The enthalpy of the reduction of UO2F2 with hydrogen was obtained from quantitative DTA measurements with a linear heating rate and under isothermal conditions, and the thermodynamic data on UO2F, formed as a stable intermediate in the reduction of UO2F2 to UO2, are also presented. The advantages of isothermal DTA in the reduction of U3O8 to UO2 could be demonstrated.
The mathematical theory is developed for heat transfer in the cells of DTA instruments with no temperature gradient. Equations are derived for the various portions of the differential curve. The concepts of real and hypothetical base lines are introduced and rules are formulated for plotting them. Three methods are proposed for processing the curves, with and without the introduction of base lines. The physical meanings of the geometrical elements of the thermal curves and their relationship with the experimentally determined thermal quantities are elucidated. Equations in differential and integral forms are derived for the base line of the cell and the base line of the reaction.