W3F1-2013-0062, Commitment Change for UT Examination Frequency for the Pressurizer Safety/Relief Valves' Nozzle Weld Overlays

Commitment Change for UT Examination Frequency for the Pressurizer Safety/Relief Valves' Nozzle Weld Overlays

ML13305A127
Person / Time
Site:	Waterford
Issue date:	10/31/2013
From:	Pellegrin B Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
W3F1-2013-0062
Download: ML13305A127 (6)

Text

Entergy Operations, Inc.

17265 River Road Killona, LA 70057-3093 Tel 504 739 6203 Fax 504 739 6698 bpelleg@entergy.com Bryan Pellegrin Licensing Manager, Acting Waterford 3 10 CFR 50.55a W3F1-2013-0062 October 31, 2013 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Waterford 3 Commitment Change for UT Examination Frequency for the Pressurizer Safety/Relief Valves Nozzle Weld Overlays Waterford Steam Electric Station, Unit 3 Docket No. 50-382 License No. NPF-38

REFERENCES:

1. Entergy Letter dated February 21, 2008, Revised Request for Alternative W3-R&R-006 - Proposed Alternative to ASME Code Requirements for Weld Overlay Repairs [Adams Accession No. ML0805600268]

2. NRC Letter to Entergy dated April 21, 2008 Approval of, "Request for Alternative W3-R&R-006 - Proposed Alternative to ASME Code Requirements for Weld Overlay (TAC NO. MD5388) [Adams Accession No. ML080950273]

3. Entergy Letter dated May 10, 2008, Summary of Design and Analyses of Weld Overlays for Pressurizer and Hot Leg Nozzle Dissimilar Metal Welds for Alloy 600 Mitigation [Adams Accession No. ML081350064]

4. NRC Letter to Entergy dated May 20, 2008, "Correction to Request for Alternative W3-R&R-006 - Proposed Alternative to ASME Code Requirements for Weld Overlay (TAC NO. MD5388) [Adams Accession No. ML081400568]

Dear Sir or Madam:

This letter is to notify the NRC of a change to a commitment made in reference 1 for the Waterford Steam Electric Station, Unit 3. This change follows the guidance provided in NEI 99-04, Revision 1, Guidelines for Managing NRC Commitment Changes. The changed commitment will require an Ultrasonic Test (UT) examination of three Dissimilar Metal Weld (DMW) overlays for the Pressurizer Safety relief valve nozzles within a nine year frequency instead of the currently committed ten year frequency. This periodicity will be followed until such time when a technique is qualified to examine cast stainless steel in accordance with the Performance Demonstration Initiative (PDI) program. This change is necessitated by a recalculated Crack Growth Analysis performed by Structural Integrity Associates, Inc. (SIA).

W3F1-2013-0062 Page 2 of 4 The recalculated Crack Growth Analysis showed that the amount of time it takes for an axial flaw to grow into the overlay without violating overlay design basis thickness for the above welds is nine years instead of ten years.

In Entergy Letter dated February 21, 2008 (Reference 1), Entergy Operations, Inc. (Entergy) made the following commitment:

Inservice inspection of the DMW weld overlays with cast stainless steel safe ends will be performed at a higher frequency than those without cast stainless steel safe ends.

First, the initial UT inspection of the DMW weld overlays will be performed during the first or second refueling outage after installation. Then, instead of being inspected on a twenty-five percent sample basis, these weld overlays will be UT examined once every ten years from the date of installation until such time when a technique is qualified to examine cast stainless steel in accordance with the PDI Program. Once the subject DMW overlays are UT examined by a qualified PDI technique (for cast stainless steel) and no planar flaws are detected, then the DMW overlays will be placed into a population in which 25% of that population is examined once every 10 years. Until such time, the UT inspections of the subject DMW overlays (with cast stainless steel safe ends) will not be credited to satisfy the 25% sample inspection requirement. Note that inservice inspection of weld overlays for stainless steel welds is performed at the frequencies required by the WF3 ISI Program as stipulated in Section V.A.3.j.

The NRC approved the relief request in NRC Letter to Entergy dated April 21, 2008 (Reference 2) and acknowledged the commitment reflected above. A correction to the approval was provided in NRC Letter to Entergy dated May 20, 2008 (Reference 4) which did not affect the above commitment.

Entergy also committed (in Reference 1) to submittal of a stress analysis summary demonstrating that the subject nozzles will perform their intended design functions after the weld overlay installation. This was to include that the postulated crack growth in the nozzles will not adversely affect the integrity of the overlaid welds. The NRC acknowledged the commitment to submit a stress analysis summary for the Pressurizer Safety/Relief Valves nozzles in its corrected approval of the alternative in Reference 4.

The stress analysis summary discussed above was provided to the NRC in Reference 3. In the attachment to Reference 3, Table 2-5 indicated that that the amount of time it takes for an axial flaw to grow into the overlay without violating overlay design basis thickness for the Pressurizer Safety/Relief Valves nozzle welds was ten years.

As part of the Waterford 3 Steam Generator Replacement Project it was determined that the Crack Growth Analysis would need to be updated to address any changed nozzle loads due to the replacement Steam Generators. This update noted that previous Crack Growth Analysis had not considered all applicable loading for the weld overlays. As a result, the updated Crack Growth Analysis (proprietary) performed by SIA determined that the amount of time it takes for an axial flaw to grow into the overlay without violating overlay design basis thickness for the Pressurizer Safety/Relief Valves nozzle welds is nine years. This is a one year reduction in the previous postulated crack growth rate of ten years. This is the only reduction in the crack growth rate in the subsequent Crack Growth Analysis that impacts the ten year inspection frequency previously committed to. That is, the remaining DMW welds crack growth rates remain bounded by performance of a UT exam once every ten years.

W3F1-2013-0062 Page 3 of 4 Based on the revised Crack Growth Analysis for the Pressurizer Safety/Relief Valves nozzle welds, the previous commitment in Reference 1 is revised to as follows:

Inservice inspection of the DMW weld overlays with cast stainless steel safe ends will be performed at a higher frequency than those without cast stainless steel safe ends.

First, the initial UT inspection of the DMW weld overlays will be performed during the first or second refueling outage after installation. Then, instead of being inspected on a twenty-five percent sample basis, these weld overlays, with the exception of the Pressurizer Safety/Relief Valves weld overlays, will be UT examined once every ten years from the date of installation until such time when a technique is qualified to examine cast stainless steel in accordance with the PDI Program. Then also, instead of being inspected on a twenty-five percent sample basis, the Pressurizer Safety/Relief Valves weld overlays will be UT examined once every nine years from the date of installation until such time when a technique is qualified to examine cast stainless steel in accordance with the PDI Program. Once the subject DMW overlays are UT examined by a qualified PDI technique (for cast stainless steel) and no planar flaws are detected, then the DMW overlays will be placed into a population in which 25% of that population is examined once every 10 years. Until such time, the UT inspections of the subject DMW overlays (with cast stainless steel safe ends) will not be credited to satisfy the 25% sample inspection requirement. Note that inservice inspection of weld overlays for stainless steel welds is performed at the frequencies required by the WF3 ISI Program as stipulated in Section V.A.3.j of Attachment 2 to letter W3F1-2008-0010.

The initial UT inspections of the DMW weld overlays were performed during Waterford 3s Refueling Outage 17, which was completed in May 2011.

This letter contains one revised commitment as summarized in the Attachment to this letter.

If you have any questions or require additional information, please contact Bryan Pellegrin, acting Licensing Manager at (504) 739-6203.

Sincerely,

Attachment:

Regulatory Commitment

W3F1-2013-0062 Page 4 of 4 cc: Mr. Marc L. Dapas RidsRgn4MailCenter@nrc.gov Regional Administrator U. S. Nuclear Regulatory Commission Region IV 1600 E. Lamar Blvd.

Arlington, TX 76011-4511 NRC Senior Resident Inspector Marlone.Davis@nrc.gov Waterford Steam Electric Station Unit 3 Chris.Speer@nrc.gov P.O. Box 822 Killona, LA 70066-0751 U. S. Nuclear Regulatory Commission Kaly.Kalyanam@nrc.gov Attn: Mr. N. Kalyanam Mail Stop O-07D1 Washington, DC 20555-0001

Attachment to W3F1-2013-0062 Regulatory Commitment

Attachment to W3F1-2013-0062 Page 1 of 1 Revised Regulatory Commitment The following table identifies those actions committed to by Entergy in this document. Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments.

TYPE (Check one) SCHEDULED ONE- CONTINUING COMPLETION COMMITMENT TIME COMPLIANCE DATE (If ACTION Required)

Inservice inspection of the DMW weld overlays with During cast stainless steel safe ends will be performed at a scheduled higher frequency than those without cast stainless inservice steel safe ends. First, the initial UT inspection of the inspections at DMW weld overlays will be performed during the the first or second refueling outage after installation. frequencies Then, instead of being inspected on a twenty-five specified in percent sample basis, these weld overlays, with the letter W3F1-exception of the Pressurizer Safety/Relief Valves 2008-0010, weld overlays, will be UT examined once every ten Attachment 2, years from the date of installation until such time paragraph when a technique is qualified to examine cast 3.0(c).

stainless steel in accordance with the PDI Program.

Then also, instead of being inspected on a twenty-five percent sample basis, the Pressurizer Safety/Relief Valves weld overlays will be UT examined once every nine years from the date of installation until such time when a technique is qualified to examine cast stainless steel in accordance with the PDI Program. Once the subject DMW overlays are UT examined by a qualified PDI technique (for cast stainless steel) and no planar flaws are detected, then the DMW overlays will be placed into a population in which 25% of that population is examined once every 10 years. Until such time, the UT inspections of the subject DMW overlays (with cast stainless steel safe ends) will not be credited to satisfy the 25% sample inspection requirement. Note that inservice inspection of weld overlays for stainless steel welds is performed at the frequencies required by the WF3 ISI Program as stipulated in Section V.A.3.j of to letter W3F1-2008-0010.