JPH09105798A - Housing basket for transport and storage vessel of spent nuclear fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly remove the decay heat of spent nuclear fuel assembly out of a basket, improve subcriticality, also improve the strength and heat conductivity, and reduce the manufacturing man-hour. SOLUTION: A plurality of cubic spent nuclear fuel assembly housing cells 2 arranged within a transport and storage vessel for a PWR spent nuclear fuel 1a (or BWR spent nuclear fuel 1b) are held with a fixed space by a structural strength member (support lattice plate 3 or 10), good heat conductive metal plates 4, 7 are set in the space between the housing cells 2 along the space, and the good heat conductive metal plates 4, 7 are arranged so as to be parallel in the horizontal direction and alternately orthogonal in the vertical direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage basket for a transportation / storage container for spent nuclear fuel.

[0002]

2. Description of the Related Art FIG. 4 (a) is a cross-sectional plan view showing an example of a storage basket of a conventional PWR spent nuclear fuel transportation / storage container, and FIG. 4 (b) is a perspective view showing a lattice plate of the storage basket. FIG. 5 is a cross-sectional plan view showing another example of a storage basket of a conventional PWR spent nuclear fuel transportation / storage container.
FIG. 6A is a cross-sectional plan view showing an example of a storage basket for a conventional BWR spent nuclear fuel transportation and storage container, FIG. 6B is a perspective view showing a lattice plate of the storage basket, and FIG. 7 is a conventional BWR use basket. It is a cross-sectional top view which shows the other example of the storage basket of the transportation and storage container of nuclear fuel.

First, an example of a storage basket for a conventional PWR spent nuclear fuel transportation / storage container will be described with reference to FIGS. 4 (a) and 4 (b). Reference numeral 11 denotes a grid-like body made of a good heat conductive metal plate (thin plate). The voids 12 are formed between the good heat transfer metal plates. Then, the PWR spent nuclear fuel assembly is housed in each rectangular parallelepiped space 13 in the same lattice-like body 11, and the void portion 1
2 secures a predetermined porosity between the PWR spent nuclear fuel assemblies, and the lattice-like body 11 secures the structural strength of the entire basket. Further, the heat transfer of the lattice-like body 11 ensures the PWR spent nuclear fuel. The decay heat of the aggregate is removed to the outside of the basket.

Next, another example of the storage basket of the conventional PWR spent nuclear fuel transportation / storage container will be described with reference to FIG. 5, in which 14 is a plurality of spent nuclear fuel assembly storage cells formed in a rectangular pipe shape. The spent nuclear fuel assembly storage cells (square pipes) 14 are arranged in the vertical and horizontal directions in an aligned state, and voids are formed between the spent nuclear fuel assembly storage cells 14.
The same voids are filled with the good heat-transfer metal 15, the spent nuclear fuel assembly storage cells 14 are integrally assembled, and the good heat-transfer metal 15 is provided with the void drilling holes 16.

Then, the spent nuclear fuel assemblies are stored in a rectangular parallelepiped space in each spent nuclear fuel assembly storage cell 14,
The good heat transfer metal 15 removes the decay heat of the PWR spent nuclear fuel assemblies to the outside of the basket, while the void drilling 16 ensures a predetermined porosity between the PWR spent nuclear fuel assemblies. I have to. Next, conventional B
An example of the storage basket for the transport / storage container of WR spent nuclear fuel will be described with reference to FIGS. 6A and 6B. The storage basket is the same as the storage basket for the transport / storage container of PWR spent nuclear fuel shown in FIG. In addition, the lattice-shaped body 18 is formed of a metal plate (thin plate) having good heat conductivity.

Then, the BWR spent nuclear fuel assembly is housed in each rectangular parallelepiped space 19 in the grid-like body 18, the grid-like body 18 secures the structural strength of the entire basket, and the heat of the grid-like body 18 is maintained. The heat of decay of the BWR spent nuclear fuel assembly is removed to the outside of the basket by transfer. Next, another example of a storage basket for a conventional BWR spent nuclear fuel transportation / storage container will be described with reference to FIG.
Reference numeral 0 is a plurality of spent nuclear fuel assembly storage cells formed in a square pipe shape, and the spent nuclear fuel assembly storage cells 20 are arranged in a dense state in the vertical and horizontal directions.

Then, the spent nuclear fuel assemblies are stored in the rectangular parallelepiped spaces in the spent nuclear fuel assembly storage cells 20,
The spent nuclear fuel assembly storage cells (square pipes) 20 remove the decay heat of the PWR spent nuclear fuel assemblies to the outside of the basket, while the spent nuclear fuel assembly storage cells (square pipes) 20 cover the entire basket. To ensure the structural strength of.

[0008]

The conventional storage baskets for the transportation and storage containers of spent nuclear fuel shown in FIGS. 4 to 7 have the following problems. The essential functions required for the storage basket of the spent nuclear fuel transportation and storage container are:
It is as follows. That is, (1) the PWR spent nuclear fuels should be kept at a constant interval between adjacent spent nuclear fuel assemblies in order to prevent the spent nuclear fuels from reaching criticality in any case. It is necessary to secure a predetermined porosity and satisfy subcriticality. (2) As a common requirement for PWR spent nuclear fuel and BWR spent nuclear fuel, the decay heat generated in the spent nuclear fuel is removed so that the temperature of the fuel cladding tube does not reach a temperature that impairs the integrity of the fuel cladding tube. There is a need to. (3) It is necessary to ensure the structural integrity that satisfies the requirements of (1) and (2) above against the assumed impact load at the time of a fall accident, etc. specified in the transportation regulations.

Even if all of the above (1) "subcriticality", (2) "heat removal", and (3) "structural integrity" are satisfied, the space in the transportation / storage container Is limited, so there was a problem that it was difficult to satisfy all of them. That is, the storage basket of the conventional spent nuclear fuel transportation / storage container shown in FIGS.
Since 1 and the grid-shaped body 18 are thin plates, it is difficult to secure structural strength. When storing the PWR spent nuclear fuel assembly,
Even if the plate thickness is increased in order to increase the structural strength, it is necessary to secure a predetermined porosity, so that the number of storage bodies is reduced by the increase in the plate thickness.

Further, since the lattice-shaped bodies 11 and 18 are thin plates, the heat transfer path is small, and the heat removal performance from the spent nuclear fuel assembly located at the center is low. In this respect, the use of a good heat conductive metal such as aluminum can improve the heat removal performance, but on the other hand, it lowers the structural strength. FIG. 5
The storage basket of the conventional spent nuclear fuel transportation / storage container shown in FIG. 2 is constructed by arranging the spent nuclear fuel assembly storage cells (square pipes) 14 in an aligned state in the vertical and horizontal directions. A space is formed between the storage cells 14, and the good heat transfer metal 15 is filled in the space, and the spent nuclear fuel assembly storage cells 14 are integrally assembled to the good heat transfer metal 15. Although the void hole 16 is formed, it is not possible to form a very large hole hole 16 in terms of structural strength.

In order to improve heat removal (and reduce weight),
Although the void is filled with the good heat-transfer metal 15, the good heat-transfer metal filler (structure) generally has low structural strength. The present invention is proposed in view of the above problems, and its object is to uniformly remove the decay heat of the spent nuclear fuel assembly to the outside of the basket and improve the subcriticality.
An object of the present invention is to provide a storage basket for a transportation / storage container for spent nuclear fuel, which can improve strength and heat transfer properties at the same time and can reduce the number of manufacturing steps.

[0012]

In order to achieve the above object, a storage basket for a spent nuclear fuel transportation / storage container according to the present invention comprises a plurality of rectangular parallelepipeds arranged in the spent nuclear fuel transportation / storage container. A structural strength member that holds the spent nuclear fuel assembly storage cells in a fixed shape at regular intervals, and a good heat transfer metal plate that is installed along the same gap between the storage cells (claim) 1).

In the storage basket of the transportation / storage container of the spent nuclear fuel, the good heat-transfer metal plates may be installed in parallel in the horizontal direction and may be installed so as to be orthogonal to each other in the vertical direction. 2).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Next, the storage basket of the transportation / storage container for spent nuclear fuel according to the present invention is used to transport the spent nuclear fuel for PWR /
A description will be given with reference to a first embodiment shown in FIGS. 1 and 2 applied to a storage basket of a storage container.

FIG. 1 is a perspective view of the storage basket, and FIG.
FIG. 2A is a plan view showing one good heat conductive metal plate among the upper and lower good heat conductive metal plates, and FIG. 2B is a plan view showing the other good heat conductive metal plate. 1a in Fig. 1 is PWR
A spent nuclear fuel assembly, 2 is a plurality of rectangular parallelepiped metallic spent nuclear fuel assembly storage cells, 3 is a plurality of support grid plates, and P
The WR spent nuclear fuel assembly 1a is stored in each spent nuclear fuel assembly storage cell 2. In this case, each spent nuclear fuel assembly storage cell 2 and each support grid 3 serve as structural strength members.

6a and 9a are good heat conductive metal plate portions, and the support grid 3 and the good heat conductive metal plate portions 6a and 9a are alternately stacked in a plurality of upper and lower stages. Each spent nuclear fuel assembly storage cell 2 is supported in an aligned state in the transportation / storage container. A space A is provided between two pairs of four.
Pairs of good heat transfer metal plates (strip-shaped metal plates) formed with
Is a good heat transfer metal plate (annular metal plate) that connects the respective good heat transfer metal plates 4, and the good heat transfer metal plate portion 6a has good heat transfer properties with these good heat transfer metal plates (strip metal plates) 4. It is composed of a metal plate (annular metal plate) 5.

Reference numeral 7 denotes a plurality of pairs of good heat-transfer metal plates (strip-shaped metal plates) each having a space A formed between two pairs, and reference numeral 8 denotes a good heat-transfer metal plate for connecting the respective good heat-transfer metal plates 7. In the (annular metal plate), the good heat transfer metal plate portion 9a is composed of the good heat transfer metal plate (strip metal plate) 7 and the good heat transfer metal plate (annular metal plate). The good heat transfer metal plate (strip metal plate) 4 of the good heat transfer metal plate portion 6a and the good heat transfer metal plate (strip metal plate) 7 of the good heat transfer metal plate portion 9a are orthogonal to each other, and the good heat transfer property is obtained. The good heat-transfer metal plate 4 of the metal plate portion 6a contacts the opposite side surfaces of the spent nuclear fuel assembly storage cell 2 made of each metal, while the good heat-transfer metal plate 7 of the good heat conductive metal plate portion 9a is made of each metal. The good heat transfer metal plate 4 and the good heat transfer metal plate 5 of each good heat transfer metal part 6a, and the good heat transfer metal part 9a of each good heat transfer metal part 6a are brought into contact with the opposite opposing side surfaces of the spent nuclear fuel assembly storage cell 2. PWR by the heat conductive metal plate 7 and the good heat conductive metal plate 8
The decay heat of the spent nuclear fuel assembly is uniformly removed to the outside of the basket.

(Second Embodiment) Next, the storage basket for the transportation / storage container of spent nuclear fuel of the present invention is applied to the storage basket for the transportation / storage container of BWR spent nuclear fuel.
The second mode will be described. FIG. 3A is a plan view showing one good heat-transfer metal plate among the upper and lower good heat-transfer metal plates, and FIG. 3B is a plan view showing the other good heat-transfer metal plate. 3 (c) is a plan view of the support grid plate.

FIG. 1b shows a BWR spent nuclear fuel assembly,
Reference numeral 2 denotes a plurality of rectangular parallelepiped metal spent nuclear fuel assembly storage cells, and the PWR spent nuclear fuel assembly storage cells 2 are stored in each spent nuclear fuel assembly storage cell 2. 6b is a good heat transfer metal plate portion, 4 is a plurality of good heat transfer metal plates (strip metal plates), 5 is a good heat transfer metal plate (annular metal plate) that connects the respective good heat transfer metal plates 4, and is good. The heat-conductive metal plate portion 6b includes the good heat-conductive metal plate (strip-shaped metal plate) 4 and the good heat-conductive metal plate (annular metal plate).
It is composed of 5 and 5.

9b is a good heat-transfer metal plate, 7 is a plurality of good heat-transfer metal plates (strip-shaped metal plates), and 8 is each good heat-transfer metal plate 7.
Is a good heat-transfer metal plate (annular metal plate), and the good heat-transfer metal plate portion 9b is a good heat-transfer inner metal plate (strip metal plate) 7 and a good heat-transfer outer metal plate (annular metal plate) 8 It is composed of In this BWR spent nuclear fuel transportation / storage container storage basket, since it is not necessary to secure the above-mentioned void A, the good heat-transfer metal plates 4 and 7 are parallel in the horizontal direction and orthogonal in the vertical direction. It suffices to arrange them side by side in the same direction, and the rectangular parallelepiped spent nuclear fuel assembly accommodating cells 2 are sandwiched by these good heat-transfer metal plates 4 and 7, and the structural stability of the entire basket is improved.

In this case, since each of the spent nuclear fuel assembly storage cells 2 is expected to have heat transfer performance, it may have a low thermal conductivity and a high strength material can be used. The body storage cell 2 serves as a structural strength member. Reference numeral 10 is a support grid plate, and since the support grid plate 10 only restrains the bundle of the spent nuclear fuel assembly storage cells 2 made of metal from the outside, the support grid plate 10 is different from the support grid plate 3 of FIG. Has a simple shape, which facilitates manufacturing (processing).

Next, the operation of the storage basket of the transportation / storage container for spent nuclear fuel shown in FIGS. 1 to 3 will be specifically described. The storage basket of the transportation / storage container for spent nuclear fuel of the present invention is configured as described above, and in the case of the PWR spent nuclear fuel shown in FIGS. 1 and 2, “subcriticality”, “heat removal”, and “health of structure”. The three mutually contradictory requirements of "property" can be satisfied at the same time, and in the case of the BWR spent nuclear fuel shown in FIG. 3, the two mutually contradictory requirements of "heat removal property" and "structural integrity" can be simultaneously satisfied. be able to. In other words, (a) In the case of PWR spent nuclear fuel, it is important in the evaluation of "subcriticality" that a certain distance is maintained between adjacent spent nuclear fuel assemblies even when an impact load is applied due to an accident or the like. To hold.

To secure the porosity between the spent nuclear fuel assemblies as much as possible, and efficiently decelerate the neutrons generated in the spent nuclear fuel by the water retained in the voids in a state where the storage basket is submerged. 2 points.
For the above requirements, the position of each spent nuclear fuel assembly storage cell is held by the support grid plate 3 made of a metal material or the like having excellent structural strength.

To meet the above requirements, metal plates 4 and 7 with good heat conductivity such as copper plates are installed in the gaps between the cells 2 for storing spent nuclear fuel assemblies. The good heat transfer metal plates 4 and 7 do not need to be considered as structural strength members and need only be capable of ensuring the required heat removal performance. Therefore, thin plates are sufficient, and the number of storage bodies is increased accordingly. (B) In both cases of the PWR spent nuclear fuel and the BWR spent nuclear fuel, it is important to secure as many heat transfer paths as possible with materials having good heat transfer properties in terms of evaluation of "heat removal property". .

To meet this requirement, good heat-transfer metal plates 4 and 7 such as copper plates, which are installed in the gaps between the spent nuclear fuel assembly storage cells 2, are arranged in parallel in the horizontal direction and in the vertical direction. Arrange them so that they are orthogonal to each other and secure many heat transfer paths. (C) In both cases of PWR spent nuclear fuel and BWR spent nuclear fuel, it is important to use the material with the highest mechanical strength as much as possible in evaluating the “structural integrity”.

Increasing the plate thickness of the structural strength member. 2 points. For the above requirements, as described in the above (a) and (b), the structural strength component and the heat transfer component are functionally divided, and regarding the structural soundness, focusing only on the strength, the mechanical strength of Use expensive materials.

In order to meet the above requirements, the thin heat-conducting metal plates 4 and 7 are used to avoid a decrease in the porosity, and the amount of the structural strength member is correspondingly increased to improve the structural soundness. Secure. (D) Further, the simple heat-transferable metal plates 4 and 7 are used, the structure of the storage basket is simplified, and the number of manufacturing steps is significantly reduced.

[0028]

As described above, the storage basket for the transportation / storage container for spent nuclear fuel of the present invention is used for transporting spent nuclear fuel.
A plurality of rectangular parallelepiped spent nuclear fuel assembly storage cells arranged in a storage container are held at regular intervals by structural strength members, and a good heat transfer metal plate is placed in the space between the storage cells along the same space. Since the heat-transfer metal plates are installed in parallel in the horizontal direction and alternately in the vertical direction, the decay heat of the spent nuclear fuel assemblies is evenly distributed outside the basket. Can be removed.

Further, since the good heat conductive metal plate is not expected to function as a structural strength member, a material having a high heat transfer coefficient can be used, and as a result, the amount of the good heat conductive metal plate can be reduced.
Particularly in the case of PWR spent nuclear fuel, the porosity between the storage cells can be increased and the subcriticality can be improved. In the past, BW
In the case of R spent nuclear fuel, each storage cell itself had to have structural strength and heat conductivity, but the structural strength is shared by the storage cell and the heat conductivity is shared by the good heat conductive metal plate. Therefore, the strength and the heat transfer property can be improved at the same time.

Further, the simple heat-transferable metal plates 4 and 7 are used, and the structure of the storage basket can be simplified.
The number of manufacturing steps can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment in which a storage basket for a transportation / storage container for spent nuclear fuel of the present invention is applied to a storage basket for a transportation / storage container for PWR spent nuclear fuel.

FIG. 2A and FIG. 2B are plan views of one and the other good heat conductive metal plates which are orthogonal to each other in the same storage basket.

3 (a) and 3 (b) are plan views of one and the other of the good heat conductive metal plates which are orthogonal to each other in the storage basket of the second form applied to the storage basket of the transport / storage container of BWR spent nuclear fuel, c) is a plan view of the support grid plate.

FIG. 4 (a) is a cross-sectional plan view showing an example of a storage basket of a conventional PWR spent nuclear fuel transportation / storage container.
(B) is a perspective view showing a lattice plate of the storage basket.

FIG. 5 is a cross-sectional plan view showing another example of a storage basket for a conventional PWR spent nuclear fuel transportation / storage container.

FIG. 6A is a cross-sectional plan view showing an example of a storage basket for a conventional BWR spent nuclear fuel transportation / storage container.
(B) is a perspective view showing a lattice plate of the storage basket.

FIG. 7 is a cross-sectional plan view showing another example of a storage basket of a conventional BWR spent nuclear fuel transportation / storage container.

[Explanation of symbols]

 1a PWR Spent Nuclear Fuel Assembly 1b BWR Spent Nuclear Fuel Assembly 2 Metal Spent Nuclear Fuel Assembly Storage Cell 3 Support Lattice Plate (Structural Strength Member) 4 Good Heat Transfer Metal Plate (Strip Metal Plate) 5 Good Heat Transfer Metal Plate (Annular metal plate) 6a Good heat transfer metal plate part 7 Good heat transfer metal plate (band metal plate) 8 Good heat transfer metal plate (annular metal plate) 9a Good heat transfer metal plate part 10 Support grid plate

Claims (2)

[Claims] 1. A structural strength member for holding a plurality of rectangular parallelepiped spent nuclear fuel assembly storage cells arranged in a spent nuclear fuel transportation / storage container at regular intervals, and a gap between the storage cells. A storage basket for the transportation and storage container of spent nuclear fuel, which is characterized by having a metal plate with good heat transfer installed along the same space. 2. The storage basket for a transportation / storage container for spent nuclear fuel according to claim 1, wherein the good heat-transfer metal plates are installed in parallel in a horizontal direction and are installed so as to be orthogonal to each other in a vertical direction.