Hitachi, Ltd.

Other

Hitachi-ge Nuclear Energy, Ltd.

Masataka Aoki

Takahiro Adachi

Kouichi Ushiroda

Hiroshi Hasegawa

Akinori Tajiri

Jun Miura

Ryohei Miyahara

Katsumi Kobayashi

Junichi Kawahata

Norihito Saitou

Kazunori Izumi

Mitsuo Kuroha

Norihito Saito

A method for carrying out a reactor internal, comprising steps of:

Method for carrying out reactor internal

When carrying the large structure out through an aperture portion provided at a roof of a reactor building, a chamber for covering the aperture is provided at the roof so that work of providing the chamber for covering the aperture portion can be performed independent of other work performed in the reactor building. At least a part of the work of using a roof crane, and at least a part of the work of handling fuel assemblies in the reactor building can be performed in parallel with forming the roof aperture.

Method of handling a large structure in a reactor building

A method of carrying equipment out of a nuclear reactor building that, in carrying equipment rendered radioactive out of a nuclear reactor building, makes it possible to shorten the operating time and reduce the number of casks to be used, wherein the structures of a nuclear power plant that are outside the equipment installed in the nuclear power plant are removed and these removed structures are then stored in the space in the equipment and carried out of the building.

Method for carrying equipment out of nuclear power plant

One of methods for carrying out a reactor vessel according to the present invention comprises the steps of removing an overhead traveling crane in a reactor containment vessel of a pressurized water reactor, or the steps of, in an area where an overhead traveling crane is installed, operating the overhead traveling crane to move aside for creating a space, through which the reactor vessel is able to pass, and then carrying out the reactor vessel through an opening provided in a top portion of the reactor containment vessel. With the present method, the reactor vessel of the pressurized water reactor can be carried out in a short time with high efficiency.

Reactor vessel handling method

In order to carry out a radioactivated reactor pressure vessel from a nuclear reactor building of a nuclear power plant, a first opening portion for carrying out the reactor pressure vessel is provided in a roof of the nuclear reactor building. A radiation shield for covering the reactor pressure vessel and shielding radiations is carried into the reactor building through the first opening portion, and installed on a reactor shield wall. A hanger is lowered through the first opening portion and a slit provided on an upper lid of the radiation shield. A portion of a lid of the reactor pressure vessel and a portion of the upper lid of the radiation shield are abutted by hanging up the reactor pressure vessel by the hanger. The reactor pressure vessel and the radiation shield integrated therewith are raised and carried out of the reactor building, whereby the shield can be easily mounted on the large-sized apparatus in a short time and a dose of radiation exposed to a worker when the shield is mounted can be reduced.

Method of removing a large-sized apparatus from a reactor building of a nuclear plant

A method of carrying out a reactor vessel according to the present invention includes removing an overhead traveling crane in a reactor containment vessel of a pressurized water reactor. Alternatively, in an area where an overhead traveling crane is installed, operating the overhead traveling crane to move aside for creating a space, through which the reactor vessel is able to pass. Then the reactor vessel is carried out through an opening provided in a top portion of the reactor containment vessel. With the present method, the reactor vessel of the pressurized water reactor can be carried out in a short period of time with high efficiency.

Method of handling reactor vessel

When carrying the large structure out through an aperture portion provided at a roof of a reactor building, a chamber for covering the aperture is provided at the roof so that work of providing the chamber for covering the aperture portion can be performed independent of other work performed in the reactor building, before at least a part of work of using a roof crane and at least a part work of handling fuel assemblies in the reactor building.

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

Mounting method for core internals

When a radioactivated reactor pressure vessel is carried out from a nuclear reactor building of a nuclear power plant, a first opening portion for carrying out the reactor pressure vessel is provided in a roof of the nuclear reactor building, a radiation shield for covering the reactor pressure vessel and shielding radiations is carried into the reactor building through the first opening portion, and installed on a reactor shield wall, lowering a hanger through the first opening portion and a slit provided on an upper lid of the radiation shield, a part of a lid of the reactor pressure vessel and a part of the upper lid of the radiation shield are abutted by hanging up the reactor pressure vessel by the hanger, and the reactor pressure vessel and the radiation shield integrated therewith are raised and carried out of the reactor building, whereby the shield can be easily mounted on the large-sized apparatus in a short time and a dose of radiations exposed to a worker when the shield is mounted can be reduced.

Method of carrying out large-sized apparatus

A cask is lifted from outside of a nuclear reactor building through an opening which is opened at a portion of the nuclear reactor positioned just above a nuclear reactor pressure vessel. By maintaining the cask under a lifted condition a shroud which is an internal structure of the nuclear reactor is transferred and inserted to the cask from the nuclear reactor vessel. After that, an inlet port of the cask is closed, and the cask together with the shroud is lifted outside of the nuclear reactor building through the opening. The internal structure of the nuclear reactor can be speedily carried from the nuclear reactor building with reduced exposure of operators to radioactivity from the radioactive internal structure.

Method of handling a nuclear reactor and an apparatus used in the handling method

A method of handling an internal structure of a nuclear reactor utilizing a receptacle such as a container or a cask. A cask, for example, is lifted from outside of a nuclear reactor building through an opening which is opened at a portion of the nuclear reactor positioned just above a nuclear reactor pressure vessel. While maintaining the cask under a lifted condition, a shroud, which is an internal structure of the nuclear reactor, is transferred and inserted to the cask from the nuclear reactor vessel. Thereafter, an inlet port of the cask is closed so that the cask substantially surrounds the shroud and substantially prevents radiation from the shroud passing therethrough. The cask together with the shroud is lifted outside of the nuclear reactor building through the opening. The internal structure of the nuclear reactor can be speedily carried from the nuclear reactor building with reduced exposure of operators to radioactivity from the radioactive internal structure.

A pressure vessel of a nuclear reactor is bodily enclosed by an inner layer made of a heat insulating material and an outer layer made of a radiation shielding material, and a nozzle joined by welding to the pressure vessel and a pipe joined by welding to the nozzle projected outwardly from the pressure vessel to extend through openings formed in the two layers. A removable heat insulator detachably attached to an edge of the inner layer defining the opening is disposed in a manner to surround the nozzle. A shielding frame is secured to walls defining the opening in the outer layer, to provide a manhole through which the nozzle and the pipe extend. A plurality of radiation shielding blocks are hingedly supported by an outer end of the shielding frame which is remote from the pressure vessel, while a plurality of radiation shielding plates are hingedly supported by an inner end of the shielding frame which is near to the pressure vessel. When the nuclear reactor is in operation, the radiation shielding blocks are kept in a closed position to plug the manhole, while the radiation shielding plates are kept in an open position. If the nuclear reactor is shut down and inspection of the welds is performed, the radiation shielding blocks are opened, the heat insulator is temporarily removed from its position and some of the radiation shielding plates are closed whereby an open space between the nozzle and pipe and the shielding frame can be closed to avoid exposure of the whole-body of the inspector to radiation.

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Hitachi, Japan

Masataka Aoki