Why Small Modular Nuclear Reactors Won’t Help Counter the Climate Crisis via EWG

By Arjun Makhijani and M.V. Ramana


The nuclear industry and the U. S. Department of Energy are promoting the development of SMRs, supposedly to head off the most severe impacts of climate change. But are SMRs a practical and realistic technology for this purpose?

To answer, two factors are paramount to consider – time and cost. These factors can be used to divide SMRs into two broad categories:

  1. Light water reactors based on the same general technical and design principles as present-day power reactors in the U.S., which in theory could be certified and licensed with less complexity and difficulty.
  2. Designs that use a range of different fuel designs, such as solid balls moving through the reactor core like sand, or molten materials flowing through the core; moderators such as graphite; and coolants such as helium, liquid sodium or molten salts.

On both counts, the prospects for SMRs are poor. Here’s why.


Finally, SMRs will also produce many kinds of radioactive nuclear waste, because the reactors are smaller in physical size and because of refueling practices adopted for economic reasons. SMRs based on light water designs, such as NuScale, will also produce a larger mass of nuclear waste per MWh of electricity generated. The federal government is already paying billions of dollars in fines for not fulfilling its contractual obligations to take possession of spent fuel from existing reactors. The legislative plan in the 1982 Nuclear Waste Policy Act was for a deep geologic disposal repository to open in 1998. After nearly four decades, that plan has come to naught.


There is no realistic prospect that SMRs can make a significant dent in the need to transition rapidly to a carbon-free electricity system. The prospects of timely contributions by even the light water designs, with NuScale being the most advanced in schedule, are dismal. The prospects for reactors of other designs, like those with graphite fuels or sodium cooling, are even more so. 

It will be a tough road for SMRs to achieve cost parity with large reactors. And that cost will still be far too high. Two things are in critically short supply on the road to a climate-friendly energy system: time and money. An objective evaluation indicates that SMRs are poor on both counts. There is simply no realistic prospect for SMRs to play materially significant role in climate change mitigation. 

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