

What about safety?
Nuclear power plants are complex buildings that rely on external power systems such as AC power, backup generators, and batteries to cool down the reactor’s fuel in the case of a power loss, which increases accident risks. Suppose something that wasn’t considered in the design happens. In that case, it may cause the system to fail, similar to what happened in the Fukushima Daiichi nuclear disaster in 2011 when a second tsunami that wasn’t expected hit the nuclear plant.On top of that, maintenance and refueling are an additional complexity for nuclear power plants. Every 18 to 24 months, these power plants are shut down for refueling, which usually takes a month without energy production, and SMRs can be a promising candidate to reduce these downsides 13, 14.When we talk about nuclear reactors, we refer to a containment building with large walls, safety measures, and cooling. But, with SMRs, it’s different. These small-sized reactors fit right into other structures or come with their own containment structure. And some of these designs have a long refueling cycle. For example, the 5 MW Micro Modular Reactor, from Ultra Safe Nuclear Corporation (USNC) … you gotta love that name … requires no refueling in its 20-year operating lifetime, and the 100 MW ARC-100 small modular reactor would have a refueling cycle of a similar 20 years.SMRs enhance safety and security through lower thermal power of the reactor core and use of passive safety systems. That means they have less reliance on active safety systems like additional pumps and AC grid power, generators, and batteries. NuScale’s SMR employs natural water circulation to passively cool its reactor down. The thermal safety system incorporates an on-site water reservoir located on the sides of the outer vessel, which removes the heat from the core, avoiding a complete meltdown. In an eventual emergency, specialized valves open automatically, which allows steam to be released from the reactor vessel into the containment vessel. The steam then condenses, and water flows back down into the core through the second set of valves at the bottom of the reactor vessel. This helps cool the reactor down. The steam generated by boiling water recirculates, setting up a passive safety cooling process that lasts until the heat and pressure finally stabilizes. All this cooling and power control happens with no external interference, no AC or DC power, no operator, and no additional water, similar to proposed molten-salt thorium reactors 15, 16, 17.Considering all these advantages, many countries have been investing a lot of money in research and development of SMRs. The Oregon-based NuScale, for example, has spent more than $800 million on its SMR design 12. In 2010, the company estimated a capital cost for a 12-module, 540 MW NuScale plant would be about $4,000/kW, which rose to $5,078/kW net in 2014 and an LCOE presumed to be about $100/MWh for the first unit. In June 2018, the company declared that its reactor could produce 20% more power than originally planned. Subject to Nuclear Regulatory Commission approval, this would lower the overall capital cost to about $4,200/kW and lower the LCOE by 18% 9. Other American SMR developers include GE Hitachi Nuclear Energy, Bill Gates-backed TerraPower, X-Energy, and Hyperion Power Generation.18China National Nuclear Corporation (CNNC) announced in 2019 it would start building a demonstration of its 125 MW ACP100 small modular reactor on the north-west side of the existing Changjiang Nuclear Power Plant by the end of the year.




But, is this all to good to be true?
So are SMRs too good to be true? Although progress has been made in SMR technology, licensing and certification are a major stumbling block for SMRs, as well as potential design changes and increased security. NuScale design, for example, is still in the licensing stage and faces important security questions, which include potential problems with the system that automatically shuts down its reactors in eventual emergencies 24. Normally, convection circulates water laced with boron to control the nuclear reaction through the core of NuScale’s reactor. As I mentioned earlier, if the reactor overheats, it shuts down and valves release steam into the containment vessel, where it condenses and flows back into the core. However, the condensed water can be low in boron, and reviewers are concerned that low boron level might mean it wouldn’t be able to stop the core. This has complicated their approval process 25.In addition to that, even though SMRs can be cheaper and safer, they still have to contend with economies of scale. Conventional power plants have thousands of Megawatts of power production capacity compared to dozens or hundreds of Megawatts for SMRs. An analysis performed by Energy Strategies for the Healthy Environment Alliance of Utah in 2019 showed an SMR LCOE range of $46.66/MWh to $90.48/MWh, and that’s with a lot of uncertainty around resource costs. Nuclear power’s biggest rival, natural gas, had an LCOE of $45.56/MWh 26.
“Radioactive left-over used fuel from the new (SMR) reactors will still require safe storage for hundreds of thousands of years.” -Gordon Edwards, president of the Canadian Coalition for Nuclear Responsibility (CCNR) 29The International Atomic Energy Agency has also written about this topic.
“Solutions for managing spent fuel and radioactive waste arising from SMRs will be one of the most important factors to take into account when choosing a technology, along with the security of fuel supply.” -Christophe Xerri, IAEA Director of Nuclear Fuel Cycle and Waste Technology 30Despite the challenges, SMR supporters look at it as a potential solution for nuclear power to be more cost-effective, safe, and competitive against other fast response power sources to balance an increasingly intermittent power supply that comes from wind and solar power. They may be right; but there are still concerns about SMR technology that need to be addressed, and unresolved problems with nuclear power in general that need solutions before this carbon-free power source can be considered a viable, worldwide option.Jump into the comments and let me know what you think. And if there’s anything I missed with SMRs. If you liked this video be sure to check out one of the ones I have linked right here. Be sure to subscribe and hit the notification bell if you think I’ve earned it. And as always, thanks so much for watching, I’ll see you in the next one.
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