2001Hiroshi Sekimoto begins a series of conceptual studies of various kinds of TWRs

The Future of Nuclear Energy Intellectual Ventures™ has launched an effort to design nuclear energy reactors that improve on those in operation today. Known as TerraPower™, the project has produced preliminary designs for a new class of nuclear reactor, called a Traveling-Wave Reactor (TWR). The TWR can run for 50 to 100 years without refueling or removing any used fuel from the reactor. By greatly simplifying the nuclear fuel cycle, TWRs could improve the cost, safety, social acceptability, and long-term sustainability of nuclear energy as a source of emissions-free electricity.

The ScienceNuclear power plants produce electricity from the heat

generated when big and unstable atoms, such as plutonium-239 or uranium-235, split apart into smaller atoms. Each time a big atom splits (or “fissions”), it releases fast-moving neutrons that can cause other fissions which allow for a sustained chain reaction.

A nuclear fission reactor produces and controls the release of energy from splitting atoms of certain heavy elements. The nuclear power plants of today require a full core of fuel made from enriched uranium. The TWR, in contrast, initially contains only a small amount of enriched uranium, which is used to kick off the chain reaction through a core of depleted uranium. The wave of fission would move slowly through this depleted uranium core, splitting many more of the uranium atoms than a conventional reactor would.

Depleted uranium, which is mostly uranium-238, is currently set aside as waste when uranium-235 is taken out of natural uranium at enrichment plants.

The Evolution of the Traveling-Wave Concept

1979Michael J. Driscoll and others at MIT further evaluate breed-burn reactor ideas

1988Lev Feoktistov works on the concept in Russia and publishes an analysis of a concept of a physically safe reactor

2000Hugo van Dam publishes mathematical analyses of waves of fission moving inside nuclear fuels

1996Edward Teller, Lowell Wood (now at Intellectual Ventures), and others at Lawrence Livermore Lab detail ways to make breed-burn waves travel through a stationary fuel supply

1958Saveli M. Feinberg proposes a “breed-burn” reactor in which unenriched fuel is moved around the core to sustain fission

Early 2000s Sergii Fomin and N. Shul’ga study the burning wave in fast reactors in the Ukraine

2006Intellectual Ventures begins detailed physics and engineering studies of the feasibility, cost, and features of various TWR designs

Fissionproducts

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Neutron

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U

Pu

1 An atom of fertile uranium captures a fast-moving neutron, which converts the uranium to a heavier, unstable form.

2 The atom quickly decays into a form of neptunium that is also unstable.

4 The plutonium captures a fast-moving neutron and fissions into smaller atoms, releasing lots of energy and several neutrons, some of which continue the chain reaction.

3 The neptunium eventually decays into an atom of fissile plutonium.

Creating Fissile Fuel Just Where It Is NeededDepleted uranium is converted from its normal fertile form into fissile plutonium in the region just ahead of the burning wave.

Many Shapes and SizesTerraPower’s scientists and engineers are investigating a

wide range of designs for TWRs. A conceptual design effort is currently underway for a small modular unit that generates a few hundred megawatts of electricity which could fit the needs of emerging markets. The conceptual design for a gigawatt-scale reactor, which is big enough to power a city, has already been completed. At Intellectual Ventures, the process of invention continues every day.

A Simpler, Safer Fuel Cycle Unlike light water reactors, the TWR can theoretically run

forever without ever needing any additional enriched uranium after its startup period, provided sufficient depleted uranium is supplied. Given currently known uranium reserves, this fleet could supply the world’s needs for energy for thousands of years without any need for chemical reprocessing of the used fuel. Since enrichment and reprocessing are the two most significant sources of proliferation risk in the nuclear fuel cycle, this ability is a major advance in reducing the inherent risks of weapons material proliferation.

Introducing

Traveling-Wave Reactors

For press inquiries: TerraPowerInfo@intven.com