ML11266A010

Cycle 17 - 90-Day Inservice Inspection Summary Report

ML11266A010
Person / Time
Site:	Sequoyah
Issue date:	09/20/2011
From:	Krich R Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML11266A010 (7)

Text

Tennessee Valley Authority 1101 Market Street, LP 3R Chattanooga, Tennessee 37402-2801 R. M. Krich Vice President Nuclear Licensing September 20, 2011 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 17 Day Inservice Inspection Summary Report In accordance with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section Xl, Article IWA-6230 and Code Case N-532-4, the Tennessee Valley Authority is providing the Sequoyah Nuclear Plant, Unit 2, Inservice Inspection Summary Report within 90 days from completion of the inspections performed during the Unit 2 Cycle 17 (U2C17) refueling outage. The U2C17 refueling outage ended on June 22, 2011. Accordingly, this report is required to be submitted by September 20, 2011. The report contains the Owner's Activity Report, a list of items with flaws or relevant conditions that required evaluation for continued service (Table 1), an abstract of repair and replacement activities required for continued service (Table 2), and the evaluation of acceptability of inaccessible areas of the steel containment vessel in accordance with 10 CFR 50.55a(b)(2)(ix).

There are no regulatory commitments associated with this submittal. Should you have any questions, please contact Dan Green at (423) 751-8423.

Respectfully, R. M. Krich

Enclosure:

ASME Section Xl Inservice Inspection Summary Report, Unit 2 Cycle 17 Refueling Outage cc (Enclosure): * ..

NRC Regional Administrator-Region II NRC Senior Resident Inspector - Sequoyah Nuclear Plant printed on recycled paper

ENCLOSURE TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNIT 2 ASME SECTION XI INSERVICE INSPECTION

SUMMARY

REPORT UNIT 2 CYCLE 17 REFUELING OUTAGE

FORM OAR-i OWNER'S ACTIVITY REPORT Report Number U12C1 7 Plant SEOUOYAH NUCLEAR PLANT, P.O. Box 2000, Soddv-Daisy, TN 37384-2000 Unit No. 2 Commercial service date June 1, 1982 Refueling outage no. 17 f applicable)

Current inspection interval Third Inspection Interval (1-Z ,3. 4-. other)

Current inspection period Second InsptonPrd wltio Perio3d Edition and Addenda of Section Xl applicable to the inspection plans 2001 Edition, 2003 Addenda Date and revision of inspection plans August 15, 2011 SI-DXI-000. 114.3, Revisions 13 through 16 Edition and Addenda of Section X) applicable to repair/replacement activities, if different than the inspection plans Not Applicable Code Cases used: N-460, N-513-2. N-526. N-532-4, N-566-2, N-586-1, N-658, N-686-1, N-695, N-706-1, N-722, N-729-1 CERTIFICATE OF CONFORMANCE I certify that (a) the statements made in this report are correct, (b) the examinations and tests meet the Inspection Plan required by the ASME Code XI and (c) the repair/replacement activities and evaluations supporting the completion of U2C17 conform to there rr mnts of Section. trefue*nag outage number)

• Signed . 7 Date Iz".\

S oesiaee.

"G"evs Title CERTIFICATE OF INSERVICE INSPECTION I, the undersigned, heoding a valid commission issued by the National Board of Boiler and Pressure Vessel Inspectors and the State or Province of Tennessee and employed by H.S.B. Global Standards of Connecticut have inspected the items described in this Owner's Activity Report, and state thai, to the best of my knowledge and belief, the Owner has performed all activities represented by this report in accordance with the requirements of Section X1.

By signing this certificate neither the Inspector nor his employer make any warranty, expressed or implied, concerning the repair/replacement activities and evaluation described in this report. Furthermore, neither the Inspector nor his employer shall be liable in manner fo onal injury or property damage or a loss of any kind arising from or connected with this inspection.

Commissions I"e National i t 13 /, Ir, -,v'zy Insyearr's Sgnaure Board,State, Province,and Encnrsewents Date  ! /5- 2-,01 E-1

ASME SECTION Xl INSERVICE INSPECTION

SUMMARY

REPORT SEQUOYAH NUCLEAR PLANT, UNIT 2 CYCLE 17 REFUELING OUTAGE TABLE I ITEMS WITH FLAWS OR RELEVANT CONDITIONS THAT REQUIRED EVALUATION FOR CONTINUED SERVICE Examination Category and Item Description Evaluation Description Item Number Pitting, gouges, and minor surface corrosion Engineering evaluation, acceptable on the steel containment vessel (SCV) as-is. Pit depth measurements and surface (NOI # 2-SQ-414, -415, -416, and ultrasonic test (UT) measurements

-417) confirmed acceptability of flaws.

Engineering evaluation, acceptable F-A, F1.20 Safety Injection (SI) System spring can as-is. Adjustment performed to setting found out of range (NOI # 2-SQ-412) maintain design configuration.

Auxiliary Feedwater System pipe clamp Engineering evaluation, acceptable F-A, Fl1.30 miaindfo misaligned etcl(O -Q4 from vertical (NOI # 2-SQ-410)

) as-is. Measurement confirmed the support is within the allowable angle.

Engineering evaluation, acceptable Fl .30 Component Cooling System spring can as-is. Spring setting acceptance F-A, setting found out of range (NOI # 2-SQ-41 1) range was found to be incorrect.

Calculation was revised.

Sealant removed for base metal SCV Moisture Barrier sealant dis-bonded inspection. Engineering evaluation E-A, E1.30 from SCV surface (NOI # 2-SQ-409) of SCV, acceptable as-is. New sealant applied to prevent moisture intrusion.

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ASME SECTION Xl INSERVICE INSPECTION

SUMMARY

REPORT SEQUOYAH NUCLEAR PLANT, UNIT 2 CYCLE 17 REFUELING OUTAGE TABLE 2 ABSTRACT OF REPAIRS, REPLACEMENTS, OR CORRECTIVE MEASURES REQUIRED FOR CONTINUED SERVICE Code Item Description Date Repair/Replacement Class Description of Work Completed Plan Number 2B SI Pump Room Cooler Replace cooler coil due to tube leak 6/18/2011 111391970 Residual Heat Repair snubber support bracket 2 Removal System due to cracked weld 6/6/2011 112318040 Snubber Support Essential Raw Replace pipe due to 3 Cooling Water microbiologically induced corrosion 10/29/2010 111396552 System piping leak I E-3

ASME SECTION XI INSERVICE INSPECTION

SUMMARY

REPORT SEQUOYAH NUCLEAR PLANT, UNIT 2 CYCLE 17 REFUELING OUTAGE REPORTING REQUIRED BY 10 CFR 50.55a(b)(2)(ix)

ASME Section XI, Subsection IWE Steel Containment Vessel Inspection Program 10 CFR 50.55a(b)(2)(ix) requires the reporting of inaccessible areas and additional examinations identified during the performance of the ASME Section Xl, Subsection IWE Steel Containment Vessel (SCV) Inspection Program when conditions exist in accessible areas that could indicate the presence of or result in degradation to such inaccessible areas.

During the Unit 2 Cycle 17 refueling outage inspection of the Steel Containment Moisture Barrier (Item Number E1.30) numerous indications were identified in the SCV moisture barrier sealant (caulk) at the interface of the SCV and the Raceway floor in which the sealant has un-bonded from the SCV surface. Failure of this moisture barrier sealant creates a condition in which moisture could be allowed to penetrate the seal, and cause corrosion damage to the underlying SCV surface. Due to this potential, the sealant was removed at 22 specific locations to perform additional examinations of the otherwise inaccessible SCV surfaces. These additional non-code examinations were performed to evaluate the acceptability of the inaccessible areas in accordance with 10 CFR 50.55a (b)(2)(ix)(A).

Results of the visual examinations and UT examinations, described below, show all areas are acceptable for continued operation with no corrective action required. Since no additional corrosion is expected after the sealant is reinstalled, an evaluation of future corrosion rates and wall thickness effects is not required. All damaged areas of the moisture barrier sealant were repaired, and do not require an engineering evaluation.

Future inspections of the SCV moisture barrier will continue to be performed in accordance with the ASME Code,Section XI, IWE-2500-1 schedule.

1. Azimuth 71 degrees - approximately 3-inch long area of un-bonding between the sealant and the SCV surface: Sealant was removed along a length of approximately 3 inches. Visual inspection of the underlying SCV surface identified no corrosion damage. Therefore, UT thickness measurements were not taken at this location. SCV sealant was reinstalled to prevent future moisture intrusion. No additional corrective actions are required.

2. Azimuth 165 degrees - approximately 4-inch long area of un-bonding between the sealant and the SCV surface: Sealant was removed along a length of approximately 9 inches. Surface rust and minor pitting was visible on the SCV surface. UT thickness measurements and pit depth measurements were taken to validate the remaining wall thickness in the excavated area. Examinations (calculated as measured wall minus measured pit depth) identified a minimum wall thickness of approximately 1.377 inches in the excavated area. The nominal wall thickness (used for stress calculations) for the SCV plate at this location is 1.25 inches. The surface was prepared and recoated in accordance with existing procedures prior to installation of SCV sealant to prevent future moisture intrusion. No additional corrective actions are required.

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3. Azimuth 179 degrees - approximately 2-1/2-inch long area of un-bonding between the sealant and the SCV surface: Sealant was removed along a length of approximately 45 inches. Surface rust was visible on the SCV surface, but no visible pitting was observed. UT thickness measurements were taken to validate the remaining wall thickness in the excavated area. Examinations identified a minimum measured wall thickness of approximately 1.435 inches in the excavated area. The nominal wall thickness (used for stress calculations) for the SCV plate at this location is 1.25 inches. The surface was prepared and recoated in accordance with existing procedures prior to installation of SCV sealant to prevent future moisture intrusion. No additional corrective actions are required.

4. Azimuth 183 degrees - approximately 2-1/2-inch long area of un-bonding between the sealant and the SCV surface: Sealant was removed along a length of approximately 8 inches. Surface rust was visible on the SCV surface, but no visible pitting was observed. UT thickness measurements were taken to validate the remaining wall thickness in the excavated area. Examinations identified a minimum measured wall thickness of approximately 1.455 inches in the excavated area. The nominal wall thickness (used for stress calculations) for the SCV plate at this location is 1.25 inches. The surface was prepared and recoated in accordance with existing procedures prior to installation of SCV sealant to prevent future moisture intrusion. No additional corrective actions are required.

5. Azimuth 200 degrees - approximately 2-1/2-inch long area of un-bonding between the sealant and the SCV surface: Sealant was removed along a length of approximately 7-1/2 inches. Surface rust was visible on the SCV surface, but no visible pitting was observed. UT thickness measurements were taken to validate the remaining wall thickness in the excavated area. Examinations identified a minimum measured wall thickness of approximately 1.439 inches in the excavated area. The nominal wall thickness (used for stress calculations) for the SCV plate at this location is 1.25 inches. The surface was prepared and recoated in accordance with existing procedures prior to installation of SCV sealant to prevent future moisture intrusion. No additional corrective actions are required.

6-22. Multiple locations of minor un-bonding between the sealant and the SCV surface:

Specific locations are identified in NOI 2-SQ-409. Damaged sealant was removed, as required, from each of these locations to allow additional inspection.

Visual inspection of the underlying SCV surface identified minor surface rust with no corrosion damage. Therefore, UT thickness measurements were not taken at these locations. The surface was prepared and recoated in accordance with existing procedures prior to installation of SCV sealant to prevent future moisture intrusion. No additional corrective actions are required.

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