ML030560592
| ML030560592 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 10/24/2002 |
| From: | Olshan L NRC/NRR/DLPM |
| To: | Rosalyn Jones Duke Energy Corp |
| References | |
| TAC MB6299 | |
| Download: ML030560592 (13) | |
Text
NRC Conf Call for ONS 2 EOC-19
- 1. Discuss any primary to secondary leakage prior to shutdown.
Response: Primary to secondary leakage prior to SD was <0.5 GPD.
- 2. Discuss results of secondary side pressure tests.
Response: No secondary side pressure test conducted.
- 3. Provide general description of areas examined, including expansion criteria, type of probe's used. Discuss inspection of the tube within the tubesheet, particularly the portion below the expansion/transition region.
Response: Scope of the inspection is shown on the attachment A. The expanded region of the tube is inspected with qualified Plus-Pt from the roll transition to the tube end.
- 4. Discuss the actions taken in response to Framatome's notification of the effect of tubesheet hole dilation on the service life of B&W welded plugs.
Response: FTI analyzed the allowed heatup/cooldown cycles for each plug type.
Verified that we have not and will not exceed this limit prior to SG replacement scheduled for the next refueling. All repair products used, except those listed below, are fully qualified for original 40 year operating life.
Plug Type
- Plugs Allowed Cycles Current Cycles OEM Welded Plugs 16 205 120 Remote Welded Plugs 52 33 13 Taper Welded 13 205 74 In addition, each welded plug will be visually inspected for any signs of leakage or cracking.
- 5. Describe the inspection/plugging plans with respect to industry identified severed tube issue.
Response: All plugged tubes that met the following criteria with rolled plugs in the inlet, were removed, tube dewatered if necessary, inspected and replugged.
- a. Tubes with rolled plug replaced in the inlet without dewatering and welded plug in outlet.
- b. Tubes with 1-600 rolled plug inlet and repair welded plug in outlet.
- c. Tubes with rolled plug replaced in the inlet and explosive plug in outlet.
- d. Tubes with ribbed plugs replaced in inlet with 1-690 rolled without dewatering and ribbed plug in outlet for drilled hole locations.
- e. Tubes with rolled plug replaced in inlet with original plug in outlet.
10/24/02 e8t*:II 20 t*a o00 2-dl 6810-ae8-t'88 NONNBHS 73W
Deplugging Results:
A OTSG 13 Removed None found with water in tube.
B OTSG 25 Removed 4 water < 70%
1 water >70%*
- Tube B 32-8 water level was 87% and was swollen by approx.
0.030" to 0.040" along entire length of tube. Tube initially plugged in 93, inlet plug was found missing in 1994, traced to plug installation torque issue. Inlet plug replaced without dewatering in 1994. Tube B 31-7, immediately downstream, showed no indications of wear and eddy current verified tube B 32-8 was not severed. Tube B 32-8 will be replugged with a full length stabilizer installed.
A&B OTSG 11 tubes have welded or ribbed plugs in inlet and can not be removed. Will be captured by surrounding with stabilized plugged tubes in flow direction.
- 6. Provide summary of number of indications to date of each degradation mode and axial location. Provide voltage, depth and length for most significant.
Response: Details of most significant degradation will not be available until all the special interest MRPC is completed. Special interest is approx. 10% complete as of 10/24.
- 7. Describe the repair/plugging plans for SG tubes that meet the repair/plugging criteria.
Response: For hot leg roll transitions that meet criteria for reroll repair, rerolls will be performed and tube left in service. For all other degradation that meets the plugging criteria, tube will be removed from service by installation of 1-690 rolled plugs in inlet and outlet.
- 8. Discuss the previous history of SG tube inspection results, including any "look backs" performed for significant indications where used for dispositioning (MBM's)
Response: All bobbin indications will have Plus-Pt exam and will be dispositioned based on this result. Previous data is not used directly in dispositioning process for ONS units.
E-l6BtO-288-t"98 O.WH 1W WOWWUHS -13W est7:1I 20 JV qO0
- 9. Discuss new inspection findings.
Response: To date, no new degradation mechanism has been seen. Current active mechanisms for ONS-2:
- a. Tube Support Plate Fretting Wear
- b. Impingement
- c. ODIGA in tubesheet crevice and freespan
- f.
Sleeve OD IGA/SCC in expansion transitions and parent tube adjacent to sleeve end
- 10. For 1-600 plants discuss actions taken based on Seabrook's recent findings.
Response: No additional actions have been identified for ONS units as a result of what is known of the Seabrook results to date. ONS tubing is 1-600 HTMA and would not be expected to perform similar to I-600TT tubing at Seabrook.
- 11. Discuss any use of inspection probes other than bobbin and typical rotating probes.
Response: Probes used are typical designs. 0.510 mid frequency bobbin, 0.460 Plus-Pt for RPC for tubes and 0.410 bobbin, 0.400 Plus-Pt for sleeves.
- 12. Discuss in-situ pressure test plans and results.
Response: To date, in-situ tests have not been completed or tubes identified.
Selection criteria are based on EPRI guidelines utilizing depth, length and voltage of defect.
- 13. Describe tube pull plans and preliminary results.
Response: Currently no tube pulls are planned or anticipated.
- 14. Discuss the assessment of tube integrity for the previous operating cycle.
Response: Condition Monitoring will be completed following completion of inspection and results from in-situ pressure testing if required. No problems are anticipated.
ý'
6810-288-1?98 e9t,:11 zo va 4oo WDWWUHS 73W
- 15. Discuss the assessment of tube integrity for next operating cycle.
Response: Operational assessment for first 90 days will be completed following completion of inspection prior to unit startup. OA for complete cycle will be completed within 90 days of unit startup. Inspection to date is consistent with degradation projections and no problems with justifying full cycle operation are anticipated.
- 16. Provide the schedule for SG related activities during the remainder of the current outage.
Response: Eddy current should complete by 10/27. In-situ testing, if required, should complete on 10/28. All repairs should complete by 11/1. Current site schedule has installation of SG primary manways on 11/4.
C; 6810-Z88-tH9B WOWWUHS 13W eLf, : Tf 20 t1,
- =0
Attachment A The OTSG eddy current inspection scope planned for the Oconee Unit 2 EOC-19 Refueling Outage:
Bobbin Coil (0.510 dia. MF)
Lane and Wedge MRPC (0.460 dia. Plus Point)
MRPC Upper Tubesheet Roll (0.460 dia. Plus Point)
MRPC Re-rolls Upper Tubesheet (0.460 dia. Plus Point)
MRPC Lower Tubesheet Roll (0.460 dia. Plus Point)
Bobbin Sleeve Exam (0.410 dia.)
Sleeve Upper and Lower Rolls (0.400 dia Plus Point)
Kidney Region (Sludge Pile)
(0.460 dia. Plus Point) 100% A-OTSG 100% B-OTSG Two Rows Around Sleeved Tubes A and B OTSG 100% A-OTSG 100% B-OTSG 100% A-OTSG 100% B-OTSG 100% Original Re-expansion 100% Sleeves A-OTSG 100% Sleeves B-OTSG 100% Sleeve Rolls A-OTSG 100% Sleeve Rolls B-OTSG 100% A-OTSG 100% B-OTSG The inspection covers minimum 12 inches into the tubesheet RPC Special Interest (0.460 dia. Plus Point)
- 1) 100% Bobbin indications regardless of location
- 2) 100% of all dents regardless of size or location eLt:,11 O t,2 o00 681 O-286-t'9B O.WH 1W WOWWUHS 13W
I Leonard Olshan - SFX3D.Ddf Paae 1 1 Duke Energy Corporation ONS 2 EOC-19 Preliminary Report Revised 10/30/02
- 1. Discuss any primary to secondary leakage prior to shutdown.
Response: Primary to secondary leakage prior to SD was <0.5 GPD.
- 2. Discuss results ofsecondary side pressure tests.
Response: No secondary side pressure test conducted.
- 3. Provide general description of areas examined, including expansion criteria, type ofprobe's used Discuss inspection of the tube within the tubesheet, particularly the portion below the expansion/transition region.
RMonse: Scope of the inspection is shown on the attachment A. The expanded region of the tube is inspected with qualified Plus-Pt from the roll transition to the tube end.
- 4. Discuss the actions taken in response to Framatome's notfication ofthe effect of tubesheet hole dilation on the service life of B& W welded plugs.
Response: FTI analyzed the allowed heatup/cooldown cycles for each plug type.
Verified that we have not and will not exceed this limit prior to SG replacement scheduled for the next refueling. All repair products used, except those listed below, are fully qualified for original 40 year operating life.
Plug Type
- Plugs Allowed Cycles Current Cycles OEM Welded Plugs 16 205 120 Remote Welded Plugs 52 33 13 Taper Welded 13 205 74 In addition, each welded plug will be visually inspected for any signs of leakage or cracking.
- 5. Describe the inspection/plugging plans with respect to industry identified severed tube issue.
Res=onse: All plugged tubes that met the following criteria with rolled plugs in the inlet, were removed, tube dewatered if necessary, inspected and replugged.
- a. Tubes with rolled plug replaced in the inlet without dewatering and welded plug in outlet.
- b. Tubes with 1-600 rolled plug inlet and repair welded plug in outlet.
- c. Tubes with rolled plug replaced in the inlet and explosive plug in outlet.
- d. Tubes with ribbed plugs replaced in inlet with 1-690 rolled without dewatering and ribbed plug in outlet for drilled hole locations.
- e. Tubes with rolled plug replaced in inlet with original plug in outlet.
If Leonard Olshan w SFX3D.od Paae 1l
I Leonard Olshan - SFX3Dndf Pce2 Duke Energy Corporation ONS 2 EOC-19 Preliminary Report Deplugging Results:
A OTSG 13 Removed None found with water in tube.
B OTSG 25 Removed 4 water < 70%
I water >70%*
- Tube B 32-8 water level was 87% and was swollen by approx.
0.030" to 0.040" along entire length of tube. Tube initially plugged in 93, inlet plug was found missing in 1994, traced to plug installation torque issue. Inlet plug replaced without dewatering in 1994. Tube B 31-7, immediately downstream, showed no indications of wear and eddy current verified tube B 32-8 was not severed. Tube B 32-8 will be replugged with a full length stabilizer installed.
A&B OTSG 11 tubes have welded or ribbed plugs in inlet and can not be removed. Will be captured by surrounding with stabilized plugged tubes in flow direction.
- 6. Provide summary of number of indications to date of each degradation mode and axial location. Provide voltage, depth and length for most significant.
Response: Following is the number of tubes plugged for categories shown:
Capture Locations Tube Defects IGA Wear Freespan SCC/IGA Roll Transition PWSCC Misc.
Total Plugged 2EOC-19 Total Cumulative Plugged 2A OTSG 2B OTSG 16 18 7
1 380 12 8
424 1,294 8.3%
Details of the depth, length and voltage will be provided in future report of inspection findings.
2 Paae 2 1
Le~o-nardQisha!n - SFX3D.pdf Pg Duke Energy Corporition ONS 2 EOC-19 Preliminary Report 3
- 7. Describe the repair/plugging plans for SG tubes that meet the repair/plugging criteria.
Response" For hot leg roll transitions that meet criteria for reroll repair, rerolls will be performed and tube left in service. For all other degradation that meets the plugging criteria, tube will be removed from service by installation of 1-690 rolled plugs in inlet and outlet.
Reroll repairs A OTSG: 0*
B OTSG: 38
- <10 locations identified for reroll repair, tubes were plugged and included in #6.
8& Discuss the previous history of SG tube inspection results, including any "look backs" performed for significant indications where used for dispositioning (MBM's)
Response: All bobbin indications will have Plus-Pt exam and will be dispositioned based on this result. Previous data is not used directly in dispositioning process for ONS units.
- 9. Discuss new inspection findings.
Response: No new degradation mechanism has been seen. Current active mechanisms for ONS-2:
- a. Tube Support Plate Fretting Wear
- b. Impingement
- c. ODIGA in tubesheet crevice and freespan
- f. Sleeve OD IGA/SCC in expansion transitions and parent tube adjacent to sleeve end Freespan indications have increased in number from previous inspections. The prediction of freespan cracking based on Weibul distribution indicates that a significant increase was expected. It's difficult to establish when the increase will begin to occur but this data indicates that significant increases would be expected in future inspections, however, this is the last cycle of operation for these SIG's prior to replacement. The number of freespan defects is within the worse case projections previously performed.
- 10. For 1-600 plants discuss actions taken based on Seabrook's recent findings.
Response: No additional actions have been identified for ONS units as a result of what is known of the Seabrook results to date. ONS tubing is 1-600 HTMA and would not be expected to perform similar to 1-600TT tubing at Seabrook.
Duke Energy Corporation ONS 2 EOC-1 9 Preliminary Report
- 11. Discuss any use of inspection probes other than bobbin and typical rotating probes.
Response: Probes used are typical designs. 0.510 mid frequency bobbin, 0.460 Plus-Pt for RPC for tubes and 0.410 bobbin, 0.400 Plus-Pt for sleeves.
- 12. Discuss in-situ pressure test plans and results.
Response: Following is the number of tubes identified for in-situ testing. All testing followed EPRI guidelines for hold times. Maximum pressure was approx.
4050 psig, which represents 3 times normal delta-P.
2A OTSG 2B OTSG Number Tested 10 (Axial)
TBD Results No leakage
- 13. Describe tube pull plans and preliminary results.
Response: Currently no tube pulls are planned or anticipated.
- 14. Discuss the assessment of tube integrity for the previous operating cycle.
Response: Condition Monitoring will be completed following completion of inspection and results from in-situ pressure testing if required. No problems are anticipated.
- 15. Discuss the assessment of tube integrity for next operating cycle.
Response: Operational assessment for first 90 days will be completed following completion of inspection prior to unit startup. OA for complete cycle will be completed within 90 days of unit startup. Inspection to date is consistent with degradation projections and no problems with justifying full cycle operation are anticipated.
- 16. Provide the schedule for SG related activities during the remainder of the current outage.
Response: Eddy current testing is complete. In-situ testing, if required, should complete on 10/3 1. All repairs should complete by 11/5. Current site schedule has installation of SG primary manways on 11/5.
4
Duke Energy Corporation ONS 2 EOC-19 Preliminary Report Attachment A The OTSG eddy current inspection scope planned for the Oconee Unit 2 EOC-19 Refueling Outage:
Bobbin Coil (0.510 dia. MF)
Lane and Wedge MRPC (0.460 dia. Plus Point)
MRPC Upper Tubesheet Roll (0.460 dia. Plus Point) 100% A-OTSG 100% B-OTSG Two Rows Around Sleeved Tubes A and B OTSG 100% A-OTSG 100% B-OTSG MRPC Re-rolls Upper Tubesheet 100% A-OTSG (0.460 dia. Plus Point) 100% B-OTSG MRPC Lower Tubesheet Roll (0.460 dia. Plus Point)
Bobbin Sleeve Exam (0.410 dia.)
Sleeve Upper and Lower Rolls (0.400 dia Plus Point)
Kidney Region (Sludge Pile)
(0.460 dia. Plus Point) 100% Original Re-expansion 100% Sleeves A-OTSG 100% Sleeves B-OTSG 100% Sleeve Rolls A-OTSG 100% Sleeve Rolls B-OTSG 100% A-OTSG 100% B-OTSG The inspection covers minimum 12 inches into the tubesheet RPC Special Interest (0.460 dia. Plus Point)
- 1) 100% Bobbin indications regardless of location
- 2) 100% of all dents regardless of size or location 5
I Leonard Olshan - SFX9C.pdf Paae 1 J Duke Energy Corporation ONS-2 EOC-19 Prehminary Information 1I/1/02 During in-situ pressure testing on OTSG 2B, Tube 37-27 failed to reach the full test pressure of 4300 psig representing the density corrected test pressure for 3 times normal delta-p. Upon reaching the 3900 psig test plateau, the hold period was just beginning and the leakage rate exceeded the capacity of the test system and pressure rapidly dropped to near zero. The in-situ test was a full length water pressure test. The defect of interest was an axial indication located at 15 TSP + 4.41 inches. The measured depth was 95%
TW with a length of 2 inches.
The following attachments give the information currently available:
Attachment A: Defect location in relation to S/G TSP locations.
Attachment B: Test pressures for in-situ testing and method of calculation Attachment C: Test pressurization curve for Tube 37-27 Attachment D: History of eddy current inspection of Tube 37-27 back to 1993.
Subsequent visual inspection indicates the axial defect at this location had opened to a gap of approx. 1/16"-1/8". Subsequent testing with a bladder was not deemed possible due to opening size. Subsequent bobbin exam indicates a length of approx 1.5 inches.
MRPC exam was not performed due to likelihood that rotating element would not adequately rotate through the defect location.
V Leonard Olshan - SFX9C.D~df Pacie 11
Leonard Olshan --SFX9C.pdf GON 26 Se,:cm @ý,ener-,-or ln-s 4 u Tube 37-27 OTSG FULL LENGTH Full Length In-Situ Toolhead and Water Line I5F ube S?.4 F104le.
Full Length In-Situ Toolhead and Water Line Page2.21
[ Leonard Olshan-SFX9C.pdf IN SITU PRESSURE TEST LOADS ALL DEFECTS PLANT Oconee 2
AM Crack (Axial or Circ) Testing in AN Tube Regions Full Tube Setup or Localized Inputs Pw.-
2200 psi Inp P=...= "
925 psi AP,.=
1275 psi Normal Operat "aP,,,.sa 2575 psi Faulted DP ODp-0 625 in ID,,
Safety Factors:
SF..so 1 43
- SFpoop, Correction Factors:
CFh,-.
1 083 CFa,*a*
CF.ý =
100 pSI p-.
TARGET TEST PRESSURES:
1 0 Normal Operating P, - AP,"CFp,_
+ CF,. + P_
Pt=
1490 psi its Source 18-1236194-04 ing Differential Pressure 0551 In 349 psi 9 psi Water Testing Target Pressure Pis - P, + CF.,
Bladder Testing Pis" 1839 psi Target Pressure 20 MSLBIFAULTED P,- AP1. 4 °CFh,,_, + CF,,
+ P_
Water Testing P,,.
2898 psi Target Pressure -
P P 2 + CF.
3247 psi Bladder Testing Target Pressure =
1500 psi 1850 psi 3250 psi 3 0 STRUCTURAL LIMIT Condiioril - SFP AP"
._P," CF_.... + CF..+ P Cwrionl -
4251 psi Condffcrn2 - SFysm" AP,.=
- CF-, + CF..+ P_.
Condltion2 -
4093 psi P3 - Larger of Condition I or Condition 2 Water Testing P-
.4251 Target Pressure-P3a -
P3 + CFbwd P3a -
4600 psi Bladder Testing Target Pressure =
4300 psi 4650 psi Pg 9e 3 oL 3
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