Passive Underwater Fire Control Feasibility System

Transcription

Here's sodium. Who wants to throw it in? Alright go. Whoo! It lights on fire then it explodes. Oh, no. I have some good friends in the nuclear industry that are very big advocates of the fast-breeder reactor. The common name for it now is the integral fast reactor. Personally, I'm not the biggest fan of a reactor that's full of liquid sodium. It's stored under an oil to stop air or moisture getting on it. It reacts very, very quickly with air and also with water. With the hydroxide there's a white crust on the outside. It's fizzing around because it's generating lots and lots of hydrogen gas. The heat from the reaction is burning away all of that hydrogen. You don't want to build a reactor out of stuff that wants to burn, react, anything. You want to go, "Whatever I've made you out of, I want it to be like the rock bottom of stability. I want there to be no step further down that is chemically favorable because that's how things burn." The fast-breeder guys that use sodium, because it doesn't slow down the neutrons. Everybody who is pushed in plutonium said, "We want a fast reactor. That's the only way to do it." Notion of public being intimately involved in very complicated technical issues which went way beyond the confidence of any member of the public. Just in same that that was the right way to do it. The basic question is, "Can modern intrusive technology and liberal democracy coexist?" The decision that was acceptable is not something that we, technologists, can make. It's something that the public makes. A lot of people were daunted by new [inaudible 02:21] . There's no way we could learn this stuff. I don't want to do that class. It can be too hard. These three clones are generally associated with three different nuclear fuels. Liquid sodium-cooled reactors are fueled by natural uranium. Water-cooled reactors are filled by enriched uranium. The molten salt reactors can be fueled by thorium. The reactors deployed commercially around the world are water cooled. Today, we use water to cool reactors, because we use enriched uranium as fuel. We use enriched uranium as fuel in today's reactors, because they are water cooled. Despite sodium's reactivity with both air and water, it is, in some respects, a safer coolant than water. This is because our enriched uranium-fueled, water-cooled reactors pressurize the water to raise its boiling point and drive steam turbines more efficiently. If we didn't pressurize the water, then we'd be using much more uranium and producing much more nuclear waste per watt of power. In addition to being a thorium guru Weinberg was also the original inventor of the pressurized water reactor. It was a little bit of a tricky thing to have the inventor of the light water reactor advocating for something very, very, very different. As long as the reactor was as small as the submarine intermediate reactor, which is only 60 megawatts, then containment was absolute. It was safe. But when went you went to 1,000-megawatt reactors, you could not guarantee this. Weinberg never really was crazy about the light water reactor. He didn't like the fact that it had to run at really high pressure. He figured there would be an accident someday where you were not able to maintain the pressure or keep cooling it. In some very remote situation conceive of the containment being breached by this molten mass. A small valve in this collection of pipes is stuck in an open position letting steam and water escape from the reactor core. It's critical that the uranium fuel rods that make up the reactor core stay under water. A yellow tag covers an important light. They're convinced that the core is covered by water. A huge bubble of hydrogen is forming right inside the reactor vessel. The hydrogen was generated by reaction between air and the zirconium fuel cladding, and then the hydrogen ignited from some sparks. Kaboom! The whole building shudders. I mean the whole building, the plant building. Kaboom! Somebody says, "What was that?" An explosion had taken place inside the containment building. Those gaseous fission products came out and were released to the environment. Pregnant women and preschool-aged children leave the area within a five-mile radius. It took a month to shut the reactor down, but finally unit two was stone cold dead. The biggest environmental release at Three Mile Island was krypton and xenon, but they don't have an uptake in the body. It scared a bunch of people, but it didn't hurt anybody. It really comes down to which fission product is it? I know it sounds particular. Number one, most dangerous is iodine because of the way it's taken up by the thyroid. There was a metallic taste in our mouth, an acidity. They say radiation has no taste. It was only later we realized it was the taste of radioactive iodine. Chernobyl was just a bad design in the first place. Cory Arkin and a fellow engineer wrote an article in the newspaper "Communist." It criticized the lack of safety in the design of the plants. They had these cylindrical graphite followers; they called them, that kept the water out of the place where the control rod was in the core. Well, they pulled it out so that the follower was out of the core, too. Now all of a sudden they had water turning to steam, and the pumping system capitated. The power's rising, Alex. The power's rising. I only put the turbine in. It was stable just now. We've had this. Let's stop it. Shut down the reactor! I'm trying to get it towards back in. Sir, I'm shutting down the reactor. Well, there goes the test. How am I supposed to explain that? I'm sorry, sir. It wasn't worth it. The power was gone. I didn't know exactly... What was that? The rods haven't gone in. Well, let them drop in. I am doing it. I just don't know why they didn't go in in the first place. I pressed the AZ button! They should have gone in! Maybe... A series of detonations go off in the core of the reactor. The explosion had thrown the 2,000-ton reactor lid in the air. It fell on edge into the mouth of the reactor vessel. Pieces of the core were scattered all around. The core just burned for days. A lot of radio-nuclides were released to the environment. The white flashes on these images are the results of radioactivity on the film. People in the streets hardly can hide at the masked soldiers scattered throughout the city. At first I was told there hadn't really an explosion. The consequences of such false information were particularly dramatic. Windows and doors should be sealed and iodine tablets swallowed to counteract the effects of radioactivity, yet no such orders have been given. Taking potassium iodide can help the thyroid not absorb radioactive iodine. It prevents your thyroid from taking up the radioactive stuff because it will be plum full of the not-radioactive kind. 30 hours after the explosion more than 1,000 buses arrived. The army announces the city is to be completely evacuated. It exploded when you hit the AZ button. Why didn't it stop the reaction? They say there wasn't a design flaw, but how else do you explain it? They'd know. If they knew, they'd tell us. They weren't aware of the facts. The potential neutron surge as the graphite tips reentered wasn't known. Known by whom? Nobody told them. Nobody. Controllers are made of boron, but they're tipped with graphite. Now in '83 a big lean on a similar reactor we found that in certain circumstances when the graphite enters the water, it causes a power surge. A power surge. If you do stupid designs, something bad will happen even after 40 years. A friend of mine was GE's first nuclear safety engineer. He worked on the Fukushima plant, and they would have meetings with the TEPCO officials and engineers. They would all nod their heads in long meetings and say, "Oh, yeah. We'll do this. We'll do that." Then they'd go off after the meeting and do whatever they wanted. That's why you had a 15-foot seawall with a 45-foot wave coming over it and diesel generators and fuel in the basement. The earthquake that shook the Fukushima Daiichi nuclear power plant was the most powerful to strike Japan since records began. The Japanese TV station's NHK offices across the country shook. I couldn't keep standing. Fires burned across the northern part of the country as gas lines ruptured, and this oil refinery was engulfed in massive flames. The skyscrapers nearby were swaying like trees in the wind. The workers stayed calm because they knew Japanese power plants are designed to withstand earthquakes. The reactors automatically shut down within seconds, but nuclear fuel rods generate intense heat even after a shutdown. Backup generators kicked in to power the cooling systems and stopped the fuel rods from melting. High-pressure water coolant reactors have an abundance of safety systems designed to always keep the core covered with water. We saw the failure of the Fukushima Daiichi. They had multiple backup diesel generators, and each one probably had a very high probability of turning on at any given time. They were there, several of them, so that if one didn't the next one would. If it didn't, the next one would. Well, the tsunami came and knocked them all out, and that's what called a common mode failure. At NASA we were always thinking about how could we have a common mode failure that just trashes our idea of redundancy. Tepco had been warned by a government committee of scientists in 2009 that its tsunami defenses were inadequate. [background noises] It was more than twice the height of the plant seawall. The waves were relentless. [sea waves] Zooming everything in their path and watch as it destroys an entire village while still burning fires ride the waves. Hundreds of cars were swept along the current. Around 20,000 people were dead or missing. The coastline was devastated. Most of the backup diesel generators needed to power the cooling systems were located in basements destroyed by the tsunami waters. The workers had no functioning instruments to reveal what was happening inside the reactor cores. All of us, we had a car rustic batteries. The [inaudible 11:56] batteries allowed vital monitoring instruments to work again. The levels caused panic. Pressure was going up and up. Everyone thought, "Isn't this dangerous?" The rising heat of the fuel rods and the reactor core was creating massive amounts of radioactive steam and hydrogen. We begin by making these uranium oxide pellets, and we formed them into fuel rods, plaid in this zirconium. It turns out the zirconium, in certain conditions, can be quite reactive... With the water that's surrounding the reactor. We have a fuel and a coolant that are inherently incompatible with one another. That's how we run nuclear today. As night fell, the Japanese government ordered an evacuation of everyone within two miles of Fukashima Daiichi. Radiation levels were now rising. This isn't inside the reactor itself. It's in the office. The engineer suspected something that Tepco would not acknowledge for months, nuclear meltdown have begun. The prime minister began to suspect that Tepco was hiding the truth. He decided to go to Fukashima Daiichi himself. The prime minister met directly with the Tepco engineers. The radiation near the vents was at potentially fatal levels. His orders might condemn the men who went into the reactor to death, but he felt Japan's future was at stake. The workers found the wheel for opening the vent. They inched it open. A thin, plume of gas signaled that the pressure on the reactor core was falling. With the vent incomplete, the workers could focus on getting vitally needed water into the reactor cores. Suddenly, the ground shook. Leaking hydrogen had exploded the roof of the reactor building, but the reactor core itself was intact. Iodine tablets were being handed out in the village. I made my daughter take one. The government widened the evacuation zone, ordering everyone within 12 miles of the plant to flee. The explosion had already set back average to get water into the melting cores of reactors one and two. Now, reactor three was also in meltdown. Another hydrogen buildup meant the reactor three housing could explode at any moment. Colonel Shinji Irokuma and his team's mission was to inject water directly into the core of reactor three. Just as we were about to get out of the jeep to connect the hose, it exploded. Our dosimeter alarms were ringing. Lumps of concrete came ripping through the roof of the jeep. The soldiers were now surrounded by radioactive debris. They were injured in the blast but managed to flee the scene before anyone received a fatal dose. The Japanese prime ministered ordered a desperate tactic, dumping water on the spent fuel pools from the air. Tungsten plates where in-bolted to the helicopter to protect the pilots from gamma rays, but the wind was too strong for accurate aiming. The Japanese government ordered a team of Tokyo fire fighters to park a truck by the sea to suck up water and lay 800 yards of hose and leave it spraying into the fuel pool. The route was blocked by tsunami debris. The firefighters now had to lay the hose by hand. After an hour on site, the hoses were finally connected. Radiation levels at the plant began to fall. The hundreds of workers who had been on standby headed into the plant to lay miles of pipes. A steady flow of water at last started to cool the reactor cores. The workers in the control center began to feel hope. Three Mile Island, Chernobyl, and Fukushima, were all radically different incidents. What was similar at all three was how poorly water performed as a coolant when things started to go wrong. This is not to say that water coolant caused these accidents to occur, it did not. All three accidents were initiated by different combinations of design and operator error. It was water coolant which allowed these errors to multiply and ultimately result in the escape of radioactive isotopes into the environment. At Three Mile Island, water couldn't be pumped into the core, because some of the coolant water had vaporized into steam. The increased pressure forced coolant water back out, contributing to a partial meltdown. At Chernobyl, the insertion of poorly-designed control rods caused core temperature to skyrocket. The boiling point of the pressurized water coolant was passed, and it flashed to steam. It was a steam explosion which toward the 2,000 ton lid off the reactor teasing and shotted up through the roof the building. At Fukushima, loss of power to the pumps allowed coolant water to get hotter and hotter until it boiled away. These three accidents illustrate the need for a coolant with a higher boiling point than water. It's only got 100 degrees of liquid range, zero to 100 C. That's not really particularly impressive. To jack up water's liquid range, you have to put it under pressure, because that's the only way to get water to go up to 300 degrees C without turning into steam. Super high pressure is one of the basic challenges, difficulties, flaws, whatever you want to call it of the water cooled reactor approach. The salts, on the other hand, you have to heat them up to about 300 C before they melt. Once they melt, they have 1,000 degree C of liquid range. Safety is one of the most important reasons to consider very seriously molten salt reactors. This is because of the clever implementation that was demonstrated in the molten salt reactor experiment of the freeze plug and the drain tank. It was just a small port in the bottom of the reactor that was kept plugged by frozen plug of salt. To keep the port plugged, they had a blower that would blow cool gas over it. There's a little plug of frozen salt there. If the power went out, the blower turned off, and the heat would melt the frozen plug. Guess what. The fuel drained into this drain tank. The difference between the drain tank and the reactor vessel was the reactor vessel was not meant to lose any thermal energy. The only place you want it to lose thermal energy was to give it up in the primary heat exchanger. The drain tank, on the other hand, is designed to maximize the rejection of thermal energy to the environment. I'm a mechanical engineer, so all we ever talked about in school was how to add heat to things and take heat out of things. One of the hard things about designing nuclear reactors is to design it to not lose any heat while you're running it, because you don't want to lose a bunch of heat in normal operation, but then to turn around and try to keep it cool if something goes wrong. There are two conflicting things. The great thing about liquid fluoride reactors is you can design them completely separately. You can say, "Here's my reactor and it's designed to make heat, and here's my drain tank and it's designed to cool in all situations." Better than having what's called deterministic safety systems or engineered safety systems is to have inherent safety systems that will work 100 percent of the time, because it is based on the laws of physics. A cooling system that is completely passive, that does not rely at all on electrical power to manage the decay heat after shutdown, it is always going to work because gravity is always going to be turned on. Because it was not operating at high pressure, this is a system that was tolerant of extraordinary damage. If you wanted to go in and jam a projectile through the side of the reactor, the salt would still just drain out, now into a pan but the pan would run back into the drain tank. In that situation, you're not going to turn the thing right back on again. But it's not going to lead to a dangerous release of radioactivity. At Three Mile Island, coolant water which had boiled into steam reacted with the fuel rod cladding to produce hydrogen gas. This led to several explosions. At Fukushima, steam also reacted with the fuel rod cladding to produce hydrogen gas. This lead to hydrogen gas explosions at reactors one, two, and three. Let me diss on water a few more times. [laughter] It's a covalently bonded substance. The oxygen has a covalent bond with two hydrogens. Neither one of those bonds is strong enough to survive getting smacked around by a gamma or a neutron. Sure enough, they knock the hydrogens clean off. In a water cooled reactor, you have a system called a recombiner that will take the hydrogen gas and the oxygen gas that is always being created from the nuclear reaction and put them back together. It's a great system as long as it's operating and the system is pumping. Well, at Fukushima Diiachi, the problem was the pumping power stopped. H20 can also react with the fuel cladding to release hydrogen and damage the cladding, releasing radioactive isotopes. These two accidents illustrate the need for a coolant which is more chemically stable than H20. A nuclear reactor is a rough place for normal matter. The nice thing about a salt is it is formed from a positive ion and a negative ion, like sodium's positively charged and chlorine's positive charged and they go, "We aren't really going to bond. We're just going to kind of associate one with another." That's what's called an ionic bond. You're kind of friends. Facebook friends. [laughter] Facebook friends. Turns out this is a really good thing for a reactor because a reactor's going to take those guys and just smack them all over the place with gammas and neutrons and everything. The good news is they don't really care who they particularly are next to as long. As there's an equal number of positive ions and negative ions, the big picture is happy. A salt is composed of the stuff that's in this column, the halogens, and the stuff that in these columns, the alkalis and the alkaliners. Fluorine is so reactive with everything, but once it's made a salt, a fluoride, then it's incredibly chemically stable and non-reactive. Sometimes people go, "You're working on liquid fluorine reactors." No, I am not working on liquid fluorine reactors! We talking about fluoride reactors and there's a big difference between those two. One is going to explode, the other one is super-duper stable. I see moving to molten salt fueled reactor technology is a way to get rid of all the stored energy term problems that we look at in today's reactors, whether it's pressure, whether it's chemical reactivity, even the potential of the fission products and the fuel itself to be released. In fluoride fuel, which is what we would use in a molten salt reactor, those fission products are bound up very tightly in salts. Strontium and caesium are both bound up in very, stable fluoride salts. Caesium fluoride, very stable salt. Strontium bifluoride, another very stable salt. In light water reactors, cesium is volatile in the chemical state of the oxide fuel of a light water reactor. That's been one of the concerns about cesium release. Cesium would not release from a fluoride reactor at all. Why are we using water to cool today's reactors? If water coolant prohibits us from completely consuming uranium or thorium as fuel, why did we start using it in the first place? The association between different nuclear fuels and their respective coolants is because some nuclear fuel requires slow neutrons and some nuclear fuel require fast. There really were three options for nuclear energy at the dawn of the nuclear era. Only one of the materials in nature is naturally fissile and that's uranium-235, which is a very small amount of natural uranium, about 0.7 percent. This was the form of uranium that could be utilized directly in a nuclear reactor. Most the uranium was uranium-238. This had to be transformed into another nuclear fuel called plutonium before it could be used. Then there was thorium. In a similar manner to uranium-238, it also had to be transformed into another nuclear fuel, uranium-233, before it could be used in a reactor. Nein, nein, nein, nein, nein, nein! This was wartime. They're plan was to make bombs. They took natural uranium and they separated those two isotopes. They would highly enrich uranium-235 from less than 1 percent up to like 90 plus percent. Too big factories, very difficult to do isotopic enrichment, but this is how they made the uranium for the first nuclear weapon used in war. This was the bomb at Hiroshima. It was called "Little Boy." Then they said, "What could we do with all this junk uranium-238, the 99.3 percent of it?" You could expose it to neutrons and you could make it into plutonium. Now, plutonium is a different chemical element than uranium, so they can be chemical separated. Uranium-235, uranium-238 are identical chemically. There's no chemical difference between them. There is a chemical difference between plutonium and uranium, so it was a lot easier to do a chemical separation of the plutonium you'd made. That's how they made the Nagasaki bomb, which was called "Fat Man." Maybe we can do the same thing with thorium. Maybe we can expose it to neutrons and we can make it into uranium-233, uranium will be chemically separable from thorium, and we can go make a bomb out of it. Sounds great. It's a really bad idea because, as you made the uranium-233, you were always making uranium-232. You didn't make a lot of it, you only made a little bit of it, but uranium-232 is much more radioactive than uranium-233. In addition to that, here's the decay chain that uranium-232 is on. It jumps down to bismuth-212 and thallium-208. These two decay products put out very, very strong gamma rays. These gamma rays are just super bad news if you want to go and build a practical nuclear device, because they tell everybody where the stuff is and they kill you. Really quickly, they were going, "We can work with uranium-235. That seems OK. We can work with plutonium. That seems, OK. But this uranium-233 stuff, that's bad news for making a nuclear weapon." Thorium was just set aside. Run! "The Wolverine," PG-13. After the war, they picked up on this again because now they were thinking, "Let's talk about making power instead of making nuclear weapons." This is the fast region. This is the thermal region. Squiggly lines, blah, blah, blah, and you could probably tell the entire history of the development of nuclear energy in this one graph. I'll tell you why. How much energy did the neutron have that you smacked the nuclear fuel with? How much energy did it have and then how many neutrons did you kick out when you smacked it through fission? Two is a very significant number in breeder reactors. You need two neutrons. You've got to have one to keep your process going, and you have to have another one to convert fertile material into fissile material. Look at plutonium. Eh, it's that dip below two right there. That's what makes it so you cannot burn up uranium-238 in a thermal spectrum reactor like a water cooled reactor. You just can't do it. The physics are against you. The reality is you do lose some neutrons. You can't build a perfect reactor that doesn't lose any neutrons. They looked at this and they said, "Man, we just can't burn uranium-238 in a thermal reactor. It just can't be done." These guys aren't deterred. They said, "Here's what we'll do. We'll just build a fast reactor because look how good it gets in the fast region. Wow, it gets above two. It gets up to three, wow! This is really good!" There's a powerful disincentive to doing it this way, and it has to do with what are called cross-sections. These are a way of describing how likely it is that a nuclear reaction will proceed. Look how much bigger the cross-sections are in thermal than they are in fast. How many of these little dots are we going to need to add up to this size? We're going to need a lot. This is why it was a big deal to be able to have performance in this region of the curve. Those little bitty dots, they're up here in this part of the curve. This is the fast region. This is the thermal region. Thorium is more abundant than uranium. All we're consuming now is that very, very, very, very small sliver of natural uranium. But this is not the big deal. No. It's not a big deal that natural thorium is hundreds of times more abundant than the very small sliver of fissile uranium. The big deal about thorium is that we can consume it in a thermal spectrum. That's the big deal of thorium is that it can be consumed in a thermal spectrum reactor. When you're talking about a thermal spectrum reactor of any kind, you have to have fuel and you have to have moderator. They're both essential to the operation of the reactor. The moderator is slowing down the neutrons. When the neutrons have been slowed down, we call them thermal neutrons or a thermal spectrum. On a water cooled reactor, we use water, specifically the hydrogen in the water, to slow down the neutrons through collisions. The graphite in the molten salt reactor, is that a moderator? Yes, that's the moderator in the reactor. Same idea, except we have graphite as the moderator instead of water. Neutrons go in the graphite, hit a carbon atoms, they lose energy, they slow down. Why slow it down? That's the difference between you're going from that little bitty dot to the big dot. That's why you want to slow it down. You want the big dot, not the little bitty dot. A thermal spectrum molten salt reactor has to have the graphite moderator of the core in order to sustain criticality. If the vessel ruptures, recriticality is fundamentally impossible. The drain tank does not have any graphite in it. If something happens where that fuel drains away from that graphite, criticality is no longer possible. The reactor is subcritical, fission stops, and there's no way to restart it without reloading the fuel back into the core. This is such a remarkable feature, and it really is unique to having this liquid fuel form and to having something that can operate at standard pressure. You can't do this in solid fuel. If you do this in solid fuel, that's called a meltdown. That's bad. Now, in a fast reactor on the other hand, you don't depend on moderator. You put enough fuel in the reactor so the criticality is possible even without moderator. In those scenarios, if there is a drain or a spill or something, you need to be careful about what geometries it can get into because recriticality is not from first principles impossible. It may be impossible in the design you design but that becomes design-specific, whereas in thermal reactor, it is just impossible. Outside of the lattice of moderator, you can't have a criticality set up. A thermal regent, look who's doing the best. Look at uranium-233. Look at that. Look at plutonium. Eh. It's that dip below two right there. You just can't do it. The physics are against you. But uranium-233 on the other hand, yeah, it gets a little better in the fast but, dang, it's still pretty dang good right there in the thermal. Big targets, lot easier. This fact was not well known probably until about the '70s. There was some data that indicated it, but there was enough uncertainty, even as late as 1969, that the Atomic Energy Commission did not feel like it was a safe bet to go with thorium. Everybody who was pushing thorium said we like thermal. This is the kind of reactor we want to build. Everybody who was pushing plutonium said no, no, no. We want a fast reactor. That's the only way to do it. What happened is they put resources into the plutonium breeder reactor almost from the get-go. They built the experimental breeder reactor one in 1951. This was the first reactor that made electricity. Four little light bulbs here. This is a mock-up of the core. This size was giving off megawatts of thermal energy. How tall is this? How many meters? Eight inches. This is actual size? No, it's scaled down. No, that's full size. EBR-1. This was a breeder reactor. It was designed to convert plutonium into energy while making new plutonium. This was not a light water. This pre-dated the light water reactor by years. It was a fast creator. 1951. This is a gen four reactor. No kidding. Early nuclear pioneers like Enrico Fermi and Eugene Wigner saw the future quite a bit differently. Fermi believed that because of the performance of plutonium, an especially because it could have a substantial breeding gain, in other words, it could make more fission material than it was consuming, that we should really focus our efforts on the fast breeder reactor. Eugene Wigner, on the other hand, looked at these same pieces of information and reached a different conclusion, which was that thorium was the superior fuel and that it should be realized in a thermal spectrum in a thermal breeder reactor. This opened up a number of possibilities with coolants and reactor configurations. Thorium, in another way, was a rather unforgiving fuel. It did not have a great breeding gain like plutonium had the potential in the fast spectrum. You had to make sure you were very careful and conserving of your neutrons. You couldn't waste a lot to losing neutrons to structural materials or losing them to leaks out of the reactor or losing them to absorptions in the daughter products of fission. The thorium also had another challenge. It took about 40 days, once it absorbed a neutron, to turn into uranium-233. There was a time delay there between when it absorbed a neutron and when it became new fuel. Fermi wondered how it would be the thorium would overcome this problem of the delay from when it absorbed the neutron to when it became new fuel. Wigner had already seen a possible path forward, which was to do something rather revolutionary. Build a nuclear reactor out of liquid fuels rather than out of solid fuels. I believe part of this came from Wigner's educational background. He was the only person, or almost the only person, who combined a great skill as a nuclear physicist with great skill as an engineer. Wigner, of course, was a chemical engineer by training. He was the only one that commanded both of those attributes. He was able to see both the engineering and physics aspects. He was a chemical engineer by training and he knew that in chemical processes the reactant streams are almost always liquids and gases. They're fluids. In fluids, complete mixing is possible and completion of the various chemical reactions are possible. He looked at the nuclear problem and wondered if the same principle might not apply. With a fluid fueled reactor, it would be possible to isolate protactinium-233 as it was formed and to allow it to decay and prevent it from being destroyed before it could complete its transition to uranium-233. Wigner was not successful in convincing the bulk of the nuclear community to take the thorium approach. They, by and large, said we're going to go the plutonium route. One of the reasons why was they had developed a great deal of understanding about plutonium from the weapons program. They had made the stuff, they had worked with its chemistry, and they had made fuel out of it. They go, "We get this. Thorium, we haven't really messed with thorium. It would be like starting over." That propensity there was to go and do what you already knew how to do. The plutonium was so much better developed than the thorium. Wigner was not terribly successful in making converts in the nuclear community, but he did make one convert. This guy, Alvin Weinberg. He was a student during the Manhattan Project. Of course I had heard of Eugene Wigner as this great particle physicist. I gradually became his assistant in charge of the nuclear design. Weinberg got it. He got the big picture. He got we need thorium, we need thermal reactor, we need liquid fuel. I see it. I see what we've got to do. We visited with Mr. Rosenthal after we met with you. He spent time in Washington DC with Milt Shaw, and that Milt actually had quite an affinity for Knoxville and Oak Ridge, but he wanted Alvin Weinberg and Oak Ridge to get on the fast breeder funding wagon and Weinberg wanted to stay on with thorium and Walton Salts. It was pretty obvious that Shaw was completely convinced the LMFBR (liquid metal fast breeder), with its sodium cooling system, was going to be successful. If we have a winner here, why spend money on what we know is going to be the loser? Everyone was so euphoric about the idea of a fast breeder? That's the way it appeared to me. The Baroness has got a bunch of people over there from GE saying you've got to go build a fast breeder. The Russians are building them and we've built a couple of them. We've had a couple problems with them, actually. In principle, I guess you could go that route. But relative to the molten salt reactor, you've got a lot of fuel cycle infrastructure you wouldn't need if you went with the molten salt reactor so I wouldn't do it. I wouldn't build fast breeder reactors if I was the one deciding. In the US nuclear Navy program, they started out with two reactor systems, one water cooled and one sodium cooled. It didn't take very long for the Navy to decide that they didn't want to deal with sodium cooling. They built a reactor and put it in a sub and they ended up cutting the reactor out of the sub and putting the LWR in it. They became disenchanted with sodium cooling rather quickly. What happens if there's a leak? Sodium reacts with the air and the water. You haven't got air next door to the sodium services. You can handle it with a freeze pads. You're not getting stuff from the core getting out into the air. People normally can't walk around the surface of this. If I've just got a little, tiny, thin pipe that can't let very much flow out you'll have a different access availability than a big sodium pipe that's two feet in diameter with several hundred pounds per hour flowing through it. What about the sodium? They're not dumb. You've got it, brother. You've got it. What's their answer? Fire suppression system. If you've got a hot, liquid, combustible metal in your iPhone, lithium, why are you allowed to walk around with it? Because lithium is in a stable compound. Actually, there's some YouTube videos of lithium not being in a stable compound. [laughs] If I had a lithium battery and I expose it to air it's not going to immediately catch on fire. Sort of uneventful. Oh well. A lithium battery catches on fire because it shorts out. It shorts out. The point is, there's a known history of lithium accidents, which are pretty bad. We don't ban them. I agree. I don't think the IFR was the best possible solution in the world, but they did have a history of proving that it could shut itself down. Total plant blackout. Simulated a complete blackout so the power was lost to all cooling systems. For fast sodium reactors, you've always got two separate loops. The primary gets radioactive from the core. You clean your dirty sodium? Yeah. Then it's the clean sodium that goes to the steam generator. If you get a failure in the steam generator wall you haven't got radioactive sodium. I got that. This thing here, there's lots of heat sink test would be turning off the power to the secondary so you're not drawing the heat out of the core/ You would shut down the tertiary, the water system. The tertiary, OK. The sudden loss of flow test, is that shutting down the intermediate? The loss of flow test is shutting off the pump, just turning off the primary pump in here. The pump for the primary sodium? Yeah. It turns off the pump that's somewhere in there. These two tests are turning off the primary and turning off the tertiary? Yeah. At all times, the core was still bathed in sodium? The sodium is turned on at all times. The only thing you're doing is you're also doing it without SCRAM. Right, without control rods going in. Without control rods going in. This gets so warm the fuel assemblies expand, the pins lengthen, they expand sideways, pressurizing up against the core rigidity structure. Achieving a strongly negative temperature coefficient in a thermal reactor is a much more straightforward proposition than in a fast reactor. It can be done, but it's easier to do in a thermal spectrum reactor. There's a lot of options. A lot of those options are connected with the process of moderating neutrons. You change something about that process and it helps you achieve a strongly negative temperature coefficient. The fuel expands, the [inaudible 41:50] expand, the fuel assemblies expand, the core support structure expands, the core plate underneath expands. This is at the molecular level in the salt reactor because it expands. The salt expands. This is the same thing, except this is done at the physical level and so in the salt it's easier to have this happen. Right. I just wanted to drill down and get some questions. Great. That was very informative. Thank you, sir. The trouble is these tests were done about two weeks before Chernobyl. Yes, I was aware of that. No one even knew about this, which is a shame. Bob? My question was this was not commercialized, right? We were going to. It was called Clinch River. I was working on Clinch River. Then Al Gore, who thought plutonium is nasty, wicked, and evil and we shouldn't have anything to do with it, persuaded Clinton to shut the program down. I've actually been to the site where the Clinch River fast breeder was supposed to be built. I hopped the fence and trespassed on federal property and walked out to the river and it's an empty field. The country thought the liquid metal fast breeder reactor was going to be the future. We've now done three of them. Two have had unintentional core melts. The last one happened in 1972 where the plant manager had to call the mayor of Detroit and say, "Prepare to evacuate Detroit." How is that Detroit reactor from here? The [inaudible 43:09] Fermi fast breeder reactor was built by Detroit Edison, made with metallic fuel like this. Actually, it went online about the same time as this one. The AEC said, "What happens if you get a meltdown?" They said, "OK, we'll put some zirconium plates underneath." The trouble is, when they put them in they only tack welded them and the vibration tore one of them off and it went up and flattened underneath, blocked out the sodium. So that's a significant meltdown, but they cleaned it all up. Milt Shaw, insisting on oxide fuel for Clinch River, wouldn't help give them some money to buy another core load. For want of a couple of million dollars, the plant went down. Good old Shaw. He's the guy who is really responsible for our trouble. Milt Shaw is quite infamous in the molten salt community. I had no idea until I read "Plentiful Energy" that Milt Shaw is infamous to the IFR crowd, as well. Boy, he was just infamous to everybody. The folks who were in support of Clinch River fast breeder reactor had very sharp elbows. Guys who were working on the integral fast reactor have just as much heartache with the focus on the oxide fueled loop reactor at Clinch River as you do. I agree. You're absolutely right. Fast reactor does not equal fast reactor. Sodium loops with pumps. That flavor, that was the project. People who wanted to do metal fuel and a pool reactor, they wanted to do molten salts, they wanted to improve the light water reactor, they wanted to prove that the light water reactor could do breeding, as well. All of those projects were put on back burners or de-funded completely. Making solid nuclear fuel is a complicated process and we extract less than one percent of the energy from the nuclear fuel before it can no longer remain in the reactor. Kurt makes a big deal about the fact that he wants to us thorium because it's 200 times better than using uranium, but using uranium is about 10,000 times better than using oil. Let's make the big jump first. The nukes, though, need to stop fighting amongst each other and compare their power plants to the real competition that holds 85 percent of the market, which is the fossil fuel companies. Nobody saw the light water reactor as the machine on which we would power our civilization using nuclear power for thousands of years. The only question is which breeder and how fast do we get to it? I got a 1962 report to the president and right in there it states this is a stop gap technology. I think these earlier nuclear pioneers would be absolutely floored to show up today in our nuclear world and go, "Oh my gosh, you're still using light water reactors? Come on, guys." We should have seen more technology advancement by now. We should have seen something better. A pressure water reactor has to take 2,000 PSI, which is a really thick pipe. It's typically four to eight inches, depending on the diameter of the pipe. We're doing new things with light water. The core, the pumps, the control rod drive mechanisms, the steam generators, the pressurizer all in one steel pressure vessel. No piping penetration is in excess of about three inches in diameter. I'm working on that exact reactor. The light water reactor is still the safest, most efficient energy source we have on the planet right now and it's a real thing. We have a big, worldwide fleet of these things that should have been bigger. We have like 400 some reactors running. All we are saying is that in the very near future we could have something that's even yet safer and even yet more efficient. If someone said all you can have are water cooled reactors of some type or a vast array of fossil fuel and so-called renewable energy, I'd rather all my energy was created by light water reactors any day. Nuclear right now means water cooled reactor, uranium oxide solid fuel, poor fuel efficiency, and steam turbine. That's what nuclear power means right now. How do you tell people this isn't your father's nuclear or this is different? It's a much better way to utilize our resources in every way. Molten salt reactors reignited my passion in nuclear because, to me, it solves the waste problem. People look at Fukushima and they go is this the end of nuclear power? I go, no, it's not the end of nuclear power. There's a zillion other ways to do nuclear power. I think this is the best way. Maybe I'm wrong, though. Maybe there's a better way. I've been looking for it. I tell everybody I've got a standing invitation. You can figure out how to do this better, I'd be happy to go to whatever it is that's better. I'm always looking for it. Show me a system that is superior to a molten salt reactor and I'll say yeah, but, to this day, there isn't one. It's not based on nothing that people have spent their careers and many, many successful long term tests. This is not a theoretical technology. This is a proven technology that just needs to be commercialized. It's just by dent of a solid fuel supply chain having gotten started that we don't have molten salt supply chain in place. While molten salt reactors allow previously unattainable levels of passive safety, this does not mean that pressurized water reactors present any greater danger than coal, solar, wind, or natural gas. Despite Three Mile Island, Chernobyl, and Fukushima, existing nuclear power is already the safest form of energy available to mankind. This is because every source of energy has risk associated with it. Molten salt reactors and other modern reactor designs, such as the AP1000, minimized the impact of any error by improving passive safety mechanisms. Any incident at a newly constructed reactor is much less likely to disburse radioactive isotopes, but the key to reducing errors in the first place is having a well-regulated industry. Hey, Barney? Yo? Open 14 and 15. You can't do that, Jack. Open them, Barney. Jack, you can't do it. The book says you can't do it. Screw the book, we're almost up to the steam lines. [pause] It just may be a feed water leak. Which valve? Can't really tell. Shut the isolation valves. You're going to need that feed water later. You want to go down there and do it by hand? Do it. [pause] Barney, give me feed water. Damn it. We'll probably never know the full extent of how badly Soviet nuclear power was managed. I sat before the world in Vienna and blamed those young men at the controls and made no mention of the role I played in their ignorance. I did not speak out. [inaudible 50:41] suicide caused shockwaves throughout the Soviet nuclear industry. Design flaws in the graphite tips of Chernobyl type RBMK reactors were finally admitted to and changes hurriedly made. We do know that Japan's nuclear industry has seen a steady stream of fatalities. This does not happen in France, this does not happen in Germany. [pause] Over a 10 year period, United States nuclear power was responsible for a single fatality. From 2003 to 2012, a uranium miner died when a support beam collapsed. Because every single source of energy has caused at least one fatality during this period and we know how much electricity was generated by each energy source, we can express how safe each form of energy is as a quantity of watts per human life. For nuclear power, because there was only a single fatality, we divide by one. Almost eight million gigawatt hours of electricity per human fatality. The next safest form of electricity is hydroelectric power. Hydro produced about half as much electricity than nuclear, for which six people died during that same period. Next is natural gas. We've all seen natural gas explosions on the news. Somewhere between 26 and 27 people were killed during that same 10-year period. It is a fractional number, because the natural gas was dual used. Only a portion of it was for generating electricity. Now that we're burning fuel, we have air pollution to consider as well. 144 fatalities can be reasonably associated with the pollution caused by burning natural gas over than same 10-year period. Even with the cleanest burning fuel, air pollution kills more people than explosions. Natural gas gives us about 52,000 gigawatt hours per human life. The safest renewable is wind, about 21,500 gigawatt hours per life. Wind fatalities are due to maintenance. Just like nuclear power, this could easily go up or down depending on how the industry is regulated in the future, but there are a lot of turbines all requiring regular maintenance, each one producing a moderate amount of electricity. To improve the watts-to-life ratio and try to make it as safe as nuclear power, it is reasonable to expect the cost of wind turbine maintenance to go up, driving up the cost of wind power. 27 people died maintaining wind turbines over that 10-year period. Natural gas comes out ahead of wind because it produced far more electricity. Solar is 2.5 gigawatt-hour per human life. There are a whole lot of rooftop solar panels, and each one only produces a tiny fraction of the energy that a wind turbine does. Of all renewable energies photovoltaic solar power is the least competitive in terms of price, but it also offers the biggest opportunity for improvement if panels can be made more efficient. Such an improvement in panel efficiency would also improve solar safety standing since more watts could be generated for the same amount of maintenance. In the United States from 2003 to 2012 average number of watts generated per fatality is 300-gigawatt hour per human life. How is our average so much lower than any number we've looked at so far? Because of coal. Let's not forget electricity produced by burning coal. Coal mining killed 298 Americans over 10 years. Coal mining fatalities dwarf all other forms of accidental death in the United States. The big numbers are in air pollution. In one decade, burning coal has killed over 130,000 Americans. Largely due to the release of tiny solid particles that we inhale causing the respiratory illness. Burning coal also exposes us to mercury poisoning. This is how America's consumption of electricity kills people, by coal. Every other source of electricity is safer per watt. On the other end of the spectrum, no other source of power has the potential to meet all of our electricity demand with such a small impact on human lives, disruptive ecosystems, and future costs projected from greenhouse gases being pumped into our atmosphere. Nuclear hardware is [inaudible 55:32] from degrading effects of sun, wind, and rain. All safety systems are focused on a small area and handful of highly-trained individuals. Nuclear has the advantage that the amount in energy per atoms is about a million times better than coal or natural gas. You start with this huge advantage, and yet, given the complexity of the plants and the things you have to do, you more than wipe out your [inaudible 56:01] advantage. Today's nuclear plants are terribly expensive, at least the way they're built outside of China. They're pushing the state of the art and they're standardizing the signs and things like that. Nuclear is one of the directions that we should innovate it. Nuclear innovation stopped in the 1970s. We basically have this sub-design thing that was put into shipping port for the first power generator. We basically built 400 of those that are all kind of custom but not many interesting way. The reactors used in the United States had 40, 50 percent up times. They're horrible. They standardize everything they could - pumps, valves, motors. That's how crazily one off these plants. They would get custom nut and bolts for the pressure vessels. Part of that, [inaudible 56:58] Three Mile Island. After Three Mile Island, they realize that training was that good and we're not uniform or process with companies. Forced all the companies and utilities to get together to share their training and procedures. Three Mile Island, what an indictment how poorly managed the industry was back then. Choosing nuclear power does not guarantee safety. It is possible to make an unsafe reactor, to staff it with poorly trained individuals, and it is possible to respond to release of radioactive isotopes by doing nothing at all to protect the public. The only equipment we have to measure it, the control room Geiger counters, and everything 3.6 nitrogen per hour. Well, I thought that is 3.6. The scanner goes up to 3.6, and it's off that scale. It could be 3.6. Yes, it could be 3.6. Exactly. I have no intention of telling Moscow it's worse than it is, OK? If it says it's 3.6, it is 3.6. The other five reactors in the Fukushima Prefecture were built just a few years later, and all the reactors at Fukushima Daini, none of them had significant damage. We figured it out how to prevent that problem sometime around 1971-72. The one thing the Japanese didn't do is go back and fix the early systems because they thought, "You know, we've operated the plants for 40 years. It's not been a problem before." We have three standard examples of what not to do, and decades of safe operational experience from hundreds of nuclear reactors around the globe to learn from as well. What choices can we make today so that nuclear power can even safer? Very few people understand all the options that are available in nuclear energy. It's a complicated subject. It's a subject that is actually quite new. The first chain reaction experiment was December of 1942. My mother was a teenager in 1942. She's still alive and kicking. This is the only part of the energy business that anything close to a Moore's Law capability for improvement. We're still at the very early stages of figuring out best to put that energy inside the atomic nucleus to use. At the time when society had its most optimistic view of science, it had the view that if that was the form it took, then it must be the right form. We still have this view that society can't shape technology, that the form that the technology takes is the form we must accept. What science and technology gives you is a range of possibilities, and those possibilities can take you in any number of directions. I'm Bert Wolfe. I had General Electric's peaceful nuclear power program. General Electric and Westinghouse took the simplest form of nuclear reactor, originally designed for submarines, and redesigned it on a gigantic scale often to power companies at knock-down prices. We would sell one at a time, and each time we sold one, we'd have a celebration. I can recall when we'd have meetings, and someone would come in and said, "We sold the plant to somebody." We'd all stand up and shake hands and go out for lunch and have wine and toast each other. It was a great celebration. We began selling these by the 10s, so it became a real business. The history of nuclear power is a history of political and economic and social decisions being made about a technology. The key decisions weren't made by the technologist. They were done in the business room.