RIC2011 MELCOR DEVELOPMENT STATUS AND CODE APPLICATIONS MELCOR Regulatory Applications
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RIC2011 MELCOR DEVELOPMENT STATUS AND CODE APPLICATIONS MELCOR Regulatory Applications
RIC2011 MELCOR DEVELOPMENT STATUS AND CODE APPLICATIONS Hossein Esmaili USNRC/RES March 9, 2011 1 MELCOR Regulatory Applications • State of the Art Reactor Consequence Analysis (SOARCA) • MOX/HBU Source Term (revised NUREG-1465) • Design Certification for New and Advanced Reactor Designs • BWR MSIV Leakage L k Analysis A l i (RG 1.183) 1 183) • Risk-Informed Regulation (e.g., combustible gas control rulemaking) • Probabilistic Risk Assessment (e.g., standardized plant analysis risk [SPAR] models) 2 MELCOR User Community • Strongly Influenced by Participation of Domestic Users and International Partners through the USNRC Cooperative Severe Accident Research Program (CSARP) and MELCOR Code Assessment Program (MCAP) – Development Contributions (new models) – Applications – Development Suggestions 3 1 MELCOR Models 4 MELCOR Nodalization Generic Models (no “built-in” nodalization) Building block approach (more flexibility =>greater user responsibility) 5 MELCOR Development Code life-cycle Code Readiness code conversion phase code ready for applications code not readyfor applications code development phase code maintenance phase V1.8.6 F 77 YG YH YI Double Precision V 2.0 F 95 YJ YI YN YP YR YP YT Double Precision YT YT V 3.0 FY 06 • MELCOR 1.8.6 –Molten pool models –Core Package upgrade –Released Fall 2005 –Code Maintenance FY 07 • MELCOR 2.1 –FORTRAN 95 –New input –2.0 beta version released Sept 2006 –2.1 Release Sept 2008 FY 08 • MELCOR 3 –Current developmental version 6 2 MELCOR Development Focus Code reliability Validation QA Numerical stability MELCOR Code Development User Utilities Code Enhancements Converter (input) PTFREAD (plotting) SNAP Uncertainty Engine New/improved modeling Code performance 7 Accident Simulation Using SNAP Containment DBA application View Results Sensitivity Calculations Severe accident application Source term DBA application User Control/Options • Plant systems (SA) • Operator actions (SA) • Type of accident (SA) • DBA Sources (M/E,FP) • etc. MELCOR Plant Model (i.e., fixed geometry, etc.) Transparent to User Phase I BWR (e.g.,ABWR) Phase II PWR (e.g., EPR) Phase III PRA Applications Generate MELCOR input model Run MELCOR SNAP GUI Boundary for User Access 8 MELCOR Interactive Systems Supports communication between SNAP and MELCOR using the Read and L-Read control functions in the safety system logic to initiate, fail, or adjust system functionality (required enhancing models and safety system details). Animation package reads the plot data and performs display function. Simple and complex elements are used to display pertinent information from the MELCOR run. Interactive commands are communicated from the display page to MELCOR . 9 3 EPR MELCOR Model Steady-State SG dryout & core relocation Lower head failure Core relocation to lower head 10 ABWR MELCOR Model Short term station blackout progression Steady-State Core uncovery Core Degradation Core Heatup Safety valves actuation 11 HTGR FP Release and Transport • Develop HTGR specific fission product release and transport models for MELCOR Use existing MELCOR modeling framework for fission product transport and deposition in the primary system and containment. Develop HTGR specific models (i (i.e., lift-off, lift ff turbulent t b l t deposition, agglomeration, dust) Implement diffusional release models for both intact and failed TRISO fuel particles (also for matrix and graphite block) 12 4 PRA Application • Improve the technical basis for, and increase the consistency of, Standardized Plant Analysis Risk (SPAR) models for selected probabilistic risk assessment (PRA) sequences of interest. Results published as NUREG-1953 (draft report for comment). Plant Information Final Safety Analysis A l i Report MELCOR Model Plant Operating Procedures SPAR Model Confirmation or Upgrade Thermal Hydraulic Analysis 13 Summary • MELCOR ongoing code development and enhancement in response to regulatory needs and user participation • Code flexibility allows its use for a variety of applications • MELCOR/SNAP integration provides an easy to use graphical user interface for accident simulation and visualization 14 Acronyms • • • • • • • • • • • • • • • • • • BWR DBA ECCS FP GUI HTGR LOCA M/E PORV PRA PWR QA RCP SA SG SNAP SPAR SRV Boiling water reactor Design basis accident Emergency core cooling system Fission product Graphical user interface High temperature gas reactor Loss of coolant accident Mass/Energy (sources) Power (or pilot) operated relief valve Probabilistic risk assessment Pressurized water reactor Quality assurance Reactor coolant pump Severe accident Steam generator Symbolic nuclear analyzer package Standardized plant analysis risk Safety relief valve 15 5