Why SMRs are the future of clean nuclear energy.
Nuclear has no economies of scale. There are only complexities of scale. Everything just gets just bigger and more complicated and more likely to fail. Small is still beautiful.
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If you were here last Friday you may have read my argument that the problem with nuclear energy in a carbon-less future scenario is not safety but the complex reality that the commercial nuclear reactors we have built to date are too big, too complicated to permit, design and build, and too expensive to justify the business risk. When Tennessee's Watts Bar Unit 2 reactor, the most recent plant to come online, began operation in June 2016, it was the first since Watts Bar Unit 1, also in Tennessee, which entered service in May 1996. One new reactor every 20 years is hardly a useful pace.
All that seems to be changing, however, as more and more policymakers, energy executives, and innovators embrace a simple fact that should have been obvious earlier: When it comes to nuclear power, bigger is not necessarily better. The size of reactor units has grown from 60 megawatts electric to more than 1600 MWe since the 1950s, with corresponding complications. There are no economies of scale. There are complexities of scale. Everything just gets just bigger and more complicated and more likely to fail.
That’s where small modular reactor (SMR) technologies come in. SMR reactors are nuclear fission reactors built at a smaller size but in larger numbers than most of the world’s current nuclear fleet. The International Atomic Energy Agency defines “small” as under 300 MWe, and up to about 700 MWe as “medium.” One “small” SMR, for example, can probably meet the electricity needs of a city of 200,000.
SMRs are also considerably safer to build and run than older larger reactors. The reactor core operates at lower thermal power and compact architecture reduces variables Most importantly, passive safety systems mean less reliance on active safety systems and human error and additional pumps, as well as AC power for accident mitigation. Passive safety systems are able to dissipate heat even after the loss of power on-site. The safety system incorporates an on-site water inventory that operates on natural circulation.
From an economic point of view, it is obviously much cheaper to produce the necessary plug-and-play parts in a factory than to construct a reactor from the ground up in one location.
There are at least a half-dozen different reactor technologies being proposed or in development by more than 40 companies and universities in North America, ranging from advanced water-cooled reactors, which would make safety, efficiency, and other improvements over existing commercial reactors; gas-cooled reactors, which use graphite as a neutron moderator or have no moderator; liquid-metal-cooled reactors, which would be cooled by liquid sodium or other metals and have no moderator; molten salt reactors, which would use liquid fuel; and, everybody’s fever dream, fusion reactors, which would release energy through the combination of light atomic nuclei rather than the splitting (fission) of heavy nuclei such as uranium.
Whatever the technology, SMRs seem to be the common denominator
Many of the new innovations are being driven by the Department of Energy’s Advanced Reactor Demonstration Program (ARDP) which in October 2020 announced that it was awarding TerraPower (Bill Gates-financed company) and X-energy (Rockville, MD) $80 million each in initial funding to build two advanced nuclear reactors that can be operational within seven years.
The awards are cost-shared partnerships with industry that promise to deliver two first-of-a-kind advanced reactors to be licensed for commercial operations. DOE will invest a total of $3.2 billion over seven years, subject to the availability of future appropriations, with the industry partners providing matching funds.
Just as importantly, the DOE announced in February 2019 that it is building a Versatile Test Reactor (VTR), to be completed by 2026. The effort is being led by Idaho National Laboratory in partnership with five national laboratories (Argonne, Los Alamos, Oak Ridge, Pacific Northwest, and Savannah River) and a host of industry and university partners. We had a couple of test sites but they were closed in the 1990sfor budgetary reasons.
There’s not much point in developing Advanced Nuclear Technologies if you don’t have someplace to test them.
Finally, I hate to drag politics into everything, but the VTR and ARDP were initiatives of the Trump administration so I hope some berserk apparatchik doesn’t get ideas. Trump didn’t do many good things but these are two of them.
I had planned to get into the story of Bill Gates and TerraPower but the hour grows late, my brain grows tired, and is balking at taking on traveling wave reactors right now. Let’s get together here again next week. Same time, same place.
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