https://www.iaea.org/newscenter/news/what-are-small-modular-reactors-smrs
Tech giants are signing deals with nuclear power companies to supply energy to their data centers. Many of these deals revolve around unproven Small Modular Reactors (SMRs). This is a relatively new term for most people, so I figured it as worth it to dig in a little to help it make sense.
First to get the hysteria out of the way. No, Microsoft and Google will NOT be running nuclear reactors. No, AI will not be running nuclear reactors. These SMRs will be operated by highly trained operators licensed by the NRC, just like I was on my reactor. Every licensed operator is personally responsible for ensuring nuclear safety. Like go to prison personally responsible. It doesn’t matter who’s name is on the front gate.
For the most part, the difference really is in scale. SMRs are just that; small. They will still use the fissioning of uranium to produce heat. The typical modern utility size nuclear reactor has an output of around 1000 MW. That’s enough electricity to power about 1000000 homes, depending on the environmental conditions in the area. SMRs on the other hand are generally less than a quarter of that size.
The idea behind SMRs is that they are small enough to be built and assembled in a factory and installed where they are needed. Using an assembly line approach should cut costs for nuclear just as it did for everything else in modern life. Whether that will happen remains to be seen, but that is the idea. Costs are one of those things about nuclear that make it so hard to place a solid bet on its future, but having trillion dollar corporations invest in it can’t hurt.
Many of the locations that these SMR companies are looking to install their reactors at are coal power plants, either retired or soon to be retired. They are already connected to the power grid via a substation, which saves a lot of money on construction costs. And, nuclear plants don’t emit CO2 or any other greenhouse gas, which is kind of the point.
Another advantage to SMRs is the incredible advancements that have been made in reactor safety since we first started building them in the 1940s. SMRs are incorporating what is known as passive safety features, meaning the safety systems do not require electrical power to function. Older nuclear plants are required to have a complex system of backup power, including massive diesel generators, to ensure the safety systems can protect the core. SMRs don’t need this.
As an example, NUSCALE’s SMR design is submerged in a pool, all of which is contained inside a containment structure. The reactor assemblies will self-cool indefinitely with no power required using natural circulation based on differences in the density of hot water and cold water. Even after all the water in the pool is gone, the reactors are able to be air cooled.
There are some interesting videos on their website to show how this works.
https://www.nuscalepower.com/en/products/voygr-smr-plants
Another big change is the fuel itself. NUSCALE uses conventional fuel assemblies, the same as any other light water PWR. These fuel assemblies have been enhanced over the years and are incorporating accident resistant technologies as they become available.
Other manufacturers are using other accident resistant fuels. Kairos and X-Energy are using TRISO fuel in their new SMR. TRISO fuel is made of tiny ceramic pellets that CANNOT melt at the temperatures inside this type of reactor. The pellets are designed to be self containing, meaning they will prevent the release of fission products from the fuel. It really is amazing stuff.
https://kairospower.com/technology/
Another key benefit to SMRs is the reduced size of the emergency planning zone (EPZ). Traditional plants have a 10 mile EPZ. This is the area that might be evacuated or told to shelter in the event of a serious accident at a nuclear plant. Those of you who live inside of one are probably familiar with the sirens.
SMRs will require a much smaller EPZ. The size of the EPZ is based on the risk of people living near the plant receiving a dose of radiation greater than the EPA says is safe. With the advances in design and the much smaller amount of fuel present in an SMR, the EPZ for an SMR will be entirely within the site boundary. This is the government recognizing that these new designs pose extremely little risk to the surrounding public and environment.
The growth in demand for electricity is outpacing the growth in clean power sources. As a result, the share of our power that comes from fossil fuels has held steady at around 60%, despite massive gains in solar and wind. SMRs will allow large technology and industrial companies to acquire the power and process heat they need in a way that does not continue to make climate change worse.
Unless we give up on the internet and allowing developing countries to grow, we need to tap all sources of power that will allow continued development and that will not further increase the climate crisis. Nuclear power, including SMRs, must be a part of that effort.
As always, this is all open source. I do not even have access to non-public information on any of this topic, so no additional links just to prove I got my information from open sources.
Sleepy Neutron's Nuclear Knowledge 
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