JPS5932412B2 - conversion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conversion device used to obtain uranium oxide, plutonium oxide, or a mixed oxide thereof for producing nuclear reactor fuel.

When manufacturing nuclear reactor fuel, uranyl nitrate solution, plutonium nitrate solution, or a mixed solution of these is heated and denitrated using microwaves to form an oxide, which is then roasted and
Uranium dioxide for the production of nuclear reactor fuel by reduction,
The aim is to obtain plutonium dioxide or a mixed oxide of both.

Conventionally, the conversion equipment used in this process is a batch method, in which the raw material solution placed in a saucer is heated and denitrified by microwave irradiation in a batch method, and the formed oxides are scraped off from the saucer and temporarily stored. When it reaches a certain amount, it is transferred to a roasting/reducing tray, and then roasted/reduced again in batch mode.
The material is introduced into a reducing furnace and roasted in an air atmosphere, and then the atmosphere in the furnace is changed to a reducing atmosphere, and then reduction is performed.

However, in the conventional batch type converter mentioned above,
Since the product after microwave heating denitrification is left for a while, there is a risk that the product may change in quality and deteriorate in quality. The disadvantage is that the mechanism of the entire device becomes complicated because it is necessary to install a mechanism.

The present invention was made in order to eliminate the above-mentioned drawbacks of conventional devices, and an object of the present invention is to provide a conversion device that continuously performs denitration and roasting.

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

A denitrification and roasting furnace 1 for continuously performing denitrification and roasting is made of a stainless steel container in order to block microwaves and the atmosphere from the outside, and a saucer 2 containing a raw material solution 2a passes through the container.

The front half 1a of the furnace is a microwave irradiation section, and microwaves generated by microwave oscillators 3a, 3b, and 3c are introduced into the furnace through a waveguide 4.

Further, an exhaust pipe 5 is attached to the upper surface of the furnace for exhausting gas generated during the heating and denitrification process of the solution from inside the furnace.

A microwave stirrer 6 for stirring the microwave is provided in the furnace of the microwave irradiation section for uniform heating, and the microwave irradiation section is partitioned into two parts by a partition plate 7.

An illumination meter 8 is attached to this latter part, and is designed to stop the oscillation of the microwave oscillator 3C by detecting the luminescence phenomenon caused by overheating of oxides produced by denitration of the raw material solution.

Microwave absorbers 9a and 9 are provided at the entrance and exit of the microwave irradiation section, that is, at the boundary between the furnace inlet and the roasting section 1c, to prevent microwave leakage to the outside of the microwave irradiation section, respectively.
b is installed.

The rear half 1b of the furnace is a roasting section, and is maintained at a constant temperature by a heater 10.

Further, a movable heat shielding plate 11 is provided at the boundary 1c between the front half 1a and the rear half 1b for heat shielding.

The bottom plate 12 of the furnace protrudes by a predetermined length in front of the entrance and behind the exit of the furnace, and has a raw material supply stage 12a and a take-out stage 12.
A stock solution supply pipe 13 is provided above the supply stage 12a to supply the raw material solution to the saucer 2.

Further, a pusher is installed on the furnace inlet side as a mechanism for transferring the tray.

The operation of the apparatus of the present invention constructed as described above is as follows.

Uranyl nitrate, plutonium nitrate, or a mixed solution of both is passed through the raw material supply pipe 13 to the raw material supply stage 12a.
It is supplied to the upper saucer 2.

The saucer 2 containing the raw material solution is pushed by a pusher 14 by a stroke of one saucer, moves forward on the furnace bottom plate 12, and enters the denitrification and roasting furnace 1.

While moving forward in the front half 1a of the furnace, the solution 2a in the saucer 2 is heated by microwaves introduced into the furnace through the waveguide 4 from the microwave oscillators 3a to 3c.

At this time, the microwave in the furnace is stirred by the microwave stirrer 6 to uniformly heat the solution 2a.

Furthermore, microwaves leaking from the microwave irradiation section of the furnace are absorbed by the microwave absorbers 9a and 9b.

When the tray 2 advances further and reaches the final stage of the microwave irradiation section partitioned by the partition plate 7 and denitrification is completed, the product will be overheated. A total of 8 are captured, and the final stage microwave oscillator 3
Stop the oscillation of c.

The scum generated during the heating denitrification described above is exhausted to the outside of the furnace through the exhaust pipe 5.

When the saucer advances further and reaches the rear half 1b of the furnace, it is heated to a constant temperature by the heater 10, and roasting is performed.

After the roasting is completed, the tray further advances and is pushed out to the take-out stage 12b outside the furnace.

Here, the denitrified and roasted product is taken out from the receiving tray 2, and the empty receiving tray is transferred again to the raw material supply stage 12a by a transfer mechanism (not shown), and is used for transferring the next raw material solution.

As explained above, since the conversion device of the present invention continuously heats and dephosphorizes and roasts the raw material solution, the product after microwave heating and denitrification is not left unattended as in the case of a batch system. It is possible to obtain oxides of stable quality without any

Furthermore, since the microwave heating denitrification section and the roasting section are integrated and the tray transfer is performed continuously, the mechanism can be simplified compared to the batch method.

[Brief explanation of drawings]

The figure is a longitudinal section of a main part showing an embodiment of the conversion device of the present invention. 1... Denitrification roasting furnace, 1a... First half,
1b...Late part, 1c...Boundary part, 2
...Saucer, 2a...Raw material solution, 3a~
3c...Microwave oscillator, 4...Waveguide, 5...Exhaust pipe, 6...Microwave scraper, 7... Partition plate, 8...Luminance meter, 9a-9b...Microwave absorber, 10
... Heater, 11 ... Heat shielding plate, 1
2...Bottom plate, 12a...Raw material supply stage, 12b...Take out stage, 13...
...Stock solution supply pipe, 14...Pusher.

Claims (1)

[Claims] 1. A microwave oscillator is provided in the first half of the denitrification roasting furnace to serve as a microwave irradiation section, and a heater is provided in the second half, which is continuous with this first half through a boundary section, to serve as the roasting section. . A conversion device configured to sequentially transfer a saucer containing a raw material solution to the first half, the boundary, and the second half using a transfer mechanism. 2. The conversion device according to claim 1, wherein the transfer mechanism includes a pusher to push the trays arranged successively on the bottom plate into the denitrification and roasting furnace with a stroke of a certain length. 3. The method according to claim 1 or 2, characterized in that a raw solution supply pipe is provided on the raw material supply stage formed at the entrance of the denitrification roasting furnace, and the raw solution is supplied to the receiving tray. Conversion device. 4 Claim 1 characterized in that an absorber for preventing microwave leakage is provided on the inlet side and the outlet side of the front half part.
Conversion charge according to any one of paragraphs 3 to 3. 5 An illumination meter is attached to the final stage partitioned by the partition plate in the first half, and when the denitrification product emits light due to overheating,
The conversion device according to any one of claims 1 to 4, characterized in that the microwave oscillator in the final stage is stopped by detecting this.