Patent Number: 053393406
Section: claims

1. A baffle in combination with a containment vessel disposed inside a silo and wherein: said baffle comprises a perforate inner wall installed between said containment vessel and said silo, and an imperforate outer wall installed between said inner wall and said silo;  said containment vessel contains a reactor vessel having a reactor core submerged in a liquid metal;  said inner wall is spaced radially outwardly from said containment vessel to define an inner riser therebetween for channeling cooling air upwardly therein;  said outer wall is spaced radially outwardly from said inner wall to define an outer riser therebetween for channeling cooling air upwardly therein;  said outer wall is spaced radially inwardly from said silo to define a radially outer flow downcomer therebetween for channeling cooling air downwardly therein; and  said downcomer is disposed in flow communication with both said inner and outer risers at bottom ends thereof for channeling downwardly flowing cooling air upwardly into both said inner and outer risers for cooling said containment vessel, said inner wall comprising a plurality of apertures spaced vertically and horizontally and sized for allowing a portion of thermal radiation from said containment vessel to pass laterally through said inner wall to said outer wall.  said inner riser has an inner width laterally between said containment vessel and said inner wall;  said outer riser has an outer width laterally between said inner wall and said outer wall; and  said outer width is less than said inner width.  said inner riser has an inlet at a bottom thereof, and an outlet at a top thereof;  said outer riser has an inlet at a bottom thereof, and an outlet at a top thereof;  said downcomer has an inlet at a top thereof, and an outlet at a bottom thereof disposed in flow communication with both said inlets of said inner and outer risers for channeling said cooling air thereto; and  said inner and outer riser outlets discharge air heated therein vertically upwardly.  a cylindrical inner wall arranged inside said annular volume and concentric with said containment vessel to form an inner riser therebetween for channeling cooling air upward; and  a cylindrical outer wall arranged inside said annular volume and concentric with said containment vessel, said outer wall being arranged between said inner wall and said silo to form an outer riser between said inner wall and said outer wall for channeling cooling air upward, and to form a downcomer between said outer wall and said silo for channeling cooling air downward,  wherein said inner wall comprises a plurality of apertures for allowing the passage of thermal radiation from said containment vessel to said outer wall.  a cylindrical inner wall is arranged between and concentric with said containment vessel and said outer wall for dividing said riser into inner and outer risers, said inner wall comprising a plurality of apertures for allowing the passage of thermal radiation from said containment vessel to said outer wall. 2. A baffle combination according to claim 1 wherein: 3. A baffle combination according to claim 1 wherein said containment vessel, said inner wall, said outer wall, and said silo are annular and concentric. 4. A baffle combination according to claim 1 wherein said inner wall is joined to said outer wall by a plurality of spaced stud bolts. 5. A baffle combination according to claim 1 further comprising a plurality of vertically spaced horizontal boundary layer trips disposed on at least one of an outer surface of said containment vessel or an inner surface of said outer wall for increasing heat transfer to said cooling air flowing upwardly in said inner and outer risers, respectively. 6. A baffle combination according to claim 1 wherein said outer wall has an outer surface facing said silo characterized by the absence of thermal insulation thereon. 7. A baffle combination according to claim 1 wherein: 8. A baffle for enhancing air cooling of a containment vessel concentrically arranged inside a silo of a nuclear reactor with an annular volume therebetween, said containment vessel encircling a reactor vessel having a nuclear fuel core submerged in liquid coolant, comprising: 9. The baffle as defined in claim 8, wherein said downcomer is disposed in flow communication with both said inner and outer risers at bottom ends thereof for channeling downwardly flowing cooling air upwardly into both said inner and outer risers for cooling said containment vessel. 10. The baffle as defined in claim 8, wherein said inner wall is supported by said outer wall. 11. The baffle as defined in claim 8, wherein said outer wall has a radially outer circumferential surface facing said silo with no thermal insulation thereon. 12. The baffle as defined in claim 8, wherein said outer wall has a radially inner circumferential surface facing said inner wall with means for generating turbulence formed thereon. 13. The baffle as defined in claim 8, wherein said containment vessel has a radially outer circumferential surface facing said inner wall with means for generating turbulence formed thereon. 14. The baffle as defined in claim 8, wherein said apertures are circular. 15. In a nuclear reactor comprising a reactor vessel having a nuclear fuel core submerged in liquid coolant, a containment vessel encircling said reactor vessel, a baffle encircling said containment vessel for enhancing air cooling thereof, and a silo encircling said baffle, said baffle comprising a cylindrical outer wall arranged between and concentric with said containment vessel and said silo, said outer wall and said silo forming a downcomer therebetween for channeling cooling air downward, and said containment vessel and said outer wall forming a riser therebetween for channeling cooling air from said downcomer upward, the improvement wherein: 16. The baffle as defined in claim 15, wherein said inner wall is supported by said outer wall. 17. The baffle as defined in claim 15, wherein said outer wall has a radially outer circumferential surface facing said silo with no thermal insulation thereon. 18. The baffle as defined in claim 15, wherein said outer wall has a radially inner circumferential surface facing said inner wall with means for generating turbulence formed thereon. 19. The baffle as defined in claim 15, wherein said containment vessel has a radially outer circumferential surface facing said inner wall with means for generating turbulence formed thereon. 20. The baffle as defined in claim 15, wherein said apertures are circular.