Determination of SONGS 2 RCS flow rate with VIPRE

The reactor coolant system (RCS) flow rate is one of the key parameters used in both the core protection calculators and the core operating limit supervisory system for Combustion Engineering-designed reactors. Thus, the flow rate directly affects the plant's operating margin and must be accurately determined. The objective of the paper is to present a new method using the VIPRE computer program to calculate the RCS mass flow rate. The vendor estimate of the SONGS 2RCS flow rate uses a hot leg stratification factor that is developed based on a scaled reactor flow model and an assumed cosine temperature distribution in the hot leg. Using this correction factor, the vendor estimated the RCS flow rate for SONGS 2 at full power is 107% of design flow. In this study, a SONGS 2 quarter-core VIPRE model is used and a best-estimate RCS flow rate is calculated using the methodology described. Based on this evaluation, the calculation SONGS 2 RCS flow rate at full power is 106.6% of design