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FPTRAN: A Volatile Fission Product and Structural Material Transport Code for RELAP

OUTLINE. IntroductionDevelopment of the ModelNumerical TreatmentPhenomena modelingImplementation into RELAP/SCDAPSIM/MOD3.2ConclusionsDevelopment of a model to predict the transport of released fission products through the RCS, and to calculate the quantities each FP product deposited in the RCS and released to the containment.

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FPTRAN: A Volatile Fission Product and Structural Material Transport Code for RELAP

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    1. FPTRAN: A Volatile Fission Product and Structural Material Transport Code for RELAP/SCDAPSIM EDUARDO HONAISER (Brazilian Navy Technological Center) SAMIM ANGHAIE (University of Florida)

    2. OUTLINE Introduction Development of the Model Numerical Treatment Phenomena modeling Implementation into RELAP/SCDAPSIM/MOD3.2 Conclusions Development of a model to predict the transport of released fission products through the RCS, and to calculate the quantities each FP product deposited in the RCS and released to the containment

    3. Fission Product Behavior

    4. Fission Product Transport (Scope) Vapor phenomena Adsorption Condensation Onto structures Onto aerosol surfaces Aerosol nucleation Aerosol Phenomena Deposition Agglomeration Re-suspension

    5. Characteristics of the Model Fixed speciation Phenomenological and convection model limited to piping system (upper plenum not considered) Decay heat of deposited FP not considered Mechanistic model for aerosol nucleation

    6. Analytical Equations Vapor species Aerosol Species

    7. Transition Analytical-Numerical

    8. Numerical Equations Bulk states (vapor+aerosol sections) Surface states (condensed, absorbed, and deposited) Total number of equations of the system: Sx(B+1+3N)

    9. Vapor-Structural Surface Laminar flow (Re<2300) Leifshitz model (1962) Turbulent flow

    10. Vapor-Aerosol Processes Homogeneous nucleation Heterogeneous nucleation

    11. Nucleation Pattern Experimental evidence PBF-SFD and Phebus-FP experiments Procedure Calculate selectively nucleation rate for Ag and U Select a model for homogeneous nucleation Obtain the particle critical size, defining lower particle size as spectrum limit

    12. Homogeneous Nucleation Models Analytical Models Classical theory (Becker-Doring (1935) Kinetic theory (Girshick et al (1990)

    13. Heterogeneous Nucleation Approach Diffusion Continuum region (Kn<<1) Near Continuum region (Fuchs and Stuggin correction)

    14. Aerosol Processes Assumptions Aerosol spherical shape Empirical evidence PBF-SFD and Phebus experiments Synergy Mathematical

    15. Aerosol-Surface Gravitational Using the concept of mobility Upper limit of the spectrum: 50 ?m Laminar diffusion Gormley and Kennedy (1954)

    16. Early Models (theoretical) Friedlander (1957), Davies (1966) and Beal (1968) Semi-empirical model (Sehmel-1970) Empirical Models Liu (1974), Iam and Chung (1983), Chiang (1996) Aerosol-Surface (Turbulent)

    17. Aerosol-Surface (Thermophoresis) Principle (Continuum) Brock Solution (1962)

    18. Other Models

    19. Aerosol-Aerosol (Agglomeration) Brownian agglomeration Approach (continuum) Target particle flux from other particles Equation Boundary conditions Continuum/near continuum region

    20. Aerosol-Aerosol (Agglomeration) Differential gravitational Simplified model Realistic model Consider the fluid trajectories Approximations Fuchs (1964) Pruppacher and Klett (1978)

    21. Turbulent agglomeration Processes Diffusivity (small particles) Inertial (large particles) Approaches Leifshitz (1962) Solution of diffusion equation Saffman and Turner (1956) Statistic approach for turbulence Aerosol-Aerosol (Agglomeration)

    22. Implementation Implementation in RELAP/SCDAPSIM/MOD 3.2

    23. Verification Robustness of the math solver, positive masses Global mass error (OK) Sensitive studies Synergy

    24. Stability

    25. Conclusions A FP transport model was developed, using a system of mass balance equations of first order Aerosol size was treated by a discrete ordinate approach, the convective term was treated using the fractional step method ODE system was solved using Hindmarsh package Phenomenological models: Condensation onto structural surfaces Condensation onto aerosol surfaces Aerosol homogeneous nucleation Aerosol deposition Gravitational settling, laminar diffusion, turbulent diffusion, thermophoresis Aerosol Agglomeration Diffusive, turbulent, and due to gravitational difference Additional models Aerosol Re-suspension, deposition onto singularities, vapor adsorption

    26. Conclusions

    27. Acknowledgments Dr. Chris Allison and Dick Wagner for their support and the use of RELAP/SCDAPSIM for this project

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