JPS608480B2 - Packaging for chemical treatment of scattering radioactive solid materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a package for packaging scattering radioactive solid materials during transport to a chemical processing facility and allowing them to be chemically processed as they are after transport.

Containers for transporting radioactive materials have different design conditions depending on the type and amount of radioactive materials they contain, but in any case, even in a free fall or in the event of a hypothetical fire,
In addition to ensuring that the radioactivity of the contents does not leak out from the sealed boundaries of the container and pose a hazard to the general public, it is also important to minimize contamination of radiation-controlled areas at transport container removal or entry facilities. You are requested to do so in a timely manner.

For example, when transporting scattering irradiated fuel pellets or granular fuel together with their cutting chips to a chemical processing facility, etc., these solid materials are placed in a metal container and the diamond part is sealed tightly. It is considered important to seal in an excellent condition.

In particular, when the fugitive radioactive solid material is plutonium mixed oxide fuel (Pu020U02), the plutonium has a strong plexus, so the fine powder of plutonium becomes an aerosol dispersed in the atmosphere and is inhaled into the human body. ``The permissible human body burden of plutonium is limited to an extremely low value.Therefore, it is considered that there are such scattering fuel pellets, and it is also possible to transport pellet chips immersed in water.'' However, it is ``unfavorable from the standpoint of handling upon opening, especially from the standpoint of preventing contamination within the hot cell.
Therefore, the conventional method is to put fuel materials etc. into a metal inner container in advance, weld the outer part around the circumference, create an atmosphere of air or inert gas inside, and then transport it in a transport container, and then transport it to the destination. The method used was to open the inner container with a welded lid at a chemical processing facility. However, with this method, whether mechanical cutting or fusing is used to open the package, it is impossible to avoid scattering radioactive solid material into the hot cell. ``Naturally, there is a mechanical cut to open the package, and it must be equipped with a fusing device.''

The purpose of the present invention is to eliminate such drawbacks of the prior art,
Our goal is to provide a package that can not only safely transport scattering radioactive solid materials, but also minimize radioactive contamination at the chemical processing facility where it is delivered, and that does not require an opening device. be.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a model showing the state in which the package according to the present invention is actually used. A package 2 containing a scattering radioactive collective substance 1 is housed in an intermediate container 3, which is loaded into a rigidly constructed transport container 4.
The interiors of the intermediate container 3 and transport container 4 are usually filled with air or inert gas at around one atmosphere. The transport container 4 may be the same as conventionally known containers, and is manufactured as a sealed container with sufficient shielding performance for transportation on public roads.

The transport container is connected to an inlet of a reprocessing facility, etc., and the lid 5 is moved to allow the intermediate container 3 to pass through the inlet to a hot melting tank of the reprocessing facility. Inserted into cells etc. and"
The package 2 is removed from the intermediate container 3 in the hot cell. Now, the package 2 according to the present invention is a container with a lid made of foamed metal or sintered metal that has liquid permeability and is made of a material that is easily dissolved in the solution in the first stage dissolution tank of the reprocessing facility. It is.

This package 2 is generally cylindrical in shape, and the lozenge 7 provided on the top of the package 2 is of a structure that allows it to be easily closed by manipulator operation inside the cell. As a material for the compacted metal, Ni
, Ni-Cr, Nj-Cr-ALNi-Cr-Fe, and other metals and metal alloys can be used.

Cu and Pb are undesirable because they may contaminate the ion exchange resin used in the extraction and separation process or may precipitate in the piping system. Sintered metal has the advantage of being easy to obtain in the form of a thick-walled cylinder with sufficient strength, but since the porosity is smaller than that of foamed metal, it takes a longer time to melt and the amount of melted metal increases. It is inferior to foam metal in that the melt must be readjusted frequently. If the pores of the foamed metal are too large, there is a risk that the activated material powder may pass through, so it is preferable that the pores be as small as possible.

Usually, a material with an average pore diameter of about 0.15 is used.
The higher the porosity of the metal foam, the better, but it is usually 90%.
Use a moderate amount. If such a package made of foamed metal or sintered metal is used, contamination of the inner surface of the intermediate container can be largely prevented, but by covering the inner surface of the main package with a soluble metal film such as aluminum, the inner surface can be more securely contaminated. Contamination can be prevented.

The package 2 containing spent uranium dioxide fuel pellets, plutonium dioxide mixed fuel pellets, or a mixture such as crushed chips of these pellets, as a scattering radioactive solid material, is It is transported to a chemical processing facility, where it is immersed directly into the first-stage dissolution tank, where it is chemically processed without dispersing radioactive materials.

FIG. 2 is an explanatory diagram showing one embodiment of the present invention.

In this embodiment, the package 2 has a foamed metal cylindrical body 10 made of pure nickel, and has a mesh wire hook 1 made of nickel arranged on the outer surface for strength reinforcement, and a lid made of the same foamed metal at the upper entrance. 12 is provided so as to be openable and closable. In addition, there is a hanging odor oven 3 on the top of the lid tatami 2. There is also a lid army 2 and a cylindrical turtle Q.
A lid stopper 84 is provided between the upper parts of the cell, and the stopper and lifting part are designed so that they can be operated by a manipulator inside the hot odor cell. By the way, in the spent fuel reprocessing process, "First, about 4 fuel assemblies are cut into 2 to 4 lengths in the length direction of the fuel rods, and the cut fuel chips and shreds are The mixture between the fuel claddings is put into a high-temperature nitric acid solution tank, and the fuel solution is sent to the next separation process.

Therefore, the foamed metal composing the package 2 that encases these cut fuel chips, cut fuel cladding tubes, etc. is made of, for example, pure nickel, which has a porosity of about 90% and an average pore size of about 0.15.
If you use the one on the side, when it is immersed in the specified reprocessed fuel melt, the solution will pass through the foamed metal material, dissolving the fuel substance inside, and also melting the package itself in a short time. Resulting in.

In addition, the foamed metal material has a microstructure that looks like a spongy three-dimensional structure.
Since it has dimensional pores and the pure amount of metal constituting the material is small compared to its volume, the amount of dissolved nickel is also extremely small and has almost no effect on changes in the concentration of the solution. In addition, if the pores of the foamed metal are sufficiently small, the scattered fine powder can be trapped by its wall thickness, and at least the contamination of the inside of the intermediate container with radioactive fine powder can be minimized. can.

Moreover, scattering radioactive solid materials can be atomized by shocks and vibrations during transportation, but if they are covered with foamed metal, they can become large particles due to their plastic nature due to their spongy structure. The impact is absorbed by the plastic deformation of the foamed metal package itself, resulting in the effect that no damage is caused to the contents.

Since the present invention is a package configured as described above, it is possible to safely transport scattering radioactive solid materials together with a transport container provided on the outside, and it is easy to handle and transported to the destination. radioactive contamination at chemical processing facilities
It has many excellent effects, such as being able to limit the amount of waste it takes, does not require special lid opening equipment, and can be used as is in conventional reprocessing processes, which will bring ground-breaking benefits to this field in the future. This is something that can be expected.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view showing an example of a usage state of a package according to the present invention, and FIG. 2 is an explanatory view showing an example of the present invention. 1...Dispersible radioactive solid substance, 2...Packaging body, 3...Intermediate container, 4...Transportation container, 10...Foaming Metal cylindrical body, 11...
・Mesh wire, 7, 12... Lid. Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. A package for packaging a scattering radioactive solid substance, stored in a transport container, and transported to a chemical processing facility, the package being made of liquid-permeable foamed metal or A container with a lid that is made of sintered metal and a material that easily dissolves in the solution in the first-stage dissolution tank of the reprocessing facility, and can be chemically processed by being thrown into the dissolution tank together with the package. A package for chemical treatment of scattering radioactive solid substances, characterized by: 2. The package according to claim 1, wherein the lidded container has an inner surface lined with a thin film of soluble metal.