Advanced Traveling-wave reactors offer a path to zero-emissions, proliferation-resistant energy that would reduce nuclear waste volumes. Exploiting new physics that has only recently been fully explored with 21st-century computational tools, traveling-wave reactors run on depleted uranium, a waste byproduct of the enrichment process. Huge amounts of depleted uranium already exist in stockpiles around the world, with more being made each year as the fleet of conventional reactors is refueled. Burned in traveling-wave reactors, this inexpensive but energy-rich fuel source could provide a global electricity supply that is, for all practical purposes, inexhaustible.
A traveling-wave reactor can sustain fission in a nonfissile fuel such as depleted uranium because it sets up a slow-moving wave in which neutrons produced by fission reactions in one small part of the core convert adjacent fuel pellets from fertile isotopes (such as U238) into fissile isotopes (such as Pu239).
The traveling-wave reactor creates the simplest nuclear energy fuel cycle. A TWR breeds its own nuclear fuel, where it needs it, when it needs it. Exhausted fuel can be left in the core. So unlike conventional nuclear plants that take in new fuel and expel high-level waste every 18 months or so, a TWR can in principle be fueled once, sealed up, and run without refueling for 60 years or more.