Nuclear power plants are not “carbon free.” They do not emit carbon or other greenhouse gases as they split atoms during the fission process, but their carbon footprint must be assessed on the basis of their complete nuclear fuel life cycle. Significant amounts of fossil fuel are used indirectly in mining, milling, uranium fuel enrichment, plant, and waste storage construction, decommissioning, and ultimately transportation and millennia-long storage of waste. There is plenty of carbon in that footprint that is rarely acknowledged, computed, or mediated. You can read that

Additionally, the industry’s rhetoric masks the astronomical costs for thousands of years of storage that could be better invested in rapidly developing renewable fuels with a lower carbon footprint such as solar, wind, geothermal, and Ocean Thermal Energy Conversion, without any potential side effects.

The prospects for SMRs are poor. Here’s why.

*Economics and scale*

Nuclear reactors are large because of economies of scale. A reactor that produces three times as much power as an #SMR does not need three times as much steel or three times as many workers. This economic penalty for small size was one reason for the early shutdown of many small reactors built in the U.S. in the 1950s and 1960s.

*Mass manufacturing aspects*

If an error in a mass-manufactured reactor were to result in safety problems, the whole lot might have to be recalled, as was the case with the Boeing 737 Max and 787 Dreamliner jetliners. But how does one recall a radioactive reactor? What will happen to an electricity system that relies on factory-made identical reactors that need to be recalled?

*SMRs and the climate crisis*

The climate problem is urgent. The IPCC and other international bodies have warned that to stop irreversible damage from climate change, we need to reduce emissions drastically within the next decade. The SMR contribution in the next decade will be essentially zero. The prospects for SMRs beyond that are also bleak, given that entire supply chains would need to be established after the first ones have been built, tested and proven in the field.

*Other concerns*

Water use is another concern that is expected to intensify in the future. Nuclear plants have very high water withdrawal requirements. A single 300 MW reactor operating at 90 percent capacity factor would withdraw 160 million to 390 million gallons of water every day, heating it up before discharge. Reducing the demand for water by using air cooling will require the addition of a tower and large electric fans – further raising the construction cost and reducing output of electricity by up to 7 percent of the capacity of the reactor.

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.