ML051260274
| ML051260274 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/11/2004 |
| From: | Sharon Bennett Entergy Operations |
| To: | Alexion T NRC/NRR/DLPM/LPD4 |
| Alexion T W, NRR/DLPM, 415-1326 | |
| Shared Package | |
| ML051600374 | List: |
| References | |
| Download: ML051260274 (8) | |
Text
l Thomas Alexion - 1R 18 Steam Generator Discussion of May 3, 2004 Page 1 From: "BENNETT, STEVE A' <SBENNE2@entergy.com>
To: "'Tom Alexion'" <twa nrc.gov>
Date: 5/11/04 11:31AM
Subject:
1R1 8 Steam Generator Discussion of May 3, 2004 liom, Attached is the discussion points from last Monday that we promised. There were a few minor changes that were updated from our call. However, there were no changes that affected how we were preceding to repair the OTSGs or the acceptability of our Operability Assessment.
Steve Bennett NSA - Licensing 479-858-4626 Pager: 479-890-3323 CC: "GREESON, WILLIAM C" <WGREESO~entergy.com>, "JAMES, DALE Ed
<DJAMES~entergy.com>, "JONES, ROCKY Lo <RJONES4@entergy.com>, "VAN BUSKIRK, FRED P"
<FVANBUS @entergy.com>
-d~tQa S6-\5
I-C-A-W'ft4D-0WS\TEMP\'G W)00001.TMP -Pa'ge Page 1 iI C:\WllJDOWS\TEMP\GWlOOOO1 .TMP Mail Envelope Properties (4OAOF19B.FCB:12:57291)
Subject:
1R18 Steam Generator Discussion of May 3, 2004 Creation Date: 5/11/04 11:21AM From: "BENNETT', STEVE A" <SBENNE2@entergy.com>
Created By: SBENNE2@entergy.com Recipients nrc.gov owf4_po.OWFN_DO TWA (Thomas Alexion) entergy.com FVANBUS CC (VAN BUSKIRK, FRED P)
RJONES4 CC (JONES, ROCKY L)
DJAMES CC (JAMES, DALE E)
WGREESO CC (GREESON, WILLIAM C)
Post Office Route owf4..po.OWVFNDO nrc.gov entergy.com Files Size Date & Time MESSAGE 350 05/11/04 11:21AM Part.001 1246 NRC Conference Call During 1R18.doc 94720 Mirne.822 133193 Options Expiration Date: None Priority: Standard Reply Requested: No Return Notification: None Concealed
Subject:
No Security: Standard
NRC Conference Call Durinq 1R18 Arkansas Nuclear One (Unit One)
Large Break LOCA Best Estimate Leakage:
LBLOCA leakage for 1R1 8 is predicted to be 2.57 gpm for the first two minutes and 1.49 gpm average leak rate for 30 days. Current ANO leakage limit is 9 gpm for the first two minutes and 3 gpm average leak rate. During 1R1 8 there werel 1 circumferential indications found inboard of the repair roll in the "A" OTSG and 6 in the "B" OTSG.
Additionally, there were 52 circumferential indications found in the "A OTSG located in the original roll or heat affected zone and 9 in the "B" OTSG.
- 1. Discuss whether any primary to secondary leakage existed in this unit prior to shutdown.
Minimal leakage was detected consistently throughout the cycle. Tritium averaged -1.6 gpd during Cycle 18.
- 2. Discuss the results of secondary side hydrostatic tests.
There were no secondary side hydrostatic tests performed during 1R1 8.
- 3. For each steam generator, provide a general description of areas examined, including the expansion criteria utilized and type of probe used in each area.
SG 'A' Area # Tested Probe Expansion Mechanism/Criteria FL Bobbin 14536 bobbin No Impingement, Wear, Axial IGA/ODSCC, Vol IGA Upper Roll 14109 plus point No Circ/Axial ODSCC Transition Circ/Axial PWSCC LTS Sludge 659 plus point No Circ/Axial ODSCC
& Dents Super Heat 128 plus point No (1) Circ/Axial PWSCC Dents 1600 101 plus point No OD IGA/SCC Sleeves Lower Roll 5014 Plus Yes (2) ID/OD IGA/SCC Transitions point Lower Tube 5014 Plus Yes (2) Circ/Axial PWSCC End point (1) expand based on EPRI GL; no cracks found (2) exception to EPRI GL; expand if more indications than predicted
SG 'B' Area # Tested Probe Expansion Mechanism/Criteria FL Bobbin 15133 bobbin No Impingement, Wear, Axial IGA/ODSCC, Vol IGA Upper Roll 14654 plus point No Circ/Axial ODSCC Transition Circ/Axial PWSCC LTS Sludge 436 plus point No Circ/Axial ODSCC
& Dents Super Heat 65 plus point Yes (1) Circ/Axial PWSCC Dents 1600 69 plus point No OD IGA/SCC Sleeves Lower Roll 5257 Plus Yes (2) ID/OD IGA/SCC Transitions point Lower Tube 5257 Plus Yes (2) Circ/Axial PWSCC End point (1) expand based on EPRI GL; 1 crack found; critical area established (2) exception to EPRI GL; expand if more indications than predicted
- 4. Discuss any exceptions taken to the industry guidelines.
Three exceptions were taken to two requirements in Revision 6 of the EPRI PWR SG Examination Guidelines. One exception was to use the bobbin probe for lower tubesheet examinations based on a site qualification when the technique is not Appendix H qualified as required in section 6.2. A 21 % sample of the tubes in the kidney region were examined with plus point probes. No indications were found at the LTS dent/sludgepile region.
The other two exceptions are taken are on the inspection expansion requirements in section 3.6 and Table 3-2 for indications found in the lower tube ends and lower roll transitions.
Lower Tube Ends: An initial inspection scope of 34% of the tube ends in each steam generator identified 1 and 4 tube end circumferential cracks in A and B SG respectively.
A scope expansion to 100% was not performed because the cracks in this location can't burst and the original lower tube rolls limit the potential leakage from any crack indications. There was additional leakage calculated for the uninspected population.
Lower Roll Transitions: The lower roll transitions were examined as part of the lower tube end inspection. During the initial 34% sample two small volumetric indications (<
0.5 inches in either direction, <1 volt) classified as inside diameter IGA were found in 'A' SG. Similar to the LTE exception these indications could not burst and leakage tests done on earlier IGA patches in the upper tubesheet demonstrated very little leakage.
The sample inspection was a 34% total of the LRT population.
- 5. Provide a summary of the number of indications identified to date of each degradation mode and SG tube location (e.g. tube support plate, top-of-tubesheet, etc). Also provide information such as voltages, and estimated depths and lengths of the most significant indications.
- ANO1 1R18 Eddy Current Inspection Results
-- Degradation/Area "A" OTSG - ---
"B"-OTSG for Worse
- --CM
-: - Indications Indications- '.Case TSG:
UpperTube End Flaws 1775 1038 2380 Upper Tube End Flaws 48 6 N/A*
(Repairable)
Upper Roll Transition PWSCC 81 91 70 Re-Roll Indications 16 17 42 Upper Tubesheet Crevice 63 1 0 Upper Tubesheet IGA 2 3 0 Sleeves 0 0 49 Indications in Dents 0 8 15 (superheated region and LTS)
TSP Wear 0 0 0 TSP Flaws/Freespan 294 167 86 Lower Tubesheet 0 0 20 Lower Roll Transition PWSCC 0 0 0 Lower Roll Transition IGA 2 0 0 Lower Tube End Flaws 1 4 280*
- Repairable indications in the tube ends are accounted for in the upper tube end flaw totals. The repairable indications account for leakage the same as non-repairable indications located within the tube end.
One indication in a dent in the "B" OTSG passed in-situ screening criteria. This flaw was 64% average depth. 1.0v MRPC voltage. Many of the confirmed freespan flaws found during 1R18 were low voltage. None of the freespan flaws required in-situ pressure testing.
- 6. Describe repair/plugging plans for the SG tubes that meet the repair/plugging criteria.
Repairs have/will be made using 1690 mechanical rolled plugs and re-rolls made in the UTS.
A SG B SG Plugs 234 78 Rerolls 233 110
- 7. Discuss the previous history of SG tube inspection results, including any "look backs" performed, specificallyfor significantindicationor indications where look backs are used in support of dispositioning(e.g., manufacturing burnish marks).
Look backs are performed to disposition MBM indications based on history. For the indication to be classified as a MBM it must have received a rotating probe examination during a previous inspection. If there was a change in the bobbin examination signal the indication was scheduled for a rotating probe examination this outage. All wear indications that have been left in service from previous inspections have received a rotating probe examination. History review is performed on wear indications and if there is a change in the bobbin signature the indications is scheduled for a rotating probe examination this outage.
- 8. Discuss, in general, the new inspection findings (e.g., degradation mode or location of degradation new to this unit).
Two modes of degradation previously found at ANO-1 were found in new locations during this inspection. Two small patches of IDIGA were found in the lower transition rolls and five circ cracks were found in lower tube ends.
- 9. Discuss your use or reliance on inspection probes (eddy current or ultrasonic) other than bobbin and typical rotating probes, if applicable.
No inspection probes other than bobbin and typical rotating probes were used in 1R1 8.
- 10. Describe in-situ pressure test plans and results, if applicable and available, including tube selection criteria.
In-situ selection is performed in accordance with the EPRI guidelines. Screening is performed and all those flaws that pass the final screening criteria are tested. No bounding is performed. One in-situ test was performed on an axial crack in a freespan dent at the 15 TSP (tube 88-40 B SG) 1.0 v 0.25 in.64.3% PDA. The indication did not leak at 3 DP (4500 psi). The dent itself was 2.9 volts.
- 11. Describe tube pull plans and preliminary results, if applicable and available; include tube selection criteria.
There were no tube pulls during 1R18.
- 12. Discuss the assessment of tube integrity for the previous operating cycle (i.e., conditionmonitoring).
The techniques used were qualified or demonstrated equivalent with the EPRI PWR Steam Generator Examination Guidelines. Several modes of degradation were detected during the exams. Most forms were expected, with the exception small patches of IGA in two lower roll transition. By benchmarking actual inspection results to the projected values, reasonable projections can be made for EOC 19. The structural aspects of the various modes of degradation are either bound by 1R1 8 in-situ testing or considered not a concern based on location within the tubesheet (e.g., URT, re-roll flaws). Additionally, the HAZ flaws and the upper tubesheet IGA are being addressed through specific Technical Specification requirements. The conclusion of this condition monitoring evaluation is that none of the performance criteria in NEI-97-06 were exceeded and based on the comprehensive exams performed it is concluded that the EOC 18 condition would not exceed the performance criteria.
- 13. Discuss the assessment of tube integrity for next operating cycle (i.e.,
operational assessment).
The operational assessment will be performed in accordance with the NEI 97-06.
Potential for burst and leakage will be assessed before entering Mode 4 for a 90 day period to allow the development of the full cycle report.
OA ..81 gpm in bounding OTSG
- 14. Provide the schedule for steam generator-related activities during the remainder of the current outage.
Eddy current testing complete Insitu testing 05/01/04 (Sat.)
Repair 05/03/04 (Monday)
Close Generator 05/05/04 (Wednesday)
- 15. With regard to loose parts, discussthe following:
- what inspectionsare performed to detect loose parts,
- a description of any loose parts detected and their location within the SG,
- if the loose parts were removed from the SG,
- indications of tube damage associated with the loose parts, and
- the source or nature of the loose parts, if known.
Eddy current inspections were used to detect the presence of loose parts touching steam generator tubes. No possible loose part (PLP) indications were identified during those examinations. No secondary side examinations were performed.
- 16. Once-Through Steam Generators: If you have Babcock and Wilcox (B&W) welded plugs installedin the SGs, be preparedto discuss the actions taken in response to Framatome'snotificationof the effect of tubesheet hole dilation on the service life of B& W welded plugs.
CR-ANO-1 -2002-00280 During a recent review of calculations associated with OTSG Remote Welded Plugs (RWP) and Manually Welded, Taper Welded Plugs (MWP), Framatome discovered that the plugs are not qualified in accordance with the requirements stated in the equipment specification requirements and associated purchase order. Specifically, the stress reports define the design transient heatup/cooldown cycles were originally evaluated for 240 cycles. The stress reports submitted to Davis Besse for their most recent outage define the heatup/cooldown cycles be limited to less than 33 to maintain a fatigue life of less than one. The latest stress reports were developed with tubesheet dilation included.
RWP's were not installed in the ANO-1 OTSG's prior to 1993 so those plugs have seen less than 15 heatup/cooldown cycles.
The results of the current Framatome re-analysis shows that the MWP is acceptable for 144 heatup/cooldown cycles. None of the MWP's installed at ANO-1 have experienced heatup/cooldown cycles anywhere near 144. The most conservative number published by Framatome is 67 heatup/cooldown cycles for ANO-1 MWP's. ANO personnel have calculated 45 heatup.cooldown cycles (the discrepancy is based on a BWOG report that counted any plant power change other than normal power swings as a cooldown).
Even with the most conservative heatup/cooldown cycles (67) ANO-1 is well within the acceptable limit of 144 heatup/cooldown.
- 17. Once-Through Steam Generators: Describe your inspection/plugging plans with respect to the industry-identifiedsevered tube issue (NRC Information Notice (IN) 2002-02 and IN 2002-02, Supplement 1).
Inspections during 1R17 in October 2002 addressed the issues associated with the potential for severed tubes. 31 tubes were plugged and stabilized in the "A" OTSG and 30 tubes were plugged and stabilized in "B" OTSG. All tubes identified for plugging in 1R1 8 are screened for stabilization and the database cannot be closed with any wear indications found at the secondary face of either tubesheet.