|Person / Time|
Tennessee Valley Authority
|To:||Shea J W, Skaggs M D|
Office of Nuclear Reactor Regulation
|Jordan N J|
|Download: ML18248A102 (21)|
Watts Bar Nuclear Plant (WBN)Pre-Submittal Meeting for Proposed License Amendment Request Regarding Shutdown Board Cleaning September 6, 2018
- Opening Remarks*Scope of 6.9 kilovolt (kV) General Electric (GE) Metal Clad Switchgear Maintenance*System Overview
- WBN Electrical Design
- Safety Related Load Distribution
- Effects of De-energized 6.9 kV Shutdown Board (SDBD)
- Proposed Technical Specification (TS)Changes
- Regulatory Precedent
- Schedule for Submittal*Summary and Closing Remarks Agendal 2 Opening Remarks*Due to WBN Unit 1 and Unit 2 sharing the alternating current (AC) electrical power distribution system and sharing several other systems, performing maintenance on a AC electrical power distribution subsystem (6.9 kV SDBDand associated 480 V SDBDs) for a shutdown unit also affects the operating unit.*The current eight-hour completion time for a de-energized AC electrical power distribution subsystem does not support maintenance on a set of 6.9 kV/480 V SDBDs. *The proposed license amendment request (LAR) will extend the completion time from eight hours to the most limiting Completion Time of the 'associated required features' when maintenance is
performed on a set of 6.9 kV/480 V SDBDs with one unit in operation.
l 3 Scope of 6.9 kV GE Metal Clad Switchgear Maintenance l 4 ACTIVITIESDURATION Clearance placement and removal (including load alignment)12 hours
Ground placement and removal9 hours
Compartment Inspections (21 compartments)42 hour
sE-16 light resistor replacements Pull-out fuse block tension Relay and Instrument PT drawer operationCircuit Breaker Interface Inspections and adjustments (17 breakers)34 hours
Primary/Secondary disconnects Shutters Breaker position and interface measurements and adjustmentsBus Inspection and Tests8 hours
As-found and as-left megger
DLRO Torque checksNote: The preventive maintenance activities for the 6.9 kV switchgear has the longest duration. The associated 480 V SDBDs and 1E MCCs will also be de-energized during this period. Preventive maintenance inspections for these boards is normally performed during the same outage window to minimize impact to the operating unit and to increase outage schedule efficiency.
System Overview*The onsite Class 1E AC electrical distribution system supplies electrical power to two power trains shared between the two units.*Some safety-related systems (e.g., Essential Raw Cooling Water (ERCW), Component Cooling (CCS), Emergency Gas Treatment (EGTS), Auxiliary Building Gas Treatment (ABGTS), Control Room Emergency Ventilation (CREVS),
and Control Room HVAC (CRACS)) are shared between the
units.*Shared loads are distributed across both unit's AC electrical power distribution subsystems.
l 5 System Overview*The core cooling and containment cooling system loads (e.g., Safety Injection (SI) pumps, Auxiliary Feedwater(AFW) pumps, Residual Heat Removal (RHR) pumps, Centrifugal Charging pumps, Containment Spray (CS) pumps, and Air Return System (ARS) fans) are unitized to the respective
unit's 6.9 kV/480 V SDBDs.*The impacts of an inoperable offsite power source or diesel generator (DG) on an opposite unit's SDBD differ from the impacts of an inoperable offsite power source or DG on an associated unit's SDBD, due to the loads powered from the
l 6 Watts Bar Electrical Design -Both Units in Operation l 7 Watts Bar Electrical Design -6.9 kV SDBD 1A-A De-energized l 8 Safety Related Load Distribution -Both Units in Operation l 9 Example Effects of De-energized 6.9 kV SDBD(For 6.9 kV SDBD 1A-A, Assuming Unit 1 in Mode 6 or defueled, Unit 2 in Mode 1)l 10Unit 1 SystemsRequired ModesU1 / U2 TS Allowed Outage Time (AOT)SI pump 1A-A1, 2, 3, 4NA / NAAFW pump 1A-A1, 2, 3, 4NA / NARHR pump 1A-A1, 2, 3, 4, 5NA / NACharging pump 1A-A 1, 2, 3, 4NA / NACS pump 1A-A1, 2, 3, 4NA / NAARS fan 1A-A1, 2, 3, 4NA / NAPressurizer (Przr) HtrGrps1A-A, 1D1, 2, 3NA / NAShared SystemsRequired ModesU1 / U2 TS AOTERCW pumps J-A, Q-A1, 2, 3, 4, 5NA /72 hour
sCCS pump 1A-A1, 2, 3, 4, 5NA / NA*CCS pump C-S (Alt. Feeder)1, 2, 3, 4, 5NA / NA*EGTS fan A-A1, 2, 3, 4NA / 7 daysControl Room (CR) Air Handling Unit (AHU) A-A1, 2, 3, 4, 5, 6, During Irradiated Fuel Movement7 days / 7 days125 V Vital Battery Charger I1, 2, 3, 4, 5, 6, During Irradiated Fuel Movement NA* /2 hour
s120 V Vital Inverters: 1-I, 2-I1, 2, 3, 4, 5, 6, During Irradiated Fuel Movement NA* /24 hour
sAC electrical power distribution1, 2, 3, 4, 5, 6, During Irradiated Fuel MovementNA* /8 hour
s* With appropriate system lineup.
Proposed TS Changes to Facilitate SDBD Maintenancel 11 TSCurrentProposed NoteLCO 3.8.1, AC Sources -72 hour
sConditions B and CEnter Condition for inoperable DGOperating, Condition E10 days / 7 daysand Condition for inoperable offsite circuit due to inoperable power source to opposite unit shutdown board.LCO 3.8.7, Inverters -Operating24 hour
sNew Condition D When due to opposite unit AC-Operating, Condition Ato declare affected shutdown board inoperable. features inoperableLCO 3.7.8, ERCW,72 hour
s7 daysSeparate LAR to Adopt TSTF-500Operating, Condition A Proposed WBN 1 TS 3.8.1 Changes (same for WBN 2)l 12 Proposed WBN 1 TS 3.8.1 Changes (Continued) (same for WBN 2)l 13 Proposed WBN 1 TS 3.8.7 Changes (same for WBN 2)l 14 Proposed WBN 1 TS 3.8.8 Changes (same for WBN 2)l 15 Proposed WBN 1 TS 3.8.9 Changes (same for WBN 2)l 16 Regulatory Precedent*The proposed changes are consistent with the changes made to the Sequoyah (SQN) TS during the ITS conversion (ML15238B460, ML15236A351, ML15258A511, ML15254A509, and ML15258A516).l 17 Schedule for Submittal*September 2018 -Pre-submittal meeting with NRC*October 2018 -Submit LAR to NRC
- Request NRC approval by October 2019 with a 90-day implementation period to support the WBN Unit 1 outage scheduled for Spring 2020 (U1R16).*December 2018 -Telecon or meeting to discuss any NRC questionsl 18 Summaryl 19The proposed TS completion times for in-operable 6.9 kV and associated 480 V SDBDs considers the impact of shared loads required for an operating unit while providing a window for maximizing maintenance for the opposite unit
when under outage conditions.
Closing Remarks*Proposed LAR is needed to support a two-unit operating site at WBN.*Due to the commonality of the AC electrical power systems, performing maintenance on 6.9 kV (and associated 480 V) SDBDs for a shutdown unit affects operability on the operating unit.*The LAR will extend the completion times for inoperable AC electrical power systems when maintenance is performed on a