 Good morning and good evening. Now We will have a lecture on generation for reactor design concepts that will be delivered by by Mr. Chirayov Bartra You know him already and please Listen carefully and ask him questions is in chat or then online here So Chirayov, Sri Bartra, please go ahead with your lecture. Thank you Vladimir. I think you have to stop sharing before I can Cool, so I think you already know me and I hope I will not bore you with the lecture. I hope you are enjoying it so far But let's go ahead. So I'll be delivering the lecture on generation for reactor designs Sometimes I get really excited about my lectures because I'm too invested in them and this is one of those lectures where I'm really invested and You will see why I'm invested in this as well. So Before I start brief acknowledgement for Professor Mikithyuk, this lecture is based on the presentation that he gave in 2018 So there's a powerful storytelling which is involved in this lecture and with the permission of Professor Mikithyuk I have taken this story and I prepared this lecture with some minor modifications. So if you want to see the original lecture The recordings are also available on YouTube for the 2018 lecture So this is the brief outline of my presentation I'll talk about mainly the generation for international forum reactor design concepts I'll give a broad introduction to what GIF is What are the GIF goals and what kind of technology selection they have done? I'll also briefly tell how they have done it because they have a very strong criteria on how the selection is done I'm not giving this lecture on behalf of GIF So I have no relation with generation for international forum. So I can also give some of my independent Opinion or independent review of what I feel about it So take this lecture also in that way And as I said that this is more of a storytelling So you can just relax sit back and enjoy the lecture. So I hope You'll be enjoying it as much as I enjoyed when I first heard this lecture. So will be good What I feel before I go ahead with this with explanation of these technologies is that GIF has put forth a very strict criteria so Most of the designs that you see currently in the market They might or might not be qualifying all of those criteria So GIF has like four criteria's eight goals and then several other parameters to qualify whether The the the reactor design is actually a generation for design or not I mean and in most of the technology industries, that's how it happens I mean you qualify the technologies from one generation to another to see how they improve So the intent is correct to see that how moving from one generation to another we can lead to a better product But in this journey, whether these requirements became too stringent or not This is something I leave for you to decide but in my personal opinion that These requirements could be very strict and not all of the designs which are currently in the market Might qualify for all of them. However, they will still claim as generation for design. So You have to be a bit aware. You have to be a bit Observant when you look at this generation for designs and understand whether they actually are Generation for designs or near to them. So this I will leave for you to have your own expert judgment on that So I will talk about the general features of these different designs Then I will also go into the specific design concept. So we'll pick up one concept Give the design description for that one And then specific features of the selected design So once we select a design out of this sex and then I'll go into the specific features for that and then some broad concluding Statements will also be given at the end This is How the reactors actually evolved so we have been talking about generation for but I think it's also important to understand that What were the previous generations? So the first generation of reactors were like from 1950s to 60s Which now probably are still a couple of them functioning in UK, but most of them have already retired and this I also said this was Previous to the era of regulation as I like to call them because if I take about big regulators like us and RCs They were mainly established in 70s where they started regulating more and that's where this requirements for safety And then things like that came into being before that they were more like demonstration projects becoming commercial But then in the generation to where there was this stringent requirements already coming into place These were also designed for longer lifetime. They had a particular design configurations and things like that. So From 1970s to most of them will be retiring in in 2040 So I can we can say that majority of our fleet is currently generation 2 So and the new ones that are currently under development or deployment are actually generation 3 or 3 plus with almost None of generation 4 designs actually coming into life as a commercial project so far we can again as I said the definition of generation 4 could be challenging We might claim some of these would include fast reactors like BN series could be generation 4 reactor But whether it qualifies all the criterias and goal will see through the story whether that happens or not So most of the designs currently are generation 3 plus and I've also written the IEA definitions of evolutionary and innovative which I also explained in my first lecture But the goal of this generation 3 or 3 plus designs as they are deployed now was to have some simpler designs and reduce cost Maybe more efficient in terms of usage of the fuel or even in the terms of efficiency of the final power of the power plant in general High emphasis was also on the safety The availability should be more higher so that means the longer operating life as well as higher capacity factor There should be reduced core damage frequencies The aim to have higher burn up because we want to extract as much energy as we want as we can from the fuel Better load following capabilities. This is also becoming more and more important when we are talking about the mix of the renewables that is coming into the market And then there was some brief, let's say attempt to also make modular design to AP600 which was certified for design but never licensed to build And the bigger version AP1000 was actually licensed to build later so we are seeing some AP1000 coming into getting connected to the grid recently Then moving ahead in this generation, the generation 4 designs were then targeted to be safe, secure, sustainable, competitive and versatile in application We also have to understand that we need both technical as well as an institutional innovation if you want to reach these goals of generation 4 So the technical solution itself is not in enough condition. It might be a necessary condition but it's not in enough condition We need some kind of institutional innovation and the institutional innovation could be in the form of legal frameworks or regulatory framework or deployment strategies, whatever you call them We need something beyond just moving to the technology for the generation 4 reactor designs to come into life This is just a summary of my previous slide that within this evolution some examples are given for early prototypes which were classified as generation 1 And then they were usually off of smaller scale than this gigawatt scale that started now I wanted to put a graph which shows that how now the number of reactors is very much equal to the number of gigawatts that are being installed or put into the grid But this was not the case before. There were like large number of reactors coming online but they were always usually smaller and I gave part of the reason in my first lecture as well So here you can see some examples that the early prototypes were almost of all types. They were like gas cooled reactor, heavy water reactor, sodium cooled fast reactor, high temperature gas cooled reactor and pressurized water reactor And then once we moved to this generation 2 where we wanted to deploy large reactors massively at a speed You can see here that all of this reactor technologies became like water cooled reactor designs So where most of the world started following the light water reactor path, some countries also took the path of heavy water reactor like Canada or India So then this became major technology and that's what we have to understand that part of the reasons for this was that the industry moved towards this design Which was commercialized first and then probably through the learning process, the learning curve made it such that it was much faster to deploy this technology And I always say that the customer as well as the cost that would always drive the technology further So here this was this technology was demonstrated, it was safer and then everybody started following the same technology in different countries And that's where the mass deployment of generation 2 happened Then there was a hope to make them better. That's where the generation 3 or 3 plus started and we are seeing several of this design and all of them are also again water cooled reactor design But then I think the whole human race is developing based on the innovations that we are doing in different fields So nuclear should not be left behind that and that's where I feel that the innovative designs become really important Which was actually similar to what happened in generation 1 but the goals might be different in this one The generation 1 was more focused on like how to get them done but now generation 4 is like now we know the technology for most of them Let's see how we can build them at a scale that we want to build for meeting the energy demands of the world So this is what we'll see happening. I mean the prediction for mass deployment has always been from 2030 onwards So this decade I still call as the decade of technology demonstration and strategy buildup And then hopefully if we are doing things correctly in this decade, we'll see mass deployment of generation 4 reactor technologies happening from the next decade onwards Now briefly on what GIF is, so it was established in 2001 so it's almost a two decade old organization It was a cooperative international endeavor which was seeking to develop the research which is necessary to test the feasibility and performance of the 4th generation of nuclear systems And then the idea from the very beginning was to make them deployed by 2030 so I think they were probably predicting quite early that this is going to take time It's not going to be an easy going process. So GIF has almost 13 countries and European Union But Eurotom has 27 countries so it's a large membership, GIF has a large membership Which is then coordinating the research and development on these systems and there are several European projects also which are always supported to fund these kind of projects So GIF then identified through their stringent criteria as I said they have criteria, goals and different parameters I think there was a big exercise to evaluate all of the designs, possible designs and then finally they came up to the conclusion of the six major designs which have listed here The sodium cooled fast reactor, the lead cooled fast reactor, the gas cooled fast reactor, the very high temperature reactor, supercritical water cooled reactor and the molten salt reactor And you can see here that out of all of the six technology, five are fast reactors and there's a reason for that and we'll talk about that in the coming lectures What I also want to give you an idea is that what is the, I mean, some typical characteristics of this GIF technology as one slide and then of course we'll go into detail into each of this So here also you can see the neutron spectrum is basically fast for all of them except the high temperature gas cooled reactor which can only operate in thermal The coolants are varied from gas to liquid metal to even water, so the supercritical water reactor still uses water and we'll look into more properties later Then these are the operating temperatures, some of them are operating at very high temperature and most of them are actually operating at high temperature and this is what also makes them Different is that now it opens the gate for different applications which have been always been emphasizing that for nuclear to play a bigger role in the energy scenario It has to go beyond the electricity production because the main output that comes from the nuclear reactors is actually heat and we should be more open to using the heat for different applications And then fuel cycle is open or closed depending upon also the configuration that you want to use We can debate on which cycles can be closed and what are the processes required for that, but I think you have a different lecture on fuel cycle and I think you will get more insights or through that lecture as well These are the typical sizes so they can range from micro reactors to large reactors So when JIF was formulated I think the SMRs were not so fancy at that point of time as they have become now so they were not very much keen into talking about SMRs But I have seen the shift as well that JIF also has now special task force working on SMRs So because most of these as I said in my previous lecture it does not make us, I mean I'm not proposing SMRs or large reactors I propose like nuclear as a solution and depending upon where you want to put and what kind of output you want to and if you have massive demand for energy use large reactors I mean it does not make sense to have SMRs when your electricity demand is huge but there might be some niche application or if the cost is effective then why not So there should be more broader consideration than only talking about SMRs These are some example developers which have taken from Wikipedia or some other sources that these are the current vendors which are developing these technologies and this can be taken also for reference We also have to understand that whether these JIF technologies have been already deployed or what is the status of their development as well as deployment And you can see that out of the six, four of them have already been built in one form or the other either as a demonstration project or even experimental or even commercial projects Two of them are still in operation, this would include fast reactor in Russia and high temperature gas reactor in China, the STRPM But the good thing to note here is that all of them have an existing project in pipeline so sooner or later we will hopefully see some of the projects coming online This is just to show that these six designs, the red box shows that it's fast spectrum design, the blue box shows that it's thermal spectrum design Whereas this is super critical water reactor you can see that there is a dashed line for red which means that it's primarily thermal But with a design configuration it can also be operated in a fast spectrum whereas for modern cool reactor it is also primarily fast But it can also be operated as a thermal spectrum based upon again in the design configuration and all of them can have these applications which I will not repeat These are the currently operating fast reactor, why I have put this here is because I said five out of six technologies are fast reactors And this is just to show that at least for fast reactor technology there is good understanding of so-input fast reactor But that does not eliminate the need or the experience or expertise that we are gaining in other fast reactor technologies as well These are the designs and the development I have crossed one which I also want to highlight is the Astrid project in France This also happened because of the national policy to shift it to a later part of the century for the development and focus more on the current fleet for their needs And then as I say again it depends upon the country's policies, the economic requirements and what they foresee as the future If a company or a country does not see generation 4 reactor technology coming into picture soon and if it does not make a commercial sense it's not going to happen So it's very important that they make commercial sense rather than also being technically competent So these are several designs which are under development and you will see these are also fast reactors and most of them are sodium And some of them are lead or even lead bismuth reactors I always try to separate SMRs because that's what my job is also so these are just fast SMRs under development Which probably you briefly also saw in Vladimir's presentation and these are also at different stages of development Some of the let's say status is given in the last column which is like prediction from these countries that when they can expect these reactors to come online So the idea for the generation 4 reactors is to actually make nuclear sustainable and then most of the goals like safety, economic competitiveness Or the proliferation resistance, waste management, efficiency of resource usage which is like high burn up recycling efficiency of the plant in general Or again the important point here is the flexibility of application They all come into picture if you want to make nuclear sustainable and looking into it such different characteristics GIF decided to figure out 4 goals or criteria as they call them In this presentation I'll call them goals but I think on the website they call them criteria and then they have 8 goals corresponding to each of these criteria So the first goal is sustainability By sustainability what GIF defines is that there should be a possibility for long term fuel supply This could also be questionable that do we have enough uranium for the current fleet that can just keep it running for Hundreds of thousands of years, yes or no But this will again be a question on demand and supply Sometimes you feel that if there is a demand there will be an exploration process and we'll have enough uranium So for now we feel there is enough uranium but that might not be the case And that's why we have to make sure that how we can close the cycle or use some other concepts which can actually bridge more fuel And use some other cycle other than the uranium cycle, maybe plutonium or thorium cycle The goal is also to minimize the waste and long term burden of this waste I mean we cannot deny that there is certain form of radio toxic city that is left behind after the reactor operation What I can say with confidence is that we know how to manage it, it's a manageable process But if there is a possibility to minimize it we could also do that through other fuel cycle options and that's what they mean by sustainability Then safety and reliability is that there should be very low likelihood and degree of core damage The current fleet is already very safe, so this does not mean that the current fleet is not safe It's just a hope that when we move from one generation to another the core damage frequency should be reduced further And the other important thing that I feel is the eliminate the need for offsite emergency response Because if we are able to reach this goal then it just makes nuclear more flexible in terms of site independence So that the site can be located wherever we want In terms of economics this is probably one of the most important goal is that the life cycle cost advantage should be there in comparison to the other energy sources So we always have to consider not only the existing fleet but the other energy sources which are coming into market now If nuclear has to compete the life cycle cost has to go down The financial risk because sometimes nuclear projects are really long projects and I don't want to emphasize which ones But if the project takes too long there's a big financial risk that's involved in that If that risk stays we will never find more investors coming into that So we have to find that how the commercial risks become acceptable and that's also one of the goals for this So this is something which I really like and emphasize usually And the goal for is to have proliferation resistance and physical protection Which is always the goal for any of the reactor that we are making So this is now my template for how the story will go I'll talk about the general concept, the image and the main features I'll give some fact sheet, I'll give some specific examples And then we'll see the problems from the viewpoint of the generation for international forums So for this story our reference design is the pressurized water reactor which you all know The specific design that I have taken here is the EPR reactor The thermal power is 4,300 megawatt, the electrical power will be 1,650 megawatt electrical The efficiency is more or less 35% The primary coolant that is used is water, the pressure primary pressure is 60 megapascal The inlet and outlet temperature is the temperature difference of around 30 degrees Celsius The coolant and the moderator is same is water, the spectrum is thermal And in terms of generation for goals, that's what we have to look into this throughout this presentation Is how sustainable they are, how safe and reliable they are and what is the status of the economics for these reactors So in terms of sustainability, it has been marked as poor Because we have to take into consideration sustainability from the fact that how is the fuel being used in the reactor And we'll see that there are better options for improving the sustainability of the reactor So the fuel used in the PWR fuel rod is the enriched uranium dioxide fuel You all know that there are control rods inserted into every fuel assembly Here you can see a schematic of one of the assemblies of a pressurized water reactor It's usually a square lettuce assembly with usually 17 by 17 pins in one assembly And around 200 assemblies in one reactor for a gigawatt scale plant The cladding used is zircaloi, it's an open assembly so you can see some cross flows happening between the assemblies This also helps in doing a better heat transfer across the core The fuel rod is made up of very small pellets which are one centimeter in diameter That's what you can see here on the left side of the screen And for the better management of the shutdown capability of the reactor The control rods are actually inserted in each of the fuel assembly as I mentioned before Now what are the advantages of pressurized water reactor? It has got an operational experience and it's an established technology So we very well know how this operates So in terms of operation they are very less unknown And we always like to reduce the number of unknowns that we have for any of the technology we want to work with Light water is used as a coolant which is abundantly available It is transparent, it's easy to handle as well And it also allows for the boron control done through the coolant or the moderator itself So there is an added mechanism for the activity control which can be done with the help of light water which is flowing through the reactor So the challenges are it has got a high coolant pressure which somehow none of the engineer likes to work in high pressure environment This is the point about sustainability that we cannot achieve enough breeding to make sure that we have enough supply of the fuel The design center development are several, I have listed few of them like EPR, AP1000 or APR 1400 There are almost 300 reactors under operation which are light water To be heavy water or light water they are water cool reactor designs with the operation capacity of around 290 gigawatt electrical So from generation 3 to generation 4 Now when we want to move from this concept that we heard now If you want to increase the efficiencies, right now we see the efficiency is 37% Can anybody guess and you can just maybe switch on your mic or just shout it from the class as you like How can you increase the efficiency? Any quick answer on that? I'll just take 15-10 seconds break, if not then I'll just go ahead Okay, no one, I think, I hope you are awake, you're not sleeping Let's go, so the way to improve the efficiency is usually to increase the water pressure and temperature So that's what we'll try to see how we can do that for the secondary side in case we want to improve the efficiency In order to reach this goal, the first concept that I'm going to discuss is the supercritical water reactor cool concept So it operates at a very high pressure which is the therm... hello? Did I drop off or the meeting was...? The meeting seems to have ended abruptly Okay, okay, I thought like I dropped off or something We had a technical problem here, now restarting the meeting and Cherai will continue Wait a minute, I'm just... Sui is the supercritical water cool reactor concept where we're going to operate at above thermodynamic critical point of the water which is around 22 mega Pascal or 374 degree Celsius We want to combine the technology which is known in the coal plants which is the supercritical water reactor technology It will be a direct one through steam cycle so that means there will be no steam generator or steam separators and dryers as possibly is also the case in the boiling water reactor And here you can see two schematics that what do I mean by the critical point So this will be the supercritical fluid, this will be the operating temperature and pressure for this reactor in order to improve the efficiency of the cycle Now what are the advantages for this? Is that it's based on the generation 3 plus technology, so we already know this technology very well We have plenty of let's say operational experience with the kind of fluid we are dealing with It also merges with the advanced supercritical water reactor technology that is currently being used in coal plants So there is a lot of operational experience in the coal plants already for that So this is just a merger of these two And the higher steam enthalpy will also allow the reduction in the size of the turbine system So if that happens then it will also lead to the lower capital cost on the conventional island as well It has got higher efficiency than the generation 3 plus reactor And that was the goal we were targeting through this story And then it can work on both thermal and fast spectrum And this will depend upon the reactor core design that we take into picture There are certain challenges which is because we are operating at high pressure and temperature The material challenge will always come and that will come probably in most of the designs What I also want to tell is that challenges does not mean that we cannot do it It's just that we need certain kind of an engineering solution to do it And probably some engineering solutions are already available But the others might need to be developed as well There is some gaps in the thermo hydraulics that needs to be filled To understand properly the supercritical water heat transfer and the critical flow databases The safety demonstration probably would be needed and that will be the case for most of the reactors Which are trying to employ a different concept in case there are no experimental data available So if we are using fast spectrum and I think this might have been touched in other lectures as well That there is a chance to have a positive wide effect So in case supercritical water reactor are also operated in a fast spectrum then we need to see that Then of course the challenges of fuel qualification because you are operating at high temperature Then the fuel temperature might also reach to a higher temperature And we will see that in the next slide how that is also dealt with The designs in the development of this high performance light water reactor in the European Union And there are none under operation So then I will take the example of the high performance light water reactor What you see here is that the delta T which was in the pressure water reactor around 30 degrees Has now reached around 200 degrees So this is a big issue for the peak loading temperature Which is usually targeted for less than 700 degrees Celsius or around 630 degrees Celsius As I said every challenge probably has some solution whether that's applicable or not But in this case the possible solution is heating in three steps And this is very interesting and this is something I also got to learn while preparing for this lecture So what happens in a supercritical water reactor is that there is water ingress through the vessel inlet And it's divided into two parts half half briefly or let's say approximately The blue means let's say it is relatively cold and red means it's hot So what happens is that the water goes into the downcomer region And I will show that in the next slide where it is that it goes through the lower plenum Goes into the core inlet chamber and then follow the black line here with me That it goes into first of the evaporator goes into upper mixing chamber And all of these are done in order to reduce the power at each step So also to reduce the temperature of the coolant that reduce the temperature of the peak Lighting that has to be avoided then it goes into the super heater one Then goes again into the lower mixing chamber to get some homogeneity Then goes back into the super heater two goes into the core outlet temperature and then goes outside Then the other half it goes into the upper plenum and then it goes into the water boxes As you can see in the center of this assembly there are certain water boxes So this also helps in moderating the spectrum So this will also keep the spectrum soft and that's why the water the cold Relatively cold water flows into these boxes and then goes back into the lower mixing chamber To also have uniform mixture of the temperature So this water boxes with separate circulation circuit is to improve the moderation as I already explained And you can also see that the assemblies have a wire wrapper as it's the case for the Sort of good fast actor or fast actor so there is no grid plate But these are grid spaces but these are the wire wrappers around the assemblies to keep the cold compact This is how you see this was the block diagram but this is how you will actually see in the reactor itself So there is that feed water inlet water will come inside get divided into two parts One goes up one goes down to the down comer Then from the down comer in the lower plenum it goes into the evaporator Goes here comes back into the super heater goes here goes back into the super heater too And then comes out what it does is that it also allows the vessel to be isolated from the high temperature So the only high temperature that you will see is actually in the outlet flange And most of the reactor will be not seeing such high temperatures as the other part of the evaporator and super heater will be seen This is how the core will look like and this is also just to give you again that how the flow will happen As you said it will go from the down comer to the evaporator so this blue or evaporator And then from there it goes to the super heater one and then it goes to the super heater two zone And then it comes out of the reactor There are several alloys these are candidate alloys for the for the for the cladding like ferritic martensic steels stainless steel nickel based alloys or the or the oxide dispersed steel alloys Because we are reaching quite high temperature in this so that's why we have to think of for certain materials So the balance of plant is will not be much different from from the other power systems as we will see As we can see from this from this slide that we reach high temperature and pressure in the primary side Which then allows us to extract more heat and then which also allows us to have better efficiency like around 44% in this case And then the rest of the balance plant like high pressure turbine low pressure turbine intermediate pressure turbine Then the pre-heaters etc are very common in the other balance of plants as well Now moving from here until in the story let's see that we want to keep the high efficiency So we want we don't want to go back to lower efficiency plant But at the same time we want to avoid parameters which are related to the high pressure and temperature So what can we do in this scenario to improve or go from this design to another design Any guess five seconds Unmute and shout or shout in the class Okay one two three four five nine So the idea is that we can use inert gas instead of water So that's what we can try to do And that's where the concept of a high temperature or very high temperature or high temperature gas to reactor comes into place This can be in two configurations as I briefly explained in my first lecture that it could be both graphite prismatic Or again graphite based pebble bed reactor which are considered as the reference configurations in the JIF And which are also currently under development both of the designs are under development It comes with a very low power density which is an advantage and disadvantages of both the site At the same time we also heard some discussion during the first day that how the sodium pool fast reactor in the BN chain in Russia from BN 600 to 1200 is also going for lower power density So this is something that has been considered that if you can operate at low power density and still reach higher efficiency and better fuel utilization then why not do it I see at least some people are interested and they are willing to contribute Please mute your microphones So following the same procedure as the other reactors the some of the advantages for the high temperature gas gas to reactors are they have as they can reach high temperature There is a possibility for more non electrical applications they are considered as walk away safe because the configuration of the trisofuel particle is such that it can withstand very high temperature without any fuel damage The gas coolant is inert so we are not dealing with let's say a very corrosive or toxic environment and it has also got a very high efficiency because of again the reasons that we have been following through So the high temperature which enables a lot of application also comes with these challenges that we can reach really high temperature that means we also have to have materials which can withstand that temperature But this can also be then used for hydrogen production The coupling with the processing application might require certain kind of regulatory involvement which has not been done so far so that also be another challenge Then it also produces graphite as a waste and this is something that we have to consider in terms of sustainability as well because I mean this radioactive graphite also has to be disposed Now there is different classification class ABC depending upon how much toxicity is there in the material but closer it is to the core it becomes more difficult to dispose this as well And then there is also at least in US I know there is GTCC which is greater than Class C configuration and I am assuming a lot of graphite will fall under that category which actually has to then eventually go to the geological disposal That means if there is a chance that a lot of waste coming from these kind of reactors might be required there might be requirement that this waste should go to deep geological disposal if that happens Again this is very preliminary analysis and discussion so cannot be said with with with sure they are many and there is one under operation I should have I should have updated the slide there is also another one under operation in China which is the SGRPM and I will take the example of SGRPM to do this exercise so the SGRPM thermal power is around 458 megawatt thermal this is a twin unit plant the efficiency that we can reach is around 45% The primary coolant use is helium the outlet temperature is around 750 degree Celsius the pressure that we reach is we need a 7 megapascal and part of the reason is because we have to pump this helium through the reactor So it needs a high pumping power and that's why we have to pressurize the system the moderator is graphite the thermal spectrum and the spectrum is thermal and again as I said the quotient sustainability comes into picture because there will be large amount of activated graphite which will be in the classification of the right waste that's going to come out of it For safety and reliability we can assume that these are going to be safer because it has been touted as walk away safe reactor and in terms of economics there might be certain improvement while this could be still challenging to say because the trisofuel particle might be expensive now in the initial stages but again depends upon if it's developed more and it has mass production it can become cheaper as well So this is an example of how the pebble bed reactor will work you can see the pebbles coming from the top in batches and then as I said one batch takes at least one year to pass through it almost 500,000 pebbles are there in the core and where we can recycle them multiple times from 6 to 10 times it can go into the core and the average burnout that we can reach is around 90 megawatt days per gram of uranium I mean briefly about the pebble fuel those who miss my first lecture is that it's in the shape of a spherical ball around 60 mm in diameter which has got a lot of trisoparticle around 15,000 trisoparticle into each of the pebble here it says around 11,000 so the range depends and the trisoparticle itself has a kernel of uranium dioxide or uranium carbide depending upon the reactor design and followed by some carbon as well as pyrolytic layer so this is to keep the integrity of the fuel as well as to provide some kind of moderation capability in the reactor itself so this is more information about the STRPM design itself as I said it's a twin reactor producing around 210 megawatt of electricity the power density is low around 2 to 3 megawatt per meter cube and just to compare it with the pressurized water reactor it's a factor of 30 less than a pressurized water reactor and I think compared to a sodium cooled fast reactor it's going to be a factor of at least two order of magnitude could go low as well then for it has got high thermal inertia so that's good that comes with the graphite itself there is no need for I mean this is debatable but let's say for the core emergency cooling system because the decay heat is removed by the natural mechanism and I'll show you in the next slide how this is done so here you can see again some parameters from the STRPM itself as you can see the control is done to the control rods in the reflector region the vessel itself is quite narrow 3 meter but quite tall and the reason for that is first because the control rods are in the periphery so we need to have enough worth in case the reactor needs to shut down plus in case of decay heat removal which has to be passive the decay heat could be done through conduction and convection mechanism through the large surface area of the reactor so they can move towards the outside and this tall core can just remove the heat through the actual convection process as well the gas cycle is that it comes from the inlet goes in the top flows through all the so it's not going against the gravity it going with the gravity as well as with the flow of the pebbles and then comes out of the reactor as a hot gas we can use direct Britain cycle also in this but that's an area of development that's happening and this can also improve the efficiency of the reactor further and also helping reducing the cost of the reactor okay we saw that the weakness of again I'm talking just to continue the story is that the weakness of super critical water reactor as well as the high temperature reactor is low breeding game so what can we do in order to improve the goal one so far we have been tackling other goals but we have not been able to improve the question of let's say the breeding in how we can do that any ideas on that five seconds again what kind of reactor design will be useful in order to do that fast spectrum very good perfect we have an answer so good people are finally awake so yeah we can change the design to obtain the fast Newton spectrum that's how we can do and that's the next reactor in my cycle that comes is the gas cool fast reactor concept so we are still in the gas cool reactor so we are using high temperature gas cool reactor but now we want to have some reading in so why not just keep the good properties that we were able to reach with the gas cool designs but make it a fast reactor concept so in this we don't need any moderator we can still use helium which is non toxic as the coolant and we can also use it in both direct and indirect cycles could be considered for this in this case we have considered an indirect cycle so the advantages are the potential for new fissile breeding due to fast Newton spectrum and we will see more into the coming designs that will come the coolant is transparent and inert that's what we are trying to reach when we are moving from super critical water reactor the challenges are the safety demonstration in particular the decay removal in case of loss of flow and the depressurization accidents there are certain engineering solutions for that which are in the which I will also cover in one of the slides and then again because we are working at high temperature so there will be challenges for high temperature material as well as the fuel qualification that will be required for this reactor design there are several some under development let's say the Allegro design as well as the gas cool fast reactor design from the European Union plus there are some private companies also like energy multiplier module from general atomics which are also under development under operations are probably none so far these are the characteristics of gas cooled fast reactor specific design chosen is gas cooled fast reactor from the European Union the thermal power is 2400 megawatt efficiency is 45% coolant is helium the pressure is we need as we need for the pumping we need some high pressure but we also have to take into consideration what happens in the depressurization accident when there is no helium flow in the reactor how will we remove the heat in case we are not able to flow the coolant through the reactor the moderator there is no moderator so we are dealing with the problem of low thermal inertia in that case we had the graphite which was able to capture some of the heat but not in this case breeding gain we are improving so that means we are improving the sustainability in terms of safety and reliability it could be more or less we don't know but because of this issue of depressurization and having low thermal inertia it still need to be question and economics we cannot say with any kind of surety because we have not seen any major development happening in this area the fuel will be quite similar as we have seen before so I will not go through it this is how the gas cooled fast reactor core will look like it will also be a very tall core with some inner core fuel assemblies as well as outer core fuel assemblies then there will be fission gas planems for release of the fission gases through the core then there will be some reflectors as well as the other shutdown rods as well as the safety devices that are required here you can see that there are certain active decay removal pump in this design and there is a main power conversion loop which will convert the heat to electricity plus the control rods and down drive mechanism is also from the bottom there is also a concept to have a spherical guard vessel all across the reactor to maintain the pressure boundary or have one more defense in depth layer so for the balance of plant it is also very conceptual as you can see here is the guard vessel but most of the things are quite similar so there is a decay heat removal pool with an active force circulation so this needs to be qualified that in case of an accident or requirement this should work and then the second decide is similar to any kind of power conversion system so I will not spend much time so there are ways to improve the safety so instead of coolant thermal inertia some kind of mechanical thermal inertia could be used by the help of some blowers or things like that the passive decay removal loop could also use Brayton cycle and then make it passive instead of an active so there are certain ways as I said engineering solutions which can also make it improve the safety ok so what can we do next I mean we have done this so the weakness of the gas cool fast reactor is low thermal inertia as we saw and that means we require some special safety measures in case of in order to avoid the core meltdown or things like that or in case of depressurization events how to remove the heat so what can we do to improve the goal to which is the safety so what can we have something which can have better thermal inertia or better ways to remove heat from the core any quick guess five seconds the answer is to use molten salt ok someone was saying online also something please go ahead yes I was going to say that using coolant that is operating at lower pressure normally is better like sodium ok so is a molten salt or sodium two answers let's see so the story goes in the way that we are looking at how we can extract more heat so we need something which can conduct better heat as well as a better thermal inertia so instead of gas let's start to use liquid metal that could also be a good option so why not use that and the first concept that we can use is the sodium cool fast reactor concept which I'm sure you have heard a lot already from Vladimir and I think there was also a lecture before me on sodium on liquid metal coolant by Christian Larges so probably you already know more than I know about the liquid metal coolant so that's good so this is brief schematic of a pool type design but you saw in Vladimir's lecture that it could also be a loop type design depending upon in some cases seismic requirements but there could be other requirements as well but this is loop type design where you see the primary sodium is here there is an intermediate heat exchanger and then there is a steam generator so why do we need an intermediate heat exchanger is also quite evident that there is a big reaction that sodium can have when it comes in contact with air or water so we want to avoid that and that's why we want to have an intermediate loop which will avoid this kind of accidents so the advantage is that there is a potential for new fissile breeding due to fast neutron spectrum there is an excellent thermal conductivity of sodium which can offer very efficient cooling that's what we were looking for there is large margin to boiling so it's not going to boil very easily and there is no pressurization required so it will be operating at atmospheric pressure or slightly above that and there is significant operation experience almost more than 400 reactor years of operation the challenges as I already identified in the previous slide was the chemical active and in contact with water air so that means we need an intermediate circuit that means we have an engineering solution that's what I always emphasize sorry we are still on the slide with gas graphite gas cooled reactor is it how about the online participants which slide do you see at least it's ok no here it's ok it's on mine on my screen something is wrong ok sorry go over it ok I go ahead so there could be a chance of positive reactivity effect and then we need to have some special safety measures for that and most of the designs know how to do that there are several designs under development I forgot to cross a straight from it it's no longer under development now and then there are under operation like BN600, BN800 and China experimental fast reactor in China and there are several under construction as well so some properties of the ESFR which is the European sodium cooled fast reactor concept it has got thermal power of 3600 megawatt efficiency of 42% the primary coolant is sodium marked in red some all the fields which need considerations are actually marked in red the pressure is as you can see is is almost atmospheric pressure the outlet temperature is is pretty high around 545 degrees Celsius spectrum is fast the goals of sustainability safety and reliability are more or less because we're able to remove more heat but then we bring this problem of sodium activity with water or air and then economics is something which will always be questionable till we deploy them this is brief description of the SFR fuel rod and the fuel sub-assembly the fuel is it could be mixed uranium or plutonium oxide I think that's what has happened also in BN600 and 800 they're using mox fuel and it's stainless steel they're hexagonal fuel assemblies and they have no possible cross flow within this wrapper so there is like there could be inter-wrapper flow between these hexagonal ducts but as I told you in the light water reactor there is also cross flow between the assemblies but it's not happening in the fast reactor and the absorbers are also inserted in the dedicated assembly so like in the light water reactor the control rods are actually in every assembly not not in the case of sort of cool fast sector part of the reason is it's a compact core and it needs to be also the activity also needs to be managed accordingly for that there is large gas plan on both our and below the below the rod as well this is the radial core layout of the SFR smart design it's almost perfectly symmetric has the configuration usually in most of the fast sector of the inner outer core reflectors as well as shielding it has got two groups of absorber rods for the reactor shutdown one is called is control and shutdown devices or rods and then there is like diversified shutdown devices and these diversified shutdown devices are there they are activated with the Curie point electromagnetic locks and I think there was some explanation done on this in one of the lectures before but if not it's like at certain temperature these electromagnetic locks will open and the rods will automatically fall down so this is a passive shutdown mechanism which can be inserted in this concept this is just the actual layout of the of the reactor so you can see that there is a fissile fuel it has a bit of higher enrichment of the plutonium that's what we need for us to start the reactor and then later it can read the fuel and then fill it itself and that's what the challenge that a lot of fast reactor vendors are facing is to how to get this high assay low enrichment to start the reactor or to get some some plutonium to start the reactor this is the global view of the SFR design from the top which has got three primary loop but has got 16 generator it's a it's a big reactor and also got some passive decay removal system is through air so it into air conversion this is probably I think for the SFR design Chris Chan will also have a lot of more understanding than I have for that this is the as I said it's a pool type design so this gives a actual cut way of the reactor and then you can see that the control rod type mechanism is from the top the core is here and there is upper and lower plan to to feed the sodium through the core the balance of plant concept is also similar this as I said this is a decay heat removal system which is sodium to air six heat exchangers use and the rest of the few heat transfer is done through an intermediate heat exchanger and then finally to the through the steam generator and the fuel uses uranium plutonium dioxide fuel so the balance of plan this is not simple not not very different okay now moving to the fifth concept the SFR is the most mature concept among all the gift designs however we saw that there is one small weakness which is the sodium water or sodium air reaction so how we can improve the gold two and three in this case while keeping the gold one so we still want to breathe we still want to keep it sustainable but how we can improve gold two and three okay five seconds to answer what we can do let majority select lead very good I think not many options are left to discuss so yeah so the right answer is we have to use some another liquid instead of sodium so what can we use instead of sodium the one of the obvious answer comes to some other liquid metal and that liquid metal turns out to be the lead cool faster and I think Vladimir Arthesuke was praising lead quite a lot yesterday and I will join that praise for the lead that lead is a doubly double magic nucleotide and you can use it in any configuration as you want depending upon the requirement so yeah lead is also one of my personal favorites design but it's it's simple there is no need for the intermediate circuit and the and several other things which are which are listed here in terms of advantages so that means there is still potential for new fissile breathing due to fast neutron spectrum there is high density so that means the thermal inertia is actually very high I mean sodium is not that dense the density is comparable to the water but for lead the density is really really high there is high thermal conductivity and expansion coefficient so that means we can efficiently remove the heat at the low velocities and I think that's what you have done in the exercise also to compare that how much velocity is actually required and probably it will be good to see what what comes out to that and there is a possibility for this high natural circulation level that could be achieved with this kind of configuration this is passive with the water or here so no intermediate circuit required and there is actually very very large while margin to boiling so probably you will never be spoiling in this case so anything that has to be do like two phase lead is not going to happen so that's a very good news for any of the people who are working in thermo hydraulics and the challenges are again high density becomes a challenge because when you scrub the high density material through the system it cause erosion and some seismic refueling issues at high temperature the structure materials such as iron or nickel are also slowly dissolving lead so that means some kind of coating is needed and we did a very interesting technical meeting Vladimir did and I was supporting him on the structural material requirements and there were a lot of papers presented actually on lead cool fast reactors that how these kind of structure how the structure material could be saved with different kind of coating so there are many engineering solutions that are coming up to protect the material there is no margin to freezing so that's very important so that means we have to keep it hot most of the time so that that's a challenge to do there are several designs under development and there are many commercial companies also developing this concept so there are no operators reactors under operation as we know we have some experience from the submarine but not from any of the commercial operation so some characteristics of the Alfred project that has been taken for this story the thermal power is 200 megawatt the efficiency is high we use sodium as a we use lead as a as a coolant the outlet temperature is around 480 degrees celsius the pressure is still atmospheric pressure let's assume there is no modulator spectrum is fast we have limited operational experience and economics we have limited this is the assembly of lead and you can see probably that it has been divided into two regions because the reactor is really really tall and this helps this kind of configuration helps in maintaining the integrity of the structure as well this is the brief schematic of the core of the of the Alfred reactor that same as any of the fast reactor core outer core and then control rods the reflectors and the shielding this is the actual cut away of Alfred reactor showing the primary system it's also a pool type reactor which has got enhanced natural convection in case of accidents the decay removal is done through isolation condensers which are connected to the deep coolers with straight double world tubes and the reactivity control is also done as we see with the two diverse and redundant systems which is the control and shutdown system as we saw in the ESFR project as well this is the balance of plant again because the concept is not that developed beyond so that's why you always see the schematics of balance of plant but will not be very different so you will see some primary side flow like this and then for secondary side the water will be used reaching higher temperatures and then using the high pressure low pressure turbine and the condenser and the feed water to feed it back to the reactor port okay cool so we have come to the five designs now we will slowly move to the six designs so what we have seen that in all of the systems the accident with the core meltdown has extremely low probability already but they might still be possible so in case it can still happen so how we can practically eliminate the core meltdown any quick guess using liquid fuel like molten salt perfect so if the core is already molten then there is no probability of have a core meltdown because this is already molten so that's where we come to the design that we can use the design with a liquid fuel so molten salt reactor can be used in a thermal configuration as you can see here where we use some kind of moderator or what I've done here is just put a block here to just show that in case there is nothing then it can be used also as a as a fast spectrum reactor and then the primary fuel or the liquid fuel could be kept separate from the secondary through an heat exchanger and then we can have a tertiary heat exchanger for the steam supply for the for the power island there are several advantages so again it is potential for fissile breeding due to fast neutron spectrum there is large margin to boiling so that means again this can operate at atmospheric pressure there is strong negative fuel salt density and I think you will have a lecture on molten salt reactor separately but you can guess also intuitively that in case let's say there is a void that happens in the in the core that means you are also displacing the fuel so if you are displacing the fuel that means you are also reducing the reactivity so this will have a negative reactivity feedback there is high efficiency due to high temperature there are no or almost minimum structural materials so I am not talking about the vessel itself the structural material are almost no or minimum so that means we are not doing any radiation damage to the structural material the possibility to add or remove salt is very easy you can have a certain loop which can just filter process the fuel and send it back to the reactor and we can also because of this possibility we can also remove continuously the insoluble fission products the challenges are molten salt fuel will be highly corrosive so that means it can affect at least the pressure vessel or the vessel itself is not a pressurized vessel so the lack of usual barriers which is like we have for the conventional reactors like fuel cladding or the other reactors is not there but there might be other ways to prove that these kind of barriers are actually not required for molten salt reactors the part of the fuel is always outside the core so that means we need a larger fuel inventory is needed there is low margin to freezing and then of course is lower unknown solubility of compounds formed during the operation because there has not been a lot of operational experience so we still have to see what compounds can actually form when there is ingress of some other structural material that goes into the molten salt reactor molten salt there are several in the development but none under operation so the example here is of the MSFR from the European Union again this is an open core, it's a fast reactor concept and it has got again three circuits which is like the fuel circuit, the intermediate circuit and then for the energy conversion system a tertiary circuit most of the designs also have this draining tank in case of any kind of accident the drain plug can open and all the salt can go into the drain tank and then freeze there safely and be subcritical as well this is again simple schematic for the heat exchanger which goes from the secondary to the tertiary side we can reach higher temperature in molten salt reactor practically around 800 to 900 degree Celsius and then we can have this intermediate cooling loop to remove the heat and send it to the heat conversion now the MSRs have to be honest like massive amount of configuration that you can play around and this is the GIF classification that came out in 2020, they can have graphite moderated and chloride salt so I mean I have not differentiated here and I should between and you will see in one of the slides that the molten salt these days as they are considered it could be like molten coolant or molten fuel but our focus is on the molten fuel not necessarily on the molten solid but this classification considers everything so they could be graphite moderated, they could be homogenous fast reactor or they could be some other concept so you can see from here some examples as well as how they will actually come out to be so for example if they have a solid fuel which will be trisoparticle in the graphite it will be pebble bed or prismatic as is the case the high temperature gas cool reactor however the coolant that goes through it is molten salt and that's why they are molten salt reactors as well but they are actually FHRs as they are called more conventionally so this is the new classification that agency has done, the IA has done in 2022 this document is not yet published it's in the preprint and should be out I think hopefully next year maybe Vladimir will know more about this but they have also done the classification based on the GIF and that's how the classification has come out it's probably difficult to read here so I have put a table which shows clearly that the fluoride salt cool reactors this family is different which has the solid fuel from the graphite moderated which has the liquid fuel and then you can see which spectrum they work in, you can see the type of salts they are working in it could be fluoride or chloride salts depending upon again on the spectrum as well you will see that most of the fast spectrums are using chloride but some of the fast spectrum in the homogenous structure could also use fluorides what configuration they can work like burner, breeder, converter they could also be possibility of to burn the minor actinides which as you can see here and several other criteria like what kind of heat transfer mechanism is needed is used here and where the primary heat exchangers are also located so in summary coming to the end of the story and I hope you enjoyed this journey from one design to another targeting one goal to another we have seen like six GIF designs and we have seen some advantages as well as the challenges of these designs but these are not to rank I mean that does not mean that the one that was shown first like the supercritical water reactor is worse than molten water reactor this was just to weave the story to go from one design to another and how to maybe to critically think that how we can improve one parameter to reach to another kind of design but this is in no way to rank the designs that which one is better than the another but some of the issues are highlighted in the red which I call them as engineering challenges some of them have found engineering solutions some of them have not found them some of them have not been found but hopefully once they become more real we'll be able to see how these are actually resolved and then something to for you to think about that this graph shows that what range is actually all of these plants can actually can work on so at different pressure ranges as well but probably I will not go into this this is for you to think about that in terms of operational ranges and the coolant densities how they could be useful or not I mean if you see that the density suddenly changes after a certain temperature or pressure what it can actually do is operation and whether it's feasible to operate in that range or whether it's advisable to operate in that range or not so this is something for you to consider later okay these are the references and I think I was able to complete it in time for some questions and answers thank you very much okay thank you very much Chirayu and before we start questions I'd like to notice that you forgot when you started the history of generation one reactor you forgotten to notice the first nuclear power plant which was started operation in 1954 in Obninsk we have people from Obninsk they just reminded me this sure I will put that in the slide I'll update the slide any questions from here yes thank you Chirayu is Christian here just a question about I have some maybe comments maybe a good question I think you have not addressed two points I don't know where they are maybe in the safety but what about the severe accidents for example for lead for example I have never seen a real detailed analysis of the severe accidents in lead fast reactors people claim that the corium go on the surface but after that in sodium or in the light elements the corium go in the thanks to gravity go in the direction of corcature okay so and with the possibility to distribute the corium but what about the lead in molten salt reactors we say okay there is a safe concept with regard to this point but what about the risk of modification of the chemistry with the possibility to have some melt down yeah it's melt yes but what about the possibility to have some modification of the stability of some compounds due to the creation of new products and what about the decommissioning also I think that decommissioning when you're now when you decide to build a reactor you need also to provide a strategy for the decommissioning so what about for example the lead fast reactors about the decommissioning people claims we can freeze just only freeze okay and after so and a point also and last point and last comment about we say that on the lead fast reactor we avoid the intermediate circuit this is true but not totally true because if you look for example in they decided in lead fast reactor to have a double wall because when you have interaction between liquid metal and the water okay you have a possibility to have you have to you have a physical interaction and chemical so chemical for sodium we have a production of hydrogen mostly not really pressure waves but okay but this is one point that is to be underlined and I think and yes we have made recently an exercise of course we have less investment about the we have intermediate circuit but what about the handling operations in heavy liquid metals so it's not so easy due to buoyancy and so on so we don't I don't I don't know if you have really a good appreciation of the extra cost on the handling systems in lead fast reactor okay you know that Christian is against so only sodium is good yeah so please please explain yeah no I think I acknowledge your comments most of them so probably many of them can actually go into challenges to be honest but I can briefly talk on few of them so one is on the molten salt reactor so think about how the salt configuration might change depending upon the let's say the operation and the ingress of other compound formation that can happen while it's in while it's in the operation so that challenge I think is known but the possible solution for that that is being considered is to reduce the lifetime of the reactor vessel so if you can reduce that lifetime to a point where not major modifications have happened into the molten salt itself then probably you are still in the zone of unknown but you can still operate safely now how this will impact the economics is a different discussion so maybe it will affect a lot maybe it will not affect a lot so this is something that is being considered in the industry and it's known now for lead I mean I'm sure you know more about queens than I do that's a fact I think at least from the perspective of decommissioning let's say lead could and this could be debatable lead could provide better possibilities than sodium could fast reactor so this is probably I will say with the sense of a bit of a doubt as well but other than that talking about how the economics might improve because there might be more requirement for handling this is something I'm not sure I can say with any kind of certainty because till it happens or till at least some designs are at higher level of development we will never know I mean most of designs are still at the stage of core designing the plant designing as I was not able to find any of the reference where actually the plant designing has happened so probably till that stage happens will be in a very difficult situation to answer that question and that's what the comments are acknowledged very nicely I think thank you for adding that okay thank you just to add about the lead also I'm not against lead or not pro lead I'm pro everything whatever whatever the nuclear technologies are to develop but what the designers of the lead reactor we say reactor of natural safety as I say since lead never boils which is probably not very true so but theoretically reaching the temperature of the fuel could be okay but let's say we assume that lead doesn't boil if it doesn't boil there is no reason for this criticality accident and there is no reason for the core meltdown of course if you melt the core and in this case for example contour roads if the structure still is molten and destroyed contour roads will do what they will float up or something so before see boron carbide will be out of the core it probably has criticality but the main reason they say simply there is no negative positive sorry void reactivity effect in that lead reactor and there is no reason could you imagine any ULOF for example calculations of the ULOF shows that with natural circulation would be enough to remove decay heat okay decay heat and also reactor will be shut down automatically without contour roads but depends on the position of course what kind of compaction due to the gravity I mean under seismic conditions could be lead to the criticality or what else or unprotected trip of power like sudden insertion of the contour roads would be also the reason but basically there is no physical reason why it should core should melt and to do of course we don't have the problem is that we don't have experience with sodium we have long experience with lead we had with lead with wood also partly successful I would say and we had accidents with plasma reactors okay we don't know exactly the reasons but can imagine that what happens so the main problem is that there are no experience but then now we are gaining the experience there are many especially here in Italy there are many researchers who are doing with lead jointly with Romania during this Alfred already site is selected in Romania unfortunately in Italy nuclear power is prohibited by referendum but the researchers are walking yeah any other questions to Chirayu thank you for a lighting lecture so I wanted to know about the depressurization accident and any strategy to prevent that in which reactor in general it is the main problem for supercritical water like I can give a general answer as well so what happens is like so why it happens is like you have to remove the heat in this and the helium is a light element and you need high pumping power to go through it the what happens is like if we lose the pressure we lose also the capability to pump a lot of helium through it so that means we need to have a way how we can remove the heat in a passive way through that now what we saw in the high temperature gas cool reactors which have this narrow core is like to remove it through conduction and convection so in case this happens there is nothing or the helium circuit is also broken there is loss of flow accident you can do it through conduction and convection that's one way to do it now for gas cool fast reactors the possibility will be to do it through a decay heat removal mechanism which could be active or passive so we need to have a certain mechanism which needs to work in order to remove this heat now if it's active we need to have redundancy or things like that when we have also in case of for example pressurized water reactor we have this emergency core cooling systems which have several tanks and several level of redundancy so this can be done in that case this part thank you if you talk about supercritical water reactor I mean it's water cooled so we can still probably maintain some level of natural circulation or heat removal through this tall core if required any other questions or comments maybe from from online audience try do you see the questions in the chat I saw but for the ESFR parameters so many people doubt that is interested in ESFR design which you presented probably right I can refer you to some papers which are published I mean and then Professor Mikit Yuk is probably the best known source for ESFR I will refer you to that I mean I'll probably I mean even if you Google like ESFR you will find a lot of papers there are several designs it's hypothetical reactor conceptual conceptual but there are several designs and there are several projects what we do so Chirai will send okay if not more no more questions then again Shri Batra thank you very much for your lecture and now we have a coffee break and then we discuss group activities this will be session just to discuss group activities to see to answer your questions and then Chirai you are attending I will be here if you are here then probably I would like to skip I'd skip my lunch so I'll go and have a lunch are you trying your flight you want to skip your flight or I want to check now okay okay so in any case on the way welcome to attend sure okay coffee break now