ML20137M897

Documents Beltline Weld Chemistry Data Which Impacts Position Re Pressurized Thermal Shock (PTS) Issue & Addresses Reporting Requirements of 10CFR50.61.Reactor Vessel Beltline Matls Fall Below PTS Screening Criteria

ML20137M897
Person / Time
Site:	Fort Calhoun
Issue date:	01/23/1986
From:	Andrews R OMAHA PUBLIC POWER DISTRICT
To:	Thadani A Office of Nuclear Reactor Regulation
References
REF-GTECI-A-49, REF-GTECI-RV, TASK-A-49, TASK-OR LIC-86-024, LIC-86-24, NUDOCS 8601290097
Download: ML20137M897 (8)

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Omaha Public Power District 1623 Hamey Omaha. Nebraska 68102 2247 402/536 4000 January 23, 1986 LIC-86-024 Mr. Ashok C. Thadani, Project Director PWR Project Directorate #8 Division of PWR Licensing - B office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555

Reference:

Federal Register, Vol. 50, No. 141, Tuesday, July 23, 1985

Dear Mr. Thadani:

Fort Calhoun Specific Weld Chemistry Data Reporting Requirements of 10CFR 50.61 In accordance with the above reference, Omaha Public Power District, (OPPD) is required to submit to the Nuclear Regula-tory Commission the projected values of RTPTS (at the inner vessel surface) for the Fort Calhoun Station Unit No. 1 re-actor vessel beltline materials, giving values from the time of submittal to the expiration date of the operating license.

This letter documents recently obtained beltline weld chem-istry data which impacts Fort Calhoun's position with regard to the pressurized thermal shock (PTS) issue in addition to addressing the above mentioned reporting requirements of 10CFR 50.61.

In an effort to better address the PTS issue, a search of Com-bustion Engineering's, (CF's) weld records was performed in 1984 to determine beltline weld chemistries for the Fort Calhoun Station reactor vessel. Weld chemical composition analyses were obtained for all weld wire heats used in the beltline regica except weld wire heat 51989, which was used in the middle shell longitudinal seam welds. This heat was trac-ed to the torus longitudinal seam welds on the Fort Calhoun i l reactor vessel head. It was determined that weld chip samples l

could be removed from these welds for analysis. A conference call involving CPPD, CE, and NRC personnel was held on 7/30/85 to review plans for sampling this material during the 1985 re-fueling outage. As a recult of this conversation and others i between CE and NRC personnel, several items of NRC concern were introduced and preliminarily resolved. These NRC con-cerns are addressed in the following paragraphs.

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. A. C. Thadani LIC-86-024 Page 2 The first concern was how the location of the weld seams could be accurately distinguished from the surrounding base metal.

This was accomplished by polishing the areas to be sampled and then etching them with a nitric acid solution to reveal the weld outline. After the chip samples were removed, the sample areas were blended and inspected by magnetic particle testing.

Photographs were taken of the prepared surfaces after etching, after chip removal and after blending at all locations to docu-ment that only weld material was removed.

The second concern was the ability to distinguish between un-charted weld repairs and cosmetic welds. CE has determined that the possibility of an uncharted weld repair was small and that cosmetic welds were not performed on the OD weld surface, rather the submerged arc weld was ground smooth to the sur-face. To further minimize this concern, duplicate samples were obtained for each weld from different locations.

The results of optical emission chemical analyses performed on the chip samples, including a check analysis by x-ray fluor-escence for copper and nickel content, are shown in Table 1.

The report for all elements determined in the optical emission analysis is attached as Table 2. The optical emission values are an average of two analyses. The x-ray fluorescence values represent a single analysis. The chemical analysis results for wire heat 51989 are consistent with the values expected for a weld made with a Mil B-4 wire and a Linde Type 124 flux, as is indicated for these welds by the weld information re-cords. Likewise, the results of the chemical analyses for wire heat 13253 are consistent with a Mil B-4 Modified wire and Linde Type 1092 flux. The D.C. Cook and Salem 2 sur-veillance welds were also made with heat 13253 and a Linde Type 1092 flux. The nickel content of the Salem 2 (0.71 w/o) and D.C. Cook (0.74 w/o) surveillance welds are almost iden-tical to the Fort Calhoun (0.73 w/o) value, indicating that 13253 was the wire heat used, and further indicating that weld metal was sampled, since the base metal normally contains less than 0.60 w/o nickel. The copper contents between these welds i vary significantly (D.C. Cook - 0.27 w/o, Salem 2 - 0.23 w/o, l Fort Calhoun - 0.14 w/o). This can be attributed to the vari-l ation in copper coating on the coils of the wire making a heat of weld wire. This wide variation in copper has been observed on several other heats of wire for which multiple analyses are available. A portion of the samples from each weld seam was metallographically examined using a Nital solution to reveal the microstructural characteristics. In all cases, the exam-ination showed the fine-grained ferritic structure of weld metal.

. A. C. Thadani LIC-86-024 Page 3 The adequacy of a smaller chip sample as opposed to a full boat sample vas also a concern. This has been addressed by the fact that the Fort Calhoun closure head has a relatively small allowance for the removal of a sample and anything larger than the proposed chip sample might require a UT in-spection and some degree of analysis. Meaningful results have been obtained since it was possible to do metallography and chemical analyses on the same chip specimens.

Using the results of the closure head weld sampling for heats 51989 and 13253, and other available records, copper and nic-kol contents have been determined for each weld deposit in the Fort Calhoun reactor vessel beltline. These copper and nickel contents are presented in Table 3. The chemistry established for wire heat 27204 resulted frcm a search in October 1985 of the CE Metallurgical and Materials Laboratory chemical ana-lysis log books for weld deposit information and a review of data for the Diablo Canyon Unit #1 surveillance weld made with heat 27204. The lower shell longitudinal seam welds were each made using three heats of wire (27204, 12008, and 13253). It is not known whether only one or a combination of two of the wires were used to weld the ID of the seam. It was assumed for conservatism that the weld wire with the highest chemistry factor was used to weld the ID of the seam. Therefore, the copper and nickel content of wire heat 12008 was used in the PTS evaluation of these weld seams.

RT in accordance with 10bfkcalculationshavebeenperformed, 50.61, to determine the RT for each weld and plate inthereactorvesselbeltlineabTkheprojectedendoflicense life and at 32 EFPY. The results are presented in Table 4.

Fort Calhoun is currently licensed for operation through the year 2008. Assuming a capacity factor of 77% beyond Cycle 9 yields a projected end of license life at approximately 25 EFPY. Cycles 1-7 used a standard symmetric (i.e. out-in-in type fuel management) core loading pattern. A symmetric low radial leakage core loading pattern was utilized in Cycles 8 and 9. Although the Cycle 10 core was designed using an asymmetric loading pattern to further reduce fluence to the critical beltline welds, no credit has been taken in these calcilations for the additional flux reduction of Cycle 10 cver Cycles 8 and 9 in the RTPTS calculations. The limiting beltline material was found to be the lower shell longitudinal weld seam, 3-410 which currently has an RTPTS of 182*F (calculated at the end of Cycle 9, 7.9 EFPY) and is projected to have an RTPTS of 242*F at the end of license life (25 Further calculations for this weld project an EFPY).

. A. C. Thadani LIC-86-024 Page 4 RT of less than 265'F at 40 EFPY. Since all Fort Calhoun StkkfonreactorvesselbeltlinematerialsfallbelowthePTS screening criteria of 270*F, no further analysis nor schedule for the implementation of a flux reduction program is required.

Sincerely, Gd kk R. L. Andrews Division Manager Nuclear Production RLA/MJM/me Attachments cc: LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Ave., N.W.

Washington, DC 20036 E. G. Tourigny, NRC Project Manager P. H. Harrell, NRC Senior Resident Inspector

. Tabla 1 Wire Type: Mil B-4 Mil B-4 Mil B-4 Mod Mil B-4 Mod Heat No.: 51989 51989 13253 13253 Flux Type: Linde 124 Linde 124 Linde 1092 Linde 1092 Flux Lot: 3687 3687 3791 3791 Weld Seam: 1-415C 1-415E 2-145/A 2-415/A (near 1-415C) (near 1-415E)

CE Lab No.: D-41589 D-41591 D-41588 D-41590 Optical Optical Optical Optical Emission Emission Emission Emission (X-Ray Flour.) (X-Ray Flour.) (X-Ray Flour.) (X-Ray Flour.)

W/O W/O W/O W/O C 0.11 0.096 0.11 0.12 Mn 1.39 1.50 1.10 1.14 P 0.011 0.013 0.010 0.013

< S 0.009 0.011 0.008 0.011 Si 0.30 0.36 0.17 0.18 Ni 0.20 (0.18) 0.13 (0.114) 0.72 (0.72) 0.74 (0.72)

Cr 0.08 0.08 0.04 0.04 Mo 0.47 0.52 0.43 0.44 Cu 0.16 (0.17) 0.18 (0.18) 0.14 (0.14) 0.14 (0.14) 1

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C-E JOB NO. 99759617 PROJECT NO. 960001 CHEMICAL ANALYSIS REPORT C-E. Lcb No. D41588 D41589 D41590 D41591 Customer No.

Area 1 Area 1 Area 2 Area 2 Description 2-415-A 1-415-C 2-415-A 1-415-E C .11 11 .12 .096 Mn 1.10 1.39 1.14 1.50 I- .010 .011 .013 .013 S .008 .009 .011 .011 Si .17 .30 .18 Ni .36

.72 .20 .74 .13 Cr .04 .08 .04 Ma

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<.01 <.01 <.01 c . 01 As .010 .010 .013 Sn .011

.005 .006 .006 .006 2: <.001 <.001 <.001 < . 001 N .009 .015 .009 0 .009 Fe Keactor Vessel Closure Head Or.aha Public Power Dist.

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Cemt ust.on Engineenng. Inc. 911 West Ma:n Street (615) 265 4631 Chanaawga. Tennectee 37402 Teer 558429

Table 3 '

Chemical Content of Fort Calhoun Beltline Welds Material Chemical Content Weld Seam (Wire Heat / Flux Lot) Cu Ni

Comment / Source N 2-410 A/C 51989/3687 0.17 0.17 Fort Calhoun closure

{f head longitudinal weld sample.

3-410 A/C 27204/3774 0.22 1.02 Average of multiple weld deposit records g including PGr.E Diablo i

Canyon surveillance t weld.

13253/3774 0.21 0.73 Average of Salem #2 and Cook #1 surveil-lance welds, and Fort Calhoun closure head torus-to-done girth seam weld samples.

' 12008/3774 0.23 0.95 Average of multiple weld deposit records of tandem arc welds in h which second weld wire heat copper content known.

9-410 20291/3833 0.21 0.74 Cooper Station surveil-lance weld.

8-410 13253/3774 0.21 0.73 (see 3-410)

L 5 N '

- Tablo 4

, i s l s 'RT PTS for Font Calhoun Beltline Welds l Weld Cu Ni Chem.* RT RT RT Seam W/O '

' W/O Factor 25bhEE 32bhPY 40bhPY 2-410 0.'17 0.17 80 110*F ll6*F 123*F (longitudinal) 3-410 0.23 0.95 ' 175 235'F 250*F - 264*F (longitudinal) 8-410 0.21 0.73 142 192*F 205'F ' 216*F (circumferential) 9-410 0.21 0.74 143 193*F 206*F 217'F (Circumferential)

• Chemistry ' Factor = -10 + 470 (Cu) + 350(Cu) (Ni) 10CFR 50.61 Equation:

RTPTS = I + M + [-10 + 470(Cu) + 350'(Cu) (Ni) ] f0.270 I = generic mean value of initial reference temperature = -56*F for welds made with Linde 1092 and 124 fluxes.

M = margin to cover uncertainties in initial RTNDT = 59'F since generic value of I was used.

The PTS criteria applied to the vessel ID for longitudinal weld seams is RTPTS = 270*F and for circumferential weld seams is RTPTS = 300*F.

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