Experimental identification for flow distribution inside APR+ reactor vessel and direction of internal structure design improvement

A test program to quantify the reactor flow distribution has been performed using a test facility, named ACOP, having a 1/5 length scale referring to the APR+ reactor design. The flow characteristics of the prototype plant could be preserved by designing the test facility by adopting a linear reduced scaling principle. An Euler number is considered as a primary dimensionless parameter, which was preserved with a 1/41.0 Reynolds number scaling ratio based on the balanced flow conditions. The important measuring parameters are the core inlet flow, outlet pressure distribution, and sectional pressure drops along the major flow path inside the reactor vessel as well as static pressure and temperature at the vessel and boundary legs. The reactor flow distribution is identified by a series of three reactor flow balancing conditions: (1) balanced cold leg flow condition (2) 5% unbalanced cold leg flow condition, and (3) extreme unbalanced flow condition under the assumption of a single pump failure. This paper describes the design features for the test facility and the measuring method, and summarizes the reactor flow and pressure characteristics by ensemble averaging for each group of tests.