NRC 2022-0015, Fall 2021 Unit 2 (U2R38) Steam Generator Tube Inspection Report
| ML22117A172 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 04/27/2022 |
| From: | Schultz E Point Beach |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC 2022-0015 | |
| Download: ML22117A172 (7) | |
Text
April 27, 2022 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 2 Docket 50-301 Renewed License No. DPR-27 Fall 2021 Unit 2 (U2R38)
Steam Generator Tube Inspection Report NRC 2022-0015 TS 5.6.8 Pursuant to the requirements of Point Beach Nuclear Plant (PBNP) Technical Specification, TS 5.6.8 "Steam Generator Tube Inspection Report," NextEra Energy Point Beach, LLC is submitting the 180-day Steam Generator Tube Inspection Report. The enclosure to this letter provides the results of the fall 2021, Unit 2 (U2R38) steam generator tube inspections.
If you have questions or require additional information, please contact me at 920-755-7854.
Sincerely, NextEra Energy Point Beach, LLC Eric Schultz Licensing Manager Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW NextEra Energy Point Beach, LLC 6610 Nuclear Road, Two Rivers, WI 54241
Document Control Desk Page 2 ENCLOSURE 1 NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNIT 2 FALL 2021 UNIT 2 (U2R38)
STEAM GENERATOR TUBE INSPECTION REPORT 5 pages follow
Enclosure Point Beach Unit 2 U2R38 Steam Generator Tube Inspection Report
==
Introduction:==
NRC 2022-0015 Page 1 of 5 The enclosed Steam Generator Tube Inspection Report for Point Beach Unit 2 is submitted for the inspection of the SGs during refueling outage 38 (hereafter referred to as the U2R38 inspection or outage), as required by Technical Specification section 5.6.8. The inspection in U2R38 was performed in accordance with Technical Specification 5.5.8, and was the 3rd (and last) inspection of the SGs in the 2nd ISi period. The previous inspection of the SGs was completed in U2R35 (Spring 2017). References to past SG Tube Inspection Reports for Point Beach Unit 2 provided in Appendix A along with a list of acronyms used in this report. At unit shutdown for the U2R38 inspection, the SGs had operated for approximately 21.4 EFPY since installation and 102.0 EFPM in the 2nd ISi period.
This included operation for approximately 17.6 EFPM, 16.4 EFPM and 18.0 EFPM in the last 3 consecutive fuel cycles, respectively, since the last SG inspection. Initial entry into Mode 4 following completion of the U2R38 inspection was made on October 30, 2021.
Point Beach Unit 2 is a Westinghouse 2-loop PWR with Model Delta 47F steam generators. The SGs are U-tube heat exchangers with tube bundles fabricated using thermally treated Alloy 690 tubing. Each SG contains 3,499 tubes arranged in 86 rows and 105 columns with a triangular pitch configuration.
Nominal tube OD is 0.875 inch with a 0.050-inch nominal wall thickness. Each SG tube bundle is supported by one flow distribution baffle (FDB) and 7 trefoil-shaped, broached-hole tube support plates (TSPs) all fabricated from stainless steel. Three (3) sets of stainless-steel anti-vibration bars (AVBs) in the U-bends also provide tube bundle support. Rows 1-14 of tubing in each SG were stress relieved in the U-bend region after bending.
A. Scope of Inspections Performed on each SG The U2R38 inspection scope was selected to meet the requirements of the plant Technical Specifications, NEI 97-06 Rev 3 and its referenced EPRI SGMP Guidelines. In addition, Point Beach intends to submit a License Amendment Request (LAR) to adopt "Revised Frequencies for Steam Generator Tube Inspections" (TSTF-577 Rev. 1) 1. SG inspections in U2R38 will be credited during the LAR process as the implementation outage for TSTF-577 Rev. 1; therefore, the scope of inspections performed was also selected to meet the requirements therein. Unless otherwise noted, the U2R38 base scope inspection in each SG was:
Primary-side:
- 100% full-length bobbin probe exams of all active tubes except low row U-bends (rows 1 & 2).
- Low row U-bends were inspected with the +Point' probe between the uppermost TSP on the HL and the CL.
- Peripheral tube inspection with the +Point' probe: 3 outermost tubes exposed to the annulus, and rows 1-4 along the no-tube lane in the HL and CL. The test extent was from the TTS +/- 3 inches.
- Various diagnostic/special interest exams using the +Point' probe including all I-codes from bobbin probe exams, tubes in the vicinity of newly identified or prior PLPs, tubes adjacent to the locations of known foreign objects, tubes with new ding/dent signals and tubes with HL tubesheet BLG/OXP signals.
- Visual inspection of all mechanical or welded plugs.
1 TSTF-577 Rev. 1, "Revised Frequencies for Steam Generator Tube Inspections", NRC ADAMS Accession No. ML21099A086.
Enclosure NRC 2022-0015 Page 2 of 5
- Visual inspection of all channel head bowl components and bowl scan everywhere within the channel head bowl with remote visual camera in both the HL and CL per Westinghouse NSAL 12-1 Rev 1, "Steam Generator Channel Head Degradation," October 2017.
Secondary-side:
- Cleanliness inspection at the TTS (annulus, no-tube lane) after sludge lancing.
- Foreign object search and recovery (FOSAR) at the TTS incl.uding in-bundle exams.
- Visual inspection of components of the Upper Internals including the feedwater ring and supports, and moisture separator components.
- 8. Degradation Mechanisms Found The following degradation mechanisms were identified during the U2R38 inspection:
- Wear at AVB contact points.
- Wear at broached TSPs.
No new degradation mechanism was identified. No corrosion damage mechanism was found.
Inspection Expansion: None required.
C. NOE Techniques utilized for each Degradation Mechanism Table 1 a is the list of the EPRI ETSSs used for degradation detection during the U2R38 ECT inspection.
Table 1a - NOE Detection Techniques for Degradation Mechanisms Detection ETSS used for Detection Degradation Location I Applicability probe Mechanism 96041.1Rev3 AVB locations Bobbin 96004.1 Rev 13 TSP and FOB locations 27091.2 Rev 2 Wear Due to foreign objects 21998.1 Rev 4
+Point' 96910.1Rev11 TSP and FOB locations Bobbin 24013.1 Rev 2 At Dents/Dings ~ 5V 10013.1 Rev 1 22401.1 Rev 4 ODSCC 21409.1 Rev 7 At Dents/Dings > 5V
+Point' 21410.1 Rev 6 21998.1 Rev 4 Diagnostic low row U-bends (Rows 1 & 2) inspection Table 1 b is the list of the EPRI ETSSs used for degradation sizing based on the degradation mechanisms reported during the U2R38 ECT inspection.
Table 1 b - NOE Sizing Techniques for Degradation Mechanisms Sizing ETSS used for Sizing Degradation Location I Applicability orobe Mechanism Bobbin 96041.1 Rev 3 Wear AVB locations
+Point' 96910.1 Rev 11 At broached TSPs
Enclosure NRC 2022-0015 Page 3 of 5 D. Location, orientation (if linear), and measured sizes (if available) of service induced indications For each SG, Table 2 provides the listing of service-induced indications identified during the U2R38 inspection, including locations and measured sizes.
Table 2 - U2R38 Wear Indications SG Row Col Per Location Volts SG Row Col Per Location Volts A
1 98 5
05C
-0.58 0.13 A
50 13 4
07C
-0.64 0.09 A
1 98 7
05C 0.35 0.17 A
59 16 4
07H
-0.69 0.1 A
1 98 4
05C 0.42 0.1 A
69 22 5
06C
-0.65 0.11 A
1 98 6
04C
-0.57 0.14 A
78 59 5
AV4 0
0.11 A
1 98 4
04C 0.43 0.09 A
78 59 3
AV5 0
0.06 A
1 98 5
04C 0.45 0.11 A
79 62 9
AV3
-0.07 0.21 A
5 28 8
06C 0.46 0.2 A
79 62 7
AV4 0
0.13 A
9 56 5
04H
-0.6 0.12 A
79 66 6
AV5 0
0.12 A
11 54 4
03H
-0.62 0.1 A
82 69 4
AV1
-0.12 0.06 A
12 53 6
06H
-0.66 0.16 A
84 45 9
AV5 0
0.22 A
12 53 5
06H
-0.59 0.13 A
84 63 3
AV5
-0.05 0.05 A
13 50 4
06H
-0.66 0.11 B
1 20 5
03H
-0.51 0.15 A
13 54 4
05H
-0.63 0.1 B
1 20 6
04H
-0.62 0.19 A
13 104 4 04C
-0.66 0.08 B
1 26 10 05C
-0.51 0.26 A
13 104 7 04C 0.36 0.16 B
1 26 5
05C
-0.36 0.14 A
13 104 3 04C 0.43 0.08 B
11 52 5
06H
-0.63 0.15 A
15 64 5
05H
-0.35 0.12 B
13 40 5
06C 0.42 0.13 E. Number of tubes plugged during the inspection outage for each degradation mechanism No tubes were plugged based on the U2R38 SG inspection.
F. Number and percentage of tubes plugged to date, and the effective plugging percentage in each steam generator The number and percentage of SG tubes plugged to-date, and the effective plugging percentage in each SG are summarized in Table 3.
Table 3 - Tubes plugged to-date and effective plugging percentage SG-A SG-8 Total Tubes Plugged 0
4 4
Percent Plugged 0%
0.114%
0.057%
G. Results of Condition Monitoring, including the results of tube pulls and in-situ testing
- 1. The largest AVB wear indication reported (9% TW) was significantly less than the CM limit of 46% TW, and less than the worst-case projected AVB wear of 19% TW from the previous
Enclosure NRC 2022-0015 Page 4 of 5 operational assessment (OA). No AVB wear indication was detected in SG-B. The deepest TSP wear indication reported (10% TW) was also considerably less than the CM limit of 42% TW, and less than the worst-case projected TSP wear of 16% TW from the previous OA. In summary, CM assessment of the inspection data demonstrated that no tubes exhibited degradation more than the CM limits. There was no reported SG primary-to-secondary leakage since the last inspection. No tubes required in-situ pressure testing (ISPT) to demonstrate structural and leakage integrity. No tube pulls were performed. The U2R38 inspection results validate the projections and conclusions of the OA from the previous inspection. Therefore, all indications found in U2R38 satisfied the SG performance criteria for structural and leakage integrity of plant Technical Specifications.
- 2. Channelhead Components Visual Inspection:
Tube Plug Inspection: During the inspection of tube plugs in U2R38, all installed plugs were confirmed to be in their correct location. In addition, all plugs were found to be dry; no dripping plugs were identified. No degradation or visible signs of leakage were noted on the plugs during the visual inspection.
Other Channel head Inspections: Visual inspection of various channel head components were performed to identify degradation per guidance in Westinghouse NSAL 12-1 Rev 1, "Steam Generator Channel Head Degradation". Areas inspected include the divider plate-to-channelhead weld, the channelhead-to-tubesheet girth weld seam region, the divider plate, and all cladded surfaces of the channelhead bowl and tubesheet. No degradation of channelhead components was observed in U2R38.
- 3. Secondary-side Inspections and Maintenance:
Sludge lancing and FOSAR: A total of 18 lbs. of sludge was removed from the 2 SGs based on secondary-side cleaning in U2R38. During TTS FOSAR, 3 foreign objects (wire bristles) were retrieved from SG-2A. The remaining foreign objects (FO) consisted of small sludge rocks, scale, wire bristles, and a possible gasket material. A FO evaluation was completed for all objects identified during FOSAR which were not retrieved. No tube damage was observed in any SG during FOSAR activities.
Upper Bundle Inspection: No evidence of blockage or occlusion of the trefoil openings of the TSPs or the flow slots was observed during upper tube-bundle visual inspection in both SGs.
The tubes in the U-bend also looked clean without the buildup of debris.
Upper Internals Inspection: Visual inspections performed in both SGs (for erosion/corrosion, mechanical damage, foreign material, and unusual conditions) included accessible portions of the feedwater ring and supports and J-nozzles, and a sample of the primary moisture separators. UT thickness measurements on the feedwater ring revealed no degradation or erosion concerns. No damage or degradation was observed during the inspection of steam drum components.
Enclosure APPPENDIX A - Additional Information NRC 2022-0015 Page 5 of 5 References to SG Tube Inspection Reports (SGTIR) in the 2nct ISi period EOC#
Outaqe ADAMS Accession No.
EOC-32 U2R32 ML13140A015 EOC-35 U2R35 ML17264A354 Abbreviations and Acronyms:
AVB Anti-Vibration Bar NSAL Nuclear Safety Advisory Letter BLG Bulge OA Operational Assessment CL Cold Leg OD Outside Diameter CM Condition Monitoring ODSCC Outside Diameter SCC ONG Ding OXP Over-expansion ONT Dent Per Percent thru-wall (% TW)
ECT Eddy Current Testing PLP Possible Loose Part EFPM Effective Full Power Months SG Steam Generator EFPY Effective Full Power Years SGMP SG Management Program EOC End of Cycle TEC Tune End Cold EPRI Electric Power Research Institute TEH Tube End Hot ETSS Exam Technique Spec Sheet TS Tubesheet FOB Flow Distribution Baffle TSC Tube Sheet Cold FO Foreign Object TSH Tube Sheet Hot FOSAR Foreign Object Search and Retrieval TSP Tube Support Plate HL Hot Leg TTS Top of Tube Sheet ISPT In-Situ Pressure Test TW Through Wall NEI Nuclear Energy Institute