ML033450187
| ML033450187 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/05/2003 |
| From: | Berkow H NRC/NRR/DLPM/LPD4 |
| To: | Overbeck G Arizona Public Service Co |
| Berkow H, NRR/DLPM/LPD2, 415-1395 | |
| References | |
| Download: ML033450187 (7) | |
Text
December 5, 2003 Mr. Gregg R. Overbeck Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 - JUSTIFICATION REQUIRED FOR MECHANICAL NOZZLE SEAL ASSEMBLY (MNSA) TO BE USED AS A PERMANENT REPAIR
Dear Mr. Overbeck:
The mechanical nozzle seal assembly (MNSA) is a mechanical device that industry is using to provide both sealing and structural integrity for leaking nozzle connections. Currently, MNSAs have been installed on the exterior surfaces of reactor coolant pressure boundary components, as an alternative to weld repairs for leaks in small diameter J-groove welded Alloy 600 instrument nozzles and thermal sleeves. The NRC has accepted MNSA repairs on a temporary basis for two operating cycles. A number of licensees have requested and have been granted NRC approval extending the temporary MNSA repairs beyond the two operating cycles for additional cycles on the same basis as that on which initial approval was granted.
It is the position of the NRC staff that should a licensee decide to keep a MNSA in service beyond the period for which temporary approval has already been granted, the licensee shall provide a justification which supports the approval of the MNSA as a permanent repair. The licensees justification should include an analysis of the pressure boundary component to which the MNSA is attached and an inservice inspection program to be maintained throughout the licensed life of the facility. The licensees justification should be submitted for NRC staff review and approval no later than one year prior to the expiration of its existing temporary repair approval period. Additional guidance regarding what information should be included in a licensees justification is provided in the enclosure.
If you have any questions, or need clarification, you can call me (301-415-1395), Steve Dembek (301-415-1455), or Brian Benney (301-415-3764).
Sincerely,
/RA/
Herbert Berkow, Director Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. STN 50-530
Enclosure:
Analysis and Inspection Criteria cc w/encl: See next page
December 5, 2003 Mr. Gregg R. Overbeck Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 - JUSTIFICATION REQUIRED FOR MECHANICAL NOZZLE SEAL ASSEMBLY (MNSA) TO BE USED AS A PERMANENT REPAIR
Dear Mr. Overbeck:
The mechanical nozzle seal assembly (MNSA) is a mechanical device that industry is using to provide both sealing and structural integrity for leaking nozzle connections. Currently, MNSAs have been installed on the exterior surfaces of reactor coolant pressure boundary components, as an alternative to weld repairs for leaks in small diameter J-groove welded Alloy 600 instrument nozzles and thermal sleeves. The NRC has accepted MNSA repairs on a temporary basis for two operating cycles. A number of licensees have requested and have been granted NRC approval extending the temporary MNSA repairs beyond the two operating cycles for additional cycles on the same basis as that on which initial approval was granted.
It is the position of the NRC staff that should a licensee decide to keep a MNSA in service beyond the period for which temporary approval has already been granted, the licensee shall provide a justification which supports the approval of the MNSA as a permanent repair. The licensees justification should include an analysis of the pressure boundary component to which the MNSA is attached and an inservice inspection program to be maintained throughout the licensed life of the facility. The licensees justification should be submitted for NRC staff review and approval no later than one year prior to the expiration of its existing temporary repair approval period. Additional guidance regarding what information should be included in a licensees justification is provided in the enclosure.
If you have any questions, or need clarification, you can call me (301-415-1395), Steve Dembek (301-415-1455), or Brian Benney (301-415-3764).
Sincerely,
/RA/
Herbert Berkow, Director Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. STN 50-530 DISTRIBUTION:
PUBLIC BElliot
Enclosure:
Analysis and Inspection Criteria PDIV-2 Reading RidsNrrDlpmPdiv (HBerkow) cc w/encl: See next page RidsNrrPMBBenney RidsNrrPMMFields RidsNrrLAMMcAlister RidsOgcRp RidsAcrsAcnwMailCenter WBateman ACCESSION NO.: ML033450187 NRR-106 MMitchell
- See Previous Concurrence OFFICE PDIV-2/PM PDIV-2/LA*
EMCB/SC*
OGC*
PDIV-2/SC PDIV/D NAME BBenney EPeyton BBateman AFernandez SDembek HBerkow DATE 12/5/03 10/24/03 10/24/03 11/24/03 12/5/03 12/5/03 DOCUMENT NAME: C:\\ORPCheckout\\FileNET\\ML033450187.wpd OFFICIAL RECORD COPY
July 2003 Palo Verde Generating Station, Units 1, 2, and 3 cc:
Mr. Steve Olea Arizona Corporation Commission 1200 W. Washington Street Phoenix, AZ 85007 Douglas Kent Porter Senior Counsel Southern California Edison Company Law Department, Generation Resources P.O. Box 800 Rosemead, CA 91770 Senior Resident Inspector U.S. Nuclear Regulatory Commission P. O. Box 40 Buckeye, AZ 85326 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 Chairman Maricopa County Board of Supervisors 301 W. Jefferson, 10th Floor Phoenix, AZ 85003 Mr. Aubrey V. Godwin, Director Arizona Radiation Regulatory Agency 4814 South 40 Street Phoenix, AZ 85040 Mr. Craig K. Seaman, Director 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 2702 N. Third Street, Suite 3040 Phoenix, AZ 85004 Mr. John Taylor Public Service Company of New Mexico 2401 Aztec NE, MS Z110 Albuquerque, NM 87107-4224 Ms. Cheryl Adams Southern California Edison Company 5000 Pacific Coast Hwy Bldg DIN San Clemente, CA 92672 Mr. Robert Henry Salt River Project 6504 East Thomas Road Scottsdale, AZ 85251 Terry Bassham, Esq.
General Counsel El Paso Electric Company 123 W. Mills El Paso, TX 79901 Mr. John Schumann Los Angeles Department of Water & Power Southern California Public Power Authority P.O. Box 51111, Room 1255-C Los Angeles, CA 90051-0100 Brian Almon Public Utility Commission William B. Travis Building P. O. Box 13326 1701 North Congress Avenue Austin, TX 78701-3326
ANALYSIS AND INSPECTION CRITERIA Analysis of Pressure Boundary Component The qualification by analysis of the pressure boundary component to which the mechanical nozzle seal assembly (MNSA) is attached by threaded bolts or tie-rods should be based on the calculation of the primary and secondary membrane, bending and shear stresses calculated from a detailed 3-D finite element analysis. The finite element model should encompass the instrument or heater nozzle through-wall hole and the adjacent tapped holes, and for MNSA-2, the machined counterbore within the nozzle hole.
The qualification should include and be based on the following:
A list of all plant unique pressure boundary design conditions and operating transients, showing operating pressure, mean wall temperature, and wall temperature gradient, for the pressure boundary component.
Detailed calculation of the load in the highest-loaded bolts or tie-rods, resulting from preloading, maximum operating loads, including seismic loads, and accounting for non-linear loading and unloading load-deformation characteristics of the gasket and Belleville washer packs.
Demonstration that the primary and secondary stresses resulting from the finite element analysis meet the ASME Section III NB-3200 stress intensity limits and appropriate special stress limits, under all design loading and service condition mechanical and thermal transients, including the effects on the tapped holes due to the highest bolt or tie-rod loads, and demonstration that the Class 1 fatigue analysis of the pressure boundary will not exceed the Code prescribed cumulative usage factor limit of 1.0 for the life of the plant.
Demonstration that there is no interaction between adjacent pressure boundary regions where MNSAs are mounted.
ASME Section III minimum wall thickness requirements at the deepest point in the counterbore should be met.
Demonstration that the ASME Section III NB-3300 area reinforcement requirements are met.
Reconciliation of the owners construction code and the replacement code.
Inservice Inspection Identify what inservice inspection program will be implemented to ensure that the structural and leakage integrity of the MNSA will be maintained throughout the licensed life of the facility. The proposed program should include consideration of the potential for leakage from the MNSA, as well as the potential for leakage from other sources which could impact the integrity of the MNSA. The proposed program should address the type of inspections (e.g., a visual examination VT-2 with insulation removed), inspection scope, periodicity of inspections, inspection qualification, and inspection acceptance criteria.
Identify what inservice inspection program will be implemented to ensure that the structural integrity of the MNSA bolting and threaded holes in the component to which the MNSA is attached will be maintained throughout the licensed life of the facility. The proposed inspections should be designed to detect cracking of the bolting and in the threaded hole due to fatigue, stress corrosion cracking, etc. Disassembly of the MNSA in order to conduct the inspections should be considered. The proposed program should address the type of inspections, inspection scope, periodicity of inspections, inspection qualification, and inspection acceptance criteria.
Identify what inservice inspection program will be implemented to ensure that corrosion detrimental to the structural integrity of the component to which the MNSA is attached will not occur due to exposure of low alloy/carbon steel material in the bore of the penetration throughout the licensed life of the facility. The proposed program should address the type of inspections, inspection scope, periodicity of inspections, inspection qualification, and inspection acceptance criteria.