Scaling Methodology for the Direct ECC Bypass During LBLOCA Reflood Phase With Direct Vessel Injection System: Its Development and Validation

From the two dimensional two-fluid model a new scaling methodology, named the “modified linear scaling”, is suggested for the scientific design of a scaled-down experimental facility and data analysis of the direct ECC bypass under LBLOCA reflood phase. The characteristics of the scaling law are its velocity is scaled by a Wallis-type parameter and the aspect ratio of experimental facility is preserved with that of prototype. For the experimental validation of the proposed scaling law, the air-water tests for direct ECC bypass were performed in the 1/4.0 and 1/7.3 scaled UPTF downcomer test section. The obtained data are compared with those of UPTF Test21-D. It is found that the modified linear scaling methodology is appropriate for the preservation of multi-dimensional flow phenomena in downcomer annulus, such as direct ECC bypass.