ML021050440
| ML021050440 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 02/12/2002 |
| From: | NRC/NRR/DLPM |
| To: | Nuclear Management Co |
| References | |
| TAC MB4012 | |
| Download: ML021050440 (6) | |
Text
Prairie Island Unit 2 EOC 20 S/G Inspection Results Category C-3 Inspection Results Draft Report to NRC - February 12, 2002
" Steam Generators: Two Westinghouse Model 51 with open tubesheet crevices, Alloy 600 Tubing, Rows 1 and 2 U-bends were heat treated in May 2000.
"* There are 1180 reroll repairs in service in Unit 2.
"* Cycle 20 length - 603 days, 567 EFPD
"* NRC Item 1: Primary to secondary leakage during operating cycle was less than 0.5 GPD based on tritium in the SG blowdown. There was no detectable gross activity in liquid SG blowdown samples and no detectable activity at the condenser air ejector discharge during the cycle.
"* NRC Item 2: Secondary side hydrostatic tests for leakage have not been done since there was no detectable primary to secondary side leakage during the previous operating cycle.
"* NRC Item 3: The inspection UNIT #2 STEAM GENERATOR INSPECTION PLAN completed is shown in detail on page 3. 100% of the hot leg tubesheet region and rows 1 and 2 u-bends were inspected with rotating coil technology. 100% of the tubing (less rows 1 and 2 u-bends) were inspected with the bobbin coil. No expansions were required.
" NRC Item 13: New Degradation Mechanisms: No new degradation mechanisms were found during this inspection. If such an indication is found, the Prairie Island steam generator program implementing procedures require initiation of a Condition Report that insures the new degradation mechanism evaluation will receive a high level of review and investigation.
" NRC Item 8: Four indications were tested in 21 SG and no leakage occurred.
Four indications were be tested today in 22 SG. Details of the indications are shown on page 4.
" A post maintenance leak check at >100 psig secondary side pressure will be conducted at the end of the rerolling and welded tubesheet plug repairs.
Feb 12 02 with corrections.doc Page 1 of 6 Enclosure 1
4'- NRC Item 5:
> Repair Criteria
- 40 % TWD (3 50% Old AVB and wear scar locations) for EPRI Appendix H qualified sizing techniques (cold leg tube support plate thinning and wear)
- Any Axial, Circumferential, Volumetric (not related to a sizeable degradation or MBM) or Mixed Mode RPC indication
- F-Star Criteria for Lower Region of Tubesheet with Rerolling and Tube End Indications
- EF-Star Criteria for Upper Region of Tubesheet with Rerolling
- Inadequate data quality in a critical area such as the u-bend
- Voltage Based Repair Criteria is available, but not implemented, yet.
Repairs SProjected
- Tubes are being repaired by rerolling (F* and EF* criteria) or plugged.
- There are no sleeves in Unit 2.
- Voltage Repair Criteria has not been implemented on Unit 2 Indication or Repair 21 SG 22 SG ARI" 288 164 AR2 17 5 ARE 4 1 F*0 130 108 F*1 696 390 F*2 30 31 plug 12 20 in situ 4 4
NRC Item 3 UNIT #2 STEAM GENERATOR INSPECTION PLAN Rev. 1 - 10/19/2001 VISUAL Hot Leg 100% all Plugs for visual signs of leakage - After probed to remove H20 Cold Leg 100% all plugs for visual signs of leakage - After probed to remove H20 BOBBIN Hot Leg 100% rows 1 through 4 07H TEH A-720-M/ULC/RF Cold Leg 100% rows 1 and 2 07C TEC A-700-SF/RM 100% rows 3 through 4 07H TEC A-700-SF/RM 100% rows 5 through 46 TEH TEC A-720-M/ULC/RF 100% PID's 0 Various Various MRPC Hot Leg 100% Tube sheets +3" TSH TEH +Point-720-115/PP11 A/S80 25% ABB 1-690 plugs UPH LPH .600 PP1 1A MB 100% Supplemental 0 Various +Point-720-115/PP11SA/80 100% PID's 0 Various Various Cold Leg 100% rows 1 and 2 (or HL) 07H 07C .650 PP11A(MR) +Point Noisy rows 1 and 2 (or HL) 07H 07C .650 PP9A(HF) +Point 100% Supplemental 0 Various +Point-720-115/36/S80 100% PID's 0 Various Various REPAIRS Hot Leg 100% Re-Rolls Various Combo Probe Hot Leg 100% Post In-Situ Various Various Cold Leg 100% Post In-Situ Various Various o PID = _ 40%, MAI, MCI, MVI, SAI, SCI, SVI, WCI and WVI.
O Supplemental MRPC = ADR, CUD, DEP, DNT Ž 5.0 volts at +/- 0.5" from a TSP or TS (verify minimum 20% sample of entire DNT population), DRI, DSI, DTI, INR > 1.5 volts
@ TSP, MBM, MRI, NQI, PLP (Bound MRPC PLP's), PSI, Cold Leg Thinning Ž_ 40% or
< 40% and > 1.5 volts.
Examination of U-Bends -Mid Range Frequency and, as required, High Range Frequency +Point Coils, all Rows 1 and 2 U-bends, 20% Sample expansion to Row 3 if indications found in Row 2. (No expansion required)
NRC Item 13 b) and c) Noise criteria applied for plugging Feb 12 02 with corrections.doc Page 3 of 6
Prairie Island Unit 2 In Situ Testing: February 2002 Insitu test list Test selection test SG leg row tube Pressure criteria results 21 hot 3 17 2816 PWSCC sat 21 hot 9 18 2816 PWSCC sat 21 hot 14 28 2816 ODSCC sat 21 hot 23 31 2816 ODSCC sat 22 hot 13 29 5256 2-81-60DSC,"-MSCC pend 22 hot 2 31 2816 PWSCC pend 22 hot 14 41 2816 ODSCC pend 22 hot 19 47 2816 5256 ODSCC pend Feb 12 02 with corrections.doc Page 4 of 6
NRC Item 4: Projected numbers of indications by location:
Disposition is F* and EF* criteria using rerolling or by plugging 21 SG Indications by Location HL Tube End Axial Indications 62 HL Roll Transition Zone PWSSS Indications, PWSCC 291 Existing HL Additional Rerolls, PWSCC 30 HL Tubesheet Crevice region, Sec. Side IGA/SCC 1 HL Top of Tubesheet, Sec. Side IGA/SCC (axial and volumetric) 1 TSP DSI's 27 TSP Max DSI Voltage 1.46 TSP Indications RPC Confirmed 0 Free Span Unknown 0 Anti-vibration Bar Locations Wear 0 Row 1 U-Bends PWSCC 0 Row 2 U-Bends PWSCC 0 Peripheral Cold Leg Tube Support Plates Wastage 0 Possible Loose Parts 6 TSP Ligament Possible Indications 0 Inadequate Data Quality 1 22 SG Indications by Location HL Tube End Axial Indications 44 HL Roll Transition Zone PWSSS Indications, PWSCC 165 Existing HL Additional Rerolls, PWSCC 11 HL Tubesheet Crevice region, Sec. Side IGA/SCC 5 HL Top of Tubesheet, Sec. Side IGA/SCC (axial and volumetric) 1 TSP DSI's 52 TSP Max DSI Voltage 1.3 TSP Indications RPC Confirmed 0 Free Span Unknown 0 Anti-vibration Bar Locations Wear 0 Row 1 U-Bends PWSCC 0 Row 2 U-Bends PWSCC 0 Peripheral Cold Leg Tube Support Plates Wastage 0 Possible Loose Parts 15 TSP Ligament Possible Indications 2 Feb 12 02 with corrections.doc Page 5 of 6
Response to NRC IN 2002-02 (TMI Severed Plugged Tube)
- Planned Inspection Routine: Neighbors to explosively plugged tubes evaluated by Independent QDA for detection of shallow long wear scars. Implemented by procedure and condition monitoring Visual examination at top of tubesheet during FOSAR after sludge lancing. Most of the plugged tubes are on the outer periphery.
Secondary Side Inspection Plan
- Visual Inspections for Internals Integrity previously done per GL 96-06
- Standard Inspections in one steam generator each outage
- Visual inspection of feed ring holes and plugs
- MT inspection of inner radius of feedwater nozzle elbow
- Visual inspection of inner radius of upper shell transition weld
- Visual inspection of feedwater ring hangers
- Visual inspection for cleanliness of drain pots from Chevron separators
- UT inspection for wall thinning of feedwater ring tee
- Analysis of ET data for support plate damage
- Computerized Data Screening to look at all tubes for significant ligament cracks
- Examine all possible support plate ligament indications from the bobbin results with RPC.
- Foreign Object Search and Retrieval at Tubesheet
- Possible loose parts identified by eddy current were investigated by remote visual inspection. Small parts removed.
- No indication of wear at locations of possible loose parts
- No eddy current indications of unexpected wear anywhere in the tube bundle Feb 12 02 with corrections.doc Page 6 of 6