Northeast Utilities Service Company has performed sensitivity studies useful for modeling a loss of feedwater transient using the RETRAN code. These studies modeled the Connecticut Yankee Nuclear Power Plant, a four-loop Westinghouse pressurized water reactor. One-, two-, and three-volume steam generator secondary models were used in conjunction with a common primary side nodalization in a two-loop model. The importance of flow area of the steam generator secondary side for this transient has been investigated. A comparison of one-and two-loop models was made, along with an assessment of the differences in response between the equilibrium and nonequilibrium pressurizer models.