ML102510185
| ML102510185 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 08/30/2010 |
| From: | Repko R Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10-MN-002 | |
| Download: ML102510185 (7) | |
Text
I REGIS T. REPKO
! Duke Vice President rEnergy McGuire Nuclear Station Duke Energy MG0IVP / 12700 Hagers Ferry Rd.
Huntersville, NC 28078 980-875-4111 980-875-4809 fax regis.repko@duke-energy. corn August 30, 2010 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Duke Energy Carolinas, LLC (Duke Energy)
McGuire Nuclear Station, Unit 1 Docket No. 50-369 Relief Request Serial # 10-MN-002 Volumetric Inspection of Steam Generator Primary Manway Studs Pursuant to 10 CFR 50.55a(a)(3)(ii), Duke Energy hereby submits the enclosed alternative to the requirements of ASME Code Section XI Table IWB-2500-1 to extend the volumetric inspection of the steam generator primary manway studs for one operating cycle past the third 10-year inservice inspection interval end date.
If you have any questions or require additional information, please contact P.T. Vu at (980) 875-4302.
Sincerely, Regis T. Repko Enclosure A-ucP www. duke-energy.com
U. S. Nuclear Regulatory commission August.30, 2010 Page 2 xc:
L. A. Reyes, Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 J. H. Thompson, Project Manager U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop O-8G9A Rockville, MD 20852-2738 J. B. Brady NRC Senior Resident Inspector McGuire Nuclear Station
Enclosure Duke Energy Carolinas, LLC McGuire Nuclear Station, Unit I Relief Request Serial # 10-MN-002 Request for Relief in Accordance with 10 CFR 50.55a(a)(3)(ii)
Extension of Volumetric Inspection of Steam Generator Primary Manway Studs for One Operating Cycle Beyond the Third 10-Year Inservice Inspection Interval End Date.
McGuire Nuclear Station, Unit 1 Relief Request # 10-MN-002 Page 1 of 4 I. ASME Code Component(s) Affected Steam Generator (SG) inlet and outlet Primary Manway Studs, Category B-G-l:
Com.ponent. Summa.ry Number*, " *Component ID :
SG 1A Primary Inlet Manway M1.B6.90.0001 1SGA-MW-X2-YI Studs SG 1A Primary Outlet M1.86.90.0002 1SGA-MW-X2-Y2 Manway Studs SG 1B Primary Inlet Manway M1.B6.90.0003 1SGB-MW-X1-Y1 Studs SG 1B Primary Outlet M1 .86.90.0004 1SGB-MW-X1-Y2 Manway Studs SG 1C Primary Inlet Manway M1.B6.90.0005 1SGC-MW-X2-Y1 Studs SG 1C Primary Outlet M1.B6.90.0006 1SGC-MW-X2-Y2 Manway Studs SG 1D Primary Inlet Manway M1.16.90.0007 1SGD-MW-X1-Y1 Studs SG ID Primary Outlet M1 .B6.90.0008 1SGD-MW-X1-Y2 Manway Studs _
II. Applicable Code Edition and Addenda ASME Boiler and Pressure Vessel Code,Section XI, 1998 Edition through the 2000 Addenda.
Ill. Applicable Code Requirement ASME Code Section XI, Table IWB-2500-1, Category B-G-1, Item B6.90, requires a volumetric examination of the SG Inlet and Outlet Primary Manway Studs in accordance with Figure IWB-2500-12 per a schedule defined by IWA-2430.
McGuire Nuclear Station, Unit 1 Relief Request # 10-MN-002 Page 2 of 4 IV. Impracticality of Compliance The McGuire SG tubing inspections, as required by McGuire Technical Specification 5.5.9, consist of primary manway removal, eddy current testing of the SG tubing, and secondary side inspections & cleaning. The Unit 1 SGs were inspected during 1EOC16 (Spring 2004) and scheduled for inspection during 1EOC18 (Spring 2007) and 1EOC20 (Spring 2010). Due to a containment sump modification and the interferences associated with two major pieces of work performed at the same time and location, a decision was made to postpone the 1EOC1 8 SG inspection until 1EOC19 (Fall 2008), as allowed by McGuire Technical Specification 5.5.9. A portion of the McGuire containment sump is directly beneath the 1B and 1C SGs. Even though 1 EOC19 was slated as a short outage window, a major'modification on the secondary side allowed ample time for SG inspections. To reset the SG inspection plan to match the outage window, the next SG inspection is planned for 1 EOC22 (Spring 2013).
The McGuire Unit 1 Third Interval Inservice Inspection Plan originally planned for the SG primary manway studs to be UT inspected during 1 EOC20 or 1 EOC21 (Fall 2011) to match up with the scheduled SG inspection. Refueling outage 1 EOC21 is the last outage in the McGuire Unit 1 Third Interval Inservice Inspection Plan. The McGuire Third Interval Inspection period ends November 30, 2011. Per ASME Section XI, Section IWA-2430, the interval could be extended to November 30, 2012. The 1 year grace does not encompass the 1 EOC22 outage currently scheduled for March 2013.
With the SG inspection scheduled for 1 EOC22 and volumetric inspections of the SG primary manway studs required during 1EOC21, the SG manways will have to be removed in consecutive outages. Duke Energy has investigated performing a volumetric examination of the SG Inlet and Outlet Primary Manway Studs during the 1 EOC21 refueling outage; however, the dose estimate projected for these examinations would result in hardship without a compensating increase in the level of quality and safety.
The ISI volumetric examinations of the SG Inlet and Outlet Primary Manway Studs will require equipment setup and teardown, SG manway and diaphragm removal and reinstallation, stud, nut, and stud hole cleaning and inspection. The dose estimated for this scope of work is 4.7 rem, just to make the studs available for volumetric inspection. The dose estimate to perform the inspection of the SG Inlet and Outlet Primary Manway Studs is based on radiological data obtained from a similar evolution during Eddy Current Testing of the SGs during refueling outage 1EOC19; therefore, the dose estimate is believed to be reasonably accurate. Duke Energy believes that volumetric inspection of the SG Inlet and Outlet Primary Manway Studs during 1 EOC21 would result in hardship without a compensating increase in the level of quality and safety due to ALARA considerations. Based on ALARA considerations, Duke Energy is proposing to reschedule the inspection' of the SG Inlet and Outlet Primary Manway Studs to coincide with the removal of these manway covers for eddy current testing during 1 EOC22 through the application of this relief request.
Relief is requested to extend the McGuire Unit 1 Third Interval extension provision as defined by IWA-2430 from one year to one refueling cycle to perform a volumetric examination of the SG Inlet and Outlet Primary Manway Studs in accordance with ASME Code Section XI, Table IWB-2500-1, Category B-G-1, Item B6.90, Figure IWB-2500-12 during 1 EOC-22 (currently scheduled
'McGuire Nuclear Station, Unit 1 Relief Request # 10-MN-002 Page 3 of 4 for March of 2013). The extension in accordance with ASME Section XI, IWA-2430 would otherwise end November 30, 2012. The studs will be volumetrically inspected during 1EOC22.
This would allow for SG tube inspection and volumetric inspection of the SG Inlet and Outlet Primary Manway Studs to be performed during the same outage.
V. Proposed Alternative and Basis for Use In accordance with 10 CFR 50.55a(a)(3)(ii), an alternative is proposed on the basis that compliance with the ASME Code requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. As an alternative to the applicable ASME Code examination requirements the following will be performed:
- 1) A visual inspection of the SG primary manways with insulation removed will be performed during the 1 EOC21 refueling outage at ambient pressure and temperature using Maintenance personnel. This inspection will be performed to look for evidence of leakage during the previous cycle.
- 2) A visual examination (VT-2) of the SG manway area with the insulation removed will be performed during the 1EOC21 refueling outage at nominal operating temperature and pressure. This examination will be conducted in accordance with ASME Code Section XI, Table IWB-2500-1 Examination Category B-P, Item B15.30 during 1EOC21.
- 3) The Third Interval inspection for volumetric examination of the SG Inlet and Outlet Primary Manway studs will be extended to the 1 EOC22 refueling outage. A volumetric examination of the SG Inlet and Outlet Primary Manway Studs in accordance with Figure IWB-2500-12 per ASME Code Section XI, Table IWB-2500-1, Category B-G-1, Item B6.90 will be performed during 1 EOC22.
VI. Duration of Proposed Alternative This request is proposed to extend the third interval for the SG Inlet and Outlet Primary Manway Stud volumetric inspections to the 1 EOC22 refueling outage.
VII. Justification for Granting Relief The Babcock & Wilcox International (BWI) 21" primary manway is a robust manway.
- 1) The manway design incorporates a metal to metal contact with gasket properly seated and use of long flexible studs. The metal to metal contact and use of long flexible studs reduces the fatigue loading on the studs during operation. The longer stud design also reduces stud stress caused bypressure and thermal distortion of the opening. This reduced stress reduces the potential for stud degradation.
.sv McGuire Nuclear Station, Unit 1 Relief Request # 10-MN-002 Page 4 of 4
- 2) The McGuire 1A and 1 D SG primary manway studs were volumetrically inspected on October 1, 1999 and 1B and 1C SG studs were volumetrically inspected on March 26, 2001 with no issues found.
- 3) The McGuire Unit 1 SG primary manway studs were visually inspected in their entirety during the 1 EOC1 9 outage, and no issues were noted.
- 4) A review of other similar units' history reveals no issues with the BWI replacement SG primary manway studs. BWI replacement SGs primary manway studs for Catawba Unit 1 (1EOC12 Fall 2000 and 1EOC14 Fall 2003) and McGuire Unit 2 (2EOC19 Fall 2009) have been volumetrically inspected with no findings.
- 5) A search of the Operating Experience database revealed no issues with BWI replacement SG primary manway studs.
- 6) BWI has previously determined that failure of a single stud will not result in failure of the primary manways to perform their function.
In addition, there are several methods available that are likely to detect a manway leak during plant operation. Listed below are some examples:
- 1. Control room operators normally perform Surveillance Test, "Reactor Coolant Leakage Calculation," daily (up to a maximum duration of 72 hrs per McGuire Technical Specification 3.4.13.1) with the plant operating at steady state conditions. Leakage would be likely discovered by the conduct of this test.
- 2. Containment airborne radiation monitors continuously sample the containment atmosphere and alarm in the control room. This detection method is dependent on the size of the leak, reactor coolant activity, and containment background activity.
- 3. Leakage would cause an increase in containment humidity and would be removed by the Containment Ventilation units. Condensate would be captured in the Ventilation Unit Condensate Drain Tank and this level is monitored in the control room.
- 4. Substantial leakage would collect in the containment sump. The sump level is monitored in the control room Based on the proposed alternative, the robustness of the BWI 21" primary manway, previous history with BWI manway studs, and additional methods to monitor leakage online, Duke Energy believes the volumetric inspection of the SG inlet and outlet primary manway studs during 1EOC21 would result in a hardship without a compensating increase in the level of quality and safety due to ALARA considerations.
VIII. Previous Submittals
- 1) Indiana Michigan Power Company, Donald C Cook Unit 1, Request for Relief No. ISIR-32 dated September 15, 2009 (ML092680143), approved February 26, 2010 (ML100539516).