Benchmark calculations of AMPX-KENO computer code system were performed to validate this code system for the criticality analysis of the new fuel storage rack. The critical experiments to study the effect due to the interpositioning of hydrogeneous materials between assembly (study connected with the problems raised by the accidental springkling of a mist into a fuel storage) were selected as the reference of the benchmark calculations. The comparsion of the results between the experiment and the calculation shows a good agreement. The bias and uncertainties were also obtained from the benchmark calculations. (Author).