ML12313A228
| ML12313A228 | |
| Person / Time | |
|---|---|
| Site: | Millstone  (NPF-049) |
| Issue date: | 11/13/2012 |
| From: | James Kim Plant Licensing Branch 1 |
| To: | Heacock D Dominion Nuclear Connecticut |
| Kim J | |
| References | |
| TAC ME8442 | |
| Download: ML12313A228 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 November 13, 2012 Mr. David A. Heacock President and Chief Nuclear Officer Dominion Nuclear Connecticut, Inc, Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711
SUBJECT:
MILLSTONE POWER STATION, UNIT 3 - REFUELING OUTAGE 14 STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT REVIEW (TAC NO, ME8442)
Dear Mr,
Heacock:
By letter dated April 6, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML12109A044), Dominion Nuclear Connecticut, Inc., (the licensee) submitted information summarizing the results of the 2011 steam generator (SG) tube inspections performed at Millstone Power Station, Unit 3, These inspections were performed during the fourteenth refueling outage (3R14), Additional information regarding the SG tube inspections for 3R 14 was provided by the licensee in a letter dated October 1, 2012 (ADAMS Accession Number ML12292A192),
The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of these reports and concludes that the licensee provided the information required by their technical specifications and that no additional follow-up is required at this time. The NRC staff's review of the reports is enclosed, Please contact me at (301) 415-4125 if you have any questions on this issue.
Sincerely,
,~~.
James Kim, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-423
Enclosure:
As stated cc w/encl: Distribution via Listserv
REVIEW OF THE 2011 STEAM GENERATOR TUBE INSERVICE INSPECTION REPORTS DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION, UNIT 3 DOCKET NO. 50-423 By letter dated April 6, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML12109A044), Dominion Nuclear Connecticut, Inc., (the licensee) submitted information summarizing the results of the 2011 steam generator (SG) tube inspections performed at Millstone Power Station, Unit 3 (MPS3). These inspections were performed during the fourteenth refueling outage (3R14). Additional information regarding the SG tube inspections for 3R14 was provided by the licensee in a letter dated October 1,2012 (ADAMS Accession Number ML12292A192).
MPS3 has four Westinghouse Model F SGs, each of which contains 5,626 thermally treated Alloy 600 tubes. Each tube has a nominal outside diameter of 0.688 inches and a nominal wall thickness of 0.040 inches. During SG fabrication, the tubes were hydraulically expanded at both ends, over the full depth of the 21.23-inch thick tubesheet. The tubesheet was drilled on a square pitch with 0.98-inch spacing. There are 59 rows and 122 columns in each SG. The radius of the row 1 U-bends is 2.20 inches. The U-bends in Rows 1 through 10 were stress relieved after bending. Eight Type 405 stainless steel support plates, which have broached quatrefoil holes, support the vertical section of the tubes, and six anti-vibration bars (AVBs) support the U-bend section of the tubes.
As of the end of Cycle 14 (October 2011), the SGs had approximately 19.3 Effective Full Power Years (EFPY) of operation.
The licensee provided the scope, extent, methods, and results of their SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions (i.e.,
tube plugging) taken in response to the inspection findings.
After review of the information provided by the licensee, the U. S. Nuclear Regulatory Commission (NRC) staff has the following comments/observations:
In steam generator D, J-nozzles 1, 15, 16, and 30 had been previously repaired by a weld overlay process. Inspections in this outage showed prior erosion damage that has not appeared to have advanced since the last inspection in spring 2004. Overspray from the J-nozzles was noted on the primary separator riser barrels.
The licensee preventively plugged the tube located at row 5 column 48 in SG A.
This tube had two indications of wear at the apex of the u-bend that were assumed to be caused by the bottom of the AVB supporting the tubes in the row above it. This tube was plugged.
Enclosure
- 2 SG A has 67 tubes and SG C has 39 tubes, which are designated as tier 1 tubes (tubes with potentially elevated residual stresses, also called 2-sigma tubes by some licensees). All of these tier 1 tubes were examined from tube-end to tube-end with a bobbin coil probe and from the hot-leg tube-end to the first detectable support above the hot-leg tubesheet with an array probe.
Based on a review of the information provided by the licensee, the staff concludes that the licensee provided the information required by their technical specifications. The SG tube inspections at MPS3 appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.
November 13, 2012 Mr. David A. Heacock President and Chief Nuclear Officer Dominion Nuclear Connecticut, Inc.
Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711 SUB~IECT:
MILLSTONE POWER STATION, UNIT 3 - REFUELING OUTAGE 14 STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT REVIEW (TAC NO. ME8442)
Dear Mr. Heacock:
By letter dated April 6, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML12109A044), Dominion Nuclear Connecticut, Inc., (the licensee) submitted information summarizing the results of the 2011 steam generator (SG) tube inspections performed at Millstone Power Station, Unit 3. These inspections were performed during the fourteenth refueling outage (3R14). Additional information regarding the SG tube inspections for 3R14 was provided by the licensee in a letter dated October 1, 2012 (ADAMS Accession Number ML12292A192).
The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of these reports and concludes that the licensee provided the information required by their TSs and that no additional follow-up is required at this time. The NRC staff's review of the reports is enclosed.
Please contact me at (301) 415-4125 if you have any questions on this issue.
Sincerely, IRA!
James Kim, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-423
Enclosure:
As stated cc w/enci: Distribution via Listserv DISTRIBUTION:
PUBLIC LPL1-1 R/F RidsNrrDorl RidsNrrDorlLpl1-1 RidsNrrPMMilistone RidsNrrCsgb RidsNrrLAKGoldstein RidsNrrDssStsb RidsRgn1 MailCenter RidsOGCRp RBeliamy, R1 AJohnson, NRR/ESGB RidsAcrsAcnw_MailCTR RidsNrrDorlDpr KKarwoski, NRR/ESGB GKulesa, NRR/DE/ESGB ADAMS ACCESSION NO.: ML12313A228
(* No substantial change in Evaluation Memo OFFICE NRR/LPL 1-1/PM NRR/LPL 1-1/LA NRR/ESGB/BC(*)
NRR/LPL1-1/BC NAME JKim KGoldstein GKulesa GWilson DATE 11/13/12 11/12/12 11/5112 11/13/12 OFFICIAL RECORD COPY