ML17009A383

Edwin I. Hatch Nuclear Plant, Unit Nos. 1 and 2: Degraded Voltage Pre-Submittal Public Meeting Slides

ML17009A383
Person / Time
Site:	Hatch
Issue date:	01/09/2017
From:	Southern Nuclear Company
To:	Orenak M D Plant Licensing Branch II
Orenak M D
References
CAC MF9043, CAC MF9044
Download: ML17009A383 (12)

Text

E. I. Hatch Nuclear PlantDegraded Grid VoltageLicense Amendment Request HNP Degraded Grid Voltage LAROverviewDVR -Degraded Voltage Relay -senses voltage on 4 kV Emergency Bus-provides contacts for automatic action LAR -License Amendment Request LOCA -Loss of Coolant Accident -requires group starting of Class 1E equipment MEV -Minimum Expected Voltage on 4 kV bus concurrent with a)steady-state LOCA loading, and b)offsite supply at minimum normal voltage, 101.3% of 230 kVMRV -Minimum Required Voltage on 4 kV bus; is the greater ofa)Min voltage for non-accident operation of Class 1E loads, b)Min pre-start voltage for LOCA group motor starting c)Min start/run voltage for individual motors under max accident loading SAT -Startup Auxiliary Transformer -supplies 4 kV buses from 230kV gridDefinitions HNP Degraded Grid Voltage LAROverview*Eliminate use of manual actions for degraded voltage protection*LAR Submission: Targeting February 28, 2017

• The LAR will contain the following:Detailed Description 3.0Technical Evaluation 4.0Regulatory Evaluation 4.1 Significant Hazards Consideration 4.2Applicable Regulatory Requirements/Criteria 4.3Precedent 4.4Conclusion5.0Environmental Consideration 6.0References Purpose of LAR and Submittal Date HNP Degraded Grid Voltage LAROverviewPhysical Change Highlights*Replace existing SATs and add a 3rdSAT per unit*Expand 4 kV cable bus system and realign loads among the 3 SATs*Replace 4 kV breakers and upgrade bus bar supports

• Replace induction disc DVRs with new solid-state DVRs (3 per bus)

HNP Degraded Grid Voltage LAROverviewTechnical Specification Change Highlights*TS 3.8.1 -Change required OPERABLE offsite circuits from 2 to 3*TS 3.3.8.1 -Increase DVR actuation voltage, specified for each bus*TS 3.3.8.1 -Decrease DVR actuation delay time

• TS 3.3.8.1 -Return alarm relay function to non-Tech Spec status Methodology for Relay Setpoints(Voltage and Time Delay)*Degraded Voltage Relays (DVRs) shall be set such that offsite power will be automatically disconnected and transferred to onsite power during an extended degraded grid condition (any voltage dip having a longer duration than expected for normal or accident operations). *The DVRs on each Class 1E 4KV bus will be set so that, including tolerances, voltage dropout valuewill be above the MRV value.*The DVR voltage reset value, including tolerances, will be set below the MEV.

HNP Degraded Grid Voltage LARElectrical system lineup after mods are implementedExisting Electrical Lineup Revised Electrical LineupBusNormal Supply Alternate Supply Normal Supply Alternate Supply 1ESAT 1DSAT 1CSAT 1ESAT 1D 1FSAT 1DSAT 1CSAT 1CSAT 1E 1GSAT 1DSAT 1CSAT 1DSAT 1C2ESAT 2DSAT 2CSAT 2ESAT 2D2FSAT 2DSAT 2CSAT 2CSAT 2E 2GSAT 2DSAT 2CSAT 2DSAT 2C HNP Degraded Grid Voltage LARLow-Voltage Switchyard Layout Showing Unit 2 SATs,Added SATs & Upgraded / Added 4 kV Cable BusesReplacementU2 SATsAdded U1 & U2 SATsReplacementU1 SATs HNP Degraded Grid Voltage LARBus 1E is shown; other buses are similar Limiting Values Diagram Future Submittal*Increased RAS times for a single offsite power source out of service*LAR Submission: Targeting June 9, 2017 Hatch Degraded Grid LAR*Questions?