ML20151V360

Forwards Response to NRC 980610 RAI Re Weld Chemistry Values for BFN Rpvs.Util Has Determined That Current BFN P-T Curves & Other Corresponding Info Are Based on Conservative Weld Chemistry Data & Do Not Require Rev

ML20151V360
Person / Time
Site:	Browns Ferry
Issue date:	09/08/1998
From:	Abney T TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-92-01, GL-92-1, TAC-MA1179, TAC-MA1180, TAC-MA1181, NUDOCS 9809140274
Download: ML20151V360 (11)

Text

s s En Tennessee Vauey Authonty Post Off 6ce Box 2000. Decatur, Alabama 35609 September 8, 1998 I

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of ) Docket No. 50-259 Tennessee Valley Authority ) 50-260 50-296 I BROWNS FERRY NUCLEAR PLANT (BFN) - UNITS 1, 2, AND 3 - GENERIC LETTER (GL) 92-01, REVISION 1, SUPPLEMENT 1, REACTOR VESSEL  ;

STRUCTURAL INTEGRITY - RESPONSE TO NRC REQUEST FOR ADDITIONAL l INFORMATION (TAC NOS. MA1179, MA1180, AND MA1181)

This letter responds to the NRC June 10, 1998, request for additional information regarding weld chemistry values for BFN reactor pressure vessels (RPVs).

As a result of information presented in recent industry reports, the staff requested that TVA reevaluate the RPV weld chemistry values that were submitted previously as part of TVA's response to GL 92-01, Revision 1, Supplement 1, and determine whether BFN RPV weld chemistry value(s) need to be revised. The results of TVA's reevaluation of the BFN Units 1, 2, and 3 RPV weld chemistry values are provided in the enclosure.

In summary, TVA has determined that the current BFN P-T curves and other corresponding information are based on conservative weld chemistry data and do not require revision. I

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9809140274 99090s '

PDR hny'6 ADOCK 05000259 P pag , .

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U.S. Nuclear Regulatory Commission Page R September 8, 1998 There are no new commitments contained in this letter. If you have any questions, please contact me at (256) 729-2636.

Sincere y, y T. E. Abney f Manager of L censing and Industry Affairs Enclosure cc (Enclosure):

Mr. Harold O. Christensen, Branch Chief U.S. Nuclear Regulatory Commission Region II 61 Forsyth Street, S.W.

Suite 23T85 Atlanta, Georgia 30303 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611 Mr. Albert W. De Agazio, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 4

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ENCLOSURE TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

( UNITS 1, 2, AND 3 l GENERIC LETTER (GL) 92-01, REVISION 1, SUPPLEMENT 1, REACTOR VESSEL STRUCTURAL INTEGRITY l RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION I

Background

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TVA is responding to the NBC June 10, 1998, request for j additional information regarding reevaluation of weld  !

chemistry values for the BFN reactor pressure vessels (RPVs). I Generic Letter 92-01, Revision 1, Supplement 1, Reactor Vessel Structural Integrity, was issued on May 19, 1995. The GL requested licensees to perform a review of their reactor j pressure vessel (RPV) structural integrity assessments to l identify, collect, and report any new data pertinent to the )

analysis of the structural integrity of their RPVs. TVA provided its response for BFN Units 1, 2, and 3 by letters dated August 17, 1995, and November 7, 1995, stating that previous evaluations remained valid. The NRC staff acknowledged that TVA had provided the reruested information by letter dated July 26, 1996.

Subsequently, the Boiling Water Reactor Vessel and Internals Project (BWRVIP) submitted a report, " Update of Bounding Assessment of BWR/2-6 Reactor Pressure Vessel Integrity Issues (BWRVIP-4 6) . " This report included bounding assessments of new data from (1) the Combustion Engineering Owners Group (CEOG) database rele4 sed in July 1997 which contains data for CE fabricated welds in pressurized-water reactor and BWR vessels; (2) Framatone Technologies Incorporated (FTI) analytes of Linde 80 welda which are documented in NRC Inspection Report 99901300/97-01 dated January 28, 1998; (3) FTI's analysis of electroslag welds which was referenced in a Dresden and Quad Cities Pressure Temperature (P-T) limits submittal dated September 20, 1996; and (4) Chicago Bridge and Iron quality assurance records.

As a result of the information presented in the CEOG, FTI, and BWRVIP reports, the staff requested that TVA reevaluate the RPV weld chamistry values that were submitted previously as part of TVA's response to GL F2-01, Revision 1, Supplement 1, l

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I and determine whether the BFN RPV weld chemistry value(s) need.

to be revised. The results of TVA's reevaluation for the BFN Units 1, 2, and 3 RPV weld chemistry values are provided below.

BFN Unit 1 The limiting material for the BFN Unit 1 RPV is the submerged arc circumferential weld. The current reported chemistry for this weld is 0.31 percent copper and 0.59 percent Nickel i based on the Babcock and Wilcox (BAW) report BAW-1845 and TVA calculation BFN-MTB-009. These values for copper and nickel correspond to a chemistry factor of 196.7.

The latest "best estimate" chemistry values for the BFN Unit 1 limiting material (submerged arc weld WF 154) is available in BAW-2325. This report provides values of 0.27 percent for copper and 0.60 percent for nickel (Attachment 1). These "best estimate" values provide a chemistry factor of 154.

An analysis of these weld chemistry values shows a slightly higher nickel content but a lower (184), less conservative, chemistry factor than currently used by BFN Unit 1. Therefore, the current BFN Unit 1 P-T curves are based on conservative PPV weld chemistry data and do not require revision.

BFN Units 2 and 3 The limiting materials fo' tna BFN Units 2 and 3 RPV are the electroslag (ES) longitudinal welds. The original reported chemistry values for these welds is 0.25 percent copper and 0.35 percent nickel based on BAW-1845. TVA revised the value for copper to 0.28 percent utilizing the methodology provided in Regulatory Guide 1.99, Revision 2, as documented in TVA calculation BEN-MTB-009.

The "best estimate" chemistry values for BFN Units 2 and 3 for copper and nickel were taken from BAW-2258/2259. BAW-2258/2259 l

represents Framatome Technology's best assessment of ES welds for the Dresden and Quad Cities reactors. These reports utilized an NRC endorsed approach for "best estimate" chemistry determination identified as "mean of the sources." This

( approach uses relevant data in determining applicable chemistry values by incorporating values obtained from applicable sources. Since these reports include data from various plants, including Brtwns Ferry, they have been used to reassess the l currently reported chemistry values. Attachment 2 shows the grouping and calculations associated with this new data.

Utilizing this approach, the newly obtained "best estimate" values for copper and nickel are 0.24 percent and 0.37 percent E-2

l respectively. Based on these values for copper and nickel, the new chemistry factor for BFN Units 2 and 3 was determined to be 141.

t l It should be noted that a discrepancy was observed in l BAW-1845 during this review. While the document text

! reports 0.35 percent nickel for Welding Procedure j Qualification (PQ) 1851, the actual PQ in Appendix E of l BAW-1845 lists nickel at 0.36 percent. TVA has previously l used 0.35 percent in determining the chemistry factor (CF) .

l The corrected chemistry factor (155.6) is slightly more conservative than the 154.5 CF currently used for BFN Units 2 and 3. However, the new "best estimate" CF, as described above, for BFN Units 2 and 3 is 141. This value is more than eight percent lower (i.e., less conservative) than either the current CF (154.5) or the corrected CF (155.6).

Additionally, TVA has determined that the difference between j the current CF and the corrected CF is small enough that any effect on the BFN Units 2 and 3 P-T curves would be i negligible. Therefore, the current BFN Units 2 and 3 P-T curves are based on conservative RPV weld chemistry data and do not require revision.

Current Licensing Basis from BFN MTB-009 Corrected Data Weld PQ Nickel Copper Weld PQ Nickel Copper PQ-1300 0.33 0.30 PQ-1300 0.33 0.30 PQ-1667 0.25 0.20 PQ-1667 0.25 0.20 PQ-1851 0.35 0.18 PQ-1851 0.36 0.18 Mean 0.310 0.227 Mean 0.313 0.227 agdad Standard 0.043 0.053 0.046 0.053 deviation ~~

deviation Mean plus Mean plus Standard 0.35 0.28 Standard 0.36 0.28 deviation deviation Chemistry Chemistry 154.5 155.6 Factor ) Factor Conclusions l Based on TVA's review, new "best estimate" chemistry values

have been determined for copper and nickel for the BFN Units 1, 2, and 3 RPVs. The corresponding information has been tabulated as requested by the NRC utaff. TVA has determined j that the nickel content increased slightly for all BFN units.

However, due to a corresponding decrease in copper content the 1

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resulting chemistry factor decreased. This results in a lower adjusted reference temperature (ART) than presently calculated.

As a result, the current BFN Units 1, 2, and 3 P-T curves, and other corresponding information, are based on more conservative RPV weld chemistry data that that reflected in the new "best estimate" chemistry values. TVA has determined that the BFN Units 1, 2, and 3 P-T curves do not require revision. TVA has also determined that there has been no adverse impact on any BFN safety related system as a result of this review. The information requested by the NRC staff for BFN Units 1, 2, and 3 is provided in Table 1.

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l Notes and References i 1

1. All equations were taken from NRC Regulatory Guide 1.99, Revision 2, Page 3.

2. The Assigned Material Chemistry Factor was linearly l interpolated from Table 1, of NRC Regulatory Guide 1.99, l Revision 2, Page 4. '

3. The value of "x" used in determining the vessel wall at l one quarter of the wall thickness is based on dimensions shown in TVA Calculation ND-Q0999-900054.

4. The precision of the Charpy impact test used in determining the Initial RTmn is estimated to be 10 degrees Fahrenheit. Therefore, a1 is estimated to be 10 degrees Fahrenheit. (TVA Calculation ND-Q0999-900054, Section 5.3)

5. Data for the Initial RTmn for Units 2 and 3 were obtained from TVA Calculation ND-Q0999-900054, Section 5.1, which states that the NRC has determined a generic upper bound of the initial RTmn for electroslag welds to be 10 degrees Fahrenheit. The Initial RTmn for Unit 1 is also found in the same section.

6. End of Life Inside Diameter (EOL ID) Fluence values for Units 2 and 3 are listed under the General Electric Power Uprate Evaluation Report, Task 09-1, section 3.0. The value for Unit 1 was taken from the update to GL 92-01 transmitted by TVA letter to NRC dated March 27, 1995.

7. The " Previous ART values" for Units 2 and 3 were developed using chemistry values of 0.28 percent copper and 0.35 percent nickel obtained from TVA Calculation BFN-MTB-009, Section 5.1. The value for Unit 1 was developed using chemistry values of 0.31 percent copper and 0.59 percent nickel also obtained from TVA Calculation BFN-MTB-009, Section 5.1.

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l-ATTACHMENT 1 Submerged Arc Weld l BAW-2325 l Analysis ,

i Unit 1 Weld ID Flux Lot Source Copper Nickel Reference

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1 Note: Cu content  !

lower than WQ retest )

Mt. Vernon analysis and analyses  !

WF-154 8720 WQ: Lab 0.20 0.59 on production welds; No.8151 Cu content not used ,

in source mean l calculction.

Retest of WQ 0.25 -

i Sarnple Retest 0 27 0.59 Retest 0.26 0 60 Mean of Sources 0.26 0.59 tagdard 0.01 0.01 Deviation Mean plus Standard 0.27 0.60 Deviation l

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Attawiarant 2

, , Bectroslag Weld DWa per BAW2259 Units 2and 3 Procedtre Qualification Crenical Omposition Data Weld PQ Nckel Copper PQ 1092-C 0.31 0.24 PQ 1138-A 0.35 0.25 PQ 1300 0.33 0.30 PQ-1309-A 0.30 0.22 PQ-1309-B 0.29 0.23 PQ-1667 0.25 0.20 PQ-1822. 0.27 0.23 PQ-1851 0.36 0.18 PQ-1928 0.38 0.19 PQ-1929 0.30 0.20 PQ-1930 0.26 0.20

_ PQ.10931 0.38 0.19 Sun eillan and Beltline Weld Chenical Composition [Wa Spccimen and Average Average gg Plant ID Nckel Copper

• ' 0"'d 0.28 0.17 Cities 1 (QC1)

MM QC1 0.25 0.136 0.26 0.19 NPDQC1 0.26 0.138 0.38 0.19 M7LQC1 0.30 0.20 NBUQC1 0.33 0.24 MBDQC1 0.39 0.16 NDCQC1 0.40 0.21 ND4 QC1 0.33 0.19 NBYQC1 0.40 0.21 0.33 0.18 Cities 1 es 0.313 0.129 2(QC2) 0.32 0.14 TAT QC2 0.359 0.122 0.33 0.16 TEPQC2 0.34 0.16 TB1 QC2 0.37 0.17 TBKQC2 0.39 0.17 TBMOC2 0.37 0.17 T72QC2 0.41 0.20 TAP QC2 0.32 0.12 TD1 QC2 0.20 0.18 0.34 0.16 Cities 2 E-7

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, , ATTACHMENT 2, (Continued) 4 Specimen and ^ # 89' ^ # *9' Nickel Copper Plant ID Nickel Copper ES Weld Dresden 0.3 0.2 (D) 3 KAE D3 0.332 0.191 t

0.29 KAL D3 0.282 0.171 0.33 0.18 K6L D3 0.41 0.24 KSA D3 0.38 0.23 KBM D3 0.36 0.22 K6T D3 0.38 0.19 i KAJ D3 0.34 0.21 KAD D3 0.34 0.21 Overall Dresden 3 0.35 0.21 Peach Bottom 2,3 0.21 0.21 0.21 0.21 prolongations -

Brown's Ferry 1 0.30 0.10 0 50 0.10 Brown's Ferry 2 0.33 0.20 0 33 0.20 Brown's Ferry 3 0.28 0.11 0.28 0.11 Peach Bottom 2 0.32 0.09 0.32 0.10 Overall PB2 0.32 0.10 Peach Bottom 3 - 0.4 0.11 0.41 0.11 Overall PB3 0 41 0.11 j i

l Nickel Copper New mean of 0.32 0.19 sources Standard 0.05 0.05 Deviation Mean plus the standar 0.37 0.2 l deviation E-8 1

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TABLE 1 I Browns Ferry Nuclear F'lant information requested on RPV Weld and/or Limiting Materials EOL ID Assened est Best h*aterial Method of Initial ART or ART with RPV Weld Fluence Unii Wire Heat ate N ate em DeteWa% Mer oi 03 Mn Mer a t "pmhf Copper Nickel (x10'D or Factor CF EOL values (RTmrctn)

(CF) 1 SA 0.27 0.60 0.0762 184 table 20 10 27.6 58.7 i33.8 141.2  ;

2 ES 0.24 0.37 0.0778 141 table 10 10 21.4 47.2 99.9 107.7  ;

3 ES , 0.24 0.37 0.0924 141 table 10 10 23.4 50.9 107.7 116.2 Unit f (x10) ff ARTer j 1 0.0522 0.2996 55.1 2 -0.0533 0.3029 42.7 3 0.0033 0.3317 46.8 ART = lnitial RTer + ARTer + Margin ARTer = (CF) x fluence factor (ff) gg = y (0.2s .o.1oiog n f = f.,,fe424x) where X equals .25 * (6.125 + .1875)

Margin = 2(o,2 y,2)1/2 ,

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o3 = .5(ARTer)

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