Abstract: Provided is an industrially feasible method for separating tritiated water from contaminated water. The method for separating tritiated water from light water contaminated by the tritiated water, includes the steps of; adding heavy water to the contaminated water; converting the liquid mixture of the contaminated water and the heavy water into a mixture of the light water and a gas hydrate consisting essentially of the tritiated water and the heavy water as the crystal structure under a condition of converting into the gas hydrate of at least one of the heavy water and the tritiated water, and yet keeping most of the light water in liquid state; and separating the gas hydrate from the light water.

Abstract: Provided is an industrially feasible method for separating tritiated water from light water.