Patent Number: 
Section: abstract

An old core shroud (11) and an old jet pump (16) received in a reactor pressure vessel (1) are cut and carried out. A module of core internals having a new core shroud (N11), a new jet pump (N16) and a new baffle plate (N29) integrated is carried into the reactor pressure vessel (1) in which an old baffle plate (28) and an old shroud support cylinder (13) welded and fixedly secured to the reactor pressure vessel (1), and an old shroud support leg (12) fixedly secured to said old baffle plate (28) and said old shroud support cylinder (13) are left. Then, the new baffle plate (29) is fixedly secured to the old baffle plate (28), and the new core shroud (11) is fixedly secured to the old shroud support leg (12).