Thermalhydraulics in reactor vessel of pool-type FBR

The most important problem in the thermalhydraulic designs of the pool-type FBR is to estimate the thermal cinditions affecting the vessel or internal structures during both steady and transient operations. The severity of these conditions in the Japanese pool-type reactor which will be reinforced and equipped with special devices for aseismic demands are apt to be much greater than other countries. Water tests and thermalhydraulic analyses have been performed to study such conditions. The main purpose of this study in to estimate the effects of the elevation of UIS (Upper Internal Structure) discharge and IHX (Intermediate Heat Exchanger) intakes on flow patterns, free surface disturbance and thermalstratification in hot plenum. Form the results of the experiments, suitable arrangements of such elevations could be recommended by comparing some thermalhydraulic characteristics. The calculations agreed well with the experimental results on the steady-state flow patterns and thermal-transients except the thermal-stratification. (author)