ML13140A005

NRR E-mail Capture - Request for Additional Information for Relief Request No. 5, Examination of Cold Leg Dissimilar Metal Welds, at St. Lucie Unit 1 (TAC No. MF-0675)

ML13140A005
Person / Time
Site:	Saint Lucie
Issue date:	05/16/2013
From:	Farideh Saba Division of Operating Reactor Licensing
To:	Frehafer K Florida Power & Light Co
References
TAC MF0675
Download: ML13140A005 (7)

Text

NRR-PMDAPEm Resource From: Saba, Farideh Sent: Thursday, May 16, 2013 5:28 PM To: ken.frehafer@fpl.com; eric.katzman@fpl.com Cc: Rodriguez, Rafael; Lingam, Siva

Subject:

Request for Additional Information for Relief Request No. 5, "Examination of Cold Leg Dissimilar Metal Welds," at St. Lucie Unit 1 (TAC NO. MF-0675)

Attachments: MF0675_SL 1_ RAI for RR-5 Examination of cold leg dissimilar metal.docx Importance: High

Ken, By letter dated February 4, 2013, (Agencywide Documents and Access Management System (ADAMS) Accession No. ML13046A101), Florida Power & Light Company submitted Relief Request No. 5 to the U.S. Nuclear Regulatory Commission (NRC) regarding examination of cold leg dissimilar metal welds at St. Lucie Plant Unit No 1. Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(A)(3)(ii), the licensee requested a relief from the requirements in 10 CFR 50.55a(g)(6)(ii)(F)(4) that imposes a condition on the American Society of Mechanical Engineers Code Case N-770-1, that essentially 100 percent coverage be achieved for the baseline required volumetric examinations of dissimilar metal welds at reactor coolant pump nozzles. The NRC staff is reviewing your submittal and has determined that additional information is needed to complete its safety review. The NRC staffs request for additional information (RAI) is attached to this email. It is requested that your RAI response be provided within 30 days of the date of this e-mail.

Thanks Farideh E. Saba, P.E.

Senior Project Manager NRC/ADRO/NRR/DORL 301-415-1447 Mail Stop O-8G9A Farideh.Saba@NRC.GOV 1

Hearing Identifier: NRR_PMDA Email Number: 700 Mail Envelope Properties (Farideh.Saba@nrc.gov20130516172700)

Subject:

Request for Additional Information for Relief Request No. 5, "Examination of Cold Leg Dissimilar Metal Welds," at St. Lucie Unit 1 (TAC NO. MF-0675)

Sent Date: 5/16/2013 5:27:31 PM Received Date: 5/16/2013 5:27:00 PM From: Saba, Farideh Created By: Farideh.Saba@nrc.gov Recipients:

"Rodriguez, Rafael" <Rafael.Rodriguez@nrc.gov>

Tracking Status: None "Lingam, Siva" <Siva.Lingam@nrc.gov>

Tracking Status: None "ken.frehafer@fpl.com" <ken.frehafer@fpl.com>

Tracking Status: None "eric.katzman@fpl.com" <eric.katzman@fpl.com>

Tracking Status: None Post Office:

Files Size Date & Time MESSAGE 1258 5/16/2013 5:27:00 PM MF0675_SL 1_ RAI for RR-5 Examination of cold leg dissimilar metal.docx 584416 Options Priority: High Return Notification: No Reply Requested: Yes Sensitivity: Normal Expiration Date:

Recipients Received:

REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUEST NUMBER 5 EXAMINATION OF COLD LEG DISSIMILAR METAL WELDS ST LUCIE PLANT, UNIT 1 FLORIDA POWER & LIGHT COMPANY DOCKET NUMBER 50-335 By letter dated February 4, 2013 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML13046A101), Florida Power & Light Company (the licensee) requested relief from Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(6)(ii)(F)(4) which imposes a condition on American Society of Mechanical Engineers (ASME) Code Case N-770-1 requiring essentially 100 percent coverage be achieved for the baseline volumetric examinations of dissimilar metal welds (DMW) at reactor coolant pump (RCP) nozzles at St Lucie Unit 1. The licensee proposed an alternative to the required examination coverage for the subject welds as documented in Relief Request Number 5 (RR-5), Revision 0.

To complete its review, the Nuclear Regulatory Commission (NRC) staff requests the licensee to response to the following request additional information (RAI).

RAI-1

On Page 8, first paragraph. the licensee discussed the reactor coolant system (RCS) leakage detection capability at St Lucie Unit 1. Describe the RCS leakage detection systems in detail.

Discuss whether the leakage detection systems satisfy the redundancy, sensitivity and reliability specifications of Regulatory Guide 1.45, Revision 1. Discuss leak rates or trends that would cause actions to be taken to determine the location of leaks.

RAI-2

A. Confirm that Performance Demonstration Initiative (PDI) procedure, EPRI-DMW-PA-1, Revision 1 was used for the examination performed in 2010.

B. Discuss whether the PDI procedure is qualified for the ASME Code,Section XI, Appendix VIII, Supplement 10, single sided axial examination of 100 percent of the susceptible material (i.e., DMW).

C. Identify any specific limitations associated with the scope of the PDI procedure.

D. Confirm that all aspects of the subject weld examinations have been through blind qualification in accordance with the ASME Code,Section XI, Appendix VIII requirements. This includes probes and ultrasonic instrumentation, procedure variables, and personnel.

E. Describe the manner in which these examinations have been performed, such as by a single examiner or by team scanning.

RAI-3

A. Provide a flaw growth analysis showing the time necessary for the largest potential semicircular (thumbnail) inside diameter-connected axial and circumferential flaw contained in the unexamined region of the susceptible weld material to grow by primary water storage tank (PWSCC) to exceed the allowable size (i.e., 75 percent through wall) in the ASME Code,Section XI, IWB-3600, and 100 percent through-wall. The flaw growth analysis should model the worst-case weld(s) (e.g., RC-121-6-504 and RC-124-7-504) that has the largest unexamined region.

B. Provide the criteria for determining how far the PWSCC flaw must extend into the examined region before it can first be detected using the ultrasonic test (UT) technique employed.

RAI-4

In order for the NRC staff to verify the above flaw analysis, provide the following items A. A scaled drawing coverage map of the axial cross section of the weld showing the unexamined region of the susceptible material and the dimensions of the largest potential undetected circumferential and axial PWSCC flaw (idealized/elliptical in shape) that can exist, along with its position when it can be detected.

B. The weld residual stress profile used and whether the effect of the safe end stainless steel weld is included in the stress profile.

C. Data on the weld operating temperature and internal pressure.

D. (Data on the pipe diameter and wall thickness, and safe end length.

E. (e) A description of the weld process, including any post-weld machining (e.g., back chipping and re-welding on the inside diameter), and information on any known weld repairs.

RAI-5

The NRC staff requests the following information for a computer modeling, which is used by the NRC staff, to evaluate the examination coverage achieved at St. Lucie Unit 1:

A. As-built weld geometry (1) Provide scaled and dimensional drawings of the subject welds including the immediate region around the weld location so that the NRC staff can create accurate computer models of the weld and surrounding geometry.

(2) Provide depth of geometrical anomalies (e.g., concavity or waviness) on the outside diameter (OD) surface of the welds that impact volumetric inspection.

B. Phased array probe used (1) Discuss center frequency, bandwidth, pulse excitation type and duration.

(2) Operating mode; (a) Transmit-receive (TR), pulse/echo, etc., and (b) Longitudinal (L) and/or shear(S) wave.

(3) Array configuration (matrix): (a) Whether identical or different transmit-receive arrays, if used, (b) Physical separation between arrays (if TRL/TRS configuration). Identify distance between first element of one array and first element of second array (array separation - see Figure 1 below), and (c) If TRL or TRS mode is used, identify transmit and receive arrays (relative to weld geometry).

(4) Total number of elements per array: (a) Number of elements along the primary axis, and (b) Number of elements along the secondary axis.

(5) Element dimensions along primary and secondary axes, spacing between elements, and center-to-center distance (pitch - see Figure 2 below), and element shape if not rectangular.

(6) Element wiring configuration and element firing/receiving ordering sequence for each array.

(7) Probe manufacturer and/or part number.

C. Wedge Used (see Figure 3 below)

(1) Material type - Rexolite, other, etc. (a) Longitudinal and shear wave velocity. (b)

Attenuation (if known) and (c) Density (if known).

(2) Wedge Geometry: (a) Wedge angle, (b) Roof angle (if used), (c) All physical dimensions necessary to create a 3-Dimensional solid model, such as height at front of wedge, height at back of wedge, width of wedge, and length of wedge.

(d) Placement of each probe on each wedge (i.e., what is the height of the middle of the first element?), and (e) Is wedge contact geometry contoured to the specimen? If not, what contour does it have, if any?

D. Beam focusing (See Figure 4 below)

(1) Discuss the type of focusing used, including associated details. The four types of focusing techniques are listed below and shown graphically in Figure 4 below.

(a) Projection - focusing in a specific vertical plane. Parameters: distance from probe reference point, sweep angles (start, stop, interval), skew angle(s),

(b) True depth - focusing at specific constant depth with all angles focused at this depth. Parameters: focusing depth, sweep angles (start, stop, interval),

skew angle(s),

(c) Half-path - sound path held constant as beam is swept. Parameters: sound path length, sweep angles (start, stop, interval), skew angle(s),

(d) Focal plane - arbitrary user-defined plane of focus. Low angle path length, high angle path length, sweep angles (start, stop, interval), skew angle(s).

(2) Number and configuration of elements used in data acquisition (active aperture),

if different than total number of elements within each probe (e.g., if a linear array probe physically contains 64 elements but only the first 32 were active - this needs to be defined).

(3) Provide a set of transmit and receive delay law values for each element at a particular angle and focus to validate model.

Figure 1 Top View of 2D Matrix Array Depicting Separation Dimension Figure 2 Top View of 2D Matrix Array Depicting Primary and Secondary Axis Pitch Dimensions

Figure 3 Definition of Wedge Angle Figure 4 Beam Focusing Options for Phased Array Probes