Based on experimental results of the catalytic decomposition of ammonia and methane into the elements, a three step process is under development for D, T recycling of the effluent gas of the main fusion reactor exhaust gas purification system. The process is designed for operation at comparatively low temperatures in order to minimize tritium permeation losses. A reduction in solid radioactive waste is achieved by the employment of catalytic cracking reactions. The high purity D, T produced may be fed directly into the isotope separation system. By process optimization sufficiently high decontamination factors of the waste gas seem possible.