Basket for a Transportation and Storage Cask for Spent Nuclear Fuel from a Pressurized Water Reactor

Abstract

Basket for a transportation and storage cask for spent nuclear fuel from a pressurized water reactor, containing a base on which steel disks are fixed in height and aluminum disks are located between the steel disks equidistantly. Vertical clamping elements connect the steel and aluminum disks into a section cover. Two rows of apertures are made in the disks relative to their axis, two aperture in the inner row and eight in the outer row. The apertures comprise channels. Vertical clamping elements are located along the outer perimeter of the disks. The basket is made of one section and equipped with additional vertical disk clamping elements located in a circle between axes of the inner and outer rows of apertures in the disks The apertures and channels are round so that canisters for spent fuel assemblies can be placed therin. Grooves and hooks for canisters are provided in the base.

Claims

1. A basket for a transportation and storage cask for spent nuclear fuel from a pressurized water reactor, containing a base on which steel disks are fixed in height and aluminum disks located between the steel disks equidistant from each other, vertical clamping elements connecting the steel and aluminum disks into a section cover, while two rows of apertures are made in the disks relative to their axis, channels are installed in the apertures, and vertical clamping elements are located along the outer perimeter of the disks, characterized in that the basket is made of one section and is equipped with additional vertical disk clamping elements located in a circle between axes of the inner and outer rows of apertures in the disks, the apertures and channels are made round with the possibility of placing canisters for spent fuel assemblies in them, while grooves and hooks for canisters are made in the base of the basket, two apertures are made in the inner row of apertures, and eight of those in the outer row.

2. The basket according to claim 1, characterized in that the basket section is provided with additional steel disks, the steel disks being equidistant from the aluminum disks.

3. The basket, according to claim 2, characterized in that the aluminum and steel disks alternate as follows: 4-1-4-1-3-1-3-1-3-1-3-1, starting from the base.

4. The cover according to claim 1, characterized in that the vertical disk clamping elements are made in the form of strainers.

Description

[0026] The invention is illustrated by drawings, where FIG. 1 shows the basket (longitudinal section), FIG. 2 shows the basket (cross section).

[0027] The basket is a metal structure consisting of a base (supporting disk) 1, heat-removing aluminum disks 2, intermediate disks 3, channels 4 for sealed canisters, vertical clamping elements, in this case, ties 5 and 6.

[0028] Base (1)—welded structure made of corrosion-resistant steel performs the function of the carrying element of the basket. From above, the base (1) has (7) grooves and (8) hooks for installing canisters. The hooks (8) can be made, for example, in the form of a mating hole for the key in the canister, made in the groove (6) and off-centered.

[0029] The basket may be fitted with additional steel disks (3). Disks (2) and (3) are equidistant to each other in certain order, thereat two rows of round apertures are made in disks (2) and (3) relative to their axes. There are two apertures made in the inner row of apertures and eight—in the outer. Channels (4) (pipes) made of boron steel are installed in the holes, and the channels are made with the possibility of placing sealed canisters with spent fuel assemblies into them. Channels (4) protect the sealed canisters (4) from mechanical damage.

[0030] Aluminum disks (2) simultaneously solve safety problems and perform the functions of heat removal from the spent fuel assemblies. Intermediate disks (3) are made of corrosion-resistant steel.

[0031] Sleeves (9) made of aluminum alloy are installed between steel disks 3 and aluminum disks (2). Assembling all parts of the basket into a single section is ensured by strainers (5) and (6), located along the perimeter of disks (2) and (3), as well as around the circumference between the axis of inner and outer rows of apertures.

[0032] Strainers (5, 6) are forming a stud, the lower end of which is screwed into the supporting disk (1), and the upper end is fixed with a nut (10).

[0033] Assembly of the basket is carried out as follows:

[0034] Strainers (5) and (6) are screwed tightly into supporting disk (1), which is the carrying element of the basket. Further, bushings (9), disks (2) and (3) are installed on strainers (5) and (6), bushings (9) are also installed between disks (2) of the cover and intermediate disks (3). The sequence of alternation of disks (3) and (2) is as follows: 4-1-4-1-3-1-3-1-3-1-3-1 starting form supporting disk (1). Such disposition of disks ensures better heat removal from the SFA. Further, channels (4) for sealed canisters in the amount of 10 pieces are passed through the apertures of the disks (2) and (3). Further, bushings 9 are installed on the strainers (5), (6) and the last steel disk, the whole structure is fixed with nuts (10), forming a section of the basket.

[0035] The operations for loading/unloading sealed canisters into the basket are as follows.

[0036] With the help of a reloading machine and a special gripper, a sealed canister with nonconforming spent fuel assemblies is guided and lowered into channel (4) of the basket until it stops. In this case, the lock on the bottom of the canister (key) must fall into hole (8) at the bottom of the base (1), which ensures that the canister does not rotate around the axis during transportation and when working with the gripper of the reloading machine. Next, the grip and the canister are released. All other canisters are loaded into the cells of the canisters one by one. Unloading of sealed canisters is carried out in the reverse order.

[0037] The possibility to install sealed canisters for spent fuel assemblies into canals (4) of the basket makes it possible to transport nonconforming spent fuel assemblies to the TSC without spreading radioactive substances into the environment, which ensures the safety requirement for the transportation and storage of spent nuclear fuel.

[0038] The round shape of the channels, grooves (7) and the hook (8) for canisters at the base of the basket allow you to place the canisters in the basket and exclude their damage during operation.

[0039] The basket, made of one single section, simplifies its design, ensures the alignment of the apertures for channels 4, and improves heat removal from the spent fuel assemblies due to the uniform distribution of steel and heat-removing disks along the height.

[0040] An additional row of strainers (6) is a replacement for the central pipe, allowing the optimal number of nonconforming spent fuel assemblies to be placed with a reduced distance between them, while maintaining the dimensions of the existing TSC and providing the required strength characteristics of the basket during operation and in emergency situations.

[0041] Thus, the proposed TSC ensures the transportation and storage of the optimal number of nonconforming spent fuel assemblies from VVER-1000/1200 reactors (10 pieces) in a container basket that fits into the dimensions of the existing TSC, while ensuring transportation safety parameters, in particular, radiation safety, nuclear safety and heat removal from SFA.