ML20198J565

Forwards Proprietery Rev 1 to WCAP-12045 & non-proprietary WCAP-12046,which Both Demonstrate That Indication Detected in Nozzle Shell-to-Intermediate Shell Weld Is Acceptable to Continue Svc.Proprietary Rept Withheld,Per 10CFR2.790(a)4

ML20198J565
Person / Time
Site:	Byron, Braidwood, Zion  File:ZionSolutions icon.png
Issue date:	10/15/1997
From:	Tulon T COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20046D900	List: ML20198J565 ML20198J570
References
NUDOCS 9710210140
Download: ML20198J565 (10)

Text

._ _ _

n mmimmuh Iilm n a umpam nraktw n ,il (,t ni taung Mahon Routr a l, ilus h e af Jt(1 tne, it (IO lO' 'Ril9

'It l Hl% 0 %M .'Nll October 15,1997 United States Nuclear Hegulatory Commission Attention: Docurnent Control Desk Washington, D.C. 20555-0001

Subject:

Draidwood Nuclear Pcwcr Station, Unit 2 Reactor Vessel Inspection Shell Weld Indication Evaluation N}LC.DElcLNo. 50-4 $7 Draidwood Unit 2 (Comed) is currently in a refueling outage (A2R06), during which an indication was detected in the Nonic Shell-to-intermediate Shell weld as part of the 10 3 car Insenice Inspection (ISI).

L Pursuant to the provisions of ASME Section XI,1983 Edition through Smumer 1983 Addenda. paragraph l

IWD 3125(b), Comed is submit'ing the attached evaintion which demonstrates that the indication is acceptable for continued senice.

Specifically, attached is Comed's evaluation, WCAP 12045 Revision I, 'llackgrout.d and Technical Basis: licndbook on Flaw Evaluation for the Zion, Byron and tiraidwood Units I & 2 Main Coolant System and Components" (Proprietary version) and WCAP 12046 'llandbook on Flaw Evaluation for Zion, Dyron, and Braidwood Units 1 and 2 Reactor Vessels" (Non Proprietary version). Please note that WCAP 12045 Rev.1 is proprictary and should be withheld from public disclosure in accordance with 10CFR2.790(a)4.

The affidavit disclosing the proprietary nature of WCAP 12045 Rev. I and the application for withholding will be forwarded under a separate coser letter. Comed is requesting the StafT complete their ictiew of this evahtation rior to October 31,1997, to support Braidwood Unit 2 restart.

Please address any comments or questions regarding this matter to T. W. Simpkin at (815) 458 2801 extension 2980.

Sincerely,

.(/ 8m Timothy J. Tule c l Site Vice President g' h l Draidwood Nuclear Generating S;ation i m e.wurn 6 Attachments cc: A. B. Deach, Regional Administrator Rlli G. F. Dick, Draidwood Project Manager . NRR C. J. Phillips, Senior Resident inspector . Braidwood OfTice of Nuclear Facility Safety IDNS 97102101409h1015 ~

PDR ADOCK 05000457 l$ lh l, llf lhllllfll PDR s . . ,

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l1 Attachment A Reactor Vessel Inspection Sliell Weld Indication Evaluation

1 Reactor Vessel Inspection Shell Weld Indication Evaluation INTRODUCTION j Pursuant to the provision of ASME Section XI,1983 Edition through Summer 1983 l Addenda, paragraph IWB 3125(b), Braidwood Station submits this document to demonstrate that the indication detected in the Nozzle Shell-to-intermediate Shell weld (Weld #2RV 01004 in Braidwood Unit 2) during the current refueling outage (A2R06) is acceptable for service without repair or replacement in accordance with the provisions of IWB 3122.4.

The subject indication was detected by ultrasonic testing (UT) of the Reactor Pressure Vessel (RPV) Shell welds, which is required by ASME Section XI,1983 Edition through Summer 1983 Addenda, Examination Category B-A, item Number B1.11, and 10CFR50.55a(g)(6)(;l)(A).

] UT INSPECTION TECHNIQUES AND QUALIFICATION Braidwood Unit 2 RPV shell welds were ultrasonically examined from the inside surface of the RPV by Framatome Technologies (FTI) using a mec5anized tool. The FTl procedure is a contact UT technique qualified in December 1995 to the Performance Demonstration initiative (PDl) program at the EPRI NDE Center. This inspection technique is being performed in accordance with ISI Program Relief Request NR 29,

, approved by the NRC on May 13,1997.

l Three transducers,45* shear,45' L wave and 70a L wave, were used to examine the full volume of the welds. The reference sensitivity, or DAC, is established on 1/8" diameter side drilled holes and scanning is performed at noise level.

INSPECTION RESULTS e PDIInspection l UT has detected one indication in weld 2RV-01004 (See Attached Figure 3).

This indication was detected at approximately 350' vessel azimuth with the 45' shear from both sides at amplitude levels of 109% and 194% of the reference.

l The indication length was determined by dropping the signal to noise level, and tip diffraction techniques were used to determine the planar depth. These sizing techniques use the same calibrations and transducers as the detection examination and are also PDI qualified. The indication is circumferentially i

oriented and is categcrized as a subsurface (or embedded) planar indication located near the outside surface (See Figures 1 and 2). The characteristics of the subject indication are:

S (distance from the indication to the nearest surface, OD) = 0.46 in.

2a (depth of indication) = 0.61 in.

I(length of indication) = 5.86 in, t (measured excluding nominal clad thickness of 0.1875 in.) = 8.91 in, Page I of 8

Figure 1 9.1" d Wcld Centerline ---

E ---------- 9 --

i l

FLAW e SupplementalInspection Additional examinations were performed on the area of concern to better characterize the indication. These examinations consisted of a Section XI, O' L.

wave, and a 45' and 60' shear wave. At a maximum gain of 38 db over reference, the O' L wave detected a spot or small portion of the indication. The indication was detected from both sides with the 45' examination at recordable l levels of 53% and 90% DAC amplitudes. The 60* examination did not detect the indication. These examinations have confirmed that the indication is a tight planar flaw, consistent with results of the PDI examinations. There is no conclusive evidence that slag is present.

. PSI Review The hard copy of the PSI NDE reports and the original videotapes of the A scan have been reviewed. The PSIinspections were conducted using an immersion UT technique. No indications were reported in this area. Efforts are underway to view the original fabrication radiographs and repair records, if any.

FLAW EVALUATION RESULTS e Evaluation per IWB 3500 This indication has been evaluated to the IWB-3500 Acceptance Standards and was found to exceed the limits of Table IWB-3510-1, " Allowable Planar Indications." The indication alt of 3.4% exceeds the maximum allowable alt of 2.4% for an aspect ratio of all = 0.05.

. Evaluation per IWB 3600 The subject indication was evaluated using the rules of IWB 3600 of ASME Section XI,1983 Edition with Summer 1983 Addenda. This is accomplished by using the " Handbook on Flaw Evaluation For Zion, Byron, and Braidwood Reactor Pressure Vessels" (WCAP-12045 and 12046) which was developed by Westinghouse based on the rules of IWB-3600 of ASME Section XI. Although Page 2 of 8

... ~ . .. . _ _ _ _-_ -- _ - . - _ _ _ -

l t

n these reports were prepared in 1988, the acceptance margins and code material properties used are unchanged $1nce that time.

Figure A 2.6 (See Attached Figure 4)in Section A 2 of the attached WCAP-4 12046 contains the applicable flaw evaluation chart for an embedded and circumferentially oriented indication in the Nozzle Shell-to-intermediate Shell

, Weld.

The Indication is located in the nozzle shell to intermediate shell weld, which is a Linde 80 weld, with heat number WF 645. The weld is located above the core region as shown in Figure 2 7 of WCAP 12045, so irradiation effects are negligible. To determine the acceptable flaw sizes, the flaw evaluation used the most limiting RTuoi of the two shell courses and the weld filler metal, all of which are provided in WCAP 12045.

Basic data:

t (Measured thickness excluding nominal clad thickness of 0.1875 in.) = 8.913in.

6 (S+a, Distance from the embedded flaw centerline to OD surface) = 0.765in.

a (Flaw depth, defined as one-half of the minor diameter) = 0.305ln.

I(Flaw length, major diameter) = 5.860in.

The following parameters are determined for evaluating the acceptability of an j embedded flaw

all (Flaw shape parameter or aspect ratio) =0.052in.

2a/t =0.068in.

alt (Flaw depth parameter) =0.0341n.

6(Distance from the centerline of the embedded flaw to OD surface) = 0.765in.

6/t (Surface proximity parameter) =0.086in.

The subject indication in weld 2RV 01004 with alt = 0.034 and 6/t = 0.086 is plotted to the right and below the " Surface / Embedded Flaw Demarcation Line" of Figure A 2.6 (See Attached Figure 4). The basis calculation for the acceptable embedded flaw sizes in Figure A 2.6 was limited to a maximum flaw size of 2a/t s 0.25. Since 2 alt = 0.068, this limitation on the Handbook applicability is met. Therefore, the embedded flaw is acceptable for service without repair or replacement.

To demonstrate the significant rnargins which exist for the indication, it was also evaluated with the assumption that it was a surface flaw. This is clearly not the case; based on IWA 3310, if S is 2 0.4a, the indication is a subsurface flaw. In this case, since S is 0.46 and 0.4a is 0.122, the indication is a subsurface flaw (0.46 2 0.122).

To evaluate the indication as a surface flaw, the depth becomes 2a + S = 1.07 inches, which gives alt = 0.117, and all = 0.18. Using Figure A 2.5 (See Attached Figure 5) of WCAP 12046 for circumferential outside surface flaws, a Page 3 of 8

flaw as large as alt = 0.2 is acceptable. Th&refore, there is a substantial margin on the acceptability of this indication even if it were evaluated as a surface flaw.

ADDITONAL AND SUCCESSIVE EXAMINATIONS Because the indication exceeds the applicable acceptance standards of IWB 3500, the ad&tional examination requirements of IWB 2430 apply. Based on the clarificat!on of IWB 2430(a), first published in the Winter 1983 Addenda of Section XI, these requirements have been satisfied by the initial examination scope performed during the current refueling outage of all similar components, i.e., all RPV Shell Welds in Examination Category B A, item Number B1,10.

Reexaminations of the subject indicathn will be performed at the next three Inspection Periods in accordance with the rules of IWB 2420, unless the NRC Staff approves an altemative approach, such as Code Case N 526.

CONCLUSIONR The subject indication was evaluated using the rules of IWB 3600 of ASME Section XI, 1983 Edition with Summer 1983 Addenda, and found to be acceptable without flaw removal, based on the Reactor Vessel design transients defined for the current 40 year license period of the plant.

Page 4 of 8

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Figure 3 Page 6 of 8

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Figure A-2.6 Evaluation Chart for Nozzle Shell to intermediate Shell Weld X Inside Surface Surface' Flaw _X Longitudinal Flaw X Outside Surface X Embedded Flaw X Circumferential Flaw Figure 4 Page 7 of 8

LEG [ND A - The 10, 20, 30 year acceptable flaw limits.

B - Within this zone, the  !

surface flaw is acceptable 20 A by Asnt Code analytical I N criteria in IWB-3600.

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] 0.1%20.1802 l FL AW SH APE (a#1 Figure A-2.5 Evaluation Chart for Nozzle Shell to Intermediate Shell Weld Inside Surface X Surface Flaw Longitudinal Flaw X Outside Surface Embedded Flaw X Circumferential Flaw .

-- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ . _ _ _ _ _ . _ _ . _ _ _ _ _ _ . . _ _ _ . _ _ _ . _ _ . _ _ . _ _ . _ _ _ _