 Now, today, our workshop will be continued by Dr. Cristian Lajer. Cristian receives his PhD from Institute of National Polytechnic of the Toulouse many years ago, and he was working in the nuclear engineering technology since 1979 in CIA. And since this year, summer, he retired from CIA, but still working as a consultant and scientific advisor for the CIA in Kaderash. Dr. Lajer will deliver his first presentation lecture on liquid metal coolant for fast nuclear reactors, properties and consequences. Cristian, please. It's not the right one. Okay. Okay. Thank you, Vladimir. So it's my pleasure to be here, and thank you to invite me again for this event. And so I appreciate to see other people here, because the two last years were not so obvious. And, okay. So it will be more technical, okay. You will see focus on sodium, even if I will give some comments on heavy liquid metal sometimes, and if you have questions, of course, I'm ready to answer. So what are the main functions of a coolant? The question is often to discuss how we can select a coolant. A lot of people speak about electronics, about materials and so on, but the key point is the coolant, in fact, because you have the structure of the reactor, the safety assessment and so on is strongly linked to the choice of these coolants. And of course, of its properties. So it's a key point. So the coolant must accomplish the following key tasks. Extract heat from the core, high specific heat and thermal conductivity, ensure good extraction. It's clear that liquid metals are better maybe than gas, gas systems. You need a pressure in gas systems, and it's so less obvious. Transfer heat to an energy conversion system. It can be, of course, to produce electricity like through a steam generator or exchanger plus turbine. You can have two thermodynamical cycles, generally speaking. You can have a Rankine cycle with a steam or Brighton cycle with a gas or something which is mixed, I would say, supercritical CO2, for example. To a system which directly uses the heat. For example, there was a famous example of heavy oil extraction in Canada, in Atabasca. But you can have also thermochemical production of hydrogen thanks to thermochemical cycles or desalination of seawater is also something, but not directly linked. It is more to use the low-level energy, in fact, we have in the reactor. Ensure safety by providing the system with a high degree of thermal inertia. This is a key point also to have time to answer to a transient, for example. And in a fast reactor, a neutron reactor, of course, the current must not slow the neutrons. Really, you need to have a strong energy, very energetic neutrons, activate under flux, producing compounds which create an unacceptable dosimetry, change the behavior of structural materials, interaction with materials is very important, induce unacceptable safety conditions, induce and summon table operating problems and lead to waste which can be processed during operation or dismantling. So here we can see, for example, that, for example, we will see in sodium, sodium is a good and very attractive properties for the, of course, with regard to the neutrons, activate under flux. We will see that it's quite limited, okay, the dosimetry induced by the activation of sodium is limited, maybe compared to heavy liquid metals, and we can have, for example, polonium 210 and so on, change the behavior of structural materials. I would say that sodium is very friendly with the materials, generally speaking, induce and accept table safety conditions, in this case we, we have not a huge problem except the fact that we have to deal with sodium, sodium fires, okay, it's clear. And then summon table operating problems and lead to waste which can be processed during operation or dismantling. We have some feedback, for example, we know, for example, for superphoenix today, we have no more, we have no more sodium in the reactor, and for phoenix, for example, we have a strategy. At the end, we have no more, no more sodium and just only concentration of activity in some specific traps, and after that we can release this effluent in the river, for example. Okay, when you select potential coolants, when you select potential coolants, of course, there is some kind of rule. There was the idea to have a maximum melting point around 330, why? I think the main reason is to accept the lead, okay, is to accept the lead, pure lead, because you will have a melting point of 327 degrees. As you know, it's possible to reduce the melting point of heavy liquid metals by adding bismuth with lead bismuth eutectic, where we have a melting temperature of about 125 degrees Celsius, and of course, you have a lot of other ones. And in France, we have to decide, for example, if we have another intermediate coolant, instead, you know that in sodium fast reactors, we need to have intermediate coolant, okay, mostly up to now for large reactors. For smaller reactors, there are some discussions in order to improve the situation, but we investigate different possibilities, including, and you have, when you select a coolant, for the primary, there are not so many choice, of course, and for the intermediate circuits, we have maybe more possibilities, but you have to take into account the possibility, the occurrence of ingress of this secondary coolant in the primary coolant. And of course, you can have consequences. For example, we investigate the possibility to have lead bismuth in the secondary circuit, but what happens in case of ingress in the primary? You produce polonium 210, so you have alpha contamination and so on. So the benefit is not so high, okay, in this case, even if we have two equivalent pressure, dynamic pressures and both circuits. And, okay, gallium also was investigated because gallium has a very low melting point and very high boiling point, a large domain in the liquid phase, but in terms of corrosion, you need surely, for sure, to have a coating on the circuits, maybe based on vanadium or something like that. So it's not so easy to use gallium and also the amount of gallium is limited. It's generally a byproduct of the aluminum production. Sodium also, it was used as a sodium potassium, we will see, indium, indium, corrosion, lithium, you produce tritium, selenium, complex tin, corrosion, bismuth, I told you, associated with lead and so on. Tallium is a poison, cadmium is a high pollutant, and so on. There are many reasons. At the end, we compare and we decide that we keep sodium, okay? Even if we have a lot of feedback, we wanted to have this overview. Okay, so we decide sodium. Just to recall that sodium, you know that in some countries we speak about sodium, for others they speak about sodium, okay? In Germany, in Russia, sodium. So the name of... In the US also. Ah, sodium, exactly, in the US also. So there is a etymology of, you know, that the name of a sodium comes from the, they come from the Egypt, probably, okay? It's an Arabian word, the Natron, and coming at the very beginning, there is a place where there is a west of Cairo in Egypt, okay? We have a Wadi El Natron, which is the place where there are a lot of sodium carbonate, in fact. It was used for many, many things, and particularly the mummy's preservation, very important thing. And some colors, some antiseptics, so it was used, but not as effectively liquid metal. You don't find in the nature liquid metal. Yes, so introduction to sodium. Okay, sodium is in the Al-Qali metal family. The name comes from Arabic, Al-Qaeda, meaning hashes coming from the sea, and then come back, but you know the properties, and one of the problem, some difficulties we face with sodium is the fact that it's in this column. So as you know, it's not possible to move one element from one column to the other one. So we have to deal with this position, okay? So you have an electron on the external layer, okay? And so you have very high-reducing properties. It can be some kind of drawbacks, but we see also there are some advantages to be here. Okay, production. In Europe, in France, we have mine in Varangeville, in Nancy, in the east part of France. And we have a company producing a large amount of sodium in the Metospecio, which is located in Moutier. This company provides the sodium for Monju, provides the sodium for Pierre Bier in India, for Ben 800 in Russia, and of course for French reactors also, like Rapsody Phoenix and Super Phoenix. So it's a very old factory. It started by hand of the 19th century, okay? So it's in the Alps because the electricity, the cost of electricity was low and it was effectively produced by the water, water dumps. Okay, so you know that sodium is not used only for nuclear and particularly for many other applications because the sodium is largely used in industry, in chemistry, in oil companies, for example, to produce Tiren and so on. And one of the most important applications is, as you know, production of indigo, indigo, the blue color for genes and so on, and the large benefits of sodium come from the indigo production, okay? So here you have, you know that sodium is used for batteries, sodium sulfur batteries, and currently there are some efforts, and particularly through the European project called Solstice, to use the sodium for the batteries to replace lithium. Because lithium, as you know, it's not so, we have less lithium than sodium comparatively. We have a lot of sodium in front of, in the sea, okay? So batteries, and particularly in Japan it was developed for domestic batteries, not for cars and so on, for domestic in order to provide electricity in some buildings. And more experiment, you know, that there are some studies dedicated to, to understand the magnetic field of the Earth, okay? You know that the magnetic field, North Pole, North Pole and South Pole are linked to the movement of the BACMA, and to have a better understanding of this phenomena, facilities, there are some facilities using, using sodium, particularly you have two impellers rotating in opposition phase, and you create a special movement, and you create an electric, magnetic field through what we call dynamo effect. This dynamo was firstly demonstrated for the first time in the Institute of Physics of the University of Latvia in Riga, but there are other facilities, one in Kadarache, for example, in France. In Germany there is a big project, Westin, you have also experiments in, in Russia, in Perm, laboratories, and in Madison, also in US, so many studies, fundamental studies. In metallurgy it's used to pre-fire, also some elements, okay? Solar applications, there are some specific thermo-electrical converters, but you have also now a new trend to use sodium in solar, solar concentration plants, particularly there are some projects in Australia, or in Sweden also, and so on. So it means that sodium has an advantage, and even if it's reactive, we can have a lot of uses. There are also some, just to recall, I recall here that we can have also binary coulombs, okay, like sodium potassium, there was one circuit in EBR-1, which was NAC, and you have also in Scotland, in Scotland, DFR reactor, which was called by sodium potassium alloy, the advantage is that it's liquid at ambient temperature, but sometimes it's not an advantage. For rapsody, I have found some, some records of the discussions we had a few, more than 60 years ago, and NAC was considered, but it was considered better to have the possibility to freeze, in some cases, consensus the sodium, okay? Because you, you, you avoid to have always the liquid, the metal phase. Lead bismuth, okay, you know, it was particularly developed, you know, the story of submarines in, in Soviet Union, but also it was, at the, at the beginning, focused, of course, for ADS, but particularly for the target. For the target called, for example, Megapie, I was lucky because I was, during, involved in this project, and at the end as director of this project, so lead bismuth is also interesting, but there are some drawbacks, okay? Particularly the activation, activation, production of polonium, but not only, lead lithium is for fusion, as you know, to produce tritium in the tritium blankets, and lead magnesium was investigated by Korean, by Korea, but not, not deeply, in fact. But the problem of this is that when you have lithium or magnesium, you know that there is a difference of potential of oxidation, so it means that if you have an air ingress in the systems, you, you have a modification of the composition, okay, and it's, you need to extract oxides and to reintroduce elements in order to keep, to keep the right composition, so it's not so easy in case of air ingress, and when you have handling operations and so on, you know that sometimes you can have, you can have pollution, okay? Sodium properties, we have no specific toxicity, even if we have irritation and local corrosivity, so it means that, of course, we have to take, to take care with that, but we have not specific toxicity like with lead, okay? With lead, you know that we have specific toxicity. We have a very large availability, okay? The, the sodium is everywhere, even in your food, okay? Here you have the values and no problem, the output every year by depends, you have different source, but a large use of sodium, so no problem to use this sodium. Sodium properties, low mating point, okay? 97.8, it means it's rather low, yeah? Some, it's, it's interesting value, we see why after, so we limit the risk of freezing in heated changes compared to some other coolants, particularly for the decayed removal systems. We need to have a rather low melting point. Large range of temperature in liquid phase, okay? Is less than lead, of course. You know that lead is higher. Nevertheless, we consider that before to reach the melting point of the, the boiling point of the lead, you can have issues on the, on the vessel, okay? And so it means that maybe the main point is effectively to, to, to have enough range between the steady state operation on the hot plenum and the boiling point. This is the reason why it's important also to develop some studies on the boiling, on the sodium boiling in order to have a good understanding of the conditions. For that, there was some, the particularly deep discussions about common program with, with IPP in, in Russia. Low density and low viscosity. What is interesting is that to, to note that I going to, and don't go too much in detail, but we have a very similar properties between some sodium and the water. So the consequence we will see is that we can carry out some experimental studies with water. When it is pure hydrodynamic studies, we can have mockups with water. So it's a quite interesting fact for experiments. Here you can see this is a mockup of a street where we have a water circulation and by coloring the water you have a very interesting results about the understanding of the flow, of the flows inside the primary vessel. High sound velocity in sodium. Okay, so it's a very small influence of the temperature on the velocity. So it means that you can have, we will have a lot of technologies and methodologies to inspect the systems with ultrasonic technologies. And so it's quite interesting property also. Very high thermal conductivity, of course, of course, liquid metal. Attractive heat capacity and excellent electrical conductivity. So like other liquid metals, we can use electromagnetic pumps, flow meters and so on. So there is a well demonstrated technology with the sodium, not only with sodium, with lithium also or heavy liquid metals, but with sodium since a very long time. And also leak detection systems. I will come back on this point. A low saturation vapor pressure, which is interesting. They be higher than the lead, but not so significant. So we have no significant deposits of sodium, vapor sodium and condensation on the slab, the upper slab of the reactor. Sodium leak detection, yes, on this point, we have, we have on this topic, we had some studies related to the development of reliable leak detection systems. In the past, we have mostly technology, which is well known and used in many countries. We have a pipe where we have, sorry, I'll come back. Yeah. We have some electrical wires. We are electrically insulated. And in case of leak, you can have a, you establish a contact between the sodium and the pipe and the wire. And if you have, so you have a shortcut. Okay. And so in this case, you can detect the variation of tension. And it's a warning saying that you have a sodium leak. But the sodium, you can have an interaction between the insulating material and you produce some oxides and mixture that can use deep corrosion, deep corrosion. So you need to detect very soon. And so it was not so comfortable for, for the detection, even if we don't face significant problems. But it's, it's important to know this fact. And so we have developed, you know, for a street innovative leak detection systems. It's a multi-layer, multi-layer system where you have sodium. You have here the, you have here the, the pipe and several layers, okay, which favor the transfer of the liquid sodium towards the detection system. And here the detection system is, is not a wire, is really a layer, electrically conductive layer around the, around the pipe. So it was test and we demonstrated the possibility of detection of very small leaks around one centimeter, cubic centimeters per minute within a few minutes, a few tenths of minutes, depending on the conditions. Okay, but it was really very efficient. About, so coming to the materials, we have a very good compatibility with the steels. No significant liquid metal embrightment. You know that is a weak point of the heavy liquid metals, okay. And in the very low corrosion kinetics. Okay, it's clear that we can notice that all the reactors in operation during a long period like Phoenix or BN600, for example, they didn't face high corrosion kinetics. And the consequence, we don't produce too much particles, okay. So it's important also, it's fact. We have a limited mass transfer and consequently very limited effect on heat transfers through heat exchangers. We have effectively deposits on the cold part of the primary circuit, but it's not so much, it's not so much. Very limited amount of particles. In sodium, we have mostly what we call chromite. Okay. And in some circumstances, we have ternary oxides, ion ternary oxides. We can perturbed some measurements, but it's quite limited, very not often event we can face during the operation. A very important property also is that the solubilities, we will come back in more detail. Oxygen and hydrogen in sodium are very low near the melting point. So it means that it's quite easy. We will see that it's quite easy to eliminate oxygen and hydrogen. Hydrogen is coming, we will see, from different sources, but particularly also from the moisture, okay, in the air. So we have very low solubilities. It means that we have a system. By cooling the sodium, we are able to trap the most important amount of impurities. This is not the case, for example, for lithium. For lithium, lithium reacts also with nitrogen, you know. It's not the case with sodium. And also with lead and lead business, we have, it's different. We have low solubilities, but the strategy is more complex for the purification. We can discuss tomorrow at this point. And what is important is here, the lowest the oxygen content is the best, okay. It's not like in heavy liquid metals where we have to work in a narrow range of concentration in order to protect the surface due to the potential liquid metal embritanment and corrosion. You have to maintain a layer of oxide, but you have also to avoid precipitation of lead oxide. Very good wetting. So it's very important property also. Why? Because sodium is a reducing coolant. So it means that if you have oxide, you are able to eliminate the oxide. So you know that the wetting, the property of wetting, you know what is wetting, okay. This is the contact between the, you have structural material here. And if you have a poor wetting, you have something like that, a droplet of sodium. If you have a good wetting, okay, you have, you are more in this situation, okay. And the angle of, the angle of wetting is quite, is null, okay. So in this case, you have a perfect contact. And you can notice that in this case, the contact is very good. And it's very, it's an important property for the inspection, for example. When you have ultrasonic waves, the return of the US, US wave, it's much more efficient in terms of industry here. So thanks to, sorry, thanks to different sensors, you can produce viewing, under sodium viewing. Here you have just an example. It's below. And it was observed, we have superposed the picture and the signal of the in-service inspection by ultrasonic technology. Okay. Here, sodium properties, okay. The sodium, just to recall, your sodium is 23, okay. 11, 11 protons and 12 neutrons. But you can have, you produce by several nuclear reactions. Sodium 24, 15 hours, half-life, 15 hours. So it means it's enough to induce some constraints for the operation. But when you want to repair, after, let's say, three days, you have acceptable dosimetry to have intervention. This sodium 22, it's 2.6 years. So it has to be, particularly, it's not a lot, large contribution for operation. But for decommissioning, you have to take into account. And so often, when you have a lot of files to prepare for the public inquiry for the decommissioning and so on, during this time, the dosimetry decreases strongly. And after that, you have a neon 23 for the duration, it's nothing. Okay. Another point, when you buy the sodium, you have to take care about the composition in terms of impurities. So when we discuss with a company selling the sodium, for example, we have to ask him in the specifications, strict specification in terms of PPM. Okay. So for different reasons, you can see here, we have a necessity to reduce the composition. Of course, the lithium, for example, for tritium, but not only some other for clogging risk of precipitation, particularly the calcium, for example. In terms of corrosion, the sulfur, you can end, for example, potassium. Potassium, the gas-planquette activity, for example, 30 years ago, they asked for less than 300 ppm, okay, in the sodium. Now, we know that metaspatio is able to produce a sodium with much lower content in potassium. Why potassium is a problem? You produce argon 41 in the cover gas. So it's necessary to reduce the content of titanium. Okay. Here, just an illustration of what we have in terms of pollution. It's a summary, I would say. Here, you can see, it's something like a primary vessel, but it can be in other circuits also. You have a free level of sodium here, okay, free level of sodium. And above that, you have argon, okay, inert gas. There were some operations with helium, but it is argon that's been, of course, selected everywhere for different reasons. First, it's a poor conducting gas. So it's an advantage also, because first we limit the convection and also you limit the transfer of heat from the sodium bulk towards the slab above. And we have also, when you introduce metallic elements here, of course, you know that in a metallic element, you have always oxide on the surface. And so you pollute the sodium, even if you take a lot of care. For example, for superphoenix, just the value is important because you know that superphoenix was the largest, the biggest reactor which was built in the past, 1200 megawatts, okay. We had in this reactor in the primary circuit, 3,300 tons of sodium in the primary circuit. And we have a surface, total variables of metallic surface in contact with sodium of 48,000 square meters more or less, okay. So it's not negligible. So even if you have a small pollution multiplied by the surface, it's not, at the end, it's not a negligible pollution, okay. Several tens of kilograms. So, but thanks to the properties of sodium, you have a decomposition of the oxide on the surface because sodium is a reducing element. And you have a transfer in the sodium and the oxygen and hydrogen. Thanks to the low solubility, as I told you, at near the melting point, it's easy, I would say easy to purify and to maintain a high level of quality of the sodium. We operate, all the reactors are more or less operated with the concentration of oxygen lower than 3 ppm, okay. So there are some variations, but generally these reactors are operated with very low, very low oxygen content. Corrosion. Corrosion in sodium, we have here, there was a lot of studies in the sodium, but now most of the studies have been done. And even if there are some new corrosion studies with new new metals, for example, ODS, what we call ODS, there are some less, let's say that we have a well, a good understanding of the corrosion phenomena. Generally it's, we have the corrosion is the homogenous phenomena, what we call generalized corrosion on the surface. This is one of the corrosion. And the main parameters are of course oxygen content, but we have the dissolution in fact, mainly dissolution of elements, chromium, nickel, and nickel, chromium, and ion. But the corrosion with nickel is very low compared to, compared to heavy liquid metals. This is a key point for heavy liquid metals where the nickel dissolution due to the high solubility of nickel in heavy liquid metals. So we release the corrosion products and the main point you have to remember is that in sodium fast reactor, it's not really a problem, an issue with the thickness of the clad, okay, for the fuel, you know that the fuel assemblies are pins with the cladding. It's more a question of contamination transfer, activated corrosion products from the core, which is the hottest part of the reactor, towards the coldest part. You have a transfer and you have deposition. And if you have to have a maintenance operation, a repair or something, you need to clean up the sodium and decontaminate. We will see that later. Okay, solubilities, okay, we already spoke about that. You can see here we have a well-established laws. There are different laws, okay. We discussed these points particularly within the frame of AEA working group in order to produce, to produce handbook on the sodium properties, the physical and chemical properties and also on the correlations. It's just thermal correlation, pressure drop correlations and so on, through a CRP called the NAPRO. And I think that the documents will be issued very soon. So, here you have, for example, our reference in CEA, Whittingham for hydrogen and Northern Solubility Law for oxygen. Cultural principle, we will go in detail tomorrow. This is a system where we circulate the sodium. We promote the, we have to cool the sodium. We have some support, but not only we will see more details and you trap sodium oxide and sodium hydride. So, we have developed some studies in, yes, some studies where we have established the kinetics for both oxygen and hydrogen separated modeling and thanks to the good knowledge of the properties of the kinetics, we have developed new systems for sodium cooled, so for sodium cooled fast reactors. I will detail that tomorrow, okay. Activated corrosion products in sodium. So, as I told you, we have a transfer from the hot part in the core towards the coldest part. So, we have developed tools to simulate the transfer, the mass transfer of activated corrosion products. And we are not alone. We are, there are efforts down in, in several countries and particularly, for example, in Japan with the sidekick code. And we have also developments in, in India with the Solpreg with, in Russia also. And so, there are different codes and the idea also to do some benchmarking activities in order to compare because the basis, scientific basis are sometimes different. Okay. For example, Russian colleagues focus more on the particulates. And, but okay. So, we have developed in France a code called Oscar, Oscar sodium, because we have different versions of this code, not only for liquid metal systems, but also for fusion, for trisium blankets, for pressurized water reactors. So, in fact, we adapt, of course, with the kinetics and so on. It's adapted for many applications. Here you can see, here we did some measurements, just interest in sodium is that, as you know, we have a lot of operational feedback in several countries. And we use the data we obtained on the intermediate exchanger. There is an exchanger between the primary circuit and the intermediate circuit. And we, this exchanger, so it's a sodium, sodium exchanger. And it's clear that we have a distribution, we have measured by what we call gamma scanning. Okay. Measurement of gamma along the system. We have the possibility to establish the distribution of radionuclide on the surface. And we had the very accurate measurements. And we, okay, so we have modeling of these measurements. And we did the calculations with our code Oscar, Oscar sodium. And we have found that we had a good, we have a very good modeling of this phenomena. Okay. So our code is now used to establish some predictions of distribution of radio elements on these cold surfaces. You have, if you want, sometimes I indicate some references for, if you want to go in more details. Okay. So particularly for free main radiocontaminants, one of them is a manganese 54. And the second one is a cobalt 60. And also, in a less extent, cobalt 58. So what we did here, you have a profile of contamination before cleaning. What we call cleaning, we will see later. We have to, okay, to eliminate the layer of sodium on the surface. And it's easy, I would say, thanks to reactivity of sodium with the steam. Okay. So cleaning, cleaning surfaces for maintenance, cleaning the surface for component of sodium fast reactor, it's easy and well mastered. Okay. Because of the reactivity of the sodium, we come back on this point after cleaning and after the contamination. For the contamination, we generally use, we will see that, I think, just after we will see, we use acidic bath to clean up the residual deposits of activated corrosion products. It's generally sulfuric acid, of course, mixed. We will see that tomorrow when we will speak about materials. But it's sulfuric acid, diluted sulfuric acid. Sodium property is very large reactivity with water. Okay. And so, as you know, we have an interaction in steam generator units. It's very important because you can inject water in the sodium. We will come back on this point. This is clearly a point we have to avoid or to detect as soon as possible. We will discuss this point later. But for cleaning pits, okay, as I told you, cleaning when you want to clean up a component, it's easy, I would say. It's easy and it's well mastered. But we have an important chemical reactivity with air which can induce sodium fire. Okay. It's clear. It's an event we have to face, a potential event we have to face. And this event can be avoided by inertization generally or by extinguishing locally, automatically, or with fire brigade here, extinguishing a sodium fire. A peculiarity why the five men is close to the fire is because it's not like hydrocarbon fire. You don't have, you have not vapors and heating in all the room. In our sodium school, in Katarash, we have a sodium school, okay, where we train not only the operators, but also the researchers. And we enter in a room where we have a sodium fire with, of course, with the gloves, glasses, and so on and all the protections. But everybody is surprised by the fact that to surprise, first the effect of fire results because you lose your repairs, but you can be close to the fire also without a specific risk. So we use the powder which can be used for extinguishing is a sodium plus lithium carbonate, a sodium carbonate, lithium carbonate and graphite. Graphite is for the fluidization to give more fluidity to the powder. And it's well mastered technology. About saturation vapor pressure, okay? We have a few limited amount of aerosol, so it's a very important point. So as I told you, we have a very low flames in case of ignition. We, temperature is above, let's say, 140 degrees Celsius. This is the reason why the producer of sodium is able to drain the sodium, liquid sodium at in air, okay, in air at low temperature to prepare the ingots, okay? So you don't have immediately a fire, except if you have, if the sodium is spread in small droplets, because you have a lot of active interaction between the droplets and the, and the air, okay? And oxygen in the air, okay? Consequences are very few aerosols. It's not possible to eliminate a sodium layer by, I would say, distillation in the vacuum. You have not enough power to extract the sodium. It's not like with water. It's quite different, okay? So we have a lot of studies dedicated to sodium fire, because we agree that it is a weak point of sodium. So here you have sodium in powder, temperature around 140, dispersed sodium. And sodium fires, okay? You have here a description of the main reaction. You produce sodium oxide and sodium peroxide, okay? This is just similar to the previous slide, okay? For the water, for the water, sodium plus water produce sodium peroxide, hydrogen, and heat, okay? But we have a different circumstances to have a sodium-water reaction. Sometimes we don't want to have this sodium interaction. It's particularly the case for the sodium-water, sodium-water interaction in steam generators. And, but sometimes for the, to the destruction of sodium, for the destruction of sodium, we, we use a process, we have developed NOAA, NOAA process. It looks like an average, okay? But you have also here four, four examples. One is a cleaning pit, I told you. You can introduce in a cleaning pit a component and with a steam or spray, we clean up our, in safe conditions, our, our components. You have the steam generator here. You can see here on this in the middle. You can see three steps. If you have a pipe with the steam inside, you inject in the sodium. You have, of course, production of heat and soda. And so you can impinge the neighboring pipe. And so you can have a propagation of sodium water in a, in a bundle, in the steam generator, a bundle of pipes. And so it's clearly an event we want to avoid. This event, this event occurred in the, in the PFR reactor in Scotland, okay? So it's not just only a prediction. It happened, okay? So we want to avoid that. And for that, we detect, as soon as possible, the interaction between sodium, between the sodium and the water, thanks to the production of hydrogen, which is dissolved in the sodium. And we have specific instrumentation to detect a very small variation of oxygen content. It's, okay. And the last is the NOAA process. So we use this process. We inject sodium in the water, okay? We destroy 2.5 tons per day about, okay? And we apply that for Rhapsody, Superphoenix, PFR in the UK. So it's a process well demonstrated and very efficient. So it means that you can have a large destruction of sodium by direct interaction between sodium and water without any consequences and safety. You can sleep close to the, you can sleep close to the machine without noise, okay? The main reason is that the fact that in steady state operation, you don't inject sodium inside the water except during the first, the first period where you reach the steady state value in terms of composition. So you inject sodium. You have a pump, a pump, specific pump. Dispersion of sodium here inside the water. Just in front of, we have injection of water mixing and fast dispersion of sodium and extraction of sodium hydroxide here. Injection of water here because we have to respect the mass balance, overall mass balance. Extraction of the gas, particularly hydrogen condensing and measuring trisium and so on and so on. And, okay, after 2 slides and I've finished for this first part. For the dismantling, we have demonstrated that it's possible to dismantle a fast reactor cooled by sodium, okay? Clearly, particularly as I told you on Super Phoenix, now there is no more sodium anywhere, okay? Everything has been processed and it's just conventional dismantling of structural material. So what are the main process for decommissioning is that we have, as I told you, the sodium process destroyed a huge amount of sodium we can have in the primary and secondary systems. But we have also, we use the cleaning pits to clean up the structural material. We have also, we develop also sometimes we have a sodium potassium in some parts of the reactor. We have a way to process that. And we have, with the residual amount of sodium, we have the possibility to carbonate. So we convert sodium into carbonate in order to be able to cut after that the structures in order to avoid any release of liquid metal, which liquid sodium, which could be heated by the mechanical stresses on the liquid metal. So typically, for example, this is a shadow we follow for the Super Phoenix. You have to know that we started to destroy, I would say, the sodium around 2010 in less than eight years, okay? Less than 10 years. All the sodium was eliminated in Super Phoenix. And another process we have developed for the decommissioning, which is linked again to the water, thanks to the reactivity of sodium with water. We have developed Hela process. This is the process where we have the possibility to cut the coal trap. For example, a system, which is, for example, for the purification, at the end, you have these systems to process. And we have developed this system, and okay, we have modeled the different operations. And one question, for example, was to know the distribution of tritium, because in these systems, we have a tritium, also a small amount of tritium. It's not like in the fusion, okay, clearly. Just for information for Super Phoenix, estimation of the tritium source was two grams of tritium per year, okay? But it's enough to have to take into account in terms of environmental consequences, okay? So we have to trap this tritium. And for that, we made some studies modeling of this Hela process where you have the residual sodium. You have a layer of sodium hydroxide, and then you drop the sodium hydroxide and we studied the different exchange between hydrogen, tritiated hydrogen, water, and so on, in order to have a good view of the distribution of tritium in all the systems. Okay, sorry. Okay, this is the result of the phenomenology. You can stop here. Next will be tomorrow. Yeah, maybe I finish with this one, sorry, an additional one to finish with sodium-water interaction. So here you have the equation of where we have the, okay, sodium-water interaction. The problem is, effectively, we have, when we have a sodium-fast reactor equipped with a Rankine cycle, it means with steam generators, we have to, okay, here you can see the reactor itself, the intermediate circuit, and here the energy, what we call energy conversion system. Here you have the steam generator here, and when you have this injection of steam inside the sodium, okay, we have, you have an, you can have an evolution of the leak, okay, from a small leak to a micro leak, small leak and evolution, okay. So, effectively, we have to address this point. So you have a lot of models in order to describe the interaction, particularly when you have injection of steam in sodium bulk, and you, we have what we call, we study and we model the impact on the neighboring pipe. This phenomenon is called wastage, okay, and we, we model that in order to develop strategies and consequence on the detection times, mitigation of this event by draining the sodium and water, water first and sodium after, and so on, to, to have a protection of the investment, okay. You don't want to lose the steam generator, particularly if you have, if you have modular steam generators, like in some countries, like in India or Russia, for example, but in Super Phoenix and Astrid, we have, we did the choice to have only one single steam generator for each loop, intermediate loop. So it's clear that it is important to have a good understanding of this phenomenon. Yeah, I will come back on this point later. I stop here. Thank you very much. Thank you very much. Dr. Lajer, we have time only for one question, which I will ask him. And, but you have time during the line, please ask, please send the questions. Okay. Can you apply this technology for, for elimination of sodium potassium alloy, which is another in the breath of the BN315 Kazakhstan, which is still under decommissioning in some of the secondary circuits, they have sodium potassium alloy remaining. Could you apply or what is the features for, if you? Sodium potassium? Yeah, if you do it for the sodium potassium. We can use, we can use NOAA process. NOAA process is, is possible to, to use this process, continuous process to convert sodium potassium alloy into a mixture of sodium and potassium hydroxide. Yeah. Very quick. Question and quick answer, please. Yeah, thank you very much. So I want to come back with your forward talking about how you manage the waste, because you said that the waste didn't contain sodium, just some activities, specific activities. And you dispense the waste in arrival. So did you prevent, because did you prevent some environmental contamination? And how did you manage it? I will, I will speak about that tomorrow afternoon. But yes, we have the possibility to eliminate, for example, a cesium. You will see that there is a continuous process to trap the cesium in the sodium using a carbon, carbon traps by adsorption. So it's a very efficient process that was developed a long time ago. It was used in several countries, like, like the USA, EBR2 and so on. We used also for absodium. We will use again for Phoenix. So it works. It works very well for cesium. For activated corrosion products, it's possible also to eliminate that. But honestly, the amount is very limited and most of it is trapped in the structures. And after that, by cleaning, we have a residual amount of, in the liquid effluent waste. We have this content, but we are able to reduce the contamination in the liquid effluent. And so at the end, we produce sodium dioxide. It is naturalized into water with salt and released. So it's a strategy. There are different strategies also. We have a possibility also to reuse this sodium dioxide. It was investigated. It was possible to use this sodium dioxide in the repossessing plant. You know that in the repossessing plant, they use a lot of acidic bath and they need sodium dioxide. So we have seen that it was possible to do that. But for political reasons, it was done to transport this hydroxide to the ag repossessing plant. And the last option also is to produce concrete. So it's a very, very low activity concrete. But there are many options. Okay. So the next lecture.