JPS62112098A - Method of mixing nuclear fuel substance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for mixing nuclear fuel materials, which are uranium, plutonium, and mixed oxides thereof.

[Prior art]

When handling nuclear fuel material, the mass of this nuclear fuel material,
Criticality safety is managed by limiting the shape (volume, diameter, thickness) of the equipment and container.In addition, there are methods to limit the rate at which nuclear fuel material is compressed by moderators such as water (H2O). The deceleration limiting method) is also adopted.

By the way, when preparing raw material powder for nuclear fuel pellets,
Nuclear fuel materials such as uranium, plutonium, and their mixed oxides are uniformly mixed and packed into a criticality-safe container.

[Problems to be solved by the present invention]

However, in the conventional method of mixing nuclear fuel materials, there are limitations on criticality safety control as mentioned above, so the loft size, that is, the size of the powder container or blender, cannot be increased without limit when mixing nuclear fuel powder. However, for light water reactor fuel with a degree of compression of 5 or less, it is possible to apply a deceleration limit and make the loft size up to about 3 tons, that is, the size of a powder container or blender. Difficult to make into powder container or blender size.

In addition, in fuels containing enriched uranium and plutonium of Tati or higher, criticality safety control restrictions are even stricter, and the loft size of the raw material powder becomes even smaller.

This reduction in loft size means that the number of lots increases, and therefore the number of tests and analyzes of the chemical and physical properties of the powder that are performed for each lot of nuclear fuel powder increases, and In the manufacturing process, it is often necessary to change manufacturing conditions due to changes in powder physical properties of each lot, resulting in problems such as low productivity.

An object of the present invention is to provide a method for mixing nuclear fuel materials that solves the above-mentioned problems of conventional methods for mixing nuclear fuel materials.

[Means for solving problems]

In order to achieve the above object, the present invention has the following configuration. That is, after filling and mixing nuclear fuel powder into a container that has undergone criticality safety control, the nuclear fuel powder is equally divided and filled into multiple containers of the same size as the previous container, and this process is repeated to form multiple containers. The nuclear fuel powder in these multiple containers is then mixed.

The method of the present invention will be explained in detail below.

The method of mixing nuclear fuel materials of the present invention first begins with a criticality-safe container shape (limited volume, diameter, thickness, etc.).
Vessel with limited deceleration (Bren II”-tDg vessel ft
Nuclear fuel powders containing tr) C0,3~/000t') K, uranium, plutonium, and their mixed oxides are filled and mixed to make these nuclear fuel powders uniform.

Next, the nuclear fuel powder homogenized by the mixing is divided into equal parts and filled into a plurality of empty containers of the same size as the plurality of criticality-safe containers (including the blender container). Next, the nuclear fuel powder in a plurality of criticality-controlled containers (including a blender) filled with equally divided nuclear fuel powder is mixed uniformly.

〔Effect of the invention〕

According to the nuclear fuel material mixing method of the present invention, the loft size of the nuclear fuel powder (raw material powder) can be further increased compared to the conventional nuclear fuel material mixing method, and the chemical and physical properties of the powder can be inspected. , it is economical because it can significantly reduce the number of analyzes υ, and in the fuel pellet manufacturing process, it is necessary to change the manufacturing conditions if the powder characteristics (sinterability, etc.) differ from lot to lot. However, since the loft size can now be increased, there is no longer a need to frequently change production conditions, and fuel pellets can be produced stably under the same conditions for a long time, greatly increasing productivity. can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

Reference numeral 1 in FIG. 7 is a powder hopper, and a screw feeder 2 is provided at the bottom of the powder hopper 1. The screw feeder 2 is connected to a ball pulp 3 and a powder container 5 under criticality safety control via an expansion joint 4. Further, a ball pulp 11 is provided below the powder container 5. This powder container 5 is placed on a weighing machine 6. 7 is a motor.

Reference numeral 8 denotes a blender, and a powder container 5 can be rotatably attached to the blender 8 via a shaft 9.

Further, a screw feeder 13 can be connected to the ball pulp 11 of the lower blade of the powder container 5 at a predetermined location via an expansion joint 12. A plurality of equally divided containers 16 having the same configuration and under criticality safety control can be detachably connected to the screw feeder 13 via a ball pulp 14 and an expansion joint 15, respectively. This equally divided container 16 is placed on a weighing machine 20. These plural equally divided containers 16 are of the same scale as the powder container 5. Each equally divided container 16 can be rotatably attached to the blender 17 via a shaft 18.

19 is a motor.

When mixing nuclear fuel material (powder), the nuclear fuel material powder, which is uranium, plutonium, and mixed oxides thereof, is introduced into the powder hopper IK, the ball pulp 3 is opened, and the screw feeder 2 is operated. The nuclear fuel powder is sent to the powder container 5 side, passes through the ball valve 3 and the expansion joint 4, and is filled into the powder container 5.

Next, the powder container 5 is removed from the expansion joint 4, weighed by a weighing machine 6, and checked at P1 to see if it has a predetermined weight.

Next, the powder container 5 that passes the measurement is attached to the blender 8 and rotated. Thereby, the nuclear fuel powder in the powder container 5 is mixed uniformly.

Next, the powder container 5 with the nuclear fuel powder mixed therein is transported to a predetermined cylinder location, and is passed through a ball valve 11, an expansion joint 12, a screw feeder 13, a ball valve 14, and an expansion joint 15 to a plurality of cylinders. The divided containers 16 are connected together.

Next, the ball pulp 11.14 is opened, the screw feeder 13 is operated, and the powder container 5 is divided into equal parts into the container 16.
is filled with a predetermined amount of nuclear fuel powder.

Next, the expansion joint 15 is removed from this equally dividing container 16, and similarly to this equally dividing container 16, other equally dividing containers 16 are sequentially filled with a fixed amount of nuclear fuel powder. When the powder container 5 is used up, the above operation is repeated to attach the next powder container 5 to a predetermined location.

Next, when the weight of the powder in each equal division container 16 reaches a constant value according to the weighing of the weighing machine 20, each division container 16 is
They are sequentially attached to the blender 17 and rotated to uniformly mix the nuclear fuel powder inside.

Due to this divided mixing, the nuclear fuel powder inside the plurality of equal division containers 16 must be from the same lot, and representative samples are collected from seven of the plurality of equal division containers 16 for powder physical property measurement and analysis. , just measure it.

According to this embodiment, the lot size of the nuclear fuel powder can be further increased compared to the conventional method of mixing nuclear fuel materials, and the same effects as those of the present invention can be achieved.

In addition, the internal volume of the powder container 5 and the equally divided container 16 is 0.3~! when mixing plutonium and highly enriched uranium oxide powder! It is as small as -18 degrees, while for low enrichment uranium it is about /3t~10001.

Next, another embodiment of the present invention will be described based on FIG. 21 in Figure 1 is a powder hopper, and this powder hopper 2
A screw feeder 23 having a motor 22 is provided at the bottom of the feeder 1 . A container-fixed blender melter 25 whose criticality safety is controlled is connected to the screw feeder 23 via a ball pulp 24. This blender 25 is relatively medium to small scale. This blender 25 is provided with a damper 25a. A scale hopper 27 is connected to the blender 25 via an expansion joint 26, and a Teflow tank 30 is connected to the scale hopper 27 via a rotary valve 28 and an expansion joint 29. This blow tank 30 is provided with a blower 30a.

Further, a vibrator 31 is connected to the blow tank 30,
This pipe 31 includes a switching valve (3-way valve) 32. 33. Branch pipes 35, 36, and 37 are provided via 34. A plender 38 is connected to the tip of the vibrator 31, and branch pipes 35, 36.3
Plenders 39, 40, and 41 are connected to 7, respectively. Each of the prenders 38, 39, 40.41 has a damper 38a, 39a, 40a, respectively.
41 a. Each of these blenders 38,3
9,40.41 is critical safety controlled and is on the same scale as the Blader-25 mentioned above. Each planner
38, 39° and 40.41 are critical safety controlled volumes with significantly larger loft sizes than conventional ones 542 and 43, respectively.
44.45 are connected.

Therefore, when mixing nuclear fuel powder, the nuclear fuel powder is put into the powder hopper 21, and the screw feeder 23.
Blender 25, 38, 39, 40° 41, blower 3
0a to open the ball valve 24. Then, the nuclear fuel powder is sent into the blender 25, where it is mixed almost evenly.

Next, the damper 25a is opened and the nuclear fuel powder is put into the scale hopper 27, and its weight is weighed in the scale hopper (27) to confirm that the nuclear fuel powder in the scale hopper 27 is a predetermined amount.

Next, the rotary valve 28 is turned to sequentially supply a certain amount of equally divided powder to the blow tank 30. Then, each time, the blower tank 30 is opened by the action of the blower 30a.
The nuclear fuel powder inside is passed through the pipe 31 to each bulengoo 38,
39, 40, and sent to the 41 side.
4゜Then, the sequential switching valve 32
, 33, 34 and turn the kettle blender 38, 39,
A certain amount of equally divided nuclear fuel powder is fed into each of the blenders 38, 39, 40, and 41, and the nuclear fuel powder in these blenders is uniformly mixed.

After this, each damper 38a, 39a, 40
a.

Open 41a and containers 42, 43, 44.45K.

Filled with nuclear fuel powder homogenized and mixed in Brengu 38, 39, 40, and 41, respectively.

By repeating the process without the above operations, the lot size of the nuclear fuel powder can be further increased compared to the conventional method of mixing nuclear fuel materials, and the mixing precision of the nuclear fuel powder can be greatly improved. Effects similar to those of the present invention described above can be achieved.

In addition, in this embodiment, there is no need to attach the container to the blender or to move the container, so the working efficiency is improved and it is economical compared to the previous embodiment.

[Brief explanation of drawings]

FIG. 7 is a schematic explanatory diagram showing an example of an apparatus for implementing the method of the present invention, and FIG. 1 is a schematic explanatory diagram showing another example of the apparatus for implementing the method of the present invention. 5... Bent powder container, 8, 17, 25. 38, 39° 40
．． 41... Blender, 1o... Container for dividing into songs, 42.43, 44.45... Container for songs.

Claims (1)

[Claims] After filling and mixing nuclear fuel powder into a criticality-safe container, the nuclear fuel powder is equally divided and filled into multiple containers of the same size as the previous container, and this process is repeated to fill multiple containers. A method for mixing nuclear fuel material, which comprises adding a certain amount of nuclear fuel powder, and then mixing the nuclear fuel powder in a plurality of containers.