CNS-14-133, Relief Request Serial Number 14-CN-003, Relief Request to Use Alternative Depth Sizing Criteria

Relief Request Serial Number 14-CN-003, Relief Request to Use Alternative Depth Sizing Criteria

ML14352A261
Person / Time
Site:	Catawba
Issue date:	12/17/2014
From:	Henderson K Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CNS-14-133
Download: ML14352A261 (7)

Text

Kelvin Henderson DUKE Vice President Catawba Nuclear Station

ENERGY, Duke Energy CNO1VP 1 4800 Concord Road York, SC 29745 o: 803.701.4251 f: 803.701.3221 CNS-1 4-133 December 17, 2014 10 CFR 50.55a U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Duke Energy Carolinas, LLC (Duke Energy)

Catawba Nuclear Station, Unit 1 Docket Number 50-413 Relief Request Serial Number 14-CN-003, Relief Request to Use Alternative Depth Sizing Criteria Pursuant to 10 CFR 50.55a(g)(5)(iii), Duke Energy hereby submits Relief Request 14-CN-003 requesting approval to use an alternative depth sizing qualification for Catawba Unit 1 reactor vessel hot leg and cold leg nozzle-to-safe end welds. The basis for the proposed relief request is provided in the enclosure to this letter.

Duke Energy requests NRC approval of this relief request at your earliest possible convenience.

There are no regulatory commitments contained in this relief request submittal.

If you have any questions or require additional information, please contact L.J. Rudy at (803) 701-3084.

Very truly yours, Kelvin Henderson Vice President, Catawba Nuclear Station LJR/s Enclosure www.duke-energy.com

U.S. Nuclear Regulatory Commission December 17, 2014 Page 2 xc (with enclosure):

V.M. McCree Regional Administrator U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 G.A. Hutto, III NRC Senior Resident Inspector Catawba Nuclear Station G.E. Miller (addressee only)

NRC Project Manager (Catawba)

U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 8 G9A 11555 Rockville Pike Rockville, MD 20852-2738

Enclosure Duke Energy Carolinas, LLC Catawba Nuclear Station, Unit 1 Relief Request Serial No. 14-CN-003 Relief Request for Alternative Depth Sizing Criteria, Submitted Pursuant to 10 CFR 50.55a(g)(5)(iii)

Relief Request 14-CN-003 Page 2 of 5

1.0 ASME Code Components Affected

Class 1 Reactor Coolant System (NC) Reactor Vessel Hot Leg Nozzle-to-Safe End and Cold Leg Nozzle-to-Safe End Dissimilar Metal Welds Listed in Table 1 Below.

Table 1 Inspection Plan Nozzle-to-Safe Summary ASME Section XI Description Size End Weld No. Number Item No.

Hot Leg Nozzle 1A to Safe End Weld 29.0" ID (Nom.) 1RPV-W1 5-SE C1.B5.10.0005 B5.10 Hot Leg Nozzle 1B to Safe End Weld 29.0" ID (Nom.) 1RPV-W16-SE C1..B5.10.0006 B5.10 Hot Leg Nozzle 1C to Safe End Weld 29.0" ID (Nom.) 1RPV-W17-SE C1..B5.10.0007 B5.10 Hot Leg Nozzle 1D to Safe End Weld 29.0" ID (Nom.) 1RPV-W18-SE C1.B5.10.0008 B5.10 Cold Leg Nozzle 1A to Safe End Weld 27.5" ID (Nom.) 1RPV-W1l-SE C1.B5.10.0001 B5.10 Cold Leg Nozzle 1B to Safe End Weld 27.5" ID (Nom.) 1RPV-W12-SE C1..B5.10.0002 B5.10 Cold Leg Nozzle 1C to Safe End Weld 27.5" ID (Nom.) 1RPV-W1 3-SE C1..B5.10.0003 B5.10 Cold Leg Nozzle 1D to Safe End Weld 27.5" ID (Nom.) 1RPV-W14-SE C1..B5.10.0004 B5.10 Component materials and nozzle weld configurations are shown in Figure 1.

F- Nozzle Safe End (SS)

N/ozzle (SA-508, Type Class 2)

/ SA-351, CF8A Pipe Figure 1 L Nozzle Cladding (SS)

Hot Leg and Cold Leg Nozzle-to-Safe End Welds (Not to Scale)

I I .

Relief Request 14-CN-003 Page 3 of 5

2.0 Applicable Code Edition and Addenda

2.1 ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through the 2000 Addenda.

2.2 The 3rd Inservice Inspection Interval Program for Unit 1 includes ASME Code Case N-695, Qualification Requirements for Dissimilar Metal Piping Welds, Section Xl, Division 1, which has been approved for use in Regulatory Guide 1.147, Rev.

17, Table 1- "Acceptable Section XI Code Cases".

3.0 Applicable Code Requirements 3.1 IWA-2232 requires that ultrasonic examinations be conducted in accordance with Mandatory Appendix I. Appendix 1,1-2220 requires that ultrasonic examinations be qualified by performance demonstration in accordance with Mandatory Appendix VIII. Appendix VIII, Supplement 10, "Qualification Requirements For Dissimilar Metal Piping Welds", Paragraph 3.2(b) requires that "Examination procedures, equipment, and personnel are qualified for depth sizing when the RMS error of the flaw depth measurements, as compared to the true flaw depths, is less than or equal to 0.125 in. (3.2 mm)."

Note that volumetric examinations of the Reactor Vessel nozzle-to-safe end dissimilar metal welds are also required to be performed in accordance with Section XI, Appendix VIII, as required by 10 CFR 50.55a(b)(2)(xv) and 10 CFR 50.55a(b)(2)(xvi).

3.2 Code Case N-695 provides alternatives to the requirements of Appendix VIII, Supplement 10, but paragraph 3.3(c) of this case requires that "Examination procedures, equipment, and personnel are qualified for depth-sizing when the RMS error of the flaw depth measurements, as compared to the true flaw depths, do not exceed 0.125 in. (3 mm)." Code Case N-695 has been accepted by the NRC without condition and is listed in Table 1 of Regulatory Guide 1.147, Rev. 17.

4.0 Impracticality of Compliance 4.1 Since 2002, the nuclear power industry has attempted to qualify personnel and procedures for depth-sizing examinations performed from the inside surface of dissimilar metal and austenitic stainless steel butt welds in PWR piping. As of October 07, 2014, no domestic or international vendor has met the applicable root mean square (RMS) error requirement of ASME Section XI Appendix VIII, Supplement 10, or the alternative qualification requirements of ASME Code Case N-695, as applicable.

4.2 Vendors that Duke Energy is using for performing these examinations have demonstrated an RMS of no less than 0.189 inch.

5.0 Proposed Alternative and Basis for Use Duke Energy proposes to use the following alternative for flaw depth sizing when dissimilar metal welds are examined from the inside surface:

1. Examinations shall be performed using ultrasonic (UT) techniques that are qualified for flaw detection and sizing using procedures, personnel and equipment qualified by demonstration in all aspects except depth sizing.

Relief Request 14-CN-003 Page 4 of 5

2. A correction factor of the RMS Error - 0.125 inches shall be added to the depths of any measured flaws. The correction factor shall be applied to the most critical location on the flaw in relation to surface proximity.

3. Eddy Current (ET) examinations shall be used to confirm whether any detected flaws are surface-breaking.

4. If any inner diameter (ID) surface-breaking flaws are detected and measured as 50%

through-wall depth or greater, Duke Energy shall repair the indications or shall perform flaw evaluations and shall submit the evaluations to the NRC for review and approval prior to reactor startup.

These flaw evaluations shall include the following:

a. Information concerning the mechanism which caused the flaw.

b. Information concerning the surface roughness/profile in the area of the pipe/weld required to perform the examination, and an estimate of the percentage of potential surface areas with UT probe "lift-off".

All other ASME Code,Section XI requirements for which relief was not specifically requested apply, including the third party review by the Authorized Nuclear Inservice Inspector.

Because compliance with the applicable requirements is impractical, this request is submitted pursuant to 10 CFR 50.55a(g)(5)(iii). Duke Energy believes that the proposed alternative provides reasonable assurance that flaws detected during examination will be sufficiently sized to disposition in accordance with acceptance standards of the ASME Code,Section XI.

6.0 Duration of Proposed Alternative The proposed alternative to the ASME Code is applicable for the third 10-year Inservice Inspection (ISI) Interval at Catawba Nuclear Station, Unit 1, which began on June 29, 2005 and is currently scheduled to end on June 29, 2016.

7.0 Related Industry Relief Requests 7.1 NRC approval of Catawba Nuclear Station, Unit 2 Relief Request 13-CN-001 (ADAMS Accession No. ML13176A400) dated July 8, 2013.

7.2 NRC approval of McGuire Nuclear Station, Unit 2 Relief Request 12-MN-003 (ADAMS Accession No. ML12258A363) dated September 24, 2012.

7.3 NRC approval of McGuire Nuclear Station, Unit 1 Relief Request 13-MN-001 (ADAMS Accession No. ML13086A508) dated March 28, 2013.

8.0 References 8.1 1998 Edition through 2000 Addenda, ASME Code, Section Xl, "Rules for Inservice Inspection of Nuclear Power Plant Components."

8.2 1998 Edition through 2000 Addenda, ASME Code,Section XI, Appendix VIII, Supplement 10.

8.3 ASME Code Case N-695, Qualification Requirements for Dissimilar Metal Piping Welds,Section XI, Division 1.

Relief Request 14-CN-003 Page 5 of 5 8.4 EPRI Materials Reliability Program: Technical Basis for Change to American Society of Mechanical Engineers (ASME)Section XI Appendix VIII Root- Mean-Square Error Requirement for Qualification of Depth-Sizing for Ultrasonic Testing (UT) Performed from the Inner Diameter (ID) of Large-Diameter Thick-Wall Supplement 2, 10, and 14 Piping Welds (MRP-373).

8.5 EPRI Materials Reliability Program Letter MRP 2012-046, dated November 26, 2012,

Subject:

Assessment of Effect of the Depth-Sizing Uncertainty for Ultrasonic Examinations from ID Surface of Large-Bore Alloy 82/182 and Austenitic Stainless Steel Butt Welds in PWR Primary System Piping, Revision 1.