BE1030063B1 - Molybdenum-99 production process - Google Patents

Abstract

The present invention relates to a method for producing molybdenum-99 comprising the following steps: Step 1: providing a basic suspension comprising at least one liquid phase comprising at least ions of molybdenum-99 and ions of radionuclides of iodine and at least one solid phase comprising at least uranium; Step 2: separation of the solid phase from the liquid phase of said basic suspension; Step 3: purification of said liquid phase by a process of adsorption of at least a portion of the iodine radionuclide ions to produce a purified liquid phase comprising at least the molybdenum-99 ions and whose ion content of iodine radionuclides is reduced by at least 90%, preferably 95%, more preferably 97%, relative to the iodine radionuclide ion content in the liquid phase before step 3, the process further comprising adding a reducing agent to said basic suspension before step 2 and/or treating said solid phase obtained in step 2 with a reducing agent so as to obtain a solid phase whose content of Iodine radionuclide ions is reduced compared to the iodine radionuclide ion content in the solid phase without addition of the reducing agent.

Description

“Production process of Molybdenum-99"

Field of invention

The present invention relates to a process for the production of molybdenum-99.

State of the art

The use of radioactive isotopes, also called radionuclides or radioisotopes, is widespread in the medical field of diagnosis and therapy.

Due to the generally short half-life of the radionuclides used in the field of medical imaging, the radionuclide of interest is generally delivered to the practitioner in the form of its parent radionuclide, with a longer half-life, which is adsorbed on an adsorbent material.

Of the wide range of radionuclides available, technetium-99m (TC), with a half-life of about 6 hours, is the most common. ®"Tc is obtained from the decay of molybdenum-99 (°°Mo), its parent radionuclide, with a half-life of approximately 66 hours. It is common to use a 99Mo/ 99"Tc then comprising a chromatographic column in which the °9Mo is adsorbed on a sorbent. °’Mo disintegrates spontaneously into ®"Tc, the latter being specifically eluted, generally by a saline solution, by difference in affinity between 99Mo and 99"Tc with respect to the sorbent.

The °°Mo currently used generally results from the fission of uranium 235 (SU). In general, highly enriched uranium (in English HEU for High

Enriched Uranium) or weakly enriched (in English LEU for Low Enriched Uranium) in uranium-235 is mixed with aluminum to be packaged in the form of a target.

The target is then irradiated by neutrons so as to split the uranium-235 into lower mass elements, which are themselves unstable and generate, via a decay chain, other radionuclides such as molybdenum-99, iodine-131 and xenon-133. J. Salaz (J. Salaz, Revue IRE Tijdschrift, Vol. 9, N° 3 (1985) “Reprocessing of irradiated Uranium 235 for the production of Mo-99, I-131, Xe- 133 radioisotopes”) has developed a process production of Mo-99 from highly enriched uranium targets. This process makes it possible to produce Mo-99, II-131 and Xe-133 at the same time. The process comprises providing a basic suspension comprising in the liquid phase iodine-131 in the form of iodide, I” and molybdenum in the form of MoO4*. Uranium and a large part of fission products in the form of hydroxides are found in the form of a precipitate. The process then includes a filtration step to separate the precipitate (also called cake) so as to recover unfissioned uranium. Acidification of the filtrate then makes it possible to eliminate iodide in the form of gas and to recover the Mo-99 in ionic form in the acidified filtrate. In this process, iodine-131 is recovered in gaseous form, which requires additional recovery means and is a disadvantage for the safety of the process. Moreover, this method does not make it possible to treat a sufficient number of targets for production of Mo-99 on a larger scale.

Document EP 3 264 420 A1 aims to use targets containing low-enriched uranium to produce a fraction containing a radioisotope of

Mo-99. The process described in this document provides for obtaining a basic slurry containing aluminum salts, uranium and isotopes resulting from the fission of enriched uranium and a gaseous phase of Xe-133. The basic slurry is then filtered in order to isolate on the one hand a solid phase containing uranium and on the other hand a basic solution of molybdate and iodine salts. Then follows an acidification of said basic molybdate solution before or after elimination of iodine. Therefore, if the acidification step is carried out before the iodine removal step, the latter passes into the gaseous phase and must be captured, thus requiring additional radioactive gas handling which can affect the safety of the process. . This process also provides for an additional step of adding alkaline earth nitrate before the filtration step. This step greatly increases the amount of waste generated and more complex contaminants to remove and does not allow for the production of Mo-99 on a larger scale.

The demand for radionuclides being constantly increasing, there is therefore a continuous need for a process for the production of Mo-99 on a larger scale which makes it possible to respect the high level of purity required in the medical field while limiting the safety problems of the process. .

Summary of the invention

The inventors have surprisingly found that it is possible to provide a method for producing molybdenum-99 that meets the above needs.

The subject of the present invention is therefore a method for producing molybdenum-99 comprising the following steps:

Step 1: supply of a basic suspension comprising at least one liquid phase comprising at least molybdenum-99 ions and iodine radionuclide ions and at least one solid phase comprising at least uranium;

Step 2: separation of the solid phase from the liquid phase of said basic suspension;

Step 3: purification of said liquid phase by a process of adsorption of at least a portion of the iodine radionuclide ions to produce a purified liquid phase comprising at least the molybdenum-99 ions and whose ion content of iodine radionuclides is reduced by at least 90%, preferably 95%, more preferably 97%, relative to the content of iodine radionuclides ions in the liquid phase before step 3, characterized by adding a reducing agent to said basic suspension before step 2 and/or treating said solid phase obtained in step 2 with a reducing agent so as to obtain a solid phase whose radionuclide ion content of iodine is reduced compared to the radionuclide ion content of iodine in the solid phase without addition of the reducing agent.

Detailed description of the invention

In the context of the present invention, the term "comprising" is inclusive or open-ended and does not exclude other non-recited elements, process steps or compositional components. This term should be interpreted as specifying the presence of the characteristics, values, stages or components referring to it, but does not exclude the presence or addition of one or more characteristics, values, stages or components. Therefore, the scope of the expression "a process comprising a step A and B" should not be limited to a process consisting only of steps A and B. This means that the only relevant steps are A and B. Therefore, the term "comprising" includes the more restrictive terms "consisting essentially of" and "consisting of".

In the context of the present invention, the term “molybdenum-99” or “99Mo” is used interchangeably and corresponds to the molybdenum radionuclide having a number of nucleons of 99.

Step 1 of supplying a basic suspension

According to the present invention, the method comprises a step 1 of supplying a basic suspension comprising at least one liquid phase comprising at least molybdenum-99 ions and iodine radionuclide ions and at least one solid phase comprising at least less uranium.

In other words, the liquid phase of the basic suspension as defined according to the present invention therefore comprises at least molybdenum-99 ions and iodine radionuclide ions.

In particular, the molybdenum-99 ions included in the liquid phase of the basic suspension are molybdate ions. The latter can occur in different forms, which strongly depend on the conditions of the basic suspension such as the pH and can, for example, occur in the form of oxyanions such as, for example, MoOa4?, [Mo:07]7 , [MosO:9]?, [Mo7O24]6, [MosO26]* or their combination.

In general, the iodine radionuclides included in the liquid phase of the basic suspension according to the present invention are the radioactive isotopes of iodine and can be, for example, iodine-131, iodine-132 and iodine. iodine-133.

Advantageously, the iodine radionuclide ions are in the form of ions chosen from the group consisting of iodides, iodates, periodates or their combination.

It is understood that the liquid phase may also include fission products of uranium-235 soluble in the basic suspension.

According to the present invention, the basic suspension also comprises at least one solid phase comprising at least uranium.

It is therefore understood that, in the context of the present invention, the basic suspension comprises a phase which is in the form of a solid dispersed in the liquid phase of the basic suspension.

It is understood that the solid phase includes at least uranium and may include fission products of uranium-235.

Uranium can be in different forms and can, for example, be in the form of sodium di-uranate Na2U2O; at least a part of which is insoluble in the basic suspension.

The basic suspension according to the present invention can come from any means known to those skilled in the art and can be obtained, for example, from a dissolution of a previously irradiated uranium target (also called "target ").

Advantageously, according to the present invention, said basic suspension is obtained by dissolving the targets with at least one aqueous solution comprising at least one base (basic solution).

In particular, the basic solution used during dissolution is chosen to obtain a basic suspension in which at least molybdenum-99 ions and iodine radionuclide ions are soluble (liquid phase) and at least a part of uranium is insoluble (solid phase).

Preferably, the basic solution further comprises a nitrate.

The basic solution according to the present invention can be produced by any means known to those skilled in the art and can be obtained, for example, by mixing a first aqueous solution comprising at least one base with a second aqueous solution comprising at least a nitrate.

In general, the base is for example an alkaline hydroxide or an alkaline-earth hydroxide, preferably an alkaline hydroxide. The alkaline hydroxide can, for example, be lithium hydroxide, sodium hydroxide, potassium hydroxide or their combination, preferably sodium hydroxide.

Advantageously, said base is present in the first aqueous solution at a concentration greater than or equal to 3.5 mol/l, preferably greater than or equal to 5.0 mol/l, more preferably greater than or equal to 6.0 mol .

Advantageously, said base is present in the first aqueous solution at a concentration less than or equal to 10.0 mol/| preferably less than or equal to 9.0 mol/l, more preferably less than or equal to 8.5 mol/l.

Advantageously, said base is present in the first aqueous solution at a concentration of between 3.5 and 10.0 mol, preferably between 5.0 and 9.0 mol/, more preferably between 6.0 and 8 .5 mol/l.

Advantageously, the nitrate is an alkali metal nitrate or an alkaline-earth nitrate or an ammonium nitrate or their combination, preferably an alkali metal nitrate. The alkali metal nitrate can, for example, be lithium nitrate, sodium nitrate, potassium nitrate or their combination, preferably sodium nitrate.

Advantageously, the nitrate is present in the second aqueous solution at a concentration greater than or equal to 1.0 mol/, preferably greater than or equal to 1.2 mol/l, more preferably greater than or equal to 1.5 mol.

Advantageously, the nitrate is present in the second aqueous solution at a concentration less than or equal to 5.0 mol, preferably less than or equal to 4.0 mol, more preferably less than or equal to 3.0 mol.

Advantageously, the nitrate is present in the second aqueous solution at a concentration of between 1.0 and 5.0 mol/, preferably between 1.2 and 4.0 mol/|, more preferably between 1 .5 and 3.0 mol/l.

Advantageously, according to the present invention, said basic suspension is obtained by bringing the targets into contact with the basic solution.

Preferably, the dissolution of the targets making it possible to produce the basic suspension is carried out by adding the basic solution to the targets.

In general, the volume of basic solution used for the dissolution of the target can be between 500 ml and 1 | per target, preferably between 600 and 700 mi.

The dissolution conditions listed above make it possible in particular to ensure appropriate dissolution kinetics.

The known targets used generally have a combustible nucleus, also called heart, containing uranium, for example in the form of a uranium-aluminum alloy (U-Al). A means known to those skilled in the art for forming a target is the use of a dispersion of uranium-aluminum aluminide. Uranium aluminide generally contains a mixture of UAl, UAls and UAI”. Such a composition is called UAL. For example, to produce a target, the UAl composition can be ground and dispersed in aluminum powder. The mixture can then be compacted and shaped to form the combustible nucleus, also called the core, of the target.

The fuel core can then be encased in aluminum for cladding. The targets are then called “UAL-AI”.

It is understood that the targets are solid and can have different shapes, they are for example flat in the form of plates.

Advantageously, the combustible core of a target comprises a uranium content of at least 18%, preferably of at least 25%, more preferably of at least 30%, even more preferably of at least 40%.

The % are expressed by weight relative to the total weight of fuel core.

Advantageously, the uranium in the target is slightly enriched (in English LEU for Low Enriched Uranium) in uranium-235 isotopes, also called *®U, which is a fissionable isotope of uranium.

Advantageously, the uranium-235 enrichment rate in the target is less than 25%, preferably less 20%, more preferably less 19%. The % are expressed by weight relative to the total weight of uranium in the target.

Advantageously, the number of previously irradiated targets is greater than or equal to 3, preferably greater than or equal to 5, more preferably greater than or equal to 6.

The number of previously irradiated targets depends on the size of the reactor used to implement the method.

Advantageously, the number of previously irradiated targets is less than or equal to 15, or less than or equal to 12.

Advantageously, the number of previously irradiated targets is greater than or equal to 3 or greater than or equal to 5, or greater than or equal to 6.

Advantageously, the number of previously irradiated targets can vary from 3 to 15, or from 5 to 12.

In the context of the present invention, the term “previously irradiated targets” is used to qualify targets having been irradiated before their dissolution to form a basic suspension. The irradiation of the targets can be carried out by any means known to those skilled in the art and can be carried out for example by means of neutrons in a reactor to fission at least part of the uranium-235. irradiation, it is known to those skilled in the art that irradiated targets can be cooled and placed in shielded containers to be transported and chemically treated in order to extract the fission products of interest.

As discussed previously, this extraction of the fission products of interest can be obtained, for example, by dissolving the targets to obtain a basic suspension. This basic suspension then includes the fission products of interest from uranium-235 such as molybdenum-99 and iodine radionuclides. In general, molybdenum-99 and iodine radionuclides are in ionic form while uranium precipitates, for example in the form of sodium di-uranate.

It is therefore understood that at least part of the uranium coming from the target is insoluble in said basic suspension and is in the form of a solid dispersed in the liquid phase of the basic suspension.

According to a certain embodiment, the basic suspension is diluted by a step of diluting said basic suspension with an aqueous solution [solution D].

In general, the solution D can be any aqueous solution making it possible to reduce the viscosity of the basic suspension and can, for example, be water or water comprising at least one base. This solution D is also called dilution water. In general, the base is for example an alkaline hydroxide or an alkaline-earth hydroxide, preferably the base is an alkaline hydroxide. The alkaline hydroxide can, for example, be lithium hydroxide, sodium hydroxide, potassium hydroxide or a combination thereof, preferably sodium hydroxide or potassium hydroxide, more preferably l 'sodium hydroxide.

Advantageously, the concentration of the base, as detailed above, in solution D is between 0.010 and 1.00 M, preferably between 0.025 and 0.750 M, more preferably between 0.050 and 0.50 M.

The purpose of introducing this solution D is in particular to reduce the viscosity of the basic suspension before starting step 2 of separation.

Advantageously, the volume of solution D used during the dilution step is adapted according to the number of targets engaged, and it is, for example, at least 750 ml, preferably at least 1.0 | in increments of 3 targets.

Advantageously, the ratio between the volume of solution D and the volume of the basic suspension is invariable regardless of the number of targets to be dissolved.

Preferably the dilution factor is 1.00, more preferably 2.00, even more preferably 2.75.

The basic suspension thus diluted can be homogenized by any means known to those skilled in the art, for example, by bubbling.

Stage 2 of separation

According to the present invention, the method comprises a step 2 comprising a separation of the solid phase from the liquid phase of said basic suspension.

This stage 2 makes it possible in particular to separate the uranium and the insoluble fission products from the soluble elements such as the radionuclide ions of iodine and molybdenum-99. During this separation step, the solid phase comprising at least the uranium is retained and is also called "cake" or "uranium cake".

The separation step according to the present invention can be carried out by any means known to those skilled in the art for separating a solid from a liquid and can be, for example, a step of sedimentation, decantation, filtration , or their combination, preferably the separation step is filtration.

Advantageously, the separation is carried out by a device known to those skilled in the art making it possible to separate a liquid phase and a solid phase through a porous medium, preferably a filter.

Advantageously, the pore size of the porous medium is between 1.5 and 7.0 µm, preferably between 2.0 and 6.0 µm, more preferably between 2.5 and 5.0 µm.

Non-limiting examples of a porous medium are in particular the nutsche filter, “Büchner” type filter, filter press, bag filter, band filter, drum filter or a combination thereof.

The material constituting the porous medium making it possible to retain the solid phase can be, for example, glass, fiberglass, metal such as stainless steel or a combination thereof.

Advantageously, the separation step can be carried out by pressure or under vacuum or their combination.

Advantageously, the temperature of the basic suspension is lower than the boiling point of said basic suspension at the start of the separation step. For example, the temperature of the basic suspension is below 100°C at the start of the separation step. Preferably, the temperature of the basic suspension is greater than or equal to 50°C, more preferably greater than or equal to 75°C, even more preferably greater than or equal to 90°C at the start of the separation step .

In a particular embodiment of the invention, several separation steps can be carried out in series or in parallel. For example, several separation steps performed in series could improve the efficiency of the separation while several steps in parallel could reduce the time required for the separation.

In a certain embodiment of the process according to the invention, step 2 may comprise at least one rinsing of said solid phase obtained during the separation with an aqueous solution [solution R]. Preferably, step 2 may comprise at least two rinsings of said solid phase obtained during the separation with an aqueous solution [solution R].

In general, the solution R is chosen to rinse or clean said solid phase and can, for example, be water or water comprising at least one base.

In general, the base is for example an alkali hydroxide or an alkaline earth hydroxide, preferably the base is an alkali hydroxide. The alkaline hydroxide can, for example, be lithium hydroxide, sodium hydroxide, potassium hydroxide or a combination thereof, preferably sodium hydroxide or potassium hydroxide, more preferably l ''sodium hydroxide.

Advantageously, the concentration of the base, as detailed above, in the solution R is between 0.010 and 1.00 M, preferably between 0.025 and 0.750 M, more preferably between 0.050 and 0.50 M.

Advantageously, the volume of the solution R is between 1600 and 2000 ml, preferably between 1700 and 1900 ml.

In a particular embodiment according to the invention, the rinsing can be repeated several times, for example at least three times, preferably at least twice.

In general, after step 2, a sample of the liquid phase is taken in order to determine the activity of molybdenum-99 and iodine-131 in the liquid phase.

In the context of the present invention, the activity of a radionuclide (expressed in Curie, Ci) which is the number of disintegrations that the radionuclide produces per unit time (second) is measured by a high purity germanium detector ( HPGe detector). The nature (qualitative analysis) and the activity of the radionuclide (quantitative analysis) present in a sample are therefore determined from the analysis of the spectra of the gamma rays measured over time by the detector.

Provision is made according to the present invention to add a reducing agent to said basic suspension before step 2 and/or to treat said solid phase separated during step 2 with a reducing agent.

In the processes of the state of the art, the solid phase separated during step 2 can present a content of iodine radionuclides which can result in a problem of safety of the process since the radionuclides of iodine can disintegrate into xenon radionuclides, in the form of a radioactive gas whose emission must be controlled.

The inventors have surprisingly found that the addition of a reducing agent, as mentioned above, makes it possible to obtain a solid phase whose content of iodine radionuclide ions is reduced compared to the content of iodine ions. of iodine radionuclides in the solid phase without addition of the reducing agent.

The addition of the reducing agent can be carried out by any method known to those skilled in the art, provided that a solid phase is obtained, the content of iodine radionuclide ions of which is reduced compared to the content into iodine radionuclide ions in the solid phase without addition of the reducing agent.

In the context of the present invention, the reduction in the iodine radionuclide ion content of the solid phase is determined via the increase in the iodine radionuclide ion content in the liquid phase separated at the 2nd step.

The increase in the iodine radionuclide ion content in the liquid phase is calculated on the basis of a measurement of the activity of the iodine radionuclide ions in the liquid phase and the activity expected theory.

In the context of the present invention, the term “expected theoretical activity” means the expected activity value for a given radionuclide determined using the Origen 2.1 computer code (RSICC COMPUTER CODE

COLLECTION, Isotope Generation and Depletion Code, Matrix Exponential Method,

Oak Ridge National Laboratory, Oak Ridge, TN). This value is a function of certain parameters such as, for example, the type of reactor, the nature of the irradiated fuel, the initial enrichment of the fuel, the specific power of the irradiation cycle and the irradiation duration.

In the context of the present invention, it is understood that the “recovery efficiency” (hereinafter RR) makes it possible to determine the efficiency of the process.

The recovery yield of a radionuclide (expressed in %) is defined by the ratio between the activity (expressed in Ci) of said measured radionuclide, An, in the solution and the theoretical activity (expressed in Ci), A: of said radionuclide:

RR = x 100% Eg. 1

Ar

In other words, in the context of the present invention, the content of a radionuclide corresponds to the recovery efficiency (RR) of this radionuclide determined on the basis of the equation, eq. 1, above and expressed in %.

The increase in iodine radionuclide ion content in the liquid phase therefore corresponds to the difference between the RR of iodine radionuclide ions in the liquid phase when a reducing agent has been added and the RR of iodine radionuclide ions in the liquid phase without the addition of a reducing agent.

Advantageously, the addition of the reducing agent makes it possible to obtain a liquid phase whose content of iodine radionuclide ions is increased by at least 3.5%, preferably by at least 5%, preferably by at least 7%, more preferably at least 15%, even more preferably at least 20%. The % are expressed relative to the theoretical activity expected for the iodine radionuclide ions in the liquid phase after step 2.

In the context of the present invention, the reducing agent can be any reducing agent known to those skilled in the art having a reduction potential allowing at least to generate an oxidation-reduction reaction during which the oxidation number of iodine is reduced.

Preferably, the reducing agent comprises at least one anion selected from the group consisting of a sulfite, a hydrosulfite, a thiosulfate, an oxalate, a borohydride and a hydrazine, preferably the anion is a sulfite or a hydrosulfite.

In particular, said reducing agent comprises at least one sulphite.

In the context of the present invention, the expression "at least one anion" means one or more than one anion. Combinations of anions are also included within the scope of the present invention. In the rest of the text, the expression “anion” can be interpreted, in the context of the present invention, in the singular or in the plural so as to mean that the reducing agent can comprise one or more than one anion.

Advantageously, the reducing agent is a salt whose counterion can be any counterion known to those skilled in the art and can be, for example, at least one element chosen from the group consisting of hydrogen , lithium, sodium, potassium, rubidium and cesium, preferably the counterion is sodium.

In a certain embodiment of the method according to the invention, provision is made to add a reducing agent to said basic suspension before step 2. In this way the reducing agent is present in the basic suspension during step 2.

Advantageously, the concentration of the reducing agent in the basic suspension is greater than or equal to 0.015 mol/l, preferably greater than or equal to 0.10 mol/l, more preferentially, greater than or equal to 0.20 mol/l , more preferably greater than or equal to 0.30 mol/l, even more preferably greater than or equal to 0.40 mol.

Advantageously, the concentration of the reducing agent in the basic suspension is less than or equal to 1.00 mol/l, preferably less than or equal to 0.60 mol/l, more preferably less than or equal to 0.40 mol, more preferably less than or equal to 0.20 mol/l, even more preferably less than or equal to 0.10 mol.

Advantageously, the concentration of the reducing agent in the basic suspension is between 0.015 and 1.00 mol/l, preferably between 0.10 and 0.60 mol/l, more preferably between 0.20 and 0.40 mol.

Alternatively or additionally, when a step of diluting the basic suspension is carried out, the reducing agent can also be added to said solution D.

In this embodiment, the concentration of the reducing agent in solution D is advantageously greater than or equal to 0.05 mol, more advantageously greater than or equal to 0.25 mol/l, preferably greater than or equal to 0.50 mol/l, more preferably greater than or equal to 0.75 mol, even more preferably greater than or equal to 1.00 mol/l.

Advantageously, the concentration of the reducing agent in solution D is less than or equal to 2.00 mol/l, more advantageously less than or equal to 1.50 mol, preferably less than or equal to 1.00 mol/l, so more preferably less than or equal to 0.50 mol, even more preferably less than or equal to 0.25 mol.

Advantageously, the concentration of the reducing agent in the solution

D is between 0.05 and 2.00 mol/l, preferably between 0.25 and 1.50 mol, more preferably between 0.50 and 1.00 mol.

In a second embodiment of the method according to the present invention, said solid phase separated in step 2 is treated with a reducing agent.

Non-limiting examples of such a treatment are washing or cleaning, preferably the treatment is a rinse treatment.

Preferably, said treatment of the solid phase separated in step 2 is a step of treating said solid phase with an aqueous solution comprising the reducing agent [solution A].

In this embodiment, the concentration of the reducing agent in solution A is advantageously greater than or equal to 0.05 mol, more advantageously greater than or equal to 0.25 mol/l, preferably greater than or equal to 0.50 mol /l, more preferably greater than or equal to 0.75 mol, even more preferably greater than or equal to 1.00 mol/l.

Advantageously, the concentration of the reducing agent in solution A is less than or equal to 2.00 mol/l, more advantageously less than or equal to 1.50 mol, preferably less than or equal to 1.00, more preferably less than or equal to 0.50 mol, even more preferably less than or equal to 0.25 mol.

Advantageously, the concentration of the reducing agent in the solution

A is between 0.05 and 2.00 mol/l, preferably between 0.25 and 1.50 mol, more preferably between 0.50 and 1.00 mol/l.

Alternatively or additionally, when a step of rinsing said solid phase with an aqueous solution is provided in the process according to the invention, the reducing agent is preferably added to the solution R (aqueous solution for rinsing the solid phase). It is then understood that each of the definitions, preferences and advantageous embodiment mentioned in connection with the solution

A of the present invention are also applicable to the embodiment in relation to solution R.

If necessary, the first and the second embodiment detailed above can be combined.

It is understood according to the present invention that the different embodiments can be made independently of each other or in combination.

Purification step 3

The liquid phase obtained after the separation of step 2, as detailed above, is then subjected to a step 3 during which the liquid phase undergoes a purification step during which at least a part of the radionuclide ions of the iodine are retained by adsorption so as to recover a purified liquid phase whose content of iodine radionuclides ions is reduced compared to the content of iodine radionuclides ions in the liquid phase before step 3.

This purified liquid phase comprises at least the molybdenum-99 ions.

A person skilled in the art can use any known means of purification provided that a purified liquid phase is obtained, the content of iodine radionuclide ions of which is reduced by at least 90%, advantageously 95% more advantageous of at least 97% relative to the iodine radionuclide ion content in the liquid phase before step 3. The iodine radionuclide ion content is determined according to eq.1 above.

In a preferred embodiment of the present invention, the liquid phase obtained after the separation of step 2 undergoes a purification step by a liquid-solid adsorption process.

In general, such liquid-solid adsorption processes are known to a person skilled in the art, in particular involved in chemical processes and in purification techniques. In the context of the present invention, the term adsorption includes the use of at least one solid support such as, for example, at least one sorbent.

In a preferred embodiment of step 3 of the present invention, the liquid-solid adsorption process is carried out by bringing the liquid phase, as defined above, into contact with at least one sorbent.

Preferably, the sorbent is contained in a chromatographic column. In general, the chromatographic column can be made of any material known to those skilled in the art, such as, for example, glass, stainless steel or polyetheretherketone (PEEK). Such a chromatographic column is known from the state of the art and is for example described in the document by M. V. Wilkinson et al. (Separation of iodine produced from fission using silver-coated alumina, Journal of Radioanalytical and Nuclear Chemistry, Vol. 256, No. 3 (2003) 413-415).

The sorbent can be any sorbent known to those skilled in the art having a particular affinity for iodine ions, preferably for iodides, 17.

Advantageously, the sorbent is an inorganic compound such as for example activated carbon, carbon black, zeolites, a metal oxide, preferably the sorbent is a metal oxide. Such a metal oxide is for example,

Titanium oxide, zirconium oxide, aluminum oxide, silicon oxide, or combinations thereof, preferably the metal oxide is aluminum oxide.

Advantageously, the sorbent is doped with a dopant. The dopant can be any dopant known to those skilled in the art having a particular affinity for iodine ions. Preferably, the dopant is a metal such as, for example, silver, copper or a noble metal, such as palladium, platinum, gold, or mixtures thereof, preferably the dopant is silver.

Advantageously, the sorbent is doped with the dopant at a rate (also called impregnation rate) greater than or equal to 5%, more advantageously greater than or equal to 6%, preferably greater than or equal to 8%, more preferably greater than or equal to 10%, more preferably greater than or equal to 12%, even more preferably greater than or equal to 15%. The % are expressed by weight relative to the total weight of sorbent.

If necessary, after carrying out the liquid-solid adsorption process, of said at least a part of the radionuclide ions of iodine on the sorbent, the sorbent on which is adsorbed at least a part of the radionuclide ions of iodine can undergo at least one rinsing with an aqueous solution comprising at least one base [RB solution].

This optional ringing step of the sorbent on which is adsorbed at least a part of the iodine radionuclide ions can be used in particular to recover the residual traces of weakly adsorbed molybdenum-99 and possibly to eliminate other fission products.

In general, the base is for example an alkaline hydroxide or an alkaline-earth hydroxide, preferably the base is an alkaline hydroxide.

The alkaline hydroxide can, for example, be lithium hydroxide, sodium hydroxide, potassium hydroxide or a combination thereof, preferably sodium hydroxide or potassium hydroxide, more preferably sodium hydroxide.

Advantageously, the concentration of the base, as detailed above, in the RB solution is between 0.01 and 0.10 mol / l, more advantageously between 0.02 and 0.07 mol /, so even more advantageous between 0.03 and 0.06 mol/l.

In general, the volume of RB solution used for rinsing the sorbent is for example between 200 and 1000 ml, preferably between 300 and 750 ml, more preferably between 400 and 600 ml.

Preferably, a new sample is taken after step 3 in order to determine the efficiency of iodine fixation on the sorbent and the recovery efficiency of molybdenum-99 in solution. These are determined by measurements of molybdenum-99 and iodine-131 activity in the purified liquid phase.

Stage 4 of acidification

In a certain embodiment of the invention, at least part of the purified liquid phase comprising at least the molybdenum-99 ions obtained after step 3 can undergo a step 4 of acidification. The purified liquid phase comprising at least the molybdenum-99 ions obtained after acidification step 4 is also called acid solution.

In general, step 4 of acidification is carried out with any acid known to those skilled in the art. Such an acid can be for example acetic acid, acetylsalicylic acid, ascorbic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid, formic acid, lactic, preferably nitric acid.

Advantageously, the acid concentration in the acid solution is greater than or equal to 0.10 mol/l, preferably greater than or equal to 0.50 mol/l, more preferably greater than or equal to 0.75 mol/l, even more preferably greater than or equal to 0.90 mol.

Advantageously, the acid concentration in the acid solution is less than or equal to 1.50 mol/l, preferably less than or equal to 1.25 mol/l, more preferably less than or equal to 1 mol.

Advantageously, the acid concentration in the acid solution is between 0.10 and 1.50 mol/l, preferably between 0.5 and 1.25 mol/, more preferably between 0.75 and 1 mol/| , even more preferably between 0.90 and 1 mol.

Advantageously, the acid is used in excess in the acid solution.

In a certain embodiment of the process according to the invention, the purified liquid phase can be heated before and/or during and/or after step 4 of acidification, advantageously at a temperature between 60 and 100°C preferably between 70 and 100°C, more preferably between 70 and 100°C, even more preferably between 90 and 99°C.

Stage 5 purification and recovery of molybdenum-99

In a certain embodiment of the invention, at least part of the acid solution obtained after step 4 can undergo a purification step by adsorption of at least part of the molybdenum-99 ions.

In a preferred embodiment of the present invention, at least part of the acid solution obtained after step 4 undergoes a purification step by a liquid-solid adsorption process.

In general, such liquid-solid adsorption processes are known to a person skilled in the art, in particular involved in chemical processes and in purification techniques. In the context of the present invention, the term adsorption includes the use of at least one solid support such as, for example, at least one sorbent. In this embodiment of the invention, the liquid-solid adsorption process of step 5 can be carried out by bringing at least part of the acid solution, as defined above, into contact with at least one sorbent so as to adsorb at least a portion of the molybdenum-99 ions on the sorbent. In general, the sorbent can be any sorbent known to those skilled in the art having a particular affinity for molybdenum ions, preferably for molybdate ions. _ Advantageously, the sorbent is an inorganic compound such as activated carbon, carbon black, zeolites, a strong anionic resin (RAF also called anion exchange resin), a metal oxide or a combination thereof. Such a metal oxide is, for example, titanium oxide, zirconium oxide, aluminum oxide, silicon oxide, tin oxide, or their combination.

Advantageously, the titanium oxide has a particle size dso of between 80 and 160 μm, preferably between 90 and 150 μm, more preferably between 100 and 120 μm. In the context of the present invention, the notation “dx of y um” means that x% in number of the particles, relative to the total number of particles, have a particle size less than y um.

The activated carbon can be any activated carbon known to those skilled in the art and can be, for example, granular activated carbon (GAC), extruded activated carbon (EAC), powdered activated carbon (PAC) , preferably powdered activated carbon. In general, the powdered activated carbon has a particle size of 0.5-1.0 mm (18-35 mesh ASTM) or 0.3-0.5 mm (35-50 mesh ASTM), preferably 0. 3- 0.5mm (35-50 mesh ASTM). Activated carbon can be doped with a dopant. The dopant can be any dopant known to a person skilled in the art which makes it possible to reduce the residual content of iodine radionuclide ions, preferably having a particular affinity for iodine radionuclide ions. Preferably, the dopant is a metal such as, for example, silver, copper or a noble metal, such as palladium, platinum, gold, or mixtures thereof, preferably the dopant is silver.

The strong anionic resin can be any strong anionic resin known to those skilled in the art having a particular affinity for molybdenum-99 ions, and can be, for example, a styrene-divinyl benzene resin.

Advantageously, the sorbent is contained in an adsorption device such as, for example, a chromatographic column.

Advantageously, the chromatographic column has a diameter between 1.0 and 8.0 cm, preferably between 2.0 and 7.0 cm, more preferably between 3.0 and 5.0 cm.

Advantageously, in this embodiment, after the liquid-solid adsorption process of step 5, said at least part of the molybdenum-99 ions adsorbed on the sorbent can undergo at least one elution by means of at least an eluent. The eluent can be any eluent known to a person skilled in the art which makes it possible to dissolve at least some of the molybdenum-99 ions adsorbed on the sorbent. This results in the recovery of an eluate comprising at least a portion of the molybdenum-99 ions previously adsorbed, preferably in the form of molybdate ions. Advantageously, the eluate comprises at least 70%, preferably 80%, more preferably at least 90% of the Mo-99 previously adsorbed on the sorbent.

Advantageously, the eluent is chosen according to the nature of the sorbent and is preferably an aqueous solution such as, for example, water or water which can also comprise a salt, an acid or a base.

If necessary, step 5 may comprise at least one rinsing step, between the liquid-solid adsorption process and the elution, during which said at least part of the molybdenum-99 ions adsorbed on the sorbent is rinsed by a rinsing solution.

Alternatively or additionally, step 5 may comprise at least one rinsing step, after the elution of at least some of the molybdenum-99 ions, during which the sorbent is rinsed with a rinsing solution.

Advantageously, the rinsing solution is chosen according to the nature of the sorbent according to the knowledge of those skilled in the art and is preferably an aqueous solution such as, for example, water or water which may further comprise a salt, an acid or a base.

When the sorbent is a titanium oxide, preferably, at least one rinsing step is carried out between the liquid-solid adsorption process and the elution, described above, with a rinsing solution comprising at least one acid [ solution

AR]. In general, the acid is for example acetic acid, acetylsalicylic acid, ascorbic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid, formic acid, l lactic acid, preferably nitric acid.

Advantageously, the concentration of the acid in the RA solution is between 0.25 and 1.75 M, preferably between 0.50 and 1.50, more preferably between 0.75 and 1.25.

Alternatively or additionally, the rinsing solution, for said at least one rinsing step carried out between the liquid-solid adsorption process and the elution, can be water or water comprising a salt, for example a salt comprising at least one sulphite, one hydrosulphite, one thiosulphate or one oxalate, preferably the salt comprises at least one sulphite.

When the sorbent is a titanium oxide, the elution of the adsorbed molybdenum-99 ions is preferably carried out by an aqueous solution comprising at least one base [solution E1]. In general, the base is for example an alkaline hydroxide or an alkaline-earth hydroxide, preferably the base is an alkaline hydroxide.

The alkaline hydroxide can, for example, be lithium hydroxide, sodium hydroxide, potassium hydroxide or their combination, preferably sodium hydroxide.

Advantageously, said base is present in solution E1 at a concentration greater than or equal to 0.50 mol/l, preferably greater than or equal to 1.00 mol/, more preferably greater than or equal to 1.50 mol.

Advantageously, said base is present in solution E1 at a concentration less than or equal to 5.00 mol/l, preferably less than or equal to 4.00 mol/l, more preferably less than or equal to 3.00 soft.

Advantageously, said base is present in solution E1 at a concentration of between 0.50 and 5.00 mol, preferably between 1.00 and 4.00 mol, more preferably between 1.50 and 3 .00 mol/l.

Advantageously, the volume of the E1 solution used during the elution is between 250 and 750 ml, preferably between 400 and 600 ml.

Advantageously, the volume of water used during the rinsing step is between 250 and 750 ml, preferably between 400 and 600 ml.

When the sorbent is a strong anionic resin (RAF also called anion exchange resin), preferably the optional rinsing step is carried out with water.

When the sorbent is a strong anionic resin (RAF also called anion exchange resin), the preferred eluent is an aqueous solution comprising at least one nitrate [solution E2].

Advantageously, the nitrate is an alkali metal nitrate or an alkaline-earth nitrate or an ammonium nitrate or their combination, preferably an ammonium nitrate.

Advantageously, the nitrate is present in the solution E2 at a concentration of between between 0.25 and 1.75 mol/l or between 0.5 and 1.5 mol, or between 0.75 and 1.25 mol /I.

When the sorbent is an activated carbon, the preferred eluent is an aqueous solution comprising at least one base [E3 solution]. In general, the base is for example an alkaline hydroxide or an alkaline-earth hydroxide, preferably an alkaline hydroxide. The alkaline hydroxide can, for example, be lithium hydroxide, sodium hydroxide, potassium hydroxide or their combination, preferably sodium hydroxide.

More advantageously, said base is present in the solution

E3 at a concentration between 0.05 and 0.75 mol/| or comprised between 0.1 and 0.5 mol or comprised between 0.2 and 0.4 mol.

More advantageously, step 5 of the present invention involves the successive use of more than one chromatographic column, even more advantageously at least two chromatographic columns, preferably at least three chromatographic columns. Completely surprisingly, the inventors found that the successive use of three chromatographic columns made it possible to obtain very good results. In this way, the acid solution obtained after step 4 undergoes a first liquid-solid adsorption process, as defined above, in the first column. The eluate recovered at the outlet of the first column is injected into the second column so as to undergo a second liquid-solid adsorption process, as defined above, in the second column. The eluate recovered at the outlet of the second column is injected into the third column so as to undergo a third liquid-solid adsorption process, as defined above, in the third column. An eluate is then recovered at the outlet of the third column.

Alternatively, the eluate recovered at the outlet of the second column can undergo an acidification step before being injected into the third column so as to undergo a third liquid-solid adsorption process, as defined below. above, in the third column.

Advantageously, when three chromatographic columns are used successively, the sorbent contained in the first chromatographic column is a titanium oxide, the sorbent contained in the second chromatographic column is a strong anionic resin and the sorbent contained in the third column is an activated carbon.

According to the present invention, the eluate or solution, recovered at the end of the molybdenum-99 production process, comprising at least the molybdenum-99 ions can also be called the mother solution of molybdenum-99 (or SM Mo-99). , which can then be distributed for use in medical diagnostic applications.

The inventors have surprisingly found that said process of the invention makes it possible to achieve a good recovery yield of molybdenum-99 having a purity in terms of content of radionuclidic impurities in accordance with the specifications required by the Pharmacopoeia while improving it the safety of the process by reducing the adsorption of iodine radionuclide ions, in particular iodates, on the solid phase comprising uranium.

The stock solution of molybdenum-99 obtained by the process of the invention can therefore be used in the medical field of diagnosis given that it meets the requirements of the 1923 monograph of the European Pharmacopoeia for a solution of molybdate (Mo-99 ) of sodium obtained by fission. Indeed, the inventors have surprisingly shown that the stock solution of molybdenum-99 obtained by the process of the invention exhibited very good results in terms of critical quality attributes (CQAs) which are the physical properties or characteristics, chemical, biological or microbiological which must meet the requirements of the 1923 monograph of the European Pharmacopoeia so that the stock solution of molybdenum-99 can be used in the medical field.

Examples

The present invention will now be described by means of examples, the purpose of which is mainly illustrative and should not be considered as limiting the scope of the invention.

Preparation of the basic suspension

Targets in the form of plates, of flat shape containing a fuel core UAlx-Al were used. The targets were made of uranium metal, uranium-aluminum alloy (U-AI) powder, aluminum powder and aluminum for the cladding.

The uranium-235 enrichment rate was 19.75% + 0.2%. The % are expressed by weight relative to the total weight of uranium in the target.

Targets were irradiated and then cooled before being used to produce the basic suspension.

The basic suspension was obtained by dissolving the targets with 3780 ml of a basic solution consisting of a 6.3 M sodium hydroxide solution and a 2.4 M sodium nitrate solution.

Separation step

The solid phase and the liquid phase of the basic suspension were separated using a “Büchner” type filtration system so that the solid phase remained on the filter. The liquid phase that passed through the filter was recovered so that a sample could be taken to determine the activity of molybdenum-99 and iodine-131.

Measurement of iodine-131 and molybdenum-99 activity in the liquid phase

The activities of iodine-131 and molybdenum-99 were measured with a high purity germanium detector (HPGe detector). The recovery yields (RR) were calculated as described above on the basis of the theoretical activities which are indicated for each example given below.

Counterexample 1 (CE1)

Counterexample 1 was performed as described in the general procedure above. The expected theoretical activities for this example are 4355 Ci for molybdenum-99 and 1319 Ci for iodine-131

The basic suspension underwent a dilution step with 2160 ml of water before undergoing the separation step. Then, the solid phase obtained during the separation underwent a first rinsing with 1800 ml of water.

The recovery yields (RR) of molybdea-99 and iodine-131 in the liquid phase after the separation step and the first rinse are given in Table 1.

Example 1 (E1)

Example 1 was carried out in the same way as counter-example 1 except that the solid phase underwent a second rinsing with 1500 ml of a 1M Na2SO3 solution followed by a third rinsing with 400 ml of water.

The recovery yields (RR) of molybdea-99 and iodine-131 in the liquid phase after the separation step and the two rinsing steps are given in Table 1.

Table 1

Eenoles |_____ Condilons | Rees RH) rer | Fingage 7] Fingage 2 [PT Moss —

It has been observed that the use of a reducing agent, Na2SO3, to rinse the solid phase after the separation step (E1) makes it possible to decrease the content of iodine-131 ions compared to the content of ions iodine-131 in the solid phase without adding the reducing agent (CE1). This decrease is determined via the 17.99% increase in the recovery efficiency of iodine-131 in the liquid phase obtained after the second rinse with a 1.0 M Na2SO3 solution (E1, 52.34%) by relative to the recovery yield of iodine-131 in the liquid phase without adding a reducing agent (CE1, 34.35%).

It was also observed that the recovery yields of molybdenum-99 are very good and are not negatively affected by the addition of the reducing agent,

Na-SOs.

Example 2a (E2a)

Example 2a was carried out in the same way as counter-example 1 except that the basic suspension dilution step was carried out with a 1M Na:SO4 solution. The expected theoretical activities are 3239 Ci for molybdenum-99 and 1073 Ci for iodine-131.

The recovery yields (RR) of molybdea-99 and iodine-131 in the liquid phase after the separation step and the first rinse are given in Table 2.

Example 2b (E2b)

Example 2b was carried out under the same conditions as Example 2a except that the solid phase was subjected to a second rinsing with 1500 ml of a solution of

Na2SOs 1M followed by a third rinse with 400 ml of water.

The recovery yields (RR) of molybdea-99 and iodine-131 in the liquid phase after the separation step and the two rinsing steps are given in Table 2.

Table 2

Benois |_____ Conalians | Ras FR)

Pray | Fine] Finance [HS Mo

It was observed that the use of a reducing agent, Na2SO: 1M, to dilute the basic suspension leads to a high recovery yield of iodine-131, 89.75% (E2a). This recovery yield is further improved, 95.48% (E2b) when the solid phase is rinsed with a 1M Na2SO:3 solution.

It was also observed that the recovery yields of molybdenum-99 are very good and are not negatively affected by the addition of the reducing agent,

NazSOs.

Example 3a (E3a)

Example 3a was carried out in the same way as counter-example 1 except that the step of diluting the basic suspension was carried out with a solution of Na-SOs; 0.5M and that no rinsing of the solid phase has been carried out. The expected theoretical activities are 3628 Ci for molybdenum-99 and 995 Ci for iodine-131

The recovery yields (RR) of molybdea-99 and iodine-131 in the liquid phase after the separation step are given in Table 3.

Example 3b (E3b)

Example 3b was carried out in the same way as example 3a except that the solid phase underwent a first rinsing with 1800 ml of a 0.5M Na2SO3 solution.

The recovery yields (RR) of molybdea-99 and iodine-131 in the liquid phase after the separation step and the first rinse are shown in Table 3.

Example 3c (E3c)

Example 3b was carried out in the same way as example 3a except that the solid phase underwent a second rinsing with 1800 ml of water.

The recovery yields (RR) of molybdea-99 and iodine-131 in the liquid phase after the separation step and the two rinsing steps are given in Table 3.

Table 3

Benois [Conditions] Raas AA er | Ringage | Fingering 2 | [Moe

It was observed that the use of a reducing agent, Na2SO:3 0.5M, to dilute the basic suspension leads to a high recovery yield of iodine-131, 77.69% (E3a). This recovery yield is further improved, 95.48% (E3b) when the solid phase is rinsed with a 0.5M Na2SO3 solution.

It was also observed that the recovery yields of molybdenum-99 are very good and are not negatively affected by the addition of reducing agent,

Na2SOs.

Claims (36)

1. Process for producing molybdenum-99 comprising the following steps: Step 1: providing a basic suspension comprising at least one liquid phase comprising at least molybdenum-99 ions and iodine radionuclide ions and at least a solid phase comprising at least uranium; Step 2: separation of the solid phase from the liquid phase of said basic suspension: Step 3: purification of said liquid phase by a process of adsorption of at least a part of the iodine radionuclide ions to produce a liquid phase purified comprising at least the ions of molybdenum-99 and whose content of ions of radionuclides of iodine is reduced by at least 90%, preferably 95%, more preferably 97%, with respect to the content of ions of iodine radionuclides in the liquid phase before step 3, characterized by adding a reducing agent to said basic suspension before step 2 and/or treating said solid phase obtained in step 2 with a reducing agent so as to obtain a solid phase whose content of iodine radionuclides ions is reduced compared to the content of iodine radionuclides ions in the solid phase without addition of the reducing agent. 2. Method according to claim 1, in which the addition of the reducing agent makes it possible to obtain a liquid phase whose content of iodine radionuclide ions is increased by at least 3.5%, preferably by at least 5%, preferably at least 7%, more preferably at least 15%, even more preferably at least 20%, the % are expressed relative to the theoretical activity expected for iodine radionuclide ions in the liquid phase after step 2. 3. A method according to any one of claims 1 or 2 wherein the reducing agent comprises at least one anion selected from the group consisting of a sulfite, a hydrosulfite, a thiosulfate, an oxalate, a borohydride and a hydrazine, 4. Process according to claim 3 in which the anion is a sulphite or a hydrosulphite. 5. Process according to any one of claims 1 to 4, in which the concentration of the reducing agent in the basic suspension is between 0.015 and 1.00 mol/, preferably between 0.10 and 0.60 mol/ , more preferably between 0.20 and 0.40 mol. 6. Method according to any one of claims 1 to 5 further comprising a step of diluting said basic suspension with an aqueous solution [solution D]. 7. Process according to claim 6, in which the reducing agent is added to the said solution D and the concentration of the reducing agent in the solution D is between 0.05 and 2.00 mol/, preferably between 0. 25 and 1.50 mol, more preferably between 0.50 and 1.00 mol. 8. Method according to any one of claims 1 to 7 wherein said treatment of the solid phase separated in step 2 is a step of treating said solid phase with an aqueous solution comprising the reducing agent [solution A] and in which the concentration of the reducing agent in the solution A is between 0.05 and 2.00 mol/, preferably between 0.25 and 1.50 mol/, more preferably between 0.50 and 1.00 mol. 9. Method according to any one of claims 1 to 8 wherein said basic suspension is obtained by dissolving at least one previously irradiated uranium target. 10. Process according to claim 9, in which said at least one previously irradiated uranium target has a uranium-235 enrichment rate of less than 25%, preferably less than 20%. 11. Process according to any one of claims 1 to 10, in which step 3 is a step during which the liquid phase obtained after the separation of step 2 undergoes a purification step by a liquid-solid adsorption process. and wherein the liquid-solid adsorption process is carried out by contacting the liquid phase with at least one sorbent. 12. The method of claim 11 wherein the sorbent is a metal oxide selected from the group consisting of titanium oxide, zirconium oxide, aluminum oxide, silicon oxide, oxide of pewter or their combination. 13. Process according to claim 11 or 12, in which the sorbent is titanium oxide. 14. Method according to any one of claims 11 to 13 wherein said sorbent is doped with a dopant at a rate greater than or equal to 5%, more preferably greater than or equal to 6%, preferably greater than or equal to 8%, more preferably greater than or equal to 10%, more preferably greater than or equal to 12%, even more preferably greater than or equal to 15%, the % are expressed by weight relative to the total weight of sorbent. 15. Process according to claim 14, in which the dopant is a metal chosen from the group consisting of silver, copper, a noble metal or a mixture thereof. 16. Process according to claim 14 or 15, in which the dopant is silver. 17. Method according to any one of claims 1 to 16 further comprising a step 4 during which at least a portion of the purified liquid phase comprising at least the molybdenum-99 ions obtained after step 3 undergoes a step of acidification. 18. Process according to claim 17, in which the acidification is carried out by adding an acid to at least part of the purified liquid phase to form an acid solution, said acid being chosen from the group consisting of acetic acid. , acetylsalicylic acid, ascorbic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid, formic acid, lactic acid or mixtures thereof. 19. A method according to claim 18 wherein said acid is nitric acid. 20. Process according to any one of claims 18 or 19, in which the acid concentration in the acid solution is between 0.10 and 1.50 mol, preferably between 0.5 and 1.25 mol/l, of more preferentially between 0.75 and 1 mol/l, even more preferentially between 0.90 and 1 mol/l. 21. Method according to any one of claims 17 to 20 further comprising a step 5 during which at least a portion of the acid solution obtained after step 4 undergoes a purification step by adsorption of at least a portion of the ions molybdenum-99. 22. Process according to claim 21, in which the adsorption is a liquid-solid adsorption process carried out by bringing at least a part of the acid solution into contact with at least one sorbent so as to adsorb at least a molybdenum-99 ions on said sorbent. 23. The method of claim 22 wherein said sorbent is an inorganic compound selected from the group consisting of activated carbon, carbon black, zeolites, a strong anionic resin, a metal oxide or a combination thereof. 24. Process according to claim 22 or 23, in which said sorbent is selected from the group consisting of activated carbon, a strong anionic resin, titanium oxide or a combination thereof. 25. Process according to any one of Claims 22 to 24, in which the said sorbent is contained in an adsorption device, preferably in a chromatographic column. 26. Process according to any one of claims 22 to 25 further comprising, after the liquid-solid adsorption process of step 5, at least one elution by means of at least one eluent of said at least part of the molybdenum-99 ions adsorbed on the sorbent to recover an eluate comprising at least a portion of the molybdenum-99 ions previously adsorbed. 27. The method of claim 26 wherein said eluate comprises at least 70%, preferably 80%, more preferably at least 90% of molybdenum-99 previously adsorbed on the sorbent, the % are expressed by weight relative to the weight total molybdenum-99 previously adsorbed on the sorbent. 28. Process according to claim 26 or 27, in which the sorbent is a titanium oxide and in which the eluent is an aqueous solution comprising at least one base [E1 solution]. 29. Process according to claim 28, in which the said base is a sodium hydroxide and is present in the solution E1 at a concentration of between 0.50 and 5.00 mol/, preferably between 1.00 and 4.00 mol. / l, more preferably between 1.50 and 3.00 mol. 30. Process according to any one of claims 26 or 27, in which the sorbent is a strong anionic resin and in which the eluent is an aqueous solution comprising at least one nitrate [solution E2]. 31. Process according to claim 30, in which the said nitrate is an ammonium nitrate and is present in the solution E2 at a concentration of between between 0.25 and 1.75 mol/l or between 0.5 and 1.5 mol/l, or between 0.75 and 1.25 mol. 32. Process according to claim 26 or 27, in which the sorbent is an activated carbon and in which the eluent is an aqueous solution comprising at least one base [E3 solution]. 33. Process according to claim 32, in which the said base is a sodium hydroxide and is present in the E3 solution at a concentration of between 0.05 and 0.75 mol/l | or between 0.1 and 0.5 mol/l or between 0.2 and 0.4 mol. 34. Process according to any one of claims 25 to 33, in which step 5 involves the successive use of more than one chromatographic column, advantageously at least two chromatographic columns, preferably at least three chromatographic columns. 35. Process according to any one of claims 25 to 34 in which step 5 involves the successive use of a first chromatographic column followed by a second chromatographic column followed by a third chromatographic column. 36. Process according to claim 35, in which the sorbent contained in said first chromatographic column is a titanium oxide, the sorbent contained in said second chromatographic column is a strong anionic resin and the sorbent contained in said third column is an activated carbon.