Hydraulic characteristics of "Joyo" irradiation test assembly(V); Flow distribution in A-Type fuel assembly

not registered; not registered; Abe, Sadayoshi*; Iguchi, Tatsuro*

The A-type fuel assembly has two kinds of irradiation ducts which contain "Monju" and "Joyo" MK-II fuel pin arrays. In this experiment, measurement test of pressure loss coefficient and electrolyte injection test were conducted for both individual elements and assembly. The experimental data can be used to calculate the coolant flow distribution in the A-type fuel assembly. The main conclutions from this experiment are as follows. (1)A wide gap is formed around the irradiation duct when the "Joyo" MKII type irradiation duct is used. The gap should be narrowed by some design improvement to decrease leakage flow. (2)The size of the orifice at the entrance region of the "Monju" type irradiation duct can be determined by using the pressure loss coefficients led from experimental results. (3)The experimental results for flow distribution rates in the irradiation ducts have rather big experimental errors because of the test method to know the rates in the small ducts from the pressure drop in the large driver bundle. Therefore, it is desirable to know correctly thermal-hydraulic characteristics of the assembly by using TED (Temperature Difference) thermometers at the first irradiation.