High temperature properties of nuclear reactor coolants and thermodynamic power cycle working Fluids

The surface tension of sodium to high temperatures is being studied using an all-molybdenum maximum-bubble-pressure apparatus suitable to some 1900 K. This property bears on boiling, condensing and two-phase flow phenomena, also related to LMFBR analysis. This same apparatus will be useful with lithium, of interest in fusion reactor cooling. Reduction of prior maximum bubble pressure results on potassium by the Schroedinger method was repeated by the more precise but time-consuming Sugden procedure, which increased the resulting surface tension values by an average of 0.27 percent. Thus, the Sugden method will be employed to reduce the data for sodium and lithium.