Remotely operated system to deploy and recover materials into and from a nuclear fusion plant

Abstract

The present invention relates to a remotely operated system (200) to deploy and recover materials (25) into and from a nuclear fusion device (100), for the purpose of exposing said materials (25) to neutron radiation, which will cause the generation of radioactive isotopes, comprising at least one loop made of pipes (14) with constant inner diameter, a plurality of capsules (23) with an outer diameter slightly smaller than the inner diameter of the at least one loop (14), wherein the capsules (23) are adapted to contain the material (25) to be irradiated by the neutron radiation, a propulsion system for circulating the capsules (23) through the at least one loop (14), a remotely operated capsule filling system (18) for filling said capsules (23) into the at least one loop (14), and a remotely operated capsule recovery system (19) for recovering said capsules (23) from the at least one loop (14).

Description

[0001] Remotely operated system to deploy and recover materials into and from a nuclear fusion plant

[0002] Description

[0003] The present invention relates to a remotely operated system to deploy and recover materials into and from a nuclear fusion plant for the purpose of exposing said materials to neutron radiation, which will cause the generation of radioactive isotopes. The invention further relates to a nuclear fusion plant comprising a reactor and a system according to the present invention as well as a nuclear fusion tokamak with beam-driven plasma and a method for producing radioisotopes using a system according to the invention.

[0004] In other words, the technical field of the present invention specifically relates to the design, configuration and operation concept of a system to deploy and recover different precursor materials into and from a nuclear fusion plant, such as for example a fusion tokamak with beam-driven plasma, for the purpose of exposing these materials to the neutron flux generated in the plasma by the process of nuclear fusion of deuterium and tritium ions, for the purpose of generation radioactive isotopes.

[0005] It is known in the art that the production of radioisotopes requires the exposure of precursor materials to neutrons and that nuclear fusion devices are neutron sources with high flux rate. The plasma in such a nuclear fusion device is an intense neutron source if operated with deuterium, D, and Tritium, T. The specific technical concept of one type of nuclear fusion device, namely a nuclear fusion tokamak with beam-driven plasma, is described in [1], while the principal possibility to produce radioisotopes in a nuclear fusion device is presented in [2], The authors of [2] consider a large nuclear fusion device called DEMO where the very high temperature in the plasma causes the fusion of D and T ions. Since most of the inner wall of DEMO that is exposed to neutron radiation must be used to breed DEMO's tritium fuel from lithium, the authors of [2] consider for the deployment of the precursor materials a port plug with a comparably small surface exposed to the neutron flux. Furthermore, the authors of [2] consider for the deployment and recovery of the precursor materials irradiation rods resembling the fuel rods of fission reactors.

[0006] A fusion power plant is based on a nuclear fusion device. The main function of such a fusion power plant is to generate energy in the plasma by fusion of deuterium, D, and tritium, T. 80% of this energy is contained in 14 MeV neutrons, which create an intense neutron flux on the so-called “wall” i.e. , the plasma-facing surfaces of the core components that are installed inside the plasma vessel enclosing the plasma. In proposed fusion power plants, most of the wall surface, approximately 85-90%, is made up of the breeding blanket, which contains breeding units. These in turn contain lithium from which tritium is produced by irradiation with neutrons to breed the reactor’s tritium fuel. Inside the breeding blanket, the neutron flux is most intense near to the plasma-facing side and decreases toward the backside of the breeding blanket as the neutrons are moderated and absorbed by the breeding blanket materials.

[0007] Further reference is made to prior art document PCT / EP2024 / 076727 (“Radioisotope production in a nuclear fusion tokamak” filed on 24.09.2024) which relates to the design, configuration and operation concept of a system, called radioisotope recovery system, to deploy and recover different precursor materials into and from the core of a nuclear fusion tokamak with beam-driven plasma for the purpose of exposing these materials to the neutron flux generated in the plasma by the process of nuclear fusion of deuterium and tritium ions, which will cause the generation of radioactive isotopes (also called radioisotopes).

[0008] In a nuclear fusion tokamak with beam-driven plasma as considered in PCT / EP2024 / 076727, it is foreseen to integrate fusion nuclear components for the purpose of testing and qualification on the outboard side of the torus-shaped plasma vessel. On the inboard side, instead a blanket with neutron absorbing materials is integrated due to design constraints of such tokamaks. While it is thus established to include static blankets containing lithium close to the core of nuclear fusion plants in order to breed tritium from said lithium targets, it has been found that the high neutron flux close to the reactor core of a nuclear fusion plant may also be used for producing different isotopes than tritium which could be used in a wide array of applications, such as medical radiotherapy etc. In contrast to lithium targets which require a high fraction of the available volume in the fusion reactor wall, typically more than 60-90%, in order to produce tritium in relevant quantities, it has been found by the inventors of the present invention that when producing radioisotopes other than tritium, different assumptions can be made and a highest possible conversion rate is not necessary to produce useful quantities of radioactivity containing said produced radioisotopes. Therefore, a different approach as compared to lithium targets within blankets can be employed and it is an object of the present invention to provide a remotely operated system with closed loops in which such a production of radioisotopes can be achieved in a cost-effective and safe manner.

[0009] For these purposes, the system according to the present invention comprises at least one loop made of pipes with constant inner diameter, a plurality of capsules with an outer diameter slightly smaller than the inner diameter of the at least one loop, wherein the capsules are adapted to contain the material to be irradiated by the neutron radiation, a remotely operated propulsion system for circulating the capsules through the at least one loop, a remotely operated capsule filling system for filling said capsules into the at least one loop, and a remotely operated capsule recovery system for recovering said capsules from the at least one loop. Herein, the remotely operated propulsion system may for example be implemented by a remotely operated pump for providing pressurized liquid or gas to the at least one loop or by a device causing direct mechanical movement of the capsules such as a carriage-rail system.

[0010] Thus, the present invention relies on circulating targets in the form of capsules instead of using fixed blankets which not only increases the flexibility concerning the amount of neutron radiation a given target is exposed to but rather also vastly facilitates the extraction from the reactor core and the handling of said capsule targets in that they can automatically be introduced and recovered from the at least one loop outside the reactor by the capsule filling and capsule recovery systems, respectively. This invention therefore adds to the system described in PCT / EP2024 / 076727 a system that may also deploy and recover precursor materials in inboard blankets without compromising their neutron absorbing function. As an option, the present invention could additionally or alternatively be implemented also to the outboard blankets.

[0011] In particular, in the system according to the present invention, the capsules may be made of a metallic material, in particular stainless steel, which facilitates their handling and allows for a relatively cheap mass production of said capsules. In order to ensure smooth movement of the capsules inside the at least one loop and to prevent congestion, the capsules may be of spherical shape or of cylindrical shape, in particular with hemi-spherical end regions.

[0012] In order to control the irradiation of the precursor material, the flow velocity of the liquid and / or an exposure time of the capsules may be adjustable. For this purpose, suitable sensor units may be positioned at or close to the at least one loop of the system according to the invention such that the activation of the material due to neutron caption may be adequately controlled and the corresponding capsules may be extracted from the system once a desired activation level has been reached.

[0013] While in theory, the system according to the present invention could be operated in an intermittent manner, such that a number of capsules may be moved to respective positions in the at least one loop, at which they may be exposed to neutron radiation for a given time and subsequently moved further down the at least one loop until they reach the capsule recovery system, in an alternative embodiment the system may also be adopted for continuous circulation of the capsules within the at least one loop, such that the capsules are constantly in motion within the at least one loop during operation of the system. In this context, the at least one loop may be provided with inlet and outlet gates such that capsules may for example circulate within an active part of the loop close to a reactor of a corresponding nuclear fusion device for a given time before they are extracted therefrom via such an outlet gate and subsequently transported to the capsule recovery system where they are finally extracted from the at least one loop overall.

[0014] While the system according to the present invention may in principle be used and combined with different types of neutron sources, the present invention specifically also relates to a nuclear fusion plant, in particular a nuclear fusion tokamak with beam-driven plasma, comprising a reactor and at least one system according to the present invention. Such nuclear fusion plants typically comprise a so-called “bioshield” as a means to reduce radiation outside the active part of the reactor, usually comprising concrete and other suitable materials for absorbing radiation. In order to further facilitate the handling of the capsules in the system according to the present invention, the propulsion system, the capsule filling system and / or the capsule recovery system may in such cases be positioned outside said bio shield, such that regular access to said systems and components is facilitated.

[0015] In contrast, the at least one loop may at least partially be integrated into the reactor, in particular into a blanket on an inboard and / or an outboard side of the reactor.

[0016] Furthermore, a nuclear fusion plant according to the present invention may comprise a plurality of systems according to the invention, wherein the respective loops of said systems may be arranged such that the energy spectra and / or flux intensities of the incident neutron radiation differ between the systems. Thus, it for example becomes possible to assign different precursor materials to the individual systems in order to optimize the yield of neutron capture reactions and / or to adjust the respective flux intensities of the radiation acting on the precursor materials in the individual systems.

[0017] According to a further aspect, the present invention also relates to a nuclear fusion tokamak with beam-driven plasma, comprising a plurality of blankets around its reactor core, wherein in at least some of the blankets, capsules containing material to be exposed to neutron radiation are incorporated in order to produce radioactive isotopes other than tritium. While it has been known in the prior art to produce tritium from lithium in blankets around reactor cores of different types of nuclear fusion plants, it is a novel idea to use such blankets in order to produce radioactive isotopes other than tritium in nuclear fusion tokamak with beam-driven plasma reactors. For this purpose, independent protection is sought for this aspect of the present invention as well.

[0018] Lastly, the present invention relates to a method for producing isotopes using a system according to the present invention in a nuclear fusion plant according to the present invention, comprising the steps of operating the nuclear fusion plant in order to produce neutron radiation, operating the capsule filling system for filling capsules into the at least one loop, operating the propulsion system to circulate the capsules within the at least one loop, and recovering the capsules after a given radiation time from the at least one loop by means of the capsule recovery system.

[0019] In particular and as already briefly mentioned above, the propulsion system in such a method may be operating in a continuous manner during operation of the system and / or may be adjustable with respect to its flow rate.

[0020] Further features and benefits of the present invention will become even clearer from the following description of embodiments thereof, when viewed together with the accompanying drawings. These show in particular:

[0021] Figure 1 a schematic cross-section view of a first embodiment of a nuclear fusion plant according to the present invention, comprising a remotely operated system for producing radioisotopes;

[0022] Figure 2 an isometric view of certain components of the system of Figure 1 ;

[0023] Figure 3 a section of a pipe of the system of Figures 1 and 2; Figure 4 a schematic exploded view of a capsule used in the system of Figures 1 to 3;

[0024] Figure 5 a schematic cross-section view of a second embodiment of a nuclear fusion plant according to the present invention, comprising a remotely operated system for producing radioisotopes;

[0025] Figure 6 a detailed view of an extension pipe used in the system of the plant of Figure 5; and

[0026] Figure 7 a schematic cross-section view of a nuclear fusion tokamak with beam-driven plasma reactor according to the present invention.

[0027] Figure 1 shows a schematic cross-section view of a first embodiment of a nuclear fusion plant 100 according to the present invention, which is housed inside a reactor building 1 and comprises a bioshield 4. Figures 2 and 3 show further detailed views of certain components of the plant 100. Said nuclear fusion power plant 100 also comprises a remotely operated system 200 for producing radioisotopes, herein also referred to as a radioisotope recovery system, which has several of its components positioned outside the bioshield 4 and in particular inside a port cell 2, which is accessible through a revolving door 3, as will be explained in detail below.

[0028] The nuclear fusion plant 100 has the principle layout of a tokamak with beam- driven plasma with a torus-shaped plasma vessel 6 as known in the art. During operation of the nuclear fusion plant 100, a nuclear fusion process such as D-T-fu- sion takes place inside the plasma vessel 6 and large numbers of free neutrons are produced, as schematically shown in Figure 1.

[0029] The plasma vessel 6 on its upper side is formed with an upper port 5 and closed by means of a closure plate 7 in order to be able to achieve a high vacuum inside the plasma vessel 6. It is also foreseen to integrate fusion nuclear components for the purpose of testing and qualification on an outboard side 8 of the torus-shaped plasma vessel 6, while on the inboard side 9 a blanket 10 with neutron absorbing materials 17 is integrated due to design constraints of such tokamaks.

[0030] The present invention adds to tokamaks known in the art the above-mentioned system 200 that deploys and recovers precursor materials in the inboard blankets 10 without compromising their neutron absorbing function. In a further variant of the present invention, similar components of the invention could be implemented to at least some of the outboard blankets.

[0031] The radioisotope recovery system 200 comprises a closed loop of pipes 14 with constant inner diameter, in which a pressurized liquid medium 24, e.g. water, can flow. The system 200 further comprises auxiliary components operating the loop 14 such as a low flow pump 20 and other auxiliary system as well as metallic capsules 23 floating in the liquid medium inside the pipe. In this particular example, the pump 20 serves as a propulsion system for causing a circulation of the capsules 23 in the loop 14, whereas in alternative variants, said propulsion system may also be embodied by a gas pump or a fully mechanical system directly acting on the capsules 23.

[0032] The shape of the capsules 23 in the present embodiment is spherical or cylindrical with rounded comers to prevent jamming of the capsules 23 inside the loop 14. The pipe connects the auxiliary components to the blanket 10 and is welded to an extension pipe 15 that is integrated into the blanket in multiple bends 22 behind the blanket first wall 16 where the neutron flux produced in the fusion reaction is intense. The auxiliary components of the loop 14 are located outside the bioshield 4 of the plant 100 in areas protected from excessive neutron and gamma radiation and accessible by remote controlled tools or personnel.

[0033] The auxiliary components include a system 19 to recover the metallic capsules from the loop upon completion of an irradiation period, a system 18 to fill metallic capsules into the loop with new precursor materials 25, the pump 20, valves 21 and other parts. These auxiliary components are operated semi-automatically through tools that are controlled by an operator 11 located in a control room 12 outside the reactor building 1 . For example, both the capsule filling system 18 and the capsule recovery system 19 may comprise robotic arms and camera systems which facilitate the operation thereof. Also, different levels of autonomous operation are conceivable for said systems, from fully autonomous components in which the operator 11 may only need to intervene in case of problems or unforeseen events, to fully remotely controlled components which are dependent on manual instructions issued by the operator 11 .

[0034] The transfer of the metallic capsules 23 between the port cell 2 and the active maintenance facility is carried out making use of the transfer system and related installations for the remote replacement of the blankets implemented in the reactor building 1 and adjacent buildings of the facility.

[0035] The metallic capsules 23 are transported to and picked up from the port cell 2 by a remotely controlled vehicle that can enter and exit into the port cell through a rotating door 3 with sealing function or by means of other remotely operated systems such as conveyer systems or the like. The preparation of the metallic capsules 23 with precursor materials 25 and their recovery after irradiation is carried out in the active maintenance facility, which may be in a separate building adjacent to the reactor building 1 or within the reactor building 1 . Reference is made to Figure 4 for a schematic exploded view of such a capsule 23.

[0036] The liquid medium 24 inside the closed loop 14 is continuously circulated through the operation of the low flow pump 20. This causes the metallic capsules 23 to also continuously circulate through the loop 14. In different parts of the loop 14, they are exposed to different levels of neutron flux. Over the time of the irradiation period, however, a uniform irradiation of the precursor materials 25 in the different capsules 23 is obtained. Due to the continuous circulation of the metallic capsules 25 in the loop 14 during the irradiation period, they are naturally extracted from the reactor core and transported outside of the bioshield 4. Their recovery from the loop 14 is possible within hours after the completion of the irradiation period because neither the plasma vessel 6 nor the bioshield 4 must be opened for access. Consequently, the present invention allows the production also of radioisotopes with short half-lives of the order of hours or days, which would substantially decay if the recovery from the capsules took too long, e.g. several days.

[0037] A nuclear fusion tokamak is generally built of several, e.g. 12, sectors forming its 360° torus, wherein in each sector there are two inboard blankets 10. Therefore, several, e.g. 24, radioisotope recovery systems 200 can be installed that can operate independently and with operating parameters customized to the neutron exposure requirements of different precursor materials 25. The configuration and integration of the respective loop's pipe 14 connecting the blanket 10 with the auxiliary components penetrates the wall of the upper port 5 rather than the removable port closure plate 7 and therefore is compliant with the upper port remote described in [3], i.e. with the maintenance concept of the blanket.

[0038] Further reference shall now be made to Figures 5 and 6 which show a schematic cross-section view of a second embodiment of a nuclear fusion plant 100’ according to the present invention, comprising a remotely operated system 200’ for producing radioisotopes, and a detailed view of an extension pipe used in the system of the plant of Figure 5, respectively. It shall be noted that all reference numerals associated with said second embodiment are provided with apostrophes in order to differentiate them from the corresponding components of the first embodiment shown in Figures 1 to 3.

[0039] The fusion power plant radioisotope recovery system 200’ of said second embodiment is a closed loop consisting of a pipe 8’ and of auxiliary components operating the loop such as a pump 14’ serving as an example for a propulsion system and other auxiliary components. Similar to the first embodiment, spherical metal capsules containing the radioisotope precursor materials are inside the pipe 8’ and are circulated in the loop. The pipe connects the auxiliary components to an extension pipe 9’ that is integrated inside the reactor in several bends.

[0040] This second embodiment is explained in detail in order to introduce three alternative or complementary integration concepts for the extension pipe: (a) The extension pipe 9’ is routed inside a breeding blanket 4’ surrounding the plasma vessel 3’ to utilize the intense neutron flux and the large volume of the breeding blanket 4’. The extension pipe 9’ can be located either behind the first wall 5’ of the breeding blanket 4’ where the neutron flux is most intense or in the backside 7’ of the breeding blanket 4’ behind the breeding units 6’, where the impact on the breeding blanket 4’ design is low. The number of bends of the extension pipe 9’ is limited occupying only a small portion of the breeding blanket volume so as not to compromise the production of tritium.

[0041] (b) The extension pipe 10’ is routed on the inner plasma vessel wall in the interspace between the breeding blanket 4’ and the plasma vessel 3’.

[0042] (c) The extension pipe 1 T is routed inside the internal volume of the plasma vessel structure 11 .

[0043] The choice of the integration concept affects the neutron spectrum and neutron flux intensity the precursor materials are exposed to and therefore depends on the requirements for the production of the specific radioisotopes. Similar as with the first embodiment, the auxiliary components of the loop are located outside the bioshield 2’ of the fusion power plant 100’ in areas protected from excessive neutron and gamma radiation and accessible by remotely operated tools or personnel. The auxiliary components include a system 13’ for recovering the spherical capsules from the loop at the end of an irradiation period, a system 12’ for filling the loop with new spherical capsules with new precursor materials, valves 15’ and a pump 14’, whose function is to circulate the spherical capsules in the loop. In the present second embodiment, these auxiliary components are operated semi-auto- matically by tools that are controlled by an operator located in a control room outside the reactor building T.

[0044] A fusion power plant typically is built up of segmented structures, e.g. the tritium breeding blanket 4’ is divided into multiple breeding blanket segments, e.g. 80. Therefore, several, e.g. 80, radioisotope recovery systems 200’ of the second embodiment can be installed in a fusion power plant, operating independently and with operating parameters tailored to the neutron exposure requirements of different precursor materials.

[0045] Lastly, reference shall be made to Figure 7, which shows a schematic cross-section view of a nuclear fusion tokamak with beam-driven plasma reactor 300 according to the present invention. Therein, there is proposed the replacement of some of the neutron absorbing materials 303 inside the blankets 302 that surround the plasma 301 with precursor materials 304 for the production of radioactive isotopes, herein called radioisotopes, other than tritium. Numerous pieces of precursor materials are contained inside metallic capsules, which are incorporated into the blankets 302 in a manner that allows their retrieval without the removal of the blankets 302 from the reactor core. While the nuclear fusion tokamak with beam- driven plasma reactor 300 is operated, these materials are exposed to the intense neutron flux generated by the plasma. After a certain time, the capsules containing the precursor materials including the generated radioisotopes are recovered for commercial use.

[0046] While it has been known in the prior art to produce tritium from lithium in blankets around reactor cores of different types of nuclear fusion plants, it is a novel idea to use such blankets in order to produce radioactive isotopes other than tritium in nuclear fusion tokamak with beam-driven plasma reactors 300, such that Figure 7 shows such a reactor 300, comprising a reactor building 308 with a plasma vessel 305, magnet coils 306 for containing the plasma 301 inside the plasma vessel 305 and neutral beam injector 307 for heating the plasma 301 . For reference the plasma major radius and plasma minor radius are denoted with reference numerals 309 and 310, respectively.

[0047] Reference signs (first embodiment):

[0048] (1 ) Reactor building

[0049] (2) Port cell

[0050] (3) Rotating door

[0051] (4) Bioshield

[0052] (5) Upper port (6) Plasma vessel

[0053] (7) Closure plate

[0054] (8) Outboard side

[0055] (9) Inboard side

[0056] (10) Inboard blanket

[0057] (11 ) Operator

[0058] (12) Control room

[0059] (13) Port plug

[0060] (14) Loop of pipes

[0061] (15) Extension pipe

[0062] (16) First wall

[0063] (17) Neutron absorbing materials

[0064] (18) Capsule refill system

[0065] (19) Capsule recovery system

[0066] (20) Pump (Propulsion system)

[0067] (21 ) Valves

[0068] (22) Bend

[0069] (23) Metallic capsule

[0070] (24) Liquid media

[0071] (25) Precursor material

[0072] Reference signs (second embodiment):

[0073] (T) Reactor building

[0074] (2’) Reactor building bioshield

[0075] (3’) Plasma vessel

[0076] (4’) Tritium breeding blanket segment

[0077] (5’) Breeding blanket first wall

[0078] (6’) Breeding blanket breeding units

[0079] (7’) Breeding blanket backside

[0080] (8’) Pipe

[0081] (9’) Extension pipe - two options inside the breeding blanket

[0082] (10’) Extension pipe - behind the breeding blanket on the internal surface of the plasma vessel (1 T) Extension pipe - within the reactor plasma structure

[0083] (12’) Capsule refill system

[0084] (13’) Capsule recovery system

[0085] (14‘) Pump (Propulsion system)

[0086] (15‘) Valves

[0087] (16‘) Plasma fusion tokamak with beam-driven plasma^

[0088] (301 ) Plasma

[0089] (302) Blanket

[0090] (303) Neutron absorbing materials

[0091] (304) Potential areas for deployment of precursor materials (indicative)

[0092] (305) Plasma vessel

[0093] (306) Magnet coil

[0094] (307) Neutral beam injector

[0095] (308) Reactor building

[0096] (309) Plasma major radius

[0097] (310) 2 x plasma minor radius

[0098] Definitions and references

[0099] Tokamak: A device which uses a magnetic field generated by external magnets and by a toroidal current in the plasma itself to confine plasma in the shape of an axially symmetrical torus. plasma whose hydrogen species are deuterium D, and tritium, T, rather than hydrogen, H. The ion particles of a D-T plasma consist of more than

[0100] 80% of D and T in similar proportions. The remaining few percent of plasma ions are impurities of other elements such as helium, tungsten, inert gases, and others.

[0101] Nuclear fusion device: "Nuclear fusion device" is an umbrella term for nuclear fusion tokamak, in that it does not specify the type of fusion device. Well-known types of fusion devices include tokamak, stellarator, and inertial fusion devices. Subspecies of “nuclear fusion device” are “nuclear fusion tokamak” and “nuclear fusion tokamak with beam-driven plasma”. "Nuclear fusion device" is a subspecies of “fusion device” that is distinguished in that it produces neutrons by the fusion of D and T ions in its plasma. The fusion of D and T ions releases energy and generates neutrons since the deuterium-tritium reaction releases a free neutron. Fusion of two particles, such as D and T ions, occurs when they collide, and their energy is sufficiently high to overcome the repulsive electrostatic force or “Coulomb barrier”. Since the energy of the particles depends on their temperature, their temperature needs to be sufficiently high.

[0102] Nuclear fusion tokamak: A nuclear fusion tokamak is a subspecies of the “nuclear fusion device”. A nuclear fusion tokamak is also a subspecies of “tokamak” that differs in that it produces neutrons by the fusion of D and T ions in its plasma.

[0103] Nuclear fusion tokamak with beam-driven plasma: A nuclear fusion tokamak with beam-driven plasma is a subspecies of a nuclear fusion tokamak in that the triple product is lower than 5e20 keV s / m3, comparable to that reached in the plasmas tested in fusion experimental devices such as ASDEX-Upgrade. Instead, the ITER experimental tokamak aims at generating for the first time ever a magnetically confined plasma with positive energy balance. The lower triple product of a beam-driven plasma distinguishes it from the plasma of a fusion power plant or of ITER.

[0104] For fusion of D and T to occur in a beam-driven plasma at a sufficiently high rate to generate a high neutron flux, it is relied on external plasma heating systems that inject into the plasma particles with a higher temperature than that of the plasma particles and / or to locally increase the temperature of the plasma particles, typically through resonance heating. More than half of the D-T fusion reactions in a beam- driven plasma of a nuclear fusion tokamak occur due to the effects caused by external plasma heating systems. Less than half of the total fusion power in a beam- driven plasma occurs because of the small fraction of the plasma particles that have a sufficiently high temperature for fusion to occur. Nuclear fusion : A nuclear fusion plant is a facility whose reactor is a nuclear fusion device.

[0105] Fusion :: A fusion power plant is an industrial facility whose primary purpose is to generate electricity and whose reactor is a nuclear fusion device. In the plasma of the nuclear fusion device of a fusion power plant more power is generated through fusion reactions than it loses through radiation and conduction losses. This plasma reaches a positive energy balance i.e. the product of the temperature of the plasma particles, their density i.e. number of particles per volume, and their confinement time i.e. the length of time for which particles are confined within the plasma must be sufficiently high to meet the Lawson criteria1. For the deuterium-tritium reaction, this so-called triple product must be at least 3e21 keV s / m3for a plasma to be considered “hot” or “burning”.

[0106] The maximum temperature of magnetically confined plasmas occurs in the core of the plasma while on the plasma edge the temperature is lower. Regarding the occurrence of fusion, the relevant temperature of a plasma is the maximum temperature in its core. The temperature of the plasma particles in the core is not homogeneous but has a Gaussian distribution. The fraction of the plasma particles with a sufficiently high temperature for fusion to occur depends on the mean temperature in the plasma core.

[0107] 1: J D Lawson: Some Criteria for a Power Producing Thermonuclear Reactor. In: Proceedings of the Physical Society. Section B. Band 70, Nr. 1 , 1. Januar 1957 Actinoids encompass the 14 metallic chemical elements in the 5f series, with atomic numbers from 89 to 102, actinium through nobelium, containing Uranium, Thorium and Plutonium. All actinoids are radioactive.

[0108]

[0001] Federici, Gianfranco. "Testing needs for the development and qualification of a breeding blanket for DEMO." Nuclear Fusion 63.12 (2023): 125002. doi:

[0109] 10.1088 / 1741 -4326 / adOOcb [2] Pereslavtsev, P.; Bachmann, C.; Elbez-Uzan, J.; Park, J.H. Potential of Radioactive Isotopes Production in DEMO for Commercial Use. Appl. Sci. 2024, 14, 442. https: / / doi.Org / 10.3390 / app14010442

[0110] [3] Mozzillo, Rocco, et al. "Replacement strategy of the EU-DEMO and CFETR breeding blanket pipes." Fusion Engineering and Design 202 (2024): 114311 . https: / / d0i.0rg / l 0.1016 / i.fusengdes.2O24.114311

[0111] Items

[0112] The following items are to be considered expressions of the present invention covering one or more of the above-described embodiments each:

[0113] Iteml : A remotely operated system to deploy and recover different materials into and from the core of a nuclear fusion tokamak with beam-driven plasma, herein called radioisotope recovery system, for the purpose of exposing these materials to neutrons, which will cause the generation of radioactive isotopes (also called radioisotopes), comprising:

[0114] • A loop with pressurized liquid e.g., water, made of stainless-steel pipes with constant inner diameter (approximately 10 mm).

[0115] • Metallic stainless-steel capsules (approximately 10,000 with external diameter somewhat smaller than the inner diameter of the pipe) stacked up inside the pipes of the loop.

[0116] • A remotely operated low-flow pump.

[0117] • A remotely operated system to fill metallic capsules into the pipe.

[0118] • A remotely operated system to recover the metallic capsules from the Pipe, wherein

[0119] • All components operating the loop i.e. , pump, capsule recovery and refill systems, valves, are located outside the bioshield, and therefore are located in areas (i) accessible by remote controlled tools or personnel, (ii) protected from excessive neutron and gamma radiation.

[0120] • The continuous operation of the loop i.e. circulation of the liquid with metallic capsules means each capsule passes multiple times through the blanket ensuring a homogeneous exposure to neutrons amongst all capsules of one loop.

[0121] • The system operation mode i.e. , flow velocity and time to recover the metallic capsules, can be customized to the production of radioisotopes from different precursor materials.

[0122] Item 2: The radioisotope recovery system according to Item 1 , wherein the pressurized liquid loop transports the metallic capsules reliably by avoiding blockage due to congestion through the following features: (i) the capsules are made of robust stainless steel, (ii) the external shape of metallic capsules and the internal shape of pipes are without major irregular geometries, (iii), equal or similar density of metallic capsules incl. precursor materialsand their container to the density of the transport liquid, (iv) conventional technologies used for components operating the loop e.g., pump, valves, etc.

[0123] Item 3: The radioisotope recovery system according to any of the preceding

[0124] Items, wherein the precursor materials are contained in metallic capsules that allow their transport in a pipe in a liquid media.

[0125] Item 4: The radioisotope recovery system according to any of the preceding

[0126] Items, wherein part of the loop's pipes are integrated into the neutron shielding blanket on the inboard side or optionally also on the outboard side of the nuclear fusion tokamak with beam-driven plasma.

[0127] Item 5: The radioisotope recovery system according to any of the preceding

[0128] Items, wherein the configuration of the loop's pipes that connect the components operating the loop with the blanket inside the plasma vessel is compatible with the maintenance of the blanket.

[0129] Item 6: The radioisotope recovery system according to any of the preceding

[0130] Items, wherein the auxiliary components of the loop requiring in-service maintenance and inspection are located outside the bioshield of the nuclear fusion tokamak with beam-driven plasma in areas protected from excessive neutron and gamma radiation and accessible by remote controlled tools or personnel.

[0131] Item 7: The radioisotope recovery system according to any of the preceding

[0132] Items, wherein the continuous circulation of the metallic capsules ensures a uniform exposure to neutron flux amongst the different capsules.

[0133] Item 8: The radioisotope recovery system according to any of the preceding

[0134] Items, wherein the circulation of the metallic capsules ensures the transport of the capsules from the reactor core outside the bioshield allowing for a recovery of the metallic capsules without major intervention and, possibly, not requiring the plasma to be shutdown.

[0135] Item 9: The radioisotope recovery system according to any of the preceding

[0136] Items, wherein the transfer of the metallic capsules between the port cell and the active maintenance facility is carried out making use of the transfer system and related installations implemented in the reactor building and adjacent buildings of the plant for the remote replacement of the blankets.

[0137] Item 10: The radioisotope recovery system according to any of the preceding Items, wherein its configuration allows implementing several radioisotope recovery systems in one nuclear fusion tokamak with beam-driven plasma that can be operated simultaneously, independently and with individual operation parameters such as flow velocity or irradiation period.

[0138] Item 11 : A remotely operated system to deploy and recover different materials into and from the reactor of a fusion power plant or demonstration fusion power plant, herein called FPP radioisotope recovery system, for the purpose of exposing these materials to neutrons, which will cause the generation of radioactive isotopes (also called radioisotopes), comprising:

[0139] - A loop made of pipes with constant inner diameter in the range between 5 mm and 60 mm. - Spherical metal capsules, e.g. made of steel, with an outside diameter slightly smaller than the inside diameter of the pipe inside the pipes of the loop containing the precursor material, support structure, and possibly neutron moderators.

[0140] - A remotely operated pump.

[0141] - A remotely operated system to fill spherical capsules into the pipe.

[0142] - A remotely operated system to recover the spherical capsules from the pipe. wherein

[0143] - All components operating the loop i.e., pump, capsule recovery and refill systems, valves, are located outside the bioshield, and therefore are located in areas (i) accessible by remote controlled tools or personnel, (ii) protected from excessive neutron and gamma radiation.

[0144] - The continuous operation of the loop i.e. circulation of the spherical capsules means each capsule passes multiple times through the internal part of the loop inside the reactor ensuring a homogeneous exposure to neutrons amongst all capsules.

[0145] - The system operation mode i.e., flow velocity and time to recover spherical capsules, can be customized to the production of radioisotopes from different precursor materials.

[0146] Item 12: The FPP radioisotope recovery system according to any of the preceding Items, wherein part of the loop's pipes are integrated into the reactor of the fusion power plant.

[0147] Item 13: The FPP radioisotope recovery system according to any of the preceding Items, wherein the circulation of the spherical capsules ensures the transport of the capsules from the reactor outside the bioshield allowing for a recovery of the spherical capsules without major intervention and possibly not requiring the plasma to be shutdown.

[0148] Item 14: The FPP radioisotope recovery system according to any of the preceding Items, wherein the auxiliary components of the loop requiring in-service maintenance and inspection are located outside the bioshield of the fusion power plant in areas protected from excessive neutron and gamma radiation and accessible by remote controlled tools or personnel.

[0149] Item 15: The FPP radioisotope recovery system according to any of the preceding Items, wherein the loop transports the spherical capsules reliably by avoiding blockage due to congestion through the following features: (i) the capsules are made of robust metal, e.g. steel, (ii) the external shape of spherical capsules and the internal shape of pipes are without major irregular geometries, (iii) conventional technologies are used for components operating the loop e.g., pump, valves, etc.

[0150] Item 16: The FPP radioisotope recovery system according to any of the preceding Items, wherein the continuous circulation of the spherical capsules ensures a uniform exposure to neutron flux amongst the different capsules.

[0151] Item 17: The FPP radioisotope recovery system according to any of the preceding Items, wherein its configuration allows implementing several radioisotope recovery systems in one fusion power plant that can be operated simultaneously, independently and with individual operation parameters such as flow velocity or irradiation period.

[0152] Item 18: The FPP radioisotope recovery system according to any of the preceding Items, wherein the available options for the integration in the reactor allow utilizing the different neutron spectra and neutron flux intensities in different zones of the reactor for the tailored production of different species of radioisotopes.

[0153] Item 19: A nuclear fusion tokamak with beam-driven plasma that is used as a neutron source for the purpose of producing radioactive isotopes (also called radioisotopes), comprising:

[0154] - A nuclear fusion tokamak with beam-driven plasma whose basic technical concept is outlined in

[0001] , wherein - numerous pieces of precursor materials contained in metallic capsules are incorporated into some of the blankets for the purpose of exposing them during plasma operation to a neutron flux, which will cause the production of radioactive isotopes other than tritium.

[0155] Item 20: A nuclear fusion tokamak with beam-driven plasma according to Item 19, wherein various different precursor materials can be incorporated into the blankets enabling the production of a wide range of radioisotopes other than tritium.

[0156] Item 21 : A nuclear fusion tokamak with beam-driven plasma according to Item 19 or Item 20, wherein the high energy of the neutrons (14 MeV) generated by the D-T fusion reaction of 14 MeV allows the production also of such radioisotopes that are difficult to produce in fission reactors which generate neutrons with a much lower energy, in average about 2 MeV.

[0157] Item 22: A nuclear fusion tokamak with beam-driven plasma according to any of Items 9 to 21 , wherein the precursor materials incorporated into the blankets can contain actinoids for the purpose of causing their transmutation by neutron irradiation.

Claims

Claims1 . Remotely operated system (200) to deploy and recover materials (25) into and from a nuclear fusion plant (100), for the purpose of exposing said materials (25) to neutron radiation, which will cause the generation of radioactive isotopes, comprising:- at least one loop made of pipes (14) with constant inner diameter;- a plurality of capsules (23) with an outer diameter slightly smaller than the inner diameter of the at least one loop (14); wherein the capsules (23) are adapted to contain the material (25) to be irradiated by the neutron radiation;- a remotely operated propulsion system (20) for circulating the capsules (23) through the at least one loop (14),- a remotely operated capsule filling system (18) for filling said capsules (23) into the at least one loop (14); and- a remotely operated capsule recovery system (19) for recovering said capsules (23) from the at least one loop(14).

2. System (200) according to claim 1 , wherein the remotely operated propulsion system (20) is implemented by a remotely operated pump for providing pressurized liquid or gas to the at least one loop (14) or by a device causing direct mechanical movement of the capsules.

3. System (200) according to claim 1 or 2, wherein the capsules (23) are made of a metallic material, in particular stainless steel.

4. System (200) according to any of the preceding claims, wherein capsules (23) are of spherical shape or of cylindrical shape, in particular with hemi-spherical end regions.

5. System (200) according to any of the preceding claims, wherein the flow velocity of the liquid (24) and / or an exposure time of the capsules (23) is adjustable in such a manner as to control the irradiation of the material (24).

6. System (200) according to any of the preceding claims, wherein the system (200) is adapted for continuous circulation of the capsules (23) within the at least one loop (14).

7. Nuclear fusion plant (100), in particular tokamak with beam-driven plasma, comprising a reactor and at least one system (200) according to any of the preceding claims.

8. Nuclear fusion plant (100) according to the preceding claim, further comprising a bioshield (4), wherein the pump (20), the capsule filling system (18) and / or the capsule recovery system (19) are positioned outside the bioshield (4).

9. Nuclear fusion plant (100) according to any of claims 7 and 8, wherein the at least one loop is at least partially integrated into the reactor, in particular into a neutron shielding blanket on an inboard (9) and / or an outboard side (8) of the reactor.

10. Nuclear fusion plant (100) according to any of claims 7 to 9, comprising a plurality of systems (200) according to any of claims 1 to 6, wherein the respective loops of said systems (200) are arranged such that the energy spectra and / or flux intensities of the incident neutron radiation differs between the systems (200).11 . Nuclear tokamak with beam-driven plasma (300), comprising a plurality of blankets (2) around its reactor core, wherein in at least some of the blankets (2), capsules containing material to be exposed to neutron radiationare incorporated in order to produce radioactive isotopes other than tritium.

12. Method for producing radioisotopes using a system (200) according to any of claims 1 to 6 in a nuclear fusion plant according to any of claims 7 to 10, comprising:- operating the nuclear fusion plant (100) in order to produce neutron radiation;- operating the capsule filling system (18) for filling capsules (23) into the at least one loop (14);- operating the propulsion system (20) to circulate the capsules (23) within the at least one loop (14); and- recovering the capsules (23) after a given irradiation time from the at least one loop (14) by means of the capsule recovery system (19).

13. Method according to the preceding claim, wherein the propulsion system (20) of the system (200) is operated in a continuous manner during operation of the nuclear fusion plant (100) and / or is adjustable with respect to its flow rate.

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