Method for treating tritium-water-containing raw water

The present invention is a method for treating tritium-water-containing raw water, the method comprising supplying, to a circulation tank, some of the tritium-water-containing raw water stored in a storage tank, mixing the raw water with alkaline water in the circulation tank to obtain an electrolytic solution regulated so as to have a desired alkali concentration, and continuously electrolyzing the electrolytic solution while circulating the electrolytic solution, thereby subjecting the raw water stored in the storage tank to alkaline-water electrolysis and thus gasifying the raw water. According to the invention, by gasifying tritium-water-containing raw water by alkaline-water electrolysis, the tritium concentration in a tritium-containing hydrogen gas is lowered to 1/1,244 and the tritium-water-containing raw water can be reduced in volume.