ML15173A000

Summary of Conference Call Regarding the Fall 2014 Steam Generator Tube Inspections

ML15173A000
Person / Time
Site:	Millstone
Issue date:	06/23/2015
From:	Richard Guzman Plant Licensing Branch 1
To:	Heacock D Dominion Nuclear Connecticut
Guzman R
References
TAC MF5037
Download: ML15173A000 (9)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 23, 2015 Mr. David A. Heacock President and Chief Nuclear Officer Dominion Nuclear Connecticut, Inc.

Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711

SUBJECT:

MILLSTONE POWER STATION, UNIT 3 -

SUMMARY

OF CONFERENCE CALL REGARDING THE FALL 2014 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MF5037)

Dear Mr. Heacock:

On October 27, 2014, the U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with representatives of Dominion Nuclear Connecticut, Inc. (the licensee) regarding the ongoing steam generator (SG) inspection activities at Millstone Power Station, Unit 3 (MPS3). The purpose of this call and NRC review of the ensuing SG 180-day report is to ensure acceptable tube inspections are being performed and that tube integrity is being maintained. In addition, these conference calls and reviews provide the NRC with information to verify that underlying assumptions made in the licensee's assessments of tube integrity (e.g.,

growth rates) are consistent with the licensee's original assumptions. is a summary of the October 27, 2014, conference call, and Enclosure 2 includes the materials that were provided by the licensee in support of the call.

If you have any questions, please contact me at 301-415-1030 or via e-mail at Richard.Guzman@nrc.gov.

Sincerely, Richard V. Guzman, Senior Project Manager Plant Licensing 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-423

Enclosures:

1. Fall 2014 SG Inspection Conference Call Summary

2. Licensee-provided Information cc w/encls: Distribution via Listserv

ENCLOSURE1 CONFERENCE CALL

SUMMARY

REGARDING FALL 2014 STEAM GENERATOR TUBE INSPECTION ACTIVITIES DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION, UNIT 3 DOCKET NO. 50-423

CONFERENCE CALL

SUMMARY

REGARDING FALL 2014 STEAM GENERATOR TUBE INSPECTION ACTIVITIES DOMINION NUCLEAR CONNECTICUT. INC.

MILLSTONE POWER STATION. UNIT 3 DOCKET NO. 50-423 TAC NO. MF5037 On October 27, 2014, the U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with representatives of Dominion Nuclear Connecticut, Inc. (the licensee) regarding the ongoing steam generator (SG) inspection activities at Millstone Power Station, Unit 3 (MPS3). In support of the conference call, the licensee provided the documents in . This information is summarized below.

MPS3 has four Westinghouse model F steam generators. Each steam generator has 5,626 thermally treated Alloy 600 tubes. The tubes have an outside diameter of 0.688 inches and a nominal wall thickness of 0.040 inches. The tubes are hydraulically expanded for the full depth of the tubesheet at each end. The tubes are supported by stainless steel support plates with quatrefoil-shaped holes and V-shaped chrome plated Alloy 600 anti-vibration bars (AVBs). The first 1O rows of tubes were stress-relieved to improve corrosion resistance. The tubes have a square pitch with a center-to-center spacing of 0.980 inches.

The following abbreviations are used in Enclosure 2:

• CL-Cold leg

• TEC - Tube End Hot

• HL- Hot Leg

• TSP - Tube Support Plate

• OXP - Overexpansion

• TW - Through-wall

• SIG - Steam Generator

• 3R16 - Unit 3 Refueling Outage 16

• TEH - Tube End Hot Additional clarifying information regarding the documents provided by the licensee in Enclosure 2 and information not included in the licensee-provided document is summarized below.

• There were no trends in the amount of primary-to-secondary leakage observed during the recently completed cycle.

• No secondary side pressure tests were performed during the outage.

• No exceptions were taken to the industry guidelines.

• During this outage, 100 percent of the tubes in SG "A" and SG "C" were inspected full length using a bobbin probe. A rotating coil probe was used to inspect the U-bends in rows 1 and 2.

• There was no corrosion degradation found during this inspection.

• There were no new foreign object wear indications found.

• There were no plans to plug any tubes in either SG at the time of the call.

• There were no in-situ pressure tests planned.

• One loose part was found in SG "C" and was described as a 3.4-inch long metal rod.

No wear indications were attributed to this loose part.

• Using a soft chemical cleaning process known as Deposit Minimization Treatment, approximately 12,000 pounds of material were removed from the steam generators.

• Secondary side inspections included foreign object search and retrieval for possible loose parts, steam drum visual inspections, upper tube support visual inspections for cleanliness, and deposit mapping.

• There were no unexpected or unusual results found during these inspections.

Additional information provided by the licensee subsequent to the conference call is summarized below:

• Among 317 AVB wear indications found in 165 tubes of SG "A", the maximum depth was 36 percent TW. Of these, 27 were newly reported with a maximum depth of 17 percent TW.

• Among 8 TSP wear indications found in 8 tubes of SG "A", the maximum depth was 16 percent TW. Of these, 2 were newly reported with a maximum depth of 16 percent TW. The maximum depth among the 6 previously reported indications was 15 percent TW.

• Among 76 AVB wear indications found in 39 tubes of SG "C", the maximum depth was 26 percent TW. Of these, 9 were newly reported with a maximum depth of 11 percent TW among them.

• Among 6 TSP wear indications found in 6 tubes of SG "C", the maximum depth was 21 percent TW. Of these, 3 were newly reported with a maximum depth of 21 percent TW among them. The maximum depth among the 3 previously reported indications was 13 percent TW.

The NRC staff did not identify any issues that required follow-up action at this time; however, the staff asked to be notified in the event that any unusual conditions were detected during the remainder of the outage.

ENCLOSURE 2 LICENSEE-PROVIDED STEAM GENERATOR TUBE INSPECTION INFORMATION DOMINION NUCLEAR CONNECTICUT, INC.

MILLSTONE POWER STATION. UNIT 3 DOCKET NO. 50-423

Millstone Nuclear Station October 2014 - 3R16 ECT Inspection nuclear enerqy Status Report ,Dominion 10/23/2014 3:40 S/G "A" S/G "C" Examination leg Probe E*lent Planned Acquired Resolved %Complete Planned Acquired Resolved %Complete Bobbin Exam Full Length Cold 560MR TEHHC 4491 330 0.00% 4524 4289 4270 94.39%

HL Straights (R 1-9) Hot SGOMR 08Hf£1l 108G 1086 236 21.73% 1080 1069 1069 98.98%

Cl Straights (R 1*2) Cold 560MR 08CTEC 243 0.00% 232 156 99 42.67%

CL Candy Canes (R 3-9) Cold 560UC 08HTEC 843 0.00% 848 564 11 1.30% __

---

---- ---*- -- ----~-

Array Exam Hl Tubesheet (Baffle Plate) Hot 560XP OlHTEH 4338 0.00% 4361 3917 1601 36.71%

HL Tubesheet (Non-Baffle) Hot 560XP 02HHH 1?39 0.00% 1243 1185 667 53.66%

Cl Tube,heet (Balfle Plate) Cold 560XP OlCTlC 606 0.00% 621 0.00%

Cl Tubesheet (Non-Baffle) Cold 560XP 02CTEC 116 0.00% 111 0.00%

Cl OXP (Baffle Plate) Cold SGOXP OlCTEC 8 000% 15 0.00%

CL OXP (Non Baffle Plate) Cold 560XP 02CTEC 12 0.00% 5 0.00%

Additional Array (xams Both 560XP Various 4 0.00%

• -~

........ ~.

MRPC Exam Low Row U-Bend Cold 5201P 08C08H 243 0.00% 232 0.00%

Hist. U-Bend Special Interest Hot 5201P Various 14 0.00% 12 0.00%

Hist. HL Special Interest Hot 560PP Various 204 0.00% 164 0.00%

Hist. Cl. Special lntNl'<>t Cold 560PP Various 31 000% 39 0.00%

3R16 Hl Special Interest Hot S&OPP Various 5] 0.00%

3R16 Cl Special lntPfPSt Cold 560PP Various 24 0.00%

3R16 U-Bend Speical Interest Both 5201P Various 6 0.00%

Total Inspections 13475 1416 23G 1.75% 13573 11180 7717 56.86%

II Calls #Tubes II Calls II Tubes

%TW Indications 1-19% 0 0 57 37 20- 36% 0 0 18 10

-~~----------

37 100% 0 0 0 0 Bobbin Indication Codes -

SI H Codes 7 5 805 572 f-------

"I" Codes (Possible Repairable) 0 0 . ., --- -----~---~*

52 47 MRPC Indication Codes -- -----~ -

"!"Codes (Possible Repairable) 0 0 0 0

---

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---~-

Estimated Number of Tubes to Plug 0 0

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ML 15173AOOO *memo dated (ML14330A528)

OFFICE LPL 1-1/PM LPL 1-1/LA NRR/DE/ESGB* LPL 1-1/BC(A) LPL 1-1/PM NAME RGuzman KGoldstein GKulesa (DPickett for) RGuzman MDudek DATE 06/22/2015 06/22/2015 12/17/2014 06/23/2015 06/23/2015