Text

End-of-Cycle 23 Steam Generator Tube Inspection Report
	ML15356A375
Person / Time
Site:	Millstone
Issue date:	12/14/2015
From:	Daugherty J; Dominion, Dominion Nuclear Connecticut
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	15-531
	Download: ML15356A375 (16)
	v • d • e

Rope Ferry Rd., Waterford, CT 06385 D mno Mailing Address: P.O. Box 128 DEC 1 4 2915 Waterford, CT 06385 dom.com U.S. Nuclear Regulatory Commission Serial No.15-531 Attention: Document Control Desk NSS&L/MLC R0 Washington, DC 20555 Docket No. 50-336 License No. DPR-65 DOMINION NUCLEAR CONNECTICUT. INC.

MILLSTONE POWER STATION UNIT 2 END OF CYCLE 23 STEAM GENERATOR TUBE INSPECTION REPORT In accordance with Millstone Power Station Unit 2 (MPS2) Technical Specification (TS) 6.9.1.9, Dominion Nuclear Connecticut, Inc. hereby submits the End of Cycle 23 Steam Generator Tube Inspection Report. The report is submitted within 180 days after initial entry into Mode 4 following completion of an inspection performed in accordance with TS 6.26, Steam Generator (SG) Program.

The report includes the following:

a. The scope of inspections performed on each SG,

b. Degradation mechanisms found,

c. Nondestructive examination techniques utilized for each degradation mechanism,

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

e. Number of tubes plugged during the inspection outage for each degradation mechanism,

f. The number and percentage of tubes plugged to date, and the effective plugging percentage in each steam generator

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

If you have any questions or require additional information, please contact Mr. Thomas G.

Cleary at 860-444-4377.

Sincerely, J$. Daugherty Site Vice President - Millstone Power Station

Serial No.15-531 Docket No. 50-336 Page 2 of 2

Enclosures:

(1)

Commitments made in this letter: None.

cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd. Suite 100 King of Prussia, PA 19406-2713 R. V. Guzman Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08-C2 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station

Serial No.15-531 Docket No. 50-336 ENCLOSURE END OF CYCLE 23 STEAM GENERATOR TUBE INSPECTION REPORT MILLSTONE POWER STATION UNIT 2 DOMINION NUCLEAR CONNECTICUT, INC.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 1 of 11 End of Cycle 23 Steam Generator Tube Inspection Report The acronyms used in this report are defined in Attachment 1.

In accordance with Millstone Power Station Unit 2 (MPS2) Technical Specification (TS) 6.9.1.9, Dominion Nuclear Connecticut, Inc. (DNC) is submitting this 180-day report which describes the results of the End of Cycle (EOC) 23 steam generator (SG) examinations which were performed during the MPS2 Refueling Outage 23 (2R23). Based upon entry into Mode 4 on November 1, 2015, this report is required to be submitted by April 29, 2016.

Backaqround:

MPS2 is a two loop Combustion Engineering pressurized water reactor (PWR) with Babcock and Wilcox replacement SGs. Each SG is designed to contain 8523 U-bend thermally-treated Inconel 690 tubes. The tubing is nominally 0.750 inch outside diameter with a 0.0445 inch nominal wall thickness. The nominal hot leg temperature is 601 °F.

Secondary side tube support structures include seven lattice grid supports on the vertical section of the tubes and twelve fan bar assemblies in the U-bend section of the tubes. All lattice grid supports are full supports. All tube supports were fabricated with 410-series stainless steel. The key design parameters for the MPS2 SGs are summarized in Table 1.

The MPS2 SGs were replaced during 2R11 (1992). The SGs have accrued approximately 16.43 Effective Full Power Years (EFPYs) of operation as of the EOC 23 (October 2015).

Since the first sequential period begins after the first inservice inspection, programmatically the MPS2 SGs have accrued 15.12 EFPYs.

See Attachment 2, "Millstone Power Station Unit 2 Steam Generator Arrangement," for an illustration of SG component locations.

Report:

TS 6.9.1.9 reporting requirements (in bold text) are provided below, followed by DNC's response:

A report shall be submitted within 180 days after initial entry into MODE 4 following completion of an inspection performed in accordance with TS 6.26, Steam Generator (SG) Program. The report shall include:

a. The scope of inspections performed on each SG, The MPS2 SG eddy current testing (ECT), conducted at the EOC 23 was completed on October 18, 2015. The examinations, personnel, and equipment conformed to the requirements of NEI 97-06, Rev. 3, Steam Generator Program Guidelines; EPRI Pressurized Water Reactor Steam Generator Examination Guidelines, Rev. 7; and Millstone Unit 2 Technical Specifications.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 2 of 11 The EOC 23 ECT inspections are summarized in Table 2. In SGI, 100% of the operational tubes (a total of 8,504 tubes) were inspected full length with bobbin probes.

An augmented sample of 2,678 SG 1 tube locations was inspected with motorized rotating pancake coil (MRPC) probes. No tube examinations were performed in SG 2.

The MRPC examinations included a 50% sample of the outer six rows of the hot and cold leg periphery and open tube lane at the top of tubesheet. The primary purpose of this examination was the detection of foreign objects or foreign object wear in the most susceptible regions of the SG. In addition, the MRPC examinations included both a pre-planned scope, and a special interest emergent scope. The pre-planned scope included historical locations of interest, dents or dings (DNT or DNG), overexpansions or bulges (OXP or BLG), percent through-wall indications (%TW), and a sample of non-quantifiable historical (NQH) indications. The emergent scope included bobbin coil special interest (SI) locations such as non-quantifiable indications (NQI), possible loose parts (PLP), and various hot leg and cold leg PLP bounding locations.

In addition to the ECT examinations, primary-side visual examinations were performed in both channel heads of SGI. These visual examinations (as-found/as-left), revealed no degradation of the divider plates, divider plate retaining bars/welds, primary closure rings/welds, or cladding. Visual examinations performed on all previously installed plugs identified no indications of plug degradation, leakage, or misplacement.

Secondary-side visual examinations were performed in SG 1 only. These examinations included:

Post-sludge lancing visual examination of the top-of-tubesheet annulus and no-tube lane (no lancing was performed in SG 2) to assess as-left material condition and cleanliness, and to identify and remove any retrievable foreign objects using FOSAR.

Visual investigation of accessible locations having eddy current indications potentially related to foreign objects, and removal of retrievable foreign objects.

Steam drum visual inspections to evaluate the material condition and cleanliness of key components such as moisture separators, drain systems, and interior surfaces.

b. Degradation mechanisms found, Fan bar wear was the only degradation mechanism found during the 2R23 SG examinations.

The results of the visual examinations performed were satisfactory, with no degradation detected.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 3 of 11

c. Nondestructive examination techniques utilized for each degradation mechanism, Table 3 identifies the examination techniques used for each detected degradation mechanism.

d. Location, orientation (if linear), and measured sizes (if applicable) of service induced indications, A complete listing of the tube degradation identified during 2R23 is provided in Table 4.

Two fan bar wear indications were detected and sized during 2R23 (see Table 3). The maximum depth of these indications was 14% TW and both indications had been reported during the previous examination performed in 2R20. Neither flaw exhibited significant growth during the operating period from 2R20 through 2R23.

e. Number of tubes plugged during the inspection outage for each degradation mechanism, No SG tubes were removed from service during 2R23.

f. The number and percentage of tubes plugged to date, and the effective plugging percentage in each steam generator, Table 5 provides the total number of tubes plugged and the percentages.

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

No tubes were pulled and no in-situ pressure tests were performed. The condition monitoring assessment concluded that the structural integrity, operational leakage, and accident induced leakage performance criteria were not exceeded during the operating interval preceding 2R23.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 4 of 11 Table 1: Key Design Parameters Tubing Material IAlloy 690 thermally treated relief of U-bends Row 1-8 with post bend stress Number of tubes 8,523 Tube Size 0.750" GD, 0.0445" wall Tube Pitch/Layout 1.00"/triangular pitch Shortest Tube Radius Row 3, 3.905" radius, Rows 1-3 are staggered Outer Row Tube Radius 72.5" Tubesheet Thickness 21.75" Support Plates Seven lattice grid support structures. Largest axial dimension is 3.15".

Anti-Vibration Bars Twelve fan bars support the tube rows. Rows 1-5 contact F01 and F12 only. Higher rows have progressively more fan bar support structures.

Largest fan bar width is 3.15".

Tubesheet Joint Full hydraulic expansion

Serial No.15-531 Docket No. 50-336 Enclosure, Page 5 of 11 Table 2: Millstone 2R23 ECT Summary

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _i _l iil Number of Installed Tubes

_ _iiii~iiiil!iii

_ _ _ il _ iliiii

_ _ lii~ii

_ _ !_ iiiiiiiiiiii!iiil!

_ _ _ _ _ _ iii!_ ii_i*i~!!i

_ ii!i!Ii

_ SG I S G 12 1iiiiiiiii!i

i¸¸¸~iSi*1iii *~l"ii~l *is T o tall

~iii!T a i 8,523* 8,523 17,046 Number of Tubes In Service Prior to 2R23 8,504 8,510 17,014 Number of Tubes Inspected F/L w/Bobbin Probe** 8,504 NA 8,504 Previously Plugged Tubes 19* 13 32 Number of Tubes Incomplete w/Bobbin Probe due to 0N Obstruction NA____0 Number of Exams with +Point TM (Total) 2,678 NA 2,678

Hot Leg Tubesheet Periphery (tubes) 1,249 1,249 eHot Leg Tubesheet Foreign Object Bounding (locations) 47 47

Hot Leg Tubesheet Previous Indications (locations) 1 NA 1

Hot Leg Previous Indications (locations) 8 8

Hot Leg 2R23 Special Interest (locations) 23 23

Cold Leg Tubesheet Periphery (tubes) 1,249 1,249 eCold Leg Tubesheet Foreign Object Bounding (locations) 33 33 eCold Leg Tubesheet Previous Indications (locations) 0 NA 0 eCold Leg Previous Indications (locations) 7 7 eCold Leg 2R23 Special Interest (locations) 9 9 eU-Bend Previous Indications (locations) 2 NA 2

U-Bend 2R23 Special Interest (locations) 8 ____ 8

Other Foreign Object Bounding Previous Indications200 (locations) NA cOther Foreign Object Bounding 2R23 Indications222 (locations)_____

Tubes with Max FB Wear >40 % 0 0 Tubes with Max FB Wear >20% but <40% 0 0 Tubes with Max FB Wear <20% 2 2 Tubes with Max SVI / VOL I WAR> 40 % 0 NA 0 Tubes with Max SVI / VOL / WAR>20% but <40% 0 0 Tubes with Max SVI / VOL / WAR<20% 0 0 Total Tubes Plugged as a Result of this Inspection 0 ____ 0

One tubesheet location in SG 1 (R57 0156) was not drilled in the cold leg tubesheet. The hot leg hole for this tube was plugged with a welded plug. Although this location was never tubed, it is included in the counts of installed tubes and plugged tubes.

- - A number of tubes were examined in hot leg / cold leg segments to achieve full length coverage.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 6 of 11 Table 3- Detection and Sizing Techniques Degradation Location Probe Technique 90% LCL Sizing Adjusted NDE Technique Analyst Total Random Mechanism Type Sheet POD Variable Parameter Uncertainty Based Uncertainty* Uncertainty @

(ETSS) @ %TWD (Systematic on Standard Error @95/50CL**

Uncertainty) of Regression @ 95/50CL

____ (Sy, x r N) 95150CL Bobbin Lattice Support 300/1 30 kHz 96004.1 0.91 @ >40% NA NA NA NA NA Differential Mix (Rev. 13)

(Detection)

FB 300/1 30 kHz 96041.1 POD Curve NA NA NA NA NA Differential Mix (App. I; Rev. 4)

(Detection) 300/130 kHz 96041.3 NA Depth y=0.99x + 2.73 5.53% 2.76% 6.17%

FB Absolute Mix (Rev. 3) (3.36 0.99 31)

(Sizing)

+PointTM Tube Wear Lattice Support, 250/100 kHz 96910.1 0.92 @>40% Depth y.l.0x + 4.30 11.0% 5.5% 12.31%

(Mech. Loose Part Differential Mix (Rev. 10) (6.68 0.96 37)

Induced) 300 kHz 27901.1 (Rev. 1) 0.93 @ >31% Depth y=l.05x- 1.97 3.78% 1.89% 4.27%

Loose Part*** (2.3 0.99 32) 300 kHz 27902.1 (Rev. 1) 0.95 @>8% Depth y=0.98x + 1.89 3.82% 1.91% 4.25%

(2.32 1.0 47) 300 kHz 27903.1 (Rev. 1) 0.94 @>21% Depth y=0.97x + 2.80 3.47% 1.74% 3.86%

(2.11 1.0 42) 300 kHz 27904.1 (Rev. 1) 0.93 @ >32% Depth y=l.00x + 0.48 3.27% 1.64% 3.66%

(1.99 0.99 32) 300 kHz 27905.1 (Rev. 1) 0.95 @ >7% Depth y=l.09x- 4.31 3.37% 1.69% 3.84%

(2.05 1.0 48) 300 kHz 27906.1 (Rev. 1) 0.95 @>11% Depth y=0.96x + 1.67 2.35% 1.18% 2.61%

(1.43 1.0 46) 300 kHz 27907.1 (Rev. 1) 0.95 @>13% Depth y=l.05x- 2.1 4.26% 2.13% 4.81%

(2.59 0.99 47)

Pancake Lattice Support 250/100 kHz 96911.1 (Rev. 9) 0.92 @ >40% Depth y=1.22x- 0.07 12.3% 6.16% 14.43%

______ ________ Absolute Mix (7.49 0.96 45)

A value of one half the technique uncertainty is assumed for the analyst uncertainty.

- In order to reflect analyst uncertainty in terms of physical depth, the analyst uncertainty value is multiplied by the technique regression slope prior to combining with technique uncertainty. The adjustment is not applicable to ETSSs whose uncertainty values are based directly on physical depth measurements (i.e., ETSSs for which system performance data is available).

- 21 additional ETSSs suitable for sizing loose part wear are documented in EPRIQ.com. These are identified as the ".2", ".4", and ".5" series of ETSSs 27901, 27902, 27903, 27904, 27905, 27906 and 27907.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 7 of 11 Table 3 - Detection and Sizing Techniques (continued)

Degradation Location Probe Technique 90% LCL Sizing Adjusted NDE Mechanism Technique Analyst Total Type Sheet POD Variable Parameter Uncertainty Uncertainty* Random (ETSS) @ %TWD (Systematic Based on @Uncertainty Uncertainty) Standard Error 95/50CL@

(Sy, x r N) of Regression @ 95150CL**

95/50CL Bobbin Loose Part 550/1 30 kHz 27091.2 na na na na na Differential Mix (Rev. 1) 0.8@>6 PonN1984 0.944 @ >20% Depth y=.6+.36.22%

Fan Bar 300/1 00 kHz Mix (Rev. 1) 3.11% 7.04%

Tube Wear (3.78 0.99 49)

(Mech.

Induced) Bobbin 10kzAs13091.1 08@>2% Dph y(1.57

= 0.94x + 1.242581.928%

130 k~z (Rev.As 0 0.88 @ >6% Depth 1.0 40)25%1.92.%

Freespan Tube- (e.0 to-Tube Wear

+PointTM 250 kHz 13901.1 0.88 @ >26% Depth y = 1.04x - 0.912.7123278 Differential Mix (Rev. 1) (1.5 1.0 40)

Bobbin Sludge Pile 550/1 30 kHz 96005.2 0.89 @ >40% Depth y=0.27x + 28.42 Differential Mix (Rev. 9) (13.36 0.41 62) 21 .98% 10.99% 22.18%

Pitting

+PointrM" Sludge Pile 300 kHz 21998.1 0.92 @ >20% Depth y=l.02x + 5.81 10.33% 5.17% 11.60%

(Note 1) (Rev. 4) (6.28 0.94 63)

Thinning Above TTS, +PointT 96001.1 0.84 @ >50% Depth y=0.97x - 6.61 21 .71% 10.86% 24.13%

Freespan 300 kHz (Rev. 11) (13.20 0.86 29)

Bobbin 96010.1 0.85 @ >5% Depth y=1.04x - 0.45 1.46%

MBM Freespan 0.73% 1.65%

130 kHz Abs (Rev. 7) (0.89 0.95 33)

Note 1: Also applicable for loose part wear.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 8 of 11 Table 3 - Detection and Sizing Techniques (continued)

Degradation Location Probe Technique 90% LCL Sizing Adjusted NDE Technique Analyst Total Mechanism Type Sheet POD Variable Parameter Uncertainty Uncertainty Random (ETSS) @ %TWD (Systematic Based on @Uncertainty Uncertainty) Standard Error 95150CL@

(Sy, x r N) of Regression @ 95/50CL**

___________95/50CL ODSCC Axial__ Bobbin Freespan, Lattice, 400/1 00 kHz 128413 POD n/a n/a n/a n/a n/a Sig Pile w/dents <2V Differential mix (Rev. 3) Curve Non-dented Lattice, 400/1 00 kHz 96008.1 0.81 @ >20% Depth y = 0.74x + 9.56 33.9% 17.0% 36.2%

Sludge Pile Differential mix (Rev. 14) (20.62 0.74 17)

Freespan Dings <5.0 100 kHz 24013.1 0.88 @ >60% n/a n/a n/a n/a n/a Volts Differential (Rev. 2)

+PointTM All Locations 200 kHz 21409.1 0.85 @ >35% Length y = 1.14x + 0.03 0.35 in. 0.18 in. 0.40 in.

(Rev. 7) (0.21 0.94 9)

All Locations 300 kHz 22401.1 0.90 @ >53% Length y = 0.74x + 0.27 0.44 in. 0.22 in. 0.47 in.

(Rev. 4) (0.27 0.62 22)

Sludge pile w/dents 300 kHz 128424 POD n/a n/a n/a n/a n/a

<2V (Rev. 3) Curve Sludge pile w/dents 300 kHz 128431 n/a BED y=0.994x+2.73 n/a n/a 17.6%

<2V (Rev. 2) BEL y=0.645x+0.0785 n/a n/a 0.17 in.

Freespan, Lattice 300 kHz 128425 POD n/a n/a n/a n/a n/a w/dents <2V (Rev. 3) Curve Freespan, Lattice 300 kHz 128432 n/a BED y=0.972x+3.70 n/a n/a 20.0%

w/dents _<2V (Rev. 2) BEL y=0.516x+0.208 n/a n/a 0.33 in.

Circc All Locations 200 kHz 21410.1 0.94 @ >42% Length y = 1.24x + 0.42 1.14 in. 0.57 in. 1.34 in.

(Rev. 6) PDA (0.69 0.69 38) 38.79 % 19.40% 43.54 %

y=1.02x + 21.84 (23.58 0.47 38)

All Locations 300 kHz 22842.3 0.89 @ >39% n/a n/a n/a. n/a n/a

_____________

_________________ (Rev. 5) ____________ _________________________ ______

Serial No.15-531 Docket No. 50-336 Enclosure, Page 9 of 11 Table 3 - Detection and Sizing Techniques (continued)

Degradation Location Probe Technique 90% LCL Sizing / Adjusted NDE Technique Analyst Total Mechanism Type Sheet POD Detection Parameter Uncertainty Uncertainty Random (ETSS) @ %TWD Variable (Systematic Based on @Uncertainty Uncertainty) Standard Error 95/50CL@

(Sy, x r N) of Regression @ 95/50CL**

__________

_______95/50CL Circ.

Dents, Exp. +PointT Transitions, TS 300 kHz 20510.1 0.94 @ >40% Depth y = 0.73x + 8.16 31 .70% 15.85% 33.74%

(Rev. 7) (19.27 0.53 37)

Length y = 1 01x + 0.16 0.43 in. 0.21 in. 0.48 in.

(0.26 0.89 37)

PDA y =0.82x +2.83 11.48% 5.74% 12.41%

(6.98 0.88 37)

Dents, 300 kHz 96701.1 0.85 @>42% Depth y =0.84x + 10.32 15.73% 7.86% 17.06%

Expansion (Rev. 12) (9.56 0.92 16)

Transitions Length y =0.91x + 0.22 0.25 in. 0.12 in. 0.27 in.

(0.15 0.97 16)

PDA y =l1.0x + 8.55 12.39% 6.19% 13.88%

(7.53 0.90 16)

Expansion 300 and 250 kHz 111524 POD NA NA NA NA NA Transitions, TS (Rev. 0) Curve Axial Bobbin Support w! Dents 96012.1 0.89 @ >34% NA NA NA NA NA

2v, Tubesheet (Rev. 12)

+PointTM Expansion Depth y = 0. 68x + 14.45 20.46% 10.23% 21 .61%

Transitions, TS 300 kHz 20511.1 0.93 @>40% (12.44 0.64 33)

(Rev. 8) Length y = 1.10x - 0.01 0.21 in. 0.11 in. 0.24 in.

(0.13 0.87 32)

Dexpntsio 300 kHz 96703.1 0.94 @>54% Depth y =0.90x + 7.56 25.14% 12.57% 27.56%

Trpansitons (Rev. 17) (15.28 0.81 46)

TastosLength y = 1.0x + 0.13 0.46 in. 0.23 in. 0.51 in.

(0.28 0.91 46)

Serial No.15-531 Docket No. 50-336 Enclosure, Page 10 of 11 Table 4: Location, Orientation (If Linear), and Measured Sizes (If Applicable) of Service Induced Indications

Axial Lngth Circ.

Length Maximum Depth 2R23 1 Depth Reported 2R20 Initially SGRwCol Location ETSS __in__ (in)__ (%'TN) (%TW) -Reported -Signal History Comment Cause- Plugged?

25 40 155 196041.13*

F06 -1.61"'N AN NA 1 1 121 r P1esn1ic4R ihltl change in depth Fan Bar Wear No 25 140 93 F08 -0.49" 96041.1 /

960410.43 0.46e0.43 14 14n12 R

2R14 chne P2esn1ice4 eth ltl in it ite Fan Bar Wear No

ETS96041.1 used for detection. ETSS 96041.3 used for sizing.

A bounding flaw length of 1.5" was assumed for the flaw in R40 C155 since this flaw was not confirmed with +'PointTM . The bounding length of 1.5" is based on an assessment of the intersection angle between the tube and the fan bar at this location.

This value is very conservative relative to measured lengths of other fan bar wear flaws at MPS2 and other plants of similar design. Because both flaws lie below the condition monitoring limit curve, it is concluded that the structural performance criteria set forth in the MPS2 TSs was not exceeded by any of the evaluated flaws.

Serial No.15-531 Docket No. 50-336 Enclosure, Page 11 of 11 Table 5: Current Tube Plugging Status SGI1 SG 2 Tubes Plugged Prior to 2R23 19 13 Tubes Plugged During 2R23 0 0 Total Plugged Following 2R23 19 13 Percentage Plugged 0.22 0.15 Overall Percentage Plugged 0.19 Since no sleeving has been performed in the MPS2 SGs, the effective plugging percentage is the same as the actual plugging percentage.

Serial No.15-531 Docket No. 50-336 Enclosure, Attachment 1, Page 1 of 1 Attachment 1 Acronyms B&W Babcock & Wilcox BLG Bulge CHN Channel C Column CM Condition Monitoring CMOA Condition Monitoring and Operational Assessment DEG Degrees DEP Deposit ECT Eddy Current Testing EFPA EfetiergFaulr Attackear LPRI Eloeti Pawrt Indicatio n sttt MBM ManufactrigBrshMk MRPC Motorized Rotating Pancake Coil MPS2 Millstone Power Station Unit 2 NDE Non-Destructive Examination NQH Non-Quantifiable Historical Indication NQI Non-Quantifiable Indication ODSCC Outer Diameter Stress Corrosion Cracking OXP Over Expansion PLP Possible Loose Part POD Probability of Detection PTE Partial Tubesheet Expansion PWSCC Primar Water Stress Corrosion Cracking

%TW Percent Through-Wall RRo SCC Stress Corrosion Cracking SVOLinl Volumetric Indication WAR Wear Indication

Serial No.15-531 Docket No. 50-336 Enclosure, Attachment 2, Page 1 of 1 Attachment 2 Millstone Power Station Unit 2 Steam Generator Arrangement o+cI

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