINGHOUSE ELECTRIC CORPORATION Systems and Major Projects Division P.O. Box 355 Pittsburgh, Pennsylvania 15230-0355
@1997 Westinghouse Electric Corporation All Rights Reserved 11/12/ %
. .. . i PREFACE 1
Revision 1: The following changes have been made to this report: Reference 4, which was inadvertently left out of revision 0, was inserted in the reference list on page 14. This reference was added to a note under Table 2 on page 8. Revision 2: 1 Added two new sets of copper / nickel values for weld metal to Table 1 and removed the last set of weld metal copper / nickel values (Cu = 0.04, Ni = 0.07). i Changed Reference 13. 1 Verified By:
- l. E. Terek i
Evaluation of PTS for Beaver Valley Unit 2
m li 1 TABLE OF CONTENTS P R E FA C E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i LI ST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii LI ST OF FIG U R ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
.1 I NTR OD U CTIO N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 l
l 2 PRESSURIZED THERMAL SHOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 METHOD FOR CALCULATION OF RTpTs . . . . . . . . . . . . . . . . . . . . . . . . . 3 4 VERIFICATION OF PLANT-SPECIFIC MATERIAL PROPERTIES . . . . . . . 5 1 5 NEUTRON FLUENCE VALUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 DETERMINATION OF RTpTs VALUES FOR ALL BELTLINE REGION MATE R I ALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7 CON CLU S ION S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8 REFERENCES........................................... 14 l APPENDIX A: SURVEILLANCE DATA CREDIBILITY EVALUATION . . . . . 16 q l l l I l l I i
)
Evaluation of PTS for Beaver Valley Unit 2
, . iii r ;
i LIST OF TABLES , Table 1 Calculation of Average Cu and Ni Weight Percent Values for ! Beltline Region Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 , i Table 2 Beaver Valley Unit 2 Reactor Vessel Beltline Region Material Properties 8 ; l Table 3 Fluence (10" n/cm", E > 1.0 MeV) on the Pressure Vessel Clad / Base Metal Interface for Beaver Valley Unit 2 . . . . . . . . . . . . . 9 Table 4 Interpolation of Chemistry Factors Using Tables 1 and 2 of 10 I C FR Part 50.61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Table 5 Calculation of Chemistry Factors Using Surveillance Capsule Data i Per Regulatory Guide 1.99, Revision 2, Position 2.1 ........... 11 i Table 6 RTns Calculations for Beaver Valley Unit 2 Beltline Region ! Materials at EOL (32 EFPY) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 : t P i I i i t r Evaluation of PTS for Beaver Valley Unit 2 l i
l r- ,. , iv UST OF FIGURES i Figure 1' identification and Location of Beltline Region Material for the Beaver Valley Unit 2 Reactor Vessel . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 ; l i l l l I I i l E% of PTS for Beaver Valley Unit 2
.. 1 t
1 INTRODUCTION l A Pressurized Thermal Shock (PTS) Event is an event or transient in pressurized water reactors (PWRs) causing severe overcooling (thermal shock) concurrent with or followed by significant pressure in the reactor vessel. A 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 flaws postulated to exist near the inner wall surface, thereby potentially affecting the integrity of the vessel. The purpose of this report is to determine the RTns values for the Beaver Valley Unit 2 reactor vessel using the results of the surveillance Capsule V evaluation. Section 2.0 discusses the PTS Rule and its requirements. Section 3.0 provides the methodology for calculating RTn,. Section 4.0 prov! des the reactor vessel beltline region material properties for the Beaver Valley Unit 2 reactor vessel. The neutron fluence values used in this analysis tre presented in Section 5.0. The results of the RTns calculations are presented in Section 6.0. The conclusion and references for the PTS evaluation follow in Sections 7.0 and 8.0, respectively. l l l l l l l l l l I Evaluation of PTS for Beaver Valley Unit 2
2 l 2 PRESSURIZED THERMAL SHOCK l l l The Nuclear Regulatory Commission (NRC) recently amended its regulations for light-water-cooled nuclear power plants to clarify several items related to the fracture toughness requirements for reactor pressure vessels, including pressurized thermal shock requirements. The revised PTS RuleD3,10 CFR Part 50.61, was published in the Federal Register on December 19,1995, with an effective date of January 18,1996. This amendment to the PTS Rule makes three changes: l 1. The rule incorporates in total, and therefore makes binding by rule, the method for determining the reference temperature, RT, Mcluding treatment of the unirradiated RT value, the margin term, and the explicit definition of " credible" surveillance data, which is currently described in Regulatory Guide 1.99, Revision 2A.
- 2. The rule is restructured .o improve clarity, with the requirements section giving only the requirements for ?N value for the reference temperature for end of life fluence, RTns-
- 3. Thermal annealing is identified as a method for mitigating the effects of neutron irradiation, thereby reducing RTns-The PTS Rule requirements consist of the following:
l . For each pressurized water nuclear power reactor for which an operating license has l been issued, the licensee shall have projected values of RTns, accepted by the NRC, l for each reactor vessel beltline material for the EOL fluence of the material. i The assessment of RTns must use the calculation procedures given in the PTS Rule, l and must specify the bases for the projected value of RTn, for each vessel beltline l material. The report must specify the copper and nickel contents and the fluence values used in the calculation for each beltline material. l This assessment must be updated whenever there is a significant change in projected values of RTn, or upon the request for a change in the expiration date for operation of the facility. Changes to RTn, va'ues are significant if either the previous value or the current value, or both values, exceed the screening criterion prior to the expiration of the operating license, including any renewal term, if applicable for the plant.
. The RTns screening criterion values for the beltline region are:
i 270'F for plates, forgings, and axial weld materials, and 300*F for circumferential weld materials. Evaluation of PTS for Beaver Valley Unit 2
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L 3 METHOD FOR CALCULATION OF RT,,,, RTm must be calculated for each vessel beltline material using a fluence value, f, which is the EOL fluence for.the rnatorial. Equation 1 must be used to calculate values of RTu or for each weld and plate or forging in the reactor vessel beltline. l RTwor=RTuorg+M+ ART uo7 (1) RTuorgy = reference temperature for a reactor vessel material in the pre-service or unirradiated condition M- =- Margin to be added to account for uncertainties in the values of RTuorca, copper and nickel contents, fiuence and calculational procedures. M is evaluated from Equation 2. M-2/o +o (2) o uis the standard deviation for RTuorgm. ou= 0*F when RTuorg, is a measured value o u= 17'F when RTuorge is a generic value L o, is the standard deviation for ARTuor. For plates and forgings: l o, = 17*F when surveillance capsule data is not used I o, = 8.5'F when surveillance capsule data is used For welds: o, = 28 F when surveillance capsule data is not used o, = 14*F when surveillance capsule data is used o, not to exceed one-half of ARTuo7 ARTuor is the mean value of the transition temperature shift, or change in RTuo7, due to irradiation, and must be calculated using Equation 3. ARTwor-(CF)*f 8'84N (3) Evaluatum of PTS for Beaver Valley Unit 2
4 L CF (*F) is the chemistry factor, which is a function of copper and nickel content. CF is l determined from Tables 1 and 2 of the PTS Rule (10 CFR 50.61). Surveillance data deemed l credible must be used to determine a material-specific value of CF. A material-specific value I of CF is determined in Equation 5. l f is the best estimate neutron fluence, in units of 10" n/cm' (E > 1.0 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. The EOL fluence is used in calculating RTn s. Equation 4 must be used for determining RTns using Equation 3 with EOL fluence values for determining ARTn .
- RTns RTg+M +A RTns (4) l l To verify that RTuo r for each vessel beltline material is a bounding value for the specific reactor vessel, licer.3ees shall consider plant-specific information that could affect the level of cmbrittlement. This information includes but is not limited to the reactor vessel operating l t
- mperature and any related surveillance program results. Results from the plant specific l surveillance program must be integrated into the RTuor estimate if the plant-specific l
surveillance data has been deemed credible. i A material-specific value of CF is determined from Equation 5. CF= E[A ii
.f *] (5)
In Equation 5, "A," is the measured value of ARTum and "f," is the fluence for each surveillance data point. If there is clear evidence that the copper and nickel content of the surveillance weld differs from the vessel weld, i.e., differs from the average for the weld wire heat number I associated with the vessel weld and the surveillance weld, the measure values of ARTum must be adjusted for differences in copper and nickel content by multiplying them by the ratio of the chemistry factor for the vessel material to that for the surveillance weld.
- Evaluation of PTS for Beaver Valley Unit 2
5 l 4 VERIFICATION OF PLANT-SPECIFIC MATERIAL PROPERTIES Before performing the pressurized thermal shock evaluation, a review of the latest plant-specific material properties for the Beaver Valley Unit 2 vessel was performed. The beltline region of a reactor vessel, per the PTS Rule, is defined as "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 radiation damage to be considered in the selection of the most limiting material with regard to radiation damage". Figure 1 identifies and indicates the location of all beltline region materials for the Beaver Valley Unit 2 reactor vessel. Meterial property values were obtained from material test certifications from the original iaorication as well as the two additional material chemistry tests performed for St. Lu'cie Unit 20 'l and Almaraz Unit 2D 'l. The average copper and nickel values were calculated for each l beltline region material using all of the available material chemistry information as shown in Table 1. Initial RT, values for Beaver Valley Unit 2 Reactor Vessel Beltline Region Material l Properties are shown in Table 2. i I Evaluation of PTS for Beaver Valley Unit 2
' 6
' CIRCUNTERENTIAL SEAMS VERTICAL SEAMS 89004-1 101-1248- /
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/
m 45* CORE 180' I O'
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B9004-2 90, 101-124A 5 CORE 4 101-171 270 101-1428 89005-2 7 _ IS' f6 CME 180* O' 101-142A 90* 89005-1 Figure 1: Identification and Location of Beltiine Region Material for the Beaver Valley Unit 2 Reactor Vessel valuation of PTS for Beaver Valley Unit 2
7 I Table 1 Calculation of Average Cu and Ni Weight Percent Values for Beltline Region Materials Inter. Shell Plate Inter. Shell(* Lower Shell Lower Shell B90041 Plate B9004-2 Plate 89005-1 Plate B9005-2 Weld Metal
- Ref. Cu % Ni % Cu % Ni % Cu % Ni % Cu % Ni % Cu % Ni %
6 0.07 0.53 7 0.07 0.59 9 0.08 0.59 10 0.07 0.58 8 0.06 0.57 0.06 0.56 0.08 0.57 0.07 0.56 14 0.05 0.56 12 0.04 -- 11 0.04 0.08 11 0.04 0.09 11 0.05 0.07 11 0.05 0.07 11 0.08 0.07 19 0.05 0.04 13 0.04 0.06 13 0.03 0.06 Avg. 0.065 0.55 0.06 0.57 0.08 0.58 0.07 0.57 0.05 0.07 NOTES: (a) Surveillance program t,ase metal material. I (b) The surveillance weld specimens were made of the same wire and flux as the intermediate and lower shell vertical seams and the girth weld between the intermediate and lower shell plates (3/16 inch Diameter Weld Wire Type B-4, Heat Number 83642, Linde 0091 Flur. Lot Number 3536). l Evaluation of PTS for Beaver Valley Unit 2
. . B l
Table 2 Beaver Valley Unit 2 Reactor Vessel Beltline Region Material Properties Material Description Cu (%) (*) Ni(%)( RTworcu> (*F) *) Intermediate Shell Plate B9004-1 0.065 0.55 60 Intermediate Shell Plate B9004-2 0.06 0.57 40 Lower Shell Plate B9005-1 0.08 0.58 28 Lower Shell Plate B9005-2 0.07 0.57 33 Weld Materia! 0.05 0.07- -30 NOTES: (a) Average values of copper and nickel as indicated in Table 1 on preceding page. (b) The RTwortu) values for the plates and welds are measured values per U.S. NRC Standard Review Plan 14 ' 51 l l l Evaluation of PTS for Beaver Valley Unit 2 L__________ _ _ __ _ _ __ . . .
9 l f 5 NEUTRON FLUENCE VALUES The calculated fast neutron fluence (E > 1.0 MeV) values at the inner surface of the Beaver Valley Unit 2 reactor vessel are shown in Table 3. These values were projected using the results of the Capsule V radiation analysis. See Section 6.0 of the Capsule V analysis report, WCAP-14484*l. 1 Table 3 Fluence (10" n/cm', E > 1.0 MeV) on the Pressure Vessel Clad / Base Metal interface for Beaver Valley Unit 2 EFPY O' 45' 5.98 0.720 0.226 16 1.93 0.604 32 3.5 1.21 l l. Evaluation of PTS for Beaver Valley Unit 2 I
10 I \ l 6 DETERMINATION OF RTm VALUES FOR ALL BELTLINE l REGION MATERIALS i i I Using tha prescribed PTS Rule methodology, RTn, values were generated for all beltline I j region materials of the Beaver Valley Unit 2 reactor vessel for fluence values at the EOL (32 EFPY). Each plant shall assess the RTn, values based on plant-specific surveillance capsule data. For Beaver Valley Unit 2, die related surveillance program results have been included in this l PTS evaluation. Specifically, the Beaver Valley Unit 2 plant-specific surveillance capsule data for the intermediate shell plate B9004-2 and weld metal is provided for the following reasons:
- 1) There have been two capsules removed from the reactor vessel, and the data is deemed credible per Regulatory Guide 1.99, Revision 2.
- 2) The surveillance capsule program is credible (See Appendix A).
l As presented in Table 4, chemistry factor values for Beaver Valley Unit 2 based on average copper and nickel weight percent were calculated using Tables 1 and 2 from 10 CFR 50.6119. Additionally, chemistry factor values based on credible surveillance capsule data are calculated in Table 5. Table 6 contains the RTn, calculations for all beltline region materials l ct 32 EFPY. Table 4 Interpolation of Chemistry Factors Usirs Tables 1 and 2 of 10 CFR Part 50.61 Material Ni, wt % Chemistry Factor, 'F Intermediate Shell Plate B9004-1 0.55 40.5 Given Cu wt% = 0.065 Intermediate Sheet Plate B9004-2 0.57 37 i Given Cu wt% = 0.06 f' Lower Shel! Plate B90051 0.58 51 Given Cu wt % = 0.08 Lower Shell Plate B9005-2 0.57 44 Given Cu wt % = 0.07 Weld Material 0.07 34.1 Given Cu wt % = 0.05 Evaluation of PTS for Beaver Valley Unit 2
11 Table 5 Calculation of Chemistry Factors Using Surveillance Capsule Data Per Regulatory Guide 1.99, Revision 2, Position 2.1 Material Capsule Capsule f(*) FFW ART ,* FF* ART, FF' intermediate Shell Plate U 0.601 0.857 24.3 20.8 0.735 B9004-2 (Longitudinal Orientation) V 2.64 1.26 55.9 70.4 1.59 Intermediate U 0.601 0.857 17.6 15.1 0.735 Shell Plate 89004-2 V 2.64 1.26 46.3 58.3 1.59 (Transverse Orientation) SUM 164.6 4.66 CFm,% = I(FF
- ART ) + I(FF')
= 35.3*F Weld Metal" U 0.601 0.857 3.6 3.1 0.735 V 2.64 1.26 25.5 32.1 1.59 SUM 35.2 2.32 CFwm, = I(FF
- ART ) + I(FF')
= 15.2*F NOTES:
(a) f = fluence (10 n/cm', E > 1.0 MeV). A!! updated fluence values were taken from the Capsule V analysis (WCAP-14484M ). (b) FF = fluence factor = f 8"*"N0 (c) ART, values wero obtained from the Capsule V analysis N, rounded to one-decimal. (d) The reactor vessel intermediate to lower shell circular weld seam was made with the same weld wire and flux as the surveillance weld specimens. (Weld wire heat no. 83642, flux type Linde 0091, flux lot no. 3536) i Evaluation of PTS for Beaver Valley Unit 2
l 12 \ . Table 6 RTn, Calculations for Beaver Valley Unit 2 Beltline Region Materials at EOL (32 EFPY) mummmmmmmmmmmmmmmmemummmmemammmmemammmmmemummmmmmemummmmemummmmmme - Material Method CF f'O FF" RTon k M ARTns RTn , (*F) ('F) (*F) (*F) (*F) Ir;ter. Shell RG 1.99, R2, P1.1 40.5 3.85 1.348 60 34 54.6 149 Plate B9004-1 Inter. Shell RG 1.99, R2, P1.1 37.0 3.85 1.348 40 34 49.9 124 Plate B9004-2 RG 1.99, R2, P2.1 35.3 3.85 1.348 40 17 47.6 105 Lower RG 1.99, R2, P1.1 51.0 3.85 1.348 28 34 68.8 131 Shell Plate 89005 1 Lower RG 1.99, R2, P1.1 44.0 3.85 1.348 33 34 59.3 126 Shell Plate B9005-2 ; Cire. Weld RG 1.99, R2, P1.1 34.1 3.85 1.348 -30 45.9 45.9 62 RG 1.99, R2, P2.1 15.2 3.85 1.348 -30 20.5 20.5 11 Long. Weld RG 1.99, R2, P1.1 34.1 1.21 1.053 -30 35.9 35.9 42 l RG 1.99, R2, P2.1 15.2 1.21 1.053 -30 16.0 16.0 2 NOTES: (a) f = peak clad / base rnetal interface fluence (10 n/cm2 , E > 1.0 MeV) at 32 EFPY (45' fluence for longitudinal welds) (b) FF = f 82' * *'* * (c) RT , values are measured values 1 Evaluation of PTS for Beaver Valley Unit 2
13 7 CONCLUSIONS As shown in Table 6, all of the beltline region materials in the Beaver Valley Unit 2 reactor vessel have EOL RTn, values well below the screening criteria values of 270 F for plates or ; forgings and longitudinal welds and 300*F for circumferential welds at EOL (32 EFPY).
]
I l l I Evaluation of PTS for Beaver Valley Unit 2
,,a' 34 i
-8 REFERENCES
- 1. i10 CFR Part 50.61, " Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events", Federal Register, Volume 60, No. 243, dated December 19,1995, effective January 18,1N6. J
- 2. Regulatory Guide 1.99, Revision 2, " Radiation Embrittlement of Reactor Vessel Materials," U.S. Nuclear Regulatory Commission, May 1988.
- 3. - WCAP 9615 Rev.1, "Duquesne Light Company Beaver Valley Unit 2 Reactor Vessel ,
Radiation Surveillance Program", P. A. Peter , June 1995. !
- 4. WCAP-12406, " Analysis of Capsule U from the Duquesne Light Company Beaver Valley ll Unit 2 Reactor Vessel Radiation Surveillance Program", S. E. Yanichko, et. al., l
- September 1989.
Si ' WCAP-14484, " Analysis of Capsule V from the Duquesne Light Company Beaver Valley Unit 2 Reactor Vessel Radiation Surveillance Program", P. A. Grendys, et. al., February 1996.
- 6. Combustion Engineering, Inc., Materials Certification Report, Contract No. 9071, Code No. 9004-1, J. M. Amold,7/31/72.
L l 7. Combustion Engineering, Inc., MateriaIs Certification Report, Contract No. 9071, Code No. 9004-2, J. M. Arnold, 11/17/72.
- 8. CE Power Systems, Westinghouse Contract No. 9071, " Intermediate and Lower Shells Analyzed to ASTM E-350 Sample Obtained at 1/4 Thickness", W. A. House,8/19/76.
- 9. Combustion Engineering, Inc., Materials Certification Report, Contract No. 9071, Code No. 9005-1, J. M. Arnold, 12/04/72.
- 10. Combustion Engineering, Inc., Materials Certification Report, Contract No. 9071, Code No. 9005-2, J M. Arnold, 12/04/72.
- 11. CE Power Systems, Westinghouse Contract No. 9071, weld chemical analysis, W. A. House,8/19/76.
- 12. Metallurgical Research and Development, Chemical Analysis of Wire flux Test Weld Coupon, Heat No. 83642, Flux 0091, Lot No. 3536, dated 10/12/72.
- 13. Attachment 2 to JPN PSL-SESP-93-47 Rev. O, " Table 1: St. Lucie Unit 2 Reactor Vessel Beltline Wold Material". This table is from Florida Power and Light Company's response the NRC RAl.
- 14. Combustion Engineering Check Analysis, Contract 9071, Plate B-9004-2.
Evaluation of PTS for Beaver Valley Unit 2
- g. * . 15 ;
i
- 15. Letter Report MT/ SMART-210(88), " Response to U.S. Nuclear Regulatory Commission Generic Letter 88-11 for the Beaver Valley Unit 2 Reactor Vessel" N.K. Ray, et al., i November 1988. j
- 16. 10 CFR 50, Appendix G, " Fracture Toughness Requirements", Federal Register, Volume 60, No. 243, dated December 19,1995.
- 17. Westinghouse Calc. Note # 1, " Fracture Toughness Properties of Beaver Valley Unit 2 ;
(DMW) Reactor Vessel Core Region", S.E. Yanichko, December 1976. (File No. SM- ! 13.2 (DMW)).
- 18. Westinghouse Calc. Note # 95-022, Rev. 0: " Beaver Valley Unit 2 Surveillance Capsule V and HU/CD Curve Calculations"; Dated 11/12/95.
- 19. WCAP-9228, " Central Nuclear de Almaraz, Almaraz Unit No. 2 Reactor Vessel Radiation Surveillance Program", P.J. Fields, et. al., December 1977.
I I Evaluation of PTS for Beaver Valley Unit 2
g.. 16 V APPENDIX A: SURVEILLANCE DATA CREDIBILITY EVALUATION Regulatory Guide 1.99, Revision 2, describes general procedures acceptable to the NRC staff for calculating the effects of neutron radiation embrittlement of the low-alloy steels currently used for light-water-cooled reactor vessels. Position C.2 of Regulatory Guide 1.99, Revision 2, describes the methodology for calculating the adjusted reference temperature and Charpy upper-shelf energy of reactor vessel beltline materials using surveillance capsule data. The methods of Position C.2 can only be applied when two or more credible surveillance data sets become available from the reactor in question. To date, there have been two surveillance capsules removed from the Beaver Valley Unit 2 reactor vessel. This capsule data must be shown to be credible. In accordance with the discussion of Regulatory Guide 1.99, Revision 2, there are five requirements that must be met
~ for tho' surveillance data to be judged credible.
The purpose of this evaluation is to apply the credibility requirements of Regulatory Guide 1.99, Revision 2, to the Beaver Valley Unit 2 reactor vessel surveillance data and determine if the Beaver Valley Unit 2 surveillance data is credible. l 4 CrNorion 1: Atatorials in the capeutee should be those judged most likely to be controlling with regard to radiation embrittlement. The beltline region of the reactor vesselis defined in Appendix G to 10 CFR Part 50"*, ,
" Fracture Toughness Requirements", December 19,1995 to be: l
*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 radiation damage to be considered in the selection of the most limiting material with regard to radiation damage."
The Beaver Valley Unit 2 reactor vessel consists of the following beltline region materials (Ref. 17): a) Intermediate shell plates B9004-1 & B9004-2, heat numbers C0544-1 & C0544-2
. b) Lower shell plates B9005-1 & B9005-2, heat numbers C1408-2 & C1408-1 c) Circumferential weld, seam 101-171 d) Intermediate shell longitudinal weld seams 101-124A and 101-124B c) Lower shell longitudinal weld seams 101-142A and 101-142B
' NOTE: Per reference 18, all belthne welds were fabncated with 3/16 inch diameter weld wire type B-4, heat number s3642, Unde 0001 type flux, lot number 3536.
Evaluation of PTS for Beaver Valley Unit 2
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.* '* 17 4
Per WCAP-9615 Rev.1W , the Beaver Valley Unit 2 surveillance program was based on ASTM E185-73, ' Standard Recommended Practice for Surveillance Tests for Nuclear Reactor Vessels". Per Section 4.1 of ASTM E185-73, "The base metal and weld metal to be included in the program should represent the material that may limit the operation of the reactor during its lifetime. The test material should be selected on the basis ofinitial transition temperature, upper shelf energy level, and estimated increase in transition temperature considering chemical composition (copper (CU) and phosphorus (P)) and neutron fluence. " Therefore, at the time the Beaver Valley Unit 2 surveillance capsule program was developed, intermediate shell plate 89004-1 was judged to be most limiting based on the above recommendations and was utilized in the surveillance program (Ref.17). The surveillance program weld for Beaver Valley Unit 2 was fabricated using the same heat of weld wire used to fabricate the intermediate and lower shell vertical seams and girth welds (Ref.17). The results of mechanical property tests performed on the surveillance weld are considered to be representative of the property changes expected in the reactor vessel beltline seams. Therefore, the materials selected for use in the Beaver Valley Unit 2 surveillance program were those judged to be most likely controlling with regard to radiation embrittlement according to the accepted methodology at the time the surveillance program was developed. The Beaver Valley Unit 2 surveillance program meets this criteria. Criterion 2: Scatter in the plots of Charpy energy versus temperature for the Irradiated and unirradiated conditions should be small enough to permit the determination of the 30 ft-Ib temperature and upper shelf energy, unambiguously. Plots of Charpy energy versus temperature for the unirradiated condition are presented in WCAP-9615 Rev.1W 'Duquesne Light Company Beaver Valley Unit No. 2 Reactor Vessel Radiation Surveillance Program," dated June 1995. Plots of Charpy energy versus temperature for the irradiated conditions are presented in the WCAP reports (Ref. 4 & 5) for Capsules U and V. Based on engineering judgement, the scatter in the data presented in these plots is small enough to determine the 30 ft-lb temperature and the upper shelf energy of the Beaver Valley Unit 2 surveillance ma 3 rials unambiguously. Therefore, the Beaver Valley Unit 2 surveillance program meets this criteria. Evaluation of PTS for Beaver Valley Unit 2
- o o< 18 I
Criterlon 3: When there are two or more sets of surveillance data from one reactor, the scatter of ARTuor values about a best-fit line drawn as described in Regulatory Position 2.1 normally should be less than 28'F for welds and 17'F for base metal. Even if the fluence range is large (two or more orders of magnitude), the scatter should not exceed twice those values. Even if the data fall this criterion for use in shift calculations, they may ' be credible for determining decrease in upper shelf energy if the upper shelf can be clearly determined, following the definition given in ASTM E185-82. l The least squares method, as described in Regulatory Position 2.1, will be utilized in determining a best-fit line for this data to determine if this criteria is met. Beaver Valley Unit 2: Table Al" Beaver Valley Unit 2 Surveillance Capsule Data Calculation of Best-Fit Line as l Descnbod in Posson 2.1 of Regulatory Guide 1.99, Revision 2 l Material Capsule f* FF" ART, FF x ART, FF' (x) (y) (xy) (:') Interrnediate Shen U 0.601 0.857 2426 20.80 0.735 Plate B9004-2 i (Longitudinal) V 2.640 1260 55.93 70.50 1.590 I l Interrnediate Sheu U 0.601 0.857 17.56 15.10 0.735 Plate B9004-2 (Transverse) V 2.640 1260 4627 58.30 1.590 l f, 4234 144.02 164.70 4.660 0 0.601 0.857 3.64 3.10 0.735 Weld Metal V 2.640 1260 25.47 32.10 1.590 f., 2.117 29.11 3520 2.320 l NOTES: (a) f = Fluence (10* n/cm'. E > 1.0 MeV) (b) FF = Fluence Factor a f"8' "* (c) Values d f. FF and ART, were taken from Table 5 herein. l i l 1
\
l Evaluation of PTS for Beaver Valley Unit 2 i _ _ _ _ _ _ _ _ _ _ _ __ I
7___. l 19 Per the 2'A Edition of the CRC Standard Mathematical Tables (page 497), for a straight line fit by the rnethod of least
. squares, the values b, and b, are obtained by solving the normal equations n b,+ b, Ix, = Iy, and b,Ix,+ b,Ix8 = Ay, These equations can be re-written as follows:
n n j E y, = an + bE x, ist i=1 } and n n n [ Xyj i = 8[ X i + b[ X, i=1 i=1 61 Intermediate Shell Plate 89004 2: , Based on the data provided in Table A1, these equations become: 1 1.) 144.02 = 4a + 4.234b or a = 36.0 1.06b ; and ; 2.) 164.70 = 4.234a + 4.66b Thus, by substituting Eq.1 into Eq. 2, b = 72.24. Now, enter b (= 72.24) into Eq.1 and a = -40.60. Therefore, the equation of the straight line which provides the best fit in the sense of least squares is: Y = 72.24 (X) - 40.6 The error in predicting a value Y corresponding to a given X value is: e=Y Y. Table A2: Best Fit Evaluation for Intermediate Shell Plate Base Material (Orientation) ART , Best Fat ART, Scatter of ART, FF (30 ft lb)(*F) (*F) (*F) mummmmmmmmmmmmmm-mummmmmmmmmmmmme intermediate SheX Plate B9004-2 0.857 24.26 21.3 3.0 (Longdudhal) 1.260 55.93 50.4 5.5 Intermediate Sher Plate B9004 2 0.857 17.56 21.3 -3.7 (Transverse) 1.260 46.27 50.4 -4.2 Evaluation of PTS for Beaver Valley Unit 2
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The scatter of ART, values about a best-fit line drawn, as described in Regulatory Position 2.1, should be less than 17'F for base metal. As shown above, the error is within 17 F of the best-fit line. Therefore, this criteria is l met for the Beaver Valley Unit 2 surveillanco plate material. I Weld Metal: Based on the data provided in Table A1 the equations become: 1.) 29.11 = 2a + 2.117b or a = 14.56 1.06b and 2.) 35.20 = 2.117a + 2.32b Thus, by substituting Eq.1 into Eq. 2, b = 54.75. Now, enter b (= 54.75) into Eq. I and a = -43.48. Therefore, the equation of the straight line which provides the best fit in the sense of least squares is: Y' = 54.75 (X) - 43.48 The error in predicting a value Y corresponding to a given X value is: e = Y - Y' Table A3: Best Fit Evaluation for Weld Metal Base Material ART , Best Fit ART, Scatter of ART, FF (30 ft4b)('F) (*F) ('F)
-nummmmmmmmmmmmmmunumummmmmmmmmmmmmummmmmmmmmmmmu Weld Metal 0.857 3.64 3.44 0.2 1.260 25.47 25.51 -0.04 The scatter of ART, values about a best-fit line drawn, as desenbed in Regulatory Position 2.1, should be less :
than 28*F. As shown above, the error is within 28'F of the best-fit line. Therefore, this criteria is met for the Beaver Valey Unit 2 surveillance weld material. , I l l l l Evaluation of PTS for Beaver Valley Unit 2
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.. ' . - 21 Criterion 4: The irradiation temperature of the Charpy specimens in the capsule should match the vessel wall temperature at the claddinghase metalinterface within +/ 25'F.
The Beaver Valley Unit 2 capsule specimens are located in the reactor between the thermal shield and the vessel wall and are positioned opposite the center of the core. The test capsules are in baskets attached to the thermal shield. The location of the specimens with respect to the reactor vessel beltline provides assurance that the reactor vessel wall and the specimens experience equivalent operating conditions and will not differ by more than 25cF. Criterion 5: The surveillance data for the correlation monitor materialin the capsule should fall within the scatter band of the data base for that material. Beaver Valley Unit 2 did not incorporate correlation monitor material in their surveillance program. Therefore, criterion 5 is not applicable. j
Conclusion:
Based on the preceding responses to the criteria of Regulatory Guide 1.99, Revision 2, Section B, and the application of engineering judgement, the Beaver Valley Unit 2 surveillance data is credible. l l l Evaluation of PTS for Beaver Valley Unit 2 _ _ _ _ _ _ _ _ _ _ _ _ _ _ -}}