ML19162A421
| ML19162A421 | |
| Person / Time | |
|---|---|
| Issue date: | 06/13/2019 |
| From: | Nick Melly NRC/RES/DRA |
| To: | |
| T. Rivera | |
| Shared Package | |
| ML19162A411 | List: |
| References | |
| Download: ML19162A421 (17) | |
Text
NUREG/CR-6850 FIRE PRA METHODOLOGYModule 1Internal Event, At
-Power ProbabilisticRisk Assessment Model for SNPPTask 14: Fire Risk QuantificationNicholas Melly
-Nuclear Regulatory CommissionFire PRA WorkshopJune 24, 2019
-June 28, 2019Rockville, MD U.S. NRC HQ Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 2Fire Risk QuantificationPurpose (per 6850/1011989)Purpose: Describe the procedure for performing fire risk quantificationProvides a general method for quantifying the final Fire PRA Model to generate the final fire risk results Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 3Fire Risk Quantification Corresponding PRA Standard ElementPrimary match is to element FQ
-Fire Risk QuantificationFQ Objectives (as stated in the PRA standard):(a) quantify the fire
-induced CDF and LERF contributions to plant risk(b) understand what are the significant contributors to the fire
-induced CDF and LERF Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 4Fire Risk Quantification HLRs (per the PRA Standard)HLR-FQ-A: Quantification of the Fire PRA shall quantify the fire-induced CDFHLR-FQ-B: The fire
-induced CDF quantification shall use appropriate models and codes, and shall account for method-specific limitations and featuresHLR-FQ-C: Model quantification shall determine that all identified dependencies are addressed appropriatelyHLR-FQ-D: The frequency of different containment failure modes leading to a fire
-induced large early release shall be quantified and aggregated, thus determining the fire
-induced LERF Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 5Fire Risk Quantification HLRs (per the PRA Standard)HLR-FQ-E: The fire
-induced CDF and LERF quantification results shall be reviewed and significant contributors to CDF and LERF, such as fires and their corresponding plant initiating events, fire locations, accident sequences, basic events (equipment unavailabilities and human failure events), plant damage states, containment challenges, and failure modes, shall be identified. The results shall be traceable to the inputs and assumptions made in the Fire PRAHLR-FQ-F: The documentation of CDF and LERF analyses shall be consistent with the applicable SRs Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 6Fire Risk QuantificationScope (per 6850/1011989)Task 14: Fire Risk QuantificationObtaining best-estimatequantification of fire riskStep 1: Quantify Final Fire CDF ModelStep 2: Quantify Final Fire LERF ModelStep 3: Conduct Uncertainty Analysis Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 7Task 14: Fire Risk QuantificationGeneral ObjectivesPurpose: perform final (best-estimate) quantification of fireriskCalculate CDF/LERF as the primary risk metricsInclude uncertainty analysis / sensitivity results (see Task 15)Identify significant contributors to fire riskCarry along insights from Task 13 to documentation, but this is not an explicit part of "quantifying" the Fire PRA modelCarry along residual risk from screened compartments and scenarios (Task 7); both (final fire risk and residual risk) are documented in Task 16 to provide total risk perspective Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 8Task 14: Fire Risk QuantificationInputs/OutputsTask inputs:Inputs from other tasks: Task 5 (Fire
-Induced Risk Model) as modified / run thru Task 7 (Quantitative Screening),Task 10 (Circuit Failure Mode Likelihood Analysis),Task 11 (Detailed Fire Modeling), and Task 12 (Post
-Fire HRA Detailed Analysis)
Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 9Task output:Output is the quantified fire risk results, including the uncertainty and sensitivity analyses, directed by Task 15 (Uncertainty and Sensitivity Analysis); all of which is documented per Task 16 (Fire PRA Documentation)Task 14: Fire Risk QuantificationInputs/Outputs (Cont.)
Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 10Task 14: Fire Risk QuantificationSteps in ProcedureFour major steps in the procedure*:Step 1: Quantify CDFStep 2: Quantify LERFStep 3: Perform uncertainty analyses, including propagation of uncertainty bounds, as directed under step 4 of Task 15Step 4: Perform sensitivity analyses as directed under step 4 of Task 15* In each case, significant contributors are also identified Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 11Task 14: Fire Risk QuantificationQuantification ProcessCharacteristics of the quantification process:Procedure is "general"; i.e., not tied to a specific method (event tree with boundary conditions, fault tree linking-)Can calculate CDF/LERF directly by explicitly including fire scenario frequencies or first calculate CCDP/CLERP and then combine with fire scenario frequenciesQuantify consistent with relevant ASME
-Sa-2009) supporting requirements Many cross
-references from FQ to internal events section (Part 2) for most aspects of risk quantification Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 12Task 14: Fire Risk QuantificationSteps in Procedure/DetailsStep 1 (2): Quantify Final Fire CDF/LERF ModelStep 1.1 (2.1): Quantify Final Fire CCDP/CLERP ModelCorresponding SRs: FQ
-A1, A2, A3, A4, B1, C1, D1, E1Final HRA probabilities, including dependenciesFinal cable failure probabilitiesFinal cable impactsStep 1.2 (2.2): Quantify Final Fire CDF/LERF FrequenciesCorresponding SRs: FQ
-A1-A4, B1, C1, D1, E1Final compartment frequenciesFinal scenario frequencies Final fire modeling parameters (i.e., severity factors, non
-suppression probabilities, etc.)
Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 13Task 14: Fire Risk QuantificationSteps in Procedure/Details (Cont.)Step 1 (2): Quantify Final Fire CDF/LERF Model (cont.)Step 1.3 (2.3): Identify Main Contributors to Fire CDF/LERF Corresponding SRs: FQ
-A1-A3, E1Contributions by fire scenarios, compartments where fire ignition occurs, plant damage states, post
-fire operator actions, etc.
Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 14Task 14: Fire Risk QuantificationSteps in Procedure/Details (Cont.)Step 3: Propagate Uncertainty Distributions Probability distributions of epistemic uncertainties propagated through the CDF and LERF calculationsMonte Carlo or Latin hypercube protocols Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 15Task 14: Fire Risk QuantificationSteps in Procedure/Details (Cont.)Step 4.1: Identification of Final Set of Sensitivity Analysis Cases Review sensitivity cases identified in Task 15Finalize sensitivity cases for Step 4.2 Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 16Task 14: Fire Risk QuantificationSteps in Procedure/Details (Cont.)Step 4.2: CDF and/or LERF Computations and ComparisonMean CDF/LERF values computed for each sensitivity analysis case considered in Step 4.1The results should be compared with the base
-case considered in Steps1 and 2 Fire PRA Workshop 2019, Rockville, MDModule 1: Internal Event, At
-Power PRA Model for SNPP Slide 17Mapping HLRs & SRs for the FQ Technical Element to NUREG/CR
-6850, EPRI TR 1011989Technical element HLR SR 6850/1011989 sections that cover SR Comments FQ A Quantification of the Fire PRA shall quantify the fire
-induced CDF
. 1 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 , 14.5.2.3 2 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 , 14.5.2.3 3 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 , 14.5.2.3 4 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 B The fire-induced CDF quantification shall use appropriate models and codes and shall account for method
-specific limitations and features
. 1 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 C Model quantification shall determine that all identified dependencies are addressed appropriately. 1 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 D The frequency of different containment failure modes leading to a fire
-induced large early release shall be quantified and aggregated, thus determining the fire-induced LERF 1 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 E The fire-induced CDF and LERF quantification results shall be reviewed, and significant contributors to CDF and LERF, such as fires and their corresponding plant initiating events, fire locations, accident sequences, basic events (equipment unavailabilities and human failure events), plant damage states, containment challenges, and failure modes, shall be identified. The results shall be traceable to the inputs and assumptions made in the Fire PRA 1 14.5.1.1, 14.5.1.2, 14.5.2.1 , 14.5.2.2 , 14.5.2.3 F The documentation of CDF and LERF analyses shall be consistent with the applicable SRs. 1 n/a Documentation not covered in 6850/1011989 2 n/a Documentation not covered in 6850/1011989