ML102390406
| ML102390406 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/01/2010 |
| From: | Nancy Salgado Plant Licensing Branch 1 |
| To: | Belcher S Nine Mile Point |
| References | |
| TAC ME2812 | |
| Download: ML102390406 (7) | |
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- i' Mr. Samuel L. Belcher Vice President Nine lVIile Point Nine Mile Point Nuclear Station, LLC P.O. Box 63 Lycoming, NY 13093 SUB-JECr:
NINE MILE POINT NUCLEAR STATION, UNIT NO.1 RE: THIRD 10-YEAR INSERVICE INSPECTION (lSI) INTERVAL - RELIEF REQUEST NO. ISI-25 (TAC NO. ME2812)
Dear Mr. Belcher:
By letter dated November 24,2009, as supplemented on April 29,2010, Nine Mile Point Nuclear Station, LLC (NMPNS, the licensee), submitted Relief Request (RR) ISI-25, Revision 00, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii) for Nine Mile Point, Unit NO.1 (NIVIP1), requesting relief from certain lSI requirements in Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for Class 1, Category R-A piping welds that are part of the licensee's risk informed program. The request proposes relief from the requirement of ASME Code Case N-578-1, Table 1, Examination Category R-A, Item Nos. R1.11 and R1.20, to perform essentially 100 percent volumetric examination of the weld and adjacent base material. The subject relief request is for the third 1O-year lSI Interval Program at NMP1 which began on December 26, 1999, and ended on August 22, 2009.
The Nuclear Regulatory Commission (NRC) staff has reviewed the subject request, and concludes that the ASME Code examination coverage requirements are impractical for the subject welds listed in the RR ISI-25, Revision 01, and pursuant to 10 CFR 50.55a(g)(6)(i),
relief is granted for the third 10-year lSI interval at NMP1. The results of the NRC staff's review are provided in the enclosed safety evaluation.
If you have any questions regarding this approval, please contact Richard Guzman, at 301-415-1030 or Richard.Guzman@nrc.gov.
Sincerely, Nancy L. Salgado, Chief Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-220
Enclosure:
As stated cc w/encl: Distribution via Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST ISI-25 NINE MILE POINT NUCLEAR STATION, LLC NINE MILE POINT NUCLEAR STATION, UNIT NO.1 DOCKET NO. 50-220
1.0 INTRODUCTION
By letter dated November 24, 2009 (Agencywide Document Access and Management System (ADAMS) Accession Number ML093350523), as supplemented by letter dated April 29,2010 (ADAMS Accession No. ML101270023) Nine Mile Point Nuclear Station, LLC (NMPNS, the licensee) submitted Relief Request (RR) ISI-25, Revision 00, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii) for Nine Mile Point, Unit NO.1 (NMP1),
requesting relief from certain inservice inspection (lSI) requirements in Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for Class 1, Category R-A piping welds that are part of the licensee's risk-informed program. The request proposes relief from the requirement of ASME Code Case N-578-1, Table 1, Examination Category R-A, Item Nos. R1.11 and R1.20, to perform essentially 100 percent volumetric examination of the weld and adjacent base material. The subject relief request is for the third 1O-year lSI Interval Program at NIV1P1 which began on December 26, 1999, and ended on August 22, 2009.
2.0 REGULATORY EVALUATION
The Nuclear Regulatory Commission (NRC) regulations in 10 CFR 50.55a(g) specify that the lSI of nuclear power plant components shall be performed in accordance with the requirements of ASIV1E Code,Section XI.
Pursuant to 10 CFR 50.55a(g)(5)(iii), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is impractical for its facility, the licensee shall notify the Commission and submit information to support the determination. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose alternative 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.
The regulations require that inservice examination of components and system pressure tests conducted during the first 1O-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 Enclosure
- 2 the limitations and modifications listed therein. The Code of record for the third 1O-year lSI interval at NMP1 was the 1989 Edition with no Addenda of the ASME Code,Section XI.
3.0 TECHNICAL EVALUATION
3.1
Applicable Code Edition and Addenda
The Code of record for the third 1O-year lSI program at NMP-1 was the 1989 Edition with no Addenda of the ASME Code,Section XI.
3.2
Applicable Code Requirement
The examination requirements for the subject piping welds at NMP1 are governed by a Risk Informed Inservice Inspection (RI-ISI) program that was developed in accordance with Electric Power Research Institute (EPRI) Topical Report (TR)-112657, Rev. B-A, "Revised Risk Informed Inservice Inspection Evaluation Procedure." As part of the NRC-approved program, the licensee has implemented the inspection requirements listed in ASME Code Case N-578-1, "Risk-Informed Requirements for Class 1,2, and 3 Piping, Method B." ASME Code Case N-578-1, Table 1, Examination Category R-A, Item Number R1.11, piping inspection elements subject to thermal fatigue and Item Number R1.20, piping inspection elements not subject to a damage mechanism, require volumetric examination of 100 percent of the weld.
3.3 Components for Which Relief is Requested Code Class:
Class 1 Examination Category:
R-A Component 10 Component Description OM Risk Cat/Item Number
% of Coverage Achieved Description of Limitation 39-WD-470 Valve -to-Pipe TASCS 2/R1.11 48%
One side exam due to valve-to-pipe configuration 39-WD-471 Pipe-to-Valve TASCS 2/R1.11 48%
One side exam due to valve-to-pipe configuration 33-WD-055 Tee-Reducer TASCS 2/R1.11 61.7%
One side exam due to T-box configuration 32-WD-017 Pump-to-Elbow None 4/R1.20 50%
One side exam due to pump-to-elbow configuration 32-WD-002 Nozzle-to-Safe End None 4/R1.20 62.5%
Surface profile inadequate due to radial shrinkage 32-WD-045 Nozzle-to-Safe End None 4/R1.20 62.5%
Surface profile inadequate due to radial shrinkaoe 32-WD-171 Pipe-to-Tee None 4/R1.20 50%
One side exam due to pipe-to-tee confiquration
- 3 3.4 Licensee Basis for Relief:
The licensee stated that during the initial alternate RI-ISI element selection process, accessibility was an important consideration, and as such, locations were initially selected for examination where the desired coverage was determined to be achievable. However, the limitations identified in their request were not known until the examinations were performed, and in many cases were being examined for the first time under the alternate RI-ISI program requirements.
The licensee states that the RI-ISI examinations were performed in accordance with ASME Code,Section XI, Appendix VIII (1995 Edition through the 1996 Addenda), as administered by the EPRI Performance Demonstration Initiative (PDI). Examinations were conducted utilizing new PDI procedures, techniques and equipment (such as UT search units) specifically identified and selected during the procedure qualification process to interrogate, detect, and size flaw indications associated with specific degradation mechanisms.
The licensee states that other considerations contributed to the selection of locations where greater than 90 percent coverage is physically impossible, especially for element selections in Risk Category 2 where the elements are selected for examination on the basis of predicted degradation severity. These locations will generally be selected for examination since they are considered more susceptible locations. Usually, less than 90 percent coverage of these locations will yield more valuable information than 100 percent coverage of a less susceptible location. For Risk Category 4, a greater degree of flexibility exists in choosing inspection locations. Normally, when an element selection is found to be obstructed, a more suitable location will be chosen. Substitutions, additions and/or deletions are made following the re-evaluation as required by the living program criteria at the end of each inspection period and at the end of the 1O-year inspection interval.
The licensee states that 10 CFR 50.55a(b)(2)(xv)(A)(2) requires that when examination from both sides is not possible on austenitic welds, full coverage from a single side may be claimed only after completing a successful single-sided Appendix VIII demonstration using flaws on the opposite side of the weld. Since the industry has not qualified single-sided examinations, NMP1 does not claim Code coverage on the far side of the weld. Therefore, the maximum Code coverage that may be claimed is 50 percent (applied to welds 32-WD-017, 32-WD-171, 39-WD-470, and 39-WD-471).
The licensee states that a risk assessment was performed and it was concluded that there is no impact on meeting the risk impact assessment acceptance criteria. The licensee further states that a re-evaluation will be performed following the end of the inspection interval (August 22, 2009). Based on the results of the re-evaluation, where alternate element selections would achieve greater than 90 percent coverage, substitutions for the elements with identified limited examination coverage will be made to the extent practical.
3.5 Licensee's Proposed Alternative Examination In lieu of the ASME Code-required essentially 100 percent (Le., greater than 90 percent) volumetric examination, NMP1 proposes an ultrasonic examination of accessible areas to the maximum extent practical, given the component design configuration of the aforementioned welds.
- 4 3.6 Duration of Proposed Alternative The proposed alternative is requested for the third 1O-year lSI interval for NMP1 which began on December 26, 1999, and ended on August 22, 2009.
3.7
NRC Staff Evaluation
The examination requirements for the subject piping welds at NMP1 are governed by an RI-ISI program that was approved by the NRC in a safety evaluation report dated February 22, 2002 (ADAMS Accession No. ML020720417). This program assigns Examination Category R-A, Item R1.11 to piping elements subject to thermal fatigue and Item R1.20 to piping elements not subject to a damage mechanism, and requires inspection of 100 percent of the examination volume for Class 1 circumferential piping welds. However, the subject piping weld configurations and base materials limit volumetric examinations. In order to meet the RI-ISI program volumetric coverage requirements, these components would have to be re-designed and modified. Therefore, 100 percent volumetric examination is considered impractical for the subject piping welds.
The licensee has determined that certain NNlP1 welds had ultrasonic examination coverage limitations of less than 100 percent of the ASME Code-required weld and adjacent material volume(s). The limitations encountered during the performance of the ultrasonic examinations on the subject welds were caused by component configurations (see table on Page 2). These configurations severely limit volumetric examinations and result in access typically to only a single side of the weld. As shown on the sketches and technical descriptions included in the licensee's submittal dated November 24, 2009, examinations of the subject piping welds have been completed to the extent practical resulting in an aggregate volumetric coverage ranging from 48 percent to 62.5 percent of the ASME Code required volume.
Ultrasonic equipment, procedures, and personnel qualified through the industry's PDI Program were employed. Examinations included 45-and 70-degree shear wave and 60-degree refracted longitudinal wave techniques, as applicable, from the accessible sides of these welds. For weld numbers 32-WD-002 and 32-WD-045, the required volume was examined with 100 percent coverage achieved for the detection of circumferentially oriented flaws, with scans performed from both sides of the weld. Only 25 percent coverage was achieved for the detection of axially oriented flaws due to radial shrinkage, with scans performed on the safe end side of the weld only, resulting in 62.5 percent coverage. All other welds were limited by configurations that allowed for single-side examination only.
The NRC staff has reviewed this request and found that the licensee demonstrated the impracticality to meet the ASME Code-required 100 percent volumetric examination coverage for the subject piping welds due to their design and ultrasonic access restrictions. Although the ASME Code-required coverage could not be obtained, the ultrasonic methods employed would have provided full volumetric coverage for the near-side of the welds and limited volumetric coverage for the weld fusion zone and base materials on the opposite side of the welds. Based on the aggregate coverage obtained for the subject welds, and considering the licensee's performance of ultrasonic techniques used to maximize this coverage, the NRC staff concludes that, if significant service-induced degradation were occurring, there is reasonable assurance that evidence of it would have been detected by the examinations that were performed.
- 5
4.0 CONCLUSION
The NRC staff has reviewed the licensee's submittal and concludes that the ASME Code examination coverage requirements are impractical for the subject welds listed in the RR ISI-25, Revision 01. Further, based on the volumetric coverage obtained, it is concluded that, if significant service-induced degradation were occurring, there is reasonable assurance that evidence of it would have been detected by the examinations that were performed. Therefore, for the items in RR ISI-25, Revision 01 relief is granted, pursuant to 10 CFR 50.55a(g)(6)(i), for the third 1O-year lSI interval at the NMP1.
The NRC staff has determined that granting relief for RR ISI-25, Revision 01, pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject request for relief remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: M. Audrain, NRR Date: Septem.ber 1, 2010
September 1, 2010 Mr. Samuel L. Belcher Vice President Nine Mile Point Nine Mile Point Nuclear Station, LLC P.O. Box 63 Lycoming, NY 13093
SUBJECT:
NINE MILE POINT NUCLEAR STATION, UNIT NO.1 RE: THIRD 10-YEAR INSERVICE INSPECTION (lSI) INTERVAL - RELIEF REQUEST NO. ISI-25 (TAC NO. ME2812)
Dear Mr. Belcher:
By letter dated November 24, 2009, as supplemented on April 29, 2010, Nine Mile Point Nuclear Station, LLC (NMPNS, the licensee), submitted Relief Request (RR) ISI-25, Revision 00, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii) for Nine Mile Point, Unit NO.1 (NMP1), requesting relief from certain lSI requirements in Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) for Class 1, Category R-A piping welds that are part of the licensee's risk informed program. The request proposes relief from the requirement of ASME Code Case N-578-1, Table 1, Examination Category R-A, Item Nos. R1.11 and R1.20, to perform essentially 100 percent volumetric examination of the weld and adjacent base material. The subject relief request is for the third 1O-year lSI Interval Program at NMP1 which began on December 26, 1999, and ended on August 22, 2009.
The Nuclear Regulatory Commission (NRC) staff has reviewed the subject request, and concludes that the ASME Code examination coverage requirements are impractical for the subject welds listed in the RR ISI-25, Revision 01, and pursuant to 10 CFR 50.55a(g)(6)(i),
relief is granted for the third 1O-year lSI interval at NMP1. The results of the NRC staff's review are provided in the enclosed safety evaluation.
If you have any questions regarding this approval, please contact Richard Guzman, at 301-415-1030 or Richard.Guzman@nrc.qov.
Sincerely, IRA!
Nancy L. Salgado, Chief Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-220
Enclosure:
As stated cc w/encl: Distribution via Listserv DISTRIBUTION:
PUBLIC RidsNrrPMRGuzman RidsNrrLASUttle RidsNrrDciCpnb LPLI-1 R/F M. Audrain, NRR RidsOGCRp RidsRgn1MailCenter Ridsl'JrrAcrsAcnw&mMailCenter Accession Number: ML102390406
- SE Input and concurrence via e-mail. No substantial changes made.
OFFICE LPL1-1/PM LPL1-1/LA CPNB/BC LPL1-1/BC NAME RGuzman SUttle TLuphold*
NSalgado DATE 8/30/10 8/30/10 08/23/10 9/01/10 OFFICIAL RECORD COpy