To obtain performance data of atmosphere detritiation system at the off normal events such as fire for the safety of ITER, the detritiation experiment was planned and performed at Tritium Process Laboratory (TPL) in Japan Atomic Energy Research Institute (JAERI) using a new scaled detritiation system for the oxidation performance test which can process gas flow rate of ~2.64 m3/hr in circulation through 2m3 tank. The detritiation system consists of two oxidation catalyst beds (473K and 773K) for converting hydrogen isotopes and tritiated methane in compounds to water vapor and a molecular sieve drying absorber for removing water vapor as the usual detritiation system. In this time, the performance of oxidation catalyst bed of the detritiation system for hydrogen and methane under existence of carbon monoxide or carbon dioxide which are produced in the fire was investigated.

Basic performance of the detritiation system for hydrogen (1.9%) and methane (1.3%) in air was evaluated under maximum ventilation flow rate (2.64m3/h). Obtained oxidation efficiency was more than 99.99% for hydrogen in the catalyst bed at 473K and more than 99.9% for methane in the 773K one, respectively. It was confirmed that these performances were maintained even under carbon dioxide of up to 20% , carbon monoxide of up to 10% if sufficient oxygen remained in the process gas, and that the existence of carbon monoxide and carbon dioxide at the fire would not influence the performance of the oxidation catalyst bed in the detritiation system.