L-PI-16-056, Response to Request for Additional Information on the Fourth Ten-Year Lnservice Inspection Interval Relief Request Nos. 1-RR-4-11 and 2-RR-4-11

Response to Request for Additional Information on the Fourth Ten-Year Lnservice Inspection Interval Relief Request Nos. 1-RR-4-11 and 2-RR-4-11

ML16195A529
Person / Time
Site:	Prairie Island
Issue date:	07/13/2016
From:	Northard S Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CAC MF7210, CAC MF7211, L-PI-16-056
Download: ML16195A529 (6)

Text

(l Xcel Energy JUL 1 3 2016 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant Units 1 and 2 Docket Nos. 50-282 and 50-306 Renewed Facility Operating License Nos. DPR-42 and DPR-60 L-PI-16-056 10 CFR 50.55a Response to Request for Additional Information on the Fourth Ten-Year lnservice Inspection Interval Relief Request Nos. 1-RR-4-11, and 2-RR-4-11 (CAC Nos. MF7210 and MF7211)

References:

1) R. Kuntz, USNRC, email to G. Carlson, NSPM, Request for Information on the Fourth Ten-Year lnservice Inspection Interval Requests for Relief Prairie Island Nuclear Generating Plant Units 1 and 2 Docket Nos. 50-282 and 50-306 (CAC Nos. MF7210 and MF7211}, 6/16/2016 (ADAMS Accession No. ML16169A002)

2) K. Davison, PINGP, letter to NRC Document Control Desk, 10 CFR 50.55a Requests:

Relief from Impractical Examination Coverage Requirements for the Fourth Ten-Year lnservice Inspection Program Interval, L-PI-15-106, 12/21/2015 (ADAMS Accession No. ML15355A253)

Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), provides the enclosed responses (Enclosure

1) to requests for additional information (Reference

1) regarding reliefrequests 1-RR-4-11 and 2-RR-4-11 (Reference

2) for relief pursuant to 10 CFR 50.55a for alternatives to limited examination coverage requirements.

In addition to the enclosed responses, NSPM clarifies that relief requests 1-RR-4-11 and 2-RR-4-11 are made in accordance with 10 CFR 50.55a(g)(5)(iii) rather than 10 CFR 50.55a(z)(2).

Summary of Commitments This letter contains no new commitment and no revision to an existing commitment.

1717 Wakonade Drive East

• Welch, Minnesota 55089-9642 Telephone:

651.388.1121 NRC Document Control Page2 If there is any question or if additional information is needed, please contact Dr. Glenn A. Carlson, P.E. at 651-267-1755.

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Co f'cc...r (. t-o"-;r c..., r-r fo-l 012-T li Scott Northard Acting Site Vice President, Prairie Island Nuclear Generating Plant Northern States Power Company -Minnesota Enclosure (1) cc: Regional Administrator, Region Ill, USNRC Project Manager, Prairie Island Nuclear Generating Plant, USNRC Resident Inspector, Prairie Island Nuclear Generating Plant, USNRC ENCLOSURE 1 Response to Request for Additional Information on the Fourth Ten-Year lnservice Inspection Interval Relief Request Nos. 1-RR-4-11, and 2-RR-4-11 (CAC Nos. MF721 0 AND MF7211) 3 pages follow Enclosure 1 to L-PI-16-056 Page 1 of 3 Response to Request for Additional Information on the Fourth Ten-Year lnservice Inspection Interval Relief Request Nos. 1-RR-4-11, and 2-RR-4-11 (CAC Nos. MF7210 AND MF7211) RAI-2.1 Table 1 of the Relief Requests specifies the code used for the volumetric examination procedure for the Category C-A welds, but not for the surface examination procedure for the Category C-C welds. Provide the applicable code for the surface examination of the Category C-C attachment welds (e.g., ASME Code Section V, Article 6.). Also provide the applicable code criteria used to determine extent of surface to be examined (e.g., ASME Code Figure IWC-2500-5.)

Response:

The fourth interval surface examination of Category C-C attachment welds was performed in accordance with site dye penetrant procedures SWI NDE-PT-1.

This procedure incorporated by reference ASME Code Section V, Article 6 and ASME Section XI, Code Figure IWC-2500-5.

RAI-2.2 Section 6 of the Relief Requests states that only one support of PINGP, Unit 1 was surface examined and that the coverage was limited to 71%, but both supports of PINGP, Unit 2 were surface examined.

Describe why one of the supports of PINGP, Unit 1 was not surface examined, or clarify your statement.

Also, explain why the maximum obtainable coverage of 75% (as stated in Table 2) was not achieved for this surface examination.

Response:

It is important to note that the examinations and coverage discussed in section 6 are from the previous 3rd interval, and included in this request to show that fourth interval limitations are consistent with the previous third interval limitations accepted under previous relief requests.

The third interval (Section 6) and fourth interval (Table 2) maximum obtainable coverage for the subject welded attachments are comparable, but somewhat different.

ASME Section XI 2000 Addenda, item C3.1 0, note 4 states that "For multiple vessels of similar design, function, and service, only one welded attachment of only one of the multiple vessels shall be selected for examination." As such, not all supports are examined.

When an examination limitation is encountered, the site will typically make an effort to substitute another component within the appropriate item number and group in order to Enclosure 1 to L-PI-16-056 Page 2 of3 meet code requirements.

A review of fourth interval surface examinations of the RHR heat exchanger welded attachments of both units is summarized in Table 1. Component Description 12 RHR Heat Exchanger Attachment Weld (B) Int. Attach Weld 21 RHR Heat .Exchanger Attachment Weld (A) 21 RHR Heat Exchanger Attachment Weld (B) Table 1: Fourth Interval Surface Examinations of the RHR Heat Exchanger Welded Attachments Exam Code Percent Code Cat. Report Component, Coverage And Method and Obtained Item No. Extent and Required Limitation 2012P004 Class 2 Welded 75% Limited C-C Attachment with due to access. C3.10 no suitable substitute.

100% Surface. 2010P020 Vessel Welded 85% Limited C-C Attachments, due to C3.10 Surface, 1 00% proximity to One of similar concrete vessels support. 2010P021 Vessel Welded 85% Limited C-C Attachments, due to C3.10 Surface, 100% proximity to One of similar concrete vessels support. Relief Request 1-RR-4-11 Relief not required as only one welded attachment of only one of the multiple vessels shall be selected for examination.

2-RR-4-11 Review of the RH Heat Exchanger support construction drawing NF-38298-3 (typical both units), examination limitations experienced in the third interval (discussed in Section 6) and fourth interval limitations summarized above, indicate all RH Heat Exchanger support welded attachments have similar limitations.

RAI-2.3 Section 6 of the Relief Requests states that Weld 2 of the PINGP, Unit 1 residual heat removal heat exchanger 12 was ultrasonically examined and found to be limited to 27% coverage.

However, Figure 3 stated that the total examination coverage for this weld was 32%. Clarify this apparent discrepancy.

Response:

It is important to note that the examinations and coverage discussed in Section 6 are from the previous 3rd interval, and included in this request to show that fourth interval limitations are consistent with the previous third interval limitations accepted under Enclosure 1 to L-PI-16-056 Page 3 of 3 previous relief requests.

The third interval (Section 6) and fourth interval (Table 2 and Figure 3) maximum obtainable coverage for heat exchanger 12 Weld 2 are comparable, but somewhat different.

RAI-2.4 Table 2 of the Relief Requests states that "Other Examination Results" include a "System Pressure test." Explain how the system pressure test is relevant to determine the acceptability of the two Category C-C attachment welds. Response:

A system pressure test is relevant to Category C-C (WELDED ATTACHMENTS FOR VESSELS, PIPING, PUMPS, AND VALVES) only to the extent that a pressure test would show a crack that had propagated from an attachment weld through the pressure boundary.

There is no implication that pressure test is a substitute for the code required surface examination.