Apparatus for draining lower drywell pool water into suppresion pool in boiling water reactor

A system for draining water from the drywell into the suppression pool in a boiling water reactor, comprising a conduit having an inlet in flow communication with the drywell and an outlet in flow communication with the suppression pool, said conduit comprising a downcoming portion in flow communication with said inlet and a generally horizontal portion in flow communication with said downcoming portion and with said outlet, wherein said downcoming portion of said conduit comprises a vertical standpipe located inside the drywell.

A boiling water reactor comprising a containment vessel, a reactor pressure vessel arranged inside said containment vessel so that a lower portion of said reactor pressure vessel is surrounded by a lower drywell pool, a nuclear fuel core arranged inside said reactor pressure vessel, a suppression pool arranged inside said containment vessel and surrounding said reactor pressure vessel with an annular volume of said lower drywell pool therebetween, said suppression pool comprising an inner bounding wall, a vertical downcomer duct formed in said inner bounding wall, and passive means for conveying surface water from said lower drywell pool into the lowermost stratum of water in said suppression pool when the water level in said lower drywell pool is higher than the water level in said suppression pool, said passive means comprising an inlet in flow communication with said lower drywell pool, an outlet in flow communication with said lowermost stratum of water in said suppression pool, and a closed portion connecting said inlet and said outlet and following a path through the vertical downcomer duct.

A boiling water reactor comprising a containment vessel, a reactor pressure vessel arranged inside said containment vessel so that a lower portion of said reactor pressure vessel is surrounded by a lower drywell pool, a nuclear fuel core arranged inside said reactor pressure vessel, a suppression pool arranged inside said containment vessel and surrounding said reactor pressure vessel with an annular volume of said lower drywell pool therebetween, and a conduit for conveying surface water from said lower drywell pool into the lowermost stratum of water in said suppression pool when the water level in said lower drywell pool is higher than the water level in said suppression pool, wherein said conduit comprises a generally vertical standpipe located inside said lower drywell pool and having an inlet in flow communication with the lower drywell pool, and a generally horizontal pipe having an outlet in flow communication with the suppression pool, said generally horizontal pipe being in flow communication with said generally vertical standpipe.

A system for draining water into a suppression pool of a boiling water reactor from an annular space between the suppression pool and a reactor pressure vessel, comprising a conduit having an inlet located in the annular space at an elevation above a water level in the suppression pool and an outlet located in the suppression pool at an elevation below the water level in and near the bottom of the suppression pool, said conduit being closed between said inlet and said outlet.