ML19275D254

End of Cycle 19 Steam Generator Tube Inspection Report

ML19275D254
Person / Time
Site:	Millstone
Issue date:	09/19/2019
From:	Daugherty J Dominion Energy Nuclear Connecticut, Dominion Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
19-375
Download: ML19275D254 (16)

Text

Dominion Energy Nuclear Connecticut, Inc Rt 156, Rope Farry Road, Waterford, CT 06385 D0m1n1onEnargy com U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 SEP 1 9 1019 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION UNIT 3 "ii o'ominion j a,, Energy~

Serial No.

NSSUMLC Docket No.

License No.19-375 RO 50-423 NPF-49 END OF CYCLE 19 STEAM GENERATOR TUBE INSPECTION REPORT In accordance with the* Millstone Power Station Unit 3 Technical Specification (TS)

Section 6.9. ~.7, Dominion Energy Nuclear Connecticut, Inc. hereby submits the End of Cy9le 19 (EOC19) Steam Generator (SG) Tube Inspection report.

The report is submitted within 180

• days after initial entry into MODE 4 following completion of the spring 2019 SG inspections 'performed in accordance with TS 6.8.4.g, "Steam Generator (SG) Program." Initial entry into Mode 4 occurred on May 11, 2019. contains the EOC19 SG Tube Inspection report. Attachment 2 contains a list of acronyms.

The report addresses the following reporting requirements:

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,

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, -

i.

The calculated accident induced leakage rate from the portion of the tubes below 15.2 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 2.49 times the maximum operational primary to secondary leakage rate, the report should describe how it was determined; and

j. The results of monitoring for tube axial displacement (slippage).

If slippage is discovered, the implications of the discovery and corrective action shall be provided.

Serial No.19-375 Docket No. 50-423 Page 2 of 2 If you have any questions or require additional information, please contact Mr. Jeffry A.

Langan at (860) 444-5544.

Sincerely, ugherty Site Vice President - Millstone Attachments:

1) Millstone Power Station Unit 3, End of Cycle 19 Steam Generator Tube Inspection Report

2) Acronyms 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 - Millstone Power Station 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 Millstone Power Station Unit 3 Serial No.19-375 Docket No.

50-423 End of Cycle 19 Steam Generator Tube Inspection Report MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC. (DNC)

Serial No.19-375 Docket No 50-423, Page 1 of 11 End of Cycle 19 Steam Generator Tube Inspection Report Transmittal of this report satisfies Millstone Power Station Unit 3 (MPS3) Technical Specification (TS) 6.9.1.7 which specifies that a report shall be submitted within 180 days after the initial entry into MODE 4 following completion of an inspection performed in accordance with TS 6.8.4.g, Steam Generator (SG) Program. During MPS3's spring 2019 refueling outage (3R19), steam generator inspections were completed in accordance with TS 6.8.4.g. Initial entry into Mode 4 occurred on May 11, 2019; therefore, this report is required to be submitted to the NRC by November 7, 2019.

This attachment provides a summary of the MPS3 SG inspection results and specific responses to each of the TS 6.9.1.7 reporting requirements. Attachment 2 contains a list of acronyms.

Introduction MPS3 is a four loop Westinghouse pressurized water reactor with Westinghouse Model F SGs. Each SG was fabricated with 5626 U-bend thermally treated lnconel 600 tubes. The tubing is nominally 0.688 inches outside diameter with a 0.040 inch nominal wall thickness.

During SG fabrication, the tubes were hydraulically expanded over the full depth of the 21.23-inch thick tubesheet. The tubesheet was drilled on a square pitch with 0.98 inch spacing. There are 59 rows and 122 columns in each SG. The radius of row 1 U-bends is 2.20 inches.

U-bends in rows 1 through 10 were stress relieved after being formed.

Secondary side tube support structures include a flow distribution baffle, seven plate supports with broached holes on the vertical section of the tubes, and six anti-vibration bars (AVBs) on the U-bend section of the tubes.

The SGs have accrued 26.16 Effective Full Power Years (EFPY) of operation as of the End of Cycle (EOC) 19 (April 2019). MPS3 has the capacity to generate a maximum calculated gross output of approximately 1,296 MWe.

TS 6.9.1.7 Reporting Requirements This section provides responses to each of the reporting requirements specified in MPS3 TS 6.9.1. 7.

Bold wording represents TS verbiage.

The required information is provided immediately following the restatement of each reporting requirement.

A report shall be submitted within 180 days after the initial entry into MODE 4 following completion of an inspection performed in accordance with TS 6.8.4.g, Steam Generator (SG) Program. The report shall include:

a. The scope of inspections performed on each SG, One hundred percent of the operational tubes in SG B and SG D, a total of 11,136 tubes or approximately 50 percent of the total population of tubes, were inspected full length using eddy current examination techniques. The majority of the tubing length was examined with bobbin probes. The U-bends of rows 1 and 2 (481 in-service tubes) were examined with a Motorized Rotating Probe Coil (MRPC) technique in addition to the bobbin probe examination of the straight legs of the tubes. An additional augmented sample of 37 4 tube

Serial No.19-375 Docket No.

50-423, Page 2 of 11 locations was examined with a MRPC probe. The augmented sample inspections were performed in areas of special interest including hot leg expansion transitions, tube overexpansion locations, dents, as well as locations where the bobbin probe response was ambiguous. An additional augmented sample of 12,663 tube locations was inspected with an array coil probe.

The array coil probe sample included 100% of the hot leg top-of-tubesheet (TTS) locations (11,083 tubes), and approximately 13% of the cold leg TIS locations (1,527 tubes). The extent of the TIS examinations was from the first support structure detected above the secondary face of the tubesheet to 15.2 inches below the secondary face of the tubesheet; except for the tubes categorized as high residual stress tubes. For the high residual stress tubes, the extent included the entire full length of the tubes.

Table 1 3Rl9 ECT Examination Summary SGA SG B SG C SG D Total Number of Installed Tubes 5626 5626 5626 5626 22504 Number of Tubes In-service at start of 3Rl9 5575 5601 5604 5535 22315 Number of Tubes Inspected w/Bobbin Probe N/A 5601 N/A 5535 11136 Number of Tube Locations Inspected w/Array Probe N/A 6370 N/A 6293 12663 Number of Exams Performed w/MRPC N/A 418 N/A 437 855 Previously Plui,;~ed Tubes 51 25 22 91 189 Tubes Plugged During 3R19 0

0 0

0 0

During 3R19, secondary side activities were performed in SGs A, B, C, and D and included the following:

• High pressure sludge lancing.

• Post-sludge lancing visual examination of the TIS annulus and no-tube lane to assess as-left material condition and cleanliness, and to identify and remove any retrievable foreign objects.

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

• Secondary side upper internal examinations within SG C as follows:

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

o Drop down examinations (through the primary separators) of the upper tube bundle and AVB supports.

o Visual inspections of feed ring internal interface for flow accelerated corrosion.

o Visual inspections of upper tube support plate (TSP) to assess material condition and cleanliness.

Serial No.19-375 Docket No.

50-423, Page 3 of 11 The results of all secondary-side visual examinations performed were satisfactory, with no degradation detected.

b. Degradation mechanisms found, The existing degradation mechanisms found during 3R19 included AVB wear, TSP wear, volumetric indications from fabrication and volumetric degradation from foreign object wear.

c. Nondestruetive examination techniques utilized for each degradation mechanism, Table 2 identtfies the examination techniques used for each identified degradation mechanism.

Table 2 Degradation Mechanisms and Inspection Techniques Class!ficatlon Degradation Location Probe Type Mechanism Existing Tube Wear Anti-Vibration Bars Bobbin - Detection and Sizing Existing Tube Wear Tube Support Plate Bobbin - Detection

+Point' - Sizing Tube Wear Bobbin, Array and +Point'M -

Existing (foreign objects)

Freespan and TIS Detection

+Point' - Sizing Existing IGA/SCC Tube Ends N/A*

Existing FAC Feed Ring and J Tube to Feed Visual Inspection Ring Interface Existing Tube Wear Flow Distribution Baffle Bobbin - Detection

+Point' - Sizing Potential ODSCC Hot Leg Top-of-Tubesheet Array - Detection PWSCC And Sludge Region

+Point'- Detection and Sizing Bulges, Dents, Manufacturing Potential ODSCC Anomalies, and Above-Array - Detection PWSCC Tubesheet Overexpansions

+Point'- Detection and Sizing (OVR)

Potential PWSCC Tubesheet Array - Detection Overexpansions (OXP)

+Point'- Detection and Sizing Potential ODSCC Row 1 and 2 U-bends

+Point' - Detection and Sizing PWSCC Potential FAC Moisture Separators Visual Inspection Potential Plug Installation Plugs Visual Inspection Problems Potential Tube Slippage Within Tubesheet Bobbin Detection

• Inspection for this mechanism was not necessary under the existing alternate repair criteria.

Serial No.19-375 Docket No.

50-423, Page 4 of 11

d. Location, orientation (if linear), and measured sizes (If available) of service induced indications, Tables 3 through 8 identify the AVB wear and non-AVB wear volumetric indications reported during 3R19.

Table 3 3R19 Volumetric Degradation Summary SG B (Excludes AVB Wear)

Fi;,}~lgn L~:Catfqfj

!Via!<" pepth

¢a~s~

e!tigge"j:I ~

s~.

Ro\\,v Col**

Ob"ect

%.iw

- L st¥11ii;*e~?

_ "it_em~inlng __

B 1

37 03C + 0.36" 6

TSP Wear N/A No B

15 99 03H - 0.80" 8

TSP Wear N/A No B

29 65 08(-0.78" 7

TSP Wear N/A No B

29 109 04H - 0.55" 5

TSP Wear N/A No B

30 52 05H - 0.74" 9

TSP Wear N/A No B

32 30 06H -1.18" 9

TSP Wear N/A No B

1 119 TSC + 4.17" 23 Foreign Object No No Wear TSC + 3.76" 19 foreign Object Wear No No B

1 120 TSC + 4.74" 17 Foreign Object No No Wear B

1 121 TSC + 6.52" 9

Foreign Object No No Wear B

22 118 TSC + 0.86" 20 Lancing Sled N/A No B

44 98 02H + 15.85" 19 Fabrication N/A No

Serial No.19-375 Docket No.

50-423, Page 5 of 11 Table 4 3R19 Volumetric Degradation Summary SG D (Excludes AVB Wear) 0Fbrelgn.

M~D~pth

• Pl@ged.&

'Sq R~-.v Co.I.

Lo~tlo_n*

%TW C~u~e Objeq:*, *

~~abll)zeci?

.Remaining D

17 24 07C-0.69" 35 TSP Wear N/A No D

24 89 06C- 0.68 10 TSP Wear N/A No D

27 39 08C - 0.81" 17 TSP Wear N/A No D

35 73 04H - 0.46" 25 TSP Wear N/A No D

46 24 01H - 0.17" 11 FDB Wear N/A No D

46 99 01H + 0.53" 25 Foreign No No Object Wear D

52 42 01H + 0.50" 24 Foreign No No Object Wear D

52 91 01H + 2.54" 31 Foreign No No Object Wear D

58 50 01C + 0.47" 16 Foreign No No ObJect Wear D

58 51 01C + 0.48" 24 Foreign No No Object Wear

Serial No.19-375 Docket No.

50-423, Page 6 of 11 Table 5 3Rl9 AVB Wear Listings, SG B - Repeat Indications SG Row Col Location

%TW SG Row Col Location

%TW SGB 30 12 AV2 10 SGB 40 23 AV2 12 SGB 30 12 AV5 13 SGB 40 23 AV3 12 SGB 32 108 AV4 13 SGB 40 23 AV4 14 SGB 33 12 AV2 16 SGB 40 23 AV5 15 SGB 33 12 AV5 17 SGB 40 24 AV3 17 SGB 33 39 AV3 10 SGB 40 24 AV4 18 SGB 33 109 AV2 15 SGB 40 24 AV5 11 SGB 33 109 AV3 18 SGB 41 34 AV2 11 SGB 33 109 AV6 7

SGB 41 34 AV3 13 SGB 34 18 AV3 9

SGB 41 34 AV4 32 SGB 34 18 AV4 6

SGB 41 34 AV5 30 SGB 34 71 AV3 9

SGB 41 34 AV6 11 SGB 34 109 AV2 9

SGB 41 50 AV3 17 SGB 34 109 AV3 19 SGB 41 50 AV4 24 SGB 34 109 AV5 12 SGB 41 69 AV3 8

SGB 34 109 AV6 8

SGB 41 69 AV4 16 SGB 34 110 AV3 10 SGB 41 69 AV5 28 SGB 35 103 AV6 11 SGB 41 77 AV3 15 SGB 35 106 AV3 7

SGB 41 77 AV4 10 SGB 35 106 AV4 15 SGB 41 77 AV5 18 SGB 35 106 AV6 9

SGB 42 19 AV1 11 SGB 36 22 AV6 9

SGB 42 21 AV2 18 SGB 36 39 AV2 8

SGB 42 21 AV3 11 SGB 36 39 AV3 9

SGB 42 21 AV4 17 SGB 36 39 AV4 9

SGB 42 21 AV5 26 SGB 36 39 AV5 17 SGB 42 21 AV6 13 SGB 36 39 AV6 11 SGB 42 33 AV2 11 SGB 36 67 AV6 9

SGB 42 96 AV2 17 SGB 37 100 AV4 12 SGB 42 96 AV3 13 SGB 37 103 AV2 10 SGB 42 96 AV4 9

SGB 37 104 AV3 12 SGB 42 96 AV5 10 SGB 37 104 AV4 9

SGB 42 98 AV1 8

SGB 38 104 AV3 12 SGB 42 98 AV2 31 SGB 38 104 AV4 23 SGB 42 98 AV3 34 SGB 38 104 AV5 9

SGB 42 98 AV4 15 SGB 39 30 AV2 10 SGB 42 98 AV5 10 SGB 39 30 AV4 11 SGB 43 86 AV4 7

SGB 39 30 AV5 9

SGB 43 100 AV3 24 SGB 39 96 AV3 13 SGB 43 100 AV4 28

Serial No.19-375 Docket No.

50-423, Page 7 of 11 SG Row Col Location

%TW SG Row Col Location

%TW SGB 43 100 AV6 10 SGB 54 35 AV4 8

SGB 45 22 AV6 9

SGB 54 35 AV5 13 SGB 46 99 AV4 6

SGB 54 35 AV6 10 SGB 48 25 AV6 7

SGB 54 36 AV5 34 SGB 49 27 AV1 11 SGB 54 36 AV6 13 SGB 49 27 AV2 9

SGB 54 37 AV1 11 SGB 49 27 AV5 11 SGB 54 45 AV2 9

SGB 50 29 AV2 17 SGB 55 84 AV6 13 SGB 50 29 AV6 14 SGB 56 41 AV3 10 SGB 50 72 AV3 12 SGB 56 42 AV6 11 SGB 50 88 AV2 17 SGB 56 71 AV2 11 SGB 50 88 AV3 21 SGB 56 81 AV1 9

SGB 50 88 AV4 21 SGB 57 70 AV2 8

SGB 50 88 AV5 11 SGB 58 74 AV4 10 SGB 50 88 AV6 10 SGB 58 75 AV5 18 SGB 51 91 AV4 14 SGB 59 65 AV2 12 SGB 51 91 AV5 13 SGB 51 91 AV6 6

SGB 54 35 AV2 13 Table 6 3R19 AVB Wear Listings, SG B - New Indications SG Row

<;of Location

%TW SGB 39 30 AV3 10 SGB 42 33 AV5 10

Serial No.19-375 Docket No.

50-423, Page 8 of 11 Table 7 3R19 AVB Wear Listings, SG D - Repeat Indications SG Row Col Location

%TW SG Row Col Location

%1W SGD 9

121 AV6 12 SGD 36 88 AV2 11 SGD 24 117 AV1 21 SGD 36 88 AV3 10 SGD 25 93 AV5 11 SGD 36 88 AV5 11 SGD 25 115 AV1 8

SGD 36 97 AV2 14 SGD 26 8

AV6 14 SGD 37 93 AV2 13 SGD 26 115 AV1 14 SGD 37 93 AV3 18 SGD 26 116 AV1 10 SGD 37 101 AV2 20 SGD 27 115 AV1 16 SGD 37 101 AV3 15 SGD 27 115 AV6 13 SGD 37 101 AV4 15 SGD 28 8

AV1 13 SGD 37 103 AV2 12 SGD 28 8

AV6 15 SGD 37 103 AV3 12 SGD 28 114 AV2 30 SGD 37 103 AV5 16 SGD 28 114 AV5 11 SGD 37 106 AV1 13 SGD 29 113 AV2 15 SGD 37 106 AV3 19 SGD 29 113 AV5 15 SGD 37 106 AV4 31 SGD 30 113 AV2 13 SGD 37 106 AV5 24 SGD 30 114 AV1 10 SGD 37 106 AV6 15 SGD 30 114 AV6 22 SGD 38 21 AV5 15 SGD 31 99 AV2 10 SGD 38 21 AV6 10 SGD 31 99 AV5 11 SGD 38 95 AV5 9

SGD 31 99 AV6 10 SGD 38 98 AV2 12 SGD 32 112 AV5 11 SGD 38 98 AV4 15 SGD 33 86 AV3 11 SGD 40 32 AV2 13 SGD 33 86 AV4 14 SGD 40 99 AV2 13 SGD 33 109 AV2 11 SGD 40 99 AV3 11 SGD 33 109 AV5 16 SGD 40 99 AV4 27 SGD 34 109 AV2 11 SGD 40 99 AV5 31 SGD 35 99 AV2 11 SGD 40 100 AV4 13 SGD 35 99 AV5 15 SGD 40 100 AV5 16 SGD 35 102 AV5 10 SGD 40 100 AV6 12 SGD 35 103 AV5 15 SGD 40 101 AV3 11 SGD 35 107 AV4 10 SGD 40 101 AV4 10 SGD 35 108 AV3 16 SGD 40 101 AV5 12 SGD 35 108 AV4 12 SGD 40 101 AV6 9

SGD 35 109 AV4 13 SGD 40 102 AV2 9

SGD 35 109 AV5 9

SGD 40 102 AV3 14 SGD 36 34 AV2 6

SGD 40 102 AV4 23 SGD 36 82 AV3 10 SGD 40 102 AV5 17

Serial No 19-375 Docket No.

50-423, Page 9 of 11 SG Row Col

.Location

%TW SG Row Col Location

%TW SGD 40 102 AV6 10 SGD 44 21 AV1 12 SGD 40 103 AV1 13 SGD 45 22 AV6 8

SGD 40 103 AV2 22 SGD 45 41 AV3 17 SGD 40 103 AV3 24 SGD 45 41 AV4 9

SGD 40 103 AV4 32 SGD 45 47 AV6 13 SGD 40 103 AV5 28 SGD 45 92 AV2 12 SGD 40 103 AV6 15 SGD 45 96 AV2 13 SGD 41 26 AV2 14 SGD 45 96 AV3 14 SGD 41 26 AV5 31 SGD 45 96 AV5 12 SGD 41 26 AV6 32 SGD 47 24 AV1 11 SGD 41 29 AV4 14 SGD 47 96 AV5 15 SGD 41 29 AV6 10 SGD 47 98 AV5 6

SGD 41 30 AV2 10 SGD 48 25 AV6 10 SGD 41 30 AV3 13 SGD 48 94 AV6 16 SGD 41 30 AV4 19 SGD 48 96 AV5 17 SGD 41 30 AV5 14 SGD 49 62 AV1 21 SGD 41 31 AV2 13 SGD 49 62 AV2 22 SGD 41 39 AV2 16 SGD 49 62 AV3 30 SGD 41 39 AV3 21 SGD 49 62 AV4 17 SGD 41 39 AV4 21 SGD 49 66 AV1 14 SGD 41 39 AV5 27 SGD 49 66 AV2 32 SGD 41 39 AV6 11 SGD 49 66 AV3 17 SGD 41 78 AV2 9

SGD 49 67 AV2 27 SGD 41 78 AV3 22 SGD 49 67 AV3 24 SGD 41 78 AV4 13 SGD 49 67 AV4 10 SGD 41 78 AV5 12 SGD 49 69 AV2 9

SGD 41 87 AV3 9

SGD 49 70 AV2 13 SGD 41 90 AV1 11 SGD 49 86 AV3 12 SGD 41 90 AV3 12 SGD 49 95 AV2 20 SGD 42.

19 AV5 15 SGD 49 95 AV3 20 SGD 42 103 AV2 17 SGD 49 95 AV4 20 SGD 43 20 AV6 10 SGD 50 28 AV6 13 SGD 43 25 AV5 11 SGD 50 80 AV2 11 SGD 43 33 AV3 8

SGD 50 80 AV3 9

SGD 43 95 AV4 11 SGD 50 83 AV1 14 SGD 43 95 AV5 16 SGD 50 83 AV2 16 SGD 43 100 AV4 18 SGD 50 83 AV3 9

SGD 43 100 AV5 6

SGD 50 90 AV1 11 SGD 43 100 AV6 8

SGD 51 87 AV5 12 SGD 43 102 AV5 13 SGD 51 89 AV6 14 SGD 43 102 AV6 11 SGD 52 33 AV5 9

Serial No.19-375 Docket No.

50-423, Page 10 of 11 SG Row Col Location

%TW SG Row Col Location

%TW SGD 52 67 AV3 12 SGD 53 35 AVG 16 SGD 52 67 AV4 22 SGD 53 36 AVG 11 SGD 52 67 AV5 16 SGD 53 70 AV2 11 SGD 52 69 AV2 13 SGD 54 49 AV2 18 SGD 52 87 AV5 11 SGD 54 49 AV3 22 SGD 52 87 AVG 8

SGD 54 49 AV4 11 SGD 52 88 AV1 12 SGD 54 87 AV1 8

SGD 52 88 AV2 17 SGD 55 40 AVG 18 SGD 52 88 AV3 11 SGD 55 75 AVG 19 SGD 52 88 AV4 14 SGD 55 84 AV5 25 SGD 53 33 AVG 10 SGD 55 84 AVG 7

SGD 53 34 AVG 10 SGD 56 43 AV1 12 SGD 53 35 AV4 13 SGD 58 59 AV1 12 SGD 53 35 AV5 15 Table 8 3R19 AVB Wear Listings, SG D-New Indications SG Row Col Location

%TW SGD 36 108 AV2 10 SGD 37 103 AVG 12 SGD 38 94 AV2 10

e. Number of tubes plugged during the inspection outage for each degradation mechanism, Based on inspection results, no tubes were plugged during the 3R19 outage.

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

Table 9 provides the total number of tubes plugged to date and the effective plugging percentage in each SG.

Serial No 19-375 Docket No.

50-423, Page 11 of 11 Table 9 Number Tubes Plugged To Date SGA SG B SG C SG D Prior to 3R19 51 25 22 91 During 3R19 0

0 0

0 Total After 3R19 51 25 22 91 Percentage 0 906 0 444 0.391 1.617 Overall Percentage 0.84 Since no sleeving has been performed in the MPS3 steam generators, the effective plugging percentage is the same as the actual plugging percentage.

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 3R19.

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, No primary to secondary SG leakage was reported during Cycle 19.

i.

The calculated accident induced leakage rate from the portion of the tubes below 15.2 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 2.49 times the maximum operational primary to secondary leakage rate, the report should describe how it was determined; For the purposes of the condition monitoring assessment, and in accordance with the permanent alternate repair criteria, the accident leakage attributed to degradation within the tubesheet below the H* dimension must be estimated by applying a factor of 2.49 to the operational leakage. There was no recordable operational leakage during Cycle 19; hence, the leakage from this degradation during a limiting accident would have been zero (i.e., 2.49 X 0).

j. The results of monitoring for tube axial displacement (slippage). If slippage is discovered, the implications of the discovery and corrective action shall be provided.

Tube slippage monitoring was performed on SG B and SG D using the bobbin coil data during 3R19.

There was no detection of slippage during the 3R19 examination.

Serial No.19-375 Docket No.

50-423 Acronyms MILLSTONE POWER STATION UNIT 3 DOMINION ENERGY NUCLEAR CONNECTICUT, INC. (DNC)

Serial No.19-375 Docket No 50-423, Page 1 of 1 Acronyms AVB Anti-Vibration Bar OVR Above Tubesheet Over Expansion BET Bottom of the Expansion Transition OXP Over Expansion BLG Bulge PIO Positive Identification C

Column PLG Tube is plugged CL Cold Leg PLP Possible Loose Part DOH Ding or Dent Signal - Reviewed in PTE Partial Tubesheet Expansion History PWR Pressurized Water Reactor DOI Distorted Dent or Ding Indication PWSCC Primary Water Stress 'corrosion DDS Ding or Dent Signal - Non-Cracking Confirming w/RPC R

Row ONG Ding RAD Retest Analyst Discretion ONT Dent Indication RBD Retest - Bad Data ECT Eddy Current Test RIC Retest - Incomplete EFPY Effective Full Power Years RRT Retest - Restricted Tube EPRI Electric Power Research Institute S/N Signal-to-Noise Ratio ETSS Examination Technique SAi Single Axial Indication Specification Sheet sec Stress Corrosion Cracking F/L Full Length SCI Single Circumferential Indication FAC Flow Accelerated Corrosion SG Steam Generator FOB Flow Distribution Baffle SLG Sludge FO Foreign Object SSI Secondary Side Inspection FOTS Foreign Object Tracking System SVI Single Volumetric Indication HL Hot Leg TEC Tube End Cold Leg IGA lntergranular Attack TEH Tube End Hot Leg INF Indication Not Found TFH Tangential Flaw-Like Signal - Reviewed INR Indication Not Reportable in History LPI Loose Part Indication TFS Tangential Flaw-Like Signal - Non-LPR Loose Part Removed Confirming w/RPC LPS Loose Part Signal TSC Top of Tubesheet Cold Leg MRPC Motorized Rotating Pancake Coil TSH Top of Tubesheet Hot Leg NOD No Detectable Degradation TSP Tube Support Plate NOE Nondestructive Examination TIS Top of Tubesheet NDF No Degradation Found TWO Through-Wall Depth NEI Nuclear Energy Institute

%TW Percent Through-Wall NQH Non-quantifiable Indication -

VOL Volumetric Indication Reviewed in History NQI Non-quantifiable Indication OA Operational Assessment ODSCC Outer Diameter Stress Corrosion Cracking