SBK-L-10056, Request for Use of an Alternate Depth Sizing Qualification

Request for Use of an Alternate Depth Sizing Qualification

ML100890436
Person / Time
Site:	Seabrook
Issue date:	03/25/2010
From:	Freeman P NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-10056
Download: ML100890436 (7)

Text

NExTeram ENER GY S SEA BROOK March 25, 2010 SBK-L-10056 Docket No. 50-443 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Seabrook Station Request for Use of an Alternate Depth Sizing Qualification Pursuant to 10 CFR 50.55a(g)(5)(iii), NextEra Energy Seabrook, LLC (NextEra) requests approval to use an alternate depth sizing qualification for volumetric examinations of the reactor pressure vessel (RPV) nozzle-to-safe end dissimilar metal (DM) welds from the inside surface. This relief request is similar to NextEra's request for alternate depth-sizing qualification for the remainder of the second 10-year inservice inspection interval, which was approved by the NRC on May 19, 2009. The details of this request are included in the enclosure to this letter.

Code Case N-695, "Qualification Requirements for Dissimilar Metal Piping Welds,Section XI, Division 1," discusses that examination procedures, equipment, and personnel are qualified for depth-sizing when the root mean square (RMS) error of the flaw depth measurements, as compared to the true flaw depths, does not exceed 0.125 inch. The nuclear industry has attempted to qualify personnel and procedures for depth-sizing examinations performed from the inside surface of dissimilar metal welds since November 2002. To date, no personnel or procedure has achieved less than or equal to the ASME Code required 0.125 inch RMS error.

The inability of examination procedures to achieve the required RMS error value is primarily due to a combination of factors such as surface condition, scan access, base materials, and the dendritic structure in the welds themselves. The combination of these factors has proven too difficult for procedures and personnel to achieve an RMS error value that meets current Code requirements. R 1 NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

U.S. Nuclear Regulatory Commission SBK-L-10056 / Page 2 This relief request is being submitted due to the impracticality of meeting the required 0.125 inch RMS value. NextEra requests review and approval of this relief request by April 1, 2011 to support the Seabrook Station refueling outage in the spring of 2011. Similar requests have been approved by the NRC and are referenced in the enclosure to this letter.

If you have any questions regarding this submittal, please contact Mr. Michael O'Keefe, Licensing Manager, at (603) 773-7745.

Sincerely, NextEra Energy Seabrook, LLC.

Pa 1 eeman Site Vice President Enclosure cc: S. J. Collins, NRC Region I Administrator J. D. Hughey, NRC Project Manager W. J. Raymond, NRC Senior Resident Inspector

Enclosure Request for Use of an Alternate Depth Sizing Qualification

10 CFR 50.55a Request Number 31R-16 Rev. 0 Relief Request In Accordance with 10 CFR 50.55a(g)(5)(iii)

Inservice Inspection Impracticality Request for Relief to Use an Alternative to the Depth-Sizing Qualification Requirement of ASME Section XI, Supplement 10 for Piping Examinations Performed From the Inside Surface for Seabrook Station Unit 1

1.0 ASME Code Components Affected

Code class: 1 System: RC Examination Categories: R-A, Risk Informed Inservice Inspection Program TABLE 1 WELD NUMBERS B Y ISI DESIGNATION Nozzle-to-Safe End Weld Item LocationWedTp Weld Type 1 RPV Outlet Nozzle @202' RC RPV-SE-301-121-A Shop 2 RPV Inlet Nozzle, @2470 RC RPV-SE-302-121-B Shop 3 RPV Inlet Nozzle, @293' RC RPV-SE-302-121-C Shop 4 RPV Outlet Nozzle, @338' RC RPV-SE-301-121-D Shop 5 RPV Outlet Nozzle, @220 RC RPV-SE-301-121-E Shop 6 RPV Inlet Nozzle, @67' RC RPV-SE-302-121-F Shop 7 RPV Inlet Nozzle, @113' RC RPV-SE-302-121-G Shop 8 RPV Outlet Nozzle, @158' RC RPV-SE-301-121-H Shop 1

2.0 Applicable Code Edition and Addenda NextEra Energy Seabrook, LLC (NextEra) will be transitioning to its third 10-year Inservice Inspection (ISI) interval on August 19, 2010. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) of record for the third 10-year ISI interval isSection XI, 2004 Edition (Reference 1). However, as stated in 10 CFR 50.55a (b)(1)(xv),

licensees who use editions and addenda later than the 2001 Edition of the ASME Code shall use the 2001 Edition of Appendix VIII. Therefore, the applicable edition of ASME Section XI for Appendix VIII qualifications is the 2001 Edition.

3.0 Applicable Code Requirement The examination of Class 1 piping welds is required to be performed using procedures, personnel, and equipment qualified to the criteria of the applicable ASME Code,Section XI, Appendix VIII, Supplements. The applicable supplement to this relief is 10, "QUALIFICATION REQUIREMENTS FOR DISSIMILAR METAL PIPING WELDS."

Paragraph 3.2, "Sizing Acceptance Criteria," subparagraph (b) of Supplement 10, states that the "examination procedures, equipment, and personnel are qualified for depth-sizing when the RMS

[root mean square] error of the flaw depth measurements, as compared to the true flaw depths, is less than or equal to 0.125 inch (3.2mm).

Code Case N-695, "Qualification Requirements for Dissimilar Metal Piping Welds, Section Xi, Division 1," provides alternative requirements to Appendix VIII, Supplement 10. Paragraph 3.3(c) of Code Case N-695 states, "Examination procedures, equipment, and personnel are qualified for depth-sizing when the RMS error of the flaw depth measurements, as compared to the true flaw depths, do not exceed 0.125-in. (3 mm)". Code Case N-695 is unconditionally approved for use through Regulatory Guide 1.147, "In-service Inspection Code Case Acceptability, ASME Section XI, Division 1," Revision 15.

4.0 Impracticality of Compliance NextEra will be performing volumetric examinations of the RPV nozzle-to-safe end dissimilar metal (DM) welds from the inside surface during the upcoming third 10-year ISI Interval and will implement the alternative requirements of ASME Code Case N-695. Code Case N-695 requires that qualified procedures and personnel shall demonstrate a flaw depth-sizing error less than or equal to 0.125 inch RMS. This relief request is being submitted due to the impracticality of meeting the required 0.125 inch RMS value required by Code Case N-695. The nuclear power industry has attempted to qualify personnel and procedures for depth-sizing examinations performed from the inside surface of dissimilar metal welds (Supplement 10, Code Case N-695) since November 2002. To date, no personnel or procedure has achieved less than or equal to the 2

ASME Code required 0.125 inch RMS error. This has been verified by NextEra in Reference 2, 3 and 4.

The inability of examination procedures to achieve the required RMS error value is primarily due to a combination of factors such as surface condition, scan access, base materials, and the dendritic structure in the welds themselves. The combination of these factors has proven too difficult for procedures and personnel to achieve an RMS error value that meets current Code requirements.

5.0 Burden Caused by Compliance The most recent attempt at achieving 0.125 inch RMS error was in early 2008. This attempt, as well as previous attempts, did not achieve the required RMS error value. The qualification attempts have been substantial. The attempts have involved multiple vendors, ultrasonic instruments, personnel, and flaw depth-sizing methodologies, all of which have been incapable of achieving the 0.125 inch RMS error value.

The process of qualification for this type of flaw sizing is well established. The cost and effort involved to perform a successful demonstration is quantifiable when a capable technique is available. However, when a capable technique is not available, the costs and effort required for a successful demonstration cannot be easily quantified.

6.0 Proposed Alternative And Basis for Use NextEra proposes using an alternative depth-sizing RMS error value greater than the 0.125 inch RMS error value stated in ASME Code Case N-695 for the examination of welds listed in Table 1 of this relief request. Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested to use an alternative depth-sizing error due to impracticality. This alternative will provide an acceptable level of quality and safety.

For Supplement 10 (N-695) qualifications, only three domestic inspection vendors have demonstrated a capability to depth-size flaws. Of the three vendors, the largest demonstrated flaw sizing error for Supplement 10 is 0.224-inches. As an alternative to the required RMS error stated in paragraph 3.3(c) of Code Case N-695, NextEra will add the difference between the required RMS error of 0.125 inch and the actual RMS error value achieved by our chosen inspection vendor, up to a maximum achieved value of 0.224-inches, to the flaw depth as determined during flaw sizing. The vendor-achieved RMS error value will be as indicated by letter from the Performance Demonstration Administrator (PDA).

Applying the difference between the required RMS error and the vendor achieved RMS error to the actual flaw size, will ensure a conservative flaw bounding approach and provide an acceptable level of quality and safety.

3

7.0 Duration of Proposed Alternative The alternative requirements of this request will be applied for the duration of the third 10-year ISI interval, which commences on August 19, 2010, or until such time that ultrasonic testing techniques are capable of satisfying the 0.125 inch RMS error requirements of N-695, whichever is sooner.

8.0 Precedents Similar relief requests have been granted to the following licensees:

" NRC letter to FPL Energy Seabrook, LLC "Seabrook Station Unit 1 - Relief Request for Use of an Alternate Flaw Sizing Methodology for the Second Inservice Inspection Interval (TAC NO. MD9785)," May 19, 2009 (ML090850504)

" NRC letter to FPL Energy Point Beach, LLC "Point Beach Nuclear Plant, Units 1 and 2 - The Fourth 10-Year Interval Inservice Inspection Program Plan Requests for Relief No. RR-21 (TAC Nos. MD8319 and MD8320)," August 25, 2008 (ML081690887)

" NRC letter to Florida Power and Light Company "Turkey Point Units 3 and 4 -

Safety Evaluation for Relief Request NOS. 34 and 35 Associated with (TAC Nos.

MC3890 and MC3891)," October 20, 2004 (ML042940490) 9.0 References

1. ASME Code,Section XI, 2004 Edition

2. EPRI Letter dated 2/25/08, "Summary of IHI Southwest Technologies (IHISWT)

Supplements 2 & 10 Depth Sizing Results Obtained from the Inside Surface

3. EPRI Letter dated 6/24/04, "Summary of Areva's Supplements 2 & 10 Depth Sizing Results Obtained from the Inside Surface

4. EPRI Letter dated 6/30/08, "Summary of Wesdyne International, LLC Supplements 2

& 10 Depth Sizing Results Obtained from the Inside Surface 4