ML20160A053
| ML20160A053 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/08/2020 |
| From: | Exelon Corp |
| To: | Office of Nuclear Reactor Regulation |
| Marshall M, NRR/DORL/LPL, 415-2871 | |
| References | |
| EPID L-2020-LRM-0041 | |
| Download: ML20160A053 (32) | |
Text
Limerick Generating Station Digital Modernization Project LAR Presubmittal Meeting NRC Presubmittal Meeting Telecon June 12, 2020
Agenda / Opening Remarks
- Introductions
- Expected outcome for meeting
- Fee Waiver
- Project description
- Current and Proposed Architecture
- Use of Alternate Review Process (ARP)
- NRC Lessons learned - digital projects
- Closing Remarks 1
Introductions - Project Team Susan Korn, VP Project Management Steve Hesse, Project Director Jerry Segner, Principal Project Manager Shannon Rafferty-Czincila, Licensing Director Dave Helker, Licensing Manager Frank Mascitelli, Licensing Lead Bob Dickinson, LGS Regulatory Assurance Manager George Budock, LGS Regulatory Assurance Pareez Golub, Digital Licensing SME Craig Myers, LGS Operations Sagar Patel LGS Operations 2
Introductions - Engineering Elliott Flick, VP Centralized Design Organization Vikram Shah, Director CDO John Connelly, I&C Analytical Branch Manager Mark Samselski, Lead Responsible Engineer George Bonanni, I&C Responsible Engineer Scott Schumacher, Systems Engineering Farad Zaman, Systems Engineering 3
Expected Outcome of Meeting 4
NRC has an overview of project scope NRC has understanding of the current project milestones Exelon gains insights on NRC lessons learned from previous digital License Amendment Requests (LAR)
Exelon - DOE Partnership
- Historically, industry has struggled with modernization of first-echelon safety systems
- NRC issuance of Digital Instrumentation and Controls Interim Staff Guidance #06 (DI&C-ISG-06), Revision 2, Licensing Process, addressed perceived regulatory barriers
- In 2019 a public / private partnership was formed through the Light Water Reactor Sustainability Program (LWRS) to research viability of modernization of safety systems 5
Exelon - DOE Partnership
- Research produced two key products - Technical Requirements Specification (TRS) and License Amendment Request framework document
- LAR Framework Document
- Vendor-independent LAR framework document created in a format consistent with the DI&C-ISG-06 ARP
- Document is a starting point and will be refined as Limericks design further matures
- LAR framework will be made available through LWRS as a starting point for other licensees 6
Intent to Request NRC Fee Waiver
- Request fee waiver under 10 CFR 170.11(b)
- LAR will exercise all portions of the DI&C-ISG-06 Alternate Review Process for a large-scale protection system replacement
- Learnings from LGS execution of ARP will be used to support US operating fleet digital protection system modernization efforts
- First-echelon safety system digitization is critical to US operating fleet sustainability 7
Intent to Request NRC Fee Waiver
- LAR will utilize standardized industry digital design guidance - pilot project for Exelon EPRI Digital Engineering Guide (DEG) and NISP-EN-04, Standard Digital Engineering Process
- NEI 06-04, License Amendment Request Guidance, Appendices F and G
Intent to Request NRC Fee Waiver 9
DI&C-ISG-06 R2, Enclosure B, Information Provided in Support of a License Amendment Request for a Digital Instrumentation and Control Modification
10 Project Overview
Project Scope Replacement of first-echelon Safety-related Systems:
Reactor Protection System (RPS)
Nuclear Steam Supply Shutoff System (NSSSS)
Emergency Core Cooling System (ECCS) 11 Project scope is draft for NRC discussion and planning purposes. Final scope to be determined by Exelon by August 2020.
Project Benefits Increase in plant safety Reduction in human error potential Increase in operational decision-making accuracy and speed Higher full system availability Enhanced self-diagnostic capabilities Increase in reliability Elimination of spurious half scrams Elimination of single component vulnerabilities Reduction of obsolete components Elimination of 1800 safety significant components 12
Project Benefits Increase in quality Operations and Maintenance Improved availability, spectrum and quality of MCR information Improved configuration control Continuous self-testing and diagnostics of all trains of safety functions Reduced administrative overhead Reduced operator burden through automation Supports workforce of the future 13
Project Milestones NRC presubmittal meeting June 2020 Vendor selection July 2020 Letter of Intent July 2020 Fee waiver request letter July 2020 Next NRC presubmittal mtg Oct 2020 PPS LAR submittal June 2021 14
15 Current Architecture
Current Architecture - Main Control Room 16 Unit 1 Unit 2 U1 - 647 -HPCI, 648
-RICI, 601 Reactor/Containment Cooling and Isolation Vertical Boards U2 - 647 -HPCI, 648 -
RICI, 601 Reactor/Containment Cooling and Isolation Vertical Boards U1 - 603 Mode Switch and Rx Scram Buttons Console U2 - 603 Mode Switch and Rx Scram Buttons Console
Current Architecture - Auxiliary Equipment Room Unit 1 Unit 2 C618 C641 C613 C620 C644 C622 C618 C641 C613 C620 C644 C622 C631 C628 C621 C640 C617 C631 C628 C621 C640 C617 C609 C609 C611 C633 C646 C611 C633 C646 C623 C623
Current Architecture - RPS, NSSSS, ECCS
- Commonalities between systems
- Detector trip unit relay
- Operator interface in Main Control Room
- Logic resides in Aux Equipment Room
- Up to 8 instrument channels to support 4 divisions of logic
- Each system installed separately
- Cohabitation of some logic and detector signals 18
Current Architecture - RPS
- RPS
- Purpose: cause rapid plant shutdown
- Logic
-Each division has two channels
-Two divisions
-One out of two taken twice
-Fail safe
- Two safeguard power supplies 19
- NSSSS
- Purpose: Isolate primary containment
- Logic
-One or two channels per division
-Up to four divisions
-Variable, purpose specific logic
-Fail safe
-Interposing relays
- Two safeguard power supplies
Current Architecture - ECCS
- From left to right
- Core Spray (CS) Div. 1 and 3
- Residual Heat Removal System (RHR) Divisions 1 and 3
- NSSSS interface
- Core Spray Divisions 2 and 4
- RHR Divisions 2 and 4
- Reactor Core Isolation Cooling (RCIC) System
- High Pressure Core Injection (HPCI) System 20
Current Architecture - ECCS
- Two instrument channels per division
- All use 1 out of 2 logic
- ADS is two divisions
- Four divisions of Low Pressure Injection
- Divisional Diesel backed safeguard power
22 Proposed Architecture
Proposed Architecture - Plant Protection System (PPS)
- New system comprised of vendors standard platform
- Vendor platform will have prior NRC approval
- New system retains similar architecture
- Replaces the existing four divisions of bi-stable analog trip units in RPS, NSSSS, and ECCS with separate, independent, channel functions in application software
- Functions retain their existing logic separation
- Clear differentiation between channels, electrical divisions, and mechanical trains 23 Digital platform vendor selection in progress
Current vs. Proposed Architecture - Main Control Room 24
- MCR Human Machine Interface (HMI) will be video display units (VDUs)
- Eliminate the separate lamp-based trip, status, and bypass indicators (BISI) and provide the information on the VDUs.
- Select manual controls are retained (e.g., Reactor SCRAM) with soft controls added for division-level systems initiation and component control
Current vs. Proposed Architecture - Auxiliary Equipment Room 25 Video Display Video Displa y
Video Display Video Displa y
To Main Control Room To Main Control Room To Main Control Room To Main Control Room To Main Control Room
Proposed Architecture - Plant Protection System (PPS)
- One-way redundant fiber optic cabling from each safety channel and safety division to the non-safety related DCS data backbone, which allows diverse display of all RPS, NSSSS, ECCS data and status by DCS/Plant Process Computer displays and annunciation.
- Ability to bypass one of the four channels for maintenance, while still retaining 2 out of 3 twice voting in the divisions
- Eliminate or reduction of Technical Specification (TS)
Surveillance Requirements (SR) through crediting platform and application self-diagnostics 26
Proposed Architecture - Plant Protection System (PPS)
- Use the existing, retained field input wiring terminals, hardwired connections to the new PPS (RPS, NSSSS, and ECCS) inputs and outputs
- To the extent practicable, eliminate redundant transmitters and bi-stables
- Ensure that the platform design does not preclude future migration of other safety systems and safety functions to the platform 27
28 LAR Use of Alternate Review Process (ARP)
Use of DI&C-ISG-06 Alternate Review Process
- Several presubmittal meetings to be planned to discuss full list of topics provided by NRC and included in DI&C-ISG-06
- Comprehensive Vendor Oversight Plan (VOP) will be developed for project - VOP Summary will be included in LAR
- NRC-approved platform used / applicability of application software development process (if NRC approved) to proposed software design, implementation, and test
- Regulatory commitments provided for:
- For uncompleted Plant Specific Action Items (PSAIs) included in LAR
- For later lifecycle design activities not governed by other regulatory processes 29
Next Presubmittal Meeting Topics
- Key design concepts, including the four fundamental design principles
- Replacement modification scope
- Comparison of the existing architecture and the proposed architecture
- D3 assessment strategy
- Identified significant deviations from a referenced NRC-approved topical report (if applicable)
- Strategy for changing TS SRs based on self-diagnostics
- Impact on Accident Analyses (e.g. response time testing)
- Human Factors considerations 30
31 NRC Lessons Learned Digital Projects