ML043650480

Relief Request to Use Code Case N-661, and Safety Evaluation

ML043650480
Person / Time
Site:	Palisades
Issue date:	01/18/2005
From:	Margie Kotzalas NRC/NRR/DLPM/LPD3
To:	Domonique Malone Nuclear Management Co
Jaffe D, NRR/DLPM, 415-1439
References
RG-1.147, TAC MC3880
Download: ML043650480 (9)

Text

January 18, 2005 Mr. Daniel J. Malone Site Vice President Palisades Nuclear Plant Nuclear Management Company, LLC 27780 Blue Star Memorial Highway Covert, MI 49043-9530

SUBJECT:

PALISADES NUCLEAR POWER PLANT - RELIEF REQUEST TO USE CODE CASE - 661 (TAC NO. MC3880)

Dear Mr. Malone:

By letter dated July 28, 2004, Nuclear Management Company, LLC (the licensee), requested that the U. S. Nuclear Regulatory Commission (NRC) approve an alternative to the requirements of IWA-4120(a) and IWA-4310 of the 1989 Edition of the American Society of Mechanical Engineers (ASME) Code,Section XI. Specifically, the licensee requested that the NRC approve the use of ASME Code Case-661, Alternative Requirements for Wall Thickness Restoration of Class 2 and 3 Carbon Steel Piping for Raw Water Service. Palisades Nuclear Power Plant (PNPP) is committed to the 1989 Edition of Section XI of the ASME Code. The request was made pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50.55a(a)(3)(i) to address replacement or internal weld repair of wall thinning conditions resulting from various wall thinning degradation mechanisms such as erosion, corrosion, cavitation, and pitting in Class 2 and 3 carbon steel raw water piping systems.

Based on the information provided in the licensees submittal, the NRC staff concludes that the licensee has provided an acceptable alternative to the requirements of IWA-4120(a) and IWA-4310 of the 1989 Edition of the ASME Code Section XI, subject to the following three conditions which must be met when using Code Case-661. These conditions are: (a) if the root cause of the degradation has not been determined, the repair is only acceptable for one cycle; (b) weld overlay repair of an area can only be performed once in the same location; and (c) when through-wall repairs are made by welding on surfaces that are wet or exposed to water, the weld overlay repair is only acceptable until the next refueling outage. The NRC staff concludes that the proposed alternative, as supplemented by the three conditions listed above, provides an acceptable level of quality and safety. Therefore, the proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for PNPP for the current 10-year inservice inspection interval, or until Code Case-661 is approved for general use by reference in Regulatory Guide (RG) 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1." After that time, if the licensee wishes to continue to use Code Case-661, the licensee must follow the conditions, if any, specified in the RG 1.147. All other ASME Code,Section XI, requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.

D. Malone A copy of the Safety Evaluation is enclosed.

Sincerely,

/RA/

Margaret Kotzalas, Acting Section Chief, Section 1 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-255

Enclosure:

As stated cc w/encls: See next page

ML043650480 *ML043500369 OFFICE PDIII-1/(A)PM PDIII-1/LA EMCB-B/SC OGC PDIII-1/(A) SC NAME DJaffe THarris TChan* MLemoncelli MKotzalas DATE 01/3/05 01/3/05 12/7/04 01/13/05 1/18/05 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST TO USE CODE CASE - 661 NUCLEAR MANAGEMENT COMPANY, LLC PALISADES NUCLEAR POWER PLANT DOCKET NO. 50-255

1.0 INTRODUCTION

By letter dated July 28, 2004, Nuclear Management Company, LLC (the licensee), requested that the U. S. Nuclear Regulatory Commission (NRC) approve an alternative to the requirements of IWA-4120(a) and IWA-4310 of the 1989 Edition of the American Society of Mechanical Engineers (ASME) Code. Specifically, the licensee requested that the NRC approve the use of ASME Code Case N-661, Alternative Requirements for Wall Thickness Restoration of Class 2 and 3 Carbon Steel Piping for Raw Water Service. Palisades Nuclear Power Plant (PNPP) is committed to the 1989 Edition of Section XI of the ASME Code. The request was made pursuant to Title 10 of the Code of Federal Regulations (10 CFR)

Part 50.55a(a)(3)(i) to address replacement or internal weld repair of wall thinning conditions resulting from various wall thinning degradation mechanisms such as erosion, corrosion, cavitation, and pitting in Class 2 and 3 carbon steel raw water piping systems. The licensee stated the primary reason for the request was to provide adequate time for additional examination of adjacent piping so that pipe replacement can be planned to reduce impact on system availability including Maintenance Rule applicability of replacement materials.

2.0 REGULATORY EVALUATION

Title 10 of the Code of Federal Regulations (10 CFR) Part 50.55a(g) specifies that inservice inspection (ISI) of nuclear power plant components shall be performed in accordance with the requirements of the ASME Boiler and Pressure Vessel Code (Code),Section XI, except where specific written relief has been granted by the NRC pursuant to 10 CFR 50.55a(g)(6)(i). 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. 10 CFR 50.55a(g)(5)(iii) states that if the licensee has determined that conformance with certain code requirements is impractical for its facility, the licensee shall notify the NRC and submit, as specified in Section 50.4, information to support the determinations.

Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the

preservice examination requirements, set forth in the ASME Code,Section XI, Rules for Inservice Inspection (ISI) of Nuclear Power Plant Components, to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that ISI of components 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 Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.

ASME Code Components Affected ASME Section XI, Class 2 and 3 Carbon Steel Piping for Raw Water Services Applicable ASME Code Requirement ASME Section XI, 1989 Edition, no addenda:

IWA-4120(a) requires that the repairs be performed in accordance with the Owners Design Specification and the original Construction Code of the component or system.

IWA-4310 requires that defects be removed or reduced in size in accordance with IWA-4000.

Reason for Request

Relief is requested from replacement or weld repair of wall thinning conditions in Class 2 and 3 carbon steel raw water piping systems to the design specification and the original construction code. The wall thinning conditions may be the result of various degradation mechanisms such as erosion, corrosion, cavitation, and pitting. The licensee stated the primary reason for this relief request is to provide adequate time so that pipe replacement can be planned to reduce impact on system availability including Maintenance Rule applicability of replacement materials.

Proposed Alternative and Basis for Use The licensee will implement the requirements of ASME Code Case-661 as an alternative under 10 CFR 50.55a(a)(3)(i) for Class 2 and 3 raw water piping system repairs resulting from degradation mechanisms such as erosion, corrosion, cavitation, or pitting as an alternative to the requirements of the ASME Section XI code as referenced above. The licensee stated that these types of defects are typically identified by small leaks in the piping system or by pre-emptive non-code required examinations performed to monitor the degradation mechanisms. The alternative repair technique described in Code Case-661 involves the application of additional weld metal on the exterior of the piping system that restores the wall thickness requirement. The licensee stated that the repair technique will be utilized whenever the engineering evaluation determines that such a repair is suitable for the particular defect or degradation being resolved. The licensee stated that provisions for use of this Code Case will be addressed in the Repair/Replacement Program for PNPP.

The licensee stated that the provisions will require that adjacent areas be examined to verify that the repair will encompass the entire flawed area and that no other unacceptable degraded

locations exist within a representative area dependent on the degradation mechanism present.

The licensee will perform an evaluation of the degradation mechanism to determine the re-examination schedule to be performed over the life of the repair. The repair will be considered to have a maximum service life of two fuel cycles unless the re-examinations conducted during each of the two fuel cycles establish the expected life of the repair.

Additionally, the licensee stated the following restrictions will be placed on the use of Code Case N- 661, to ensure that the use of the Code Case will provide an acceptable alternative pursuant to 10 CFR 50.55a(a)(3)(i):

(a) If the root cause of the degradation has not been determined, the repair is only acceptable for one cycle.

(b) Weld overlay repair of an area can only be performed once in the same location.

(c) When through-wall repairs are made by welding on surfaces that are wet or exposed to water, the weld overlay repair is only acceptable until the next refueling outage.

The basis for use of the repair technique described in Code Case N- 661 is that the ASME Code subcommittee for Section XI determined that this repair technique provides an acceptable alternative to the requirements of IWA-4000 and provides an acceptable level of quality and safety. Therefore, the proposed alternative is justified per 10 CFR 50.55a(a)(3)(i).

Code Case N- 661 was approved by the ASME Section XI Code Committee on July 23, 2002; however, it has not been incorporated into NRC Regulatory Guide (RG) 1.147 Inservice Inspection Code Case Acceptability, ASME Section XI Division 1, and thus is not available for application at nuclear power plants without specific NRC approval. Therefore, the licensee is requesting use of the alternative repair technique described via this relief request.

Duration of Proposed Alternative The licensee requested authorization of Code Case N- 661 to be used for PNPPs 10-year ISI interval or until the NRC publishes Code Case N-661 in a future revision of RG 1.147. Upon incorporation into the RG, the licensee stated they will review and follow the conditions specified. The licensee also stated that all other ASME Code,Section XI requirements for which relief was not specifically requested and authorized by the NRC staff will remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.

Staff Evaluation By letter dated July 28, 2004, the licensee requested that the NRC approve an alternative to the requirements of IWA-4120(a) and IWA-4310 of the 1989 Edition of the ASME Code Section XI.

Specifically, the licensee requested that the NRC approve ASME Code Case N-661 for use at PNPP. The request was made pursuant to 10 CFR 50.55a(a)(3)(i) to address replacement or internal weld repair of wall thinning conditions resulting from various wall thinning degradation mechanisms such as erosion, corrosion, cavitation, and pitting in Class 2 and 3 carbon steel raw water piping systems. The licensee stated the reason for the relief request was to provide

adequate time for additional examination of adjacent piping so that pipe replacements can be planned to reduce impact on system availability and availability of replacement materials.

The licensee is proposing to use the provisions of Code Case N-661 to perform an alternative repair of degraded components which involves the application of weld metal overlay on the exterior of the piping system to restore the wall thickness of the component. The licensee stated that this repair technique will be utilized whenever engineering evaluations determine that such a repair is suitable for the particular defect or degradation being resolved. Provisions for use of this Code Case will be addressed in the licensees Repair and Replacement Program. The licensee stated that those provisions will require that adjacent areas be examined to verify that the entire flawed area will be encompassed by the repair and that there are no other unacceptable degraded locations within a representative area dependent on the degradation mechanism present. An evaluation of the degradation mechanism will be performed by the licensee to determine the re-examination schedule to be performed over the life of the repair. The licensee stated the repair will be considered to have a maximum service life of two fuel cycles unless examinations during each of the two fuel cycles are performed to establish the expected life of the repair.

The NRC staff finds the licensees reasoning in support of its request for relief acceptable. This finding is based on the fact that the NRC staff has reviewed Code Case N-661 for inclusion in RG 1.147. The NRC staffs review of Code Case N-661 established three conditions that the licensee agreed to place on the use of Code Case N-661 to assure that the Code Case will provide an acceptable alternative pursuant to 10 CFR 50.55a(a)(3)(i). These conditions are:

(a) If the root cause of the degradation has not been determined, the repair is only acceptable for one cycle.

(b) Weld overlay repair of an area can only be performed once in the same location.

(c) When through-wall repairs are made by welding on surfaces that are wet or exposed to water, the weld overlay is only acceptable until the next refueling outage.

The NRC staff established these three conditions based on the following considerations:

(a) If the root cause of the degradation has not been determined, a suitable reinspection frequency cannot be established.

(b) Weld overlay repair of an area can only be performed once to ensure that ineffective repairs are not being repeatedly implemented in the same location.

(c) Performing through-wall weld repairs on surfaces that are wet or exposed to water would produce welds that include weld defects such as porosity, lack of fusion, and cracks. It is highly unlikely that a weld can be made on an open root joint with water present on the backside of the weld without having several weld defects.

These types of weld defects can, and many times do, lead to premature failure of a weld joint.

3.0 CONCLUSION

Based on the information provided in the licensees submittal, the NRC staff concludes that the licensee has provided an acceptable alternative to the requirements of IWA-4120(a) and IWA-4310 of the 1989 Edition of the ASME Code Section XI, subject to the following three conditions which must be met when using Code Case N-661. These conditions are: (a) if the root cause of the degradation has not been determined, the repair is only acceptable for one cycle; (b) weld overlay repair of an area can only be performed once in the same location; and (c) when through-wall repairs are made by welding on surfaces that are wet or exposed to water, the weld overlay repair is only acceptable until the next refueling outage. The NRC staff concludes that the proposed alternative, as supplemented by the three conditions listed above, provides an acceptable level of quality and safety. Therefore, the proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for PNPP for the current 10-year ISI interval, or until Code Case N-661 is approved for general use by reference in RG 1.147. After that time, if the licensee wishes to continue to use Code Case N-661, the licensee must follow the conditions, if any, specified in RG 1.147. All other ASME Code,Section XI, requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.

Principal Contributor: Eric Reichelt Date: January 18, 2005

Palisades Plant cc:

Robert A. Fenech, Senior Vice President Michigan Department of Attorney General Nuclear, Fossil, and Hydro Operations Special Litigation Division Consumers Energy Company 525 West Ottawa St.

1945 Parnall Rd. Sixth Floor, G. Mennen Williams Building Jackson, MI 49201 Lansing, MI 48913 Arunas T. Udrys, Esquire Manager, Regulatory Affairs Consumers Energy Company Nuclear Management Company, LLC 1 Energy Plaza 27780 Blue Star Memorial Highway Jackson, MI 49201 Covert, MI 49043 Regional Administrator, Region III Director of Nuclear Assets U.S. Nuclear Regulatory Commission Consumers Energy Company 801 Warrenville Road Palisades Nuclear Plant Lisle, IL 60532-4351 27780 Blue Star Memorial Highway Covert, MI 49043 Supervisor Covert Township John Paul Cowan P. O. Box 35 Executive Vice President & Chief Nuclear Covert, MI 49043 Officer Nuclear Management Company, LLC Office of the Governor 700 First Street P. O. Box 30013 Hudson, WI 54016 Lansing, MI 48909 Jonathan Rogoff, Esquire U.S. Nuclear Regulatory Commission Vice President, Counsel & Secretary Resident Inspector's Office Nuclear Management Company, LLC Palisades Plant 700 First Street 27782 Blue Star Memorial Highway Hudson, WI 54016 Covert, MI 49043 Douglas E. Cooper Michigan Department of Environmental Quality Senior Vice President - Group Operations Waste and Hazardous Materials Division Palisades Nuclear Plant Hazardous Waste and Radiological Nuclear Management Company, LLC Protection Section 27780 Blue Star Memorial Highway Nuclear Facilities Unit Covert, MI 49043 Constitution Hall, Lower-Level North 525 West Allegan Street P.O. Box 30241 Lansing, MI 48909-7741 October 2003