US nuclear regulator greenlights early work on 680-MW small reactor in Michigan

The US Nuclear Regulatory Commission has cleared clean energy firm Holtec to begin key early construction work for two planned small modular reactors at the Palisades Energy Center in Michigan, allowing excavation and ground preparation to move ahead before a Limited Work Authorization is issued. The NRC granted the exemption on August 28, 2026, permitting Holtec to install permanent support-of-excavation and cutoff-wall systems for Pioneer Units 1 and 2. The approval covers work needed to stabilize the site and prepare the ground for the reactors and associated facilities. The two units are planned to deliver a combined 680 megawatts of electricity. They are part of Holtec’s plan to deploy its SMR-300 advanced small modular reactor at the Palisades site, where the company is also working to restart the existing nuclear power plant. The newly approved work will include excavation, dewatering and ground improvements for the Nuclear Island, Turbine Island and Balance of Plant structures. The walls will help hold surrounding soil in place, control groundwater and protect nearby structures and utilities during construction. Excavation sets foundation first The support system will use diaphragm walls, soldier-pile soil-mix walls and perimeter cutoff walls. Depending on site conditions, tiebacks or internal struts can be used to provide additional support. Holtec plans to leave the support-of-excavation walls in place after construction rather than remove them. The space between the walls and permanent structures will then be backfilled to ground level. The NRC’s decision follows an environmental assessment issued August 25. The agency found that the authorized activities would not significantly affect the human environment or historic properties and concluded that a separate environmental impact statement was not required for the exemption. The NRC also determined that the exemption meets requirements under federal regulations, including provisions covering public health and safety, national security and special circumstances. The approval does not, however, amount to a construction permit. Holtec must still obtain further regulatory approvals before it can proceed with the full construction of the nuclear units. Nuclear construction moves ahead The early excavation work is intended to establish the stable foundation conditions required for later plant construction. Holtec will also conduct geologic mapping and collect data as excavation progresses. The company must notify the NRC when the excavation is open for inspection. Information gathered from the exposed geology will be incorporated into analyses used to evaluate how the structures and surrounding ground will interact. The NRC’s exemption allows Holtec to advance these activities while its broader application moves through the regulatory process. The company had submitted the exemption request on December 31, 2025, as part of the first phase of its phased Construction Permit Application. Holtec is developing the Pioneer units around its SMR-300 reactor, which uses passive safety systems designed to respond to abnormal conditions without relying on active operator intervention. The company expects the first two SMR-300 units to be deployed at the Palisades site. It is also pursuing the recommissioning of the existing Palisades nuclear plant, which would make the site a combination of existing and new nuclear generation.For now, the latest NRC decision clears the way for site preparation, not reactor construction or operation. The exemption gives Holtec permission to establish the underground excavation and foundation conditions needed for the next stage of the project.Get the latest in engineering, tech, space & science - delivered daily to your inbox.With over a decade-long career in journalism, Neetika Walter has worked with The Economic Times, ANI, and Hindustan Times, covering politics, business, technology, and the clean energy sector. Passionate about contemporary culture, books, poetry, and storytelling, she brings depth and insight to her writing. When she isn’t chasing stories, she’s likely lost in a book or enjoying the company of her dogs.