CA2249347A1 - Method for preparing highly radioactive materials for transmutation and/or combustion - Google Patents
Method for preparing highly radioactive materials for transmutation and/or combustion Download PDFInfo
- Publication number
- CA2249347A1 CA2249347A1 CA002249347A CA2249347A CA2249347A1 CA 2249347 A1 CA2249347 A1 CA 2249347A1 CA 002249347 A CA002249347 A CA 002249347A CA 2249347 A CA2249347 A CA 2249347A CA 2249347 A1 CA2249347 A1 CA 2249347A1
- Authority
- CA
- Canada
- Prior art keywords
- impregnation
- pellets
- materials
- transmutation
- radioactive materials
- 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.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
- G21F9/06—Processing
- G21F9/14—Processing by incineration; by calcination, e.g. desiccation
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/28—Treating solids
- G21F9/30—Processing
- G21F9/32—Processing by incineration
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Environmental & Geological Engineering (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Medicines Containing Material From Animals Or Micro-Organisms (AREA)
- Saccharide Compounds (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention concerns a method of preparing highly radioactive materials for transmutation and/or burn-up by irradiation in a nuclear plant. The invention proposes that the materials are first converted into liquid form by melting or chemical dissolution and a porous carrier material which is essentially insoluble in the liquefied materials is impregnated with the liquefied materials and then heated in such a way that the materials are converted into the finally required chemical form and density.
Description
' CA 02249347 1998-09-16 METHOD FOR PREPARING HIGHLY RADIOACTIVE MATERIALS
- FOR TRANSMUTATION AND/OR COMBUSTION
The invention refers to a method of preparing highly radioactive materials for transmutation and/or combustion by irradiation in a nuclear plant.
The transmutation and combustion of radioactive materials is applied especially in the frame of the disposal of nuclear materials. As a result of the transmutation and combustion radioactive materials are obtained having a drastically shortened half-lifetime thereby loosing their radiological danger within tolerable time periods , or materials having a lower radiologically dangerous radiation intensity.
It would now be possible by applying processes analog to those for the production of nuclear fuel, to transform the materials to be submitted to transmutation or combustion into powders, to mix them with inactive powders, to compress them into pills (pellets, targets) and to enclose them in tubular containers which are then put into a nuclear plant in view of transmutation and combustion. However, this method entails the creation of highly radiotoxic dust which deposits on the walls of hot cells or glove boxes and con-stitutes an additional radiation charge for the persons working in this area. Moreover there exists a risk that the powders are incompletely mixed and that during the success-ive irradiation in the nuclear plant hot points appear and may oblige to stop prematurely the transmutation and combus-tion.
Object of the invention is therefore a method which does not produce at all or only insignificantly toxic dust and which insures a very uniform distribution of the highly radioactive materials such that hot points are avoided ' CA 02249347 1998-09-16 during irradiation.
This ob;ect is achieved according to the invention by a method as defined in claim 1. It is essentially character-ized in that a convenient porous support material is impreg-nated by the highly radioactive materials which have been converted into liquid form. In the case of a powdery or particle like support material the latter is preferably pressed into pellets. If on the contrary the support material is already in a pellet shape prior to impregnation it is preferable degas it prior to impregnation in order to facilitate a uniform distribution of the radioactive material in the support material.
In some applications it is important to improve the mechanical stability of the pellets in order to insure their integrity during the entire impregnation phase. This can be achieved by keeping the central core of the pellets free of highly radioactive materials, ensured by a convenient limi-tation of the impregnation time. By this means the mechan-ical stability of the pellets is conserved.
Furthermore it can be useful to exclude a portion of the pellet surface from impregnation in order to avoid the creation of thermal fission energy in the core of the pel-lets during irradiation, thus improving the mechanical stability. To this end either the pellets are immersed only partially into the impregnation liquid or the pellets are partly coated with an layer impermeable for the liquid prior to impregnation.
The invention will now be described in more detail by means of some preferred embodiments.
The porous support material may be used in powder, granulate particles or microspheres form of for example uranium oxide, plutonium oxide, thorium oxide, yttrium oxide, cerium oxide or mixtures therefrom, for example spinel and YAG (yttrium-aluminum-garnet). However, this list is not at all exhaustive and depends upon the type of material which should be submitted to transmutation or combustion.
Even carbides, and nitrides of the mentioned elements or other elements can be used. The materials to be submitted to transmutation and combustion may be different isotopes of plutonium, americium, neptunium, curium and other actinides as well as fission products, for example technetium. These materials are transformed into liquids either by high tem-perature fusion or by chemical dissolution in an appropriate solvent.
The support material must be sufficiently porous in order to allow impregnation by the liquid material. Moreover the support material should not be dissolved to a substan-tial extent by the liquid material during impregnation. The mechanical constitution of the support material depends on the required degree of impregnation. One can employ powders and granulates produced by precipitation or transformation processes, microspheres obt~ine~ in a so-called droplets-to-particle conversion method (SOL-GEL) or pellets obtained from powders, granulates or microspheres.
If the support material is during impregnation in power, granulate or microspheres form, then this material is given the desired shape after impregnation by applying mechanical pressure or vibration.
According one possible realisation pellets are pressed and burned from a powdery support material. Such pellets present a porosity of about 40% and can be impreg-nated without difficulties. In the simplest case they are immersed into a smelt or a solution of a highly radioactive material. To this end the pellets are placed in a defined position on a grip whereupon the latter is slowly lowered into the liquid. The impregnation rate depends on the dimen-sions of the pores, the viscosity and surface tension of the liquid, the moistening rate of the pellet material and the impregnation material.
If a very uniform distribution of the liquid in the pellet is required then the presence of gas bullets imprisoned in the pellet can be detrimental since non-im-pregnated zones will remain. This problem can solved by submitting the impregnation tank to a vacuum prior to the admission of the impregnation liquid whereby the gas bullets are eliminated.
In some applications it is desired to only affect the outer layer of the pellets by the impregnation. This can be achieved by an appropriate choice of the impregnation time thereby ensuring that the impregnation liquid only pe-netrates to a predetermined depth into the pellets. It is further possible to deposit on a portion of the pellet surface a protective coating which is impermeable for the liquid in order to avoid penetration through this surface portion and to maintain without impregnation a core region of the pellet which is not attainable by the liquid. The advantage of this is that the fission energy created during irradiation of the highly radioactive material in a nuclear plant causes the production of heat mainly at the pellet surface. This heat can be easily evacuated while the solid core of the pellet prevents the latter from collapsing.
After the impregnation the highly radioactive material which has been introduced into the pellet in liquid form can be converted by a heat treatment into a desired chemical form (e.g. oxide, nitride or carbide) and sintered.
In another embodiment the support material can consist of microspheres, as mentioned, obtained by the SOL-GEL method. Due to the high porosity (about 80~) such micro-spheres are particularly adapted to a high rate impreg-nation. Thus a cylindrical column can be filled with micro-spheres and a nitrate solution of the highly radioactive material is added thereto. The dimensions of the column are chosen in such a way that critical conditions cannot occur.
After the impregnation the rem~;~;ng nitrate solution of the radioactive material is pumped back to a supply tank. The part of this material remaining between the spheres in then converted into an oxide, nitride or a carbide. This conver-sion is realised under an appropriate atmosphere in a con-ventional furnace or by means of microwaves. Thereafter themicrospheres are compacted into the shape required for the irradiation in the nuclear plant.
The impregnation of microspheres and their compacta-tion later-on into pellets can be performed in a completely automatic manner such that the personnel is not submitted to an additional radiation charge. In addition this method does not deal with dust of highly toxic materials.
Instead of the impregnation of microspheres in a column the microspheres can equally be put into a basked and immersed into the liquid, or the microspheres can be moved or stirred while the liquid material is sprayed thereon.
The essential advantages of the method according to the invention are as follows:
1 - The process steps during which highly radioactive materials are processed, are limited to the liquification and impregnation steps.
- FOR TRANSMUTATION AND/OR COMBUSTION
The invention refers to a method of preparing highly radioactive materials for transmutation and/or combustion by irradiation in a nuclear plant.
The transmutation and combustion of radioactive materials is applied especially in the frame of the disposal of nuclear materials. As a result of the transmutation and combustion radioactive materials are obtained having a drastically shortened half-lifetime thereby loosing their radiological danger within tolerable time periods , or materials having a lower radiologically dangerous radiation intensity.
It would now be possible by applying processes analog to those for the production of nuclear fuel, to transform the materials to be submitted to transmutation or combustion into powders, to mix them with inactive powders, to compress them into pills (pellets, targets) and to enclose them in tubular containers which are then put into a nuclear plant in view of transmutation and combustion. However, this method entails the creation of highly radiotoxic dust which deposits on the walls of hot cells or glove boxes and con-stitutes an additional radiation charge for the persons working in this area. Moreover there exists a risk that the powders are incompletely mixed and that during the success-ive irradiation in the nuclear plant hot points appear and may oblige to stop prematurely the transmutation and combus-tion.
Object of the invention is therefore a method which does not produce at all or only insignificantly toxic dust and which insures a very uniform distribution of the highly radioactive materials such that hot points are avoided ' CA 02249347 1998-09-16 during irradiation.
This ob;ect is achieved according to the invention by a method as defined in claim 1. It is essentially character-ized in that a convenient porous support material is impreg-nated by the highly radioactive materials which have been converted into liquid form. In the case of a powdery or particle like support material the latter is preferably pressed into pellets. If on the contrary the support material is already in a pellet shape prior to impregnation it is preferable degas it prior to impregnation in order to facilitate a uniform distribution of the radioactive material in the support material.
In some applications it is important to improve the mechanical stability of the pellets in order to insure their integrity during the entire impregnation phase. This can be achieved by keeping the central core of the pellets free of highly radioactive materials, ensured by a convenient limi-tation of the impregnation time. By this means the mechan-ical stability of the pellets is conserved.
Furthermore it can be useful to exclude a portion of the pellet surface from impregnation in order to avoid the creation of thermal fission energy in the core of the pel-lets during irradiation, thus improving the mechanical stability. To this end either the pellets are immersed only partially into the impregnation liquid or the pellets are partly coated with an layer impermeable for the liquid prior to impregnation.
The invention will now be described in more detail by means of some preferred embodiments.
The porous support material may be used in powder, granulate particles or microspheres form of for example uranium oxide, plutonium oxide, thorium oxide, yttrium oxide, cerium oxide or mixtures therefrom, for example spinel and YAG (yttrium-aluminum-garnet). However, this list is not at all exhaustive and depends upon the type of material which should be submitted to transmutation or combustion.
Even carbides, and nitrides of the mentioned elements or other elements can be used. The materials to be submitted to transmutation and combustion may be different isotopes of plutonium, americium, neptunium, curium and other actinides as well as fission products, for example technetium. These materials are transformed into liquids either by high tem-perature fusion or by chemical dissolution in an appropriate solvent.
The support material must be sufficiently porous in order to allow impregnation by the liquid material. Moreover the support material should not be dissolved to a substan-tial extent by the liquid material during impregnation. The mechanical constitution of the support material depends on the required degree of impregnation. One can employ powders and granulates produced by precipitation or transformation processes, microspheres obt~ine~ in a so-called droplets-to-particle conversion method (SOL-GEL) or pellets obtained from powders, granulates or microspheres.
If the support material is during impregnation in power, granulate or microspheres form, then this material is given the desired shape after impregnation by applying mechanical pressure or vibration.
According one possible realisation pellets are pressed and burned from a powdery support material. Such pellets present a porosity of about 40% and can be impreg-nated without difficulties. In the simplest case they are immersed into a smelt or a solution of a highly radioactive material. To this end the pellets are placed in a defined position on a grip whereupon the latter is slowly lowered into the liquid. The impregnation rate depends on the dimen-sions of the pores, the viscosity and surface tension of the liquid, the moistening rate of the pellet material and the impregnation material.
If a very uniform distribution of the liquid in the pellet is required then the presence of gas bullets imprisoned in the pellet can be detrimental since non-im-pregnated zones will remain. This problem can solved by submitting the impregnation tank to a vacuum prior to the admission of the impregnation liquid whereby the gas bullets are eliminated.
In some applications it is desired to only affect the outer layer of the pellets by the impregnation. This can be achieved by an appropriate choice of the impregnation time thereby ensuring that the impregnation liquid only pe-netrates to a predetermined depth into the pellets. It is further possible to deposit on a portion of the pellet surface a protective coating which is impermeable for the liquid in order to avoid penetration through this surface portion and to maintain without impregnation a core region of the pellet which is not attainable by the liquid. The advantage of this is that the fission energy created during irradiation of the highly radioactive material in a nuclear plant causes the production of heat mainly at the pellet surface. This heat can be easily evacuated while the solid core of the pellet prevents the latter from collapsing.
After the impregnation the highly radioactive material which has been introduced into the pellet in liquid form can be converted by a heat treatment into a desired chemical form (e.g. oxide, nitride or carbide) and sintered.
In another embodiment the support material can consist of microspheres, as mentioned, obtained by the SOL-GEL method. Due to the high porosity (about 80~) such micro-spheres are particularly adapted to a high rate impreg-nation. Thus a cylindrical column can be filled with micro-spheres and a nitrate solution of the highly radioactive material is added thereto. The dimensions of the column are chosen in such a way that critical conditions cannot occur.
After the impregnation the rem~;~;ng nitrate solution of the radioactive material is pumped back to a supply tank. The part of this material remaining between the spheres in then converted into an oxide, nitride or a carbide. This conver-sion is realised under an appropriate atmosphere in a con-ventional furnace or by means of microwaves. Thereafter themicrospheres are compacted into the shape required for the irradiation in the nuclear plant.
The impregnation of microspheres and their compacta-tion later-on into pellets can be performed in a completely automatic manner such that the personnel is not submitted to an additional radiation charge. In addition this method does not deal with dust of highly toxic materials.
Instead of the impregnation of microspheres in a column the microspheres can equally be put into a basked and immersed into the liquid, or the microspheres can be moved or stirred while the liquid material is sprayed thereon.
The essential advantages of the method according to the invention are as follows:
1 - The process steps during which highly radioactive materials are processed, are limited to the liquification and impregnation steps.
2 - The method is perfectly adapted to a remotely con-trolled and largely automatic process.
3 - Toxic dust or radioactive waste are nearly not exist-ent.
4 - The radiation charge of the personnel is substan-tially reduced.
~, .
~, .
Claims (8)
1. A method for preparing highly radioactive materials for transmutation and/or combustion by irradiation in a nuclear plant, characterized in that the materials are liquefied by smelting or chemical dissolution, in that a porous support material which is practically insoluble by the liquified material is impregnated with the liquefied ,material and thereafter submitted to a heat treatment which converts the radioactive materials into the chemical form which is finally intended.
2. A method according to claim 1, characterized in that the support material consists of powder or particles and that it is brought into the desired shape after impregnation and heat treatment by means of a mechanical pressure or vibration.
3. A method according to claim 1, characterized in that the support material is initially in pellet form.
4. A method according to claim 3, characterized in that the pellets are additionally degassed prior to and during the impregnation phase.
5. A method according to claim 3, characterized in that the impregnation is limited in time in such a way that the impregnation liquid does not arrive at the core of the pellets.
6. A method according to claim 3, characterized in that the pellets are immersed only partly into the impregnation liquid.
7. A method according to claim 3, characterized in that the pellets are coated on a portion of their surface prior to impregnation with a layer which is impermeable to the impregnation liquid.
8. A method according to one of claims 1 to 7, characterized in that a final heat treatment is performed (sintering).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| LU88727A LU88727A1 (en) | 1996-03-19 | 1996-03-19 | Process for the preparation of highly radioactive substances for transmutation and / or combustion |
| LU88727 | 1996-03-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2249347A1 true CA2249347A1 (en) | 1997-09-25 |
Family
ID=19731583
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002249347A Abandoned CA2249347A1 (en) | 1996-03-19 | 1997-03-10 | Method for preparing highly radioactive materials for transmutation and/or combustion |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0888623B1 (en) |
| JP (1) | JP2000506976A (en) |
| AT (1) | ATE202235T1 (en) |
| CA (1) | CA2249347A1 (en) |
| DE (1) | DE59703801D1 (en) |
| DK (1) | DK0888623T3 (en) |
| ES (1) | ES2159115T3 (en) |
| GR (1) | GR3036593T3 (en) |
| LU (1) | LU88727A1 (en) |
| PT (1) | PT888623E (en) |
| WO (1) | WO1997035324A1 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2262854B1 (en) * | 1974-02-28 | 1976-12-10 | Commissariat Energie Atomique | |
| FR2280180A1 (en) * | 1974-07-22 | 1976-02-20 | Aerojet General Co | METHOD AND APPARATUS FOR TREATMENT OF RADIOACTIVE WASTE |
| US4609430A (en) * | 1984-03-07 | 1986-09-02 | Ngk Insulators, Ltd. | Liquid material drying apparatus |
| DE3583595D1 (en) * | 1984-12-25 | 1991-08-29 | Ebara Corp | METHOD AND DEVICE FOR TREATING WASTE MATERIAL. |
-
1996
- 1996-03-19 LU LU88727A patent/LU88727A1/en unknown
-
1997
- 1997-03-10 DE DE59703801T patent/DE59703801D1/en not_active Expired - Fee Related
- 1997-03-10 PT PT97908208T patent/PT888623E/en unknown
- 1997-03-10 JP JP9533110A patent/JP2000506976A/en not_active Ceased
- 1997-03-10 CA CA002249347A patent/CA2249347A1/en not_active Abandoned
- 1997-03-10 WO PCT/EP1997/001214 patent/WO1997035324A1/en active IP Right Grant
- 1997-03-10 AT AT97908208T patent/ATE202235T1/en not_active IP Right Cessation
- 1997-03-10 DK DK97908208T patent/DK0888623T3/en active
- 1997-03-10 EP EP97908208A patent/EP0888623B1/en not_active Expired - Lifetime
- 1997-03-10 ES ES97908208T patent/ES2159115T3/en not_active Expired - Lifetime
-
2001
- 2001-09-11 GR GR20010401450T patent/GR3036593T3/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1997035324A1 (en) | 1997-09-25 |
| GR3036593T3 (en) | 2001-12-31 |
| PT888623E (en) | 2001-10-31 |
| EP0888623B1 (en) | 2001-06-13 |
| JP2000506976A (en) | 2000-06-06 |
| ATE202235T1 (en) | 2001-06-15 |
| DE59703801D1 (en) | 2001-07-19 |
| DK0888623T3 (en) | 2001-09-03 |
| ES2159115T3 (en) | 2001-09-16 |
| LU88727A1 (en) | 1997-09-19 |
| EP0888623A1 (en) | 1999-01-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108028080A (en) | The manufacture method of full ceramics micropackaging nuclear fuel | |
| CA2211145A1 (en) | Stabilized depleted uranium material | |
| JPS5990100A (en) | Wrapping and higher density of granular substance | |
| Vance et al. | Synroc development—Past and present applications | |
| CA1107054A (en) | Process for the production of ceramic plutonium uranium nuclear fuel in the form of sintered pellets | |
| US3213031A (en) | Method of sealing refractory vessel containing radioactive wastes | |
| CN109641272B (en) | Method for producing a green body of a nuclear fuel body | |
| CA2249347A1 (en) | Method for preparing highly radioactive materials for transmutation and/or combustion | |
| Mukerjee et al. | Fabrication technologies for ThO2-based fuel | |
| Lahr | Fabrication, properties, and irradiation behavior of U/Pu particle fuel for light water reactors | |
| CA1155565A (en) | Production of tritium | |
| Ringwood et al. | Uniaxial hot-pressing in bellows containers | |
| US3838184A (en) | Process for producing fuel and breeder bodies for a nuclear reactor | |
| Nagarajan et al. | Sol-gel processes for nuclear fuel fabrication | |
| GB954821A (en) | Improvements in or relating to process for the preparation of carbide | |
| Larker | Hot isostatic pressing for the consolidation and containment of radioactive waste | |
| US5932930A (en) | Method for fabricating mixed oxide fuel | |
| Lackey et al. | Application of Sol-Gel Technology to Fixation of Nuclear Reactor Waste | |
| WO1998044834A1 (en) | Large size, thick-walled ceramic containers | |
| Mardon | Powder metallurgy techniques in nuclear technology | |
| Mishra et al. | Fabrication of Nuclear Fuel Elements | |
| EP0026573A1 (en) | A mixed oxide fuel pellet for use in a nuclear reactor and a method of manufacturing such a pellet | |
| Sullivan et al. | AECL's progress in DUPIC fuel development | |
| US4432892A (en) | Process for the safe intermediate and final storage of tritium | |
| Fernández et al. | Fuel/target concepts for transmutation of actinides |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |