State of the Plant Update Diablo Canyon Power Plant Jan Nimick Senior Director Nuclear Services PG&E Good afternoon. I’m Jan Nimick. I have addressed the committee on several occasions in different roles. Since last time I was here I have transitioned from Station Director to Senior Director, Nuclear Services with responsibility for Engineering, Strategic Projects, Security, Emergency Services, and the decommissioning at Humboldt Bay. Paula Gerfen is taking some well deserved vacation so I will be providing the State of the Plant update today. June 22, 2016

Overview Station Update Upcoming Key Station Activities In this presentation I will be discussing occurrences and performance at DCPP since last DCISC meeting and providing a preview of upcoming station activities.

Station Update Plant Operation Unit 1 and Unit 2 are safely operating at 100 percent power with Probabilistic Risk Assessments (PRAs) of “Green.” All NRC Performance Indicators (PI’s) are “Green.” Unit 1 has remained at 100% since completion of 1R19 refueling outage Successful completion of 2R19 refueling outage As you will see on the next slide our reliability has been strong since last DCISC meeting. 2R19 was completed within business plan and Unit 1 is on track for a breaker to breaker run. All NRC performance indicators are green and we are in column 1 of the reactor oversight program.

DAILY LOAD PROFILE (% MDC Net) Diablo Canyon Power Plant Generation History – Capacity Factor: Past 12 Months 2015 2016 U-1 Unit-1 2016 YTD Capacity Factor 102.11% 08/10 02:14 AUTO curtailment to 98% due to MSR PY-1728 tripping open. 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. 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. Unit 1 COD 05-07-1985 Total Plant 2016 YTD Capacity Factor 91.30% MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB U-2 What is explanation of higher than 100% power– need answer to this. On U-1 you can see the completion of 1R19 in November. In December we ramped both units to 25% power in response to condenser fouling arising from a wave/kelp event. From this power we can perform a controlled shutdown if conditions suddenly get worse and avoid tripping the reactor. We were able to clean the condensers using a “pick and dredge” methodology and maintain the units at power. Following the event and cleaning the condensers we returned both units to 100% power. On the right side of the slide you can see where we took Unit Two off line for 2R19. Unit-2 2016 YTD Capacity Factor 80.45% 08/14 01:01 Curtailed to 53% for Condenser Waterbox Pick & Dredge . 09/12 01:01 Curtailed to 50% for Circ Water Tunnel cleaning. 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. 0.1-Day Maintenance Outage 9/12 – 9/12 Electrical Insulator Cold-Wash Manual Turbine Trip. Reactor 17% Power. 05/01 00:01 Commenced 2R19 Refueling. 2R19 Refueling Outage In Progress Target Duration 33 Days Unit 2 COD 03-13-1986 Current Continuous Days On-line Unit-1 = 206.0 Unit-2 = 0 DAILY LOAD PROFILE (% MDC Net) Through May 2016 Source: Accenture Experience (Utility companies of various sizes in North America) 7

Station Update 2R19 Refueling Outage Highlights: Replaced “C” Low Pressure Turbine rotor Replaced Turbine building 500 kV standoff insulators Upgraded Intake travelling screens New seals on all Reactor Coolant Pumps (RCP) – design to support FLEX, National Fire Protection Association Standard 805 (NFPA 805) and Risk Based Tech Specs Replaced Reactor Coolant Pump (RCP) 2-1 rotor and stator RCP 2-3 10-year inspection and maintenance Completed modification to the Hot Shut Down Panel for NFPA 805 Reactor Vessel10-year inspection This slide shows the major jobs completed in 2R19. With the replacement of the RCP seals with accident tolerant seals we have fully implemented our FLEX requirements. That and the modifications to the HSDP support the transition to NFPA 805. Some more routine work was done to maintain our Reactor Coolant Pumps and Low Pressure C turbine rotor after ten years in operation.

Station Update Electric Power Reliability Initiative Unit 2 500 kV Turbine Building insulators replaced during 2R19 Ongoing improvements to 230kV & 500kV system Replacement of the 500 kV insulators is part of the continuing improvement in our electric system. Recall we were taking the units off line to cold wash the insulators. Now U-1 and U-2 are both using the insulators with the five year wash interval—though we plan to wash every outage. We also replaced air switches in the 500 kV yard.

Station Update Maintenance & Technical Training Program Accreditation Renewal Programs: Electrical Maintenance Instrument & Control Mechanical Maintenance Chemistry Radiation Protection Engineering Personnel Like colleges, nuclear power plants maintain accreditation of their training programs. The accreditation process involves a detailed review of the preceding four years of training materials, programs, interviews with instructors and students, and observations of training. The process culminates in an accrediting board in which a panel of industry experts provide review and challenge to the leadership team before deciding on accreditation outcome. In March the accrediting board renewed DCPP training program accreditation in the maintenance and technical programs.

Station Update Recent Inspections: In-Service Inspection Radiation Protection Inspection Target Set (Security related) Part 37 – Physical Protection of Nuclear Material In addition to the ongoing inspections by our on-site Resident Inspectors, we have had four recent inspections by the Nuclear Regular Commission Inspectors in specific areas. The in-service inspection is on how we monitor the material condition of our plant—things like ultra-sonic testing of piping welds and our flow accelerated corrosion monitoring program. The radiation protection inspection is on our compliance with regulations minimizing radiation dose received by workers and controlling radioactive materials. The target set inspection ensures we are correctly assessing our plant to understand vulnerabilities to physical attack. Target sets are a significant input to the physical security plan. The part 37 inspection relates to ensuring we are physically protecting nuclear materials from theft or sabotage. In all cases we completed the inspections without violations.

Baffle-Former Bolt Overview

Lower Core Support Plate Vessel Head Control Rod Guide Tube Outlet Nozzle Core Barrel Thermal Shield Former Plate Hold Down Spring Lower Core Support Plate Vessel Head Pressure Vessel Inlet Nozzle Upper Support Plate Lower Core Plate Bottom-Mounted Instrumentation Column Body Lower Support Column Body Upper Core Plate Baffle Plate Upper Support Column Source: Westinghouse

Baffle-former Bolt Locations Example Baffle-former Bolt Locations Thermal Shield Core Barrel Baffle Plate Former Plate Source: ML15331A264

Baffle to Core Barrel Bolt Former Baffle to Core Barrel Bolt Baffle Baffle Plate Edge Bolt Baffle to Former Bolt (Long & Short) Corner Edge Bracket Baffle to Former Bolt Source: ML15331A179

Station Update Baffle Bolts: To ensure the greatest margins of safety and fully understand conditions of baffle bolts: Participate in industry working group to share best practices, lessons learned, and develop additional guidance. Conduct ultrasonic testing of DCPP Unit 1 during the next refueling outage in 2017 Perform a thorough engineering analysis of the baffle former assembly. Through analysis and repair ensure a robust baffle former assembly Safety is and always will be the core value for PG&E and Diablo Canyon. Since 2010, when PG&E was first made aware of potential domestic baffle bolt failures, PG&E has been actively engaged with the industry through the EPRI Material Reliability Programs Committee. In light of the recent events at Indian Point and Salem Nuclear Power Plants, an industry working group of Pressurized Water Reactor plants was formed to share best practices, lessons learned, and develop additional guidance in coordination with the NRC to further mitigate this potential risk. While we wait for guidance from EPRI and technical information from the other facilities, PG&E has proactively planned to conduct ultrasonic testing of DCPP Unit 1 during the next refueling outage in 2017 that will ensure the greatest margins of safety and fully understand the conditions of the baffle former bolts. PG&E will fully comply with any NRC requirements as it relates to this issue. Unit 1 is susceptible – visual inspection 1R18 No indications or problems Full ultrasonic testing 1R20 Unit 2 is not susceptible – bolt material, up flow modification

Upcoming Key Station Activities Dry Cask Storage Campaign Summer 2016 NRC Problem Identification and Resolution Program Inspection June 2016 Mid-Cycle Self Assessment August 2016 NRC Triennial Force-on-Force Inspection Sept 2016 Mention End of Cycle meeting on evening of June 22 Source: Accenture Experience (Utility companies of various sizes in North America)

Thank You Jan Nimick