ML043270626

Palo Verde - Correction to Approval Letter for Relief Request No. 30

ML043270626
Person / Time
Site:	Palo Verde
Issue date:	11/19/2004
From:	Fields M NRC/NRR/DLPM/LPD4
To:	Overbeck G Arizona Public Service Co
Fields M, NRR/DLPM, 415-3062
References
TAC MC5080, TAC MC5081, TAC MC5082
Download: ML043270626 (4)

Text

November 19, 2004 Mr. Gregg R. Overbeck Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034

SUBJECT:

CORRECTION TO APPROVAL LETTER FOR RELIEF REQUEST NO. 30 (TAC NOS. MC5080, MC5081, AND MC5082)

Dear Mr. Overbeck:

On November 19, 2004, the Commission issued its approval letter for Relief Request No. 30, requested by Arizona Public Service Company in its letter dated November 11, 2004. The approval was for an alternative to American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case 1361-2, "Socket Welds,Section III," to allow a slightly larger diametral clearance between the replacement pressurizer heater sleeves and the heater sheaths.

Based on conversations with your staff, we are re-issuing the first two pages of the safety evaluation to remove references to mid-wall weld repairs associated with the pressurizer half-sleeve repairs activities. The areas of change are indicated by marginal lines. These references were related to the background discussion of the repair activities, and were not germane to the staff<s decision to approve the relief request. We apologize for any inconvenience this may have caused.

Sincerely,

/RA/

Mel B. Fields, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529 and STN 50-530

Enclosure:

Safety Evaluation (Pages 1 and 2) cc w/encl: See next page

November 19, 2004 Mr. Gregg R. Overbeck Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034

SUBJECT:

CORRECTION TO APPROVAL LETTER FOR RELIEF REQUEST NO. 30 (TAC NOS. MC5080, MC5081, AND MC5082)

Dear Mr. Overbeck:

On November 19, 2004, the Commission issued its approval letter for Relief Request No. 30, requested by Arizona Public Service Company in its letter dated November 11, 2004. The approval was for an alternative to American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case 1361-2, "Socket Welds,Section III," to allow a slightly larger diametral clearance between the replacement pressurizer heater sleeves and the heater sheaths.

Based on conversations with your staff, we are re-issuing the first two pages of the safety evaluation to remove references to mid-wall weld repairs associated with the pressurizer half-sleeve repairs activities. The areas of change are indicated by marginal lines. These references were related to the background discussion of the repair activities, and were not germane to the staff<s decision to approve the relief request. We apologize for any inconvenience this may have caused.

Sincerely,

/RA/

Mel B. Fields, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529 and STN 50-530

Enclosure:

Safety Evaluation (Pages 1 and 2) cc w/encl: See next page DISTRIBUTION:

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ACCESSION NO: ML043270626 Nrr-028 OFFICE PDIV-2/PM PDIV-1/LA PDIV-2/SC NAME MFields DBaxley RGramm DATE 11/19/04 11/19/04 11/19/04 OFFICIAL RECORD COPY

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION INSERVICE INSPECTION PROGRAM RELIEF REQUEST NO. 30 ARIZONA PUBLIC SERVICE COMPANY, ET AL.

PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 DOCKET NOS. STN 50-528, STN 50-529, AND STN 50-530

1.0 INTRODUCTION

By letter dated November 11, 2004, Arizona Public Service Company (APS or the licensee) submitted Relief Request No. 30, requesting NRC approval of an alternative to an American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) Case requirement for the Palo Verde Nuclear Generating Station (Palo Verde), Units 1, 2, and 3. The request for relief is from Code Case 1361-2, "Socket Welds,Section III," to allow a slightly larger diametral clearance between the replacement pressurizer heater sleeves and the heater sheaths. This request is associated with the pressurizer half-sleeve weld repairs at all three l units. These repairs were completed for Unit 2 during its fall 2003 refueling outage, are ongoing during the fall 2004 refueling outage for Unit 3, and are scheduled for the fall 2005 refueling outage for Unit 1. The relief is requested for the remainder of plant life at the three units.

2.0 BACKGROUND

The pressurizer lower head, to which the heater sleeves are attached, is manufactured from SA-533, Grade B, Class 1 low alloy steel. The pressurizer in each unit has 36 heater sleeves.

Each sleeve is a tube having nominal 1.66 inch outside diameter and 0.192 inch wall thickness, and is attached to the lower pressurizer head by a partial penetration weld (J-groove weld) made at the pressurizer inside surface. The original sleeves are made from Alloy 600 material, a nickel-based alloy, which has been found to be susceptible to primary water stress corrosion cracking (PWSCC). The attachment weld is made with Alloy 82/182 material which is a nickel-based alloy and is susceptible to PWSCC also. There is an overlay on the inside surface of the pressurizer at the intersection of the sleeve and penetration to reinforce the pressurizer wall.

The heater is inserted into the sleeve and is welded (fillet weld) to the sleeve.

Replacement of these sleeves by excavating the original attachment weld and then re-welding new full-length sleeves is not practical due to inaccessibility of the pressurizer vessel internal surface and high radiation field associated with the pressurizer. Therefore, APS proposes the half-sleeve replacement method. The lower half of the original sleeve is removed in two independent steps. First, the original sleeve is cut approximately 1 inch below the bottom surface of the pressurizer using a grinder. Second, the sleeve is severed within the penetration, approximately mid-wall, using a circular cutting disk, and is then removed. The l half-length replacement Alloy 690 sleeve is then inserted into the penetration by slip fit. The top l

half of the original sleeve and associated attachment weld will remain in service. There will be l a gap between the original half-sleeve and the new half-sleeve in the penetration.

APS stated that the Palo Verde, Unit 1, pressurizer sleeves have not had any repairs; however, as a preventive measure, APS will perform half-sleeve replacement on all 36 heater sleeves in Palo Verde, Unit 1, in the fall of 2005. The Palo Verde, Unit 2, pressurizer sleeves have been repaired using the half-sleeve replacement method and no additional repairs are necessary.

APS will perform half-sleeve replacement on all 36 heater sleeves in Palo Verde, Unit 3, in the fall of 2004.

The Palo Verde, Unit 2, heater sleeve replacement project (fall 2003) identified challenges in sleeve alignment and subsequent installation of heaters. As a result, a significantly longer duration than originally projected was required for sleeve welding. In an attempt to resolve the heater insertion challenges, APS increased the inside diameter of the replacement sleeve from 1.273 inch to 1.300 inch. The heater insertion challenges were essentially resolved utilizing the increased sleeve diameter. Ultimately, less radiation dose was incurred since substantially less time was spent by licensee personnel on the working platform.

The Unit 3 heater sleeve replacement project (fall 2004) incorporated the same heater sleeve inside diameter (1.300 inch). All heaters were inserted into the pressurizer on the initial attempt without rework and, therefore, there was no additional dose to personnel on the working platform due to rework.

The licensee recently determined that increasing the inside diameter of the replacement sleeves adversely impacted compliance with an ASME Section III Code Case.

3.0 REGULATORY REQUIREMENTS The inservice inspection (ISI) of the ASME Code Class 1, 2, and 3 components in nuclear plants is to be performed in accordance with the ASME Code Section XI and applicable edition and addenda as required by 50.55a(g) of Title 10 of the Code of Federal Regulations (10 CFR),

except where specific relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). The regulation at 10 CFR 50.55a(a)(3) states: "Proposed alternatives to the requirements of paragraphs (c), (d), (e), (f), (g), and (h) of this section or portions thereof may be used when authorized by the Director of the Office of Nuclear Reactor Regulation. The applicant shall demonstrate that: (i) The proposed alternatives would provide an acceptable level of quality and safety, or (ii) Compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety." The second 10-year ISI interval code for Palo Verde, Units 1, 2, and 3, is the ASME Code,Section XI, 1992 Edition, 1992 Addenda.

The 1992 Edition, 1992 Addenda, of the ASME Code,Section XI, IWA-4120(a) states that:

"Repairs shall be performed in accordance with the Owner's Design Specification and the original Construction Code of the component or system. Later Editions and Addenda of the Construction Code or of Section III, either in their entirety or portions thereof, and Code Cases may be used." The construction code for the Palo Verde units is ASME Section III, 1971 Edition, and 1973 Winter Addenda, and the installation code is ASME Section III, 1974 Edition, and 1975 Winter Addenda.

Palo Verde Generating Station, Units 1, 2, and 3 cc:

Mr. Steve Olea Mr. John Taylor Arizona Corporation Commission Public Service Company of New Mexico 1200 W. Washington Street 2401 Aztec NE, MS Z110 Phoenix, AZ 85007 Albuquerque, NM 87107-4224 Douglas Kent Porter Ms. Cheryl Adams Senior Counsel Southern California Edison Company Southern California Edison Company 5000 Pacific Coast Hwy Bldg DIN Law Department, Generation Resources San Clemente, CA 92672 P.O. Box 800 Rosemead, CA 91770 Mr. Robert Henry Salt River Project Senior Resident Inspector 6504 East Thomas Road U.S. Nuclear Regulatory Commission Scottsdale, AZ 85251 P. O. Box 40 Buckeye, AZ 85326 Mr. Jeffrey T. Weikert Assistant General Counsel Regional Administrator, Region IV El Paso Electric Company U.S. Nuclear Regulatory Commission Mail Location 167 Harris Tower & Pavillion 123 W. Mills 611 Ryan Plaza Drive, Suite 400 El Paso, TX 79901 Arlington, TX 76011-8064 Mr. John Schumann Chairman Los Angeles Department of Water & Power Maricopa County Board of Supervisors Southern California Public Power Authority 301 W. Jefferson, 10th Floor P.O. Box 51111, Room 1255-C Phoenix, AZ 85003 Los Angeles, CA 90051-0100 Mr. Aubrey V. Godwin, Director Brian Almon Arizona Radiation Regulatory Agency Public Utility Commission 4814 South 40 Street William B. Travis Building Phoenix, AZ 85040 P. O. Box 13326 1701 North Congress Avenue Mr. M. Dwayne Carnes, Director Austin, TX 78701-3326 Regulatory Affairs/Nuclear Assurance Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072-2034 Mr. Hector R. Puente Vice President, Power Generation El Paso Electric Company 310 E. Palm Lane, Suite 310 Phoenix, AZ 85004 November 2003