Since various gases such as carbon monoxide (CO) are generated by MCCI (Molten Core Concrete Interaction), this is suppressed by injecting water into the lower part of the containment vessel. In order to install silver zeolite in the containment vessel and confirm whether it can play an auxiliary role in the hydrogen recombiner, we conducted joint research with PSI on the effects of CO and other substances on hydrogen reactivity. AgX exhibits a remarkable hydrogen-catalyzed reaction as before in a water vapor-free environment. Furthermore, it was confirmed that the concentration of CO₂ in the out gas increased in the presence of CO, indicating that it also has a catalytic effect on CO. The amount of hydrogen treated was calculated from the results of the AgX hydrogen reaction test. Under the conditions of sample temperature 170°C, residence time 0.092 seconds, air 45%, hydrogen 5%, water vapor 9%, and atmospheric pressure, it was found that the hydrogen processing capacity per AgX unit weight was 0.207 kmol / kg or more of hydrogen.