ML17240A338

Non-Safety Related Digital Feedwater and Amsac/Dss Control Systems Replacement Project Presentation

ML17240A338
Person / Time
Site:	Prairie Island
Issue date:	08/30/2017
From:	Northern States Power Co, Xcel Energy
To:	Robert Kuntz Plant Licensing Branch III
Kuntz R, NRR/DORL/LPLIII
References
Download: ML17240A338 (31)

Text

Non-Safety Related Digital Feedwater and AMSAC/DSS Control Systems Replacement Project Xcel Energy Prairie Island Nuclear Generating Plant 8-30-2017 1

Agenda

• Introductions

• Meeting Purpose

• Project Overview

• 10 CFR 50.59 Assessment

• Future Actions

• Summary

• Feedback and Questions 2

Meeting Purpose

• Outline project scope, design, and licensing basis supporting the digital FW and AMSAC/DSS control system change

• Discuss the preliminary 10 CFR 50.59 assessments and conclusions

• Discuss possible future interaction with the NRC staff 3

Project Overview

• Current System

- Westinghouse WDPF System

• Digital Technology

• Installed WDPF FWCS and AMSAC in 1989/1990

• Modified AMSAC and installed DSS Feature in 1998/1999

• Non-Safety Related Distributed Control System (DCS) 4

Project Overview

• Project Drivers

- Obsolescence

• WDPF Systems are 28 years old

- Parts not manufactured since 2002

- Vendor technical support ends in 2017

• Recent Hardware Issues

• Current system not suitable for plant life

- Unit 1 operation to 2033

- Unit 2 operation to 2034

- Long term operating and maintenance strategy

• Common platform with demonstrated history of reliable operation 5

Project Overview

• Timeline

- 2015-2016: Preliminary Engineering Phase

• Multidiscipline team

• Many team members from original WDPF team

- 2017: 10 CFR 50.59 Assessment Phase

- 2018: Detailed Design Phase

- 2019-2020: Installation Phase

• In service dates:

- Unit 2 - 2019

- Unit 1 - 2020 6

Project Overview

• Project Scope

- Replace existing DCS

• Digital to digital - Ovation

• WDPF to Ovation

- Next generation of platform

- Same OEM

- Upgrade FW Reg Valve Controls

• Analog to digital - DVC 7

Project Overview

• Project Design Principles

- Mitigate obsolescence

- Improve equipment reliability

- Eliminate SPVs and transient initiators

- Use well vetted, common platform with demonstrated history

- Design system hardware and software within the bounds of current design and licensing basis

- Use industry standard methods for design and testing

- Use a multi-layer testing approach through fabrication, installation, and commissioning

- Design, test, and install system to minimize outage impact 8

Project Overview 9

Project Overview

• Project Scope Detail

- Install Ovation DCS:

• FW Control System (SGWLC)

• AMSAC/DSS System

• Control System Infrastructure

- Modify Main Control Board Operator Interface:

• Retain operator manual controls

• Move some indications to new graphic display

- Modify FW Control Valve field devices:

• Replace FW Reg valve controls with dual redundant digital positioners on Main Control Valves and single digital positioner on Bypass Control Valves

- Modify Simulator 10

Project Overview

• Project Scope Detail (contd)

- Improve Equipment Reliability

• Increase redundancy

• Eliminate at least 16 SPVs (8 per unit)

- Functional Control Enhancements

• Reduce operator burden

• More fault tolerant

• Improve FW Control strategies

• Improve time response 11

10 CFR 50.59 Assessment

• FW Design & Licensing Basis

• AMSAC/DSS Design & Licensing Basis

• Assessment Approach

• Qualitative Assessment

• 10 CFR 50.59 Criteria

• Preliminary 10 CFR 50.59 Overall Conclusion 12

10 CFR 50.59 Assessment

• FW Design & Licensing Basis

- USAR described FWCS & Control Valve Design Functions:

• Provide FW flow to SGs for RCS heat removal during normal operation

• Provide SG Program Level Control during normal operation

• Prevent control and protection interaction with Median Signal Select (MSS) for NR SG level

• Valves provide isolation of FW flow to SGs

- Licensing

• Steam Flow/FW Flow mismatch trip elimination

- USAR described Failures and Accident Analysis 13

10 CFR 50.59 Assessment

• AMSAC/DSS Design & Licensing Basis

- Design Function: Satisfy 10 CFR 50.62

• AMSAC Actuation: Turbine Trip and AFW actuation

• DSS Actuation: Remove power to the control rods

- Licensing

• Installed WDPF AMSAC to meet requirements of 10 CFR 50.62

• Modified AMSAC logic and added DSS feature

- USAR described Failures and Accident Analysis 14

10 CFR 50.59 Assessment

• Assessment Approach

- Use current regulatory requirements & guidance

• NEI 96-07, Rev 1, endorsed by NRC RG 1.187

• NEI 01-01 (including Appendix A) endorsed by NRC RIS 2002-22

• NRC IN 2010-10

- Monitoring ongoing NEI/NRC efforts

- 10 CFR 50.59 screening considerations (NEI 01-01 Section 4.3):

• Software considerations

• Functional segmentation

• Time response

• Human System Interface

• Safety to Non-Safety Interface

- NEI 01-01 drives conservative conclusion to screen in 15

10 CFR 50.59 Assessment

• Assessment Approach (contd)

- 10 CFR 50.59 Evaluation Considerations (NEI 01-01 Section 4.4)

• Same as screening considerations

• Qualitative Assessment is key to addressing Criterion 1, 2, 5, and 6 of 10 CFR 50.59 16

10 CFR 50.59 Assessment

• Assessment Approach (contd)

- NEI 01-01, Section 5.3.1, Factors that Affect Dependability

• The ability to provide reasonable assurance that an upgrade will exhibit sufficient dependability is a key element of 10 CFR 50.59 evaluations

- Qualitative Assessment characteristics:

• System design features

• System design development and quality processes

• Operating history 17

10 CFR 50.59 Assessment

• Qualitative Assessment - Design Features

- Design Features to support low likelihood of failure (examples):

• Isolation Devices

• Redundancy

• Architectural assignments

• Segmentation

• Self Diagnostics

• Failure states

• Existing Manual Controls

- Susceptibility Analysis

• Hardware Failures

• Environmental

• Design Defects

• Operator or Maintenance Errors 18

10 CFR 50.59 Assessment

• Qualitative Assessment - Design Development and Quality Processes

- Design specification provides requirements for design, fabrication, documentation, testing, and delivery

- Specification and Westinghouse design development processes based upon industry standards

- Specification requires multi-layer testing approach through fabrication, installation, and commissioning 19

10 CFR 50.59 Assessment

• Qualitative Assessment - Operating History

- Ovation Experience

• More than 100 Ovation nuclear systems deployed

• Variety of nuclear applications worldwide

• Greater than 500 Rx years of OE

- Fisher DVC Experience

• Over 700,000 sold

• Over 7 years

- OE Research 20

10 CFR 50.59 Assessment

• Qualitative Assessment Preliminary Conclusions

- Will demonstrate dependability and low likelihood of failure:

• Required design features maintained and no new failure results

• Design development and quality processes being applied

• Operating history is strong 21

10 CFR 50.59 Assessment

• 10 CFR 50.59 Criteria

- Expected 10 CFR 50.59 Criteria 1, 2, 5, and 6 conclusions based on preliminary Qualitative Assessment and preliminary design work:

• No more than a minimal increase in frequency of an accident

• No more than a minimal increase in likelihood of malfunction

• No possibility of an accident of a different type

• No possibility of a malfunction with a different result 22

10 CFR 50.59 Assessment

• 10 CFR 50.59 Criteria (contd)

- Other 10 CFR 50.59 Criteria:

• Criteria 3 & 4:

- Systems do not initiate new failures or malfunctions

- Radiological consequences are not evaluated for these events

• Criterion 7:

- Systems do not impact any critical inputs credited in the Safety Analysis for fission product barriers

- Change will not exceed or alter a fission product barrier design basis limit

• Criterion 8:

- Change does not constitute, involve or modify a method of evaluation described in the USAR 23

10 CFR 50.59 Assessment

• Preliminary 10 CFR 50.59 Overall Conclusion

- Screens in for evaluation

- Would not require prior NRC approval

- Perform change under 10 CFR 50.59 24

Future Actions

• Xcel Next Steps

- Proceed with detailed design

- 10 CFR 50.59 evaluation sufficiently complete in 3rd Quarter 2018

- Opportunity for additional learning with new guidance

- Timing to accommodate project installation

• Unit 2 - 2019

• Unit 1 - 2020 25

Summary

• Described the project scope, design, and licensing basis supporting the digital FW and AMSAC/DSS control system change

• Discussed the preliminary 10 CFR 50.59 assessment and conclusions

• Outlined next steps and possible future interaction with the NRC staff 26

Feedback and Questions

?

27

Acronyms

• AFW - Auxiliary Feedwater

• AMSAC - ATWS Mitigating System Actuation Circuitry

• AOO - Anticipated Operational Occurrences

• ATWS - Anticipated Transient Without SCRAM

• BFRV - Bypass Feedwater Regulating Valve

• CCF - Common Cause Failure

• CFR - Code of Federal Regulations

• CR - Control Room

• DCS - Distributed Control System

• DSS - Diverse Scram System

• DVC - Digital Valve Controller

• FW - Feedwater 28

Acronyms

• FWCS - Feedwater Control System

• HSI - Human System Interface

• IN - Information Notice

• I/O - Input/Output

• I/P - Current to Pressure Converter

• LVDT - Linear Variable Differential Transformer

• MFRV - Main FW Regulating Valve

• M/A - Manual/Automatic Control Station

• M/L - Manual Loading Station

• M/P - Motor to Pressure Converter

• MSS - Median Signal Select

• NEI - Nuclear Energy Institute 29

Acronyms

• NR - Narrow Range

• NRC - Nuclear Regulatory Commission

• NRR - Nuclear Reactor Regulation (Office of)

• OE - Operating Experience

• OEM - Original Equipment Manufacturer

• P/I - Pressure to Current Converter

• RCP - Reactor Coolant Pump

• RCS - Reactor Coolant System

• RG - Regulatory Guide

• RIS - Regulatory Issue Summary

• Rx - Reactor

• SF/FF - Steam Flow/Feedwater Flow 30

Acronyms

• SG - Steam Generator

• SGWLC - Steam Generator Water Level Control

• SLIM - Small Loop Interface Module

• SME - Subject Matter Expert

• SPV - Single Point Vulnerability

• SWIL - Software In Loop

• USAR - Updated Safety Analysis Report

• WDPF - Westinghouse Distributed Processing Family

• WR - Wide Range 31