Investigation of preventive measures of gas entrainment phenomena for large scale FBR; Investigation on Baffle ring and porous-type UIS

not registered; not registered; Yamaguchi, Akira; not registered; not registered; Sugawara, Satoru

In-vessel thermohydraulic analysis with multi-dimensional code AQUA was conducted to investigate efficiency of a baffle ring and of a porous-type UIS (upper instrumentation structure) for preventation of gas entrainment to coolant from gas plenum of reactor vessel. Through the analysis using the AQUA code and the discussion based on their results, the following results have been obtained: [Baffle Ring Equipment] (1)In order to reduce maximum surface verocity, the effect with the width 40 cm of the baffle ring equipment better than the width 20 cm. (2)Maximum surface velocity is 40 cm/s using the baffle ring equipment of width 40 cm. [Porous-type UIS] (1)Effective mass flow ratio of the UIS porous to the UIS skirt is 50 % to decrease maximum surface velocity. (2)Maximum surface velocity is 52 cm/s using the porous-type UIS with the above mass flow distribution. Furthermore analysis with the AQUA code were carried out for the conbined condition of the baffle rings with 40 cm width and the porous-type UIS with the condition of the effective mass flow ratio 50 %. Maximum surface velocity 0.33 m/s closer to the MONJU condition (0.3 m/s) was obtained from the analysis.