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WO2010086431A1 - Élément combustible contenant une matière fissile et une matière fertile, ainsi que son procédé de fabrication - Google Patents

Élément combustible contenant une matière fissile et une matière fertile, ainsi que son procédé de fabrication Download PDF

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Publication number
WO2010086431A1
WO2010086431A1 PCT/EP2010/051136 EP2010051136W WO2010086431A1 WO 2010086431 A1 WO2010086431 A1 WO 2010086431A1 EP 2010051136 W EP2010051136 W EP 2010051136W WO 2010086431 A1 WO2010086431 A1 WO 2010086431A1
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WIPO (PCT)
Prior art keywords
fuel
core
particles
uranium
coated
Prior art date
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Ceased
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PCT/EP2010/051136
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German (de)
English (en)
Inventor
Milan Hrovat
Richard Seemann
Karl-Heinz Grosse
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ALD Vacuum Technologies GmbH
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ALD Vacuum Technologies GmbH
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Filing date
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Application filed by ALD Vacuum Technologies GmbH filed Critical ALD Vacuum Technologies GmbH
Publication of WO2010086431A1 publication Critical patent/WO2010086431A1/fr
Anticipated expiration legal-status Critical
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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
    • G21C3/42—Selection of substances for use as reactor fuel
    • G21C3/58—Solid reactor fuel Pellets made of fissile material
    • G21C3/62—Ceramic fuel
    • G21C3/626—Coated fuel particles
    • 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
    • G21C3/28—Fuel elements with fissile or breeder material in solid form within a non-active casing
    • 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

Definitions

  • the present invention relates to a fuel assembly (BE) comprising a fuel and a breeding material, and a method for its production.
  • BE fuel assembly
  • the present invention provides fuel assemblies that are characterized by having a high residence time in the reactor.
  • the fuel assemblies of the present invention preferably have a diameter of about 60 mm. They preferably contain a graphite matrix as the main component. Furthermore, they have a core, which preferably has a diameter of about 48 mm.
  • the broth-containing core preferably contains thorium as a breeding substance in coated particles and is enclosed by a preferably 3 mm-thick gap-containing layer.
  • the fissile is preferably also present in coated particles.
  • the fuel is preferably selected from uranium, preferably UO 2 , or fissile plutonium isotopes.
  • the fuel assembly further includes an outer shell.
  • the outer shell of preferably 3 mm thickness is fuel-free and preferably comprises the graphite matrix and may additionally contain silicon carbide.
  • the brittle-containing core and the nip-containing layer and the outer shell are preferably seamlessly connected to each other by pressing and thus form a unit.
  • the core of the fuel element according to the invention preferably contains about 31 g of thorium and about 1.7 g of uranium as (U 1 Th) O 2 coated particles and the fissile layer contains 4.6 g of uranium as UO 2 particles.
  • the uranium in the core and in the shell is preferably enriched to about 17% of U-235. To maintain the negative temperature coefficient, preferably about 27% of the U-235 is shifted from the fissile layer into the core.
  • the core diameter of the coated UO 2 and (U, Th) O 2 particles is preferably about 500 ⁇ m.
  • the essential feature of the proposed fuel is the separate arrangement of the breeding substance in the core and the fissile in the
  • uranium-233 from thorium and the formation of fissile plutonium isotopes from uranium-238.
  • the uranium converted from uranium to uranium-233 is a valuable fissile and is characterized by high ⁇ values. With a 2.21 ⁇ value for uranium-233, it is significantly higher than the ⁇ value of uranium-235 of 1.95.
  • the manufacturing method according to the invention preferably provides the step of producing a graphite powder, which serves to construct the graphite matrix.
  • the graphite press powder preferably has approximately the following composition: 64 percent by weight natural graphite, 16 percent by weight graphitized petroleum coke, 20 percent by weight phenol formaldehyde resin.
  • the phenol-formaldehyde resin is preferably characterized by the condensing agent HCl, a molecular weight of about 690, a softening point of about 101 0 C, a pH of about 6, an acid number of about 7.5, free phenol of about 0.12 % By weight, coke yield of about 50%, a solubility in methanol of about 99.97% by weight, an ash content of about 160 ppm and / or a boron equivalent from the impurities of the ash of ⁇ 1 ppm.
  • the condensing agent HCl a molecular weight of about 690, a softening point of about 101 0 C, a pH of about 6, an acid number of about 7.5, free phenol of about 0.12 %
  • coke yield of about 50% a solubility in methanol of about 99.97% by weight
  • an ash content of about 160 ppm and / or a boron equivalent from the impurities of the ash of
  • the resin is preferably subjected to a steam distillation after the condensation.
  • the natural and electrographic powders are homogenized in a weight ratio of preferably about 4: 1 dry in a mixer.
  • the phenolic resin is dissolved in methanol.
  • the weight ratio of resin to methanol is preferably about 1.25: 2.3.
  • the graphite powder mixture and the resin dissolved in the methanol are preferably transferred to a kneader.
  • the methanol can be replaced by denatured ethanol.
  • the kneaded material is preferably pressed out by extrusion on a belt dryer and dried at about 105 0 C.
  • the evaporated methanol (ethanol) is preferably recycled.
  • the kneaded material is preferably broken with a hammer mill (sieve adjustment about 1 mm), then homogenized and stored as needed.
  • the method comprises the addition of SiÜ 2 to the graphite press powder.
  • This oxide is later converted into carbide when coked.
  • the content of the kneaded SiO 2 powder is preferably about 83.4% by weight based on the binder resin. This corresponds to a volume fraction in the 3 mm thick shell of 6.8%.
  • the manufacturing method of the present invention further preferably provides the step of producing coated particles.
  • the fuel and / or the breeding substance are present in the form of such coated particles within the fuel element.
  • a coated particle always has a core, which is provided with a coating.
  • the core may preferably be prepared by the gel precipitation method by dripping solutions of the substances to be coated. This method comprises a sintering step resulting in cores having, for example, a diameter of about 500 ⁇ m with a density of about 10.4 g / cm 3 .
  • the solution to be dripped preferably contains polyvinyl alcohol (PVA) and / or tetrahydrofurfuryl alcohol (THFA).
  • PVA polyvinyl alcohol
  • THFA tetrahydrofurfuryl alcohol
  • the required pH is preferably adjusted with ammonia.
  • the cores are calcined and sintered. This is described in the publication DE 10204166 A1; This document is hereby expressly incorporated into the present application.
  • the two processes of calcination and sintering are preferably carried out in a cascade rotary kiln.
  • the oven includes a double-sided and inclined tube. Inside the tube, crucible fittings (cascades) are integrated.
  • the crucible moldings have openings on both sides for the passage of the particles and are arranged offset one after the other. In one revolution of the tube, the particles move gently into the next in the flow direction located crucible molding (cascade).
  • the bottom residual surface of the crucible molding nozzle is preferably slightly more than 50%. It prevents slippage of the particles in the axis of rotation and serves as a radiation shield. Consequently, an optimal transverse mixing of the moving (circulated) particles without mixing with the particles in the adjacent chambers (cascades) is ensured. In addition, a defined particle flow is achieved along the entire furnace.
  • the sintered particles are preferably sieved in a drum apparatus and the non-round particles or particles with "noses" on a vibrating plate are separated from the target fraction
  • the proportion of separated particles is relatively low and amounts to about 1% by weight.
  • the brood and / or fission cores thus obtained are provided with a coating in a further method step according to preferred embodiments.
  • the coating of the cores with pyrolytic carbon and silicon carbide for example, preferred in fluidized beds.
  • These systems consist of a vertical graphite tube with conical bottom, which is heated from the outside, preferably with a graphite resistance heater.
  • the carrier gas required for whirling, preferably argon or hydrogen, and coating gases is introduced.
  • the coating method comprises applying at least one pyrocarbon layer and one silicon carbide layer.
  • the pyrocarbon layers are deposited by thermal decomposition of a mixture comprising ethyne and propyne at temperatures between about 1200 ° C. and 1400 ° C.
  • the coating gas used is methyltrichlorosilane.
  • the deposition temperature is slightly higher and is about 1500 0 C.
  • the reaction and carrier gases are introduced via a water-cooled nozzle lance through a provided with nine holes cone insert from below into the reaction space.
  • the geometry of the cone, the arrangement of the bores, the bore diameter, the angle of inclination of the bores and the gas flow of the coating gases are coordinated so that a very good low vortex height of the particles of less than 500 mm is formed.
  • a uniform concentration of the coating gases can be achieved. This is an important prerequisite for depositing uniform, dense and isotropic layers without soot inclusions.
  • a discharge of the particles is prevented from the reaction tube.
  • the concentration of the reaction gases is preferably about 54% by volume for C 2 H 2 and about 46% by volume for CsH 6 .
  • This composition allows for an exothermic reaction, a deposition of the ILTI and Olti (Inner and Outer Layer isotropy Low Temperature Low Temperature isotropy Layer) at temperatures below 1300 0 C. Consequently, a diffusion of uranium via the gas phase in pyrocarbon layers (Coating contamination) is avoided.
  • ILTI and Olti Inner and Outer Layer isotropy Low Temperature Low Temperature isotropy Layer
  • the cores having a preferred diameter of about 0.5 mm and a preferred density of about 10.4 g / cm 3 are preferably coated four times: first with a buffer layer of pyrocarbon (thickness preferably about 95 ⁇ m, density of preferably about 1, 05 g / cm 3 ), then with a dense pyrocarbon layer (thickness preferably about 40 ⁇ m, density preferably about 1.90 g / cm 3 ), then with a dense SiC layer (thickness preferably about 35 ⁇ m, density preferably about 3, 19 g / cm 3 ) and finally with a dense pyrocarbon layer (thickness preferably about 40 ⁇ m, density preferably about 1.90 g / cm 3 ).
  • the fluids of tetrabromoethane with a density of 2.97 g / cm 3 and barium tetrachloride with a density of 3.49 g / cm 3 can be used in the buoyancy process.
  • the proportion of separated coated particles by sieving and floating is relatively low and is less than 5 wt.%.
  • the manufacturing method according to the invention further comprises the steps of pressing the Brutstoffkernes and repressing the Brutstoff core with the cleavage-containing layer.
  • the number of particles in the fissile layer is about 12,180 and in the ball core about 68,840, which corresponds to a proven by the production and irradiation ago volume loading of 35%.
  • Starting components for the pressing of the fuel elements are the coated particles and the graphite press powder.
  • the coated particles are mixed with the graphite press powder. Then, this mixture is preferably transferred into rubber molds, which are preferably surrounded by steel molds.
  • the material to be compacted is then at a pressure of preferably between 3 and 10 MPa kernel to a viable B renn fabric. This core is then pressed with the clinker-containing layer and transferred into a form that already contains the lower half of the fuel-free layer.
  • the pressing pressure which surrounds the fuel-free layer with the core, which is already surrounded by a gap-containing layer, is preferably in the range between 10 and 30 MPa.
  • the fuel elements are preferably finished with a high-pressure press with a pressing force of preferably about 250 tons with an upper and a lower punch and a steel die with preferably about 10 cm inside diameter.
  • the automated pressing of the fuel elements takes place in two successive stages, namely a first phase of the pre- and post-pressing, which is followed by a third phase of the final pressing.
  • the punching time of the molds is also longer, because there is no more powder in the parting lines, where it causes wear.
  • the already pre-compressed fuel elements are between two rubber cups with an outer diameter of preferably only 10 cm finished pressed, consequently, a lower pressing force is required.
  • the production frequency per fuel element is about 10 seconds. Only one person is required to monitor and operate the system.
  • the method according to the invention preferably also includes over-spinning of the fuel elements. After pressing, the fuel elements are preferably over-turned to the nominal diameter. The shrinkage of the balls during the heat treatment is taken into account.
  • the method according to the invention preferably comprises a heat treatment of the fuel elements.
  • the fuel assemblies are te in an inert atmosphere, preferably argon was heated in an oven at preferably about 85O 0 C.
  • the heating and cooling cycle is preferably about 11 hours.
  • the furnace is preferably a circulating furnace in the form of a cylindrical hood furnace with internal heating.
  • the fuel elements are preferred in vacuo (2 mbar, preferably ⁇ ⁇ 10) calcined at preferably about 2000 0 C.
  • the mixed SiO 2 reacts with the binder coke selectively to SiC (according to DE-102006040309).
  • the annealing is preferably carried out in an induction furnace designed for continuous operation.
  • the BE sphere of 60 mm diameter consists of the A3 graphite matrix tested in irradiation tests with the composition of 71 wt.% Natural graphite FP 1 18 wt.% Graphitized petroleum coke KRB and 11 wt.% Binder coke.
  • the spherical core of 50 mm diameter contains the fuel in the form of UO 2 coated TRISO particles and is enclosed by a 5 mm thick fuel-free shell.
  • the shell is seamlessly connected to the core and forms a unit with it.
  • the binder coke of the shell is transferred during the vacuum annealing to SiC or ZrC.
  • the heavy metal content of the BE ball is 14g or 23,333 coated particles.
  • the uranium is enriched to 7.8% with U-235.
  • the mean residence time of the BE spheres in the reactor is given as 948.4 days and the mean burnup as 80,090.7 MWd / t.
  • the fuel cores are produced by the grafting process by dripping uranium nitrate casting solutions with additives.
  • the diameter of the sintered U ⁇ 2 fuel cores is 500 ⁇ m with a density of 10.4 g / cm 3 .
  • the starting material is U 3 O 8 .
  • U 3 O 8 it is also possible to produce from UF 6 .
  • To prepare the casting solution U 3 Oe is dissolved in nitric acid (HNO 3 ).
  • the concentration of dissolved uranium is 150g / l_iter.
  • 5 g of polyvinyl alcohol (PVA) and 10 g of tetrahydrofurfuryl alcohol (THFA) are added.
  • the required pH is adjusted by the use of ammonia.
  • the casting solution is dripped at a frequency of 100 Hz with a tenfold nozzle head. Each individual nozzle is controlled by its own mass flow controller.
  • the spherical drops thus formed are first solidified in ammonia solution (NH 4 OH) to form ammonium diuranate (ADU) according to the following equation:
  • the cores are calcined and sintered according to DE 10204166A1.
  • the two processes take place in a cascade rotary kiln.
  • the furnace consists of a double-sided inclined pipe. Inside the tube, crucible fittings (cascades) are integrated.
  • the crucible moldings have openings on both sides for the passage of the particles and are arranged offset one after the other. With one revolution of the tube, the particles move gently in the next located in the flow direction crucible molding (cascade).
  • the bottom residual surface of the crucible molding is slightly more than 50%. It prevents slippage of the particles in the axis of rotation and serves as a radiation shield.
  • the sintered particles are sieved in a drum device and the non-round particles or particles with "noses" on a vibrating plate are separated from the target fraction
  • the proportion of separated particles is relatively low and amounts to about 1% by weight.
  • the coating of the fuel cores with pyrolytic carbon and silicon carbide takes place in fluidized beds. These systems consist of a vertical graphite tube with conical bottom, which is heated from the outside with a graphite resistance heater. In the top of the cone open several nozzles through which the carrier gas required for whirling argon or hydrogen and coating gases are introduced.
  • the Pyrokohlenstoff füren are deposited by thermal decomposition of a mixture consisting of ethyne and propyne at temperatures between 1200 ° C and 1400 0 C.
  • coating with silicon carbide serves as coating gas methyltrichlorosilane. The deposition temperature is slightly higher and is 1500 0 C.
  • the CVD coating system is designed for a working tube with an internal diameter of 170 mm to 400 mm.
  • the reaction and carrier gases are introduced from below into the reaction space via a water-cooled nozzle lance through the conical insert provided with nine bores.
  • the cone geometry, the arrangement of the bores, the bore diameter, the angle of inclination of the bores and the gas flow of the coating gases are coordinated so that a very low vortex height of the particles of less than 500 mm is formed (cone designation K 26 B).
  • K 26 B At a low vortex level, a uniform concentration of the coating achieve gas. This is an important prerequisite for depositing uniform, dense and isotropic layers without soot inclusions.
  • a discharge of the particles is prevented from the reaction tube.
  • the concentration of the reaction gases C 2 H 2 of 54 vol.% And C 3 H 6 of 46 vol.% Allows due to exothermic reaction, a deposition of ILTl and OLTI (Inner Low Temperature Isotropy Layer and Outer Low Temperature Isotropy Layer) at temperatures below 1300 0 C. Consequently, a diffusion of uranium over gas phase in pyrocarbon layers (coating contamination) is avoided.
  • ILTl and OLTI Inner Low Temperature Isotropy Layer and Outer Low Temperature Isotropy Layer
  • the system can be used to control the important process parameters, pressure, gas flows and temperature.
  • the gas flows are controlled electronically by a mass flow controller (MFC).
  • MFC mass flow controller
  • the system is equipped with a menu-driven PC control. Recipient is a double-walled, water-cooled, vertical cylinder.
  • the recipient is designed for a permissible operating pressure of 0 to 1.4 bar and has, in addition to the electrical and cooling connections, all the necessary connections for visual observation and pyrometric temperature measurement in the upper cover flange as well as gas supply and thermocouple feedthrough on the lower cover flange.
  • the gas is supplied via a water-cooled nozzle lance made of stainless steel, which opens conically into the Ausströmboden.
  • the temperature measurement on the system is carried out via four to five measuring ports introduced laterally.
  • Thermocouples, radiation pyrometers or infrared measuring devices can be used here.
  • the two water-cooled lids at the bottom and top are hinged, flanged and can be used for Installation and removal of graphite internals (cone and reaction tube) or to remove particles.
  • the UO 2 fuel cores with a diameter of 0.5 mm and a density of 10.4 g / cm 3 are coated four times, first with a buffer layer of pyrocarbon (thickness 95 .mu.m, density of 1.05 g / cm 3 ), then with a dense pyrocarbon layer (thickness 40 ⁇ m, density 1, 90 g / cm 3 ), then with a dense SiC layer (thickness 35 ⁇ m, density 3.19 g / cm 3 ) and finally with a dense pyrocarbon layer (thickness 40 ⁇ m , Density 1, 90g / cm 3 ).
  • the particles are separated with oversize and undersize, and the particles with geometric densities d ⁇ 2.97 g / cm 3 and d> 3.49 g / cm 3 of the target fraction.
  • the fluids of tetrabromoethane with a density of 2.97 g / cm 3 and barium tetrachloride with a density of 3.49 g / cm 3 can be used in the buoyancy process.
  • the proportion of separated coated particles by sieving and floating is relatively low and is less than 5 wt.%.
  • the graphite press powder consists of:
  • Crystallite size Lc 100 nm, mean grain diameter 10 to 20 ⁇ m, ash content 200 ppm and boron equivalent from the impurities of the ash ⁇ 1 ppm.
  • the natural and electrographic powders are homogenized in a weight ratio of 4: 1 dry in Lödige mixer.
  • the phenolic resin is dissolved in methanol.
  • the weight ratio is resin: methanol
  • the graphite powder mixture and the resin dissolved in the methanol are transferred to the 100 l kneader from Werner and Pfleiderer.
  • the methanol can be replaced by denatured ethanol.
  • the sigma blades of the kneader can be moved in and out. After kneading (1/2 hour right and left 1/2 hour), the kneaded material is forced by extrusion onto a belt dryer and at 105 0 C getrock- net.
  • the evaporated methanol (ethanol) is returned. After drying, the kneaded material is crushed with a hammer mill (sieve setting 1 mm), then homogenized and stored. All devices are explosion-proof and in VA quality.
  • the wrapping of the particles takes place in a rotating drum in the manner of a coating process.
  • the batch size after splitting A is nominally 11,136.36 g UO 2 corresponding to 34,000 g coated particles. These are wrapped in three wrapping batches with 12,000 g graphite powder each.
  • the powdered powder is added to the rolling bed of coated particles, whereby the atomization of alcohol under pressure without the addition of air he follows.
  • the air nozzle diameter is 1, 5 to 2 mm depending on the humidity.
  • the coated particles are dried analogously to the kneaded on a belt dryer at 105 0 C. Subsequently, the non-round particles or twins are separated on a vibrating plate. The coating of the separated particles is removed by washing in methanol, and the recovered particles are returned to the successive batch.
  • the coated coated particles are provided as a multiple of the amount required per ball (14 g of heavy metal) and divided into single portions in a rotating cell storage. Each of the 71 lines can be emptied individually by a bottom flap.
  • the portion divider consists of two cell memories, one of which is in the split position, the other in the allocation position. The portioning process is carried out because it provides a defined number of homogeneous fuel particles and results in a high sum quantity inaccuracy.
  • the graphite press powder for the fuel-containing core is added by weight to a weigh feeder.
  • Enveloped coated particles and graphite press powder fall together in a rotating premixer, which is emptied by reversing the direction of rotation via built-in blades.
  • the production of the particle-containing fuel core takes place on a switching turntable with 8 positions.
  • the rubber mold becomes filling composed.
  • the pressed material falls into the rubber mold in position 10.
  • the rubber mold consists of a lower part and upper part and is surrounded by a steel mold.
  • the steel molds are partially rotatably mounted on the shift turntable. In position 11 to 13, the mold rotates slowly, at the same time a whirl rotating in the opposite direction dives into the mold and produces a homogeneous distribution of the fuel particles in the pressed powder. In positions 11, 12, and 13, the rotary whisker dives on and is folded out in position 13.
  • the rubber mold In position 14, the rubber mold is closed by the rubber cover attached to the hydraulically actuated upper punch of the press and the pressed material is pre-pressed at a pressing pressure of 3 and 10 MPa to a fuel core capable of handling.
  • the lower stamp of the steel mold sits on a ring spring.
  • the lifting height is such that, when compressed, this coincides with the lifting height of the upper punch.
  • the frame of the press is U-shaped and surrounds the shift turntable with the matrices.
  • the mold top of the rubber mold is removed with a vacuum and lifted in position 9 to refill the mold.
  • a Polyp gripper grasps the pre-pressed ball core and raises it. After the upper part has been swung back into position 9 and laid on top, the rubber mold runs in position 10 for refit.
  • the high-pressure press with a press force of about 250 tons consists of an upper and a lower punch and a steel die with 10 cm inner diameter, whereby the two punches are hydraulically driven.
  • ball sockets made of silicone rubber with a detachable button connection are attached.
  • the rubber cups are dimensioned so that with an outer diameter of 10 cm and an adjusted ball cavity of the pressed BE balls of approx. 7 cm are pressed to the final density.
  • the automated pressing of the BE balls takes place in two successive stages, namely a first phase of the pre- and post-pressing, which is followed by a third phase of the final pressing.
  • the ball retainer is made by two steel calottes arranged on the left and right, each with a rubber sleeve. Between the calottes there is a turning tool that can be swiveled through 90 ° with a cutting bit made of diamond, in order to virtually eliminate wear during turning.
  • the balls are first held by vacuum suction in the right dome and half turned off. After the change of position from the right to the left dome, the twisting off of the second ball half takes place.
  • the two calottes and the tool are housed in a Plexiglas box connected to a suction device.
  • the crazy one Material is returned to the graphite powder.
  • the calibration cycle (cycle time / ball) is approx. 20 seconds.
  • the BE-balls for carbonization of the phenol formaldehyde binder resin, the BE-balls in an inert atmosphere, preferably argon in a heated convection oven at about 85O 0 C.
  • the batch size is 1,000 BE balls.
  • the heating and cooling cycle is approx. 11 hours.
  • the Umisselzofen is a cylindrical hood furnace with internal heating.
  • a variable-speed heating gas fan sucks the furnace atmosphere from top to bottom through the ball packing, blowing it upwards through a chrome-nickel heating coil and through the annulus between a guide tube and the furnace shell. All connections and feedthroughs are located on the fixed cooled base plate which also carries the batch table, the heater coil and the cooled fan tray. Insulating hood and recipient do not need any connection cables, they can be removed separately or together freely.
  • the low heat capacity of the high-quality ceramic fiber insulation allows such short cooling times that the furnace can be operated in a 12-hour cycle.
  • the operating voltage of the heater is 50 V, the connected load only 14 KW. Since there are no cold components above the batch table, the batch area remains completely clean during operation and, in contrast to the Dragon and HOBEG coking ovens, free of condensate. The discharge of the cracking products takes place rapidly and practically without secondary pyrolysis.
  • the oven is equipped with six thermocouples and one device each to measure liquid and gaseous cracking products. All measured quantities are converted into electrical signals and registered on a 6-color point recorder. After coking, the BE-spheres in vacuum ( ⁇ 2 mbar ⁇ 10) calcined at about 2000 0 C. The mixed SiÜ 2 reacts with the binder coke selectively to SiC according to DE-102006040309.
  • the annealing takes place in an induction furnace designed for continuous operation.
  • the BE sphere of 60 mm diameter made of A3 graphite matrix consists of a core of 48 mm diameter.
  • the core contains predominantly the breeding substance thorium in the form of TRISO-coated particles and is enclosed by a 3 mm-thick gap-containing layer.
  • the fissile is also in the form of TRISO-coated particles of UO 2 low uranium enrichment or fissile plutonium isotopes.
  • the outer shell of 3 mm thickness is fuel-free and consists of A 3 Graphithmatrix.
  • the binder coke formed during coking is converted to SiC.
  • the void-containing ball core and the fissile-containing layer as well as the fuel-free shell are seamlessly connected to each other by pressing and form a unit.
  • the spherical core contains 31 g of thorium and 1.7 g of uranium as ⁇ U, Th) ⁇ 2 coated particles and the fissile layer contains 4.6 g of uranium as UO2 particles.
  • the core and shell uranium is 17% enriched in U-235. To maintain the negative temperature coefficient, be 27% of U-235 is displaced from the fissile layer into the ball core.
  • the core diameter of the coated UO2 and (U, Th) ⁇ 2 particles is 500 ⁇ m.
  • the particles are coated four times with pyrocarbon and silicon carbide.
  • the number of particles in the fissile layer is 12,180 and in the ball core 68,840, which corresponds to a proven by the manufacture and irradiation volume loading of 35%.
  • the essential feature of the proposed BE-ball is the separate arrangement of the breeding substance in the spherical core and the Spaitschers in the layer.
  • the separate arrangement of fission and breeding material within a sphere and a high ratio of thorium to uranium-235 of about 30 favor the formation of uranium-233 from thorium and the formation of fissile plutonium isotopes from uranium-238.
  • the uranium converted from uranium to uranium-233 is a valuable fissile and is characterized by high ⁇ values. With a 2.21 ⁇ value for uranium-233, it is significantly higher than the ⁇ value of uranium-235 of 1.95.

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Abstract

La présente invention porte sur un élément combustible (BE), qui comprend une matière fissile et une matière fertile, ainsi qu'un procédé pour sa fabrication. L'élément combustible selon l'invention comprend un coeur, une couche entourant le coeur et une coque extérieure, le coeur contenant une matière fertile et la couche qui l'entoure contenant une matière fissile. La présente invention met à disposition des éléments combustibles qui sont caractérisés par le fait qu'ils présentent une longue durée de séjour dans le réacteur.
PCT/EP2010/051136 2009-01-30 2010-02-01 Élément combustible contenant une matière fissile et une matière fertile, ainsi que son procédé de fabrication Ceased WO2010086431A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102009000526.9 2009-01-30
DE102009000526 2009-01-30

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Publication Number Publication Date
WO2010086431A1 true WO2010086431A1 (fr) 2010-08-05

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WO2012075094A3 (fr) * 2010-12-02 2012-12-13 Logos Technologies, Inc. Combustible nucléaire entièrement céramique et procédés associés
US9620248B2 (en) 2011-08-04 2017-04-11 Ultra Safe Nuclear, Inc. Dispersion ceramic micro-encapsulated (DCM) nuclear fuel and related methods
US10109378B2 (en) 2015-07-25 2018-10-23 Ultra Safe Nuclear Corporation Method for fabrication of fully ceramic microencapsulation nuclear fuel
US10573416B2 (en) 2016-03-29 2020-02-25 Ultra Safe Nuclear Corporation Nuclear fuel particle having a pressure vessel comprising layers of pyrolytic graphite and silicon carbide
EP3437108A4 (fr) * 2016-03-29 2020-02-26 Ultra Safe Nuclear Corporation Procédé de traitement rapide de combustibles en boulet de particules triso à matrice de sic et graphitique
CN112678872A (zh) * 2020-11-20 2021-04-20 中核北方核燃料元件有限公司 一种球形燃料元件中铀回收方法
US11101048B2 (en) 2016-03-29 2021-08-24 Ultra Safe Nuclear Corporation Fully ceramic microencapsulated fuel fabricated with burnable poison as sintering aid

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WO2012075094A3 (fr) * 2010-12-02 2012-12-13 Logos Technologies, Inc. Combustible nucléaire entièrement céramique et procédés associés
US9299464B2 (en) 2010-12-02 2016-03-29 Ut-Battelle, Llc Fully ceramic nuclear fuel and related methods
US9620248B2 (en) 2011-08-04 2017-04-11 Ultra Safe Nuclear, Inc. Dispersion ceramic micro-encapsulated (DCM) nuclear fuel and related methods
US10475543B2 (en) 2011-08-04 2019-11-12 Ultra Safe Nuclear Corporation Dispersion ceramic micro-encapsulated (DCM) nuclear fuel and related methods
US10109378B2 (en) 2015-07-25 2018-10-23 Ultra Safe Nuclear Corporation Method for fabrication of fully ceramic microencapsulation nuclear fuel
US10573416B2 (en) 2016-03-29 2020-02-25 Ultra Safe Nuclear Corporation Nuclear fuel particle having a pressure vessel comprising layers of pyrolytic graphite and silicon carbide
EP3437108A4 (fr) * 2016-03-29 2020-02-26 Ultra Safe Nuclear Corporation Procédé de traitement rapide de combustibles en boulet de particules triso à matrice de sic et graphitique
US10878971B2 (en) 2016-03-29 2020-12-29 Ultra Safe Nuclear Corporation Process for rapid processing of SiC and graphitic matrix TRISO-bearing pebble fuels
US11101048B2 (en) 2016-03-29 2021-08-24 Ultra Safe Nuclear Corporation Fully ceramic microencapsulated fuel fabricated with burnable poison as sintering aid
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CN112678872A (zh) * 2020-11-20 2021-04-20 中核北方核燃料元件有限公司 一种球形燃料元件中铀回收方法

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