JP3101095B2 - Decommissioning method and system for reactor pressure vessel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear power plant, and more particularly, to the construction of an underground containment building on a site of a power plant, a storage of a used reactor pressure vessel inside the containment building, and a further improvement of the pressure vessel. A method and apparatus suitable for effectively utilizing the site of a nuclear power plant and securing a radioactive waste storage facility by storing a reactor internal structure therein and using it as a storage container for radioactive waste. About.

[0002]

2. Description of the Related Art Conventionally, radioactive waste in a nuclear power plant is reduced in volume according to its radioactivity level and form, then vitrified, or stored in a cask as it is. Nuclear power plants are designed with a lifetime of 30 or 40 years. 10 with long life technology
Even if the service life is extended, they must eventually be disposed of. However, the disposal method has not been established yet.

[0003]

The above-mentioned prior art deals with radioactive waste having a relatively small capacity, and cannot deal with the disposal of large structures such as reactor pressure vessels and pipes. For disposal of large structures, it is necessary to devise a new concept of disposal or storage. On the other hand, nuclear power plants are difficult to locate in response to the constantly increasing trend of power demand in recent years. If a new location is difficult, it is a challenge to effectively use the site of the power plant that has been located in the past. It is believed that methods that can be used will solve the above problems.

The disposal of large radioactive structures in a nuclear power plant requires a very large radioactive waste storage facility using conventional techniques. In the situation where the final disposal method of radioactive waste has not been established yet, it is necessary to store it safely for a long time. Therefore, using the reactor pressure vessel itself containing the most highly radioactive internal structures as a containment vessel, constructing a concrete storage building underground in the premises of the power plant and storing it inside it The above object can be achieved by adopting a method of reducing the volume of a furnace internal structure or other radioactive waste and storing it in a pressure vessel.

[0005]

In order to achieve the above object, a method for decommissioning a reactor pressure vessel according to the present invention comprises installing a concrete containment building underground in the premises of a nuclear power plant, Store the used pressure vessel in
Further, the reactor internal structure is stored in the used pressure vessel, and the decommissioning system of the nuclear pressure vessel according to the present invention is configured to blow and compress the reactor equipment temporary storage pool of the reactor building. An overhead traveling crane is installed on the rooftop and outside of the reactor building to install a plasma fusing machine and a press to reduce the volume of the reactor internals and to transfer the pressure vessel from the reactor building to the containment building. Rails and overhead traveling cranes, and rails for overhead traveling cranes and overhead traveling cranes are installed outside the reactor building and between the pressure vessel containment building.

[0006]

[Function] By storing a used reactor pressure vessel containing radioactive waste such as reactor internals in an existing nuclear power plant in an underground storage facility, the nuclear power plant can be installed without a new location. It can be installed and there is no need to newly install a radioactive waste storage facility.

[0007]

FIG. 1 shows an embodiment of the present invention. In a nuclear power plant, a containment vessel 2 made of steel is provided inside a reactor building 1, and a reactor pressure vessel 3 is installed inside the containment vessel 2. Such reactors are designed with a life of 30 or 40 years. However, since the actual life of a nuclear power plant has much more margin than the design life, a technology for performing a deterioration diagnosis of materials and using a reactor beyond the design life has been developed. Even then, the reactor must eventually be scrapped.

By the way, radioactive waste discharged from a nuclear power plant is reduced in volume according to the radioactivity level and form and then vitrified or stored in a cask as it is and stored in a radioactive waste storage building. I have. However, disposal of large structures with radioactivity requires an extremely large-scale radioactive waste storage facility using conventional techniques. In addition, at present, the final disposal method of radioactive waste has not yet been established, and it is necessary to store structures with high radioactivity safely for a long period of time.

[0009] On the other hand, nuclear power plants are difficult to locate in response to the constantly increasing tendency of power demand in recent years. If a new location is difficult, it is a challenge to effectively use the site of the power plant that has been located in the past. The advantage of using is that it is possible to install a nuclear power plant without having to set up a new location, and it is not necessary to newly install a radioactive waste storage facility.

Therefore, as shown in FIG. 1, a concrete storage building 7 is constructed underground at a location close to the reactor building 1 in the premises of the nuclear power plant. The inner surface may be lined with steel. The support frame 6 is provided at the bottom of the containment building 7, and the reactor pressure vessel 3 containing the most highly radioactive internal structure is fixed thereon via the support skirt 4. In addition, a support 5 is installed between the housing 7 and the stowage building 7 by using stud bolts of the flange portion to prevent earthquake. The upper part of the storage building 7 is covered with a lid 8 made of concrete or steel. At this time, the used pressure vessel itself is used as a storage container for radioactive waste, and the furnace internal structure and other radioactive waste are reduced in volume and stored in the pressure vessel.

FIG. 2 shows a flowchart of the procedure for disposing of the pressure vessel. First, in step (1), a hole is dug in a place near the reactor building 1 in the premises of the nuclear power plant, and in step (2), a concrete storage building 7 is constructed underground. Next, in step (3), the pipes attached around the pressure vessel 3 to be discarded are cut so that the pressure vessel 3 can be taken out. In step (4), since the inside of the pressure vessel 3 has high radioactivity, an end cap is attached to a nozzle or the like to which the pipes have been attached by welding or the like so as to suppress radiation leakage.

In step (5), the stud bolt of the pressure vessel is loosened, the upper mirror is removed, and the furnace internal structure is removed. At this time, the reactor internals are temporarily stored in the reactor equipment temporary storage pool 10 in order to perform various processes. In step (6), in the reactor equipment temporary storage pool 10, the reactor internal structure is cut using a plasma welding machine or the like, and volume reduction processing for reducing the volume is performed. In step (7), the pressure vessel 3 is transferred to the storage building 7 using a crane or the like. In step (8), the pressure vessel 3 is fixed to the support base 6 via the support skirt 4 and the support 5. In step (9), the upper mirror of the pressure vessel 3 is opened, and the furnace internals subjected to the volume reduction processing are carried in. In step (10), the upper lid of the storage building 7 is attached, and the disposal of the used pressure vessel 3 is completed.

The details of each step will be described below. First, in step (1), a hole deep enough in comparison with the height of the pressure vessel 3 is dug in a place near the reactor building 1 in the premises of the nuclear power plant. In step (2), as shown in FIG. 1, a concrete storage building 7 is constructed underground. The thickness of the containment building 7 should be sufficient to shield radioactivity, and in some cases steel lining the inside. A support base 6 is provided at the bottom of the storage building 7. Also,
A support plate for mounting the support 5 is provided on the side wall of the storage building 7 in order to install the support 5 between the storage building 7 and the storage building 7 using stud bolts of the flange portion to prevent earthquakes.

In step (3), the pressure vessel 3 to be discarded
In step (4), since the inside of the pressure vessel 3 has high radioactivity, the pipes attached to the nozzles or the like to which the pipes were mounted are cut so as to suppress radioactive leakage. Attach the cap by welding or the like. That is, as shown in FIG. 3, a large number of furnace internal structures are installed inside the pressure vessel 3, a large number of nozzles are provided on the outer peripheral portion for connection with piping, and the lower mirror portion is controlled. Holes such as a rod drive housing and a neutron flux monitor housing are provided. These are cut at the connection with the pressure vessel, and an end cap 50 is provided for suppressing radioactivity as shown in FIGS. In that case, as shown in FIG. 5, a can-shaped end cap having one opened is prepared, and the end is welded, for example, to N
Attached to the two nozzles 43.

In step (5), the stud bolt 48 of the pressure vessel 3 is loosened, the upper mirror 49 is removed, and the furnace internal structure is removed. At this time, the reactor internals are temporarily stored in the reactor equipment temporary storage pool 10 in order to perform various processes.

In step (6), in the reactor equipment temporary storage pool 10, the reactor internal structure is cut using a plasma welding machine or the like, and volume reduction processing for reducing the volume is performed. This processing method will be described later in detail.

In step (7), the pressure vessel 3 is transferred to the storage building 7 using a crane or the like. FIG. 6 shows a method of transferring the used pressure vessel 3. If an overhead traveling crane used during construction remains above the reactor building 1, it is used. If not, the rails 11 for the overhead traveling crane are installed outside the reactor building 1 with a sufficient space for the pressure vessel 3 to be lowered.
Similarly, a rail 13 for an overhead traveling crane is installed outside the reactor building 1 while securing a sufficient space for lowering the pressure vessel 3 in the direction of the containment vessel 7. Large cranes 12 and 14 are installed on the rails 11 and 13 for the overhead traveling crane.

When disposing of the pressure vessel, first, the lid of the reactor containment vessel 2 is opened, the surrounding piping and the internal structure of the reactor are removed, and the pressure vessel having an end cap 50 attached to the nozzle portion. 3 is hoisted by a large crane 12 using a wire rope. Next, it moves in the horizontal direction and is transported to the outside of the reactor building 1. Then, it is suspended and lowered until the support skirt 4 contacts the ground. At this time, the pressure vessel 3 may be supported only by the support skirt 4. However, for safety, a pressure vessel support structure 15 as shown in FIG. A support 16 is installed between the container support structure 15 and fixed. Next, when preparation for lifting by the large crane 14 is completed, the support skirt 4 and the support 16
Loosen the fixing bolt. Then, the container is lifted by the large crane 14, moved to the upper center of the storage building 7, and the pressure vessel 3 is hung.

In this case, the rails 11 and 13 and the large cranes 12 and 14 for the overhead traveling crane may be prepared respectively, but in consideration of the equipment cost, the rails 11 and 13 are basically commonly used. The position of the storage building 7 is determined so that it can be used. Similarly, only one large crane 12, 14 is prepared and commonly used. Alternatively, rail 11
And the rail 13 can be connected to each other.
18 are prepared in large numbers according to the number of rail digits to be connected, so that they can be commonly used. In this case, the equipment cost can be reduced, but the days for disassembling and assembling the rails 11 and 13 and the cranes 12 and 14 require a long period of time.

In the step (8), the pressure vessel 3 is fixed to the support base 6 by bolts via the support skirt 4.
This fixing method is performed by the same method as the method in which the pressure vessel 3 is fixed in the storage container 2. Further, the support 5 is used to fix the space between the support plate provided in the storage building 7 and the stud bolt 48 of the flange portion.

In step (9), the upper mirror 4 of the pressure vessel 3
Open 9 to carry in the furnace structure and other waste that have been subjected to volume reduction processing. The details will be described later.

In step (10), the upper lid of the storage building 7 is attached, and the disposal of the used pressure vessel 3 is completed.

Next, a method of treating the furnace internals will be described. In step (5), the furnace internal structure is removed from the pressure vessel 3, and the furnace internal structure is temporarily stored in the reactor equipment temporary storage pool 10 for performing various processes. In step (6), in the reactor equipment temporary storage pool 10, the reactor internal structure is finely cut using a plasma welding machine or the like to perform volume reduction processing to reduce the volume, or to remove only a part thereof. Is performed. As the processing method, there is the following method.

(1) All welding cutting and volume reduction processing (2) Partial welding cutting and volume reduction processing (shroud 42
(3) Partial welding cutting and volume reduction processing (shroud 42)
And its outside, a core support plate 41, a shroud head 22,
(Excluding upper grid plate 38 and steam separator 35) (4) Classify and process as follows Left: Shroud 42 Jet pump 27 Core support plate 41 Upper grid plate 38 Shroud head 22
Separator 35 Partially disassembled: Stand pipe 36 Volume reduction processing: Dryer 33 Removed: Control rod drive mechanism housing 31 Neutron bundle monitor housing 46 Neutron bundle monitor housing stabilizer 44 (5) Shroud head 22, Stand pipe 36,
The separator 35 is turned upside down and stored in the shroud 42 or the shroud support 45. (6) All furnace internal structures are left. (1) All welding cutting and volume reduction processing is shown in FIG. 4, for example. As described above, all the reactor internals are removed from the interior of the pressure vessel 3 to the reactor equipment temporary storage pool 10, and are cut finely using a plasma welding machine or the like, and subjected to a volume reduction process to reduce the volume. .

As shown in FIG. 8, the partial welding cutting and volume reduction processing (excluding the shroud and its outside) of (2)
Water supply sparger 21, core sparger 23, shroud 42, shroud support 45 at the outer periphery of the furnace
All other structures of the steam dryer 33, the steam separator 35, the stand pipe 36, the shroud head 22, the upper lattice plate 38, the core support plate 41, and the lower plenum, for example, the control rod guide The volume is reduced by fusing the tube 28 and the like.

(3) Partial welding cutting and volume reduction processing (shroud and its outside, core support plate, shroud head,
As shown in FIG. 9, the upper grid plate and the steam-water separator are left as they are, with the water supply sparger 21, the core sparger 23, the shroud 42, the shroud support 45 and the like at the outer periphery of the furnace being left as they are, and steam drying Vessel 33, steam separator 35, stand pipe 36, shroud head 22,
Among the large internal structures such as the upper lattice plate 38 and the core support plate 41, the outer periphery of the core support plate 41, the upper lattice plate 38, the shroud head 22, the steam separator 35, and the steam dryer 33 are shroud or shroud support. And is concentrically blown so that it fits within the shroud or shroud support. All the structures in the lower plenum are subjected to volume reduction by fusing.

The items to be classified and processed in (4) are, as to be left, structures outside the shroud such as the shroud 42, the shroud support 45, and the jet pump 27, and the core support plate 41, the upper grid plate 38, the shroud. A stand pipe 36 is used for partial decomposition, such as the head 22 and the steam separator 35, a steam dryer 33 is used for volume reduction processing, and a control rod drive mechanism housing 31 is used for removing and finely cutting, a neutron flux monitor. There are a housing 46, a neutron flux monitor guide tube stabilizer 44, and the like. FIG. 10 shows a core support plate 41, an upper lattice plate 38,
The outer peripheries of the shroud head 22 and the steam separator 35 are concentrically blown so as to be accommodated in the shroud or the shroud support, and housed in the shroud or the shroud support. Although not shown in FIG. 10, the steam dryer 3
3 is melted, and the volume is further reduced by a compression process using a press machine.

(5) As shown in FIG. 11, the outer periphery of the core support plate 41, the upper grid plate 38, the shroud head 22, the stand pipe 36, and the steam separator 35 are accommodated in the shroud or the shroud support. So, after fusing concentrically, shroud head, stand pipe,
The steam separator is turned upside down and housed in a shroud or shroud support.

The method of leaving all the furnace internals of (6) is as follows.
Inside the furnace structure, steam dryer 33, shroud head 2
2. The detachable parts such as the stand pipe 36, the steam separator 35, the fuel assembly 26, etc. are removed to the reactor equipment temporary storage pool 10 outside the reactor. It is transported to the storage building 7 while remaining inside, and thereafter all the furnace internal structures are carried in. Therefore, in this case, as shown in FIG. 12, the condition inside the furnace is that there is no fuel assembly and the control rod drive mechanism housing 3 attached to the lower part of the lower mirror of the pressure vessel 3.
1. Since there is no neutron flux monitor housing 46, the neutron flux monitor housing 46 is stored in the storage building 7 and discarded in the same state as in use.

In the above embodiment, for example, as in step (9), the pressure vessel is housed in the containment building, and then the melted or reduced furnace internal structure is housed in the vessel. Alternatively, the pressure vessel may be housed in a pressure vessel outside the containment building, and then the pressure vessel may be housed in the containment building. In addition, volume reduction processing is cutting, fusing,
It can be carried out by an appropriate combination such as pressing, and the dryer can be easily processed by pressing.

[0031]

As described above, according to the present invention,
On the premises of the nuclear power plant, a concrete containment building will be constructed underground, used pressure vessels will be housed inside, and the furnace internal structure will be housed inside the used pressure vessels. This eliminates the need to install a nuclear power plant using a newly manufactured nuclear reactor, and eliminates the need to install a radioactive waste storage facility.

[Brief description of the drawings]

FIG. 1 is a diagram showing a method of disposing of a used reactor pressure vessel in a nuclear power plant premises.

FIG. 2 is a flowchart showing a method of disposing of a used reactor pressure vessel.

FIG. 3 is a diagram showing a reactor pressure vessel and reactor internals.

FIG. 4 is a view showing a method of applying an end cap to a nozzle of a reactor pressure vessel.

FIG. 5 is a view showing a shape of an end cap to a nozzle or the like and a method of attaching the same by welding.

FIG. 6 is a diagram showing a method of transferring a used reactor pressure vessel in a premises of a nuclear power plant.

FIG. 7 is a diagram showing a method of transferring a used reactor pressure vessel in a nuclear power plant premises.

FIG. 8 is a diagram showing a method for removing a reactor internal structure of a used reactor pressure vessel.

FIG. 9 is a diagram showing a method for removing a reactor internal structure of a used reactor pressure vessel.

FIG. 10 is a diagram showing a method for removing a reactor internal structure of a used reactor pressure vessel.

FIG. 11 is a diagram showing a method for removing a reactor internal structure of a used reactor pressure vessel.

FIG. 12 is a diagram showing a method for removing a reactor internal structure of a used reactor pressure vessel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor building 2 ... Containment vessel 3 ... Pressure vessel 4 ... Support skirt 5 ... Support 6 ... Support stand 7 ... Containment building 8 ... Top lid 10 ... Reactor equipment temporary storage pool 11 ... Rail for overhead traveling crane 12 ... Ceiling Traveling crane 13 ... Rail for overhead traveling crane 14 ... Overhead traveling crane 15 ... Support 16 ... Support 17, 18 ... Prop 21 ... Water supply sparger 22 ... Shroud head 23 ... Core place sparger 24 ... Low pressure water injection coupling 25 ... Control rod 26 ... Fuel assembly 27 ... Jed pump 28 ... Control rod guide tube 29 ... Jet pump adapter 30 ... Differential pressure detection boric acid water injection system piping 31 ... Control rod drive mechanism housing 32 ... Dryer hold down bracket 33 ... Steam dryer 34 ... shroud head bolt 35 ... steam separator 36 ... stand Pipe 37: Core spray system piping 38 ... Upper lattice plate 39 ... Jet pump riser brace 40 ... Fuel support bracket 41 ... Core support plate 42 ... Shroud 43 ... N2 nozzle 44 ... Neutron flux monitor guide tube stabilizer 45 ... Shroud support 46 ... Neutron Bundle monitor guide tube housing 47 Access hole cover 48 Stud bolt 49 Upper mirror 50 End cap 51 Lower mirror

Continuation of front page (72) Inventor Hideyo Saito 3-1-1 Sachimachi, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (56) References JP-A-53-71799 (JP, A) JP-A-60 -24498 (JP, A) JP-A-64-66372 (JP, A) JP-A-4-174399 (JP, A) JP-A-3-18797 (JP, A) (58) Fields investigated (Int. . ^7, DB name) G21F 9/30

Claims (10)

(57) [Claims] Claims: 1. In a premises of a nuclear power plant, concrete
A metal-made containment building is installed underground and used inside.
Of the pressure vessel, or in the containment building
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used nuclear reactor pressure vessel described above, the internal structure of the reactor is finely cut using a plasma welding machine or the like.
And then perform a volume reduction process to reduce the volume, and then
A method for decommissioning a used reactor pressure vessel , comprising storing the used pressure vessel in a house. 2. A concrete facility in a nuclear power plant premises.
A metal-made containment building is installed underground and used inside.
Of the pressure vessel, or in the containment building
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used nuclear reactor pressure vessel described above, after all of the reactor internal structures are subjected to fusing and volume reduction processing,
A method for decommissioning a used reactor pressure vessel, wherein the used pressure vessel is stored in a used pressure vessel stored in the storage building . 3. A concrete facility in a nuclear power plant premises.
A storage building made of metal is installed in the basement, and the used pressure vessel is stored in the basement.
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used reactor pressure vessel described above, all of the reactor internals except for the shroud and the outside are melted.
A method for decommissioning a used nuclear reactor pressure vessel , comprising subjecting the used pressure vessel to storage in the storage building after disconnection and volume reduction processing . 4. A concrete facility in a premises of a nuclear power plant.
A metal-made containment building is installed underground and used inside.
Of the pressure vessel, or in the containment building
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used reactor pressure vessel described above, the shroud and its exterior, the core support plate, and the shroud
The furnace structure excluding the head, upper lattice plate, and steam separator
A method for decommissioning a used nuclear reactor pressure vessel , comprising subjecting the used pressure vessel to fusing and volume reduction processing, and then storing it in a used pressure vessel stored in the storage building. 5. A concrete facility in a premises of a nuclear power plant.
A metal-made containment building is installed underground and used inside.
Of the pressure vessel, or in the containment building
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used nuclear reactor pressure vessel, the internal structure of the reactor is left as it is, partially disassembled,
Reduce volume by fusing, do not reduce volume with a press.
A method for decommissioning a used nuclear reactor pressure vessel, wherein the method includes a step of treating the structure in accordance with the structure and then storing the treated pressure vessel in a used pressure vessel stored in the storage building. 6. A concrete facility in a premises of a nuclear power plant.
A metal-made containment building is installed underground and used inside.
Of the pressure vessel, or in the containment building
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used nuclear reactor pressure vessel, a core support plate, an upper lattice plate, a shroud head, a stand
Pipe or steam / water separator with shroud or shroud
Fused concentrically so that it fits inside the udo support
Later, housed in shroud or shroud support
A method for decommissioning a used nuclear reactor pressure vessel, characterized in that: 7. A concrete facility in a premises of a nuclear power plant.
A metal-made containment building is installed underground and used inside.
Of the pressure vessel, or in the containment building
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used reactor pressure vessel described above, the outer circumference of the stand pipe and the steam separator is shroud or
Is concentric so that it fits inside the shroud support
After fusing, shroud bed, stand pipe, steam
Turn the separator upside down and shroud or shroud support
A method for decommissioning a used reactor pressure vessel, wherein the method is carried out in a reactor. 8. A concrete facility in a premises of a nuclear power plant.
A metal-made containment building is installed underground and used inside.
Of the pressure vessel, or in the containment building
Store the furnace internals in the used pressure vessel.
In the method for decommissioning a used nuclear reactor pressure vessel described above, all reactor internal structures except the structure under the fuel assembly and the lower mirror are used.
Stored in a storage building in the same state as used
A method for decommissioning a used reactor pressure vessel, wherein the internal structure of the reactor is stored in the pressure vessel. 9. A concrete facility in a premises of a nuclear power plant.
A metal-made containment building is installed underground and used inside.
Used reactor pressure vessel to house the pressure vessel
In the decommissioning method of the vessel, cutting the piping provided around the pressure vessel,
End-cap the nozzle, etc., to which the piping was attached.
The pressure vessel is attached to the containment building by welding
A method for decommissioning a used nuclear reactor pressure vessel, comprising: 10. A temporary pool for reactor equipment in a reactor building.
In order to reduce the volume of the furnace internals by fusing and compression
A plasma fusing machine and a press machine are installed, and the pressure vessel is atomized.
To transfer from the reactor building to the containment building,
Rails and overhead running for overhead traveling cranes on the roof and outside
A row type crane is placed outside the reactor building,
Rail and overhead traveling type for overhead traveling crane between the shop
A decommissioning system for a used reactor pressure vessel, which is equipped with a crane .