The nuclear industry is very young. Nuclear power has only been around for 65-70 years. It's so important to be open to the new potential for this technology because it's so different from what's existed in the past.

Thank you so much. I'm here because I'm designing a type of nuclear reactor that can run entirely on nuclear waste. It's able to consume the waste. So it actually turns it into a clean and carbon-free source of electric power. I became a nuclear engineer, in the first place because I'm an environmentalist. I believe that we need nuclear power, alongside solar and wind if we want to have any hope of getting the world away from fossil fuels and preventing the wide spread environmental devastation that's caused by coal, in particular.

So, to start the nuclear physics part of the journey we're first going to go back in time, to the 1950s. The United States was aglow with the prosperity of its post-war economic expansion. And it had been barely a decade since the end of World War Two. The devastation in Hiroshima and Nagasaki was still very fresh in peoples' minds. Though somehow through a set of coordinated political and scientific and social campaigns, people we able to also see the immense potential benefits of atomic power. And understand that nuclear reactions had as much potential for creation as they did for destruction. All this stopped very abruptly in 1979 when there was a partial meltdown at the Three Mile Island Nuclear Facility. So, this accident coupled with the rising concerns over nuclear waste and what we're going to do with it effectively put the brakes on the nuclear industry. And the industry's recovery since then has been very slow and painstaking to this day.

So, we started developing this design for a nuclear reactor that can consume the existing stockpiles of nuclear waste, of used nuclear fuel. And we started a company to commercialize the design. It's able to reduce the waste's lifetime and break it down and use it to generate enormous amounts of electric power. So, just to put some numbers on it. If you take all 270,000 metric tons of nuclear waste that exists worldwide it's about a football field's worth of nuclear waste that exists worldwide. We can turn it into enough electricity to power the entire world for 72 years. Even taking into account increasing electricity demand. So, it's just a staggering amount of electricity that's left in this waste. And I think that there's a possibility to start thinking of it as a resource to be tapped rather than a liability to be disposed of without any further thought.

The basis of this technology actually comes from 50 years ago from the Oak Ridge National Lab in Tennessee when there was enormous amounts of exciting new work going on in the nuclear field. So, throughout the 50s, 60s and 70s they worked on a type of liquid fuelled nuclear reactor called a Molten Salt Reactor. And they showed that this type of design had some incredible safety benefits. But this design was ultimately abandoned because this one required very highly enriched fresh uranium as fuel. It was also very big and bulky, had a low power density and it was very expensive. And it couldn't be justified on safety grounds at that point because it was in a world that hadn't yet experienced Chernobyl or Three Mile Island or Fukushima. So it was ultimately shelved and research on it slowed down to a crawl in the subsequent decades. 

What my co-founder and I were able to do was find a way to make this design much more compact and cheaper, able to run on the nuclear waste while keeping the same safety benefits as it had before. It works because what we call nuclear waste isn't actually waste at all because there's still a tremendous amount of energy that's left in it. The conventional reactors just aren't very good at using all of the energy that they can conceivably get out of the uranium in their fuel. They're fuelled by pellets of solid uranium oxide that's held in place within a thin metal clotting, called a fuel assembly. The metal in the clotting has to be thin so that it doesn't absorb too many neutrons. But this very thin metal gets damaged quite readily because it's literally within the core of a nuclear reactor and the accumulating damage limits the amount of time that the fuel can spend in a conventional reactor to about three or four years. And this produces a whole lot of electricity, a whole lot of carbon-free electricity. But the three or four years just isn't long enough to use very much of the energy that's in the fuel. So, it only uses about four percent of the energy that it could conceivably get out of the uranium oxide solid fuel. And, to some degree this is why the conventional nuclear waste is so dangerous and so long lived because it has so much energy that's left in it that you can potentially still extract. So, what we're able to do in our reactor is take out the fuel assemblies, strip off the metal clotting and dissolve the uranium oxide pellets into a molten salt, into a similar type of liquid fuel as what they used at the Oak Ridge plant 50 years ago. And because we're using a liquid as a fuel we don't have the clotting. A liquid has no long range structure to be damaged by radiation. We can keep the fuel in the reactor for essentially as long as it takes to extract almost all of its remaining energy. So, instead of just using about four percent, we can extract up to 96 percent of the energy that's left in it. And that's just by simmering it in the reactor for decades. Basically like simmering it in a crockpot. So... and the interesting thing about this also is that as you, as you let it simmer, as you break it down use it to produce more electricity, you're also reducing the radioactive lifetime of the majority of the waste.

So, conventional nuclear waste is radioactive for hundreds of thousands of years. But the majority of this waste, the broken down waste is only radioactive for a few hundred years. And so a hundred-- I always feel weird saying only a few hundred years but a hundred years it makes it a human time-scale. People can build structures and repositories that last for a few hundred years where as hundreds of thousands of years becomes a geological time-scale.

So, here's the simplified schematic of what molten salt reactors in general look like. Up on the left, you have the primary loop that has the liquid fuel salt flowing through it. In the far left, the fuel is in what's called a critical configuration, so you have a large stable number of nuclear fission reactions that are generating a great deal of heat. This heat is carried over across heat exchangers to the power production loop, that's on the right. And in that loop the heat is used to boil water into steam. The steam drives a turbine that powers the generator that produces the electricity. So, then what specifically makes our new design... different from the older Oak Ridge molten salt reactor, the one that was tried and abandoned 50 years ago? So, there are two main materials changes that we make here and the first is to what's called the moderator. The early molten salt reactor used graphite, as a moderator. So, you had this very large bulky core with only a few small channels for the fuel salt to flow through it so you couldn't fit very much uranium in the core. We switch it to using a clad zirconium hydride moderator that lets it be much more compact. You can fit five times as much salt in the core. The second thing that we changed was the salt itself. We switched it to a new type of salt that lets you dissolve 27 times as much uranium in the salt. So, 27 times as much uranium in the salt, five times as much salt in the core. So, together those two facts let us both go to very, very low enriched fuel and at the same time, it gives us a much higher power density so we can increase the power density by a factor of more than 20. So, by doing this, making it much more compact power dense, able to run on the nuclear waste and in turn, making it much cheaper we solve all of the original problems that prevented the earlier design from gaining traction 50 years ago.

So, where are we at right now? We've finished our preliminary design for the plant and we're beginning component level testing and materials testing of key pieces of it. We're doing a 520-megawatt electric design so the right size to replace coal plants in the future that'll fit on a ten-acre site. But now... just as in the early days of the industry the science isn't going to be enough. Getting the world to embrace a new form of power generation, especially one that comes with as much baggage as atomic power, is no small task. It's going to take years of testing and building and planning and trying things out. And just as before, it's going to require very broad social and scientific and political support and... simply optimism in order to get everyone to... to rouse everyone to overcoming their doubts and their fears. I'm committed to making this vision a reality and I hope that you all join me in this quest. Thank you so much.