ML14311A318

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10/09/2014 Summary of Conference Call with Donald C. Cook Nuclear Plant, Unit 1 Regarding the Fall 2014 Steam Generator Inspections (TAC No. MF4714)
ML14311A318
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 11/14/2014
From: Chawla M L
Plant Licensing Branch III
To: Weber L J
Indiana Michigan Power Co
Chawla M L
References
TAC MF4714
Download: ML14311A318 (11)
v • d • e


Text

Mr. Lawrence J. Weber Senior Vice President and Chief Nuclear Officer UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 14, 2014 Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, Ml 49106

SUBJECT:

SUMMARY OF CONFERENCE CALL WITH DONALD C.COOK NUCLEAR PLANT UNIT 1 REGARDING THE FALL 2014 STEAM GENERATOR INSPECTIONS (TAC NO. MF4714)

Dear Mr. Weber:

On October 9, 2014, the U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with representatives of Indiana Michigan Power Company (the licensee) regarding the ongoing steam generator (SG) inspection activities at the Donald C. Cook Nuclear Plant, Unit 1. In support of the conference call, the licensee provided slides (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 14287 A330) concerning the preliminary results of the fall 2014 SG tube inservice inspections. The information provided by the licensee in support of the teleconference is part of the enclosed conference call summary. Based on the information provided by the licensee, the NRC staff did not identify any issues that warranted immediate follow up action. However, the staff asked to be notified in the event that any unusual conditions were detected during the remainder of the outage including whether any in-situ pressure tests were performed.

L. Weber If you have any questions regarding this matter, I may be reached at 301-415-8371. Docket No. 50-315

Enclosure:

Conference call summary cc: Distribution via ListServ Sincerely, Mahesh Chawla, Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation CONFERENCE CALL SUMMARY REGARDING DONALD C. COOK NUCLEAR PLANT. UNIT 1 FALL 2014 STEAM GENERATOR INSPECTIONS DOCKET NO. 50-315 TAC NO. MF4714 On October 9, 2014, the U.S. Nuclear Regulatory Commission staff of the Steam Generator Tube Integrity and Chemical Engineering Branch (ESGB) of the Division of Engineering participated in a conference call with representatives of Indiana Michigan Power Company (the licensee) regarding the ongoing steam generator (SG) inspection activities at the Donald C. Cook Nuclear Plant, Unit 1. In support of the conference call, the licensee provided slides (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 14287 A330) concerning the preliminary results of the fall 2014 SG tube inservice inspections. The Donald C. Cook Nuclear Plant, Unit 1 has four Babcock and Wilcox International Model 51 R replacement SGs that were installed in December 2000. Each SG has 3496 thermally treated Alloy 690 tubes with a nominal outside diameter of 0.875 inches and a nominal wall thickness of 0.049 inches. During manufacturing, all tubes were hydraulically expanded at each end for the full depth of the tubesheet. The tubesheet was drilled on a triangular pitch with 1.1875-inch spacing, center-to-center. The radius of row 1 U-bends is 4. 75 inches and the bends in rows 1 through 13 were stress relieved after bending. The tubes are supported by lattice grid tube supports and flat fan bars constructed from Type 410 stainless steel. Each lattice grid tube support consists of interlocking high (3.15 inches high and 0.135 inches thick) and low ( 1 inch high and 0.135 inches thick) bars that form a lattice pattern. This lattice provides lateral support in the straight section of the tube. Abbreviations used in the licensee-provided documents include:

  • CL-cold leg
  • NRC-U.S. Nuclear Regulatory
  • EPRI -Electric Power Research Commission Institute
  • PLP -possible loose part
  • FO -foreign object
  • R#/C# -Row#, Column #
  • FOSAR -foreign object search and
  • RPC -rotating pancake coil retrieval
  • SG -steam generator
  • HL-hot leg
  • TTS -top of tubesheet
  • MFP -main feed water pump
  • TW-through-wall
  • N/A-not applicable
  • NEI -Nuclear Energy Institute Additional clarifying information regarding the licensee-provided document and information not included in the licensee-provided document is summarized below: Enclosure
  • The examinations at the top of the tubesheet were from 3 inches above to 3 inches below the top of the tubesheet.
  • Based on the operational assessment from the previous outage, the number and severity of wear indications is consistent with expectations.
  • The majority of the larger fan bar wear indications were seen in the previous outage (i.e., very few of the fan bar wear indications are new indications).
  • The growth rates of the more significant fan bar wear indications are relatively small. For example, the 38 percent TW indication at R78/C62 in SG 11 grew by 6 percent TW from 32 percent TW in the previous outage. The growth rate of the larger fan bar wear indications has decreased by approximately 20 percent.
  • The most significant lattice grid indication in SG 12 is located at the 3rd hot leg support in R56/C86 and is 18 percent TW.
  • The large number of loose part indications is the result of a strainer failure in the main feed pump from the previous operating cycle.
  • With respect to the table on pages 4 and 5, "not attempted" includes the meaning that the licensee will not attempt to retrieve the loose part from the SGs.
  • The licensee indicated that the polymer found near tube R82/C54 is about 1.5 to 2 inches in length and 0.5 inches in diameter. It was classified as "poly" based on its white color. The licensee plans to assess the chemical composition of this polymer to determine if it is acceptable to leave it in service.
  • Sludge lancing in the previous inspection removed about 75 pounds of material in total.
  • Based on visual inspections, the top of the tube bundle appeared to be free of deposits. Prior deposit mapping studies indicated that there may be deposit buildup in this region. 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 including whether any in-situ pressure tests were performed.

Preliminary Information from Ongoing U1 C26 Activities 10/09/2014 NRC Questions Page 3 of 8 Status: (10/9/14@ 1144) Full Length Hot Leg Cold Leg Overall (Bobbin) Top of Tubesheet Top of Tubesheet % % (RPC) (RPC) Complete Complete %Complete %Complete SG 11 83.8 0 0 57.2 SG 12 82.1 0 0 56.2 SG 13 74.9 0 0 51.1 SG 14 78.5 0 52.8 62.2 1. Discuss any trends in the amount of primary-to-secondary leakage observed during the recently completed cycle. R1: No primary-to-secondary leakage has been detected since the steam generators were replaced in 2000. This includes the recently completed cycle of operation. 2. Discuss whether any secondary side pressure tests were performed during the outage and the associated results. R2: No steam generator secondary side pressure tests were planned or performed during the outage. 3. Discuss any exceptions taken to the industry guidelines. R3: No exceptions have been taken to the EPRI Steam Generator Guidelines (inclusive of the examination, integrity, insitu, leak or water chemistry guidelines) or the NEI 97-06 Steam Generator Program Guidelines. 4. For each SG, provide a description of the inspections performed including the areas examined and the probes used (e.g., dents/dings, sleeves, expansion-transition, U-bends with a rotating probe), the scope of the inspection (e.g., 100 percent of dents/dings greater than 5 volts and a 20 percent sample between 2 and 5 volts), and the expansion criteria. R4* Exam Full HUCL Special Special Special Special Special Length TTS Interest-Interest Interest Interest Interest Lattice Foreign New Dents & Proximity Grids Objects Bobbin Dings & Fan Bars Probe Bobbin +Point +Point +Point +Point +Point +Point All SGs 100% -25% All wear All All /-codes All current All TW PLPs!FO dents/dings indications Wear 2 volts of proximity All confirmed but not removed FO locations New FO I'd by FOSAR Expansion NIA C-1,C-2, NIA Minimum 1 NIA NIA NIA Criteria C-3 tube bound criteria Preliminary Information from Ongoing U1C26 Activities 10/09/2014 NRC Questions Page 4 of 8 5. For each area examined (e.g., tube supports, dent/dings, sleeves, etc), provide a summary of the number of indications identified to-date for each degradation mode (e.g., number of circumferential primary water stress corrosion cracking indications at the expansion transition). For the most significant indications in each area, provide an estimate of the severity of the indication (e.g., provide the voltage, depth, and length of the indication). In particular, address whether tube integrity (structural and accident induced leakage integrity) was maintained during the previous operating cycle. In addition, discuss whether any location exhibited a degradation mode that had not previously been observed at this location at this unit (e.g., observed circumferential primary water stress corrosion cracking at the expansion transition for the first time at this unit). R5: SG Fan Bar Lattice Grid Foreign Object Wear Wear SG 11 710 5 SG 12 461 13 SG 13 430 8 SG 14 828 15 Totals 2429 41 Fan Bar Significant Indications

  • SG 11 -R78/C62-38% fan barFB4
  • SG 12 -R76/C64 -37% fan barFB4
  • SG 13 -R70/C54 -34% fan barFB4
  • SG 14-R77/C65-32% fan barFB5 Lattice Grid Significant Indications
  • SG 11 -R34/C36-16% lattice grid 04H
  • SG 12 -R62/C66-12% lattice grid 03H
  • SG 13-R42/C42 -12% lattice grid 05H
  • SG 14-R57/C45-10% lattice grid 03H Foreign Object Wear Significant indications
  • None to date Wear 0 0 0 0

0 Based upon our ongoing condition monitoring assessment tube integrity (both structural and accident induced leakage integrity) was maintained during the previous operating cycle. No new degradation mechanisms have been identified during the course of the inspection and no locations along the tube exhibited a degradation mode that had not previously been observed at this location at this unit. 6. Describe repair/plugging plans. R6: Tube repairs will be limited to mechanical plugging and stabilization (if required). Single cycle and double cycle plugging scenarios are being evaluated. 7. Describe in-situ pressure test and tube pull plans and results (as applicable and if available). R7: lnsitu screenings are in progress as the remaining data is being reviewed by our tube integrity engineer; however no insitu testing is expected. No conditions have been detected which would suggest a tube pull will be required during this inspection.

Preliminary Information from Ongoing U1C26 Activities 10/09/2014 NRC Questions Page 5 of 8 8. Discuss the following regarding loose parts:

  • what inspections are performed to detect loose parts
  • a description of any loose parts detected and their location within the SG (including the source or nature of the loose part, if known)
  • if the loose parts were removed from the SG
  • indications of tube damage associated with the loose parts RB: Loose part inspections include:
  • Visual inspections at the top of the hot and cold leg tubesheets o Divider lane o Bundle periphery o Historical loose part locations * +Point probe examination is being performed on the hot and cold leg peripheral tubes (+1-3'} at the top of tubesheet. The typical examination pattern is shown below by the red tubes. . .*.*:*:*:*:*:*:*:*:*.** . * . :. :::::::::::::::::::::::::::::::.:.4 ,, ******************************-****************************************************************************
  • Bobbin coil examination of the tube bundle is being performed using a turbo mix has been noted as enhancing bobbin probe detection of foreign object wear at the top of tubesheet Loose parts were prioritized based on engineering evaluations which included applying a comparative wear analysis to those foreign objects which could not otherwise be dispositioned based, for instance, on legacy status or size. This approach is consistent with the prescriptions of EPRI Report 1020989, Steam Generator Management Program: Foreign Object Prioritization Strategy for Triangular Pitch Steam Generators. The following table summarizes the loose parts detected, retrieval status, priority and suspected source. Currently, (RPC inspections in progress) no tube damage has been attributed to these objects.

>' 11 12 ::s<l Preliminary Information from Ongoing U1 C26 Activities 10/09/2014 NRC Questions Page 6 of 8 (j$j:,;:: Wire (legacy) R53/C19 HL TTS Not 3 Unknown atter1pted Debris R7/C107 CL TTS Yes 2 MFP Strainer Debris R32/C102 CL TTS Yes 2 MFP Strainer Debris R85/C55 CL TTS Yes 2 MFP Strainer Strainer piece R84/C64 HL TTS Yes 1 MFP Strainer Unknown R66/C40 HL TTS No 2 or3 Unknown Strainer piece R84/C56 HL TTS Yes 1 MFP Strainer Metal piece R44/C98 HL TTS Yes 3 Unknown Debris R811C71 HL TTS Yes 2 MFP Strainer Strainer piece R37/C49 HL TTS Not 3 MFP attempted Strainer Weld slag R83/C49 HL TTS 3 Unknown (legacy' Sludge R57/C39 HL TTS Not 3 Lancing (legacy) attempted Hard R56/C36 HL TTS 3 Lancing collar(legacy) Bristle R83/C41 HL TTS Not 3 MFP attempted Strainer Strainer bits R851C53 HL TTS Yes 3 MFP Strainer Bristle R85/C59 CL TTS Not 3 MFP attempted Strainer Bristle R81/C71 CL TTS Yes 1 MFP Strainer Unknown R39/C23 HL TTS Not 3 Unknown atter1pted Bristle R29/C103 HL TTS Yes 3 MFP Strainer Strainer piece R44/C98 HL TTS Not 3 MFP aLLvt lf.JIO"U Strainer Mletallic curl R471C97 HL TTS Yes 2 u lf\IIUW. Strainer piece R761C32 HL TTS Yes 1 MFP Strainer Poly R82/C54 CL TTS 1 Unknown Sludge R83/C67 CL TTS 3 Lancing Unknown R81/C69 CL TTS Not 2 Unknown attempted Poly? R1/C21 HL TTS Yes 1 Unknown Sludge R4/C28 CL TTS Not 3 Lancing attempted Unknown R6/C80 CL TTS Not 3 Unknown attern_Rled Urtf\1/uvv, R74/C30 HL TSS Yes Unknovvr Strainer piece R77/C41 HL TSS No 1 MFP r,:', * ';1:%: None None None None None None None None None None None None None None None None None None None None None None None None None _None None None None None Strainer *' "< ' ' Lt:::;t,, -**vriil. ,* c ** -'\,

,);.1".:*.;*;*.* 13 14 i :; (':nnnAr nUt (legacy) Curved metal s (legacy) Curved metal s (legacy) Curved plate {lt::ydcy) Metal plate (legacy) Sludge (legacy) Possible strainer Metal plate Granular debri Tiny wire Thin bristle Debris Mag. base hook Preliminary Information from Ongoing U1 C26 Activities 10/09/2014 NRC Questions Page 7 of 8 R85/C61 CL TTS Not 3 Unknown None attempted R67/C27 CL TTS Not 3 Unknown None R42/C12 HL TTS Not 3 Unknown None attempted R65/C25 HL TTS Not 3 Unknown None attempted R13/C43 HL TTS Not 3 Unknown None attempted R54/C16 HL TTS Not 3 Unknown None attempted R63/C43 HL TTS Not 3 Lancing None attempted R83/C67 CL TTS Yes 1 MFP None strainer R81/C71 HL TTS Yes 1 Unknown None R85/C61 HL TTS Not 3 Unknown None attempted R2/C50 HL TTS Not 3 Unknown None attempted R851C53 HL TTS Not 3 Unknown None attempted R81/C37 HL TTS Disirtegrated 2 U* 1\1/UVI II None NTL TTS Yes --Unknown None 9. Discuss the scope and results of any secondary side inspection and maintenance activities (e.g., in-bundle visual inspections, feedring inspections, sludge lancing, assessing deposit loading, etc). R9: Secondary side activities include top of the tube sheet visual inspections as discussed previously. No abnormal conditions were noted during these inspections; with the exception of the foreign objects summarized above. Sludge lancing was performed in each of the steam generators. Removal weights are noted below: SG 11: 11.5 lbs. SG 12: 9 lbs. SG 13: 12 lbs. SG 14: 10.5 lbs. Total: 43 lbs. A visual inspection was performed in the SG 14 steam drum. The primary and secondary hatches were examined as were a sample of the primary and secondary separators, accessible areas of the feedring, a sampling of j-nozzles, decking and support structures. In addition, limited upper bundle views were gathered of the tube bundle and U-bend support structure via remote camera through the separators. No signs of erosion or degradation were identified in any of the areas examined. 10. Discuss any unexpected or unusual results. R10: None Preliminary Information from Ongoing U1 C26 Activities 10/09/2014 NRC Questions Page 8 of 8 11. Provide the schedule for steam generator-related activities during the remainder of the current outage. R11: Eddy current inspection complete: Plugging complete: Nozzle dam removal: Reinstall primary manways: 10111114 10113114 10115114 10116114

  • ML 14311A318 .. OFFICE NRR/LPL3-1/PM NRR/LPL3-1/LA DSS/SCVB/BC NRR/LPL3-1/BC NRR/LPL3-1/PM NAME MChawla MHenderson GKulesa DPelton MChawla DATE 11/10/2014 11/13/2014 10/22/2014 11/14/2014 11/14/2014
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