Patent Number: 
Section: claims

1. A nuclear reactor module, comprising:a reactor vessel;a pressurizer located at an upper portion of the reactor vessel;a reactor core located at a lower portion of the reactor vessel;a baffle assembly located between the reactor core and the pressurizer; anda reactor housing having an inward-facing portion and a flow path through the reactor housing that fluidly couples the reactor core to a lower portion of the baffle assembly, the inward-facing portion comprising a curvature for reducing turning loss of a coolant flowing past the inward-facing portion, the inward-facing portion of the reactor housing comprising multiple wing-shaped extensions located about a perimeter of an upper portion of the reactor housing. 2. The nuclear reactor module of claim 1, wherein a cross section of the inward-facing portion comprises an airfoil. 3. The nuclear reactor module of claim 2, wherein the inward-facing portion of the reactor housing is disposed about a perimeter of an upper portion of the reactor housing. 4. The nuclear reactor module of claim 1, wherein the baffle assembly comprises a lower baffle plate including an ellipsoidal surface having a perimeter that is larger than the inward-facing portion of the reactor housing. 5. The nuclear reactor module according to claim 4, wherein the ellipsoidal surface of the lower baffle plate directs the coolant towards the lower portion of the reactor vessel. 6. The nuclear reactor module according to claim 1, wherein the inward-facing portion of the reactor housing includes a cross section that approximates an inverted teardrop. 7. The nuclear reactor module according to claim 1, wherein the inward-facing portion of the reactor housing includes a cross section that increases in thickness towards an upper portion of the reactor housing. 8. The nuclear reactor module according to claim 7, wherein the upper end of the reactor housing comprises a perimeter that includes a rounded rim. 9. A baffle assembly for use in a nuclear reactor module, comprising:an upper baffle plate exposed to a pressurized volume of saturated coolant; anda lower baffle plate exposed to subcooled coolant, the subcooled coolant in fluid communication between a location proximate to a portion of the lower baffle plate and a location proximate with the upper baffle plate, wherein one or more of the upper baffle plate and the lower baffle plate are heated by the saturated coolant. 10. The baffle assembly of claim 9, wherein a flow path created by a separation of the upper baffle plate and the lower baffle plate is of sufficient length to prevent an insurge of coolant from a volume proximate with the lower baffle plate. 11. The baffle assembly of claim 9, wherein the upper baffle plate is heated by the pressurized volume of saturated coolant. 12. The baffle assembly of claim 9, wherein the peripheral portion of the lower baffle plate curves in a direction towards a lower portion of the nuclear reactor module. 13. The baffle assembly of claim 9, wherein the lower baffle plate comprises a bullet-shaped tip at a central portion. 14. The baffle assembly of claim 13, wherein the lower baffle plate curves downward at a peripheral portion. 15. An upper portion of a nuclear reactor module, comprising:a pressurizer region; anda baffle assembly below the pressurizer region, the baffle assembly comprising:an upper baffle plate proximate with the lower portion of the pressurizer region; anda lower baffle plate below the upper baffle plate, wherein the lower baffle plate comprises a surface that curves downward toward a peripheral region of the lower baffle plate. 16. The upper portion of the nuclear reactor module of claim 15, further comprising an upper portion of a riser having a curved inward-facing portion for reducing turning loss of coolant circulating from a lower portion of the nuclear reactor module. 17. The upper portion of the nuclear reactor module of claim 16, wherein the curved inward-facing portion of the riser extends continuously about a perimeter of the upper portion of the riser. 18. The upper portion of the nuclear reactor module of claim 15, further comprising a divider for directing coolant in an outward direction from a center of the lower baffle plate. 19. The upper portion of the nuclear reactor module of claim 15, wherein the lower baffle plate is defined by a shape selected from the group consisting of an ellipsoid, a dome, a hemisphere, and a concave surface.