Patent Number: 
Section: claims

1. A method comprising:circulating a primary coolant into a reactor housing;partitioning the primary coolant into a first portion and a second portion, wherein the first portion passes entirely through a reactor core located in the reactor housing, and wherein the second portion passes partially through the reactor core before entering an inlet of a neutron reflector, wherein the inlet is located in a side wall of the neutron reflector, and wherein the side wall faces the reactor core; anddirecting the second portion of the primary coolant through the neutron reflector. 2. The method according to claim 1, further comprising:recombining the second portion of the primary coolant that exits the neutron reflector with the first portion of the primary coolant that passes through the reactor core. 3. The method according to claim 2, wherein the second portion of the primary coolant is recombined with the first portion within the reactor housing. 4. The method according to claim 2, wherein the second portion of the primary coolant enters the neutron reflector primarily as single-phase liquid, and wherein the second portion of the primary coolant exits the neutron reflector as two-phase steam and liquid. 5. The method according to claim 1, further comprising circulating the second portion from the inlet to an outlet located in an axial wall of the neutron reflector. 6. The method according to claim 5, further comprising adjusting a flow direction of the second portion of the primary coolant from the inlet to the outlet. 7. The method according to claim 6, wherein the flow direction is adjusted about 90 degrees. 8. The method according to claim 2, further comprising increasing, by recombining the second portion of the primary coolant with the first portion, a flow rate of the primary coolant through a riser conduit. 9. The method according to claim 8, further comprising circulating the recombined first and second portions of the primary coolant from the riser conduit, through an annulus between the riser conduit and the reactor housing, and towards the reactor core. 10. A method for operating a nuclear reactor, comprising:communicating a primary coolant through a reactor housing that encloses a reactor core having axial and radial surfaces;communicating the primary coolant in an annulus between a reflector and the reactor housing, the reflector at least partitioning partially surrounding the radial surfaces of the reactor core;communicating the primary coolant from the annulus to an inlet of the reactor core;communicating a first portion of the primary coolant from the inlet of the reactor core through the reactor core and to an outlet of the reactor core;communicating a second portion of the primary coolant from the inlet of the reactor core, through a portion of the reactor core, and through one or more openings in the radial surfaces of the reactor core;communicating the second portion of the primary coolant from the one or more openings to inlets of fluid pathways in the reflector, through the fluid pathways, and to outlets of the fluid pathways; andcommunicating the first portion from the outlet of the reactor core and the second portion from the outlets of the fluid pathways together through a riser conduit enclosed in the reactor housing. 11. The method of claim 10, wherein the inlets of the fluid pathways are arranged on a radial surface of the reflector that faces at least one of the radial surfaces of the reactor core. 12. The method of claim 10, wherein the outlets of the fluid pathways are arranged on an axial surface of the reflector that is parallel with at least one of the axial surfaces of the reactor core. 13. The method of claim 10, wherein at least a portion of each of the fluid pathways is substantially parallel with portions of adjacent ones of the fluid pathways. 14. The method of claim 10, further comprising communicating the primary coolant from the annulus to a lower end of the reactor housing and from the lower end of the reactor housing to the inlet of the reactor core. 15. The method of claim 10, wherein communicating the second portion of the primary coolant from the one or more openings to inlets of fluid pathways in the reflector, through the fluid pathways, and to outlets of the fluid pathways comprises:communicating the second portion of the primary coolant from the inlets of the fluid pathways through first segments of the fluid pathways, the first segments of the fluid pathways angularly arranged relative to the radial surfaces of the reactor core;communicating the second portion of the primary coolant from the first segments of the fluid pathways through second segments of the fluid pathways, the second segments of the fluid pathways angularly arranged relative to the first segments of the fluid pathways; andcommunicating the second portion of the primary coolant from the second segments of the fluid pathways to the outlets of the fluid pathways. 16. The method of claim 15, wherein the first segments are orthogonal to the radial surfaces of the reactor core, and the second segments are orthogonal to the first segments. 17. The method of claim 16, wherein the reflector comprises a plurality of sections, and the first segments of the fluid pathways are arranged between adjacent ones of the sections, and at least one of the second segments extends through the adjacent sections. 18. The method of claim 17, wherein at least two of the plurality of sections are of different thickness. 19. The method of claim 10, wherein the second portion of the primary coolant comprises a single-phase liquid at the inlets of the fluid pathways, and the second portion of the primary coolant comprises a two-phase fluid at the outlets of the fluid pathways.