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For SpaceNut ... we did not appear to have a topic devoted to small modular reactors.
This topic is offered for NewMars members who might wish to contribute links, images and text about the growth of this important industry. We will open with a report of Canada (Ontario) planning to build four SMR systems.
https://www.msn.com/en-us/news/world/of … 4e65&ei=49
Canada is leading the Group of Seven in developing new nuclear energy technology with the construction of the first of four small modular reactors in Ontario, the Associated Press reported.
The government's Ontario Power Generation will proceed with its plan to construct the first of four SMRs at its Darlington nuclear site. It will be North America's first commercial, grid-scale reactor and is expected to be in service by the end of 2030, supplying low-carbon power to about 300,000 homes.
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Post #3: Calliban re reactor type
https://newmars.com/forums/viewtopic.ph … 91#p232091
Also see: https://www.gevernova.com/nuclear/carbo … ar-reactor
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Although the article doesn't mention them by name, the SMRs are BWR-300X units. So far, I have seen only limited concept design information on this reactor type. But it does appear to be very compact for the amount of power it produces. This reactor could be useful for powering a Martian base. Unlike PWRs, the BWR does not require bulky heat exchangers. That is a significant weight saving.
All LWRs have comparable thermodynamic efficiency: 30-35%. The remainder is waste heat, which is warm water at 30°C. This could have uses for district heating on Earth. It could have uses on Mars as well.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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SMRs would be a great capability to have, and absolutely necessary for powering colonies on Mars. Unfortunately, every one of these designs has ultimately gone nowhere in about 5 to 10 years time. A bunch of money is spent to construct a scale prototype, and then for reasons unknown to me we never drag the finalized design across the finish line where the first commercial units are certified to start producing electric power. That's a shame because a number of innovative designs, arguably safer / easier to use / easier to maintain, have been on offer. The closest thing to a SMR we have are the nuclear submarine reactors, and all of those seem to work quite well, decade after decade.
I don't know if the hurdle is a regulatory issue or because the companies involved in SMR design lack the depth of engineering talent or financing talent or something else like institutional bias against smaller reactors. I'd be quite pleased if this time is different and we end up with real tangible hardware, ready to deploy to remote locations around the world and on other planets. I know that many of the engineering challenges are the same regardless of reactor power level, but SMRs must also have some unique challenges of their own.
Maybe someone can speak to the engineering issues unique to SMRs. I listened to a YouTube podcast on Decouple Media where a US DoE expert was talking about working with various reactor designers to evaluate the technical merits / demerits of SMR designs. He talked a lot about cooling the reactor and operations, especially maintaining the balance-of-plant for SMRs, which is apparently a bit of an issue due to close proximity to the operating reactor. My gut-feel on this is that maintaining the power turbine and electrical equipment is something of an afterthought in these highly integrated reactor designs, and that the inability for a human worker to go physically tweak components makes them unreliable from the standpoint of having to shut down the reactor to work on everything else that is not the reactor itself.
The gist of the conversation on Decouple Media is that when you design a SMR, even if the reactor core itself is readily truck-transportable, we're going to stuff that reactor into a subsurface concrete containment structure with a bunch of infrastructure built on top of it, just like a conventional power plant. The net-net is that the reactor core and electric generating equipment is transportable by truck or rail, but the facility that will operate the reactor is not transportable in any sense of the word. It's a fixed site that involves excavation and must be fabricated over multiple months. The upside is that following fuel depletion the reactor itself can then be returned to the "reactor factory" for refueling and refurbishment, so there's no pile of fuel rods that accumulates onsite the way they would with a traditional GW-class PWR or BWR. This approach is "cleaner" in the sense that the fuel stays inside the reactor core and will never leave the core while the reactor is on onsite.
I think the key to making these reactors profitable is operating them at elevated temperatures and using sCO2 turbines so that the balance-of-plant is tiny and doesn't require a fresh water supply. I don't think most people recognize how great a technological windfall it is to have "steam turbine equivalents" that are 10 times smaller than steam turbine equipment and don't need a water supply. So long as you can deliver the materials to fabricate the power plant facility, to include the power transformers / switching yard / power lines, all the rest of the equipment can be trucked into and out of the facility. That is simply not feasible using steam turbines and traditional GW-class reactors, which must be fabricated onsite over 5 to 10 years. It should be possible to get a SMR facility up and running over 2 years.
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