Patent Number: 
Section: claims

1. A steam generator comprising:a vessel having an inlet and an outlet, wherein in use, a primary fluid flow enters the vessel through the inlet and exits the vessel through the outlet; anda plurality of modules connected in series and at least partially housed within the vessel, wherein each module comprises:a plurality of tubes, anda flange plate positioned at an axial end of the plurality of tubes,wherein the modules are arranged such that each of the plurality of tubes of one module is coaxial with one of the plurality of tubes of an adjacent module so as to form a conduit bundle comprising a plurality of conduits through which a secondary fluid can flow from one module to an adjacent module, and wherein adjacent modules of the plurality of modules are connected together via the flange plates of the adjacent modules, andwherein an intermediate plate is positioned between adjacent flange plates of the adjacent modules, the intermediate plate comprising a plurality of holes, each hole receiving one of the plurality of tubes of each of the adjacent modules, and the axial end of the plurality of tubes of the one module and the axial end of the plurality of tubes of the adjacent module are both located within the intermediate plate. 2. The steam generator according to claim 1, wherein each flange plate comprises a plurality of holes, each hole receiving one of the plurality of tubes. 3. The steam generator according to claim 1, wherein the intermediate plate and two flange plates are bolted together. 4. The steam generator according to claim 1, wherein the intermediate plate and the flange plates are welded together. 5. The steam generator according to claim 1, further comprising a seal between adjacent flange plates and the intermediate plate. 6. The steam generator according to claim 1, wherein the flange plates are formed as a separate component to the tubes. 7. The steam generator according to claim 6, wherein one or more of the plurality of flange plates are integrally formed with the vessel. 8. The steam generator according to claim 1, wherein the conduit is U-shaped. 9. The steam generator according to claim 1, wherein the conduit is helical. 10. The steam generator according to claim 9, wherein one tube defines one turn of the helical conduit and an adjacent tube defines an adjacent turn of the helical conduit. 11. A steam generator system comprising the steam generator according to claim 1; a primary fluid flow channel connecting to the inlet of the vessel and for connection to a heat source; and a secondary fluid flow channel connecting to the outlet of the vessel and for connection to a turbine. 12. A steam generator comprising one or more tube bundles, the steam generator being configured to receive a secondary flow through the tube bundles and a primary flow outside the tube bundles;wherein each tube bundle comprises a first sub-bundle connected in series to a second sub-bundle,wherein each of the first and second sub-bundles comprise a plate including a plurality of holes, each hole receiving one of a plurality of tubes of the respective first or second sub-bundle, andwherein the plate of the first sub-bundle connects to the plate of the second sub-bundle with an intermediate plate positioned between the plates of the first and second sub-bundles, the intermediate plate comprising a plurality of holes, each hole receiving one of the tubes of each of the first and the second sub-bundles, an axial end of the plurality of tubes of the first sub-bundle and an axial end of the plurality of tubes of the second sub-bundle are both located within the intermediate plate, and the first and second sub-bundles and the intermediate plate are arranged such that the tubes of the first sub-bundle are substantially coaxial to the tubes of the second sub-bundle, such that in use, fluid flows from the first sub-bundle to the second sub-bundle. 13. The steam generator according to claim 1, wherein each of the plurality of holes of the intermediate plate include a chamfered axial end. 14. The steam generator according to claim 1, wherein the vessel is configured to receive the primary fluid as a pressurized liquid. 15. The steam generator system according to claim 11, wherein the heat source is a nuclear reactor. 16. A nuclear power plant steam generator comprising:a vessel having an inlet and an outlet, wherein in use, a primary fluid flow from a nuclear reactor of the nuclear power plant enters the vessel through the inlet and exits the vessel through the outlet; anda plurality of modules connected in series and at least partially housed within the vessel, wherein each module comprises:a plurality of tubes, anda flange plate positioned at an axial end of the plurality of tubes,wherein the modules are arranged such that each of the plurality of tubes of one module is coaxial with one of the plurality of tubes of an adjacent module so as to form a conduit bundle comprising a plurality of conduits through which a secondary fluid can flow from one module to an adjacent module, and wherein adjacent modules of the plurality of modules are connected together via the flange plates of the adjacent modules, andwherein an intermediate plate is positioned between adjacent flange plates of the adjacent modules, the intermediate plate comprising a plurality of holes, each hole of the plurality of holes of the intermediate plate receiving one of the plurality of tubes of each of the adjacent modules, and the axial end of the plurality of tubes of the one module and the axial end of the plurality of tubes of the adjacent module are both located within the intermediate plate.