CA1220934A - Method for treating plutonium oxide and/or plutonium- uranium mixed oxide - Google Patents
Method for treating plutonium oxide and/or plutonium- uranium mixed oxideInfo
- Publication number
- CA1220934A CA1220934A CA000433123A CA433123A CA1220934A CA 1220934 A CA1220934 A CA 1220934A CA 000433123 A CA000433123 A CA 000433123A CA 433123 A CA433123 A CA 433123A CA 1220934 A CA1220934 A CA 1220934A
- Authority
- CA
- Canada
- Prior art keywords
- oxygen
- oxide
- metal oxide
- plutonium
- atom ratio
- 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
- C01G56/005—Oxides; Hydroxides
-
- 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
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
- G21C3/42—Selection of substances for use as reactor fuel
- G21C3/58—Solid reactor fuel Pellets made of fissile material
- G21C3/62—Ceramic fuel
- G21C3/623—Oxide fuels
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
- C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Ceramic Engineering (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
Abstract of the Disclosure To avoid an unduly heavy increase of the oxygen/metal atom ratio during storage of plutonium oxide and/or plutonium-uranium mixed oxide heated in a reducing atmosphere, this oxide is cooled-down to a low temperature and is kept at this temperature, at which the oxygen/metal atom ratio does not exceed the predetermined value during a predetermined storage period.
Description
:~Z0~34 Background o~ the Invention Field of the Invention The invention relates to a method for treating plutonium oxide and/or plutonium-uranium mixed oxide by heating in a reducing atmosphere for the purpose of adjusting the metal oxide to a predetermined value of the oxygen/metal atom ratio and subsequently cooling-down of the oxide in an atmosphere of reducing and/or inert gas.
Description of the Prior Art ` United States Patent No. 4,158,681, discloses such a method.
There, pellets of plutonium-uranium mixed oxide are heated in a gas mixture of nitrogen and hydrogen, i.e., of an inert and a reducing gas, in a reduction furnace. Subsequently, the pellets are sintered in a sintering furnace in a gas mixture of argon and hydrogen, which, for buffering the reduction potential, may have additions of traces of water vapor, so that the desired stoichiometric value of the oxygen/metal atom ratio is set in the pellets. After sintering, the pellets are cooled down in a water-cooled discharge tube to normal temperature ~room temperature).
According to the known method, an understoichiometric value of the oxygen/metal atom ratio can also be obtained in the plutonium-uranium mixed oxide. Such an understoichiometric value advantageously causes a reduction in the internal corrosion of the material of fuel-rod cladding tubes which are sealed gas-tight and in which the mixed oxide is present in the nuclear reactor, usually in the form of pellets.
It has been found that when plutonium-uranium mixed oxide treated in the known manner to produce an understoichiometric value is stored in a normal air atmosphere, the oxygen/metal atom ratio increases and approaches 12Z~34 the stoichiometric ~alue. Plutonium or plutonium-uranium mixed oxide pellets which were produced for stock must therefore be subjected again to a heat treatment in a reducing atmosphere beEore they are filled into fuel-rod cladding tubes for nuclear reactors, in order to again reach the predetermined understoichiometric value of the oxygen/metal atom ratio.
Summary of the Invention . . .
An object of the invention is to avoid such repeated heat treatment, especially of plutonium or plutonium/uranium mixed oxide which had been stored for a long period of time, without an unduly great increase of the oxygen/metal ratio during the period of storage.
With the foregoing and other objects in view, there is provided in accordance with the invention a method for treating a metal oxide selected from the group consisting of plutonium oxide and plutonium-uranium mixed oxide by heating the metal oxide in a reducing atmosphere with adjustment of the oxygen/metal atom ratio to a predetermined value and subsequently cooling-down the treated metal oxide having the predetermined value of the oxygen/metal atom ratio in an atmosphere selected from the group consisting of reducing gas and inert gas and thereafter storing the cooled-down treated metal oxide for a predetermined storage period, the improvement comprising preventing a substantial increase of the oxygen/metal a~om ratio of the metal oxide with concomitant increase in corrosive property of the metal oxide during the predetermined storage period by cooling-down the treated metal oxide having the predetermined value of the oxygen/metal atom ratio to a temperature below 20C and maintaining the treated metal oxide at this temperature, at which its oxygenlmetal atom ratio does not substantially exceed the predetermined value during the predetermined storage period.
~;~20934 Other fcatures which are considered as characteristic for the in-vention are set forth in the appended claims.
Although the invention is illustrated and described herein as em-bodied in a method for treating plutonium oxide and/or plutonium-uranium mixed oxide, 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 Drawings The invention, however, together with additional objects and ad-vantages thereof will be best understood from the following description when read in connection with the accompanying drawings, in which:
FIGURE 1 shows schematically a cooled storage cabinet for storing plutonium oxide and/or plutonium-uranium mixed oxide pellets during a pre-determined storage time.
FIGURES 2-4 show graphic presentations of the oxygen/metal, i.e.
O/M atom ratio of different plutonium-uranium mixed oxide pellets as a function of the storage time (t) in days.
Detailed Description of the Invention The method mentioned at the outset ~or treating plutonium oxide and/or plutonium-uranium mixed oxide is characterized, according to the invention, by the feature that the oxide is cooled down to such a temperature and is held at this temperature, at which its oxygen/metal atom ratio does not exceed a predetermined value during a predetermined storage time.
The invention starts from the insight, that the increase of the oxygen/metal atom ratio of stored oxide is related to the storage temperature ~L2Z093~
such that the increase proceeds more slowly with decreasing storage temperature.
Therefore, the choice of a sufficiently low storage temperature will prevent an undwly large increase of the oxygen/metal atom ratio during the storage period.
Advantageously, the oxide is cooled down to and maintained at a temperature at which the value of its oxygen/metal atom ratio is increased by no more than 0.01 during the storage period. This ensures that fuel rod cladding tubes which are sealed gas-tight and are filled with pellets of such stored oxide, corrode in a nuclear reactor to practically the same small extent as fuel-rod cladding tubes sealed gas-tight, which tubes were filled immediately after sintering with oxide pellets with the same under-stoichiometric initial oxygen/metal atom ratio.
Advantageously, the oxide can also be kept during the predetermined storage period in an oxygen-containing atmosphere, preferably air, since, as we found, the oxygen/metal atom ratio of the oxide does not increase appreciably also in an oxygen-containing or a water vapor-containing atmos-phere. The oxide can therefore be stored, for instance, in cooled storage cabinets without the need for special measures to keep the normal ambient atmosphere or ambient air away from these cooled storage cabinets.
The invention and its advantages will be explained in greater detail by embodiment examples, with reference tG the drawings.
In FIGURE 1, the cooled storage cabinet 1 is arranged in a glove box 2. This glove box 2 is provided with an air-supply inlet 3 and an exhaust air-connection 4, with which pump and filter devices,not shown, are associated.
A small desiccator 5 is installed in the cooled storage cabinet 1.
Raw pellets of pressed U02- and PU02-powder (blanks~ are first reduced, for lL2~0934 lnstance, in a reduction furnace shown in German Patent No. 26 ll 750, :in a gas mixture of inert nitrogen and ~ to 8 volume percent of hydrogen at a temperature of about 1000C. Then, these pellets are subjected to sintering in~a sintering furnace at 1700C, and for adjusting an understoichiometric starting oxygen/metal atom ratio (O/M) to a reduction anneal in argon which contains about 8% by volume hydrogen and traces of water vapor. Subsequently, the annealed pellets (sintered bodies) are cooled-down in the discharge tube of the sintering furnace in the same atmosphere to normal temperature or room temperature of about 20 to 25C.
These cooled-down pellets can then be stored in the desiccator 5 in the storage cabinet l according to FIGURE l. These pellets may also be stored in the open in a cooled storage cabinet l. The pellets stored in the cooled storage cabinet are kept at a temperature below the normal temp-erature (room temperature) which is in the range of 20 to 25C. It is ad-vantageous to keep these pellets at a temperature lower than or equal to 10C and preferably at a temperature in the range of 10C to 4C, for instance at a temperature of 5C.
In FIGURES 2-4, time (t) is plotted as the abscissa in days and the oxygen/metal atom ratio (O/M~ as the ordinate. The ordinate values were determined from plutonium-uranium mixed oxide pellets with understoichio-metric initial oxygen/metal atom ratio. Some pellets were treated in a cooled storage cabinet according to FIGURE l. Other pellets were not treated according to the invention, but were held at room temperature.
FIGURE 4 relates to raw pellets (blanks) which were pressed from granulate. This grnnulate was obtained by pre-compacting and crushing UO2-PuO2~powder and milled returns of sintered UO2/PuO2.
` ` l;~Z0~3~
The solid curves in FIGURES 2 and 3 relate respectively to measurement results on pellets held at 5C, in a desiccator 5 in the cooled storage cabinet 1 according to FIGURE 1. The solid curve in FIGURE 4 relates to measurement results on pellets which were likewise kept at 5C in an open dish in the cooled storage cabinet 1.
The dash~dotted curves in FIGURES 2-4 relate to the re-spective pellets similar to the pellets with the solid curve and with the same understoichiometric starting oxygen/metal atom ratio.
These pellets were kept in the glove box 2 outside the cooled storage cabinet 1 according to FIGURE 1 at normal temperature or room temperature, i.e. at 20C to 25C, in a desiccator or open dish, i.e. were not treated in accordance with the invention.
The circular measurement points in FIGuREs 2-4 relate in each case to pellets which were kept in accordance with the invention at 5C. The triangular measurement points refer to the pellets whic~l were kept at room temperature and there~ore were not treated according to the invention.
Description of the Prior Art ` United States Patent No. 4,158,681, discloses such a method.
There, pellets of plutonium-uranium mixed oxide are heated in a gas mixture of nitrogen and hydrogen, i.e., of an inert and a reducing gas, in a reduction furnace. Subsequently, the pellets are sintered in a sintering furnace in a gas mixture of argon and hydrogen, which, for buffering the reduction potential, may have additions of traces of water vapor, so that the desired stoichiometric value of the oxygen/metal atom ratio is set in the pellets. After sintering, the pellets are cooled down in a water-cooled discharge tube to normal temperature ~room temperature).
According to the known method, an understoichiometric value of the oxygen/metal atom ratio can also be obtained in the plutonium-uranium mixed oxide. Such an understoichiometric value advantageously causes a reduction in the internal corrosion of the material of fuel-rod cladding tubes which are sealed gas-tight and in which the mixed oxide is present in the nuclear reactor, usually in the form of pellets.
It has been found that when plutonium-uranium mixed oxide treated in the known manner to produce an understoichiometric value is stored in a normal air atmosphere, the oxygen/metal atom ratio increases and approaches 12Z~34 the stoichiometric ~alue. Plutonium or plutonium-uranium mixed oxide pellets which were produced for stock must therefore be subjected again to a heat treatment in a reducing atmosphere beEore they are filled into fuel-rod cladding tubes for nuclear reactors, in order to again reach the predetermined understoichiometric value of the oxygen/metal atom ratio.
Summary of the Invention . . .
An object of the invention is to avoid such repeated heat treatment, especially of plutonium or plutonium/uranium mixed oxide which had been stored for a long period of time, without an unduly great increase of the oxygen/metal ratio during the period of storage.
With the foregoing and other objects in view, there is provided in accordance with the invention a method for treating a metal oxide selected from the group consisting of plutonium oxide and plutonium-uranium mixed oxide by heating the metal oxide in a reducing atmosphere with adjustment of the oxygen/metal atom ratio to a predetermined value and subsequently cooling-down the treated metal oxide having the predetermined value of the oxygen/metal atom ratio in an atmosphere selected from the group consisting of reducing gas and inert gas and thereafter storing the cooled-down treated metal oxide for a predetermined storage period, the improvement comprising preventing a substantial increase of the oxygen/metal a~om ratio of the metal oxide with concomitant increase in corrosive property of the metal oxide during the predetermined storage period by cooling-down the treated metal oxide having the predetermined value of the oxygen/metal atom ratio to a temperature below 20C and maintaining the treated metal oxide at this temperature, at which its oxygenlmetal atom ratio does not substantially exceed the predetermined value during the predetermined storage period.
~;~20934 Other fcatures which are considered as characteristic for the in-vention are set forth in the appended claims.
Although the invention is illustrated and described herein as em-bodied in a method for treating plutonium oxide and/or plutonium-uranium mixed oxide, 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 Drawings The invention, however, together with additional objects and ad-vantages thereof will be best understood from the following description when read in connection with the accompanying drawings, in which:
FIGURE 1 shows schematically a cooled storage cabinet for storing plutonium oxide and/or plutonium-uranium mixed oxide pellets during a pre-determined storage time.
FIGURES 2-4 show graphic presentations of the oxygen/metal, i.e.
O/M atom ratio of different plutonium-uranium mixed oxide pellets as a function of the storage time (t) in days.
Detailed Description of the Invention The method mentioned at the outset ~or treating plutonium oxide and/or plutonium-uranium mixed oxide is characterized, according to the invention, by the feature that the oxide is cooled down to such a temperature and is held at this temperature, at which its oxygen/metal atom ratio does not exceed a predetermined value during a predetermined storage time.
The invention starts from the insight, that the increase of the oxygen/metal atom ratio of stored oxide is related to the storage temperature ~L2Z093~
such that the increase proceeds more slowly with decreasing storage temperature.
Therefore, the choice of a sufficiently low storage temperature will prevent an undwly large increase of the oxygen/metal atom ratio during the storage period.
Advantageously, the oxide is cooled down to and maintained at a temperature at which the value of its oxygen/metal atom ratio is increased by no more than 0.01 during the storage period. This ensures that fuel rod cladding tubes which are sealed gas-tight and are filled with pellets of such stored oxide, corrode in a nuclear reactor to practically the same small extent as fuel-rod cladding tubes sealed gas-tight, which tubes were filled immediately after sintering with oxide pellets with the same under-stoichiometric initial oxygen/metal atom ratio.
Advantageously, the oxide can also be kept during the predetermined storage period in an oxygen-containing atmosphere, preferably air, since, as we found, the oxygen/metal atom ratio of the oxide does not increase appreciably also in an oxygen-containing or a water vapor-containing atmos-phere. The oxide can therefore be stored, for instance, in cooled storage cabinets without the need for special measures to keep the normal ambient atmosphere or ambient air away from these cooled storage cabinets.
The invention and its advantages will be explained in greater detail by embodiment examples, with reference tG the drawings.
In FIGURE 1, the cooled storage cabinet 1 is arranged in a glove box 2. This glove box 2 is provided with an air-supply inlet 3 and an exhaust air-connection 4, with which pump and filter devices,not shown, are associated.
A small desiccator 5 is installed in the cooled storage cabinet 1.
Raw pellets of pressed U02- and PU02-powder (blanks~ are first reduced, for lL2~0934 lnstance, in a reduction furnace shown in German Patent No. 26 ll 750, :in a gas mixture of inert nitrogen and ~ to 8 volume percent of hydrogen at a temperature of about 1000C. Then, these pellets are subjected to sintering in~a sintering furnace at 1700C, and for adjusting an understoichiometric starting oxygen/metal atom ratio (O/M) to a reduction anneal in argon which contains about 8% by volume hydrogen and traces of water vapor. Subsequently, the annealed pellets (sintered bodies) are cooled-down in the discharge tube of the sintering furnace in the same atmosphere to normal temperature or room temperature of about 20 to 25C.
These cooled-down pellets can then be stored in the desiccator 5 in the storage cabinet l according to FIGURE l. These pellets may also be stored in the open in a cooled storage cabinet l. The pellets stored in the cooled storage cabinet are kept at a temperature below the normal temp-erature (room temperature) which is in the range of 20 to 25C. It is ad-vantageous to keep these pellets at a temperature lower than or equal to 10C and preferably at a temperature in the range of 10C to 4C, for instance at a temperature of 5C.
In FIGURES 2-4, time (t) is plotted as the abscissa in days and the oxygen/metal atom ratio (O/M~ as the ordinate. The ordinate values were determined from plutonium-uranium mixed oxide pellets with understoichio-metric initial oxygen/metal atom ratio. Some pellets were treated in a cooled storage cabinet according to FIGURE l. Other pellets were not treated according to the invention, but were held at room temperature.
FIGURE 4 relates to raw pellets (blanks) which were pressed from granulate. This grnnulate was obtained by pre-compacting and crushing UO2-PuO2~powder and milled returns of sintered UO2/PuO2.
` ` l;~Z0~3~
The solid curves in FIGURES 2 and 3 relate respectively to measurement results on pellets held at 5C, in a desiccator 5 in the cooled storage cabinet 1 according to FIGURE 1. The solid curve in FIGURE 4 relates to measurement results on pellets which were likewise kept at 5C in an open dish in the cooled storage cabinet 1.
The dash~dotted curves in FIGURES 2-4 relate to the re-spective pellets similar to the pellets with the solid curve and with the same understoichiometric starting oxygen/metal atom ratio.
These pellets were kept in the glove box 2 outside the cooled storage cabinet 1 according to FIGURE 1 at normal temperature or room temperature, i.e. at 20C to 25C, in a desiccator or open dish, i.e. were not treated in accordance with the invention.
The circular measurement points in FIGuREs 2-4 relate in each case to pellets which were kept in accordance with the invention at 5C. The triangular measurement points refer to the pellets whic~l were kept at room temperature and there~ore were not treated according to the invention.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method for treating a metal oxide selected from the group consisting of plutonium oxide and plutonium-uranium mixed oxide by heating the metal oxide in a reducing atmosphere with adjustment of the oxygen/metal atom ratio to a predetermined value and subsequently cooling-down the treated metal oxide having the predetermined value of the oxygen/metal atom ratio in an atmosphere selected from the group consisting of reducing gas and inert gas, and thereafter storing the cooled-down treated metal oxide for a predetermined storage period, the improvement comprising preventing a substantial increase of the oxygen/metal atom ratio of the metal oxide with concomitant increase in corrosive property of the metal oxide during the predetermined storage period by cooling-down the treated metal oxide having the predetermined value of the oxygen/metal atom ratio to a temperature below 20°C and maintaining the treated metal oxide at this temperature, at which its oxygen/metal atom ratio does not substantially exceed the pre-determined value during the predetermined storage period.
2. Method according to claim 1, wherein the oxygen/metal atom ratio increases by no more than 0.01 during the predetermined storage period.
3. Method according to claim 1, wherein the treated metal oxide is kept in an oxygen containing atmosphere during the predetermined storage period.
4. Method according to claim 3, wherein the oxygen-containing atmosphere is air.
5. Method according to claim 1, wherein the treated metal oxide is kept at a temperature of 10°C and lower.
6. Method according to claim 5, wherein the treated metal oxide is kept at a temperature in the range of 10 to 4°C.
7. Method according to claim 5, wherein the treated metal oxide is kept at a temperature of 5°C.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DEP3227868.3 | 1982-07-26 | ||
DE3227868A DE3227868C2 (en) | 1982-07-26 | 1982-07-26 | Process for treating plutonium dioxide or plutonium-uranium mixed dioxide |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1220934A true CA1220934A (en) | 1987-04-28 |
Family
ID=6169356
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA000433123A Expired CA1220934A (en) | 1982-07-26 | 1983-07-25 | Method for treating plutonium oxide and/or plutonium- uranium mixed oxide |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0100026B1 (en) |
JP (1) | JPS5926929A (en) |
BE (1) | BE897320A (en) |
BR (1) | BR8303928A (en) |
CA (1) | CA1220934A (en) |
DE (2) | DE3227868C2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS62197119U (en) * | 1986-06-03 | 1987-12-15 | ||
ES2059653T3 (en) * | 1988-08-17 | 1994-11-16 | Gen Electric | PASSIVATION PROCEDURE OF URANIUM OXIDES TO CONTROL OXIDATION, AND URANIUM RESISTANT TO OXIDATION PRODUCED BY IT. |
US5069888A (en) * | 1989-07-31 | 1991-12-03 | General Electric Company | Process for passivating uranium oxides to control oxidation |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3872022A (en) * | 1970-08-10 | 1975-03-18 | Gen Electric | Sintering uranium oxide in the reaction products of hydrogen-carbon dioxide mixtures |
US4052330A (en) * | 1975-03-20 | 1977-10-04 | Gen Electric | Sintering uranium oxide using a preheating step |
DE2611750C3 (en) * | 1976-03-19 | 1979-08-09 | Alkem Gmbh, 6450 Hanau | Process for the production of nuclear fuel pellets |
GB1561161A (en) * | 1977-01-06 | 1980-02-13 | Atomic Energy Authority Uk | Processes for redusing the oxygen content of metal oxides |
-
1982
- 1982-07-26 DE DE3227868A patent/DE3227868C2/en not_active Expired
-
1983
- 1983-07-13 EP EP83106885A patent/EP0100026B1/en not_active Expired
- 1983-07-13 DE DE8383106885T patent/DE3373998D1/en not_active Expired
- 1983-07-18 JP JP58130726A patent/JPS5926929A/en active Granted
- 1983-07-19 BE BE0/211196A patent/BE897320A/en not_active IP Right Cessation
- 1983-07-22 BR BR8303928A patent/BR8303928A/en unknown
- 1983-07-25 CA CA000433123A patent/CA1220934A/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS5926929A (en) | 1984-02-13 |
EP0100026B1 (en) | 1987-10-07 |
DE3373998D1 (en) | 1987-11-12 |
JPH0580415B2 (en) | 1993-11-09 |
EP0100026A3 (en) | 1985-05-15 |
BE897320A (en) | 1983-11-14 |
BR8303928A (en) | 1984-02-28 |
DE3227868C2 (en) | 1984-07-26 |
DE3227868A1 (en) | 1984-02-02 |
EP0100026A2 (en) | 1984-02-08 |
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