NRC Certifies First U.S. Small Modular Reactor Design

[Mary Wilson]

Office of Nuclear Energy
JANUARY 20, 2023



The U.S. Nuclear Regulatory Commission (NRC) issued its final rule in the Federal Register to certify NuScale Power’s small modular reactor.

The company’s power module becomes the first SMR design certified by the NRC and just the seventh reactor design cleared for use in the United States.

The rule takes effects February 21, 2023 and equips the nation with a new clean power source to help drive down emissions across the country.

Historic Rule Making

The published final rule making allows utilities to reference NuScale’s SMR design when applying for a combined license to build and operate a reactor.

The design is an advanced light-water SMR with each power module capable of generating 50 megawatts of emissions-free electricity. ...

https://www.energy.gov/ne/articles/nrc-certifies-first-us-small-modular-reactor-design

[Mary Wilson]

Nuclear waste from small modular reactors - PNAS

May 31, 2022
119 (23) e2111833119

https://doi.org/10.1073/pnas.2111833119

Lindsay M. Krall, Allison M. Macfarlane, and Rodney C. Ewing

Abstract

Small modular reactors (SMRs; i.e., nuclear reactors that produce <300 MW_elec each) have garnered attention because of claims of inherent safety features and reduced cost. However, remarkably few studies have analyzed the management and disposal of their nuclear waste streams. Here, we compare three distinct SMR designs to an 1,100-MW_elec pressurized water reactor in terms of the energy-equivalent volume, (radio-)chemistry, decay heat, and fissile isotope composition of (notional) high-, intermediate-, and low-level waste streams. Results reveal that water-, molten salt–, and sodium-cooled SMR designs will increase the volume of nuclear waste in need of management and disposal by factors of 2 to 30. The excess waste volume is attributed to the use of neutron reflectors and/or of chemically reactive fuels and coolants in SMR designs. That said, volume is not the most important evaluation metric; rather, geologic repository performance is driven by the decay heat power and the (radio-) chemistry of spent nuclear fuel, for which SMRs provide no benefit. SMRs will not reduce the generation of geochemically mobile ¹²⁹I, ⁹⁹Tc, and ⁷⁹Se fission products, which are important dose contributors for most repository designs. In addition, SMR spent fuel will contain relatively high concentrations of fissile nuclides, which will demand novel approaches to evaluating criticality during storage and disposal. Since waste stream properties are influenced by neutron leakage, a basic physical process that is enhanced in small reactor cores, SMRs will exacerbate the challenges of nuclear waste management and disposal.

https://www.pnas.org/doi/full/10.1073/pnas.2111833119

[JJackson]

Thorium based reactors seem a better option from a waste, operational safety and nuclear proliferation point of view. They produce U232, U233 and Th232 as waste, which are shorter lived isotopes, and none of which can be refined into nuclear weapons. The reactor design is safer as failures lead to an automatic shutdown, not meltdown.