Abstract: Gases and entrained particulate matter are automatically vented from a nuclear containment as pressure approaches a set point of the containment design during a postulated accident scenario. A porous bed filter is submerged in a tank of water, affording a first stage of filtration of the vented gases and entrained particulate matter passing in an upward flow from the bottom of the tank through the porous filter bed and a second, pool scrubbing stage as the flow proceeds upwardly through a central region of the water above the filter with accompanying decay heat removal prior to release of the gases from the water surface and discharge to atmosphere. The water returns through a down-flow path defined by an annular boundary region surrounding the central region of the water volume, in a pumping function for repeating the mixing and two-stage flow, and purges the porous filter bed.

Abstract: Components and systems which impact technical specifications (tech specs) in a nuclear power plant are modeled in a set of cascading operability trees which represent the various combinations of component, system and parameter statuses which can result in non-compliance with the tech specs. Cutsets for the operability trees are entered into a cutset table in the data base of a digital computer which tracks the effect of a selected event up through the trees by repetitively searching the cutset table using the top event activated by the selected event as the selected event for the next search, until an activated top event is reached which is not entered in the cutset table as an event. A separate cutset evaluation table is used to assure that all the members of a multiple event cutset have been activated before the associated top event is activated.