ML15238A359
| ML15238A359 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 01/22/1997 |
| From: | Berkow H NRC (Affiliation Not Assigned) |
| To: | Hampton J DUKE POWER CO. |
| Shared Package | |
| ML15238A360 | List: |
| References | |
| TAC-M97470, NUDOCS 9701240221 | |
| Download: ML15238A359 (4) | |
Text
0, UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 22, 1997 Mr. J. W. Hampton Vice President, Oconee Site Duke Power Company P. 0. Box 1439 Seneca, SC 29679
SUBJECT:
RELIEF REQUEST NO. 96-05 TO USE ALTERNATIVE TO ASME CODE SECTION III REPAIR OF REACTOR COOLANT PUMP MAIN FLANGE - OCONEE NUCLEAR STATION UNIT 1 (TAC NO. M97470)
Dear Mr. Hampton:
By letter dated December 26, 1996, Duke Power Company (licensee) requested approval of the alternative tests and inspections to the requirements of the ASME Section III Code, 1989 Edition, for weld repair to the Oconee Unit 1, reactor coolant pump main flange, pursuant to 10 CFR 50.55a(a)(3).
The staff's evaluation and conclusion are contained in the attached safety evaluation.
The staff has determined that the Code-required radiographic examination of the repaired areas lacks sensitivity to detect flaws smaller than one-half of an inch due to the magnitude of thickness being radiographed. Also, the other volumetric examination such as the ultrasonic examination of the flange as an alternative to radiographic examination, is impractical due to large grain size of cast stainless steel material as that of the main flange. However, the proposed liquid penetrant examination is a surface examination but very sensitive to detection of fine cracks such as the shrinkage cracks and the intergranular stress-corrosion cracks in stainless steel material.
When this examination is performed on layers of deposited weld metal, it is believed to provide adequate assurance of a sound weld metal.
Furthermore, a fatigue crack growth analysis and fracture evaluation was performed to determine the sensitivity of the pump main flange to the presence of flaws. A conservative analysis of crack growth as a function of number of startup-shutdown cycles for postulated flaws with depths from 0.5 to 2.5 inches indicates that the fatigue crack growth rate is negligible for all but the largest flaw, which will even withstand three times the design number of cycles. Since the flange material has good fracture toughness and the thickness in the bore region where cracks originally occurred is 30 inches, there is a large margin against any potential failure in this region. Therefore, your proposed alternative would provide an acceptable level of quality and safety and is authorized pursuant to 10 CFR 50.55a(a)(3)(i).
240039 MR8 FR.E CENTER 8 V p
9701240221 970122 PDR ADOCK 05000269 P
J. W. Hampton
-2 Accordingly, your request for relief is hereby granted.
Sincerely, H rbert N. Berkow, Director Project Directorate 11-2 Division of Reactor Projects -
I/II Office of Nuclear Reactor Regulation Docket No. 50-269
Enclosure:
Safety Evaluation cc w/encl: See next page
J.
January 22, 1997 Accordingly, your request for relief is hereby granted..
Sincerely, Original signed by:
Herbert N. Berkow, Director Project Directorate 11-2 Division of Reactor Projects -
I/II Office of Nuclear Reactor Regulation Docket No. 50-269
Enclosure:
. Safety Evaluation cc w/encl:
See next page Distribution:
Docket File LBerry EMerschoff, Ru PUBLIC DLaBarge RCrlenjak, RI PD 11 -2 Rdg.
OGC SVarga GHill (2)
JZwolinski ACRS HBerkow' GTracy PRII DOCUMENT NAME: G:\\OCONEE\\0C097470. RR
- See previous concurrence To receive a copy of this document, indicate in the box:
"C" = Copy without attachment/enclosure "E" = Copy with attachment/enclosure "N" = No copy OFFICE PM: DII 2*
LA:PDII C, OGC*
D:,PD I H
NAME -AUDrMRGE:cri LBERRY SET w/chgs.
H9ER J' DATE 1/16/97 1
/ 7 1/16/97 tI/
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/97 OFFICIAL RECORD COPY
Duke Power Company Oconee Nuclear Station cc:
Mr. Paul R. Newton Mr. Ed Burchfield Legal Department (PB05E)
Compliance Duke Power Company Duke Power Company 422 South Church Street Oconee Nuclear Site Charlotte, North Carolina 28242-0001 P. 0. Box 1439 Seneca, South Carolina 29679 J. Michael McGarry, III, Esquire Winston and Strawn Ms. Karen E. Long 1400 L Street, NW.
Assistant Attorney General Washington, DC 20005 North Carolina Department of Justice Mr. Robert B. Borsum P. 0. Box 629 Framatome Technologies Raleigh, North Carolina 27602 Suite 525 1700 Rockville Pike Mr. G. A. Copp Rockville, Maryland 20852-1631 Licensing -
ECO50 Duke Power Company Manager, LIS 526 South Church Street NUS Corporation Charlotte, North Carolina 28242-0001 2650 McCormick Drive, 3rd Floor Clearwater, Florida 34619-1035 Mr. Dayne H. Brown, Director Division of Radiation Protection Senior Resident Inspector North Carolina Department of U. S. Nuclear Regulatory Commission Environment, Health and Route 2, Box 610 Natural Resources Seneca, South Carolina 29678 P. 0. Box 27687 Raleigh, North Carolina 27611-7687 Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta Street, NW. Suite-2900 Atlanta, Georgia 30323 Max Batavia, Chief 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