Date of Award


Degree Type


Degree Name

Master of Science (MS)


Electrical and Computer Engineering

Committee Chair(s)

William L. Jones


William L. Jones


Bruce O. Watkins


Ronald L. Thurgood


The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory experiences occasional operating difficulties caused by temporary low voltage conditions on its main power feeder line. The low voltage causes the shutdown of one or more of the three primary coolant pumps. When two of these pumps are shut down, the capacity of the cooling system is reduced to the point where the reactor is scrammed due to a high inlet coolant temperature.

This study was made to determine the cause of the high inlet temperature when operating with one primary coolant pump and to suggest possible changes in the system or its operation to eliminate the undesired shutdowns.

Three methods are suggested for elimination or reduction of the scrams: (1) Cross connect the suction side of the primary coolant pumps so any pump can circulate coolant through all three heat exchangers; (2) Reduce the power to flow ration of the reactor if the coolant flow drops below a set value; (3) Put two primary pumps and one secondary pump on each of the two feeder power lines to reduce the possibility of having more than one pump shut down. Combinations of these methods are also possible.