Analysis of the Main Steam Line Break Benchmark (Phase II) Using ANCK/MIDAC Code

The three-dimensional (3D) neutronics and thermal-and-hydraulics (T/H) coupling code ANCK/MIDAC has been developed. ANCK/MIDAC consists of the 3D nodal kinetic code ANCK and the 3D drift flux T/H code MIDAC. In order to verify the adequacy of ANCK/MIDAC, the Phase II problem in the "OECD main steam line break benchmark (MSLB benchmark)" was analyzed. This MSLB benchmark has been defined in order to simulate the core response and the reactor coolant system response to a relatively severe steam line break accident condition. The Phase II problem has a conservative condition that the control rod with the maximum worth is stuck in a fully withdrawn position throughout the transient. The simulation was performed using the core inlet temperatures and flow rates for 18 different regions, which were provided by the PSU best-estimate TRAC-PF1/NEM calculations. The comparison of the ANCK/MIDAC results with other participants' results shows the excellent agreement on main core parameters. ANCK/MIDAC has good capability and reliability for the best-estimation code and a reasonable calculation time.