ML13165A050

Cycle 18 - 180-Day Steam Generator Tube Inspection Report

ML13165A050
Person / Time
Site:	Sequoyah
Issue date:	06/11/2013
From:	James Shea Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML13165A050 (8)

Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 June 11, 2013 10 CFR 50.4 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Unit 2 Facility Operating License No. DPR-79 NRC Docket No. 50-328

Subject:

Unit 2 Cycle 18 - 180-Day Steam Generator Tube Inspection Report In accordance with Sequoyah Nuclear Plant, Unit 2, Technical Specification (TS) 6.9.1.16.1, "Steam Generator (SG) Tube Inspection Report," Tennessee Valley Authority is submitting the 180-day SG tube inspection report. This report is required to be submitted within 180 days after initial entry into Mode 4 following completion of inspection activities performed in accordance with TS 6.8.4.k, "Steam Generator (SG) Program," and includes the results of inservice inspections performed on Unit 2 SGs during the SQN Unit 2 Cycle 18 refueling outage. Initial entry into Mode 4 following the SG tube inspection activities performed during the Unit 2 Cycle 18 refueling outage occurred on December 29, 2012.

There are no commitments contained in this letter. If you have any questions concerning this report, please contact Clyde Mackaman at (423) 751-2834.

Respectfully, J. W. Shea Vice President, Nuclear Licensing

Enclosure:

Unit 2 Cycle 18 - 180-Day Steam Generator Tube Inspection Report cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Sequoyah Nuclear Plant Printed on recycled paper Th~o c

ENCLOSURE TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT UNIT 2 CYCLE 18 180-DAY STEAM GENERATOR TUBE INSPECTION REPORT

Tennessee Valley Authority Sequoyah Nuclear Plant Unit 2 Refueling 18 Steam Generator 180 Day Report Revision 0 Prepared by

"/ Grator Specialist Gveam Reviewed by: .4 sV ae t

-SteamGeeator Specialist Reviewed by:, k A' TVA Eddy (urrest Level III 13' Approved by: ato G2er>. orMng -- 013 Steam Generator Program Mana'ger

SQN Unit 2 Refueling 18 180 Day Report In accordance with Sequoyah Unit 2 Technical Specifications 6.8.4.k "Steam Generator Program" and 6.9.1.16.1 "Steam Generator Tube Inspection Report" this report documents the results of the Unit 2 Cycle 18 replacement steam generator (RSG) tube preservice inspection. The following questions and responses are the required scope of the 180 Day Report [5].

Acronyms 141 ADI - Absolute Drift Indication MBM - Manufacturing Burnish Mark ADS - Absolute Drift Signal NDE - Nondestructive Examination ATSG - Advanced Tube Support Grid NDF - No Degradation Found BLG - Bulge Signal PVN - Permeability Variation CL - Cold Leg PLP - Possible Loose Part CTS - Cold Leg Top of Tubesheet RSG - Replacement Steam Generator DF1 - Differential Freespan Indication SG - Steam Generator DFS - Differential Freespan Signal SQN - Sequoyah DNG - Ding TTS - Top of Tubesheet FOSAR - Foreign Object Search and TVA - Tennessee Valley Authority Retrieval UB - U Bend GEO - Geometric Vpp - Voltage Peak to Peak HL - Hot Leg HTS - Hot Leg Top of Tubesheet

1. The scope of inspections performed on each SG.

The Sequoyah Unit 2 Replacement Model 57 AG+ steam generators were designed by Westinghouse and fabricated by Doosan Heavy Industries. There are 4,983 U-bend Inconel 690 tubes in each of the 4 steam generators with nominal dimensions of 0.750" O.D. X 0.043" wall thickness. A full length examination of 100% of the steam generator tubes was performed using 0.610" diameter bobbin probe. Motorized pancake/Plus Point testing was used for detection of anomalies in the tube sheet region hot leg side (TTS, +3 inches to -3 inches) and for further evaluation of detected bobbin indications. Plus Point examination was also used in the first four rows in the U-bend region.

The Special interest Plus Point exams were performed on Dings 2 volts or greater, and "I" code, PVN, PLP, BLG, and selected support structures.

Plus Point examination was performed on a sample of 50 intersections across all four steam generators at various ATSG locations of interest. These exams were for information only, and they are not required by the industry guidelines. This selection of

SQN Unit 2 Refueling 18 180 Day Report exams will be used to provide eddy current data at various locations near internal bundle features to give analysts a baseline signal to evaluate for the ATSG structure. [1][2][61 EDDY CURRENT EXAM TYPE RSGI RSG2 RSG3 RSG4 Total 610 Full Length Bobbin Coil Row 5 and above 4735 4735 4735 4735 18940 610 Candy Cane Bobbin Row 1-4 248 248 248 248 992 610 Straight Length Bobbin Row 1-4 248 248. 248 248 992 610 Top of Tubesheet Plus Point HL 4983 4983 4983 4983 19932 Low Row U-Bend Plus Point Row 1-4 248 248 248 248 992 HL Special Interest Plus Point 23 15 23 24 85 CL Special Interest Plus Point 2 3 8 9 22 UB Special Interest Plus Point 22 13 3 7 45 Total Exam Completed 10509 10493 10496 10502 42000

2. Active degradation mechanisms found.

No active degradation mechanisms were found.

3. Nondestructive Examination (NDE) Techniques used for each degradation mechanism.

Degradation Mechanism Detection Technique U-Bend/Vertical Strap Wear Bobbin Horizontal/Tube Support Grid Wear Bobbin Foreign Object Wear Bobbin Volumetric Lap Signals Bobbin Manufacturing Burnish Marks Bobbin Motorized pancake/Plus Point testing was used for detection of anomalies in the tube sheet region hot leg side (TTS, +3 inches to -3 inches) and for further evaluation of detected bobbin indications. Plus Point examination was also used in the first four rows in the U-bend region. Special interest Plus Point exams were performed on Dings 2 volts or greater, "I" code, PVN, PLP, BLG, and selected support structures. [6]

SQN Unit 2 Refueling 18 180 Day Report

4. Location, orientation (if linear), and measured sizes (if available) of service induced indications.

The U2R18 inspection was the Baseline inspection for the RSGs. No service induced indications exist at this time. 16]

This table shows the indications of interest received during bobbin inspections. [6]

SGi

_-G21 I S/G*3 SG 4* Ttaln

__0 0 00 11 DFI 6 2 14 10 32 DNG 0.5 Volts to < 2 Volts 189 181 224 201 795 DNG 2 Volts 22 9 3 16 50 GEO 2 0 0 0 2 BLG I 1 0 1 3 PLP 0 j0 1 0 1 MBM 0 0 2 0 2 PVN 0 0 0 0 0 ADI - There was 1 ADI. This indication was inspected with a rotating coil and resulted in no degradation found (NDF). The ADI type indication was changed to ADS.

DFI - There were a total of 32 differential freespan indications reported in all four steam generators. All indications were inspected with a rotating coil and dispositioned as no degradation found (NDF). The DFI's were changed to DFS.

GEO - There were a total of 2 geometric indications in 2 different tubes inspected using a rotating coil. No damage was detected in any of these tubes.

BLG - There were a total of 3 bulges reported. The bulges were identified by the bobbin probe. The reporting criteria was 2 volts or greater above the tubesheet and 18 volts or greater within the tubesheet. All bulges were tested with a rotating coil and reported no degradation found (NDF). Location of Bulges: SGI Row 3 Column 41 (18.6Vpp) CTS -9.74", SG2 Row 14 Column 50 (32.87Vpp) HTS -18.59, SG4 Row 94 Column 74 (2.18Vpp) C08 +1.59.

PLP - There was 1 very small voltage bobbin PLP indication which was tested with rotating coil and not confirmed. FOSAR identified only minor debris and dust in all 4 steam generators.

MBM - There were 2 manufacturing burnish marks (MBM's) reported.

PVN - There were no tubes identified with permeability variations.

SQN Unit 2 Refueling 18 180 Day Report DNG - There were 845 Dings reported. The reporting criteria was 0.5 volts and greater in the freespan or structure. A rotating coil inspection was conducted on dings 2 volts and greater and no degradation was found.

5. Number of tubes plugged during the inspection outage for each active degradation mechanism.

RSGI RSG2 RSG3 RSG4 Total TOTAL TUBES PLUGGED 0 0 0 0 0

6. Total number and percentage of tubes plugged to date.

The U2R1 8 outage was the replacement steam generator outage. No tubes have been plugged in the RSGs. [3]

7. The results of condition monitoring, including the results of tube pulls and in-situ testing.

Condition Monitoring was not performed because the steam generators have not been in operation. U2R18 was the baseline examination for the Unit 2 Replacement Steam Generators. [3]

8. The effective plugging percentage for all plugging in each SG.

The effective plugging percentage for all Unit 2 replacements steam generators is 0%.

SQN Unit 2 Refueling 18 180 Day Report References

1. TVA Document B85 120120 004, "Sequoyah Nuclear Plant Unit 2 Cycle 18 RSG Baseline Replacement Steam Generator Tubing Examination Pre-Service Inspection Scan Plan".

2. TVA Document B85 130207 002, "Sequoyah Nuclear Plant U2R18 Steam Generator Degradation Assessment".

3. TVA Document B85 130429 005, "Sequoyah Nuclear Plant Unit 2 Refueling 18 Steam Generator Operational Assessment".

4. TVA Document L18 120120 801, "Sequoyah Nuclear Plant-Unit 2 Replacement Steam Generator Eddy Current Examination Guideline".

5. TVA Sequoyah Unit 2 Technical Specifications Section 6.8.4.k "Steam Generator (SG) Program" and 6.9.1.16.1 "Steam Generator Tube Inspection Report".

6. Westinghouse Document MRS-FSR- 188 1-TEN, "Steam Generator Pre-Service Eddy Current Examination Report".