Classifications

• • 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
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
  • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
  • C01B3/06—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen with inorganic reducing agents
  • C01B3/08—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen with inorganic reducing agents by reaction of inorganic compounds with metals
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D1/00—Oxides or hydroxides of sodium, potassium or alkali metals in general
  • C01D1/04—Hydroxides
• • 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
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• • 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
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/10—Process efficiency
  • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Definitions

• the field of the invention is that of sodium treatment processes, particularly necessary during plant treatment operations comprising elements wet with sodium, used for example as heat transfer fluid.
• FIG. 1 extracted from the file CLEFS CEA - No. 55 - SUMMER 2007 schematizes this type of reactor comprising a core 1 comprising the fuel, coupled to control rods 2 (a control bar being a "moving part" of neutron-absorbing material, used to reduce the multiplication factor of neutrons and thus to control chain reactions).
• the reactor also comprises a hot plenum 3 and a cold plenum 4 representing the feed chambers (or tank) (or intake) respectively filled with hot primary sodium (near the core 1) and cold primary sodium.
• the core corresponds to the region where the chain reactions are maintained, and includes the fuel that contains the energetic fissile materials (heavy nuclei) as well as fertile materials that, under the action of neutrons, will be transformed. partially.
• the fuel can take different forms (pellets, balls, particles) and the fuel elements can be gathered in pencils, needles or plates, themselves joined together.
• the reference process requires two ways to be used, depending on the type of assembly: the "spray” route, for the majority of the assemblies, and the “slow immersion” route, for certain types of assemblies.
• the "sprinkling" route implements a progressive treatment in several stages:
• the dissolution phase of the carbonates by complete immersion of the component to be treated. All the sodium having been treated, the immersion of the assembly is carried out rapidly at a speed of between 60 and 1200 cm / minute; the final rinsing phase carried out by a recirculation of water in the washing well. The assembly is continuously cooled by water.
• This type of process has shown its effectiveness in treating residual sodium in the form of films. It requires a geometry favorable to the flow of the reactive gas mixture to prevent coalescence and / or condensation of water on the structures. Indeed, these phenomena can lead to the accumulation of liquid water which is to be avoided to avoid any reaction sodium - violent water.
• the "slow immersion" route has been developed specifically for this type of assembly in which sodium clusters can also form: the neutralization phase has been removed and replaced by a slow immersion step in pure water .
• the immersion rate should not be greater than 2 cm / minute to avoid any violent reactions of sodium with water. All operations represent a significantly longer duration of about 12 hours.
• This type of process is effective for treating residual sodium present in the form of films and sodium clusters. Because of this, it is much more flexible. On the other hand, it requires a low immersion rate to avoid any damage to the structures caused by a violent sodium-water reaction. It requires good control of this speed. According to the constraints of the Superphénix plant, the immersion velocities are incompatible with the treatment of fuel assemblies with residual powers greater than about 1 kW.
• the Applicant proposes a sodium treatment method for performing a washing operation comprising immersing the sodium in a solution comprising constituents for reducing the reaction rate of sodium with water and thus the speed of the reaction. release of the energy of the reaction, therefore the value of the associated overpressure peak. By reducing the phenomenon of occurrence of surge peak, it then becomes possible to increase the immersion rate and therefore the treatment, especially in the case of the aforementioned assemblies.
• the present invention proposes to proceed with the immersion of sodium in an aqueous monophasic medium comprising particular constituents.
• the present invention thus relates to a sodium treatment process by immersion in an aqueous salt solution, characterized in that said solution is a solution of carboxylate salt or amino-carboxylate salt.
• said solution is an acetate salt solution.
• said solution is a solution of lithium acetate salt, or sodium acetate, or potassium acetate.
• the solution when the solution is an acetate salt solution, its concentration may be less than or equal to 3 mol / L.
• the salt solution is a solution of amino-carboxylate salt which may be a solution of ethylene diamine. Tetra-tetra-sodium acetate.
• amino-carboxylate salts EDTA
• RSE Sodium Water
• the subject of the invention is also a method for washing a sodium wetted element, characterized in that it comprises the sodium treatment method according to the invention and comprising the immersion of said sodium-wetted element in said sodium salt solution.
• carboxylate or amino carboxylate salt is also a method for washing a sodium wetted element, characterized in that it comprises the sodium treatment method according to the invention and comprising the immersion of said sodium-wetted element in said sodium salt solution.
• the sodium-wetted element is an element present in a nuclear reactor with a sodium heat transfer fluid, or in a sodium treatment plant, said element possibly being an intermediate heat exchanger, a pump, or a tank, a tank, an external storage compartment.
• the subject of the invention is also a process for washing a nuclear reactor fuel assembly using sodium heat transfer fluid, and comprising the sodium treatment method according to the invention.
• the washing process of said assembly comprises the following steps:
• the container is a wash well.
• the washing process of said assembly comprises a prior temperature adjustment step of said assembly introduced into said container, before the injection of said solution.
• the temperature adjustment step is performed by a scan of cooling gas may be nitrogen, introduced into said container.
• the washing process of said assembly comprises a water-washing step, said assembly and said container, subsequent to the step of circulating said solution in said container.
• the washing method comprises a drying step subsequent to said water-washing step, said assembly and said container.
• FIG. 1 schematizes a fast neutron nuclear reactor
• FIGS. 2a and 2b illustrate the differences in behavior in terms of relative dynamic pressure as a function of time, during the treatment of sodium respectively with a solution of pure water and with a solution comprising a lithium acetate salt;
• FIG. 3 illustrates a device making it possible to carry out measurements for monitoring the sodium-water reaction such as those represented in FIGS. 2a and 2b.
• the method of treating sodium with a solution containing a certain type of salt makes it possible to reduce the rate of release of the energy of the reaction (1) presented above.
• the Applicant has indeed found that the addition of carboxylate salt or amino-carboxylate salt in water reduces the reaction rate with water and thus the rate of release of the energy of the reaction , therefore the value of the associated dynamic overpressure peak.
• FIGS. 2a and 2b illustrate the differences in behavior in terms of relative dynamic pressure as a function of time, of sodium treatment respectively with a solution of pure water and with a solution comprising a lithium acetate salt.
• FIG. 3 illustrates a device developed by the Applicant making it possible to follow the Sodium-Water Reaction (RSE) and to perform the relative dynamic pressure measurements illustrated in FIGS. 2a and 2b. More specifically, this device comprises a basket containing sodium 10: this basket is formed by a small cage disposed at the end of a rod, which allows to quickly dive a sodium sample of controlled weight and shape within the solution of aqueous salt and maintain the sodium within the aqueous salt solution. A manometer 11 is provided for carrying out pressure measurements. The aqueous solution with or without salts is introduced before the test in a chemical reactor 13, coupled to a magnetic stirrer 14 to ensure a good homogeneity of said solution.
• RSE Sodium-Water Reaction
• inlet / outlet of inert gas 12 in order to allow analysis of the gases at the outlet.
• inert gas 12 in order to allow analysis of the gases at the outlet.
• heat transfer fluid sodium it becomes particularly interesting to exploit the phenomenon described above to treat the sodium adherent to the walls of the assemblies, or more generally elements other than assemblies wetted with sodium, with aqueous solutions containing the salts of the present invention. More generally, the process of the present invention thus makes it possible to treat both films and sodium clusters for the washing of elements coated with sodium.
• salt solutions used can be solutions:
• lithium acetate or potassium or sodium acetate with concentrations preferably of less than 3 mol / L;
• amino carboxylate of which tetrasodium ethylene diamine tetraacetate with a concentration of preferably less than 0.1 mol / l.
• the sodium treatment method according to the invention thus makes it possible to obtain the following positive effects:
• the present invention makes it possible in this context to minimize the handling times and therefore to increase the availability of the reactor, and / or to minimize the investment of the reactor by reducing the number of wells required for washing. It also increases safety, since it is no longer necessary to strictly control a speed of immersion.
• the invention is described in more detail, hereinafter in the case of washing a fuel assembly but can be applied equally to any other element having been wetted with sodium which it is sought to eliminate.
• a first step we proceed to the introduction of the assembly in a washing well, then it is proceeded to the closure of said wash well, before conducting a well leak test.
• inert gas which may be N 2 nitrogen
• a cooling operation of the assembly is carried out.
• the assembly is swept with nitrogen in order to cool it by forced convection to a temperature of about 150 ° C.
• the pump is started up to inject the saline solution into the washing well.
• the treatment is monitored by hygrometric parameters, hydrogen produced and the temperature of the gaseous effluents.
• the saline solution has been prepared beforehand in a so-called treatment tank whose capacity is sufficient to immerse the assembly at one time.
• the temperature used is about 20 ° C.
• the selected salt is dissolved in the tank water by means of an efficient mixing system.
• a volume of approximately 0.5 m 3 of 3M sodium acetate solution a mass of approximately 123 kg is continuously introduced into the stirred tank.
• the saline solution is circulated by means of a dedicated pump until the evolution of hydrogen is zero.
• an emptying operation of the washing well is carried out to a liquid effluent reservoir provided for this purpose.
• a rinsing operation is carried out on the assembly and the washing well. To carry out this operation, the well is immersed in pure water with velocities of between 600 and 1200 cm. min- 1, then a recirculation operation is carried out It should be noted that in order to minimize the liquid effluents generated by the installation, the rinsing water can be used for the treatment phase of the next assembly. The rinsing efficiency can be followed by a measurement of conductivity in the liquid effluents.
• the well is drained to the so-called treatment tank.
• a well drying operation and cooling of the assembly before evacuation by dry nitrogen sweep are carried out: the operation is followed by a measurement of hygrometry.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Health & Medical Sciences (AREA)
• Combustion & Propulsion (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Cleaning In General (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=50976766

Family Applications (1)

Country Status (5)

Citations (3)

Family Cites Families (11)

• 2014
  • 2014-01-22 FR FR1450520A patent/FR3016537B1/fr not_active Expired - Fee Related
• 2015
  • 2015-01-21 WO PCT/EP2015/051158 patent/WO2015110480A1/fr not_active Ceased
  • 2015-01-21 RU RU2016133261A patent/RU2682639C2/ru active
  • 2015-01-21 JP JP2016537490A patent/JP6599866B2/ja active Active
  • 2015-01-21 EP EP15704470.2A patent/EP3097049B1/fr active Active

Patent Citations (3)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events