METHODOLOGY. Module I-1: Fire Risk Requantification. J.S. Hyslop NRC/RES R.P. Kassawara EPRI

Transcription

1 EPRI/NRC-RES RES FIRE PRA METHODOLOGY Module I-1: Fire Risk Requantification Project J.S. Hyslop NRC/RES R.P. Kassawara EPRI Fire PRA Workshop 2011 San Diego CA and Jacksonville FL

2 General Based on MOU between NRC-RES and EPRI on fire risk Needed to provide more realistic methods for risk-informed, performance-based fire protection activities Scope is full power, CDF and LERF Course does not provide official NRC positions, but does represent the expertise of authors of NUREG/CR-6850 (EPRI ) Fire PRA Workshop 2011, San Diego & Jacksonville Module I-1: Fire Risk Requantification Project Slide 2

3 Quality Product Participation by industry and the public Formal process to resolve technical disputes within NUREG/CR-6850 (EPRI ) team Improvements made in areas important to fire risk Fire PRA methodology still evolving Solutions provided to fifteen fire PRA questions in NFPA 805 frequently asked questions (FAQ) process in NUREG/CR-6850 Supplement 1, EPRI Unreviewed Analysis Methods in process Fire PRA Workshop 2011, San Diego & Jacksonville Module I-1: Fire Risk Requantification Project Slide 3

4 Uses Of Methodology Support for 10CFR50.48(c) implementation Plants using technology for fire PRA development/upgrade ANS fire risk standard development Typically defines state-of-art, although supports lesser capability categories as well Reactor Oversight Process analyses Refined phase 3 analyses Development of phase 2 Fire Protection SDP (IMC 0609, Appendix F) Other expected uses Analyses under the current fire protection regulations (i.e. exemptions/deviations or plant changes due to risk-informed informed technical specifications) Fire PRA Workshop 2011, San Diego & Jacksonville Module I-1: Fire Risk Requantification Project Slide 4

5 Fire Model Validation and Verification (V&V) Fire modeling is an integral part of fire PRA Fire model verification and validation (V&V) is required for NFPA 805 applications Most fire models are computational Some are based only on empirical correlations Address cases where computational fire models inadequate Fill important gaps in fire PRA PRA Methodology document not a reference for fire models EPRI/RES V&V of fire models EPRI /NUREG Fire PRA Workshop 2011, San Diego & Jacksonville Module I-1: Fire Risk Requantification Project Slide 5

6 Related Activities EPRI /NUREG/CR-6850 Publication 2005 General workshops 2005, 2006 Detailed training EPRI /NUREG Fire PRA NFPA 805 FAQ Support 2010 Fire HRA Methodology Development Late 2011 Fire Modeling Application Guide Early 2012 Fire Events Database 2012 Fire Modeling Training Integrated Low Power/Shutdown Fire PRA Methods NRC Fire PRA Workshop 2011, San Diego & Jacksonville Module I-1: Fire Risk Requantification Project Slide 6

7 EPRI/NRC-RES RES FIRE PRA METHODOLOGY Introduction and Overview: the Fire PRA Methodology and Course Structure Steve Nowlen - Sandia National Laboratories Bijan Najafi - Science Applications International Corp. Joint RES/EPRI Fire PRA Training Workshop San Diego, CA, August 1-5, 2011 and Jacksonville, FL, November 14-18, 18, 2011

8 Overview of this morning s presentations I. A brief overview of the course structure, content and objectives II. User experience industry and NRC III. An overview of the ASME/ANS PRA Standard IV. Ongoing projects and activities related to fire PRA Fire Event Database update activity Supplemental methods development efforts and the NRC/industry peer review panel Ongoing g efforts on fire-induced circuit failure mode and likelihood analysis (recent testing, PIRT panel, PRA expert panel) Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 2

9 PART I A brief Overview of the EPRI/NRC-RES RES Fire PRA Methodology & The Fire PRA Course Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 3

10 Course Structure Five parallel modules: 1. PRA/Systems Analysis 2. Electrical Analysis 3. Fire Analysis 4. Fire PRA Human Reliability Analysis (HRA) 5. Advanced Fire Modeling General structure for each module: PowerPoint presentations covering key concepts and the general how to of each task Example problems to illustrate key elements Our intent is that you participate actively in the discussions Ak Ask questions! Instructors will both encourage and moderate discussions They may also closure if discussion gets off-track (e.g., we cannot solve your regulatory questions) Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 4

11 OVERVIEW OF FIRE PRA PROCESS AND MODULE STRUCTURE TASK 1: Plant Boundary & Partitioning TASK 2: Fire PRA Component Selection TASK 3: Fire PRA Cable Selection SUPPORT TASK A: Plant Walk Downs TASK 4: Qualitative ti Screening TASK 5: Fire-Induced Risk Model TASK 6: Fire Ignition Frequencies SUPPORT TASK B: Fire PRA Database TASK 7A: Quantitative Screening - I TASK 12A: Post-Fire HRA: Screening TASK 8: Scoping Fire Modeling Fire Analysis Module Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview TASK 7B: Quantitative Screening - II B Slide 5 PRA/System Module Circuits Module HRA Module Fire Analysis and Fire Modeling Modules

12 OVERVIEW OF FIRE PRA PROCESS AND MODULE STRUCTURE (2) B Detailed Fire Scenario Analysis TASK 9: Detailed Circuit Failure Analysis TASK 10: Circuit Failure Mode & Likelihood Analysis TASK 11: Detailed Fire Modeling A. Single Compartment B. Multi-Compartment C. Main Control Room TASK 13: Seismic-Fire Interactions TASK 14: Fire Risk Quantification TASK 12B: Post fire HRA: Detailed & recovery Fire Analysis Module TASK 15: Uncertainty & Sensitivity Analyses TASK 16: Fire PRA Documentation PRA/System Module Circuits Module HRA Module Fire Analysis and Fire Modeling Modules Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 6

13 Module 1: PRA/Systems Analysis This module cover analysis elements related to plant systems accident response modeling, integration of human actions into the plant model, and risk 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 15: Risk Quantification Task 16: Uncertainty Analysis Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 7

14 Module 2: Electrical Analysis This module covers analysis elements related to the identification and tracing of cables, and the analysis of electrical circuit failure modes and likelihood Tasks covered are: Task 3: Cable Selection (and Routing) Task 9: Detailed Circuit Analysis Task 10: Failure Mode Likelihood Analysis Support Task B: FPRA Database Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 8

15 Module 3: Fire Analysis This module covers analysis elements related to the identification, characterization and analysis of fires scenarios fire sources, fire frequency, fire damage, and fire protection systems and features, Tasks covered are: Task 1: Plant Partitioning i Task 6: Fire Ignition Frequency Task 8: Scoping Fire Modeling Task 11: Detailed Fire Scenario Analysis Task 13: Seismic/Fire Interactions (briefly) Support Task A: Plant Walkdowns Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 9

16 Module 4: Fire PRA Human Reliability Analysis Second year for fire HRA module Updated based on last year s roll-out experience and refinements to the reference document (NUREG-1921, TR , draft for comment) Covers fire PRA analysis elements related to the identification of human failure events (HFEs) and quantification of human error probabilities (HEPs) Tasks covered: Task 12a: screening level HRA Task 12b: detailed HRA quantification Note: EPRI/RES guidance includes an intermediate scoping approach Approach more realistic than screening, yet lacks detail and realism of detailed HRA quantification Instructors will explain how this fits into overall analysis framework Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 10

17 Module 5: Advanced Fire Modeling (New!) Covers the use of computational fire models in support of fire scenario screening and analysis Reference: RES/EPRI NPP Fire Modeling Application Guide (NUREG-1934, TR , draft for comment) From handbook correlations to computational fluid dynamics Fire modeling tools support: Task 8: Scoping Fire Modeling Task 11: Detailed Fire Scenario Analysis Intended as a complement to the fire analysis module 3: Module 3 focuses on the overall structure and content of the fire analysis elements Module 5 focuses on the actual use of computational ti fire models Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 11

18 Another element that you will see in training is citations to the PRA Quality Standard ASME/ANS RA-Sa 2009: Addenda to ASME/ANS RA-S-2008: Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications The training slides provide links from elements of the methodology to requirements of the standard Not intended to teach the standard Intended to provide a road map between the methods and the standard s Supporting Requirements A separate presentation this morning will provide a high-level introduction to the standard, it s structure, and it s place Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 12

19 Any questions before we move on? Fire PRA Training, 2011, San Diego CA and Jacksonville FL Introduction and Overview Slide 13

20 EPRI/NRC-RES FIRE PRA METHODOLOGY AND ITS RELATIONSHIP TO NRC s REGULATORY STRUCTURE Mary Drouin U.S. Nuclear Regulatory Commission Fire PRA Workshop 2011 San Diego CA and Jacksonville FL

21 How Does NUREG/CR-6850 Fit into the NRC Regulatory Structure? The objective here is to provide an understanding, from a regulatory perspective, the need for a fire probabilistic risk assessment (PRA) methodology document, and therefore, its role in the regulatory structure. A major aspect of this objective is understanding what is meant by regulatory structure. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 2

22 NRC Regulatory Structure Congressional Mandate Atomic Energy Act indicates that the mission of the NRC is to ensure that commercial nuclear power plants are operated in a manner that provides adequate protection of public health and safety and is consistent with the common defense and security. NRC provides for public health and safety via a licensing, oversight and enforcement process. Licensing, oversight and enforcement all involve establishing regulations and developing the necessary supporting structure (e.g., regulatory guides). Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 3

23 What is the Relationship Between a Regulation and a Methodology Document? REGULATIONS (e.g., 10 CFR Part 50) Defines technical requirements for the design and operation of the nuclear power plant REGULATORY GUIDES Provides one technical approach that is acceptable for meeting the regulation SUPPORTING TECHNICAL GUIDANCE Technical documents provide detailed guidance on issues associated with meeting the approach established in the regulatory guide (or regulation) Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 4

24 What is the Relationship in the Context of a Fire PRA? Example relevant regulations: 10 CFR 50.48(c), Fire Protection, National Fire Protection Association Standard NFPA CFR 50.69, Risk-informed categorization and treatment of structures, systems and components for nuclear power reactors 10 CFR 50.90, Application for amendment of license, construction permit, or early site permit 10 CFR 50.36, Technical Specifications What is the common element among these regulations? The use of risk information, and therefore, the need to have confidence in the risk analyses (or PRAs) being used to generate the information Risk contributors to be addressed include internal fires. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 5

25 How is This Confidence Achieved? REGULATIONS 10 CFR 50.48(c) 10 CFR CFR CFR etc. RG RG RG RG Guidance/staff position includes use of risk/pra information Reference to RG for guidance on determining PRA technical acceptability for both internal and external hazards (e.g., internal fire) RG Describes one acceptable approach for determining whether the technical adequacy of the PRA, in total or the parts that are used to support an application, is sufficient to provide confidence in the results, such that the PRA can be used in regulatory decision-making for lightwater reactors. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 6

26 How is This Confidence Achieved (cont d)? The approach provided in RG defines the attributes and characteristics of a technically acceptable PRA. The defined attributes and characteristics are very high level. For example, characteristics and attributes provided in RG for Fire Ignition Frequencies: Frequencies are established for ignition sources and consequently for physical analysis units. Transient fires should be postulated for all physical analysis units regardless of administrative controls. Appropriate justification must be provided to use nonnuclear experience to determine fire ignition frequency. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 7

27 How is This Confidence Achieved (cont d)? RG allows the use of a consensus standard (as endorsed by the NRC) with a peer review to demonstrate conformance with the defined attributes and characteristics. RG endorses and provides a position on the ASME/ANS PRA Standard (ASME/ANS RA-Sa-2009). Part 4 of the ASME/ANS standard provides the requirements for fires at-power PRA. The PRA Standard, however, only defines what is required for a technically acceptable PRA and an acceptable peer review. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 8

28 How is This Confidence Achieved (cont d)? Guidance is needed for how to accomplish the requirements in the standard and guidance is needed for the peer review in determining whether the intent of requirement is met. This guidance is particularly needed for those aspects in the PRA where the model is not well known. One major objective of NUREG/CR-6850 is to provide the detailed guidance for how to accomplish meeting the requirements for Fire PRA. As such, NUREG/CR-6850 supports both the PRA standard and the PRA peer review guidance Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 9

29 Overall Relationship REGULATIONS (e.g., 10 CFR Part 50) 50.48(c) etc. REGULATORY GUIDES RG RG RG RG etc. RG WHAT TO SUPPORTING TECHNICAL GUIDANCE DETAILED HOW TO SUPPORTING TECHNICAL GUIDANCE PRA Standard and Peer Review (ASME/ANS RA-Sa-2009 and NEI-07-12) NUREG/CR-6850 NUREG-1855 NUREG-1842 NUREG/CR-6823 etc. PRA Technical Acceptability Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 10

30 Structure of PRA Standard Hazard Type Two different hazard types are defined in the Standard which include both internal and external hazards. Hazard groups Technical Elements Objectives High Level Requirements (HLRs) Supporting Requirements (SRs) For each hazard type, the various groups of hazards are defined, for example for internal hazards: internal events, internal flood and internal fires. For each hazard group, the technical elements are defined for developing the hazard-specific PRA model. The objective of each technical element is defined. High level requirements are defined which specify what is needed to accomplish the defined objective of the technical element. Supporting requirements are defined which, in turn, specify what is needed to accomplish the defined high level l requirement. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 11

31 Structure of PRA Standard (cont d) At the supporting requirement level, it was recognized that the extent or to which the level of detail, the level of plant specificity and the level of realism of the PRA model can vary Consequently, the minimum defined by the requirement can also vary Consequently, three categories of capability were defined for the supporting requirements. Capability Category I: the very basic needed. Capability Category II: the minimum to support majority of applications Capability Category III: the minimum to support application with high reliance on the fidelity of the PRA results. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 12

32 Standard Capability Categories Supporting Requirement Specifies the minimum with regard to level of detail, plant design and operational specificity, and realism of plant response Capability Category I minimum addressed by the technical requirement Capability Category II minimum to achieve current good practice for the technical requirement Capability Category III minimum to achieve the state of the art for the technical requirement Level of detail of plant model Plant design and operational specificity Realism of plant response Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 13

33 Standard Capability Categories (cont d) PRA Attribute Scope and Level of Detail Plant- Specificity Realism Capability Category I Capability Category II Capability Category III Sufficient to identify relative importance at the system or train level Generic data/models except for unique design and operational features Sufficient to identify relative importance of significant component level contributors Plant-specific data/models for the significant contributors Sufficient to identify relative importance of all component level contributors Plant-specific data/models for all contributors Departures from realism Departures from realism will Departures for realism will will have moderate impact* have small impact* have negligible ibl impact* *Differentiation from moderate, to small, to negligible is determined by the degree that the conclusions and risk insights could affect a decision under consideration. Moderate: likely that a decision could be affected Small: unlikely a decision could be affected Negligible: a decision would not be affected. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 14

34 Illustration of Fire PRA Standard Structure and NUREG/CR-6850 Hazard Type Internal Hazards External Hazards Hazard groups Internal Events Internal Floods Internal Fires Seismic Events High Winds External Floods Other External Hazards Technical Elements Plant Partitioning Equipment Selection Cable Selection Qualitative Screening Plant Response Model Fire Scenario Selection Fire Ignition Frequency Quantitative Screening Circuit Failure Human Reliability Analysis Risk Quantification Seismic/Fire Interactions Fire PRA Standard Objectives The objectives of the equipment selection elements is to select the plant equipment that will be included/credited in Fire PRA plant response model. High Level Requirements (HLRs) HLR ES A The Fire PRA shall identify equipment whose failure.... HLR ES B The Fire PRA shall identify equipment whose failure including spurious operation would adversely affect the operability/functionality of that portion of the plant design to be credited in the Fire PRA. HLR ES C the Fire PRA shall identify instrumentation.... HLR ES D TheFire PRA shall document the Fire PRA equipment selection.... Supporting Requirements (SRs) ES B1 Capability Category I Capability Category II Capability Category III IDENTIFY Fire Safe Shutdown/ IDENTIFY Fire Safe Shutdown/ IDENTIFY Fire Safe Shutdown/ Appendix R equipment to be Appendix R equipment to be Appendix R equipment to be credited in thefire PRA. credited in thefire PRA and credited in thefire PRA and INCLUDE risk significant INCLUDE all equipment from equipment from the IE PRA the IE PRA NUREG/ CR-6850 Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 15

35 Fire PRA Standard and NUREG/CR-6850: Illustration of the Mapping of HLRs & SRs to 6850 Technical element HLR SR 6850/ sections that cover SR Comments ES A The Fire PRA shall identify equipment whose failure caused by an initiating fire including spurious operation will contribute to or otherwise cause an initiating event. B C D Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Covered in Cable Selection chapter , The Fire PRA shall identify equipment whose failure including spurious operation would adversely affect the operability/functionality of that portion of the plant design to be credited in the Fire PRA Covered in Fire-Induced Risk Model chapter Covered in Cable Selection chapter 5 n/a Exclusion based on probability is not covered in 6850/ The Fire PRA shall identify instrumentation whose failure including spurious operation would impact the reliability of operator actions associated with that portion of the plant design to be credited in the Fire PRA The Fire PRA shall document the Fire PRA equipment selection, including that information about the equipment necessary to support the other Fire PRA tasks (e.g., equipment identification; equipment type; normal, desired, failed states of equipment; etc.) in a manner that facilitates Fire PRA applications, upgrades, and peer review. 1 n/a Documentation not covered in 6850/ Slide 16

36 Overall Process When implementing RG 1.200, PRA technical acceptability involves: RG Developing a PRA in accordance to the technical requirements of the Standard (as endorsed by NRC) ASME/ANS RA-Sa-2009 NUREG/CR-6850 Technical requirements in the PRA Standard describe what needs to be in the PRA, but do not describe how to build the PRA model Provides guidance for one acceptable methodology that can be used for how to develop PRA and meet the PRA Standard PRA Model Performing a peer review (as endorsed A peer review is required to by NRC) to assess NEI evaluate how the PRA whether the technical model was built to determine requirements were whether it meets the intent of actually met the technical requirements in the PRA Standard Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 17

37 Summary/Conclusion NUREG/CR-6850 is a methodology document and, while not required to be met, plays a major role in defining a technically acceptable Fire PRA to support NRC activities i i where a Fire PRA model is needed and the results of the Fire PRA model are used to meet a regulation. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA Methodology and its Relationship to NRC S Regulatory Structure Slide 18

38 FIRE PRA METHODS AND RESEARCH UPDATE Rick Wachowiak Sr Project Manager EPRI Fire PRA Workshop 2011 San Diego CA and Jacksonville FL Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 1

39 Contents Fire Events Database Heat Release Rates for Electrical Cabinets Fire Methods Expert Review Panel Fire Modeling Application Guide Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 2

40 FEDB Purpose and Objectives The Electric Power Research Institute s Fire Events Data Base is the principal i source of fire incident id operational data for use in fire PRAs This project will improve the FEDB by: Including expanded and improved data fields Improving consistency and quality of information Improved fire event severity classification These improvements support fire PRA: Updated, improved fire frequencies Treatment of detection & suppression effectiveness Estimates of damaging fire frequencies and their characteristics Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 3

41 Scope and Cooperation with NRC under MOU Update data through 2009, and beyond as available Pi Principal i ldata sources: Plant records, e.g. condition or corrective action reports supplemented with available LERs, ENs NEIL, EPIX reports Plant specific data collected for FPRAs Cooperative effort lead by EPRI with NRC under MOU Database software upgrades Data field content and definitions Fire severity criteria Beta testing QA audit Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 4

42 Key Fire Event Data Base Features Event summary description Location and source characteristics Fire duration, growth, and damage descriptive details Detection Time(s) Systems & equipment Fire brigade and other personnel role Suppression Time(s) Systems & equipment Fire brigade and other personnel role Fire severity classification graded, dependent on magnitude and impact details Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 5

43 Fire Event Severity Classifications The severity levels used in the updated FEDB are challenging, potentially challenging, and not challenging The new challenging and potentially challenging classifications combined are essentially equivalent to the NUREG/CR-6850 potentially challenging classification A distinction made between challenging fires that did (or could) damage a critical component beyond the ignition iti source and those potentially challenging fires that might evolve into challenging fires in fire PRA model Initial classification using fire severity algorithm Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 6

44 Fire Event Severity Determination Applied to new and existing fire event data (1990 forward) Fire event severity classification algorithm: Logic model using FEDB data field entries to indicate initial fire severity classification Challenging Potentially Challenging Not Challenging Identifies key missing information needed to make classification on undetermined events Fire event severity classification review & justification for exceptions required Resolution of undetermined severity classifications incorporated in event data collection and coding process to extent practical Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 7

45 Event Derived/Inferred: Fire Severity Event Classification CHALLENGING One of the following: Event Sub-Classification Criteria Damage to or ignition of an adjacent object occurred. This includes ignition of secondary combustibles. Damage to or ignition of an adjacent object could have occurred if the fire were in a different location. Damage to or ignition of an adjacent object or component could have occurred if significant suppression actions had not been taken. POTENTIALLY CHALLENGING Not challenging and one of the following: NOT CHALLENGING Not potentially challenging and one of the following: Damage to or ignition of an adjacent object could have occurred if minor suppression actions were not taken in a timely manner. Damage to or ignition of an adjacent object could have occurred if the fire were in a different location and if minor suppression actions were not taken in a timely manner. Overheat condition only; no smoldering or flaming combustion. Smoldering fire self-extinguishes without any active intervention. Fire involves an ignition source in a location that has no relevance to plant operations or safety. UNDETERMINED Any fire event that t does not have sufficient i information to classify as challenging, potentially challenging, or not challenging. Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 8

46 Fire Events Database Progress 1 Request CR List for Key Words (2,000-4,000 / plant) n = input from utilities required Important t Existing FEDB Fire Events (0 5 / plant) Owner s Groups Perform Screening Review Request CRs for Probable Fires ( / plant) 1 2 Plants responding to requests 3 EPRI Screen for Potential Significance Site Follow-up for Real Fires (10 15 / plant) 2 m = Audit (NRC) Expect completion in 2011 Potentially Challenging and Challenging Fires EPRI Categorize Important Fires (0-3/plant) 3 Events in New FEDB 3 rd audit in Nov 2011 Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 9

47 Fire Ignition Frequency (Re)Analysis: Purpose, Objective, Scope Re-examine and update fire event trends and fire ignition frequencies developed in EPRI interim Report , FAQ Use data from the FEDB updated through 2009 Improved methods to address statistical issues/concerns for low density fire ignition bins Results to be suitable for use in plant specific fire PRA applications Includes coordination with the NRC, industry technical review Preparation of EPRI technical reports Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 10

48 Fire Ignition Frequency (Re)Analysis: Technical Issues and Approach Based on data from , between plant variability detected Strong indication for aggregated data, high density fire ignition bins Low density fire ignition bins indeterminate Approach assumes between plant variability Plan to apply hierarchical Bayes treatment for all fire ignition bins; draft methodology report prepared and in review Uncertainty bounds & plant specific sensitivity will generally increase while maintaining generic results for mean fire ignition frequencies Industry wide trends and any implications unknown until new data is available for analysis Use of pre-1990 data under discussion between RES and EPRI Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 11

49 Fire Ignition Frequency (Re)Analysis: Status and Schedule Methodology report for technical review with NRC under MOU: Comments received 2 nd Qtr 2011 Draft EPRI Interim Technical Report on methodology for industry technical review: 4 th Qtr 2011 Draft EPRI Technical Report on updated FEDB fire ignition frequency (re)analysis: 1 st Qtr 2012 Final EPRI Technical Report (methodology and data analysis): Mid 2012 Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 12

50 Vertical Electrical Cabinet Heat Release Rate Proposed Methodology Purpose of study: Re-evaluate the heat release rates (HRRs) of cabinet fires recommended for use in NUREG/CR-6850 (Table G-1) Scope limited to: Vertical electrical cabinets No quantification of external influences No quantification of fire duration Model developed to characterize potential HRR for cabinet fires Cabinet size and combustible load Ventilation characteristics Types of combustibles Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 13

51 Vertical Electrical Cabinet Heat Release Rate Model Proposed Methodology Model maintains distinction between qualified cable and non-qualified cable fires Establish probability that fire in a cabinet with only qualified cables may remain localized Model adds refinements and thus more inputs needed than in NUREG/CR- 6850: If not ventilation-limited: HRR dependent on combustible loading. Combustible loading estimated based on: Cabinet volume Estimate of cabinet fullness (low/high loading). If ventilation-limited: HRR controlled by amount of air available for combustion. Determination on whether cabinet is cooled by forced or natural ventilation Assessment of robustness regarding gap potential Need to know vent area and position of vents (top, bottom, or vents at intermediate t level) l) Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 14

52 Vertical Electrical Cabinet Heat Release Rate Proposed Methodology Current Status Independent d expert review panel Fire modeling and fire PRA practitioners Mix of contractors and utility Verify that the method is correct, has proper bases, and is useable Comments received and are being resolved Expected to be published in 2011 NRC requested formal review by NRC-RES RES Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 15

53 FPRA Unreviewed Analysis Methods Review Panel NEI allows Fire PRA peer reviews to identify unreviewed analysis methods Panel process established to provide a review for any new methods 6 to 10 members Utilities, EPRI, Owners Groups, NRC Independent from developer and user(s) of method(s) Review proposed method and provide comments Determine the applicability / limitations of the method Identify interface with the Fire PRA Standard EPRI to publish approved methods via letter to NEI Eventually provided as a collection in an EPRI report Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 16

54 Panel Status ERIN Engineering and Research, Inc. submitted four methods Alignment factors for: Electrical cabinet fires Pump oil fires Transient fires Hot work fires Each method attempts to add realism to a fire PRA Proposition is that fires included in the generic frequencies do not generally behave as aggressively as the Fire PRA treats them Review of methods as submitted is complete and there are significant comments ERIN is resolving comments Each of the methods will need to be re-reviewed following update of the documentation Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 17

55 Insights From the Panel Process Methods that treat all scenarios the same are more difficult to justify Tie method to scenario specific information Specify information needed to justify applicability Methods relying on expert judgment may put the panel into a different role Expert panel vs. independent review Different process may be needed when in this role Co onservatism in Method Scenario specific examples needed d Involve the author earlier in the process Review one method at a time Generic Applicability Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 18

56 Fire Modeling Application Guide Joint EPRI / NRC RES publication under MOU Describes the process of conducting a fire modeling analysis for commercial nuclear power plant applications Provides guidance on incorporating the uncertainty associated with a fire modeling analysis in a Fire PRA Five fire models discussed Two empirical, two zone, one CFD Eight real world examples provided Applicability of models and data ranges Draft is out for public comment This forms the bases for Module 5 Advanced Fire Modeling Fire PRA Workshop 2011, San Diego & Jacksonville Fire PRA New Methods Update Slide 19

57 Enhanced Fire Events Database to Support Fire PRA (A joint NRC-RES/EPRI project) Given by J.S. Hyslop, NRC/RES Joint RES/EPRI Fire PRA Workshop August and November 2011 San Diego, CA

58 Motivation Need for improved database identified by NFPA 805 FAQ program FAQ 48 required an update of current fire events database to include data address fire ignition frequency Updated, improved database will also serve more general fire PRA needs of both NRC and industry Fire PRA Workshop, 2010, San Diego & Jacksonville Enhanced Fire Events Database Slide 2

59 Participants and Roles Joint project by RES and EPRI RES and EPRI collaborated on data fields and criteria for severity classification EPRI taking the lead in collecting data and populating database, with RES in an audit role SNL and INL under contract to RES; ERIN lead contractor to EPRI Plan for a joint RES/EPRI report to be issued on project in 2012 Fire PRA Workshop, 2010, San Diego & Jacksonville Enhanced Fire Events Database Slide 3

60 Improvements Expanded and improved data fields Improved Fire Ignition Source Details Improved Fire Detection and Suppression Response Details Improved Fire Event Severity Classification More complete data Update expected to collect more data than currently exists for total period of existing database Expanded fields will capture important information relevant to analyses unavailable in existing version. Each individual event description will also be more complete Reduced d percentage of undetermined d data Fire PRA Workshop, 2010, San Diego & Jacksonville Enhanced Fire Events Database Slide 4

61 Improvements (cont.) Severity classification for applying database to frequency expanded to be more transparent and reproducible, although some judgment remains Generic rules to eliminate false positives for events under the severity classification generated Improving Consistency and Quality Assurance Allowing for Reference Data Source Traceability Fire PRA Workshop, 2010, San Diego & Jacksonville Enhanced Fire Events Database Slide 5

62 Four severity classifications Challenging Potentially Challenging Not Challenging Undetermined Event Derived/Inferred : Fire Severity For challenging, the fire is further developed than for potentially challenging Potentially challenging fires evolve into challenging fires in fire PRA model Thus, no PRA applications distinguish between potentially challenging and challenging fires Fire PRA Workshop, 2010, San Diego & Jacksonville Enhanced Fire Events Database Slide 6

63 Applications Initial application will be fire ignition frequency An essential companion application will be suppression reliability Some very minor fires kept in earlier database will be removed in update Expect true component frequencies will be developed once component population data collected by Owners Groups (later than 2012 schedule cited earlier) Further qualitative insights on fires to be gained Fire PRA Workshop, 2010, San Diego & Jacksonville Enhanced Fire Events Database Slide 7

64 EPRI/NRC-RES RES FIRE PRA METHODOLOGY dc Circuits Project and Related Activities Gabriel Taylor U.S. NRC U. S. NRC Office of Nuclear Regulatory Research Joint RES/EPRI Fire PRA Training i Workshop San Diego, CA, August 2011 and Jacksonville, FL, November 2011

65 History of Fire & Circuit Problems Failure, Protection, Testing RG 1.75, Physical Independence of Electrical Systems Browns Ferry Fire 1975 IEEE 383, Qualifying Class 1E Electrical Cables IN 99-17, Post-Fire Safe-Shutdown Shutdown Circuit Analysis Problems NEI Cable Testing 2001 & Expert Elicitation 2002 RIS , Risk-Informed Approach for Post-Fire Safe- Shutdown Circuit Inspections NRC CAROLFIRE RIS Bin 2 & Fire Modeling DUKE Armored Cable Testing NRC DESIREE-FIRE direct current circuits KATE-FIRE Kerite Thermal Fragility Evaluation Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 2

66 NEI / EPRI Testing 2001 Square Steel Room Diffusion Burner Cable Tray & Conduit Bend Sprinkler Head Hot Gas & Plume Exposures 18 Tests using MOV Circuit Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 3

67 CAROLFIRE Cable Response to Live Fire 78 Small- and 18 Intermediate-scale tests ac MOV and Insulation Resistance Measurement Systems used for failure mode diagnostic RIS & Fire Model Improvement Penlight Shroud A Cable Tray & Test Cables A A-A 0.81 m (2'-8") 0.51 m (1'-8 1/4") Cable Tray Supports Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 4

68 DESIREE-FIRE Direct Current Electrical Shorting In Response to Exposure Fire Similar thermal exposure methods as CAROLFIRE 59 small- and 17 intermediate scale tests 225 individual circuit trials Insulation resistance measurement was not used Several different dc control circuits simulated NPP circuits and monitored cable failure modes. dc MOV Medium Voltage Switchgear (15kV / 4.16kV) Pilot SOV 1 SOV assembly Large coil Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 5

69 Diagnostic Units FROM DISTRIBUTION CIRCUIT BREAKER FUSE BLOCK DCCCS V A CABLE UNDER TEST P VDC 10A A C NC C NC B NO A NC O V V V V A A A A G R YC1 YO A V A N V SP Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 6

70 DESIREE-FIRE Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 7

71 CAROLFIRE ac Results RIS Inter-cable shorting less likely than Intra- Inter-cable between thermoset and thermoplastic is very small compared to either common type No basis on number of failures to consider No basis for taking credit of CPT Very low probability of ac hot shorts >20 minutes in duration THIEF fire model Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 8

72 Cable Damage Prediction Model THIEF Thermally-Induced Electrical Failure (THIEF) Provides a numerical solution of the one-dimensional heat conduction equations within a homogenous cylinder with fixed temperature-independent properties Incorporated in CFAST and FDS fire models User specifies cable failure temperature Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 9

73 Electrical PIRT Phenomena Identification and Ranking Table Structured approach to an expert elicitation Facilitated by Brookhaven National Laboratories Group of 8 electrical experts 4 NRC, National Laboratories 4 EPRI, Utilities, Contractors Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 10

74 PIRT Objectives Review test data, identify important phenomena that affects cable/circuit it failure mode, and then rank the phenomena and important influencing parameters. Consensus on longstanding post-fire safe-shutdown shutdown circuit issues. MHIF, 3 phase proper polarity, CTs, etc. Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 11

75 PIRT Work PIRT panel identified lack of readily usable information from multiple testing reports NRC has initiative to provide a compilation NUREG document of previous test results Focus on evaluating the data based on the key phenomena and parameters identified by PIRT panel. Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 12

76 Data Report Example Failure Mode 80 Global Approach - Insultion Type 100% 60 Co ount % 52% 62% Fuse Clear Spurious Actuation Hot Short 38% HS/SA Possible 20 44% 51% 56% 0 TP TS Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 13

77 Data Report Example Raceway Routing Duration 400 Duration - Raceway Routing MAX = 1345 MAX = Seconds q1 min median max q3 0 AIR CONDUIT TRAY AIR CONDUIT TRAY Hot Short Spurious Actuation Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 14

78 PRA Expert Panel Electrical PIRT Panel results will be used by a follow-on group of fire PRA experts PRA panel will revise EPRI best-estimate conditional probabilities for circuit hot short/spurious actuations used in fire PRA methods, along with developing new probabilities. Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 15

79 dc Circuits Project and Related Activities Questions Questions? Fire PRA Workshop, 2011 Fire PRA Circuit Analysis Activities Slide 16

80 EPRI/NRC-RES Fire PRA Course Revision Date: June 21, 2011 Electric Power Research Institute (EPRI) Division of Risk Analysis 3412 Hillview Avenue Office of Nuclear Regulatory Research (RES) Palo Alto, CA U.S. Nuclear Regulatory Commission Washington, DC 20555

81 2

82 PREPARERS TECHNICAL TEAM LEADS: Bijan Najafi Science Applications International Corp Dell Ave, Suite 100 Campbell, CA Steven P. Nowlen Sandia National Laboratories (SNL) PO Box 5800 Albuquerque, NM PROJECT MANAGERS: Richard Wachowiak Electric Power Research Institute J. S. Hyslop U.S. Nuclear Regulatory Commission Office of Nuclear Regulatory Research Fire Research Branch iii

83

84 CONTENTS 1 INTRODUCTION Background How to Use this Package References EXAMPLE CASE PLANT - GENERAL INFORMATION Overall Plant Description Systems Description Primary Coolant System Chemical Volume Control and High Pressure Injection Systems Residual Heat Removal System Auxiliary Feedwater System Electrical System Other Systems Plant Layout SNPP Drawings MODULE 1: PRA/SYSTEMS MODULE 2: ELECTRICAL ANALYSIS MODULE 3: FIRE ANALYSIS MODULE 4: FIRE PRA HUMAN RELIABILITY ANALYSIS MODULE 5: ADVANCED FIRE MODELING v

85

86 LIST OF ACRONYMS AFW Auxiliary Feedwater ATWS Anticipated Transient Without Scram BWR Boiling Water Reactor CCDP Conditional Core Damage Probability CF Cable (Configuration) Factors CCW Component Cooling Water CDF Core Damage Frequency CFD Computational Fluid Dynamics CFR Code of Federal Regulations CLERP Conditional Large Early Release Probability CM Corrective Maintenance CRS Cable and Raceway (Database) System CVCS Chemical and Volume Control System EDG Emergency Diesel Generator EF Error Factor EOP Emergency Operating Procedure EPR Ethylene-Propylene Rubber EPRI Electric Power Research Institute FEDB Fire Events Database FEP Fire Emergency Procedure FHA Fire Hazards Analysis FIVE Fire-Induced Vulnerability Evaluation (EPRI TR ) FMRC Factory Mutual Research Corporation FPRAIG Fire PRA Implementation Guide (EPRI TR ) FRSS Fire Risk Scoping Study (NUREG/CR-5088) FSAR Final Safety Analysis Report HEAF High Energy Arcing Fault HEP Human Error Probability HFE Human Failure Event HPI High Pressure Injection HPCI High Pressure Coolant Injection HRA Human Reliability Analysis HRR Heat Release Rate HVAC Heating, Ventilation, and Air Conditioning ICDP Incremental Core Damage Probability ILERP Incremental Large Early Release Probability vii

87 IPE IPEEE IS ISLOCA KS LERF LFL LOC LOCA MCC MCR MG MOV MQH MS NC NEI NEIL NFPA NPP NPSH NQ cable NRC P&ID PE PM PMMA PORV PRA PSF PVC PWR Q cable RCP RCS RDAT RES RHR RPS RWST SDP SGTR SI SO SOV SRV Individual Plant Examination Individual Plant Examination of External Events Ignition Source Interfacing Systems Loss of Coolant Accident Key Switch Large Early Release Frequency Lower Flammability Limit Loss of Control Loss of Coolant Accident Motor Control Center Main Control Room Motor-Generator Motor Operated Valve McCaffrey, Quintiere and Harkleroad s Method Main Steam No Consequence Nuclear Energy Institute Nuclear Electric Insurance Limited National Fire Protection Association Nuclear Power Plant Net Positive Suction Head Non-Qualified (IEEE-383) cable Nuclear Regulatory Commission Piping and Instrumentation Diagram Polyethylene Preventive Maintenance Polymethyl Methacrylate Power Operated Relief Valve Probabilistic Risk Assessment Performance Shaping Factor Polyvinyl Chloride Pressurized Water Reactor Qualified (IEEE-383) cable Reactor Coolant Pump Reactor Coolant System Computer program for Bayesian analysis The Office of Nuclear Regulatory Research (at NRC) Residual Heat Removal Reactor Protection System Refueling Water Storage Tank Significance Determination Process Steam Generator Tube Rupture Safety Injection Spurious Operation Solenoid Operated Valve Safety Relief Valve viii

88 SSD SSEL SUT T/G TGB TSP UAT VCT VTT XLPE ZOI Safe Shutdown Safe Shutdown Equipment List Start-up Transformer Turbine/Generator Turbine-Generator Building Transfer Switch Panel Unit Auxiliary Transformer Volume Control Tank Valtion Teknillinen Tutkimuskeskus (Technical Research Centre of Finland) Cross-Linked Polyethylene Zone of Influence ix

89

90 1 INTRODUCTION 1.1 Background The U.S. Nuclear Regulatory Commission and Electric Power Research Institute under a Memorandum of Understanding (MOU) on Cooperative Nuclear Safety Research have been developing state of the art methods for conduct of fire PRA. In September 2005, this work produced the EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities, EPRI , and NUREG/CR-6850 [1]. A Fire PRA Course has been put together to train interested parties in the application of this methodology. The Course/Seminar is provided in five parallel modules. The first three modules are based directly on Reference [1]. However, that document did not cover fire human reliability analysis (HRA) methods in detail. For 2010, the training materials were enhanced to include a fourth module based on a more recent EPRI/RES collaboration and a draft guidance document, EPRI , NUREG-1921 [2] published in late The training materials are based on this draft document including the consideration of public comments received on the draft report and the team s responses to those comments. For 2011 a fifth training module on Advanced Fire Modeling techniques and concepts has been added to the course. This module is based on the another joint RES/EPRI collaboration and a draft guidance published in January 2010, EPRI , NUREG-1934 [3]. The four training modules are: Module 1: PRA/Systems Analysis - This module covers the technical tasks for development of the system response to a fire including human failure events. Specifically, this module covers Tasks/Sections 2, 4, 5, 7, 14, and 15 of Reference [1]. Module 2: Electrical Analysis This module covers the technical tasks for analysis of electrical failures as the result of a fire. Specifically, this module covers Tasks/Sections 3, 9, and 10 of Reference [1]. Module 3: Fire Analysis This module covers technical tasks involved in development of fire scenarios from initiation to target (e.g., cable) impact. Specifically, this module covers Tasks/Sections 1, 6, 8, 11, and 13 of Reference [1]. Module 4: Fire Human Reliability Analysis: This module covers the technical tasks associated with identifying and analyzing operator actions and performance during a postulated fire scenario. Specifically, this module covers Task 12 as outlined in Reference [1] based on the application of the approaches documented in Reference [2]. 1-1

91 Module 5: Advanced Fire Modeling: This module is new for the 2011 training course and covers the fundamentals of fire science and provided practical implementation guidance for the application of fire modeling in support of a fire PRA. Module 5 covers fire modeling applications for Tasks 8 and 11 as outlined in Reference [1] based on the material presented in Reference [3]. Integral to Modules 1, 2 and 3 is a set of hands-on problems based on a fictitious, simplified nuclear power plant. The same power plant is used in all three modules. This document provides the background information for the problem sets of each module. Clearly, the power plant defined in this package is an extremely simplified one that in many cases does not meet any regulatory requirements or good engineering practices. Design features presented are focused on bringing forward the various aspects of the Fire PRA methodology. This package includes a general description of the power plant and the internal events PRA needed as input to the Fire PRA. For Module 4 and 5, independent sets of examples are used to illustrate key points of the analysis procedures. The examples for these two modules are not tied to the simplified plant. Module 4 uses examples that were derived based largely on pilot applications of the proposed fire HRA methods and on independent work of the EPRI and RES HRA teams. The examples for Module 5 were taken directly from Reference [3] and represent a range of typical NPP fire scenarios across a range of complexity and that highlight some of the computation challenges associated with the NPP fire PRA fire modeling applications. The instruction package for specific technical tasks is provided in Sections 3, 4, 5 and 6 which are organized by Modules (see above). A short description of the Fire PRA technical tasks is provided below. For further details, refer to the individual task descriptions in EPRI , NUREG/CR-6850, Volume 2. The figure presented at the end of this chapter provides a simplified flow chart for the analysis process and indicates which training module covers each of the analysis tasks. 1-2 Plant Boundary Definition and Partitioning (Task 1). The first step in a Fire PRA is to define the physical boundary of the analysis, and to divide the area within that boundary into analysis compartments. Fire PRA Component Selection (Task 2). The selection of components that are to be credited for plant shutdown following a fire is a critical step in any Fire PRA. Components selected would generally include many, but not necessarily all components credited in the 10 CFR 50 Appendix R post-fire SSD analysis. Additional components will likely be selected, potentially including most but not all components credited in the plant s internal events PRA. Also, the proposed methodology would likely introduce components beyond either the 10 CFR 50 Appendix R list or the internal events PRA model. Such components are often of interest due to considerations of multiple spurious actuations that may threaten the credited functions and components; as well as due to concerns about fire effects on instrumentation used by the plant crew to respond to the event. Fire PRA Cable Selection (Task 3). This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as EPRI FIVE and Fire PRA Implementation

92 Guide) this task was relegated to the SSD analysis and its associated databases. This document offers a more structured set of rules for selection of cables. Qualitative Screening (Task 4). This task identifies fire analysis compartments that can be shown to have little or no risk significance without quantitative analysis. Fire compartments may be screened out if they contain no components or cables identified in Tasks 2 and 3, and if they cannot lead to a plant trip due to either plant procedures, an automatic trip signal, or technical specification requirements. Plant Fire-Induced Risk Model (Task 5). This task discusses steps for the development of a logic model that reflects plant response following a fire. Specific instructions have been provided for treatment of fire-specific procedures or preplans. These procedures may impact availability of functions and components, or include fire-specific operator actions (e.g., self-induced-station-blackout). Fire Ignition Frequency (Task 6). This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully componentbased ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE). Quantitative Screening (Task 7). A Fire PRA allows the screening of fire compartments and scenarios based on their contribution to fire risk. This approach considers the cumulative risk associated with the screened compartments (i.e., the ones not retained for detailed analysis) to ensure that a true estimate of fire risk profile (as opposed to vulnerability) is obtained. Scoping Fire Modeling (Task 8). This step provides simple rules to define and screen fire ignition sources (and therefore fire scenarios) in an unscreened fire compartment. Detailed Circuit Failure Analysis (Task 9). This task provides an approach and technical considerations for identifying how the failure of specific cables will impact the components included in the Fire PRA SSD plant response model. Circuit Failure Mode Likelihood Analysis (Task 10). This task considers the relative likelihood of various circuit failure modes. This added level of resolution may be a desired option for those fire scenarios that are significant contributors to the risk. The methodology provided in this document benefits from the knowledge gained from the tests performed in response to the circuit failure issue. Detailed Fire Modeling (Task 11). This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the EPRI FIVE and Fire PRA Implementation Guide in nearly all technical areas. 1-3

93 Post-Fire Human Reliability Analysis (Task 12). This task considers operator actions for manipulation of plant components. The analysis task procedure provides structured instructions for identification and inclusion of these actions in the Fire PRA. The procedure also provides instructions for incorporating human error probabilities (HEPs) into the fire PRA analysis. (Note that NUREG/CR-6850, EPRI did not develop a detailed fire HRA methodology. Fire-specific HRA guidance can be found in NUREG-1921, EPRI , EPRI/NRC-RES Fire Human Reliability Analysis Guidelines Draft Report for Comment, November Publication of the final Fire HRA report remains pending.) Seismic Fire Interactions (Task 13). This task is a qualitative approach to help identify the risk from any potential interactions between an earthquake and fire. Fire Risk Quantification (Task 14). The task summarizes what is to be done for quantification of the fire risk results. Uncertainty and Sensitivity Analyses (Task 15). This task describes the approach to follow for identifying and treating uncertainties throughout the Fire PRA process. The treatment may vary from quantitative estimation and propagation of uncertainties where possible (e.g., in fire frequency and non-suppression probability) to identification of sources without quantitative estimation. The treatment may also include one-at-a-time variation of individual parameter values or modeling approaches to determine the effect on the overall fire risk (sensitivity analysis). 1.2 How to Use this Package This package is intended to provide the background information necessary to perform some of the problem sets of the Course/Seminar. Please note: 1. All Course/Seminar attendees are expected to review Section 2 of this document and become familiar with the power plant defined in that section. 2. The instructors of each module will provide questions or case study problem sets and will guide the attendees to sections relevant to each specific problem set. Attendees will be expected to review those relevant sections and use the information or examples provided in those sections to complete the assigned problem set. 3. Do not make any additional assumptions in terms of equipment, systems, or plant layout other than those presented in the problem package without consulting the instructor. 1.3 References 1. EPRI , NUREG/CR-6850, EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities, September EPRI , NUREG-1921, EPRI/NRC-RES Fire Human Reliability Analysis Guidelines Draft Report for Comment, Technical Update, November EPRI , NUREG-1934, Nuclear Power Plant Fire Modeling Application Guide Draft Report for Comment, January

94 1-5

95 1-6