 z Prof. Wajdža, z vsej sej. Najbolj spet, kaj sem zelo zelo v franči sodiom polonji. Zelo zelo. Počkaj, Vista. Počkaj, Vladimir. Zelo zelo zelo zelo zelo zelo zelo. Zadam z vseh vodnih aktivitaj vzglom način, ki je pripravljen srednih. Vzglom so do zelj in všeč po nekaj tomo topike. Vjezglom z Fuzion, da sem pravite in za HDR projekte, in za ADS projekte. I do zelj, do zelj, po nekaj, in čutvo vseč sem način vzglom vzglom, for INSTN in CE, but also I am advisor for Astrid project and involved in international collaborations. So now the topic is to, I will address, yesterday you had the opportunity with Konstantin and extensive overview on the reactors, various types of reactors and focused on many aspects today. This morning, in the first part, I am going to, I would say, to have a review of the coolants, particularly coolants, because often people are speaking about the systems, the safety, the materials, but we know that there is a fluid, which is absolutely necessary to transfer the heat, particularly from the core to the energy conversion system. Energy conversion system is the system where we produce electricity or heat, or different options, even if now the main application is production of electricity, of course. So what we can say also is that the coolant, you will see that the choice of the coolant has a strong influence also on the systems, on the design of the systems, on the safety also, and it's clear that the coolant has to be properly, has to be selected. Of course, even if, as you know, there are some main parameters that drive your choice, of course, but nevertheless, I am going to express some kind of questions we can have in order to choose the coolant. And when you say, choosing the coolant, also you choose the reactor system. OK, so pardon me, I will effectively address more particularly the sodium-fast reactor, even if from time to time, I will speak about lead and some other coolants, of course. And for the next presentation, I will address also in some aspects how to maintain the quality of the coolant, because if you lose the coolant, after that in terms of composition, in terms of radiocontamination, you have, of course, some consequences on the operation, and also on the maintenance, on the in-service inspection, and some other aspects like that, because the reactor is not only designed, but also it's always and often, and we hope that for the future operation also. OK, so here it's just to recall the, it's just to recall the, oh, sorry, I'm looking, where is the laser? It's on the top. Ah, yes, OK. Yes, here is just to, OK, here you have the, I recall you, the pull concept of reactor, as it was said yesterday, we have two main concepts, what we call pull concept, where the main characteristic is, of course, to have the core, the core and production of it, but also you have also in the pull two main components. One is the primary pump to circulate the sodium and you have the intermediate heat exchanger. In a sodium reactor you have an intermediate circuit, as it was said so yesterday, for lead fast reactor, in principle you don't need, you don't need an intermediate circuit even if you need a double wall steam generator. In order to prevent, I would say physical phenomena when you have a water coolant interaction. About the, about the, so you have the, here we have the core, below that we have a system that is able to distribute the sodium, we call that diagrid, and here you have under structures called strong back and you push the, thanks to the primary pump we have generally always a mechanical pump in this primary system. You have a circulation of sodium, you pump sodium here and thanks to the shaft and the impeller we can reach the sodium with some dynamic pressure below the core in order to distribute properly the sodium. Inside the fuel elements and also between the fuel elements also. And then the hot sodium, generally we enter here 400 degrees Celsius or below, slightly below and then here often we are above 500 degrees Celsius. We can reach 550 generally maximum even if there are some studies currently in Russia for example to study the possibility to have some pressure in the sodium circuit and to be able to have a liquid sodium up to at the outlet up to 600 degrees Celsius. This is investigation. There are some investigation. But of course 550 was selected because we know that below these values we have no specific issues they are well mastered and the operational feedback from the previous reactor is reserve positive. Then the sodium, hot sodium is sent here in the intermediate heat exchanger and the cold sodium come back in the so called cold plenum here. Of course for that we need a separation between the hot sodium and the cold sodium. We also called hot plenum and cold plenum and we have a separation here. The name of that is we call that inner shell. We use also another term which is French, Rodin. We have this circulation. We have a free level of sodium here and above that we are operating here at almost atmospheric pressure and we have above that argon which is the cover gas argon I answered yesterday to one question or comment argon was selected because it is slightly over the density over the hair and secondly it is because we have it has a poor conductivity so it means that the transfer of heat between the sodium bulk and the slab is rather limited. Here you have a picture of a primary pump and generally the primary pumps are tested in water. Why? Because the sodium, maybe you know the density of sodium and the viscosity of sodium are close to the properties of water so it means that a lot of studies only dedicated to thermodynamics can be performed with water. You have here the intermediate exchanger and here you have the energy conversion system so generally it is based on a Rankine cycle a thermodynamic cycle with a change of phase with water, liquid water in the bottom and gas steam but for a street project also we investigate also the possibility to install a Brighton cycle using another coolant, pure nitrogen. I will come back on this point later speaking about the coolant but the main reason for that is the main the main objective was to avoid the potential sodium water reaction. So if you have no more water no hazard related to the sodium water reaction. Nevertheless we have for example for a street even for a street we have what we call a robust backup solution using Rankine cycle. Why? Because even if the sodium water issue is often underlined I would say that the operational feedback of the reactors show that it is possible to master and we know that there are some solutions to reduce the hazards induced by a sodium water reaction by different solutions. I will come back on this point later. Here you have so called the control plug or called also above core structure. This system is very important because here you can see the thermocouples which are able to control the temperature and the outlet of each fuel assembly. Here so we control the temperatures. You have these thermocouples. On this it is fixed on the slab and you have also some devices for the handling operations yesterday you have seen that on the slide of Konstantin. You have systems to extract the irradiated fuel assemblies and also to change the position of these fuel assemblies thanks to transfer harms and two systems in fact but you are able to move these fuel assemblies of course to manage. Yes It's all for what I want to present now about so we have to consider the three coolants. One coolant is the coolant of the primary pool. Of course here the choice we will see that the choice is I would say more or less decided before they are not really we have a comparison during some time but after when you have a choice after that this is okay you don't come back on this option so we will use some information about that after that of course you can have a different there was some investigations I will address this point also about potential other coolants for the intermediate loops particularly when I said that we want to avoid sodium water reaction we can also say okay if we can keep the water but we can investigate also the possibility to introduce in foresee for example another coolant like molten salt like lead business like sodium hydroxide and potassium hydroxide mixture and so on so we did an exercise on that in order to investigate these possibilities we were not alone to do that because there was some other teams working in this field there was some projects particularly in the lead business for example why because the melting point of the sodium is 98 and the melting point of the lead business is 125 24-25 so it means that it was not possible for example to foresee a lead why? because we have a big advantage of sodium here is that the melting point is 98 because if we want to load fuel assemblies if we have a campaign for removing the fuel assemblies or for any specific handling changing a pump changing removing it removing intermediate heat exchanger we have a so-called called shutdown temperature for example in superfinex 380 so it means that in this case you can operate the reactor at low temperature for example it's very interesting for in-service inspection operations which is easy more easy than to perform these operations at temperature above let's say 380 for example which is the current called shutdown temperature for lead fast reactor because the melting temperature for the lead is 325 200 degrees above the lead business so here you have a view from the top you can see from the top here you have the core and above that you have the the upper core structure I don't detail here but in fact this the above core structure is in fact fixed on two rotating two rotating plugs which allows you to reach any position of the core in order to with the handling system to extract to extract and remove any fuel assembly or control system and so on ok just to say here about steam generators for example you can have a so-called monolithic steam generator as it means a huge steam generator which is able to for one intermediate loop here we have I have shown you a system with two intermediate loops we can have three intermediate loops or four for example like in Super Phoenix here is just an example illustrative ok with only two it's just to indicate that we can have a large monolithic steam generator or here you have another option which is particularly used in Russia or in India for example with modular steam generator we can have also as I told you a gas heat exchanger in case of if you select a Brighton cycle ok so some about the about for nuclear systems of course you know sodium ok it has been extensively used and we come back on that the lead it can be used for fast neutral reactors or subcritical reactors like ADS we have some discussions about Mira system for example but the lead can be used even if the lead business is also can be used as a coolant for the primary system at the same time can be used for the ADS target you know that in a subcritical system we need to I would say to add some neutrons in order to reach the criticality and for that we need to have a specific component called the separation target where accelerated protons impact the heavy liquid metal and produce additional neutrons and these neutrons fast neutrons are able to transmute waste ok minor actinides installed all around the target ok so lead business so has been extensively studied there is operational feedback in the from the Russian submarines the gas the gas is his option for very high temperature thermal reactors as it was said helium sometimes helium nitrogen mixture has been investigated also and supercritical CO2 for innovative energy conversion systems come back on this point because we have a specific properties when you have a supercritical fluid in terms of performance for exchange and so this option is studied in several countries in order for the future not for the short term I would say but for investigation for the long term about the mercury mercury is used for spalation targets also for example for in S in Oak Ridge or in G Park in Japan in Tokai so you have mercury which is used the interest of course of mercury is to be liquid at ambient temperature molten salt ok for molten salt reactors can be used also for alternative coolants for the secondary loops I will discuss about this point water steam also in some concepts and of course in generally in the energy conversion system based on ranking cycle infusion of course you know that the lead lithium you tactic for blankets is used for blankets what is interesting is the lead and the lithium lead to multiply the denotranspatter so the lithium of course to produce the tritium to produce the tritium and it can be can be used lithium can be used as a coolant also for in support to the fusion for the IFMIF project this project is connected to the ITER project this is the facility to study the behavioural materials by production of the tons and the lithium the lithium has been also used for fast reactors but for special special application there was some studies why because one of the main characteristic of the lithium is the density you know that the density is 0.5 so it means it is very interesting when you have to launch a rocket the weight the weight is important parameter but honestly here the main duties is of course coolant but also the main objective is to produce lithium you know that there is some alternative solution you can use powders of lithium silicates for example and so on to produce tritium and the lead business also has the function to produce neutrons here ok about the story I don't go into much detail what you have to know is that the very beginning the first one was Clementine the coolant was Mercury ok then sodium potassium and then enough quickly sodium sodium and sodium potassium sometimes sodium for the primary and sodium potassium for the secondary in in Great Britain in the DFR we have the sodium potassium also in the first reactor then in PFR they moved to the sodium and after that most all the projects were done with sodium for absolutely I found some discussions before to start the project discussing about what was the best between sodium and sodium potassium they select sodium the main reason why at the beginning some people says ok sodium potassium you know it's a eutectic which is liquid at ambient temperature so it can be an advantage but some people says in terms of sodium safety sometimes it's good also to have the possibility to freeze to freeze the sodium so there was the main argument to keep the sodium in fact after that we have so the reactor the following reactors Jojo Jojo which is a sodium Kajnkatu in Germany and so on and so on sodium all these reactors are considered in operation with a red arrow ok bar 60 I think it started in 1967 and now we have ok in operation also we have considered in jojo even if it has been stopped but repaired and BN600 also is in operation since 1980 FBTR in India EFR in China even if it is not in operation since 5 years for some specific reasons to restart the reactor BN900 was in operation since start 2015 but really in operation spring of 2016 and PFBR reactor which is not a project it is really they are in a commissioning phase ok so they have already filled a part of the reactor with sodium and they are currently waiting for some authorization to go on the operations maybe Jekar will give more information about that so in the beginning it was interesting that there was some application for submarine and sometimes for planes I have heard that one of the first molten salt reactor was for the plane so it is strange now we have difficulties to imagine a plane with a nuclear engine but the unknown process is the lead business called fast reactor which gave a lot of information particularly for the chemistry monitoring they face some difficulties with the chemistry and the chemistry as you know of the lead business is not so easy to master so it is can be tricky and so it is necessary to implement some specific systems oxygen control systems ok then so the course what are the duties of the coolant the duties of the coolant I go quickly through this different thing first is to extract the heat from the core so high specific heat and thermal conductivity ensure good extraction so it is in favor of metallic I would say metallic coolant particularly for the thermal conductivity even if specific heat the specific heat of sodium is slightly lower than the specific heat of water for example just for information the transfer heat to energy conversion system so it is important steam generator or coolant gas exchanger plus turbine to produce electricity to a system which directly use the heat there was some application particularly for gas temperature reactors some projects to produce heat to extract the oil for example in Canada in Alberta in Atabaska area and also some projects also to produce hydrogen by thermochemical cycles particularly iodine sulfur system has been extensively used the idea is through a chemical process to split in fact the water molecule into hydrogen and oxygen the interest is of course hydrogen for oxygen no problem also it is no problem to release oxygen in our atmosphere about sea water desalination there was some application we used generally what we call the residual power the low temperature fluids in order to help to support the distillation particularly the distillation of the sea water evaporation you promote evaporation and condensation in order to produce distillate the water by multi flash or multi effect process you can connect that also to the hot reverse osmosis process so it was used for example in the it was connected on the reactor BN 350 in former soviet union now in Kazakhstan in the city of Aktao Shevchenko so another point is ensure safety by providing the system with a degree of thermal high degree of thermal inertia so it means that condensed coolants are more favored for this aspect compared to gas of course we need to maintain a pressure in order to have enough efficiency enough thermal inertia the coolant must not significantly slow neutrons we are in fast neutrons we need to have a coolant without with a limited activation for example sodium as excellent has an excellent behavior we produce isotope of sodium is sodium 23 the natural isotope we produce sodium 24 the dedicate is 15 hours so it means that has to be taken into account when we stop the reactor shutdown for example prayer repair but it's not really a big issue and we have also sodium 22 sodium 22 the period decay is 2.6 years so it means that we have to take into account that for the decommissioning nevertheless it's not a big issue maybe I have not discussed this point but if you ask me some questions about decommissioning after that I can tell you because on this reactor which was operated of course we had to perform decommissioning operations about the important point is to limit the mechanical property the change of the mechanical properties of structural materials it's clear that the coolant the choice of the coolant we have to have friendly behavior with materials this is typically the case with sodium we have seen that other reactors some of them you have seen are operated in the long time we have an excellent I would say an excellent yes behavior of of materials with sodium we have some corrosion we don't come back on this point tomorrow but this is a rather limited we have no liquid metal embrightment with sodium which is important property also so generally we have not real issue this is also for another reason maybe I don't describe in more detail the structure but we maintain sorry I come back before yes here I have to mention that here in fact some details are missing we have some kind of recirculation of the cold sodium along the vessel in order to here we have a system which allows in fact the hot sodium is not in contact with the upper part of the inner vessel in fact we have a recirculation here along the wall of the cold sodium in order to maintain I would say the main vessel is located below 400 degree Celsius so we have not difficulties we got to creep for example we don't have any we are working at the lower temperature than 550 here so there are some design approaches that allow to keep the main vessel at the lower temperature so important point induce and acceptable safety conditions and some other operating issues so it's important also to mention that we have to master all the situations this is particularly the case for sodium because as I use sodium as I would say a lot of good properties nevertheless some important drawback as you know we will see that later as Alkaline so he is a strong reducer so he is reactive with oxygen and water we have to master these two potential interactions and last point he asked not to lead to waste which can be processed during operation and dismantling also it's important to avoid any production of secondary waste during operation so properties melting temperature important one sodium 98 so as I told you we can operate at low temperature for loading and unloading fuel assemblies boiling point and liquid phase temperature range this is important and impact on the safety so there are some discussions about boiling temperature which is 880 for the sodium round and for lead is higher in practice it seems that there is an advantage for the lead on this point thermal stability no problem with the liquid metal for gas but for molten salts can be an issue because you know a molten salt there is not properly speaking a boiling phenomena but you start to have thermal decomposition we see that for example for the molten salts which are used for the solar applications thermal properties of course these are important parameters density density is an important point for example with regard to seismic resistance for the sloshing phenomena sloshing phenomena means that when you have a quake you have some waves and so you have an impact on the vessel interactions with structural materials I discussed this point so the solubility of metal elements environment and also what we call potential mass transfer it means that you can have a corrosion in the hot part of the reactor in the core production of activated corrosion products and transfer in the coldest part of the reactor particularly for example deposition in the intermediate heat exchanger there is this kind of transfer and so it's important to master that and to have a limited phenomena reactivity with surrounding fluids air, water so as I told you this is an important point for sodium water also for all the liquid metals for physical phenomena organic products sometimes and you can have oil circuits sometimes so you take care about you avoid some options the interaction with organic can produce gas, ethylene hydrogen and so on methane opacity this is an important point so it's a clear advantage for gas this was the main reason for to investigate the gas also for fast reactors one of the main reasons why because you know that in the history of fast reactors we can come back during further discussions but we have seen that each time we have to stop to stop reactor or to control some ways to have an intervention when you have a liquid metal it's the opacity needs to develop new technologies for example we are using a lot of ultrasonic ultrasonic technologies in order to be able for example to have sodium under viewing of the of the structure immersed in sodium to check the position by so called telemetry you can have also viewing you can have a view like with a camera and we can also detect small cracks sometimes on the welds so there are a lot of efforts done in this field in order to guarantee that we are able to operate the reactor in safe conditions next vapor pressure low it's important also this is low which indicates the transfer of pressure the transfer of vapor towards the coldest part of the reactor the slab possibility of interaction with the neighboring coolant ability to be purified emit again quality standards we will come back on this point this is important in case of pollution because our system of course we have confinement but we need sometimes to open in some aspects the reactor the toxicity which is important to address ability to be processed during dismantling you have to demonstrate that when you build a new facility you are able also later to dismantle production of waste the coolant availability I will come back on this point but first also can be an important point for the energy conversion system ability to design manufacture many electricity production components absence of significant structure interaction corrosion on the water side but well known technologies and chemical process to master for example the quality of the water in the absence of the intermediate loop acceptability of ingress in the primary system of the coolant introduction of water in the primary sodium was not really wished this is the main reason to have an intermediate loop and so on even if we have sometimes some other solutions we investigate some solutions like double world steam generator also some degazine systems and so on but important point also is ability to avoid any acceptable trisium release trisium is a tricky element is a top of hydrogen which is produced in all the nuclear systems and as I said there are very strict rules in terms of release to the environment so it means that you have to master this point so in sodium we have made a demonstration that we are able to master that but it's necessary to do that for all the systems because sometimes people forget that trisium even if it is a beta emitter needs to be well mastered so when we select you have a lot of I don't go in this table of course just to say that some of them are not we are looking all the melting metal with melting points below 330 there are a lot of possibilities but a lot of have large drawbacks for example potassium if you have only potassium you produce a lot of agon 41 in the chlorogaz indium indium you produce you have some corrosion thalium thalium is poison bismuth produce we will see it can be used but you produce also polonium 210 sodium not interesting and so on one which is interesting also is the gallium why? it looked more carefully because you have a very large temperature range in liquid state between about 30 degree celsius and 2400 so it means that you have a very large liquid phase and could be interesting because the rest there is a problem we will see later of behavior with the material and so on I don't go in detail to comment so coming to the sodium here you have the sodium you know that sodium is here on the left column it comes from the from Arabic alkaline means hash coming from the sea and here the sodium on the left column it means that it is very reactive is a reducer due to is external electron here the lead comparatively is in the center of the table just for the availability of sodium sodium is largely used every year we produce around 200,000 tons of sodium for many applications the most important application is the blue color blue indigo the indigo is about so here is information coming from metospatio which is a company installed in France belonging to the nippon soda and here you have a lot of applications the most important application currently is the production of pure selisium titanium pure titanium but growing and some other applications a lot of boridrate is also for the in your car when you have in case of accident you have a balloon which inflates yes so there are a lot of applications for that so it means that the cost of sodium is fixed by the other applications when the people from nuclear comes and say I would like 5000 tons of sodium for a reactor like super phoenix is not really an issue for them to produce in two months they can produce you for you the sodium required for a reactor ok this is sodium coming from the mines ok is produced by electrolysis is a very hard process the factories started its activities in 1898 at the end of the 19th century in the Alps ok so diverse application in the good detail you will see but sodium sulfur batteries are currently developed particularly in Japan for some other applications now it's important maybe for the future also because we know that using renewable energies will require also developments of storage capacities sodium is used also for another application is dynamo experiments there are some teams focusing on the to get a better understanding of the magnetic field of the earth movement and so on so the best option is to use sodium in some systems where you are developing some very specific movements and you create a magnetic field like that so this is an experiment which was developed in Mikadarache but the first dynamo experiment was observed in Riga in Latvia in 1991 and there are some other laboratories in Russia, in Perm or in USA in Germany now a new facility and so on main sodium characteristics so in terms of toxicity you know it's not toxic everyday you hit some sodium and you have a lot of resource the sea water of course and the earth crust so there are no any issues in terms of availability no specific toxicity like lead of course but of course you need to avoid to breath the vapors and sodium hydroxide is not good so we call more not really toxicity but we prefer to speak irritation corrosivity and so on it's not intrinsic toxicity the lead about the lead in the economic value it was used really in the past a long time ago it was used in Egypt for example we have found some figurines it was used also for the water pipes in the city of Arla in south of France we have found all the pipes made of lead 2000 years ago and a lot of use so it's largely available even if now the lead a lot of lead is recycled from the batteries we have a lot of recycling and we don't need a lot of new whore for that lead is here so it's less of course much less reactive than the sodium if we compare very quickly main difference is on the melting temperature boiling temperature also is an advantage for lead density here the fact that the density and viscosity is close to the water it's clear that this is an advantage for thermoidolic studies specific heat is different but if we multiply specific heat by the density we have similar properties heat transport properties is better for sodium and so on about the main advantage for the lead they are here I indicated that the main drop box is the corrosion in a city to have an efficient oxygen control on a city to foresee reliable coating there are a lot of developments which were done in the last 10-15 years toxicity even if it is disadvantage because the pressure the partial pressure is low seismic resistance for sloshing high melting point can be a disadvantage because you need to maintain the reactor always at high temperature density dismantling chemical conversion is not possible in sodium we can come back to the sodium hydroxide and to a salt with the lead probably we will keep in state the lead there are no options for that and of course no operational feedback for the lead except LBE in fact lead absence of chemical reaction this is important one absence of coolant fire of course good capacity of lead to secrate under natural conversion thanks to a good crash of number main drop box in on come back I think I would like to underline one of them is the of course the lead material compatibility they need to have generally a velocity below 2 meters per second in order to avoid any important corrosion so it is a constraint for the design another point is also the poor wetting capability due to the fact that they need to maintain a coating they want to maintain a coating if you have a coating generally it is because you limit the wetability in fact the wetability of the structure so it means for in service inspection we are in in a so good position compared to sodium because sodium is a reducing element after that after emanating above structure oxides you have an excellent contact between the sodium and the structure so it means that if you have ultrasonic technologies generally we don't face any difficulty due to the wetability so it's important advantage for sodium absence of chemical reaction of course can be an advantage as I told you but it is also a disadvantage because the cleanup process with sodium what we use we have a cleaning pit with steam we clean up with steam and we produce sodium hydroxide and you clean up very easily the structure wet with sodium so we can also destroy the large amount of sodium the sodium into sodium hydroxide and after neutralization has water with salt if you have not the interaction between the coolant and the water you have some difficulties to develop efficient cleaning process even if we did that for lead business we need to have a more sophisticated process using for example nitric acid or oxalic solution so it means that for sodium the cleaning the interaction between sodium and water can be an advantage then sometimes we have considered also the binary I go quickly through this system sodium potassium was used in the past lead business we know the properties it was now extensively studied for the ADS as a coolant but also as a aspiration for aspiration targets lead lithium can be but we don't use it because the production of lithium is not an objective for the efficient reactors lead magnesium was studied by the Koreans there was some investigation about the lead magnesium when you have a two binary compound what is important when you have for example here lead and magnesium which is easily oxidized if you have an ingress of air you create for example here magnesium oxide so it means that you modify the composition so it means you need to foresee a system which is able to maintain chemical composition of the coolant in case of pollution particularly the pollution of air this is the most anticipated pollution so you need if you select this option it's necessary to investigate the system to introduce fresh magnesium in the system and to have a good mixture and so on here you have the diagram I don't go you can see here the minus 12 melting point for the eutectic ok, I would like to underline also sodium potassium was also abandoned because you can have some safety issues due to the formation in case of contact with oxygen you can produce some products like potassium peroxide sodium superoxide you can have a violent reactions there was some accidents in the past using sodium potassium and when you have a component using sodium potassium it is necessary to freeze to freeze the sodium potassium at a very low temperature for the transportation ok, in case because just the contact between the liquid sodium potassium and its oxides can generate a violent reaction so it's important to note because sometimes people think this is the reason why we don't use for the new project sodium potassium about lead business, I don't go into much detail but low melting temperature one key point is how to maintain how to maintain the right oxygen content we have to avoid two things if you have a too high oxygen content you can have a precipitation of lead oxide and if you are too low oxygen content you have an area where you can have the solution of some elements in particular nickel elements so it's important to keep the sodium the lead business in a range of oxygen content which needs to be well well monitored or another option is to foresee coatings but coating you cannot have coatings everywhere so it needs new developments of materials for example maybe yes I think for the lead is more stringent ok so aluminium coatings there are different techniques developments for example in Germany with a geza system implementation of aluminium in the material and so on there are also some solutions which are used because if you create lead oxide when you have sodium oxide it is easy to come back to sodium because sodium is a very reducing element so the oxygen is dissolved and thanks to a purification system I will come back on this point you can purify your sodium easily in case of lead oxide it's more tricky to reduce the content of lead oxide so you need to apply a specific process with particularly hydrogen so there are some options but you need to have more sophisticated chemical control of the content we have a potential interaction with sodium why I mention that is because we investigate the possibility to use lead business in the intermediate loop and if you have ingress of lead business in the primary what we create is you are able to create this product so it means that you create some particulates in the primary sodium in case of rupture of the tightness between the intermediate intermediate heat exchanger so it means that we have to take care about that and of course we don't want to have polonium in the primary in the primary vessel of a sodium fast reactor so but what I mention here is just to have but we have a very large operating feedback of course there was a Russian sovietic feedback but more recently there was through the european programs there was a lot of investigation not only Europe but also in other countries an issue which was on the line is a bismuth some people say it's a bismuth we have not a lot of bismuth this is not exactly true we have a bismuth generally you find a bismuth with the lead or and the galini but the problem is that now for the production of lead for the batteries the producer select whore with a very limited amount of bismuth why because it's not so easy to separate lead and bismuth so there are mines rich in bismuth but very few are exploited for the previous reason I told you for example in Canada there are some interesting mines but the problem is that the lead bismuth is used for some specific weddings for example for some monuments for the church what we call vitrai I don't know how we translate in English so it's a very specific application stain stain glasses so it's not a big application so it means that if there is also a bismuth for some medicine bismuth is not considered as a toxic so it means that there is not a big market so it means that if the nuclear starts to ask for a lot of bismuth nuclear will have to pay for the extraction and production of lead bismuth because there are no other large applications so it's an important issue the cost is about 25 to 30 euro per kilogram I don't go in detail here you have some data about the availability it's just you have a USGS survey every 5 years and you have an idea about the production of all the minerals which are used in the industry about the gas few words about the gas about helium the main reason is okay, the neutronics the main arguments, neutronics transparency no phase change chemical inertness, optical transparency opening the gate to high temperatures yes, through the very high temperature which is not really very HDR is the thermal reactor but for gas fast reactor can be used but the problem is that you need to have a perfect tightness if not you need to have some storage close to the reactor specific motivation for helium here you have a comparison of properties between steam, CO2 helium, argon compare to sodium is a good gas coolant nevertheless the main drawback is a low capability regarding natural convection and also the thermal inertia of course about molten salts for primary circuits I don't go in detail because they will be anticipate the presentation on this topic but there are different molten salts nitrates, chlorides fluorides only fluorides I take into consideration for the primary for the primary circuits of some nuclear reactors you know that there is a specific there are specific properties good cp thermal conductivity which is rather low it is transparent dynamic viscosity close to water we have high melting temperature but the necessity to control the redox potential to limit the corrosion a key point for fast reactor is stability as coolant under irradiation at high temperature and of course we have how to manage the efficient products in a continuous way you need to have I would say a reprocessing plant connected to the reactor so there are some studies on MSFR and there are some specific salts with a high I would say a high temperature range of temperature up to but I don't go in detail because it will be addressed more specifically about intermediate loops we have as you know possible detrimental effects due to the sodium reactives with air and water but water was ok here we have to take care about that with the sodium fires but about water so as I told you we have two different options one option is to develop energy conversion system using a brighton cycle so what we have selected is pure nitrogen because it was simple we have investigated nitrogen mixed with nitrogen and helium but we found that the advantage to introduce helium was not so significant in terms of thermodynamic efficiency for the energy conversion supercritical CO2 is interesting because we can reach in the future if you solve some technological problem particularly with the turbine we can reach thermodynamic efficiency so just to give you some values with the water with the ranking cycle the thermodynamic efficiency can be up to let's say between 40 and 42 there are different options in steam generator it depends of the number of stages between 40 and 42 with nitrogen around 37 maybe a little bit more and with the supercritical CO2 we can maybe estimate to reach maybe 43-44 ok so it means it can be promising with the gas nevertheless we will see that we have an interaction with sodium but it's quite different than the interaction with water ok so it can be interesting this is the reason why there are always some investigation within the frame of GIF generation 4 forum it's a topic of studies in order to investigate this option if we keep the ranking option means with the steam one is you can have detection system very efficient we have today developed some systems to detect the hydrogen at a very low value we are able to detect hydrogen at the value of 10 power minus 8 grams grams grams of hydrogen per gram of sodium ok 1 0.01 ppm of hydrogen per gram of ppm of hydrogen in sodium so it means we are able to detect very quickly a sodium-water interaction I recall you that sodium plus water gives sodium hydroxide plus hydrogen plus heat heat which is able to you can have an interaction and we have a bundle of pipes when you have an injection of steam in the sodium you can create a hot point in a neighboring pipe and create a secondary sodium-water interaction and so on you can have a propagation of this sodium water in the steam generator so the hydrogen has to be avoided this phenomena arrived in UK in PFR reactor so this has to be mastered but thanks to efficient detection of hydrogen you can there are two systems one is with nickel membrane where you have a permeation of hydrogen through a wall another one is electrochemical hydrogen meter which has been developed initially in UK and now currently for example in India or in Russia and you have these systems which are very efficient about you can avoid also to have another option is to avoid any welds under the sodium with the pipes because generally the most important reason to have a leak is generally to have a problem at the level of a weld so there and of course you can have inspection by ultrasonic techniques for example in Monju for Monju they have developed a very efficient technique to control the defaults you can have in the steam generator pipes so it's clearly there are some solutions and of course the last one was the double world steam generator units which happens particularly in US but seems not to be feasible and very efficient you don't improve really the reliability of the system so this is the reason why we prefer to keep the other options and last option is to investigate investigate the possibility to remove the sodium mediate loop and to for another coolant so we made the comparison for that we have a methodology to compare the coolants with regards to various parameters for example you have this parameter you have the reference of this paper produced by CEA where we compare the properties of various typical coolants through different parameters this parameter you can see fusion temperature vaporization temperature and here you have the difference of temperature between the fusion and the vaporization this is in fact the range in the liquid range of temperature in the liquid state so if we compare that this parameter we give the value of one for the best one what is the best one is the gallium why is not surprising as I told you previously the gallium melting point is around 30 and the boiling point is 2400 degrees if you compare these coolants you can notice that the tin can be interesting but for other reasons we don't use it for corrosion you need a multi when you have that you need to have a multi criteria evaluation of course but here it's a comparison with regard to this parameter so the gallium then you can see that the sodium and lithium are interesting the lithium also the lead and okay lead lithium but for other reasons we are not interested here and so on another parameter is transport and transfer this is interesting parameter here you have the cp it means row cp it's in fact the terms of transport of the heat and here the term B and the term C is connected you introduce in fact the heat the conductivity and so it means that you have here a term the heat transfer potentialities through the exchangers and here when we look that the best is the lithium then you have the water but we are not interested really in our case with the water and so on and you have also the gallium again and the sodium is not so bad another parameter we call that is related to the cycle efficiency row cp the best one is again lithium water and sodium so you have several parameters like that so it means that the sodium is always has a good good performances some words about the gallium gallium has been used in some experimental loops in fact is a product you find the gallium when you are looking for the aluminium or and we have a factory producing gallium in France for example but so interesting properties except one key drawback is a very severe attack on the materials and embrightment just to give an idea this is the kinetic of corrosion of steel of iron 1.9 millimeters per day 400 degrees celsius it's like if you put sugar in the coffee so it means that you need for protective coatings, there was some developments with the vanadium alloys but you can imagine that the reactor to coat everything with the vanadium it's not maybe suitable so there is some paper sometimes there are some reference here reaction between sodium I told you yes you have a production of bay and nafri here this is the reason why we don't like to much to have in the second intermediate loop about the molten salts we have investigated the molten salts which are used currently in the solar applications in the solar applications for example we came in in Italy in Rome to see people from La Casaccia they are using some molten salts for concentration solar applications I will come back sorry there is ok sorry I will come back in the previous one yes this is molten salt nitrate now we know also that we have made some test interaction between sodium and nitrate can be violent strong interaction this is another reason we have found but another point is also the maximum temperature is result low so it means that if you are above this temperature you start to have a decomposition decomposition of the molten salt you produce NOx ok what we call NOx nitrogen oxides and so it's not so easy to keep the quality so for solar applications it's ok but for our conditions and taking also the wish to have some range of temperature above the maximum operating temperature in case of malfunctioning or so it means that we are not satisfied with this option another option is the evaluation hydroxide compounds for example binary NOH-KOH we have some good properties except of course we have some reactivity with sodium but it's very highly corrosive and so we have some drawbacks if we use that particularly to have only nickel based stainless steel and could be could be possible but it's difficult to develop such option another option was also studied particularly in US and also in Japan by the Hokkaido University there was some investigation about the possibility to introduce in the sodium some nano particles nano particles of nickel and titanium what we have seen the key point is what is seen is that we have less reactivity between this product and the water but but necessity to study deeply the following point manufacturing methodology on to maintain the stability and the homogeneity of this mixture what happens in case of introduction of air for example pollution so if you need to if you are not able to recover the initial composition and distribution of nano particles quite difficult so it's interesting in the theoretical approach but in a practical way it's difficult to implement gas coolant for energy conversion coolants ok helium nitrogen nitrogen peroxide there was a solution which was investigated long time ago in soviet union but it was abandoned due to particularly safety issues steam, supercritical water carbon monoxide is not considered could be there are some interesting properties but you know carbon monoxide is not explosive we don't want to have the same hazards we have in the mines coal mines hydrogen also but is not considered for the same reasons if you look on the diagram ternary diagram showing this hydrogen air and humidity the zones of risk you can notice that it's very it's necessary to maintain certain humidity to avoid this is the basic principle of we master the hydrogen hazard in the pressurized water reactors using recombiners same approach so you can maintain also humidity or you can use recombiners so here hydrogen is not really a solution gas coolant properties I don't go in detail about supercritical fluids what is important here you have the diagram one is interesting is the carbon dioxide you can see that the critical point is 31 degrees the critical pressure 70 around 74 and if you look so here you have a diagram showing a triple point here you have the liquid state the gas state in the supercritical region supercritical CO2 as a property to have very interesting properties in terms of density and so on and the behavior sometimes the advantage of liquid and the advantage of the gas it can be used for it is already used for some other purpose for example for coffee to extract the caffeine it is used also for we use that we develop some process to decontaminate the soils you have several applications so here you have a typical energy conversion system where you extract you have to go through a turbine the specific turbine is not a traditional gas turbine it is so called a radial turbine which is technologically slightly different than with classical gas but you need a lot of storage if you have a system you need to have a storage for CO2 so it is possible and due to the advantage of potential advantage in term of thermo dynamical efficiency of energy conversion system as I told you previously 44% there is some interest to go on studies with supercritical CO2 this is the reason why you can see several papers in this item one of the point we want to address also will be the interaction between sodium and CO2 when we have a sodium fire we don't distinguish of course with water or with carbon dioxide because due to fact in carbon dioxide you have oxygen you could have some in don't stop the fire but for the study of interaction for example in the intermediate heat exchanger in the intermediate heat exchanger sorry in the exchanger between the secondary sodium and and the supercritical CO2 we have seen that we don't have a possibility to have propagation of this leaks like with water previously I mentioned possibility to have a propagation of sodium water interaction in a bundle it has been demonstrated that it is not possible to have such phenomena using supercritical CO2 this demonstration has been done by Kyrie in Korea recently within the frame of gen4 activities so it remains interesting there is less so in terms of corrosion we have a lot of feedback particularly coming from the UK studies we had some reports given through different meetings showing that the interaction between CO2 and CO2 with materials is acceptable ok studies and more recent studies don also that demonstrates of course we have to take care about that but it is not this issue can be solved we can solve this difficulty what we have done nevertheless we want to see in case of leak what happens in the sodium so here it is rather complex when you have a sodium water reaction of course it is almost instantaneous but the leak depends of course of the water flow rate injection injected in the sodium but with a supercritical CO2 sorry with water you produce always sodium hydroxide hydrogen and heat ok so for this reason we have an impact on the neighboring pipes you need to have a very fast detection and so on with a case specific case of supercritical CO2 the reaction is not the same if you work above 500 degree Celsius or below 500 degree Celsius there was some studies performed in Japan in Korea in France and here I show you what was done in France above below 500 degrees you produce oxalate you produce a part of carbonate oxide, carbon and carbon monoxide and after that we have a reaction between sodium and carbon monoxide which produce carbonate but this reaction the interaction between sodium and carbon monoxide we have a so called induction time so it means that you have not instantaneous reaction below 500 and the induction time depends on the temperature difference between 500 and the operating temperature for example if you are at 400 the induction time is more important if you are at 450 at 500 no more induction time so it means that in this case if you have the leak in the lower part of the heat exchanger you will produce carbon monoxide and this carbon monoxide can be located transported and located in the cover gas in the intermediate circuit for example where you have your secondary pumps for example or at the top of the heat exchanger so what it means in case of event of course you detect so it's not so complex to detect presence of carbon dioxide or carbon monoxide using for example chromatograph or mass spectrometer nevertheless you need to have sweeping to sweep the gas in order to eliminate quickly because you can have a secondary reaction of course it will depends on the content so it's necessary to master correctly the carbon monoxide deoxide and monoxide in the secondary intermediate loop above 500 in the upper part we have no problem because we have already this reaction so you produce some particulates so it means that you will have to prefi but it's not dissolved the dissolution of the sodium carbonate in sodium is reser limited so you need to filter you need to foresee a filter can be a tangential filter there are different techniques for filtering and so it's okay what we did we have done a study also when you have a leak injection of CO2 into the sodium we have developed a system where we are measuring the temperature with let's say a comb like a comb with different samples we move the comb and measure the temperature profile the temperature profile from here close to the leak and going in the sodium in order to know what is the temperature as a function of the distance from the leak so it's important when you develop a heat exchanger and we have developed that and by using a reverse how to say methodology we come back from the profiler temperature to the kinetics so we have established the kinetics of this diffasic system with sodium and bubbles of carbon dioxide we did also some other experiments with this system up to 200 bars because yes I forgot to say that we can foresee for example high pressure up to 200 bars in this system and we have a system here where we have what we call autoclave and we have a good resistance to the pressure here we put something like coca cola or beer and what is interesting here when we have sodium we have CO2 and of course when we increase the temperature suddenly we can follow the reaction and avoid burst the burst of this box we have a counter pressure which is applied which is applied outside this box so this methodology is currently used in the chemistry for safety studies yes what we have seen is we have measured here you can see the evolution of the concentration we increase the constant CO2 and here in blue you can follow the pressure suddenly we observe reduce the pressure and we analyze also what we have seen here that we have some small consumption of CO2 and then suddenly we have a decrease of pressure and exothermicity so the pressure decrease in response to the induction so-called induction time due to the carbon monoxide which is produced also by a reduction of the CO2 ok so it's an interesting methodology where you can we are able to follow the composition of the gas and the pressure and so on I have tried to give you another view of some options of course we can tell a lot of things about this I hope you have good information I will provide you presentation I will not give you about the typically sodium properties but it's not it's not updated because we have as it was told by Shirai and Vladimir we have a CRP called the NAPRO and we are finishing the work reviewing and it will be an excellent reference for the sodium properties and so we recommend of course to use these properties so you have these values but it is not the last values so if you need some properties of course the best is all you need you can contact us we can give the results already of the document in the next 6-8 months I would say the tech doc so thank you for your kind attention