NON-BOLTED RINGLESS NOZZLE DAM

摘要

A nozzle dam for providing a fluid-tight seal across a primary fluid nozzle in the plenum of a nuclear steam generating vessel includes an elongated shaft coupled at one end thereof to an anchor assembly frictionally engageable with the inner surface of the nozzle to anchor the dam in place and a fluid-impermeable seal apparatus coupled to the shaft and closing the nozzle and frictionally engageable with the inner surface thereof to form a fluid-tight seal. The seal apparatus includes a circular plate disposable in wedging frictional engagement with a frustoconical portion of the nozzle inner surface. The shaft extends through a central aperture in the plate and is threadedly engaged with a nut which holds the plate in place. The anchor assembly includes a foldable tripod arrangement coupled to the shaft in such a way that movement of the shaft toward the seal plate effects an increase in the frictional anchoring force. The seal assembly also includes an inflatable portion. In one embodiment this inflatable portion extends around the perimeter of the seal plate and is readily expandable. In another embodiment the inflatable portion includes inflatable pillows disposed between the seal plate and the anchor assembly and inflatable for completely closing the nozzle. A foldable tripod centering mechanism and a shaft tensioning tool are also disclosed.