To enhance cooling efficiency in a core by equalizing the flow speed of cooling water inside a downcomer, where the core is located.
This reactor is equipped with an inner cylinder 2 surrounding the outer periphery of the core, an outer cylinder 1 that is placed concentrically outside of the inner cylinder 2 and has a space 3, an inlet nozzle 5 that is inserted between the inner cylinder 2 and the outer cylinder 1 from the outside of the latter and enables the cooling water to flow into the space 3, a partition board 7 placed in an interstice and an outlet nozzle 6 that is inserted into the inner cylinder 2 from the outside the outer cylinder 1 and allows the cooling water flowing through the space 3 into the inner cylinder 2 to be released to the outside. The partition board 7 makes it possible to improve the uniformity of the flow speed in the interstice, and to enhance the cooling efficiency in the core in the inner cylinder 2.
TAKADA TOMONARI
NAGANO TERUYUKI
