ML13024A405

Licensee Slides from 1/24/13 Meeting to Discuss Offsite Power

ML13024A405
Person / Time
Site:	Diablo Canyon
Issue date:	01/24/2013
From:	Bates A, Reimers G, Richardson M, Summy J Pacific Gas & Electric Co
To:	Joseph Sebrosky Plant Licensing Branch IV
Sebrosky J
References
Download: ML13024A405 (20)

Text

Diablo Canyon Power Plant Offsite Power January 24, 2013 Washington DC Pacific Gas and Electric Company Al Bates Gregg Reimers Michael Richardson Jeff Summy 1

Diablo Canyon Power Plant 2

Agenda

• High level overview of Diablo Canyon offsite power system

• Changes to the Auxiliary offsite power circuit (500 kV) being considered

• Grid changes to the 230 kV transmission network being considered

• Impacts to the December 29, 2009 license amendment request related to delayed offsite power circuit conformance with GDC 17 3

Overview of Offsite Power Systems

• The Transmission Grid (Western Interconnect) at DCPP provides power at two voltage levels.

• The immediately available preferred (offsite) power circuit is supplied power via the 230 kV transmission network.

- Two incoming transmission lines

- Cross-tie capability between the two units

• The delayed preferred (offsite) power circuit is supplied power via the 500 kV transmission network.

- Three incoming transmission lines 4

Overview of Grid Interface 742 642 542 Midway Line No. 2 732 632 532 Midway Line No. 3 722 622 Gates No. 1 500kV Switchyard 282 230kV Mesa 500kV Aux Aux Transformers 25kV Transformers 262 MODs MODs Morro Bay 212 Unit Unit 1 2 292 Startup 1-1 2-1 Transformers 12kV Startup Bus 374 384 Capacitor Banks 5

Overview of Offsite Power Circuits 230 kV 500 kV Switchyard Switchyard 632 532 212 Main Trans 211-1 211-2 LTC LTC SU Trans 1-1 2-1 MOD 52VU12 52VU24 12 kv SU 12 kv SU Aux Trans 1-1 Aux Trans 1-2 Bus Unit 1 Bus Unit 2 52VU11 Main Gen 52VU14 SU Trans 1-2 52HE3 52HD15 52HE2 52HD14 52HG15 4 kV Bus E 4 kV Bus D DG 11 DG 12 DG 13 52HH14 52HG14 52HH13 52HG13 52HF13 52HF14 4 kV Bus H 4 kV Bus G 4 kV Bus F 6

Issues Being Addressed

• LAR submitted to address delay time in UFSAR for delayed offsite power circuit

• Considering changes to delayed Auxiliary offsite power circuit to make immediately available

• Considering changes to 230 kV transmission network to increase capacity, flexibility, and address long term load growth 7

Changes to the Auxiliary offsite power circuit being considered

• Generator Output Breakers to replace MOD

- Auxiliary offsite power circuit becomes immediately available subsequent to a unit trip

- Startup offsite power circuit becomes backup to Auxiliary offsite power circuit

- Protective logic changes w/ dual unit trip load shed logic to support single Startup transformer operation 8

Changes to the Auxiliary offsite power circuit being considered Generator output breaker with 500 kV as an immediate source of offsite power 742 642 542 Midway Line No. 2 732 632 532 Midway Line No. 3 722 622 Gates No. 1 500kV Switchyard 282 230kV Mesa 500kV Aux Aux Transformers 25kV Transformers 262 Morro Bay 212 Unit Unit 1 2 292 Startup 1-1 2-1 Transformers 12kV Startup Bus 374 384 Capacitor Banks 9

Changes to the Auxiliary offsite power circuit being considered 10

Changes to the Auxiliary offsite power circuit being considered 11

Potential addition of a 500/230kV transformer bank

• Add a 500/230 kV transformer bank

- Normal operating metering issue if loads fed directly from the transmission grid

- Additional lines from the 500 kV to 230 kV switchyards needed

- Breaker configuration to ensure 500 kV and 230 kV not connected 12

Potential addition of a 500/230kV transformer bank 742 642 542 Midway Line No. 2 732 632 532 Midway Line No. 3 722 622 Gates 500kV Switchyard No. 1 282 230kV Mesa 500kV Aux Aux Transformers 25kV Transformers 262 MODs MODs Morro Bay 212 Unit Unit 1 2 292 Startup 1-1 2-1 Transformers 12kV Startup Bus 374 384 Capacitor Banks 13

Changes to the 230 kV transmission network being considered Install new static VAR compensator 742 642 542 Midway Line No. 2 732 632 532 Midway Line No. 3 722 622 Gates No. 1 500kV Switchyard 282 230kV Mesa 500kV Aux Aux Transformers 25kV Transformers 262 MODs MODs Morro Bay 212 Unit Unit 1 2 292 Startup 1-1 2-1 Transformers 12kV Startup Bus 374 384 Capacitor Banks 14

Changes to the 230 kV transmission network being considered

• Construct a new 230 kV line between Midway and Mesa substations

- Would support ability to feed area loads during planned upgrades or maintenance work on the 230 kV lines 15

Changes to the 230 kV transmission network being considered

• (Alternative) Add a new substation

- Upgraded 230 kV line from Midway (replaces 115 kV from Midway to Mesa)

- New 230 kV line from new substation to Mesa 16

December 29, 2009 LAR Summary

• Proposed revisions to UFSAR

- Specify 54 min to establish 500 kV backfeed, isolation of RCP seal cooling, and restoration of RCS makeup flow to meet GDC 17 requirements

• "Each of these circuits shall be designed to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuit, to assure that specified acceptable fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded"

- Added discussion on RCP seal performance

• Response to RAIs submitted November 22, 2011

- Addressed technical and licensing basis questions 17

Impacts to the December 29, 2009 LAR

• Withdraw existing LAR (Short term)

- Submit letter committing to new LAR when determination made

• Submit new LAR (Option 1) (Longer term)

- Similar to previous LAR with the following changes

- Credit for alternate AC diesel

- Credit for RCP shutdown seals

- Revisions to UFSAR

- Several other plants licensed with delayed access, including DCPP 18

Impacts to the December 29, 2009 LAR

• Submit new LAR for changes (Option 2) (Longer term)

- Two immediate offsite power circuits

- Generator Output Breakers

- Other alternative?

- Startup (230 kV) backup to Aux (500 kV)

- New load shed logic to facilitate single Startup transformer via unit crosstie for dual unit trip

- Revisions to UFSAR and TS / TS Bases 19

Summary

• PG&E will provide a commitment to resubmit a LAR prior or concurrent to withdrawal of the current request

• A new LAR would be submitted to address delayed circuit licensing basis and/or proposed modifications

• 230 kV transmission improvements will provide additional capacity / flexibility and address system load growth 20