A simplified theoretical model for bubble nucleation stability has been proposed, and an approximate stability criterion has been developed. This criterion contains both fluid and surface properties, and it predicts that nucleation for sodium should be unstable. Commercial-grade sodium was boiled from a horizontal disk at pressures near 60 mm Hg absolute, with sodium temperatures near 1200 F. Heat fluxes as high as 236,000 Btu/hr ft2 were attained. Boiler surface finishes ranged from highly polished mirror finishes to coarse, porous coatings. The effects of surface material, chemical treatment, heat flux, and cavity geometry on nucleation stability were measured, and the experimental results agreed with the predictions of the proposed stability model.

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