ML14188C478

Draft RAI for Catawba RR 14-CN-001

ML14188C478
Person / Time
Site:	Catawba
Issue date:	07/07/2014
From:	Ed Miller Division of Operating Reactor Licensing
To:	Rudy L J Duke Energy Corp
References
Download: ML14188C478 (4)

Text

1 NRR-PMDAPEm Resource From: Miller, Ed Sent: Monday, July 07, 2014 2:30 PM To: 'lawrence.rudy@duke-energy.com'

Subject:

Draft RAI for Catawba RR 14-CN-001 Attachments:

DRAFT Catawba 1-2 RR 14-CN-001 RAI.docxLarry, The NRC staff's draft RAI for the subject relief request is atta ched to this e-mail. The draft RAI is not an official NRC staff request and is being provided to you to facilitate a subsequent conference call to determine: 1) If the questions clearly convey the NRC staff information needs; 2) Whether the regulatory basis for the questions is understood; 3) Whether the information is already available in existing, docketed, correspondence; and 4) To determine an appropriate response time-frame. After you've had a chance to review the draft information request, please contact me to schedule the conference call.

Ed Miller

(301) 415-2481

Hearing Identifier: NRR_PMDA Email Number: 1413 Mail Envelope Properties (9C2386A0C0BC584684916F7A0482B6CAFD30068935)

Subject:

Draft RAI for Catawba RR 14-CN-001 Sent Date: 7/7/2014 2:29:42 PM Received Date: 7/7/2014 2:29:00 PM From: Miller, Ed Created By: Ed.Miller@nrc.gov Recipients: "'lawrence.rudy@duke-energy.com'" <lawrence.rudy@duke-energy.com> Tracking Status: None

Post Office: HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 672 7/7/2014 2:29:00 PM DRAFT Catawba 1-2 RR 14-CN-001 RAI.docx 35125 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: Recipients Received:

ENCLOSURE DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING CATAWBA NUCLEAR STATION, UNITS 1 AND 2 RELIEF REQUEST SERIAL NUMBER 14-CN-001 LIMITED VOLUMETRIC EXAMINATION OF CLASS 1 WELDS 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 (Duke) submitted relief request 14-CN-001. Pursuant to 10 CFR 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.

RAI 1 The NRC compared the volumetric examinati on coverage amounts obtained during the third 10-year inservice inspection (ISI) 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 ISI interval examinat ions. The NRC noted significant differences in the coverage amounts for the CNS Units 1 and 2 pressurizer surge nozzle to head welds, as summarized in Table 1.

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.

Table 1. Pressurizer Surge Nozzle to Head Weld Examination Coverage Amounts CNS Unit Weld 3 rd ISI Interval Coverage and Scan Angles (1) 2 n d ISI Interval Coverage and Scan Angles [Date of Exam, Source]Change in Coverage 1 1-PZR-W1 81.4 %

Scan angles used: 35°, 45°, 60° 77.2 % [2005, September 8, 2005 Relief Request (ML052590564)]

Scan angles used: 35°, 45° + 4.2 % 2 2-PZR-W1 81.2 %

Scan angles used: 35°, 45°, 60° 42.8 % [2001, December 20, 2001 Relief Request (ML0203300121)]

Scan angles used: 60°, 70° + 38.4 % Note: (1) Source: Relief Request 14-CN-001 (ML14052A387).