ML063450347

Relief, Relief Request ISI-3-23 for Third 10-Year ISI Interval to Allow Use of American Society of Mechanical Engineers Code Case N-746, MC9433 & MC9434

ML063450347
Person / Time
Site:	San Onofre
Issue date:	12/27/2006
From:	Terao D NRC/NRR/ADRO/DORL/LPLIV
To:	Rosenblum R Southern California Edison Co
Kalynanam N, NRR/DORL/LP4, 415-1480
References
TAC MC9433, TAC MC9434
Download: ML063450347 (8)

Text

December 27, 2006 Mr. Richard M. Rosenblum Senior Vice President and Chief Nuclear Officer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128

SUBJECT:

SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 - RE:

REQUEST FOR RELIEF ISI-3-23 FOR THIRD 10-YEAR INSERVICE INSPECTION INTERVAL TO ALLOW THE USE OF AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE CASE N-746 (TAC NOS. MD1809 AND MD1810)

Dear Mr. Rosenblum:

By letter dated May 16, 2006, Southern California Edison (SCE, the licensee) submitted Relief Request ISI-3-23, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) paragraph 50.55a(a)(3)(i), to allow the use of American Society of Mechanical Engineers (ASME) Code Case N-746, Use of 46Fe-24Ni-21Cr-6Mo-Cu-N (UNS N08367) Bolting Material for Class 2 and 3 Components, for the third 10-year inservice inspection (ISI) interval, which began on August 18, 2003, and is scheduled to end on August 17, 2013.

The licensee proposes to use the Code Case for the replacement of bolting material associated with eight saltwater cooling pumps that supply cooling water from the ocean to the component cooling water-heat exchangers at San Onofre Nuclear Generating Station, Units 2 and 3 (SONGS 2 and 3). Use of Code Case N-746 will allow SCE to use Unified Numbering System N08367 (UNS N08367) bolting material conforming to the requirements of SB-691 on replacement Salt Water Cooling Pumps.

The Nuclear Regulatory Commission (NRC) staff finds the licensees request for relief acceptable. Therefore, the NRC staff authorizes the alternative proposed by SCE, in accordance with 10 CFR 50.55a(a)(3)(i), which states that the proposed alternatives may be used when authorized by the Director of the Office of Nuclear Reactor Regulation if the applicant demonstrates that the proposed alternatives would provide an acceptable level of quality and safety.

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 ASME Code,Section XI, 1998 Edition through 2000 Addenda. The staff concludes that the proposed alternative provides reasonable assurance of quality and safety. Therefore, the proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for SONGS 2 and 3 for the current 10-year ISI interval, or until Code Case N-746 is approved for general use by inclusion in Regulatory Guide (RG) 1.84. After that time, if the licensee wishes to continue to use Code Case N-746, the licensee must follow the conditions, if any, specified in the RG.

R. Rosenblum The staff's safety evaluation is enclosed.

Sincerely,

/RA/

David Terao, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362

Enclosure:

Safety Evaluation cc w/encl: See next page

ML063450347 *Minor editorial changes made in staff supplied SE OFFICE NRR/LPL4/PM NRR/LPL4/LA DCI/CPNB* OGC-NLO NRR/LPL4/BC NAME NKalyanam LFeizollahi TChan TCampbell DTerao DATE 12/18/06 12/18/07 12/4/06 12/21/07 12/27/07 San Onofre Nuclear Generating Station Units 2 and 3 cc:

Mr. Daniel P. Breig Director, Radiologic Health Branch Southern California Edison Company State Department of Health Services San Onofre Nuclear Generating Station P.O. Box 997414, MS 7610 P.O. Box 128 Sacramento, CA 95899-7414 San Clemente, CA 92674-0128 Resident Inspector/San Onofre NPS Mr. Douglas K. Porter, Esquire c/o U.S. Nuclear Regulatory Commission Southern California Edison Company Post Office Box 4329 2244 Walnut Grove Avenue San Clemente, CA 92674 Rosemead, CA 91770 Mayor Mr. David Spath, Chief City of San Clemente Division of Drinking Water and 100 Avenida Presidio Environmental Management San Clemente, CA 92672 P.O. Box 942732 Sacramento, CA 94234-7320 Mr. James T. Reilly Southern California Edison Company Chairman, Board of Supervisors San Onofre Nuclear Generating Station County of San Diego P.O. Box 128 1600 Pacific Highway, Room 335 San Clemente, CA 92674-0128 San Diego, CA 92101 Mr. James D. Boyd, Commissioner Mark L. Parsons California Energy Commission Deputy City Attorney 1516 Ninth Street (MS 31)

City of Riverside Sacramento, CA 95814 3900 Main Street Riverside, CA 92522 Mr. Ray Waldo, Vice President Southern California Edison Company Mr. Gary L. Nolff San Onofre Nuclear Generating Station Assistant Director - Resources P.O. Box 128 City of Riverside San Clemente, CA 92764-0128 3900 Main Street Riverside, CA 92522 Mr. Brian Katz Southern California Edison Company Regional Administrator, Region IV San Onofre Nuclear Generating Station U.S. Nuclear Regulatory Commission P.O. Box 128 611 Ryan Plaza Drive, Suite 400 San Clemente, CA 92764-0128 Arlington, TX 76011-8064 Mr. Steve Hsu Mr. Michael R. Olson Department of Health Services San Diego Gas & Electric Company Radiologic Health Branch 8315 Century Park Ct. CP21G MS 7610, P.O. Box 997414 San Diego, CA 92123-1548 Sacramento, CA 95899 Mr. A. Edward Scherer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128 March 2006

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF NUMBER ISI-3-23 SOUTHERN CALIFORNIA EDISON COMPANY SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362

1.0 INTRODUCTION

By letter dated May 16, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML061380119), the Southern California Edison Company (SCE, the licensee) requested, pursuant to Title 10 of the Code of Federal Regulations (10 CFR),

paragraph 50.55a(a)(3)(i), that the Nuclear Regulatory Commission (NRC) approve Relief Request ISI-3-23. The relief requested approval of American Society of Mechanical Engineers (ASME) Code Case N-746, Use of 46Fe-24Ni-21Cr-6Mo-Cu-N (Unified Numbering System (UNS) N08367) Bolting Material for Class 2 and 3 Components. Specifically, the licensee proposed to use the Code Case for the replacement of bolting material associated with eight saltwater cooling pumps that supply cooling water from the ocean to the component cooling water-heat exchangers at San Onofre Nuclear Generating Station, Units 2 and 3 (SONGS 2 and 3). The ASME Code of record for replacement of components for SONGS 2 and 3 is the ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through the 2000 Addenda.

The ASME Code,Section XI, requires that the replacement pumps meet the construction code (or later) to which the original component was constructed. The existing pumps are ASME Code,Section III, Division 1, Class 3 pumps, constructed from 316L stainless steel material which require periodic overhauls to maintain reliability because of saltwater corrosion. The pumps will be replaced using UNS N08367 material, which is saltwater corrosion-resistant.

UNS N08367 material is included in the ASME Code,Section III, as an approved material for pressure boundary parts; however, the material is not listed in the ASME Code as an approved bolting material. To allow the use of UNS N08367 material, the ASME Code approved and published Code Case N-746 which approved UNS N08367 material for bolting applications.

Experience has shown the that use of UNS N08367 bolting material is superior to the existing 316L stainless steel bolting material that is currently used. The UNS N08367 bolting material provides superior corrosion resistance in saltwater service and provides galvanic compatibility with the pump pressure boundary parts.

The replacement of the saltwater pumps is scheduled to take place during the third 10-year inservice inspection (ISI) interval which began on August 18, 2003 and is scheduled to end on August 17, 2013. The ISI code of record for the SONGS 2 and 3, is ASME Code,Section XI, 1998 Edition through 2000 Addenda.

2.0 REGULATORY EVALUATION

Paragraph 50.55a(g) of 10 CFR specifies that ISI of nuclear power plant components shall be performed in accordance with the requirements of the ASME Code,Section XI, except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).

Paragraph 50.55a(a)(3) of 10 CFR 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.

Paragraph 50.55a(g)(5)(iii) of 10 CFR states that if the licensee has determined that conformance with certain code requirements is impractical for its facility, the licensee shall notify the Commission and submit information, as specified in §50.4, to support the determinations.

3.0 EVALUATION OF THE RELIEF REQUEST The information provided by the licensee in support of the request has been evaluated by the NRC staff and the bases for disposition are documented below.

3.1 Licensees Evaluation 3.1.1 Component Identification SONGS Units: 2 and 3

==

Description:==

Salt Water Cooling Pumps, 4 per Unit.

Code Class: 3 3.1.2 Applicable Code Edition and Addenda The construction code for the SONGS 2 and 3 replacement saltwater cooling pumps is the ASME Boiler and Pressure Vessel Code,Section III, 1998 Edition through 2000 Addenda.

3.1.3 Applicable Code Requirements Sub-article ND-2128(a) ASME Code, Section Ill, 1998 Edition through 2000 Addenda states, "Material for bolts and studs shall conform to the requirements of one of the specifications listed in Table 3, ASME Section II, Part D, Subpart 1. Material for nuts shall conform to SA-194 or to the requirements of one of the specifications for nuts or bolting listed in Table 3 of ASME Section II, Part D, Subpart 1."

3.1.4 Reason for Request New saltwater cooling pumps are being fabricated from UNS N08367 material to replace the existing 316L stainless steel pumps. The pressure boundary parts will be UNS N08367 material as allowed by ASME Code,Section III. It is desired to use pressure boundary bolting

of the same chemical composition as the pressure parts, namely N08367. However, N08367 material is not listed in the bolting table (Table 3, ASME Code,Section II, Part D) specified in ASME Code, Section Ill, ND-2128.

For this application, the use of UNS N08367 bolting material is superior to the existing bolting materials in Table 3, ASME Code,Section II, Part D. The current bolting materials available in the Table 3 do not provide the superior corrosion resistance of UNS N08367 material in saltwater service and galvanic compatibility with the pressure boundary parts.

3.1.5 Proposed Alternative and Basis for Use Pursuant to 10 CFR 50.55a(a)(3)(i), SCE proposes to implement Code Case N-746 and use alternative pressure boundary bolting material (UNS N08367) for use on ASME Code, Section Ill, Division 1, Class 3 saltwater cooling pumps. The pumps fall under 10 CFR 50.55a(e), Quality Group C Components meeting the requirements for Class 3 components in the ASME Boiler and Pressure Vessel Code. Specifically, SCE is requesting approval to use Code Case N-746. This proposed alternative would provide an acceptable level of quality and safety and thus would meet the requirements of 10 CFR 50.55a(a)(3).

The pumps are being replaced with UNS N08367 material because of its superior corrosion resistance for saltwater service. The UNS N08367 material is already approved for use as pressure boundary components in various product forms such as plate (SB-688), forgings (SB-462 and SB-564), welded pipe and tube (SB-675, 804, and 676), seamless pipe and tube (SB-690); and rod, bar, and wire (SB-691).

There is a precedent for application of rod material for use as bolting. A review of Table 3, ASME Code,Section II, Part D, shows three nickel-alloy specifications that cover rods:

Ni-Cr-Fe-Mo, Fe-Ni-Cr-Co (SB-572), Ni-Mo-Cr, Ni-Cr-Mo (SB-574), and Ni-Cr-Fe rods (SB-581), listed as bolting. This precedent supports the approval of Code Case N-746.

3.1.6 Duration of Proposed Alternative SCE requests that the 10 CFR 50.55a(a)(3)(i) relief for the alternative bolting material for the saltwater cooling pumps be granted for SONGS 2 and 3 for the third 10-year interval which began on August 18, 2003, and is scheduled to end on August 17, 2013.

3.1.7 Staff Evaluation The licensee requested approval of ASME Code Case N-746, Use of 46Fe-24Ni-21Cr-6Mo-Cu-N (UNS N08367) Bolting Material for Class 2 and 3 Components. The relief is needed because of planned replacement of eight saltwater cooling pumps at SONGS 2 and 3. ASME Code,Section XI, 1998 Edition through the 2000 Addenda is the ISI Code of record for SONGS 2 and 3.

ASME Code,Section XI, requires that the new pumps meet the construction code to which the original item was constructed. The licensee stated that the existing pumps are ASME Code,Section III, Division 1, Class 3 pumps constructed from 316L stainless steel material, which require periodic overhauls to maintain reliability because of corrosion from saltwater. The existing pumps will be replaced with corrosion-resistant material UNS N08367, which is superior material for seawater service as compared to 316L material currently in service. UNS N08367 is a

nickel-molybdenum alloy with excellent resistance to chloride pitting and crevice corrosion.

UNS N08367 retains high ductility and impact strength and has been used for chemical process tanks and pipelines, offshore oil and gas production equipment, and seawater heat exchangers.

UNS N08367 material is included in the ASME Code,Section III, as an approved material for pressure boundary parts. However, the material is not listed in the ASME Code as an approved bolting material.

To approve the use of UNS N08367 as bolting material, the ASME Code,Section III, approved and published Code Case N-746. The NRC staff finds Code Case N-746 to be acceptable for use and has included it in the forthcoming revision of Regulatory Guide (RG) 1.84, Design, Fabrication, and Materials Code Case Acceptability, ASME Section III. However, the forthcoming revision of RG 1.84 has not yet been published and, therefore, Code Case N-746 is not yet listed as an approved Code Case in RG 1.84.

Based on the pending approval of Code Case N-746, the staff finds the licensees reasoning in support of its request for relief acceptable and concludes that the use of Code Case N-746 is acceptable.

4.0 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 ASME Code,Section XI, 1998 Edition through 2000 Addenda. The staff concludes that the proposed alternative provides reasonable assurance of quality and safety. Therefore, the proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the SONGS 2 and 3 for the current 10-year ISI interval, or until Code Case N-746 is approved for general use by reference in RG 1.84.

After that time, if the licensee wishes to continue to use Code Case N-746, the licensee must follow the conditions, if any, specified in the RG. All other ASME Code, Sections III and 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: G. Georgiev Date: December 27, 2006