Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G43/00—Compounds of uranium
  • C01G43/01—Oxides; Hydroxides
  • C01G43/025—Uranium dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
  • B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
  • B01J2/06—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a liquid medium
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F15/00—Compounds of thorium
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G56/00—Compounds of transuranic elements
  • C01G56/004—Compounds of plutonium
  • C01G56/005—Oxides; Hydroxides
• • 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
• • 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
• • 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

Definitions

• the invention relates to a process for the production of spherical fuel or Hutzstoffp firmwaren from an oxide of the group of heavy metals uranium, thorium, plutonium or mixtures thereof comprising the steps of preparing a starting solution of the nitrates of at least one of the heavy metals, adding a first reagent from the group Urea and / or ammonium carbonate and / or ammonium bicarbonate and / or ammonium cyanate and / or biuret, adding at least one second reagent in the form of PVA and / or THFA to adjust the viscosity of the solution, dripping the solution into microspheres, at least superficial solidifying the Microspheres in an ammonia-containing atmosphere, collecting the microspheres in an ammonia-containing solution and then washing, drying and thermal treatment.
• graphitic fuel elements in different geometrical configurations are usually used.
• the actual fuel or breeding substance uranium, thorium or plutonium
• uranium, thorium or plutonium is present in it in the form of coated particles.
• the pure oxide spheres are called kernels in nuclear technology or kernels in the English-speaking world.
• the cores are usually prepared from the corresponding nitric acid solutions: the low-viscosity nitrate solutions are converted into highly viscous solutions, which can be dripped into ideally round drops, and then converted into solid gel beads by chemical reaction. Called gel method.
• the reagent of choice for the reaction to the solid is ammonia: uranium reacts to form ADU (ammonium diuranate), thorium and plutonium to the hydroxide. So far, two methods have been used to make these cores:
• External gelation processes drop relatively low concentration (about 100 g U / l) solutions in an ammonia atmosphere, catch the resulting beads in an ammonia solution, allow them to age (to react with ADU or hydroxides), wash first with ammonia-containing water, but then with a water-miscible organic solvent such as isopropanol or another alcohol
• the first wash, with water serves to remove by-products of the reaction, such as ammonium nitrate and also the added THFA (tetrahydrofurfuryl)
• the second wash, with isopropanol is to remove the water from the cores, and the wash must even be carried out with absolute isopropanol, which is particularly laborious since the reprocessing of the isopropanol is beyond the azeotrope for recrystallization Only anhydrous cores can then be further processed without being damaged dry Cores are calcined to remove the contained organic matter, reduced and finally sintered to the UO 2 core.
• DE-B-20 37 232, DE-B-15 92 477, DE-B-18 17 092 are known as prior art in which corresponding methods are described.
• DE-B-24 59 445 provides in that an aqueous suspension of uranyl nitrate, polyvinyl alcohol (PVA), urea and carbon black is dripped.
• DE-A-19 60 289 uses an aqueous solution of uranyl nitrate and urea, the hexamethylenetetramine in a temperature range between 0 0 C and 10 0 C is added to obtain a stable solution. The stable solution is dripped by means of a cooled to 5 0 C nozzle in paraffin oil. From the Journal of Nuclear Science and Technology, Vol. 41, no. 9, p. 943-948 (September 2004) "Preparation Of UO 2 Kernels For HTR-10 Fuel Elements" discloses a method of producing fuel particles after which urea / oxide solution is added prior to adding PVA and THFA urea
• the object of the present invention is to develop a process which retains the known good properties of fuel or hull cores, which are produced by the solution / gel process, but dispenses with the use of problematic organic substances. Also, a concentrated solution of water-soluble complex cations of heavy metals is to be provided to allow easy further processing while avoiding the disadvantages inherent in the prior art. It should easily be made a stable solution that is to drip.
• the second reagent is added to the solution at room temperature, the second reagent should be dissolved in solid form to avoid dilution of the solution.
• the starting solution provided with the dissolved first reagent is heated at an elevated temperature in the range preferably between 80 ° C. and 100 ° C., in particular in the range from 90 ° C., and over several hours, preferably 3 to 6 Hours kept at this temperature, the solution remains stable, but at the same time the decomposition of the first Reagenzie and the removal of the excess of water takes place and at the same time a concentrated solution of water-soluble complex cations of heavy metals is formed, which can then be solidified after the addition of the second Reagenzie after the gel precipitation s process in an ammonia-containing atmosphere into beads, wherein in the subsequent treatment of the washed Globules the use of an alcohol such as isopropanol is not required.
• the starting solution itself should be a 1 to 2.5 molar nitrate solution.
• urea or an equivalent first reagent is added to the starting solution at room temperature, in particular as a solid, in order to avoid dilution of the solution.
• the solution thus prepared is then heated to a temperature below the boiling point, preferably in the range between 80 0 C and 100 0 C, in particular of about 90 0 C over a period of between 3 and 6 hours, preferably in about 4 hours, the Decomposition of the urea or the equivalent first reagent and the removal of the excess of water leads to a concentrated solution of water-soluble complex cations of heavy metals.
• PVA and / or THFA as the second reagent beads are then prepared by the gel precipitation method, which are post-treated in a known manner while avoiding alcohol.
• the casting solution that is, the solution adjusted to a desired viscosity, dripped into microspheres in vibration nozzles, the microspheres solidified in an ammonia atmosphere on the surface, then collected in aqueous ammonia solution, in which they are aged. At- Finally, the microspheres are washed, dried, calcined and finally reduced to the desired cores and sintered.
• the solution is prepared without the use of hexamethylenetetramine and thus no cooling below room temperature is required.
• a casting solution is prepared, as is known per se for the known "external gelation", but the first reagent is added for the internal release of ammonia upon increasing the temperature
• the first reagent such as urea
• This solution can then be dripped into relatively small droplets, the droplets are gelled in an ammonia atmosphere, then aged at elevated temperature in ammonia solution, washed with water, dried, calcined and sintered to specification-compliant UO 2 cores.
• a solution of the corresponding heavy metal nitrates with urea or equivalent first reagent, the or . which dissociates ammonia in the heat and thereby reacts as precipitant, and mix additives for adjusting the viscosity, dribble this solution, superficially solidify the resulting beads in an ammonia atmosphere, further solidify the beads in an ammonia solution under elevated temperature, they only with water. Do not wash with water, dry, calcine and finally sinter to the final product with organic solvents.
• the solution PVA and THFA in the ratio of about 1:10 is added, in particular about 50 g / kgU PVA and about 500 g / kgU of THFA.
• the fresh cores are transferred with the Klallaimssstrom in the container for aging, washing, drying and aged here for several hours at about 60 0 C, then washed at about 6O 0 C several times with water, and finally up to 8O 0 C dried under vacuum.
• the dried cores are first calcined in corresponding ovens under air for a special temperature program between 100 0 C and 500 0 C to UO 3 , then under hydrogen at 600 0 C - 700 0 C and then at 165O 0 C to UO 2 cores reduced and sintered.
• UO 2 cores can be provided with over 90% yield for further processing with the properties shown in the following table:
• this solution is heated to about 90 0 C and kept at this temperature for 4 hours. Subsequently, the hot solution is cooled to room temperature and used for the production of casting solution.
• the volume is 8.1 1/4 kgU, corresponding to a U content of 494 g / l and a density of approximately 1.6 g / ml.
• polyvinyl alcohol (PVA) is used, among other things, to increase the viscosity. By dissolving PVA in ultrapure water, a 10 weight percent PVA solution is prepared, with a density of 1.022 g / ml.
• the volume of this casting solution is 12.0 1 and the weight 17.3 kg.
• the U content is 231 g / kg solution and the viscosity in the range 55 to 80 mPa ⁇ s.
• the casting solution is divided in a known manner by means of 5 flow meters and a 5-nozzle vibrator system at a frequency of 100 hertz in uniform drops, which harden after formation of the spherical shape in ammonia gas and then in 5 to 12 molar ammonia solution as a spherical Particles are collected from ammonium diuranate.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Inorganic Chemistry (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Ceramic Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=39877299

Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (11)

Family Cites Families (8)

• 2007
  • 2007-08-08 DE DE102007037473A patent/DE102007037473A1/de not_active Withdrawn
• 2008
  • 2008-05-20 EP EP08759783A patent/EP2160358A1/de not_active Withdrawn
  • 2008-05-20 KR KR1020097026931A patent/KR101378729B1/ko active Active
  • 2008-05-20 US US12/600,509 patent/US8535579B2/en active Active
  • 2008-05-20 RU RU2009148048/05A patent/RU2459766C2/ru active
  • 2008-05-20 WO PCT/EP2008/056169 patent/WO2008142072A1/de not_active Ceased
  • 2008-05-20 JP JP2010508824A patent/JP5657381B2/ja active Active
• 2009
  • 2009-12-18 ZA ZA2009/09029A patent/ZA200909029B/en unknown

Also Published As

Similar Documents

Legal Events