On the mechanisms associated with the chemical reactivity of Be in steam

One safety concern surrounding beryllium as a plasma-facing material in a water-cooled Tokamak is steam interactions with hot beryllium and the production of significant quantities of hydrogen. We have tested several different product forms of Be with different densities and levels of porosity. Oxidation kinetics has been determined by measurements of hydrogen release with a mass spectrometer, volumetric measurements of the product gas and weight change of the sample. We discuss and compare with the literature the fundamental mechanisms and kinetics controlling the oxidation of Be in steam. Fully dense beryllium exhibits parabolic, linear and accelerating modes of oxidation as temperature increases from 450°C to 1200°C. The oxidation mechanisms and temperature trends are similar for other product forms. Oxidation rates are higher, however, when processing or annealing significantly increases the extent of interconnected porosity and consequently the effective surface area. The effective surface area as measured by BET surface analyses is a key parameter when comparing oxidation rates.

[1]  S. J. Gregg,et al.  The high temperature oxidation of beryllium. Part III In carbon dioxide, carbon monoxide and carbon monoxide-carbon dioxide mixtures , 1961 .

[2]  Brad J. Merrill,et al.  Reaction of porous beryllium in steam , 1992 .

[3]  J. E. Burke,et al.  The metal beryllium , 1955 .

[4]  O. Kubaschewski,et al.  Oxidation of metals and alloys , 1953 .

[5]  S. J. Gregg,et al.  The high temperature oxidation of beryllium: Part I. In dry oxygen , 1960 .

[6]  V. Alimov,et al.  Gas swelling and related phenomena in beryllium implanted with deuterium ions , 1996 .

[7]  M. Bennett,et al.  The oxidation of irradiated beryllium in carbon dioxide , 1965 .

[8]  J. Thome,et al.  Convective Boiling and Condensation , 1972 .

[9]  J. Roth,et al.  Release of Deuterium from Carbon-Deuterium Films on Beryllium during Carbide Formation and Oxidation , 1997 .

[10]  J. D. Spencer,et al.  Fly ash utilization. Proceedings: Edison Electric Institute-National Coal Association-Bureau of Mines Symposium, Pittsburgh, Pennsylvania, March 14--16, 1967. [Thirty-two papers] , 1967 .

[11]  S. J. Gregg,et al.  The high temperature oxidation of beryllium: Part II the reaction with carbon dioxide and with carbon monoxide , 1960 .

[12]  S. J. Gregg,et al.  The high temperature oxidation of beryllium. Part IV In water vapour and in moist oxygen , 1961 .

[13]  S. J. Gregg,et al.  The high temperature oxidation of beryllium: Part V In moist carbon dioxide and moist carbon monoxide , 1961 .

[14]  G. Holcomb.  Countercurrent Gaseous Diffusion Model of Oxidation Through a Porous Coating , 1996 .

[15]  M. Enoeda,et al.  Measurements of breakaway reaction between beryllium and water vapor for ITER blanket design , 1992 .