Evaluation of experiments in the AVR with the DALTON–THERMIX coupled code system

The DALTON–THERMIX coupled code system for pebble-bed high temperature reactors was further validated by simulation of two dynamic experiments in the AVR. The validation included a rapid mass flow reduction experiment and a depressurized loss of forced cooling (DLOFC) experiment. For the mass flow reduction experiment, the rotational speed of the blowers dropped rapidly from 100% to 50% in 62 s. In the DLOFC experiment, the long term behavior (100 h) of the reactor was calculated and compared with experiments. Besides the transient calculation, each experiment included a coupled steady state calculation to determine the initial condition for the transient. The calculated results of the new code system agree very well with the experimental ones, from which it is concluded that the code system is very well suited for the design and optimization of future (V)HTR cores.