ML14206A929
| ML14206A929 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 07/24/2014 |
| From: | McCartney E Point Beach |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC 2014-0050, TAC 3304 | |
| Download: ML14206A929 (7) | |
Text
NEXTera ... July 24, 2014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Point Beach Nuclear Plant Unit 2 Docket 50-301 Renewed License No. DPR-27 10 CFR 50.55a Request. Relief Request 2-RR-7 Re-Categorization of Unit 2 Steam Generator Nozzle to Safe-End Welds Response to Request for Additional Information
References:
( 1) NextEra Energy Point Beach, LLC letter to NRC, dated POINT BEACH NRC 2014-0050 10 CFR 50.55a December 27, 2013, 10 CFR 50.55a Request, Relief Request 2-RR-7 Re-Categorization of Unit 2 Steam Generator Nozzle to Safe-End Welds (ML 13365A31 0) (2) NRC electronic mail to NextEra Energy Point Beach, LLC, dated June 24, 2014, Point Beach Nuclear Plant, Unit 2-Draft RAis Regarding 2-RR-7 (TAC No. MF3304) NextEra Energy Point Beach, LLC (NextEra) requested in Reference (1) that the Nuclear Regulatory Commission (NRC) allow the re-categorization of the four steam generator nozzle dissimilar metal welds installed in Point Beach Nuclear Plant (PBNP) Unit 2. Due to the June 21, 2011 rulemaking change to 1 OCFR50.55a [FR36232 Volume 76, Number 119], the primary steam generator (SG) nozzle to safe-end welds were required to have a baseline inspection performed in the first outage following August 22, 2011. The rulemaking required the use of American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel Code (BPVC) Code Case N-770-1 with conditions specified in 10CFR50.55a(g)(6)(ii)(F). NextEra requested the dissimilar metal weld categorization be changed to reflect the actual weld profile rather than the default A-2 and B assignment under the new rule. Via Reference (2), the NRC determined additional information was required to enable the staff's continued review of the Relief Request 2-RR-7. The Enclosure to this letter contains the response to the request for additional information in Reference (2). This letter contains no new Regulatory Commitments or revisions to existing Regulatory Commitments. NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241 Document Control Desk Page 2 If you have questions or require additional information, please contact Mr. Michael Millen, Licensing Manager, at 920/755-7845. In accordance with the provisions of 10 CFR 50.91, a copy of this submittal has been provided to the designated Wisconsin Official. Very truly yours, NextEra Energy Point Beach, LLC Eric McCartney Site Vice President Enclosure cc: Regional Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW Mr. Mike Verhagan, Department of Commerce, State of Wisconsin ENCLOSURE NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNIT 2 10 CFR 50.55a REQUEST, RELIEF REQUEST 2-RR 7 RE-CATEGORIZATION OF UNIT 2 STEAM GENERATOR NOZZLE TO SAFE-END WELDS RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION The NRC staff determined that additional information was required (Reference 1) to enable the continued review of the Relief Request 2-RR-7 (Reference 2). The following information is provided by NextEra Energy Point Beach, LLC (NextEra) in response to the NRC staff's request. By letter dated December 27, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML 13365A310), NextEra Energy Point Beach, LLC (NextEra) submitted for the U.S. Nuclear Regulatory Commission (NRC) staff review and approval Relief Request 2-RR-7, which requests authorization for re-categorization of primary Steam Generator (SG) nozzle to safe-end welds under the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code), Code Case N-770-1, with conditions specified in Title 10 of the Code of Federal Regulations, Part 50 (10 CFR 50), paragraph 55a(g)(6)(ii)(F), for duration of the extended license at the Point Beach Nuclear Plant (Point Beach), Unit 2. To complete its review, the NRC staff requests the following additional information: On page two of the December 27, 2013, submittal, NextEra states that one of the SG safe-end to inlet nozzle welds will be examined in approximately 2022, but do not mention the examination of the outlet nozzle to safe end welds. Under 10 CFR 50.55a(g)(6)(ii)(F)(5), all hotleg operating temperature welds in Inspection Items G, H, J, and K must be inspected each interval. A 25-percent sample of Inspection Items G, H, J and K cold-leg operating temperature welds must be inspected whenever the core barrel is removed (unless it has already been inspected within the past 10 years) or 20 years, whichever is less. Given this requirement, please identify your future inspection plans and, if a proposed alternative is requested, provide justification for the change from the current regulatory requirements. Response to RAI 1 The Point Beach Nuclear Plant (PBNP) steam generator (SG) outlet nozzle to safe-end welds are subject to temperatures below the reactor pressure vessel (RPV) outlet temperature of approximately 61 ooF (outlet T = 543°F). If re-categorized to an Item "G" weld (un-cracked butt weld mitigated with an inlay), the two hot leg (inlet nozzle) welds would be examined once an Interval and one of the cold leg (outlet nozzle) welds would be examined within the next twenty years. These welds would be re-examined using both a surface examination from the inside Page 1 of 5 surtace and volumetric examination from the ID or OD (from CC N-770-1 Table 1, "Extent and Frequency of Examination"). It is anticipated that they would be examined utilizing similar techniques to those used in November, 2012 (i.e., eddy current and phased array UT from the I D). Were any indications detected during the pre-inlay installation examination of the Alloy 82/182 weld? If so, discuss whether the indication was removed in its entirety prior to the inlay installation or discuss the flaw size that remained in the alloy 82/182 weld. Please discuss whether the remaining indication was accepted by the ASME Code,Section XI, Table IWB-3410-1. If not, discuss whether the remaining indication was evaluated in accordance with IWB-3600. Response to RAI 2 The PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were "inlaid" at the Westinghouse fabrication facility in Pensacola, FL and were examined in accordance with the rules of ASME Section Ill, 1986 Edition and the design specification (liquid penetrant and radiography). No flaws were recorded during fabrication of the "inlay". The industry operating experience of UT of Alloy 82/182 welds in hot leg nozzles and weld overlaid pressurizer nozzles has shown that the conventional UT has missed detecting indications. Please discuss whether the future inspections of the subject weld(s) at Point Beach, Unit 2, will include the latest industry guidance on UT of Alloy 82/182 welds. Response to RAI 3 The applicable PBNP SG safe-end to inlet and outlet nozzle to safe-end weld(s) will be examined using both surtace (eddy current) and volumetric (UT) techniques from the inside surtace using tooling developed specifically for the November 2012 examinations referenced in the original letter. In the August 12, 2011, Public Meeting Summary (ADAMS Accession Number ML 112240818), the NRC staff provided guidance on requesting re-categorization of mitigated welds (see question/answer #24). Several of the topics to be addressed are not included in your submittal. Please provide the following information with regard to the inlay installed at the SG nozzles, or alternatively provide a technical justification for not doing so: Page 2 of 5 RA/4a a. Repairs pet1ormed on the Alloy 82/182 weld prior to the inlay installation and on the inlay during inlay installation and any fillers materials used; Response to RAI 4a The PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were fabricated and then "inlaid" at the Westinghouse fabrication facility in Pensacola, FL. The welds and inlay were examined in accordance with the rules of ASME Section Ill, 1986 Edition (liquid penetrant, ultrasonic for lack-of-bond, and radiography). No flaws were recorded during fabrication of the welds or inlay materials which required repair. RA/4b b. Methods used to identify the dissimilar metal weld fusion zones and the accuracy of the methods used; Response to RAI 4b The PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were fabricated and then "inlaid" at the Westinghouse fabrication facility in Pensacola, FL. According to Westinghouse drawing numbers 6147E62-3 and 6147E62-6, the dissimilar metal weld (Alloy 82/182) was fabricated and as-built dimensions were recorded prior to weld overlay (inlay) build-up with Alloy 52/152 material. The build-up (inlay) area was shown to be 2.25 +/-.025 inches from the center-line of the dissimilar metal weld (Step 3 on drawing 6147E62-3). During the 2012 lnservice Examination (lSI), the PBNP SG safe-end to inlet and outlet nozzle to safe-end welds had the fusion zones identified by eddy current (ET) and phased array UT (PAUT) examination techniques. The ET equipment was calibrated utilizing a mock-up/calibration block which was designed to replicate approximately the inner 1/3t of the PBNP SG nozzle/safe-end region, including the carbon-clad nozzle, dissimilar metal weld, Alloy 52/152 inlay, and stainless steel safe-end. The response from the fusion zones were detectable by both ET and PAUT (see reports attached to original submittal). The mechanical accuracy of the automated scanning equipment was reported by the examination vendor to be approximately +/-0.125 inches. RA/4c c. Qualifications of the weld procedure specifications, welders and welding operators; Response to RAI 4c The PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were fabricated and then "inlaid" at the Westinghouse fabrication facility in Pensacola, FL. The manufacturing records are not readily available. Page 3 of 5 RA/4d d. Pre-and post-weld heat treatment or temper bead welding requirements followed; Response to RAI 4d The PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were fabricated and then "inlaid" at the Westinghouse fabrication facility in Pensacola, FL. The manufacturing records are not readily available. RA/4e e. Design and analysis requirements used, in detail; Response to RAI 4e The PBNP Unit 2 SG were designed and built to ASME Section Ill, 1986 Edition, no Addenda. RA/4f f. Preservice and inservice inspections performed since installation of the inlays/onlays; Response to RAI 4f The PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were fabricated and then "inlaid" at the Westinghouse fabrication facility in Pensacola, FL. The welds and "inlay" were examined in accordance with the rules of ASME Section Ill, 1986 Edition (liquid penetrant, ultrasonic for lack of bond, and radiography). During the 2012 lnservice Examination (lSI), the PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were examined by automated eddy current and phased array UT examination techniques. RAI4g g. ASME Code Editions and Addenda associated with requirements used, where applicable, and figures, as applicable, to assist in describing the information submitted in conjunction with the request for alternative categorization; Response to RAI 4g The PBNP Unit 2 SG were designed and built to ASME Section Ill, 1986 Edition, no Addenda. Page 4 of 5 RA/4h h. Thickness of inlay/onlay; Response to RAI 4h Westinghouse fabrication drawing 6147E62-3, Step 4 indicates that the design thickness of the cladding and "inlay" was approximately 0.22 inches nominal with a minimum thickness of 0.13 inches. RA/4i i. Flaw evaluation to show adequate thickness against stress corrosion cracking. Response to RAI 4i The PBNP SG safe-end to inlet and outlet nozzle to safe-end welds were fabricated and then "inlaid" at the Westinghouse fabrication facility in Pensacola, FL. Since the inlay was placed over the Alloy 82/182 weld material prior to installation at PBNP, that material has never been exposed to primary coolant. The Alloy 52/152 inlay material which has a minimum thickness of 0.13 inches provides adequate assurance against initiation of SCC in the Alloy 82/182 weld material. References (1) NextEra Energy Point Beach, LLC letter to NRC, dated December 27, 2013, 10 CFR 50.55a Request, Relief Request 2 RR-7 Re-Categorization of Unit 2 Steam Generator Nozzle to Safe-End Welds (ML 13365A31 0) (2) NRC electronic mail to NextEra Energy Point Beach, LLC, dated June 24, 2014, Point Beach Nuclear Plant, Unit 2-Draft RAis Regarding 2-RR-7 (TAG No. MF3304) Page 5 of 5