Hybrid nuclear energy gains traction

Russian engineers are embarking on a quest already under way at U.S. labs: The creation of a “hybrid” nuclear reactor combining fusion and fission to deliver cleaner, safer nuclear energy.

Today’s nuclear reactors deliver energy through fission, the shattering of atoms, which creates radioactive waste. In fusion, atoms don’t fly apart but fuse together, releasing non-radioactive neutrons. But today’s fusion reactions don’t release enough energy to be practically useful.

In a hybrid reactor, atoms would fuse in a core chamber, spewing neutrons into surrounding fissionable material, such as uranium. The neutrons would collide with atoms and ignite energy-releasing fission reactions to power turbines.

The concept is enticing. Conventional nuclear reactors burn only a fraction of their fuel, leaving most as radioactive waste. A hybrid reactor could steadily deliver enough neutrons to burn much more of the fuel — including uranium discarded by today’s reactors — so far less toxic waste would remain.

A hybrid design also would be safer. Fissionable material by itself can lurch into a runaway chain reaction and “melt down,” as happened at Fukushima. In a hybrid reactor, fission could be snuffed in seconds by turning off the fusion reaction and ending the flow of neutrons.

The engineering challenges are daunting. Building a commercial fusion reactor has never been done; building one inside a nuclear-fission reactor multiplies the complexity. But Russia declares that hybrid reactors are a near-term goal, not a distant dream, and has offered China a role in the project.

Moreover, this is just one example to track as alternative energy development emerges as a key 2015 trend line.