2CAN011502, Response to Request for Additional Information Concerning the Spring 2014 Steam Generator Inspections

Response to Request for Additional Information Concerning the Spring 2014 Steam Generator Inspections

ML15014A040
Person / Time
Site:	Arkansas Nuclear
Issue date:	01/12/2015
From:	Pyle S Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2CAN011502
Download: ML15014A040 (13)

Text

SEnterg Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802 Tel 479-858-4704 Stephenie L. Pyle Manager, Regulatory Assurance Arkansas Nuclear One 2CAN01 1502 January 12, 2015 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Response to Request for Additional Information Concerning the Spring 2014 Steam Generator Inspections Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6

REFERENCES:

1. Entergy letter to NRC, "Steam Generator Tube Inspection Report -

2R23," dated August 18, 2014 (2CAN081404) (ML14230A898)

2. Email from Andrea George (NRC) to David B. Bice (Entergy),

"Request for Additional Information for Spring 2014 Steam Generator Tube Inspection Report for ANO, Unit 2 (MF4653)," dated November 19, 2014 (ML14323A206)

Dear Sir or Madam:

Entergy Operations, Inc. (Entergy) inspected the Arkansas Nuclear One, Unit 2 (ANO-2) steam generator tubes during the Spring 2014 refueling outage (2R23) in accordance with ANO-2 Technical Specification (TS) 6.5.9. ANO-2 TS 6.6.7 requires a written report of the results of the inspection be submitted to the NRC. Reference 1 provided the required report.

In the course of the NRC's review of the report, it was determined that additional information was required to complete the evaluation. The purpose of this submittal is to provide the information that was requested in Reference 2 (see Attachment 1).

This correspondence contains one new commitment. This commitment is summarized in .

Aool

2CAN01 1502 Page 2 of 2 Should you have any questions regarding this submittal, please contact me.

Sincerely, 4(/

SLP/rwc Attachments: 1. Responses to Request for Additional Information Concerning the Spring 2014 Steam Generator Inspections

2. Regulatory Commitments cc: Mr. Marc L. Dapas Regional Administrator U. S. Nuclear Regulatory Commission, Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Senior Resident Inspector Arkansas Nuclear One P. 0. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Ms. Andrea E. George MS O-8B1 One White Flint North 11555 Rockville Pike Rockville, MD 20852

ATTACHMENT I TO 2CAN01 1502 RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION CONCERNING THE SPRING 2014 STEAM GENERATOR INSPECTIONS to 2CAN01 1502 Page 1 of 8 RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION CONCERNING THE SPRING 2014 STEAM GENERATOR INSPECTIONS By letter dated August 18, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14230A898), Entergy Operations, Inc. (Entergy, the licensee) submitted information summarizing the results of the Spring 2014 steam generator tube inspections performed at Arkansas Nuclear One, Unit 2. These inspections were performed during refueling outage 23 (RFO 23). In a letter dated June 23, 2014 (ADAMS Accession No. ML14170A060), the U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call that was held with the licensee during RFO 23.

In order to complete the review, the NRC staff requests responses to the follow questions:

ESGB-RAI-1 The "Cycle Effective Full Power Year (EFPY)" and "Cumulative SG EFPY" columns in Table 1-1 agree with each other up until outage "2R20." Please confirm the values for EFPY in these columns.

RESPONSE

The cumulative value following refueling outage 2R20 was listed as 8.62 which was a transcription error. The actual value should have been 8.26 or a difference of 0.36 EFPY. This was carried through the rest of the values through 2R23. See Table 1 below:

Table 1 ANO-2 Operating Cycles since SG Replacement Outage Year Cycle EFPY Cumulative Notes EFPY 2R14 2000 0 0 Baseline (PSI) 2R15 2002 1.35 1.35 ist ISI 2R16 2003 1.35 2.7 Skip 2R17 2005 1.36 4.06 54% Bobbin 2R18 2006 1.43 5.49 Skip 2R19 2008 1.35 6.84 Skip 2R20 2009 1.42 8.62 100% Bobbin 2R21 2011 1.40 10.02 Skip 2R22 2012 1.43 11.45 Skip 2R23 2014 1.39 12.84 100% Bobbin 6.84 + 1.42 = 8.26 to 2CAN01 1502 Page 2 of 8 All the EFPYs were reviewed as part of developing this response. Previously some of the values were projected values versus actual values for the outages. The table has been updated with the actual values. A corrected table with additional data is provided below (Table 2):

Table 2 ANO-2 Operating Cycles since SG Replacement Outage Year Cycle EFPD EFPY Cumulative Notes 2000 14 517.004 1.42 0.00 Baseline 2R14 (PSI) 2R15 2002 15 471.493 1.29 1.29 1st ISI 2R16 2003 16 492.902 1.35 2.64 Skip 54%

17 495.698 1.36 4.00 Bbi 2R17 2005 Bobbin 2R18 2006 18 522.796 1.43 5.43 Skip 2R19 2008 19 489.419 1.34 6.77 Skip 100%

2R20 2009 20 495.707 1.36 8.13 Bobbin 2R21 2011 21 493.944 1.35 9.48 Skip 2R22 2012 22 528.071 1.45 10.93 Skip 100%

2R23 2014 23 498.19 1.36 12.30 100%

Bobbin 2R24 2015 24 452 PROJECTED 1.24 13.53 Skip EFPD = Effective Full Power Days EFPY = Effective Full Power Years ESGB-RAI-2 The NRC staff notes that in Tables 3.6.1 and 3.6.2 of the letter dated August 18, 2014, the

"% Plugged" columns appear to be incorrect based on the number of tubes plugged in each SG. Please clarify.

RESPONSE

In the originally submitted % Plugged column, the numerical values represented did not increase the values by 100 necessary to achieve a "percent". Therefore, ifthe values are multiplied by 100, true percent values can be obtained. There are 10637 tubes per generator.

A corrected table is listed below:

to 2CAN01 1502 Page 3 of 8 Table 3 Cumulative Plugs in Service in SG A YEAR OUTAGE INSTALLED CUMULATIVE  % PLUGGED 2000 Fabrication 0 0 0 2000 Baseline 0 0 0 2002 2R15 0 0 0 2005 2R17 4 4 0.04 2009 2R20 1 5 0.05 2014 2R23 5 10 0.09 Table 4 Cumulative Plugs in Service in SG B YEAR OUTAGE INSTALLED CUMULATIVE  % PLUGGED 2000 Fabrication 1 1 0.009 2000 Baseline 0 1 0.009 2002 2R15 0 1 0.009 2005 2R17 7 8 0.08 2009 2R20 5 13 0.12 2014 2R23 5 18 0.17 ESGB-RAI-3 In the teleconference summary dated June 23, 2014, the NRC staff noted that "an evaluation of blockage of the top support plate will be done as part of the eddy current auto-analysis that is verifying the position of the AVBs [anti-vibration bars]." Please discuss the results of the position verification of the AVBs and the evaluation of the blockage of the top support plate.

RESPONSE

This analysis was being performed post outage utilizing the 2R23 eddy current data. The AVB design of the Westinghouse Delta 109 is complex and has resulted in difficulties in pinpointing the exact locations since there are changes in configuration within the individual AVBs by design. Therefore, the evaluation is not yet complete.

to 2CAN01 1502 Page 4 of 8 The original intent of the sludge buildup at the top tube support plate analysis was to evaluate the operating experience by the French where a tube locked into place due to excessive sludge build up and eventually severed due to fatigue. It was not anticipated that this would be the case for ANO-2 due to differences in the designs. This will be a qualitative assessment to determine if there is an excessive buildup of deposits. ANO-2 has operated 14 calendar years since the steam generators were replaced. The analysis will be of individual locations on the top support plate to determine the deposit at the top, bottom and center of the intersections.

Entergy will provide the information for both the AVB positioning and sludge evaluation within 45 days of Entergy's receipt of the AREVA report. Currently it is estimated that Entergy will have received the report from AREVA prior to mid-February 2015.

ESGB-RAI-4 Please discuss the results of the primary side channel head inspections and the tube plug inspections.

RESPONSE

Visual inspections of the primary side cladding and previously installed plugs were performed in 2R23. All four channel heads were included in the inspection. There were no irregularities identified in the cladding inspection or any issues identified in the previously installed plugs.

ESGB-RAI-5 Please provide a tubesheet map so the NRC staff can better understand the locations of the indications. In addition, please provide the thickness of the tubesheet with and without cladding.

RESPONSE

Please refer to the ANO-2 tubesheet map included in this letter. The tubesheet is a forged carbon steel plate with cladding installed on the primary side.

Tubesheet thickness without the clad 31.13 inches Tubesheet cladding thickness 0.43 inches Tubesheet thickness with clad 31.56 inches to 2CAN01 1502 Page 5 of 8 ESGB-RAI-6 In Section 3.2 of the letter dated August 18, 2014, a number of dents were reported. It was indicated that these dents were present in the preservice inspection. Please discuss whether these dents have been increasing in size (voltage). Please discuss whether these dents are service-induced or have been present since the preservice inspection. If service-induced, please discuss the cause.

RESPONSE

Dents (DNT) were reported with the bobbin coil examination at 1128 locations in 319 tubes.

The criteria for reporting DNTs are > 2.00 volts on Channel P1 (630 / 150 kHz differential mix) in the free span and at structures. All DNT signals have been compared with historical data and exhibited no change in signal formation, voltage, and/or phase.

The dents were fabrication induced due to elevated temperatures during post-weld heat treatment. There are no service induced dents identified to date.

ESGB-RAI-7 A number of possible loose part (PLP) indications were reported in both steam generators. In steam generator B, three parts were removed, reducing the number of PLP indications to one. Please discuss whether visual inspections were performed at all PLP locations. If visual inspections were performed, please discuss the results of these inspections. If any loose parts were left in the steam generators, please discuss the results of any assessments performed on the effect these parts may have on tube integrity.

RESPONSE

A Foreign Object Search and Retrieval (FOSAR) activity was performed to confirm / retrieve any potential objects identified by eddy current testing. Eddy current inspections identified PLP indications affecting 15 tubes in SGA and affecting 17 tubes in SGB; however, no wear was associated with any of the affected tube locations. Visual inspections were performed and all foreign material was either retrieved or determined to be acceptable as-is (unretrieved).

Refer to Table 8-1 (from operational assessment) of this letter, which summarizes the assessment of PLP indications and foreign objects identified during 2R23.

to 2CAN01 1502 Page 6 of 8 B WELDED GROUP 0 Arkansas Unit 2 - Replacement ROLLED -AREVA 5 H ROLLED - W 4 Hardware Repair Status I ROLLSTAB - W 1 FORCED SCALE: 0.283977 X Fri Jun 06 09:07:25 2014 Post RF023 - 05/14 - N-W*.. d 3I W -,-qE p.

VA..NAIAU AREr& NPAdbCI. A= A. y*t~~

p E At Drawing #: 02-6004834-E-003 DCN :121-9224603-000 S/G A TOTAL TUBES: 10637 COLD SELECTED TUBES: 10 PRIMARY FACE OUT OF SERVICE (#): 10 Manway 04 A',ý 20 40 30 -.

• 0 10 10 20 30 40 50 60 70 00 90 100 110 120 130 140 10 160 170 180 to 2CAN011502 Page 7 of 8 Table 8-1: ANO 2R23 PLP and FOSAR Summary 2R23 PLP Indications SG Row-Col. Location History 2R23 SSI Results Loose Part Wear Assessment SSI identified sludge rock at tubes 4-89, No wear identified by ECT and object not a threat 5-88, and 6-89 CL and left as-is. to tube integrity.

5-88 TSC +0.17 New PLP in 2R23 See tube R4-C89 above. See tube R4-C89 above.

6-89 TSC +0.17 New PLP in 2R23 See tube R4-C89 above. See tube R4-C89 above.

6-91 TSH +0.31 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

7-92 TSH +0.54 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

8-91 TSH +0.86 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

40-87 TSH +0.17 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

A 40-89 TSH +0.15 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

41-88 TSH +0.15 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.48-151 TSH +1.62 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.49-152 TSH +0.74 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

50-151 TSH +1.26 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

50-153 TSH +0.24 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.51-152 TSH +0.49 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

128-57 03H +3.19 NDF with PlusPt SSI not required for this PLP. No wear identified by ECT.

15-42 TSH +0.63 PLP in 2R20 & 2R23 SSI not performed for this historical PLP. No wear identified by ECT.

104-67 TSC +30.02 New PLP in 2R23 SSI could not access the elevation at this Acceptable to leave as-is. PLP is in a low flow location for visual confirmation of new PLP. region and no wear was identified by ECT.

SSI could not access the elevation at this Acceptable to leave as-is. PLP is in a low flow location for visual confirmation of new PLP. region and no wear was identified by ECT.

SSI identified and removed a long machine Object was removed and no wear was identified 115-138 TSH +4.61 New PLP in 2R23 turning piece at tubes 115-138, 116-139 by ween 117-138, 117-140, 118-139, and 119-140 by ECT.

SSI identified and removed a long machine Object was removed and no wear was identified 115-146 TSH +21.52 New PLP in 2R23 turning piece at tubes 115-146, 116-145, bj ween 116-147, 117-146, 117-148. by ECT.

to 2CAN01 1502 Page 8 of 8 2R23 PLP IndicationsT SG Row-Cl.

Row-Col. Location Location History 2R23 SSI Results Loose Part Wear Assessment 116-139 TSH +4.76 New PLP in 2R23 See Tube R115-C138 above. See Tube R115-C138 above.

116-145 TSH +21.39 New PLP in 2R23 See Tube R115-C146 above. See Tube R115-C146 above.

116-147 TSH +21.00 New PLP in 2R23 See Tube R115-Cl46 above. See Tube R115-Cl46 above.

117-138 TSH +4.63 New PLP in 2R23 See Tube R 115-C138 above. See Tube R I15-C138 above.

117-140 TSH +4.98 New PLP in 2R23 See Tube Rl 15-C138 above. See Tube R1 15-C138 above.

117-146 TSH +21.49 New PLP in 2R23 See Tube R115-C146 above. See Tube R115-C146 above.

B 117-148 TSH +20.89 New PLP in 2R23 See Tube R115-C146 above. See Tube R115-C146 above.

118-139 TSH +4.72 New PLP in 2R23 See Tube R 115-C138 above. See Tube R1 15-C138 above.

119-140 TSH +5.28 New PLP in 2R23 See Tube R115-C138 above. See Tube R115-C138 above.

SSI identified and removed a long machine Object was removed and no wear was identified 137-118 TSH +33.28 PLP in 2R20 & 2R23 turning piece at tubes 137-118, 138-119, and by ECT.

139-118.

138-119 TSH +33.66 PLP in 2R20 & 2R23 See Tube R137-C118 above. See Tube R137-C 118 above.

139-118 TSH +34.05 PLP in 2R20 & 2R23 See Tube R 1 37-C 118 above. I See Tube R137-C118 above.

ATTACHMENT 2 TO 2CAN01 1502 REGULATORY COMMITMENTS to 2CAN01 1502 Page 1 of 1 List of Regulatory Commitments This table identifies actions discussed in this letter for which Entergy commits to perform. Any other actions discussed in this submittal are described for the NRC's information and are not commitments.

TYPE (Check one) SCHEDULED COMMITMENT ONE-TIME CONTINUING COMPLETION DATE ACTION COMPLIANCE (If Required)

Entergy will provide the information for both Within 45 days of the AVB (anti-rotation bar) positioning and X Entergy receipt of sludge evaluation. AREVA report