ML17137A174

Summary of Conference Call Regarding the Spring 2017 Steam Generator Tube Inspections

ML17137A174
Person / Time
Site:	Comanche Peak
Issue date:	05/22/2017
From:	Watford M Plant Licensing Branch IV
To:	Peters K TEX Operations Company
Watford M, 301-415-1233
References
CAC MF9392
Download: ML17137A174 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 22, 2017 Mr. Ken J. Peters Senior Vice President and Chief Nuclear Officer Attention: Regulatory Affairs TEX Operations Company LLC P.O. Box 1002 Glen Rose, TX 76043

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT, UNIT NO. 2 -

SUMMARY

OF CONFERENCE CALL REGARDING THE SPRING 2017 STEAM GENERATOR TUBE INSPECTIONS (CAC NO. MF9392)

Dear Mr. Peters:

On April 20, 2017, the U.S. Nuclear Regulatory Commission (NRC) participated in a conference call with representatives of TEX Operations Company, LLC (the licensee) regarding the ongoing steam generator (SG) inspection activities at Comanche Peak Nuclear Power Plant (CPNPP),

Unit 2. By e-mail dated March 14, 2017, the NRC staff provided discussion points to facilitate the conference. In response, the licensee provided draft information related to the spring 2017 inspections in an e-mail dated April 19, 2017. Enclosed with this letter is a summary of that call.

The NRC staff did not identify any issues that required followup action at this time.

If you have any questions, please call me at 301-415-1233 or via e-mail at Margaret.Watford@nrc.gov.

Sim~v~J Margaret M. Watford, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-446

Enclosure:

Conference Call Summary cc w/encl: Distribution via Listserv

ML17137A174 **concurrence via memo OFFICE N RR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DE/ESGB/BC(A)**

NAME MWatford PBlechman AJohnson DATE 05/10/17 05/18/17 05/04/17 OFFICE NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME RPascarelli MWatford DATE 05/22/17 05/22/17

SUMMARY

OF CONFERENCE CALL REGARDING THE SPRING 2017 STEAM GENERATOR INSPECTIONS TEX OPERATIONS COMPANY LLC COMANCHE PEAK NUCLEAR POWER PLANT. UNIT 2 DOCKET NO. 50-446 On April 20, 2017, the U.S. Nuclear Regulatory Commission (NRC) participated in a conference call with representatives of TEX Operations Company, LLC (the licensee) regarding the ongoing steam generator (SG) inspection activities at Comanche Peak Nuclear Power Plant (CPNPP),

Unit 2. By e-mail dated March 14, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17074A024), the NRC staff provided discussion points to facilitate the conference. In response, the licensee provided draft information related to the spring 2017 inspections in an e-mail dated April 19, 2017 (ADAMS Accession No. ML17135A025).

CPNPP, Unit 2 has four Westinghouse Model D5 SGs. Each SG contains 4,570 thermally treated Alloy 600 U-bend tubes, with a nominal outside diameter of 0. 750 inches and a nominal wall thickness of 0.043 inches. The tubes are hydraulically expanded for the full depth of the tubesheet and are supported by stainless steel tube support plates with quatrefoil-shaped holes and V-shaped chrome-plated Alloy 600 anti-vibration bars.

The following abbreviations are used in the document provided by the licensee in the e-mail dated April 19, 2017:

• %TW - Percent Through-Wall

• 2R16 - Unit 2, Refueling Outage 16

• AVB -Anti-Vibration Bar

• CL - Cold Leg

• CPNPP - Comanche Peak Nuclear Power Plant

• EPRI - Electric Power Research Institute

• HL- Hot Leg

• PBP - Preheater Baffle Plate

• PWSCC - Primary Water Stress Corrosion Cracking

• SG - Steam Generator

• TS - Tubesheet

• TSP - Tube Support Plate

• TTS - Top of Tubesheet Information exchanged during the call and not included in the document provided by the licensee in the e-mail dated April 19, 2017, is summarized below:

• The licensee stated that the purpose of the "100% +Point inspection of dents >

2.0 volts at H3 TSP in all four SGs" was to be proactive in finding potential cracking associated with dent indications since operating experience in similar, older model SGs show that these are typically first detected around the third TSP Enclosure

on the hot leg side. The licensee also stated that these inspections were part of a commitment for the CPNPP, Unit 1 original SGs that was also applied to the CPNPP, Unit 2 SGs.

• Circumferential PWSCC indications were detected in three tubes near the top of the tubesheet. This is the first occurrence of PWSCC in the CPNPP, Unit 2 SGs.

The licensee indicated that one of the three tubes, located at row 5, column 79 in SG 3, had a similar eddy current signal during the 2014 inspections. The NRC staff asked the licensee to provide insights into the reasons the indication was not called in the 2014 outage. The licensee stated that the likely reason the indication was not called was due to differences in "sensitivity" to making PWSCC calls between the 2014 and 2017 inspections. The licensee stated that PWSCC in the tubesheet was part of the site-specific performance demonstration for the 2014 outage. The NRC staff stated that the expectation is that analysts would be sensitive to indications from any potential degradation mechanism in the tubes, not just those that have been historically present.

• The licensee stated that there were five new AVB wear indications identified this outage and no tubes exhibited wear indications with depths greater than 40% TW.

• The licensee stated that there were 64 foreign objects remaining in the SGs at the end of 2014 outage and 14 foreign objects were removed during the 2017 outage. Thus, approximately 50 foreign objects remain, including 4 legacy objects that have been present for the past several inspections.

• The licensee stated that there was a possible loose part (PLP) indication on top of the sixth TSP on the CL side in the tube located at row 13, column 92 in SG 4.

According to the licensee, indications have been present since at least 2011 and an indication has been detected at the top of the TSP that appears to be a wear scar. The licensee stated the loose part is no longer in the area around the tube and the area will be bounded by eddy current inspections.

• The licensee stated that the appearance of the channel head indication in the cold leg of SG 1, which was identified in the 2014 outage, shows no apparent growth, based on review of visual inspection video recordings from the last several outages. Based on images seen in the camera used for visual inspections, the licensee estimates that the width of the indication is about the diameter of a tube (i.e., 0.75 inches) and the height of the indication is about 0.25 inches. In addition, the licensee stated that ultrasonic thickness measurements from the outer surface of the channel head did not measure any depth to the indication.

The NRC staff did not identify any issues that required followup action at this time.