High Quality Content by WIKIPEDIA articles! A traveling-wave reactor, or TWR, is a type of conceptual nuclear reactor that theorists speculate can convert fertile material into fissile fuel as it runs using the process of nuclear transmutation. TWRs differ from other kinds of fast-neutron and breeder reactors in their ability to, once started, reach a state whereafter they can achieve very high fuel utilization while using no enriched uranium and no reprocessing, instead burning fuel made from depleted uranium, natural uranium, thorium, spent fuel removed from light water reactors, or some combination of these materials. The name refers to the design characteristic that fission does not happen in the entire TWR core, but takes place in a fairly localized zone that advances through the core over time. TWRs could theoretically run, self-sustained, for decades without refueling or removing any used fuel from the reactor.