[en] A new design feature of DVI+, to mitigate an ECC bypass fraction and to prevent switching an ECC inlet to a break outlet during a DVI line break, is presented for an advanced DVI system. The injected ECC water into the downcomer is easily shifted to the broken cold leg by a high steam cross flow which is coming from the intact cold legs during the late reflood phase of a LBLOCA with a smooth annulus of the downcomer in the current DVI system. The performance of the ECC penetration duct is evaluated by LOCA PCT behaviors for a LOCA and an ECC penetration flow shape for a nominal working condition. The MARS code and CFX code are applied for this evaluation