ML021800003

Summary of Conference Calls with North Atlantic Energy Service Corp. Regarding 2002 Steam Generator Inspection Results

ML021800003
Person / Time
Site:	Seabrook
Issue date:	07/02/2002
From:	Starkey R NRC/NRR/DLPM/LPD1
To:	Feigenbaum T, Peschel J North Atlantic Energy Service Corp
Starkey, D, NRR/DLPM, 415-1122
References
TAC MB5299
Download: ML021800003 (6)

Text

July 2, 2002 Mr. Ted C. Feigenbaum Executive Vice President and Chief Nuclear Officer North Atlantic Energy Service Corporation c/o Mr. James M. Peschel P.O. Box 300 Seabrook, NH 03874

SUMMARY

OF CONFERENCE CALLS WITH NORTH ATLANTIC ENERGY SERVICE CORPORATION REGARDING THE 2002 STEAM GENERATOR INSPECTION RESULTS AT SEABROOK STATION, UNIT NO. 1 (SEABROOK)

(TAC NO. MB5299)

Dear Mr. Feigenbaum:

On May 20 and 23, 2002, the Nuclear Regulatory Commission staff participated in conference calls with North Atlantic Energy Service Corporation representatives regarding the ongoing steam generator tube inspection activities at Seabrook. Enclosed please find a summary of those conference calls.

Sincerely,

/RA/

Robert D. Starkey, Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-443

Enclosure:

As stated cc w/encl: See next page

July 2, 2002 Mr. Ted C. Feigenbaum Executive Vice President and Chief Nuclear Officer North Atlantic Energy Service Corporation c/o Mr. James M. Peschel P.O. Box 300 Seabrook, NH 03874

SUMMARY

OF CONFERENCE CALLS WITH NORTH ATLANTIC ENERGY SERVICE CORPORATION REGARDING THE 2002 STEAM GENERATOR INSPECTION RESULTS AT SEABROOK STATION, UNIT NO. 1 (SEABROOK)

(TAC NO. MB5299)

Dear Mr. Feigenbaum:

On May 20 and 23, 2002, the Nuclear Regulatory Commission staff participated in conference calls with North Atlantic Energy Service Corporation representatives regarding the ongoing steam generator tube inspection activities at Seabrook. Enclosed please find a summary of those conference calls.

Sincerely,

/RA/

Robert D. Starkey, Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-443

Enclosure:

As stated cc w/encl: See next page DISTRIBUTION:

PUBLIC BFu JZimmerman LLund DStarkey KKarwoski TClark DLew OGC ACRS SRichards (e-mail) CCowgill, RI Accession Number: ML021800003 *Concurrence via e-mail OFFICE PDI-2/PM PDI-2/LA* PDI-2/SC(A)

NAME DStarkey TClark JZimmerman DATE 7-2-02 07/02/02 7/2/02 OFFICIAL RECORD COPY

Seabrook Station, Unit No. 1 cc:

William J. Quinlan, Esq. Mr. Stephen McGrail, Director Assistant General Counsel ATTN: James Muckerheide Northeast Utilities Service Company Massachusetts Emergency Management Agency P.O. Box 270 400 Worcester Road Hartford, CT 06141-0270 Framingham, MA 01702-5399 Mr. Peter Brann Philip T. McLaughlin, Attorney General Assistant Attorney General Steven M. Houran, Deputy Attorney State House, Station #6 General Augusta, ME 04333 33 Capitol Street Concord, NH 03301 Resident Inspector U.S. Nuclear Regulatory Commission Mr. Donald Bliss, Director Seabrook Nuclear Power Station New Hampshire Office of Emergency P.O. Box 1149 Management Seabrook, NH 03874 State Office Park South 107 Pleasant Street Town of Exeter Concord, NH 03301 10 Front Street Exeter, NH 03823 Mr. Daniel G. Roy Nuclear Training Manager Regional Administrator, Region I Seabrook Station U.S. Nuclear Regulatory Commission North Atlantic Energy Service Corp.

475 Allendale Road P.O. Box 300 King of Prussia, PA 19406 Seabrook, NH 03874 Office of the Attorney General Mr. James M. Peschel One Ashburton Place Manager - Regulatory Programs 20th Floor Seabrook Station Boston, MA 02108 North Atlantic Energy Service Corp.

P.O. Box 300 Board of Selectmen Seabrook, NH 03874 Town of Amesbury Town Hall Mr. Gene F. St. Pierre Amesbury, MA 01913 Station Director Seabrook Station Mr. Dan McElhinney North Atlantic Energy Service Corporation Federal Emergency Management Agency P.O. Box 300 Region I Seabrook, NH 03874 J.W. McCormack P.O. &

Courthouse Building, Room 401 Mr. Frank W. Getman, Jr.

Boston, MA 02109 President and Chief Executive Officer BayCorp Holdings, LTD 20 International Drive, Suite 301 Portsmouth, NH 03801-6809

Seabrook Station, Unit No. 1 cc:

Mr. Bruce D. Kenyon President and Chief Executive Officer Northeast Utilities Service Company P.O. Box 270 Hartford, CT 06141-0270 Mr. Steve Allen Polestar Applied Technology, Inc.

77 Franklin Street, Suite 507 Boston, MA 02110

SUMMARY

OF CONFERENCE CALLS WITH NORTH ATLANTIC ENERGY SERVICE CORPORATION REGARDING THE MAY 2002 STEAM GENERATOR INSPECTION RESULTS AT SEABROOK The Nuclear Regulatory Commission (NRC) staff participated in conference calls on May 20 and 23, 2002, with North Atlantic Energy Service Corporation (North Atlantic) representatives regarding the ongoing steam generator (SG) tube inspection activities at Seabrook Station, Unit No. 1 (Seabrook).

Topics discussed during the conference call consisted of: background, initial eddy current testing scope, scope expansion plans, indications identified to-date, repair/plugging plans, new degradation findings, and tube-pull analysis plans.

Background

Seabrook is a four-loop Westinghouse 1,198 MWe PWR unit. Commercial operation started in August of 1990. The unit has operated for approximately 9.67 effective full power years (EFPY).

Seabrook has four Westinghouse Model-F recirculating steam generators (A, B, C, and D).

Each steam generator contains 5,626 thermally treated Inconel 600 tubes, which are nominally 0.688 inch in diameter with a wall thickness of 0.040 inches. Prior to installation, the tubes in Rows 1 through 10 were treated in a furnace in order to relieve the stresses from bending the tubes. Each SG contains eight stainless steel tube support plates and six anti-vibration bars in the U-bend region. The first tube support plate is a partial plate which consists of only a plate ring with drilled tube holes (i.e., the plate only supports a limited number of tubes in the periphery). The remaining seven plates contain quatrefoil broached tube holes. Plates 1 - 4 are 0.75 inches in thickness; Plates 5 - 8 are 1.12 inches thick.

New Degradation Findings During the current refueling outage at Seabrook in May 2002, North Atlantic performed SG tube inspections as required by the technical specifications. The initial scope of the inspection included two of the four SGs -- A and D. While performing bobbin probe inspections of tubes in SG D, North Atlantic detected indications at a number of tube to tube support plate intersections. Subsequent plus-point probe inspection confirmed the indications as axially oriented linear indications, initiating on the outside diameter (OD) tube surface. North Atlantic also performed ultrasonic testing (UT) on a few of the indications, which further confirmed the findings. At this stage, North Atlantic classified these indications as axial OD cracking.

North Atlantic noted that all indications are confined to the intersection locations in the portion of the tube within the thickness of the tube support plates, opposite the broached tube hole lands.

As of May 23, 2002, North Atlantic found that 42 of these intersections contain axial OD Enclosure

indications. These 42 intersections are located in 15 tubes between Row 2 and Row 9 of SG D. The indications are located at tube support plates 2 through 6 on the hot leg side and 3 through 5 on the cold leg side. If a tube had an indication at a cold-leg tube support plate, it also had one or more indications at a hot-leg tube support plate. The maximum depth of the indications was estimated to be 62% through-wall (TW) using available techniques. Lengths range from 0.3 to 0.75 inches.

Based on the axial cracking indications found in SG D, North Atlantic re-trained the eddy current analysts to be sensitive to the characteristics of the signals and expanded the inspection to include 100% of the active tubes in SGs B and C. No similar degradation was found in these SGs.

Other Findings As a result of the inspections, North Atlantic plugged 13 tubes in SG A. Five were plugged due to anti-vibration bar (AVB) wear. One of the 13 plugged tubes was due to a volumetric indication above the top of the tube sheet. The volumetric indication was caused by foreign objects. As a precaution, North Atlantic plugged the tube and the seven surrounding tubes.

In addition to plugging the 15 tubes with axial indications in SG D, North Atlantic plugged 6 tubes as a result of AVB wear and one tube for a volumetric indication. The volumetric indication was near the top of the tubesheet in the periphery. The depth was measured to be 46% through-wall. The indication was attributed to a loose part. (Although no loose part was visually identified, sludge lancing may have removed the foreign object.)

North Atlantic inspected SGs B and C based on finding the crack-like indications in SG D.

North Atlantic inspected 100% of the tubes with bobbin probes, 50% of Row 1 and Row 2 U-bends with plus point probes, and tubesheet transition region with plus point probes. No crack-like indications were detected as a result of these inspections.

Tube-Pull Analysis As a result of the axial OD cracking findings, North Atlantic has pulled two tubes for metallurgical analysis to characterize the degradation and to identify its root cause. The pulled tubes contain four intersections with indications including the one with the maximum voltage amplitude and the one with the maximum measured depth. These two tubes and the rest of the affected tubes will be plugged.

North Atlantic indicated that the analysis will take about 4 weeks. As results from the root-cause analysis become available, North Atlantic will discuss them with the NRC staff.