ML13189A222
| ML13189A222 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 04/12/2013 |
| From: | Division of Operating Reactor Licensing |
| To: | |
| Wengert T J | |
| Shared Package | |
| ML13189A226 | List: |
| References | |
| TAC MF0875 | |
| Download: ML13189A222 (4) | |
Text
Preliminary Information from Ongoing U1C25 Activities 4/12/13 NRC Questions Page 1 of 4 Status: (4/11/13 @ 1700 hrs)
Bobbin Exam % HL TTS% CL TTS% Overall % SG 11 84.8 0 0 58.4 SG 12 83.9 92.5 0 71.3 SG 13 77.3 98.8 0 67.5 SG 14 75.7 91.1 0 65.8
- 1. Discuss any trends in the amount of primary-to-secondary leakage observed during the recently completed cycle.
R1: No primary-to-secondary leakage has been detected since the steam generators were replaced in 2000. This includes the recently completed cycle of operation.
- 2. Discuss whether any secondary side pressure tests were performed during the outage and the associated results.
R2: No steam generator secondary side pressure tests were planned or performed during the outage.
- 3. Discuss any exceptions taken to the industry guidelines. R3: No exceptions have been taken to the EPRI Steam Generator Guidelines (inclusive of the examination, integrity, insitu, leak or water chemistry guidelines) or the NEI 97-06 Steam Generator Program Guidelines.
- 4. For each SG, provide a description of the inspections performed including the areas examined and the probes used (e.g., dents/dings, sleeves, expansion-transition, U-bends with a rotating probe), the scope of the inspection (e.g., 100 percent of dents/dings greater than 5 volts and a 20 percent sample between 2 and 5 volts), and the expansion criteria.
R4: Exam Full Length HL/CL TTS Special Interest - Lattice Grids & Fan Bars SI - Foreign Objects SI - New Bobbin SI - Dents & Dings SI - Proximity &
Freespan Wear Probe Bobbin X-probe +Point +Point +Point +Point +Point All SGs 100% ~21% All wear > 20% All PLPs/ FO Wear, Affected historical FO locations, New FO I'd by FOSAR All I-codes & new bobbin signals Historical bobbin > 2 volts All indications of proximity & freespan wear Expansion Criteria N/A Min. 1 tube bound N/A Min. 1 tube bound EPRI C-1, C-2, C-3 criteria EPRI C-1, C-2, C-3 criteria EPRI C-1, C-2, C-3 criteria Preliminary Information from Ongoing U1C25 Activities 4/12/13 NRC Questions Page 2 of 4
- 5. For each area examined (e.g., tube supports, dent/dings, sleeves, etc), provide a summary of the number of indications identified to-date for each degradation mode (e.g., number of circumferential primary water stress corrosion cracking indications at the expansion transition). For the most significant indications in each area, provide an estimate of the severity of the indication (e.g., provide the voltage, depth, and length of the indication). In particular, address whether tube integrity (structural and accident induced leakage integrity) was maintained during the previous operating cycle. In addition, discuss whether any location exhibited a degradation mode that had not previously been observed at this location at this unit (e.g., observed circumferential primary water stress corrosion cracking at the expansion transition for the first time at this unit).
R5: SG Fan Bar Wear Lattice Grid Wear Foreign ObjectWear SG 11 658 6 0 SG 12 480 9 0 SG 13 426 2 0 SG 14 789 9 0 Totals 2353 26 0 Fan Bar Significant Indications
- SG 11 - R78/C62 - 32% fan bar 4 Lattice Grid Significant Indications
- SG 11 - R34/C46 - 18% fan bar Foreign Object Wear Significant indications
- None Based upon our ongoing condition monitoring assessment tube integrity (both structural and accident induced leakage integrity) was maintained during the previous operating cycle.
No new degradation mechanisms have been identified during the course of the inspection and no locations along the tube exhibited a degradation mode that had not previously been observed at this location at this unit.
- 6. Describe repair/plugging plans.
R6: Tube repairs will be limited to mechanical plugging and stabilization (if required). Based upon results to date, 0 tubes are projected to require plugging. This is based on a projected operating duration of one cycle and a 36 TW% repair criteria.
- 7. Describe in-situ pressure test and tube pull plans and results (as applicable and if available).
R7: Insitu screenings are in progress as the remaining data is being reviewed by our tube integrity engineer; however no insitu testing is expected. No conditions have been detected which would suggest a tube pull will be required during this inspection.
Preliminary Information from Ongoing U1C25 Activities 4/12/13 NRC Questions Page 3 of 4
- 8. Discuss the following regarding loose parts:
- what inspections are performed to detect loose parts
- a description of any loose parts detected and their location within the SG (including the source or nature of the loose part, if known)
- if the loose parts were removed from the SG
- indications of tube damage associated with the loose parts
R8: Loose part inspections include:
- Visual inspections at the top of the hot and cold leg tubesheets o Divider lane o Bundle periphery o Historical loose part locations
- X-probe examination is being performed on the hot and cold leg peripheral tubes from the tube end to the first support. Tube selection is based on a 3 tube pattern (diagonally or along the Y-axis) as depicted below.
- Bobbin coil examination of the tube bundle is being performed using a turbo mix has been noted as enhancing bobbin probe detection of foreign object wear at the top of tubesheet
The following table summarizes the loose parts detected, tube damage and retrieval status:
SG Description Location RetrievedSource Tube Damage (%TW) SG 12 3" x 0.25" Wire Screen (rectangular) 0.5" x0.5" Wire Screen (tri-shaped) 0.25" x 0.25" Wire Mesh (square) R81/C49 HL R59/C33 HL R64/C26 HL Yes Yes Yes Oct. 2012 MFP Strainer Failure No deg, +pt pending No deg, +pt pending No deg, +pt pending SG 13 Object from SSI (retrieval pending) R54/C16 HL No Unknown No deg, +pt pending SG 14 2.5"x 0.5"Banding wire 1"x 0.5" Banding wire 1.25"x0.25" Wire Screen (crumpled) ECT PLP - Nothing found R1/C65 CL R71/C69 HL R44/C10 CL R5/C91 HL Yes Yes Yes NA Unknown Unknown Strainer Failure NA No deg, +pt pending No deg, +pt pending No deg, +pt pending No deg, +pt pending
Preliminary Information from Ongoing U1C25 Activities 4/12/13 NRC Questions Page 4 of 4 9. Discuss the scope and results of any secondary side inspection and maintenance activities (e.g., in-bundle visual inspections, feedring inspections, sludge lancing, assessing deposit loading, etc).
R9: Secondary side activities include top of the tube sheet visual inspections as discussed previously. No abnormal conditions were noted during these inspections; with the exception of the foreign objects summarized above.
No steam drum or water lancing activities are scheduled this outage. Deposit mapping will be performed using eddy current data post outage to trend bundle loading.
- 10. Discuss any unexpected or unusual results.
R10: None
- 11. Provide the schedule for steam generator-related activities during the remainder of the current outage.
R11: Eddy current inspection complete: 4/14/13 Nozzle dam removal: 4/20/13 Reinstall primary manways: 4/21/13