The CAPER facility operated at the Tritium Laboratory Karlsruhe for the demonstration of the tokamak exhaust processing system comprises a PERMCAT reactor as final clean-up stage. CAPER has been upgraded to enable the production of highly tritiated water (HTW) to be detritiated with PERMCAT. A staged approach for HTW production in CAPER is ongoing, using currently a metal oxide reactor, and later a micro-channel catalytic reactor. The whole experimental plan using the current single-tube PERMCAT reactor shall cover the HTW processing at flow rates up to 10 mL/min, with HTW up to 1.4 MCi/kg (i.e. stoichiometric DTO). The staged approach and corresponding CAPER modifications are described. The first experimental results obtained using metal oxide reactor are reported and discussed.