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WO2000065607A1 - Desactivation de refrigerants metalliques liquides utilises dans des systemes de reacteurs nucleaires - Google Patents

Desactivation de refrigerants metalliques liquides utilises dans des systemes de reacteurs nucleaires Download PDF

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Publication number
WO2000065607A1
WO2000065607A1 PCT/US2000/009084 US0009084W WO0065607A1 WO 2000065607 A1 WO2000065607 A1 WO 2000065607A1 US 0009084 W US0009084 W US 0009084W WO 0065607 A1 WO0065607 A1 WO 0065607A1
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WIPO (PCT)
Prior art keywords
alkali metal
liquid
precipitating agent
alkali
ammonia
Prior art date
Application number
PCT/US2000/009084
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English (en)
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WO2000065607A8 (fr
WO2000065607B1 (fr
Inventor
Gerry D. Getman
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Commodore Applied Technologies, Inc.
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Filing date
Publication date
Priority claimed from US09/542,167 external-priority patent/US6175051B1/en
Application filed by Commodore Applied Technologies, Inc. filed Critical Commodore Applied Technologies, Inc.
Priority to AU43313/00A priority Critical patent/AU4331300A/en
Publication of WO2000065607A1 publication Critical patent/WO2000065607A1/fr
Publication of WO2000065607B1 publication Critical patent/WO2000065607B1/fr
Publication of WO2000065607A8 publication Critical patent/WO2000065607A8/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/04—Chlorides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/12—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions
    • C22B3/14—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions containing ammonia or ammonium salts
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/10—Processing by flocculation
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/28—Treating solids
    • G21F9/30—Processing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • This invention relates generally to remediation of nuclear reactor wastes, and more specifically, to deactivation of metal liquid coolants used for absorbing and transferring heat in nuclear reactors.
  • the site must be decommissioned which includes decontamination, dismantling and demolition with subsequent return to green field status.
  • the first stage in nuclear plant decommissioning is the removal of fuel, followed by the initial wash out of the coolant system and then in situ decontamination for removing residual active species before dismantling the facility.
  • the liquid metal coolant which may be an alkali metal such as sodium or a sodium-potassium alloy, presents unthoughtof problems for disposal.
  • Liquid sodium and/or sodium/potassium alloys are extremely reactive metals subject to highly exothermic reactions with water which may result in the generation of hydrogen gas. Accordingly, when liquid alkali metal coolants are involved in the decommissioning of a nuclear reactor additional precautions must be taken for disposing of the large quantities of alkali metal wastes.
  • liquid metal coolant In a breeder nuclear reactor a liquid metal coolant is used in several different areas but always for its cooling and/or heat transferring capabilities.
  • the core of the reactor which contains the fuel element pins and the uranium-238 blanket surrounding the core are cooled by liquid metal coolant which circulates in two separate and distinct coolant loops, namely the primary and secondary or intermediate loop.
  • the primary and secondary loops are isolated from each other to reduce the transfer of radioactive isotopes between the loops.
  • the primary coolant loop surrounds the fuel core for absorbing heat from fission activity within the core and this coolant may contain radioisotopes of the liquid metal due to absorption of neutrons.
  • the coolant enter the primary loop at about 600 °F and leaves the core at about 900 °F.
  • alkali metal especially sodium bonded fuel found within spent fuel elements must be deactivated.
  • Fuel elements used in breeder reactors include uranium-235 pencil like pellets that are inserted into a thin-walled stainless steel tube. Included in these tubes is a small amount of an alkali metal, such as sodium which functions as a heat-transfer agent. The tube is welded shut and as more and more of the uranium-235 undergoes fission, fissures develop in the fuel allowing the alkali metal to enter the voids. The sodium extracts an important fission product, namely cesium- 137, and hence become intensely radioactive.
  • the liquid alkali metal drained and removed from the coolant system and/or removed from spent fuel elements must be disposed of in a safe and secure manner. However, before final disposal, the alkali metals must be deactivated, especially sodium, to reduce its reactivity.
  • U.S.Pat. No. 4,032,614 discloses a method for contacting molten alkali metal with a caustic solution thereby forming an alkali metal hydroxide.
  • this method is carried out at increased temperatures with a concomitant production of hydrogen gas.
  • the high temperatures used in this process increase the possibility of a hydrogen explosion thereby presenting an additional safety hazard.
  • the method produces large quantities of caustic material which is considered hazardous due to its corrosivity.
  • disposal becomes a problem because the Environmental Protection Agency considers this caustic material as "mixed waste" due to its hazardous characteristics and radioactive content. Accordingly, the caustic material has to be disposed of in a hazardous waste site.
  • this method has the limitation of not being applicable for dissolving and removing any deposited alkali metal remaining on process equipment, tools or in the circuit loops of the reactor.
  • U.S. Pat. No. 5,678,240 overcomes the problems presented when producing alkali metal hydroxides by further converting the caustic waste materials to alkali metal carbonates. This method eliminates the concern for disposal of hazardous corrosive materials but includes several steps that involve the initial conversion to a hydroxide. As such, concerns for generating explosive hydrogen gas is still applicable. Furthermore, this method may not be used for final wash out of a reactor's coolant systems to remove any remaining scale or solids.
  • Precipitating agent means a compound that ionizes in an ammoniacal liquid such as anhydrous liquid ammonia to form an anion that combines with an alkali or alkaline earth metal cation to form a alkali or alkaline earth metal salt.
  • Binder Reactor as used herein means a nuclear reactor wherein the amount of plutonium produced exceeds the amount of plutonium consumed.
  • Precipitating ammoniacal mixture as used herein is a mixture containing a precipitating agent dissolved and ionized in an ammoniacal liquid.
  • Metal coolants as used herein means alkali and alkaline metals and mixtures thereof, either in a liquid or solid state, that have been used as circulating liquid coolant in a nuclear reactor or as heat transfer agents included within fuel element tubes. These metal coolants or heat transfer agents may contain other contaminates such as radioactive materials.
  • Ammoniacal liquid as used herein means solutions having an ammonia content ranging from at least 50 percent-by- weight of ammonia in water to anhydrous liquid ammonia.
  • a still further object of the present invention is to provide a method that not only deactivates liquid alkali metals removed from a breeder reactor but also detoxifies hazardous materials thereby rendering both the liquid alkali metal and hazardous waste as a non- hazardous waste stream.
  • Yet another object of the present invention is to provide a method for deactivation of alkali metals removed from or included within spent fuel elements.
  • a liquid alkali or alkaline earth metal can be deactivated by combining with a precipitating agent, both of which are soluble in liquefied ammonia to form a precipitating compound.
  • a precipitating agent both of which are soluble in liquefied ammonia to form a precipitating compound.
  • sodium and sodium-potassium alloys can be deactivated by contacting the alkali metal with an excess of an ammoniacal liquid such as anhydrous liquid ammonia to form a reaction mixture which when combined with a precipitating agent that substantially dissolves and ionizes in the ammoniacal liquid forms an alkali metal salt precipitate.
  • the reaction mixture comprises a solution of solvated alkali metal cations and electrons that combine with an ionizable compound for precipitating an alkali metal salt.
  • the resulting alkali metal salt precipitate may have a reduced solubility in the ammoniacal liquid when compared to that of the original precipitating agent and alkali metal thereby providing for easy separation of the precipitate from the ammoma solution.
  • the process comprises the step of combining two mixtures, a reaction mixture comprising an alkali metal coolant removed from a reactor, either in solid or liquid form, introduced into a reaction vessel containing an ammoniacal liquid such as anhydrous liquid ammonia wherein the alkali metal is solubilized thereby forming alkali metal cations and solvated electrons.
  • the alkali metal is introduced into the reaction mixture in an amount not exceeding the solubility of the alkali metal in the ammoniacal liquid ammonia.
  • a precipitating ammoniacal mixture comprising a precipitating agent solubilized and/or ionized in anhydrous liquid ammonia is combined in the reaction vessel with the solvated alkali metal cations and electrons.
  • the combining of ions in the reaction vessel forms an alkali metal salt which may be removed from the reaction vessel.
  • the anhydrous liquid ammonia may be evaporated from the reaction vessel and recovered for future use.
  • the processes of the present invention further contemplate in situ deactivation and recovery of solidified metal coolant from surfaces of a reactor coolant system, process equipment, tools and any other surfaces encrusted with solidified alkali or alkaline earth metal.
  • an ammoniacal liquid such as anhydrous liquid ammonia is circulated through the coolant system, that being the primary and secondary loops and any other loops or surfaces exposed to the liquid metal coolant, to dissolve any remaining metal liquid coolant that solidified as a scale and/or became trapped in the coolant system after initial drainage of the molten metal.
  • the anhydrous liquid ammonia is pumped through the coolant system under pressure to maintain the anhydrous ammonia in a liquefied state.
  • the anhydrous liquid ammonia is circulated until a sufficient amount of the solidified metal, such as alkali metal is dissolved in the liquid ammonia and then removed from the coolant system. Upon removal from the system, the ammonia solution comprising solvated alkali metal cations and electrons is combined with a precipitating agent that solubilizes and ionizes in ammoniacal liquid. The combined mixtures effect the precipitation of an alkali metal salt.
  • the final waste product may be an alkali or alkaline earth metal salt which is not considered a hazardous material.
  • liquid alkali metal circulating in the secondary loop of a reactor's cooling system is usually considered non-radioactive, assuming there has not been a leak between the primary and secondary circuit, and the precipitated alkali metal salt can be disposed of in a non-RCRA controlled landfill.
  • the process may be utilized for in situ decontamination which dissolves and removes solidified alkali metal from the coolant system for further treatment with a reagent that yields an alkali metal salt.
  • Yet another advantage of the present process is the substantial reduction of the production of hydrogen gas by selectively choosing a precipitating agent that has a cation or anion that may be reduced in the reaction mixture by solvated electrons.
  • FIG. 1 is a flow diagram of the deactivation process of the present invention showing the system for converting an alkali metal to an alkali metal salt.
  • FIG.2 is an illustration showing the circulating coolant system of a generic breeder reactor.
  • FIG.3 is a schematic diagram of a preferred embodiment of the deactivation of alkali metal coolant according to the present invention.
  • FIG.4 is a reaction plot showing the deactivation of sodium in the presence of liquid ammonia and a precipitating agent.
  • the processes of the present invention are directed to the deactivation of alkali or alkaline earth metal used as liquid coolant and/or heat transfer agents in nuclear reactor systems.
  • sodium will be used as a representative of an alkali metal but this is not intended to be a limitation of the invention.
  • Methods of the present invention can be demonstrated by reference to Figure 1 which teaches that molten sodium can be accumulated in a storage tank 10 at a temperature ranging from about the melting point of 98°C to less than the boiling range of 883 °C to maintain the sodium in a liquid state, and preferably, from about 110°C to 200 °C.
  • the sodium can be pumped from the storage tank 10 or directly from a source such as the primary or secondary coolant system of a breeder reactor.
  • the molten sodium may be injected into a reaction vessel 14 which is charged with an ammoniacal liquid in a sufficient amount to dissolved the injected alkali metal.
  • the reaction vessel is charged with at least a stoichiometric excess (greater than a 1 : 1 mole ratio) of the ammoniacal liquid ammonia to dissolve the alkali metal.
  • the ammoniacal liquid is preferably anhydrous liquid ammonia, but solutions of at least 50 percent-by-weight of ammonia in water can also be employed.
  • the temperature and or pressure in the reaction vessel is controlled to maintain the anhydrous ammonia in a liquefied state.
  • the pressure may range from about 15 psi to about 200 psi.
  • the pressure range will be dependent upon the temperature generated by the reaction within the vessel and whether the vessel is being cooled by an outside cooling system. Accordingly, if the reaction is carried out under normal atmospheric pressure then the temperature should be maintained at or below -30 °C by any means known in the art. Alternatively, if the pressure within the reaction vessel is increased then the temperature may rise above -30°C.
  • the molten sodium may be injected or pumped under pressure into the reaction vessel through nozzle 15 that atomizes the sodium at a controlled rate to facilitate dissolution of sodium in the ammoniacal liquid under stirring conditions.
  • the amount of sodium introduced into the reaction vessel should not exceed the solubility of sodium in anhydrous liquid ammonia at the specific temperature and pressure within the reaction vessel.
  • solvated electrons are chemically generated.
  • the sodium becomes a cation by losing a valence electron as illustrated in the following equation: dissolve in NH3
  • the ammonia molecules of the solvent surround the charged electrons which provide stability so the sodium ions do not react with the solvated electrons. Instead, the sodium ions are free to react and/or combine with a reagent that provides a combinable anion to form a sodium salt precipitate or an easily separated sodium complex.
  • the sodium cations and solvated electrons in the reaction vessel 14 are next introduced and combined with a precipitating agent that upon ionization in the liquid ammonia will provide an anion for combining with the sodium cation to form a salt precipitate.
  • any precipitating agent that ionizes in ammoniacal liquid and provides an anion to combine with the sodium cation for precipitating a sodium salt may be used in the present invention.
  • the precipitating agent is selected from the group consisting of ammonium chloride, water, hydrogen chloride, ammonium nitrate, sodium nitrate, nitric acid, ammonium sulfate, ammonium chromate, ammonium dichromate, ammonium perchlorate, ammonium iodate, ammonium periodate, ammonium benzoate, and metal halides such as zinc halides, copper halides and nickel halides.
  • the precipitating agent is selected from the group including ammonium chloride, copper chloride and ammonium nitrate.
  • the precipitating agent may be solubilized in an ammoniacal liquid in a precipitating agent tank 16 before introduction to the reaction vessel 14.
  • the ionizable precipitating agent is added to the ammoniacal liquid in an amount not exceeding the solubility of the precipitating agent in the liquid ammonia at the specific temperature and pressure within the reaction vessel.
  • the precipitating salt can be removed from the reaction vessel by any means of separation including venting the liquid ammonia, removing the salt from the reaction vessel by filtration, spray drying, and or evaporation.
  • ammonium chloride may cause the production of hydrogen gas an alternative precipitating agent may be utilized, that being a precipitating agent that upon ionization has an anion that can be reduced, such as ammonium nitrate.
  • a solution of anhydrous liquid ammonia containing dissolved ammonium nitrate can form precipitates without the production of hydrogen.
  • the sodium is introduced either directly or indirectly into an ammoniacal solution of ammonium nitrate, the sodium is deactivated without the evolution of hydrogen.
  • the alkali metal sodium is added in an amount to provide sufficient solvated electrons to reduce the anion of the dissolved precipitating agent.
  • the sodium is added in at least a 1 : 1 ratio, and more preferably, sodium and ammonium nitrate react in the approximate ratio of 2:1, a ratio required for the following reaction.
  • the sodium metal is deactivated without the concomitant production of hydrogen gas when an excess of sodium is introduced into the ammonia solution containing ionized ammonium nitrate. It is believed that the solvated electrons formed during the dissolution of the sodium metal act as a powerful reducing agent and are consumed by the reduction of the nitrate anion forming a nitrite wherein the nitrogen atom has a lower oxidation number.
  • precipitating reagents that reduce the production of hydrogen gas when deactivating an alkali metal may include metal halide agents that upon ionization provide a cation that can be reduced, such as copper halides, zinc halides, magnesium halides, cadmium halides and mixtures thereof.
  • metal halide agents that upon ionization provide a cation that can be reduced, such as copper halides, zinc halides, magnesium halides, cadmium halides and mixtures thereof.
  • the metal cation is reduced to a free metal with a concomitant metal replacement reaction forming a metal salt.
  • the free metal acting as a catalyst, will frequently cause the formation of an amide, as a secondary reaction such as shown below:
  • This secondary reaction may be minimized by having a shorter time of reaction, rapid addition of the alkali metal and the use of the alkali metal in only a slight excess over the stoichiometric quantity.
  • anhydrous liquid ammonia can be slowly vented from the reaction vessel to reduce the overall temperature within the reaction vessel.
  • the unvented anhydrous liquid ammonia is allowed to expand slightly in the vessel with a concomitant cooling effect which is transferred to the reaction mixture.
  • This reduction in temperature counteracts any heat generated by the reaction of the precipitating reagent with the sodium cation. Therefore, the formation of a precipitating alkali metal salt may proceed without overheating.
  • a reduced temperature decreases the possibility of an explosion of any hydrogen gas that may form during the reaction.
  • the vented ammonia may be scrubbed in scrubber 18 which will remove any hydrogen gas that may form during the reaction and the cleaned ammoma can be stored in vessel 12 to be reused for recharging of the reaction vessel.
  • the present invention has been described in terms of combining a reaction mixture with a precipitating ammoniacal mixture in a two step batch process, it should be clear that the deactivation methods of the present invention can be performed in a continuous process.
  • the formed precipitate is continuously removed while the reaction vessel is continuously recharged with anhydrous liquid ammonia.
  • the alkali metal and precipitating agent can be introduced in a step process or simultaneously in controlled amounts.
  • the precipitating agent may be added directly to the reaction vessel for ionization in the ammoniacal liquid within the reaction vessel without first being ionized in a separate ammoniacal mixture.
  • the alkali metal may be directly introduced into an ammoniacal liquid which already contains a dissolved precipitating agent.
  • hazardous wastes may be halogenated organics including chemical warfare agents, PCB compounds, highly halogenated toxic waste materials, halogenated insecticides and pesticides and other toxic materials or mixed waste stored on site waiting to be detoxified.
  • Current methods of detoxification include incineration, neutralization and/or chemical processing. However, these methods can produce environmental concerns regarding atmospheric pollution and large quantities of additional waste material.
  • this invention further contemplates processes wherein the solvated electrons generated in the reaction vessel are used to decontaminate hazardous materials.
  • Methods for decontaminating hazardous wastes including halogenated materials, nonradioactive metals or metalloids, and radioactive mixed wastes, using solvated electrons are disclosed in U.S. Patents 4,853,040, 5,495,062 and 5,613,238 all of which are incorporated-by-reference herein. Accordingly, a halogenated hazardous waste material can be detoxified simultaneously with the deactivation of the alkali metal coolant thereby eliminating two different types of hazardous waste material with a single process.
  • the solvated electrons acting as a reducing agent, should be in a sufficient amount to partially or completely dehalogenate a halogenated hazardous waste material to yield a compound(s) of lesser toxicity than the original waste material.
  • the uncombined halogen atoms that are removed from the halogenated compound may be combined with the alkali metal cation in the reaction vessel to form an insoluble alkali metal salt.
  • the detoxified hazardous waste and alkali metal salts are removed from the reaction vessel for disposal.
  • the anhydrous liquid ammonia is vented and scrubbed for possible reuse in the reaction vessel.
  • Methods of the present invention further provide for the deactivation of alkali metal by dissolution of a precipitating agent in an ammoniacal liquid, such as anhydrous liquid ammonia with the subsequent addition of an alkali metal therein.
  • a precipitating agent in an ammoniacal liquid, such as anhydrous liquid ammonia
  • the closed reaction vessel 14 is charged with an excess of anhydrous liquid ammonia and the precipitating agent stored in tank 16 is introduced directly into the liquid ammonia.
  • the precipitating agent is introduced in an amount so as to permit ionization of the agent.
  • an alkali metal from storage tank 10 is introduced and dissolved in the anhydrous liquid ammonia thereby forming solvated electrons and cations.
  • the alkali metal cations may combine with anions of the ionized precipitating agent and form a precipitating alkali metal salt.
  • the precipitating salt may be removed from the reaction vessel or the liquid ammonia may be optionally vented for recovery and reuse.
  • Liquid alkali metal drawn from the primary, intermediate and/or any contaminated circuit of a cooling system, such as in a pool system may initially warrant decontamination to reduce the radioactivity of the alkali metals. The radioactivity may be reduced to unrestricted levels before being treated by the processes of the present invention for final disposal. Molten sodium removed from the primary circulating loop is contaminated with radioactive isotopes such as Na-24 which occurs due to neutron bombardment.
  • the sodium in the primary loop enters the core of the reactor, and therefore, can be contaminated with uranium dioxide and fission products as a result of direct contact with the irradiated uranium dioxide in the core.
  • the precipitated alkali metal salt may be disposed of in a low-level radioactive site where storage is less restrictive and monitoring is reduced because of the removal of any plutonium-239.
  • any method that purifies and/or decontaminates sodium metal may be used as long as the sodium can be maintained in a liquid state or can resume a liquid state for further deactivation by the processes of the present invention.
  • U.S. Pat. No. 3,854,933 discloses a method to remove impurities in metallic sodium, the contents of which are herein incorporated-by-reference. Briefly, calcium and/or magnesium and/or calcium- magnesium alloy are dissolved in the molten metallic sodium at a high temperature from about 450 to 850 °C. Thereafter, these dissolved metals are precipitated at a lower temperature, that being, a little higher than the melting point of sodium (97.5 °C).
  • nuclear fission products comprising elements from the group consisting of O, N, S, Sr, Ba, Sb, Sm, Pr, La, Ce, Ni, Si, Sn, Zn, Tl, Th, Pu, Rh, and Pb are separated from the sodium by chemically bonding with, adsorbing with and/or co-precipitating with the calcium and magnesium additives.
  • Na-24 formed in the molten metal by neutron bombardment is also removed because Na-24 acting as a magnesium atom precipitates when the molten solution is cooled to just above the melting point of sodium.
  • the decontaminated sodium may be introduced directly into the reaction vessel for deactivation and precipitation by the methods of the present invention.
  • the primary and secondary circuit loops of a breeder reactor may be deactivated in situ thereby removing any remaining solidified sodium metal after the bulk of the molten sodium has been drained.
  • Figure 2 illustrates a generic breeder reactor having separate and distinct primary and secondary circulating loops. The engineering design of the vessels and pipelines makes complete drainage of the system impossible, and therefore, the remaining sodium must be removed by other means. More important, by decontaminating the primary loop any radioactive fission products that may have contaminated the sodium in the loop are also removed thereby allowing the metallic hulk of the reactor to be shredded and disposed of as low-level radioactive waste.
  • the processes of the present invention are ideal for decontaminating the coolant circulating loops and removing any remaining metal coolant that has solidified on surfaces or in crevices within the reactor system.
  • the process comprises several steps.
  • anhydrous liquid ammonia is circulated through the circuit loops at a pressure and temperature to maintain the anhydrous ammonia in a liquefied state.
  • the present process exploits the physical dissolution of sodium in liquid ammonia.
  • the anhydrous liquid ammonia is circulated through the system until it becomes saturated with sodium and/or reaches an acceptable level of sodium ions dissolved in the ammoniacal solution and then is removed from the circulating system.
  • ammoniacal liquid containing the dissolved sodium After the ammoniacal liquid containing the dissolved sodium is removed from the system it may be directly introduced into the reaction vessel as shown in Figure 1 for mixing with a precipitating agent.
  • the anhydrous liquid ammonia with the dissolved sodium may be removed and evaporated to recover the sodium.
  • This route may be utilized if the sodium removed from the primary loop must be decontaminated to remove radioactive fission products.
  • the sodium can be reheated and the method discussed above may be used to remove unwanted fission products and the decontaminated sodium may then be deactivated by the processes of the present invention.
  • a 7.0 gram sample of ammonium sulfate was introduced into a 600 ml beaker containing 350 ml of NH 3 under stirring conditions forming a reagent mixture.
  • Sodium was slowly added to the reagent mixture forming a reaction mixture.
  • the addition of sodium precipitated a limited amount of sodium sulfate.
  • the reaction mixture maintained a blue color in the vortex of the stirring mechanism and remained a permanent blue after only 0.59 grams of sodium were added.
  • the reaction mixture containing ammoniacal liquid maintained the expected blue solution due to solvated alkali metal cations and electrons. This example demonstrates that some reagents are more aggressive in precipitating an alkali metal salt and this may be dependent on the solubility of the precipitating agent in liquid ammonia.
  • a closed reaction vessel was charged with approximately 6 liters of liquid anhydrous ammonia.
  • a 60 gram sample of metal sodium was introduced in the reaction vessel.
  • the pressure within the vessel and the conductivity of the reaction mixture were monitored.
  • the conductivity of the reaction mixture increased due to the sodium cations and solvated electrons formed during the solubilizing of sodium in liquid ammonia. This increase in conductivity is shown in Fig. 4 wherein the curve (labeled RxCl) rapidly increases.
  • the pressure in the reaction vessel also increased as shown by the curve (labeled RxPl).
  • the reaction vessel was vented to reduce the pressure with a concomitant reduction in the conductivity of the reaction mixture.
  • a 23 gram sample of metal sodium was introduced into a closable and pressurizable reaction vessel equipped with a stirring mechanism.
  • the reaction vessel was assembled and charged with approximately 1.3 liters of anhydrous liquid ammonia.
  • the solution within the vessel had the typical blue color of a solution containing solvated electrons.
  • the pressure within the vessel was initially about 110 psi which slowly increased to 120 psi with a temperature within the vessel of approximately 21- 22 °C.
  • the temperature was adjusted to approximately 5-6 °C by venting the ammonia to reduce the internal temperature within the reaction vessel.
  • the pressure was reduced to approximately 64 psi.
  • the bottom valve of the hopper was opened and an additional amount of the ammonium nitrate ammoniacal solution was introduced into the reaction vessel.
  • the pressure and temperature in the vessel increased to 190 psi and 26 °C, respectively and the blue color of the solution in the reaction vessel disappeared.
  • the pressure started to decrease within the reaction vessel while the temperature held steady.
  • the pressure was approximately 148 psi and at 6 minutes the pressure was down to 144 psi.
  • Reaction vessel containing sodium in ⁇ o 8 67 liquid anhydrous ammonia
  • a possible explanation for the reduction of pressure within the vessel after the introduction of the ammonium nitrate ammoniacal solution may include the decrease of hydrogen gas produced because the solvated electrons acting as reducing agents are consumed in the reduction of the N0 3 " anion, wherein the N has a +5 oxidation state, to
  • the present process provides a safe and efficient method for deactivating molten alkali metals removed from nuclear reactors by forming an easily disposable alkali metal salt precipitate.
  • a 68 gram sample of copper chloride may be introduced into a closable and pressurizable reaction vessel that is equipped with a stirring mechanism.
  • the reaction vessel is assembled and charged with approximately 3 liters of anhydrous liquid ammonia or a sufficient amount to dissolve and ionize the copper chloride therein and to dissolve the sodium metal that will be introduced subsequent to the addition of copper chloride.
  • the temperature in the vessel may be adjusted to approximately 5-6 °C by venting the ammonia to reduce the internal temperature within the reaction vessel and to maintain the anhydrous liquid ammonia in a liquefied state.
  • the lock hopper is connected to the reaction vessel via a valve.
  • the valve of the hopper is opened allowing the molten sodium metal to be injected or pumped into the reaction vessel.
  • a solution of solvated electrons is formed from the reaction of the liquid ammonia with the sodium metal introduced into the reactor.
  • the addition of the metal may be in a one-time injection or by serial mode of addition
  • the amount of molten sodium pumped into the reaction vessel is a slight amount greater than a stoichiometric amount for the reaction that being approximately twice the moles of the copper chloride according to the following equation:
  • NaCI has a reduced solubility in the ammoniacal liquid when compared to that of the original precipitating agent CllCl 2 and alkali metal Na which will make for easy separation from the ammonia solution.

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  • Geochemistry & Mineralogy (AREA)
  • Environmental & Geological Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Removal Of Specific Substances (AREA)

Abstract

La présente invention concerne la désactivation en toute sécurité de réfrigérants métalliques liquides, tels que les métaux alcalins, utilisés dans des systèmes de réacteurs nucléaires, et leur mise sous forme d'un déchet solide jetable. Le métal (10) alcalin est dissout dans un liquide (14) ammoniacal, tel que l'ammoniac liquide anhydre, afin de former un mélange réactionnel comprenant des cations de métal alcalin et des électrons solvatés. Un agent (16) de précipitation qui s'ionise dans l'ammoniac liquide est introduit dans le mélange réactionnel afin de se combiner avec les cations de métal alcalin et/ou les électrons solvatés et former ainsi un sel de métal alcalin précipitant. En outre, il est possible de dissoudre le métal alcalin solide restant dans le système réfrigérant, après vidange initiale de ce métal, par circulation de liquide ammoniacal dans le système réfrigérant. La récupération de l'ammoniac liquide contenant le métal alcalin dissout est suivie de l'addition d'un agent de précipitation ionisable afin de former un sel de métal alcalin.
PCT/US2000/009084 1999-04-26 2000-04-05 Desactivation de refrigerants metalliques liquides utilises dans des systemes de reacteurs nucleaires WO2000065607A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU43313/00A AU4331300A (en) 1999-04-26 2000-04-05 Deactivation of metal liquid coolants used in nuclear reactor systems

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US13108099P 1999-04-26 1999-04-26
US60/131,080 1999-04-26
US09/542,167 US6175051B1 (en) 2000-04-04 2000-04-04 Deactivation of metal liquid coolants used in nuclear reactor systems
US09/542,167 2000-04-04

Publications (3)

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WO2000065607A1 true WO2000065607A1 (fr) 2000-11-02
WO2000065607B1 WO2000065607B1 (fr) 2000-12-21
WO2000065607A8 WO2000065607A8 (fr) 2001-06-21

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112810824A (zh) * 2019-11-15 2021-05-18 通用电气公司 用于冷却高速交通工具的前缘的系统和方法
RU2794139C1 (ru) * 2021-12-29 2023-04-11 Акционерное общество "Государственный научный центр Российской Федерации - Физико-энергетический институт имени А.И. Лейпунского" Способ перевода оборудования с недренируемыми остатками щелочного металла во взрывопожаробезопасное состояние и устройство его осуществления

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4853040A (en) * 1987-03-30 1989-08-01 A. L. Sandpiper Corporation Processes for decontaminating polluted substrates
US5613238A (en) * 1994-09-12 1997-03-18 Commodore Applied Technologies, Inc. Methods of decontaminating soils containing hazardous metals
US6049021A (en) * 1999-02-11 2000-04-11 Commodore Applied Technologies, Inc. Method for remediating sites contaminated with toxic waste

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4853040A (en) * 1987-03-30 1989-08-01 A. L. Sandpiper Corporation Processes for decontaminating polluted substrates
US5613238A (en) * 1994-09-12 1997-03-18 Commodore Applied Technologies, Inc. Methods of decontaminating soils containing hazardous metals
US6049021A (en) * 1999-02-11 2000-04-11 Commodore Applied Technologies, Inc. Method for remediating sites contaminated with toxic waste

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112810824A (zh) * 2019-11-15 2021-05-18 通用电气公司 用于冷却高速交通工具的前缘的系统和方法
CN112810824B (zh) * 2019-11-15 2023-04-07 通用电气公司 用于冷却高速交通工具的前缘的系统和方法
RU2794139C1 (ru) * 2021-12-29 2023-04-11 Акционерное общество "Государственный научный центр Российской Федерации - Физико-энергетический институт имени А.И. Лейпунского" Способ перевода оборудования с недренируемыми остатками щелочного металла во взрывопожаробезопасное состояние и устройство его осуществления

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WO2000065607A8 (fr) 2001-06-21
WO2000065607B1 (fr) 2000-12-21

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