The design of fast reactor boilers

The paper reviews the various styles of steam generators being considered by design teams throughout the world and draws attention to the properties of the tube materials needed to meet the designers' requirements. The various candidate materials now under consideration are examined in the light of these requirements notably strength and the various corrosion phenomena to which they may be subjected and highlights the present uncertainties associated with each of those materials. Recommendations are made for the development work needed to resolve these uncertainties. In the light of present information, however, it is concluded that the best choice of boiler style for a fast reactor is the once-through helically wound tube system having a monometallic tabulation and Alloy 800 is recommnded as the preferred material. To take advantage of the good stress-corrosion resistance of the low carbon stabilised version of this alloy in the Grade 1 condition and yet avoid the low creep ductility of this type at the design temperatures, it is suggested that the best compromise is to specify this low carbon alloy but with controlled total aluminium and titanium content and in the high temperature (Grade 2) heat-treated condition. (author)