An integrated fusion fuel loop was constructed. A palladium diffuser first treated a simulated plasma exhaust gas, that is a mixture of hydrogen isotopes and impurities such as helium and methane. A pure hydrogen isotopes stream was sent to a cascade of cryogenic distillation columns. The impurities were processed with a unit of an electrolytic reactor and a palladium diffuser. The integrated fusion fuel loop was thus demonstrated. A major result was that the electrolytic reactor processed methane successfully in a gas phase without using the catalysts. A laser Raman analysis system installed into the cryogenic distillation columns gave a set of analysis results with no time delay and no sampling gas exhaust. It was demonstrated that the laser Raman was a promising analysis system for the control of the fusion fuel loop.