METHOD FOR REPLACING NUCLEAR REACTOR INTERNAL CONSTITUTION

PURPOSE: To contrive the reduction of a construction period, exposure reduction of workers, cost reduction or the like by establishing a method for replacing a shroud, an upper lattice plate and a reactor core support plate in accordance with a specific procedure. CONSTITUTION: A reactor pressure vessel upper cover 28, a drier 10 and a shroud head 11 are removed, and superimposed on DSP. Next, the whole fuel is taken out in a fuel pool, and removal is performed in order of control rods 12, control rod guide tube 13, guide rods, reactor core spray tubing 14, shrouds 2, an upper lattice plate 4 and a rector core support plate 5. Next, differential pressure reduction tubing 5 and SLC17 are cut and removed. After removal work completion reactor water is drained, the plates are previously centered, a new rector core shroud and a shroud support ring are welded and mounted on each other. After reactor core shroud installation completion the inspection of a welding part is performed by a remote-controlled inspection instrument, the tubing 5, SLC17 and the tubing 14 are restored by a remote-controlled specialized device, the devices for removing at the time of ordinary periodical inspection are set to the previous positions, and the whole working is completed.