CP-200800927, (Cpnpp), Relief Request B-8 for Unit 1 Second 10 Year ISI Interval & B-6 for Unit 2 Second 10 Year ISI Interval from 10 CFR 50.55a Requirements for Reactor Vessel Hot & Cold Leg Nozzle Weld Examinations (Unit 1 Second Interval Start..

(Cpnpp), Relief Request B-8 for Unit 1 Second 10 Year ISI Interval & B-6 for Unit 2 Second 10 Year ISI Interval from 10 CFR 50.55a Requirements for Reactor Vessel Hot & Cold Leg Nozzle Weld Examinations (Unit 1 Second Interval Start..

ML082000123
Person / Time
Site:	Comanche Peak
Issue date:	07/10/2008
From:	Blevins M, Madden F Luminant Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CP-200800927, TXX-08097
Download: ML082000123 (6)

Text

Mike Blevins Luminant Power Executive Vice President P 0 Box 1002

& Chief Nuclear Officer 6322 North FM 56 mikeblevins@luminant.com Glen Rose, TX 76043 Luminant T 254 897 5209 C 817 559 9085 F 254 897 6652 CP-200800927 Ref: 10CFR50.55a TXX-08097 July 10, 2008 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT (CPNPP)

DOCKET NOS. 50-445 AND 50-446 RELIEF REQUEST NO. B-8 FOR THE UNIT 1 SECOND 10 YEAR ISI INTERVAL AND B-6 FOR THE UNIT 2 SECOND 10 YEAR ISI INTERVAL FROM 10 CFR 50.55a REQUIREMENTS FOR REACTOR VESSEL HOT AND COLD LEG NOZZLE WELD EXAMINATIONS (UNIT 1 SECOND INTERVAL START DATE: AUGUST 13, 2000; UNIT 2 SECOND INTERVAL START DATE: AUGUST 3,2004)

Dear Sir or Madam:

Pursuant to 10 CFR 50.55a(a)(3)(ii), Luminant Generation Company LLC (Luminant Power) hereby requests NRC approval of the attached relief request B-8 for the second ten-year inservice inspection interval for Unit 1 and B-8 for the second ten-year inservice inspection interval for Unit 2. A Proposed Alternative approval is requested from the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI 1998 Edition through the 2000 Addenda, for an alternative method for examination of the reactor vessel hot and cold leg nozzle welds.

The basis and justification for the relief request are attached. Luminant Power requests approval of this alternative for examination of reactor vessel hot and cold leg nozzle welds scheduled to be performed in upcoming outages for Units 1 and 2. Approval of this relief request is requested by September 30, 2008 for implementation during the fall 2008 refueling outage for Unit 1. The next Unit 2 refueling outage is scheduled for the fall 2009.

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance c)(4 7 Callaway Comanche Peak

• Diablo Canyon

• Palo Verde

• San Onofre South Texas Project Wolf Creek w1k

U. S. Nuclear Regulatory Commission TXX-08097 Page 2 of 2 7/10/2008 This communication contains no new licensing basis commitments regarding CPNPP.

If you have any questions regarding this request, please contact Jack Hicks at (254) 897-6725.

Sincerely, Luminant Generation Company LLC Mike Blevins By: { 272,2/*

/Arred W. Madden Director, Oversight & Regulatory Affairs Attachment JCH c- E. E. Collins, Region IV B. K. Singal, NRR Resident Inspectors, Comanche Peak A. Jones, TDLR Brian Welch ANII, Comanche Peak

U. S. Nuclear Regulatory Commission Attachment to TXX-08097 Page 1 of4 7/10/2008 Luminant Power Comanche Peak Nuclear Power Plant Relief Request B-8 for Unit 1 and B-6 for Unit 2 Proposed Alternative In Accordance With 10 CFR 50.55a(g)(6)(ii)(C)

Implementation of Appendix VIII to Section XI

1. ASME Code Component(s) Affected Class 1 Risk-Informed Inservice Inspection (RI-ISI) Reactor Coolant piping welds as shown:

Code Cat/Item No. Description Weld No.'s (both Units)

R-A, R1.20 (formerly Code Cat B-F, B5.10) 8- Nozzle-to-Safe End Butt Welds 1-4100-1 (29")

1-4100-14 (27.5")

1-4200-1 (29")

1-4200-14 (27.5")

1-4300-1 (29")

1-4300-14 (27.5")

1-4400-1 (29")

1-4400-14 (27.5')

R-A, R1.20 (formerly Code Cat B-J, B9.11) 8- Circumferential Pipe Welds 1-4100-2 (29")

1-4100-13 (27.5")

1-4200-2 (29")

1-4200-13 (27.5")

1-4300-2, (29")

1-4300-13 (27.5")

1-4400-2 (29")

1-4400-13 (27.5')

2. Applicable Code Edition and Addenda The applicable ASME Boiler and Pressure Vessel Code (hereafter referred to as the "Code") edition and addenda is ASME Section XI, "Rule for Inservice Inspection of Nuclear Power Plant Components," 1998 Edition, through 2000 Addenda. In addition, as required by 10CFR5O.55a, ASME Section XI, 1995 Edition, 1996 Addenda through the 2001 Edition is used for Appendix VIII, Performance Demonstration Initiative for Ultrasonic Examination System.

3. Applicable Code Requirements Examination Category R-A, items R1.20 (formerly Code Categories B-F, B5.10 and B-J, B9.11 in the 1998 Edition through 2000 Addenda) specifies volumetric examination. This volumetric examination is to be conducted in accordance with Appendix VIII, Supplements 10 and 2 in the 1995 Edition of Section XI with 1996 Addenda per 10CFR50.55a(g)(6)(ii)(C). Additionally, approved Code Cases N-695 and N-696 as noted in the Comanche Peak Examination Plan are also referenced.

4. Reason for Request Two relief actions are requested by Luminant Power.

a) Relief from the 0.125inches RMSE depth sizing requirement of Appendix VIII, Supplements 10 and 2:

U. S. Nuclear Regulatory Commission Attachment to TXX-08097 Page 2 of 4 07/10/2008 Luminant Power Comanche Peak Nuclear Power Plant Relief Request B-8 for Unit 1 and B-6 for Unit 2 Proposed Alternative In Accordance With 10 CFR 50.55a(g)(6)(ii)(C)

Implementation of Appendix VIII to Section XI To date, although examination vendors have qualified for detection and length sizing on these welds, the examination vendors have not met the established root mean square error (RMSE) of 0.125 inches for depth sizing.

Luminant Power proposes to use a contracted examination vendor that has demonstrated ability to meet a depth sizing qualification requirement with an RMSE of 0.189 inches instead of the 0.125 inches required for Supplement 10, an RMSE of 0.367 inches instead of the 0.125 inches required for Supplement 2, and an RMSE of 0.245 inches instead of the 0.125 inches for Supplements 10 and 2 combined, as per approved Code Case N-696.

b) Relief from using only the) ultrasonic test method when performing examinations of the Code specified pipe weld volumes from the ID surface in the presence or weld root and counter-bore surface conditions:

The examination vendor for the Comanche Peak Nuclear Power Plant reactor vessel nozzle examinations has qualified for detection of circumferential flaws in accordance with Appendix VIII, Supplements 10 and 2, as demonstrated through the Electric Power Research Institute (EPRI)

Performance Demonstration Initiative (PDI) Program, for nozzle-to-safe end and safe end-to-pipe welds examined from the ID surface. The vendor is similarly qualified for detection of axial flaws provided the surface is machined or ground smooth with no exposed root reinforcement or counter-bore. Surface.

roughness may be present that could call into question the ultrasonic qualifications demonstrated for detection of axial flaws.

The examination vendor has developed an eddy current technique to augment the ultrasonic examination method and provide increased sensitivity at the ID surface. The eddy current technique was first used in the VC Summer reactor vessel primary nozzle examinations of 2000. The procedure was refined after its first use in 2000 by applying it to the VC Summer hot leg dissimilar metal weld section removed from service. The removed section had a number of primary water stress corrosion cracking flaws along with non-relevant indications resulting from metallurgical interface and surface geometry. Using these actual flaws and geometric conditions in the removed section to refine the technique, the vendor developed a reliable flaw-screening criteria which allowed for the successful use of the procedure in the VC Summer 2002 and 2003 examinations.

Since that time, the technique has been successfully blind tested for the Swedish authority SQC Kvalificeringscentrum AB (SQC NDT Qualification Center) under the program, "Qualification of Equipment, Procedure and Personnel for Detection, Characterization and Sizing of Defects in Areas in Nozzle to Safe End Welds at Ringhals Unit 3 and 4," Hakan Soderstrand 7-10-03. The important qualification parameters for Eddy Current in the SQC blind tests were as follows:

-Defect types: fatigue and stress corrosion cracks, surface initiated

-Tilt: +/-10 degrees; Skew: +/-10 degrees

-Detection target size: IDSCC 6mm (0125 inches) long

-Flaw Location: within 10mm (13/32 inch)

-Length of the planar flaw within a 70% confidence interval: +/-9mm (3/8 inch)

U. S. Nuclear Regulatory Commission Attachment to TXX-08097 Page 3 of 4 07/1012008 Luminant Power Comanche Peak Nuclear Power Plant Relief Request B-8 for Unit 1 and B-6 for Unit 2 Proposed Alternative In Accordance With 10 CFR 50.55a(g)(6)(ii)(C)

Implementation of Appendix VIII to Section XI

-False call rate: less than or equal to 20% for the personnel qualification tests (Ref. SQC Qualification Report No. 019AN03)

The technique has also been used to supplement examination of portions of the relevant near-surface volumes during the last 15 domestic pressurized water reactor nozzle-to-pipe examinations conducted by the vendor.

5. Proposed Alternative and Basis for Use Luminant Power proposes to use approved Code Case N-695 and N-696 with a combined RMSE of 0.245 inches instead of the 0.125 inches specified for depth sizing in the Code Cases. In the event an indication is detected that requires depth sizing, the 0.120 inch difference between the required RMSE and the demonstrated RMSE (0.245 inches -0.125 inches = 0.120 inches) will be added to the measured through-wall extent for comparison with applicable acceptance criteria. If the examination vendor demonstrates an improved depth sizing RMSE prior to the examination, the excess of that improved RMSE over the 0.125 inch RMSE requirement, if any, will be added to the measured value for

'comparison with applicable acceptance criteria.

The proposed alternative assures that the nozzle-to-safe-end welds and the subject reactor coolant piping circumferential welds will be fully examined by procedures, personnel and equipment qualified by demonstration in all aspects except depth sizing. For depth sizing, the proposed addition of the difference between the qualified and demonstrated sizing tolerance to any flaw required to be sized compensates for the potential variation and provides an acceptable level of quality and safety in accordance with 10CFR50.55a(a)(3)(i).

Use of the combined qualification requirements for Supplements 10 and 2 prior to availability of Code Case N-696, and the concept of adding the difference between the required RMSE value and the demonstrated RMSE value to the measured indication depth, were separately approved for the V.C.

Summer Station by NRC letter dated February 3,'2004 (ML040340450).

Luminant Power also proposes using surface geometry profiling software (profilometry) in conjunction with a focused immersion ultrasonic transducer positioned to permit accurate profile data across the examination volume to help the examiner confirm locations where the raw data indicates lack of transducer contact due to problematic surface geometry. In addition to profilometry, eddy current examination will be used to supplement ultrasonic examination for the nozzle-to-safe end or safe end-to-pipe welds having sufficient surface roughness to call into question the applicability of the ultrasonic examination qualification to detect axial flaws. Profilometry will be used to determine the surface areas, if any, where roughness may limit the ability of ultrasonic methods to be used effectively as qualified through performance demonstration.

The eddy current method will be used in the areas identified by profilometry to assure any axial flaws at the ID surface volume that could be missed by ultrasonic examination due to potential surface

U. S. Nuclear Regulatory Commission Attachment to TXX-08097 Page 4 of 4 07/10/2008 Luminant Power Comanche Peak Nuclear Power Plant Relief Request B-8 for Unit 1 and B-6 for Unit 2 Proposed Alternative In Accordance With 10 CFR 50.55a(g)(6)(ii)(C)

Implementation of Appendix VIII to Section XI roughness are detected. As a compliment to ultrasonic examinations for rough surface detection coverage, the following eddy current techniques will be utilized:

- up to two plus point probes applied circumferentially on the pipe inside surface in scan increments of 0.080 inches circumferentially (for axial flaws) and 0.25 inches axially.

- Automated systems for data collection and analysis The target flaw size for the eddy current procedure is 0.28 inches long, well within the ASME Code linear flaw acceptance standards of 0.45 inches for austenitic material, and 0.625 inches for ferritic material (defined for the outside surface in the Code Tables). All eight nozzle-to-safe end welds and all eight safe end-to-pipe welds will be examined.

The ultrasonic examinations supplemented by eddy current examinations and profilometry will be conducted to the maximum extent practical and are subject to third party review by the Authorized Nuclear Inservice Inspector.

Use of ultrasonic profilometry and eddy current examination with procedures and personnel qualified through the SQC blind tests to supplement Appendix VIII qualified ultrasonic procedures and personnel for the nozzle-to-safe end and safe end-to-pipe welds provides additional assurance that surface-breaking flaws that may be present would be detected in the presence of potential surface roughness, resulting in an equivalent or better level of quality and safety than that currently qualified to meet ASME Code requirements in accordance with 10 CFR 50.55a(a)(3)(i). The proposed alternative was approved for the V.C. Summer Station by NRC letter dated October 16, 2004 (ML042950444).

6. Duration of Proposed Alternative The proposed alternative is for the second ten-year ISI interval for Unit 1 of CPNPP, which began on August 13, 2000, and ends on August 12, 2010 and the second ten-year ISI interval for Unit 2 of CPNPP, which began August 3, 2004 and ends on August 2, 2014. There is no undue risk to the public health and safety, presented by this request.

7. Precedents:

The proposed alternative for the use of the combined qualification requirements for Supplements 10 and 2 prior to availability of Code Case N-696, and the concept of adding the difference between the required RMSE value and the demonstrated RMSE value to the measured indication depth, were separately approved for the V.C. Summer Station by NRC letter dated February 3, 2004 (ML040340450).

The proposed alternative was approved for profilometry and eddy current for the V.C. Summer Station by NRC letter dated October 16, 2004 (ML042950444).