JPH02128198A - Device for disolving and treating spent nuclear fuel - Google Patents

Abstract

PURPOSE:To precisely take out insoluble hangovers while a maintenance frequency is lessened and facilitate maintenance work by providing a device for inclining a nuclear fuel charge cage at a specified position. CONSTITUTION:An elevator 6 is descended and the upper portion of a fuel charge cage 2 arranged in a soluble vessel 1 is grasped by a fuel charge hold rotation mechanism 5. the grasped cage 2 is hung up by the fuel charge cage elevator mechanism 6 to transport to a coating tube taking-out portion 10. The cage 2 hung up in the coating tube taking-out portion 10 is inclined by a fuel charge inversion mechanism 7. A cover 8 is rotated as the inclined cage 2 is, so that the cage 2 is horizontally moved up to the upward of a coating tube branch outlet 4. Next, the hold rotation mechanism 5 is descended, so that the cage 2 is inverted and the coating tube in the cage is released in the coating tube branch outlet 4. Thereby, insoluble hangovers are precisely taken out while a maintenance frequency is lessened and the facilitation of maintenance work can be contrived.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a nuclear fuel melting device used in the reprocessing process of spent nuclear fuel in a nuclear reactor, and in particular, to It relates to target extraction means or structure.

[Prior Art] Nuclear fuel used in nuclear power plants is generally referred to as spent nuclear fuel. Reprocessing is a process for reusing useful fissile material and nuclear raw material from this spent nuclear fuel.

For reprocessing in Japan, the Picolex method is adopted, and the reprocessing process consists of a wide variety of unit processes. In the initial process, the spent nuclear fuel rods are sheared into small pieces and then taken to a process where the nuclear fuel material inside is dissolved in nitric acid. This fuel material cladding is
Generally made of zirconium alloy or stainless steel, it does not dissolve in nitric acid and can be separated when the nuclear fuel material has finished melting, and is separated at this stage.

There are three types of spent nuclear fuel melting apparatus: a batch type, a continuous type, and a semi-batch type which is a compromise between the former. In general, the continuous type has higher efficiency than the single-batch type, but there is a problem in removing undissolved materials such as cladding tubes, etc. As a solution to this problem, the process described in Japanese Patent Application No. 55-177054 continuously processes the treated materials. A method has been proposed. However, since this device has a vertically elongated structure, it is disadvantageous in terms of earthquake resistance, and since the structure is complicated, there is a risk of clogging of the path by the cladding tube.

In order to improve earthquake resistance and avoid clogging, multiple charged fuel bags loaded with fuel pieces are immersed in the melting solution in a circular melting container held horizontally to melt the nuclear fuel material. Research and development is underway on a continuous melting treatment device that is characterized by removing the cladding from the fuel bag charge. As a publicly known material.

There is a continuous nuclear fuel melting and processing apparatus described in Japanese Patent Application Laid-open No. 169798/1983.

[Problems to be Solved by the Invention] In a continuous melting treatment apparatus in which a fuel basket as described above is arranged in an annular container, it is difficult to accurately remove undissolved residues such as cladding tubes from a fuel loading section after melting treatment. must be carried out. At this time, the inside of this melting treatment equipment is in a highly corrosive atmosphere, and therefore, periodic maintenance of drive parts and the like is essential.

Maintenance work for this purpose is dangerous and difficult as it involves work under high radioactivity. Therefore, there is a need for a simple structure that is easy to maintain and requires less frequent maintenance, and that has a small number of driving parts.

The present invention has a structure in which insoluble residues can be removed accurately, maintenance frequency is reduced, maintenance work is easy, and airtightness is easily maintained to prevent the spread of contamination when removing the coating material. The present invention aims to provide a continuous dissolution treatment apparatus having the following features.

[Means for Solving the Problems] The above problem is achieved by arranging a plurality of corrosion-resistant nuclear fuel loading baskets in a row in the circumferential direction in a corrosion-resistant annular container containing a dissolution treatment solution, and dissolving the lower part of the nuclear fuel loading basket. In a device that dissolves nuclear fuel by immersing it in a liquid, and after the melting is finished, insoluble residues such as nuclear fuel cladding tubes that remain in the charged nuclear fuel are taken out and newly loaded with nuclear fuel for melting processing. An annular lid rotatable in the circumferential direction of the annular container is provided, and the annular lid removably grips the upper part of the nuclear fuel loading basket, and the nuclear fuel loading basket is held between the annular container and the annular lid. This problem can be solved by providing a nuclear fuel loading part moving device having a moving function and a nuclear fuel loading basket tilting device having a function of tilting the nuclear fuel loading basket at a predetermined position.

[Operations] According to the present invention, a circumferentially movable annular lid is provided on the annular melting container so as to cover the melting container in an airtight manner, and a nuclear fuel loading basket is held inside the lid. A moving device is provided, and the moving device grips the nuclear fuel loading basket and moves it to the top of the lid, and then the cage is tilted by a mechanism to take out the undissolved residue in the cage. Therefore, it is easy to maintain airtightness of the entire device, the folding mechanism is simple, and the operation is accurate.

[Example] An embodiment of the present invention will be described below.

FIG. 1 shows a vertical cross section of a continuous melting and processing apparatus for spent nuclear fuel according to an embodiment.

A high-temperature, highly acidic dissolution treatment liquid 3 is contained in the annular dissolution container-1, and a plurality of fuel-charged batteries 2 are arranged in the circumferential direction, the lower part of which is immersed in the dissolution treatment liquid 3. are doing.

The fuel bag charge 2 is loaded with fuel sheared pieces, and only the fuel is dissolved in the dissolution treatment liquid 3, and the insoluble fuel cladding tube remains in the fuel load n2. .

The upper part of the dissolution container 1 is kept airtight by a cover 8. The fuel bag charge holding rotation mechanism 5 is suspended and connected to the fuel loading section elevator I+1!6, and the fuel bag charge holding rotation mechanism 6
is held by the cover 8 and the fuel bag charge retention rotation mechanism 5
is movably installed inside the cover 8.

Further, a fuel bag charge reversal device 7 is installed on the side surface of the cladding tube removal section 10. The cladding tube removal section 10 is covered with a cover 8, and the airtightness of the entire melting treatment apparatus is maintained.

The cladding tube port 4 is connected to a cladding tube extraction section 10 .

In order to take out the cladding tube in the fuel load n2, the fuel bag charge holding rotation mechanism 5 first grasps the fuel bag charge 2 and is suspended by the fuel charge lifting mechanism 6. By tilting the fuel bag charge 2 by the fuel bag charge reversal mechanism 7 and then rotating the cover 8 by the cover rotation drive mechanism 9,
The fuel load 1'12 is moved horizontally to the top of the cladding tube outlet 4. By moving the fuel bag charge holding rotation mechanism 5 downward, the fuel bag charge is reversed and the cladding tube is taken out to the cladding tube outlet. After taking out the cladding tube, the fuel bag charge is suspended to its original state and returned to the melting container 1.

The method for removing the fuel cladding tube will be explained in detail below. Second
Figure (a) shows the operation at the position where the fuel bag charging lifting device 6 grips the fuel bag charging 2. As shown in FIG.

The lifting device 6 descends, and the upper part of the fuel bag charge 2 placed in the melting container 1 is gripped by the fuel bag charge holding rotation mechanism 5 . FIG. 2(b) is a diagram showing a state in which the fuel loading n2 is pulled up to the cladding tube extraction section 10. The gripped fuel bag charge 2 is lifted up by the fuel charge lifting mechanism 6 and transported to the cladding tube removal section 10.

FIG. 3(a) shows a state in which the fuel bag charge 2 is tilted in the cladding tube removal section 10 to such an extent that the next moving operation is not hindered and the cladding tube in the fuel load n2 does not fall out.

The fuel bag charge 2 pulled up to the cladding tube removal section 10 is tilted as shown in FIG. 3(a) by the fuel loading charge inversion machine gI7.

FIG. 4 is a diagram showing the positional relationship between the cladding tube extraction section 10 and the cladding tube extraction port 4 in the cover 8, viewed from the outer circumferential side of the melting container 1. as it is,
By rotating the cover 8 as shown in FIGS. 4(a) and 4(b), it is horizontally moved to above the cladding tube outlet 4.

FIG. 3(b) and FIG. 4(c) are for extracting the cladding tube inside the fuel bag charge 2 to the cladding tube extraction port 4.

It is a diagram showing a mechanism for reversing the fuel loading n2 by lowering the fuel bag charge holding rotating machine uI5. fuel loading n2
By reversing the cage, the cladding tube in the cage is discharged into the cladding tube extraction port 4. Fuel loading I' completes discharge of cladding tube! ! 2 is returned to the state shown in FIG. 4(b) and FIG. 3(a) by raising the fuel bag charge retention rotation mechanism 5, and then moved to the position shown in FIG. Moving on to the operation for loading the tube.

FIG. 5 shows a mechanism for gripping the fuel load n2 by the fuel bag charge retention rotation mechanism 5.

The fuel bag charge 2 is coupled to the basket holding rotation mechanism 5 by inserting the grip claw 13 of the fuel bag charge retention rotation mechanism 5 into the grip hole 14 provided in the fuel bag charge 2. The gripping claw 13 and the gripping hole 14 have a rotatable structure so that the cladding tube inside the fuel loaded lv1!2 can be discharged while gripping the charged fuel bag 2. The shape of the gripping claw 13 is shown in Figs. 5(b), (c), (d), and (e) in addition to Fig. 5(,).
, (f), Fig. 6 (1), (2), (3), etc. are possible.

FIG. 7 shows the fuel bag charge 2 and the gripping hole 14. For the gripping hole 14 in FIG. 7(b), FIG.
It is effective to combine the gripping claws 13 of any one of b), (c), and (d), and for the gripping hole 14 of FIG. , (e) and (f) are effective in combination. Also, Figure 7(a)
Good results can also be obtained by providing gripping claws 13 on the fuel bag charge 2 as shown in FIG. FIG. 6 shows that the gripping claw 13 and the gripping hole 14 are
When the fuel bag charge 2 is reversed, the fuel bag charge 2 and the fuel bag charge maintenance rotation mechanism 5 are connected to each other by fitting like a key and a keyhole, thereby preventing the fuel bag charge 2 from falling. This shows a structure that allows for

[Effects of the Invention] According to the present invention, in a continuous melting device used in a spent fuel reprocessing process, the device is a simple device for removing residual materials such as cladding tubes after melting from the melting device. The drive mechanism provides a structure with which the removal operation can be carried out precisely, the entire device is compact and the space for the residue removal operation is small. The reliability of the device is high and the possibility of failure is low, so maintenance of the device is easy and the frequency of maintenance can be reduced.

Further, it becomes possible to take out the remaining materials in an airtight environment, and the spread of contamination can be prevented to that extent.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the structure of a continuous melting treatment apparatus according to an embodiment of the present invention, and FIGS. 2, 3, and 4 are partial cross-sectional views for explaining the cladding tube removal operation by the apparatus of FIG. 1. , Figure 5,
FIG. 6 is a diagram showing the structure of an example of a gripping part and a gripping claw for charging the fuel bag, and FIG. 7 is a perspective view showing the structure of an example of charging the fuel bag. DESCRIPTION OF SYMBOLS 1... Melting container, 2... Fuel bag charging, 3... Dissolving treatment liquid, 4... Cladding tube outlet, 5... Fuel loaded oil holding rotation mechanism, 6... Fuel bag charging Lifting mechanism, 7... Fuel bag charge reversal mechanism, 8... Cover, 9... Cover rotation mechanism. 10... Cladding tube removal part, 11... Gripping part, 12...
-Rotating shaft portion, 13...gripping claw, 14...gripping hole.

Claims (1)

[Claims] 1. A plurality of corrosion-resistant nuclear fuel loading baskets are arranged circumferentially in a corrosion-resistant annular container containing a dissolution treatment solution, and the lower part of the nuclear fuel loading basket is immersed in the dissolution treatment solution. In a device that melts nuclear fuel, removes insoluble residues such as nuclear fuel cladding tubes that remain in the nuclear fuel loading cage after melting, and newly loads nuclear fuel for melting processing, the circumference of this annular container is placed above the annular container. Nuclear fuel is provided with an annular lid rotatable in a direction, the annular lid removably grips the upper part of a nuclear fuel loading basket, and the nuclear fuel has the function of moving between the annular container and the annular lid while gripping the nuclear fuel loading basket. A spent nuclear fuel melting and processing device comprising a loading basket moving device and a nuclear fuel loading basket tilting device having a function of tilting the nuclear fuel loading basket at a predetermined position. 2. The spent nuclear fuel melting and processing device according to claim 1, wherein the nuclear fuel loading basket is rotatably coupled to the nuclear fuel loading basket moving device. 3. In the invention of claims 1 and 2, the joint portion of the nuclear fuel loading basket and the nuclear fuel loading basket moving device is composed of a gripping claw and a gripping hole, and when the gripping claw and the gripping hole are fitted, both A spent nuclear fuel melting and processing device characterized in that the components are bonded together so as not to be inadvertently detached. 4. In the invention of claims 1 and 2, the nuclear fuel loading cage tilting device includes means for moving the lower part of the nuclear fuel loading basket and holding it in a tilted state, and means for moving the nuclear fuel loading basket up and down. A spent nuclear fuel melting and processing device characterized by: