JP3143866B2 - Crystallization / separation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cooling a nitric acid solution containing U and Pu in which spent nuclear fuel is dissolved, or a nitric acid solution containing U or Pu obtained from a co-decontamination and distribution step in a purex solvent extraction process. The present invention relates to a crystallization / separation device for precipitating a nitric acid compound crystal and separating the same.

[0002]

2. Description of the Related Art As a method of reprocessing spent nuclear fuel, there is a purex method mainly based on a solvent extraction method. At present, many good results have been obtained, and the solvent extraction method has been judged to be the best process. Is done. However, in this reprocessing method, since the entire process is performed only by the solvent extraction method, there is a point to be improved that the process becomes complicated and the number of apparatuses and equipment increases. In addition, since this reprocessing method uses an organic solvent, a solvent-related waste such as a solvent washing waste liquid and a waste solvent is generated, and a solvent for decomposing or mineralizing the solvent is required. There is a feature unique to the extraction method, and when a future reprocessing process is considered, improvement of the reprocessing process such as further simplification of processes and equipment and reduction of waste is desired.

[0003] In order to achieve this improvement, the present applicant has, in the conventional Purex method, an inner pipe that is rotationally driven by a drive unit inside a horizontal or inclined outer pipe,
A raw material supply port for supplying a nitric acid solution containing U and Pu and a plurality of refrigerant supply ports for supplying a cooling medium for cooling the nitric acid solution are provided at an upper portion of the outer tube, and a guide blade is provided on an outer peripheral surface of the inner tube. Filed a patent application for "Crystallizer" (Japanese Unexamined Patent Publication No.
No. 94). In this crystallization apparatus, the other end of the outer tube is closed by an outer tube cap, and a mother liquor extracting portion and a crystal extracting portion are formed on the upper and lower portions of the outer tube cap, respectively. A plurality of coolant supply ports are provided at predetermined intervals in the longitudinal direction at the top of the outer tube, and a coolant such as liquid nitrogen or dry ice is supplied from this supply port to cool the nitric acid solution in the outer tube. Has become.

In the crystallizer configured as described above, the nitric acid solution is cooled in a limited space between the outer tube and the inner tube to precipitate nitric acid compound crystals, thereby producing a slurry containing the crystals. The crystals contained in the slurry are continuously taken out from the crystal take-out section, and at the same time, the mother liquor of the slurry is taken out from the mother liquor take-out section. As a result, even if there is a limitation on the criticality management, the nitrate compound crystal can be obtained continuously and with high decontamination efficiency.

[0005]

However, in the above-mentioned conventional crystallizer, there is a problem that it takes a relatively long time for the nitrate compound crystals precipitated by cooling the nitric acid solution to settle. Further, in the above-mentioned conventional crystallizer, since the crystal take-out part is provided below the outer tube cap,
When taking out the nitrate compound crystal from the crystal take-out part, the mother liquor of the nitric acid solution is discharged together with the crystal. As a result, it is necessary to separate the crystal and the mother liquor using a mesh screen or the like smaller than the crystal grain size, and there has been a problem that the apparatus becomes large. An object of the present invention is to provide a crystallization / separation apparatus which can perform cooling crystallization and solid-liquid separation of a nitric acid solution in a short time and simultaneously, and can greatly reduce the process of cooling crystallization and solid-liquid separation. Is to do.

[0006]

The invention according to claim 1 is
As shown in FIG. 1, a nitric acid solution 17 containing U and Pu in which spent nuclear fuel is dissolved, or U or P obtained from a co-decontamination and distribution step in a purex solvent extraction process.
cooling the nitric acid solution 17 containing u
This is an improvement of a crystallization / separation apparatus for separating nitrate compound crystals 17b from a slurry containing nitrate compound crystals 17b by precipitating the same. Its characteristic configuration is that an upper cone 11a having a divergent opening 11e at the lower end and a divergent opening 11 at the upper end.
and a lower cone 11b in which the f is formed. The peripheral edges of the divergent openings 11e and 11f are joined to each other so that the nitric acid solution 17 can be stored therein, and the upper end of the upper cone 11a and the lower end of the lower cone 11b are vertically arranged. A rotating container 11 rotatable about a shaft 12 connected to and connected to the inner wall of the upper cone 11a and a lower wall of the lower cone 11b. The nitric acid solution 17 in the rotating container 11 is cooled to form a nitrate compound crystal 17b. A cooling liquid passage 11c through which the precipitated cooling liquid can pass, and a nitric acid compound crystal 17b formed on the outermost peripheral portion of the rotary container 11 and deposited on the inner surface of the outermost peripheral portion by centrifugal force generated by rotation of the rotary container 11
And a valve opening / closing mechanism 16 for opening and closing the crystal outlet 11d.

In the crystallization / separation apparatus according to the first aspect,
When the nitric acid solution 17 is supplied to the rotating container 11 while supplying the cooling liquid to the cooling liquid passage 11 c while the rotating container 11 is rotated about the shaft 12, the nitric acid solution 17 in the rotating container 11 is cooled by the cooling liquid. Nitrate compound crystal 1
7b is precipitated, and the nitric acid compound crystal 17b is
Due to the centrifugal force caused by the rotation of No. 1, it is deposited on the inner surface of the outermost peripheral portion of the rotating container 11. Next, after the rotation of the rotating container 11 is stopped and the mother liquor 17a of the nitric acid solution 17 in the rotating container 11 is discharged, the rotating container 11 is rotated again to open the crystal outlet 11d by the valve opening / closing mechanism 16, and the crystal 17b Is discharged out of the rotating container 11 from the crystal outlet 11d by centrifugal force.

The invention according to claim 2 is the invention according to claim 1, and further includes a valve opening / closing mechanism 16 as shown in FIG.
A valve body 29 pivotally connected at a substantially center to the rotary container 11 via a support pin 29d; and a valve seat portion 29a formed at the tip of the valve body 29 and capable of closely contacting the crystal outlet 11d of the rotary container 11.
A valve main body driving means 30 connected to the base end of the valve main body 29 and swinging the valve main body 29 around the support pin 29d to bring the valve seat portion 29a into close contact with the crystal outlet 11d or to separate from the crystal outlet 11d; The valve body 29 of the valve body 29
The valve seat 29a is urged in a direction in which the valve seat portion 29a comes into close contact with the crystal outlet 11d by centrifugal force generated when the valve body 29 rotates together with the rotary container 11 and is provided between the base end of the valve body and the support pin 29d. And a weight 29b. In the crystallization / separation apparatus according to the second aspect, when the crystallization outlet 11d is closed by the valve opening / closing mechanism 16 and the valve body 29 rotates together with the rotary container 11, the centrifugal force generated in the weight 29b causes the valve body 29 to rotate. The support pin 2
It is urged to rotate around 9d in a predetermined direction.
The predetermined direction is a direction in which the valve seat 29a is in close contact with the crystal outlet 11d.
Adhesion to 1d is improved.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIGS. 1 and 2,
The crystallization / separation device 10 includes a rotating container 11 formed by joining an upper cone 11a and a lower cone 11b to each other and rotatable about a shaft 12, and a cooling formed from the inner peripheral wall of the upper cone 11a to the inner peripheral wall of the lower cone 11b. It has a liquid passage 11c, a crystal outlet 11d formed at the outermost periphery of the rotary container 11, and a valve opening / closing mechanism 16 for opening and closing the crystal outlet 11d. The upper cone 11a has a divergent opening 11e at the lower end.
1b has a divergent opening 11f at the upper end, and the rotary container 11 is configured to be able to store the nitric acid solution 17 therein by welding the divergent openings 11e and 11f to each other by welding. The nitric acid solution 17 contains U and P obtained by reprocessing spent nuclear fuel.
nitric acid solution containing u, or U or P obtained from the co-decontamination and distribution step in the Purex solvent extraction process
This is a nitric acid solution containing u. The shaft 12 has an upper shaft 13 whose lower end is connected to the upper end of the upper cone 11a by welding, and a lower shaft 14 whose upper end is connected to the lower end of the lower cone 11b by welding. The upper shaft 13 and the lower shaft 14 They are connected to the upper cone 11a and the lower cone 11b, respectively, so that the axes are located on the same vertical line.

The rotating container 11 is accommodated in a case 19 whose lower end is attached to a base 18. Lower shaft 14
Is rotatably mounted on a base 18 via a bearing 21, and the upper shaft 13
It is rotatably mounted via. In addition, lower shaft 1
4 has a nitric acid solution 17 corresponding to the axis of the shaft 14.
Solution supply passage 14a for supplying
Is formed on the upper shaft 13.
And a mother liquor discharge passage 13a for discharging the mother liquor 17a of the nitric acid solution 17 from the rotary container 11 is formed. The upper end of the stock solution supply passage 14a reaches the upper surface of the lower shaft 14 and faces the inside of the rotary container 11, and the lower end reaches the lower surface of the lower shaft 14. The lower end of the mother liquor discharge passage 13a reaches the lower surface of the upper shaft 13 and faces the inside of the rotating container 11, and the upper end reaches the side surface of the upper shaft 13 a predetermined distance above the lower end of the upper shaft 13. Preferably, a screen is provided on the upper surface of the lower shaft to cover the upper end of the stock solution supply passage. The screen has a predetermined mesh that can pass through the nitric acid solution and cannot pass through the nitrate compound crystal.

The upper shaft 13 protrudes upward from the upper end of the case 19, and a driven pulley 23 is fitted to a protruding lower portion of the shaft 13. A motor 26 is mounted on the upper outer surface of the case 19 via a bracket 24, and a drive pulley 27 is fitted on an output shaft 26 a of the motor 26. The driving pulley 27 and the driven pulley 23 have a belt 2
8 is passed over. The rotating vessel 11 is provided in the coolant passage 11c.
A cooling liquid (not shown) for cooling the nitric acid solution 17 therein to precipitate the nitric acid compound crystals 17b is configured to pass therethrough. As the cooling liquid, a mixture of ethylene glycol and water is used. The upper end of the coolant passage 11c is
The coolant passage 11c is formed to extend vertically and communicates with the coolant supply passage 13b that supplies coolant to the coolant passage 11c. The lower end of the coolant passage 11c extends vertically to the lower shaft 14 and extends from the coolant passage 11c. It communicates with a coolant discharge passage 14b for discharging the coolant. The coolant supply passage 13 b is formed at a position deviated from the axis of the upper shaft 13 and in parallel with the axis, and the upper end reaches the upper surface of the upper shaft 13. The coolant discharge passage 14 b is formed at a position deviated from the axis of the lower shaft 14 in parallel with the axis, and the lower end thereof reaches the lower surface of the lower shaft 14.

The valve opening / closing mechanism 16 includes a valve main body 29 pivotally attached to the rotary container 11, a valve seat portion 29a formed at the tip of the valve main body 29 and capable of closely contacting a crystal outlet 11d of the rotary container 11,
Valve body driving means 30 connected to the base end of the valve body 29;
A weight 29b provided on the valve body 29. The valve body 29 is formed in a substantially crank shape, and a lower center portion thereof is swingably attached to an outer peripheral surface of the upper cone 11a via a bracket 29c and a support pin 29d. Valve seat 2
9a is configured so as to be able to adhere to the crystal outlet 11d, and is configured to prevent leakage of the nitric acid solution 17 in the rotating container 11 when the crystal outlet 9d is in close contact with the crystal outlet 11d. The valve body driving means 30 includes a piston 30a fixed to a lower portion of the upper shaft 13.
And the upper shaft 1 that accommodates the piston 30a and
3 and a cylinder 30b that slides vertically with respect to the piston 30a, and an upper surface of the piston 30a and the cylinder 30b.
And a cylinder spring 30c urged to push up the cylinder 30b.

An engaging member 30d is formed on the lower surface of the cylinder 30b and has an elongated hole 30e extending in the horizontal direction.
An engagement pin 29e fixed to the base end of the valve body 29 is slidably inserted into the elongated hole 30e. In addition, the upper shaft 13 has an oil passage 13 which coincides with the axis of the shaft 13.
c is formed, and the lower end of the oil passage 13c is
The inside of b communicates below the piston 30a, and the upper end reaches the upper surface of the upper shaft 13. The weight 29b is provided between the base end of the valve body 29 and the support pin 29d.
And the valve body 29 is urged in a direction in which the valve seat portion 29a comes into close contact with the crystal outlet 11d by centrifugal force generated when the valve body 29 rotates together with the rotary container 11. It is configured to It is preferable that a plurality of valve bodies 29 are provided symmetrically around the shaft 12 in consideration of the rotational balance of the rotary container 11.
1d, the engagement member 30d, and the like are formed in the same number as the valve body 29.

As shown in FIG. 3, a small-diameter pipe 13d for projecting the oil passage 13c upward is provided at the upper end of the upper shaft 13. A lower flange 13e is fitted on the upper end of the upper shaft 13, and this flange 13e
Has a first communication hole 13f communicating with the coolant supply passage 13b.
Is formed. A known first rotary joint 31 in which a cooling liquid supply port 31a communicating with the cooling liquid supply passage 13b and an oil supply / discharge port 31b communicating with the oil passage 13c are formed at the upper end of the lower flange 13e and the upper end of the small diameter pipe 13d. Is connected. A coolant pump (not shown) is connected to the coolant supply port 31a of the first rotary joint 31 via a coolant supply pipe 38, and an oil pump (not shown) is connected to the oil supply / discharge port 31b via an oil supply pipe 39. (Not shown). That is, the first rotary joint 31 can smoothly supply and discharge the coolant and the high-pressure oil without leaking into the coolant supply passage 13b and the oil passage 13c formed in the rotating upper shaft 13.

The first rotary joint 31 is attached to an upper flange 32 attached to the upper end of the lower flange 13e, a cylindrical member 34 fitted into the upper flange 32 via bearings 33, 33, and inserted into the upper end of the cylindrical member 34. A cylindrical member 35 having the cooling liquid supply port 31a and the oil supply / discharge port 31b formed therein.
And The first communication hole 13f is formed in the upper flange 32.
A second communication hole 32a communicating with the small diameter pipe 1 is formed.
A connection pipe 37 is connected to the upper end of 3d via a gasket packing 36. The cylindrical member 35 has a large-diameter hole 35 a communicating with the coolant supply port 31 a and an oil supply / discharge port 31.
A small hole 35b communicating with b is formed. Large diameter hole 3
5a and the small-diameter hole 35b are slidable vertically in the first direction.
And the second seal holders 41 and 42 are inserted respectively.

The first seal holder 41 is formed with a third communication hole 41a for communicating the second communication hole 32a of the upper flange 32 with the large-diameter hole 35a. The lower end of the holder 41 is made of carbon graphite. Formed cylindrical first
The seal member 51 is inserted. A first spring 61 is interposed between the cylindrical member 35 and the first seal holder 41, and the lower surface of the first seal member 51 is slidably pressed against the upper surface of the upper flange 32 by the elastic force of the spring 61. Is done. Second
A fourth communication hole 42a that connects the hole 37a of the connection pipe 37 and the small-diameter hole 35b is formed in the seal holder 42,
A cylindrical second seal member 52 made of carbon graphite is inserted into the lower end of the holder 42.
A second spring 62 is interposed between the cylindrical member 35 and the second seal holder 42, and the lower surface of the second seal member 52 is slidably pressed against the upper surface of the connecting pipe 37 by the elastic force of the spring 62. Is done. Reference numeral 71 in FIG. 3 is a first solenoid valve that switches between three ports and two positions, and reference numeral 72 is a cylinder 30b.
An oil return pipe that returns high-pressure oil inside the tank to an oil tank (not shown). When the first electromagnetic valve 71 is turned on, the high-pressure oil 40 is supplied to the cylinder 3 via the oil supply pipe 39 and the oil passage 13c.
0b, and when turned off, the high-pressure oil in the cylinder 30b is discharged through the oil passage 13c and the oil return pipe 72.

Further, as shown in FIG.
A large-diameter concave portion 14c communicating with the cooling liquid discharge passage 14b is formed at the lower end of the lower end, and a short pipe 14d for projecting the stock solution supply passage 14a downward is formed at the center of the concave portion 14c. At the lower end of the lower shaft 14 and the lower end of the short pipe 14d, a coolant discharge port 82 communicating with the coolant discharge passage 14b is provided.
a and a second rotary joint 82 formed with a stock solution supply port 82b communicating with the stock solution supply passage 14a. This second
The rotary joint 82 is configured substantially the same as the first rotary joint 31. 4, the same reference numerals as those in FIG. 3 indicate the same parts.
A coolant discharge pipe 83 is connected to the coolant discharge port 82a of the second rotary joint 82, and a stock solution supply pipe 84 is connected to the stock solution supply port 82b. That is, the second rotary joint 82 is connected to the coolant discharge passage 1 formed in the rotating lower shaft 14.
The cooling liquid can be smoothly discharged from the lower shaft 4b without leaking, and the nitric acid solution can be smoothly supplied to the raw liquid supply passage 14a formed in the rotating lower shaft 14 without leaking. Reference numeral 92 in FIG. 4 denotes a second electromagnetic valve that switches between three ports and two positions, and reference numeral 93 denotes a mother liquor tank (not shown) for storing a mother liquor of the nitric acid solution in the rotary container.
This is the mother liquor return pipe discharged to Second electromagnetic valve 92
Is turned on, the nitric acid solution is supplied into the rotary container via the raw liquid supply pipe 84 and the raw liquid supply passage 14a, and when turned off, the mother liquor of the nitric acid solution in the rotary container is discharged via the raw liquid supply passage 14a and the mother liquid return pipe 93. It has become so.

Returning to FIGS. 1 and 2, a cylindrical first partition wall 18 a having a diameter slightly smaller than the case 19 and a diameter slightly smaller than the outer diameter of the rotary container 11 are provided on the base 18 concentrically with the shaft 12. And the cylindrical second partition wall 18b is erected. A mother liquor discharge chamber 18c is formed between the case 19 and the first partition wall 18a, and a crystal discharge chamber 18d is formed between the first partition wall 18a and the second partition wall 18b. The base 18 has a mother liquor discharge port 18e facing the mother liquor discharge chamber 18c.
Is formed, and this outlet 18e is connected to the mother liquor tank. The base 18 has a large-diameter crystal discharge port 18f facing the crystal discharge chamber 18d. A mother liquor discharge pipe 1 is provided at the upper end of the mother liquor discharge passage 13a of the upper shaft 13.
The base end of 8 g extends in the horizontal direction and is connected.
The tip of 8 g faces the mother liquor discharge chamber 18c. In order to efficiently discharge the nitrate compound crystal 17b from the crystal discharge chamber 18d, the number of the crystal discharge ports 18f is increased, the crystal discharge ports 18f are formed in arc-shaped long holes, or the base 19 is formed.
It is preferable that the surface forming the bottom surface of the crystal discharge chamber 18d is formed as an inclined surface such that the nitrate compound crystal 17b flows down toward the crystal discharge port 18f.

The operation of the crystallization / separation apparatus thus configured will be described. First, the shaft 12 and the rotary container 11 are rotated by the motor 26, and a coolant (not shown) is supplied from the coolant supply port 31 a of the first rotary joint 31 to the coolant supply passage 1.
The liquid is supplied to the cooling liquid passage 11c of the rotary container 11 through 3b. Next, the second electromagnetic valve 92 is turned on to supply the nitric acid solution 17 from the stock solution supply port 82b of the second rotary joint 82 into the rotary container 11 via the stock solution supply passage 14a at a constant supply speed. At this time, since the first electromagnetic valve 71 is off, the high-pressure oil 40 (FIG. 2) is not supplied into the cylinder 30b, and the cylinder 30b is maintained at the highest position by the elastic force of the cylinder spring 30c. Valve seat 2 of body 29
9a comes into close contact with the crystal outlet 14d and closes the crystal outlet 14d. In addition, since the valve body 29 rotates together with the rotating container 11, the centrifugal force generated in the weight 29b urges the valve body 29 to rotate in the direction of the dashed arrow in FIG. As a result, the adhesion of the valve seat 29a to the crystal outlet 11d is improved. The nitric acid solution 17 sequentially supplied into the rotating container 11 is cooled by a cooling liquid to precipitate nitric acid compound crystals 17b.
Is deposited on the inner surface of the outermost peripheral portion of the rotating container 11 by the centrifugal force caused by the rotation of the rotating container 11. The mother liquor 17a of the nitric acid solution 17 in the rotating container 11 is supplied to the mother liquor outlet 1 via a mother liquor discharge passage 13a, a mother liquor discharge pipe 18g, and a mother liquor discharge chamber 18c.
8e.

After a lapse of a predetermined time, the rotation of the shaft 12 and the rotary container 11 by the motor 26 is stopped, and at the same time, the second electromagnetic valve 92 is turned off to turn off the nitric acid solution 17 in the rotary container 11.
Is discharged from the stock solution supply port 82b through the stock solution supply passage 14a. Next, the shaft 12 and the rotating container 1
1 is rotated again, the first electromagnetic valve 71 is turned on, and the high-pressure oil 40 is supplied into the cylinder 30b via the oil passage 13c. By supplying the high-pressure oil 40 into the cylinder 30b,
When the cylinder 30b descends against the elastic force of the cylinder spring 30c, the valve body 29 rotates in the direction in which the valve seat portion 29a separates from the crystal outlet 11d to reach the position shown in FIG. The nitrate compound crystal 17b is discharged from the outlet 11d into the crystal discharge chamber 18d by centrifugal force generated by the rotation of the rotary container 11, and further discharged from the crystal discharge port 18f. When the discharge of the crystal 17b from the rotating container 11 is completed, the first electromagnetic valve 71 is turned off, the crystal outlet 11d is closed by the valve seat 29a, and the second electromagnetic valve 92 is turned on to transfer the nitric acid solution 17 to the rotating container 11 And the above operation is repeated. In this manner, the cooling crystallization and the solid-liquid separation of the nitric acid solution 17 can be performed simultaneously and efficiently in a short time.

[0021]

As described above, according to the present invention, a rotating container capable of storing a nitric acid solution is formed by joining an upper cone and a lower cone to each other, and the rotating container is rotated about a shaft extending in a vertical direction. Configure as possible,
A cooling liquid passage was formed from the inner wall of the upper cone to the inner wall of the lower cone, and the crystal outlet formed at the outermost periphery of the rotating container was closed by a valve opening / closing mechanism so as to be openable. When the nitric acid solution is supplied to the rotating container while supplying the cooling liquid to the passage, the nitric acid solution is cooled by the cooling liquid to precipitate a nitrate compound crystal, and the crystal is centrifugally generated by the rotation of the rotating container to rotate the rotating container. It is deposited on the inner surface of the outermost periphery. Next, after stopping the rotating container and discharging the mother liquor of the nitric acid solution in the rotating container, the rotating container is rotated again, and the crystal outlet is opened by the valve opening / closing mechanism. Is discharged. Thus, the cooling crystallization and the solid-liquid separation of the nitric acid solution can be performed in a short time and simultaneously.

Further, in comparison with the conventional crystallization apparatus in which the size of the apparatus is increased, in the present invention, the cooling crystallization and the solid-liquid separation of the nitric acid solution can be simultaneously performed as described above. The separation process can be made much more compact. A substantially center of the valve body of the valve opening / closing mechanism is pivotally connected to the rotary container via a support pin, and a valve seat portion is provided at the tip of the valve body so as to be in close contact with the crystal outlet of the rotary container. Connect the valve body drive means to close the crystal outlet or detach from the crystal outlet,
If a weight is provided on the valve body, the crystal outlet is closed by the valve opening / closing mechanism, and when the valve body rotates together with the rotary container, the valve seat is brought into close contact with the crystal outlet due to centrifugal force generated in the weight. Since the main body is urged, the adhesion of the valve seat to the crystal outlet is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a crystallization / separation apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view corresponding to FIG. 1 and showing a state in which a crystal outlet is opened by a valve opening / closing mechanism of the apparatus.

FIG. 3 is an enlarged sectional view of a portion A in FIG. 1;

FIG. 4 is an enlarged sectional view of a portion B in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Crystallization / separation apparatus 11 Rotating container 11a Upper cone 11b Lower cone 11c Coolant passage 11d Crystal outlet 11e, 11f Spherical opening 12 Shaft 16 Valve opening / closing mechanism 17 Nitric acid solution 17b Nitric acid compound crystal 29 Valve body 29a Valve seat 29b Weight 29d Support Pin 30 Valve body driving means

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Kenji Nishimura, Naka-cho, Naka-machi, Naka-gun, Ibaraki Pref. 1002, 1414 Mitsubishi Materials Corporation Naka Energy Laboratory (56) References JP-A-64-85153 (JP, A) Japanese Utility Model Showa 64-48102 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G21C 19/46 G21F 9/06

Claims (2)

(57) [Claims] 1. Cooling a nitric acid solution (17) containing U and Pu in which spent nuclear fuel is dissolved, or a nitric acid solution (17) containing U or Pu obtained from a co-decontamination and distribution step in a purex solvent extraction process. In the crystallization / separation apparatus for separating the nitrate compound crystal (17b) from the slurry containing the nitrate compound crystal (17b) by depositing the nitrate compound crystal (17b), a divergent opening (11e) is formed at the lower end. Ta upper cone (11a)
And a lower cone (11b) with a divergent opening (11f) at the upper end
By joining the peripheral edges of the divergent openings (11e, 11f) to each other, the nitric acid solution (17) is formed therein so as to be able to store therein, and the upper end of the upper cone (11a) and the lower cone (11b) are formed. A rotatable container (11) rotatable around a shaft (12) extending vertically and connected to the lower end of the lower cone, and the lower cone from inside the peripheral wall of the upper cone (11a).
A cooling liquid passageway (11c) formed around the inside of the peripheral wall of (11b) and through which a cooling liquid for cooling the nitric acid solution (17) in the rotating container (11) to precipitate a nitrate compound crystal (17b) can pass; The rotating container (1) formed at the outermost peripheral portion of the rotating container (11)
A crystal outlet (11d) capable of discharging the nitrate compound crystal (17b) deposited on the inner surface of the outermost peripheral portion by centrifugal force due to the rotation of 1)
A valve opening / closing mechanism (1) for opening and closing the crystal outlet (11d).
6) A crystallization / separation device comprising: 2. A valve opening / closing mechanism (16) comprising: a valve body (29) pivotally connected at a substantially center to a rotary container (11) via a support pin (29d); and a tip of the valve body (29). A valve seat (29a) formed and capable of closely contacting a crystal outlet (11d) of the rotary container (11); and the valve body connected to a base end of the valve body (29) and centering on the support pin (29d). By swinging (29), the valve seat
(29a) in close contact with the crystal outlet (11d) or the crystal outlet (11
d) a valve body driving means (30) to be disengaged from the valve body (29), provided between the base end of the valve body (29) and the support pin (29d) of the valve body (29). A weight (29b) for urging the valve body (29) in a direction in which the valve seat portion (29a) comes into close contact with the crystal outlet (11d) due to centrifugal force generated when the rotary container (11) rotates with the rotating container (11). The crystallization / separation apparatus according to claim 1, comprising: