 Thank you everybody, we now will restart our workshop with presentation on technical and associated challenges in establishing a viable SMR that will be delivered by Professor Akira Tokuhiro. Akira, please. Yes, let me share my screen. Can you confirm? You can see the first title slide? Yes, we see, but this is not in full screen. Ah, so we have this problem again, so we have to... Okay, you try if still we have a minute or two, if possible, otherwise just go. Like what I do here, I also learn it this week. I start full screen PowerPoint presentation and then it has two windows. Okay, looks now, no. No, okay. First I start this PowerPoint in full screen and it shows the two windows. Then I start share screen from here and select the big window, which is full screen. Ah, I see, okay, so let me try to... So first you start it and then come back with Alt-Tab to this browser window and then share screen. If not okay, you just maybe minimize. No, no. Okay, I just keep, I just start. I hope you can see the title slide. Okay, okay. Okay, I just go, yeah. So, thank you very much, Amira and the organizers and the students. I think you had a very interesting week. I'm sorry I cannot be there in person, but it's a busy time of the year. So I will talk about the technical and some of the related or associated challenges in establishing a viable small modular reactor initiative in the whole world. I think you saw this on Monday. I hope you all just connect with me on LinkedIn. I use LinkedIn quite a bit. I'm happy to see the list of participants, all of you except maybe one or two I know in person. So thank you very much for that. To start, I think you know about this slide. This is one of the most used slides in the nuclear energy world. Generation one to generation four reactors, just some important points. We will, maybe in your career you will reach 2014-2050 when we have to get the net zero carbon SMRs roughly started a lot of progress in about 2010-2011. We are already at 2022, at the end of 2022. Generation four reactors, I think the initial conversation started in about 2000. So this tells you about the nuclear world that doesn't change very much compared to, for example, the software world, which changes quite a bit. So that's just the, and we have about 425 operating reactors. I can tell you now we need, as I said on Monday, in some of the models on how many nuclear power plants, large and small, do we need to counter or combat climate change or get to net zero carbon. We need something like 4,000 more than, or more, so we need 10 times more than what we have now. So for me the question is how can we get to, not to have 430 nuclear power plants, but 4,000 nuclear power plants, large and small, throughout the world in a very short amount of time. So, okay, so let's talk about both small and micromodular reactors. We have them in many places. We have research reactors that are very small or micro, but they don't have energy conversion systems, and they do not generate electricity. There are a few examples, but few is not having 400 or 4,000. Okay, I talked a bit about this on Monday. I hope the slides are advancing. This is the startup financing cycle, commercial sector slide. What has changed since about, well, compared to 1990 or so, 30 years ago? Sorry, Professor, I think the slides are not working as you might be. Okay. If you share the wall screen, instead of the window, you should be able to let us know. My screen? Yeah, instead of the window. So, if you get out of the presentation and the screen sharing and select to share the wall screen, we can see exactly what you are seeing. Okay. Okay, how's this? Do you see the, are my slides changing? Here's a standard PowerPoint window, maybe, if you share entire screen. Entire screen. Maybe the entire screen. Let's just try to make the presentation with a slide or the button. Okay. How's this? Do you see the title slide? No, still not. Ah, this is a problem. It's like you have two windows. One is standard PowerPoint windows for editing and another for presentation. So, we see the standard, not window for presentation because. Stop sharing. Do you see me? Yeah, now you see me. So, okay. I guess one option if you click share screen and I see here entire screen. When you click entire screen, you see everything what is on your screen. Or you have two monitors, I guess. No, I have only today, I reduced, I changed to one. Do you see the slide? Now, if you click this F5 or go to the full screen mode. Okay. How's this now? Still the same PowerPoint. Okay. Do you see this slide, the title slide? Now, we see the first slide, title slide. Yeah. Okay. I will go with this. I hope you can. Yeah. Yeah. Ask for your patience. Okay. So, I switch to my career slide. I hope you will connect to me on LinkedIn. Just, that's what I said. Okay. So, let me jump to this slide, which I hope you see. Evolution. We see evolution of commercial. Yeah. Okay. Yeah. Okay. Okay. So, the evolution is the most used slide. And what I said before was that from generation one to generation four. And then to 2014 and 2050. We have to get the net zero carbon by 2050 or so at the earliest. We have about 425 operating reactors. I can, as I said, how many, how many large and small reactors do we need to get to net zero carbon? And to replace all the power that's electricity, electrical power that's being generated by fossil fuels, coal, especially coal and natural gas and petroleum. We need about 4,000, at least 4,000. So, the question is, can we build, can we increase the number of nuclear power plants throughout the world to 10 times what we have today? It's quite a big challenge for us. Right? In the next 30 years, can we get to more than 1,000 reactors, more than 4,000 reactors is the type of numbers we need for 8 billion people and the electricity demands that we have. Now, remember, what I often think about what is urgent. And is when you have to charge your cell phone, right, that's really an immediate task that you have to do. And that's, where is that electricity coming from? And that has to come from a nuclear power. Okay. Let's talk about small and micromodular reactors. There are some examples of micromodular and small reactors today in research reactors throughout the world. They don't have energy conversion systems and they do not necessarily generate electricity or have distributed heat. Okay. All right. This is slide number six is a startup financing cycle and commercial sector. I talked about this on Monday. What has changed since 1990 compared to Westinghouse and General Electric and Hitachi and other large companies. We have, and certainly in North America and some in Europe, US, Canada, we have a small modular reactor startup companies. And remember, they operate on a different financing cycle. They have to have investments in order to make progress in their engineering and design. And this is the, you have to remember the startup cycle initially when you start up, you are doing everything at your own cost. And then startup people have, you have these four questions, you know, they, they, do they want to have a startup to make, to sell the company, a successful company eventually and then retire young or do they want to do something good for humanity and then undergo some financial hardship because they believe what they are doing is very good. So they're, they're, that's different from a commercial company like General Electric investing, being in the business of nuclear power. So you have to know that difference that the define, essentially the financing cycle and the investment cycle is, is different for startup companies compared to traditional nuclear vendors. Okay, the other thing that's important to know is the technology readiness level one through nine. This is in Wikipedia. I would ask you to look at Wikipedia technology readiness level. This is important because you may have a very good idea, but it may be you're at the technology readiness level number one. And in order to get the technology readiness level eight or nine takes quite a bit of time or even seven system prototype demonstration and operational environment is really a large, large scale engineering demonstration in a near commercial type environment. So technology, technology readiness level number five, for example, technology validated in a relevant environment, maybe a test facility. All those things take quite a bit of time. So you have to think about the technology readiness level. Okay. And I just have the example of a picture of the airline industry. They have the same kinds of constraints. Okay. Here's slide number eight is just another slide on the technology readiness level. This is from Wikipedia and then again technology level one to nine. Okay. Now, the other thing about startups is that with small modular actors, especially in North America and some little bit a few companies in Europe, they live on the idea. So that idea is intellectual property or proprietary. And you see the black box is essentially that it's a it's an SMR, but you don't know many of the details. So you have to keep that in mind. The regulator may know some details, but then to the public that some of the details of the design are protected. And it's hard to know what's exactly inside. So that can be a problem for the public to access in terms of the information. Okay. Now, let's look at beyond the investment slide number 11. Remember that nuclear engineering and the scales of engineering are one of the most challenging in engineering design because the length, energy, number, distribution, information and time. If you just look at the first letters, L E N D I T I call lend it or have some of the biggest and the widest scales, like the energies may go from 10 to the minus three MEV all the way to 10 to the minus 10 to 10 to the plus seven MEV. And the time may go from from femto seconds, 10 to the minus 15 seconds to thousands of years. So you're doing engineering and design and over this very wide range of scales. So this is why nuclear engineering is interesting, but it's also a very big challenge. Okay. All right. The other thing that's difficult with traditional nuclear reactor engineering and codes is that because it started in the late sixties and early seventies, even earlier, many of the computer codes are still in the Fortran structured programming language. And we have changed since that time. And we don't really teach at least in the US and Canada. We don't really teach Fortran. So you have to learn that on your own. Although as an older person, I learned Fortran at the university. Now, you know, people are learning HTML and Java and Python and so forth. And then Fortran is some of the codes are unfortunately still in Fortran version. And you have to learn Fortran to make sense or to work with Fortran based codes. Now what else has changed is we have new software like GitHub or sites or platforms like Slack and GitHub and some of the fortunately some of the coding is has been done so many times it's shared. So GitHub is you don't have to write the original code for a certain routine because it may be already available on Slack or GitHub or some of these other newer platforms. Okay. And then the other problem is that some of the codes like MCMP or Melcore and Relop even are controlled and they're not easily available for everybody in the world. And some of the control is coming out to the Radiation Safety Information Computational Center, RSICC out of Oak Ridge National Labs. And then you might not be able to get the latest version but the maybe an older version of a code like Relop. Okay. Okay. Slide 13. Yeah. Because I just want to say that because compared to a large water reactor or larger reactor design because of the smaller scale of small modular reactor in the simplicity in design, it's much more possible to integrate and model and simulate much more than larger large water reactors. The analysis is should run faster in principle. And we should be able to look at more details of the design. Does somebody have a microphone on please turn that off. Okay. Slide 14. Again, the technical needs in SMR safety and design I use this term safety and design for to capture the design and engineering. You have the regulatory body and licensing strategy to get your design through the regulator. You have to certainly have a probabilistic safety assessment of the design or risk assessment of the design. You certainly need system analysis of design. You need accident analysis of the design really to get to get the potential source term. What is the magnitude of the source term that can go off site from the reactor through dispersion analysis and then back to the current design philosophy and design approach. So you go in a circular iteratory process to do the design. Now, when I say the SMR is designed as simple enough, one example is that you're deciding between, for example, a safety relief valve. You may only have three safety relief valves and you may be thinking about adding a fourth safety relief valve relief valve. So the difference between three and four safety relief valves in typically integrated PWR SMR design can change the accident scenario or the accident sequence. So because it's smaller and you have much fewer components, whether you have three valves or four valves safety relief valves can make a large impact on the behavior under accident conditions. So that's why the details are important on the accident, especially on the accident revolution or the time dependent sequence of events in a small modular reactor. So, project-wise, you may not be able to freeze the design to say, okay, no more changes to design. This is the final design for our SMR before we submit it to the regulator. In project management terms, you may be at 80% completion, but you may still be deciding between a design with three safety relief valves versus design with four relief valves. But you have to come to a point where you 85% project management completion percentage, you say, okay, no more changes. We will do, we decided on four safety relief valves, and we have to go with that design and no more changes, design changes, for example. All right, again, the same six aspects of SMR design. And you have to also remember from this slide 15 aspects and specialization that in some of the SMR designs, you're saying that the design basis accidents in a traditional sense for large water reactors are zero, reduced to zero or not applicable, and that you cannot have, because of the goodness or the greatness of the design, that you cannot have a beyond design basis accident. All right, and you may have, as a result, a core damage frequency, CDF, perhaps smaller than 10 to the minus eight, or smaller. And you have to have an incredibly small event or a sequence of things that can happen, like, for example, the Fukushima. You have a very large earthquake and then it's tsunami. The earthquake probability may be small, the tsunami probability may be small, but it can happen. So you have to think of, let's say, a small break loco, large loss of coolant accident. That itself may be small, but you may have another event that can happen. So you may have, overall, a core damage frequency of 10 to the minus eight or 10 to the minus 10, something very small. And you have to consider, even though it's not possible from your design, you have to think of that as a possibility to the regulator. Or, and the regulator may say that we don't believe that the probability can be 10 to the minus 10. We cannot, we don't have a position on something so small, but we are convinced that it, for your design, that it's incredibly small and it's not likely to happen. Now, Insect 10 is, look on Wikipedia or on Google. Insect 10 is a design philosophy that's very important. There are five levels. You may make the design to meet all five levels that you cannot have level one, level two, level three. But it's also possible to design to say your design is made so that you, if you are at level one, the design is, makes it very difficult to get to level two. Right. So, again, I'll say if you are at level one, under the Insect 10, five levels, the design is such that it's very difficult to go from level one to level two. So, that's another design approach that you can take. And overall, what you want to do is that you don't want to introduce human intervention because human beings can, are typically human beings, human operators under stress can make mistakes. And you don't want human intervention in order to, in order to prevent mistakes made by human operators. Right. So, that's something that's, that's important to remember in the overall design process as well. And then if you have a small source term and a dispersion is very limited, then you can have a small emergency planning zone, EPZ. And that's typical for a small modular reactor. Okay. Slide 16, just to say that just some features of the triple crown, what they call a triple crown of, at least in the west of Hylobal Objectives and Functions of the design. No AC or DC power necessary at the plant. The plant is, is often said the plant can operate on, on, on island mode, meaning it can operate on its own electrical power and not require power from the grid because from the earthquake or tsunami, the external grid may be out. You may not be able to, to have electrical power coming back into the nuclear power plant so that the power plant itself can work on island mode. So, so those are some of the, the, the, these are some of the questions that are asked to have a good design in the SMR. Okay. All right. So I talked a little bit slide 17, I talked about passive safety systems a little bit. I'll talk a little bit more about that. I talked, certainly talk about insect 10 here are the five levels. And with respect to talk more and more about passive safety systems, PSS. Here are the five levels. As I said, in the SMR space, you really want to only work in levels of defense and depth levels one, two and three. And because four and five are already severe accident conditions and mitigating severe accident conditions. So you want to make the design good enough and without human intervention needs so that you operate even under the worst conditions at level of defense and depth number three. And you make the design so that if you are one, if you have abnormal operations or failures, it's difficult to get to level two. Okay. Here's the, here's some different levels that defense and depth levels from insect 10 on the very left. Some target frequencies in terms of probabilities per year. Some attributes there. And then you have what's called PRA probabilistic risk assessment levels one, two and three. These are approximate correspondences between defense and depth and PRA and the current regulatory requirements. This is not a absolute correspondence, but these are some interpreted correspondences and there's some differences that still need to be resolved. And you see that the probabilities that are listed in the second column from the left are very small, level four and level five, let's say are 10 to the minus 10, 10 to the minus 12. So very, very small probabilities and there may be some differences between you, the designer and the regulator who takes a position if they take a position on the probability. So that has to be discussed early in the design process. Okay. Here are some more into the technical details. Here I've taken the example of the ESBWR and the PANDA facility that was at the Paul Scherrer Institute in Europe. Some SMR technology, some design simplifications compared to the evolutionary simplified boiling water reactor ESBWR. And now that design is 30 years later has become, for example, the BWRX300 looks very similar. And you have this passive safety system for this BWRX300, for example. So, yeah, so I'll talk a little bit about that. Slide 20. Yeah, so linking the three elements, probabilistic risk analysis or probabilistic safety analysis, PSA or PRA, system analysis and excellent analysis. And then the reactor design and the lessons learned maybe over 30 years. In the case of, for example, for General Electric, all the things that eliminate some of the higher level design objectives like human intervention, the triple crown, defense and depth. You really have to integrate and have activities and integrate activities and reactor design, safety and that system analysis, excellent analysis and PRA, PSA. Okay. Now, slide 21, time evolution of events, including accidents and PSS. What we have used in the industry is what I call or some call classic PRA, classic probabilistic safety assessment or risk assessment. And these are discrete models. And there's a software for making the PRA, PSA model. And as you know from your education probably from inventories and fault trees. These are classic PRA is our discrete events in time and they happen in an idealized world automatically. But there is another dynamic probabilistic risk assessment or PSA dynamic, which includes explicitly includes time as a variable. And so you know much more with dynamic PRA, the evolution of the of events that happen with the system that you design. And that's important. And you can do that with SMRs because the system is simpler. The overall system is simpler so that it's amenable to computational models and simulation. Although for even for large reactors, software models and simulations are possible, but you need more computing resources. So for the design engineer, for the SMR for design engineer, you may be able to do dynamic PRA analysis on your laptop, as opposed to having a computing cluster on high performance computer. So, slide 22 is just a very busy slide, but in the US there's a documentation called Code for Federal Regulation CFR. CFR 50 Appendix A is a thing called a general design criteria, GDC, and it has a list of about 50 design criteria for how objectives that have to be met when designing a nuclear power plant. Okay, so this is one regulatory approach. The US NRC takes what we call a prescriptive approach or a checklist approach. And if you have to meet all these criteria, if you design a reactor, other regulators may have a different viewpoint. But if you consider the US one, it's useful because when you think about the completeness of your design, an SMR in this case, or an micromodular reactor, then you can go to criterion 25, for example, and make sure that you have taken this criterion 25, for example, into consideration. So, if you look, this is one for protection systems, protection system requirements for reactivity control malfunctions. So, these are design criterion, for example, that does talk about the fuel design limit, not to exceed for any single malfunction of the reactor reactivity control system, such as accidental withdrawal or rod ejection or rod dropout, control rod dropout. So, you have to design the system and the reactor so that even with a rod accident, a control rod withdrawal or ejection accident, that you still have some reactivity control. So, it's a checklist in a sense for the goodness in design. Okay, slide 23, safety SMR design features that challenge the conventional safety analysis. These are just examples of generic eliminated scenarios in your small modular reactor. You may design the reactor so that you don't have large piping connections in the design, only at the very top, for example, and nothing at the bottom. And it may be impossible to have a large break loss of coolant accident because you don't have any penetrations into the pressure vessel, for example, and that you do by introducing an integrated reactor cooling system feature. So, you see in some designs already that you don't have any penetrations at the bottom of the pressure vessel or even the containment so that it's hard to have any loss of coolant accident. All right, so slide 24 is just an overall schematic of the safety assessment. The classical approach is the PRA, PSA, and then the deterministic safety analysis or safety assessment. And the integrated approach is that you combine these two. And in addition, that coupled to the design, so you have to, as I said before, you might have to think about in an integrated approach, what happens to the PSA and the safety assessment and the accident analysis when you have three examples, is an example of three safety relief valves versus four safety relief valves. All right, so here's a detail of passive safety systems, and you have at least at this moment four different types. And this is what I was, this is an example of what I was saying, that the evolution, the time dependent evolution of the accident can be dependent on the type of passive, here in this case, passive residual safety system that you may use for your design. And they are a little bit different for each type of SMR design. Okay, so here are four, and here are in graphic form, passive residual heat removal system. I'll go back, that's number one. And even with number one, you have three different types, and you can see that type three is very different than type one or two. And even type one or two is actually very, very slightly different. And you have to really look in detail to see if the difference between type one and two. But one thing to remember is that in passive residual heat removal systems or passive designs, you don't have a pump because you eliminate the pump to have, and for circulation, you eliminate your option to have for circulation without a pump, and you operate the reactor on natural circulation. And natural circulation is at a much lower velocity or mass flow rate than for circulation, but maybe the safety system is, and the normal operation is okay, acceptable on natural circulation. All right, slide 27 is potential advantages of implementing a passive safety system in an IPWR type SMR, some design characteristics. For example, lower core power capacity is facilitated by less decay heat to be removed or smaller magnitude of decay heat removal. So if you have a small module reactor with lower thermal output, of course you're going to have a decay heat to be removed that's smaller. And that you may be limiting the thermal output capacity of your small module reactor so that it can be cooled. Ultimately, if you go to a micro module reactor, the ultimate heat sink is really air. So, and that's not really much different than having a water cooled automobile engine design or air cooled, like the Volkswagen Beetle, is an air cooled, some of the smaller, the original 1100 cc cubic centimeter design is an air cooled design, right. So it's only when they increase the capacity to 1300, 1.3 liters, then they have to use, beyond that point, you have to use some liquid cooling. So if you have a lower core power capacity, for example, you may, you have less decay heat to be removed, for example. So here's a slide 28 is just a detail, much more detail on the evaluation metrics for our PSS passive safety system among I integrated pressurized water reactor designs. So these are PSS types of PSS systems and you look at the cooling time, redundancy and diversity, and for R and D and R is for the redundancy, D is for diversity. So you can see some differences and the evaluation metrics are for a paper by Williams, but you, what this really says is that when do you use your passive safety systems and are, are you using what type of PSS passive safety system design are you using. And that can really impact the time evolution of your accident sequence. So the, getting to the end here, the, the, the importance about this, the whole thing is that you're going to have for SMR design one through nine, for example, you're going to have some rank, if you had a ranking. Some of them are going to be better than others or best or good or expected or minimum, depending on your passive safety system design. Okay, so this is, this is just to suggest that not all SMRs are alike. And, and the passive safety system design, being different in each type of SMR, some are going to perform in a better manner than others. And you may not, the regulator needs to know this, because the designs are different, the public may not know it because that the detail information is hard to access. Okay, just to give you some references, I mentioned the paper by Williams. That is really good paper in terms of the defense and depth metrics and new reactive designs. I would recommend that as for reading, just a picture of two of my former master students, you and me and Chiru Zelyang from India. And then I just want to say in slide 232 about low, medium and high in terms of digital twins. Digital twins are needed, but in terms of engineering and design, if you need high performance computing or cluster based computing, it may not be practical. And you may be talking about details that really do not matter, but may matter because of the smaller when the reactor is smaller in design, your safety margins also may be smaller. And you need to check if your safety margins and uncertainties in the modeling and simulations are smaller and to make sure that they are not critical factors in the safety of the design. I talked about on Monday about complexity overall, if you take a systems level view, the complexity, if you think of the number of variables and parameters, then you have a complex process. You often use heuristics to optimize the entire system, whether technical or non technical. And I talked a little bit about Pareto and these are available in Wikipedia, so please look at complex system analysis and the parameters that I introduced or the heuristics that I introduced are the blended parameters. I talked about this in the very beginning. For systems, for thermodynamic systems, pressure, temperature, mass flow rate, valve position and liquid level are very important. And during accident analysis, system state resource and response are applicable. You have to know the state of the system. You have to know what resources you have that may be engineered or non engineered. You may have an emergency diesel generator. You may have a fire truck as a resource and you may be able to use that in the responding to the accident event that you may have. Okay, in summary, slide 39. These are not in any order or priority. You may have, we have today, some 80 current SMR designs. And I think a smaller number will get to the end. Getting to the end means for me, finishing construction, starting the operation and connecting to the grid. You pouring concrete at a site is the beginning, but pouring concrete does not guarantee that the plant is construction will be finished. The operational testing, the core first criticality, getting up to 100% power connecting to the grid is really the most important. So, some things that I worry about, do you have enough of a workforce? Do you have how many SMRs can be constructed simultaneously in the world is important? Do you have enough funding? You make sure that in order to finish the construction that you have a sufficient number of sufficient funding. Is there regulatory approval? Is there support in Russia and China, Argentina and some other countries? You have a different financing model as well. So that's important to remember. So, with that, I'll take some questions. Thank you very much for your time and your attention. Thank you very much, Akira. Now we have several questions. Let's start from Chad. And one question from Ibrahim Ballaradi-Mansir. My question is, does the SMR design is robust under the loss of power accident since there is no human intervention during decay heat removal? Yeah, so that's a good question. What I meant is that you have to rely on passive safety system design. It essentially means natural circulation. And the operator, and those happen automatically in that you are able to remove decay heat. And assuming that you have a natural shutdown system, so the reactor is in shutdown, but you have to still remove the decay heat. And that requires no judgment or intervention by the operator. It happens and that requirement may be within the first 24 hours, first 72 hours, maybe within the first week. It depends on the regulatory requirement and expectation. And that can impact the SMR design. So I think you have to think of that upfront on whether the regulatory position is that you have no human intervention within the first 24 hours or 48 hours or 72 hours or one week. So hopefully that's a partial question answered to the question. Thank you. Thank you. We have a question from our audience. Thank you, Professor Tokoiro. I'm Seydali Hussaini. I have a question about dynamic PSA. One of your slides says that dynamic PSA is a potential for using in small modular reactors. But NRC not accepted the dynamic PSA or dynamic PRA as a requirement. There isn't no document for dynamic PRA, even for PWRs or LWRs. So how we can make a practical way for SMR safety assessment based on a dynamic PRA? Yeah, so I think I thank you for that question. It's a very good question. So the regulatory requirement is that you have a classic PRA. And that satisfies the regulatory requirement. The research, if you want as a vendor, want to know more details and time evolution of the reactor. You may want to have an internal dynamic PRA analysis to keep as part of your knowledge base. You're right. It does not mean there's not a regulatory requirement for dynamic PRA. But you may want to know as a company and use dynamic PRA. For example, in Japan, even classic PRA is not a regulatory requirement. But the utility owner and operator, of course, has a classic PRA model and they do simulations to know much more detail about what can happen and how it can happen. And this is the same case for dynamic PRA. So is that partially in answer for your good question? Yeah, I agree with you to going toward the IDPSA, dynamic PRA, best estimate tools in licensing process. But there are many restrictions, regulatory restrictions. But if both related to the SNL modular reactor, if we should come back to the conservative strategies, I think it's a full of drawbacks and rollbacks for safety. And thank you for your specific answer. Thank you so much. And I have another question. Later, please. You will have a chance if we have time, okay? Now let's accept another question from, I see that also Alessio Luwara has two, even three questions in one. I just will reformulate first question. Why do you rely on this outdated stupid Fortran language? Why not to develop a new software suits which more updated programming paradigms to be used by all different, to be used by all different proposing SMR microreactor vendors during design phases and even beyond? Yeah, so I'm glad for that comment. It is a very silly situation. And I don't know what all the software tools that all the AT SMR vendors are using. But some of them, I am assuming that some of them are using free or cost free old SMR or old reactor system analysis codes or PSA codes and they might be even written in Fortran language and maybe Fortran 2000. Maybe they have been converted from Fortran 4, which is of old version, to Fortran 2000. But it's still an old structured language and it takes some time. You need to hire a software engineer to convert. And that's really not productive time to convert that Fortran 2000 to some other modern language. And this is where the change comes. You may make that code available on GitHub or Slack or some shared global site to facilitate the water usage of software tools for the entire community. And on that, I just want to answer one other question. The role of the IAEA is very important in some of these new methods like dynamic PRA because they are able to get all the stakeholders together to have a discussion about some of these newer methods and standards and expectations of newer methods. And it does take time. It may take 10 years before we have a consensus as a community, a global community in saying that we should share, we should get away from Fortran-based nuclear reactor design analysis or use of dynamic PRA versus classical PRA. So just to give you a short answer, I hope that's the case. I hope I see that. I see also Adrian answering in the chat. Adrian, could you just add to this? Yeah, sorry, I couldn't resist answering in the chat. I love Fortran because it's such a nice language. And the fact is just that a lot of old code is written in Fortran and the legacy code, as we call it, and not just in the nuclear industry but also in the automotive industry in lots of places. They have lots of code, tens, hundreds of thousands of lines of code in Fortran, but it is hopelessly outdated. And therefore universities don't teach it anymore and new codes are written in C or C++. Now, one point that is very important though is that there has to be a standard and Fortran has a standard. If you have a Fortran statement that adds two numbers, then the standard says what the result should be. In Python it used to be a long time that well, it depends on the version of Python that you have, whether the division gives you this answer or that answer. That's not something you can use when you build a nuclear reactor. So that's why Fortran is still around a lot and I personally love it and I would be very happy to teach it. So back to you. Thank you. Thank you. Now, darling, your second question to Akira. Thank you. My second question about the passive safety system, the other part of your presentation. The passive safety system from the reliability point data is despite of the many advantage is a challenging issue. You recommended about the advantage. So the dynamic PSA or PRA is potentially challenging for SMR with the passive safety systems. Combine the passive safety system with the dynamic PRA. How we can do in this situation in your opinion? Thank you. Yeah, so that's a very good question. So I often worry about this as well. For example, I'll give you an example. If you have natural circulation and have much lower cooling flow rate velocities, for example, as a metric, and you need the reactivity control and you're going to use boric acid injection, the question is where do you add the reactivity controls in the core? Where do you add the boric acid? If you add it beneath the core, then you have a penetration into the pressure vessel, for example, and you could have a small break loco. You introduce a small break loco. But it's the most effective and the shortest time frame to have reactivity control. If you do not want to have any small break loco possibility, you introduce the boric acid midway or above the core or further away from the core, and then you have to wait for the boric acid to traverse all the way down into the bottom of the direct pressure vessel and then into the core. And there's a lot of uncertainty in that calculation. So you have to actually look at both in terms of dynamic PRAs, PSA, and compare it even to classical PSA and account for the uncertainty because you have much longer time scales for circulation and eventual reactivity control. So you have some design optimization process and you have to look at both classical PRA and dynamic PRA and you have to look at seriously in detail the uncertainty associated with that. And that's why, this is the point I make, the importance of dynamic PRA and the importance of the optimization in the trade-offs that you make in this case boric acid injection as a secondary reactivity control as a consideration. So these are kind of research questions and maybe for the SMR vendor, they want to finish the design so they don't have to know that this is an issue but this is a research question to be explored maybe at the university or at a research institute. So hopefully I gave you a part of an answer to your good question. Okay, thank you. I also have a question. Just please clarify it. Let's say we want to replace instead of one big reactor, we need to generate the same electricity. We need 10 SMRs, let's say, or 15 SMRs. From the point of view of the probability of severe accidents, you also have to reduce the probability in order of magnitude. And of course you can say that the source term is smaller but for the public support or let's say acceptance, if you have any accident of the big power plant, small power plant, result will be the same for the nuclear industry. Could you explain how to do it? Yeah, so that's a very good question and you're right. There is a difference certainly in the non-technical perception of risk versus benefit of whether you have one large plant or 10 to 15 small module reactors. It depends on, I guess, on the location, right? It's because you're dealing with... Part of the answer is that you're dealing with the public acceptance of a nuclear power plant. And, you know, we have... I'm in Toronto area. We have a pickering generation station that's just outside of Toronto. And you can see the plant from the freeway. And that one plant generation site is probably objectionable if you are very anti-nuclear because it's almost within the city, right? But if you go to a remote location like a mining site, you can have a large reactor or a small reactor and then there's hardly anybody there. So I think the public perception is one issue. The other issue is earthquakes from the Fukushima Daiichi accident. Earthquakes are the size of the wave or the tremor of the earth is much larger than a large plant or a small plant. So you do have this multi-unit or multiple SMR model that you have to convince the regulator that it's safe, whether you have 10 to 15 small module reactors, like you said, to replace one large plant that you may have. So I think one of my concerns is the scale of what is the probability of a large earthquake. But we have to remember Fukushima that the plant shut down as designed. And then the problem was that you had the loss of off-site power to the plant and in addition, you had this historically large tsunami. And unfortunately you had emergency diesel generators that were in the basement of the site and were flooded and became unavailable. There was one emergency diesel generator at Fukushima Daiichi that was above ground and was operating for units 5 and 6. So that is a good design to be above the ground and inward, not right on the coast because Fukushima Daiichi plant is right on the Pacific Ocean, some of the auxiliary and emergency systems were behind the reactor building as it should be. So partial answer to your good question. Thank you. Thank you still. I think the main problem here, even like you noticed at Fukushima, Fukushima happens in Daiichi in Japan. The most influence on the public was in Germany. Germany decided to completely shut down all their reactors. It does not depend where a small reactor or a big reactor, a remote area or not. It depends on this general understanding of the public, of the situation. Okay, we should go. Thank you very much, Akira. Yeah, thank you. Again, Professor Takuhira, thank you for joining us. Now I would like to ask Adrian, Professor Bozo.