ML14206A716
| ML14206A716 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/21/2014 |
| From: | Mark D. Sartain 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 Dominion Web Address: www.dom.com July 21, 2014 U. S. Nuclear Regulatory Commission Serial No.14-303 Attention: Document Control Desk NSSL/MLC RO Washington, DC 20555 Docket No.
50-336 License No.
DPR-65 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING NICKEL ALLOY 600 AGING MANAGEMENT PROGRAM, LICENSE RENEWAL COMMITMENT #14 (MF3402)
By letter dated July 31, 2013, Dominion Nuclear Connecticut, Inc. (DNC) submitted the proposed Nickel Alloy 600 Aging Management Program (Commitment Item #14 of NUREG-1838) for Millstone Power Station Unit 2 (MPS2).
In an e-mail dated June 4, 2014, the Nuclear Regulatory Commission transmitted a request for additional information (RAI) related to the submittal. Attachment 1 to this letter contains DNC's response to the RAI.
If you have any questions or require additional information, please contact Wanda Craft at (804) 273-4687.
Sincerely, Mark D. Sartain Vice President - Nuclear Engineering NOTAYRY MIC comrnonweeflt of Virginia Reg. # 140S42 COMMONWEALTH OF VIRGINIA
)
CommIslion Expires May 31, 2018 COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President - Nuclear Engineering of Dominion Nuclear Connecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this Of day of
/211ti 2014.
My Commission Expires: A1--4J 1
4ki.' 3/
Notary Public
Serial No.14-303 Docket No. 50-336 Page 2 of 2 Commitments made in this letter: None Attachments:
1.
Response to Request for Additional Information Regarding License Renewal Commitment #14 cc:
U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 Mohan C. Thadani Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08 B1 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station
Serial No 14-303 Docket No. 50-336 Response to Request for Additional Information Regarding License Renewal Commitment #14 Dominion Nuclear Connecticut, Inc.
Millstone Power Station Unit 2
Serial No 14-303 Docket No. 50-336, Page 1 of 4 Response to Request for Additional Information Regarding License Renewal Commitment #14 By letter dated July 31, 2013, Dominion Nuclear Connecticut, Inc. (DNC) submitted the proposed Nickel Alloy 600 Aging Management Program (Commitment Item #14 of NUREG-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 additional information (RAI) related to the submittal. The response to this RAI is as follows:
Question I Section 3.10 mentions several examinations that were to be conducted in the spring 2014 outage. Have these examinations been completed?
What were the results of the examinations? In particular, please provide information on the inspections that have been conducted on the half nozzle repairs.
DNC Response Yes, 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-end weld, two-inch NPS cold leg letdown nozzle-to-safe end weld, and the eight 36-inch NPS reactor coolant pump suction and discharge safe-end-to-pipe welds were completed in the spring 2014 refueling outage. The welds were inspected to the requirements of ASME Code 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 line were inspected per the requirements of ASME Code Case N-722-1.
The examinations were acceptable.
An ASME Section X1 leakage test is performed every refueling outage on the half nozzle repairs of the hot leg instrumentation nozzle penetrations.
The last examination was performed during the spring of 2014 outage.
The results were acceptable with no indication of leakage.
Question 2 Section 3.1 of the plan lists the components within the scope of the aging management program (AMP)
- a. Are there any pressure boundary susceptible Nickel Alloy components or welds present which are exposed to high temperature primary coolant, e.g. 475F which are not included in the list provided for reasons such as they are too small or they do not fall within the scope of American Society of Mechanical Engineers (ASME)
Serial No 14-303 Docket No. 50-336, Page 2 of 4 Code Cases N-722-1, N-729-1, or N-770-1? If so please provide details of these components or welds.
- b. Are there any pressure boundary components listed which are not inspected in accordance with ASME Code Cases N-722-1, N-729-1, or N-770-1? If so please identify the component and describe how its aging is managed.
DNC Response
- a. No, there are no pressure boundary susceptible nickel alloy components or welds exposed to high temperature primary coolant which are not included in the aging management plan list.
- b. The 19 hot leg instrumentation nozzles listed in Section 3.1 are not examined in accordance with the listed Code Cases because half-nozzle repairs were performed on the nozzles. These nozzles were redesigned using Alloy 690 material (see the attached sketches; New Hot Leg RTD Nozzle Geometry with Half Nozzle Repair and New Instrument Nozzle Geometry with Half Nozzle Repair). These nozzles are subject to an ASME Section Xl leakage test that is performed each refueling outage.
Question 3 The NRC staff has recently identified operating experience at a US plant where a dissimilar metal weld was not inspected pursuant to ASME Code Case N-770-1 on the basis that the weld under consideration was a branch connection weld and not a butt weld as required by ASME Code Case N-770-1. Are there any Alloy 82/182 full penetration welds which are not inspected under ASME Code Case N-770-1? If so, please identify the weld(s) and identify whether the weld(s) are associated with Alloy 600 components, and the reason the weld(s) are not inspected under ASME Code Case N-770-1.
DNC Response The Alloy 600 welds associated with the cold leg and steam generator instrumentation nozzles 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 welds associated with the nozzles are examined in accordance with Code Case N-722-1 requirements.
Question 4 Some of the components listed in table 3.1 appear to be non-pressure boundary components.
Please describe the manner in which aging is managed for these
Serial No 14-303 Docket No. 50-336, Page 3 of 4 components as they appear to be out of scope for ASME Code Cases N-722-1, N-729-1, and N-770-1.
DNC Response The non-pressure boundary components listed in Table 3.1 are inspected by either the steam generator program or the reactor vessel internals program per MRP-227-A.
Question 5 Please provide a drawing(s) showing the configuration and materials of construction of the nozzle penetrations discussed in the first full paragraph on page 11 of the plan.
DNC Response The attached sketches, Original Instrument Nozzle Geometry Hot and Cold Legs, New Instrument Nozzle Geometry with Half Nozzle Repair, and New Hot Leg RTD Nozzle Geometry with Half Nozzle Repair, show the configuration and materials of construction of the cold leg and hot leg instrumentation nozzles.
Question 6 Please clarify the design, materials of construction, and inspections of the 2 inch NPS hot leg 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 inch stainless piping at the outlet end by a dissimilar metal weld and joined to the carbon steel hot or cold leg piping by a dissimilar metal weld. Please confirm this assumption and the type of inspection planned/conducted for each weld.
DNC Response The 2-inch hot leg drain line and the 2-inch cold leg letdown lines are attached to the main reactor coolant pipe with a carbon steel nozzle that is clad with stainless steel (i.e., the nozzle-to-pipe weld is carbon steel). (See the attached sketch, RCS Small Bore Nozzle Design). The lines are inspected per the requirements of ASME Code Cases N-722-1 and N-770-1.
The 2-inch hot leg drain line is visually inspected each refueling outage with volumetric UT inspection every five years until the weld is mitigated. The 2-inch cold leg letdown lines are visually inspected once during the 10-year inservice inspection interval with volumetric UT inspections every second inspection period, not to exceed seven years, until the weld is mitigated.
Serial No 14-303 Docket No. 50-336, Page 4 of 4 The assumption that the penetrations consist of an Alloy 600 nozzle joined to carbon steel piping by a dissimilar metal weld is not correct. There is only one dissimilar metal weld on each nozzle of the 2-inch hot leg drain line and the cold leg letdown lines. The nozzles have Inconel 182 buttering on the end. The nozzles are welded to a type 316 stainless steel safe-end using Inconel 82/182 welds. Inconel 82 and 182 are Alloy 600 bare weld wire and covered weld electrode.
NEW INSTRUMENT NOZZLE GEOMETRY WITH HALF NOZZLE REPAIR NOZZLE MATERIAL:
SA-479, TYPE 316 OR SA-182, GRADE F316 NOZZLE MATERIAL:
(SB-166) UNS N06690 (ALLOY 690)
HOT LEG BASE MATERIAL:
A516 Gr 70 52/152 HOT LEG CLADDING MATERIAL:
A240, TYPE 304L
NEW HOTLEG RTD NOZZLE GEOMETRY WITH HALF NOZZLE REPAIR THERMOWELL MATL: INCONEL SB-166, ALLOY 690 A
.063 MIN
.125 MAX PRIOR TO WELDING T
NOZZLE MATERIAL SB-166 UNS NO G690 (ALLOY 690)
HOT LEG BASE MATERIAL:
A516 Gr 70 HOT LEG CLADDING MATERIAL:.
A240, TYPE 304L
.063 MIN
.125. MAX PRIOR TO WELDING ALLOY 600
ORIGINAL INSTRUMENT NOZZLE GEOMETRY HOT AND COLD LEGS EXISTING PIPE NIPPLE
/-(EXISTING STAINLESS STEEL SAFE END) 82/182 WELD
( SA-516, GRADE 70) 82/182 WELD
6 ALLOY-82/182 CoSo--
- ST AIN LESS STEEL SAFEND ALLOY 182 BUTTERING
- C. S.
NOZZLE
=*WELD S
.So CLAD-C.S.
PIPE