Toshiba Corp and Microsoft Corp Chairman Bill Gates would team up to develop a next-generation nuclear reactor that can operate for up to 100 years without refueling, the Nikkei business daily said.

Current light-water reactors require refueling once every several years, the paper said.

TerraPower, which is effectively owned by Gates, and Toshiba would focus on the Traveling-Wave Reactor (TWR), which consumes depleted uranium as fuel, Nikkei said.

TWRs will likely come in sizes ranging from 100,000 Kilowatts to 1 million KW, which is comparable to many of today's reactors in terms of power output, the paper said.

The major Japanese nuclear power systems maker has already developed a design for an ultra compact reactor, known as the Super-Safe, Small and Simple (4S), that can operate continuously for 30 years, Nikkei said.

Toshiba expects to get U.S. approval for its ultracompact 4S design, with an output of about 10,000 KW, this fall and start construction of the first such reactor by 2014, the paper said.

Toshiba expects that about 80 percent of the technologies used in the 4S reactor can be applied to the TWR.

But one issue for the TWR is developing materials that can withstand nuclear reactions for such long periods of time, a problem that is expected to take more than 10 years to solve, the business daily said.

Toshiba will likely handle mass production of the reactors if the effort is successful, the daily said.

Gates is expected to use his personal wealth to back the development of TWRs and may invest as much as several hundred billion yen, the paper said.

(Reporting by Supantha Mukherjee in Bangalore; Editing by Gopakumar Warrier)