Will Fusion be Most Useful for Burning Waste from Fission?
Using Sandia National Laboratories data, Helion calculates 50 fusion engines could incinerate the entire U.S. stockpile of nuclear waste in 20 years._PM
Many billions of dollars have been spent on large scale fusion efforts such as the National Ignition Facility in Livermore or ITER in France. But if the best use of fusion in the intermediate term is to burn up non-recyclable nuclear waste from fission reactors, perhaps the smaller-scale, cheaper approaches might be better? Small efforts such as Bussard IEC fusion, Focus Fusion, General Fusion, Tri Alpha etc. are the sentimental favourites, because they are the work of relatively small groups with low budgets. Their reactors would be small enough to mass produce in factories. And maybe they could even provide the heart of a deep space fusion rocket propulsion system one day.
Regardless, the teams of scientists and engineers are out there giving it their best. Here is a quick look at Helion Energy's fusion project, based in Redmond, Washington:
Helion is among a handful of fusion startups, such as Tri Alpha Energy in Foothill Ranch, Calif., and General Fusion in Vancouver, British Columbia, all striving for the same grand goal as their outsize government counterparts: remaking the global energy landscape by proving that fusion power is feasible. A few forward-looking venture-capital firms have provided funding to get them off the ground; Tri Alpha, for instance, has attracted more than $50 million from a variety of prominent firms, including Goldman Sachs and Vulcan Capital.
Helion's technology was developed for about $5 million by MSNW, a company owned by University of Washington research associate professor John Slough. To see a full-scale component of the reactor, which Slough calls a fusion engine, I meet him at an industrial building a few minutes' drive from Helion's headquarters and walk past a conference table to a room filled with giant metal parts.
Inside the 26-foot-long prototype, two plasmas—clouds of hot ionized gas containing hydrogen isotopes—hurtle toward each other. The clouds collide inside a burn chamber, merging into a single entity. An electromagnet surrounding the chamber squeezes the plasma tighter and tighter, creating the high temperature and pressure conditions needed for fusion—a milestone MSNW first passed in 2008. "The idea," says Slough, who has the white hair and slightly disheveled appearance of a modern-day Einstein, "is to have the energy that comes out of the plasma exceed the energy that goes into it for a brief period of time."
...With its pulsed magnetic field design, the Helion team claims it has found the elusive sweet spot in the fusion landscape: a reliable, cheap reactor that doesn't require fine-tuned optics or complicated plasma confinement. In Helion's reactor, electric currents flowing inside the plasma reverse the direction of a magnetic field that's applied from the outside; the new, closed field that results effectively confines the plasma. "Compared to the tokamak and NIF, Helion's reactor is relatively compact and low-cost," says Richard Milroy, a physicist at the University of Washington who isn't affiliated with Helion. "Utilities don't need to invest billions for the first test reactor to see if things will work out." Plus, he says, the plasma-formation area is separate from the burn chamber in Helion's reactor, so its expensive components may last longer.
...While Helion's reactor is much simpler than those of ITER or NIF, it's also not yet powerful enough to be useful to a utility. Slough says his team will need to increase the size of the reactor's magnetic confinement field and boost the acceleration rate so that the plasmas will be traveling about twice as fast by the time they crash into each other. Those refinements will require at least $15 million to $20 million in development costs, money Helion does not currently have. Even if the funds materialize, there's no guarantee the reactor will work as projected when scaled up, or function consistently over long periods of time.
...fusion might be most useful—at least in the near term—as a means of destroying waste from nuclear fission. University of Texas physicist Swadesh Mahajan and his colleagues are developing a hybrid fusion–fission reactor that shunts neutrons produced during fusion to a fission blanket that burns nuclear waste as fuel. "Producing energy by fusion is at best a very long-term project," Mahajan says, "but through this intermediary, we can become useful to the energy sector."
NIF's projected LIFE power plant will be designed to burn waste, too, and Helion is considering adapting its reactor to do the same in order to provide revenue from utilities sooner. It's easier from a technical standpoint than using fusion to produce energy, because achieving break-even is not necessary—and it could potentially help solve a long-standing problem. Using Sandia National Laboratories data, Helion calculates 50 fusion engines could incinerate the entire U.S. stockpile of nuclear waste in 20 years. _PM
The R&D work and expense would be worth it, just to be able to safely dispose of non-recyclable nuclear waste (and any other toxic waste). But if any of the small-scale fusion projects actually succeeds in producing large scale electric power safely and sustainably from fusion, the world will have changed overnight.