NuScale responds to SMR critique

June 2, 2022, 9:30AMNuclear News

A Stanford University–led research article on small modular reactors published Tuesday in Proceedings of the National Academy of Sciences (PNAS) is not sitting well with SMR developers or, for that matter, with much of the largely pro-SMR nuclear community.

Authored by, among others, Allison Macfarlane, former chairman of the Nuclear Regulatory Commission, “Nuclear waste from small modular reactors” looks at three reactor designs—NuScale Power’s, Terrestrial Energy’s, and Toshiba’s—and concludes that SMRs will generate more nuclear waste than a standard pressurized water reactor (of 1,100 MWe, to be specific) by a factor of anywhere from 2 to 30.

“These findings stand in sharp contrast to the cost- and waste-reduction benefits that advocates have claimed for advanced nuclear technologies,” said coauthor Lindsay Krall in a Stanford News piece.

NuScale responds: Following the study’s publication, Jose Reyes, NuScale’s chief technology officer and cofounder, wrote the following to PNAS editor-in-chief May R. Berenbaum. (Others in the nuclear community have also commented on the Stanford article, as noted on the Neutron Bytes site):


Dear Professor Berenbaum:

I respectfully write this letter to inform you of a factual error in the paper titled “Nuclear waste from small modular reactors,” authored by Lindsay M. Krall, Allison M. Macfarlane, and Rodney C. Ewing and published May 30, 2022, in the Proceedings of the National Academy of Sciences. Because PNAS is widely recognized as an authoritative source of high-impact original research, publications in PNAS are widely read and frequently cited. As such, errors in PNAS papers require prompt correction.

The authors mistakenly assert that NuScale small modular reactors will produce significantly more spent nuclear fuel (SNF) than existing light water reactors. The basis for this statement is their analysis of the NuScale 160-MW thermal core as opposed to the NuScale 250-MW thermal core implemented in NuScale VOYGR plants. In January 2021, NuScale provided the characteristics of the 250-MWt core to the National Academies of Science, Engineering, and Medicine (NASEM) ad hoc committee to evaluate and assess the “Merits and Viability of Different Nuclear Fuel Cycles and Technology Options and the Waste Aspects of Advanced Nuclear Reactors.” NuScale’s response to the NASEM ad hoc committee questionnaire is publicly available and states that the NuScale fuel has an average fuel burnup of approximately 45,000 MWd/t at discharge and that it has a design basis maximum exposure of 62 GWd/MTHM. These values are within the values typically observed in the existing fleet of LWRs. Therefore, the NuScale 250-MWt design does not produce more SNF than the small quantities typically observed in the existing LWR fleet. One of the authors of the subject paper, Dr. Macfarlane, was also a member of the NASEM ad hoc committee that received our questionnaire responses.

I have copied Richard Meserve, chairman of the ad hoc committee on “Merits and Viability of Different Nuclear Fuel Cycles and Technology Options and the Waste Aspects of Advanced Nuclear Reactors,” and Charles Ferguson, NASEM project officer for the Nuclear Fuel Cycle Study, so that this error in the subject paper is not incorporated into the NASEM Fuel Cycle Study.

Lastly, I note that the authors did not contact NuScale for information or clarifications regarding NuScale fuel burnup, even though a publicly available document on the subject was available. We learned of the subject paper by five members of the media who had received advanced copies of the PNAS paper. As a member of the academy, I was not aware of the policy to issue advanced copies of PNAS papers to the media.

Jose N. Reyes, Ph.D., Chief Technology Officer and Cofounder, NuScale Power

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