CA1153883A - Method for the production of nuclear fuel oxides - Google Patents
Method for the production of nuclear fuel oxidesInfo
- Publication number
- CA1153883A CA1153883A CA000367197A CA367197A CA1153883A CA 1153883 A CA1153883 A CA 1153883A CA 000367197 A CA000367197 A CA 000367197A CA 367197 A CA367197 A CA 367197A CA 1153883 A CA1153883 A CA 1153883A
- Authority
- CA
- Canada
- Prior art keywords
- furnace
- intermediate tank
- gases
- puc
- auc
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G56/00—Compounds of transuranic elements
- C01G56/004—Compounds of plutonium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G43/00—Compounds of uranium
- C01G43/01—Oxides; Hydroxides
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Gas Separation By Absorption (AREA)
- Treating Waste Gases (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Calcination and reduction of AUC and AU/PuC by heating in a furnace to cause decomposition and generation of ammonia, carbon dioxide and steam.
Passing the generated gases to an intermediate tank. Returning a portion of the gases directly from the tank to the furnace. Also passing gases from the tank to a gas scrubber in contact with water to form an ammonium carbonate solution.
Calcination and reduction of AUC and AU/PuC by heating in a furnace to cause decomposition and generation of ammonia, carbon dioxide and steam.
Passing the generated gases to an intermediate tank. Returning a portion of the gases directly from the tank to the furnace. Also passing gases from the tank to a gas scrubber in contact with water to form an ammonium carbonate solution.
Description
Background of the Invention Field of the Invention The present invention relates to a method for carrying out the cal-cination and reduction process in the manufacture of nuclear fuel oxides, where AUC or AU/PuC is decomposed in a steam/ammonia atmosphere under the action of heat.
Description of the Prior Art AUC (ammonium uranyl carbonate) and AU/PuC ~ammonium uranyl plutonyl carbonate) are known in the art and usually produced as a filter cake product.
According to the state of the art, see German Patent No. 1 592 478, AUC or AU/PuC filter cake is decomposed in a furnace, for instance a pusher furnace or a fluidized furnace, in a hydrogen-steam atmosphere. The hydrogen and the steam must be resupplied continuously to the process. The furnace exhaust gases are then conducted through a gas scrubber in which the steam is condensed and the remaining exhaust gases are purified. The excess hydrogen is dis-charged. It is seen from this brief description of the customary method that gaseous operating means and auxiliary substances must be supplied and discharged continuously to and from the process.
Summary of the Invention An object of the present invention is to provide a more efficient method of calcination and reduction of AUC and AU/PuC with reduced consumption of auxiliary substances as well as energy.
With the foregoing and other objects in view, there is provided in accordance with the invention a method for calcination and reduction of material selected from the group consisting of AUC and AU/PuC in the manufacture of nuclear fuel oxides, in which said materials are decomposed in a steam/ammonia atmosphere under the action of heat, which comprises heating said starting ' ' ~
1153~383 material in a furnace to effect its decomposition and generate ammonia, carbon dioxide and steam, passing the generated gases to an intermediate tank main-tained at a controlled temperature, returning a portion of the generated gases in the intermediate tank directly to said furnace in contact with said material, passing another portion of the generated gases in the intermediate tank to a gas scrubber in direct contact with water to form an ammonium carbonate solu-tion, and recovering ammonium carbonate solution.
Other features which are considered as characteristic for the inven-tion are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for the production of nuclear fuel oxides, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
Brief Description of the Drawing .
The invention, however, together with additional objects and advan-tages thereof will be best understood from the following description when read in connection with the accompanying drawing, in which is diagrammatically il-lustrated apparatus for carrying out of the invention involving a fluidized column furnace in which gases are generated by decomposition of AUC or AU/PuC, an intermediate tank receiving the generated gases and means for returning part of the gases to the furnace and an absorption gas scrubber for scrubbing the generated gases from the intermediate tank with water to form an ammonium carbon-ate solution. The heads of the furnace, intermediate tank and gas scrubber extend into a glove box and their bases extend into another glove box.
Detailed Description of the Invention The moist starting material, AUC or AU/PuC, is first heated in a fur-.
~, . . .
. .. .
11538~
nace. The gases formed thereby, ammonia, CO2 and steam are first fed into an intermediate tank kept at a controlled temperature and are returned from there in a closed loop at least partially to the furnace and also directed to a gas scrubber. Ammonium carbonate solution is formed by scrubbing the gases with water, and the solution returned to the process as washing water.
To further illustrate this method, reference is made to the flow diagram schematically shown in the drawing which will be explained in greater detail by way of an example. The AUC/PuC method in accordance with the inven-tion, employs a fluidized-column furnace 1, i.e. known fluidized bed in which AUC/PuC is maintained in the fluidized state in a tower. The furnace is oper-ated at approximately 600C. The AUC/PuC filter cake is charged-in in batches through line 14 into furnace 1. Nitrogen is first blown as the fluidizing gas from a gas supply tank, not shown, into the furnace 1 from below through line 17.
In the fluidized column, the ammonium-uranyl-plutonyl carbonate is decomposed and reduced by ammonia to U/PuO2-powder:
(NH4)4 C (U/Pu)o2 (CO3)3 ~ x n H2O > U/PuO2 + 3 CO2 + 3 NH3 + (3 + n) H2O + 1/2 N2 + 1/2 H2 This chemical reaction equation represents an overall equation for the reaction which proceeds in partial steps. In order to ensure substantial-ly quantitative reduction to U/PuO2, an excess of ammonia or hydrogen should be present in the furnace atmosphere. After this reaction has first been - initiated, the gases produced in the decomposition, ammonia, carbon dioxide, steam, hydrogen and nitrogen are conducted through a heat-insulated line 15 to an intermediate tank 2. To the latter is connected via the line 27 an absorp-tion gas scrubber 3. Excess gas quantities are discharged from gas scrubber 3 through line 41. For the scrubbing process, the gas mixture introduced via the line 27 is conducted to a nozzle box 33 and is mixed with water from the tank 3 which is supplied via the ]ine 36 by means of the pump 34. The mixture of gases and water from nozzle box 33 is fed into the tank 3 through line 35. By the gas absorption taking place there, an underpressure, that is, a reduced pressure, is produced which is communicated to the entire system. Since the large installation parts furnace 1, tank 2 and gas scrubber 3, preferably in the form of vertical towers, have their heads and bases extending into respec-tively glove boxes 31 and 32 it is unlikely that the reduced pressure in the glove boxes will be disturbed in the event of a leak in the apparatus.
After the starting phase of the process, a large part of the exhaust gases coming from the furnace 1 is returned and introduced as fluidizing gas from the intermediate tank 2 via the line 25 and the pump 26 instead of the nitrogen from the line 17, into the fluidized furnace 1. The ammonia and hy-drogen contained in these exhaust gases lead to a complete reduction of the powder in the furnace 1. Through the energy already contained in the fluidizing gases, the energy consumption of the furnace which was originially heated to about 600C by means of the heating system 13, is lowe-.ed. By means of a tem-perature control 24 at the intermediate tank, ~he proc,~s proceeding in the fluidized furnace can be controlled so that the steam i_ either condensed or returned to the furnace with the other gases as fluidizing g~s. This is of particular importance for the desired powder quality. Undesired li4uid and solids collecting in intermediate tank 2 may be discharged from the bottom of tank 2 through valve 23. At the end of the reduction phase for the entire powder, the furnace 1 is purged with nitrogen from the line 17 and subsequently, the powder is discharged via the valve 16 for further processing. The nitrogen used as the purging gas is drawn off again from the exhaust gas scrubber 3 through the line 41 and can be reused.
11538~3 Additional water may, in the course of time, be added through line 43 and valve 38 to the exhaust gas scrubber 3 to form a saturated ammonium carbonate solution. The latter is drawn off via the valve 39 and the line 42 and can be utilized in the conversion process of the AUC or AU/PuC method for washing the filter cake.
After completion of treatment of AU/PuC in furnace l, the product U/PuO2 powder is discharged through the valve 16, and then the latter is closed again. AU/PuC is again charged-in into furnace 1 via the line 14 and the process is again set in operation as described.
In conclusion, the advantages of the new method are listed once more in brief:
l. The use of specially fed-in hydrogen in the reduction from AUC
or AU/PuC is eliminated.
Description of the Prior Art AUC (ammonium uranyl carbonate) and AU/PuC ~ammonium uranyl plutonyl carbonate) are known in the art and usually produced as a filter cake product.
According to the state of the art, see German Patent No. 1 592 478, AUC or AU/PuC filter cake is decomposed in a furnace, for instance a pusher furnace or a fluidized furnace, in a hydrogen-steam atmosphere. The hydrogen and the steam must be resupplied continuously to the process. The furnace exhaust gases are then conducted through a gas scrubber in which the steam is condensed and the remaining exhaust gases are purified. The excess hydrogen is dis-charged. It is seen from this brief description of the customary method that gaseous operating means and auxiliary substances must be supplied and discharged continuously to and from the process.
Summary of the Invention An object of the present invention is to provide a more efficient method of calcination and reduction of AUC and AU/PuC with reduced consumption of auxiliary substances as well as energy.
With the foregoing and other objects in view, there is provided in accordance with the invention a method for calcination and reduction of material selected from the group consisting of AUC and AU/PuC in the manufacture of nuclear fuel oxides, in which said materials are decomposed in a steam/ammonia atmosphere under the action of heat, which comprises heating said starting ' ' ~
1153~383 material in a furnace to effect its decomposition and generate ammonia, carbon dioxide and steam, passing the generated gases to an intermediate tank main-tained at a controlled temperature, returning a portion of the generated gases in the intermediate tank directly to said furnace in contact with said material, passing another portion of the generated gases in the intermediate tank to a gas scrubber in direct contact with water to form an ammonium carbonate solu-tion, and recovering ammonium carbonate solution.
Other features which are considered as characteristic for the inven-tion are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for the production of nuclear fuel oxides, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
Brief Description of the Drawing .
The invention, however, together with additional objects and advan-tages thereof will be best understood from the following description when read in connection with the accompanying drawing, in which is diagrammatically il-lustrated apparatus for carrying out of the invention involving a fluidized column furnace in which gases are generated by decomposition of AUC or AU/PuC, an intermediate tank receiving the generated gases and means for returning part of the gases to the furnace and an absorption gas scrubber for scrubbing the generated gases from the intermediate tank with water to form an ammonium carbon-ate solution. The heads of the furnace, intermediate tank and gas scrubber extend into a glove box and their bases extend into another glove box.
Detailed Description of the Invention The moist starting material, AUC or AU/PuC, is first heated in a fur-.
~, . . .
. .. .
11538~
nace. The gases formed thereby, ammonia, CO2 and steam are first fed into an intermediate tank kept at a controlled temperature and are returned from there in a closed loop at least partially to the furnace and also directed to a gas scrubber. Ammonium carbonate solution is formed by scrubbing the gases with water, and the solution returned to the process as washing water.
To further illustrate this method, reference is made to the flow diagram schematically shown in the drawing which will be explained in greater detail by way of an example. The AUC/PuC method in accordance with the inven-tion, employs a fluidized-column furnace 1, i.e. known fluidized bed in which AUC/PuC is maintained in the fluidized state in a tower. The furnace is oper-ated at approximately 600C. The AUC/PuC filter cake is charged-in in batches through line 14 into furnace 1. Nitrogen is first blown as the fluidizing gas from a gas supply tank, not shown, into the furnace 1 from below through line 17.
In the fluidized column, the ammonium-uranyl-plutonyl carbonate is decomposed and reduced by ammonia to U/PuO2-powder:
(NH4)4 C (U/Pu)o2 (CO3)3 ~ x n H2O > U/PuO2 + 3 CO2 + 3 NH3 + (3 + n) H2O + 1/2 N2 + 1/2 H2 This chemical reaction equation represents an overall equation for the reaction which proceeds in partial steps. In order to ensure substantial-ly quantitative reduction to U/PuO2, an excess of ammonia or hydrogen should be present in the furnace atmosphere. After this reaction has first been - initiated, the gases produced in the decomposition, ammonia, carbon dioxide, steam, hydrogen and nitrogen are conducted through a heat-insulated line 15 to an intermediate tank 2. To the latter is connected via the line 27 an absorp-tion gas scrubber 3. Excess gas quantities are discharged from gas scrubber 3 through line 41. For the scrubbing process, the gas mixture introduced via the line 27 is conducted to a nozzle box 33 and is mixed with water from the tank 3 which is supplied via the ]ine 36 by means of the pump 34. The mixture of gases and water from nozzle box 33 is fed into the tank 3 through line 35. By the gas absorption taking place there, an underpressure, that is, a reduced pressure, is produced which is communicated to the entire system. Since the large installation parts furnace 1, tank 2 and gas scrubber 3, preferably in the form of vertical towers, have their heads and bases extending into respec-tively glove boxes 31 and 32 it is unlikely that the reduced pressure in the glove boxes will be disturbed in the event of a leak in the apparatus.
After the starting phase of the process, a large part of the exhaust gases coming from the furnace 1 is returned and introduced as fluidizing gas from the intermediate tank 2 via the line 25 and the pump 26 instead of the nitrogen from the line 17, into the fluidized furnace 1. The ammonia and hy-drogen contained in these exhaust gases lead to a complete reduction of the powder in the furnace 1. Through the energy already contained in the fluidizing gases, the energy consumption of the furnace which was originially heated to about 600C by means of the heating system 13, is lowe-.ed. By means of a tem-perature control 24 at the intermediate tank, ~he proc,~s proceeding in the fluidized furnace can be controlled so that the steam i_ either condensed or returned to the furnace with the other gases as fluidizing g~s. This is of particular importance for the desired powder quality. Undesired li4uid and solids collecting in intermediate tank 2 may be discharged from the bottom of tank 2 through valve 23. At the end of the reduction phase for the entire powder, the furnace 1 is purged with nitrogen from the line 17 and subsequently, the powder is discharged via the valve 16 for further processing. The nitrogen used as the purging gas is drawn off again from the exhaust gas scrubber 3 through the line 41 and can be reused.
11538~3 Additional water may, in the course of time, be added through line 43 and valve 38 to the exhaust gas scrubber 3 to form a saturated ammonium carbonate solution. The latter is drawn off via the valve 39 and the line 42 and can be utilized in the conversion process of the AUC or AU/PuC method for washing the filter cake.
After completion of treatment of AU/PuC in furnace l, the product U/PuO2 powder is discharged through the valve 16, and then the latter is closed again. AU/PuC is again charged-in into furnace 1 via the line 14 and the process is again set in operation as described.
In conclusion, the advantages of the new method are listed once more in brief:
l. The use of specially fed-in hydrogen in the reduction from AUC
or AU/PuC is eliminated.
2. The steam need not be introduced from an external source into the system via steam generators.
3. The energy content of the furnace exhaust gases is returned to the process.
4. The capacity of the gas scrubbers for the furnace exhaust gases can be reduced, since the latter are returned to the process to a large extent prior to passage through the gas scrubber.
5. Reduced pressure is obtained in the entire system.
6. The costs for energy and auxiliary substances are lowered con-siderably as compared to the state of the art method.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Method for calcination and reduction of materials selected from the group consisting of AUC and AU/PuC in the manufacture of nuclear fuel oxides, in which said materials are decomposed in a steam/ammonia atmosphere under the action of heat, which comprises heating said starting material in a furnace to effect its decomposition and generate ammonia, carbon dioxide and steam, passing the generated gases to an intermediate tank maintained at a controlled temperature, returning a portion of the generated gases in the intermediate tank directly to said furnace in contact with said material, passing another portion of the generated gases in the intermediate tank to a gas scrubber in direct contact with water to form an ammonium carbonate solution, and recovering ammonium carbonate solution.
2. Method according to claim 1, wherein said material is AUC.
3. Method according to claim 1, wherein said material is AU/PuC.
4. Method according to claim 1, wherein said furnace is a fluidized column furnace in which a fluidized bed of said material is subjected to decomposition, and wherein said returned gases are introduced into said bed to additionally serve to maintain the bed in a fluidized state.
5. Method according to claim 1, wherein said furnace, said intermediate tank and said gas scrubber are in the form of connected vertical towers and a reduced pressure in the gas scrubber resulting from said gas absorption in water therein is transmitted to said connecting intermediate tank and furnace, and wherein said vertical towers have their heads extending into a glove box and their bases extending into another glove box.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792951451 DE2951451A1 (en) | 1979-12-20 | 1979-12-20 | METHOD FOR PRODUCING NUCLEAR FUEL OXIDS |
| DEP2951451.0 | 1979-12-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153883A true CA1153883A (en) | 1983-09-20 |
Family
ID=6089097
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000367197A Expired CA1153883A (en) | 1979-12-20 | 1980-12-19 | Method for the production of nuclear fuel oxides |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0031066A1 (en) |
| JP (1) | JPS5696732A (en) |
| BR (1) | BR8007801A (en) |
| CA (1) | CA1153883A (en) |
| DE (1) | DE2951451A1 (en) |
| ES (1) | ES497965A0 (en) |
| PT (1) | PT72213A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6415960U (en) * | 1987-07-13 | 1989-01-26 | ||
| JP2545313Y2 (en) * | 1991-11-08 | 1997-08-25 | 日新電機株式会社 | Instrument transformer |
| CN1042321C (en) * | 1996-03-12 | 1999-03-03 | 中国核动力研究设计院 | Method and equipment for preparing ceramics grade powder of uranium dioxide |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA926583A (en) * | 1969-07-18 | 1973-05-22 | Westinghouse Electric Corporation | Production of uranium dioxide |
-
1979
- 1979-12-20 DE DE19792951451 patent/DE2951451A1/en not_active Withdrawn
-
1980
- 1980-11-28 BR BR8007801A patent/BR8007801A/en unknown
- 1980-12-08 EP EP80107728A patent/EP0031066A1/en not_active Withdrawn
- 1980-12-15 JP JP17796080A patent/JPS5696732A/en active Pending
- 1980-12-17 PT PT7221380A patent/PT72213A/en unknown
- 1980-12-19 CA CA000367197A patent/CA1153883A/en not_active Expired
- 1980-12-19 ES ES497965A patent/ES497965A0/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ES8207489A1 (en) | 1982-09-16 |
| DE2951451A1 (en) | 1981-07-16 |
| EP0031066A1 (en) | 1981-07-01 |
| BR8007801A (en) | 1981-06-23 |
| JPS5696732A (en) | 1981-08-05 |
| PT72213A (en) | 1981-01-01 |
| ES497965A0 (en) | 1982-09-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |