Diablo Canyon Power Plant: State of the Plant Update 4/15/2018 Diablo Canyon Power Plant: State of the Plant Update Paula Gerfen Station Director October 20, 2016

Overview Station Update Upcoming Key Station Activities

Station Update Plant Operation Unit 2 is safely operating at 100 percent power with Probabilistic Risk Assessments (PRAs) of “Green.” Unit 1 is currently curtailed at 50 percent power for a planned tunnel cleaning All NRC Performance Indicators (PIs) are “Green.” 2016 Generation Capacity Factor (year to date) Unit 1 = 102.1% Unit 2 = 88.1%   Total Plant = 95.1%  

Station Update Plant Operation Unit 2 curtailed to 75 percent power during performance of STP R-1A to resolve a misaligned control rod Unit 2 went off-line for 2R19 Refueling Outage May 2016   

Current Continuous Days On-line DAILY LOAD PROFILE (% MDC Net) Generation History – Capacity Factor: Past 4 Months 2016 % U-1 Unit 1 COD 05-07-1985 Unit-1 2016 YTD Capacity Factor 102.05% Total Plant 2016 YTD Capacity Factor 95.09% JUNE JULY AUGUST SEPTEMBER U-2 % Unit 2 COD 03-13-1986 08/04 11:37 Manual curtailment to 75% during STP R-1A to resolve misaligned control rod. Unit-2 2016 YTD Capacity Factor 88.10% 2R19 Refueling Outage 5/1/16 – 6/2/16 32.6 Days 06/02 14:47 Paralleled to the grid. 06/08 04:03 Full power on the grid. Current Continuous Days On-line Unit-1 = 328.0 Unit-2 = 120.4 DAILY LOAD PROFILE (% MDC Net) Through: SEP 2016 Source: Accenture Experience (Utility companies of various sizes in North America) 7

Current Continuous Days On-line DAILY LOAD PROFILE (% MDC Net) Generation History – Capacity Factor: Past 12 Months 2015 2016 % U-1 Unit 1 COD 05-07-1985 12/11 16:30 Curtailed to 25% to clean debris from Intake and Main Condenser due to high seas. 04/22 10:01 Curtailed to 88% for STP M-21C Main Steam Isolation Valve Testing. 10/04 00:01 Commenced 1R19 Refueling. Unit-1 2016 YTD Capacity Factor 102.05% 1R19 Refueling Outage 10/04/15 – 11/07/15 Actual 35 Days 11/07 23:21 Paralleled to the grid. 11/12 18:38 Full power on the grid. Total Plant 2016 YTD Capacity Factor 95.09% JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN U-2 % Unit 2 COD 03-13-1986 12/11 23:43 Curtailed to 25% to clean debris from Intake and Main Condenser due to high seas. 04/30 14:58 Commenced ramp-down to begin 2R19 Refueling Outage. 08/04 11:37 Manual curtailment to 75% during STP R-1A to resolve misaligned control rod. Unit-2 2016 YTD Capacity Factor 88.10% 05/01 00:01 Commenced 2R19 Refueling. 06/02 14:47 Paralleled to the grid. 06/08 04:03 Full power on the grid. 2R19 Refueling Outage 5/1/16 – 6/2/16 32.6 Days Current Continuous Days On-line Unit-1 = 328.0 Unit-2 = 120.4 DAILY LOAD PROFILE (% MDC Net) Through: SEP 2016 Source: Accenture Experience (Utility companies of various sizes in North America) 7

Station Update Completed 2R19 Refueling Outage Highlights of work performed: Replaced “C” Low Pressure Turbine Replaced 500kV Turbine building standoff insulators Upgraded Intake travelling screens New seals on all Reactor Coolant Pumps (RCP) – design to support FLEX, NFPA 805 and risk managed Tech Specs Replaced RCP 2-1 rotor and stator RCP 2-3 10 year maintenance Modification to the Hot Shut Down Panel for NFPA 805 completed Core Barrel 10 year inspection NFPA 805 HSDP modifications and CFCU 2-5 cooler replacement Reactor coolant pump Thermal Seals – all 4 Reactor coolant pump 2-1 motor overhaul Reactor Vessel inspections RCCA guide card inspection 500 kV disconnect switch replacements Replace 500 kV dead end insulators 230 kV switchyard cold wash Vital battery and DC distribution panel 2-3 replacement 480 V vital bus H breaker replacements "C" LP turbine replacement 11 feedwater heater inspections Steam Generator sludge lance, and FOSAR 5 intake travelling screen overhauls

Station Update 1R20 Implementation Baffle Bolting: Baffle bolt damage found at other plants Unit 1 – Visual inspection 1R18 No indications or problems Full ultrasonic testing 1R20 Planning for the replacement of approximately 120 bolts during 1R20 Unit 2 is not susceptible – bolt material, up flow modification This is a known industry issue The Outage Management Team has discussed the Scope, Schedule, and Cost of 1R20 based upon the implementation of the Reactor Cavity Seal and the inspection and possible replacement of some Core Barrel Baffle Bolting.  Based on reviewing a number of options a baseline duration of 65 Days is needed to safely and methodically implement an outage of this complexity.  This duration is based on the assumption that the station will replace approximately 150 bolts in an 18 day window. 

Upcoming Station Activities Preview NRC Triennial Fire Inspection October 2016 NRC Radiation Safety Inspection October 2016 NRC Initial Operator Exams October 2016 NRC EP Performance/Exercise Inspection November 2016 NRC Security Access Control Inspection February 2017 NRC Biennial Requal Inspection April 2017 1R20 Refueling Outage April 2017 Source: Accenture Experience (Utility companies of various sizes in North America)

Thank you Paula Gerfen email@pge.com 10