ML16139A442
| ML16139A442 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/11/1994 |
| From: | Berkow H Office of Nuclear Reactor Regulation |
| To: | Hampton J DUKE POWER CO. |
| References | |
| TAC-M89886, NUDOCS 9408170179 | |
| Download: ML16139A442 (5) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 August 11, 1994 Docket No. 50-287 Mr. J. W. Hampton Vice President, Oconee Site Duke Power Company P. 0. Box 1439 Seneca, South Carolina 29679
Dear Mr. Hampton:
SUBJECT:
REQUEST FOR RELIEF NO. 94 OCONEE NUCLEAR STATION, UNIT 3 (TAC NO. M89886)
By letter dated July 14, 1994, you submitted Relief Request No. 94-07 from ASME Code requirements for the preservice inspection of four welds performed by the vendor during the fabrication of the replacement 3A High Pressure Injection Letdown Cooler. The welds were on the primary side inlet and outlet of the cooler, attaching each tubesheet to its tube side channel body, and connecting each channel nozzle to its tube side channel body.
For these inservice inspection (ISI) Class 1 welds, the ASME Boiler and Pressure Vessel Code Section XI, 1980 Edition (with addenda through Winter 1980) in Paragraphs IWB-7400, IWA-7530, IWB-2200, and Table IWB-2500-1, Examination Category B-B and B-D, requires that replacements receive a preservice inspection prior to the return of the plant to service. Code Case N-460 requires 90% or greater examination coverage for the volumetric examination to be considered acceptable.
These welds received a liquid penetrant examination of the root and final welds by the manufacturer. The primary side of the cooler was hydrostatically tested at 3750 psig by the manufacturer. During the replacement of the letdown cooler, the tubesheet and nozzle welds for the primary side inlet and outlet were ultrasonically examined by Duke Power Company to satisfy the preservice examination requirements of Section XI of the ASME Code. Due to part geometry, joint configuration, and interferences, it was not possible to obtain 90% examination coverage on these welds. The examination coverages were 38% on the inlet and outlet channel nozzle welds, 80.9% on the inlet tubesheet weld, and 84.09% on the outlet tubesheet weld. The joint and part configurations are such that radiographic examination cannot be used to supplement the ultrasonic examination to increase the examination coverage.
By teleconference call to your staff on July 15, 1994, we obtained further information regarding the location of the subject welds, the nature of the obstructions and interferences that make increased volumetric examination coverage of the welds impractical, and the reason why the incompletely inspected cooler was accepted from the vendor. We obtained additional information regarding the ISI class and specifications for the manufacture and testing of the replacement letdown cooler.
9408170179 940811 W C RLE N TE COP PDR ADOCK 05000287 Q
Mr. J. W. Hampton
- 2 The relief request further stated that, if these welds fail, emergency procedures are in place to safely recover from this event. There is a cooler inlet valve which can be closed to isolate the reactor coolant system from the failed weld. Should the "A" cooler fail, it would be isolated and the "B" cooler could be used to perform the system function.
Your staff has requested relief from the volumetric examination coverage requirements of the ASME Code and approval of the alternative testing proposed in Relief Request No. 94-07, i.e., the non-destructive examinations and hydrostatic testing already performed by the manufacturer and the limited ultrasonic examinations by Duke Power, as described above.
Based on a preliminary review of the UT examinations, we find that it is impractical to achieve the Code-required coverage of the cooler welds in volumetric examinations. We also have determined that the penetration and hydrostatic pressure tests performed by the manufacturer and the limited ultrasonic tests performed by Duke Power Company will provide reasonable assurance of the structural reliability of the welds for an interim period until a more in-depth review is performed. We have given consideration to the fact that imposition of the Code requirement for 90% examination coverage would require development and implementation of plant design changes.
Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), Relief Request 94-07 is granted for an interim period, specifically until the end of the next refueling outage, to provide the opportunity for a more in-depth review of the preservice UT examinations of the replacement letdown coolers and the consideration of possible future design changes to allow sufficient weld inspection to meet Code requirements.
This 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 giving due consideration to the burden that could result if the requirements were imposed on the facility.
Sincerely, Original signed by:
Herbert N. Berkow, Director Project Directorate 11-3 Division of Reactor Projects -
I/II Office of Nuclear Reactor Regulation cc:
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Mr. J. W. Hampton
- 2 The relief request further stated that, if these welds fail, emergency procedures are in place to safely recover from this event. There is a cooler inlet valve which can be closed to isolate the reactor coolant system from the failed weld.
Should the "A" cooler fail, it would be isolated and the "B" cooler could be used to perform the system function.
Your staff has requested relief from the volumetric examination coverage requirements of the ASME Code and approval of the alternative testing proposed in Relief Request No. 94-07, i.e., the non-destructive examinations and hydrostatic testing already performed by the manufacturer and the limited ultrasonic examinations by Duke Power, as described above.
Based on a preliminary review of the UT examinations, we find that it is impractical to achieve the Code-required coverage of the cooler welds in volumetric examinations. We also have determined that the penetration and hydrostatic pressure tests performed by the manufacturer and the limited ultrasonic tests performed by Duke Power Company will provide reasonable assurance of the structural reliability of the welds for an interim period until a more in-depth review is performed. We have given consideration to the fact that imposition of the Code requirement for 90% examination coverage would require development and implementation of plant design changes.
Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), Relief Request 94-07 is granted for an interim period, specifically until the end of the next refueling outage, to provide the opportunity for a more in-depth review of the preservice UT examinations of the replacement letdown coolers and the consideration of possible future design changes to allow sufficient weld inspection to meet Code requirements.
This 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 giving due consideration to the burden that could result if the requirements were imposed on the facility.
Sincerely, H rbert N. B kow, Director Project Directorate 11-3 Division of Reactor Projects -
I/II Office of Nuclear Reactor Regulation cc:
See next page
Mr. J. W. Hampton Duke Power Company Oconee Nuclear Station cc:
A. V. Carr, Esquire Mr. Steve Benesole Duke Power Company Compliance 422 South Church Street Duke Power Company Charlotte, North Carolina 28242-0001 Oconee Nuclear Site P. 0. Box 1439 J. Michael McGarry, III, Esquire Seneca, South Carolina 29679 Winston and Strawn 1400 L Street, NW.
Mr. Marvin Sinkule, Chief Washington, DC 20005 Project Branch #3 U. S. Nuclear Regulatory Commission Mr. Robert B. Borsum 101 Marietta Street, NW. Suite 2900 Babcock & Wilcox Atlanta, Georgia 30323 Nuclear Power Division Suite 525 Ms. Karen E. Long 1700 Rockville Pike Assistant Attorney General Rockville, Maryland 20852 North Carolina Department of Justice Manager, LIS P. 0. Box 629 NUS Corporation Raleigh, North Carolina 27602 2650 McCormick Drive, 3rd Floor Clearwater, Florida 34619-1035 Mr. G. A. Copp Licensing -
ECO50 Senior Resident Inspector Duke Power Company U. S. Nuclear Regulatory Commission 526 South Church Street Route 2, Box 610 Charlotte, North Carolina 28242-0001 Seneca, South Carolina 29678 Dayne H. Brown, Director Regional Administrator, Region II Division of Radiation Protection U. S. Nuclear Regulatory Commission North Carolina Department of 101 Marietta Street, NW. Suite 2900 Environment, Health and Atlanta, Georgia 30323 Natural Resources P. 0. Box 27687 Max Batavia, Chief Raleigh, North Carolina 27611-7687 Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 County Supervisor of Oconee County Walhalla, South Carolina 29621
- 4.
DISTRIBUTION NRC & Local PDRs PD23 Reading File W. Russell/F.Miraglia R. Zimmerman E. Rossi J. Lieberman S. Varga G. Lainas L. Wiens H. Berkow S. Kirslis L. Berry OGC E. Jordan G. Hill (4)