This is Part B of Thesis. / <p> This report is divided into two parts. The first part contains the results of a simulation performed by the two-phase thermohydraulics code Firebird. </p> <p> The second part of this report deals with the "water packing" problem. Its mathematical and physical interpretations are discussed in detail and a method for identifying a transition node together with an alternate mathematical treatment of the boiling boundary are also included.</p> / Thesis / Master of Engineering (MEngr)