Abstract: A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using a series of radial guide elements and cascading weir boxes to collect and then distribute the cooling water into a series of distribution areas through a plurality of cascading weirs. The cooling water is then uniformly distributed over the curved surface by a plurality of weir notches in the face plate of the weir box.

Abstract: A procedure document is maintained by storing procedure records identifying each procedure in the document, step records describing the steps performed in each procedure and substep records for steps broken into substeps. Internal references in one step to another step are delimited so that when the step sequence of a procedure is changed the internal step references can be automatically modified to correspond to the change which is made. In addition, the steps and substeps may contain references to instrument and equipment and setpoints of, e.g., pressure, which are pertinent to the procedure. The procedure records may contain a number of columns indicator which indicates whether the steps and substeps of that procedure will use one column or two columns. Seperate files are maintained to provide cross-referencing for the instruments and equipment as well as the setpoints. A description of the setpoints is maintained in a separate file containing unique setpoint identifiers.