ML20296A692
| ML20296A692 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 10/20/2020 |
| From: | Lippard G Dominion Energy South Carolina |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 20-349 SPR 2020002 | |
| Download: ML20296A692 (10) | |
Text
V.C. Summer Nuclear Station Bradham Blvd & Hwy 215, Jenkinsvill e, SC 29065 Mailing Address:
P.O. Box 88, Jenkinsville, SC 29065 Dominion Energy.com Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 October 20, 2020 DOMINION ENERGY SOUTH CAROLOINA (DESC)
VIRGIL C. SUMMER NUCLEAR STATION (VCSNS) UNIT 1
~
Dominion
~
Energy Serial No.20-349 VCS UC/BAB/Rev 0 Docket No. 50-395 License No. NPF-12 SPECIAL REPORT (SPR) 2020-002 - STEAM GENERA TOR TUBE INSPECTION REPORT Dominion Energy South Carolina (DESC) hereby submits the Steam Generator Tube Inspection Report pursuant to the requirements of Technical Specifications 6.9.1.12. This report summarizes the examination conducted during the 2020 Spring Refueling (RF-25) and the state of the three steam generators installed at V. C. Summer Nuclear Station (VCSNS), Unit 1.
Should you have any questions, please call Michael Moore at (803) 345-4752.
Sincerely, George A. Lippard Site Vice President V.C. Summer Nuclear Station Commitments contained in this letter: None
Enclosure:
RF-25 Steam Generator Tube Inspection Report cc:
G. J. Lindamood - Santee Cooper L. Dudes - NRC Region II T. Vaughn - NRC Project Mgr.
NRC Resident Inspector
1.0 Background
Steam Generator Tube Inspection Report VC Summer Nuclear Station Jenkinsville SC 29065 RF-25 Spring 2020 Serial No.20-349 Docket No. 50-395
Enclosure:
Page 1 of 9 Commissioned in January 1984, VC Summer originally had three Westinghouse Model D3 steam generators. The original steam generators (SGs) were replaced with Westinghouse Delta-75 steam generators in the fall of 1994.
Each of the replacement steam generators contains 6307 thermally treated alloy 690 tubes with an outside diameter of 0.6875 inches and a nominal wall thickness of 0.040 inches. Stress relief was performed during fabrication on the U-bends of the first 17 rows of tubing. The straight sections of the tubing are supported by nine tube support plates made of 1.125" thick, SA-240, Type 405 stainless steel. The tube support plates (TSP) have trefoil, broached holes which reduce dryout and the collection of impurities at the tube-to-support plate intersections. The u-bend sections of the tubing are supported by four sets of anti-vibration bars (A VB) made of SA-240, Type 405 stainless steel. A flow distribution baffle (FDB) plate is located between the tubesheet and the lowest support plate. The flow distribution baffle increases the secondary side flow velocity near the tubesheet, thus reducing the accumulation of sludge at the top of the tubesheet.
The D-75 steam generators contain a sludge collector above each primary separator which is designed to reduce the accumulation of sludge at the tubesheet. The tube-to-tubesheet joints are formed by a full depth hydraulic expansion and a weld to the primary cladding on the tubesheet.
2.0 Scope of Inspections Performed on Each SG The RF-25 inspection program, as required by the EPRl PWR SG Examination Guidelines Revision 8, addressed the existing and potential degradation mechanisms for VC Summer. The defined scope included the following:
Bobbin Coil Examinations (all 3 SGs) 100% full length tube-end to tube-end Deposit mapping Top ofTubesheet sludge height reporting Monitoring for tube-to-tube wear Array Probe Examinations (all 3 SGs unless otherwise noted) 100% Hot Leg Top of the Tubesheet (TTS)
Approximately 75% Cold Leg Top of Tubesheet (TTS). This included outer 30 rows (tubesheet periphery and no-tube lane) on the Cold Leg.
2018 sludge (SLG) indications as defined by the Degradation Assessment Legacy foreign objects/possible loose parts (PLP)
RF-25 foreign objects/possible loose parts Special interest not performed by +Point'
+Point' Probe Examinations (all 3 SGs unless otherwise noted)
RF-25 Dents/Dings > 5 Volts RF-24 bulge (BLG) indications 20% Row 1 and 20% Row 2 U-bends (SGA Only)
All Array I-Codes All Bobbin I-Codes not captured by Array All permeability variations (PVN)
All foreign object wear All anti-vibration bar (A VB) wear with a corresponding dent All new dent (ONT) or ding (ONG) or bulge (BLG)
Support wear sizing and/or profiling Primary Side Visual Inspections (all 3 SGs)
Tube plugs Serial No.20-349 Docket No. 50-395
Enclosure:
Page 2 of 9 SG channel head bowl cladding and internal surfaces as recommended by Nuclear Safety Advisory Letter (NSAL) 12-1 Revision 1 Secondary Side Activities Deposit Minimization Treatment (DMT) cleaning Sludge lancing Top ofTubesheet Inspections/Foreign Object Search and Retrieval (FOSAR)
Flow Distribution Baffle (FOB) Inspections/Foreign Object Search and Retrieval (FOSAR)
Top of 9th Tube Support Plate (TSP) inspections 3.0 Degradation Mechanisms Found Existing degradation mechanisms are those mechanical or corrosive processes previously and/or currently observed in a Steam Generator. The existing degradation mechanisms within the VC Summer replacement steam generators are outlined below.
3.1 Anti-Vibration Bar (AVB) Wear Wear related to tube interaction with A VB supports results from flow-induced vibration in the upper bundle. This mechanical process is related to the tightness of the upper bundle assembly as expressed in the distribution of tube-to-A VB gaps. Indications of A VB wear in the replacement steam generators were first reported during RF-12. There were five (5) instances of A VB wear reported in RF-25. Three (3)
A VB wear indications were reported in SGA, one (1) indication in SGB, and one (1) indication in SGC.
Of these, there was one (1) new A VB wear indication (SGB) and four (4) repeat indications. The maximum depth of repeat A VB wear was 13%TW. The maximum depth of new AVB wear was l 1%TW.
None of the A VB wear indications exceeded the Condition Monitoring (CM) limit. Table 3-1 summarizes the RF-25 inspection results for A VB wear.
Table 3-1: RF-25 Anti-Vibration Bar Wear SC Tot:al
- Reput Nenr Rep.at New Tubes / Indications Tubes / huti.c:atimis Tubts / Indi~om Max'1/4TW M.x%TW A
2 / 3 2/3 0 10 13 N/A B
l / l 0 /0 111 NIA 11 C
l / l l / l 0 / 0 6
3.2 Tube Support Plate (TSP) Wear Serial No.20-349 Docket No. 50-395
Enclosure:
Page 3 of 9 Flow-induced vibration that causes tube wear at TSPs and FOBs is governed primarily by secondary side thermal hydraulic characteristics and the geometry (sizes of the tube-to-support gaps, TSP spacing, etc.)
Tube wear at TSPs was first reported in the replacement steam generators during RF-15. In RF-25, there were forty-two (42) TSP wear indications reported in SGA, sixty-one (61) indications in SGB, and twenty-seven (27) indications in SGC. Of these, there were sixteen (16) new TSP indications and one hundred fourteen (114) repeat indications. The maximum depth of repeat TSP wear was 36%TW. The maximum depth of new TSP wear was 16%TW. None of the TSP wear indications exceeded the Condition Monitoring (CM) limit. Table 3-2 summarizes the RF-25 inspection results for TSP wear.
Table 3-2: RF-25 Tube Support Plate Wear SC Tot:al R-at New K-at New Tubes / Indications Tubes/ Indications Tubes / Indi.c.atiom Mu:o/.TW Mu.%TW A
35/42 27 /34 8 / 8 36 16 B
45 / 61 42 157 3 / 4 21 11 C
23 / 27 20 / 23 3 / 4 23 11 3.3 Flow Distribution Baffle (FDB) Wear Flow-induced vibration that causes tube wear at TSPs and FOBs is governed primarily by secondary side thermal hydraulic characteristics and the geometry (sizes of the tube-to-support gaps, TSP spacing, etc.)
Tube wear at the FOB was first reported in the replacement steam generators during RF-18. There were zero (0) FOB wear indications reported in SGA, zero (0) indications in SGB, and three (3) indications in SGC. All the FOB indications were repeat indications. The maximum depth of FOB wear was 23%TW.
None of the FOB wear indications exceeded the Condition Monitoring (CM) limit. Table 3-3 summarizes the RF-25 inspection results for FOB wear.
Table 3-3: RF-25 Flow Distribution Baffle Wear SC Total R-at New Repeat New Tubes / Indications Tubes / Indications Tubes / Indi.c.atiom Mu:%1'W Mu.%TW A
0 / 0 0 / 0 0 / 0 NIA NIA B
0 / 0 0 / 0 0 /0 NIA NIA C
3/ 3 3/ 3 0 / 0 23 NIA 3.4 Foreign Object Wear Foreign objects may enter the SGs through the feedwater stream and may cause tube wear. Foreign object wear was only detected in SGB during RF-25; however, this was a repeat indication with no increase in depth, which was expected since no part was found at the affected tube location during RF-24. The depth of this wear indication reported at RF-25 was 26%TW, showing no growth over cycle 25 as expected. In summary, no new foreign object wear was detected in any SG at RF-25. Table 3-4 summarizes the RF-25 inspection results for foreign object wear.
Table 3-4: RF-25 Foreign Object Wear SC Tot:al R-at New L11eat New Tubes / Indications Tubes / Indications Tubes / Indi.c.atiom Mu: o/.TW Mu.%TW A
0 / 0 0 /0 0 / 0 NIA N/A B
l /1 l /1 0 /0 26 N/A C
0 / 0 i0/ 0 0 / 0 NIA N/A
4.0 NDE Techniques for each Degradation Mechanism Serial No.20-349 Docket No. 50-395
Enclosure:
Page 4 of 9 Examination Technique Specification Sheets (ETSS) identified in the RF-25 Degradation Assessment for each previously discussed degradation mechanism are identified in Table 4-1.
a e - :
u e T bl 41 SGT b D egra a 10n ec d f M h amsms an dA ssoc1a e ec mques
. t dNDET h.
Degradation Probe EPRIETSS Demonstrated Extended Applicability Mechanism(s)
Applicability 96041.1 (Rev. 6)
AVBs None Appendix I Bobbin Support Wear 96042.1 (Rev. 4)
Drilled TSPs None Appendix I 96004.1 (Rev. 13)
A VBs and TSPs None Foreign Object Bobbin 27091.2 (Rev. 2)
Freespan Foreign Detection of foreign object Object Wear (Part Not wear with part present and Wear Present) detection of foreign objects
+Point' 10908.5 (Rev. 0)
AVBs Sizing ofFO wear with Appendix. I part present AVB Wear 17909.1 (Rev. 1)-Ax.
Array 17909.4 (Rev. 1)-Circ.
AVBs None Appendix I FDB wear ( drilled
+Point' 96910.1 (Rev. 11)
Broached TSP wear supports) and sizing ofFO TSP/FOB Wear wear when part is present 11956.3 (Rev 3)-Ax.
FDB wear ( drilled) and FO Array 11956.4 (Rev 3) - Circ.
Broached TSP wear wear with or without part Appendix I present 27901.1 (Rev. 1)
Circ groove, PLP wear PLP wear at TTS and TSP (part not present)
(part present) 27902.1 (Rev. 2)
Axial Groove, PLP PLP wear at TTS and TSP wear (part not present)
(part present) 27903.1 (Rev. 1)
Tapered football, PLP PLP wear at TTS and TSP wear (part not present)
( part present)
Foreign Object Tapered round hole, PLP wear at TTS and TSP
+Point' 27904.1 (Rev. 2)
PLP wear (part not Wear present)
(part present) 27905.1 (Rev. 2)
Flat wear, PLP wear PLP wear at TTS and TSP (part not present)
(part present) 27906.1 (Rev. 1)
Tapered wear, PLP PLP wear at TTS and TSP wear (part not present)
(part present) 27907.1 (Rev. 2) 45° tapered wear, PLP PLP wear at TTS and TSP wear (part not present)
(part present) 17901.1 (Rev. 0)-Ax.
Circ groove, PLP wear PLP wear at TTS and 17901.3 (Rev. 0)- Cir.
(part not present) in the supports (part present).
freespan 17902.1 (Rev. 0)-Ax.
Axial groove, PLP wear PLP wear at TTS and Foreign Object (part not present) in the Wear / Pitting Array 17902.3 (Rev. 0) - Cir.
freespan supports (part present).
17903.1 (Rev. 0)-Ax.
Tapered football, PLP PLP wear at ITS and wear (part not present) 17903.3 (Rev. 0)- Cir.
in the freespan supports (part present).
17904.1 (Rev. 0)-Ax.
Tapered round hole, PLP wear at TTS and
17904.3 (Rev. 0) - Cir.
PLP wear (part not present) in the freespan 17905.1 (Rev. 0)-Ax.
Flat wear, PLP wear 17905.3 (Rev. 0) - Cir.
(part not present) in the freespan 17906.1 (Rev. 0) -Ax.
Tapered wear, PLP 17906.3 (Rev. 0)-Cir.
wear (part not present) in the freespan Serial No.20-349 Docket No. 50-395
Enclosure:
Page 5 of 9 supports (part present).
PLP wear at TTS and supports (part present).
PLP wear at TIS and supports (part present).
5.0 Location, Orientation (if linear), and Measured Sizes (if available) of Service Induced Indications Tables 5-1, 5-2, 5-3, and 5-4 provide the location and measured sizes of service induced indications relative to each degradation mechanism. The majority of the indications were from tube support plate wear.
Table 5-1: RF-25 Anti-Vibration Bar Wear SG Row Col Volts Deg
%TW Location A
19 140 0.17 90 13 AV7 +0.25 A
26 139 0.15 84 12 AV7+0.77 A
26 139 0.12 136 10 AV2-0.78 B
90 29 0.16 97 11 AV2 +0.09 C
26 3
0.14 112 6
AV2-0.56 a e - :
u e uppor T bl 5 2 RF 25 T b S tPl t W a e ear SG Row Col Volts Dee:
%TW Location A
1 10 0.23 95 18 06C-0.60 A
1 10 0.40 111 25 05C-0.09 A
1 10 0.20 69 16 04C -0.11 A
1 16 0.09 60 9
05C -0.57 A
1 52 0.11 63 10 04C -0.52 A
1 58 0.12 100 11 03C -0.53 A
1 60 0.25 111 19 03C +0.46 A
1 60 0.11 99 10 03C -0.55 A
1 66 0.18 94 15 03C +0.41 A
1 78 0.21 75 16 06C-0.05 A
1 82 0.14 123 12 03C-0.60 A
1 88 0.27 96 20 07C -0.07 A
2 1
0.24 142 19 07C -0.71 A
2 3
0.12 129 10 07C +0.39 A
2 5
0.13 103 12 05C-0.60 A
2 59 0.17 54 14 07C-0.05 A
2 77 0.88 110 36 07C-0.07 A
2 77 0.21 78 17 08C -0.07 A
2 77 0.14 49 13 08H +0.48 A
2 77 0.73 114 34 08H-0.48 A
2 79 0.22 84 17 07C -0.07 A
2 87 0.20 59 16 07C -0.07
A 3
54 A
3 66 A
3 108 A
3 140 A
4 81 A
4 99 A
4 103 A
4 103 A
6 1
A 6
93 A
8 131 A
17 2
A 61 12 A
67 24 A
77 122 A
91 28 A
96 55 A
101 62 A
115 62 A
115 72 B
1 2
B 1
2 B
1 2
B 1
2 B
1 14 B
1 28 B
1 28 B
1 140 B
1 140 B
2 17 B
2 31 B
2 31 B
2 61 B
2 111 B
2 113 B
2 113 B
3 4
B 3
46 B
3 46 B
3 54 B
3 76 B
3 80 B
3 84 B
3 88 B
3 90 B
3 112 B
4 117 B
5 84 B
5 88 0.16 66 0.24 95 0.21 129 0.14 34 0.12 116 0.16 60 0.15 73 0.12 23 0.17 35 0.15 135 0.10 48 0.21 108 0.13 93 0.16 85 0.21 87 0.20 97 0.16 99 0.12 55 0.16 88 0.14 105 0.20 120 0.16 109 0.18 127 0.05 45 0.20 108 0.09 82 0.16 86 0.16 127 0.09 37 0.10 45 0.15 110 0.22 121 0.12 68 0.19 101 0.32 105 0.30 93 0.15 113 0.23 118 0.40 108 0.16 89 0.12 105 0.26 120 0.30 112 0.27 117 0.17 86 0.19 137 0.13 104 0.13 149 0.08 53 13 17 17 13 11 14 13 11 13 12 12 16 11 13 15 15 16 13 12 15 15 12 13 4
15 8
13 13 8
9 12 16 10 14 20 19 10 14 21 10 8
15 17 16 11 13 9
12 8
Serial No.20-349 Docket No. 50-395
Enclosure:
Page 6 of 9 07C +0.41 08C +0.00 05C +0.35 07C +0.30 07C +0.41 05C +0.42 05C +0.42 05C -0.58 04C -0.57 05C +0.44 06C +0.50 05C +0.32 04C -0.62 07C +0.40 07C +0.37 07C -0.65 06C -0.46 08C +0.48 09H +0.40 08C +0.39 06C +0.37 06C -0.69 05C +0.35 05C-0.64 07H-0.55 07H +0.41 07H-0.57 06C +0.39 06C -0.65 07H +0.44 06C +0.44 05C +0.39 04C-0.57 07C +0.44 06C +0.00 07C +0.00 06C -0.65 08C -0.40 07C -0.46 06C +0.44 07C -0.58 06C +0.37 07C +0.44 07C -0.42 07C +0.42 07C +0.51 07C +0.44 07C +0.44 05C -0.49
B 5
88 0.22 B
5 88 0.11 B
5 88 0.09 B
5 88 0.10 B
5 90 0.08 B
5 90 0.08 B
5 90 0.15 B
5 90 0.16 B
5 116 0.16 B
6 75 0.11 B
6 125 0.11 B
10 121 0.07 B
10 121 0.06 B
12 139 0.12 B
20 139 0.15 B
34 9
0.11 B
39 120 0.08 B
45 12 0.12 B
54 121 0.10 B
56 11 0.15 B
64 13 0.16 B
69 126 0.09 B
94 45 0.08 B
95 110 0.11 B
99 44 0.10 B
99 106 0.08 B
108 47 0.11 B
108 47 0.09 B
108 63 0.10 B
110 89 0.09 B
114 75 0.09 B
115 74 0.15 C
1 4
0.09 C
1 8
0.17 C
1 16 0.11 C
1 16 0.10 C
1 82 0.15 C
1 94 0.32 C
1 112 0.23 C
1 112 0.16 C
2 137 0.06 C
5 52 0.31 C
6 25 0.12 C
6 25 0.15 C
6 107 0.16 C
7 54 0.25 C
25 36 0.25 C
30 137 0.19 C
48 15 0.13 95 18 83 11 94 9
103 10 54 8
82 8
113 13 105 14 105 14 36 11 59 11 60 7
51 6
149 11 141 13 98 11 132 8
104 12 43 10 46 14 136 14 82 9
160 8
93 11 147 10 34 8
124 11 75 9
82 10 26 9
101 9
118 14 93 7
81 12 61 8
75 8
83 9
123 17 91 15 98 11 38 5
100 14 38 8
49 9
31 8
136 12 104 14 45 9
42 8
Serial No.20-349 Docket No. 50-395
Enclosure:
Page 7 of 9 07C -0.46 07C +0.55 08C -0.42 08C +0.46 07C -0.46 08C -0.46 07C +0.53 08C +0.50 07C +0.53 07C -0.46 05C +0.60 08C -0.53 08C +0.65 06C-0.58 03H-0.63 06C +0.49 08C +0.51 03H -0.56 07C -0.49 03H -0.63 07C +0.37 07C +0.45 09C +0.45 08C -0.58 09C +0.49 07C -0.58 07H +0.35 07H -0.70 08C +0.49 08C -0.61 04H +0.40 06H +0.37 06C +0.42 07C +0.37 06C +0.44 06C -0.51 08H +0.50 06H +0.46 06C -0.55 06C +0.47 08C +0.36 06C -0.41 07C-0.48 07C +0.58 05C -0.37 06C -0.49 07C +0.61 08C +0.46 08C +0.49
C 52 19 0.15 101 C
82 113 0.13 55 C
83 116 0.25 139 C
104 55 0.53 147 C
104 67 0.17 51 C
105 78 0.24 113 C
105 78 0.15 40 C
107 98 0.12 118 C
110 73 0.43 124 C
114 83 0.11 32 Table 5-3: RF-25 Flow Distribution Baffle Wear SG Row Col Volts De2 C
32 89 0.29 141 C
34 91 0.16 130 C
35 92 0.70 116 SG Row Col Volts B
92 87 0.16 6.0 Tubes Plugged during the Inspection Outage 10 9
12 23 11 11 8
7 21 7
%TW 13 8
23
%TW 26 Serial No.20-349 Docket No. 50-395
Enclosure:
Page 8 of 9 08C +0.56 07C -0.56 07C -0.56 08C +0.42 08C -0.53 07C -0.51 08C +0.49 08C +0.44 08C +0.44 09H +0.42 Location BPH +0.41 BPH +0.44 BPH +0.44 Location TSH+0.03 During RF-25, four (4) tubes total were removed from service, by plugging. Two (2) tubes were preventively plugged due to Tube Support Plate (TSP) Wear indications. Neither of these two (2) tubes had indications that exceeded the 40% plugging criteria. The remaining two (2) tubes were plugged due to possible loose parts (PLPs) whose locations were not accessible via inspection or foreign object search and retrieval. Table 6-1 identifies RF-25 tube plugging.
T bl 6 1 RF 25 T b Pl a e - :
u e U!!!!llll.?:
Tube Degradation Steam Generator A
B C
TSP Wear 2
0 0
Possible Loose Part 1
1 0
RF-25 Tubes Plu1med 3
1 0
7.0 Number and Percentage of Tubes Plugged to Date A total of twenty-two (22) tubes have been plugged in all three of the VC Summer Steam Generators as shown in Table 7-1. Each steam generator has a total of 63 07 tubes.
a e - :
T bl 7 1 VC S ummer e a um ero u es D It 75 N
b fT b Pl u22e d Outage Steam Generator A
B C
Pre-Service (1994) 0 1
2 RF-12 (Fall 2000) 3 0
2 RF-24 (Fall 2018) 7 1
2
RF-25 (Spring 2020) 3 Total Tubes Plu1n!ed 13 Total Percentage 0.206%
(Total DlU2'2'ed/6307) 1 3
0.0476%
0 6
Serial No.20-349 Docket No. 50-395
Enclosure:
Page 9 of 9 0.095%
8.0 Results of Condition Monitoring, including the results of Tube Pulls and In-Situ Testing All degradation identified during RF-25 inspection satisfied condition monitoring requirements for SG tube structural and leakage integrity. Therefore, tube pulls and in-situ pressure testing were not necessary.
9.0 References 9.1 V.C. Summer 1RF25 Steam Generator Degradation Assessment (Spring 2020) 9.2 VC Summer 1RF25 Steam Generator Condition Monitoring and Final Operational Assessment 9.3 VC Summer 1RF25 Steam Generator Eddy Current Final Report