JP2001183495A - Method of manufacturing cartridge for radioactive waste fluid disposal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a cartridge for radioactive waste fluid disposal, having as sufficient compression and impulse strength as a conventional cartridge for radioactive waste fluid disposal and suitable for mass-production. SOLUTION: The method of manufacturing the cartridge for radioactive waste fluid disposal comprises preparing of a raw material slurry with a raw material cotton having disorganized glass fibers, an inorganic binder and a water, pouring the raw material slurry into a mold, dewatering and forming it into a predetermined shape, and giving heat treatment to the dewatered molding to which the glass fibers are welded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a cartridge for treating radioactive waste liquid, which is used for impregnating an object to be treated with heat, melting it by heating, and vitrifying it when disposing of the radioactive waste liquid. .

[0002]

2. Description of the Related Art When a spent fuel used in nuclear power is reprocessed in a reprocessing plant, a high-level radioactive liquid waste containing nitric acid containing uranium, transuranium elements and fission products is produced as a by-product. Therefore, a technique for safely and efficiently disposing of such radioactive waste liquid is desired.

Conventionally, in order to treat such a radioactive waste liquid, the radioactive waste liquid is directly or denitrated and concentrated to form a slurry, mixed with a glass raw material and supplied to a high-temperature glass melting furnace, and the waste liquid in the furnace is heated in the furnace. A technique has been developed in which a liquid component is evaporated and a radioactive substance is melted in glass, and the molten glass is poured into a stainless steel container and solidified.

In such a waste liquid treatment technique, when the waste liquid boils violently in a glass melting furnace, dust containing a large amount of radioactive substances is generated and flows out together with the exhaust gas. It is important to prevent it.

The prior art of this type is disclosed in Japanese Patent Publication No. 4-2.
In Japanese Patent Publication No. 40, a glass fiber is filled in a mold, and the glass fiber is heated and partially fused to prepare a radioactive waste liquid treatment cartridge molded into a predetermined shape. Techniques relating to a radioactive waste liquid treatment cartridge that is impregnated, heated and melted, and vitrified have already been proposed.

[0006]

However, when the cartridge of the above technology is used, a large amount of dust is generated when the cartridge is conveyed to a heating and melting furnace, which causes a trouble in the apparatus, and requires much trouble in cleaning and maintenance of the apparatus. Problem,
In addition, since the cartridge is formed only by partial fusion of glass fibers without using a binder, there is a problem that a sufficient compressive strength and impact strength cannot be obtained and a problem of powder drop during use.

Further, when the cartridge of the above-mentioned technology is used, the glass fiber plate is rolled and pressed into the mold, thereby filling the inside of the mold, and heat-treating the glass fiber plate to partially fuse it.
Since it is formed into a predetermined shape, it is not suitable for mass production, and a large amount of time is required to produce a large number of pieces, which leads to a problem of an increase in cost.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a radioactive waste liquid processing cartridge which has sufficient compressive strength and impact strength of a conventional radioactive liquid processing cartridge and is suitable for mass production. It is in.

[0009]

According to the present invention, there is provided a method for manufacturing a cartridge for treating a radioactive waste liquid, the method comprising:
As set forth in claim 1, a raw material slurry is prepared from raw raw cotton obtained by defibrating glass fibers, an inorganic binder and water, and the raw material slurry is poured into a mold, dewatered and formed into a predetermined shape, and the dewatered molded product is heated. It is characterized in that the glass fibers are partially fused by the treatment.

The method for manufacturing a cartridge for treating radioactive waste liquid according to claim 2 is a method for manufacturing a cartridge for treating radioactive waste liquid according to claim 1, wherein boric acid, an inorganic acid of silicic acid, It is characterized in that one or more selected from these salts are used.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a raw material cotton is prepared by fibrillating glass fibers, a raw material slurry is prepared by adding the raw material raw cotton and an inorganic binder to water, and the raw material slurry is poured into a mold. The dewatered molded product is heat-treated and the glass fiber is partially fused to obtain a radioactive waste liquid treatment cartridge.

As a method of pouring the raw material slurry of the present invention into a mold, the raw material wool, the inorganic binder and water are supplied to a single mixing tank at a constant rate and mixed in the upper layer to form the raw material slurry. At the same time, there is a method in which the raw material slurry is constantly supplied from a lower part of the mixing tank into a plurality of molds through a single service tank.

In another method, the raw cotton wool, the inorganic binder, and water are supplied to a mixing tank A to be mixed and mixed as the raw material slurry, and then the raw material slurry is supplied from the mixing tank A to a service tank. The raw material slurry is prepared by supplying the raw material cotton, the inorganic binder, and water to another mixing tank B, and then preparing the raw material slurry. There is a method of switching and using.

Further, as another method, the raw cotton wool, the inorganic binder and water are supplied to one spiral tube at a constant rate, and the raw material slurry is mixed at the upper end of the spiral tube while the lower end of the spiral tube is simultaneously fed. There is a method in which the raw material slurry is supplied into a plurality of molds at a constant rate, but the method for preparing the raw material slurry is not particularly limited.

As the inorganic binder of the present invention, one or more binders selected from boric acid, inorganic acids of silicic acid and salts thereof are preferably provided.

The glass fibers are fused and fixed to each other at the intersections by heat treatment. However, when a binder is not provided, the degree of fusion and the location of fusion are small, and therefore, Fixation is insufficient, glass fibers are relatively mobile, and high compressive strength cannot be obtained.
Further, since the glass fiber is fixed at a small number of places and the distance between the fixed parts is large, when an impact is applied, the glass fiber is broken, becomes dust, and easily scatters.

On the other hand, when a binder is provided, the glass fibers are bonded to each other at their intersections by the binder itself, and the binder acts as a flux to promote fusion of the glass fibers. As a result, the glass fibers are firmly fixed to each other and the number of fixing points is increased, so that the compressive strength and the impact strength are increased and the generation of dust is reduced.

The binder may be applied in a solution state or a powder state together with the glass fiber raw material to the raw material slurry, but is preferably applied in a solution state. For example, a glass fiber may be immersed in a solution such as an aqueous solution, or sprayed on the glass fiber. The application of the binder may be performed in a fiberizing step of the glass fiber.

The average fiber diameter of the glass fibers of the present invention may be 0.5 to 40 μm from the viewpoint of the raw material raw cotton production method. In particular, the thickness is preferably 10 to 20 μm in order to increase the productivity and the speed of soaking the waste liquid into the cartridge. When the average fiber diameter is less than 10 μm, the waste liquid permeation rate is reduced. On the other hand, when the average fiber diameter exceeds 20 μm, it is difficult to maintain the shape at the time of dehydration molding, which lowers productivity.

The average fiber length of the glass fiber of the present invention is 0.1.
5-5 mm, especially 1-2 mm, is preferred. The average fiber length is 0.
If it is less than 5 mm, the adhesion per fiber during heating and fusion is reduced, and powder dropping when dropped is increased. On the other hand, when the length is more than 5 mm, division due to cracks at the time of falling tends to occur.

The density of the glass fiber of the present invention is 240 to 2
It is preferable to adjust so as to be 60 kg / m ³ . If the density is less than 240 kg / m ³ , sufficient compressive strength cannot be obtained. On the other hand, when the density exceeds 260 kg / m ³ , the amount of radioactive waste liquid permeated decreases.

The heat fusion temperature and the heat fusion time of the glass fiber of the present invention are preferably 70 to 15 minutes at 670 to 730 ° C., but the productivity and the occurrence of melting of the outer surface during the heat fusion are reduced. To prevent, especially 40 ~ 2 at 690 ~ 710 ° C
0 minutes is preferred. If the heat fusing temperature is lower than 670 ° C. or the heating time is shorter than 15 minutes,
The glass fibers are not sufficiently fused, resulting in poor shape retention. If the heating temperature is higher than 730 ° C. or the heating time is longer than 70 minutes, the glass fiber melts to the surface or inside and shrinks, and the water retention becomes poor and the glass fiber is easily cracked.

During the heat treatment, the binder applied to the glass fibers is oxidized, melted and coated on the glass fibers, thereby providing an adhesive effect and a film forming effect.

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings.

First, the manufacturing process of the cartridge according to the present invention will be described with reference to FIGS.

FIG. 1 shows a defibration step, in which fibers are formed by a centrifugal method, collected in particular without using a binder, wound up into a roll, and have an average fiber diameter of 13 μm and a softening point of 650.
The glass fiber 11 of ° C. is conveyed to a feather mill (defibrating device) 13 by a belt conveyor 12. The defibrated material 14 defibrated to a fiber length of about 1 to 2 mm by the feather mill (defibrillation device) 13 is crushed by a degranulation device 15 to obtain raw cotton 16. At that time, the dust is sucked by the blower 17, separated by the cyclone device 18, collected by the dust collector 19, and exhausted.

FIG. 2 shows a wet molding process, in which the raw glass raw material cotton 16, boric acid 20 as an inorganic binder,
The fresh water 21 is supplied to one mixing tank 22 at a constant rate and the upper layer 22
a, while simultaneously forming the raw material slurry 23 from the lower layer portion 22 b of the mixing tank 22.
Through a single service tank 24 into the four dehydrators 25, 25, 25, 25.

The dewatering device 25 is provided with the raw material slurry 2.
Pump 25a for constantly supplying the slurry 3; a vat tank 25b for storing the slurry 23;
And a net 25d for separating water from the raw material slurry 23.

The raw material slurry 23 constantly supplied into the dehydrating device 25 is sucked and suctioned by a blower 26,
The cylindrical mold 25 having an inner diameter of 70 mm, an outer diameter of 90 mm, and a height of 90 mm.
It is wet molded into the cylindrical body 27 in c.

The water separated by the suction passes through a dewatering tank 28 and returns as return water 29 to the mixing tank 22.
Returned to The cylindrical body 27 is dried at 100 ° C.
The density is 250 kg / m ³ , the diameter is 70 mm, and the height is 70 mm.

FIG. 3 shows a heat-sealing process, and FIG. 4 is an overall view of a heat-sealing cylindrical type used for the process.

A 5 mmφ air hole 32 is provided in the cylindrical mold 25 c.
The upper and lower lids 32 and 33 each having five a are stacked in a three-tiered manner by heating and fusing cylindrical molds 34 each having a length of 7 rows and 7 rows, and are heated and fused in a heating and fusion furnace 30. The glass fiber cartridge 31 is prepared by heat-sealing at a fixing temperature of 700 ° C. and a heat-fusion time of 30 minutes.

The glass fiber cartridge of the present invention obtained by the above-mentioned manufacturing method was compared with the glass fiber cartridge of the present invention as a comparative example.
A glass fiber cartridge disclosed in -240 was made. In the latter, first, a glass fiber is formed into a sheet shape, and the sheet is rolled up to a predetermined diameter while being rolled, and is filled in a two-piece stainless steel mold, and the density of the glass fiber is 250 kg / m2. ^{So that} it becomes ³ , then
Heat fusing temperature 700 ° C, heat fusing time 30 minutes, fusing glass fiber, diameter 70mm, height 70mm
As a glass fiber cartridge. The performance of each of the obtained cartridges was tested.
The results are shown in Table 1 below.

[0034]

[Table 1]

Test Method I. Dust generation (g / piece) A pipe with a diameter of 80 mm x 3 m was set upright, and the weight change of the lowermost cartridge before and after the test when 20 cartridges were dropped simultaneously was measured.

Weight before test (g / piece)-Weight after test (g / piece)
= Dust generation (g / piece) II. Compressive strength A load of 10 kg was applied in the diameter direction and the axial direction of the cartridge, and the amount of change in the cartridge at that time was measured.

III. Drop strength A pipe with a diameter of 80 mm x 3 m was set upright, and the appearance of the lowermost cartridge when 20 cartridges were dropped simultaneously was inspected.

Appearance condition: No remarkable fluff, crack, chipping, etc.

According to the above-mentioned test, the examples have achieved the target values of the compressive strength and the drop strength, which are comparable to those of the comparative example of the prior art, and the comparative examples show that the productivity and the amount of dust generation reach the target values. However, the example satisfied the target value of 50 particles / h · person or more and the target value of the amount of generated dust of 0.8 g / piece or less.

[0040]

As described above, according to the present invention,
By using the wet molding technique, mass production becomes possible, that is, the number of products produced per unit time per unit person increases, and a radioactive waste liquid treatment cartridge that can reduce the manufacturing cost of the cartridge is obtained. In addition, since there is no distortion due to the conventional method of rolling up a filling sheet to a predetermined diameter while rolling and filling the sheet, a cartridge for radioactive waste liquid treatment that has a small powder drop-off / crack after molding and a high compression breaking strength is provided. can get.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a defibration process of a cartridge for treating a radioactive waste liquid of the present invention.

FIG. 2 is a manufacturing process diagram of a wet molding process of the radioactive waste liquid treatment cartridge of the present invention.

FIG. 3 is a manufacturing process diagram of a heating and fusing step of the cartridge for treating a radioactive waste liquid of the present invention.

FIG. 4 is an overall view of a cylindrical shape for heat fusion used in the heat fusion step of the cartridge for treating radioactive waste liquid of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Glass fiber 12 Belt conveyor 13 Feather mill (fibrillation apparatus) 14 Defibrated material 15 Dehulling apparatus 16 Raw material cotton 17 Blower 18 Cyclone apparatus 19 Dust collector 20 Boric acid 21 Fresh water 22 Mixing tank 22a Upper part 22b Lower part 23 Raw material slurry 24 Service tank 25 Dehydrator 25a Pump 25b Butt tank 25c Cylindrical type 25d Net 26 Blower 27 Cylindrical body 28 Dehydration tank 29 Return water 32 Top lid 32a Air hole 33 Lower lid 34 Heat welding cylindrical type

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinori Nakamura 415 Sakunodani, Yuki-shi, Ibaraki Pref. Inside the Yuki Plant of Inorganic Inorganic Company, Ltd. Inside the Yuki factory

Claims (2)

[Claims] 1. A raw material slurry is prepared from raw raw cotton obtained by defibrating glass fibers, an inorganic binder and water, and the raw material slurry is poured into a mold to be dehydrated and formed into a predetermined shape. A method for manufacturing a cartridge for treating a radioactive waste liquid, wherein a glass fiber is partially fused. 2. The radioactive waste liquid treatment cartridge according to claim 1, wherein one or two or more selected from boric acid, inorganic acids of silicic acid and salts thereof are used as the inorganic binder. Manufacturing method.