Exchange method for reactor inner structural member

A dryer and a shroud head are removed from the inside of a reactor pressure vessel (RPV) of a BWR type reactor, and they are stacked in a dryer and steam separator pool (DSP). Next, fuel assemblies, fuel support fittings, control rods and control rode guide tubes are successively removed and stored in an exclusive storage vessel. Then, guide rods are removed by cutting and temporarily placed in the DSP. Then, an upper lattice plate and a reactor core support plate are successively removed and temporarily placed in the DSP. Reactor core spray pipes are removed by cutting and temporarily placed in the DSP. Then, a shroud support cylinder is cut, and the shroud is removed and temporarily placed in the DSP. Subsequently, reactor water is drained, and a reactor core shroud to which the upper lattice plate and the reactor core support plate are previously disposed is suspended in the RPV, and the existent shroud support cylinder and the new reactor core shroud are welded. (I.N.)