Induced nuclear reactions: processes – systems – and elements – Handling of fission reactor component structure within...
Reexamination Certificate
2000-09-06
2001-06-26
Jordan, Charles T. (Department: 3641)
Induced nuclear reactions: processes, systems, and elements
Handling of fission reactor component structure within...
C376S268000, C376S272000
Reexamination Certificate
active
06252922
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of handling a nuclear reactor and an apparatus used in the handling method and in particular to a handling technique of an internal structure of a nuclear reactor with which a taking-out working of the internal structure of the nuclear reactor to outside of a nuclear reactor building or containment is provided.
In the nuclear reactor building or containment of an atomic power plant station, a nuclear reactor pressure vessel is received and in this nuclear reactor pressure vessel a shroud for surrounding a reactor core of a nuclear reactor and an upper portion lattice plate and a reactor supporting plate etc. exist as an internal structure.
In the nuclear reactor internal structure of the atomic power plant station, a damage state of the nuclear reactor internal structure is carried out to inspect and mend during every regular inspection time, however from the aspects of a conservation performance, an economic performance and a prevention preservation in a midway of durable years the nuclear reactor internal structure is exchanged over and renewed with a new nuclear reactor internal structure.
In a renewal working or processing of the nuclear reactor internal structure according to the prior art, in a nuclear reactor well pool, an upper portion lattice plate, an upper portion shroud and a reactor core supporting plate etc. are cut roughly and taken out in advance. In a nuclear reactor building using a previous-established ceiling crane, the roughly cut-down upper portion lattice plate, the roughly cut-down upper portion shroud and the roughly cut-down reactor core supporting plate etc. are temporally placed in a dry separator (herein, it is called as “DS”).
Further, in DS pool, a decomposition taking-out working and a fine cutting working for the roughly cut-down upper portion lattice plate, the roughly cut-down upper portion shroud and the roughly cut-down reactor core supporting plate etc. are performed with a remote control in the water. Accordingly, the upper portion lattice plate, the upper portion shroud and the reactor core supporting plate etc. are converted to waste materials.
Accordingly, so as to isolate the nuclear reactor well pool a and DS pool, DS pool gate is newly established. Further, the fine cut waste materials (the small chips of the nuclear reactor internal structure) are received in plural receptacles such as casks and on occasion the fine cut waste materials are transferred and kept on the premises to a sight bunker or a solid waste material reservoir.
Accordingly, in accordance with the working for cutting roughly in the nuclear reactor well pool, the working for cutting finely in DS pool, the supplementary working for increasing the storage containers and the supplementary material amount increase, since the above stated workings extend over a long period, there is problems from the aspects of the cost and radiation exposure etc. Further, a long period for a plant stop period in a total becomes a big burden economically to an electric power company from a reduction in an operation of rate of an equipment.
On the other hand, when the nuclear reactor pressure vessel is exchanged over, as described in Japanese application patent laid-open publication No. Hei 8-285981 and Japanese application patent laid-open publication No. Hei 8-262190, a technique has known in which the nuclear reactor pressure vessel is drawn in in a transfer receptacle or container which has waited on a roof of a nuclear reactor building by a crane and the nuclear reactor pressure vessel with the transfer container is transferred to a desired point of the nuclear reactor building.
In the above stated prior art example, the nuclear reactor pressure vessel with the transfer container is moved at an upper portion to the roof by performing an uncover to the nuclear reactor pressure vessel and by lifting the nuclear reactor pressure vessel with the transfer container in the nuclear reactor building. Accordingly, an exposure reduction countermeasure against to working men in the nuclear reactor building who relates to radiation from the nuclear reactor pressure vessel is insufficient.
Taking into consideration about the exposure reduction countermeasure against to the working men in the nuclear reactor building, as disclosed in Japanese application patent laid-open publication No. Hei 9-145882, a techniques has known in which plural divided shield bodies are assembled so as to surround the nuclear reactor pressure vessel in the nuclear reactor building and the reduction of the radiation and the diffusion of the radioactivity are shielded by the shield bodies and as a result the nuclear reactor pressure vessel is taken out from the roof of the nuclear reactor building.
However, in the above stated prior art method, since the assembling working of the shield body in the nuclear reactor building equipment is accompanied with, such an assembling working requires the labor time and accordingly it takes the time for carrying out the shield bodies to an outside of the nuclear reactor building.
To avoid the labor time for requiring the assembly of the shield bodies in the nuclear reactor building containment, a technique described in Japanese application patent laid-open publication No. Sho 62-285100 has known. The contents described in this patent publication will be shown as follows.
Namely, a cask for storing the radioactive waste material is lifted by a crane which is provided at an outside of the nuclear reactor building and the cask is passed through a provisional opening which is provided with an opening and closing state on the roof of the nuclear reactor building and further the cask is lifted in the nuclear reactor building.
After that, the cask is separated once from the crane and the cask is placed on a floor of the nuclear reactor building and further the cask is moved in a horizontal direction at a position in which the radioactive waste material to be subjected to the carry-out exists.
Next, the radioactive waste material (in concretely, an upper portion cover of the nuclear reactor pressure vessel) is lifted in the cask using a lifting machine in the cask and after that a bottom portion of the cask is closed according to an opening and closing door.
After that, the cask is moved toward a horizontal direction at just an under portion of the provisional opening which has provided with the opening and closing state on the roof of the nuclear reactor building. The cask is connected together with the crane and this cask is lifted up by the crane and further the cask is passed through the provisional opening of the cask and is carried out to the outside of the nuclear reactor building.
In the prior art technique described in Japanese application patent laid-open publication No. Sho 62-285100, it takes no labor time for requiring the assembly of the shield bodies in the nuclear reactor building, however it is effective to the reduction of radiation exposure and the diffusion of the radioactivity. However, in this prior art technique, the cask is separated once on the floor of the nuclear reactor building from the crane and the cask is placed and after that the cask is moved toward the horizontal direction.
Accordingly, from the lift-in of the cask in the nuclear reactor building until the lift-out of the cask, however since the working of the horizontal movement of the cask and the working of the connection and the separation of the cask and the crane are accompanied with, it takes the labor time yet.
In a case of the requirement of the above stated labor time, since the exchange-over of the internal structure is delayed, and further since also a re-operation time period of the atomic power plant station after the exchange-over of the internal structure is delayed, an operation efficiency of the atomic power station becomes worse.
Further, in a case of the decomposition of the atomic power plant station, there is a problem about a long-pending of the decomposition working.
SUMMARY OF THE INVENTION
An object of the prese
Aoki Masataka
Hasegawa Hiroshi
Miura Jun
Miyahara Ryohei
Tajiri Akinori
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Jordan Charles T.
Mun Kyoytack K.
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