Estimation for side flow holes of an end-plug in a dual-cooled annular fuel

A dual-cooled annular fuel for a PWR has been introduced for a significant increase in reactor power. KAERI has been developing a dual-cooled annular fuel for a power uprate of 20% in an optimized PWR in Korea, an OPR1000. Several thermal-hydraulic issues exist for the application of dual-cooled annular fuel. One of the key issues is the hypothetical event of inner channel blockage because the inner channel is an isolated flow channel without coolant mixing between the neighboring flow channels. A conceptual design used to complement the entrance blockage of an inner channel was suggested by KAERI. A long lower end plug for the annular fuel is invented to provide flow holes by perforating the side surface of the end plug body. Experiments and a numerical analysis were performed to investigate the bypass flow through the side holes of the lower end plug to complement the entrance blockage of an inner channel. In this study, An experiment with a single annular rod within a round tube is performed to measure the form loss coefficient of the side holes in the long lower end plug, and a numerical study was performed to estimate the parametric sensitivity of the geometric effect. (author)