ML14226A175

Request for Additional Information Regarding Relief Request 14-CN-001

ML14226A175
Person / Time
Site:	Catawba
Issue date:	08/15/2014
From:	Geoffrey Miller Plant Licensing Branch II
To:	Henderson K Duke Energy Carolinas
Miller G
References
TAC MF3527, TAC MF3528
Download: ML14226A175 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 August 15, 2014 Mr. K. Henderson Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 297 45

SUBJECT:

CATAWBA NUCLEAR STATION, UNITS 1 AND 2- REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST 14-CN-001 (TAC NOS. MF3527 AND MF3528)

Dear Mr. Henderson:

By letter dated February 20, 2014, Duke Energy Carolinas, LLC (Duke, the licensee), submitted relief request 14-CN-001 . The application requested relief from the volumetric examination coverage requirements of the ASME Code,Section XI.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's submittal and determined that additional information is needed in order to complete our review. The enclosed document describes this request for additional information (RAI). On August 5, 2014, the Duke staff indicated that a response to the RAI would be provided within 30 days of the date of this letter.

If you have any questions, please call me at 301-415-2481.

Sincerely,

. Edward Miller, Project Manager lant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-413 and 50-414

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST SERIAL NUMBER 14-CN-001 LIMITED VOLUMETRIC EXAMINATION OF CLASS 1 WELDS DUKE ENERGY CAROLINAS. LLC CATAWBA NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS. 50-413 AND 50-414 By letter dated February 20, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14052A387), Duke Energy Carolinas, LLC (Duke Energy) submitted relief request 14-CN-001. Pursuant to Title 10 of the Code of Federal Regulations Part 50.55a(g)(5)(iii), the request sought relief from the volumetric examination coverage requirements of the ASME Code,Section XI. In order for the NRC staff to complete its review of the relief request, the following additional information is requested.

RAI1 The NRC reviewed the volumetric examination coverage amounts obtained during the third 10-year inservice inspection (lSI) interval for the nine welds identified in Table 1 in Duke Energy's Relief Request 14-CN-001, and compared them to the coverage amounts obtained during the second 10-year lSI interval examinations. The NRC noted significant differences in the coverage amounts for the Catawba Nuclear Station (CNS), Units 1 and 2, pressurizer surge nozzle to head welds, as summarized in Table 1 below.

a. Explain the rationale for using the different scan angles to examine the pressurizer surge nozzle to head welds for both CNS units that led to the significantly different amount of coverage observed for these welds.

b. Explain the capability of the 35 degree scan angle to adequately detect flaws in the pressurizer surge nozzle to head welds compared to the standard 45 degree and 60 degree scan angles.

c. The figures in 14-CN-001 associated with this component indicate welds that have been ground flush. Clarify the surface condition of the welds and whether credit was taken for scans performed over the welds.

Enclosure

I I

Table 1. Pressurizer Surge Nozzle to Head Weld Examination Coverage Amounts 2na lSI Interval 3rd lSI Interval CNS Coverage and Scan Change Weld Coverage and Scan Unit Angles (t) Angles In Coverage

[Date of Exam, Source]

1 1-PZR-W1 81.4% 77.2% +4.2%

[2005, September 8,.2005 Relief Request (ML052590564)]

Scan angles used: Scan angles used:

35°, 45°, 60° i 35°, 45° 2 2-PZR-W1 81.2% 42.8% + 38.4%

[2001, December 20, 2001 Relief Request (ML0203300121 )]

Scan angles used: Scan angles used:

35°, 45°, 60° 60°, 70° Note: (1) Source: Relief Request 14-CN-001 (ML14052A387}.

ML14226A175 OFFICE NRR/LPL2-1 /PM NRR/LPL2-1/LA NRR/LPL2-1/BC NRR/LPL2-1/PM NAME GEMiller SFigueroa RPascarelli (GEMiller for) GEMiller (JRHall for)

DATE 08/15/14 08/14/14 08/15/14 08/15/14