ML13024A405
| 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
1 Diablo Canyon Power Plant Offsite Power January 24, 2013 Washington DC Pacific Gas and Electric Company Al Bates Gregg Reimers Michael Richardson Jeff Summy
2 Diablo Canyon Power Plant
3 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
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
5 Overview of Grid Interface 5
Startup Bus MODs MODs 212 292 384 374 Capacitor Banks Midway Line No. 2 Midway Line No. 3 Gates No. 1 742 732 722 642 632 622 542 532 500kV Switchyard 500kV 25kV Aux Transformers Aux Transformers Unit 1
Unit 2
Mesa Morro Bay 230kV Startup Transformers 12kV 1-1 2-1 282 262
Overview of Offsite Power Circuits 6
52HG15 52HD14 52HD15 52HE2 52HE3 52HF14 52HG14 52HH14 52HF13 52HG13 52HH13 52VU14 52VU12 52VU24 52VU11 500 kV Switchyard Switchyard 230 kV 212 632 532 SU Trans 1-1 2-1 12 kv SU Bus Unit 1 12 kv SU Bus Unit 2 SU Trans 1-2 Aux Trans 1-2 Aux Trans 1-1 MOD Main Trans Main Gen 4 kV Bus E 4 kV Bus D 4 kV Bus F 4 kV Bus G 4 kV Bus H DG 11 DG 12 DG 13 LTC LTC 211-2 211-1
Issues Being Addressed
- 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
8 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
9 Generator output breaker with 500 kV as an immediate source of offsite power Changes to the Auxiliary offsite power circuit being considered Startup Bus 212 292 384 374 Capacitor Banks Midway Line No. 2 Midway Line No. 3 Gates No. 1 742 732 722 642 632 622 542 532 500kV Switchyard 500kV 25kV Aux Transformers Aux Transformers Unit 1
Unit 2
Mesa Morro Bay 230kV Startup Transformers 12kV 1-1 2-1 282 262
10 Changes to the Auxiliary offsite power circuit being considered
11 Changes to the Auxiliary offsite power circuit being considered
12
- 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 Potential addition of a 500/230kV transformer bank
Potential addition of a 500/230kV transformer bank 13 Startup Bus MODs MODs 212 292 384 374 Capacitor Banks Midway Line No. 2 Midway Line No. 3 Gates No. 1 742 732 722 642 632 622 542 532 500kV Switchyard 500kV 25kV Aux Transformers Aux Transformers Unit 1
Unit 2
Mesa Morro Bay 230kV Startup Transformers 12kV 1-1 2-1 282 262
14 Changes to the 230 kV transmission network being considered Install new static VAR compensator Startup Bus MODs MODs 212 292 384 374 Capacitor Banks Midway Line No. 2 Midway Line No. 3 Gates No. 1 742 732 722 642 632 622 542 532 500kV Switchyard 500kV 25kV Aux Transformers Aux Transformers Unit 1
Unit 2
Mesa Morro Bay 230kV Startup Transformers 12kV 1-1 2-1 282 262
15 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
16 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
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
18 18 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
19 19 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
20 20 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