ML072760048

Relief Request (12R-49), Regarding Inservice Inspection Program Alternative Method (TAC Nos. MD5996 and MD5997)

ML072760048
Person / Time
Site:	Braidwood
Issue date:	11/08/2007
From:	Gibbs R A NRC/NRR/ADRO/DORL/LPLIII-2
To:	Pardee C G Exelon Generation Co
Thorpe-Kavanaugh, Meghan, NRR 415-5735
References
TAC MD5996, TAC MD5997
Download: ML072760048 (8)

Text

Mr. Charles G. Pardee November 8, 2007 Senior Vice President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BRAIDWOOD STATION, UNITS 1 AND 2 - RELIEF REQUEST (I2R-49) REGARDING INSERVICE INSPECTION PROGRAM ALTERNATIVE METHOD (TAC NOS. MD5996 AND MD5997)

Dear Mr. Pardee:

By letter dated July 10, 2007 (Agencywide Document Access And Management System Accession No. ML071910315), the Exelon Generation Company, LLC, (the licensee) submitted Relief Request (I2R-49) proposing an alternative to the requirements of Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.55a, concerning certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for certain inservice inspection (ISI) programs at Braidwood Station (Braidwood), Units 1 & 2.

Specifically, the licensee proposed using ASME Code Case N-696, "Qualification Requirements for Appendix VIII Piping Examination Conducted from the Inside Surface," and a root mean square (RMS) error criterion for flaw sizing that is greater than the ASME Code,Section XI, Appendix VIII, Supplement 10, "Qualification Requirements for Dissimilar Metal Piping Welds," Paragraph 3.2(b); ASME Code Case N-695, "Qualification Requirements for Dissimilar Metal Piping Welds," Paragraph 3.3(c); and Code Case N-696, Paragraph 3.3(d) acceptance criterion for examinations performed from the inside surface of pressure boundary piping. ASME Code Case N-695 is an alternative to Appendix VIII, Supplement 2, "Qualification Requirements for Wrought Austenitic Piping Welds," which is referenced in Regulatory Guide (RG) 1.147, "Inservice Inspection Code Case Acceptability, ASME Code,Section XI, Division 1." The request is for the second 10-year inservice inspection (ISI) interval which is scheduled to end July 28, 2008, for Unit 1 and October 16, 2008, for Unit 2.

Based on the enclosed review, the NRC staff concludes that ASME Code Case N-696 (qualifying personnel and procedures for examinations performed from the pipe ID on dissimilar metal welds) provides an acceptable level of quality and safety, and therefore, is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the remainder of the second 10-year ISI interval at Braidwood Station.

In addition, the NRC staff concludes that compliance with the ASME Code-required 0.125-inch RMS depth sizing error is impractical, and that the proposed alternative for a coordinated Supplement 2 and Supplement 10 (Code Case N-696) provides reasonable assurance of structural integrity, and therefore, pursuant to 10 CFR 50.55a(g)(6)(i), relief is granted for Braidwood Station, for the second 10-year ISI interval.

The NRC staff's safety evaluation is enclosed.

Sincerely,

/RA/ Russell A. Gibbs, Branch Chief Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Docket Nos. STN 50-456 and STN 50-457

Enclosure:

Safety Evaluation

cc w/encl: See next page C. Pardee In addition, the NRC staff concludes that compliance with the ASME Code-required 0.125-inch RMS depth sizing error is impractical, and that the proposed alternative for a coordinated Supplement 2 and Supplement 10 (Code Case N-696) provides reasonable assurance of structural integrity, and therefore, pursuant to 10 CFR 50.55a(g)(6)(i), relief is granted for Braidwood Station, for the second 10-year ISI interval.

The NRC staff's safety evaluation is enclosed.

Sincerely,

/RA/ Russell A. Gibbs, Branch Chief Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

Docket Nos. STN 50-456 and STN 50-457

Enclosure:

Safety Evaluation

cc w/encl: See next page

DISTRIBUTION

PUBLIC RidsRgn3MailCenter LPL3-2 R/F RidsNrrDorlLpl3-2 RidsOgcRp TBloomer, EDO, Region III RidsNrrLAEWhitt RidsAcrsAcnwMailCenter Don Naujock, DCI/CPNB RidsNrrPMMThorpe-Kavanaugh

Adams accession no.: ML072760048 *See memo ML072690252 OFFICE LPL3-2/PM LPL3-2/LA DC/CPNB/BC OGC LPL3-2/BC NAME MThorpe-Kavanaugh EWhitt TChan* MSmith RGibbs DATE 10/26/07 10/26/07 9 / 25 /07 10/15/07 11/8/07 OFFICIAL RECORD COPY

Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION

RELATED TO RELIEF REQUEST I2R-49 EXELON GENERATION COMPANY, LLC BRAIDWOOD STATION, UNITS 1 AND 2 SECOND 10-YEAR INSERVICE INSPECTION INTERVAL

DOCKET NOS. STN 50-456 AND STN 50-457

1.0 INTRODUCTION

By letter to the Nuclear Regulatory Commission (NRC) dated July 10, 2007 (Agencywide Document Access And Management System (ADAMS) Accession No. ML071910315), the Exelon Generation Company, LLC, (the licensee) submitted a relief request (I2R-49) proposing an alternative to certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) at the Braidwood Station (Braidwood), Units 1 & 2.

Specifically, the licensee proposed using ASME Code Case N-696, "Qualification Requirements for Appendix VIII Piping Examination Conducted from the Inside Surface," and a root mean square (RMS) error criterion for flaw sizing that is greater than the ASME Code,Section XI, Appendix VIII, Supplement 10, "Qualification Requirements for Dissimilar Metal Piping Welds," Paragraph 3.2(b); ASME Code Case N-695, "Qualification Requirements for Dissimilar Metal Piping Welds," Paragraph 3.3(c); and ASME Code Case N-696, Paragraph 3.3(d) acceptance criterion for examinations performed from the inside surface of pressure boundary piping. ASME

Code Case N-695 is an alternative to Appendix V III, Supplement 2, "Qualif ication R equirements for Wrought Austenitic Piping Welds," which is referenced in Regulatory Guide (RG) 1.147, "Inservice Inspection Code Case Acceptability, ASME Code Section XI, Division 1." The request is for the second 10-year inservice inspection (ISI) interval which is scheduled to end July 28, 2008, for Unit 1 and October 16, 2008, for Unit 2.

2.0 REGULATORY EVALUATION

In accordance with Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.55a(g)(4), ASME Code Class 1, 2, and 3 components must meet the requirements set forth in ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plants Components,"

to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that all inservice examinations and system pressure tests conducted during the first 10-year interval, and subsequent intervals, comply with the requirements in the latest edition and addenda of ASME Code,Section XI, incorporated by reference in 10 CFR 50.55a(b) on the date 12 months prior to the start of the 10-year interval.

For Braidwood, the Code of Record for Units 1 and 2 second 10-year ISI interval is the 1989 Edition of Section XI of the ASME Code.

Alternatives to requirements may be authorized or relief granted by the NRC pursuant to 10 CFR 50.55a(a)(3)(i), 10 CFR 50.55a(a)(3)(ii), or 10 CFR 50.55a(g)(6)(i). In proposing alternatives or request for relief, the licensee must demonstrate that: (1) the proposed alternatives provide an acceptable level of quality and safety; (2) compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety; or (3) conformance is impractical for the facility. Pursuant to 10 CFR 50.55a(g)(4)(iv), ISI items may meet the requirements set forth in subsequent editions and addenda of the ASME Code that are incorporated by reference in 10 CFR 50.55a(b), subject to the limitations and modifications listed therein, and subject to Commission approval. Portions of editions and addenda may be used provided that related requirements of the respective editions and addenda are met.

3.0 TECHNICAL EVALUATION

FOR REQUEST I2R-49

3.1 Affected

Components

The request is specific to pipe welds.

3.2 Applicable

Code

For Units 1 and 2, second 10-year ISI interval, the ISI Code of record for ultrasonic testing (UT) examinations is the 1995 Edition with 1996 Addenda of the ASME Code,Section XI, Appendix

VIII, Supplement 2 and Supplement 10, Paragraph 3.2(b) (for both supplements) whic h states that the RMS error for flaw depths estimated by UT shall not exceed 0.125-inch.

3.3 Proposed

Alternative

The licensee proposed using the Electric Power Research Institute (EPRI) - Performance Demonstration Initiative (PDI) program for the im plementation of Appendix VIII, Supplement 10, Paragraph 3.2(b), 0.189-inch RMS error in lieu of the ASME Code-required 0.125-inch RMS criterion.

The licensee proposed using Code Case N-696, Paragraph 3.3(d), with a 0.245-inch RMS criterion in lieu of the required 0.125-inch RMS error.

The difference between 0.189-inch (Supplement 10) and the ASME Code-required 0.125-inch RMS error and the difference between 0.245-inch (Supplement 2) and ASME Code-required 0.125-inch RMS error will be added to the UT measured flaw depth for the purpose of flaw evaluation.

3.4 Licensee

Basis for the Alternative

The licensee is performing volumetric examinations of all nozzle-to-safe end welds, dissimilar metal (DM) welds, and a select number of adjacent safe end-to-pipe or safe end-to-elbow welds from the inside diameter (ID) surface during the second ten-year ISI inspection interval. If only the DM weld is examined, the licensee will use the NRC approved Code Case N-695 for qualification requirements. However, for a DM weld and an adjacent austenitic similar metal weld examination, the licensee proposed using Code Case N-696 which is a coordinated Supplement 2 and Supplement 10 qualification.

The licensee also proposes using an alternative RMS error depth-sizing requirement as compared to the 0.125-inch RMS error value stated in Supplement 10, Code Case N-695, and Code Case N-696. The licensee contracted the Electric Power Research Institute (EPRI)

Nondestructive Examination (NDE) Center on June 15, 2007 and confirmed that no vendor has successfully demonstrated compliance with the ASME Code required 0.125-inch RMS error for qualification tests performed from the ID surface (for either stand alone Supplement 10 or coordinated Supplement 2 and 10 qualifications).

The licensee has verified through the EPRI-NDE Center that the vendor selected to perform the UT examinations at Braidwood has achieved a 0.245-inch RMS error for the Coordinated Supplements 2 and 10 qualification (as addressed in Code Case N-656) and 0.189-inch RMS error (as addressed in Code Case N-695) for the stand alone Supplement 10 qualification.

3.5 Evaluation

The licensee's ISI Code of record for Units 1 and 2 second 10-year ISI interval is the 1989 Edition with no addenda. 10 CFR 50.55a(g)(6)(ii)(C)(2) require licensees using the 1989 Edition or earlier editions and addenda ISI Code of record to use the 1995 Edition with 1996 Addenda of the ASME Code,Section XI, Appendix VIII to qualify personnel and procedures for UT examinations. The licensee's vendor performed a Supplement 10 (Code Case N-695) and a coordinated Supplement 2 and Supplement 10 (Code Case N-696) performance demonstration as implemented by the EPRI-PDI program. The licensee is requesting to use Code Case N-696 with an 0.245-inch RMS error in lieu of the 0.125-inch RMS error in Paragraph 3.3(d). Code Case N-696 is in the process of being reviewed for endorsement in RG 1.147.

The NRC staff participated in the development of Code Case N-696 in the ASME Code consensus building process. The NRC issued Draft RG Guide (DG) DG-1134, "Proposed Revision 15 of Regulatory Guide 1.147," dated October 2006 which referenced Code Case N-696 as acceptable without conditions.

The ASME Code requires that the maximum error for flaw depth measurements, when compared to the true flaw depth, must not exceed 0.125-inch RMS error. The nuclear power industry has been trying to qualify personnel and procedures for examinations performed from the inside pipe diameter of austenitic similar metal (Supplement 2/Code Case N-695) and dissimilar metal welds (Supplement 10/Code Case N-696) since November 2002. However, to date, no personnel or procedure has achieved the ASME Code-required maximum RMS error.

The difficulties are associated with the surface roughness of the field welds. As licensees perform ID UT examinations, they are taking profilometry measurements which can be used to assess the representativeness of the test specimens used to establish the vendors RMS error criterion. At this time, achieving a 0.125-inch maximum RMS error criterion is impractical.

The licensee has stated that the vendor has achieved an 0.189-inch RMS in their Supplement 10 (Code Case N-695) performance demonstration and an 0.245-inch RMS error in their coordinated Supplement 2 and Supplement 10 (Code Case N-696) performance demonstration.

The licensee proposed adding the depth sizing difference between their demonstrated 0.189-inch RMS error and the ASME Code-required 0.125-inch RMS error to the measured flaw value of any flaws in an austenitic similar metal weld, and the difference between the demonstrated 0.245-inch RMS error and the ASME Code-required 0.125-inch RMS error to the measured flaw value of any flaws in dissimilar metal welds.

The NRC staff finds that compliance with the ASME Code-required RMS error criterion is impractical at this time and that adding the difference between the performance demonstrated depth sizing RMS error and the ASME Code-required depth sizing RMS error to the measured flaw value for determining acceptability according to the standards specified in ASME Section XI, IWB-3500, provides reasonable assurance of structural integrity.

4.0 CONCLUSION

Based on the above review, the NRC staff concludes that Code Case N-696 (qualifying personnel and procedures for examinations performed from the pipe ID on dissimilar metal welds) provides an acceptable level of quality and safety, and therefore, is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the remainder of the second 10-year ISI interval at Braidwood, Units 1 and 2.

Based on the above review, the NRC staff concluded that compliance with the ASME Code-required 0.125-inch RMS depth sizing error is impractical, and that the proposed alternative to use an 0.189-inch RMS error for Supplement 10 (Code Case N-695) and an 0.245-inch RMS error for a coordinated Supplement 2 and Supplement 10 (Code Case N-696) provides reasonable assurance of structural integrity. Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), relief is granted for Braidwood, Units 1 and 2 for the second 10-year ISI interval.

The granting of relief is authorized by law and will not endanger life or property, or the common defense and security and is otherwise in the public interest, given the consideration of the burden upon the licensee.

All other requirements of the ASME Code,Section XI for which relief has not been specifically requested remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.

Principal Contributor: D. Naujock

Date: November 8, 2007

Enclosure Braidwood Station, Units 1 and 2

cc:

Document Control Desk - Licensing via e-mail

Mr. Dwain W. Alexander, Project Manager Westinghouse Electric Corporation via e-mail

Ms. Bridget Little Rorem Appleseed Coordinator via e-mail

Howard A. Learner Environmental Law and Policy Center of the Midwest via e-mail

Braidwood Senior Resident Inspector U.S. Nuclear Regulatory Commission via e-mail

Ms. Lorraine Creek RR 1, Box 182 Manteno, IL 60950

Illinois Emergency Management Agency Division of Disaster Assistance &

Preparedness via e-mail

County Executive via e-mail

Attorney General 500 S. Second Street Springfield, IL 62701

Plant Manager - Braidwood Station via e-mail

Site Vice President - Braidwood via e-mail

Senior Vice President - Operations Support via e-mail

Chairman, Ogle County Board Post Office Box 357 Oregon, IL 61061 Manager Regulatory Assurance - Braidwood via e-mail

Director - Licensing and Regulatory Affairs via e-mail

Associate General Counsel via e-mail

Senior Vice President - Midwest Operations via e-mail

Vice President - Regulatory Affairs via e-mail

Manager Licensing - Braidwood, Byron and LaSalle via e-mail