JP2004093143A - Nuclear steam supply cassette and method for handling it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nuclear steam supply cassette which is utilized as a non-network power source unconnected with an electric power system network, is used for a lower-output nuclear reactor of a package type and can be safely carried, and a method for handling the cassette. <P>SOLUTION: A reflector 5 is placed radially outside an in-cassette core 4 so that the reflector 5 can surround the in-cassette core 4, and a shield 6 is placed outside the reflector 5. The in-cassette core 4 is cylindrical, and a cylindrical inner wall face 13 is formed inside it. A pressure tube 2 is equipped with a bulkhead part 12 so that it can face the inner wall face 13, and a concave part 14 which opens on the side of a bottom face 2c and is recessed is formed. The nuclear steam supply cassette 1 is carried to a site where a reactor is installed in a dry condition where a control rod 32 or a moderator rod is inserted into the concave part 14 and a primary coolant 8 is not filled inside it. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a nuclear-powered steam supply cassette used in a packaged nuclear reactor that constitutes a reactor having a desired output by combining a nuclear-powered steam supply cassette and a method of handling the same.
[0002]
[Prior art]
Due to geographical circumstances, it is not possible to connect to a power grid with another power supply, and in areas such as remote islands and outbacks where an independent power supply is required, There is a demand for a power supply system that supplies power using compact equipment.
Conventionally, diesel power generation, gas turbine power generation, and the like have been used in such an area, but attention has been focused on nuclear power generation that uses nuclear fuel that can easily transport fuel required for power generation and that does not cost much.
[0003]
[Problems to be solved by the invention]
However, conventional nuclear power plants generally perform high-output power generation efficiently using large-scale facilities. For example, a reactor vessel used in a conventional nuclear power plant generally has a diameter of about 4 m and a height of more than 10 m. Also, the output of nuclear power generation is often huge, and even a small reactor has a power of 300 MWt or more (electrical output of about 100 MWe) or more. Would.
In such a large-scale reactor, the amount of installation work on the site where the reactor is to be installed increases, and in areas such as remote islands and outlying areas, there are many difficult operations under severe weather conditions. It is a factor that hinders development.
In designing a reactor, first, the target power of the reactor is set, the number of fuel bodies to be loaded in the core is set according to the target power, the core configuration is determined, and the reactor pressure in which it is built is determined. Determine the dimensions of the container and the furnace internals. As described above, there is a face that it is difficult to standardize if various devices are individually designed according to the furnace power.
Since nuclear fuel has a remarkably small weight per unit heat energy, as described above, transport is easy, but careful attention must be paid to safe transport.
[0004]
The present invention has been made in order to solve such problems, and is used as a non-network power supply not connected to a power system network, is used in a relatively low-power reactor, and can be safely transported. The purpose is to provide a handling method.
[0005]
[Means for Solving the Problems]
A nuclear-vapor-steam supply cassette according to the present invention is a nuclear-vapor-steam supply cassette including a pressure tube, a core made of a fuel assembly, and a steam generator inside the pressure tube, wherein the core is on the bottom side of the pressure tube. The pressure tube is opposed to the inner wall surface of the core, and has a partition wall opening to the bottom surface side of the pressure tube to form a concave recess. The control rod or the speed reduction rod can be inserted into the recess from outside the pressure tube so as to face the inner wall surface of the pressure pipe.
Further, a reflector may be provided around the core, and a shield may be provided.
It is preferable that the nuclear steam supply cassette is transported in a state where the control rod is inserted into the concave portion and the inside of the pressure tube is dry.
A plurality of the nuclear steam supply cassettes are arranged in the nuclear reactor, and the power fluctuation of the nuclear reactor can be adjusted by changing the replacement time of each nuclear steam supply cassette.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are sectional views of a nuclear steam supply cassette according to an embodiment of the present invention. 3 and 4 are cross-sectional views of a packaged nuclear reactor using the nuclear steam supply cassette.
The nuclear-powered steam supply cassette 1 includes a pressure tube 2, a steam generator 3 circumferentially arranged from the center of the inner wall to an upper part, a cassette core 4 as a fuel assembly provided below the steam generator 3, A reflector 5, a shield 6, and a shroud 7 are provided.
[0007]
The pressure pipe 2 is an elongated cylindrical pipe having a diameter of about 1.5 m and a length of several meters and having a closed upper and lower end. The pressure pipe liner 2a is made of a metal material such as stainless steel. And a reinforcing fiber layer 2b reinforced with strength. Between the pressure pipe 2 and the core 4 in the cassette, a downcomer section 9 in which the primary coolant 8 sealed in the pressure pipe 2 flows downward is formed. Above the core 4 in the cassette, a shroud 7 defining a flow path of the primary coolant 8 is provided. Further, a riser 10 is formed above the shroud 7 in which the primary coolant 8 heated by the core 4 in the cassette rises, so that the primary coolant 8 circulates in the pressure pipe 2 in the direction of a white arrow. It is configured.
[0008]
A reflector 5 is provided radially outside the core 4 in the cassette so as to surround the core 4 in the cassette. The reflector 5 reflects neutrons leaking from the core 4 in the cassette and returns the neutrons to the core 4 in the cassette to maintain the operation of the reactor with less fuel.
Further outside the reflector 5, a shield 6 for shielding neutrons and gamma rays emitted from the cores 4 in each cassette from the outside is provided.
[0009]
On the other hand, as shown in FIGS. 1 and 2, the cassette core 4 has a cylindrical shape, and has a cylindrical inner wall surface 13 penetrating vertically.
The pressure tube 2 has a partition wall portion 12 so as to face the inner wall surface 13. The partition 12 extends from the bottom surface 2 c in an elongated cylindrical shape to form a concave recess 14. The control rod 32 is configured to be inserted into the concave portion 14, and the control rod 32 and the inner wall surface 13 of the cassette core 4 are arranged so as to face each other with the partition wall 12 of the pressure tube 2 interposed therebetween.
The in-cassette core 4 has a core configuration in which the control rod 32 is inserted to maintain subcriticality.
[0010]
Next, FIGS. 3 and 4 show a structure of a packaged nuclear reactor 30 configured by combining a plurality of the nuclear steam supply cassettes 1 configured as described above.
As shown in FIG. 3, a plurality of nuclear steam supply cassettes 1 are arranged in the tank 31. A control rod 32 is inserted into the concave portion 14 of the nuclear-vapor-steam supply cassette 1. The control rod 32 extends downward, penetrates the bottom surface 31a of the tank 31, and is connected to the control rod driving device 33.
The control rod driving device 33 controls the output of the reactor by moving the control rod 32 up and down. A secondary coolant pipe provided with an on-off valve 37 on the way is disposed above the nuclear steam supply cassette 1 and is connected to a turbine and a pump (not shown). The secondary coolant pipe forms a water supply line 34 and a steam line 35 as a supply / discharge path of the secondary coolant 33 of the steam generator 3.
[0011]
Next, a method of transporting the nuclear steam supply cassette 1 until the cassette 1 is mounted on the packaged nuclear reactor 30 will be described.
The nuclear steam supply cassette 1 is transported to a site where a nuclear reactor is installed in a dry state in which the control rod 32 is inserted into the concave portion 14 and the primary coolant 8 is not sealed inside. Since the inside is maintained in a dry state during transportation, the nuclear steam supply cassette 1 can be securely maintained in a subcritical state and can be transported safely. Further, since the control rod 32 is inserted into the core 4 in the cassette, the reaction of the nuclear steam supply cassette 1 is suppressed by the control rod 32, the subcritical state can be ensured, and the nuclear steam supply cassette 1 can be transported safely. That is, a double treatment for maintaining the subcritical state of the nuclear steam supply cassette 1 is performed by keeping the inside dry and inserting the control rod 32.
After that, the nuclear steam supply cassette 1 is installed in a nuclear reactor on site, and then the primary coolant 8 is injected, and the control rod 32 is pulled out.
[0012]
Next, the operation of the packaged nuclear reactor using the nuclear steam supply cassette 1 according to the embodiment of the present invention will be described with reference to FIG.
The primary coolant 8 in each nuclear steam supply cassette 1 of the packaged nuclear reactor 30 is heated by the reaction heat of the core 4 in the cassette, rises the shroud 7 and the riser 10 and performs secondary cooling in the steam generator 3. Heat exchange is performed with the material 33. The cooled primary coolant 8 descends the downcomer section 9 and is heated again in the core 4 in the cassette.
In the steam generator 3, the secondary coolant 33, which has taken heat from the primary coolant 8 and has been heated to be steam, is led to the turbine via a steam line 35, and is then steamed from a water supply line 34 via a pump. Returned to generator 3.
The steam guided to the turbine rotates the turbine, and power is generated by a generator driven by the turbine.
[0013]
In this way, from each nuclear steam supply cassette 1, the secondary coolant 33 is supplied to the turbine as steam and supplied to the turbine for power generation, and a desired power generation amount can be obtained according to the number of the nuclear steam supply cassettes 1. it can.
Here, the number of the disposed nuclear steam supply cassettes 1 can be appropriately selected according to the required output of the nuclear reactor. Therefore, it is possible to configure the packaged nuclear reactor 30 having a desired output according to the number of the nuclear steam supply cassettes 1 accommodated in the nuclear reactor.
[0014]
When the packaged nuclear reactor 30 is operated for a long period of time, the combustion in each nuclear steam supply cassette 1 proceeds, the fuel in the core 4 in the cassette decreases, and the output of the nuclear reactor 30 gradually decreases. Instead of replacing the steam supply cassette 1 with a new one, it is possible to replace only the nuclear power supply cassette 1 whose output has decreased. Further, by staggering the replacement time of each nuclear steam supply cassette 1, it is possible to easily adjust the output fluctuation width of the entire reactor 30.
[0015]
Embodiment 2 FIG.
In the first embodiment, the control rod 32 is inserted into the recess 14 of the pressure pipe 2 of the nuclear steam supply cassette 1. However, a speed reduction rod may be inserted instead of the control rod 32. Good.
In this case, the fuel in the core 4 in the cassette is configured to maintain the subcritical state unless the moderator is inserted, and the nuclear steam supply cassette 1 has no moderator and the primary coolant 8 inside. It is transported to the site where the reactor is installed in a dry state without being enclosed.
After that, the nuclear steam supply cassette 1 is installed in the nuclear reactor at the site, and then a speed reduction rod is inserted to achieve the criticality only when the neutrons are decelerated.
Therefore, even with such a configuration of the nuclear steam supply cassette, the nuclear steam supply cassette can be safely transported to the site.
[0016]
Embodiment 3 FIG.
FIG. 5 shows a cross section of the core 41 in the cassette of the nuclear steam supply cassette according to Embodiment 2 of the present invention. The configuration of the nuclear steam supply cassette according to this embodiment is such that, in the cassette core 4 of the first embodiment shown in FIG. The control rod 42 is provided on the circumference so that the control rod 42 can be inserted into each recess 43. Each of the control rods 42 is joined to each other at one end by a control rod cluster 44, and is connected to the control rod driving device 33 through the control rod cluster 44 in the same manner as in FIG.
Note that, instead of each control rod 42, the reduction rod used in the second embodiment may be used.
[0017]
The present invention described above is not limited to the above, and can be implemented with appropriate modifications.
The partition 12 of the pressure tube 2 shown in FIG. 1 is not limited to the one integrally formed with the pressure tube 2, but is formed by forming a through hole in the bottom surface 2 c of the pressure tube 2, and opening and closing the upper end and the lower end. The lower end and the through-hole may be welded and formed separately from the pressure pipe 2.
The inner wall surface 13 of the core 4 in the cassette shown in FIG. 1 is not limited to a cylindrical surface penetrating to the upper part of the core 4 in the cassette, but may be open and concave on the bottom surface 2c side. That is, it is not necessary to open the upper part of the core 4 in the cassette.
Absent.
A steam separator may be provided above the shroud 7 of the nuclear steam supply cassette 1 shown in FIG. Thereby, the heat exchange efficiency of the primary coolant 8 in the steam generator 3 can be increased.
[0018]
【The invention's effect】
As described above, according to the present invention, there is provided a nuclear steam supply cassette including a pressure pipe, a core made of a fuel assembly, and a steam generator inside the pressure pipe. The pressure tube is provided with a concave inner wall surface opened to the bottom surface side, and the pressure tube is opposed to the inner wall surface of the reactor core, and is provided with a partition wall portion opened to the bottom surface side of the pressure tube to form a concave concave portion. The control rods and reduction rods can be inserted into the recesses from the outside of the pressure pipe so as to face the inner wall surface of the core. It is possible to provide a nuclear steam supply cassette which can be used in a nuclear reactor and can be safely transported.
Further, according to the present invention, since the control rod is inserted into the recess and the inside of the pressure tube is transported in a dry state, the nuclear steam supply cassette can be transported safely to the installation location of the nuclear reactor.
Further, according to the present invention, a plurality of nuclear steam supply cassettes are arranged in the reactor, and the power fluctuation of the reactor is adjusted by changing the replacement time of each nuclear steam supply cassette, so that the entire nuclear reactor is controlled. The output fluctuation width can be easily adjusted.
[Brief description of the drawings]
FIG. 1 is a vertical sectional view showing a structure of a nuclear steam supply cassette according to Embodiment 1 of the present invention.
FIG. 2 is a plan cross-sectional view around the core in the cassette of the nuclear steam supply cassette of FIG. 1;
FIG. 3 is an elevational sectional view showing the structure of a packaged nuclear reactor using the nuclear steam supply cassette according to the first embodiment.
FIG. 4 is a plan sectional view of the packaged nuclear reactor of FIG. 3;
FIG. 5 is a plan cross-sectional view around a core in a cassette used for a nuclear steam supply cassette according to Embodiment 3 of the present invention. It is an elevation sectional view showing a structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Nuclear steam supply cassette, 2 ... Pressure tube, 3 ... Steam generator, 4, 41 ... Cassette core, 5 ... Reflector, 6 ... Shield, 12 ... Partition part, 13 ... Inner wall part, 14, 43 ... Recesses, 30: packaged reactor, 32, 42: control rods.

Claims (5)

A pressure tube,
A nuclear steam supply cassette including a core and a steam generator made of a fuel assembly inside the pressure tube,
The core includes an inner wall surface that is open and concave on the bottom side of the pressure tube,
The pressure tube includes a partition wall portion facing the inner wall surface of the core and forming a concave portion that is open to the bottom surface side of the pressure tube,
A nuclear power steam supply cassette, wherein a control rod or a reduction rod can be inserted into the recess from outside the pressure tube so as to face the inner wall surface of the core with the partition wall interposed therebetween. The nuclear steam supply cassette according to claim 1, wherein a reflector is provided around the core. The nuclear steam supply cassette according to claim 1, wherein a shield is provided around the core. The method for handling a nuclear steam supply cassette according to any one of claims 1 to 3, wherein the control rod is inserted into the recess and the inside of the pressure tube is transported in a dry state. A nuclear power supply cassette according to any one of claims 1 to 3, wherein a plurality of the nuclear power supply cassettes are arranged in a nuclear reactor, and a power fluctuation of the nuclear reactor is adjusted by changing a replacement time of each nuclear power supply cassette. How to handle the steam supply cassette.

Images