ML20211F880
| ML20211F880 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 09/22/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20211F876 | List: |
| References | |
| NUDOCS 9710010259 | |
| Download: ML20211F880 (7) | |
Text
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g UNITED STATES
-r NUCLEAR REGULATORY COMMISSION l
WASHINGTON, D.C. 30006-0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
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OF THE SECOND 10-YEAR INTERVAL INSERVICE INS *ECTION PROGRAM PLAN AND ASSOCIATED REQUESTS FOR RELIEF I
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l DUKE ENERGY CORPORATION i
l' CATAWBA NUCLEAR STATION. UMLT_1 DOCKET NO. 50413 L
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1.0 INTRODUCTION
i The Technical Specifications (TS) for Catawba Nuclear Station, Unit 1, state that the inservice inspection of the American Society of Mechanical Engineers (ASME) Code Class 1,
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2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler j
and Pressure Vessel Code (ASME Code) and applicable addenda as required by Title 10 of
- the Code of Federal Reaulations (10 CFR) Section 50.55a(g), except where specific written i
relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).
i Section 50.55a(a)(3) states that altamatives to the requirements of paragraph (g) may be j
used, when authorized by the NRC, if (i) the proposed attematives would provide an l _
acceptable level of quality and safety or (ii) compliance with the specified requirements would j
result in hardship or unusual difficulties without a compensating increase in the level of -
quality and safety.
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- Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including
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supports) shall meet the requirements, except the design and access provisions and the pre-i-
service examination requirements, set forth in the ASME Code,Section XI, " Rules for
. inservice inspection of Nuclear Power Plant Components," to the extent practical within the i
limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests i
conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50 55a(b) 12 months prior to the start of the 120-month interval,
. subject to the limitations and modifications listed therein. The applicable edition of Section XI i
of the ASME Code for the Catawba Nuclear Station, Unit 1, second 10-year Inservice.
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inspection (ISI) interval is the 1989 Edition.
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' Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an
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examination requirement of Section XI of the ASME Code is not practical for its facility, j
information shall be submitted to the Commission in support of that determination and a i
request made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(l), the Commission may grant relief and may i
9710010259 970922 PDR-ADOCK 05000413 G
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[ impose altomative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
In a letter dated December 12,1996 Duke Power Company (licensee, currently named Duke Energy Corporation), submitted to the NRC its Second 10-Year Inservice Inspection interval Program Plan Request for Relief 96-04 for Catawba Nuclear Station, Unit 1.- As a result of the staffs request for additionalinformation dated March 7,1997, the licenses provided moditional information in its letter dated May 5,1997.
2.0 EVALUATION The staff, with technical assistance from its contractor, the Idaho National Engineering and Environmental Laboratory (INEEL), has evaluated the information provided by the licensee in support of its Second 10-Year Inservice Inspection Interval Program Plan Request for Relief l
96-04 for Catawba Nuclear Station, Unit 1. Based on the information submitted, the staff-adopts the contractor's conclusions and recommendations presented in the attached Technical Letter Report (TLR), which is hereby made a part of this safety evaluation.
Request for Relief 96 04, Revision 1: ASME Section XI, Examination Category B-J,- Item B09.011, Safety injection System Circumferential Piping Welds requires 100% sudace and volumetric examination, as defined by Figure IWB-2500-8, for Class 1 circumferential welds 4-inch nominal pipe size or larger.
Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee has requested relief from the Code coverage requirements for the Safety injection System welds listed in the table below.
@ ltem NoMfp 9 WaldID$# 99MhumstationW# MAm a Coverage :
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B09.011.163 1N1148-10 Geometric configuration -
59.85 %
B09.011.164 1N1148-11 Georaetric configuration 61 %
The Code requires 100% volumetric examination of the subject safety injection welds.
However, complete examination is restricted by geometric configuration which makes the 100% volumetric examination impractical to perform for these welds. To gain access for examination, the welds and connected components would require design modification.
imposition of this requirement would create an undue burden on the licensee.
The licensee completed the Code-required surface examinations and has performed the.
Code-required volumetric examinations to the extent practical. The coverage obtained for the volumetric examination was approximately 60% for each weld, in addition, these welds are part of a large sample of Class 1 welds that are receiving volumetric examination to the extent required by the Code. Therefore, any existing pattems of degradation would have been detected by the examinations that were completed and reasonable assurance of structural integrity has been provided.
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As part of the proposed attemative, the licensee stated that they will ' continue to use their i
Appendix Vill qualified ultrasonic _ examination procedures for detection of far side flaws, when examining through mustenitic weld metal." The use of Appendix Vill for Catawba Nuclear
__ Station, as well as the McGuire and Oconee stations, was previously evaluated and authorized (letter, H. N. Berkow of NRC to M. S. Tuckman, dated September 12,1995). However,' one-sided volumetric examinat.on is not a conservative approach and should not be considered acceptable when access to both sides of the weld is available. During a June 6,1997, conference call, the licensee confirmed that one sided examinations are only performed when two-sided examinations are impractical. Since access to both sides of the weld is impractical for the subject welds, the licensee's approach to the volumetric examination for these welds is technically sound.
- Based on the impracticality of meeting the Code coverage requirements for the subject welds,-
i and the reasonable assurance provided by the examinations that were completed on these and j
other welds, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i).
3.0 CONCLUSION
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The staff has reviewed the licensee's submittal and concludes that the Code coverage requirements are impractical for the subject Safety injection System welds at Catawba Nuclear
. Station, Unit 1, and that reasonable assurance of the structuralintegrity has been provided by the examinations that were completed. Therefore, relief is granted pursuant to 10 CFR 4
50.55a(g)(6)(l). The granting of this relief will not endanger life, property, or the common defense and security, and is otherwise in the public interest, giving due consideration to the -
burden upon the licensee that could result if the requirements were imposed on the facility, j
Attachment:
INEEL Technical Evaluation Report I:
Principal Contributor:
T. K. McLellan i
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M. T. Ander*nm !NEEL -
L A. M. Porter, INEEL
- Date:
-September 22, 1997 J
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l TECHNICAL LETTER REPORT ON THE SECOND 10. YEAR INTERVAL INSERVICE INSPECTION 4
REQUEST FOR RELIEF 96 04. REVISION 1 DUKE POWER COMPANY CATAWBA NUCiRAR STATION UNIT 1 i
DOCKET NUMBER 50 413 l'
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1.0 INTRODUCTION
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By letter dated December 12,1996, the licensee, Duke Power Company, requested
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relief from the coverage requirements of the Code for two Class 1 circumferential i
j piping welds. In response to a Nuclear Regulatory Commission (NRC) request for additional information, the licensee submitted Request for Relief 96 04, Revision 1 in a letter dated May 5,1997. A conference call was held with the licensee on e
j June 2,1997, to obtain further clarification regarding the submittals. The Idaho National Engineering and Environmental Laboratory (INEEL) staff has evaluated the l
'information provided by the licensee in support of this request for relief in the following section.
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i 2.0 EVALUATION 4
I The Code of record for the Catawba,' Unit 1, second 10-year inservice inspection (ISI)intervalis the 1989 Edition of Section XI of the American Society of
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Mechanical Engineers (ASME) Boiler and Pressure Vessel Code.
l Reauest for Relief 96-04. Revision 1. Framination Catenorv B-J. Item B9.11. Safety i'
iniection System Circumferential Pinina Walds i
Code Reauirement: ASME Section XI, Examination Category B J, item B9.11, j-requires 100% surface and volumetric examination, as defined by Figure IWB-2500-8, for Class 1 circumferential welds 4-inch nominal pipe size or larger.
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Attachment I
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Licensee's Code Relief Raouest: Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee
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has requested relief from the Code coverage requirements for the Saf3ty injection l
System welds listed in the tabic below.
j T@itemhoF 3MWeldllDP M8%MuiniMtiorifs3F W IC66erags?
B09.011.163 1NI14810 Geometric configuration 59.85 %
B09.011.164 1NI14811 Geometric configuration 61 %
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l Licensee's Basis for Renuestina Relief (as stated):
"During the ultrasonic examination of the welcs shown in Attachment 1, coverage -
I of the required examination volume as modified by Code Case N-460 could not be obtained. Causes of these limitations are single sided access due to pipe to-valve configuration and austenitic weld material. Where possible, a combination of angles and wave modes were used to maximize the coverage obtained. The weld and base metal at the component inside surface was covered from at least one
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' direction with a minimum of one angle. The examinations were performed in j
accordance with ASME Section XI, Appendix I and Appendix Vill,1992 Edition j
- with 1993 Addends as allowed by Request for Relief 95 GO-003, dated j
September 12,1995.
l Justification for the Granting of Rollef:
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e Although the examination volume requirements as defined in ASME Section XI, Figure IWB-2500-8, Examination Volume C-D E F could not be met, the amount of coverage obtained for these examinations provides an acceptable level of quality l
and integrity. The inside surface of the pipe, within the required examination 1
L volume,~ received 100% coverage in the axial direction. If a surface connected circumferential flaw had been present, it would have been detected. For results of examinations, reference Attachment 2', pages 6 of 9 and 9 of 9. The welds in l
question connect the first and second check valves off the reactor coolant system and are one of the four paths for ECCS injection. In the unlikely event of their
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failure fluid would leak from the Cold Leg Accumulator (CLA) to the containment building floor. A drop in level from an accumulator with a corresponding increase in i
' aump inputs would occur. An eventual alarm in the control room for CLA level would require action per Technical Specification 3/4.5.1. The limit on unidentified i.
leakage is 1 gpm from sump input and is monitored by OAC point alarms. The Technical Specification 3/4.6.2 would be enforced if the unidentified leakage went
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above 1 gpm. These alarms would indicate a problem and allow adequate response
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Attachments contained in the licensees's submittal are not included in
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this report.
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3 time before the current margin in injection flow (actual to test acceptance criteria) indicated by the ECCS flow balance testing is surpassed. Based on these evaluations, it is Duke Power Company's opinion that the limited coverage will not endanger the health and safety of the general public. Duke Power Company will perform UT examinations to the extent practical using procedures and personnel 2
qualified with ASME Section XI, Appendix Vill,1992 Edition with 1993 Addenda."
i Licensee's Pronosed Alternative (as stated):
"No additional examinations are planned during the current interval for Weld ID Numbers 1N1148-10 and 1N114811. The use of radiography as an alternate
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volumetric examination method for Weld ID Numbers 1N1148-10 and 1N114811 is not feasible due to component thickness, geometric configurations and restrictions from physical barriers which prohibit access for the placement of source, image quality indicators, film, etc. Duke Power Company will continue to use Appendix Vill qualified ultrasonic examination procedures for detection of far side flaws, when examining through austenitic weld metal."
Evaluation: The Code requires 100% volumetric examination of the subject safety injection welds. However, complete examination is restricted by geometric configuration which makes the 100% volumetric examination impractical to perform for these welds. To gain access for examination, the welds and connected i
components would require design modification. Imposition of this requirement would create an undue burden on the licensee.
The licensee completed the Code-required surface examinations and has performed the Code-required volumetric examir.ations to the extent practical. The coverage obtained for the volumetric examination was approximately 60% for each weld. In addition, these welds are part of a large sample of Class 1 welds that are receiving volumetric examination to the extent required by the Code. Therefore, bny existing patterns of degradation would have been detected by the examinations that were completed and reasonable assurance of structuralintegrity has been provided.
As part of the proposed alternative, the licenses stated that they will " continue to use their Appendix Vill qualified ultrasonic examination procedures for detection of far side flaws, when examining through austenitic weld metal." The use of Appendix Vill for Catawba Nuclear Station, as well as McGuire and Oconee Stations, was evaluated and authorized in an NRC Safety Evaluation Report dated f
4 September 11,1995. However, one-sided volumetric ' xamination is not a e
conservative approach and should not be considered acceptable when access to both sides of the weld is available. During a June 6,1997, conference call, the licensee confirmed that one sided examinations are only performed when two sided examinations are impractical. Since access to both sides of the weld is impractical for the subject welds, the licensee's approach to the volumetric examination for these welds is technically sound.
Based on the impracticality of meeting the Code coverage requirements for the subject welds, and the reasonable assurance provided by the examinations that were completed on these and other welds, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
3.0 CONCLUSION
The INEEL staff has reviewed the licensee's submittal and concludes that the Code coverage requirements are impractical for subject safety injection welds at Catawba Nuclear Station, Unit 1 and that reasonable assurance of the structural integrity has been provided by the examinations that were completed. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
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