ML061670325
| ML061670325 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 06/14/2006 |
| From: | Tulon T Exelon Generation Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML061670325 (23) | |
Text
1 Quad Cities Station Update End-of-Cycle Meeting June 14, 2006 Tim Tulon Site Vice President
2 Topics:
- Extended Power Uprate
- The problem
- The fix
- Radiation Reduction
3 Extended Power Uprate Completed
- 17% Power Uprate
- Produce 912 megawatts electric
- NRC approval in December 2001
- Initial EPU operation:
- Unit 2 in March 2002
- Unit 1 in December 2002 Objective - Increase total generation output on both reactors
4 The Problem Increased steam flow Increased acoustic loads Increased Steam Dryer loads Increased steam line piping vibrations ERV actuator damage Steam Dryer cracks
5 Finding the Source
- Unprecedented testing and analysis determined the source of the vibration to the standpipes on the steam lines where the valve attach to the piping.
- The length of the standpipe was increased to reduce the acoustics inside the pipe. ---
Similar to tuning a pipe organ, or blowing over the top of a soda bottle.
ERV Standpipe
6 State-of-the-Art Testing and Analysis Conducted to Validate Vibration Source
- Testing conducted in six states
- Scale models of actual Quad Cities reactor and piping utilized
- Shaker table testing conducted to duplicate actual vibration levels
7 Actions Taken to Correct Vibration Problem
- Installed New Steam Dryers
- More robust
- Installed Acoustic Side Branch Modification
- Retune the steam system
- Installed Upgraded Valve Actuators
- Hardened the actuator
8 New Steam Dryers
- Both Quad Cities steam dryers were replaced in early 2005 with a more robust design:
- Increased stress margins on steam dryers
- Instrumentation provided validation of design load
- Strain gauges provided stress data for analytical purposes
9 2006 Electromatic Relief Valve Upgrade
- Late 2005 issues were discovered with the actuators on the Electromatic Relief Valves (ERVs) due to vibration.
- The ERV actuators have now been replaced with more robust design:
- Several ERV actuator replacement options evaluated. New General Electric design proved to be most rigorous as validated with shaker table tests.
10 Shaker Table Testing ERV Actuator Testing ERV Testing
11 New ERV Actuator -vs-Previous New GE Design Previously Installed Design
12 2006 Acoustic Side Branch Modification Removing the Source of the Vibrations
13 2006 Acoustic Side Branch Modification
- Objectives:
- Reduce dryer loading to increase stress margin for long-term operation of dryer
- Reduce overall MSL vibrations impacting ERV actuators and other attached main steam components
- Retuned the steam system
14 How Does the ASB Work?
The addition of the ASB increases the effective length of the ERV/SV standpipe, thereby decreasing the frequency of the acoustic standing wave. It is similar to a muffler, the ASB tunes the steam flow to reduce vibrations in the piping.
15 Acoustic Side Branch Mod Main Steam Safety Valve Electromatic Relief Valve ASBs
16 Unit 2 Startup Testing RESULTS:
Reduced to ~ 50% Original Licensed Thermal Power Levels.
- Meaning: today steam piping vibration levels at full-EPU power is approximately 50% than when the plant was first put in to commercial operation in 1972.
17 Typical Accelerometer Data Results Q2R18 Accelerometer Trends Target Rock Inlet Flange - X 0
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0
500 1000 1500 2000 2500 3000 Core Thermal Power, MWt Acceleration, grms 3A Target Rock Inlet Flange X1 Historical (pre-ASB) EPU Value Historical (pre-ASB) OLTP Value 3A Target Rock Inlet Flange X2 3A Target Rock Historical - X Last May w/o ASBs With ASBs
18 Conclusions
- Main Steam Line (MSL) vibrations are reduced
- The ASB modification effectiveness has been confirmed. This adds significant safety margin and substantially increased vibration tolerance to the steam dryer structural integrity and other main steam line components.
- Both units can operate safely and reliably at EPU power levels.
ASBs Work!
19 Radiation Exposure Efforts
20 Station Has Taken Aggressive Actions to Reduce Radiation Exposure
- Chemical decontamination of reactor piping on both units
- Replacement of turbine blades which contained high sources of Cobalt 60
- Installed permanent lead shielding in several high radiation areas of the plant
- Improved worker training / increased awareness through individual dose goals
21 486.0 436.3 336.2 190.0 162.0 0 rem 100 rem 200 rem 300 rem 400 rem 500 rem 600 rem Q2R16 (2002)
Q2R17 (2004)
Q2R18 (2006)
Q2R18 minus ASB / Dryer Q2R19 projected (2008)
Dose (person-rem)
Red line represents 150 rem - our path to full INPO points and industry best dose performance Red line represents 150 rem - our path to full INPO points and industry best dose performance U2 Outage Dose Reduction Trend Industry Best
22 Where Are We Going INPO Collective Radiation Exposure Point Performance 6.2 9.7 10.0 0.0 0.0 0 points 1 points 2 points 3 points 4 points 5 points 6 points 7 points 8 points 9 points 10 points Current 2007 2008 2009 Full Points Industry Best Red line represents 150 rem - our path to full INPO points and industry best dose performance Red line represents 150 rem - our path to full INPO points and industry best dose performance
23 Questions?