Critical Power Experiments of Tight Fuel Rod Lattice for Light Water Reactors

Abstract This paper deals with the results of critical power experiments performed simulating commercial BWR conditions at Hitachi Core and Fuel Test Loop with seven fuel-rod heater bundles in a tight triangular lattice array, which is assumed to be used in high conversion BWRs. The main conclusions of experiments are; (1) The critical power in high conversion BWR fuel bundles in a tight triangular lattice array showed almost the same dependence on operating conditions, namely mass flux, pressure, inlet subcooling etc., and the critical power can be accurately correlated by critical quality and boiling length relation as in current BWR fuel bundles in a loose square lattice array, (2) A correlation to predict the critical power in high conversion BWR fuel bundles was obtained from the experimental results, and the predicted results by the correlation were summarized as,