The expected behaviour during the melt progression phase of the FPT4 experiment has been analysed assuming a molten pool geometry as a function of the deposited power in the debris bed. In case of low deposited power, leading to a limited radial expansion of the molten pool in the debris bed, the initial non uniformity of the debris bed have been assumed to slightly affect the molten material behaviour leading to a quasi axis-symmetrical geometry. In such a condition, the gas flow channel around the molten blockage appears as an annulus insulating the molten pool from the shroud inner surface. For higher deposited power, the molten material approaches the shroud enhancing the non uniformity effect on the pool geometry. The ideal gas flow channel is assumed to degenerate into a small bypass (chimney) at the outer boundary of the molten pool, allowing most of the molten pool external edge to contact the shroud inner surface. Specic ICARE2 calculations have been performed to simulate this described scenario, emphasising the assessment of the threshold power beyond which, in steady state conditions, there is no formation of a solid crust between the molten material and the flowing gas. The calculation assumptions and the obtained results, compared with the reference calculation, are described in the report. A brief comparison with the MERIS-3D calculation results, with similar assumptions concerning the gas bypass, is also given.

PHEBUS FPT4: Expected Behaviour during the Melt Progression Phase. Gas Chimney Simulation with ICARE2 V3 Mod0

Ederli, S.
1999-06-01

Abstract

The expected behaviour during the melt progression phase of the FPT4 experiment has been analysed assuming a molten pool geometry as a function of the deposited power in the debris bed. In case of low deposited power, leading to a limited radial expansion of the molten pool in the debris bed, the initial non uniformity of the debris bed have been assumed to slightly affect the molten material behaviour leading to a quasi axis-symmetrical geometry. In such a condition, the gas flow channel around the molten blockage appears as an annulus insulating the molten pool from the shroud inner surface. For higher deposited power, the molten material approaches the shroud enhancing the non uniformity effect on the pool geometry. The ideal gas flow channel is assumed to degenerate into a small bypass (chimney) at the outer boundary of the molten pool, allowing most of the molten pool external edge to contact the shroud inner surface. Specic ICARE2 calculations have been performed to simulate this described scenario, emphasising the assessment of the threshold power beyond which, in steady state conditions, there is no formation of a solid crust between the molten material and the flowing gas. The calculation assumptions and the obtained results, compared with the reference calculation, are described in the report. A brief comparison with the MERIS-3D calculation results, with similar assumptions concerning the gas bypass, is also given.
Analisi sistemi e di sicurezza
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12079/6467
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