ML21174A085

Digital Modernization Project LAR Pre-submittal Meeting

ML21174A085
Person / Time
Site:	Limerick
Issue date:	06/23/2021
From:	Exelon Generation Co LLC, Exelon Nuclear
To:	Office of Nuclear Reactor Regulation
Marshall M
References
L-2020-LRM-0041
Download: ML21174A085 (52)

Text

Limerick Generating Station Digital Modernization Project LAR Pre-submittal Meeting NRC Pre-submittal Meeting June 29, 2021 Westinghouse Non-Proprietary Class 3

©2021 Westinghouse Electric Company LLC. All Rights Reserved GLIMM-RPS-PM-L1-000002, Revision 0 Page 2 of 53

Closed Portion 19 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 3 of 53

Architecture 20 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 4 of 53

Integrated Architecture a,c 21 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 5 of 53

Integrated Architecture The following changes to the Integrated Architecture presented during March's pre-submittal presentation.

PPS:

DCS:

a,c a,c 22 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 6 of 53

Sensor Reduction 23 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 7 of 53

Sensor Reductions

• Existing design implementation has multiple identical transmitters associated with input logic channels across the logic of all systems

• The PPS will evaluate Nuclear Boiler Instrumentation for the reduction of duplicated field transmitters

• The PPS will utilize an analyzed minimum set of transmitters to support diversity and redundancy

• The PPS will use four sensors to monitor each variable used for a reactor scram.

-These sensors may also monitor the same variable for an engineered safety feature actuation

-Analog measurements are converted to digital within each of four divisions

-When a measurement exceeds the setpoint, the output of the comparison results in a channel partial trip condition

-The partial trip condition is transmitted to the coincidence logic to form the signals that result in a safety feature actuation.

24 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 8 of 53

Sensor Reductions RPS, NSSSS, & ECCS Typical Architecture One Transmitter or Sensor into one Bistable Processing Cabinet Transmitter, Sensor, or Switch Logic for Each RPS, NSSSS, and ECCS Function Field Actuated Devices Main Control Room Interface Main Control Room Indication 25 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 9 of 53

Sensor Reductions - Existing RWL 2 Instrument Function Range Variable Leg Nozzle Nozzle Height Reference Leg Nozzle Nozzle Height LT-1(2)N081A NS4 WR N16D 366 N12D 599 LT-1(2)N081B NS4 WR N16A 366 N12A 599 LT-1(2)N081C NS4 WR N16B 366 N12B 599 LT-1(2)N081D NS4 WR N16C 366 N12C 599 LT-1(2)N091A CS(A)/RHR(A)/ADS(A), RCIC WR N16D 366 N12D 599 LT-1(2)N091B CS(B)/RHR(B), HPCI WR N16A 366 N12A 599 LT-1(2)N091F CS(B)/RHR(B), HPCI WR N16A 366 N12A 599 LT-1(2)N091C CS(C)/RHR(C)/ADS(C)

WR N16B 366 N12B 599 LT-1(2)N091G CS(C)/RHR(C)/ADS(C)

WR N16B 366 N12B 599 LT-1(2)N091D CS(D)/RHR(D), HPCI WR N16C 366 N12C 599 LT-1(2)N091H CS(D)/RHR(D), HPCI WR N16C 366 N12C 599 LT-1(2)N091E CS(A)/RHR(A)/ADS(A), RCIC WR N16D 366 N12D 599 LT-1(2)N097A RCIC WR N16D 366 N12D 599 LT-1(2)N097E RCIC WR N16D 366 N12D 599 LT-1(2)N402A RRCS WR N16D 366 N12D 599 LT-1(2)N402B RRCS WR N16A 366 N12A 599 LT-1(2)N402E RRCS WR N16B 366 N12B 599 LT-1(2)N402F RRCS WR N16C 366 N12C 599 LT-1(2)15A Wide Range Indication WR N16D 366 N12D 599 LT-1(2)15B Wide Range Indication WR N16A 366 N12A 599 Existing Reactor Pressure Vessel Level Instrumetnation for Reactor Water Level 2 26 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 10 of 53

Sensor Reductions - Proposed RWL 2 Instrument Function Range Variable Leg Nozzle Nozzle Height Reference Leg Nozzle Nozzle Height LT-1(2)N081A NS4, CS(A)/RHR(A)/ADS(A), RCIC, RRCS, Wide Range Indication WR N16D 366 N12D 599 LT-1(2)N081B NS4, CS(B)/RHR(B), HPCI, RRCS, Wide Range Indication WR N16A 366 N12A 599 LT-1(2)N081C NS4, CS(C)/RHR(C)/ADS(C), RRCS WR N16B 366 N12B 599 LT-1(2)N081D NS4, CS(D)/RHR(D), HPCI, RRCS WR N16C 366 N12C 599 LT-1(2)15A Wide Range Indication WR N16D 366 N12D 599 LT-1(2)15B Wide Range Indication WR N16A 366 N12A 599 Proposed Reactor Pressure Vessel Level Instrumetnation for Reactor Water Level 2 27 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 11 of 53

Existing Sensor Assignment RRCS (1A)

NSSSS (1A)

RPS (1A)

RRCS (1B)

NSSSS (2A)

RPS (2A)

RRCS (2B)

NSSSS (2B)

RPS (2B)

RRCS (2A)

NSSSS (1B)

RPS (1B) 0 90 180 270 ECCS DIV 1 ECCS DIV 3 ECCS DIV 4 ECCS DIV 2 Vessel Plan View: Separation Assignment With Respect To Vessel Instrumentation Only 28 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 12 of 53

PPS Sensor Assignment RRCS (Ch. 1)

NSSSS (Ch. 1)

RPS (Ch. 1)

RRCS (Ch. 3)

NSSSS (Ch. 3)

RPS (Ch. 3)

RRCS (Ch. 4)

NSSSS (Ch. 4)

RPS (Ch. 4)

RRCS (Ch. 2)

NSSSS (Ch. 2)

RPS (Ch. 2) 0 90 180 270 ECCS DIV 1 ECCS DIV 3 ECCS DIV 4 ECCS DIV 2 Vessel Plan View: Separation Assignment With Respect To Vessel Instrumentation Only 29 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 13 of 53

PPS Sensor Failure Impact Existing Systems PPS One out of Two Take Twice Logic Scheme Two out of Four Logic Scheme Two Channels could vote to scram while the other two changes do not vote resulting in half scram All channels provide votes to scram or actuate from bi-stable channels to RPS NSSSS & ECCS

- Ensures same scram initiator is required from more than one channel Existing scram actuation occurs if any single scram initiator occurs in one division combined with any single scram initiator in the other division Scram will no longer occur if the channels produce different scram initiators 30 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 14 of 53

Soft Controls 31 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 15 of 53

System Level Actuation Thread (Soft Controls) a,c 32 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 16 of 53

Component Level Actuation Thread (Soft Controls) a,c 33 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 17 of 53

Additional Component Level Actuations a,c 34 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 18 of 53

System and Component Level Actuation (Soft Controls)

Safety Display Software Implementation

• Robust software display design in accordance with the SPM for Important To Safety requirements (safety-related).

a,c 35 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 19 of 53

System, Component Level Actuation (Soft Controls)

Redundancy and Diagnostics

• Fault tolerant design:

- Redundant Safety Displays

• Diagnostics (Active Monitoring)

- Continuous monitoring of the Safety Display system software and hardware

- Continuous monitoring of the AC160 software and hardware modules

- Continuous monitoring of AF100 communications links

- Continuous monitoring of HSL communication links a,c 36 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 20 of 53

Diversity and Defense in Depth (D3) Approach 37 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 21 of 53

CIM Priority Module 38 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 22 of 53

Priority Module a,c 39 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 23 of 53

CIM and CCF a,c 40 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 24 of 53

Priority Module - Licensing Precedence The LAR will also describe the CIM's internal diversity attributes and the licensing precedence of the Wolf Creek MSFIS application that was reviewed and approved by the NRC (ML# 0906103170)

- Rigorous Design Process Includes Independent Verification and Validation Reviewed by NRC as part of AP1000 PMS a,c 41 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 25 of 53

Priority Module - Comparison of Design Features

• Rigorous Design Process

- Includes Independent Verification and Validation

- Reviewed as part of AP1000 PMS a,c 42 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 26 of 53

D3 CCF Coping Analysis 43 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 27 of 53

Presentation of D3 CCF Coping Examples Four D3 CCF coping examples are presented to demonstrate the approach for a D3 CCF Analysis.

These examples correspond to the following LGS UFSAR Chapter 15 events:

- Chapter 15.1.4 Inadvertent Main Steam Relief Valve Opening

- Chapter 15.2.3 Turbine Trip Without Bypass

- Chapter 15.2.7 Loss of Feedwater

- Chapter 15.6.5 LOCA Inside Containment 44 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 28 of 53

Presentation of D3 CCF Coping Examples (cont.)

a,c 45 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 29 of 53

Presentation of D3 CCF Coping Examples (cont.)

a,c 46 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 30 of 53

Four Examples of D3 CCF Coping Analysis Breakout 47 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 31 of 53

D3 CCF Coping Analysis Assumptions a,c 48 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 32 of 53

Preliminary Summary of Required Diverse Actuations a,c 49 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 33 of 53

Spurious Actuation 50 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 34 of 53

Spurious Actuation Due to a CCF BTP 7-19: Spurious Actuation is an initiating event a,c 51 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 35 of 53

Spurious Actuation Due to a CCF a,c 52 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 36 of 53

SECY 93-087 Position 4 Controls Discussion 53 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 37 of 53

Position 4 Diverse Manual Controls

• Position 4:

A set of displays and controls located in the main control room shall be provided for manual, system-level actuation of critical safety functions and monitoring of parameters that support the safety functions. The displays and controls shall be independent and diverse from the safety computer system identified in items 1 and 3 above (those identified from D3 coping).

• SECY-93-0087 identified the following critical safety functions to be managed from the MCR in accordance with Position 4:

-Reactivity control

-Core heat removal

-Reactor coolant inventory

-Containment isolation

-Containment integrity 54 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 38 of 53

Summary for Position 4 Controls a,c 55 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 39 of 53

Summary of Diverse Containment Isolation (Position 4) a,c 56 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 40 of 53

SECY 93-087 Position 4 Display Discussion 57 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 41 of 53

SECY 93-087 Position 4 Displays Existing LGS Safety Parameter Display System (SPDS) can be credited for SECY-93-087 Position 4 displays:

• SPDS part of the Plant Process Computer (PPC)

• No changes anticipated to SPDS/PPC by the proposed modification

• SPDS meets the BTP 7-19 Position 4 Acceptance Criteria for Displays

• SPDS monitors and indicates the critical safety parameters of reactivity control, reactor core cooling and heat removal from the primary system, reactor coolant system integrity, radioactivity control, and containment conditions

• LAR and LTR will demonstrate SPDS is independent and diverse from the proposed PPS 58 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 42 of 53

SECY 93-087 Position 4 Displays (cont'd)

Existing LGS Safety Parameter Display System (SPDS) can be credited for SECY-93-087 Position 4 displays:

• SECY-93-087 Position 4 allows use of non-safety related equipment with adequate reliability and quality

• SPDS reliability established through:

-Redundant and validated signals

-On-line failure diagnostics

-Processor backup

-Use of quality components

• It will be demonstrated that the SPDS meets the BTP 7-19 Rev. 8 quality requirements

• SPDS designed using human factors engineering principles 59 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 43 of 53

Software Design Process for RRCS & DPS 60 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 44 of 53

Software Design Process for RRCS & DPS a,c 61 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 45 of 53

Regulatory Guide 1.97 Discussion 62 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 46 of 53

Regulatory Guide 1.97 Impacts

• Implemented on safety and non-safety devices (depends on the variable category)

• Impacted variables to be brought into PPS (fully qualified system)

-PPS is available post-design basis accident (LOCA, SSE, OBE, LOOP, etc.)

• Not all RG 1.97 variables will be brought into PPS - only those on the impacted MCR panels

• Limerick does not credit SPDS for Reg Guide 1.97 information

• Note that all current field sensors will be retained, i.e., no consolidation of RG 1.97 field sensors is planned

• Proposed change impacts display devices only 63 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 47 of 53

Next Pre-submittal Meeting 64 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 48 of 53

Topic Areas for next Pre-submittal Meeting

• MCR Human-System Interface and Human Factors Engineering

• VOP update

• Project status update

• Diversity and Defense in Depth (continued)

• Follow-up items identified from June 29 meeting 65 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 49 of 53

Closing Comments 66 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 50 of 53

Acronyms Acronym Definition ADS Automatic Depressurization System AER Auxiliary Equipment Room AOI Advant Ovation Interface ARI Alternate Rod Injection ARP Alternate Review Process ASAI Application Specific Action Item ATWS Anticipated Transient Without Scram BPL Bistable Protection Logic BWR Boiling Water Reactor CAP Corrective Action Program CCF Common Cause Failure CDO Central Design Organization CRDR Control Room Design Review CIM Component Interface Module CRADA Cooperative Research and Development Agreement CPU Central Processing Unit CS Core Spray D3 Defense-in-Depth and Diversity DCS Distributed Control System DDS Data Display System DEHC Digital Electro-Hydraulic Control DPS Diverse Protection System ECCS Emergency Core Cooling System EDG Emergency Diesel Generator EOP Emergency Operating Procedures EQSR Equipment Qualification Summary Report ESFAS Emergency Safety Function Actuation System 67 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 51 of 53

Acronyms (cont'd)

Acronym Definition FMEA Failure Modes and Effects Analysis FMEDA Failure Modes, Diagnostics, and Effects Analysis FPGA Field Programmable Gate Array FSAR Final Safety Analysis Report HFE Human Factors Engineering HPCI High Pressure Core Injection HSL High Speed Link IBR Incorporated by Reference ILP Integrated Logic Processor INL Idaho National Labs I/O Input/Output ITAAC Inspection, Test, Analysis, and Acceptance Criteria LAR License Amendment Request LCL Local Coincidence Logic LGS Limerick Generating Station LOOP Loss of Offsite Power LPCI Low Pressure Coolant Injection LRA Licensee Required Action LTR Licensing Technical Report MCR Main Control Room MPB Manual Partial Bypass MPT Manual Partial Trip MSFIS Main Steam and Feedwater Isolation System MSIV Main Steam Isolation Valve NSR Nonsafety-related NSSSS Nuclear Steam Supply Shutoff System OBE Operating basis earthquake PC Personal Computer PMS Protection and Monitoring System PPC Plant Process Computer 68 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 52 of 53

Acronyms (cont'd)

Acronym Definition PPS Plant Protection System PSAI Plant Specific Action Items QA Quality Assurance QMP Quality Management Plan RAI Request for Additional Information RCIC Reactor Core Isolation Cooling RHR Residual Heat Removal RPS Reactor Protection System RPV Reactor Pressure Vessel RRCS Redundant Reactivity Control System RWCU Reactor Water Cleanup SER Safety Evaluation Report SFMS Supplier Fundamental Management System SDC Shutdown Cooling SDV Scram discharge volume SLCS Standby Liquid Control System SPDS Safety Parameter Display System SPM Software Program Manual SR Safety-related SRNC Safety Remote Node Controller SRV Safety Relief Valve SSE Safe Shutdown Earthquake SyDS System Design Specification SyRS System Requirements Specification TS Technical Specifications TU Trip Unit UFSAR Updated Final Safety Analysis Report VOP Vendor Oversight Plan WEC Westinghouse AP1000 is a trademark or registered trademark of Westinghouse Electric Company LLC, its affiliates and/or its subsidiaries in the United States of America and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited. Other names may be trademarks of their respective owners.

69 Westinghouse Non-Proprietary Class 3 GLIMM-RPS-PM-L1-000002, Revision 0 Page 53 of 53