In order to increase the usefulness of the nuclear research reactor, it is necessary to enhance the neutron fluxes available in the experimental facilities. One method of attaining this objective is to increase the power level of the reactor. The VPI&SU 100 KW research reactor has been studied to investigate the feasibility of operation of 500 KW. From a thermal-hydraulic point of view, the following limiting conditions should not be exceeded for a 500 KW operation: 1) bulk boiling of the coolant should not occur, 2) surface boiling should not occur on any fuel plate, 3) fuel meltdown must not occur after a loss-of-flow or loss-of-coolant accident, 4) fuel plate vibration problems should not be significant. The results of the investigation indicate that the above limiting conditions will not be exceeded provided that certain system modifications are made. Thus the operation of the VPI&SU reactor at 500 KW is feasible as far as thermal-hydraulics is concerned. / Master of Science