ML17079A384

Summary of the U.S. Nuclear Regulatory Commission Staff'S Review of the Spring 2016 Steam Generator Tube Inservice Inspections

ML17079A384
Person / Time
Site:	Nine Mile Point
Issue date:	03/24/2017
From:	Richard Guzman Plant Licensing Branch 1
To:	Stoddard D Dominion Nuclear
Guzman R, NRR/DORL/LPL1
References
CAC MF8506
Download: ML17079A384 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 24, 2017 Mr. Daniel G. Stoddard Senior Vice 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 NO. 3 -

SUMMARY

OF THE U.S. NUCLEAR REGULATORY COMMISSION STAFF'S REVIEW OF THE SPRING 2016 STEAM GENERATOR TUBE INSERVICE INSPECTIONS (CAC NO. MF8506)

Dear Mr. Stoddard:

By letters dated August 2, 2016, and January 31, 2017 (Agencywide Documents Access and Management System Accession Nos. ML16222A351 and ML17038A005, respectively),

Dominion Nuclear Connecticut, Inc. (the licensee) submitted information summarizing the results of the spring 2016 steam generator tube inspections performed at the Millstone Power Station, Unit No. 3 (MPS3). These inspections were performed during the MPS3 Refueling Outage 17.

The U.S. Nuclear Regulatory Commission (NRC) staff has completed its evaluation of the steam generator tube inspection summary report and concludes that the licensee provided the information required by the MPS3 Technical Specifications, and no additional followup is required at this time. The results of the NRC staff's review of the report submitted by the licensee are summarized in the enclosed NRC staff's evaluation.

If you have any questions regarding this matter, please contact me at 301-415-1030 or Richard.Guzman@nrc.gov.

Sincerely, Richard V. Guzman, Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-423

Enclosure:

Steam Generator Tube Inspection Report Summary cc w/enclosure: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 REVIEW

SUMMARY

OF THE SPRING 2016 STEAM GENERATOR TUBE INSERVICE INSPECTIONS MILLSTONE POWER STATION, UNIT NO. 3 DOCKET NO. 50-423 By letters dated August 2, 2016, and January 31, 2017 (Agencywide Documents Access and Management System Accession Nos. ML16222A351 and ML17038A005, respectively),

Dominion Nuclear Connecticut, Inc. (the licensee) submitted information summarizing the results of its 2016 steam generator (SG) tube inspections performed during Refueling Outage 17 (RF0-17) at the Millstone Power Station, Unit No. 3 (MPS3). In its letter dated January 31, 2017, the licensee provided additional information regarding the 2016 report.

MPS3 has four Westinghouse Model F SGs that were installed in 1986. Each SG contains 5,626 thermally treated Alloy 600 tubes, with nominal outside diameters of 0.688 inches and nominal wall thicknesses 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 U-bends in row 1 is 2.20 inches. The U-bends in rows 1 through 10 were stress relieved after bending. Eight Type-405 stainless steel tube support plates, which have broached quatrefoil holes, support the vertical section of the tubes, and six anti-vibration bars support the U-bend section of the tubes.

The licensee provided the scope, extent, methods, and results of its 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. Secondary side visual inspections were performed in all four SGs during RF0-17, and upper internals inspections were performed in only SG B. Only the tubes in SG B and SG D were inspected this outage.

Based on its review of the information provided, the U.S. Nuclear Regulatory Commission (NRC) staff has the following comments/observations:

• One foreign object remains in SG C. The foreign object is a block of metal lodged between the blowdown piping and a tube in row 1, column 4, on the cold leg side. The tube was plugged and stabilized during RF0-8 (2002) when the object was first observed. The existence of the foreign object has been confirmed to be confined at this location during every secondary side visual inspection.

Based on a review of the information provided by the licensee, the NRC staff concludes that the licensee provided the information required by its 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 Enclosure

experience at similarly designed and operated units. Therefore, the NRC staff concludes that there are no technical issues that warrant followup action at this time.

Principal Contributor: A. Huynh Date: March 24, 2017

SUBJECT:

MILLSTONE POWER STATION, UNIT NO. 3 -

SUMMARY

OF THE U.S. NUCLEAR REGULATORY COMMISSION STAFF'S REVIEW OF THE SPRING 2016 STEAM GENERATOR TUBE INSERVICE INSPECTIONS (CAC NO. MF8506) DATED MARCH 24, 2017 DISTRIBUTION:

Non-Public LPL 1 R/F RidsACRS_MailCTR Resource RidsNrrDeEsgb Resource RidsNrrDorlLpl1 Resource RidsNrrPMMillstone Resource RidsNrrLALRonewicz RidsRgn1 MailCenter Resource AHuynh, NRR AJohnson, NRR PKlein, NRR ADAMS Accession Number: ML17079A384 *by memorandum OFFICE DORL/LPL 1/PM DORL/LPL 1/LA DE/ESGB/BC(A)* DORL/LPL 1/BC DORL/LPL 1/PM NAME RGuzman LRonewicz AJohnson JDanna RGuzman DATE 03/21/2017 03/21/2017 03/13/2017 03/24/2017 03/24/2017 OFFICIAL RECORD COPY