JPH0659096A - Protected radioactive waste body and its manufacture - Google Patents

Abstract

PURPOSE:To provide a radioactive waste body highly protected in safety and a method for manufacturing it capable of certainly stabilizing the low level radioactive waste body in a protective container by a simple method. CONSTITUTION:Coarse aggregate 4 is filled in a protective container 1, and a cage type container 2 is fixed buried in this coarse aggregate 4. Additionally, a cement filler 6 is filled in the upper part of the protective container 1, and its part is permeated into the coarse aggregate 4. A low level radioactive waste substance 3 is contained in the cage type container 2. Even in the upper part of the cage type container 2, the coarse aggregate 4 can be filled. Concerning its manufacturing method, the coarse aggregate 4 is filled in the lower part of the protective container 1, the cage type container 2 containing the low level radioactive waste body is placed on it, additionally the coarse aggregate 4 is put in the circumference of the cage type container 2 and filled near to the upper face of the cage container 2, thereafter the cement filler 6 is injected, the cement filler 6 is permeated into the coarse aggregate 4 and a space in an inside cage and the protective container l is injected with the cement filler 6 until it is filled with the cement filler 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to protection of radioactive waste and a method for producing protected radioactive waste, and more specifically to a protective body in which low-level radioactive waste is put in a protective container and solidified. The present invention relates to a method for producing a protected radioactive waste body without leakage of radioactivity.

[0002]

2. Description of the Related Art If radioactive waste is discarded as it is,
Due to the adverse effects of radioactivity, such radioactive waste is placed under strict control.However, the low-level radioactive waste is placed in a protective container and is filled with various cement-based fillers. It is solidified and discarded or stored.

For solidifying low-level radioactive waste, there is a solidifying method using cement, asphalt, plastics or the like. Of these, there are many types of low-level radioactive waste of metal solids such as metal pieces generated during maintenance, vinyl insulation, etc., and their shapes and pollution forms are complicated, so solidification with cement-based fillers is effective. is there.

Conventionally, when a low-level radioactive waste is put in a protective container to make a radioactive protective body, the low-level radioactive waste is put in the protective container and a cement-based filler is filled. Or, as shown in FIG. 3, low-level radioactive miscellaneous solid waste 3 is placed in an inner basket 2 with legs 5, the inner basket 2 is set in a protective container, and then cement, sand, etc. The cement-based filler composed of the mixture is poured and filled. The upper part of the protective container is produced by previously forming a lid and integrally molding it, and by filling a gap formed between the lid and the lid later with a cement-based filler.

[0005]

However, in the above-mentioned method that does not use the inner basket, the safety is low because the radioactive waste directly contacts the protective container. Further, when the waste has a low strength like a heat insulating material, the strength cannot be maintained.

Further, in the case of manufacturing a radioactive protective body by a method using an inner basket with legs as shown in FIG. 3, when the protective container is damaged for some reason, the legs of the inner car and the protective container come into contact with each other. However, there was a drawback that the radiation leaked through it. Steel drums and containers are generally used as protective containers, but the drastic improvement in corrosion resistance of the protective containers and ensuring safety complicate the process and increase the cost. was there.

[0007] Therefore, the present inventors have made various studies on the above-mentioned drawbacks, found that a manufacturing method for overcoming the above-mentioned drawbacks by a simple method and that an excellent radioactive protective body can be obtained by the method, and make the present invention. Came to.

[0008] Therefore, it is an object of the present invention to provide a protected radioactive waste in which a low level of radioactive waste is sufficiently fixed in a protective container and does not cause radioactive leakage. Another object of the present invention is to provide a method for producing a protected radioactive waste in which a low level radioactive waste can be reliably immobilized in a protective container in a simple manner.

[0009]

The above objects of the present invention are as follows.
The present invention can be achieved by the following inventions. (1) In a radioactive waste product in which an inner basket containing low-level radioactive waste carried in a protective container is solidified with a cement-based filler, the aggregate between the container and the inner basket is filled with coarse aggregate. The protected radioactive waste is characterized in that the coarse aggregate and the voids in the inner cage are integrally injected with a cement-based filler.

(2) Coarse aggregate is filled in the lower part of the protective container, a basket-like container containing low-level radioactive waste is placed thereon, and coarse aggregate is put around the basket-like container. After filling up to near the upper surface of the cage, the cement-based filler is injected to allow the cement-based filler to permeate into the coarse aggregate and voids in the inner cage, and the protective container is filled with the cement-based filler. A method for producing a protected radioactive waste, characterized in that it is injected up to.

(3) A method for producing a protected radioactive waste material according to the method (2), wherein the upper part of the basket-like container is also filled with the coarse aggregate.

The present invention will be described in more detail below. According to the present invention, by placing the inner car containing the low-level radioactive waste on the pre-filled coarse aggregate, the arrangement of the inner car is stably fixed without contact with the protective container.

Further, in the present invention, the periphery of the inner cage containing the low-level radioactive waste is preliminarily filled with coarse aggregate to be fixed, and then the cement type filler is injected by injecting the cement type filler. Since it is infiltrated into the coarse aggregate to form concrete, concrete filling can be done with a simple method under a stable arrangement.

The low-level radioactive waste used in the present invention includes all parts, equipment, instruments, heat insulating materials, vinyl, etc. which have been exposed to radioactivity. As the protective container, a drum can is mainly used, but the container is not limited to this, and any container may be used as long as it has durability, and the material thereof is metal, plastics, or the like. There is no particular limitation.

As the inner cage for containing the low-level radioactive waste, a cage, a net-like vessel, a vessel with a permeation hole, etc. are used, but an ordinary vessel without holes may be used. In this case, the basket,
It is preferable to use a net-like container, a container having a permeation hole, or the like, because the cement-based filler permeates and fills the gap or the coarse aggregate void portion of the low-level radioactive waste through the hole.

The coarse aggregate used in the present invention is preferably gravel or crushed stone having a maximum size of 40 mm or less and 15 to 25 mm. Also, in order to completely fill every corner, the minimum dimension must be at least 5 mm, preferably 1
It is 0 mm or more. As the cement-based filler, those containing normal cement as a component such as Portland cement and mixed cement can be used, and the kind thereof is not particularly limited.
It is also possible to use rapid hardening cement.

Cement-based filler, cement, water, and if necessary, sand having a size of 5 mm or less, preferably 2.5 mm or less, or a chemical admixture such as an AE water reducing agent or a high-performance water reducing agent, or an admixture of aluminum powder, fly ash, etc. Materials can be used. By creating a concrete layer around the waste material, it is possible to secure not only the radiation protection performance but also the safety against the load generated during transportation and burial.

Further, when the coarse aggregate is added to the upper part of the inner car, the rise of the heat insulating material and vinyl can be suppressed and the concrete portion is increased, so that the strength and durability are improved. A suitable filling thickness of the coarse aggregate is 2.5 to 10 cm. If the filling thickness is less than 2.5 cm, it is difficult to fill the aggregate,
If it exceeds 10 cm, it becomes difficult for the cement-based filler to permeate, and the volume of the inner cage decreases significantly.

[0019]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 FIG. 1 shows a sectional view of an embodiment of the protected radioactive waste material of the present invention. In FIG. 1, 1 is a drum can used as a protective container. Is filled with coarse aggregate 4, and further embedded in the coarse aggregate 4 to fix the inner car 2. Further, the cement-based filler 6 is filled in the upper part of the drum, and a part of the cement-based filler 6 penetrates into the coarse aggregate 4.
The inner basket contains low-level radioactive waste 3.

FIG. 2 is a sectional view showing another embodiment of the present invention. In FIG. 2, the coarse aggregate 4 is also laid on the upper part of the inner car, and the cement-based filler 6 penetrates into the coarse aggregate 4 and the voids of the low-level radioactive waste body 3.

In this protected radioactive waste, the inner car 2 is firmly fixed by the coarse aggregate 4 filled in advance. Furthermore, since the cement-based filler 6 is injected and penetrates into the spaces between the coarse aggregates 4 and the voids of the radioactive waste body 3 and is hardened, it becomes as if the radioactive waste body 3 is confined in the concrete container and prevents leakage of radioactivity. be able to.

Embodiment 2 Further, according to the present invention, the inner cage can be securely fixed by the following manufacturing method to prevent the leakage of radioactivity. First, the coarse aggregate 4 is spread over the lower portion of the drum 1 and then the inner car 2 containing the low-level radioactive waste 3 is placed on the coarse aggregate 4 and the lid 22 is put on the car. However, the lid 22 may be omitted. Further, the inner car 2 is fixed by filling the coarse aggregate 4 around the inner car 2.

Since it is necessary for the filler to surely penetrate into the gap, 16 to 20 seconds is preferable for the P funnel which is an index of fluidity. An example of a mixture satisfying this condition is 100 parts by weight of Portland cement and 80 parts of sand. Parts by weight, 50 parts by weight of water and a trace amount of admixture. This cement filler 6 is poured from the upper or lower part of the drum can 1. The cement filler 6 penetrates by sewn in the voids of the coarse aggregate 4 to penetrate the coarse aggregate 4.
The inside of the drum can 1 is filled as well as filled up.

After that, the lid 11 of the drum 1 is closed to seal the lid. If necessary, an injection port may be provided in the lid 11 and re-injection may be performed to eliminate the gap. As a result, the inner basket can be sufficiently fixed by a simple manufacturing method, and a highly safe and protected radioactive waste can be manufactured.

[0026]

As described above, according to the present invention, since the inner car is previously fixed with the coarse aggregate, it can be stably fixed at a predetermined place, and after the inner car is previously fixed with the coarse aggregate, the cement-based filling is performed. Since it is filled with material to produce a concrete-filled radioactive waste, the inner basket can be sufficiently fixed by a simple method,
A safe and protected radioactive waste can be produced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a protective structure for a protected radioactive waste body of the present invention.

FIG. 2 is a cross-sectional view showing another protective structure for the protected radioactive waste according to the present invention.

FIG. 3 is a cross-sectional view showing a structure of a conventional inner car.

[Explanation of symbols]

 1 Protective Container 2 Inner Cage 3 Radioactive Waste 4 Coarse Aggregate 5 Inner Cage Leg 6 Cementitious Filler 11, 12 Lid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Koga 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Corporation Cement Research Institute

Claims (3)

[Claims] 1. A radioactive waste body in which an inner basket containing low-level radioactive waste bodies carried into a protective container is solidified with a cement-based filler, and coarse aggregate is provided in the gap between the container and the inner basket. And the voids in the coarse aggregate and the inner cage are integrally injected with a cement-based filler. 2. A cage in which coarse aggregate is filled in a lower portion of a protective container, a basket-like container containing low-level radioactive waste is placed on the container, and the aggregate is put around the basket-like container. After filling up to near the upper surface of the cylindrical container, injecting the cement-based filler to allow the cement-based filler to penetrate into the voids in the coarse aggregate and the inner cage and until the protective container is filled with the cement-based filler. A method for producing protected radioactive waste, characterized in that it is injected. 3. The method for producing a protected radioactive waste according to claim 2, wherein the upper part of the basket-like container is also filled with the coarse aggregate.