GB2601332A

GB2601332A - A method and passageway for a superconducting cable

Info

Publication number: GB2601332A
Application number: GB2018609.4A
Authority: GB
Inventors: Sharratt Rob
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 2020-11-26
Filing date: 2020-11-26
Publication date: 2022-06-01
Also published as: WO2022112740A1; GB202018609D0

Abstract

A predefined pathway 10, method or flexible superconducting cable 20 for installing or removing a flexible superconducting cable 20 into or out from a desired position, where at least a portion of the cable 20 is moved through a predefined pathway 10 and into or out from the desired predefined position. An anisotropic flexible superconducting cable 20, which easily bends in a first direction perpendicular to the cable whilst is less bendy in a second direction perpendicular to the first direction and to that of the cable 20, may include a plurality of individual sub-cables which may be pushed and/or pulled through a pathway 10, possibly involving a cable reel 40. The pathway 10 may be a channel passageway that guides a cable 20 into a desired predefined position. The predefined pathway 10 may form toroidal or poloidal field coils for a tokamak nuclear fusion reactor. The cable 20 may be secured into position and joints may be formed during the coil formation process. The pathway 10 may include removable cable guide means members. The method allows for the easy installation and/or replacement of superconducting cable arrangements within magnetic field coil and other formations.

Description

A METHOD AND PASSAGEWAY FOR A SUPERCONDUCTING CABLE

FIELD OF THE INVENTION

The present disclosure relates to a method and passageway for a superconducting cable and the superconducting cable. in particular, although not exclusively, the present disclosure relates to the application of the method, passageway and superconducting cable to a nuclear fusion reactor.

BACKGROUND OF THE INVENTION

A tokamak is a nuclear fusion reactor that confines a mix of deuterium and tritium in plasma fonn by a magnetic field with a toroidal geometry. A spherical tokamak is a compact version, in which the radius at the centre of the toroid is minimised. Such a compact arrangement is still topologically a toroid, but it is referred to as a spherical tokamak due to its spherical appearance.

Figure 1 shows a cutaway view of a previously-proposed tokamak arrangement.

Superconducting magnet assemblies I, 2, 3 are disposed around a toroidal vessel 4. Superconducting magnet assembly I comprises toroidal field coils which extend around a section of the vessel 4. A plurality of such toroidal field coils may be provided and may be distributed about a circumference of the vessel 4. The toroidal field coils provide a magnetic field with field lines circulating around the centre of the vessel 4 and help to contain the plasma.

Superconducting magnet assembly 2 comprises poloidal field coils which extend about the circumference of the vessel 4. A plurality of such poloidal field coils may be provided and they may be distributed along a central axis of the vessel 4. The poloidal field coils help to shape and stabilise the 25 plasma.

Superconducting magnet assembly 3 comprises a central solenoid that extends through the centre of the toroidal vessel 4. The central solenoid may induce a current in the plasma so as to heat the plasma.

A benefit of the spherical tokamak is its compact nature, which is expected to reduce the capital cost. Other benefits include attractive plasma physics features. A key efficiency parameter, called beta, is the ratio of the thermal energy density stored in the plasma to that stored in the confining magnetic field. A spherical tokamak can accommodate much higher values of beta than a conventional tokamak because of the high ratio of plasma current to magnetic field it can contain.

However, the more compact arrangement of the spherical tokamak presents challenges. For example, there may not be sufficient space for shielding to allow the magnet assemblies I, 2, 3 to survive the full life of the reactor. The magnetic assemblies may therefore require replacement during the life of the reactor. Replacing the magnetic assemblies will be difficult, time-consuming and costly. Degradation of the magnetic assemblies may otherwise limit the lifespan of the reactor.

Likewise, in other applications, it may be desirable to readily install or replace superconducting cables or magnets

SUMMARY OF THE INVENTION

According to a first specific aspect, there is provided a method of installing or removing a superconducting cable into or from an installed operative position, wherein the superconducting cable is flexible and the method comprises: moving at least a portion of the superconducting cable through a predefined pathway into or from the installed operative position.

The method may further comprise pushing or pulling the superconducting cable through the predefined pathway into or from the installed operative position.

The method may further comprise rotating a reel onto which the superconducting cable is wound around; and feeding the superconducting cable onto or from the rotating reel.

The method may further comprise guiding the superconducting cable through the predefined pathway, e.g. with a guide, such as a track, rail or other such guide. The guide may comprise at least one bearing, such as a plain bearing, ball bearing, roller bearing or any other type of bearing. The method may further comprise removing the guide from the predefined pathway after the superconducting cable has been instilled into the installed operative position. Alternatively, the guide may remain in the pathway.

The superconducting cable may be anisotropic such that the superconducting cable is more flexible in a first direction than a second direction. The first and second directions may be orthogonal to one another and a longitudinal direction of the superconducting cable.

The superconducting cable may be made up of a plurality of sub-cables. The plurality of sub-cables may be pre-assembled to form the superconducting cable. The method may further comprise moving the pre-assembled superconducting cable through the predefined pathway into or from the installed operative position. Alternatively, the method may comprise moving the sub-cables individually through the predefined pathway into or from the installed operative position.

The method may further comprise securing the superconducting cable in place after the superconducting cable has been installed into the installed operative position.

The method may further comprise installing or removing the superconducting cable into or from a nuclear reactor, such as a nuclear fusion reactor. The predefined pathway may be provided in the nuclear reactor. In the installed operative position, the superconducting cable may contribute to a toroidal or poloidal magnetic field of a tokamak nuclear fusion reactor.

The method may thither comprise joining a first portion of the superconducting cable extending from a first end of the predefined pathway to a second portion of the superconducting cable extending from a second end of die predefined pathway. The first and second portions may be joined at a location spaced apart from the nuclear reactor, e.g. using mechanical means, welding, brazing or any other joining method.

The method may thither comprise feeding or extracting the superconducting cable into or from the nuclear reactor at a bottom or a top of the nuclear reactor.

The nuclear reactor may comprise a toroidal vessel. The predefined pathway may pass through a central region of the toroidal vessel. The method may further comprise moving the superconducting cable through the central region of the toroidal vessel.

The nuclear reactor may comprise at least one partition layer. The partition layer may provide radiation and/or thermal shielding. The partition layer may additionally provide a wall at least partially defining the predefined pathway. The method may thither comprise moving the superconducting cable along the partition layer.

According to a second specific aspect, there is provided a predefined pathway configured to receive a flexible superconducting cable in an installed operative position, the predefined pathway being configured such that at least a portion of the superconducting cable can be moved into or from the installed operative position.

The predefined pathway may further comprise a guide, such as a track, rail or other such guide, to guide the superconducting cable through the predefined pathway. The guide may comprise at least one bearing, such as a plain bearing, ball bearing, roller bearing or any other type of bearing. The guide may (or may not) be removable from the predefined pathway. The guide may be removable after the superconducting cable has been installed into the installed operative position.

An assembly may comprise the above-mentioned predefined pathway and the flexible superconducting cable The assembly may further comprise a rotatable reel or drum onto which the superconducting cable is wound around. The reel may be configured such that the superconducting cable is fed onto or from the reel.

The superconducting cable may be an isotropic. The superconducting cable may be more flexible in a first direction than a second direction. The first and second directions may be orthogonal to one another and a longitudinal direction of the superconducting cable.

The superconducting cable may be made up of a plurality of sub-cables. The plurality of sub-cables may be pre-assembled to form the superconducting cable prior to installation into the predefined pathway. Alternatively, the sub-cables may be individually movable through the predefined pathway into or from the installed operative position The assembly may fiirther comprise securing means configured to secure the superconducting cable in place after the superconducting cable has been installed into the installed operative position.

A nuclear reactor, such as a fusion reactor, may comprise the above-mentioned assembly or the above-mentioned predefined pathway.

In the installed operative position, the superconducting cable may contribute to a toroidal or poloidal magnetic field of a tokamak nuclear fusion reactor.

A first portion of the superconducting cable may extend from a first end of the predefined pathway and a second portion of the superconducting cable extends from a second end of the predefined pathway. The first and second portions of the superconducting cable may be joined at a location spaced apart from the nuclear reactor, e.g. using mechanical means, welding, brazing or any other joining means.

The nuclear reactor may comprise an inlet to the predefined pathway. The inlet may be provided at a bottom or a top of the nuclear reactor. The superconducting cable may be fed into or extracted from the inlet.

The nuclear reactor may comprise a toroidal vessel. The predefined pathway may pass through a central region of the toroidal vessel.

The nuclear reactor may comprise at least one partition layer. The partition layer may provide radiation and/or thermal shielding. The partition layer may additionally provide a wall at least partially defining the predefined pathway.

According to a third specific aspect, there is provided a flexible superconducting cable configured with a flexibility that allows the superconducting cable to be installed into or removed from an installed operative position by moving at least a portion of the superconducting cable through a predefined pathway.

The superconducting cable may be an isotropic such that the superconducting cable may be more flexible in a first direction than a second direction. The first and second directions may be orthogonal to one another and a longitudinal direction of the superconducting cable.

These and other aspects will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will now be described, by way of example only, with reference to the following drawings, in which: Figure 1 is cutaway schematic view of a previously-proposed tokamak nuclear fusion reactor; Figures 2a and 2b (collectively Figure 2) are partial and vertical sectional views of a predefined pathway and nuclear fusion reactor comprising the predefined pathway according to embodiments of the present invention: Figure 3 is a vertical sectional view of a nuclear fusion reactor according to an embodiment of the present invention (the solenoid has been omitted); Figure 4 is a vertical sectional view of a nuclear filsion reactor according to an embodiment of the present invention (the solenoid has been omitted); Figure 5 is a partial and vertical sectional view of a nuclear fusion reactor according to an embodiment of the present invention; Figure 6 is a horizontal sectional view of a nuclear fusion reactor according to an embodiment of the present invention; Figure 7 is a schemat c sect onal view of a superconducting cable according to an embodiment of the present invention; Figure 8 is a flowchart of a method according to an embodiment of the present invention; and Figure 9 is a vertical sectional view of a nuclear fusion reactor according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to Figure 2, the present invention relates to a predefined pathway 10 configured to receive a flexible superconducting cable 20. The pathway 10 receives the superconducting cable 20 in an installed operative position, which is depicted in Figure 2. The predefined pathway10 is configured such that at least a portion of the superconducting cable 20 can be moved along the pathway 10 and into or from the installed operative position. Accordingly, the pathway 10 defines both a channel in which the superconducting cable 20 resides during use of the superconducting cable and a passageway that guides movement of the superconducting cable 20. The pathway 10 may be elongate and extend longitudinally.

The superconducting cable 20 may be correspondingly elongate and move along the longitudinal direction of the pathway 10 and cable 20. The superconducting cable 20 may be moved, e.g. by pushing and/or pulling, when installing or removing the superconducting cable.

In the particular example shown, the predefined pathway 10 is provided in a nuclear reactor, such as a nuclear fusion reactor 30. However, it is also envisaged that the predefined pathway 10 may be provided in other applications, such as electrical transmission, superconducting magnet applications or any other application with superconducting cables.

The arrangement of the nuclear fusion reactor 30 may correspond to that shown in Figure 1. As such, the nuclear fusion reactor 30 comprises a toroidal vessel 31 that is configured to contain a plasma 39. Within the vessel 31 there may be provided a first wall or blanket 32 and a divcrtor 33. (Note that Figure 2 only shows one side of the toroidal vessel 31.) The toroidal vessel 31 comprises a central region 34 about which the toroidal vessel 31 extends and through which a solenoid 35 may be provided. The predefined pathway 10 may pass through the central region 34 and extend around the toroidal vessel 32, e.g. in a vertical plane. The pathway 10 may extend in a poloidal direction, i.e. around the smaller circumference of the toroidal vessel 31.

The vessel 31 may comprise a lid 36. The lid 36 may enable access to the vessel 31. The passageway 10 may extend through the lid 36, e.g. at the top of the vessel 31. An inlet 37a and outlet 37b may be provided, e.g. on the lid 36. The inlet and outlet 37a, 37b may permit passage of Helium or another gas into and around the vessel 31.

A plurality of such pathways 10 may be provided at positions around the larger circumference of the toroidal vessel 31, e.g. at other vertical cross-sections. When a current passes through the superconducting cables 20 within these pathways 10, a toroidal magnetic field may be generated within the vessel 31. As such, the superconducting cable 20 may contribute to and may thus be referred to as a toroidal magnet.

Additionally or alternatively, at least one predefined pathway may be provided in a horizontal plane, e.g. extending in a toroidal direction around the larger circumference of the toroidal vessel 31. When a current passes through superconducting cables 21 (shown in Figures 3 and 4) within these pathways, a poloidal magnetic field may be generated within the vessel 31. As such, the superconducting cables 21 may contribute to and may thus be referred to as the poloidal magnets.

Again, additionally or alternatively, at least one predefined pathway may extend in both poloidal and toroidal directions, e.g. in a helical direction around the toroidal vessel. Superconducting cables may be provided in such pathways and the superconducting cable may contribute to both the poloidal and

toroidal magnetic fields.

Once installed, a first end 20a of the superconducting cable 20 may be at a first end 10a of the predefined pathway 10 and a second end 20b of the superconducting cable may be at a second end 10b of the predefined pathway 10. As shown in Figure 2, the first and second ends 20a, 20b of the superconducting cable 20 may be electrically coupled together so as to create the continuous loop required for the current path of the field coil. In particular, as depicted in Figure 2a, the first and second ends 20a, 20b may be joined together with a join 29 in the region of the nuclear fusion reactor 30, for example at or within the vessel lid 36. The first and second ends 20a, 20b may be directly joined together or via an intermediate piece. However, in an alternative arrangement depicted in Figure 2b, first and second portions of the superconducting cable 20, which extend from respective first and second ends 10a, 10b of the pathway 10, may be joined at a location spaced apart from the nuclear reactor 30. This may be beneficial as the join can be further away from and better shielded from the nuclear reactor. In either case, the superconducting cable 20 may be joined e.g. using mechanical means, welding, brazing or any other joining means.

Referring now to Figure 3, the superconducting cable 20 may be wound around a rotatable spool, drum or reel 40. The reel 40 may feed out the superconducting cable 20 as it moves through the pathway 10. Rotation of the reel 40 may provide at least a portion of the force required to move the cable 20 into and through the pathway 10. As such, the reel 40 may push the cable through the pathway 10. It is also envisaged that additional or alternative means may be provided for pushing the cable 20 through the pathway 10.

The superconducting cable 20 may additionally or alternatively be pulled through the pathway 10. For example, a further cable (not shown), such as a structural or load carrying cable, may be connected to an end of the superconducting cable 20 and this further cable may be pulled, e.g. by virtue of a further reel, so as to pull the superconducting cable 20 through the pathway 10.

In a similar manner, the reel 40 may be used for extracting the superconducting cable 20 from the pathway 10. In this case, the reel 40 may provide the force required to move the cable 20 out of the pathway 10.

It will be appreciated that a corresponding reel arrangement (not shown) may be provided for the superconducting cables 21 extending in the toroidal direction, e.g. with a reel having a vertical axis of rotation.

The nuclear reactor 30 may comprise an inlet 11 to the predefmed pathway 10 into which the superconducting cable 20 is fed or extracted from. The inlet 11 may be provided at the first end 10a of the pathway. As shown in Figure 3, the inlet 11 may be provided at a bottom of the nuclear reactor 30. However, as shown in Figures 2 and 4, the inlet may be provided at the top of the nuclear reactor. Furthermore, as depicted in Figures 3 and 4, the inlet 11 may be orientated so that the cable 20 is substantially horizontal at the inlet, or as shown in Figure 2, the inlet 11 may be orientated so that the cable 20 is substantially vertical at the inlet. It will be appreciated that other intermediate orientations of the inlet 11 and thus cable 20 are contemplated.

With reference to Figure 5, the predefined pathway 10 may further comprise a guide 12, such as a track, rail or other such guide, to guide the superconducting cable 20 through the predefined pathway. For example, the guide 12 may be formed by side walls defining the pathway 10. The guide 12 may also comprise at least one bearing 13, such as a plain bearing, ball bearing, roller bearing or any other type of bearing. The bearings 13 may, in particular, be provided at bends in the pathway 10.

The guide 12, or at least parts of the guide, may be removable from the predefined pathway 10. For example, the guide may comprise a track, which may also move within the pathway 10. The guide 12 (or parts thereof) may be removable after the superconducting cable 20 has been installed, in a similar manner, the bearings 13 may be accessible so that they can be removed once the cable 20 is in place.

Securing means (not shown) may be provided to secure the superconducting cable 20 in place after it has been installed into the installed operative position. The securing means may comprise mechanical fasteners, such as clamps, wedges or any other type of securing device.

With reference to Figure 6, the nuclear reactor 30 may comprise at least one partition wall or layer 38. The partition layer 38 may provide radiation, thermal shielding, electrical insulation and/or structural support. The partition layer 38 may additionally provide a surface at least partially defining the predefined pathway 10. The partition layer 38 may thus help guide the superconducting cable 20 as it moves through the pathway 10. As depicted in Figure 6, the partition layer 38 may be provided between neighbouring pathways 10. However, it is also envisaged that the partition layer 38 may be provided between the pathway 10 and the vessel 31 or solenoid 35.

With reference to Figure 7, the present invention also relates to the flexible superconducting cable 20, 21 that is configured with a flexibility that allows the superconducting cable 20, 21 to follow the curvature of the predefined pathway 10 and thus be installed into or removed from the predefined pathway 10.

By way of example, the superconducting cable 20, 21 may be made up of a plurality of sub-cables 22 that are assembled together. The plurality of sub-cables 22 may be pre-assembled to form the superconducting cable 20, 21 prior to insertion into the predefined pathway 10. The assembled sub-cables 22 may then be moved together through the pathway 10. Alternatively, the sub-cables 22 may be individually movable through the predefined pathway 10 such that the superconducting cable 20, 21 can effectively be assembled in-situ.

As depicted in Figure 7, each sub-cable 22 may be made of a plurality of strands 23 around a core 24. These strands 23 may be arranged in a helical fashion. A protective sheath 25 may be provided around each sub-cable 22. An outer protective sheath 26 may be provided around the collection of sub-cables 22.

The superconducting cable 20, 21 (e.g. sub-cables 22 or strands 23) may be made from a superconducting material, such as Niobium-titanium, Yttrium barium copper oxide (YBCO), Bismuth strontium calcium copper oxide (BSCCO) or any other superconducting material. In particular, the superconducting cable 20, 21 may be a high temperature superconductor.

The superconducting cable 20, 21 may have a thickness (in a first direction 27) that is smaller than its width (in a second direction 28). In particular, the cable 20,21 may be rectangular. This cross-sectional shape may be achieved by having more sub-cables 22 in the second direction 28 than in the first direction 27 and/or by haying sub-cables 22 with a thickness smaller than their width. Other shapes are also contemplated, for example the cable 20, 21 may have a D shaped or wedged shaped cross-section. Such shapes may be achieved by varying the number of sub-cables 22 across the thickness or width of the cable 20, 21.

The superconducting cable 20,21 may be anisotropic. As such, the superconducting cable 20, 21 may be more flexible in the first direction 27 than the second direction 28. The first and second directions 27, 28 may be orthogonal to one another and a longitudinal direction of the superconducting cable 20, 21. The anisotropic property of the cable 20, 21 may be achieved by the difference between the thickness and the width of the cable or sub-cables and/or by the variation in the number of sub-cables.

The anisotropic superconducting cable 20, 21 may thus behave like a chain that is constrained in one of its non-longitudinal directions (such as a roller chain) and such behaviour may facilitate movement of the cable through the pathway 10. In particular, the superconducting chain 20,21 may be orientated so that its dimension with increased flexibility aligns with any changes of direction in the pathway 10. For example, the increased flexibility of the superconducting cable 20 in the first direction 27 of the cable may facilitate bending around the bends in the pathway 10. Conversely, the reduced flexibility in the second direction 2/1 of the cable may help constrain movement of the cable and keep it travelling in the right direction. Furthermore, the flexibility of the cable 20, 21 fin either direction) may be configured to best match the radii of curvature of the bends encountered in the pathway 10.

With reference to Figure 8, the present invention relates to a method 100 of installing or removing the flexible superconducting cable 20 into or from the installed operative position. The operative position may be in the nuclear fusion reactor 30 mentioned above and the superconducting cable may contribute to a magnetic field, e.g. for containing or controlling the plasma in the toroidal vessel 3 I. In a first optional step 110, the method 100 may comprises rotating the reel 40 onto which the superconducting cable 20 is wound, and feeding the superconducting cable 20 onto or from the rotating reel 40.

In a second step 120, the method 100 comprises moving at least a portion of the superconducting cable 20 through the predefined pathway 10 into or from the installed operative position. As mentioned above, the superconducting cable 20 may be moved by pushing or pulling the cable through the predefined pathway 10 into or from the installed operative position, e.g. by virtue of the rotating reel 40.

The method 100 may comprise moving the pre-assembled superconducting cable 20 as a single piece through the predefined pathway 10. Alternatively, the method may comprise moving one or more individual sub-cables 22 through the predefined pathway ID. The superconducting cable 20 can thus be built up as part of the process of installing it into the pathway 10.

In a third optional step 130, when installing the superconducting cable 20, the method 100 may comprise removing the guide 12 (or components thereof) from the predefined pathway 10 after the superconducting cable 20 has been installed into the installed operative position In a fourth optional step 140, when installing the superconducting cable 20, the method 100 may comprise joining the first end or portion 20a of the superconducting cable 20 to the second end or portion 20b of the superconducting cable 20. The first and second ends or portions 20a, 20b may be joined at the nuclear reactor or at a location spaced apart from the nuclear reactor.

With reference to Figure 9, when removing the superconducting cables 20, the method 100 may further comprise removing the vessel lid 36 to access inside the vessel 31. The present invention advantageously permits easier removal of the superconducting cables, which can then allow access to the vessel 31 or replacement of the superconducting cables if for example they have degraded within the lifespan of the remainder of the nuclear fitsion reactor. As a result, maintenance of the nuclear fusion reactor is facilitated and the lifespan of the reactor is improved.

Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the principles and techniques described herein, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMSA method of installing or removing a superconducting cable into or from an installed operative position, wherein the superconducting cable is flexible and the method comprises: moving at least a portion of the superconducting cable through a predefined pathway into or from the installed operative position.
The method of claim 1, wherein the method further comprises: pushing or pulling the superconducting cable through the predefined pathway into or from the installed operative position.
The method of claim I or 2, wherein the method further comprises: rotating a reel onto which the superconducting cable is wound around; and feeding the superconducting cable onto or from the rotating reel.
The method of any of the preceding claims, wherein the method further comprises: guiding the superconducting cable through the predefined pathway with a guide.
The method of claim 4, wherein the method further comprises: removing the guide from the predefined pathway after the superconducting cable has been installed into the installed operative position.
6. The method of any of the preceding claims, wherein the superconducting cable is made up of a plurality of sub-cables, the plurality of sub-cables being pre-assembled to form the superconducting cable, and wherein the method further comprises moving the pre-assembled superconducting cable through the predefined pathway into or from the installed operative position.
7. The method of any of claims I to 5, wherein the superconducting cable is made up of a plurality of sub-cables, and wherein the method further comprises moving the sub-cables individually through the predefined pathway into or from the installed operative position.
The method of any of the preceding claims, wherein the method further comprises: securing the superconducting cable in place after the superconducting cable has been installed into the installed operative position.
The method of any of the preceding claims wherein the method further comprises: installing or removing the superconducting cable into or from a nuclear fusion reactor, the predefined pathway being provided in the nuclear fusion reactor.
10, The method of claim 9, wherein the method further comprises: joining a first portion of the superconducting cable extending from a first end of the predefined pathway to a second portion of the superconducting cable extending from a second end of the predefined pathway, the first and second portions being joined at a location spaced apart from the nuclear fusion reactor.
11. The method of claim 9 or 10, wherein the method further comprises: feeding or extracting the superconducting cable into or from the nuclear fusion reactor at a bottom or atop of the nuclear fusion reactor.
12. The method of any of claims 9 to 11, wherein the nuclear fusion reactor comprises a toroidal vessel and the predefined pathway passes through a central region of the toroidal vessel, the method further comprising: moving the superconducting cable through the central region of the toroidal vessel.
13. The method of any of claims 9 to 12, wherein the nuclear fusion reactor comprises at least one partition layer, the partition layer providing radiation and/or thermal shielding, wherein the partition layer additionally provides a wall at least partially defining the predefined pathway, the method further comprising: moving the superconducting cable along the partition layer.
14. A predefined pathway configured to receive a flexible superconducting cable in an installed operative position, the predefined pathway being configured such that at least a portion of the superconducting cable can be moved into or from the installed operative position.
15. The predefined pathway of claim 14 further comprising a guide to guide the superconducting cable through the predefined pathway.
16. The predefined pathway of claim 15, wherein the guide comprises at least one bearing.
17. The predefined pathway of claim 15 or 16, wherein the guide is removable from the predefined pathway such that the guide is removable after the superconducting cable has been installed into the installed operative position.
18. An assembly comprising the predefined pathway of any of claims 14 to 17 and the flexible superconducting cable.
19. The assembly of claim 18 further comprising a rotatable reel onto which the superconducting cable is wound around, the reel being configured such that the superconducting cable is fed onto or from the reel.
20. The assembly of claim 18 or 19, wherein the superconducting cable is anisotropic such that the superconducting cable is more flexible in a first direction than a second direction, the first and second directions being orthogonal to one another and a longitudinal direction of the superconducting cable.
21. The assembly of any of claims 18 to 20, wherein the superconducting cable is made up of a plurality of sub-cables, the plurality of sub-cables being pre-assembled to form the superconducting cable prior to installation into the predefined pathway.
22. The assembly of any of claims 18 to 20, wherein the superconducting cable is made up of a plurality of sub-cables, the sub-cables being individually movable through the predefined pathway into or from the installed operative position.
23. The assembly of any of claims 18 to 22 further comprising securing means configured to secure the superconducting cable in place after the superconducting cable has been installed into the installed operative position
24. A nuclear fusion reactor comprising the assembly of any of claims 18 to 23.
25. The nuclear fusion reactor of claim 24, wherein in the installed operative position the superconducting cable contributes to a toroidal or poloidal magnetic field of a tokamak nuclear fusion reactor.
26. The nuclear fusion reactor of claim 24 or 25, wherein a first portion of the superconducting cable extends from a first end of the predefined pathway and a second portion of the superconducting cable extends from a second end of the predefined pathway, wherein the first and second portions of the superconducting cable are joined at a location spaced apart from the nuclear fusion reactor.
27. The nuclear fusion reactor of any of claims 24 to 26, wherein the nuclear fusion reactor comprises an inlet to the predefined pathway, the inlet being provided at a bottom or a top of the nuclear fusion reactor, the superconducting cable being fed into or extracted from the inlet.
28. The nuclear fusion reactor of any of claims 24 to 27, wherein the nuclear fusion reactor comprises a toroidal vessel and the predefined pathway passes through a central region of the toroidal vessel.
29. The nuclear fusion reactor of any of claims 24 to 28, wherein the nuclear fusion reactor comprises at least one partition layer, the partition layer providing radiation and/or thermal shielding, wherein the partition layer additionally provides a wall at least partially defining the predefined pathway.
30. A flexible superconducting cable configured with a flexibility that allows the superconducting cable to be installed into or removed from an installed operative position by moving at least a portion of the superconducting cable through a predefined pathway.
31. The flexible superconducting cable of claim 30, wherein the superconducting cable is anisotropic such that the superconducting cable is more flexible in a first direction than a second direction, the first and second directions being orthogonal to one another and a longitudinal direction of the superconducting cable.