The Uncertain Future of Nuclear Power
Over the past 5 decades nuclear power has prevented the release of 50 gigatonnes of carbon dioxide. That’s equivalent to 2 years of total global energy generation related emissions. [REF][1] Nuclear Power is the most powerful tool at our disposal to stop human driven climate change in its tracks, yet powerful industrial countries like Germany have turned their back on this technology. Rapidly deactivating power plants prematurely.
Nuclear power, despite its clear climate change fighting potential, carries inherent risks that have hampered political will to invest in the technology. In order to thrive and help our planet overcome its greatest challenge, nuclear Power needs to evolve. This is the Future of Nuclear power.
We can’t begin to address the solutions of the future, without addressing the failures of the past. Many of the most notorious nuclear meltdowns were caused by errors in coolant systems. Take the three-mile island partial meltdown incident of 1979. The incident began with a mechanical failure in the plant's cooling system. It all started when the steam generator stopped receiving water due to a faulty clogged filter.
The loss of water meant that the reactor's energy didn't have anywhere to go, raising the temperature of the reactor. As the pressure rose due to water being boiled, a relief valve opened. [2][REF] A valve designed to only open for 10 seconds, but another fault resulted in the valve staying open. Allowing the precious coolant inside the reactor to escape. Pushing temperatures even higher.
As the core temperature continued to rise, the reactor operators received conflicting information from the control room. The emergency water system that should have provided extra water to the cores was blocked. Two days earlier, the plant was closed due to maintenance, and the valves for the emergency coolant were closed.
Unfortunately, they were not reopened when the reactor was restarted. The operator should have noticed that these valves were closed but for reasons unknown, he didn't see the warning lights in his panel. One leading theory is that his stomach blocked his view of the control panel. Even then, The NRC, the regulatory body governing nuclear safety, Had a rule that if the emergency coolant valves were closed, the reactor must be shut down. The Situation at Three Mile Island was in clear violation of those rules.
While the meltdown was triggered by a mechanical failure, the situation was worsened by human error. The Three Mile Island incident serves as a reminder of the critical importance of both robust mechanical safety systems and foolproof controls in nuclear power plants. It highlights the need for attention to detail in design, where even minor aspects like the positioning of alarms on control panels can have far-reaching consequences, potentially leading to catastrophic meltdowns. To prevent such incidents, future nuclear power plant designs must proactively address these issues. When the consequences of human error are nuclear meltdowns, there is no room for human error.
[REF][3] In Fukushima, an earthquake and its resulting tsunami knocked out the plant's cooling systems. The cooling systems in Fukushima depended on a separate energy source. The pumps that were needed to cool the reactors lost power, resulting in a catastrophic meltdown. The plant did have a backup system, which also failed.
This need for external power to cool the reactors was a key disadvantage of the design. Fukushima also highlighted a weakness of current nuclear reactors, the use of water as a coolant. Liquid water is a great conductor of heat and serves as a fantastic cooling agent.
However, when control is lost this water can lead to a high-pressure steam explosion, spreading radioactive materials across vast distances. For this reason, many new reactor designs seek to incorporate passive cooling systems, which require no external power source, and aim to replace water with safer cooling mediums. Before discussing these future designs, there is another large problem facing Nuclear Energy.
Its waste. Light-water reactors operate in what is called an open fuel cycle. In this cycle, The uranium gets mined, processed, enriched, used, and then stored. Leaving us with barrels of radioactive waste that governments have been struggling to deal with.
In the US, there has been a plan to create deep geological storage facilities 660 meters below Yucca Mountain. This has been the plan since the 1980s but hasn't been put into action, so nuclear fuel is still being stored in dangerous interim storage facilities scattered around the country. As is the case with most nuclear energy projects it has faced delays and a lack of funding. Obama, Trump, and Biden have all failed to address this looming ecological threat. Waste management issues have continually caused political turmoil.
Shipments of nuclear waste from France to Germany have been met with thousands of protestors, a key driver of political pushback on the development of nuclear energy. So is there an engineering solution to this logistical concern? Of Course, adequate long-term storage is possible. Sweden has approved large storage repositories here in Frostmak. [4,5][REF][REF] Finland
has made similar arrangements to store its Nuclear waste here. [4,6][REF] [REF]This Finnish deep geological repository is expected to come online within a year. Deep geological repositories are sophisticated engineered systems that employ multiple layers of protective barriers to isolate the spent fuel from the surrounding environment. [REF] [4] What if we could make use of this nuclear waste, rather than locking it away for centuries like a supernatural Zelda villain.
Nuclear waste can be recycled. During the early development of Nuclear power, Uranium was thought to be a limited resource so a lot of research was directed into creating closed fuel cycles where the spent uranium would be reprocessed and recycled. But the assumption of limited uranium was wrong. Uranium is very common in the earth's crust. It’s much cheaper to mine, enrich, and process uranium than it is to recycle nuclear waste into workable fuel. Hence the adoption of an open fuel cycle.
This is the system currently operating on most nuclear reactors with new waste piling every minute. Recycling spent nuclear fuel is just a matter of separating unused uranium from the fission products. This process is also not new, it was developed in the 1950s and the basic steps are still used today in France and in Japan. France for example, cools its nuclear waste here.
For three years it sits there before moving to the reprocessing steps. [REF] [7] With the added cost, and the potential of extracting plutonium for nuclear weapons, the Carter administration banned US recycling facilities in 1977. [REF] [7] This recycled fuel can go back into regular light water reactors, or it could go into newer reactor designs. Two common themes in new generation reactors is passive cooling and higher thermal efficiencies through high temperature coolants. Light water reactors are limited to an operating temperature of around 300 degrees celsius, above this temperature the high pressure water begins to boil. Thermal efficiency is how much electrical energy we can produce from thermal energy, and in general, this efficiency gets better with higher temperatures.
To increase efficiency, future nuclear reactors can switch the coolant to something that can handle higher temperatures. In the early 2000s, the US Department of Energy decided to create the Gen IV international forum. It was composed of the best scientists around the world to direct policy decisions and funding for new reactor designs. They chose a total of 6 new reactor technologies and coined them Generation IV reactors.
Instead of using water as a coolant, Gen IV reactors can use gas, supercritical water, molten salts, molten lead, or sodium to increase the operating temperature of the reactor. This increase in efficiency will result in less nuclear waste per gigawatt generated, but these designs also aim to increase passive cooling capabilities and limit nuclear proliferation risks. One of the most interesting prospects is the Molten salt reactor or MSR. In these reactors, the coolant and the radioactive fissile material are all combined. The basic premise of these reactors was tested and experimented with during the 1960s at the Oak Ridge National Laboratory In an MSR, the fuel consists of nuclear fuel, such as uranium or thorium, dissolved in a molten salt mixture. The salts typically used are fluorides or chlorides, which have high melting points and good heat transfer properties.
The fuel salt circulates through the reactor core, absorbing heat generated by nuclear fission. After it passes through the core, the fuel salt transfers heat to a secondary salt coolant loop. The secondary salt, which does not contain fissile material, absorbs the heat from the fuel salt and carries it to a heat exchanger. In the heat exchanger, the heat from the secondary salt is transferred to a separate working fluid, typically water, which then powers a steam generator.
Since the coolant that they use does not need to be at high pressure like the water-cooled reactors in Fukushima, salt reactors also are not at risk of high-temperature steam explosions. While light water reactors typically have a thermal energy efficiency of around 30%, molten salt reactors have been theorized to achieve efficiencies between 40% to 45% [REF] [4]. Molten Salt Reactors also have the potential for inline fuel processing, which means that while the reactor is operating, the fuel salt can be continuously reprocessed to remove fission products and add new fuel. Meaning the machine can run continuously without stopping for refueling. At first glance, you'll notice that the system needs not one, but two pumps.
However, these reactors can safely cool down even when power is lost to these pumps. The salts' chemical properties naturally inhibit further nuclear fission as temperatures increase. The exact mechanisms of this depend on the salt composition, but generally, as the molten salt gets hotter, it expands. This expansion decreases the volume of fuel in the core of the reactors, and therefore decreases the rate of nuclear fission. [Ref] [Ref][8,9] Meaning, the hotter it gets, the less fission occurs, helping prevent nuclear meltdown.
[REF][9] A freeze plug is also located at the bottom of the liquid salt pool. The freeze plug is designed to melt at a particular temperature. In the event of an uncontrolled rise in temperature the plug will melt and allow the fuel and molten salt to passively drain into cooled dump tanks. [REF][9] Molten Salt Reactors are some time away from commercial readiness and that problem extends to all other 4th generation reactors despite significant support from proponents of these technologies.
The 4th generation international forum originally proposed that most of these technologies would to be ready by 2020, but based on the fact that the only footage available is from the 1960s, that has not come to fruition. Lack of funding, and competition from low cost solar and wind, has held back development of these fourth generation technologies. This problem is only going to continue until Nuclear energy addresses its largest problem. Cost. Since 2003, MIT has been conducting studies specifically aimed at guiding researchers and policymakers towards a viable future for nuclear energy.
In their latest report, they stated that the utmost importance must be given to lowering the cost of nuclear plants.[REF] [4]. And thus, the most promising ideas seek to address these cost issues. While deep geological repositories, uranium reprocessing, and Gen IV reactors had the brunt of the work done during the 1900s. A new design concept started to emerge in the early 2000s. Small Modular Reactors, or SMRs for short.
The goal of this design is to miniaturize reactors and convert them into small standardized modules that can be fabricated in factories. This standardization not only could decrease costs but inherently increases their reliability and safety as complexity is removed from the manufacturing and assembly while decreasing on-site construction costs. Small modular reactors work in much the same way as regular nuclear plants, but with smaller individual reactors that can work in expandable modules.
Gradually increasing the output of a power plant with cheaper factory-made modules, rather than building one large custom-designed nuclear power plant with 1000 Megawatts of electricity capacity. [REF][10] Making the reactors smaller also comes with the big benefit of passive safety. A smaller reactor has more surface area for heat transfer to occur in proportion to the volume of material that needs cooling.
Meaning natural convection cycles are sufficient to cool the reactor. As the coolant is heated, it rises due to its lower density, establishing a natural flow pattern that drives the cooling process. SMRs are not defined as one type of nuclear reactor or one design, rather, they are a family of designs that takes advantage of the miniaturization of the technology.
Because of this, no one SMR is like the other. Some use Gen IV reactors, others use light water reactors. Currently, over 70 commercial small modular reactors are being developed. [REF][REF][11,12] Nuscale may be the most promising of all these companies.
Their most recent 77MW Module is around 20 m tall and 4.5 m in diameter. [REF] [13] Each of these modules is lowered into a water bath and set on top of seismic isolators. This makes sure that any earthquakes do not affect the reactor. [REF] [14] All of the components needed for the nuclear reaction are fitted in one steel containment vessel. To create a larger plant, Multiple modules are connected together.
If power to the reactor is lost, control rods fall automatically in a gravity driven mechanism, and the containment vessel seals its valves to isolate itself. The water from the core is boiled off as steam but stays inside the containment vessel. Transferring heat with the outside cooling pool, the steam condenses and pools at the bottom of the reactor vessel. Creating a natural circulation of cooling water inside the steel containment vessel. Within seconds the energy and temperature drop drastically and within a day the thermal power drops by 90%.
Cooling off the last 10% over the course of weeks. And while this all sounds great, we are nowhere near commercial deployment. NuScale is by far the most ahead, but have only managed to create a one-third scale model of their power plant.
[15][REF] Other countries like Russia, China, France, and South Korea have also invested in creating SMR technologies but have struggled to find utility customers. Without potential customers these startups will always fail in a capitalist system. Even Nuslace has been dropped by some utility clients as their prices seem to have exceeded expectations. [REF] [16] This poses a massive challenge to companies that rely on large-scale standardized factories to achieve their key market advantage. To build the factory they need customers, but they can’t get customers without the factory. Thousands of reactors will need to be built before economies of scale can kick in, and in reality, the exact reason traditional nuclear reactors produce so much electricity is to benefit from the economies of scale.
Building a 1000 MW reactor reduces the cost per megawatt, and that’s THE most important metric in the electricity market. That’s how you get grid operators to buy your electricity, by making it cheaper. NuScales’ original price point was 55$/ MWh.
However, due to inflation, rising steel costs, development issues, and many delays the costs are now estimated at 100$/ MWh. [17,18][REF][REF] In comparison, onshore wind and solar can be as cheap as 30$/MWh [19]. [REF].
With the threat of climate change looming over us, we need to ask ourselves. Can we rely on a capitalist system to fix a problem driven by capitalism? There is a distinct possibility that these technologies will never succeed without government funding. Energy generation is the foundation of every major world economy, and it is in countries best interest to invest in these technologies . Nuclear energy provides energy security. The US is not alone in trying to develop the technology.
China has embarked on the construction of a functional small modular reactor (SMR) project here. However, similar to many nuclear ventures, costs have significantly escalated, with the SMR reportedly being twice as expensive, in terms of cost per kilowatt hour, compared to a traditional large-scale nuclear plant. [REF][20] Canada has formulated a 2020 SMR action plan to help bring down cost, and have invested millions of dollars into SMR start ups. [REF] [REF] [21,22] Developing these technologies will need vastly more money than this, but it’s a step in the right direction. Wind and solar are game changing technologies that we could only have dreamed of being as cheap as they are today 2 decades ago, but we need every tool at our disposal to fight climate change. Not just to decarbonize our energy generation, but to start fighting the effects of climate change ,population growth and global industrialization.
From increasing demand for air conditioning, water scarcity driving the need for energy intensive water desalination, to last ditch efforts to reverse climate change with carbon capture. Energy is the cause and solution to our problems. The transition from fossil fuels, in my opinion, is the most pressing issue facing humanity.
This is an all hands on deck problem. We need our best minds working on it, and I see it as part of my responsibility with a platform as large as mine to inspire the next generation of engineers to work on the solutions. Where I try to inspire, I see Brilliant as the perfect partner for follow through. For education. The courses on Brilliant are perfect for getting you prepared for engineering college, or for simply advancing your current career. From advanced mathematics courses to computer science.
They even have courses on the very foundation of energy generation, electricity and magnetism. Brilliant uses interactive courses that test your knowledge along the way. A platform designed to teach you difficult subjects in the most efficient way possible. Using visual interactive examples, and they don’t impede your progress when you struggle. If you can’t figure out an answer, you can open an in depth explanation and move onto the next section.
These are likely the most universally useful courses to present and future engineers, but there are plenty of other courses on Brilliant. AI, data science, neural networks and more. You can get access to that course right now, and all of Brilliant's other curated interactive courses, by clicking the link in the description and on screen now.
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2023-07-23 19:15
