ML12258A080
| ML12258A080 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 09/14/2012 |
| From: | Steam Generator Tube Integrity and Chemical Engineering Branch |
| To: | |
| Johnson A | |
| References | |
| Download: ML12258A080 (4) | |
Text
NRC CONFERENCE CALL ST. LUCIE UNIT 2 STEAM GENERATOR INSPECTION SEPTEMBER 13, 2012 AREVA 86/19 TI REPLACEMENT STEAM GENERATOR (RSG)
Overview of Inspection:
- No tube integrity issues identified
- Average wear rate attenuation continues
- Preliminary OA supports full cycle operation
- Additional preventive plugging will be implemented to increase margin; similar to past inspections
- SONGS operating experience was applied to the inspection; no issues were identified Examination Scope for third in-service inspection:
- 100% Bobbin
- +Point of all periphery tubes hot & cold leg
- +Point diagnostics based on bobbin results
- +Point discretionary profiling History of wear indications/ affected number of tubes (Cumulative):
INSPECTION YEAR 2009 2011 2012 SG A 3700/ 1231 5864/ 1862 7646/ 2211 SG B 2157/ 815 2963/ 1125 3988/ 1503 Wear rate progression (%/EFPY):
INSPECTION YEAR 2009 2011 2012 Avg.
Growth Upper 95th Avg.
Growth Upper 95th Avg.
Growth Upper 95th SG A 7.9 13.6 4.0 9.2 2.6 7.5 SG B 7.7 13.0 1.6 6.3 1.0 4.2
NRC CONFERENCE CALL ST. LUCIE UNIT 2 STEAM GENERATOR INSPECTION SEPTEMBER 13, 2012 Wear distribution:
Wear Rates 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 2009 2011 2012 Inspection Year Wear (%/EFPY)
SG A - Avg SG B - Avg SG A - 95th SG B - 95th
NRC CONFERENCE CALL ST. LUCIE UNIT 2 STEAM GENERATOR INSPECTION SEPTEMBER 13, 2012 Preliminary CMOA Results:
- Independent assessments will be performed by Aptech and Areva
- Maximum wear depth: 40% TW
- Preliminary OA Results shows POB < 5%:
o 7 required tube plugs in A SG; none in B SG (All at 40%)
o Additional tubes will be plugged to provide defense in depth Tubes with multiple indications High current wear/wear rate o Wear rate increase factor of 24% applied to account for effects of power uprate.
- Plan to inspect next outage AVB Wear Indication Depth Distribution PSL-2 SGA Sep-2012 0
500 1000 1500 2000 2500 3000 Estimated Bobbin Depth (%TW)
Number of Indications Previously-Reported Indications Newly-Reported Indications Previously-Reported Indications 161 1664 1119 849 666 481 313 119 7
0 0
Newly-Reported Indications 4
1237 325 141 59 14 2
0 0
0 0
<5%
5-9%
10-14%
15-19%
20-24%
25-29%
30-34%
35-39%
40-49%
50-59%
>=60%
NRC CONFERENCE CALL ST. LUCIE UNIT 2 STEAM GENERATOR INSPECTION SEPTEMBER 13, 2012 Secondary Side Scope:
- FOSAR - SG A, SG B o Metal shaving ~3 x 1/8 from SG A annulus o Beebe size part retrieved from debris screen SG B
- Upper Steam Drum o Feedwater Ring Inspection Cover Assessment SG A, SG B o Sample of primary separators for wear SG A, SG B o General Walkdown SG A, SG B
==
Conclusions:==
- Steam Generators continue high, but manageable amount of wear
- No tube integrity issues identified
- Average and statistical wear rate attenuation continues
- Preliminary OA supports full cycle operation
- Additional preventive plugging will be implemented to increase margin; similar to past inspections
- Inspection planned after one cycle of operation