Lower tie plate of fuel assembly

Object: To prevent leakage of a cooling medium through reduction of the difference between the inner and outer pressures on the lower portion of a channel box by providing a nozzle section at a cooling medium outlet of a lower tie plate. Structure: A cooling medium passage where a fuel rod end plug of a lower tie plate is secured is made in the form of a nozzle. In this way, a portion of the dynamic pressure of the total pressure of the cooling medium is increased to reduce the static pressure portion so as to reduce the difference between the inner and outer pressures on the lower portion of a channel box lower for preventing the leakage of the cooling medium. (Kamimura, M.)