Analysis of resistance effect on core flow distribution

Three dimensional CFD analysis is performed for the region from reactor inlet to core outlet of FBR type reactor. From the analysis, it is found that the inlet geometry and core design determine unique core flow characteristics. The resistance coefficient, however, needs attention in design process since it decides pressure drop that has direct effect on flow distribution. With linear overall change of resistance coefficients, central group of fuel assembly shows little effect on flow distribution while outer group of fuel assembly shows significant change. The resistance coefficients change for the central group only results strong effect on flow distribution. The change for outer group only shows immediate change of flow distribution for this region, however, spreading its effect to other groups takes time to result uneven flow distribution. Overall pressure drop determines the core flow distribution, thus design of resistance coefficients for inlet plenum assembly duct and receptacle orifice can be effective tool to induce uniform flow and temperature distribution. (author)