ML19162A416
| ML19162A416 | |
| Person / Time | |
|---|---|
| Issue date: | 06/13/2019 |
| From: | NRC/RES/DRA |
| To: | |
| T. Rivera | |
| Shared Package | |
| ML19162A411 | List: |
| References | |
| Download: ML19162A416 (17) | |
Text
NUREG/CR-6850 FIRE PRA METHODOLOGY Module 1 Internal Event, At-Power Probabilistic Risk Assessment Model for SNPP Introduction and Overview:
Scope and Structure of PRA/
Systems Analysis Module Nicholas Melly - Nuclear Regulatory Commission Fire PRA Workshop June 24, 2019 - June 28, 2019 Rockville, MD U.S. NRC HQ
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 2 What Well Cover in the Next Four Days An Overview The purpose of this presentation is to provide an Overview of the Module 1 - PRA/Systems Analysis
Scope of this module relative to the overall methodology
Which tasks fall under the scope of this module
General structure of the each technical task in the documentation
Quick introduction to each task covered by this module:
Objectives of each task
Task input/output
Task interfaces
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 3 Training Objectives Our intent:
To deliver practical implementation training
To illustrate and demonstrate key aspects of the procedures We expect and want significant participant interaction
Class size should allow for questions and discussion
We will take questions about the methodology
We cannot answer questions about a specific application
We will moderate discussions and we will judge when the course must move on
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 4 Recall the Overall Fire PRA Structure Module 2 Covers the Blue Tasks TASK 1: Plant Boundary &
Partitioning TASK 2: Fire PRA Component Selection TASK 3: Fire PRA Cable Selection TASK 4: Qualitative Screening TASK 6: Fire Ignition Frequencies TASK 5: Fire-Induced Risk Model TASK 7A: Quantitative Screening - I TASK 8: Scoping Fire Modeling SUPPORT TASK A: Plant Walk Downs SUPPORT TASK B: Fire PRA Database TASK 7B: Quantitative Screening - II TASK 12A: Post-Fire HRA:
Screening B
Fire Analysis Module PRA/System Module Circuits Module HRA Module Fire Analysis and Fire Modeling Modules
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 5 Recall the Overall Fire PRA Structure (2)
Module 2 Covers the Blue Tasks Detailed Fire Scenario Analysis B
TASK 11: Detailed Fire Modeling A. Single Compartment B. Multi-Compartment C. Main Control Room TASK 9: Detailed Circuit Failure Analysis TASK 10: Circuit Failure Mode &
Likelihood Analysis TASK 14: Fire Risk Quantification TASK 15: Uncertainty &
Sensitivity Analyses TASK 16: Fire PRA Documentation TASK 12B: Post fire HRA:
Detailed & recovery TASK 13: Seismic-Fire Interactions Detailed Fire Scenario Analysis B
TASK 11: Detailed Fire Modeling A. Single Compartment B. Multi-Compartment C. Main Control Room TASK 9: Detailed Circuit Failure Analysis TASK 10: Circuit Failure Mode &
Likelihood Analysis TASK 14: Fire Risk Quantification TASK 15: Uncertainty &
Sensitivity Analyses TASK 16: Fire PRA Documentation TASK 12B: Post fire HRA:
Detailed & recovery TASK 13: Seismic-Fire Interactions Fire Analysis Module PRA/System Module Circuits Module HRA Module Fire Analysis and Fire Modeling Modules
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 6 Each Technical Task Has a Common Structure as Presented in the Guidance Document
- 1. Purpose
- 2. Scope
- 3. Background information: General approach and assumptions
- 4. Interfaces: Input/output to other tasks, plant and other information needed, walk-downs
- 5. Procedure: Step-by-step instructions for conduct of the technical task
- 6. References Appendices: Technical bases, data, examples, special models or instructions, tools or databases
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 7 Scope of Module 1: PRA/Systems Analysis This module will cover all aspects of the plant systems accident response modeling, integration of human actions into the plant model, and quantification tasks Specific tasks covered are:
Task 2: Equipment Selection
Task 4: Qualitative Screening
Task 5: Fire-Induced Risk Model
Task 7: Quantitative Screening
Task 14: Fire Risk Quantification
Task 15: Uncertainty and Sensitivity Analyses
Task 16: Documentation
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 8 Task 2: Equipment Selection (1 of 2)
Module 1 Objective: To decide what subset of the plant equipment will be modeled in the FPRA FPRA equipment will be drawn from:
Equipment from the internal events PRA
We do assume that an internal events PRA is available!
Equipment from the Post-Fire Safe Shutdown analysis
e.g., The Appendix R analysis or the Nuclear Safety Analysis under NFPA-805
Other new equipment not in either of these analyses
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 9 Task 2: Equipment Selection (2 of 2)
Module 1 Many choices to be made in this task; many factors will influence these decisions
Fire-induced failures that might cause an initiating event
Mitigating equipment and operator actions
Fire-induced failures that adversely impact credited equipment
Fire-induced failures that could lead to inappropriate or unsafe operator actions Choices are important in part because selecting equipment implies a burden to Identify and Trace cables
Cable selection is Task 3 (Module 2)
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 10 Task 4: Qualitative Screening (1 of 2)
Module 1 Objective: To identify fire compartments that can be screened out as insignificant risk contributors without quantitative analysis This is an Optional task
You may choose to bypass this task, which means that all fire compartments will be treated quantitatively to some level of analysis (level may vary)
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 11 Task 4: Qualitative Screening (2 of 2)
Module 1
Qualitative screening criteria consider:
Trip initiators
Presence of selected equipment
Presence of selected cables
Note that any compartment that is screened out in this step is reconsidered in the multi-compartment fire analysis as a potential source of multi-compartment fires
See Module 3, Task 11c
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 12 Task 5: Fire-Induced Risk Model Module 1
Objective: Construct the FPRA plant response model reflecting:
Functional relationships among selected equipment and operator actions
Begins with internal events model but more than just a tweak
Adds fire unique equipment - Various reasons/sources
May delete equipment not to be credited for fire
Adds fire-specific equipment failure modes
e.g., Spurious actuations (Task 9)
Adds fire-specific human failure events (Task 12)
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 13 Task 7: Quantitative Screening (1 of 2)
Module 1
Objective: To identify compartments that can be shown to be insignificant contributors to fire risk based on limited quantitative considerations
This task is Optional
Analyst may choose to retain all compartments for more detailed analysis
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 14 Task 7: Quantitative Screening (2 of 2)
Module 1
Screening may be performed in stages of increasing complexity
Consideration is given to:
Fire ignition frequency
Screening of specific fire sources as non-threatening (no spread, no damage)
Impact of fire-induced equipment and cable failures
Conditional core damage probability (CCDP)
A word of caution: Quantitative screening criteria should consider the PRA standard and Reg. Guide 1.200
6850/1011989 criteria are obsolete, but approach is unchanged
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 15 Task 14: Fire Risk Quantification Module 1
Objective: To quantify fire-induced CDF and LERF
Covered in limited detail
Relatively straight-forward roll-up for fire scenarios considering:
Ignition frequency
Scenario-specific equipment and cable damage
Equipment failure modes and likelihoods
Credit for fire mitigation (detection and suppression)
Fire-specific HEPs
Quantification of the FPRA plant response model
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 16 Task 15: Uncertainty and Sensitivity Module 1
Objective: Provide a process for identifying and quantifying uncertainties in the FPRA and for identifying sensitivity analysis cases
Covered in limited detail
Guidance is based on potential strategies that might be taken, but choices are largely left to the analyst
e.g., What uncertainties will be characterized as distributions and propagated through the model?
Fire PRA Workshop 2019, Rockville, MD Module 1: Internal Event, At-Power PRA Model for SNPP Slide 17 Any questions before we move on?