ML051450296
| ML051450296 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/09/2005 |
| From: | Sharon Bennett Entergy Operations |
| To: | Alexion T NRC/NRR/DLPM |
| References | |
| Download: ML051450296 (7) | |
Text
Thomnas Alexion - Draft 1R18 SG 151 RAI Responses Page 1 From:
"BENNETT, STEVE A" <SBENNE2@entergy.com>
To:
"'Tom Alexion"' <twa@nrc.gov>
Date:
3/9/05 11:40AM
Subject:
Draft 1 R18 SG ISI RAI Responses
- Tom, Attached is the draft responses to Joseph Terrell's 1 R18 OTSG ISI Report. As you will notice in response to question 5, we have reduced our best estimate LBLOCA leakage due to some of the flaws being outside the pressure boundary.
Due to the ANO-2 outage, we may be limited on availability to discuss these until after the outage.
Steve Bennett NSA - Licensing 479-858-4626 Pager: 479-890-3323 CC:
"MEATHEANY, DANIEL J" <DMEATHE@entergy.com>, "GREESON, WILLIAM C0
<WG REESO @ entergy.com>
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Draft IR18 SG ISI RAI Responses 3/9/05 11:25AM "BENNETT, STEVE A" <SBENNE2@entergy.com>
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SBENNE2@entergy.com Recipients nrc.gov owf4_po.0WFNDO TWA (Thomas Alexion) entergy.com WGREESO CC (WILLIAM C GREESON)
DMEATHE CC (DANIEL J MEATHEANY)
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DRAFT Response to Requests for Additional Information (RAls)
Received on the ANO-1 1R18 Outage Steam Generator ISI Report RAI 1 - 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.
RESPONSE
No volumetric indications were identified in the upper tubesheet original roll expansion transition during 1R18. The number of axial and circumferential indications reported in the upper tubesheet original expansion transition is provided in Table 1 below.
TABLE 1 INDICATIONS SG A SG 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 1R15 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.
RESPONSE
Repair Rolls have been installed every outage since 1 R14. Table 3 provides a list of tubes with repair rolls that were repaired in 1 R1 8. This table includes the outage that the original repair roll was installed. Five tubes in SGA and 3 tubes in SGB that would have had an additional repair roll installed were plugged for other indications or because a second repair roll had already been installed (SGA R5 T11). Mix mode indications were reported based on their axial and circumferential components for condition monitoring assessment. The number of 1
DRAFT axial, circumferential and volumetric indications reported at repair roll transitions is provided in Table 2 below. The volumetric indications identified are the same upper tubesheet Intergranular Attack (IGA) that has been present since the early 1980's. 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 SG A SG B Axial 2
11 Circumferential 11 6
Volumetric 3
0 Total 16 17 TABLE 3 STEAM GENERATOR A ROW TUBE OUTAGE REPAIR TYPE 1R14&
5 11 1 R16 Repair Roll 5
11 1R18 Plug 10 34 11R14 Repair Roll 10 34 1R118 Plug 35 105 11R14 Repair Roll 35 105 1R18 Plug 38 104 11R14 Repair Roll 38 104 1R18 Plug 39 99 11R14 Repair Roll 39 99 1R118 Repair Roll 39 101 11R14 Repair Roll 39 101 1R118 Repair Roll 39 103 11R14 Repair Roll 39 103 1 R18 Repair Roll 40 98 11R16 Repair Roll 40 98 1R18 Repair Roll 54 110 1R14 Repair Roll 54 110 1R18 RepairRoll 90 54 1R14 Repair Roll 90 54 11R18 Repair Roll 98 5
1R14 Repair Roll 98 5
1R18 Repair Roll 123 2
1 R14 Repair Roll STEAM GENERATOR B ROW TUBE OUTAGE CODE 4
28 1R14 Repair Roll 4
28 1 R18 Repair Roll 10 17 1R14 Repair Roll 10 17 1R18 Plug 17 32 1R14 Repair Roll 17 32 1R18 Repair Roll 27 99 1R14 Repair Roll 27 99 1R18 Repair Roll 28 96 1R14 Repair Roll 28 96 1 R18 Repair Roll 63 48 1 R16 Repair Roll 63 48 1 R18 Repair Roll 71 51 1R14 Repair Roll 71 51 1R18 Repair Roll 73 51 1R14 Repair Roll 73 51 1R18 Repair Roll 81 11 1R14 Repair Roll 81 11
__1R18 Repair Roll 81 14 1R14 Repair Roll 81 14 1R18 Repair Roll 82 11 1R14 Repair Roll 82 11 1R18 Repair Roll 95 7
1R14 Repair Roll 2
DRAFT 123 2
1R18 Repair Roll 132 35 1R14 Repair Roll 132 35 1 R18 Repair Roll 141 26 1R14 Repair Roll 141 26 1R18 Plug 142 51 1R14 Repair Roll 142 51 1R18 Repair Roll 144 42 1R14 Repair Roll 144 42 1R18 Repair Roll 95 7
1 R18 Repair Roll 111 2
1R14 Repair Roll 111 2
1_R18 Repair Roll 115 8
11R14 Repair Roll 115 8
1R18 Plug 132 53
_1R14 Repair Roll 132 53 11R18 Repair Roll 138 67 1R14 Repair Roll 138 67 1R18 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.).
RESPONSE
Single Axial and Multiple Axial indications are ODSCC while the volumetric indications are IGA patches. The 1R18 breakdown of indications is provided in Table 4 below.
Table 4 INDICATIONS SG A SG 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.
RESPONSE
The following Table 5 lists the different mechanisms identified and the associated estimated leakage:
3
DRAFT TABLE 5 1R18 Leakage Condition Mechanism Actual Monitoring Met?
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 (SAA/MAA) 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 0.54 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.
4
DRAFT
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 1 R1 8.
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 (SG "A").
The same general approach was used during 1 R1 8 as was used in 1 R1 7 with the exception of the inclusion of the Lower-Tube-Sheet examination into the 1 R1 8 LBLOCA leakage evaluation.
TABLE 6 LORT Total TEC Flaws UORT Flaws URRT Flaws LORT Flaws Total Flaws Flaws Contributing to Leakage 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 5