Calorimetry Servo Control Evaluation

Heat flow calorimeters have been used at Mound for over forty years to assay quantities of radioactive materials. To reduce assay times calorimeters are often servo controlled to hold the temperature of the sample chamber constant. To achieve optimum operation of the calorimeter (short assay times with high accuracy) servo control parameters must be tuned, based on calorimeter design and sample characteristics. In this study three methods of servo controlling a calorimeter were investigated: a commercially available self tuning controller; a currently used computer based servo control algorithm; and a new computer algorithm. Each method of control was evaluated based on measurement time (prediction-equilibration), measurement accuracy, and the advantages-disadvantages of each method.