Government-funded scientists have proposed placing huge "uranium farms" on the seabed, consisting of anchored sponges which soak up the element.
Dr Masao Tanada, of the Japan Atomic Energy Agency, has developed a fabric made primarily of irradiated polyethylene that is able to soak up the minute amounts of uranium – around 3.3 parts per billion – in the seawater.
The world's oceans contain an estimated 4.5 billion tons of uranium, around 1,000 times the amount that is known to exist in uranium mines.
Dr Tanada claims Japan's nuclear power industry could harvest the 8,000 tons it needs each year a year from the Kuroshio Current that flows along Japan's eastern seaboard.
"At the moment, Japan has to rely on imports of uranium from Canada and Australia, but this technology could be commercially deployed in as little as five years," he said.