ML23086B917
| ML23086B917 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 03/24/2023 |
| From: | Denise Wilson Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 23-020 | |
| Download: ML23086B917 (1) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 ELECTRIC AND POWER COMPANY S
RY W
STATION NIT 1 STEAM GENERATOR TUBE INSPECTION REPORT FOR THE FALL 2022 REFUELING OUTAGE Serial No.
SS&L/MMT Docket No.
License No.23-020 RO 50-280 DPR 32 Technical Specification 6.6.A.3 for Surry Power Station Units 1 and 2 requires the submittal of a Steam Generator Tube Inspection Report to the NRC within 180 days after Tavg exceeds 200°F following completion of an inspection performed in accordance with Technical Specification 6.4.Q, Steam Generator Program. Attached is the Surry Unit 1 report for the Fall 2022 refueling outage.
If you have any questions concerning this information, please contact Mr. Michael M.
True, Jr. at (757) 365-2446.
Very truly yours, David H.
ilson Site Vice President
Attachment:
Surry Unit 1 Steam Generator Tube Inspection Report for the Fall 2022 Refueling Outage Commitments made in this letter: None MARCH 24, 2023
cc:
U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 Mr. John Klos NRC Project Manager - Surry U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. G. Edward Miller NRC Senior Project Manager - North Anna U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, Maryland 20852-2738 NRC Senior Resident Inspector Surry Power Station Mr. Rusty R. Richardson Authorized Nuclear Inspector Surry Power Station Serial No.23-020 Docket No. 50-280 Page 2 of 2
ATTACHMENT 1 SURRY UNIT 1 STEAM GENERATOR TUBE INSPECTION REPORT FOR THE FALL 2022 REFUELING OUTAGE VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)
Serial No.23-020 Docket No. 50-280
SURRY UNIT 1 STEAM GENERATOR TUBE INSPECTION REPORT FOR THE FALL 2022 REFUELING OUTAGE Serial No.23-020 Docket No. 50-280 page 1 of 28 The following satisfies the Surry Power Station Technical Specification (TS) reporting requirement section 6.6.A.3.
During the Surry Unit 1 Fall 2022 End-Of-Cycle 31 (EOC31) refueling outage, Steam Generator (SG) inspections were completed in accordance with TS 6.4.Q for all three SGs, designated as SG-A, SG-B, and SG-C. Unit 1 exceeded 200°F on December 13, 2022; therefore, this report is required to be submitted by June 11, 2023.
All three Unit 1 SGs were last inspected during the Spring 2021 refueling outage (EOC30) and had operated for 383.1 EFPM prior to that outage. Unit 1 operated for 16.8 EFPM during cycle
- 31.
Consequently, at the time of this inspection the Unit 1 SGs had operated for 399.9 EFPM since the first in-service inspection.
The three Surry Unit 1 steam generators are replacement Model 51 F lower assemblies (i.e.,
tube bundle, lower shell, and channel head) and primary moisture separator assemblies (F-type ). They were replaced in 1981. The moisture separators were subsequently upgraded to support a core power up-rate implemented in 1995. The feedrings were replaced in 2010.
Each of the three SGs were fabricated with 3,342 Thermally Treated Alloy 600 tubing, with nominal 0.875" OD x 0.050" wall thickness.
The seven broached quatrefoil support plates are fabricated from 405 Stainless Steel.
Figure 10 contains a schematic depicting the general arrangement of the steam generators without dimensions.
Figures 11 and 12 contain a photo of the Disk Stack and an illustration of its position in the Feedwater Regulating Valve respectively.
The Disk Stack provides an effective barrier against foreign objects in the feedwater entering the steam generators.
However, it is believed that the legacy foreign material on the top of the tubesheet had been introduced into the steam generators from the previously mentioned maintenance activities performed in the steam drums.
The Unit 1 steam generators have experienced no reportable primary to secondary leakage since the 1990s and operate with a nominal hot leg temperature of 604°F.
Each of the Surry Unit 1 SGs was screened to identify any low row indications of improper heat treatment. None were identified. All of the SGs were also screened for long row indications of improper heat treatment (-2 sigma tubes) and associated high residual stress. This evaluation identified 19, 22, and 3 tubes in SGs A, B, and C, respectively, which may have been improperly heat treated.
One of the 19 tubes in SG-A with potentially higher stress has since been plugged. Table 1 provides a listing of the 43 in-service tubes that have been identified through screening as possibly containing high residual stress due to an improper heat treatment.
These tubes were examined full length with array probes and closely scrutinized during the analysis process.
There were no deviations taken from Mandatory and/or Needed (Shall) requirements important to tube integrity from the EPRI Guidelines referenced by NEI 97-06 during the examination or the cycles preceding the EOC31 examination.
Table 1: Tubes with Potentially High Residual Stress SG Row Column No. Tubes A
9 33 A
11 8
A 13 86 A
14 44 A
16 6
A 16 11 A
16 41 A
16 90 A
17 42 A
17 72 18 A
20 42 A
20 51 A
22 9
A 22 11 A
22 13 A
23 43 A
26 81 A
28 77 B
9 79 B
11 4
B 11 10 B
11 11 B
11 85 B
18 31 B
18 50 B
18 75 B
19 50 B
21 6
B 21 7
22 B
23 8
B 23 25 B
23 41 B
23 88 B
24 42 B
25 9
B 25 39 B
25 53 B
26 15 B
26 45 B
27 38 C
22 21 C
23 12 3
C 29 16 Serial No.23-020 Docket No. 50-280 page 2 of 28 In the discussion below Bold Italicized wording represents TS verbiage and the required information is provided directly below each reporting requirement.
A list of acronyms is contained in Table 12 at the end of this report.
Serial No.23-020 Docket No. 50-280 page 3 of 28 A report shall be submitted within 180 days after Tavg exceeds 200°F following completion of an inspection performed in accordance with the Specification 6.4.Q, "Steam Generator (SG) Program.
11 The report shall include:
- a. The scope of inspections performed on each SG Primary Side The tubing in each SG was inspected with bobbin coil probes over their full length except for the Row 1 and 2 U-bends, which were examined with a +Point' rotating probe.
An array probe examination was conducted on 100% of the tubes at the hot leg and cold leg tubesheets. The extent of the array probe tubesheet examinations was from the first support structure located above the tubesheet down to the H-star dimension.
Note that the permanent alternate repair criteria (PARC), Technical Specification (TS 6.4.Q),
eliminates the need to analyze the Surry SG tubing for degradation in the region below the H-star dimension which is 17.89 inches below the top of the tubesheet. It also eliminates the need to plug tubes if the only repairable degradation is located below the H-star dimension.
All high residual stress (HRS) tubes in Table 1 were examined full length with both Bobbin and Array probes due to the potentially increased susceptibility of Stress Corrosion Cracking.
In addition to the base scope, a preplanned special interest scope was developed for the EOC31 inspection, which includes a sample of previously identified dents, dings, manufacturing burnish marks, volumetric indications, and wear (excluding AVB wear).
As a result of concerns for possible degradation at dent/ding locations, the special interest scope of dents/dings with a +Point' probe included 100% of all dents/dings.:: 2 Volts located in the hot leg straight section and 100% of all dents/dings.:: 5 Volts in the U-bend and cold-leg sections of the tubes.
It should be noted that both terms Dent and Ding refer to a plastic deformation of the tube that results in a reduction in the tube diameter. The two different terms were used to differentiate between the location of the signals.
Historically (early generation designs) the term dent referred to local tube diameter reductions due to corrosion products from carbon steel (typically, drilled carbon steel tube support plates).
The term ding referred to local tube diameter reductions due to mechanical means (manufacturing, vibration, incidents during maintenance activities, or impact from foreign objects).
Since the eddy current signals from both dents and dings are similar, the location of the indication was used to differentiate which term was used (dent for indications at supports and ding for all free span indications).
At Surry Power Station, the referenced dent signals do not represent the same phenomena as classical denting on older generation units caused by drilled carbon steel support plate corrosion damage. Since the Surry units are not similar in design (i.e., quatrefoil stainless steel tube support plate design vs. drilled hole carbon steel tube support plate design) these same "denting" issues do not directly apply to the Surry units. Tube support plate areas are not susceptible to denting caused by corrosion of the tube support plates.
However, the historical nomenclature assigned to these signals has existed in the database since the steam generators were installed and has remained unchanged since that time.
Serial No.23-020 Docket No. 50-280 page 4 of 28 No scope expansions were required; however, the base scope was augmented with additional rotating probe (including magnetically bias probes) to resolve ambiguous indications consistent with the special interest criteria.
The primary side work scope also included video/ visual examinations (as-found/ as-left) of all channel heads specifically including:
All plugs Tube-to-tubesheet welds Stub runner and divider plate Stub runner to divider plate welds Stub runner to tubesheet clad weld Divider plate-to-channel head clad weld Tubesheet cladding Closure ring welds Entire bowl cladding with the bowl effectively dry All primary side visual examinations were completed satisfactorily with no degradation or anomalies reported.
Secondary Side During the EOC31 examination, the following secondary side activities were performed in all three SGs:
Top of tubesheet water lancing Post-lancing visual examination of the tube bundle from the entire periphery Visual examination of historical foreign object-related locations Visual investigation of any accessible locations having eddy current signals potentially related to foreign objects, and removal of retrievable foreign objects.
- b. Degradation mechanisms found During the EOC31 examination, degradation modes observed were legacy anti-vibration bar (AVB) wear and various legacy volumetric indications (two maintenance related, several foreign object related, some TSP wear, and a few of undetermined origin). New degradation included a single small TSP wear indication and several small AVB wear indications. None of legacy or new degradation exceeded the 40% TW technical specification plugging criteria. No corrosion related degradation (such as stress corrosion cracking) was detected. No detected degradation exceeded condition monitoring limits.
Serial No.23-020 Docket No. 50-280 page 5 of 28
- c. Nondestructive examination techniques utilized for each degradation mechanism The inspection program focused on the degradation mechanisms listed in Table 2 and utilized the referenced eddy current techniques.
Table 2 - Inspection Method for Applicable Degradation Mechanism Classification Degradation Location Probe Type Mechanism Existing Wear Anti-Vibration Bars Bobbin - Detection and Sizing Existing OD Pitting Top-of-Tubesheet (TTS)
Bobbin and Array - Detection
+Point' - Sizing Existing Wear Tube Support Plate Bobbin - Detection
+Point' - Sizing Existing Tube Wear (Foreign Freespan and TTS Bobbin and Array - Detection Objects)
+Point' - Sizing Existing PWSCC Tube Ends N/A*
Existing Wear Flow Distribution Baffle (FOB)
Bobbin - Detection
+Point' - Sizing Potential PWSCC Tubesheet Overexpansions (OXP)
Array - Detection
+Point' - Sizing Bulges, Dents, Manufacturing Array - Detection Potential ODSCC, PWSCC Anomalies, and Above Tubesheet Overexpansions (OVR)
+Point' - Sizing Potential ODSCC Tubesheet Crevice in Tubes With N/A**
NTE Potential Tube Slippage Within Tubesheet Bobbin - Detection Existing ODSCC, PWSCC Hot Leg TTS Array - Detection
+Point' - Sizing Potential ODSCC, PWSCC Row 1 and 2 U-bends
+Point' - Detection and Sizing Potential ODSCC Freespan and Tube Supports Bobbin - Detection
+Point' - Sizing Existing ODSCC, PWSCC High Residual Stress Tubes Bobbin and Array - Detection
+Point' - Sizing Inspection not required per technical specification alternate repair criteria All tubes with no tubesheet expansion (NTE) have previously been plugged
Serial No.23-020 Docket No. 50-280 page 6 of 28
- d. Location, orientation (if linear), and measured sizes (if available) of service induced indications As stated in the (b) response above, anti-vibration bar (AVB) wear, tube support plate (TSP) wear, flow distribution baffle (FOB) wear, and foreign object wear were detected during EOC31.
No indications of stress corrosion cracking (SCC) were detected during the EOC31 SG tube inspection.
AVB Wear In total, 114 AVB wear indications in 84 tubes were identified among all three SGs during EOC31. Of these, 12 indications in 8 tubes were sized ;;:: 20% TW. None of the identified flaws exceeded the Technical Specification plugging limit (40% TW) and none were plugged.
The maximum reported depth was 28% TW.
A listing of all 114 indications of AVB Wear is contained in Table 3.
Table 3: Surry 1 EOC31 Inspection Summary - AVB Wear Indications Wear Depth (% TW)
ETSS 96041.1 SG Row Col AVB No.
EOC30 EOC31 A
9 54 AV1 11 10 A
12 45 AV1 17 13 A
12 45 AV4 15 11 A
12 47 AV4 12 14 A
21 86 AV2 9
10 A
30 57 AV2 16 12 A
30 57 AV3 14 12 A
32 14 AV4 12 9
A 32 48 AV3 15 12 A
32 65 AV2 17 12 A
32 66 AV2 10 9
A 32 69 AV2 25 21 A
32 69 AV3 20 15 A
32 69 AV4 21 17 A
33 16 AV2 11 13 A
33 63 AV3 25 21 A
33 63 AV4 20 16 A
33 66 AV1 11 12 A
33 66 AV2 11 13
SG Row Col AVB No.
A 34 59 AV2 A
35 17 AV2 A
35 78 AV2 A
36 47 AV1 A
36 75 AV2 A
36 76 AV2 A
37 75 AV2 A
37 75 AV3 A
38 62 AV1 A
38 62 AV4 A
38 73 AV3 A
39 42 AV1 A
39 72 AV2 A
39 72 AV4 A
40 42 AV1 A
40 69 AV4 A
42 65 AV2 A
43 59 AV2 A
44 55 AV2 A
44 59 AV3 A
45 40 AV4 A
46 43 AV1 A
46 43 AV2 A
46 44 AV1 A
46 44 AV4 A
46 45 AV1 A
46 45 AV4 B
22 72 AV3 B
26 61 AV3 B
28 57 AV1 B
28 66 AV2 B
28 83 AV2 B
31 33 AV2 Wear Depth (% TW)
ETSS 96041.1 EOC30 EOC31 16 13 14 16 14 16 9
8 13 11 11 12 13 12 11 9
12 7
14 9
15 10 13 12 10 10 13 11 13 13 12 14 12 13 12 14 13 11 12 13 11 13 9
15 13 12 13 14 17 12 15 17 18 16 14 12 8
12 10 9
6 18 17 Serial No.23-020 Docket No. 50-280 page 7 of 28
SG Row Col AVB No.
B 32 26 AV3 B
34 58 AV2 B
34 58 AV3 B
34 58 AV4 B
34 79 AV3 B
35 17 AV1 B
35 17 AV2 B
35 17 AV3 B
36 33 AV3 B
36 65 AV4 B
38 22 AV2 B
38 22 AV3 B
39 24 AV3 B
39 36 AV3 B
39 66 AV1 B
40 25 AV2 B
40 26 AV2 B
41 27 AV2 B
41 27 AV3 B
41 47 AV2 B
42 29 AV1 B
42 29 AV2 B
43 32 AV2 B
43 34 AV3 B
43 39 AV2 B
45 37 AV2 B
45 37 AV3 B
45 38 AV2 B
46 45 AV2 C
22 7
AV3 C
24 33 AV2 C
27 10 AV3 C
27 85 AV2 Wear Depth (% TW)
ETSS 96041.1 EOC30 EOC31 12 9
27 27 23 22 13 12 11 8
11 9
14 11 26 26 10 9
15 12 13 8
14 9
12 8
13 9
11 7
18 19 12 8
14 12 13 11 11 6
11 8
16 15 15 10 15 9
13 9
14 8
13 7
9 6
18 14 11 10 10 7
14 11 11 Serial No.23-020 Docket No. 50-280 page 8 of 28
SG Row Col AVB No.
C 27 85 AV3 C
33 16 AV2 C
34 16 AV2 C
35 17 AV1 C
35 17 AV4 C
35 46 AV2 C
35 46 AV3 C
35 77 AV3 C
37 24 AV2 C
38 67 AV3 C
39 23 AV1 C
39 23 AV2 C
39 23 AV3 C
39 69 AV3 C
40 66 AV2 C
42 31 AV1 C
42 31 AV2 C
42 31 AV3 C
42 31 AV4 C
43 31 AV2 C
43 46 AV2 C
44 59 AV2 C
45 37 AV3 C
45 38 AV3 C
45 40 AV4 C
45 52 AV4 C
45 58 AV1 C
45 58 AV2 C
45 58 AV4 Wear Depth (% TW)
ETSS 96041.1 EOC30 EOC31 10 11 12 11 8
25 24 12 11 13 11 14 11 12 13 12 9
22 20 18 18 21 20 30 28 16 15 12 11 24 23 24 23 22 20 16 15 13 12 11 12 10 10 11 10 14 11 11 10 9
11 11 11 Serial No.23-020 Docket No. 50-280 page 9 of 28
Non-AVB Wear Serial No.23-020 Docket No. 50-280 page 10 of 28 Bobbin probe or array probe inspections of in-service tubes identified 36 indications of volumetric tube degradation not related to AVB wear, in 35 tubes among all three SGs.
The measured flaw depths range from 5% TW to 33% TW.
Sizing of these indications was performed with a +Point' rotating coil.
Table 4 lists the 36 Non-AVB Wear indications. The sizing techniques used to determine the dimensions of the flaws are also identified in the table.
Thirty-five (35) of the 36 indications were reported during previous inspection outages, meaning that one indication was newly reported during EOC31 (15% TW TSP wear in SG-C R34-C55 at 02H-0.67"). None of the 35 repeat indications have exhibited signal change indicative of wear growth.
Two (2) of the 36 indications (SG-A R 1-C86 and SG-B R 1-C7) were caused by a sludge lancing process applied approximately 20 years ago (no longer used). Seven (7) of the indications result from support wear (TSP or baffle plate). One (1) indication result from legacy pitting. Three (3) of the indications are of uncertain origin, and twenty-three (23) indications result from foreign object wear, with no foreign object remaining in the vicinity of the wear indication.
Figure 1 through Figure 4 provide the 95/50 CM limit curves for flaws sized with ETSS 21998.1, 27901.1, 27902.1, and 96910.1 respectively. The CM curves represent the structural performance criteria derived by conservatively accounting for material property uncertainties, model uncertainties, and NOE depth sizing uncertainties.
The uncertainties were combined using Monte Carlo techniques.
Because each flaw plotted in Figure 1 through Figure 4 lies below the CM limit curve, each flaw satisfies the structural integrity performance criterion.
Table 4: Summary of Non-A VB Wear Volumetric Degradation Max Axial Circ Depth Length Length Initially SG Row Col Location ETSS Volts
(%TW)
(in)
(in)
Reported Cause A
1 86 BPC -5.55" 21998.1 0.32 25 0.85 0.37 2015 Lancing Equipment Damage A
2 57 06C -0.37" 96910.1 0.51 13 0.27 0.32 2006 TSP Wear A
3 66 05C -0.67" 27901.1 0.21 24 0.27 0.32 2009 Foreign Object A
6 88 TSH +0.16" 27901.1 0.20 23 0.35 0.42 2006 Foreign Object A
8 38 TSH +0.40" 21998.1 0.21 16 0.27 0.37 2001 Legacy Pitting A
34 67 TSH +0.03" 27901.1 0.19 22 0.27 0.26 2006 Foreign Object TSC +0.05" 27901.1 0.12 16 0.27 0.42 A
38 27 2018 Foreign Object TSC +0.67" 27901.1 0.15 19 0.37 0.37 A
38 30 TSC +1.84" 27901.1 0.12 16 0.35 0.4 2006 Foreign Object B
1 7
TSH+0.24" 21998.1 0.21 18 0.37 0.32 2007 Historical SG Maintenance B
12 51 TSC+0.27" 21988.1 0.11 10 0.32 0.37 2019 Unknown. Small volumetric B
31 15 BPH +0.53" 27901.1 0.11 15 0.21 0.37 2010 Foreign Object B
31 16 BPH +0.53" 27901.1 0.16 20 0.24 0.48 2010 Foreign Object B
32 15 BPH +0.51" 27901.1 0.1 14 0.21 0.48 2010 Foreign Object Foreign Object Remaining?
N/A N/A No No N/A No No No N/A N/A No No No In Situ Tested?
No No No No No No No No No No No No No Serial No.23-020 Docket No. 50-280 page 11 of 28 Plugged &
Stabilized?
No No No No No No No No No No No No No
Max Depth SG Row Col Location ETSS Volts
(%TW)
B 32 18 BPH +0.61 "
27901.1 0.09 12 B
33 17 BPH+0.56" 27901.1 0.05 8
B 33 18 BPH +0.61 "
27901.1 0.13 17 B
35 20 BPH +1.07
27902.1 0.27 15 B
37 31 04H-24.40" 21998.1 0.13 12 B
40 50 TSH +0.48" 27901.1 0.31 31 B
40 51 TSH +0.85" 27901.1 0.34 33 B
41 51 TSH +0.13" 27901.1 0.11 15 B
45 48 TSC+2.48" 21998.1 0.43 32 C
3 52 TSC +0.40" 27901.1 0.3 30 C
4 68 06C -0.32" 96910.1 0.33 17 C
15 49 04H -0.61 "
96910.1 0.31 15 C
26 85 BPH + 0.59" 27901.1 0.26 28 C
27 82 BPH +0.56" 27901.1 0.25 27 Axial Circ Length Length Initially (in) fin)
Reported Cause 0.24 0.26 2010 Foreign Object 0.21 0.34 2019 Foreign Object 0.29 0.32 2010 Foreign Object 0.48 0.48 2010 Foreign Object 0.21 0.37 2013 Unknown. Small volumetric 0.48 0.42 2007 Foreign Object 0.32 0.45 2007 Foreign Object 0.24 0.32 2007 Foreign Object 0.32 0.32 2013 Unknown. Small volumetric 0.27 0.37 2015 Foreign Object 0.29 0.37 2015 TSP Wear 0.24 0.32 2021 TSP Wear 0.19 0.63 2018 Foreign Object 0.29 0.4 2010 Foreign Object Foreign Object Remaining?
No No No No N/A No No No N/A No N/A N/A No No In Situ Tested?
No No No No No No No No No No No No No No Serial No.23-020 Docket No. 50-280 page 12 of 28 Plugged &
Stabilized?
No No No No No No No No No No No No No No
Max Depth SG Row Col Location ETSS Volts
(%TW)
C 29 82 BPH + 0.56" 27901.1 0.23 25 C
34 55 02H -0.67 96910.1 0.32 15 C
36 24 BPH -0.27" 96910.1 0.12 7
C 36 64 TSC +0.03" 27901.1 0.3 30 C
36 66 TSC-0.11" 27901.1 0.22 25 C
38 66 TSC +0.08" 27901.1 0.29 30 C
44 50 BPH -0.29" 96910.1 0.09 5
C 45 52 BPH -0.21" 96910.1 0.09 5
Axial Circ Length Length Initially (in)
(in)
Reported Cause 0.27 0.56 2018 Foreign Object 0.27 0.26 2022 TSP Wear 0.32 0.26 2012 FOB Wear 0.27 0.37 2012 Foreign Object 0.27 0.37 2015 Foreign Object 0.32 0.37 2009 Foreign Object 0.24 0.26 2015 FOB Wear 0.24 0.29 2015 FOB Wear Foreign Object Remaininq?
No N/A N/A No No No N/A N/A In Situ Tested?
No No No No No No No No Serial No.23-020 Docket No. 50-280 page 13 of 28 Plugged &
Stabilized?
No No No No No No No No
Stress Corrosion Cracking No indications of stress corrosion cracking were identified during EOC31.
Foreign Objects Serial No.23-020 Docket No. 50-280 page 14 of 28 In previous outages, multiple small pieces of wire had been detected, which had migrated into low flow areas forming localized entangled wire masses. These wire masses had been present in some of the SGs for more than 10 years without causing any tube wall degradation. The wires were evaluated and determined to be made of 304 stainless steel approximately 0.5" long and 0.012" in diameter. This is a diameter common for wire bristles associated with cleaning tools such as small wire brush wheels.
Individually, these small wires don't present a threat to tube integrity because they lack the mass required to penetrate the tube wall and are therefore considered to be benign.
During the EOC29 (Fall 2019) outage an enhanced tubesheet cleaning process was performed in all three steam generators to remove debris and legacy foreign objects. The as-left condition also provided a known baseline to positively identify any new foreign object intrusion during future operational cycles.
The foreign objects identified in Table 5 below include foreign objects removed during the EOC31 FOSAR and water lancing activities and the foreign objects known to be remaining at the conclusion of the EOC31 outage.
During 1 R31, TTS sludge lancing was performed in each of the Surry Unit 1 SGs. In total, 84 pounds of sludge related material was removed from all three SGs (A= 40 lbs., B= 24 lbs., and C = 20 lbs.).
Table 5: Foreign Object Highlights SG-Item#
Description Location Configuration ECT Results Estimated Size R6-C69 Legacy metal disk lodged between tubes R7-C68 R6-C69 and R7-C69.
1.1" diameter A-1 Historical (1 R20) Metal R7-C69 The disk is sitting on PLP disk its edge and is fused No Wear 0.2" thick TSC +0.24" to +1.24" to the top of the C/L tubesheet.
Legacy entangled Historical (1 R21)
R30-C47 mass of wire and Not A-2 Entangled wire mass of sludge located at TSH NDD Determined sludge/scale at TSH R30-C48 located behind the center stay rod Irregular shaped object Historical (1 R29) Irregular R36-C73 discovered at TSH PLP
~0.4" diameter A-21 object at TSH R37-C73 during 1 R29 post No Wear lance SSI R35-C71 R34-C71 R33-C71 R32-C71 Area of sludge (behind Region is Historical (1 R29) Area of R31-C71 inner most tie-rod) spread over 5 A-22 sludge (behind inner most R31-C72 discovered at TSH NDD rows and 2 tie-rod) at TSH during 1 R29 post columns of R32-C72 lance SSI tubes R33-C72 R34-C72 R35-C72 1R31 Hard sludge rock R25-C46 1 R31 Hard sludge rock LPS 0.50" X 0.25" X A-33 located on TSH R26-C46 fixed to TSH.
No Wear 0.10" 1 R31 Loose Wire on A-34 1 R31 Wire located on R30-C47 TSH. (Discovered at NDD
~2" long wire TSH FOTS A-2 I location)
Fixity Fixed Fixed Fixed Fixed sludge at TIS.No loose parts noted.
Fixed Retrieved 1R31 Serial No.23-020 Docket No. 50-280 page 15 of 28 2022 Disposition Initially identified 1 R20. Evaluated in 2009 (1 R22) with Framatome CR 2009-2529.
Object has remained fixed since that time.
Position and fixity again confirmed during 1 R31. Object has not caused tube degradation. Leave as is and monitor by ECT and SSI during next ISi.
During 1 R29, a small pile of legacy fine wires embedded in fixed sludge was aggressively raked and water lanced.
During 1 R31, configuration confirmed by SSI. Wires pose no threat to tube integrity (since 2007). Leave as is and monitor by ECT and SSI at next ISi.
Irregular object identified during 1 R29 Post Lance. Object is tightly lodged in place between two tubes. ECT history shows object present back to 2006. 1 R31 ECT observed no wear. Leave as is and monitor by ECT and SSI at next ISi.
During 1 R29, the sludge region was investigated by FOSAR and determined to be sludge deposits located on the TIS (H/L) and fixed in place. No loose parts were noted. During 1 R31, ECT was NDD (no wear). Leave as is and monitor by ECT at next ISi.
During 1 R31 sludge rock discovered and fixed to the TIS. ECT was NDD (no wear).
Leave as is and monitor by ECT at next ISi.
During 1 R31 ~2" wire discovered on TIS.
ECT was NDD (no wear). Item was removed and closed out at 1 R31. No actions required going forward.
SG-Item#
Description Location Configuration Parts captured in the (1R31) Lancing strainer lancing strainers A-32 parts TTS during 1R31 TTS lancing Historical (1 R29) lodged R40-C39 1 R29 Foreign object B-9 round object at TSH.
R40-C40 lodged between two Likely hard sludge.
tubes atTSH R35-C27 1R31 piece of weld B-20 1R31 Piece of Weld Slag slag discovered during located at TSH R35-C28 post lance inspection.
Parts captured in the (1R31) Lancing strainer lancing strainers B-21 parts TTS during 1R31 TTS lancing R4-C55, R4-C56 Historical (1 R29) Deposit 1 R29 Hard deposit C-38 adhered to TSH R5-C55, R5-C56 tightly adhered to TSH.
No tube contact.
1 R29 Hard deposit Historical (1 R29) Hard R9-C40 C-42 tube-to-tube bridging deposit bridging at TSH R10-C40 atTSH 1 R31 Irregular Object C-49 (Tube Scale) in C/L R27-C85 Tube Scale annulus 1 R31 Tube Scale located R4-C29 Tube Scale C-50 atTSC R4-C30 C-51 1 R31 Tube Scale located NTL Tube Scale on NTL ECT Results Estimated Size Fixity Various parts Retrieved at N/A ranging from 1R31
~1/8" to ~1" Two PLPs 0.4" diameter Fixed NOD 1.50" X 0.24" X Retrieved at 0.20" 1R31 Various parts Retrieved at N/A ranging from 1R31
~1/8" to ~1" NOD
~0.5" diameter Fixed Spans multiple NOD tubes in TTS Fixed sludge region INF 0.75" piece of Retrieved at scale 1R31 NOD 0.3" piece of Retrieved at scale 1R31 N/A 0.75" piece of Retrieved at scale 1R31 Serial No.23-020 Docket No. 50-280 page 16 of 28 2022 Disposition During 1 R31, many objects were captured in the SGA lancing strainers. Most are sludge related. There were also fragments of small diameter wire and small pieces of flex gasket material.
Historical 1 R29 object. During 1 R31 ECT detected two PLP. No wear detected. SSI confirmed that part remains fixed to the TTS. Continue to monitor with ECT and SSI at next ISi.
During 1 R31, weld slag identified during post lance ISi and removed from the SG.
ECT results NOD. Item closed out at 1 R31.
Going forward no further actions required.
During 1 R31, many objects were captured in the SGB lancing strainers. Most are sludge related. There were also fragments of small diameter wire and flex gasket material.
Deposit is fixed in place and not making contact with tubes. During 1 R31, ECT was NOD (no wear). Going forward, monitor with ECT and perform SSI to verify part configuration.
Object is hard deposit bridging and fixed in place. During 1R31, ECTwas NOD (no wear). Going forward, monitor with ECT and perform SSI to verify part configuration.
During 1 R31, affected and bounding tubes NOD (no wear). Part was retrieved at R31.
Item closed out at R31 and requires no action going forward.
During 1 R31, affected and bounding tubes NOD (no wear). Part was retrieved at R31.
Item closed out at R31 and requires no action going forward.
During 1 R31, part was retrieved at R31 from the NTL. No tubes affected. Item closed out at R31 and requires no action going forward.
SG-Item#
Description Location Configuration Irregular shaped object 1 R31 Irregular shaped R1-C47 wedged between C-52 center Tie Rod object located at TSC R1-C48 pedestal and first row of tubes 1R31 Small wire located R9-C39 Small wire embedded C-53 atTSH R10-C39 in sludge 1 R31 Small wires C-56 embedded in sludge R1-C48 Small wires embedded buildup at TSH R1-C49 in sludge buildup Parts captured in the (1 R31) Lancing strainer lancing strainers C-58 TTS parts during 1R31 TTS lancing ECT Results Estimated Size Fixity Retrieved at NOD 0.3" diameter 1R31 NOD Small wire Fixed NOD Mass of small Fixed wires Various parts Retrieved at N/A ranging from
~1/8" to ~1/2" 1R31 Serial No.23-020 Docket No. 50-280 page 17 of 28 2022 Disposition During 1 R31, affected and bounding tubes NOD (no wear). Part was retrieved at R31.
Item closed out at R31 and requires no action going forward.
During 1 R31, affected and bounding tubes NOD (no wear). SSI confirmed that part is fixed. Going forward, monitor with ECT and perform SSI to verify part configuration.
During 1 R31, affected and bounding tubes NOD (no wear). SSI confirmed that part is fixed. Going forward, monitor with ECT and perform SSI to verify part configuration.
During 1 R31, many objects were captured in the SGC lancing strainers. Most are sludge related. There were also fragments of small diameter wire and flex gasket material.
Serial No.23-020 Docket No. 50-280 page 18 of 28 Table 6: Summary of Prior OA Validation Spring 2021, EOC30 Operational Fall 2022 EOC31 Degradation Mechanism Assessment Projection Observed AVB Wear 33%TW 28%TW TSP/FDB Wear 22%TW 17%TW Specific depth not projected; no actual Maximum depth of 33% TW Volumetric Degradation growth expected; flaws expected to remain detected; no growth observed.
structurally insignificant CM criteria satisfied.
Circumferential ODSCC Lower 95/50 burst pressure = 7385 psi at No indications detected at top of tubesheet EOC33 Axial PWSCC Lower 95/50 burst pressure = 5155 psi at No indications detected at top of tubesheet EOC33 Circumferential PWSCC Lower 95/50 burst pressure = 7385 psi at No indications detected within Tubesheet EOC33 Operational Leakage Projected: <150 GPO No measurable leakage during cycle 31
- e. Number of tubes plugged during the inspection outage for each degradation mechanism One tube in SG-A was plugged for a large historical free span ding indication.
- f. The number and percentage of tubes plugged to date, and the effective plugging percentage in each steam generator.
Table 7 provides the plugging totals and percentages to date.
a e -
u e T bl 7 T b Pl u~gmg s ummarv Steam Generator SG-A SG-B SG-C Total Prior to EOC-31 44 26 42 112 EOC-31 I
0 0
I Total 45 26 42 113
% Plugged 1.3%
0.8%
1.3%
1.1%
Since no sleeving has been performed in the Surry Unit 1 steam generators, the effective plugging percentage is the same as the actual plugging percentage.
Serial No.23-020 Docket No. 50-280 page 19 of 28
- g. The results of condition monitoring, including the results of tube pulls and in-situ testing None of the tube degradation identified in Surry Unit 1 SGs during the EOC31 outage violated the structural integrity performance criteria; thereby providing reasonable assurance that none of these flaws would have leaked during a limiting design basis accident. Therefore, tube pulls and in-situ pressure testing were not necessary.
The Condition Monitoring (CM) Assessment for each detected degradation mechanism was determined using the methodology described below.
Table 8-CM Methodology CM (Mechanism)
Methodoloav Structural Limit Note AVB Wear Mixed Arithmetic/Monte Carlo Structural Limit (61 % TW) 1 Vol (Non AVB)
Monte Carlo CM Curve 2
Notes;
- 1) For CM, three uncertainties must be considered (NOE, burst relationship, and material properties). The Mixed Arithmetic/Monte Carlo methodology accounts for these uncertainties as follows. The Arithmetic part accounts for NOE uncertainty by using the ETSS depth sizing regression equation together with a 95/50 value (of the ETSS standard deviation) to arrive at the limiting upper bound % TW value. The Monte Carlo part accounts for uncertainty, from burst relationship and material properties, for determining the structural limit. If the upper bound % TW value is less than the structural limit, CM is met.
- 2) The CM curve, itself, has built into it the three uncertainties using Monte Carlo methods.
Therefore, no arithmetic correction for NOE sizing is required since it's accounted for by the CM curve.
AVB Wear Tabl 9 A d A. h e
m1xe r1t met1c
. /M onte ar o met o o oav was use C I h d I or 0
Degradation Mechanism Maximum 95%/50% Upper CM Limit Depth (wear)
Depth Bound Depth AVB Wear 28%
34.7%
61%
Since this upper bound estimate does not exceed the conservative structural limit of 61 % TW, it is concluded that none of the AVB wear flaws exceeded the structural limit. Note that the 61 % TW structural limit was developed under the guidance of Regulatory Guide 1.121 which considers both pressure and non-pressure loads.
Volumetric (Non-AVB Wear)
As indicated above, a Monte Carlo methodology was used for CM of the volumetric indications not attributed to AVB wear.
Figure 1 through Figure 4 provide the 95/50 CM limit curves for flaws sized with ETSS 21998.1, 27901.1, 27902.1, and 96910.1 respectively.
Serial No.23-020 Docket No. 50-280 page 20 of 28 Figure 1: CM Curve for Flaws Sized w/ETSS 21998.1 - Model: Axial Thinning w/Limited Circumferential Extent 100 90 80 70
[
60
~
0
.s::;
'a.
50 0
E 40 E
- E 30 w
0 z 20 10 7
0 0.0 0.2 ETSS 21998.1 R4 0.4 0.6 0,8 Length, (Inch)
-21998.1 R4 VOLs 1.0 1.2 1.4 Figure 2: CM Curve for Flaws Sized w/ETSS 27901.1 - Model: Axial Thinning w/Limited Circumferential Extent
[
C
.s::;
'a..,
0 E
E w
0 z 100 90 BO 70 60 50 40 30 20 10 0
0.0
\\
1.-
I
~ --
--f*"
0.2 0.4 ETSS 27901.1 R1 I
I
- 1
-27901.1 R1 Foreign Object Wear
-~
- -J
-- ~
-~
f----
0,6 0.8 1.0 1.2 1.4 Length, (Inch)
Serial No.23-020 Docket No. 50-280 page 21 of 28 Figure 3: CM Curve for Flaws Sized w/ETSS 27902.1 - Model: Axial Thinning w/Limited Circumferential Extent ETSS 27902.1 R1 100 90 27902.1 R1 Foreign Object Wear 80 70
~
~
60
.l! 0.
50 0
E 40 E
- E 30 w
0 z 20 10 0 +-----+-----+-----+-----+-----+------+----~---'
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Length, (Inch)
Figure 4: CM Curve for Flaws Sized w/ ETSS 96910.1 - Model: Axial Thinning w/Limited Circumferential Extent 100 90 80 70
~
60 C
\\
I I
96910.1 R11
\\
TSP / FOB Wear
--- \\
~
--f--
-t--
-r---___
ETSS 96910.1 R11
.l! 0.
50 -
0 E
40 E
- E 30 w
0 z 20
(
10 0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Length, (Inch)
OA (Mechanism)
AVB Wear TSP/FDB Wear FO Wear Circ PWSCC (TTS/TS)
Axial PWSCC (TTS/TS)
Circ ODSCC (TTS)
Axial ODSCC (DNT/DNG)
Serial No.23-020 Docket No. 50-280 page 22 of 28 Table 10- QA Methodology Methodoloav Structural Limit Note Mixed Arithmetic/Monte Carlo Structural Limit (61 % TW}
1 Mixed Arithmetic/Monte Carlo Structural Limit (57% TW}
1 Monte Carlo Structural Limit (58% TW}
2 Fullv Probabilistic Multi-Cvcle OA Lower 95/50 Burst Pressure > 3.l\\P 3
Fully Probabilistic Multi-Cycle OA Lower 95/50 Burst Pressure > 3.l\\P 3
Fullv Probabilistic Multi-Cvcle OA Lower 95/50 Burst Pressure > 3.l\\P 3
Fully Probabilistic Multi-Cycle OA Lower 95/50 Burst Pressure> 3.l\\P 3
Fully Probabilistic Multi-Cycle OA Lower 95/50 Burst Pressure > 3.l\\P 3
- 1) For OA (plug on NDE sizing), four uncertainties must be considered (NDE, growth, burst relationship, and material properties). The Mixed Arithmetic/Monte Carlo methodology accounts for the four uncertainties as follows. The Arithmetic part accounts for NDE uncertainty by using the ETSS depth sizing regression equation together with a 95/50 value (from the ETSS standard deviation) to arrive at the limiting BOC
% TW value. The limiting BOC % TW value is adjusted for growth allowance/uncertainty to arrive at the EOC % TW value, for comparison to the structural limit. Built into the structural limit, using Monte Carlo methods, are adjustments for burst relationship and material properties uncertainties. When the EOC
% TW value is less than the structural limit, OA is projected to be met.
- 2) The limiting BOC % TW is set equal to the upper 95th POD physical depth value. This value is adjusted for growth to arrive at the EOC % TW, for comparison to the structural limit. Built into the structural limit, using Monte Carlo methods, are adjustments for burst relationship and material properties uncertainties. When the EOC % TW value is less than the structural limit, OA is projected to be met.
- 3)
For the Fully Probabilistic Multi-Cycle OA, all uncertainties are accounted for within the probabilistic model. OA is projected to be met when the calculated lower 95/50 burst pressure exceeds three times the primary-to-secondary differential pressure (3.l\\P).
Table 11 - QA Projected Condition During EQC34*
Structural Integrity Accident Induced Leakage Performance Criteria Performance Criteria Degradation Mechanism EOC34 EOC34 Limit Projection Limit Projection AVB Wear 61%
40.8%TW 470 GPD Zero Leakage Maximum Depth Foreign Object Wear 58%
54.3%TW 470 GPD Zero Leakage Maximum Depth TSP/FDB Wear 57%
53%TW 470 GPD Zero Leakage Maximum Depth Pittinq Dormant. No projected pittin ~-
Circumferential ODSCC @
4470 psi 7147 psi 470 GPD Zero Leakage TTS Axial PWSCC TTS 4470 psi 5647 psi 470 GPD Zero Leakaqe Circumferential PWSCC within 4470 psi 7106 psi 470 GPD Zero Leakage tubesheet expansion Axial ODSCC (@ TSPs 4470 psi 6079 psi 470 GPD Zero Leakage Axial ODSCC @ (DNT/DNG) 4470 psi 5507 psi 470 GPD Zero Leakage
- Although the Operational Assessment is projected to EOC34, the current Technical Specification requires an inspection to be performed during EOC33.
Serial No.23-020 Docket No. 50-280 page 23 of 28 Figure 5: EOC34 Worst Case Burst Pressure - Circumferential ODSCC @TTS 0.25 ~--------------------------.~ ---~
0.20 t
i).15
.0 2
Q.
QI
~.10
- I E
- I u 0.05
EOC34 Min BP I
I I
I I
I '
f I
I I
f I
I
- I ' '
Lower 95/50: 7147 ps\\
/
I I
I f
I I I I I I 3XNOPD: 4470 psi
- /
1
J.--
Prob: 0.05 I
I I
I I
I 0.00 --------------,----------- -=-"----...... -----.----
1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Projected EOC34 Worst Case Burst Pressure (psi)
Figure 6: EOC34 Worst Case Burst Pressure - Axial PWSCC @TTS 0.25 ---------------------~ ---------~
0.20
~
- s Cl!
0.15
.c e 0..
Q)
.2: i
- i 0.10 E
- l V
0.05
---* EOC34 Min BP I
I I
I I I
I,
I I '
I I
I I
I I
I I
I I
I I
I I
I I I I
Lower 95/50: 564 7 psi 1 I
I I
I,'
I /
I,'
3XNOPD: 4470 psi
,, I I
I I
Probability: 0.05 -----
0.00 +---- --.-----
.,e.=-=--- _,_---.-----&--..-----~----------l 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Projected EOC34 Worst Case Burst Pressure (psi)
~
- E Serial No.23-020 Docket No. 50-280 page 24 of 28 Figure 7: EOC34 Worst Case Burst Pressure - Circ PWSCC within Tubesheet 0.25 ~--------------------------, --------,
EOC34 Min BP 0.20 I
I I
I I
I I
I I
I I
I
~ 0.15 I
I I
e Q.
Q)
.c:
]i e 0.10
- i CJ 0.05 3XNOPD: 4470 psi I
I I
I I
I Lower 95/50: 7106 psi 1 :
1 1 I I,:,,
1---*
I 11 I
/ I
/ I Probability: 0.05 I
,l I 0.00 +-----~---~--~* -~----~-----~--.......... *~---~-----<
2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Projected EOC34 Worst Case Burst Pressure (psi)
Figure 8: EOC34 Worst Case Burst Pressure - Axial ODSCC @TSPs 0.25 ~---------------------------.----------,
0.20
~
- E
<11 0.15
.D e Q.
Q)
.c:
1\\i
- i 0.10 E
- i u 0.05 I I I,
EOC34 Min BP
/
I,,
I I I I
I,,,
I I
I I
I '
I Lower 95/50: 6079 psi 1 I
/
I
/
I I l 1/
3XNOPD: 4470 psi
,t!-------* Probability: 0.05 11 I I
,,, I I
I
-~~-
I I
I 0.00 -+-----.--- --,__,,...... -...,-::..:,..
- i..;-;;_ __ __ _ --,-------.-1-----...,...------r-------1 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Projected EOCJ4 Worst Case Burst Pressure (psi)
~
- s (11
..c e
- n.
(I>..: -
.l!l
- I E
0.20 0.15 0.10 0.05 I
I I
I
EOC34 Min BP
/ '
I I
I I '
I I I I '
I I
I I
I,
I '
Lower 95/50: 5507 psi 1
/
I
/
I I,'
I /
I,'
3XNOPD: 4470 psi
1-------------
Probability: 0.05
' I I
,,' I I
I I
I I
~
I 0.00 +------.----........ - =--~----L-~---~---~-----l 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Projected EOC34 Worst Case Burst Pressure (psi)
- h. The primary to secondary LEAKAGE rate observed in each SG (if it is not practical to assign the LEAKAGE to an individual SG, the entire primary to secondary LEAKAGE should be conservatively assumed to be from one SG) during the cycle preceding the inspection which is the subject of the report, Routine primary-to-secondary leak monitoring is conducted in accordance with station procedures. During the cycle preceding EOC31, no measurable primary-to-secondary leakage was observed in any Unit 1 SG.
- i. The calculated accident induced LEAKAGE rate from the portion of the tubes below 17.89 inches from the top of the tubesheet for the most limiting accident in the most limiting SG. In addition, if the calculated accident induced LEAKAGE rate from the most limiting accident is less than 1.80 times the maximum operational primary to secondary LEAKAGE rate, the report should describe how it was determined, The permanent alternate repair criteria (PARC) requires that the component of operational leakage from the prior cycle from below the H-star distance be multiplied by a factor of 1.8 and added to the total accident leakage from any other source and compared to the allowable accident induced leakage limit. Since there is reasonable assurance that no tube degradation identified during this outage would have resulted in leakage during an accident, the contribution to accident leakage from other sources is zero.
Assuming that the prior cycle operational leakage is <1 GPO originated from below the H-star distance and multiplying this leakage by a factor of 1.8 as required by the PARC, yields an accident induced leakage value of <1.8 GPO.
Serial No.23-020 Docket No. 50-280 page 26 of 28 This value is well below the 470 GPO limit for the limiting SG and provides reasonable assurance that the accident induced leakage performance criteria would not have been exceeded during a limiting design basis accident.
- j. The results of the monitoring for tube axial displacement (slippage). If slippage is discovered, the implications of the discovery and corrective action shall be provided.
No indications of tube slippage were identified during the evaluation of bobbin probe examination data from any SG during EOC31.
Table 12 - Acronyms AILPC Accident Induced Leakage Performance Criteria NDD No Degradation Detected ARC Alternate Repair Criteria NOPD Normal Operating Pressure Differential AVB Anti-Vibration Bar NTE No Tube Expansion BLG Bulge OA Operational Assessment BOC Beginning Of Cycle OD Outside Diameter BPC Baffle Plate Cold ODSCC Outer Diameter Stress Corrosion Cracking BPH Baffle Plate Hot OVR Over Roll CM Condition Monitoring Assessment OXP Over Expansion DNG Ding PARC Permanent Alternate Repair Criteria DNT Dent PDA Percent Degraded Area ECT Eddy Current Test PLP Possible Loose Part EFPM Effective Full Power Months POD Probability Of Detection EOC End Of Cycle PWSCC Primary Water Stress Corrosion Cracking ETSS Examination Technique Specification Sheet sec Stress Corrosion Cracking EWM Entangled wire mass so Steam Generator FAC Flow Assisted Corrosion SIPC Structural Integrity Performance Criteria FDB Flow Distribution Baffle SSI Secondary Side Inspection FO Foreign Object TS Technical Specification FOSAR Foreign Object Search And Retrieval TSC Tube Sheet Cold GPD Gallons Per Day TSH Tube Sheet Hot HRS High Residual Stress TSP Tube Support Plate ISi In-Service Inspection TTS Top ofTubesheet LPM Loose Part Monitoring TW Through Wall LPS Loose Part Signal VOL Volumetric MBM Manufacturing Burnish Mark WAR Wear
Figure 10 - General Arrangement Serial No.23-020 Docket No. 50-280 page 27 of 28
Figure 12 - Disk Stack Location in Feed Regulating Valve O-Ring
-- Disk Stack
~--.. O-Ring O-Ring Seat Ring
~
Serial No.23-020 Docket No. 50-280 page 28 of 28