ML17159A353
| ML17159A353 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 06/01/1998 |
| From: | Capra R NRC (Affiliation Not Assigned) |
| To: | Byram R PENNSYLVANIA POWER & LIGHT CO. |
| References | |
| TAC-M98736, TAC-M98737, NUDOCS 9806030446 | |
| Download: ML17159A353 (5) | |
Text
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Mr. Robert G. Byram Senior Vice President-Generation and Chief Nuclear Officer Pennsylvania Power and Ught Company 2 North Ninth Street Allentown, PA 18101 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&0001 3une 1,
1998
Dear Mr. Byram:
By letter dated November 13, 1995, PP8L (the licensee) submitted an inspection relief request (Relief Request RR-12) for NRC approval.
PP8L's relief request (RR-12) proposed to inspect the IGSCC Category C welds in accordance with the scope and frequency of IGSCC Category B welds. The NRC denied PP8L's relief request RR-12 in a letter dated June 24, 1996.
By letter dated March 21, 1997, PP8L provided a response to NRC's denial and requested NRC to reevaluate its relief request RR-12.
In accordance with Generic Letter (GL) 88-01, IGSCC Category C welds are welds made of non-resistant stainless steel materials and were stress improved after 2 years of operation.
All IGSCC Category C welds are required to be ultrasonically inspected (UT) within the next two fuel cycles after the stress improvement application followed by 100% inspection every 10 years.
IGSCC Category B welds are welds made of non-resistant stainless steel material and were stress-improved within 2 years of operation.
For IGSCC Category B welds, UT is required for 50% of the welds every 10 years.
The main reason for inspecting Category C welds more frequently than Category B welds is that cracks could be initiated in the susceptible welds after 2 years of plant operation.
There are 32 IGSCC Category C welds on Unit 1 and 31 such welds on Unit 2. The licensee stated that these'welds were treated by a mechanicai stress improvement process (MSIP) during the last two refueling outages (7th and 8th refueling outages on Unit 1 and 6th and 7th refueling outages on Unit 2). Therefore, both Units 1 and 2 have been operated on an average of more than 10 years when the MSIP was applied. To qualify for IGSCC Category B inspection schedule, the welds must be stressed-improved within 2 years of plant operation.
The bases of the staff's denial of the licensee's relief request were discussed in the staffs safety evaluation dated June 24, 1996. The bases were summarized befow:
(1)
The IGSCC is a time-dependent process.
It is not prudent to decrease the inspection scope or increase the interval between inspections as plants age, (2)
In view of the recent finding of deep axial cracks at several stress-improved welds, the staff has concerns regarding the ability in detecting the axial cracks by Ultrasonic testing (UT) and the effectiveness of the subject mitigation technique in arresting the axial cracks.
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SUBJECT:
REEVALUATIONOF PENNSYLVANIAPOWER AND LIGHTCOMPANY'S (PP&L)
INSPECTION RELIEF REQUEST OF INTERGRANULARSTRESS-CORROSION CRACKING (IGSCC) CATEGORY C WELDS'USQUEHANNASTEAM ELECTRIC STAT(ON, UNITS 1 AND2 (TAC NOS. M98736 AND M98737)
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R. Byram (3)
The staff has concerns regarding the lack of test data such as the residual stress measurements and the stress corrosion testing to verifythe effectiveness of the process MSIP control parameters and regarding the potential of a relaxation of compressive residual stresses as a result of operating loads as well as the anticipated and unanticipated transient loads.
(4)
Since the MSIP process was accepted by NRC in 1988 as an effective process to mitigate IGSCC, the service experience of those MSIP treated welds is limited. It is not conservative to reduce the inspection frequency based on a limited service experience.
(5)
The staff suggested that the licensee could achieve a significant saving of the total personnel radiation exposure in performing the subject UT inspection by implementing measures such as chemical decontamination, removal of hot spots, hydrogen water chemistry, installation of effective shielding, integrated service inspection program and performing automatic UT inspection.,
The staff has reviewed the licensee's response and finds that it does not provide any new significant information. The staff has determined that the licensee has not provided adequate justification to support its inspection relief request., Therefore, the licensee's relief request RR-12 for Susquehanna, Units 1 and 2, is denied.
Ifthe industry desires a generic inspection relief from GL 88-01, it would be more desirable to have the Boiling Water Reactor Owners Group initiate such a proposal.
'incerely,
/s/
'.,'obert A. Capra, Director Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket Nos. 50-387 and 50-388 cc: See next page
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R. Byram (3)
The staff has concerns regarding the lack oftest data such as the residual stress measurements and the stress corrosion testing to verifythe effectiveness of the process MSIP control parameters and regarding the potential of a relaxation of compressive residual stresses as a result of operating loads as well as the anticipated and unanticipated transient loads.
(4)
(5)
Since the MSIP process was accepted by NRC in 1988 as an effective process to mitigate IGSCC, the service experience of those MSIP treated welds is limited. It is not conservative to reduce the inspection frequency based on a limited service experience.
The staff suggested that the licensee could achieve a significant saving of the total personnel radiation exposure in performing the subject UT inspection by implementing measures such as chemical decontamination, removal of hot spots, hydrogen water chemistry, installation of effective shielding, integrated service inspection program and performing automatic UT inspection.
The staff has reviewed the licensee's response and finds that it does not provide any new significant information. The staff has determined that the licensee has not provided adequate justification to support its inspection relief request.
Therefore, the licensee's relief request RR-12 for Susquehanna, Units 1 and 2, is denied.
Ifthe industry desires a generic inspection relief from GL 88-01, it would be more desirable to have the Boiling Water Reactor Owners Group initiate such a proposal.
Sincerely, Docket Nos. 50-387 and 50-388 cc: See next page Q.-g~
Robert A. Capra, Director Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
v Mr. Robert G. Byram Pennsylvania Power & Light Company Susquehanna Steam Electric Station, Units 1 &2 CC:
Jay Silberg, Esq, Shaw, Pittman, Potts &Trowbridge 2300 N Street N.W.
Washington, D.C. 20037 Bryan A. Snapp, Esq.
Assistant Corporate Counsel Pennsylvania Power & Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 General Manager Susquehanna Steam Electric Station Pennsylvania Power and Light Company Box 467 Beiwick, Pennsylvania 18603 Licensing Group Supervisor Pennsylvania Power & Light Company 2 North Ninth Street Allentown, Pennsylvania'8I01 Senior Resident Inspector U. S. Nuclear Regulatory Commission P.O. Box 35 Berwick, Pennsylvania 18603-0035 Director-Bureau of Radiation Protection Pennsylvania Department of Environmental Resources P. O. Box 8469 Harrisburg, Pennsylvania 171 05-8469 Mr. Jesse C. Tilton, III Allegheny Elec. Cooperative, Inc.
212 Locust Street P.O. Box 1266 Harrisburg, Pennsylvania 17108-1266 Mr. Herbert D. Woodeshick Special Office of the President Pennsylvania Power and Light Company Rural Route 1, Box 1797 Berwick, Pennsylvania 18603 George T. Jones Vice President-Nuclear Operations Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Dr. Judith Johnsrud National Energy Committee Sierra Club 433 Orlando Avenue State College, PA 16803 Chairman Board of Supervisors 738 East Third Street Berwick, PA 18603