Creating sustainable energy security Dr Trevor Dudley, CEO of Mozweli (Pty) Ltd, unpacks the financial and logistical benefits of deploying pebble small modular nuclear reactors, using the latest, safest technology. What is generation four technology? The main aspect in nuclear is always safety. Generation four is the highest league where the pebble technology is classified as inherently safe. You do not need passive and active safety systems because of the fuel technology that is used. The fuel technology has four inherent safety barriers. The pebble fuel has a low power density of 5MW/dm3, compared to PWR fuel which has a fuel density of 20MW/dm3. The pebble coefficient of reactivity is negative. This implies that the fission process requires continuous activation, and if not activated continuously, the fission process decay will decrease and die out. It has a negative reactivity coefficient and that's a big plus because if you do have a human or mechanical mishap, the plant (through the chemical fission process) goes to sleep, it shuts down by itself. There are safety mechanisms just for that rare occasion of an accident taking place. It has been demonstrated on a live plant that when severe cases of helium coolant in the reactor are removed, if the temperature of the pebbles goes above or near to 1 600, it suffocates the chemical fission process. The majority of over the 400 nuclear reactors in the world are pressurised water reactor types; these are classified as generation two. With them, if the fission process does get out of hand, for example as happened at Chernobyl, then you need an active safety mechanism. You insert the control rods and if things continue, you need other systems to be in place. After Chernobyl and the Three Mile Island challenges, the nuclear industry has learnt a lot and the international nuclear regulator, the International Atomic Energy Agency (IAEA) in Vienna, has now put out new safety regulations. For example, at Fukushima when they had that tsunami, all the safety aspects were adhered to during the design of the power plants at Fukushima Daiichi, but when that tsunami came a 20m wave crashed into the nuclear power plant and knocked out the electrical system and the system which drives the pumps. So they had challenges. There we see that the active mechanisms were there as designed. In the future design of power plants, most nuclear vendors and designers are talking about generation three-and-a-half. It's still a challenge, you can have a meltdown, but there are many safety systems. With a passive safety system like those on the pressurised water reactors, they are saying keep a swimming pool of water on top of the reactor building, so that you can release water onto the building to cool it down. With Mozweli pebble technology generation four, you don't need all those active or passive safety systems because our safety is in the pebble technology. The fuel that we use has its own four barriers of safety and that is a big plus. Why is the term “pebble” used? The fuel that we are using actually looks like tennis balls, spherical, or like a cricket ball. It's 60 millimeters in diameter but in the past, the field looked like pebbles on a riverbed. Pebble is a misnomer. 14 | www.opportunityonline.co.za
MOZWELI _________________ The technology is sound, the proof of concept is working and the team is ready. ________________ What are the other advantages of pebble technology? An advantage of pebble Small Modular reactors (SMRs) is that the power output is 100 megawatts, compared to the large conventional power plants, which is about 3 200MWe. You can construct, manufacture and get to market in eight years. The Chinese have done that. They started in 2010 and they commissioned in 2018. We take that parameter from the Chinese. A normal pressurised water reactor takes 20 to 25 years in design and construction. With the PSMR your cost is reduced to US0- million, your manufacturing is much more convenient and you get to market as quickly as possible. Pebble nuclear reactors also don't have to shut down for refuelling. It’s an online process that allows you to keep generating power while you add and remove fuel. For example Koeberg needs to shut down for a month or two to reshuffle the fuel. We don't have that problem. How is The PSMR a mitigator of climate change? When the power plant is running, for every megawatt of electricity produced there is zero carbon dioxide, zero sulphur dioxide and zero nitrous oxide. That's why we say it mitigates climate change. A fossil power plant that produces electricity using coal, fossils, oil or gas is taxed for every megawatt ton of carbon dioxide produced. Every megawatt of energy produced by nuclear power is actually a positive, which you can sell to the airways who are producing carbon dioxide. Does pebble technology store nuclear waste differently? The pebbles are totally different to a conventional nuclear power plant. For pressurised water reactors, the high-density radiation is plutonium and that has to be kept in a pool of deuterium water. It has to be kept on site for a number of years until the high level of radiation is reduced and then it can be moved to a deep fault in the earth somewhere. You are taking uranium oxide out of the earth, you use it, and you put it back in the earth. Some of the anti-nuclear people don't want you to put it back because it's radioactive. The storage of high-level nuclear waste is highly regulated. Every gram is accounted for by the IAEA. In pebble technology, we have dry storage. We take the pebbles out of the reactor once we have used the energy, store it below the plant for 40 years and we monitor it. It's a much safer option and we are doing research on recycling those pebbles. About seven grams of uranium is used; 90% of the pebble is graphite. Why is the PSMR particularly relevant in the African context? Our power plant does not depend on a large amount of water for cooling. It does not depend on the position of the power plant. Pressurised water reactors need the ocean or a river to cool down the process. We can put the power plant where the power is needed. Take for example a mining house. We can place a Mozweli power plant of 100MWe where they are mining. The mine has a life of about 30 years which ties in with the life of the Mozweli power plant, which is 40 years. We are saying to African countries, here’s a Mozweli power plant as big as a soccer field, put it where you need the energy, 100MWe for your mines or for your people and off you go. You don't need a lot of water and long transmission lines. That makes economic sense in Africa. The PSMR is ideally suited to place your power plant where you need the power. The time of long transmission lines has expired. Can you create reactors smaller than 100MWe? We market a 100MWe of nominal output power. The installed capacity is 144MWe. Four reactors are based on 25MWe each and that is your N minus-three redundancy. If one reactor and its turbine is in outage for maintenance or servicing, your three remaining reactors will guarantee you a 100MWe nominal output power for 40 years is the principle. The Canadians have enquired about a 25MWe plant and we said we can look into that. The only shortcoming here is that the price of a 25MWe and the price of a 100MWe is the same, US0-million. This is because the regulatory process Biography Dr Trevor Dudley is the founder, owner and appointed managerial director (CEO) of Mozweli (Pty) Ltd and Programme/Project Director for all countries. Dr Dudley is a world-renowned nuclear physicist and large-scale technical project developer with 30 years nuclear experience and 27 years pebble Dr Trevor Dudley, CEO of Mozweli (Pty) Ltd technology experience. Dr Dudley has a PhD in Electrical/Nuclear Engineering from the University of Manchester/Institute of Technology [UMIST/UK] (2004); a Bachelor of Science in Engineering BSc Eng (Hons) in Power Systems/Energy/Management from the University of Cape Town (1996); a Bachelor of Science (Honours) BSc (Hons) in Applied Mathematics from the University of Witwatersrand; and a Bachelor of Science BSc in Nuclear Physics and Chemistry from the University of Botswana (1981). He is a member of the Institute of Directors in Southern Africa (IoDSA), a member of the Engineering Council of South Africa, the South African Council for Natural Scientific Professions and the American Nuclear Society. Mozweli IP belongs to all Mozwelians, as derived from first principles.