ML052140189

RIC 2005 Presentation - H1 - James Meister - Power Uprates

ML052140189
Person / Time
Site:	Dresden, Quad Cities
Issue date:	03/08/2005
From:	Meister J Exelon Nuclear
To:	Office of Nuclear Reactor Regulation
References
Download: ML052140189 (10)

Text

Exelon Learnings from Extended Power Uprates Presentation to NRC 2005 Regulatory Information Conference March 8, 2005 Washington DC James R. Meister Exelon Nuclear

Overview

• Operational Challenges from EPU

• Vibration Monitoring and Actions

• EPU Vulnerability Review and Actions

• Steam Dryer Repairs and Replacement 2

Dresden / Quad Cities EPU

• Increased steam and feed flow velocities have caused increased pressure pulsations and vibration levels, leading to equipment failures and degradation.

- Steam Dryer Failures

- Main Steam Relief Valve Failure

- Main Steam Line Low Pressure Switch Failure (1/2 Group Isolation)

- Turbine Control Valve Pressure Switch Failure (1/2 Scram)

- HPCI Test Tap Connection Failure

- Main Steam Drain Line Failure

- Feedwater Sample Probe Failure

• Industry data indicates that nearly all EPU related problems are caused by increased vibration. 3

Operational Challenges from D/Q EPU

• Reduction of margin has affected several systems

- Reduction in available Main Steam Safety Valve set point tolerance

- Reduction in Feedwater Heater Drain Emergency Valve capacity

- Previous Standby Feedwater and Condensate Pumps are normally operated

- Reduction in Main Condenser margin 4

Learned

• Teams were established to address three major impact areas

- Vibration Impact Resolution

- EPU Vulnerability Review and Actions

- Steam Dryer Repair and Replacement

• Exelon established Technical Human Performance Initiative 5

Vibration Monitoring and Actions

• Monitoring and Performance Evaluations for Critical Subcomponents

- Accelerometers to collect actual vibration data for piping, valves and actuators

- Shaker table testing at Wyle Labs

- Analytical Modeling of affected components

• Resulting Actions

- Adjust PM scope and frequency based on results

- Implemented focused / detailed outage walkdowns

- Identify subcomponent wear and implement modifications for ERV and Target Rock Valves 6

EPU Vulnerability Review

• Comprehensive and rigorous review of systems and components

- Utilized multiple industry organizations

- For the purpose of this review, every component in the plant was assumed to be susceptible to failure, unless proven otherwise

- Evaluated changes in operating parameters post EPU for all 4 units

• Flow rates, temperature, pressure, radiation levels, vibration levels, wear

- Review was conducted both at the system and component levels

- 53 systems included

- Identified potential vulnerabilities due to the changed parameters

- Provided recommendations to address the potential vulnerabilities 7

EPU Vulnerability Review Results

• Reviews confirmed that adequate safety margin exists

• 101 recommendations were made

- 60 require outage inspections over next 4 years

- 9 involve non-outage work

- 32 involve additional analyses or studies

- 27 are Exelon specific

- 74 have potential BWR fleet applicability

• Review results were subject to three independent challenges

- Internal Team Challenges

- Executive Challenge Board

- BWROG Challenge review

• Actions are in progress and Dresden and Quad Cities 8

Steam Dryer Repairs and Replacement

• Enhanced repairs implemented at Dresden 2/3 and Quad Cities 2

• Dryer Replacement Project Initiated

- Develop advanced steam dryer design

- Implement design features to minimize stresses

- Qualify the replacement dryer through testing and analysis

- Instrument the first dryer to verify design loadings

- First installations will be at Quad Cities units 1 & 2 Spring 2005 9

Conclusions

• Adverse effects have been and are being addressed

• Safety margins were confirmed adequate

• Exelon experience has been shared with the industry and with the NRC

• Implementation of recommended actions continues 10