Analysis of a hypothetical boron dilution event by means of the neutron kinetic core model DYN3D using different cross section libraries

Stationary and transient core calculations for a hypothetical boron dilution event have been carried out by the nodal code DYN3D. Two different two-group diffusion-parameter libraries, generated by the cell codes HELIOS and CASMO, have been used, in order to assess the influence of these data. Realistic core inlet boundary conditions have been applied using a validated semi-analytical coolant mixing model. The initial deborated-coolant-slug volumes, necessary for reaching recriticality in stationary calculations with both data libraries, differ by some 20 %. Differences are also observed in the height and time point of the power peak in transient calculations. The deviations between the applied data libraries are mainly due to different SCRAM reactivities and Doppler coefficients. Even when assuming a 36 m3 deborated slug, the core is brought back to subcriticality in all calculations.