ML12258A080

NRC Conference Call St. Lucie Unit 2 Steam Generator Inspection September 13, 2012

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. Upper Avg. Upper Avg. Upper Growth 95th Growth 95th Growth 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 Rates 16.00 14.00 Wear (%/EFPY) 12.00 SG A - Avg 10.00 SG B - Avg 8.00 6.00 SG A - 95th 4.00 SG B - 95th 2.00 0.00 2009 2011 2012 Inspection Year Wear distribution:

NRC CONFERENCE CALL ST. LUCIE UNIT 2 STEAM GENERATOR INSPECTION SEPTEMBER 13, 2012 AVB Wear Indication Depth Distribution PSL-2 SGA Sep-2012 3000 Previously-Reported Indications 2500 Newly-Reported Indications 2000 Number of Indications 1500 1000 500 0

<5% 5-9% 10-14% 15-19% 20-24% 25-29% 30-34% 35-39% 40-49% 50-59% >=60%

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 Estimated Bobbin Depth (%TW)

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

NRC CONFERENCE CALL ST. LUCIE UNIT 2 STEAM GENERATOR INSPECTION SEPTEMBER 13, 2012 Secondary Side Scope:

• Sludge Lance and Upper Bundle Flush - SG A, SG B

• 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