ML21078A095
| 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.