ML11202A009

St. Lucie Unit 2, Inservice Inspection Plan, Third Ten-Year Interval Unit 2 Relief Request No. 12

ML11202A009
Person / Time
Site:	Saint Lucie
Issue date:	07/13/2011
From:	Katzman E S Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2011-267
Download: ML11202A009 (5)

Text

0Florida Power & Light Company, 6501 S. Ocean Drive, Jensen Beach, FL 34957 L July 13, 2011 FPL L-2011-267 10 CFR 50.4 10 CFR 50.55a U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Unit 2 Docket No. 50-389 Inservice Inspection Plan Third Ten-Year Interval Unit 2 Relief Request No. 12 Pursuant to 10 CFR 50.55a(a)(3)(i), Florida Power & Light (FPL) requests relief from Code requirements for Ultrasonic (UT) examination of the Class I Reactor Pressure Vessel (RPV) Upper Shell-to-Flange Weld. As an alternative to the requirements specified in ASME Section XI, Appendix I, Article 1-2110(b), FPL proposes to use procedures, personnel, and equipment qualified to the requirements of ASME Section XI, Appendix VIII, Supplements 4 and 6 of the 1998 Edition with Addenda through 2000, as administered by the Electric Power Research Institute's (EPRI) PDI program to conduct the reactor vessel upper shell-to-flange weld examination.

The Third Inspection Interval Relief Request No. 12 is essentially the same as the previously approved in the NRC safety evaluations dated February 19, 2008, "Point Beach Nuclear Plant, Units 1 and 2 -The Fourth 10-Year Interval Inservice Inspection Program Plan Requests for Relief Nos. RR-18, RR-19, and RR-20 (TAC Nos. MD6346 and MD6347),"and dated April 7, 2009, "Seabrook Station, Unit No. 1, Relief Request for Reactor Pressure Vessel Shell to Flange Weld Examination for the Second Inspection Interval (TAC No. MD9784)." FPL requests approval of this relief request to support the upcoming Unit 2 SL2-20 Spring/ Summer 2012 refueling outage Please contact Ken Frehafer at (772) 467-7748 if there are any questions about this submittal.

Sincerely, Eric S. Katzman Licensing Manager St. Lucie Plant Attachment ESK/KWF an FPL Group company L-2011-267 Attachment 1 of 4 St. Lucie Unit 2 Third Inservice Inspection Interval Relief Request Number 12 Proposed Alternative In Accordance with 10 CFR 50.55a (a)(3)(i)--Alternative Provides Acceptable Level of Quality and Safety--"Alternative Ultrasonic Examination of the Reactor Pressure Vessel Upper Shell-to-Flange Weld using ASME Section XI, Appendix VIII Demonstrated Techniques" 1. ASME Code Component(s)

Affected Class 1 Reactor Pressure Vessel (RPV) Upper Shell-to-Flange Weld (Weld Number 101 -121) subject to Ultrasonic (UT) examination.

2. Applicable Code Edition and Addenda St. Lucie Unit 2 is currently in the 3rd 10-year Inservice Inspection (ISI) interval.The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) of record for the current 10-year ISI interval isSection XI, is 1998 Edition with Addenda through 2000.3. Applicable Code Requirement ASME Code Class 1, Table IWB-2500-1, "Pressure Retaining in Reactor Vessel," Examination Category B-A, Item Number B1.30, "Shell-to-Flange Weld". ASME Section XI, Paragraph IWA-2232 states, "Ultrasonic examinations shall be conducted in accordance with Appendix I." Appendix I, Article 1-2110(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 1-2000-1.4. Reason for Request FPL is performing volumetric examinations of all Reactor Pressure Vessel (RPV)welds during the upcoming 10-year Inservice Inspection (ISI). FPL is required to perform the 10-year RPV ISI pursuant to 10CFR50.55a.

The Code requires that Ultrasonic (UT) examination of RPV welds, excluding the reactor vessel upper shell-to-flange weld, shall be with techniques that have been demonstrated in accordance with ASME Section XI, Appendix VIII.Examination from the inside surface provides the best access for examination of the reactor vessel upper shell-to-flange weld. The outside surface of the RPV is inaccessible due to its' placement inside the biological-shield wall and the installed insulation.

Although the reactor vessel upper shell-to-flange weld is specifically excluded from the requirement to utilize ASME Section Xl, Appendix VIII qualified UT techniques L-2011-267 Attachment 2 of 4 St. Lucie Unit 2 Third Inservice Inspection Interval Relief Request Number 12 by the referenced Code, FPL believes that performing the UT examination with Appendix VIII/PDI qualified personnel and procedures from the inside surface will provide an acceptable level of quality and safety.5. Proposed Alternative and Basis for Use Proposed Alternative:

As an alternative to the requirements specified in ASME Section XI, Appendix I, Article 1-2110(b), FPL proposes to use procedures, personnel, and equipment qualified to the requirements of ASME Section XI, Appendix VIII, Supplements 4 and 6 of the 1998 Edition with Addenda through 2000, as administered by the Electric Power Research Institute's (EPRI) PDI program to conduct the reactor vessel upper shell-to-flange weld examination.

The examinations from the inside surface will be implemented to achieve the maximum coverage possible utilizing procedures and personnel qualified by the PDI program. The proposed alternative represents the best techniques, procedures, and qualifications available to perform UT examinations of RPV welds. The PDI program addresses qualification requirements for each of the supplements that are defined in ASME Section Xl, Appendix VIII. The applicable vendor procedure has been qualified in accordance with PDI's implementation of Supplements 4 and 6 of ASME Section Xl, Appendix VIII.Basis for Use The listed weld is the only circumferential shell weld in the reactor vessel that is not examined with ASME Section XI, Appendix VIII techniques, as mandated by 10CFR50.55a.

10CFR50.55a mandates the use of ASME Section XI, Appendix VIII, Supplements 4 and 6 for the conduct of all other reactor vessel weld examinations.

ASME Section XI, Appendix I, Article 1-2110(b) identifies that ASME Section V, Article 4 techniques be utilized for the examination of the reactor vessel-to-flange weld. The calibration techniques, recording criteria, and flaw sizing methods are based upon the use of a distance-amplitude-correction (DAC) 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% of the amplitude response of the DAC 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 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.

L-2011-267 Attachment 3 of 4 St. Lucie Unit 2 Third Inservice Inspection Interval Relief Request Number 12 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 upon tip diffraction are the most accurate.

ASME Section XI, Appendix VIII qualified detection and sizing methodologies use analysis tools based upon echo dynamics and tip diffraction.

This methodology is considered more sensitive and accurate than amplitude only based comparisons.

For the RPV upper shell-to-flange weld examinations using ASME Section XI, Appendix VIII, qualified techniques, FPL anticipates obtaining essentially 100%code volume coverage.

However, if limitations are encountered that preclude obtaining essentially 100% examination coverage of the required volume, individual relief requests will be submitted.

Procedures, equipment, and personnel qualified via the PDI Appendix VIII, Supplement 4 and 6 programs have been demonstrated to have a high probability of detection and are generally considered superior to the techniques employed during previous ASME Section V, Article 4, reactor vessel weld examinations.

Accordingly, approval of this alternative examination and evaluation process is requested pursuant to 1OCFR50.55a (a)(3)(i).

6. Duration of Proposed Alternative FPL will implement the proposed alternative Ultrasonic examination of the reactor vessel upper shell-to-flange weld using PDI Demonstrated Techniques during the St. Lucie Unit 2 Third Inservice Inspection Interval.7. Precedents Similar Relief Requests have been granted to the following plants: NRC Safety Evaluation dated February 19, 2008, "Point Beach Nuclear Plant, Units 1 and 2 -The Fourth 10-Year Interval Inservice Inspection Program Plan Requests for Relief Nos. RR-18, RR-19, and RR-20 (TAC Nos. MD6346 and MD6347)." NRC Safety Evaluation dated April 7, 2009, "Seabrook Station, Unit No.1, Relief Request for Reactor Pressure Vessel Shell to Flange Weld Examination for the Second Inspection Interval (TAC No. MD9784)." 8. Attachments to Relief Request 12 Illustration of reactor vessel upper shell-to-flange weld L-2011-267 Attachment 4 of 4 St. Lucie Unit 2 Third Inservice Inspection Interval Relief Request Number 12 Illustration of Reactor Vessel Upper Shell-to-Flange Weld.00 METAL/KEYWAY LOCATIONS AT 0",90',180'.270' Vessel interior 8141/2 1.25 ___ ___i WELD CENTERILINE BMT/2 BMT= Bose Metal Thickness-10.75 (BMT) ý- 0.31 NOM.