WO1995008827A1 - Nuclear fuel sintered body and process for producing it - Google Patents
Nuclear fuel sintered body and process for producing it Download PDFInfo
- Publication number
- WO1995008827A1 WO1995008827A1 PCT/EP1994/003060 EP9403060W WO9508827A1 WO 1995008827 A1 WO1995008827 A1 WO 1995008827A1 EP 9403060 W EP9403060 W EP 9403060W WO 9508827 A1 WO9508827 A1 WO 9508827A1
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- nuclear fuel
- sintered body
- surface film
- boron
- particles
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Classifications
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- 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
-
- 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
-
- 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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S376/00—Induced nuclear reactions: processes, systems, and elements
- Y10S376/90—Particular material or material shapes for fission reactors
- Y10S376/901—Fuel
Definitions
- the invention relates to a nuclear fuel sintered body according to claim 1, a nuclear reactor fuel element according to claim 13 and a method for producing a nuclear fuel sintered body according to claim 14.
- EP-A1-0 239 843 discloses a nuclear fuel sintered body made of U ⁇ 2 (U, Pu) ⁇ 2 and (U, Th) ⁇ 2.
- This known nuclear fuel sintered body is obtained by producing a mixture of uranium oxide powder or uranium mixed oxide powder with uranium boride or boron carbide powder and pressing it into compacts, which are then sintered in a sintering furnace in a reducing sintering atmosphere to form nuclear fuel sintered bodies.
- the boron is thus distributed uniformly everywhere in the sintered matrix.
- Boron in uranium-containing nuclear fuel sintered bodies is a neutron absorber that can be burned off in terms of physical physics and, after a certain period of use, these nuclear fuel sintered bodies lose their property as an absorber for thermal neutrons in a nuclear reactor.
- Nuclear reactor fuel elements with fuel rods which contain uranium-containing nuclear fuel sintered bodies are used in the nuclear reactor, for example, during four successive, generally equally long fuel element cycles. At the end of a fuel element cycle, some of the nuclear reactor fuel elements in the nuclear reactor are replaced by fresh, unirradiated nuclear reactor fuel elements.
- the fresh, unirradiated nuclear reactor fuel elements would bring about a relatively high reactivity in the nuclear reactor compared to the already irradiated nuclear reactor fuel elements.
- the boron in the nuclear fuel sintered bodies of these fresh, unirradiated nuclear reactor fuel elements initially dampens the reactivity brought about by these nuclear reactor fuel elements by initially absorbing thermal neutrons.
- the nuclear fuel of fresh and unirradiated nuclear reactor fuel elements gradually burns off in the nuclear reactor by nuclear fission, but at the same time a combustible neutron absorber present in this nuclear fuel gradually burns off neutron physically, so that this neutron absorber finally has little or no thermal energy Neutrons absorb. That is why even freshly inserted unirradiated nuclear reactor fuel elements in the nuclear reactor can have about the same reactivity in the nuclear reactor during their entire service life in the nuclear reactor as the nuclear reactor fuel elements that have already undergone a fuel element cycle in the nuclear reactor.
- Boron as a neutron absorber in the nuclear fuel is compared to other combustible neutron absorbers such as rare earths
- the fuel element cycles are relatively long, e.g. are longer than 12 months, since boron prevents heat build-up in the nuclear fuel.
- the invention is based on the object of developing the known nuclear fuel sintered body so that there is no increase in reactivity which is too rapid and too high when starting up a nuclear reactor if this nuclear fuel sintered body is freshly introduced into this nuclear reactor in the unirradiated state .
- the particles of boron or a chemical boron compound with a are provided surface film that holds back boron, this boron cannot escape from the nuclear fuel sintered body according to the invention. This ensures an increase in reactivity which is damped with regard to its speed and height.
- the surface film advantageously contains no boron at all.
- Claims 2 to 12 are directed to advantageous further developments of the nuclear fuel sintered body according to claim 1.
- the further development according to claim 9 ensures good retention of boron
- the further development according to claim 10 ensures a largely uniform distribution of the particles of boron or chemical boron compound in the sintered matrix of the nuclear fuel sintered body enables.
- Claim 13 relates to a nuclear reactor fuel element with a fuel rod which contains such a nuclear fuel sintered body in a cladding tube.
- the method according to claim 14 allows a relatively simple production of a nuclear fuel sintered body which contains particles of boron and / or a chemical boron compound provided with the surface film.
- Claims 14 and 15 are directed to advantageous developments of this method.
- UO2 powder is used as the powdered starting oxide and is obtained, for example, in accordance with the ammonium uranyl carbonate or AUC process (for example, Gemelin Handbook of Inorganic Chemistry, Uranium, Supplement Volume A3, 1981, pplOl to 104).
- This U ⁇ 2 "powder has an average particle diameter of 15 to 20 .mu.m.
- the U ⁇ 2 ⁇ powder can also by another method, such as the ammonium diuranate (ADU) process (e.g.
- crystalline boron powder 300 ppm of crystalline boron powder, the average particle diameter of which is 20 to 25 ⁇ m, is added to the U ⁇ 2 ⁇ powder.
- the particles of this crystalline boron powder have a surface film made of metallic molybdenum, the film thickness of which is approximately 5 ⁇ m. This surface film is in a sputtering device (e.g. E. Lang, "Coatings For High Temperature
- the sputtering device has an electrically conductive anode body, for example made of aluminum, on which crystalline boron powder was located. Furthermore, a cathode body is made of The crystalline starting boron powder with a mean starting particle size of about 15 ⁇ m is treated between anode and cathode body in a argon atmosphere at a direct electrical voltage of about 2000 V during a sputtering time of about 2.
- the crystalline boron powder rolls again and again during this sputtering on an inclined plane from the anode body, so that a uniformly thick, firmly adhering and all-round dense surface film of molybdenum is achieved on the boron powder particles.
- the surface film can also consist of at least one of the metals, ruthenium, tungsten and chromium or of at least one of the alloys molybdenum-based alloy, ruthenium-based alloy, tungsten-based alloy and chromium-based alloy. It is favorable if this surface film from a
- Chromium-nickel alloy or a molybdenum-niobium alloy exists.
- the metals of these two alloys all have one relatively small capture cross section for thermal neutrons.
- the metals rhenium, rhodium and hafnium and the base alloys of these metals are also suitable for the surface film, since these metals have a large initial cross section for thermal neutrons, but do not burn out neutron physically as quickly as boron Therefore, in conjunction with boron, particularly long fuel element cycles are possible.
- the surface film can also consist of at least one of the non-metals tantalum carbide, niobium carbide, titanium carbide, tantalum carbide, niobium carbide, titanium carbide, zirconium carbide, chro carbide, vanadium carbide, tungsten carbide, molybdenum carbide, tantalum nitride, niobium nitride, titanium nitride, zirconium nitride, zirconium nitride Vanadium silicide, tungsten silicide, molybdenum silicide, zirconium silicide, magnesium oxide, beryllium oxide, chromium oxide, calcium oxide, cerium oxide and zirconium oxide exist.
- the surface film consists of at least one of the substances silicon carbide and silicon nitride, preferably Si3N4.
- the capture cross section for thermal neutrons of these non-metals is particularly small.
- These non-metals are advantageously applied in the form of a surface film to the boron powder particles by precipitating the reaction product of a chemical gas phase reaction of chemical compounds which contain the components of the surface film (for example chemical vapor deposition (CVD) processes according to E. Lang , “Coating For High Temperature Applications", 1983, Applied Science Publishers, London and New York, pp.33 to 78). In this way, however, a metallic surface film can also be applied to the boron powder particles.
- CVD chemical vapor deposition
- 0.2% by weight of powdered zinc stearate is also added to the UO2 powder with the added crystalline boron powder as a pressing aid.
- powdered aluminum distearate can also be used as a pressing aid.
- the UO2 powder with the added boron powder and the added pressing aid is then mixed intimately in a tumbling mixer for 15 minutes.
- about 5% powdered U3O3 can be added to the powder in the tumble mixer as a pore former.
- compacts are pressed from the mixture obtained by intimate mixing, which are sintered in a hydrogen atmosphere at a sintering temperature of 1750 ° C. for three hours.
- the nuclear fuel sintered bodies After cooling, the nuclear fuel sintered bodies have a specific density of approximately 10.30 g / cm 3 to 10.55 g / cm 3 while the specific density of the boron particles in the sintered matrix is 7 to 9 g / cm 3 , that is to say in the favorable range of 5 g / cm 3 to 10 g / cm 3 .
- Boron analysis of the nuclear fuel sintered bodies after sintering shows a boron concentration of 295 ppm, that is to say only a very small boron loss within the measuring accuracy.
- the equivalent diameter of the boron particles (diameter of a sphere whose spherical volume is equal to the boron particle volume) in the sintered matrix is in the favorable range from 5 ⁇ m to 300 ⁇ m.
- the thickness of the surface film on these boron particles, which consists of a different material than the sinter matrix and the boron particles is in the favorable range from 0.3 ⁇ m to 30 ⁇ m.
- Such boron particles show practically no tendency to segregate, in particular in UO2 powder which has been obtained by the processes indicated above. No boron escapes from them during sintering.
- the boron concentration in the sinter matrix of the nuclear fuel sintered body is in the range from 100 ppm to 10,000 ppm; because on the one hand a strong damping of the speed and amount of the increase in reactivity can be achieved in a nuclear reactor into which such nuclear fuel sintered bodies are introduced as part of a fresh nuclear reactor fuel element, but on the other hand the formation of cracks in the sintered matrix of the nuclear fuel sintered body is avoided.
- the isotope B] _Q in the boron in the boron or in the boron-containing chemical compounds used is enriched compared to the natural isotope composition of boron. This can be achieved in a known manner, for example by cyclotron, diffusion or separation nozzle enrichment. This isotope B I _ Q practically absorbs the thermal neutrons. Due to its accumulation in the boron, which is located in the sintered matrix of the nuclear fuel sintered body, the concentration of this boron can be chosen to be relatively low.
- a nuclear reactor fuel element for a nuclear reactor.
- a nuclear reactor fuel element is advantageously provided for a light water nuclear reactor, in particular for a pressurized water nuclear reactor or a boiling water nuclear reactor.
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Abstract
Description
Beschreibungdescription
KERNBRENNSTOFFSINTERKÖRPER UND VERFAHREN ZU SEINER HERSTELLUNGNUCLEAR FUEL INTERBODE AND METHOD FOR THE PRODUCTION THEREOF
Die Erfindung betrifft einen Kernbrennstoffsinterkörper nach Patentanspruch 1, ein Kernreaktorbrennelement nach Patentan¬ spruch 13 und ein Verfahren zum Herstellen eines Kernbrenn- stoffsinterkörpers nach Patentanspruch 14.The invention relates to a nuclear fuel sintered body according to claim 1, a nuclear reactor fuel element according to claim 13 and a method for producing a nuclear fuel sintered body according to claim 14.
Aus der EP-A1-0 239 843 ist ein Kernbrennstoffsinterkörper aus Uθ2 (U,Pu)θ2 und (U,Th)θ2 bekannt. In der Sintermatrix dieses Kernbrennstoff-Sinterkörpers ist Bor als Neutronengift in der chemischen Verbindung UBX mit x=2 ; 4 und/oder 12 und/oder B4C eingebaut. Dieser bekannte Kernbrennstoffsinter¬ körper wird gewonnen, indem ein Gemisch aus Uranoxidpulver oder Uranmischoxidpulver mit Uranborid- oder Borcarbidpulver hergestellt und zu Preßlingen gepreßt wird, die anschließend in einem Sinterofen in einer reduzierend wirkenden Sinterat¬ mosphäre zu Kernbrennstoffsinterkörpern gesintert werden. In diesen Kernbrennstoffsinterkörpern ist somit das Bor in der Sintermatrix überall gleichmäßig verteilt.EP-A1-0 239 843 discloses a nuclear fuel sintered body made of Uθ2 (U, Pu) θ2 and (U, Th) θ2. In the sintered matrix of this nuclear fuel sintered body, boron is a neutron poison in the chemical compound UB X with x = 2; 4 and / or 12 and / or B4C installed. This known nuclear fuel sintered body is obtained by producing a mixture of uranium oxide powder or uranium mixed oxide powder with uranium boride or boron carbide powder and pressing it into compacts, which are then sintered in a sintering furnace in a reducing sintering atmosphere to form nuclear fuel sintered bodies. In these nuclear fuel sintered bodies, the boron is thus distributed uniformly everywhere in the sintered matrix.
Bor in uranhaltigen Kernbrennstoffsinterkörpern ist ein neu¬ tronenphysikalisch abbrennbarer Neutronenabsorber, der nach einer gewissen Einsatzzeit dieser Kernbrennstoffsinterkörper in einem Kernreaktor seine Eigenschaft als Absorber für ther¬ mische Neutronen verliert.Boron in uranium-containing nuclear fuel sintered bodies is a neutron absorber that can be burned off in terms of physical physics and, after a certain period of use, these nuclear fuel sintered bodies lose their property as an absorber for thermal neutrons in a nuclear reactor.
Kernreaktorbrennelemente mit Brennstäben, die uranhaltige Kernbrennstoffsinterkörper enthalten, werden z.B. während vier aufeinanderfolgender, in der Regel gleichlanger Brenn¬ element-Zyklen im Kernreaktor eingesetzt. Am Ende eines Brennelement-Zyklus wird jeweils ein Teil der Kernreaktor¬ brennelemente im Kernreaktor durch frische, unbestrahlte Kernreaktorbrennelemente ersetzt . Die frischen, unbestrahlten Kernreaktorbrennelemente würden im Kernreaktor verglichen mit den bereits bestrahlten Kern¬ reaktorbrennelementen eine verhältnismäßig hohe Reaktivität bewirken. Das Bor in den Kernbrennstoff-Sinterkörpern dieser frischen, unbestrahlten Kernreaktorbrennelemente dämpft zu¬ nächst jedoch die durch diese Kernreaktorbrennelemente be¬ wirkte Reaktivität, in dem es anfänglich thermische Neutronen absorbiert.Nuclear reactor fuel elements with fuel rods which contain uranium-containing nuclear fuel sintered bodies are used in the nuclear reactor, for example, during four successive, generally equally long fuel element cycles. At the end of a fuel element cycle, some of the nuclear reactor fuel elements in the nuclear reactor are replaced by fresh, unirradiated nuclear reactor fuel elements. The fresh, unirradiated nuclear reactor fuel elements would bring about a relatively high reactivity in the nuclear reactor compared to the already irradiated nuclear reactor fuel elements. However, the boron in the nuclear fuel sintered bodies of these fresh, unirradiated nuclear reactor fuel elements initially dampens the reactivity brought about by these nuclear reactor fuel elements by initially absorbing thermal neutrons.
Der Kernbrennstoff frischer und unbestrahlter Kernreaktor¬ brennelemente brennt im Kernreaktor durch Kernspaltung all¬ mählich ab, zugleich brennt aber auch ein in diesem Kern¬ brennstoff vorhandener abbrennbarer Neutronenabsorber neutro- nenphysikalisch allmählich ab, so daß dieser Neutronenabsor¬ ber schließlich keine oder nur noch wenige thermische Neutro¬ nen absorbier .Deshalb können auch frisch in den Kernreaktor eingesetzte unbestrahlte Kernreaktorbrennelemente während ih¬ rer gesamten Standzeit im Kernreaktor etwa gleiche Reaktivi- tat im Kernreaktor wie die Kernreaktorbrennelemente bewirken, die schon einen Brennelement-Zyklus im Kernreaktor hinter sich haben.The nuclear fuel of fresh and unirradiated nuclear reactor fuel elements gradually burns off in the nuclear reactor by nuclear fission, but at the same time a combustible neutron absorber present in this nuclear fuel gradually burns off neutron physically, so that this neutron absorber finally has little or no thermal energy Neutrons absorb. That is why even freshly inserted unirradiated nuclear reactor fuel elements in the nuclear reactor can have about the same reactivity in the nuclear reactor during their entire service life in the nuclear reactor as the nuclear reactor fuel elements that have already undergone a fuel element cycle in the nuclear reactor.
Bor als Neutronenabsorber im Kernbrennstoff ist gegenüber an- deren abbrennbaren Neutronenabsorbern wie Seltene Erden vonBoron as a neutron absorber in the nuclear fuel is compared to other combustible neutron absorbers such as rare earths
Vorteil, wenn die Brennelemen -Zyklen verhältnismäßig lang, also z.B. länger als 12 Monate sind, da mit Bor Wärmestau im Kernbrennstoff vermieden wird.Advantage if the fuel element cycles are relatively long, e.g. are longer than 12 months, since boron prevents heat build-up in the nuclear fuel.
Der Erfindung liegt die Aufgabe zugrunde, den bekannten Kern¬ brennstoff-Sinterkörper weiterzubilden, so daß kein zu schneller und zu hoher Reaktivitätεanstieg beim Anfahren ei¬ nes Kernreaktors bewirkt wird, wenn dieser Kernbrennstoffsin¬ terkörper im unbestrahlten Zustand frisch in diesen Kernreak- tor eingebracht ist.The invention is based on the object of developing the known nuclear fuel sintered body so that there is no increase in reactivity which is too rapid and too high when starting up a nuclear reactor if this nuclear fuel sintered body is freshly introduced into this nuclear reactor in the unirradiated state .
Da beim erfindungsgemäßen Kernbrennstoffsinterkörper die Par¬ tikel aus Bor oder einer chemischen Borverbindung mit einem Oberflächenfilm versehen sind, der Bor zurückhält, kann die¬ ses Bor nicht aus dem erfindungsgemäßen Kernbrennstoff-Sin¬ terkörper austreten. Damit ist ein Reaktivitätsanstieg ge¬ währleistet, der hinsichtlich seiner Geschwindigkeit und Höhe gedämpft ist .Günstigerweise enthält der Oberflächenfilm über¬ haupt kein Bor.Since in the nuclear fuel sintered body according to the invention the particles of boron or a chemical boron compound with a Are provided surface film that holds back boron, this boron cannot escape from the nuclear fuel sintered body according to the invention. This ensures an increase in reactivity which is damped with regard to its speed and height. The surface film advantageously contains no boron at all.
Die Patentansprüche 2 bis 12 sind auf vorteilhafte Weiterbil¬ dungen des Kernbrennstoffsinterkörpers nach Patentanspruch 1 gerichtet .Insbesondere die Weiterbildung nach Patentanspruch 9 gewährleistet ein gutes Zurückhalten des Bors, während die Weiterbildung nach Patentanspruch 10 eine weitgehend gleich¬ mäßige Verteilung der Partikel aus Bor bzw. der chemischen Borverbindung in der Sintermatrix des Kernbrennstoff-Sinter- körpers ermöglicht. Patentanspruch 13 betrifft ein Kernreak¬ torbrennelement mit einem Brennstab, der in einem Hüllrohr einen solchen Kernbrennstoffsinterkörper enthält.Claims 2 to 12 are directed to advantageous further developments of the nuclear fuel sintered body according to claim 1. In particular, the further development according to claim 9 ensures good retention of boron, while the further development according to claim 10 ensures a largely uniform distribution of the particles of boron or chemical boron compound in the sintered matrix of the nuclear fuel sintered body enables. Claim 13 relates to a nuclear reactor fuel element with a fuel rod which contains such a nuclear fuel sintered body in a cladding tube.
Das Verfahren nach Patentanspruch 14 erlaubt ein verhältnis- mäßig einfaches Herstellen eines Kernbrennstoffsinterkörpers, der mit dem Oberflächenfilm versehene Partikel aus Bor und/oder einer chemischen Borverbindung enthält. Die Patent¬ ansprüche 14 und 15 sind auf vorteilhafte Weiterbildungen dieses Verfahrens gerichtet .The method according to claim 14 allows a relatively simple production of a nuclear fuel sintered body which contains particles of boron and / or a chemical boron compound provided with the surface film. Claims 14 and 15 are directed to advantageous developments of this method.
Die Erfindung und ihre Vorteile seien anhand von Ausführungs- beispielen näher erläutert:The invention and its advantages are explained in more detail with reference to exemplary embodiments:
Als pulverförmiges Ausgangsoxid wird UO2-Pulver verwendet, das beispielsweise entsprechend dem Ammoniumuranylcarbonat- bzw. AUC-Verfahren (z.B. Gemelin Handbuch der Anorganischen Chemie, Uran, Ergänzungsband A3, 1981, pplOl bis 104) gewon¬ nen wird. Dieses Uθ2"Pulver hat einen mittleren Partikel¬ durchmesser von 15 bis 20 um. Das Uθ2~Pulver kann auch nach einem anderen Verfahren, z.B. dem Ammoniumdiuranat- (ADU-) Verfahren (z.B. Gmelin Handbuch der Anorganischen Chemie, Uran, Ergänzungsband A3, 1981, pp 99 bis 101) , dem IDR-Verfah- ren oder dem DC-Verfahren (z.B. Gmelin Handbuch der Anorgani¬ schen Chemie, Uran, Ergänzungsband A3, (1981), pp 104 bis 115 "Trockenchemische Prozesse") gewonnen werden. Bei dem pulver- för igen Ausgangsoxid kann es sich auch um die Mischoxide (U,Pu)02, (U,Th)02, (U,RE)02, (U,Pu,RE)02, (U,Th,RE)02 oder (U, Pu,Th,RE)θ2 mit RE=Seltene Erde (insbesondere wenigstens eines der Elemente Gadolinium, Europium und Samarium) han¬ deln.UO2 powder is used as the powdered starting oxide and is obtained, for example, in accordance with the ammonium uranyl carbonate or AUC process (for example, Gemelin Handbook of Inorganic Chemistry, Uranium, Supplement Volume A3, 1981, pplOl to 104). This Uθ2 "powder has an average particle diameter of 15 to 20 .mu.m. The Uθ2 ~ powder can also by another method, such as the ammonium diuranate (ADU) process (e.g. Gmelin Handbook of Inorganic Chemistry, Uranium, Supplement A3, 1981 , pp 99 to 101), the IDR process Ren or the DC method (eg Gmelin handbook of inorganic chemistry, uranium, supplement volume A3, (1981), pp 104 to 115 "dry chemical processes"). The powdery starting oxide can also be the mixed oxides (U, Pu) 0 2 , (U, Th) 0 2 , (U, RE) 0 2 , (U, Pu, RE) 0 2 , (U , Th, RE) 0 2 or (U, Pu, Th, RE) θ2 with RE = rare earth (in particular at least one of the elements gadolinium, europium and samarium).
Dem Uθ2~Pulver wird 300 ppm kristallines Borpulver zugesetzt, dessen mittlerer Partikeldurchmesser 20 bis 25 μm beträgt. Die Partikel dieses kristallinen Borpulvers haben einen Ober¬ flächenfilm aus metallischem Molybdän, dessen Filmdicke etwa 5 um beträgt. Dieser Oberflächenfilm wird in einer Sputter- Vorrichtung (z.B. E. Lang, "Coatings For High Temperature300 ppm of crystalline boron powder, the average particle diameter of which is 20 to 25 μm, is added to the Uθ2 ~ powder. The particles of this crystalline boron powder have a surface film made of metallic molybdenum, the film thickness of which is approximately 5 μm. This surface film is in a sputtering device (e.g. E. Lang, "Coatings For High Temperature
Applications", 1983, Applied Science Publishers, London und New York, pp.79-120) hergestellt. Die Sputtervorrichtung hat im vorliegenden Fall einen elektrisch leitenden Anodenkörper z.B. aus Aluminium, auf dem sich kristallines Ausgangsborpul- ver befand. Ferner ist ein Katodenkörper aus Molybdänblech vorhanden. Das kristalline Ausgangsborpulver mit einer mitt¬ leren Ausgangspartikelgröße von etwa 15 um wird während einer Sputterzeit von etwa 2 Stunden in Argonatmosphäre bei einer elektrischen Gleichspannung von etwa 2000 V zwischen Anoden- und Katodenkörper behandelt. Während dieses Sputterns rollt das kristalline Borpulver immer wieder auf einer schiefen Ebene am Anodenkörper ab, so daß ein gleichmäßig dicker, fest haftender und allseitig dichter Oberflächenfilm aus Molybdän auf den Borpulverpartikeln erzielt wird.Applications ", 1983, Applied Science Publishers, London and New York, pp.79-120). In the present case, the sputtering device has an electrically conductive anode body, for example made of aluminum, on which crystalline boron powder was located. Furthermore, a cathode body is made of The crystalline starting boron powder with a mean starting particle size of about 15 μm is treated between anode and cathode body in a argon atmosphere at a direct electrical voltage of about 2000 V during a sputtering time of about 2. The crystalline boron powder rolls again and again during this sputtering on an inclined plane from the anode body, so that a uniformly thick, firmly adhering and all-round dense surface film of molybdenum is achieved on the boron powder particles.
Der Oberflächenfilm kann auch aus mindestens einem der Me¬ talle , Ruthenium, Wolfram und Chrom oder aus mindestens ei¬ ner der Legierungen Molybdänbasislegierung, Rutheniumbasisle¬ gierung, Wolframbasislegierung und Chrombasislegierung beste- hen. Günstig ist, wenn dieser Oberflächenfilm aus einerThe surface film can also consist of at least one of the metals, ruthenium, tungsten and chromium or of at least one of the alloys molybdenum-based alloy, ruthenium-based alloy, tungsten-based alloy and chromium-based alloy. It is favorable if this surface film from a
Chrom-Nickel-Legierung oder einer Molybdän-Niob-Legierung be¬ steht. Die Metalle dieser beiden Legierungen haben alle einen verhältnismäßig geringen Einfangsquerschnitt für thermische Neutronen. Geeignet für den Oberflächenfilm sind auch die Me¬ talle Rhenium, Rhodium und Hafnium, sowie die Basislegierun- gen dieser Metalle, da diese Metalle zwar einen großen Ein- fangsquerschnitt für thermische Neutronen haben, aber nicht so schnell neutronenphysikalisch ausbrennen wie Bor. Sie kön¬ nen daher in Verbindung mit Bor besonders lange Brennele¬ mentzyklen ermöglichen.Chromium-nickel alloy or a molybdenum-niobium alloy exists. The metals of these two alloys all have one relatively small capture cross section for thermal neutrons. The metals rhenium, rhodium and hafnium and the base alloys of these metals are also suitable for the surface film, since these metals have a large initial cross section for thermal neutrons, but do not burn out neutron physically as quickly as boron Therefore, in conjunction with boron, particularly long fuel element cycles are possible.
Der Oberflächenfilm kann auch aus mindestens einem der Nicht¬ metalle Tantalcarbid, Niobcarbid, Titancarbid, Tantalcarbid, Niobcarbid, Titancarbid, Zirkoniumcarbid, Chro carbid, Vana- diumcarbid, Wolframcarbid, Molybdäncarbid, Tantalnitrid, Niobnitrid, Titannitrid, Zirkoniumnitrid, Vanadiumnitrid, Tantalsilizid, Niobsilizid, Vanadiumsilizid, Wolframsilizid, Molybdänsilizid, Zirkoniumsilizid, Magnesiumoxid, Beryllium¬ oxid, Chromoxid, Calciumoxid, Ceroxid und Zirkoniumoxid be¬ stehen. In besonders vorteilhafter Weise besteht der Oberflä¬ chenfilm aus mindestens einem der Stoffe Siliziumcarbid und Siliziumnitrid, vorzugsweise Si3N4. Der Einfangsquerschnitt für thermische Neutronen dieser Nichtmetalle ist besonders gering. Diese Nichtmetalle werden günstigerweise in Form ei¬ nes Oberflächenfilms auf die Borpulverpartikel durch Nieder¬ schlagen des Reaktionsprodukts einer chemischen Gasphasen- reaktion von chemischen Verbindungen aufgebracht, die die Komponenten des Oberflächenfilms enthalten (z.B. Chemical Vapour Deposition- (CVD-) Verfahren nach E. Lang, "Coating For High Temperature Applications", 1983, Applied Science Publishers, London und New York, pp.33 bis 78) . Auf diese Weise kann aber auch ein metallischer Oberflächenfilm auf die Borpulverpartikel aufgebracht werden.The surface film can also consist of at least one of the non-metals tantalum carbide, niobium carbide, titanium carbide, tantalum carbide, niobium carbide, titanium carbide, zirconium carbide, chro carbide, vanadium carbide, tungsten carbide, molybdenum carbide, tantalum nitride, niobium nitride, titanium nitride, zirconium nitride, zirconium nitride Vanadium silicide, tungsten silicide, molybdenum silicide, zirconium silicide, magnesium oxide, beryllium oxide, chromium oxide, calcium oxide, cerium oxide and zirconium oxide exist. In a particularly advantageous manner, the surface film consists of at least one of the substances silicon carbide and silicon nitride, preferably Si3N4. The capture cross section for thermal neutrons of these non-metals is particularly small. These non-metals are advantageously applied in the form of a surface film to the boron powder particles by precipitating the reaction product of a chemical gas phase reaction of chemical compounds which contain the components of the surface film (for example chemical vapor deposition (CVD) processes according to E. Lang , "Coating For High Temperature Applications", 1983, Applied Science Publishers, London and New York, pp.33 to 78). In this way, however, a metallic surface film can also be applied to the boron powder particles.
Dem UO2-Pulver mit dem zugesetzten kristallinen Borpulver wird ferner 0.2 Gew.-% pulverförmiges Zinkstearat als Preß- hilfsmittel zugefügt. Anstelle von Zinkstearat kann auch pul¬ verförmiges Alu iniumdistearat als Preßhilfsmittel verwendet werden. Das UO2-Pulver mit dem zugesetzten Borpulver und dem zugesetzten Preßhilfsmittel wird sodann in einer Taumelmisch¬ anlage 15 Minuten lang innig vermischt. Auch kann dem Pulver in der Taumelmischanlage noch etwa 5 % pulverförmiges U3O3 als Porenbildner zugesetzt werden. Die Tatsache, daß mit Molybdän beschichtete Partikel des kristallinen Borpulvers etwa die gleiche Dichte haben wie die Partikel des Uθ2~Pul- vers, fördert die innige Vermischung dieser beiden Pulver miteinander und steht einer Entmischung beim späteren Trans¬ port und Lagern des Gemisches entgegen.0.2% by weight of powdered zinc stearate is also added to the UO2 powder with the added crystalline boron powder as a pressing aid. Instead of zinc stearate, powdered aluminum distearate can also be used as a pressing aid. The UO2 powder with the added boron powder and the added pressing aid is then mixed intimately in a tumbling mixer for 15 minutes. Also, about 5% powdered U3O3 can be added to the powder in the tumble mixer as a pore former. The fact that particles of the crystalline boron powder coated with molybdenum have approximately the same density as the particles of the UO 2 powder promotes the intimate mixing of these two powders with one another and prevents segregation during the subsequent transport and storage of the mixture.
Aus dem durch inniges Vermischen gewonnenen Gemisch werden schließlich Preßkörper gepreßt, die in Waserstoff-Atmosphäre bei einer Sintertemperatur von 1750° C drei Stunden lang ge¬ sintert werden. Nach dem Abkühlen haben die Kernbrennstoff- Sinterkörper eine spezifische Dichte von etwa 10.30 g/cm3 bis 10.55 g/cm3 während die spezifische Dichte der Borpartikel in der Sintermatrix 7 bis 9 g/cm3 beträgt, also im günstigen Be¬ reich von 5 g/cm3 bis 10 g/cm3 liegt.Finally, compacts are pressed from the mixture obtained by intimate mixing, which are sintered in a hydrogen atmosphere at a sintering temperature of 1750 ° C. for three hours. After cooling, the nuclear fuel sintered bodies have a specific density of approximately 10.30 g / cm 3 to 10.55 g / cm 3 while the specific density of the boron particles in the sintered matrix is 7 to 9 g / cm 3 , that is to say in the favorable range of 5 g / cm 3 to 10 g / cm 3 .
Bei metallischem, silizidischem oder oxidischem Oberflächen¬ film auf den Partikeln des Borpulvers wird außer in H2-Atmo¬ sphäre vorteilhafterweise auch in Inertgas, z.B. Argon, ge¬ sintert, während bei einem carbidischen Oberflächenfilm das Sintern günstigerweise in CO und /oder CO2 und bei nitridi- sehen Oberflächenfilm in Stickstoffe und/oder einer gasför¬ migen Ammoniakverbindung vorgenommen wird, so daß ein Zerset¬ zen des Oberflächenfilms durch die Sinteratmosphäre praktisch vermieden wird. Da überdies die Sintertemperatur kleiner als der Schmelzpunkt des Oberflächenfilms aus den angegebenen Me- tallen, Metall-Legierungen und Nichtmetallen auf den Borpar¬ tikeln ist, bleibt dieser Oberflächenfilm gleichmäßig dicht.In the case of metallic, silicidic or oxidic surface film on the particles of the boron powder, in addition to the H2 atmosphere, it is advantageously also carried out in inert gas, e.g. Argon, sintered, while in the case of a carbide surface film the sintering is advantageously carried out in CO and / or CO2 and in the case of nitride surface film in nitrogen and / or a gaseous ammonia compound, so that the surface film is decomposed by the sintering atmosphere is practically avoided. Since, moreover, the sintering temperature is lower than the melting point of the surface film made of the specified metals, metal alloys and non-metals on the boron particles, this surface film remains uniformly dense.
Eine Boranalyse der Kernbrennstoffsinterkörper nach dem Sin¬ tern ergibt eine Borkonzentration von 295 ppm, also nur einen sehr geringen Borverlust innerhalb der Meßgenauigkeit. Der äquivalente Durchmesser der Borpartikel (Durchmesser einer Kugel, deren Kugelvolumen dem Borpartikelvolumen gleich ist) in der Sintermatrix liegt im günstigen Bereich von 5 μm bis 300 um. Ferner liegt die Dicke des Oberflächenfilms auf die¬ sen Borpartikeln, der aus einem anderen Stoff als die Sinter¬ matrix und die Borpartikel besteht, im günstigen Bereich von 0.3 μm bis 30 μm. Derartige Borpartikel zeigen insbesondere in UO2-Pulver, das nach den oben angegebenen Verfahren gewon¬ nen wurde, praktisch keine Entmischungstendenz. Während des Sinterns entweicht aus ihnen auch kein Bor.Boron analysis of the nuclear fuel sintered bodies after sintering shows a boron concentration of 295 ppm, that is to say only a very small boron loss within the measuring accuracy. The equivalent diameter of the boron particles (diameter of a sphere whose spherical volume is equal to the boron particle volume) in the sintered matrix is in the favorable range from 5 μm to 300 μm. Furthermore, the thickness of the surface film on these boron particles, which consists of a different material than the sinter matrix and the boron particles, is in the favorable range from 0.3 μm to 30 μm. Such boron particles show practically no tendency to segregate, in particular in UO2 powder which has been obtained by the processes indicated above. No boron escapes from them during sintering.
Beim Verwenden von pulverförmigem Zirkoniumdiborid ZrB2 als borhaltige Verbindung anstelle des kristallinen Bors wurden ähnlich geringe Borverluste beim Sintern erzielt.When using powdered zirconium diboride ZrB2 as the boron-containing compound instead of the crystalline boron, similarly low boron losses were achieved during sintering.
Es ist vorteilhaft, wenn die Borkonzentration in der Sinter- matrix des Kernbrennstoffsinterkörpers im Bereich von 100 ppm bis 10 000 ppm liegt; denn dadurch kann einerseits eine star¬ ke Dämpfung von Geschwindigkeit und Höhe des Reaktivitätsan- stiegs in einen Kernreaktor erzielt werden, in den solche Kernbrennstoffsinterkörper als Bestandteil eines frischen Kernreaktorbrennelements eingebracht werden, andererseits wird aber auch eine Ausbildung von Rissen in der Sintermatrix des Kernbrennstoffsinterkörpers vermieden.It is advantageous if the boron concentration in the sinter matrix of the nuclear fuel sintered body is in the range from 100 ppm to 10,000 ppm; because on the one hand a strong damping of the speed and amount of the increase in reactivity can be achieved in a nuclear reactor into which such nuclear fuel sintered bodies are introduced as part of a fresh nuclear reactor fuel element, but on the other hand the formation of cracks in the sintered matrix of the nuclear fuel sintered body is avoided.
Es ist günstig, wenn in dem verwendeten Bor bzw. in den ver- wendeten borhaltigen chemischen Verbindungen das Isotop B]_Q im Bor verglichen mit der natürlichen Isotopenzusammenset- zung des Bors angereichert ist. Dies kann in bekannter Weise z.B. durch Zyklotron-, Diffusions- oder Trenndüsenanreiche¬ rung erzielt werden. Dieses Isotop BI_Q absorbiert praktisch die thermischen Neutronen. Durch seine Anreicherung im Bor, das sich in der Sintermatrix des Kernbrennstoffsinterkörpers befindet, kann die Konzentration dieses Bors verhältnismäßig gering gewählt werden.It is favorable if the isotope B] _Q in the boron in the boron or in the boron-containing chemical compounds used is enriched compared to the natural isotope composition of boron. This can be achieved in a known manner, for example by cyclotron, diffusion or separation nozzle enrichment. This isotope B I _ Q practically absorbs the thermal neutrons. Due to its accumulation in the boron, which is located in the sintered matrix of the nuclear fuel sintered body, the concentration of this boron can be chosen to be relatively low.
Es ist vorteilhaft, die erfindungsgemäßen Kernbrennstoff-Sin¬ terkörper in ein Hüllrohr, in der Regel aus einer Zirkonium- basislegierung oder rostfreiem Stahl, eines Brennstabs einzu- bringen und dieses Hüllrohr gasdicht zu verschließen. Dieser Brennstab ist günstigerweise Bestandteil eines Kernreaktor¬ brennelements für einen Kernreaktor. Vorteilhafterweise ist ein solches Kernreaktorbrennelement für einen Leichtwasser- kernreaktor vorgesehen, insbesondere für einen Druckwasser¬ kernreaktor oder einen Siedewasserkernreaktor.It is advantageous to insert the nuclear fuel sintered bodies according to the invention into a cladding tube, usually made of a zirconium-based alloy or stainless steel, of a fuel rod. bring and seal this cladding gas-tight. This fuel rod is advantageously part of a nuclear reactor fuel element for a nuclear reactor. Such a nuclear reactor fuel element is advantageously provided for a light water nuclear reactor, in particular for a pressurized water nuclear reactor or a boiling water nuclear reactor.
Versuche an einem solchen Hüllrohr, die die Bedingungen in einem Kernreaktor simulierten, ergaben, daß Bor sogar bei Temperaturen von 800 °C und mehr nicht aus den Kernbrenn¬ stoff-Sinterkörpern entweicht. Experiments on such a cladding tube, which simulated the conditions in a nuclear reactor, showed that boron does not escape from the nuclear fuel sintered bodies even at temperatures of 800 ° C. and higher.
Claims
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP94926937A EP0720766A1 (en) | 1993-09-22 | 1994-09-13 | Nuclear fuel sintered body and process for producing it |
| JP7509538A JPH09503858A (en) | 1993-09-22 | 1994-09-13 | Nuclear fuel sintered body, nuclear reactor fuel element having nuclear fuel sintered body, and method for manufacturing nuclear fuel sintered body |
| KR1019960701486A KR960705324A (en) | 1993-09-22 | 1996-03-22 | Nuclear fuel sintered body and its manufacturing method (NUCLEAR FUEL SINTERED BODY AND PROCESS FOR PRODUCING IT) |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP93115342.3 | 1993-09-22 | ||
| EP93115342 | 1993-09-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1995008827A1 true WO1995008827A1 (en) | 1995-03-30 |
Family
ID=8213295
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP1994/003060 Ceased WO1995008827A1 (en) | 1993-09-22 | 1994-09-13 | Nuclear fuel sintered body and process for producing it |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0720766A1 (en) |
| JP (1) | JPH09503858A (en) |
| KR (1) | KR960705324A (en) |
| TW (1) | TW257869B (en) |
| WO (1) | WO1995008827A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2814584A1 (en) * | 2000-09-27 | 2002-03-29 | Commissariat Energie Atomique | NUCLEAR FUEL COMPRISING A CONSUMABLE POISON AND ITS MANUFACTURING METHOD |
| KR100746800B1 (en) | 2002-03-11 | 2007-08-06 | 우렌코 네덜란드 비.브이. | A method of providing a nuclear fuel, and a fuel component provided with a nuclear fuel obtained by the method |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2787370B1 (en) * | 1998-12-22 | 2001-03-16 | Franco Belge Combustibles | METHOD FOR JOINING TWO COAXIAL TUBULAR PARTS, TOOL FOR MAKING THE SAME AND USE THEREOF |
| KR100331483B1 (en) * | 1999-06-02 | 2002-04-03 | 장인순 | Method of manufacturing oxide fuel pellets containing neutron-absorbing materials |
| KR101436499B1 (en) * | 2012-11-05 | 2014-09-01 | 한국원자력연구원 | Fabrication method of burnable absorber nuclear fuel pellet using rapid sintering, and the burnable absorber nuclear fuel pellet thereby |
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|---|---|---|---|---|
| FR1414598A (en) * | 1963-11-25 | 1965-10-15 | Int Research & Dev Co Ltd | Improvements in materials containing boron and in the processes for their production |
| US3917768A (en) * | 1969-02-25 | 1975-11-04 | Fiat Spa | Sintered nuclear fuel and method of preparing same |
| US4671927A (en) * | 1984-12-03 | 1987-06-09 | Westinghouse Electric Corp. | Nuclear fuel rod containing a hybrid gadolinium oxide, boron carbide burnable absorber |
| EP0239843A1 (en) * | 1986-03-24 | 1987-10-07 | Siemens Aktiengesellschaft | Sintered nuclear-fuel body, and method of manufacturing it |
| ES2002719A6 (en) * | 1986-07-22 | 1988-10-01 | Westinghouse Electric Corp | A FUEL PAD FOR A NUCLEAR REACTOR |
| JPH01155294A (en) * | 1987-12-14 | 1989-06-19 | Toshiba Corp | Neutron absorber |
| EP0418578A1 (en) * | 1989-09-18 | 1991-03-27 | General Electric Company | Fissionable nuclear fuel composition |
-
1994
- 1994-08-25 TW TW083107798A patent/TW257869B/zh active
- 1994-09-13 WO PCT/EP1994/003060 patent/WO1995008827A1/en not_active Ceased
- 1994-09-13 JP JP7509538A patent/JPH09503858A/en active Pending
- 1994-09-13 EP EP94926937A patent/EP0720766A1/en not_active Ceased
-
1996
- 1996-03-22 KR KR1019960701486A patent/KR960705324A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1414598A (en) * | 1963-11-25 | 1965-10-15 | Int Research & Dev Co Ltd | Improvements in materials containing boron and in the processes for their production |
| US3917768A (en) * | 1969-02-25 | 1975-11-04 | Fiat Spa | Sintered nuclear fuel and method of preparing same |
| US4671927A (en) * | 1984-12-03 | 1987-06-09 | Westinghouse Electric Corp. | Nuclear fuel rod containing a hybrid gadolinium oxide, boron carbide burnable absorber |
| EP0239843A1 (en) * | 1986-03-24 | 1987-10-07 | Siemens Aktiengesellschaft | Sintered nuclear-fuel body, and method of manufacturing it |
| ES2002719A6 (en) * | 1986-07-22 | 1988-10-01 | Westinghouse Electric Corp | A FUEL PAD FOR A NUCLEAR REACTOR |
| JPH01155294A (en) * | 1987-12-14 | 1989-06-19 | Toshiba Corp | Neutron absorber |
| EP0418578A1 (en) * | 1989-09-18 | 1991-03-27 | General Electric Company | Fissionable nuclear fuel composition |
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| DATABASE WPI Section Ch Week 8930, Derwent World Patents Index; Class K05, AN 89-217108 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2814584A1 (en) * | 2000-09-27 | 2002-03-29 | Commissariat Energie Atomique | NUCLEAR FUEL COMPRISING A CONSUMABLE POISON AND ITS MANUFACTURING METHOD |
| EP1193717A1 (en) * | 2000-09-27 | 2002-04-03 | Commissariat A L'energie Atomique | Nuclear fuel comprising a burable poison and method of manufacture therefor |
| KR100746800B1 (en) | 2002-03-11 | 2007-08-06 | 우렌코 네덜란드 비.브이. | A method of providing a nuclear fuel, and a fuel component provided with a nuclear fuel obtained by the method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09503858A (en) | 1997-04-15 |
| KR960705324A (en) | 1996-10-09 |
| EP0720766A1 (en) | 1996-07-10 |
| TW257869B (en) | 1995-09-21 |
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