 Welcome everybody. Thank you so much for being here. We're very pleased to have Rod Ewing here to talk to us about the promise and peril of nuclear. Rod is a professor in nuclear security and a senior fellow at the Freeman's Bogley Institute for International Studies and the Free Court Institute for Energy and I'm sure many other things as well. So we're very happy to have Rod here. Please take it away. All right. Well, good morning. And welcome to Stanford under very difficult circumstances. We're a small enough group that actually as I'm giving lecture just shout out and feel free to interrupt me, but then I may push along with my eye to the clock. So you can put questions also on chat or I've inserted time within the lecture where I'll pause and gather up your questions oral or on chat and discuss them. So let's do it this way if it's a point of clarification then shout out so I can address it immediately. If it's a larger question, wait for the question section and there'll be two one in the middle and one one at the end. I'd like to start by looking at the results from the poll. I had two questions and this is mainly for my information. The first is will nuclear power be an important source of energy for the United States in the future. So and the second is, does nuclear power play a significant role in reducing greenhouse gas emissions. So if you could just answer those questions. The majority of you think that nuclear will play an important role of as a source of energy for the United States in the future, and you 100% think it plays a significant role. Could could play a significant role in reducing greenhouse gas emissions. Alright, good. That gives me some idea of your positions. And I'll, as I shape what I say, I'll try to challenge some of your fundamental assumptions. Okay, let's get started. Well, what I'll talk about of course is heavily shaped by my own background in my research interest. My research interest has to do with nuclear materials, everything from spent fuel to the high level waste associated with reprocessing of spent fuel to nuclear materials, physical materials that now require disposal. So, mainly, my work deals with the back end of the fuel cycle. There's a lot of different perspectives that one can take on nuclear energy, looking both at its promise or its peril, protect, protect one of the, let's say, most common value seen in nuclear power is if you look at the diagram on the upper left. It shows the increasing CO2 concentration here's atmosphere. This is an old diagram would now pass 400 parts per million of carbon dioxide. So, climate change is a major concern. And a question is what would be the role of nuclear energy and reducing greenhouse gas emissions. There are concerns with nuclear power or nuclear things, let's say, the proliferation of nuclear weapons. This is an atmospheric test in Nevada. On the upper right, you can see the diagram which is an inventory of the global inventory of plutonium. And so you can see that the world has two problems. One is increasing CO2 concentrations in the atmosphere. But we also suffer from increasing plutonium inventories as plutonium, a manmade element, grows into the fuel of nuclear reactors. And then there's the issue of catastrophic failure of nuclear power plants. This is a picture of Chernobyl, but it could just as easily have been a picture of Fukushima. So, nuclear energy, or I would say better nuclear processes, have really important positive elements, primary among them I would say is the production of energy, but nuclear processes provide for medical treatments. Some would argue it's a deterrent against global war health applications and so on. And at the nuclear peril side, this is a slide from a colleague Sieg Hecker. It's nuclear war, proliferation of nuclear weapons, nuclear terrorism, radiological terrorism, health and environmental disasters associated with let's say the catastrophic failure of nuclear power plants. So I always like to go back and look at a little bit of the history and emphasize a few points. And considering the history of all things nuclear during the 20th century, probably the most important day was December the 2nd 1942. When Enrico Fermi and his colleagues demonstrated that it was possible to have sustained nuclear reactor reactions, and I'll discuss what that means in a moment. This event was the culmination of the exciting physics during the first half of the 20th century. And I just want to touch on a few of the names that played a critical role in getting us to the point of this first reactor. This is a Chicago pile one reactor built by Fermi and colleagues under the stands at the stag field. And so let's look at some of the major players. Probably the most important person in this story is Marie Curie and her husband Pierre Curie. He's a mineralogist as well. And so this is Gledowsky, Marie Curie's maiden name was Gledowska. And this is curate for Pierre Curie, both uranium minerals. For, as I mentioned, people, I'll try to give you a reference that you can go to to get, of course, much more of their interesting story. But Marie Curie as a graduate student didn't discover radioactivity, but she invented the word radioactivity. She's the only person to have received two Nobel Prizes in two different sciences, in this case, physics and chemistry. Her first prize in physics was shared with her husband, Pierre, and Becquerel, the discoverer of radioactivity. Originally, she wasn't on the list to receive with the other two, the Nobel Prize, but her husband, Pierre, with great justification, refused to accept the Nobel Prize without including his wife, Marie. So the discovery of radioactivity opened up a whole new type of physics, and I'm going to skip over a very interesting story. But it became even more interesting with the work of Otto Hahn and Fritz Strassman during, or just before the Second World War, where Otto Hahn and Strassman, this is their experimental apparatus, you can see it's very crude, discovered that when they irradiated heavy atoms with such as uranium with neutrons. They created some new elements, in this case, barium 141. Strassman was the chemist who was responsible for doing, I would say, the most important part of this work that is identifying the elements that went with the irradiation. Now, this experiment was based on the idea that if one irradiated heavy elements with neutrons, one would get even heavier elements. So they were very confused by the fact that they were getting lighter elements, and that confusion. So they reported the results. But more importantly, by letter, they sent the results to Lise Meitner. And Lise Meitner had been a member of the Institute in Berlin, being a woman and Jewish. She had never been allowed inside the big building, the big building is there. She did all of her work in a small, almost hut behind the building. And then in the 1930s, I've forgotten the exact year, she fled to Sweden with the help of her colleagues to escape the Nazis. She was in Sweden when she received news of this strange phenomena. Her nephew, Otto Frisch, was a physicist. And so on a ski trip, and in discussions, what they realized is that if they took the drop model of the nucleus developed by Niels Bohr in Copenhagen, they could describe a process or imagine a process that would lead to the splitting of the atom. And this was the origin of the word fission. Otto thought of this. And the beginning of the story of nuclear fission, nuclear energy and nuclear weapons. Otto Frisch during the war found his way to Los Alamos. He was part of the Manhattan Project. He did some very exciting and interesting experiments. One called tickling the tale of a sleeping dragon where he would do experiments to determine the critical mass. I'll discuss that more later of uranium and plutonium. Once it was realized it was possible to split the atom, a Hungarian physicist, Leo Slazar, realized that it might be possible to have a chain reaction, a sustained chain reaction, because in addition to splitting the atom, there were some extra neutrons. And so he envisioned this series of steps that would occur very rapidly, release huge amounts of energy. Slazar had fled to the United States. And it was Slazar who really coached Einstein in writing the letter to President Roosevelt, pointing out that this was potentially an important source of energy that could be released by a bomb. So that letter really initiated the Manhattan Project and we'll say a little more about that later. Enrico Fermi, an Italian physicist, his Nobel Prize was in 1938 his wife was Jewish, and they went to Stockholm to pick up his Nobel Prize. And that was a little bit of a ruse in that he was actually on his way to the United States fleeing fascist Italy. And so he joined the Manhattan Project and led the team. He was first at Columbia, designing very crude concepts for a reactor, but then finally demonstrating what Slazar had proposed that it was possible to have sustained nuclear reactions. That brings us to 1942. So this is about 78 years ago. And one thing that's important to realize about nuclear weapons, nuclear energy, in many ways, this is an old technology. The generation is excited by an entirely different array of technologies. Nuclear somehow is old hat and concerns for weapons proliferation. Development of new nuclear reactors. In some ways I would say this is fallen by the wayside. The reactor already in this picture, you can see some of the important components, the graphite blocks, their 45,000 bricks of graphite. We'll have to discuss what that's for in a moment. 45 tons of uranium metal 45 tons of uranium oxide. And this fellow here is in charge of a big device that would with by cutting a rope, a rod would drop into the reactor. A rod made of cadmium that would absorb neutrons if the reactor got out of control. You'll see there's no shielding. There's no water surrounding the reactor is shielding and also to cool it. It's been demonstrated at about half a watt. So, but this reactor once in 1942 it had been demonstrated it was possible to have a sustained nuclear reaction led to the construction of the be reactor at Hanford, Washington. That's now a national monument and the be reactor, you can see this wall was a huge to don't plutonium production facility. And you'll, I'll talk about the fission process in a moment. It was built in just a year. And you would take your uranium, put it in aluminum tubes with the diameter the size of a quarter, and you can see the holes in the front of this reactor. You would push those tubes through the reactor operating reactor. The uranium would be converted to some plutonium. You'd leave the these capsules inside the reactor. And then finally push them out the other side where there was a big collection pool. And then those capsules would be chemically processed to reclaim the plutonium, and this plutonium would be used later to bomb Nagasaki. That's on the weapons side. On the power side the first reactor was in the US was a ship shipping port atomic power station in an Ohio River in Pennsylvania. It went online in 1957 so just note that that took some time. And in fact this is the core of the reactor, and that core was originally destined to be a power source for an aircraft carrier, nuclear aircraft carrier that was canceled. There is this close connection between nuclear energy and nuclear power, particularly in the the earliest days. Where are we today on the nuclear power side. I didn't update these figures this is 2017. There are over 400 nuclear power reactors generating nearly 400 gigawatts of electricity around the world. In the US. We have a decreasing number of reactors were down to I think 99 reactors today. And those 99 reactors account for about 20% of the electricity that's used in the United States. That's decreasing slightly it may be down to 19 or 18% globally. Ask us the question well what's happening to this idea of nuclear power. This purple is North America US and Canada. Canada also has nuclear power. You can see that it's pretty constant in. Sorry for the clock in the background. You can see that the number or the amount of electricity generated by nuclear power is pretty constant. But the growth. Most recent growth in the use of nuclear power is in Asia, mainly China. In China, there are nine reactors under construction, about 40 that are in the planning stages, not all of those will will finally be built. But some projections suggest that by the year 2030 just 10 years from now. China will surpass the US. China will be generating more electricity. From nuclear fission than the United States does. Now, the, even with that rapid expansion and that's very rapid expansion, the same projections say that that then only four to 5% of the electricity consumed. That would come from nuclear power plants. Okay, now, it's easy to just focus on the nuclear power plant and the generation of electricity. But it's important to realize with any energy source. Before and after the before is the exploration for an extraction of the material used to generate the energy. And the after is the waste. So for fossil fuels of course petroleum exploration, coal mining. These are at the front end of the fossil fuel cycle. And at the back end of the fossil fuel cycle we would find the greenhouse gas gases there that are emitted during the combustion of these fossil fuels. The physics and chemistry of the process. The cycles are different. And the nuclear fuel cycle is unique in that there's this recycle arrow, which we'll discuss in a moment. But there's the possibility in a nuclear power plant to generate fissile material that then can be used to create more energy so this is, you may have heard the expression breeder reactors. We don't have time to go through all of these steps. But each of these steps has implications not only for nuclear power, but can be related back to nuclear weapons proliferation. Now, let me dwell a little bit on the physics of fission. This is very elementary. So it's not even the physics of fission just some perspectives on fission. So the whole idea is to split an atom. This is what Han and Strassman demonstrated. And with the splitting of that atom. The fission fragments for Han that was the barium 141. Some extra neutrons for those are those were what would drive succeeding splitting of the atoms the chain reaction, and the energy, which can either be released essentially instantaneously in a weapon. Or if controlled that energy 200 MeV for every splitting event could drive a nuclear power reactor. Now, as it happens, there are different isotopes of uranium uranium 235 is the one that's fissile, meaning it's most easily split by neutrons. These neutrons though have to be slow called thermal neutrons. And by slow, I mean that the energy that this impending neutron has is a fraction of electron volt. These neutrons are traveling at about two kilometers per second. The neutrons that result from the fission event. These are fast neutrons. They're traveling at about 20,000 kilometers per second. Their energies of let's say two to three MeV the energy. Again, as I've said is 200 MeV. The fission fragments, you split the uranium atom so you end up with a bimodal distribution of new elements shown here this is the Z number the mass number. I'm sorry mass number across the bottom, not Z. So that's understandable. And in fact most of these fission product elements are the nuclear waste that finally will have to deal with because they're highly radioactive. Many have short half lives, but a few by a few I mean four or five they have half lives stretching to hundreds of thousands to millions of years. The extra neutrons, the extra neutrons, the fast neutrons have to be slowed down in order to be slow enough to interact with the uranium 235 nucleus. We slow them down by surrounding the fissionable material with light elements. So that when the neutrons bounce off these light elements they slow down. And so that's the role of carbon, we saw that with the Chicago pile number one, or you could use water. But you need to slow down these extra neutrons to propagate the chain reaction by splitting the uranium 235 nucleus. The uranium 235 is only 1% of the uranium we dig out of the ground. And so in order to sustain a nuclear reaction, we typically not always it depends on the design of the reactor, enrich the uranium 235 from less than 1% to maybe four to 5%. And so in order to avoid geometry matters. That is, we want the reaction, the nuclear reaction to occur in a shape that saves neutrons, and you save neutrons by having a lower surface area. So that you lose fewer neutrons to the surroundings. Neutrons and slow neutrons. When they interact with the more abundant isotope uranium 238, it makes up about 99% of what natural uranium or consist of. But it absorbs that neutron creating uranium 239. There are a series of decay events, and you create plutonium 239. Plutonium 239 is fissile. And so it grows into the fuel from the more abundant neutron capture reactions on uranium 238. And since it's fissile, it also in a nuclear fuel visions and generates energy. In fact, in a normal reactor commercial reactor about a third of the energy generated comes from fissioning plutonium 239 plutonium is very important. In fissile, you can make a weapon with it. So that means if you take the used fuel and chemically separate the plutonium from the uranium, then you have material for a weapon. Now I know this is a little fast but I'll repeat some of these points as we come to their importance. Is this important or what is the source of the energy and has to do with this curve, the binding energy curve. There's a nice short book by John McPhee famous writer on the binding energy curve and it's a weapon scientist. But what this shows very quickly is that they're the bond, the binding energy per nucleon per proton or neutron in the nucleus is highest for iron and nickel elements in that part of the periodic chart. It's lower for very heavy elements, and it's much lower for very glide elements like hydrogen and helium. This means that you can increase the binding energy when you as an example split the nucleus, you move it toward a more strongly bound nucleus. And that releases energy or one could take light elements and fuse them. And that releases releases energy and that additional energy from fission and fusion comes from a slight loss of mass using Einstein's famous equation. There's huge amounts of energy because after all this is the speed of light squared a very large number. Okay. So, with fusion we, we can have hydrogen bombs with fission, we can have bombs such as were dropped on Hiroshima and Nagasaki. Okay. In the fuel cycle. There are two possibilities, an open fuel cycle in which we mine mill and here's the enrichment step for the uranium 235. We fabricate a fuel that goes into the reactor, we irradiate it, we pull it out. We let it cool down because it's thermally hot, and then we dispose of it for an open fuel cycle. So, because of nuclear proliferation proliferation, the enriched uranium, once enriched to much higher levels of uranium 235 can be used for a weapon. The closed fuel cycle such as practiced by the French goes through the same steps. You have enrichment of the uranium. In the process, they reclaim, sorry, I'm pointing to my screen, they reclaim the uranium and plutonium run the plutonium back through the reactor this can be done several times, and get additional energy. In this case, the enriched uranium can be used to make weapons, or if the plutonium is diverted from the chemical processing plant such as has had, has happened in North Korea, that plutonium can be used for a weapon. In the US, we've had two fuel cycles for nuclear power. We fabricate fuel, run it through a reactor, and that fuel is not reprocessed. It goes, hopefully, to geologic repository. On the defense side, we've had reprocessing, reprocessing of reactor fuel that reactor, the B reactor at Hanford are reprocessing of submarine fuel. We fabricate waste from that, the process, high level waste, those are the fission product elements that by modal distribution, and then material true waste transuranic waste material contaminated mainly by plutonium. This is just a picture of the spent fuel as it comes out of reactor. It's fractured. It's about a centimeter across. It's fractured because the thermal gradient from the center to the edge of this one centimeter in diameter pellet is about 1300 degrees C. And you, when you look in more detail, you see these bubbles, the bubbles come from the fact that some of the fission product elements in that by modal distribution are gases, and so they accumulate in, in the structure. In fact, about 3% of spent fuel consist of these fission product elements after an average burnout. And it's important to realize in terms of disposal. Those in red are quickly released, and those in blue are less quickly released. And so the disposal problem with spent fuel is not only the uranium, not so it's such a serious and challenging problem, but this gives you an idea of the array of fission product elements in their location in the fuel. The US now has about 80,000 metric tons of fuel. And depending on whether reactors are renewed or not, we can expect to have about 130,000 metric tons of fuel. On the defense side, we have a considerable amount of high level waste. That's from the reprocessing of fuel from plutonium production reactors. And this also requires disposal. This is just a chart of kind of the list of waste in the US in 2010. I'll simply point out that spent fuel from commercial power reactors. Now, as I said, 80,000 metric tons in terms of curie content, about 40 billion curies is the main actor in terms of what we have to do. So commercial nuclear power plants are generating in terms of activity, radioactivity, a tremendous amount of waste. Although the volume is contained and very small. I won't dwell on Yucca Mountain, but if you follow this subject at all, you realize that the sole repository for high level waste in the US proposed repository with Yucca Mountain that's met with much resistance in Nevada. And so the history of nuclear waste management and disposal in the US is an expensive and sad story. So I've touched on nuclear fuel cycles. They affect the carbon cycle in different ways. The geochemical cycles here refer to nuclear waste. Okay, let me just say a little bit about the weapon side. I'll just use two or three minutes so you can ask a few questions if you want. So those plutonium production reactors that led to the gadget, which was tested at the Trinity site in New Mexico. This is a spherical bomb. It was made of pipes, and it was tested in July 16 1945. So 75 years ago. It was a sobering demonstration of the power of nuclear weapons. And the power comes. And we've already discussed the physics a little bit from two approaches. You can have a gun type assembly where you take uranium 235. Two pieces. And using conventional explosives, you drive them to one another, reach a critical mass, and you have an explosion. Or you can take the plutonium 239 and I showed you where the uranium 235 and plutonium 239 come from and using high explosive focus collapse the volume of the plutonium 239 pit. Get an explosion and gun type assembly was type of weapon dropped on Hiroshima. The implosion assembly using plutonium was dropped on Nagasaki. The devastation was complete. The number of lives lost was between the two cities, let's say several hundred thousand. This initiated an arms race, which you can see part of it listed here with the different countries who have developed nuclear weapons and of course, there are others such as Israel, North Korea, and Iran is was and is on the way. Big change in the 1950s was the fusion hide the hydrogen bomb, taking advantage of fusion of light light elements. And the, the challenge is that we have a lot of fissile material around the world. And commercial power plants, which we often think of as not part of this story as part of the fuel cycle for nuclear power plants with separated plutonium and it amounts to an equivalent of 53,000 weapons. I'll just say the doomsday clock has never been. This is both an atomic scientist was created at the end of the Manhattan project in the 1940s. The doomsday clock tells us how far scientists thinks we think we are from nuclear Holocaust. And when the hydrogen bomb was developed, it was at its lowest point, which was two minutes to midnight, but now we're 100 seconds to midnight. I can't tell you why, but this is the lowest it's ever been the most dangerous time. And I commend to you a very recent book out in the last few months by Bill Perry and Tom Kalina that will tell you why so sorry to take so much of the question time but now I'm open to questions so just cut cut me off when I will. We do have one question in the chat which I think you answered at least in the aggregate but I'll get started with it which is how much radioactive waste as a nuclear plant generate I imagine the average plant. Okay, so annually each nuclear power plant, on average, generates 20 metric tons of used fuel. And that's where most of the radioactivity will be. There's also intermediate and low level waste associated with just running the plant. But in terms of radioactivity. It's the spent or used fuel that is the source of most of the waste. Katie go ahead and or Kate sorry go ahead and ask your question. Hi, and that was really helpful first also thank you. I have been really interested in development work, and I've heard a lot about like modular nuclear power units, especially being developed by like Bill Gates, my company's associated with him. I'm curious to hear your thoughts on like the potential for that powering developing regions. And if you think there's like any risks. Okay, so the answer is necessarily complicated. I'll give you the very short answer. So the attraction for small modular reactors is reduce costs because they're modular. And because they're smaller than they can be placed around the country and for specific applications. So the, and the, the regulatory process would be simpler if we all built the same kind of reactors and the nuclear regulatory commission was familiar with them and just could approve them. So those are positive. But what you have to realize is that after all their vision reactors. So it doesn't matter whether you have your vision event in a large gigawatt facility, or in a smaller modular reactor. As long as you're making a lot of electricity or heat from larger small reactors, you still have the vision product or the waste problem to deal with. And the waste problem is not only disposal, but keep in mind, it could involve processing the fuel, certainly involves transportation of the fuel. So to this extent that let's say small modular reactors are successful economically. I would say I'd like to, to understand why they would be considered successful from an environmental impact point of view. And that really hasn't been addressed. Yeah, I had a quick question. Given the urgency that a lot of people talk about greenhouse gases and everything. The environmental impact obviously of the way you know storage processing transportation of spent fuels is a big thing but basically what's your opinion on the future of nuclear is a lot of pros and a lot of cons. That's a great question. That's a good way to maybe end our session. So I've been to many conferences where nuclear power is the answer. Okay, it does, you know it's CO2 or greenhouse gases aren't emitted except in a very smallest scale. Most of, and then the discussion is on advanced reactor systems. And those advanced reactor systems are projected by the nuclear community. I'm a member of that community to come online in 102050 years. And my concern is, that's not soon enough. If nuclear is the answer, then it has to arrive on the scene and at a scale that can have an impact on the carbon cycle. And that's tough. Just to give you an idea, if we wanted to hold CO2 emissions constant. You may be familiar with the concept of wedges by Soklo and Pagala. And if not, I'll just say it. If we doubled the number of reactors worldwide, which means more than doubling because many need to be replaced. That could only contribute about one eighth of what we need in order to bring CO2 emissions to a constant level, not a decreasing level. So doubling or tripling or quadrupling. This is a huge job in the best of times. And it's an even larger job if you're on a tight schedule. So the key is timing and scale.