CA1205927A - Nuclear fuel element, and method of producing same - Google Patents
Nuclear fuel element, and method of producing sameInfo
- Publication number
- CA1205927A CA1205927A CA000409841A CA409841A CA1205927A CA 1205927 A CA1205927 A CA 1205927A CA 000409841 A CA000409841 A CA 000409841A CA 409841 A CA409841 A CA 409841A CA 1205927 A CA1205927 A CA 1205927A
- Authority
- CA
- Canada
- Prior art keywords
- zirconium
- container
- fuel
- column
- zirconium metal
- 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
- 239000003758 nuclear fuel Substances 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 12
- 239000000446 fuel Substances 0.000 claims abstract description 90
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical group [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims abstract description 71
- 230000004888 barrier function Effects 0.000 claims abstract description 52
- 239000000463 material Substances 0.000 claims abstract description 28
- 230000001681 protective effect Effects 0.000 claims abstract description 25
- 238000005253 cladding Methods 0.000 claims description 42
- 229910001093 Zr alloy Inorganic materials 0.000 claims description 33
- 239000002131 composite material Substances 0.000 claims description 17
- 229910052726 zirconium Inorganic materials 0.000 claims description 14
- 239000008188 pellet Substances 0.000 claims description 9
- 229910045601 alloy Inorganic materials 0.000 claims description 8
- 239000000956 alloy Substances 0.000 claims description 8
- 230000000717 retained effect Effects 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 3
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 claims description 2
- 229910052776 Thorium Inorganic materials 0.000 claims description 2
- 229910052770 Uranium Inorganic materials 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims description 2
- DNYWZCXLKNTFFI-UHFFFAOYSA-N uranium Chemical compound [U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U] DNYWZCXLKNTFFI-UHFFFAOYSA-N 0.000 claims description 2
- 239000013078 crystal Substances 0.000 claims 6
- 229910052778 Plutonium Inorganic materials 0.000 claims 1
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 claims 1
- 239000001257 hydrogen Substances 0.000 abstract description 16
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 16
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 230000004992 fission Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000002826 coolant Substances 0.000 description 5
- 239000007789 gas Substances 0.000 description 4
- 238000009825 accumulation Methods 0.000 description 3
- 239000012141 concentrate Substances 0.000 description 3
- 230000002939 deleterious effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- 239000003039 volatile agent Substances 0.000 description 2
- -1 zirconium hydride compounds Chemical class 0.000 description 2
- NSMXQKNUPPXBRG-SECBINFHSA-N (R)-lisofylline Chemical compound O=C1N(CCCC[C@H](O)C)C(=O)N(C)C2=C1N(C)C=N2 NSMXQKNUPPXBRG-SECBINFHSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000004845 hydriding Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000004449 solid propellant Substances 0.000 description 1
- 229910052845 zircon Inorganic materials 0.000 description 1
- 229910000568 zirconium hydride Inorganic materials 0.000 description 1
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- G21C3/02—Fuel elements
- G21C3/04—Constructional details
- G21C3/16—Details of the construction within the casing
- G21C3/20—Details of the construction within the casing with coating on fuel or on inside of casing; with non-active interlayer between casing and active material with multiple casings or multiple active layers
-
- 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
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
- Structure Of Emergency Protection For Nuclear Reactors (AREA)
- Glass Compositions (AREA)
- Catalysts (AREA)
- Laminated Bodies (AREA)
Abstract
NUCLEAR FUEL ELEMENT, AND METHOD OF PRODUCING SAME
ABSTRACT OF THE DISCLOSURE
An improved nuclear fuel element for use in the core of a nuclear reactor. The improved fuel element has a protective barrier of zirconium metal bonded over the inside surface of the fuel container only in the section thereof adjacent to the charge of fissionable fuel material contained therein in order to localize hydrogen concentrations at the barrier layer. A method of producing the fuel element is disclosed.
ABSTRACT OF THE DISCLOSURE
An improved nuclear fuel element for use in the core of a nuclear reactor. The improved fuel element has a protective barrier of zirconium metal bonded over the inside surface of the fuel container only in the section thereof adjacent to the charge of fissionable fuel material contained therein in order to localize hydrogen concentrations at the barrier layer. A method of producing the fuel element is disclosed.
Description
5~
NUCLEAR FUEL ELEMENT, AND MæTHOD
: ~ P:RODUCING:SAME
BACKGROUND OF THE INV~NTION
This invention relates to an improvement in nuclear fuel elements for service in the core of nuclear fission reactors, and applies to such fuel elements having a composite container comprising a cladd.ing sheath provided with a protective barrier covering the inner surface thereo.
Nuclear fuel elements having a composite container and to which this invention specifically relates are disclosed in U.S. Patent No. 4,2Q0,492, issued April 29, 1980 to Armijo, assigned to the same assignee as this application.
Barrier layers or coatings bonded over the inside surface of nuclear fuel containers, commonly referred to as fuel cladding, are provided to protect the metal container from certain deleterious phenomena known as stress corrosion cracking and/or liquid metal embrittlement. The occurrence of such destructive activity results in failure of the unltO The cause of this phenomena is generally attributed to a combination of mechanical and chemical interactions occurring between the nuclear fuel material~ the metal container and the products of nucleax ~ission during reactor service. For instance~ neutrons and fission products from the fuel material irradiate and .interact with the metal of the container while physical forces are applied thereto by the thermal expansion of the body of fuel.
~.,~....
5~
The failure of nuclear fuel elements from such causes is described in some detail in U~S. Patent Nos. 4,057,466, issued November 8, 1977 to Thompson and 4,045,288, issued August 30, 1977 to Armijo, and elsewhere in the art.
Stress corrosion cracking and other destructive phenomena of zirconium alloy ~fuel containers, such as those constructed of the well known, commercially available Zircaloy compositions (see U.S. Patent No.
NUCLEAR FUEL ELEMENT, AND MæTHOD
: ~ P:RODUCING:SAME
BACKGROUND OF THE INV~NTION
This invention relates to an improvement in nuclear fuel elements for service in the core of nuclear fission reactors, and applies to such fuel elements having a composite container comprising a cladd.ing sheath provided with a protective barrier covering the inner surface thereo.
Nuclear fuel elements having a composite container and to which this invention specifically relates are disclosed in U.S. Patent No. 4,2Q0,492, issued April 29, 1980 to Armijo, assigned to the same assignee as this application.
Barrier layers or coatings bonded over the inside surface of nuclear fuel containers, commonly referred to as fuel cladding, are provided to protect the metal container from certain deleterious phenomena known as stress corrosion cracking and/or liquid metal embrittlement. The occurrence of such destructive activity results in failure of the unltO The cause of this phenomena is generally attributed to a combination of mechanical and chemical interactions occurring between the nuclear fuel material~ the metal container and the products of nucleax ~ission during reactor service. For instance~ neutrons and fission products from the fuel material irradiate and .interact with the metal of the container while physical forces are applied thereto by the thermal expansion of the body of fuel.
~.,~....
5~
The failure of nuclear fuel elements from such causes is described in some detail in U~S. Patent Nos. 4,057,466, issued November 8, 1977 to Thompson and 4,045,288, issued August 30, 1977 to Armijo, and elsewhere in the art.
Stress corrosion cracking and other destructive phenomena of zirconium alloy ~fuel containers, such as those constructed of the well known, commercially available Zircaloy compositions (see U.S. Patent No.
2,772,964, issued December 4, 1956 to ~homas et al), has been found to be effectively controlled or overcome by imposing a barrier of zirconium metal of at least moderate purity over the inside surface of the container. This use of zirconium metal barriers for fueI containers is set forth in the above noted patent 4,200,492.
lS Typical nuclear fuel elements for use in BWR and PWR power generating nuclear reactors have fissionable fuel material in only a portion of the container or cladding sheath, whereby there remains a vacant region therein devoid of any fuel. The provided vacant region comprises a plenum or empty space within the fuel container for the accumulation and retention of gaseous fission products, water vapor and any other volatiles.
In this common type of nuclear fuel element, a column of fissionable uel ma-terial, such as stacked 2S pellets, is deposited within the container extending upward from its base or lower end. The quantity of fuel in the column is designed to extend therefrom to a pre-determined height or point within the container and the uppermost or remaining portion of the fuel container extending beyond the fuel charge is without fuel as illustrated in U.S.
Patent Nos. 3,898,125l issued August 5, 1975 to Grossman et al and 3,969,186, issued July 13, 1976 to Thompson et al, for example. The fuel element and its container is thus divided into a fueI portion and a plenum region at the interface boundary therebetween.
~0S~27 This plenum region within the fuel container in -the area beyond the fuel charge th~erein, is provided with a biasing means such as a spring shown in the aforesaid patents to retain the fueI charge in position, such as affixed abutting one end of the container.
Typically the fueI container plenum region is filled with helium or a like inert gas as a non-r~active, effective heat transfer medium.
Accordingly, the fuel container in the area of the plenum region beyond the fueI charge is es~ntially isothermal, and remains at a substantially equal temperature with its surroundings comprising the coolant due to the effective heat transferring capacity and mobility of the gas medium therein. The fuel container in the portion retaining the fissionable fuel material therein, is maintained at a temperatur~ gradient during power generation with respect to its surroundings comprising the coolant. Specifically, there is a temperature gradi~nt extendin~ from within the fuel charge or column outward with markedly dropping temperatures through the fuel container wall to the surrounding coolant.
In the operation of a water cooled and/or moderated nuclear reactor system the release of hydrogen from the dissociation o~ water within the coolant medium is an inherent phenomenon. The hydrogen release is primarily attributable to the irradiating conditions and high temperature of the system, and the strong affinity between oxygen and the zirconium alloys which are commonly used to fabricate fuel containers or cladding.
It has been determined that within a reactor environment, or combination of conditions such as re~erred to abo~e, the behavior of free hydrogen and its effects upon zirconium alloy fueI containers vary with respect to different temperature conditions. For instance, it appears that the hydrogen seeks lower temperature levels upon permeating zirconium alloys whereby different - ~z~
temperature gradients or levels of the fueI con-tainer cause the hydrogen to migrate in different patterns therein.
Thus, upon penetrating the zirconium alloy o~
the fuel container in the portion retaining the fissionable fuel material, and therefore wherein there is a pronounced temperature gradient, hydrogen has been found to concentrate and remain at or near the cooler outer portion of the cladding wall and it is dispersed inward thexeIrom in diminishing amounts.
On the othèr hand, the hydrogen upon contacting and pen~trating the zirconium alloy of the ue~ containex in the portion thereof providing the plenum re~ion which is essentially isothermal, has been found to exhibit a propensity to migrate and distribute uniformly through the zirconium cladding wall of a fuel container. However, when a zirconium alloy fuel container is enhanced with a barrier of zirconium metal bonded over the cladding's inner surface, such as described in the hereinbefore cited patent , the lnwardly migrating hydrogen has been found to concentrate in the inner zirconium metal barrier provided f~r the protection of the container from the interiorly generated fission products and the fuel expansion.
Accordingly, in such barrier-provided uel containers it appears that the hydrogen migratin~ into and through the zirconium alloy container wall significantly accumulates and concentrates within the area of the container wall adjacent to its interface with the ~irconium metal barrier thereon.
Such a concentration of hydrogen atoms accumulated within a limited portion of the cladding wall, particularly adjacent to the interface of the bond of the baxrier layer to the container inner surface, is an undesirable effect of the composite fuel container structure, and under severe operating conditions could degrade the fueI performance.
5~7 SUMMAR~ OF TH~ VENTION
This invention comprises means for impro~ing composite constructed nuclear fuel containers comprising a barrier of zirconium metal overlying the inner surface of a zirconium alloy container such as described in U.S.
Patent 4,~00,492, and rendering fueI elements comprising the same more resistant to hydrogen accumulation in service.
The invention specifically comprises removing substantially all zirconium metal of the barrier layer from within the approxirnate portion of the fuel container comprising or de~ining the plenum region therein~ Thus, the protec~ive barrier of zirconium metal is retained covering only the inner surface portion of thè zircon:ium alloy fuel contain-er in the area approximately adjacent to or immediately embracing the fissionable fueI material contained therein.
OBJECTS OF THE INVE~TION
It is a primary object of this invention to provide an improved nuclear fuel element comprising a composite fuel container having a cladding sheath of zirconium alloy and a protective barrier therefor of zirconium metal.
It is a further object of the invention to provide a nuclear fuel eIement having a composite cladding sheath o~ zirconium alloy and zirconium metal barrier that resists the deLeterious effects o free hydrogen, and thereby extends the service life of the fuel element.
It is also an object of this invention to provide a nuclear fuel element comprising a composite container of zirconiurn alloy with a ~ixconium metal barrier therein that increases the as-fabricated gas plenum volume and resists subsequent plenum volume reduction attributable to the action of hydrogen forming zirconium hydride compounds therein.
It is still another object of this invention to provide a method of improving nuclear fuel eIements comprising a composite container of zirconium alloy with a zirconium metal barrier therein.
~2~5~ 7 It is an additional obj'ect of this invention to provide a method of rendering nuclear ~uel elements comprising a component container of a zirconium alloy with a protective barrier of zirconium metal therein more~resistant to free hydrogen and the debilitating effects thereof upon such'fuel containers and -~heir service life.
.. . . .
DESCRIPTION OF TH~ ~R~WING
/ The figure'of the'drawing comprises a partial 10 ~ sectional view of a nuclear fuel element assembly con-taining fissionable'fueI material constructed according to this invention.
DESCRIPTION OF THE INVENTION
This invention is particularly directed to nuclear fueI elements for power generating reactors having composite fuel containers comprising a cladding sheath of an alloy of zirconium such as a Zircaloy, with a protective covering barrier of substantially pure zirconium metal metallurgically bonded over its inside surface. Nuclear fueI elements of this con9truction and composition are disclosed in U.S.
Patent No. 4,200,492.
Specifically, the invention deals with composite fuel containers constructed of a cladding sheath from a zirconium alloy having at least about 5000 parts per million by weight of constituents therein other than zirconium, and a protective barrier member therefor of a zirconium metal having less than about 5000 parts per million by weight of impurities therein. Preferably the zirconium metal of the barrier component has less than about 4200 parts per million by weight of impurities.
Alloys of zirconium for the fueI cladding sheath commonly comprise commerci~lly available Zircaloy 2 or 4 which are well known in the nuclear industry.
This invention broadly comprises precluding any degrading or deleterious effects of free hydrogen upon composite nuclear fuel -containers of the afore-5~2'7 mentioned design. ~Iydrogen caused degradation orimpairment is overcome by removing the zirconium metal barrier material from within the zirconium alloy cladding sheath in the portion extending beyond the fueI charge whereby it is devoid of fissionable fueI material and comprises the plenum region.
The resultant unique fuel container of the no-veI nuclear fueI eIement of the invention resists hydriding in and about the plenum region which is free of any fuel material. Thus it avoids any discernable reduction in the vaid volume of the plenum area of the container provided for gas collection, attributable to the action of hydrogen reacting with zirconium metal to produce zirconium hydrides within the plenum region.
lS Removal of the zirconium metal of the barrier bonded on to the inside surface of the zirconium alloy cladding in the designated axea of the plenum region can be accomplished by any one of several techniques or measures, or combinations thereof. For instance, the zirconium metal can be eIiminated by mechanical means such as abrading, reaming or honing. The mechanical dimensions to remove the zirconium metal from the surface of the alloy over an area generally coextensive with the section of the fueI container designed as the plenum reyion of the unit. Apt chemical means can also be used to remove the zirconium metal by contacting the section thereof designated for elimination of the zirconium metal with a dissoluting reagent such as an acid reactive with the metal.
Referring to the drawing, the improved nuclear fuel element 10 of the invention is constructed as follows.
Fuel element 10 includes a clos~d, elongated composite container 12 comprising a cladding sheath 14 formed of an alloy of zirconium for the enclosure o-f the fission~
able fuel material 16 and its physical isolation from the coolant medium (not shown) which surrounds the element 10 ~20S~
in service. Generally the fueI eIement 10 is tubular in configuration as illustrated. Thb container 12 includes closing end plugs affixed in ends of the tubular cladding sheath 14 to seal the container.
Fissionable fuel material 16, such as an oxide or other compound of uranium, plu~:onium, or thorium, is commonly employed in the form of a plurality of small bodies such as the cylindrical shaped peIlets shown. The fuel material 16, or units thereof, is generally of the same or similar cross--sectional configuration as the fuel container or sheath, typicallycy~indrical. Moreover, the body of the fueI material charge is of slightly smaller cross-sectioned area or dimension than the inside open area of the composite fueI container 12 to provide a ~ree space 18 between khe fueI and container or the purpose of enabling a predetermined unrestric~ed la~eral thermal expansion of the fuel material 16. Thus, in a typical tubular fuel element, the cylindrical fueI charge provided therein would be of sufficiently smaller diameter with respect to the inside of the container to leave an annular space thereabout.
The fuel material 16, ~hown in pellet form is stacked in a column extending upward from the base or lower end of thè composite container 12 to the extent for providing therein a predetermined quantity of fissionable material for the fuel charge, which only partially occupies the interior space of the container 12.
Typically in a water cooled and moderated power generating reactor the fuel charge would occupy the major portion of the volume of the container, or the length of a tubular eIement.
The remaining portion or length o the fuel container 12 extending beyond the fuel charge contained therein, is retained vac~nt or devoid of any solid fuel material to thereby provide a plenum region for the accumulation and retention of gas~ous fission products, ~LZ05~
water vapor and the like'free volatiles. In prac-tice the plenum region is generally filled with an inert gase-ous medium of good heat transferring characteristic such as heIium to occupy -the area and improve the efficiency of heat transfer withou~ contrihuting to chemical activity.
This minor portion of the fueI element comprising the plenum comprises only a small- fraction thereof. For instance about 8 to 12 inches, preferably 10 inches, for a 160 inch long (I50 inches of fuel) boiling water reactor fuel element, and about 4 to 8 inches, preferably 6 inches, in a pressure water reactor fuel element.
The column of the' fueI charge within the container 12 is typicaLly affixed in position with a spring 20 located within the plenum region as shown.
The fuel container 12 is thus divided by its contents and/or function into two aistinct segments or portions, a fuel material retaining portion 22 and the plenum region 24.
In accordance with this invention the improved nuclear fueI eIement lO'has a protective barrier 26 of substantially pure zirconium metal superimposed contin-uously over and metallurgically bonded to the inside surface of the container cladding sheath 14 throughout the fuel retaining portion 22~ Thus, the zirconium metal barrier 26 provides a lining on thè inner surface of the container 12 in all portions thereof approximateIy adjacent to or embracing the body of the fuel material 16 retained therein.
In a prefexred embodiment of this invention, the improved nuclear fueI element 10 is produced from a composite fuel container initially having a metallurgically bonded barrier of zirconium metal extending substantially over the entire interior surface thereofO The new fuel element i~ therefore'formed by substantially completely removing the zirconium metal of the barrier member 26 from within the'portion thereof to provide the plenum ~Z05~;~7 area that extends beyond the portion adjacent the fuel charge. A honing tool of apt dimensions and length to eliminate the zirconium metal layer down to the inside diameter of the underlying alloy and for a dis~ance to the predetermined portion for ~he containment of the fueI charge, is preferred for this operation. Thus it can be achieved by means of a simple machining operation.
The zirconium metal of the barrier member 26 should be eliminated only in the portion of the fuel container designed to constitut,e the plenum region 24, and not keyond the approximate boundary betweeII the plenum region and the fueI portion of the container which is approximately adjacent to fueI charge as shown in the drawing.
The boundary between the plenum region and fuel portion within the container preferably is designated at the approximate position of the fuel-plenum interface when the column of fuel material is in a fully extended condition within the container as a result of the thermal expansion incurred under reactor service conditions. However, precision of location of the fueI-plenum interface, and in turn elimination of the zirconium metal barrier, is not particularly critical especially in boiling water reactors.
Thîs is in part so because of the reduced fission activity, and in turn heat generated, in the upper portion of the fuel column and fuel element. The lower fission activity occurs in such upper regions because the steam produced displaces the water which functions as a neutron moderator. Thus the thermal gradient is not as great in the upper regiQn of the fuel portion of the element as it is in the lower region thereof.
lS Typical nuclear fuel elements for use in BWR and PWR power generating nuclear reactors have fissionable fuel material in only a portion of the container or cladding sheath, whereby there remains a vacant region therein devoid of any fuel. The provided vacant region comprises a plenum or empty space within the fuel container for the accumulation and retention of gaseous fission products, water vapor and any other volatiles.
In this common type of nuclear fuel element, a column of fissionable uel ma-terial, such as stacked 2S pellets, is deposited within the container extending upward from its base or lower end. The quantity of fuel in the column is designed to extend therefrom to a pre-determined height or point within the container and the uppermost or remaining portion of the fuel container extending beyond the fuel charge is without fuel as illustrated in U.S.
Patent Nos. 3,898,125l issued August 5, 1975 to Grossman et al and 3,969,186, issued July 13, 1976 to Thompson et al, for example. The fuel element and its container is thus divided into a fueI portion and a plenum region at the interface boundary therebetween.
~0S~27 This plenum region within the fuel container in -the area beyond the fuel charge th~erein, is provided with a biasing means such as a spring shown in the aforesaid patents to retain the fueI charge in position, such as affixed abutting one end of the container.
Typically the fueI container plenum region is filled with helium or a like inert gas as a non-r~active, effective heat transfer medium.
Accordingly, the fuel container in the area of the plenum region beyond the fueI charge is es~ntially isothermal, and remains at a substantially equal temperature with its surroundings comprising the coolant due to the effective heat transferring capacity and mobility of the gas medium therein. The fuel container in the portion retaining the fissionable fuel material therein, is maintained at a temperatur~ gradient during power generation with respect to its surroundings comprising the coolant. Specifically, there is a temperature gradi~nt extendin~ from within the fuel charge or column outward with markedly dropping temperatures through the fuel container wall to the surrounding coolant.
In the operation of a water cooled and/or moderated nuclear reactor system the release of hydrogen from the dissociation o~ water within the coolant medium is an inherent phenomenon. The hydrogen release is primarily attributable to the irradiating conditions and high temperature of the system, and the strong affinity between oxygen and the zirconium alloys which are commonly used to fabricate fuel containers or cladding.
It has been determined that within a reactor environment, or combination of conditions such as re~erred to abo~e, the behavior of free hydrogen and its effects upon zirconium alloy fueI containers vary with respect to different temperature conditions. For instance, it appears that the hydrogen seeks lower temperature levels upon permeating zirconium alloys whereby different - ~z~
temperature gradients or levels of the fueI con-tainer cause the hydrogen to migrate in different patterns therein.
Thus, upon penetrating the zirconium alloy o~
the fuel container in the portion retaining the fissionable fuel material, and therefore wherein there is a pronounced temperature gradient, hydrogen has been found to concentrate and remain at or near the cooler outer portion of the cladding wall and it is dispersed inward thexeIrom in diminishing amounts.
On the othèr hand, the hydrogen upon contacting and pen~trating the zirconium alloy of the ue~ containex in the portion thereof providing the plenum re~ion which is essentially isothermal, has been found to exhibit a propensity to migrate and distribute uniformly through the zirconium cladding wall of a fuel container. However, when a zirconium alloy fuel container is enhanced with a barrier of zirconium metal bonded over the cladding's inner surface, such as described in the hereinbefore cited patent , the lnwardly migrating hydrogen has been found to concentrate in the inner zirconium metal barrier provided f~r the protection of the container from the interiorly generated fission products and the fuel expansion.
Accordingly, in such barrier-provided uel containers it appears that the hydrogen migratin~ into and through the zirconium alloy container wall significantly accumulates and concentrates within the area of the container wall adjacent to its interface with the ~irconium metal barrier thereon.
Such a concentration of hydrogen atoms accumulated within a limited portion of the cladding wall, particularly adjacent to the interface of the bond of the baxrier layer to the container inner surface, is an undesirable effect of the composite fuel container structure, and under severe operating conditions could degrade the fueI performance.
5~7 SUMMAR~ OF TH~ VENTION
This invention comprises means for impro~ing composite constructed nuclear fuel containers comprising a barrier of zirconium metal overlying the inner surface of a zirconium alloy container such as described in U.S.
Patent 4,~00,492, and rendering fueI elements comprising the same more resistant to hydrogen accumulation in service.
The invention specifically comprises removing substantially all zirconium metal of the barrier layer from within the approxirnate portion of the fuel container comprising or de~ining the plenum region therein~ Thus, the protec~ive barrier of zirconium metal is retained covering only the inner surface portion of thè zircon:ium alloy fuel contain-er in the area approximately adjacent to or immediately embracing the fissionable fueI material contained therein.
OBJECTS OF THE INVE~TION
It is a primary object of this invention to provide an improved nuclear fuel element comprising a composite fuel container having a cladding sheath of zirconium alloy and a protective barrier therefor of zirconium metal.
It is a further object of the invention to provide a nuclear fuel eIement having a composite cladding sheath o~ zirconium alloy and zirconium metal barrier that resists the deLeterious effects o free hydrogen, and thereby extends the service life of the fuel element.
It is also an object of this invention to provide a nuclear fuel element comprising a composite container of zirconiurn alloy with a ~ixconium metal barrier therein that increases the as-fabricated gas plenum volume and resists subsequent plenum volume reduction attributable to the action of hydrogen forming zirconium hydride compounds therein.
It is still another object of this invention to provide a method of improving nuclear fuel eIements comprising a composite container of zirconium alloy with a zirconium metal barrier therein.
~2~5~ 7 It is an additional obj'ect of this invention to provide a method of rendering nuclear ~uel elements comprising a component container of a zirconium alloy with a protective barrier of zirconium metal therein more~resistant to free hydrogen and the debilitating effects thereof upon such'fuel containers and -~heir service life.
.. . . .
DESCRIPTION OF TH~ ~R~WING
/ The figure'of the'drawing comprises a partial 10 ~ sectional view of a nuclear fuel element assembly con-taining fissionable'fueI material constructed according to this invention.
DESCRIPTION OF THE INVENTION
This invention is particularly directed to nuclear fueI elements for power generating reactors having composite fuel containers comprising a cladding sheath of an alloy of zirconium such as a Zircaloy, with a protective covering barrier of substantially pure zirconium metal metallurgically bonded over its inside surface. Nuclear fueI elements of this con9truction and composition are disclosed in U.S.
Patent No. 4,200,492.
Specifically, the invention deals with composite fuel containers constructed of a cladding sheath from a zirconium alloy having at least about 5000 parts per million by weight of constituents therein other than zirconium, and a protective barrier member therefor of a zirconium metal having less than about 5000 parts per million by weight of impurities therein. Preferably the zirconium metal of the barrier component has less than about 4200 parts per million by weight of impurities.
Alloys of zirconium for the fueI cladding sheath commonly comprise commerci~lly available Zircaloy 2 or 4 which are well known in the nuclear industry.
This invention broadly comprises precluding any degrading or deleterious effects of free hydrogen upon composite nuclear fuel -containers of the afore-5~2'7 mentioned design. ~Iydrogen caused degradation orimpairment is overcome by removing the zirconium metal barrier material from within the zirconium alloy cladding sheath in the portion extending beyond the fueI charge whereby it is devoid of fissionable fueI material and comprises the plenum region.
The resultant unique fuel container of the no-veI nuclear fueI eIement of the invention resists hydriding in and about the plenum region which is free of any fuel material. Thus it avoids any discernable reduction in the vaid volume of the plenum area of the container provided for gas collection, attributable to the action of hydrogen reacting with zirconium metal to produce zirconium hydrides within the plenum region.
lS Removal of the zirconium metal of the barrier bonded on to the inside surface of the zirconium alloy cladding in the designated axea of the plenum region can be accomplished by any one of several techniques or measures, or combinations thereof. For instance, the zirconium metal can be eIiminated by mechanical means such as abrading, reaming or honing. The mechanical dimensions to remove the zirconium metal from the surface of the alloy over an area generally coextensive with the section of the fueI container designed as the plenum reyion of the unit. Apt chemical means can also be used to remove the zirconium metal by contacting the section thereof designated for elimination of the zirconium metal with a dissoluting reagent such as an acid reactive with the metal.
Referring to the drawing, the improved nuclear fuel element 10 of the invention is constructed as follows.
Fuel element 10 includes a clos~d, elongated composite container 12 comprising a cladding sheath 14 formed of an alloy of zirconium for the enclosure o-f the fission~
able fuel material 16 and its physical isolation from the coolant medium (not shown) which surrounds the element 10 ~20S~
in service. Generally the fueI eIement 10 is tubular in configuration as illustrated. Thb container 12 includes closing end plugs affixed in ends of the tubular cladding sheath 14 to seal the container.
Fissionable fuel material 16, such as an oxide or other compound of uranium, plu~:onium, or thorium, is commonly employed in the form of a plurality of small bodies such as the cylindrical shaped peIlets shown. The fuel material 16, or units thereof, is generally of the same or similar cross--sectional configuration as the fuel container or sheath, typicallycy~indrical. Moreover, the body of the fueI material charge is of slightly smaller cross-sectioned area or dimension than the inside open area of the composite fueI container 12 to provide a ~ree space 18 between khe fueI and container or the purpose of enabling a predetermined unrestric~ed la~eral thermal expansion of the fuel material 16. Thus, in a typical tubular fuel element, the cylindrical fueI charge provided therein would be of sufficiently smaller diameter with respect to the inside of the container to leave an annular space thereabout.
The fuel material 16, ~hown in pellet form is stacked in a column extending upward from the base or lower end of thè composite container 12 to the extent for providing therein a predetermined quantity of fissionable material for the fuel charge, which only partially occupies the interior space of the container 12.
Typically in a water cooled and moderated power generating reactor the fuel charge would occupy the major portion of the volume of the container, or the length of a tubular eIement.
The remaining portion or length o the fuel container 12 extending beyond the fuel charge contained therein, is retained vac~nt or devoid of any solid fuel material to thereby provide a plenum region for the accumulation and retention of gas~ous fission products, ~LZ05~
water vapor and the like'free volatiles. In prac-tice the plenum region is generally filled with an inert gase-ous medium of good heat transferring characteristic such as heIium to occupy -the area and improve the efficiency of heat transfer withou~ contrihuting to chemical activity.
This minor portion of the fueI element comprising the plenum comprises only a small- fraction thereof. For instance about 8 to 12 inches, preferably 10 inches, for a 160 inch long (I50 inches of fuel) boiling water reactor fuel element, and about 4 to 8 inches, preferably 6 inches, in a pressure water reactor fuel element.
The column of the' fueI charge within the container 12 is typicaLly affixed in position with a spring 20 located within the plenum region as shown.
The fuel container 12 is thus divided by its contents and/or function into two aistinct segments or portions, a fuel material retaining portion 22 and the plenum region 24.
In accordance with this invention the improved nuclear fueI eIement lO'has a protective barrier 26 of substantially pure zirconium metal superimposed contin-uously over and metallurgically bonded to the inside surface of the container cladding sheath 14 throughout the fuel retaining portion 22~ Thus, the zirconium metal barrier 26 provides a lining on thè inner surface of the container 12 in all portions thereof approximateIy adjacent to or embracing the body of the fuel material 16 retained therein.
In a prefexred embodiment of this invention, the improved nuclear fueI element 10 is produced from a composite fuel container initially having a metallurgically bonded barrier of zirconium metal extending substantially over the entire interior surface thereofO The new fuel element i~ therefore'formed by substantially completely removing the zirconium metal of the barrier member 26 from within the'portion thereof to provide the plenum ~Z05~;~7 area that extends beyond the portion adjacent the fuel charge. A honing tool of apt dimensions and length to eliminate the zirconium metal layer down to the inside diameter of the underlying alloy and for a dis~ance to the predetermined portion for ~he containment of the fueI charge, is preferred for this operation. Thus it can be achieved by means of a simple machining operation.
The zirconium metal of the barrier member 26 should be eliminated only in the portion of the fuel container designed to constitut,e the plenum region 24, and not keyond the approximate boundary betweeII the plenum region and the fueI portion of the container which is approximately adjacent to fueI charge as shown in the drawing.
The boundary between the plenum region and fuel portion within the container preferably is designated at the approximate position of the fuel-plenum interface when the column of fuel material is in a fully extended condition within the container as a result of the thermal expansion incurred under reactor service conditions. However, precision of location of the fueI-plenum interface, and in turn elimination of the zirconium metal barrier, is not particularly critical especially in boiling water reactors.
Thîs is in part so because of the reduced fission activity, and in turn heat generated, in the upper portion of the fuel column and fuel element. The lower fission activity occurs in such upper regions because the steam produced displaces the water which functions as a neutron moderator. Thus the thermal gradient is not as great in the upper regiQn of the fuel portion of the element as it is in the lower region thereof.
Claims (20)
1. A nuclear fuel element comprising a closed, elongated container comprising a cladding sheath formed of an alloy of zirconium, a column of nuclear fuel material having a cross-section dimension smaller than the interior of the container disposed in and partially filling said container so as to leave a space thereabout between said fuel column and the interior of the container and to provide a plenum region within the container extending beyond the fuel column therein, said cladding sheath having a protective barrier of zirconium metal lining extending over and metallurgically bonded to only the portion of its inner surface approximately adjacent to the column of fuel therein.
2. The nuclear fuel element of claim 1, wherein the protective barrier is of substantially pure zirconium metal selected from the group of sponge zirconium and crystal bar zirconium.
3. A nuclear fuel element comprising a closed, elongated container comprising a cladding sheath formed of an alloy of zirconium, a column of nuclear fuel material having a cross-section dimension smaller than the interior of the container disposed in and partially filling said container so as to leave a space thereabout between said fuel column and the interior of the container and to provide a plenum region within the container extending beyond the fuel column whereby said column of fuel partially filling the container defines a fuel section in the portion adjacent thereto and a plenum region extending therebeyond, said cladding sheath having a protective barrier of zirconium metal lining covering over and metallurgically bonded to only the portion of its inner surface in the fuel section thereof approximately adjacent to the column of fuel therein.
4. The nuclear fuel element of claim 3, wherein the nuclear fuel material is selected from the group consisting of compounds of uranium, plutonium, and thorium, and mixtures thereof.
5. The nuclear fuel element of claim 3, wherein the protective barrier is of substantially pure zirconium metal selected from the group of sponge zirconium and crystal bar zirconium.
6. A nuclear fuel element comprising a closed, elongated container comprising a cladding sheath formed of an alloy of zirconium, a column of pellets of nuclear fuel material having a cross-section dimension smaller than the interior of the container disposed in and partially filling said container so as to leave an annular space thereabout between said column of fuel and the interior of the container and to provide a plenum region within the container extending beyond the column of fuel whereby said column of fuel partially filling the container defines a fuel section in the portion adjacent thereto and a plenum region extending therebeyond, said cladding sheath having a protective barrier of a zirconium metal lining covering over and metallurgically bonded to only the portion of its inner surface within the fuel section thereof approximately adjacent to the column of fuel therein, and the inner surface of the portion of the cladding sheath extending beyond the column of fuel forming the plenum region being substantially devoid of any zirconium metal of the protective barrier.
7. The nuclear fuel element of claim 6, wherein the protective barrier is of substantially pure zirconium metal selected from the group of sponge zirconium and crystal bar zirconium.
8. A nuclear fuel element comprising a closed, elongated tubular container comprising a cladding sheath formed of an alloy of zirconium, a column of cylindrical pellets of nuclear fuel material having a diameter smaller than the interior diameter of the tubular container disposed in and partially filling said container so as to leave an annular space thereabout between said column of fuel pellets and the interior of the container and to provide a plenum region within the container extending beyond the column of fuel pellets whereby said column of fuel pellets partially filling the container defines a fuel section in the portion of the container adjacent thereto and a plenum region extending therebeyond, said cladding sheath having a protective barrier of zirconium metal lining covering over and metallurgically bonded to only the portion of its inner surface within the fuel section thereof approximately adjacent to the column of fuel pellets therein, and the inner surface of the portion of the cladding sheath extending beyond the column of fuel pellets forming the plenum region being substantially devoid of any zirconium metal of the protective barrier.
9. The nuclear fuel element of claim 8, wherein the protective barrier is of substantially pure zirconium metal selected from the group of sponge zirconium and crystal bar zirconium.
10. A method of producing an improved nuclear fuel element having a composite container comprising a cladding sheath of an alloy of zirconium and a protective barrier of zirconium metal metallurgically bonded to the inside surface of said alloy cladding sheath, comprising the step of removing the zirconium metal of the barrier from the inside surface of the zirconium alloy cladding within the portion thereof to provide the plenum region extending from beyond the approximately upper most extent of nuclear fuel material to be provided therein for reactor service.
11. The method of claim 10, wherein the zirconium metal of the barrier is removed by mechanical means.
12. The method of claim 10, wherein the zirconium metal of the barrier is removed by honing.
13. A method of producing an improved nuclear fuel element having a composite container comprising a cladding sheath of an alloy of zirconium and a protective barrier of zirconium metal metallurgically bonded to the inside surface of said alloy cladding sheath, comprising the steps of removing the zirconium metal of the barrier from the inside surface of a segment of the zirconium alloy cladding and then introducing nuclear fuel into a segment of the zirconium alloy cladding having the protective barrier of zirconium metal retained therein.
14. The method of claim 13, wherein the zirconium metal of the barrier is removed from the segment of the alloy cladding by mechanical means.
15. The method of claim 13, wherein the zirconium metal of the barrier is removed from the segment of the alloy cladding by honing.
16. An elongated container for a nuclear fuel element comprising a cladding sheath formed of an alloy of zirconium, said cladding sheath having a protective barrier of zirconium metal lining a major portion of the length of its inner surface wherein a column of nuclear fuel is located and a minor portion of the length of its inner surface being substantially devoid of any zirconium metal.
17. The elongated container of claim 16, wherein the protective barrier of zirconium metal covers at least about 90 percent of the length of the inner surface of the cladding sheath while less than about 10 percent of the length of the inner surface thereof is substantially devoid of any zirconium metal.
18. The elongated container of claim 16, wherein the protective barrier is of substantially pure zirconium metal selected from the group of sponge zirconium and crystal bar zirconium.
19. An elongated tubular container for nuclear fuel element comprising a cladding sheath formed of an alloy of zirconium, said cladding sheath having a protective barrier of substantially pure zirconium metal selected from the group of sponge zirconium and crystal bar zirconium covering a major portion of the length of its inner surface comprising the approximate portion therein that will be adjacent to the fuel when charged therewith, and a minor portion of the length of the inner surface including the approximate portion therein that will comprise the plenum region being substantially devoid of any zirconium metal.
20. The elongated tubular container of claim 19, wherein the protective barrier of zirconium metal covers at least about 90 percent of the length of the inner surface of the cladding sheath while less than about 10 percent of the length of the inner surface thereof is substantially devoid of any zirconium metal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29575781A | 1981-08-24 | 1981-08-24 | |
| US295,757 | 1981-08-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1205927A true CA1205927A (en) | 1986-06-10 |
Family
ID=23139120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000409841A Expired CA1205927A (en) | 1981-08-24 | 1982-08-20 | Nuclear fuel element, and method of producing same |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5866093A (en) |
| BE (1) | BE894171A (en) |
| CA (1) | CA1205927A (en) |
| DE (1) | DE3226403A1 (en) |
| ES (1) | ES279692Y (en) |
| FR (1) | FR2511803B1 (en) |
| GB (1) | GB2104711B (en) |
| IT (1) | IT8222715A0 (en) |
| SE (1) | SE451415B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4775508A (en) * | 1985-03-08 | 1988-10-04 | Westinghouse Electric Corp. | Zirconium alloy fuel cladding resistant to PCI crack propagation |
| US4933136A (en) * | 1985-03-08 | 1990-06-12 | Westinghouse Electric Corp. | Water reactor fuel cladding |
| US6512806B2 (en) | 1996-02-23 | 2003-01-28 | Westinghouse Atom Ab | Component designed for use in a light water reactor, and a method for the manufacture of such a component |
| SE509382C2 (en) * | 1996-02-23 | 1999-01-18 | Asea Atom Ab | Component designed for use in a light water reactor and process for making such a component |
| US20140169516A1 (en) * | 2012-12-14 | 2014-06-19 | Global Nuclear Fuel - Americas, Llc | Fuel rods with varying axial characteristics and nuclear fuel assemblies including the same |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA805850A (en) * | 1969-02-04 | Sawatzky Anton | Protection of zirconium alloy components against hydriding | |
| US2772964A (en) * | 1954-03-15 | 1956-12-04 | Westinghouse Electric Corp | Zirconium alloys |
| US3085059A (en) * | 1958-10-02 | 1963-04-09 | Gen Motors Corp | Fuel element for nuclear reactors |
| NL6703265A (en) * | 1966-03-09 | 1967-09-11 | ||
| BE792371A (en) * | 1971-12-08 | 1973-03-30 | Gen Electric | NUCLEAR FUEL CARTRIDGE |
| US3969186A (en) * | 1974-02-11 | 1976-07-13 | General Electric Company | Nuclear fuel element |
| IL46627A (en) * | 1974-04-12 | 1977-04-29 | Gen Electric | Conditioning of nuclear reactor fuel |
| GB1507487A (en) * | 1974-06-24 | 1978-04-12 | Gen Electric | Nuclear fuel element |
| GB1525717A (en) * | 1974-11-11 | 1978-09-20 | Gen Electric | Nuclear fuel elements |
| US4200492A (en) * | 1976-09-27 | 1980-04-29 | General Electric Company | Nuclear fuel element |
| US4045288A (en) * | 1974-11-11 | 1977-08-30 | General Electric Company | Nuclear fuel element |
| JPS5445494A (en) * | 1977-09-16 | 1979-04-10 | Toshiba Corp | Fuel element |
| CA1139023A (en) * | 1979-06-04 | 1983-01-04 | John H. Davies | Thermal-mechanical treatment of composite nuclear fuel element cladding |
-
1982
- 1982-06-23 GB GB08218232A patent/GB2104711B/en not_active Expired
- 1982-07-15 DE DE19823226403 patent/DE3226403A1/en active Granted
- 1982-08-03 IT IT8222715A patent/IT8222715A0/en unknown
- 1982-08-19 ES ES1982279692U patent/ES279692Y/en not_active Expired
- 1982-08-20 CA CA000409841A patent/CA1205927A/en not_active Expired
- 1982-08-20 FR FR8214385A patent/FR2511803B1/en not_active Expired
- 1982-08-23 SE SE8204812A patent/SE451415B/en not_active IP Right Cessation
- 1982-08-23 BE BE0/208856A patent/BE894171A/en not_active IP Right Cessation
- 1982-08-24 JP JP57145588A patent/JPS5866093A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| SE8204812D0 (en) | 1982-08-23 |
| GB2104711A (en) | 1983-03-09 |
| DE3226403C2 (en) | 1987-07-16 |
| FR2511803A1 (en) | 1983-02-25 |
| ES279692Y (en) | 1985-06-01 |
| SE8204812L (en) | 1983-02-25 |
| IT8222715A0 (en) | 1982-08-03 |
| GB2104711B (en) | 1985-05-09 |
| DE3226403A1 (en) | 1983-03-10 |
| JPH0136915B2 (en) | 1989-08-03 |
| SE451415B (en) | 1987-10-05 |
| BE894171A (en) | 1983-02-23 |
| FR2511803B1 (en) | 1986-01-10 |
| JPS5866093A (en) | 1983-04-20 |
| ES279692U (en) | 1984-11-16 |
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