ML17009A383

Degraded Voltage Pre-Submittal Public Meeting Slides

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

Text

E. I. Hatch Nuclear Plant Degraded Grid Voltage License Amendment Request

HNP Degraded Grid Voltage LAR Overview Definitions DVR - 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 kV MRV - Minimum Required Voltage on 4 kV bus; is the greater of a) 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 grid

HNP Degraded Grid Voltage LAR Overview Purpose of LAR and Submittal Date

• Eliminate use of manual actions for degraded voltage protection

• LAR Submission: Targeting February 28, 2017

• The LAR will contain the following:

Detailed Description 3.0 Technical Evaluation 4.0 Regulatory Evaluation 4.1 Significant Hazards Consideration 4.2 Applicable Regulatory Requirements/Criteria 4.3 Precedent 4.4 Conclusion 5.0 Environmental Consideration 6.0 References

HNP Degraded Grid Voltage LAR Overview Physical Change Highlights

• Replace existing SATs and add a 3rd SAT 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 LAR Overview Technical 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 value will be above the MRV value.

• The DVR voltage reset value, including tolerances, will be set below the MEV.

HNP Degraded Grid Voltage LAR Electrical system lineup after mods are implemented Existing Electrical Lineup Revised Electrical Lineup Bus Normal Supply Alternate Supply Normal Supply Alternate Supply 1E SAT 1D SAT 1C SAT 1E SAT 1D 1F SAT 1D SAT 1C SAT 1C SAT 1E 1G SAT 1D SAT 1C SAT 1D SAT 1C 2E SAT 2D SAT 2C SAT 2E SAT 2D 2F SAT 2D SAT 2C SAT 2C SAT 2E 2G SAT 2D SAT 2C SAT 2D SAT 2C

HNP Degraded Grid Voltage LAR Low-Voltage Switchyard Layout Showing Unit 2 SATs, Added SATs & Upgraded / Added 4 kV Cable Buses Replacement U1 SATs Replacement U2 SATs N

Added U1 & U2 SATs

HNP Degraded Grid Voltage LAR Limiting Values Diagram Bus 1E is shown; other buses are similar

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?