ML13260A493
| ML13260A493 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 11/29/2013 |
| From: | Jessie Quichocho Plant Licensing Branch II |
| To: | Nazar M Florida Power & Light Co |
| Klett A DORL/LPLII-2 301-415-1447 | |
| References | |
| TAC MF0086, TAC MF0087 | |
| Download: ML13260A493 (7) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Mano Nazar Executive Vice President and Chief Nuclear Officer Florida Power & Light Company P.O. Box 14000 Juno Beach, Florida 33408-0420 November 29, 2013
SUBJECT:
TURKEY POINT NUCLEAR GENERATING UNIT NOS. 3 AND 4-SAFETY EVALUATION FOR RELIEF REQUEST NUMBER 10- FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL TO USE ASME CODE, SECTION XI, APPENDIX VIII IN LIEU OF ASME CODE, SECTION V, ARTICLE 4 FOR INSPECTIONS OF WELDS 3-WR-18 AND 4-WR-18 (TAC NOS. MF0086 AND MF0087)
Dear Mr. Nazar:
By letter to the Nuclear Regulatory Commission (NRC or the Commission) dated November 13, 2012, Florida Power & Light Company (the licensee) submitted Relief Request No. 10 to use an alternative to certain requirements of the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code (Code),Section XI, Appendix I, Article l-2110(b)Section V, Article 4 inspections at Turkey Point Nuclear Generating Unit Nos. 3 and 4 (Turkey Point 3 and 4).
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.55a(a)(3)(i), the licensee requested to use the examination requirements in ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 as an alternative to the requirements in ASME Code,Section XI, Appendix I, Article 1-211 O(b) for inspections of the reactor pressure vessel upper shell-to-flange welds 3-WR-18 and 4-WR-18. Article 1-211 O(b) requires that ultrasonic examination of the reactor vessel-to-flange welds, closure head-to-flange welds, and integral attachment welds be conducted in accordance with Article 4 of Section V, except that alternative beam angles are used and that Table 1-2000-1 shall further supplement these examinations. The licensee requested to use an alternative that provides an acceptable level of quality and safety.
The NRC staff determined the use of procedures qualified to the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 to inspect the reactor pressure vessel upper shell-to-flange welds 3-WR-18 and 4-WR-18 provides an acceptable level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(i). Therefore, the NRC staff authorizes Relief Request No. 10 at Turkey Point 3 and 4 for the remainder of the fourth 1 0-year in service
inspection {lSI) intervals of Turkey Point 3 and 4, which are currently scheduled to end on February 21 and April14, 2014, respectively. The licensee may invoke the provision of the ASME Code,Section XI, paragraph IWA-2430, which allows the licensee to extend the fourth 1 0-year lSI intervals by 1 year. The licensee may perform the proposed alternative in the 1-year extension periods.
All other ASME Code,Section XI requirements for which the request was not specifically requested and approved remains applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
If you have any questions regarding this issue, please feel free to contact Ms. Audrey Klett at (301) 415-0489.
Sincerely, Docket No. 50-250 and 50-251
Enclosure:
Safety Evaluation cc w/enclosure: Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST NO. 10 FOR THE FOURTH 10-YEAR INSERVICE INSPECTION INTERVAL FLORIDA POWER & LIGHT COMPANY TURKEY POINT NUCLEAR GENERATING UNIT NOS. 3 AND 4 DOCKET NOS. 50-250 AND 50-251
1.0 INTRODUCTION
By letter to the Nuclear Regulatory Commission (NRC or the Commission) dated November 13, 2012 (Agencywide Documents Access & Management System Accession No. ML12340A070),
Florida Power & Light Company (the licensee) submitted Relief Request No. 10 to use an alternative to certain requirements of the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code (Code),Section XI, Appendix I, Article l-2110(b)Section V, Article 4 inspections at Turkey Point Nuclear Generating Unit Nos. 3 and 4 (Turkey Point 3 and 4).
Pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR), Part 50, Section 50.55a(a)(3)(i), the licensee requested to use the examination requirements in the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 as an alternative to the requirements in the ASME Code,Section XI, Appendix I, Article 1-211 O(b) for inspections of the reactor pressure vessel (RPV) upper shell-to-flange welds 3-WR-18 and 4-WR-18.
Article 1-211 O(b) requires that ultrasonic examination of the reactor vessel-to-flange welds, closure head-to-flange welds, and integral attachment welds be conducted in accordance with Article 4 of Section V, except that alternative beam angles are used and that Table 1-2000-1 shall further supplement these examinations. The licensee requested to use an alternative that provides an acceptable level of quality and safety.
The licensee requested to use the alternative for Turkey Point 3 and 4 until the end of the fourth 1 0-year inservice inspection (lSI) intervals. The Turkey Point 3 fourth 1 0-year lSI interval is currently scheduled to end on February 21, 2014, and the Turkey Point 4 fourth 1 0-year lSI interval is currently scheduled to end on April 14, 2014. However, the licensee may invoke the provision of the ASME Code,Section XI, paragraph IWA-2430, which allows the licensee to extend the fourth 1 0-year lSI intervals by 1 year. Extending the fourth 1 0-year lSI intervals would be necessary because the previous refueling outages were extended to install power uprate modifications.
Enclosure
2.0 REGULATORY EVALUATION
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee proposed the use of an alternative lSI for two RPV upper shell-to-flange welds at Turkey Point 3 and 4.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 1 0-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code, which was incorporated by reference in 1 0 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the conditions listed therein.
Section 50.55a(a)(3) states, in part, that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if the applicant demonstrates that: (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Based on the above regulatory requirements, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the Commission to authorize the use of an alternative requested by the licensee.
The Code of Record for the fourth 1 0-year lSI interval at Turkey Point 3 and 4 is the 1998 Edition of the ASME Code,Section XI with Addenda through 2000.
3.0 TECHNICAL EVALUATION
3.1 Licensee's Proposed Alternative The RPV upper shell-to-flange welds 3-WR-18 and 4-WR-18 are classified as ASME Code Class 1, Table IWB-2500-1, "Examination Categories, Pressure Retaining Welds in Reactor Vessel," Examination Category 8-A, Item No. 81.30, "Shell-to-Flange Weld." These welds require essentially 100 percent volumetric coverage. The ASME Code,Section XI, Paragraph IWA-2232 states, "Ultrasonic examinations shall be conducted in accordance with Appendix 1." Appendix I, Article 1-211 O(b), requires, "Ultrasonic examination of reactor vessel-to-flange welds, closure head-to-flange welds, and integral attachment welds shall be conducted in accordance with Article 4 of Section V, except that alternative beam angles may be used.
These examinations shall be further supplemented by Table 1-2000-1."
As an alternative to the requirements specified in the ASME Code,Section XI, Appendix I, Article 1-2000, paragraph 1-211 O(b), the licensee proposed to use procedures, personnel, and equipment qualified to the requirements of the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 of the ASME Code 1998 Edition with Addenda through 2000, as administered by the Electric Power Research Institute's (EPRI's) Performance Demonstration Initiative (POl) program to conduct the reactor vessel upper shell-to-flange weld examination.
The examinations from the inside surface would be implemented to achieve the maximum coverage possible using procedures and personnel qualified by the POl program. The licensee stated in its request that the proposed alternative would represent the best techniques, procedures, and qualifications available to perform ultrasonic testing (UT) examinations of RPV welds and that the POl program addresses qualification requirements for each of the supplements that are defined in the ASME Code,Section XI, Appendix VIII. The licensee stated in its request that the applicable vendor procedure has been qualified in accordance with POl program's implementation of Supplements 4 and 6 of the ASME Code,Section XI, Appendix VII I.
As the basis for the proposed alternative, the licensee stated the vessel-to-flange weld is the only circumferential weld that is not required to be examined in accordance with the techniques in the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6. The licensee stated in its request that the ASME Code,Section V, Article 4 calibration techniques, recording criteria, and flaw sizing methods are based on the use of a distance-amplitude-correction (OAC) curve derived from the ultrasonic responses to machined reflectors in a basic calibration block.
Reflectors detected in the field require investigation only if they exceed 20 percent of the amplitude response of the OAC curve obtained from the machined reflectors in the basic calibration block. Indications detected in the designated examination volume with amplitudes below this threshold are therefore not required to be recorded. The amplitude-based recording threshold is generic and does not take factors into consideration such as flaw orientation, which can influence the amplitude of the UT response. Use of the ASME Code,Section XI, Appendix VIII, qualified techniques enhance the quality of the examination. The detection criterion is more conservative because the qualified procedure requires examiners to measure and evaluate all indications determined to be flaws, regardless of their amplitude response, in accordance with the applicable criteria.
The licensee stated in its request that EPRI Report NP-6273, "Accuracy of Ultrasonic Flaw Sizing Techniques for Reactor Vessels," dated March 1989, contains a comparative analysis of sizing accuracy for several different techniques. The results show that the UT flaw sizing techniques based on tip diffraction are the most accurate. The ASME Code,Section XI, Appendix VIII-qualified detection and sizing methodologies use analysis tools based on echo dynamics and tip diffraction. This methodology is considered more sensitive and accurate than comparisons based only on amplitude.
3.2 NRC Staff's Evaluation The licensee proposed to use the examination requirements in the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 instead of those in the ASME Code,Section V, Article 4 for ultrasonic inspections of the RPV upper shell-to-flange welds 3-WR-18 and 4-WR-18. The NRC staff evaluated the proposed alternative examinations to determine if the use of the ASME Code,Section XI, Appendix VIII-qualified procedures has an acceptable level of quality and safety for the two welds.
Procedures developed in accordance with the ASME Code,Section V, Article 4 are not required to be qualified or performance-based. However, techniques in the ASME Code,Section XI Appendix VIII to qualify UT procedures and personnel are performance-based. This difference has resulted in an improvement in the effectiveness of lSI of nuclear power plant components.
Increasing the number of ASME Code,Section XI, Appendix VIII-qualified examinations would increase the effectiveness of lSI inspections. The NRC staff has supported the use of performance-based nondestructive examinations (NOEs) and continues monitoring, reviewing, and evaluating the adequacy of the transition to performance-based examinations and the appropriateness of selected performance-based criteria. The use of performance-based NDE methods provides confidence in the effectiveness and reliability of the examinations.
The NRC staff generally is concerned that when switching to Appendix VIII-qualified examinations, there is a possibility of reduction of inspection coverage. However, the licensee stated in its request that it expects to achieve 100 percent coverage with the ASME Code,Section XI, Appendix VIII-qualified procedure. The licensee also stated in its request that it will submit individual relief requests if it encounters limitations that preclude obtaining essentially 100 percent coverage.
The aforementioned evaluations, procedures, equipment, and personnel qualified to the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 have shown a high probability of flaw detection and have increased the reliability of examinations of welds configurations within the scope of the PDI program. Therefore, the NRC staff has determined that using inspections to the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 in lieu of the ASME Code,Section V, Article 4 for the RPV upper shell-to-flange welds 3-WR-18 and 4-WR-18 provides an acceptable level of quality and safety.
4.0 CONCLUSION
The NRC staff determined the use of procedures qualified to the requirements of the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 to inspect the RPV upper shell-to-flange welds 3-WR-18 and 4-WR-18 provides an acceptable level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(i). Therefore, the NRC staff authorizes Relief Request No. 10 at Turkey Point 3 and 4 for the remainder of the fourth 1 0-year lSI intervals of Turkey Point 3 and 4, which are currently scheduled to end on February 21 and April 14, 2014, respectively. However, the licensee may invoke the provision of the ASME Code,Section XI, paragraph IWA-2430, which allows the licensee to extend the fourth 10-year lSI intervals by 1 year. The licensee may perform the proposed alternative in the 1-year extension periods.
All other ASME Code,Section XI requirements for which the request was not specifically requested and approved remains applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
Principal Contributor: Stephen E. Cumblidge Date: November 29, 2013
inspection (lSI) intervals of Turkey Point 3 and 4, which are currently scheduled to end on February 21 and April14, 2014, respectively. The licensee may invoke the provision of the ASME Code,Section XI, paragraph IWA-2430, which allows the licensee to extend the fourth 1 0-year lSI intervals by 1 year. The licensee may perform the proposed alternative in the 1-year extension periods.
All other ASME Code,Section XI requirements for which the request was not specifically requested and approved remains applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
If you have any questions regarding this issue, please feel free to contact Ms. Audrey Klett at (301) 415-0489.
Sincerely, IRA/
Jessie F. Quichocho, Chief Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-250 and 50-251
Enclosure:
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