GO2-05-153, Analytical Evaluation of Inservice Inspection Examination Results

Analytical Evaluation of Inservice Inspection Examination Results

ML052710359
Person / Time
Site:	Columbia
Issue date:	09/15/2005
From:	Oxenford W Energy Northwest
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GO2-05-153
Download: ML052710359 (3)

Text

Xj-- ENERGY k' -NORTHWEST People. Vision *Solutions P.O. Box 968

• Richland, WA

• 99352-0968 September 15, 2005 G02-05-1 53 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject:

COLUMBIA GENERATING STATION, DOCKET NO.60-397 ANALYTICAL EVALUATION OF INSERVICE INSPECTION EXAMINATION RESULTS

Reference:

ASME Section Xi, 1989 Edition, "Rules for Inservice Inspection of Nuclear Power Plant Components"

Dear Sir or Madam:

During the recent 2005 refueling outage, Energy Northwest detected two indications in the reactor pressure vessel (RPV) of Columbia Generating Station. The indications exceeded the acceptance standards listed in Table IWB-3510-1 of the Reference. The indications were evaluated and determined to be acceptable for continued service without repair. The evaluation results are provided in the Attachment.

The analytical evaluation of the weld examination results for the indication, as required by Subsection IWB-3134(b) of the Reference, is provided in the Enclosure.

If you have any questions or require additional information regarding this matter, please contact GV Cullen, Licensing Supervisor at (509) 377-6105 Respectfully WS Oxenf d Vice Pres dent, Technical Services Mail Drop PE04

Attachment:

ASME Section XI, IWB-3600 Evaluation

Enclosure:

Energy Northwest Calculation ME-02-05-07, Revision 1, "Evaluation of RPV Shell Indications Identified During R-17 ISI" cc: BS Mallett - NRC RIV NRC Sr. Resident Inspector - 988C t.OqtI BJ Benney - NRC NRR RN Sherman - BPA/1399 WC Sifre - NRC RIV WA Horin - Winston & Strawn

ANALYTICAL EVALUATION OF INSERVICE INSPECTION EXAMINATION RESULTS ASME Section Xl, IWB - 3600 Evaluation Attachment Page 1 of 2 INTRODUCTION Two indications were identified during the Spring 2005 inservice inspection of the Columbia Generating Station (Columbia) reactor pressure vessel (RPV). The indications are located in Category B-A, Item Number B1.12 welds. The indications exceeded the acceptance standards listed in Table IWB-3510-1 of the ASME Boiler and Pressure Vessel (B&PV) Code,Section XI, 1989 Edition, no Addenda (Columbia's current inspection interval code). An analytical evaluation of the indications was performed in accordance with ASME Section Xl, IWB-3600. This evaluation demonstrated that the welds are acceptable for continued service without repair.

Automated ultrasonic examinations were performed to satisfy the examination requirements of ASME B&PV Code,Section XI, 1989 Edition, no Addenda; Section Xl, 1995 Edition with the 1996 Addenda as modified by the Performance Demonstration Initiative (PDI) program description; and the Federal Register, Part II, Nuclear Regulatory Commission, 10 CFR Part 50 for Category B-A RPV longitudinal shell welds.

ULTRASONIC INSPECTION TECHNIQUE Automated ultrasonic examinations were performed using 45 degree shear wave, 60 degree refracted longitudinal (RL) wave, and 70 degree RL wave search units from the outside surface of the RPV. The examinations were performed in accordance with ASME Section Xl, Appendix VI1I, as modified by 10 CFR 50.55a and the PDI.

EXAMINATION RESULTS The two indications were recorded utilizing a 45-degree shear wave search unit. The two indications are planar indications located in the beltline longitudinal welds of the RPV. The first indication is located in the base material adjacent to longitudinal weld BG. This subsurface indication has a depth of 0.39 inches, a length of 3.0 inches, with a surface separation of 2.68 inches. The second indication is in longitudinal weld BM.

This indication has a depth of 0.38 inches, a length of 3.75 inches, with a surface separation of 2.78 inches. The lower nominal wall thickness of 6.4375 inches is used in the evaluation for welds BG and BM. For flaw evaluation this is conservative since for a given flaw size the plate is more flaw tolerant with greater thickness.

The indications were then evaluated but failed to meet the acceptance criteria of ASME Section Xl, Table IWB-3510-1. Therefore, an analytical evaluation in accordance with ASME Section Xi, IWB-3600 was required to be performed. The analysis is provided as the Enclosure.

ANALYTICAL EVALUATION OF INSERVICE INSPECTION EXAMINATION RESULTS ASME Section Xi, IWB - 3600 Evaluation Attachment Page 2 of 2 IWB-3600 FLAW EVALUATION RESULTS The Enclosure calculated the crack growth an d the stress intensity factors for the two indications described above. The evaluation showed that the stress intensity factors for normal and faulted conditions were less than the allowable stress intensity factors permitted by IWB-3612 of ASME Section Xl. The crack growth when 500 safety relief valve blowdown events were applied was 0.0064 inches over the life of the plant. This growth is negligible compared to the original indication sizes, which were determined to be acceptable by the rules of ASME Section Xl.

CONCLUSIONS Analytical evaluation of the indications identified above has determined that they are acceptable under the rules of ASME Section Xl IWB-3600. In accordance with IWB-3132.4, welds BG and BM are-acceptable for continued service.