ML093220983
| ML093220983 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 11/10/2009 |
| From: | Siva Lingam Division of Operating Reactor Licensing |
| To: | Andrea Johnson, Karwoski K NRC/NRR/DCI/CPTB |
| Lingam, S NRR/DORL 415-1564 | |
| References | |
| TAC ME2354 | |
| Download: ML093220983 (7) | |
Text
From:
Lingam, Siva Sent:
Tuesday, November 10, 2009 3:24 PM To:
Johnson, Andrew; Karwoski, Kenneth Cc:
Boyce, Tom (NRR); Guthrie, Eugene; Young, Cale; Speck, Mark
Subject:
FW: SG phone call Attachments:
S2C16 SG tube inspection discussion points.doc From: Proffitt, James W Jr [1]
Sent: Tuesday, November 10, 2009 3:19 PM To: Lingam, Siva; Michel, Eric Cc: Mashburn, Fredrick C Jr
Subject:
SG phone call Attached is the information we will be providing during the SG phone call.
The following personnel will be in attendance:
Emmett Camp Clayton Webber Dan Folsom William Pierce Fred Mashburn Kevin Jones Rod Krich Tim Cleary Rusty Proffitt If you have any questions, please contact me.
Rusty Proffitt Sequoyah Nuclear Plant Nuclear Engineer - Licensing (423) 843-6651 Fax (423) 843-8750 Attachment STEAM GENERATOR TUBE INSPECTION DISCUSSION POINTS The following discussion points have been prepared to facilitate the conference call that will be arranged with the licensee to discuss the results of the steam generator tube inspections to be conducted during the upcoming fall 2009, Unit 2 refueling outage for Sequoyah Nuclear Plant.
This conference call is scheduled to occur towards the end of the planned SG tube inspections, but before the unit completes the inspections and repairs.
The NRC staff plans to document a summary of the conference call as well as any material that is provided in support of the call.
- 1. Discuss any trends in the amount of primary-to-secondary leakage observed during the recently completed cycle.
On October 1, 2009 an approximately 0.17 gpd primary to secondary leak was detected.
The leakage value was unchanged to the end of cycle. Presence of Argon-41 was detected in the condenser vacuum exhaust. Presently, SG 4 has an axial ODSCC indication (approximately 6.55 volts) at a tube support plate which is believed to be the leaking tube.
- 2. Discuss whether any secondary side pressure tests were performed during the outage and the associated results.
No secondary side pressure tests have been performed to date. Contingency plans are in place for a SG pressure test. The 6.55 volt indication will be In-Situ pressure tested to determine if leakage occurs. A SG pressure test will be performed, if needed, as described in the steam generator program.
- 3. Discuss any exceptions taken to the industry guidelines.
No exceptions have been taken.
- 4. For each steam generator, 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% of dents/dings greater than 5 volts and a 20% sample between 2 and 5 volts), and the expansion criteria.
The following provides number of tubes to be tested, probe types and expansion criteria per degradation mechanism.
BOBBIN FL:
100% of non-plugged tubes in all four generators will be tested full length using a mag-bias bobbin coil probe (Rows 1 through 4 U-bends were examined by Plus Point).
TTS HL:
100% of non-plugged tubes in all four generators will be tested using
+Point examination at the hot leg tubesheet expansion transition region
(+2/-8).
TTS CL 100% of non-plugged tubes in all four generators will be tested using
+Point examinations at the cold leg tubesheet expansion transition region
(+2/-10.5).
LR U-BEND:
100% of non-plugged tubes in rows 1 through row 4 in all four generators have been selected for mag-bias U-Bend +Point.
HR U-BEND:
100% of all tubes in rows 5 through row 10 in all four generators have been selected for MHI array probe (or mag-bias U-Bend +Point) inspection.
UB FS DING:
100% of non-plugged u-bend freespan dents (any voltage) found during U2C15 in all four generators have been selected for +Point examination (excluding those tubes in LR U-Bend inspection scope).
AVB DING:
100% of non-plugged tubes at AVB locations with dents found during U2C15 in all four generators have been selected for +Point examination.
MBM DING:
100% of non-plugged tubes with both an MBM and DNT at same location found during U2C15 in all four generators have been selected for +Point examination.
HL FS DING:
100% of non-plugged tubes with freespan dents greater than or equal to 2 volts between HTS and H07 found during U2C15 in all four generators have been selected for +Point examination.
H01 thru H07 DENT:
100% of non-plugged tubes with dents found during U2C15 at each hot support plate in all four generators which were greater than or equal to 2 volts selected for +Point examination.
C07 DENT:
100% of non-plugged tubes with dents found during U2C15 at the seventh cold support plate in all four generators which were greater than or equal to 2 volts selected for +Point examination.
CL FS PAIR DING 100% of non-plugged tubes with cold straight leg freespan paired dings (dent calls within 0.75 inches of each other) found during U2C15 in all four generators which were greater than or equal to 2 volts selected for
+Point examination.
Location Nomenclature for SQN U2 Notation Description HTE Tube end - hot leg HTS Top of tubesheet - hot leg H01 First support plate - hot leg H02 Second support plate - hot leg H03 Third support plate - hot leg H04 Fourth support plate - hot leg H05 Fifth support plate - hot leg H06 Sixth support plate - hot leg H07 Seventh support plate - hot leg AV1 First anti-vibration bar above H07 AV2 Second anti-vibration bar above H07 AV3 Second anti-vibration bar above C07 AV4 First anti-vibration bar above C07 C07 Seventh support plate - cold leg C06 Sixth support plate - cold leg C05 Fifth support plate - cold leg C04 Fourth support plate - cold leg C03 Third support plate - cold leg C02 Second support plate - cold leg C01 First support plate - cold leg CTS Top of tubesheet - cold leg CTE Tube end - cold leg (Examinations)
DATASET EXTENT TECHNIQU E
S/G-1 S/G-2 S/G-3 S/G-4 BOBBIN FL CTE-HTE BOBBIN 3296 3191 3226 3235 TTS HL HTS+2/-8
+Point (or MHI) 3296 3191 3226 3235 TTS CL CTS+2/-10.5 MHI (or +Point) 3296 3191 3226 3235
LR U-BEND C07-H07
+Point 338 317 339 340 HR U-BEND C07-H07 MHI (or +Point) 546 512 535 511 UB FS DING Various U-Bend FS
+Point 76 22 8
73 AVB DING Various AVB+1/-1
+Point 3
7 2
33 MBM DING Various
+Point 1
HL FS DING Various HTS+2 to H07-1
+Point 103 119 80 23 CL FS PAIR DING Various CL FS
+Point 10 11 10 2
C07 DENT C07+1/-1
+Point 148 38 101 142 H01 DENT H01+1/-1
+Point 22 25 39 3
H02 DENT H02+1/-1
+Point 2
3 3
H03 DENT H03+1/-1
+Point 7
16 1
1 H04 DENT H04+1/-1
+Point 3
6 3
H05 DENT H05+1/-1
+Point 25 12 4
7 H06 DENT H06+1/-1
+Point 69 20 30 11 H07 DENT H07+1/-1
+Point 152 56 122 69
EXPANSION CRITERIA PER DAMAGE MECHANISM Damage Mechanism Location Initial S2C16 Exam Expansion Criteria PWSCC / ODSCC Axial and Circ HL TTS
+Pt (+2/-8) 100%
HTS in all 4 SGs HL-N/A no expansion due to 100% initial scope PWSCC / ODSCC Axial and Circ CL TTS
+Pt (+2/-10.5) 20%
CTS in all 4 SGs CL-indication in initial sample results in 100% of that SG. 1 indication in expanded sample results in 100% of all S/Gs PWSCC / ODSCC Axial and Circ H/L Dings freespan
+Pt 100% HTS-H07 in all 4 SGs If crack-like indications are identified at H06-H07, then 20% of C07-C06 dings in the effected SG PWSCC / ODSCC Axial and Circ Dented 2 volts TSPs
+Pt 100% TSPs H01-C07 Dented >2Volts in all 4 SGs If crack-like indications are identified at C07, then 100% of C06 will be examined in the effected SG.
If circ indics in <2.0 volt dents, then 100%
of all H/L dents > 1.0 volts will be examined.
If circ indics in 1.0 to 2.0 volt dented TSPs and structural integrity is challenged, then TVA will develop an expansion plan for less than 1.0 volt dented TSPs.
ODSCC Axial Non-Dented TSPs BC 100% Full Length in all 4 SGs N/A base scope includes all H/L and C/L TSPs.
ODSCC Sludge Pile
+Pt (+2/-8) or MHI 100% HTS in all 4 SGs If max sludge height > 2 then ensure complete sludge height is inspected.
ODSCC Freespan BC 100% FL in all 4 SGs N/A - 100% BC base scope, +Pt or MHI indications for confirmation PWSCC / ODSCC U-bends Rows 1-10 U-bend regions 100% +Pt Rows1-4 in all SGs, 100% MHI or
+Pt Rows 5-10 in all SGs. Bobbin in MHI U-bends.
If > 0 Circ indics in R 9-10 then, 100% of R 11-20 in the effected SG.
If > 0 Circ indics in R 15-20 then 100% of all rows in the effected SG.
If >0 Axial indics in R 5-8, then 100% of R5-16, and 50% of R 17 in the effected SG.
If >0 Axial indics in R. 9-10, then 100% of R 11-25 in the effected SG.
AVB Wear U-bends BC100% F/L in all 4 SGs N/A 100% base scope, +Pt new indications and those which have changed TTS Loose Parts Wear TTS
+Pt (+2/-8) 100%
HTS, +Pt (+2/-10.5) 20% CTS, and BC 100% F/L in all 4 SGs All wear from loose parts and/or PLPs will be bounded with +Point PWSCC/ODSCC MBM with ding/dent
+Pt 100% MBM with dents or dings within 1 inch in all 4 SGs N/A - 100% BC/+Pt base scope PWSCC/ODSCC AVBs with dents
+Pt 100% AVBs with dents or dings in all 4 SGs N/A - 100% BC/+Pt base scope PWSCC/ODSCC U-bend freespan dings
+Pt 100% U-bend region freespan dings in all 4 SGs N/A - 100% BC/+Pt base scope Cold Leg Thinning Cold Leg TSPs BC 100% FL in all 4 SGs
+Pt new indications and those which have changed Cracked TSP TSPs BC 100% FL in all 4 SGs
+Pt inspection will be required in areas where adjacent tubes have cracked TSP
- 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).
The Steam Generator inspection activities are presently 80% complete The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.
- 6. Describe repair/plugging plans.
Mechanical ribbed plugs are the method to be used for plugging. Stabilization will be considered in addition to the plugging.
- 7. Describe in-situ pressure test and tube pull plans and results (as applicable and if available).
In Situ equipment is on site and screening for in situ testing will be performed as degraded tubes are identified.
A preliminary list of candidate indications has been developed based on production voltage screening criteria. A final listing will be developed based on results of sizing analysis and In-Situ Guidelines. No tube pull is planned.
No tube pull is planned.
- 8. Discuss the following regarding loose parts:
what inspections are performed to detect loose parts 100% bobbin coil in all four SGs and 100% Plus Point hot leg and cold leg top of tubesheet. Secondary side FOSAR of top of tubesheet in all four SGs and steam drum inspections in SGs 2, 3, and 4. SG 1 steam drum inspection was performed last outage.
a description of any loose parts detected and their location within the SG (including the source or nature of the loose part, if known)
FOSAR is being performed in each steam generator. FOSAR has been completed for SGs 2 and 3.
One piece of flexitalic gasket was identified and removed from SG 3 during FOSAR.
The following table is a list of eddy current Possible Loose Part (PLP) indications.
PLPs identified during previous outages have been FOSAR inspected with no loose parts remaining in the SGs. FOSAR results indicate PLPs identified by eddy current are often the result of bridging and not loose parts.
Eddy Current SG ROW COL LEG INDIC LOC PREVCYCLE 1
7 88 H
PLP HTS+.22 PLP 1
8 88 H
PLP HTS+.21 PLP 1
28 20 H
PLP HTS+.10 PLP 1
33 37 H
PLP HTS+.18 PLP 1
34 37 H
PLP HTS+.18 PLP 3
8 3
H PLP HTS+1.61 NDD 3
16 35 C
PLP HTS+1.35 PLP 3
30 58 H
PLP HTS+.18 PLP 4
7 45 C
PLP CTS+.29 NDD 4
12 47 C
PLP CTS+.22 NDD 4
24 54 H
PLP HTS+.14 NDD 4
24 55 H
PLP HTS+.18 NDD 4
26 18 C
PLP HTS+3.00 PLP 4
26 18 H
PLP HTS+3.28 PLP 4
36 45 H
PLP HTS+.28 NDD 4
39 36 H
PLP HTS+46.55 PLP 4
39 37 C
PLP HTS+46.55 PLP 4
44 41 H
PLP HTS+.12 PLP 4
44 42 H
PLP HTS+.14 NDD if the loose parts were removed from the SG The removal of the flexitalic gasket is complete in SG 3.
indications of tube damage associated with the loose parts No indication of tube wall loss associated with loose parts has been identified.
- 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).
SGs 2, 3, and 4 will receive upper internal inspections which includes feedwater tee thickness measurements. All four SGs will be sludge lanced and receive FOSAR.
FOSAR includes one in bundle inspection per quadrant plus investigating all new PLPs.
- 10. Discuss any unexpected or unusual results.
Two axial indications have been detected in the cold leg tubesheet region of SG 4. These indications are several inches down into the tubesheet. In accordance with TVAs commitment, all four SG cold leg tubesheets are being 100% inspected.
The two indications of axial ODSCC at tube support plates are larger than the Operational Assessment predicted maximum voltage. The predicted maximum voltage was 4.1 volts.
SG 3 has one 4.17 volt and SG 4 has one 6.55 volt indication. The 6.55 volt indication grew from 0.36 volts. The Operational Assessments projected probability of burst,
leakage, and quantity of indications bounded the corresponding Condition Monitoring values.
- 11. Provide the schedule for steam generator-related activities during the remainder of the current outage.
All eddy current examinations are expected to be completed by late Thursday followed by plugging. 11/12/09 All secondary side maintenance is expected to be completed by Thursday. 11/12/09 E-mail Properties Mail Envelope Properties ()
Subject:
FW: SG phone call Sent Date: 11/10/2009 3:23:10 PM Received Date: 11/10/2009 3:24:00 PM From: Lingam, Siva Created By: Siva.Lingam@nrc.gov Recipients:
Andrew.Johnson@nrc.gov (Johnson, Andrew)
Tracking Status: None Kenneth.Karwoski@nrc.gov (Karwoski, Kenneth)
Tracking Status: None Tom.Boyce@nrc.gov (Boyce, Tom (NRR))
Tracking Status: None Eugene.Guthrie@nrc.gov (Guthrie, Eugene)
Tracking Status: None Cale.Young@nrc.gov (Young, Cale)
Tracking Status: None Mark.Speck@nrc.gov (Speck, Mark)
Tracking Status: None Post Office:
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