HCPB (Helium Cooled Pebbles Bed) Test Blanket Model (TBM) is based on solid breeder. Tritium has to be extracted using Helium purge gas flowing through breeder pebbles bed. He-stream must be cooled down and processed and all these steps are carried out in TES (Tritium Extraction System). A modeling work has been performed to study the behavior of the TES of the HCPB TBM and for Molecular Sieve 5A as adsorbent material. The result is the capability to model the extraction process of gaseous tritium compounds and to estimate the breakthrough curves of two main tritium gaseous species (H2 and HT).