ML063620418
| ML063620418 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 12/27/2006 |
| From: | Murillo R Entergy Nuclear South |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| W3F1-2006-0066 | |
| Download: ML063620418 (11) | |
Text
-_Entergy Entergy Nuclear South Entergy Operations, Inc.17265 River Road Killona, LA 70057-3093 Tel 504-739-6715 Fax 504-739-6698 rmurill(~enterav.com Robert J. Murillo Licensing Manager Waterford 3 W3F1 -2006-0066 December 27, 2006 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
REFERENCES:
Response to Request for Additional Information (RAI)Regarding RF 13 Steam Generator Tube Inspections Waterford Steam Electric Station, Unit 3 Docket No. 50-382 1 Entergy letter dated May 24, 2005 "Combined C-3 and 15-Day Special Report SR-05-001
-00 on the 13th' Refueling Outage Steam Generator Tube I nservice Inspection" (W3F1 -2005-0037))
2 Entergy letter dated May 17, 2006 "12-Month Special Report SR-06-001-00 on the 1 3 th Refueling Steam Generator Tube Inservice Inspection" (W3F1 -2006-0024) 3 NRC letter dated October 11, 2006, Request for Additional Information Regarding Steam Generator Tube Inspections
Dear Sir or Madam:
In Reference 1, Entergy Operations, Inc. (Entergy) provided the number of tubes plugged in each Steam Generator (S/G) in refueling outage 13, as specified by Technical Specification (TS) 4.4.4.5.a, within 15 days following completion of S/G tube Inservice Inspection (ISI). In Reference 2, Entergy provided the complete eddy current test results for refueling outage 13, as specified by TS 4.4.4.5.b, within 12 months following the inspection.
The report contained the number and extent of tubes inspected, the location and percent of wall-thickness penetration for each indication of an imperfection, and the identification of tubes plugged or sleeved.On October 11, 2006, Entergy received an NRC request for additional information to support the review of the 13 th Refueling Outage Steam Generator Tube Inservice Inspection.
On December 8, 2006, Entergy and a member of your Staff held a conference call to discuss the status of the RAI response and Waterford-3's need to revise the reply date. A two week extension to the original reply date of December 11, 2006 was granted. Entergy's response is contained in Attachment
- 1.
W3F1 -2006-0066 Page 2 of 3 There are no new commitments contained in this letter. If you have any questions or require additional information, please contact Ron Williams at 504-739-6255.
Sincerely, RLJM/R LW!
Attachment:
1 .Response to Requests for Additional Information (RAI)Regarding RF13 Steam Generator Tube Inspections W3F1 -2006-0066 Page 3 of 3 cc: Dr. Bruce S. Mallett U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 NRC Senior Resident Inspector Waterford 3 P.O. Box 822 Killona, LA 70066-0751 U.S. Nuclear Regulatory Commission Attn: Mr. Mel Fields MS O-7D1 Washington, DC 20555-0001 Wise, Carter, Child & Caraway Attn: J. Smith P.O. Box 651 Jackson, MS 39205 Winston & Strawn Attn: N.S. Reynolds 1400 L Street, NW Washington, DC 20005-3502 Louisiana Department of Environmental Quality Office of Environmental Compliance Surveillance Division P.O0. Box 4312 Baton Rouge, LA 70821-4312 American Nuclear Insurers Attn: Library Town Center Suite 300S 2 9th S. Main Street West Hartford, CT 061 07-2445 Attachment I W3FI -2006-0066 Response to Request for Additional Information (RAI)Regarding RF13 Steam Generator Tube Inspections Attachment 1 W3F1 -2006-0066 Page 1 of 7 Response to Request for Additional Information (RAI)Regarding RFI 3 Steam Generator Tube Inspections
REFERENCES:
1., Entergy letter dated May 24, 2005 "Combined 0-3 and 15-Day Special Report SR-05-001
-00 on the 1 3 t1h Refueling Outage Steam Generator Tube Inservice Inspection" (W3F1 -2005-0037)
- 2. Entergy letter dated May 17, 2006 "12-Month Special Report SR-06-001
-00 on the 1 3 th Refueling Steam Generator Tube Inservice Inspection" (W3F 1-2006-0024)
RAI 1 -On page 3 of the May 24, 2005, report and page 3 of the May 17, 2006, report, you indicated that possible loose parts indications were identified during the inspection.
Please discuss the scope and results of the foreign object search and retrieval on each steam generator (SG). If any loose parts were identified, discuss whether the loose parts were removed. If the parts were not removed or the locations were not visually inspected, please discuss the results of any evaluations performed to ensure these parts (or suspected parts) would not result in a loss of tube integrity for the period of time between inspections.
Entergy Response: ,During RF1 3 (April 2005), the as found condition of the SG thermal liner resulted in the initiation.of Condition Report CR-WF3-2005-01762.
A second Condition Report, CR-WF3-2005-01 861, was initiated based on concerns from eddy current examination that identified potential loose parts (PLPs). There were 41 PL-Ps identified in SG 31 and 17 PL-Ps in SG 32 when the CR was written.An evaluation of the loose parts was performed during RFl 3. The evaluation, contained in CR-WF3-2005-01 861, concluded that 12 tubes in SG 31 and 3 tubes in SG 32 should be plugged/stabilized as a preventive measure against potential wear. Waterford 3 implemented a contingency Foreign Object Search and Retrieval (FOSAR) inspection on SG 31 because of concerns of potential pieces from the degraded condition of the FW Thermal Liner, previously identified in CR-WF3-2005-01762.
The FOSAR inspection revealed a few minor sized objects (e.g. small diameter wire) which were of low concern due to their small cross section relative to flow. One object, a mechanical SG plug called a "Pop-a-Plug," was found in SG 31 Blowdown lane, which was not previously identified as a PLP by eddy current examination.
The Pop-a-Plug was removed. This condition was also entered into the site's Corrective Action Program as CR-WF3-2005-01958.
The potential pieces from the degraded condition of the FW Thermal Liner were not seen during the FOSAR inspection and therefore concluded not to exist.Based on the FOSAR results from SG 31, additional actions to perform a FOSAR on SG 32 were considered unnecessary.
This plant management decision was based on a future secondary side inspection scheduled for RF14 (Fall 2006) along with sludge lancing activities that were considered a normal activity associated with the inspection.
The decision not to inspect SG 32 was later determined to be a deviation to Section 3.8 of the NEI 97-06 Guideline Requirements.
Attachment 1 W3F1 -2006-0066 Page 2 of 7 Section 3.*8 specifies that a secondary side visual examination shall be performed each time the secondary side of the SG is opened for maintenance access. Condition Report CR-WF3-2006-0933 was entered into the plant's Corrective Action Program and a deviation was processed in accordance with the requirements of the EPRI SG Administrative Procedures and Entergy Procedures.
The following Tables 1 and 2 for SG 31 and 32, respectively, list the potential loose parts based on eddy current results.TABLE I WATERFORD 3 SG 31 RF13 POTENTIAL LOOSE PART
SUMMARY
PLP SG ROW COL VOLTS LOCATION POSITION WEAR FLOW FINAL COUNT (YESINO) (HIGHILOW)
DISPOSITION 1 31 1 27 0.85 TSH 0.22 No High Inservice 2 31 1 29 0.89 TSC 0.08 No High Inservice 3 31 2 28 0.61 TSH 0.23 No High Inservice 4 31 12 116 0.41 TSH 0.14 No Low Inservice 5 31 14 40 0.44 TSH 0.26 No Low Inservice 6 31 14 158 1.10 TSH 0.13 No Low Inservice 7 31 15 159 0.83 TSH 0.21 No Low Inservice 8 31 20 150 0.69 TSH 0.12 No Low Inservice 9 31 33 5 0.96 TSH 0.21 No High Inservice 10 31 38 112 1.87 TSC 0.63 No High Inservice 11 31 41 149 0.84 TSH 0.19 No Low Inservice 12 31 45 141 1.02 TSH 0.42 No Low Inservice 13 31 47 73 0.62 TSH 0.29 No Low Plugged 14 31 51 139 0.69 TSH 0.12 No Low Inservice 15 31 55 45 0.91 TSH 0.24 No Low Inservice 16 31 60 98 0.67 TSH 0.16 No Low Inservice 17 31 70 148 1.26 TSH 0.30 No Low Inservice 18 31 74 154 0.75 TSH 0.38 No Low Inservice 19 31 79 123 0.18 TSH 0.35 No Low Inservice 20 31 83 117 0.99 TSH 0.20 No Low Inservice 21 31 87 121 0.95 TSH 0.16 No Low Inservice 22 31 90 124 1.00 TSH 0.89 No Low Inservice 23 31 91 117 1.38 TSH 0.04 No Low Inservice 24 31 92 152 0.86 TSH 0.37 No Low Inservice 25 31 94 152 1.12 TSH 0.16 No Low Inservice 26 31 99 31 0.71 TSH 0.10 No High Inservice 27 31 100 30 0.39 TSH 0.11 No High Inservice 28 31 104 128 1.18 TSH 0.31 No Low Inservice 29 31 104 130 0.80 TSH 0.14 No Low Inservice 30 31 116 106 0.76 TSH 0.08 No Low Inservice 31 31 119 67 0.66 TSH 0.21 No Low Inservice 32 31 125 111 0.58 TSH 0.62 No Low Inservice Plugged/33 31 126 122 0.53 TSH 0.66 No High Stabilized Plugged/34 31 127 121 1.17 TSH 0.62 No High Stabilized Attachment 1 W3F1 -2006-0066 Page 3 of 7 Plugged/35 31 128 122 0.38 TSH 0.40 No High Stabilized Plugged/36 31 136 112 0.85 TSH 0.36 No High Stabilized Plugged/37 31 137 111 0.67 TSH 1.11 No High Stabilized Plugged!38 131 138 1110 0.89 1 TSH 0.30 No High Stabilized Plugged!39 31 138 112 1.12 TSH 0.12 No High Stabilized Plugged!40 31 138 112 1.10 TSH 0.64 No High Stabilized Plugged!41 31 139 111 0.83 TSH 0.90 No High Stabilized Plugged!42 31 139 113 1.01 TSH 0.12 No High Stabilized Plugged!43 31 139 113 0.95 TSH 0.58 No High Stabilized TABLE 2 WATERFORD 3 SG 32 RF13 POTENTIAL LOOSE PART
SUMMARY
PLP SG RW CLVLS LCTO OIIN WEAR FLOW FINAL COUNT SG RW CL VLS LCTO OIIN (YES!NO) (HIGHILOW)
DISPOSITION 1 32 3 115 0.76 fSH 0.36 No Low Inservice 2 32 7 59 1.46 TSH 0.43 No Low Inservice 3 32 19 121 0.24 TSH 0.24 No Low Inservice 4 32 30 36 0.86 TSH 0.17 No Low Inservice 5 32 32 36 0.73 TSH 0.12 No Low Inservice 6 32 71 149 1.63 TSH 0.11 No Low I nservice 7 32 73 115 0.62 TSH 0.30 No Low Inservice 8 32 82 94 0.61 TSH 0.68 No Low Inservice 9 32 88 86 1.21 TSH 0.34 No Low Inservice 10 32 91 89 1.30 TSH 0.52 No Low Inservice 11 32 107 111 0.74 TSH 0.28 No Low Inservice 12 32 109 79 1.13 TSH 0.22 No Low Inservice 13 32 111 93 0.73 TSH 0.29 No Low Inservice 14 32 112 114 0.68 TSH 0.26 No Low Inservice 15 32 113 71 0.67 TSH 0.16 No Low Inservice Plugged!16 32 127 131 1.16 TSH 10.05 No High Stabilized Plugged!17 32 128 130 1.13 TSH 10.94 Yes High Stabilized Plugged!18 32 142 74 0.89 TSH 0.33 No High Stabilized-Attachment 1 W31F11-2006-0066 Page 4 of 7 RAI 2 -On page 2 of the May 24, 2005, report, Table 2.1 states that you expanded the inspection of wear scars for SG 31, but not for SG 32. Then, on page 2 of the May 17, 2006, report, Table 3.1 states that you did not expand the inspection of wear scars for SG 31, but you did for SG 32. Please clarify this discrepancy.
Entergy Response: There is an error in reporting the expansion in the May 2005 report. The May 2006 report is correct, expansion was in SG32.RAI 3 -On page 2 of the May 17, 2006, report, you indicated in Table 3.1 that you identified 188 new wear scars in SG 31 and 214 new wear scars in SG 32. Please discuss the cause for the apparent increase in the number of new wear scars.Entergy Response: Waterford-3 has chemically cleaned Steam Generators in RF10 and RF12. One suspected cause of increased wear is the possibility of more tube bundle movement due to the removal of corrosion product from throughout the bundle and a thickness reduction of the structures.
Waterford-3 Steam Generators have carbon steel supports which were susceptible to metal removal during the chemical cleaning.During Cycle 13 there were no plant reactor trips and the turbine was only removed from service once. It is unlikely that any particular transient was the cause of the increased wear.RAI 4 -On page 3 of the May 24, 2005, letter, you indicated in Table 2.2 that four volumetric indications were detected in the cold leg of SG 31 and one volumetric indication was detected in the hot leg of SG 32. Please discuss the nature, cause, and severity of these indications.
Entergy Response Table 2.2 lists all pluggable indications.
Some tubes contain more than one indication.
The four volumetric indications on SG 31 cold leg are adjacent to each other: R1 C171, R3 01 71, R2 01 72 and R2 01 72. The previous inspection results (RF1 2) at each of these locations were all NDD. The location is adjacent to the blowdown lane and near the periphery of the tube bundle. The flaw could have been caused by a loose part which was no longer present when visually examined.The one hot leg (HL) volumetric indication on SG 32 is associated with a loose part. R128 0130 was stabilized and plugged. This volumetric indication was specifically evaluated and documented in the station's Corrective Action Program, condition report CR-WF3-2005-01 861.
Attachment 1 W3F1 -2006-0066 Page 5 of 7 The condition report evaluated the HL indication associated with a loose part as follows: Only one PLP identified in RF13 has caused wear The loose part was identified on ECT inspection of tube 128-130. The PLP indication was located approximately 10 inches above the hot leg top of tubesheet in SG32.The potential loose part associated with PLP indication called on 128-130 is acceptable to remain in senvice because: 1. The loose part is lodged between two tubes and has been so lodged for at least 1 cycle. History review of the tube indicates the tube had a possible loose part during the RF12 inspection.
Wear caused by the part during the last cycle was classified as very small. Thus, it is fully expected that the potential loose part is lodged in a very stable manner within the two tubes. The wear is not expected to increase significantly over the course of another cycle nor will it move during the next cycle.2. In the unlikely event the loose part should move, the potential for the loose part to cause a leak in a tube is small because the moved loose part will have to start the wear process over and the chances developing into a deep enough wear scar to cause a leak in a relocated spot in less than a cycle is small.3. Tube 12 8-130 was preventatively plugged and stabilized.
RAI 5 -On page 4 and page 7 of the May 24, 2005, report, you indicated in Tables 3.1.1 and 3.3.1 that there has been a reduction in the number of detected indications of circumferential and axial cracking at the top of the tube sheet when compared to past outages. Please discuss any insights you have concerning the 'trend." In addition, please discuss the reduction in the number of free-span indications.
Include in your response a discussion on the noise levels associated with the SG eddy current data.Entergy Response Waterford 3 has completed 100% HL Top of Tubesheet (TTS) examinations since RF06 (1994).The inspection depth has changed: RF8 +2/-2; RF9 +2/-2; RF10 +2/ -5; RF1 1 +2 1 -5; RF12 +3 1-8; and RF1 3 +3 / -11. The chemical cleaning in RF1 0 (2000) created interfering signals from copper which remains a concern and was the driving issue for conducting a second chemical cleaning in RF12 (2003).The varying inspection depth should cause additional tube flaw identification.
The assumption being that there is a population of tubes which have not been examined with the rotating pancake probe (RPC).Insights RF1 2 and RF1 3 were much improved over RF1O0 and RF1 1 with respect to interfering signals from copper. SG 31 is the leading SG for flaw discovery; this is a normal phenomenon for PWRs though there is no specific explanation of why SG 31 would lead.
Attachment 1 W3F1 -2006-0066 Page 6 of 7 The RF10 number of axial indications (22 in each SG) was probably influenced by the interfering copper signals which may have been overcome by conservative eddy current calls.Bobbin Freespan Indications Extensive history reviews in the freespan was performed during the inspection by the resolution analysts.
All freespan indications reported by Bobbin were reviewed by both a Primary and a Secondary resolution analyst at least back to 1994 RFO6. If the indication had not changed from history, it was reported as DFH (Differential Freespan History Review) or as ADH (Absolute Freespan History Review). Those indications which either were new or showed a change from RF06 1994 historical data were reported as a DFI (Differential Freespan Indication) and +Pt RPC tested. A total of 22 indications in SG 31 and 12 in SG 32 were reported as a DFI in freespan and none showed degradation when tested with +Pt RPC. The DFI calls were left in the database for future tracking.
The result of the freespan bobbin indication historical review is as follows: I SG 31 I SG 32 DFH (Freespan Differential History Reviewed) 911 796 ADH (Freespan Absolute Histor Reviewed) 1 3 Eddy Current NoiseýDuring the inspection eddy current data quality was continuously monitored throughout the data acquisition and analysis processes.
All of the data quality requirements in EPRI PWR SG Examination Guidelines, Rev. 6 required to be implemented was addressed either by the data quality monitoring software, acquisition operators, data quality analyst or data analysts.
Prior to the start of the outage a comparison of RF12 data with the EPRI qualified techniques was performed as part of the site validation process. This comparison showed that the data from RF12 was as good as or better than the data used in the EPRI qualification data sets. During the inspection, any tube that did not meet the data quality standards was given the "Retest Bad Data" (RBD) analysis code signifying that the tube was required to be retested.In preparation for the Waterford-3 RF14 inspection, a comparison was performed between the RF13 data and the EPRI qualified techniques.
This comparison, again, showed that the data collected in RF1 3 was as good as or better than the data used in the EPRI qualification data sets. The most challenging degradation mechanism in the Waterford-3 steam generators is ODSCC located in eggcrate supports using the bobbin probe for detection.
For this region of the Waterford-3 steam generators, the average noise was measured as 0.90 Vpp in SG 31 and 0.95 Vpp in SG 32. The maximum noise measurement was 1.93 Vpp in SG 31 and 2.11 Vpp in SG 32. This compares to an average noise measurement of 1.33 Vpp and a maximum noise measurement of 3.33 Vpp for EPRI qualification 96008.1 for detection of ODSCC at non-dented eggcrate supports.
For rotating probe techniques, using the +Point coil, noise measurements were compared in the Low Row U-Bends and at the hot leg expansion transitions.
The results of this comparison are summarized in the table below:
Attachment 1 W3F1 -2006-0066 Page 7 of 7 Noise Measurement Data From: Probe Vpp Ave Vpp Max EPRI Qualification 96511.2 Low Row U-Bend Apex +Point I 1.09 1.62 Tangent +Point 1.49 2.90 RF 13 Low Row U-Bend (Data Combined for SG 31 and SG 32)Apex +Point 1.04 1.52 Tangent +Point 0.94 1.24 EPRI Qualification 20510.1 Expansion Transition
+ P o in~t 0.59 1.20 EPRI Qualification 20511.1 Expansion Transition
+Point 0.35 0.62 RF13 Expansion Transition SG 31 +Point I 0.35 I 0.52 SG 32 +Point 0.43 0.75 The above information helps to illustrate that overall data quality in the Waterford-3 steam generators for both the bobbin and +Point probes is good. In addition, measures have been implemented to ensure that bad or noisy data is not accepted.