1CAN080501, License Amendment Request Response to NRC Request for Additional Information on ANO-1 Once Through Steam Generator Inservice Inspection Report

License Amendment Request Response to NRC Request for Additional Information on ANO-1 Once Through Steam Generator Inservice Inspection Report

ML052230276
Person / Time
Site:	Arkansas Nuclear
Issue date:	08/08/2005
From:	James D Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
1CAN080501
Download: ML052230276 (11)

Text

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Entergy Operations, Inc.

1448 S.R. 333 Entergy Russeliville, AR 72802 Tel 479-858-4619 Dale E. James Acting, Director, Nuclear Safety Assurance 1CAN080501 August 8, 2005 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

License Amendment Request Response to NRC Request for Additional Information on ANO-1 Once Through Steam Generator Inservice Inspection Report Arkansas Nuclear One, Unit 1 Docket No. 50-313 License No. DPR-51

REFERENCES:

1 Entergy letter dated August 3, 2004, Once Through Steam Generator Inservice Inspection Report Arkansas Nuclear One, Unit I (1CAN080401) 2 Entergy letter dated March 1, 2004, Response to NRC Request for Additional Information Regarding ANO-1 Steam Generator Tube Inservice Inspection Report from 1RI7 (1CAN030402)

Dear Sir or Madam On August 3, 2004 (Reference 1), Entergy provided the Arkansas Nuclear One, Unit 1 (ANO-1),

Once Through Steam Generator Inservice Inspection Report in accordance with Technical Specification 5.6.7.a. This report covered steam generator (SG) inspection activities for the ANO-1 eighteenth refueling outage (1R18). As part of that report, Entergy provided the best-estimate total leakage that would result from an analysis of the limiting large break loss of coolant accident.

As a result of NRC Staff review of this report, requests for additional information (RAls) were provided to Entergy on December 3, 2004 and May 31, 2005. Entergy provided draft responses to these RAls on March 9, 2005 and June 21, 2005, respectively. This letter provides the documentation for the NRC RAls and Entergy's response to these RAls.

1'7

1CAN080501 Page 2 of 2 This submittal contains no new commitments. Should you have any questions, please contact Steve Bennett at (479) 858-4626.

-sicerely, DEJ/s a hments:

Response to Requests for Additional Information (RAls) Received on December 3, 2004, regarding the ANO-1 IR18 Outage Steam Generator Inservice Inspection Report

2. Response to Requests for Additional Information (RAls) Received on May 31, 2005, regarding the ANO-1 1R18 Outage Steam Generator Inservice Inspection Report cc: Dr. Bruce S. Mallett Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. Mohan Thadani MS O-7D1 Washington, DC 20555-0001 Mr. Bernard R. Bevill Director Division of Radiation Control and Emergency Management Arkansas Department of Health 4815 West Markham Street Little Rock, AR 72205

Attachment I I CAN080501 Response to Requests for Additional Information (RAls) Received on December 3, 2004 regarding the ANO-I 1RI8 Outage Steam Generator Inservice Inspection Report to 1CAN080501 Page 1 of 5 Response to Requests for Additional Information (RAls) Received on December 3, 2004 regarding the ANO-1 IRI8 Outage Steam Generator Inservice Inspection Report RAI I - On page 5 of the C-3 submittal regarding the upper tubesheet original roll transitions, it was stated that the 172 total indications found in OTSG-A and OTSG-B included axial, circumferential, and volumetric indications, and that all of the tubes with these indications were re-rolled.

Provide a breakdown of these indications in terms of the number of axial, circumferential, and volumetric indications for each OTSG. Describe your assessment concerning the defect mechanism and cause of the volumetric indications.

ANO Response:

No volumetric indications were identified in the upper tubesheet original roll expansion transition during 1R1 8. The number of axial and circumferential indications reported in the upper tubesheet original expansion transition is provided in Table 1 below.

TABLE I INDICATIONS OTSG A OTSG B Axial 79 91 Circumferential 2 0 Total 81 91 RAI 2 - On page 5 of the C-3 submittal regarding the upper tubesheet re-roll transitions, it was stated that the 33 total indications found in OTSG-A and OTSG-B included volumetric and axial/mixed mode indications, and that these indications were repaired by installing a second re-roll below the initial re-roll.

Confirm that re-rolls were performed only during the 1R14 and IR15 outages. Provide a breakdown of these indications in terms of: (a) the outage in which the re-roll was performed, and (b) the number of volumetric and axial/mixed mode indications for each OTSG. Describe your assessment concerning the defect mechanism and cause of the volumetric indications.

ANO Response:

Repair Rolls have been installed every outage since 1R14. Table 3 provides a list of tubes with repair rolls that were repaired in 1RI 8. This table includes the outage that the original repair roll was installed. Five tubes in OTSG-A and 3 tubes in OTSG-B that would have had an additional repair roll installed were plugged for other indications or because a second repair roll had already been installed (OTSG-A R5 T11). Mix mode indications were reported based on their axial and circumferential components for condition monitoring assessment. The number of axial, circumferential and volumetric indications reported at repair roll transitions is provided in Table 2 below. The volumetric

Attachment I to 1CAN080501 Page 2 of 5 indications identified are the same upper tubesheet Intergranular Attack (IGA) that has been present since the early 1980s. This mechanism was initiated by high sulfate concentrations which have been removed therefore the initiation of new IGA patches in the unexpanded portion of the tube is essentially zero. The volumetric indications identified in the repair rolls are believed to be old initiation sites that when stressed by the installation of a repair roll, over time, grow to become detectable with eddy current testing.

TABLE 2 INDICATIONS OTSG-A OTSG-B Axial 2 11 Circumferential 11 6 Volumetric 3 0 Total 16 17 TABLE 3 OTSG-A OTSG-B ROW TUBE OUTAGE REPAIR TYPE ROW TUBE OUTAGE CODE 1R14 &

5 11 1R16 Repair Roll 4 28 1R14 Repair Roll 5 11 1R18 Plug 4 28 1R18 Repair Roll 10 34 1R14 Repair Roll 10 17 1R14 Repair Roll 10 34 1R18 Plug 10 17 1R18 Plug 35 105 1R14 Repair Roll 17 32 1R14 Repair Roll 35 105 1R18 Plug 17 32 1R18 l Repair Roll 38 104 1R14 Repair Roll 27 99 1R14 Repair Roll 38 104 1R18 Plug 27 99 1R18 Repair Roll 39 99 1R14 Repair Roll 28 96 1R14 Repair Roll 39 99 1R18 Repair Roll 28 96 1R18 Repair Roll 39 101 1R14 Repair Roll 63 48 1R16 Repair Roll 39 101 1R18 Repair Roll 63 48 IR18 Repair Roll 39 103 1R14 Repair Roll 71 51 1R14 Repair Roll 39 103 1R18 Repair Roll 71 51 1R18 Repair Roll 40 98 1R16 Repair Roll 73 51 1R14 Repair Roll 40 98 1R18 Repair Roll 73 51 1R18 Repair Roll 54 110 1R14 Repair Roll 81 l 1 1R14 Repair Roll 54 110 1R18 Repair Roll 81 l 1 1R18 Repair Roll 90 54 1R14 Repair Roll 81 14 1R14 Repair Roll 90 54 1R18 Repair Roll 81 14 1R18 Repair Roll 98 5 1R14 Repair Roll 82 11 1R14 Repair Roll 98 5 1R18 Repair Roll 82 11 1R18 RepairRoll

- to 1CAN080501 Page 3 of 5 OTSG-A OTSG-B ROW TUBE OUTAGE REPAIR TYPE ROW TUBE OUTAGE CODE 123 2 1R14 Repair Roll 95 7 1R14 Repair Roll 123 2 1R18 Repair Roll 95 7 1RI8 l Repair Roll 132 35 1R14 Repair Roll i11 2 1R14 Repair Roll 132 35 1R18 Repair Roll 111 2 1R18 Repair Roll 141 26 1R14 Repair Roll 115 8 1R14 Repair Roll 141 26 1R18 Plug 115 8 1RI8 Plug 142 51 1R14 Repair Roll 132 53 1R14 Repair Roll 142 51 1R18 Repair Roll 132 53 1RI8 Repair Roll 144 42 1R14 Repair Roll 138 67 1R14 Repair Roll 144 42 1RI8 Repair Roll 138 67 1RlB Repair Roll 140 18 1R14 Repair Roll 140 18 1R18 Plug RAI 3 - In Table 2 of the 90-day submittal, it is reported that a total of 64 upper tubesheet crevice indications were detected. Describe the indications in more detail, including a more detailed description of each indication (i.e., single axial indication, single circumferential indication, volumetric indication, etc.), and a defect mechanism (i.e.,

ODSCC, intergranular attack, etc.).

ANO Response:

Single Axial and Multiple Axial indications are Outside Diameter Stress Corrosion Cracking (ODSCC) while the volumetric indications are IGA patches. The 1R18 breakdown of indications is provided in Table 4 below.

Table 4 INDICATIONS OTSG-A OTSG-B Single Axial 59 0 Multiple Axial 3 0 Volumetric 1 1 Total 63 1 RAI 4 - In the 90-day submittal, the condition monitoring leakage estimates for upper tube end cracking (Tables 4 and 5) and upper tubesheet ODIGA (Table 10) were given. Identify any other mechanisms and their contributions to total condition monitoring estimate of accident-induced leakage. State the condition monitoring estimate of total accident-induced leakage from all mechanisms.

ANO Response:

The following Table 5 lists the different mechanisms identified and the associated estimated leakage:

Attachment 1 to 1CAN080501 Page 4 of 5 TABLE 5 Condition Mechanism 1R18 Leakage Actual Monitoring Met?

OTSG-A OTSG-B TSP Wear New 0 0 Yes TSP Wear Old 0 0 Yes ORT Axial 0 0 Yes ORT Circ 0 0 Yes Re-roll Cracking (Heel) 0 0 Yes Re-roll Cracking (Toe) 0 0 Yes Sleeve Cracking 0 0 Yes FS Groove IGA 0 0 Yes FS Volumetric 0 0 Yes TSP Axial 0 0 Yes TSP Circ 0 0 Yes TSP & Dent Volumetric 0 0 Yes Dent Axial 0 0 Yes UTS Axial 0 0 Yes LTS Axial, Circ and Volumetric 0 0 Yes TEC UTS (SAAIMAA) 0.568 0.409 Yes TEC LTS 0.0016 0.0031 Yes UTS IGA 0.0962 0.104 Yes Installed Re-roll Leakage 0.001 0.001 Yes Hardware Plugs and Sleeves 0.02 0.02 Yes Total 0.69 0.64 TSP = Tube Support Plate ORT = Original Roll Transition FS = Free Span LTS = Lower Tube Sheet TEC = Tube End Cracking IGA = Inter-Granular Attack RAI 5 - The cover letter for the 90-day submittal states that the calculated total best estimate LBLOCA leakage during 1R18 is estimated to be 2.57 gpm for the initial two minutes and 1.49 gpm for the remaining 30 days. Provide a summary of the flaws used in the LBLOCA leakage evaluation and discuss their individual contributions to the leak rate.

Discuss whether the general approach used to evaluate LBLOCA leakage for 1R18 was the same as that used during 1R17, and describe any differences.

to 1CAN080501 Page 5 of 5 ANO Response:

During the process of answering this question, it was discovered that there were flaws that had been classified as being in the pressure boundary (IPB), when in fact the flaws were located out of the pressure boundary (OPB). This resulted in a revision to the calculated total best estimate LBLOCA leakage during 1R18. The best estimate LBLOCA leakage has been revised to be 1.29 gpm for the initial two minutes and 0.02 gpm for the remaining 30 days; instead of the 2.57 gpm and 1.49 gpm that had been originally reported. Table 6 below lists the location, quantity, and leakage amounts for the flaws used in the LBLOCA leakage evaluation for the most limiting steam generator (OTSG-A).

The same general approach was used during 1R18 as was used in 1R17 with the exception of the inclusion of the Lower-Tube-Sheet examination into the I R1 8 LBLOCA leakage evaluation.

TABLE 6 TEC UORT URRT LORT Total Flaws Contributing to Leakage Flaws Flaws Flaws Flaws Flaws Flaws Contributing zero LBLOCA Leakage 281 7 329 1 618 Flaws Contributing to LBLOCA Leakage 43 0 18 0 61 Total Flaws 324 7 347 1 679 TEC UORT URRT Axials, Sleeves, Total Leakage Assignment Leakage Leakage Leakage Plugs, etc. Leakage Average LBLOCA - Leak Rate for first 2 minutes 0.83 0.00 0.44 0.02 1.29 Average LBLOCA - Leak Rate for 30 days 0 0 0 0.02 0.02 OPB - Out of Pressure Boundary TEC - Tube End Crack UORT - Upper-Tube-Sheet Original Roll Transition URRT - Upper-Tube-Sheet Re-Roll Transition LORT - Lower-Tube-Sheet Original Roll Transition

Attachment 2 I CAN080501 Response to Requests for Additional Information (RAIs) Received on May 31, 2005 regarding the ANO-1 1R18 Outage Steam Generator Inservice Inspection Report to 1CAN080501 Page 1 of 2 Response to Requests for Additional Information (RAls) Received on May 31, 2005 regarding the ANO-1 IRI8 Outage Steam Generator Inservice Inspection Report The August 3, 2004, report (ADAMS Accession No. ML042240207) provided the results for the calculated total best-estimate large-break loss-of-coolant accident (LBLOCA) leakage during the ANO-1 eighteenth refueling outage (1R18). The calculated total best-estimate LBLOCA leakage for Cycle 18 was estimated to be 2.57 gallons-per-minute (gpm) for the initial two minutes and 1.49 gpm for the remaining 30 days. In Question 5 of the NRC staffs request for additional information (see e-mail at ADAMS Accession No. ML051450289), the licensee was asked to provide a summary of the flaws used in the evaluation and to discuss their individual contributions to the leak rate. In their draft response (see e-mail at ADAMS Accession No. ML051450296), the licensee discovered that there were flaws that had been classified as being in the pressure boundary during the original calculation, but were in fact outside the pressure boundary. When the licensee re-calculated the total best estimate LBLOCA leakage for Cycle 18, the estimate was revised downward. The revised best estimate LBLOCA leakage was estimated to be 1.29 gpm for the initial two minutes and 0.02 gpm for the remaining 30 days.

The staff notes that the licensee's LBLOCA leakage estimate during the previous refueling outage (1R17) considered the potential leakage of all circumferential cracks found during the inspection, including those above the re-roll repairs, because of the possibility that a leak path could exist around the roll or re-roll joints.

RAI 1. Discuss why the flaws in question were classified as being inside the pressure boundary for the original LBLOCA leakage estimate for Cycle 18, and discuss the basis for re-classifying the flaws as being outside of the pressure boundary. Include in your discussion the reasons why you concluded that the flaws in question should not be included in the LBLOCA leakage estimate and why the revised leakage estimate is conservative.

ANO Response:

The difference was due to the way the analyst labeled flaws in the steam generator database for 1R18. The program used to calculate LBLOCA leakage acquired data based on the way they were labeled in the steam generator database. Therefore, some flaws were conservatively called to be inside the pressure boundary (i.e. like a crack in a transition above the roll). As a result, a higher LBLOCA leakage value was reported in the 1R18 OTSG ISI report.

This methodology for 1RI 8 is consistent with the methodology used in the previous cycle (1R17). The revised 2-minute leakage value of 1.29 gpm is believed to be representative of the as-found flaws discovered during I RI8. However, even if the leakage value was not revised downward, the previously reported leakage value of to 1CAN080501 Page 2 of 2 2.57 gpm is still well within the accident leakage of 9.0 gpm for the initial 2 minutes and 3.0 gpm for the remaining 30 days (Reference 2). Either value still retains conservative margin to the accident analysis.

RAI 2. Discuss whether the LBLOCA leakage estimate methodology (ie., not considering cracks above original rolls or re-roll repairs in the leakage estimate) has changed since the previous outage. If the LBLOCA leakage estimate methodology has changed, provide a technical basis. Include in your discussion the reasons why the leakage of flaws above the original rolls or re-roll repairs during a LBLOCA is no longer important in your assessment.

ANO Response:

As mentioned in question 1 above, the methodology is the same, therefore there is no difference. The flaws above the rolls are still included but are limited by the leakage past the roll.