阅读说明：本技术 富集和放射性同位素生产 (Enrichment and radioisotope production ) 是由 P·W·H·德贾格 A·T·A·M·德克森 于 2019-09-13 设计创作，主要内容包括：一种组合式富集和放射性同位素生产设备,包括：电子源,所述电子源被布置成提供电子束,所述电子源包括电子注入器和加速器；波荡器,所述波荡器被配置成使用所述电子束来产生辐射束；分子流发生器,所述分子流发生器被配置成提供与辐射束相交的分子流；接收器,所述接收器被配置成接收从分子流选择性接收的分子或离子；以及靶标支撑结构,所述靶标支撑结构被配置成在使用中保持所述电子束入射到其上的靶标。(A combined enrichment and radioisotope production facility, comprising: an electron source arranged to provide an electron beam, the electron source comprising an electron injector and an accelerator; an undulator configured to generate a beam of radiation using the electron beam; a molecular flow generator configured to provide a molecular flow that intersects a radiation beam; a receiver configured to receive molecules or ions selectively received from a stream of molecules; and a target support structure configured to hold a target on which the electron beam is incident, in use.)

1. A combined enrichment and radioisotope production facility, comprising:

an electron source arranged to provide an electron beam, the electron source comprising an electron injector and an accelerator;

an undulator configured to generate a beam of radiation using the electron beam;

a molecular flow generator configured to provide a molecular flow that intersects the radiation beam;

a receiver configured to receive molecules or ions selectively received from the molecular stream; and

a target support structure configured to hold a target on which the electron beam is incident, in use.

2. The apparatus of claim 1, wherein the beam of radiation is configured to at least partially ionize the molecular stream.

3. The apparatus of claim 2, wherein the apparatus further comprises a magnet configured to generate a magnetic field traversed by the at least partially ionized molecular stream.

4. The apparatus of claim 2 or 3, wherein the apparatus further comprises electrodes configured to generate an electric field that is traversed by the at least partially ionized molecular stream.

5. The apparatus of claim 3 or 4, wherein the receiver is a first receiver of two or more receivers, the first receiver configured to receive ions having a mass corresponding to a desired isotope, and a second receiver configured to receive other ions.

6. The apparatus of claim 5, wherein the first receiver comprises a cold plate onto which ions condense or freeze, or a pump that pumps ions to a vessel.

7. The apparatus of any of claims 2 to 6, wherein the radiation beam is an infrared radiation beam.

8. The apparatus of claim 1, wherein the radiation beam is configured to excite a desired isotope in the molecular stream.

9. The apparatus of claim 8, wherein the receiver is a first receiver of two or more receivers, the first receiver configured to receive molecules comprising the excited desired isotope, and a second receiver configured to receive other molecules.

10. The apparatus of claim 9, wherein the first receiver comprises an annular opening configured to receive molecules comprising the excited desired isotope.

11. The apparatus according to any one of claims 8 to 10, wherein the radiation beam is an ultraviolet radiation beam.

12. A method of combined enrichment and radioisotope production, comprising:

providing an electron beam using an electron injector and an accelerator;

generating a beam of radiation with the electron beam using an undulator;

providing a molecular stream that intersects the radiation beam;

selectively receiving molecules or ions from the molecular stream containing the desired isotope in a receiver; and

the electron beam is directed onto a target containing a desired isotope to produce a radioisotope.

13. The method of claim 12, wherein the method further comprises: extracting isotopes received in the receiver and using the isotopes to form subsequent targets on which the electron beam is incident.

14. A method according to any one of claims 12 to 13, wherein the beam of radiation at least partially ionizes the molecular stream, and wherein the at least partially ionized molecular stream subsequently passes through a magnetic and/or electric field that alters the trajectory of the ions according to their mass.

15. The method of any one of claims 12 to 14, wherein the radiation beam excites a desired isotope in the molecular stream, and wherein molecules containing the desired isotope are subsequently deflected away from other molecules in the molecular stream.

Technical Field

The present invention relates to a combined enrichment and radioisotope production facility.

Background

Radioisotopes are unstable isotopes. The radioisotope will decay over time by emitting protons and/or neutrons. Radioisotopes are used in medical diagnostics and medicine, and also in industrial applications.

The most commonly used medical radioisotope is Tc-99m (technetium) for diagnostic applications. The production of Tc-99m uses a high-throughput nuclear reactor. Uranium (a mixture including U-238 and U-235) is bombarded with neutrons in a nuclear reactor. Spontaneous and neutron-induced fission of uranium 235 occurred, and U-235 separated into Mo-99 plus Sn (x13) plus neutrons. Photon fission of U-238 can also produce Mo-99. Mo-99 is separated from the other fission products and shipped to the radiopharmacy. Mo-99 has a half-life of 66 hours and decays to Tc-99 m. Tc-99m has a half-life of only 6 hours (which is useful for medical diagnostic techniques). Tc-99m is separated from Mo-99 in the radiopharmacy and then used in medical diagnostic techniques.

Mo-99 is widely used worldwide to produce Tc-99m for use in medical diagnostic techniques. However, only a very few high flux nuclear reactors can be used to produce Mo-99. These high-flux nuclear reactors are also used to make other radioisotopes. All high flux nuclear reactors have been in excess of 40 years and are not expected to continue operating indefinitely.

Disclosure of Invention

It may be deemed desirable to provide alternative radioisotope production facilities and associated methods and/or associated systems.

According to one aspect of the present invention, there is provided a combined enrichment and radioisotope production facility, comprising: an electron source arranged to provide an electron beam, the electron source comprising an electron injector and an accelerator; an undulator configured to generate a beam of radiation using the electron beam; a molecular flow generator configured to provide a molecular flow that intersects a radiation beam; a receiver configured to receive molecules or ions selectively received from a stream of molecules; and a target support structure configured to hold a target on which the electron beam is incident, in use.

The apparatus is advantageous in that it utilizes the same source of electrons to produce the radioisotope and to produce the beam of radiation for enrichment. Radioisotope production and enrichment can be performed using the same source of electrons simultaneously. This dual use of the electron source reduces costs.

The beam of radiation may be configured to at least partially ionize the molecular stream.

The apparatus may further comprise a magnet configured to generate a magnetic field traversed by the at least partially ionized molecular stream.

The device may further comprise electrodes configured to generate an electric field for being traversed by the at least partially ionized molecular stream.

The receiver may be a first receiver of two or more receivers. The first receiver may be configured to receive ions having a mass corresponding to a desired isotope. The second receiver may be configured to receive other ions.

The first receiver may include a cooling plate to which ions condense or solidify. The first receiver may comprise a pump to pump ions to the container.

The radiation beam may be an infrared radiation beam.

The beam of radiation may be configured to excite a desired isotope in the molecular stream.

The receiver may be a first receiver of two or more receivers. The first receiver may be configured to receive a molecule comprising the excited desired isotope. The second receiver may be configured to receive other molecules.

The first receiver may include an annular opening configured to receive molecules including the excited desired isotope.

The first receiver may include a cooling plate to which molecules containing desired isotopes condense or solidify. The first receiver may include a pump that pumps molecules containing the desired isotope to a container.

The radiation beam may be an ultraviolet radiation beam.

The apparatus may further comprise a controller configured to control the wavelength of the radiation beam by adjusting the power delivered to the accelerator.

According to a second aspect of the present invention there is provided a method of combined enrichment and radioisotope production, the method comprising: providing an electron beam using an electron injector and an accelerator; generating a beam of radiation with the electron beam using an undulator; providing a molecular stream that intersects the radiation beam; selectively receiving molecules or ions from the molecular stream containing the desired isotope in a receiver; and directing an electron beam onto a target containing a desired isotope to produce the radioisotope.

The method is advantageous because it utilizes the same source of electrons to produce the radioisotope and to produce the beam of radiation for enrichment. Radioisotope production and enrichment can be performed using the same source of electrons simultaneously. This dual use of the electron source reduces costs. The enriched isotopes produced using the enrichment methods can subsequently be used by radioisotope production methods.

The method may further comprise: the isotopes received in the receiver are extracted and used to form a subsequent target on which an electron beam is incident.

The electron beam may have an energy of about 14MeV or higher.

The beam of radiation may at least partially ionize the molecular stream. The at least partially ionized molecular stream may then pass through a magnetic and/or electric field that alters the trajectory of the ions according to their mass.

Ions having a mass corresponding to a desired isotope may be received in the first receiver.

The radiation beam may excite a desired isotope in the molecular stream. Molecules containing the desired isotope may then be deflected away from other molecules in the molecular stream.

A molecule containing a desired isotope may be received in a first receptacle.

Features of any given aspect of the invention may be combined with features of other aspects of the invention.

As will be appreciated by those skilled in the art, various aspects and features of the present invention set forth above or below may be combined with various other aspects and features of the present invention.

Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which:

figure 1 is a schematic view of a combined enrichment and radioisotope production facility according to an embodiment of the invention;

figure 2a is a schematic view of a target of the radioisotope production device of figure 1;

figure 2b is a schematic view of an alternative target of the radioisotope production device of figure 1;

figure 3 is a schematic view of an alternative enrichment apparatus which may form part of a combined enrichment and radioisotope production apparatus in accordance with an alternative embodiment of the invention.

Detailed Description

Fig. 1 schematically depicts a combined enrichment and radioisotope production facility 2 according to an embodiment of the invention. The enrichment device 4 of the combined device 2 is configured to produce enriched Mo-100. This may start with a mixture of Mo-100, Mo-98 and other Mo isotopes, or may start with a mixture containing molybdenum (such as MoF)₆Or MoO₃) The compound of (1). The radioisotope production facility 6 of the combined facility is configured to convert the enriched Mo-100 to Mo-99. Mo-99 decays to Tc-99m, which can be separated from Mo-99 and used in medical diagnostic techniques.

The combined apparatus 2 comprises an electron injector 8 and an electron accelerator 10. The electron accelerator 10 may be a linear accelerator. Both the electron injector 8 and the linear accelerator 10 form part of the enrichment apparatus 4 and both form part of the radioisotope production apparatus 6.

The electron injector 8 is arranged to generate a beam of bunched electrons E and comprises an electron source (for example a photocathode illuminated by a pulsed laser beam or a thermionic emission source).

Electrons in the electron beam E may be guided from the electron injector 8 to the linear accelerator 10 by a magnet (not shown). The linac 10 accelerates the electron beam E. In one example, the linac 10 may include a plurality of axially spaced apart radio frequency cavities, and one or more radio frequency power supplies operable to control the electromagnetic field along a common axis as electron bunches pass between the one or more radio frequency power supplies, thereby accelerating each electron bunch. The radio frequency cavity may be a superconducting radio frequency cavity. Advantageously, this allows: a relatively large electromagnetic field applied at a high duty cycle; a larger beam aperture, which results in less loss due to the wake field; and increasing the fraction or fraction of the radio frequency energy (relative to the radio frequency energy dissipated through the cavity wall) transmitted to the beam. Alternatively, the rf cavity may be conventionally conductive (i.e., not superconducting) and may be formed of, for example, copper. Other types of linacs may be used, such as, for example, a laser wake field accelerator or an inverse free electron laser accelerator. As an alternative to the linear accelerator, a circular accelerator, such as a synchrotron or a quincunx (rheotron) accelerator, may be used.

The linac 10 may be composed of a single module, or may be composed of a plurality of modules. Although the linac 10 is depicted in fig. 1 as being positioned along a single axis, the linac may include a plurality of modules that are not all located on a single axis. For example, bends may exist between some linac modules and other linac modules.

For example, the linac 10 may accelerate electrons to energies of about 14MeV or higher. The linac may accelerate electrons to an energy of about 30MeV or more (e.g., up to about 75MeV, up to about 90MeV, or up to about 100 MeV).

The radioisotope production device 6 also includes an electron beam splitter 12. The undulator 16 is located between the linac 10 and the electron beam splitter 12. The undulator has no significant effect on the operation of the radioisotope production device 6, but is an important component of the enrichment device 4 (as discussed further below). The electron beam splitter 12 is arranged to split the electron beam E along two propagation paths: a first propagation path towards one side of the target 14 and a second propagation path towards the opposite side of the target 14. Magnets (not shown) may be provided to direct the electron beam E along each propagation path. As will be understood by those skilled in the art, the electron beam E may be referred to as a pulse train. The electron beam splitter 12 is arranged to direct a portion of the pulses along the first path and a portion of the pulses along the second path. For example, 50% of the pulses in the electron beam E may be sent along the first path and 50% of the pulses are sent along the second path. However, it will be appreciated that any pulse ratio (between the two propagation paths) may be used.

The electron beam splitter 12 may be implemented using any suitable means, and may be, for example, a deflector (e.g., kicker) utilizing magnetic deflection or electrostatic deflection. The beam splitting may be performed at a sufficiently high frequency so that the heat load from the electron beam E is substantially evenly distributed on each side of the target 14. In some embodiments, pulses may be skipped within the electron beam E to allow time for switching between pulses. As an example, if the pulses are generated at 375MHz, 1000 pulses may be skipped every 20 milliseconds, leaving about 3 microseconds for the beam splitter 12 to switch the propagation path of the electron beam E.

The target 14 is configured to receive electrons of the electron beam E and to use the electrons to convert the source material into a radioisotope. In this embodiment, the target 14 may be Mo-100(Mo-100 is a stable and naturally occurring isotope of Mo) that is converted to Mo-99 via photon-induced neutron emission. The mechanism of photon generation is Bremsstrahlung radiation (braking radiation) due to electrons striking the target 14. The energy of the photons generated in this way may be, for example, greater than 100kev, may be greater than 1MeV, and may be greater than 10 MeV. The photons may be described as extremely hard X-rays.

This reaction has a threshold energy of 8.29MeV and thus, if a photon incident on the photon target has an energy of less than 8.29MeV, this reaction will not occur. The reaction has a cross section that peaks at about 14MeV (reaction cross section indicates the probability of the reaction being initiated by a photon of a given energy). In other words, the reaction has a resonance peak at about 14 MeV. Thus, in one embodiment, photons having energies of about 14MeV or higher can be used to convert Mo-100 photon targets to Mo-99.

The energy of the photons generated by said braking radiation has an upper limit set by the energy of the electrons in the electron beam E. The photons will have an energy distribution, but the upper limit of the distribution will not exceed the energy of the electrons in the electron beam. Thus, in an embodiment for converting a Mo-100 photonic target to Mo-99, the electron beam will have an energy of at least 8.29 MeV. In an embodiment, the electron beam E may have an energy of about 14MeV or greater.

As the energy of the electron beam increases, more photons will be generated with sufficient energy (for the same electron flow) to cause the desired reaction. For example, as noted above, Mo-99 produces a cross-section having a peak at about 14 MeV. If the electron beam E has an energy of about 28MeV, each electron can generate two photons with an energy of about 14MeV, thereby increasing the conversion of the photon target to Mo-99. However, as the energy of the electron beam increases, photons with higher energy will initiate other unwanted reactions. For example, photon-induced emission of protons and neutrons has a threshold energy of 18 MeV. This reaction is undesirable because it does not produce Mo-99, but instead produces unwanted reaction products.

In general, the selection of the energy of the electron beam (and thus the maximum energy of the photons) may be based on a comparison between the yield of the desired product (e.g., Mo-99) and the yield of the undesired product. In an embodiment, the electron beam may have an energy of about 14MeV or greater. The electron beam E may, for example, have an energy of about 30MeV or greater (e.g., up to about 45 MeV). This range of electron beam energy may provide good production rates of photons having an energy of the reaction resonance peak of about 14 MeV. However, in other embodiments, the electron beam may have other energies. For example, an electron beam may have an energy of 60MeV, as electrons at this energy may be able to cause multiple reactions and thereby increase yield.

Fig. 2a schematically depicts an example arrangement of the target 14. In fig. 2a, the target 14 comprises a plurality of plates 32 made of Mo-100 supported by a support structure 31. As described above, when electrons in the electron beam E are incident on the plate 32, photons are emitted. The photons emitted from the target 14 are schematically depicted in fig. 2a by the wavy line γ. When a photon gamma is incident on a Mo-100 nucleus, the photon may cause a photonuclear reaction through which neutrons are ejected from the nucleus. Thus, Mo-100 atoms are converted to Mo-99 atoms. In the arrangement of fig. 2a, the plate 32 can be considered to be both an electronic and a photonic target.

The target 14 may receive the photons γ for a period of time during which the proportion of Mo-99 in the target 14 increases and the proportion of Mo-100 in the target decreases. The target 14 is then removed from the radioisotope production facility 6 for processing and transport to a radiopharmacy. Tc-99 (which is the decay product of Mo-99) is then extracted and used in medical diagnostic applications.

Fig. 2b schematically depicts an alternative example arrangement of the target 14. In fig. 2b, the target 14 also includes a discrete electronic target 34. Where a separate electronic target is provided, the target plate 32 may be considered a photonic target. For example, the electron target 34 may be formed of tungsten, tantalum, or some other material that will decelerate electrons and generate photons. However, the electronic target 34 may be formed of the same material as the photonic target (e.g., Mo-100). The electronic targets are held by support structures 33a, 33 b.

Although the target 14 shown in fig. 2a and 2b includes three plates, the target may include any suitable number of plates. Although the targets described include Mo-100, the photonic targets may include any suitable material. Similarly, the material of the target may be provided in any suitable shape and/or configuration. A shield (e.g., lead shield) may be provided around the target 14.

Each electronic target 34a, 34b in fig. 2b is depicted as a single block of material. However, each electronic target may be provided as a plurality of plates. The plate may, for example, have a configuration corresponding to that of the targeting plate 32 described above. Similarly, the support structures 33a, 33b may be configured to hold a plurality of electronic target boards.

The electronic target 34 and the target plate 32 may be provided with conduits for coolant fluid to flow through.

Other forms of target support structure may be provided.

In both fig. 2a and 2b, the electron beam E is received at each side of the target 14. By distributing the heat load more evenly across the target 14, the overall temperature generated is reduced, thereby mitigating and simplifying the cooling requirements (as compared to directing the electron beam E onto only one side of the target 14).

In other embodiments of the present invention, electron beam splitter 12 is not present. In such embodiments, a single electron beam may be incident on the target 14.

As further indicated above, the electron injector 8 and the linear accelerator 10 form part of the enrichment apparatus 4 in addition to forming part of the radioisotope production apparatus 6. The enrichment device 4 further comprises an undulator 16. The electron beam E enters the undulator after being accelerated by the linac 10. Alternatively, the electron beam E may pass through a beam condenser (not shown) disposed between the linac 10 and the undulator 16. The bunching compressor may be configured to spatially compress an existing electron bunch in the electron beam E.

The undulator 16 may comprise a plurality of modules or a single module. The or each module comprises a periodic magnet structure operable to generate a periodic magnetic field and arranged to direct an electron beam E generated by the electron injector 8 and the linear accelerator 10 along a periodic path within the module. The periodic magnetic field generated by the undulator 16 causes the electrons to follow an oscillating path about the central axis. As a result, within the undulator 16, electrons generally radiate electromagnetic radiation in the direction of the central axis of the undulator. The radiated electromagnetic radiation forms a radiation beam B (e.g., infrared radiation). The beam B is oriented so that it intersects the molybdenum gas flow, thereby facilitating molybdenum enrichment (as described further below).

The path followed by the electrons of the electron beam E in the undulator 16 may be sinusoidal and planar, with the electrons periodically crossing the central axis. Alternatively, the path may be helical and the electrons rotate about the central axis. The type of oscillation path may affect the polarization of the radiation beam B emitted by the undulator 16.

As the electrons move through the undulator 16, they interact with the electric field of the radiation, exchanging energy with the radiation. Typically, the amount of energy exchanged between the electrons and the radiation will oscillate rapidly unless the condition is close to a resonance condition. Under a resonant condition, the interaction between the electrons and the radiation causes the electrons to bunch together into a microbeam that is modulated within the undulator at the wavelength of the radiation and that stimulates coherent emission of the radiation along the central axis. The resonance condition may be given by the following equation:

wherein λ_emIs the wavelength, λ, of said radiation_uIs the undulator period of the undulator module through which the electrons propagate, γ is the lorentz factor of an electron, and K is the undulator parameter. A depends on the geometry of the undulator 16: for a spiral undulator a generating circularly polarized radiation 1, for a planeUndulator a-2 and for a helical undulator 1 generating elliptically polarized radiation (neither circular nor linear polarization)<A<2. In practice, each electron bunch will have an energy spread, but this energy spread can be minimized as much as possible (by generating an electron beam E with a low emittance). The undulator parameter K is typically approximately 1 and is given by

Wherein q and m are respectively the charge and mass of said electron, B₀Is the magnitude of the periodic magnetic field and c is the speed of light.

Resonant wavelength λ_emEqual to the first harmonic wavelength spontaneously radiated by electrons moving through the or each undulator module. The electron injector 8, accelerator 10 and undulator 16 may together be considered a free electron laser.

The radiation beam B generated by the undulator 16 may be an infrared radiation beam. For example, the radiation beam B may have a wavelength of about 10 microns (e.g., between 9 and 11 microns). A wavelength of about 10 microns is particularly suitable for molybdenum enrichment.

In an embodiment, the electron beam transmitted from the accelerator 10 to the undulator 16 may have an energy of about 60 MeV. The undulator 16 may have a magnetic period of about 140 mm. An undulator length of about 4.5 meters may be sufficient to provide saturation of the radiation beam B emitted by the undulator. Each electron pulse with a bunching charge of 75pC and a bunching length of 10fs will produce about 100 muj of infrared radiation. The bunching frequency is 375 MHz. With this set of electron beams and undulator parameters, a beam of infrared radiation B with a power exceeding 35kw may be generated. In another example, the beaming frequency may be about 1.3 GHz. In general, the parameters of the electron beam E may be any suitable parameters and may be selected to provide a desired power to the radiation beam B.

The generation of the beam B of infrared radiation using the undulator 30 takes away only a small fraction of the energy of the electron beam E. Thus, the electron beam E still has sufficient energy to convert Mo-99 (or a compound containing Mo) to Mo-100 in the exposure unit 14.

The beam steering mirror 42 directs the infrared beam B toward the gas flow of molybdenum (or a molybdenum-containing compound). Although a single beam steering mirror 42 is depicted, in practice two or more beam steering mirrors may be provided to allow the position of the radiation beam to be adjusted with additional flexibility. Due to the schematic nature of fig. 1, it appears as if the infrared beam B intersects the electron beam E. However, the beam of infrared radiation B can be easily directed such that it travels around (e.g., above or below) the electron beam E.

The enrichment device 4 comprises a molybdenum flow generator 44, a magnet 45, a first receiver 58 and a second receiver 60. The molybdenum flow generator 44, magnet 45 and receivers 58, 60 may be disposed within a housing 62, the housing 62 being sealed such that the molybdenum flow generator 44, magnet 45 and receivers 58, 60 are isolated from the external environment. A window 52 may be provided in the housing 62 to allow the infrared beam B to enter the housing.

The molybdenum flow generator 44 may include a vessel 54, the vessel 54 containing MoO₃Or MoF₆Or some other gaseous molybdenum-containing molecule. Other gaseous molybdenum-containing molecules may be used, but these molecules may need to be heated to higher temperatures, e.g., in excess of 200 ℃, to form a gas (MoF)₆Boil at 34 ℃). The receptacle 54 includes an opening at one end. The opening includes a nozzle 56 configured to generate a stream 46 of gaseous molybdenum-containing molecules. The infrared beam B intersects the flow of gaseous molybdenum-containing molecules and at least partially ionizes the flow. In embodiments, the oxygen atoms may be from MoO₃Is stripped to form MoO₂. In another embodiment, the fluorine atoms may be selected from MoF₆Is stripped to form MoF₅. The flow of at least partially ionized molecules passes through the magnetic field 48 generated by the magnet 45. Additionally or alternatively, the electric field may be generated using a differential voltage applied to the electrodes. Electric and magnetic fields orthogonal to each other may provide the most optimal for the moleculeAnd (4) effectively separating.

The path of travel of the ions in the stream 46 through the magnetic field generated by the magnet 45 depends on the mass and charge of the ions. Thus, molecules with higher mass ions (e.g., molecules comprising Mo-100) will exit the magnetic field at different locations and with different trajectories than lower mass ions (e.g., molecules comprising Mo-92 through Mo-98).

The higher mass ions (molecules comprising Mo-100) form the first ion stream 47 a. This first stream of ions 47a enters the first receiver 58 and is retained within the first receiver. Generally, ions having a mass corresponding to a desired isotope are received by the first receiver 58. The first receiver 58 may, for example, comprise a cooling plate on which the gas molecules condense or solidify. Alternatively, the first receiver may comprise a pump that pumps the gas molecules to a container.

The second ion stream 47b has a different trajectory and enters the second receiver 60. The second stream of ions, consisting of low mass ions, is retained in the second receiver 60. Typically, ions having a mass that does not correspond to the desired isotope are received by the second receiver 60. The second receiver 60 may for example comprise a cooling plate on which the gas molecules condense or solidify on the second receiver 60. Alternatively, the second receiver may comprise a pump to pump the gas molecules to a container.

In this way, the enrichment device 4 separates the molecules comprising Mo-100 from the molecules comprising Mo-92 to Mo-98. In other words, an enrichment of molybdenum is achieved, which increases the percentage of Mo-100. The enriched molybdenum forms part of the target 32, which is described elsewhere in this document.

As will be understood from equations (1) and (2), the wavelength of the radiation beam B output from the undulator 16 may be selected via appropriate selection of the period of the undulator magnetic field, or the lorentz factor of the electrons (determined by their energy). As noted elsewhere in this document, there is a wide range of tens of MeV where electrons can be incident on Mo-100 and still provide a reasonably efficient transition to Mo-99. Thus, if the enrichment of molybdenum requires a specific wavelength of the beam B of infrared radiation, the energy of the electron beam E may be adjusted until a radiation beam having said wavelength is generated by the undulator 16. Adjusting the energy of the electron beam E is significantly easier than adjusting the periodicity of the undulator. The energy of the electron beam E can be adjusted by adjusting the power delivered to the accelerator 10. The adjustment may be controlled by a controller (not depicted). The controller may receive feedback indicative of the wavelength of the radiation beam and may operate using a feedback loop to maintain the wavelength of the radiation beam at a desired wavelength.

An alternative enrichment apparatus is schematically illustrated in figure 3. In an alternative enrichment arrangement, the molybdenum flow generator 44 includes a vessel 54 and a nozzle 56, the molybdenum flow generator 44 for providing gaseous molybdenum-containing molecules (e.g., MoO)₃Or MoF₆) Stream 70 of (a). Generally, the generator 44 is configured to generate a molecular stream and may be referred to as a molecular stream generator. The radiation beam B intersects the flow 70. The wavelength of the radiation beam is chosen such that it excites a specific isotope of molybdenum (e.g. Mo-100). That is, the wavelength of the radiation beam B corresponds to atomic transitions of the isotope but not atomic transitions of other isotopes, and is therefore preferentially absorbed by the isotope. Isotopes that preferentially absorb the radiation beam B, such as Mo-100, are excited and thus vibrate more. This results in the molecules containing the isotope being offset from the central axis of the flow of molybdenum-containing molecules. As a result, the flow 70 includes a first portion 70a that diverges or diverges at the same rate as upstream of the radiation beam B and a second portion 70B that diverges or diverges at a greater rate than upstream of the radiation beam B.

The first receiver 72 is arranged to receive the second portion 70b of the molecular stream. The first receiver 72 may include an annular opening. The first receiver 72 may be generally annular. The central receiver 74 is arranged to receive said first portion 70a of the flow molecules. The central receiver 74 may be referred to as a second receiver. In this way, isotopes such as Mo-100 can be separated from other isotopes such as Mo-92 through Mo-98.

The first receiver 72 may, for example, comprise a cooling plate on which molecules containing the desired isotope condense or solidify. Alternatively, the first receiver 72 may include a pump that pumps molecules containing the desired isotope to a container. The second receiver 74 may, for example, comprise a cold plate on which other molecules condense or solidify. Alternatively, the second receiver 74 may comprise a pump to pump other molecules to the container.

The enrichment apparatus depicted in fig. 3 uses a radiation beam B with a well controlled wavelength. That is, the wavelength is controlled sufficiently accurately to ensure that it excites primarily one molybdenum isotope but not the other. The electron injector 8, accelerator 10 and undulator 16 (which together may comprise a free electron laser) provide good stability and adjustability and are thus capable of providing a radiation beam B having a desired wavelength that is sufficiently well controlled. As noted above, the wavelength of the radiation beam B may be controlled by adjusting the power delivered to the accelerator 10.

The electron orbitals of Mo-100 differ most strongly from those of Mo-92 to Mo-98 close to the nucleus. The energy of these electron orbitals corresponds to a shorter wavelength than infrared radiation. For this reason, the radiation beam B may have a shorter wavelength than infrared radiation (e.g. ultraviolet radiation). For example, the beam of ultraviolet radiation may be generated by applying a non-linear effect, such as frequency doubling, to the infrared beam (e.g., using one or more frequency doubling crystals).

In the embodiment depicted in fig. 1, an electron beam splitter 12 is used for splitting the electron beam E. In addition to splitting the electron beam, the electron beam splitter 12 also separates the electron beam E from the infrared radiation beam B. In an alternative arrangement (not depicted), a magnet may be used to bend the path of the electron beam E such that the electron beam bends away from the infrared radiation beam B. In this way, the electron beam E and the infrared radiation beam B can be separated.

Although the above description relates to the enrichment of molybdenum, embodiments of the invention may also be used for the enrichment of other materials, such as uranium, for example.

In an embodiment, the electron injector 8, accelerator 10, and undulator 16 may be configured to provide an electron beam E having a current of 10mA or greater. For example, the current may be up to 100mA or more. The electron beam E having a high current (e.g., 10mA or more) is advantageous because it increases the specific activity or radioactivity of the radioisotope generated by the radioisotope generation apparatus 6.

As explained further above, Mo-100 can be converted to Mo-99 (a desired radioisotope) using very hard X-ray photons generated by an electron beam hitting an electron target. The half-life of Mo-99 was 66 hours. Because of this half-life, there is a limit to the specific activity of Mo-99 that can be provided when starting with Mo-100, which is determined by the rate at which Mo-99 is produced. If Mo-99 is produced at a relatively low rate, for example using an electron beam current of about 1 to 3mA, it may not be possible to provide a specific activity of Mo-99 greater than about 40Ci/g in the target. This is because although the irradiation time may be increased to allow more Mo-99 atoms to be produced, a significant portion of those atoms will decay during the irradiation time. In Europe, the threshold value for the specific activity of Mo-99 for medical applications should be 100Ci/g, and thus Mo-99 having a specific activity of 40Ci/g or less is not applicable.

When a higher electron beam current is used, the rate of Mo-99 atoms produced is correspondingly increased (assuming that the volume of Mo-99 that receives a photon remains the same). Thus, for example, for a given volume of Mo-99, a beam current of 10mA will produce Mo-99 at 10 times the production rate provided by a beam current of 1 mA. The beam current used by embodiments of the present invention may be high enough to achieve a specific activity of Mo-99 in excess of 100 Ci/g. For example, embodiments of the present invention may provide an electron beam having a beam current of about 30 mA. Simulations indicate that for a beam current of about 30mA, if the electron beam has an energy of about 35MeV and the volume of the Mo-100 target is about 5000mm³Then can obtainThe specific activity of Mo-99 exceeding 100Ci/g is obtained. The Mo-100 target may, for example, comprise 20 plates having a diameter of about 25mm and a thickness of about 0.5 mm. Other numbers of plates may be used, which may have non-circular shapes and may have other thicknesses.

The embodiments may also be described using the following aspects:

1. a combined enrichment and radioisotope production facility, comprising:

an electron source arranged to provide an electron beam, the electron source comprising an electron injector and an accelerator;

an undulator configured to generate a radiation beam by using the electron beam;

a molecular flow generator configured to provide a molecular flow that intersects a radiation beam;

a receiver configured to receive molecules or ions selectively received from a stream of molecules; and

a target support structure configured to hold a target on which the electron beam is incident, in use.

2. The apparatus of aspect 1, wherein the beam of radiation is configured to at least partially ionize the molecular stream.

3. The device of aspect 2, wherein the device further comprises a magnet configured to generate a magnetic field traversed by the at least partially ionized molecular stream.

4. The device according to aspects 2 or 3, wherein the device further comprises electrodes configured to generate an electric field that is traversed by the at least partially ionized molecular stream.

5. The apparatus of aspects 3 or 4, wherein the receiver is a first receiver of two or more receivers, the first receiver configured to receive ions having a mass corresponding to a desired isotope, a second receiver configured to receive other ions.

6. The apparatus of aspect 5, wherein the first receiver comprises a cold plate onto which the ions condense or freeze, or a pump that pumps the ions to the vessel.

7. The apparatus of any of aspects 2 to 6, wherein the radiation beam is an infrared radiation beam.

8. The apparatus of aspect 1, wherein the radiation beam is configured to excite a desired isotope in a molecular stream.

9. The apparatus of aspect 8, wherein the receiver is a first receiver in the two or more containers, the first receiver configured to receive molecules comprising the excited desired isotope, and a second receiver configured to receive other molecules.

10. The apparatus of aspect 9, wherein the first receiver comprises an annular opening configured to receive molecules comprising the excited desired isotope.

11. The apparatus of aspect 9 or 10, wherein the first receiver comprises a cold plate to which molecules containing the desired isotope condense or solidify, or a pump that pumps molecules containing the desired isotope to a container.

12. The apparatus according to any one of aspects 8 to 11, wherein the radiation beam is an ultraviolet radiation beam.

13. The apparatus according to any preceding aspect, wherein the apparatus further comprises a controller configured to control the wavelength of the radiation beam by adjusting the power delivered to the accelerator.

14. A method of combined enrichment and radioisotope production, comprising:

providing an electron beam using an electron injector and an accelerator;

generating a beam of radiation with the electron beam using an undulator;

providing a molecular stream that intersects the radiation beam;

selectively receiving molecules or ions from the molecular stream containing the desired isotope in a receiver; and

an electron beam is directed onto a target containing a desired isotope to produce a radioisotope.

15. The method of aspect 14, wherein the method further comprises: extracting isotopes received in the receiver and using the isotopes to form subsequent targets on which the electron beam is incident.

16. The method of aspect 14 or 15, wherein the electron beam has an energy of about 14MeV or greater.

17. The method according to any one of aspects 14 to 16, wherein the radiation beam at least partially ionizes the molecular stream, and wherein the at least partially ionized molecular stream subsequently passes through a magnetic and/or electric field that alters the trajectory of the ion according to the mass of the ion.

18. The method of aspect 17, wherein ions having a mass corresponding to a desired isotope are received in the first receiver.

19. The method according to any one of aspects 14 to 16, wherein the radiation beam excites a desired isotope in the molecular stream, and wherein molecules containing the desired isotope are subsequently deflected away from other molecules in the molecular stream.

20. The method of aspect 19, wherein the molecule comprising the desired isotope is received in a first receiver.

As further noted above, the electron injector of embodiments of the present invention may be a photocathode illuminated by a pulsed laser beam. The laser may, for example, comprise a Nd: YAG laser and associated optical amplifier. The laser may be configured to generate picosecond laser pulses. The current of the electron beam can be adjusted by adjusting the power of the pulsed laser beam. For example, increasing the power of the pulsed laser beam will increase the number of electrons emitted from the photocathode and thereby increase the beam current.

The electron beam E used by the radioisotope production apparatus 6 according to an embodiment of the present invention may, for example, have a diameter of 1mm and a divergence or deviation of 1 mrad. Increasing the current in the electron beam E will cause the electrons to spread out due to space charge effects and thus may increase the diameter of the electron beam. Therefore, increasing the current of the electron beam may decrease the brightness of the electron beam. However, the radioisotope production apparatus 6 does not need the electron beam E having a diameter of, for example, 1mm, and an electron beam having a larger diameter may be utilized. Thus, increasing the current of the electron beam may not reduce the brightness of the beam to a level that significantly adversely affects radioisotope production. In fact, it may be advantageous to provide an electron beam having a diameter larger than 1mm, since it disperses the thermal load transferred by the electron beam. However, it will be understood that other types of injectors may be used.

Although embodiments of the present invention have been described in connection with the production of the radioisotope Mo-99, embodiments of the present invention may be used to produce other radioisotopes. In general, embodiments of the present invention may be used to generate any radioisotope that may be formed on a source material via the direction of very hard X-rays.

An advantage of the present invention is that it provides for the production of radioisotopes without the need for the use of high-throughput nuclear reactors. Another advantage is that it does not require the use of highly enriched uranium, a hazardous material subject to diffusion-prevention regulations.

Although embodiments of the present invention have been described as using Mo-100 to produce a Mo-99 radioisotope that decays to Tc-99, embodiments of the present invention may be used to produce other medically useful radioisotopes. For example, embodiments of the present invention may be used to produce Ge-68, which decays to Ga-68. Embodiments of the present invention can be used to produce W-188, which decays to Re-188. Embodiments of the present invention can be used to produce Ac-225, which decays to Bi-213, Sc-47, Cu-64, Pd-103, Rh-103m, In-111, I-123, Sm-153, Er-169, and Re-186.

Embodiments of the invention have been described in the context of a free electron laser FEL outputting a beam of infrared radiation. However, the free electron laser FEL may be configured to output radiation having any wavelength. Accordingly, some embodiments of the invention may include a free electron laser that outputs a radiation beam that is not a beam of infrared radiation.

The different embodiments may be combined with each other. Features of embodiments may be combined with features of other embodiments.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not restrictive. Accordingly, it will be apparent to one skilled in the art that modifications may be made to the invention without departing from the scope of the claims set out below.