L-2008-018, Transmittal of Pressurized Butt Weld Alloy Report, and Mitigation Status and Swol Inspection Results

Transmittal of Pressurized Butt Weld Alloy Report, and Mitigation Status and Swol Inspection Results

ML080660074
Person / Time
Site:	Saint Lucie
Issue date:	02/21/2008
From:	Johnston G Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2008-018, TAC MD5114
Download: ML080660074 (4)

Text

Florida Power & Light Company, 6501 S. Ocean Drive, Jensen Beach, FL 34957 0 February 21, 2008 L-2008-018 FIPL 10 CFR 50.4 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Unit 2 Docket No. 50-389 Unit 2 SL2-17 Pressurizer Butt Weld Alloy 82/182 Mitigation Status and SWOL Inspection Results On January 31, 2007, Florida Power and Light Company (FPL) submitted letter L-2007-013 to notify the NRC of the actions taken or planned for inspecting or mitigating Alloy 82/182 butt welds on pressurizer connections for St. Lucie Unit 2. Additionally, via letters L-2007-045, L-2007-148, and L-2007-172, dated March 29, 2007, September 24, 2007, and October 24, 2007, respectively, FPL sought relief from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code to allow the use of full structural weld overlays (SWOLs) to mitigate select pressurizer Alloy 82/182 butt welds. Within the letters, FPL committed to provide the results of future inspections or mitigations of the St. Lucie Unit 2 -pressurizer butt welds within 60 days of startup from the outage in which they were performed. St.

Lucie Unit 2 commenced commercial power operations from the SL2-17 refueling outage on January 4, 2008.

As required by FPL letter L-2007-148 and the NRC SER for TAC NO. MD5114, dated December 12, 2007, Attachment 1 provides the report of the structural weld overlay (SWOL) Ultrasonic (UT) examinations and a discussion and reason for any repairs to the SWOL and/or base metal. Attachment 2 provides the results of future inspections or mitigations of pressurizer alloy 82/182 butt weld locations as committed to in L-2007-013.

Please contact Ken Frehafer at 772-467-7748 if there are any questions about this submittal.

Very truly yours, Gordon L. Johnston Site Vice President St. Lucie Plant Attachments GLJ/KWF an FPL Group company

St. Lucie Unit 2 L-2008-018 Pressurizer Butt Weld Alloy 82/182 Attachment 1 Mitigation Status and SWOL Inspection Results Page 1 of 2 PSL-2 SL-2-17 Weld Overlay Installation Examination Results Surge Line to Hot Leg No Recordable NRI NRI NRI B Pipe Nozzle Indications (NRI)

Shutdown Cooling Outlet to Hot Leg A NRI NRI NRI NRI Pipe Shutdown Cooling Outlet to Hot Leg B NRI NRI NRI NRI Pipe Hot Leg A Drain NRI NRI NRI NRI PT of barrier layer identified numerous rejectable rounded and linear indications resulting in repair Pressurizer Surge Line NRI NRI NRI Nozzle (at pressurizer) PT of barrier layer excavation -

NRI PT of barrier layer after repair-NRI

St. Lucie Unit 2 L-2008-018 Pressurizer Butt Weld Alloy 82/182 Attachment 1 Mitigation Status and SWOL Inspection Results Page 2 of 2 Three circumferential indications (3.0", 9.0", 5.5") in length by (0.20") in width of lack of bond (LOB) between the overlay and the base material at same axial location were identified. All indications were outside of structural and examination area. The PT of base metal PT of barrier layer identified one indications were evaluated as rejectable in accordance with the identified one linear indication approximately Pre acceptance criteria of FPL's relief request 10, revision 1. A repair rejectable indication 1/8 inch in length. excavation of the indications was performed.

Pressurizer Relief Line approximately 3/16" PT of barrier layer after buffing- final PT of After repair, UT identified three remaining circumferential Nozzle long near toe of safe NRI surface-NRI indications (0.3", 1.2", 0.3") in length by (0.20") in width of LOB.

end between the overlay and the base material at the same axial PT of SWOL excavation to Final PT of PT results after surface-NRI location. The indications were evaluated as acceptable in remove volumetric (UT) accordance with Table IWB-3514-3 and FPL's relief request 10, buffing - NRI indications - NRI revision 1. All indications are outside of structural and ISI examination area.

There was no reduction of the PSI or ISI angle beam UT coverage due to presence of the remaining LOB.

St. Lucie Unit 2 L-2008-018 Pressurizer Butt Weld Alloy 82/182 Attachment 2 Mitigation Status and SWOL Inspection Results Page 1 of 1 St. Lucie Unit 2 Alloy 82/182 Pressurizer Butt Weld Inspection and Mitigation Summary Results The St, Lucie Unit 2 pressurizer has 6 piping nozzle welds that were originally made with alloy 82/182 as identified in the table below. During the SL2-17 refueling outage all 6 piping nozzle welds were mitigated by the method shown in the table below:

Nozzle Mitigation Completed (Note 1)

Susceptible 'Outage Mitigation performed (Note 2)

Function /

Designation Material Description Designation Surge Nozzle-to-safe SL 2-17 Structural Weld Overlay (SWOL)

RC-514-671 end weld only Spray Nozzle-to-safe SL 2-17 Cut out and replacement with Stainless RC-504-671 end weld only Steel (SS)

Safety Nozzle-to-safe SL 2-17 Cut out and replacement with SS 503-671-A end weld only Safety Nozzle-to-safe SL 2-17 Cut out and replacement with SS 503-671-D end weld only Safety Nozzle-to-safe SL 2-17 Cut out and replacement with SS 503-671-C end weld only Relief Nozzle-to-safe SL 2-17 Structural Weld Overlay RC-506-671 end weld only Notes:

1) Refueling Outage started 10-2007 and returned to service 1-4-2008.

2) No evidence of leakage was noted from these butt welds during the preparation for the pressurizer butt weld mitigations identified. In addition, PT was performed prior to SWOL of 2 pressurizer butt welds with the results noted in Attachment 1.