ML21078A095

Session W20 - James Petty - Slide Deck 3

ML21078A095
Person / Time
Site:	Braidwood
Issue date:	03/08/2021
From:	Petty J Exelon Nuclear
To:	NRC/RGN-III
References
Download: ML21078A095 (4)

Text

Risk Informed Completion Times Licensee Experience James T. Petty Director of Site Operations Braidwood Generating Station - Exelon Nuclear

TSTF-505 Overview

• TSTF-505 license amendment requests (LAR) approval for Braidwood in March 2020.

• A new Risk-Informed Completion Time (RICT) program was added to the Administrative Controls section of TS

• RICT is only applied in Modes 1 and 2 (Exelon does not have a Shutdown PRA so Modes 3 and 4 were not included)

• RICT may not exceed 30 days

• If TS LCO is not restored prior to reaching RICT, then TS requirements for plant shutdown or other remedial action become applicable

• RICT is not permitted for a loss of TS safety function configuration or inoperability of all required safety trains

• Impacts on baseline CDF and LERF are periodically monitored

TSTF-505 Benefits

• Emphasis on risk-significant configurations

• Increased control of plant configuration during SSC unavailability

• Avoided shutdowns = Avoided safety challenges

• Reduced use of NOEDs

• Increased flexibility in scheduling maintenance

• Shorter, less-complex refueling outages - Outage work moved online

• Reduced organizational stress with short work windows

• Increased plant availability and capacity factors

RICT Examples at Braidwood

• Station Auxiliary Transformer (SAT) work window - Fall 2020

• Normally requires 3 separate 72-hour LCO windows to complete all PMs on both transformers.

• Work window scope revision with RICT requires a single LCO window.

• Results in less EDG and equipment manipulations.

• Component Cooling Water (CC) system Heat Exchanger (HX) work - Winter 2021

• CC HX flange degradation identified in 2011 required repairs to ensure minimum wall criteria/maximum allowable wall stresses are maintained.

• Outage work scope would have required an ~12-day work window that would be scheduled only 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> off outage critical path.

• 51 hours5.902778e-4 days <br />0.0142 hours <br />8.43254e-5 weeks <br />1.94055e-5 months <br /> of scope expansion contingency work would potentially challenge overall outage duration and goals.

• Significant challenge to Shutdown Safety profile and Shutdown Cooling availability.