Patent ID: 7558360

Claim:
An assembly comprising: a containment vessel comprising a suppression pool, a drywell and a floor, said drywell comprising a sidewall extending upward from said floor, said sidewall separating said suppression pool from said drywell, said suppression pool, said drywell, and said drywell sidewall located inside said containment vessel; a reactor pressure vessel installed inside said containment vessel; a base grid disposed underneath said pressure vessel and spaced vertically above said floor of said containment vessel to define a sump therebetween, said drywell sidewall bounding said sump, wherein a vertical axis of said reactor pressure vessel intersects said base grid, said base grid comprising a top plate; a layer of refractory material disposed on top of said top plate; an annular base grid shield wall extending vertically upward from said base grid, said base grid shield wall having a configuration comprising at least one of: (a) said base grid shield wall spaced inwardly from said drywell sidewall to define an annular channel therebetween; and (b) said base grid shield wall positioned adjacent said drywell sidewall; at least one flow baffle in said sump, said at least one flow baffle comprising a base end and a tip end, said base end having a larger cross-sectional area than said tip end, said base end positioned proximate said drywell side wall; an inlet flow channel extending through at least one of said annular channel providing flow communication between said drywell and said sump, and an inlet flow passage through said drywell sidewall providing flow communication between said sump and said suppression pool; and an outlet flow channel extending through at least one of said annular channel providing flow communication between said sump and said drywell, and an outlet flow passage through said drywell sidewall providing flow communication between said sump and said suppression pool.