ML14206A716
| ML14206A716 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/21/2014 |
| From: | Sartain M D Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 14-303, TAC MF3402 | |
| Download: ML14206A716 (11) | |
Text
Dominion Nuclear Connecticut, Inc.5000 Dominion Boulevard, Glen Allen, VA 23060 DominionWeb Address: www.dom.comJuly 21, 2014U. S. Nuclear Regulatory Commission Serial No. 14-303Attention: Document Control Desk NSSL/MLC ROWashington, DC 20555 Docket No. 50-336License No. DPR-65DOMINION NUCLEAR CONNECTICUT, INC.MILLSTONE POWER STATION UNIT 2RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING NICKELALLOY 600 AGING MANAGEMENT PROGRAM, LICENSE RENEWALCOMMITMENT #14 (MF3402)By letter dated July 31, 2013, Dominion Nuclear Connecticut, Inc. (DNC) submitted theproposed Nickel Alloy 600 Aging Management Program (Commitment Item #14 ofNUREG-1838) for Millstone Power Station Unit 2 (MPS2). In an e-mail dated June 4,2014, the Nuclear Regulatory Commission transmitted a request for additionalinformation (RAI) related to the submittal. Attachment 1 to this letter contains DNC'sresponse to the RAI.If you have any questions or require additional information, please contact Wanda Craftat (804) 273-4687.Sincerely,Mark D. SartainVice President -Nuclear EngineeringNOTAYRY MICcomrnonweeflt of VirginiaReg. # 140S42COMMONWEALTH OF VIRGINIA ) CommIslion Expires May 31, 2018COUNTY OF HENRICOThe foregoing document was acknowledged before me, in and for the County and Commonwealthaforesaid, today by Mark D. Sartain, who is Vice President -Nuclear Engineering of Dominion NuclearConnecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoingdocument in behalf of that company, and that the statements in the document are true to the best of hisknowledge and belief.Acknowledged before me this Of day of /211ti 2014.My Commission Expires: A1--4J14ki.' 3/ _ .Notary Public Serial No. 14-303Docket No. 50-336Page 2 of 2Commitments made in this letter: NoneAttachments:1 .Response to Request for Additional Information Regarding License RenewalCommitment #14cc: U.S. Nuclear Regulatory CommissionRegion I2100 Renaissance Blvd, Suite 100King of Prussia, PA 19406-2713Mohan C. ThadaniSenior Project ManagerU.S. Nuclear Regulatory CommissionOne White Flint North, Mail Stop 08 B111555 Rockville PikeRockville, MD 20852-2738NRC Senior Resident InspectorMillstone Power Station Serial No 14-303Docket No. 50-336Attachment 1Response to Request for Additional Information Regarding License RenewalCommitment #14Dominion Nuclear Connecticut, Inc.Millstone Power Station Unit 2 Serial No 14-303Docket No. 50-336Attachment 1, Page 1 of 4Response to Request for Additional Information Regarding License RenewalCommitment #14By letter dated July 31, 2013, Dominion Nuclear Connecticut, Inc. (DNC) submitted theproposed Nickel Alloy 600 Aging Management Program (Commitment Item #14 ofNUREG-1838) for Millstone Power Station Unit 2 (MPS2). In an e-mail dated June 4,2014, the Nuclear Regulatory Commission (NRC) transmitted a request for additionalinformation (RAI) related to the submittal. The response to this RAI is as follows:Question ISection 3.10 mentions several examinations that were to be conducted in the spring 2014outage. Have these examinations been completed? What were the results of theexaminations? In particular, please provide information on the inspections that have beenconducted on the half nozzle repairs.DNC ResponseYes, as discussed in Section 3.10 of the July 31, 2013 submittal, ultrasonic test (UT)examinations of the two-inch nominal pipe size (NPS) hot leg drain nozzle-to-safe-endweld, two-inch NPS cold leg letdown nozzle-to-safe end weld, and the eight 36-inch NPSreactor coolant pump suction and discharge safe-end-to-pipe welds were completed in thespring 2014 refueling outage. The welds were inspected to the requirements of ASMECode Case N-770-1 and were acceptable with no relevant indications detected.In addition, the two-inch NPS hot leg drain line and the two-inch NPS cold leg letdown linewere inspected per the requirements of ASME Code Case N-722-1. The examinationswere acceptable.An ASME Section X1 leakage test is performed every refueling outage on the half nozzlerepairs of the hot leg instrumentation nozzle penetrations. The last examination wasperformed during the spring of 2014 outage. The results were acceptable with noindication of leakage.Question 2Section 3.1 of the plan lists the components within the scope of the aging managementprogram (AMP)a. Are there any pressure boundary susceptible Nickel Alloy components or weldspresent which are exposed to high temperature primary coolant, e.g. 475F whichare not included in the list provided for reasons such as they are too small or theydo not fall within the scope of American Society of Mechanical Engineers (ASME)
Serial No 14-303Docket No. 50-336Attachment 1, Page 2 of 4Code Cases N-722-1, N-729-1, or N-770-1? If so please provide details of thesecomponents or welds.b. Are there any pressure boundary components listed which are not inspected inaccordance with ASME Code Cases N-722-1, N-729-1, or N-770-1? If so pleaseidentify the component and describe how its aging is managed.DNC Responsea. No, there are no pressure boundary susceptible nickel alloy components or weldsexposed to high temperature primary coolant which are not included in the agingmanagement plan list.b. The 19 hot leg instrumentation nozzles listed in Section 3.1 are not examined inaccordance with the listed Code Cases because half-nozzle repairs were performedon the nozzles. These nozzles were redesigned using Alloy 690 material (see theattached sketches; New Hot Leg RTD Nozzle Geometry with Half Nozzle Repairand New Instrument Nozzle Geometry with Half Nozzle Repair). These nozzles aresubject to an ASME Section Xl leakage test that is performed each refuelingoutage.Question 3The NRC staff has recently identified operating experience at a US plant where adissimilar metal weld was not inspected pursuant to ASME Code Case N-770-1 on thebasis that the weld under consideration was a branch connection weld and not a butt weldas required by ASME Code Case N-770-1. Are there any Alloy 82/182 full penetrationwelds which are not inspected under ASME Code Case N-770-1? If so, please identify theweld(s) and identify whether the weld(s) are associated with Alloy 600 components, andthe reason the weld(s) are not inspected under ASME Code Case N-770-1.DNC ResponseThe Alloy 600 welds associated with the cold leg and steam generator instrumentationnozzles are not examined under Code Case N-770-1 requirements. The weld sizes are 1-inch NPS and less, which is not within the scope of Code Case N-770-1. The weldsassociated with the nozzles are examined in accordance with Code Case N-722-1requirements.Question 4Some of the components listed in table 3.1 appear to be non-pressure boundarycomponents. Please describe the manner in which aging is managed for these Serial No 14-303Docket No. 50-336Attachment 1, Page 3 of 4components as they appear to be out of scope for ASME Code Cases N-722-1, N-729-1,and N-770-1.DNC ResponseThe non-pressure boundary components listed in Table 3.1 are inspected by either thesteam generator program or the reactor vessel internals program per MRP-227-A.Question 5Please provide a drawing(s) showing the configuration and materials of construction of thenozzle penetrations discussed in the first full paragraph on page 11 of the plan.DNC ResponseThe attached sketches, Original Instrument Nozzle Geometry Hot and Cold Legs, NewInstrument Nozzle Geometry with Half Nozzle Repair, and New Hot Leg RTD NozzleGeometry with Half Nozzle Repair, show the configuration and materials of construction ofthe cold leg and hot leg instrumentation nozzles.Question 6Please clarify the design, materials of construction, and inspections of the 2 inch NPS hotleg drain lines and cold leg letdown lines discussed in paragraph 3 of page 11 of the plan.The staff assumes that these penetrations consist of an Alloy 600 nozzle joined to 2 inchstainless piping at the outlet end by a dissimilar metal weld and joined to the carbon steelhot or cold leg piping by a dissimilar metal weld. Please confirm this assumption and thetype of inspection planned/conducted for each weld.DNC ResponseThe 2-inch hot leg drain line and the 2-inch cold leg letdown lines are attached to the mainreactor coolant pipe with a carbon steel nozzle that is clad with stainless steel (i.e., thenozzle-to-pipe weld is carbon steel). (See the attached sketch, RCS Small Bore NozzleDesign). The lines are inspected per the requirements of ASME Code Cases N-722-1 andN-770-1. The 2-inch hot leg drain line is visually inspected each refueling outage withvolumetric UT inspection every five years until the weld is mitigated. The 2-inch cold legletdown lines are visually inspected once during the 10-year inservice inspection intervalwith volumetric UT inspections every second inspection period, not to exceed seven years,until the weld is mitigated.
Serial No 14-303Docket No. 50-336Attachment 1, Page 4 of 4The assumption that the penetrations consist of an Alloy 600 nozzle joined to carbon steelpiping by a dissimilar metal weld is not correct. There is only one dissimilar metal weld oneach nozzle of the 2-inch hot leg drain line and the cold leg letdown lines. The nozzleshave Inconel 182 buttering on the end. The nozzles are welded to a type 316 stainlesssteel safe-end using Inconel 82/182 welds. Inconel 82 and 182 are Alloy 600 bare weldwire and covered weld electrode.
NEW INSTRUMENT NOZZLE GEOMETRYWITH HALFNOZZLEREPAIRNOZZLE MATERIAL:SA-479, TYPE 316 ORSA-182, GRADE F316NOZZLE MATERIAL:(SB-166) UNS N06690 (ALLOY 690)HOT LEGBASE MATERIAL:A516 Gr 7052/152HOT LEGCLADDING MATERIAL:A240, TYPE 304L NEW HOTLEG RTD NOZZLE GEOMETRYWITH HALF NOZZLE REPAIRTHERMOWELL MATL: INCONEL SB-166, ALLOY 690 A.063 MIN.125 MAXPRIOR TO WELDINGTNOZZLE MATERIALSB-166 UNS NO G690(ALLOY 690)HOT LEGBASE MATERIAL:A516 Gr 70HOT LEGCLADDING MATERIAL:.A240, TYPE 304L.063 MIN.125. MAXPRIOR TO WELDINGALLOY 600 ORIGINAL INSTRUMENT NOZZLE GEOMETRYHOT AND COLD LEGSEXISTING PIPE -NIPPLE/-(EXISTING STAINLESS STEEL SAFE END)82/182 WELD( SA-516, GRADE 70)82/182 WELD 6ALLOY-82/182CoSo--RCS Small Bore Nozzle DesignAIN LESSSTEELSAFENDALLOY 182BUTTERINGS.NOZZLES .So CLAD- C.S.PIPE