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RIC 2009 MELCOR Analyses to Address Regulatory Issues: Evaluation of System Success Criteria

RIC 2009 MELCOR Analyses to Address Regulatory Issues: Evaluation of System Success Criteria. Hossein Esmaili USNRC March 12, 2009. Containment. Safeguards Building. Auxiliary Building. Reactor w/ RCS. MELCOR Modeling Approach . Generic Models (no “built-in” nodalization).

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RIC 2009 MELCOR Analyses to Address Regulatory Issues: Evaluation of System Success Criteria

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  1. RIC 2009 MELCOR Analyses to Address Regulatory Issues: Evaluation of System Success Criteria Hossein Esmaili USNRC March 12, 2009

  2. Containment Safeguards Building Auxiliary Building Reactor w/ RCS MELCOR Modeling Approach Generic Models (no “built-in” nodalization) Building block approach (more flexibility =>greater user responsibility)

  3. Westinghouse AP-1000 Design Certification • Severe accident response and source term • Containment response to design basis accident US APWR US EPR ESBWR

  4. Success Criteria Application • Staff Identified Inconsistencies in Similar-Plant SPAR Model Success Criteriafor Currently Operating Reactors • Use MELCOR for Thermal-Hydraulic Analysis • Surry (PWR) and Peach Bottom (BWR) models from State-of-the-art Reactor Consequence Analysis (SOARCA) • Definition of core damage (e.g., 2200 F) • Code calculations for various scenarios to define success criteria • Collaborative Effort • Project Management: Don Helton • Calculation Matrix: Don Dube, Rick Sherry, et al. • Systems Analysis Support: Don Marksberry • MELCOR Analysis: Hossein Esmaili • SPAR Model: Pete Appignani, INL

  5. Surry Calculation Matrix • Small LOCA dependency on sump recirculation • Effect of sprays on RWST depletion • Does the system depressurize (and how fast)? • Feed & Bleed PORV success criteria • Combination of HHSI and PORVs • Steam Generator Tube Rupture • Multiple tube ruptures • Impact of secondary cooling, HHSI, forced cooldown • Station blackout • Investigating time available for A/C power recovery • Both small and large RCP leaks with and without TD-AFW • Accumulator injection • Spectrum of LOCA sizes • Availability of HHSI/LHSI in conjunction with number of accumulators

  6. Peach Bottom Calculation Matrix • SRV/RCIC • Can RCIC maintain cooling until low pressure system injects? • Station blackout (RCIC/HPCI availability) • Investigating time available for A/C power recovery • Suppression pool heatup and pump NPSH limit HPCI RCIC

  7. Concluding Remarks • Application of MELCOR to Obtain Consistent System Success Criteria for Representative PWR (Surry) and BWR (Peach Bottom) Plants • Use the Thermal-hydraulic Results to Develop a More Extensive Technical Basis for the SPAR Models • Possible Extension to Other Plants (e.g., ice condenser) as Input Models Become Available

  8. Acronyms • A/C Alternating Current • HHSI High-Head Safety Injection • HPCI High Pressure Coolant Injection • LHSI Low-Head Safety Injection • LOCA Loss-of-Coolant Accident • NPSH Net Positive Suction Head • PORV Power (or Pilot) Operated Relief Valve • RCIC Reactor Core Isolation Cooling • RWST Refueling Water Storage Tank • SGTR Steam Generator Tube Rupture • SPAR Standardized Plant Analysis Risk • SRV Safety Relief Valve • TD-AFW Turbine-Driven Auxiliary Feedwater

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