 So now I'd like to ask Dr. Christiane Lajer to continue his presentation, and this will be final, right? Your final presentation on coolants, coolants for fast nutrient systems, which means sodium. About sodium again? No? Yes, but if you want, I have a mega-pire, a lead-bismuth. Okay. If you have some questions, I have some additional questions. Please, please, choose yourself. Okay, Christiane, please go ahead. Okay, so I will go through maybe this more faster, because some points have been a little bit addressed. I will give you, I take this opportunity also to give some information on Astrid. What was Astrid? Because many of you don't know, maybe, what was Astrid, and several times it was, yeah. So here, this is just a simplified scheme. The screen is not shared online. Thank you. Okay, now? Yes, I think it's fine, yeah. At least I see. No, this is a game. Oh my God, this is something. Now it's perfect, is there a presentation mode? It was a presentation mode. Yes, yes, now? No, perfect. It's okay? Yes, please go. Now it's confirmed. So I'm going to speak to give you some elements, because materials is a large topic, so it's not of use to give an overview. So just because to discuss, it's important to have what is a fast reactor. It is a very simplified fast reactor here, because generally it's complex. So you can see here the core, where we have the fuel assemblies and the clad. Here you have the hot plenum above and the cold plenum below. Here you have the intermediate exchanger. Here you have the below the core in yellow, you have what we call the diagrid is a structure when you can install the fuel assemblies in a honeycomb structure. And below you have what we call the stormback, which is an element to stabilize this very important part of the reactor. You have on the right side the pump, the end on the left side the intermediate exchanger, and then you have the energy conversion system here. We can have a steam generator, as I told you, or it's possible also to have a gas system. You can see a picture here of a very sensitive component, which is called the control plug in France, or it is called also above core structure, which is above control system, which is dedicated to monitor the temperature at the outlet of each fuel assembly. You have a sodium in blue and in gray. You have argon and the slab above. Here you have the rotating plugs here in the center, small rotating plug and large rotating plug. And thanks to these two plugs, you have the possibility to reach any position of the core for the handling operations. And around here you have the main components, mainly primary pumps, PP, and IHX, intermediate exchanger. For example here we have one loop, two loops, three loops, and four loops. And here we have a system with four loops, okay? So it's typical from Super Phoenix. Here you have the rotating plugs. This picture of the rotating plugs of Super Phoenix, okay? You can see here in the center of the small rotating plug, this control, this is a place for what we call control plug, okay? Or above core structure. Here you can see this component, which is inserted here in order to measure temperature and of course to provide handling systems, harness, in order to reach any position of the core to extract the fuel assemblies and to transfer them from the primary circuit to the external vessel to decrease the heat, okay? Or also you have the possibility to transfer from the external vessel the fresh fuel to be introduced in the reactor. This is Super Phoenix, okay? With a lot of structures. Just to remember, you remember I give you the surface, 48,000 square meters inside. So it was huge and 3,500 tons of sodium. Here you have the description, wow, diameter is 21 meters. It's huge. Now the reactors are smaller, okay? And you can, you have here the control plug, what I tell you, and we have a mechanism not only for handling operations, transfer machine, okay? It's in green, but you have also in the center a control route also to shut down, to shut down the reactor and so on. But you can see that the geometry is much more complex than the previous drawing, but to explain, it's much better to use the first one, okay? This is a secondary loop, okay? I presented that this morning. And Astrid, okay, just to give you more fresh information because Super Phoenix is a reference, but it starts to be old, has been, we say. And here, so the idea was to have a technological demonstration reactor. It's a step before what we called folk, first of a kind. It means the first main reactor. The idea is to integrate French and international SFR feedback. It's a generation four system. You know maybe the requirements for generation four systems. I think it's not maybe necessary to detail because it's general aspects, but for safety, we say a level at least equivalent to gen three systems in terms of safety, progress on sodium reactor specificities. What are the specificities? Of course, one is the capacity, the possibility to have a sodium fire, how to deal with that. Or sodium water, even if it's more comfortable, according to me. Integrating the Fukushima accident feedback, it means for the decay three more systems, particularly robustness of safety demonstration, durability. So you know all these aspects of gen four. I don't go again in detail, okay? Operability, load factor of 80% or more after first learning years. We accept to say that during the first years, we need some maybe some time to consolidate and to reach reliable strategies. Ultimate waste transmutation, of course, and master investment costs. So it's not maybe so obvious. We know that for many projects, the cost at the end is not the cost. The cost anticipates at the beginning, non-proliferation warranty, of course. Okay. Here you have all the structure of the Astrid project. We were the maximum 600 and more than 600 people working on that. Of course, there was a CA, the center contracting authority, strategic management, Astrid project team. With the support of EDF. But also you can notice here we have GAE, which was an important partner of the project. GAE with Mitsubishi and MFBR. And of course, the R&D to support the development and some engineering activities also. We have EDF. We have European R&D laboratories. We paid for that, Ardeco. We had the support of, for example, Italy. Italy, we have the support of Germany, Karlsruhe from Latvia and so on. So we have CA for R&D, innovation, qualification, codes, specific developments, expertise. The reactor core was designed and by CA. The nuclear island we have Areva, now it's from Atom, again GAE and Mitsubishi, hot cells with SEV, power conversion system is Alstom, civil engineering is Buig, which is a large big company in France, Jacobs for the balance of plant, for the reliability, availability and maintainability of the reactor, Airbus. So it's strange, but we work with airplane companies and we have also some other companies like Toshiba for the pump, electromagnetic pump, as I told you this morning, Kniem, Vellarm for the valves, Rolls-Royce for the e-tech changers and so on, so many companies and I think, and of course from Atom. So a lot of partners, here you have a view on the, on the, Astrid is just to show where they were working, here you have a same, some definition of the implementation of Astrid. We have a site close to the, near the Rhon River, near Phoenix reactor, because the lamp belongs to EDF and so it was easy to build a reactor on this lamp near the Rhon River. Here you have a description of the main options, I think, well I don't go in detail because in fact from where you are, it looks like conventional sodium fast reactors, many sodium fast reactors looks, they are, looks very similar, in fact in more details you have of course differences, but if you look like that it's more or less the same. You have a pull type, okay, pull type reactor, it means, you know what it means, pull type, yeah, yes, in fact, in fact the way the main difference is that you have the primary pumps and primary pumps and any tech changer inside the main vessel, the main advantage of course is to avoid, yeah, all the sodium, all the active sodium is inside the main vessel. So we have a core with low sodium void wars, so it was, there was a special design for the core for that, oxide fuel, preliminary strategy for civil accidents with the internal core catcher, diversified decay removal system, fuel engine system, Rodin, Rodin, you know what is Rodin, this is the wall who separates the hot plenum from the cold plenum and three primary pumps, four intermediate detectors, four secondary circuits, five decay removal circuits and so on. Main technological innovations you can see here you have effectively this core, equipment and dispositions to eliminate large early accidental radioactive release, a lot of equipments, sorry, a lot of equipments for the in-service inspection and of course a Brighton cycle, even just to be, to give all the information, we have effectively the Brighton equipment but also we have a backup solution, what we call robust backup solution with the steam generators, yes, okay. So we have both, one is innovative with maybe a TRL which has to be increased but if you, if we decide to build this reactor maybe and say we need them very quickly, we will probably decide to have a ranking cycle, okay, here this is the reactor site close to, here you have in blue the, the run river and okay, I don't go in detail but the same, sorry, here, yes interesting, you have the material distribution, so you can notice that we have an objective target of 60 years, okay, life duration, we have so-called austenitic steel, 316LN, okay, we have here, so also in some place we have coatings and particularly on the foot of the funeral assemblies, in the past we have what we call stellite and stellite you have a cobalt, so you induce a large dosimetry, so there are some investigation about other, other options for the coating, hard coating in order to avoid, to avoid any, any trouble and, and foreseen events. About on the wall, on the first wall, we have, we have also a double, double wall, one is the main vessel, the second one is the safety, so-called safety vessel, between the two we have nitrogen, but we have the possibility for example to send the robot, okay, to inspect the, the weddings and in case of rupture on the first vessel, we, the second vessel is able to contain the, the sodium after, I would say, enforcing draining, okay, all the components are in austenitic steel, except the steam generator, sorry, where we have 800 alloy, which is in fact, load with nickel to have a good properties and the particularity is well adapted for the, they are generally speaking two different steam generators, two types, one is the straight tube and in this case we prefer generally ferritic steel and if you want to have a helical, we prefer to have this 800 steel, okay, so here you have everywhere what is interesting on this table in blue, you can see the operating conditions very simplified, of course we have the temperature or the range of temperature and we have also the main phenomena you have to face, for example for the steam generator, as I told you this morning we have this oxidation, which is not a key problem, you have also wastage, what is wastage is typically what I explained yesterday, when you have a rupture, rupture of the confinement, an ingress of steam, you create soda and hot soda and we have an impact on the neighboring pipes, we call that wastage. On the main vessel we have also creep, creep fatigue, aging, okay, aging effects. On the, so we have also in some places we see some fatigue which is induced by the stratification, temperature stratification in the reactor, particularly this is a typical phenomena we can have with liquid metal coolant, okay, so this stratification can induce some enlightenment, I would say, another point which is sometimes discussed, another point which is sometimes discussed is at the free level of the sodium in the atmosphere. Please mute your microphones. Yeah, so on the surface of the sodium and near the wall we have, we have what we call a risk of nitricization due to, if there is some nitride nitrogen, you can have some, maybe some embracement, but it is not, it has not been proven at this temperature. A point, important point, yes, you have to notice, you could say that in the upper part we have the temperature of the hot plenum, it means 550. In fact, in these reactors we have a system where a part of the cold sodium circulates around near the main vessel and come back in the cold plenum just in order to protect the vessel and to maintain the vessel, let's say below 400 degrees Celsius. So it means that we are in good conditions in order to limit creep fatigue on this, on this, on this factor. Okay, so, and for the core materials, for the first core and next ones, it was foreseen for the cloudy space and space where IM1, it's in fact 1515 titanium and so we have a certain number of data, okay, on this alloy and we have a mechanical properties database up to 1000 degrees Celsius, which is available, modeling, we have also, we address the welding process and so on. So the resistance, we have assumed an hypothesis 120 DPA for this, for that and for, for the future there is a so-called ODS, oxide dispersed steel. In fact, this is a specific technique to produce these steels, which are maybe more favorable with regard to swelling, for example, the swelling properties and the target was 150 DPA. About the excan material, okay, you know that the pins are inside the hexagonal, hexagonal can. It is a ferrite martensitic steel called EM10, okay, and we have mechanical properties database up to 1900 degrees Celsius and we had the data coming from irradiation. Of course, this is important to have reliable data coming from some irradiations, okay, and we have a code for this part, you know, it is codification. Codification is like, it's a code where you have recommendations for the engineering, for the designers and of course, we have ISME, ISME, for example, but in France and in some other country, we use also OGSME and we have in France RCCMR code with Afsen French Association, which is, which is, which developed this tool. It's used for ITER, for example, it's used by Indians also for LPFBR and we use also and we introduce periodically some recommendations, but for that we need to have a good exchange between the designer expression of needs and how to demonstrate some recommendations because it's not possible to introduce new recommendations for the designers without, without definition and arguments based on, for example, experiments or correct analysis of some feedback and so on and so on. So, and for the core materials, we have a so-called Ramses, we develop Ramses, okay. So what is important is in terms of R&D, you know that there are a lot of activities, maybe less than for every liquid metals because the challenge are less, of course, for sodium. Nevertheless, there is a necessity to have, to have a correct analysis of the feedback and we are lucky because in, for sodium, for sodium fast reactors, in the world there was some reactors and since a long time and so we have the possibility to analyze the data, the some data. For example, for Phoenix, we have some samples having 130,000 hours of operation, for example. Super Phoenix is low, lowest of course because of some components where the operation duration was not so long but in the, I would say in steady state conditions. So we need to, we can analyze, when you analyze the samples, you need also to analyze, but to know exactly what were the environmental conditions. It means temperature, transience sometimes, effect of maybe some operations like cleaning, aging, effect, creep, staking, fatty, blah, blah, blah, irradiation of course sometimes. So we have a knowledge R&D data and but it's necessary to have a robust data. If you want to extrapolate to 60 years, it's necessary to have more data. So this is the reason why we have some tests even now in order to accumulate hours of operation on the samples in order to have more pertinent important information for the future. Okay, so you can see on the left, on the right, sorry, some mechanical tests in hot laboratories for example in Sackling. Damage mode in SFR, you can, of course we are taking care about sheer buckling, buckling under pressure, excessive deformation, creep fatigue, high cycle fatigue. Why? Because we are in a liquid metal system and but we have, as you have seen, we don't mention a lot of aggressivity, I would say, of the liquid metal. It's more a question of temperature and transience of temperature and so on. About the core materials. Okay, yes, for the astrid demonstrator 110 in the range of temperature 480 to 700 degrees Celsius. For future SFRs, maybe we are, our target would be higher in terms of DPA. So what are the main environmental effects of my own materials with liquid metal coolants? Okay, generally, this is general, it's not only for sodium. You have a neutral flux, neutral flux on particularly on fuel cladding, under core structures, temperature, temperature, temperature gradients, temperature cycling also, instabilities and rifts, liquid metal chemistry, local sodium velocities and pressure. Here we have not indicated what we call dbtT, ductile-brital transition temperature. It was a point we addressed, for example, for Megapie project, because when you have phallitic T91 steel, due to the strong irradiation, due to proton and neutrons, of course, we have to deal with this potential phenomena. But it was a way also, thanks to some R&D we perform before Megapie, with the lead business, before in a so-called LISO experiment, we have seen that it was possible to demonstrate that during one year we will have no problems with this issue. The dbtT remains below the operating temperature, so we remain in the ductile domain. So it was an interesting point. About involved phenomena, of course, on structural materials, we have the general corrosion. We discussed that yesterday, very briefly. Deposition, what we say, of activated corrosion products and impact on contamination is more an issue linked to the dosimetry. It's not really an issue for the mechanical behavior of components. Embrittlement can be desquamation. What is desquamation is when you have an oxide on the surface, possibility that you produce some particles, because the oxide is not strongly linked to the substrate. Activation, potential stress corrosion cracking, on coolant, activation, sodium contamination, and so on. And on the gas, contamination. But so we will come back on this point. The context for the astrid, generally, we consider that we have a very satisfactory feedback regarding behavior when in contact with high purity sodium. So if you keep oxygen content below 3 ppm, let's say 3 ppm, we consider that behavior of material is very, very interesting and very attractive. We don't face any difficulty, not significant difficulty, and it is a feedback which is shared with all our partners who have operated sodium facilities. Here you have the same table as previous, but I have indicated in red what is relevant for the sodium. For the neutron flux, it's mainly on fuel cladding. We have to check the behavior of our undercoast structures, even if we know that for example for phoenix or some we maybe in BN600, they didn't face any big difficulty due to that. Sodium chemistry is mainly oxygen and hydrogen involved phenomena on structural materials. We have to deal with the generalized corrosion and mass transfer. I explained already that. It's more a question of contamination, of structure, which is important to know in terms of dosimetry for the, in terms of dosimetry for the, when you have to repair, for example, and so on, the position impact on contamination. Embracement, exclamation is not really an issue. Okay, particularly it's more an issue for heavy liquid metals. Potential stress corrosion cracking is typical problem of sodium in this case because when you have, I will come back on this point later. We discussed already, we give you more information. On the coolant, no specific issue except maybe we have some, we produce some particles of sodium chromite, okay, and some sodium chromite, but generally the size of these particles is rather small. You don't, there is no real risk of plugging with these kind of particles. In the cover gas, not only we have noble gas like Xenon and Krypton, but also we have cesium. I explained this morning and the cesium, we have a volatility, higher volatility from cesium. So, and target objective is 60, 60 years, but a question we have is what about the impact on particles for 60 years. So I think we need to have a deeper analysis of this point about particles because maybe we have some feedback. We are not, we are far from 60 years, even if we have a good evaluation of the production of particles, but it's a point to be, to increase, we need to increase the reliability of our evaluation. Okay, well, you know this figure. Okay, corrosion. I don't come back on that. Here you have, okay, some characteristic. Okay, as you have seen, we have developed a code oscar sodium to study the transfer of radio contamination. Here you can see facilities in SACLEE. Corrosion studies are carried out not in Kavahash, but in SACLEE. And if you want to have more information, you have here a reference, but Jean-Louis Couraud, he's the name of this researcher, has done a lot of activities related to corrosion since this year, but there are some corrosion studies are carried out in the so-called corona facility. In fact, here you can see this is some, I would say some vessels, small vessels in which we have sodium, control of the oxygen and the possibility to have a rotation in order to simulate, to simulate realistic conditions. Sodium water reaction. Okay, you know this slide, just by, there is an impact on materials. Okay, you have here what you have to look here is this. Here you have a picture where you have a, at this, my pointer, you have an impact. Okay, you can see that the pipe has been heated by the reaction. And generally you have a chemical effect, temperature effect, inducing a swelling and of course mechanical effects after. At the beginning you can have no leak and then increase of the leak. There is a phenomenology that can be more or less fast. Risk of corrosion cracking after repair. Stress corrosion cracking is very localized, the corrosion with small amounts of aqueous soda. We have a corrosion process characterized by transgarinar cracks, okay, in austenitic steels. If you look, we have of man, what we call of man diagram. Okay, and we, here you can see on the, on the right side you have always the same of man diagram. Here you have the stress corrosion cracking area for stainless steel. You have to notice that this phenomena occurs at relatively low temperature up to, let's say, up to 200 degrees Celsius. And what is important is to avoid to have in some remote place some sodium hydroxide. Typically when you open a circuit, if you have a moisture, hair and moisture, you have, you can have a production of soda. And after that, when you feel again the, or you heat up the circuit and feel again with sodium, you can create, can locally have cracks and so you can have damages. So for that, so generally the domain is between 120 and 200 degrees Celsius. And when you have between 30 to 80 percent of caustic soda in the area. And there is a strategy to, there is a strategy to avoid that by appropriate procedure, drying the, drying the gas, drying the local before to fill with the sodium. So there is a specific procedure which has been applied successfully on the, particularly on Phoenix reactor. So here you have the recommendation with regard to the stress corrosion cracking, recommendation on design rules and operating procedures. So we have to avoid aqueous hydroxide formation by design and draining options just in order to avoid the possibility to have this sodium hydroxide, aqueous sodium hydroxide. We have a procedure also with, in order to avoid to stay too much, too long time in this range of temperature when you fill the system. The washing procedure when you have to wash your systems, you take care for a sick sodium retention elimination. It can be done during the design of course. You try to avoid some place where you can keep some sodium. And for Phoenix, all removal components dismounted, clean, inspect, repair. And we have a generally satisfactory reuse in the reactor. And also for the feasibility demonstration, we had a very valuable feedback from SFR operation also. So it means that it's a potential problem, serious problem, but we have the tools and the procedures to avoid that. Maybe I think the first day I explained this point. You have here, this is a pipe below the insulating material, thermal insulating material. And we can have a phenomena of corrosion, deep corrosion. We have a collaboration with Japan, with Dr. Tomohiro Furukawa on this topic. We have a common publication, a common paper. And we address this point. But now it's a problem we avoid. And particularly you have seen that we have innovation, we have innovation. And thanks also to a correct leak detection system. Here is just a view on the, here you have the core, okay, here. Above you have the, what we call above core structure, heat exchanger. In this end, here we have the so-called Rodin. So the Rodin separates the hot plenum from the cold plenum. And here you have a list of items which can impact the mechanical behavior of the walls or the structures. And so you can see, for example, one key component is the above core structure. You can have here thermal fatigue because you can imagine at the outlet of the core of each fuel assembly, you have a jet of sodium, okay, that impinge, impact the upper core structure. And so this, this component has to be correctly sized and so on. So we have also some stratification, some stratification, you know what this stratification is, the variation in a short distance of the temperature, a gradient. And if you have fluctuation of the levels, you can induce fatigue. Here you have a, we have codes for that and here you can see a picture where you have the movements of the, movements of the sodium. Of course, we use the mock up with water also for a part of the validation of this tool. And, and, okay, so thermo hydraulic impact on material. Thermo hydraulic studies are relevant for material analysis. We have to justify a thermomechanical criteria for a four year design life for, of course, for the subassemblies in sodium, 60 year design life for most of the primary internals, and below for the large components. We can imagine that, for example, it's possible to change a pump after 20, 30 years. Same for intermediate heat exchanger. We have to take into account the planned transients, like for, like for reactor maintenance, shut down, scram. Same design life goals as above for the, for this taking into account the planned transients. Accidental transients, short-term behavior of the cladding, scans and so on. So there are many issues and a lot of them are, the thermo hydraulic is important factor, environmental factor. Here you can see for the modeling approach in terms of thermo hydraulics, what is new is that you can imagine that only a CFD is very complex, okay? It's impossible and maybe not very useful. We have, we use a system code, you know, a system code which, in fact, we have a description of the circulation and for each area you have, I would say, a model, okay? And if you have perturbation somewhere, you study the propagation of this perturbation in the world system. We have a Qatar code, which is, we have a Qatar version for sodium. We use Qatar also for lead, there was some exchange with the heavy liquid metal community. And we have also locally a CFD, a CFD model, which is our reference. And locally, if it is necessary to have a better description in one place where we think that it could be, it is necessary to have a better description. We have, we can have locally a CFD. So we have a coupling between the system code and the CFD code in order to have a good description of, so you can see, we have a team working on this item in SACLE also. Phenomena of interest, there are many phenomena we are interested in such a complex system. Maybe I am not going to describe in detail, but the phenomena of in the output jet mixing at the core outlet, you can imagine that the outlet of the core, we have a lot of phenomena, recirculation and so on. Because just in front of the outlet, we have the upper core structure. We have also thermal shocks during transients, three level fluctuations, I already spoke about that. Wedding phenomena, okay, you remember what I said about that. With the sodium, it's a, it's a good, general good consequences because we don't, we are not, we don't face really liquid metal embrasurement like with heavy liquid metals and a lot of big corrosion issues. Nevertheless, we have the wedding, when you have a good wedding, we have a good accuracy of measurements, okay. A good for waiting, waiting is good for any service inspection also. Mass transfer, okay, impact on mass transfer, thermal exchange in heat exchanger, in some heat exchangers, it doesn't mean that for example, for the large intermediate heat exchanger where you have a large exchange, thermal exchange surface, we have for super phoenix is what 1200 square meters of surface of exchange for each, about for each intermediate heat exchanger. So if you distribute your radio contamination products, nothing has no impact on the heat transfer, okay. But for a smaller heat exchanger, can be for example, if you accumulate, but generally the fact that the reactor is always operated in a non-isothermal situation, you don't dissolve the products in the sodium and so on. Easy requirements, this is important, this service. I have already discussed about this point. So it's important to characterize the, and sometime to check the good health of some wells, for example, in some particular places, okay, particularly for the example for the under core structures. About the materials issues also on the core catcher, okay. So for example, we investigate the possibility to have a core catcher, a core catcher here below the, below the strong back, below the core, and we have this developments, okay. Here also, so we had some studies in order to study the behavior of Zirconi, for example. We don't want to, we don't want to have, I would say, we don't want to have, for example, the composition of oxygen and to introduce because the core catcher is always in contact with sodium. So we need that during all these years and during 60 years, we have to avoid any release of particles or oxygen, okay. It's not, it's not good to have a source of oxygen. So there was these investigations and at the end, we decided to have, maybe to move more to molybdenum, maybe some core catcher without, without ceramics because what is the behavior of ceramics during a long time of operation? It was not so easy to understand. And I finish my last, my last slide is here. We have, in order to study this environmental effects on materials and particularly the interaction between the coolant with various temperatures, with a concentration, various concentration of oxygen, even if in sodium fast reactor, it's much easier because we work below 3 ppm. It's okay. And so in this case, we have investigations about the environmental conditions and factors that affect materials behavior, relevant for the structure integrity or come of confinement barriers and components. This is one part of the activity of this OECD expert group. We have, in the OECD, we have contributions from many countries, of course, the European countries, but also we have also a contribution from Russia, from China, also they entered and also from, from, from, from, sorry, Korea, Korea and Japan. Yeah. So there is a first topic which is how to address the environmental conditions. And the idea is to address the environmental effects relevant for construction standards. It means that if we need new recommendations, we need to have demonstrations. So the goal of this working group is not only to synthesize the issues we can face, both for sodium and heavy liquid metals. Okay, we work together. But also to importance, it's important to also say what we need in terms of R&D to validate some new recommendations, yes, for at the level of the design. Second part. Yeah, I finished. Coolant and cover gas, coolant and cover gas issues. Here, the focus is placed on issues relevant for radiological impact assessment, operating and handling. It's more to give some recommendations for the operation, not for the design, but for the operation. And the very important point we, we, we have also is the thermohydraulics and particularly for heavy liquid metals because in sodium we have enough feedback, but it was an important point for the heavy liquid metal community. Thank you. Okay. Thank you very much, Christian. Now, last chance to ask questions, questions. Just wait. What is it? Thank you again, Dr. Leje. I have a question about the, I see that you make a lot of material testing and regarding to radiation and thermal stresses, but how about the critical welds in these, in these materials? Because after welding they can change the, the microstructure and in this long-term situation. For the long time. It's, for example, it's a point we have to address. For example, to, when we have a weld, you have what we call that affected temperature zone. Okay. That affected zone. And effectively we have to take care with, in case of, if we want to have a decontamination, for example, after cleaning, maybe the, the, we have to test on some samples the behavior of these zones. So it means that when you think about, okay, the welding, you have also to think about the potential cleaning and decontamination after. Nevertheless, generally they, of course they weld as they, with the best, the process they know. But after that, we have to have a good idea about, about the behavior of the ZAT with, I would say, in contact with some water or acidic bath. Okay. But you mean like, try to project the, the behavior or because there was some, there was some studies, but above all what we are, we are very lucky because also currently we have the strategy to analyze a lot of samples coming from Phoenix reactor. Because Phoenix was operated between 1973 and 209. Okay. Two. Yes, structure testing, there will be mechanical tests. And we have also to establish a relationship between the sample and the life and the operating conditions. So, so there is a deep strategy in order to have a full benefit from these samples from Phoenix. And of course, some specific tests also. So, you mentioned that the ceramic is not being considered for sacrificial material in core catcher, but ESBWR and VBE are there already implementing like Portland cement and bricks of ferric oxide, aluminum oxide. So, is this oxygen problem only for sodium cold fast reactor or there will be problem for these reactors also? I mean, they're already being Excuse me. I have not, well, that's your question. Sacrificial material for the core catcher. Yeah. So, ESBWR and VBE, they have already implemented core catcher with Portland cement and bricks of aluminum oxide and ferric oxide. VBE are also doing the same thing. They are creating the core catcher. So, is this oxygen problem, you just said the problem can be happened. Is this only for the sodium cold reactor or this problem is also happened for those? No, it's, well, first is of course for sodium fast reactor. For lead fast reactor, they don't have to address a contact between between the coolant and the core catcher because in case of civil accident melting, the corium goes on the surface. Probably. Probably. It doesn't mean that the situation is safe because they have not seen, never seen good description of the scenario of movement of the corium and so on. But for example, for sodium fast reactor, what we foresee is there from below the core, there is a transfer transfer pipes in order that the melted the melted the corium is directed towards the sacrificial material and of course between the supporting structure and the core catcher. Effectively, there are the necessity to study very deeply what we call the fuel coolant interaction. Yeah. And because you can have in this kind of scenario, you have to investigate this, this phenomena. This is the reason why in Katarash, we have a project to develop a large facility to study in detail all these phenomenologies we can face both for fast reactors. Sodium, let's say, and also for light water reactors also called we have already a facility called the building experimental building dedicated to civil accidents called the Plinius. But but there is a project called the safety safety in order to develop new new facilities in order to have a better description of the interaction phenomena between the coolant and and the fuel. And for that, also, we have some collaboration discussions with some other partners. Okay, they're in Japan, particularly in India. Also, they have a facility called Sophie. So there are some facilities now, not so many, but for this item, it's clearly a necessity to have deep discussions because it's not so easy to investigate such complex phenomena. This is a case for fast reactors. It is also the case for for light water reactors, where you can have some kind of separation between the oxides and the metal phase, which is on the surface inducing. So what we call focusing effect on the structural material. A layer of metal zone. It's an issue which is deeply investigated, for example, in Kadarache, but not only in Kadarache, of course. So which material is considered for a fast reactor as sacrificial material? But it's not, it was not really a conclusion, but what we, maybe we think about, there is a solution which was investigated in Russia for BN 1200, I think. It's the molybdenum. If I remember well, there is, but to be checked, I think it is that. So there is no, if I understand, there is no ceramic, but we investigate the possibility to have, for example, for example, Zirconia, but how to demonstrate that during 60 years, you have a good stability of this sacrificial material. Because we have to have in mind that it's impossible to, it's impossible to change. You install this system before. We imagine also that we could have a liner on the surface in order to protect below. But it was the reason why, one of the reasons why we said, okay, we need more time to qualify the corcature. Okay, this is clearly a point, important point for these fast reactors. Thank you. Okay, thank you. Christian, interesting question from the chat. From Daouda Saleh, from safety point of view, what is the basic difference between homogeneous as it called, and heterogeneous? The basic difference? Yes, it's, I think, I hope I'm not that expert, but homogeneous is when you mix with, you mix with actinides, minor actinides. It's homogeneous, heterogeneous. I think you have a part with uranium plutonium oxide, but you can have also some, you can have also some specific area where you have more actinides and so on. I think you think. If I hope it's the correct answer, but I think it's... Any other? Before Saleh? Yes, please. Thank you for your presentation. Last day, you said that in a Phoenix reactor, the heat accumulates in some corner of the core, corner of the core. The heat accumulates in a corner assemblies, if you remember correctly. The heat accumulates in the corner assemblies. Corner assemblies? Corner. Near to the wall assemblies. No, no, no. The heat, the super Phoenix, the heated, accumulated, the hot zones near to the corner assemblies. What does it, what do you mean by corner assemblies? Corner assemblies near to the wall. Fuel assemblies in a Phoenix, the heat, the hot zone near to the walls. In the center, yes. Quarters in the center. Power. The most powerful in the center. I think... No, I think... What I said yesterday about some radial variations, I said, baby, but I'm not sure you refer to that. I said that in order to avoid a hot, hot temperature near the main vessel, we have a recirculation of where the VEA, WER system, where you recirculate cold sodium in order to avoid to have a too high temperature on the main vessel. I think I didn't speak about the... You have a picture, very old picture about this. So I... Yesterday? Yeah, about, speak about the Phoenix thermohydrolix briefly. So I checked this, I, if... Okay. So I want to about this, have this optimization about this phenomenon in a Astrid project for a thermohydrolix performance of the new design. Sorry, I have not catch the problem you refer to. I have another question. I discuss about in a brief... Okay, thank you. About the validation of the... We have to finish now, okay? The validation of the CFD. You talk about the validation of CFD and say that you use the water instead of the sodium. Yeah, it's partially validation. It's a partial validation. But for the main circulation, we can use this mockup, which is the scale is maybe one, one, one to four, okay? Scale divided by four. I think I have to check, but... And it's with water, effectively, we can have a good idea of the recirculation and so on, using colors, for example. This is one way. And you have seen that geometry is very similar to the Astrid geometry. There is another way. I visit, for example, in Borsig's, in Obninsk. You have a facility B200, I think the name of this facility, instead to have geometry very similar to the reactor. In fact, you have a circulation and each zone is represented by a volume, okay? And you check the distribution of... You follow the distribution of volumes, okay? And you describe the system with a different approach, I would say, by a systemic approach. And coming back to our facility, of course, we have this mockup with water, but also we need to have, of course, for some specific geometries, it could be useful to have some, maybe some mockups, if the CFD is not enough robust to describe correctly the recirculations and the temperature transients and so on. Because with water, of course, we are not in the same conditions as we have with... By the way, when you model with water, which criteria you use? Reynolds, growth, growth, growth, I don't know. Reynolds, yes. And in detail, yeah, you asked me the similitude rules. I have... I can check and send you a relevant paper on that. Okay, thank you. If my colleague is going to do, this is the name of the expert, we can... Thank you for the great talk. So, we stop now, okay? So, unfortunately, we have to stop now. Thank you very much. Thank you. Thank you for...