Validation exercise for the MAAP4 containment model

The Modular Accident Analysis Program version 4 (MAAP4) is an integrated severe accident analysis code which integrates a large number of phenomena and models into a single plant simulation. MAAP4 was used to predict the containment response to a simulated large LOCA and hydrogen distribution (Test T31.5) in the decommissioned German Heiss Dampf Reactor (HDR) facility as a validation/benchmark exercise. In MAAP4, 22 nodes and 66 flow paths were used to model the highly compartmentalized containment. The MAAP4 predictions of the containment pressure and gas temperature over the duration of the transient and the transient distribution of hydrogen/helium concentration in containment compartments are compared here with experimental results. The nature of how the validation exercise is integrated with the MAAP4 code for continual dynamic benchmarking is also discussed. (author)