The Nuclear Regulatory Commission is developing a generic environmental impact statement (GEIS) for small-scale advanced reactor designs. Just how small a reactor must be to fit the parameters of the GEIS is one topic open for public comment, but the NRC staff anticipates including reactors generating up to 30 MWt. The public comment period is open until June 30

When it comes to advanced, high-temperature reactors—using working fluids such as molten salt, high-temperature gases, or sodium—there simply are not many qualified materials for nuclear component construction. Alloy 617 is not a new material, but it made the news after Idaho National Laboratory announced that it was recently added to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code for high-temperature nuclear applications, bringing the total number of qualified high-temperature materials to six.

High-assay low-enriched uranium (HALEU) is the fuel of choice for many advanced reactor developers, including Advanced Reactor Concepts, which is designing the ARC-100, a sodium-cooled fast reactor. Developers face a potential supply problem, however: The United States has no clear path to build the commercial HALEU production facilities that would be needed to fuel a fleet of advanced reactors. A letter of intent signed by ARC and Centrus Energy, announced on April 28, calls for cooperation on the deployment of a commercial supply of HALEU and could lead to a HALEU purchase agreement for ARC-100 deployments in the late 2020s.

The Department of Energy announced on April 28 that the Southern Ohio Diversification Initiative (SODI) and the Southern Nuclear Development LLC (SND) would receive funding for their advanced nuclear technology development projects. The two awards—one to support site preparation for a future domestic advanced reactor demonstration project and the other for an advanced reactor regulatory licensing grant—have a total value of $5.4 million.

Battelle Energy Alliance, the managing and operating contractor for Idaho National Laboratory, is seeking an expression of interest (EOI) from industry stakeholders interested in forming a partnership to develop and/or demonstrate advanced construction technologies and processes. The effort would be executed as an initiative of the National Reactor Innovation Center (NRIC) at INL. Battelle announced the EOI on April 17, with a deadline for responses of May 16.

The University of Tennessee (UT) and the Tennessee Valley Authority (TVA) signed a memorandum of understanding on April 7 to evaluate the development of a new generation of cost-effective advanced nuclear reactors, such as small modular reactors (SMR), at TVA’s 935-acre Clinch River Nuclear Site in Roane County, Tenn.

The TCR program is leveraging an agile approach—one that is centered around continuously informing the process—to accelerate deployment timelines and introduce performance improvements. Image: Adam Malin, ORNL

Soon after Enrico Fermi’s Chicago Pile-­1 went critical for a brief duration in December 1942, the construction of the first continuously operating reactor, the X-­10 Graphite Reactor, was initiated in February 1943 at Clinton Engineer Works in Oak Ridge, Tenn. On November 4 of that year, a mere nine months after the start of construction, the reactor began operation. This marked the onset of what Alvin M. Weinberg referred to as “the first nuclear era,” during which many reactors of various designs and operating parameters were built and demonstrated across the United States. Forty years ago, the Fast Flux Test Facility was the last U.S. non-­light-­water reactor to reach criticality, and it has since been decommissioned.

On February 27, Sens. Lisa Murkowski (R., Alaska) and Joe Manchin (D., W.Va.) introduced the American Energy Innovation Act (AEIA), a 555-­page piece of policy legislation that incorporates over 50 energy-­related bills considered and individually reported by the Senate Energy and Natural Resources Committee last year—measures sponsored or cosponsored by more than 60 senators from both sides of the aisle.

This week I had some considerable interaction on social media in the area of replacing fossil power at existing sites with micro reactors or SMR’s (Small Modular Reactors.) As we see real progress happening now in these exciting reactor fields (NuScale and Oklo come to mind first, but there are others!) I’d like to share five things to think about as we begin to seriously consider replacing fossil power (coal, oil) at particular sites with nuclear.

Advanced reactor cores are being designed for higher efficiencies and longer lifetimes, but to get there, they need high-assay low-enriched uranium (HALEU).

Enriched to between 5 and 19.75 percent fissile U-235, HALEU is packed with nuclear potential. It can be used as a feedstock for the demonstration of new fuel designs, from uranium alloys to ceramic pellets and liquid fuels. Those fuels can enable advanced reactor and microreactor demonstrations. Operating light-water reactors could potentially transition to HALEU uranium oxide fuels for extended operating cycles and improved plant economics.