Holtec SMR project receives regulatory approval to proceed with early site construction

The U.S. Nuclear Regulatory Commission (NRC) has granted Holtec International a regulatory exemption allowing the company to advance certain early construction activities for two small modular reactor (SMR) units at the Palisades Energy Center in Michigan before obtaining a Limited Work Authorization (LWA).

Palisades SMR, a wholly owned subsidiary of Holtec International, submitted the first part of a phased construction permit application to the NRC last December for the dual-unit SMR-300 project (Units Pioneer 1 and 2). The application included a request for a Limited Work Authorization aimed at allowing specific construction activities to begin before a construction permit or combined construction and operating license is formally issued. The NRC accepted and completed its docketing review of the application in February of this year.

The exemption approved by the NRC on August 28 authorizes Holtec to install permanent Support of Excavation (SOE) and groundwater cutoff systems for Units Pioneer 1 and 2. According to Holtec, these systems include diaphragm walls, steel-reinforced cement-soil mixing walls, and perimeter cutoff walls, with anchors or bracing structures configured as needed.

These early works will establish stable and solid excavation and foundation conditions, thereby providing strong support for subsequent plant construction after the LWA is granted and accelerating the overall construction schedule. After construction is completed, the excavation support walls will ultimately be “abandoned in place,” and the space between the walls and permanent structures will be backfilled to design grade.

Before issuing the exemption, the NRC published an environmental assessment and a Finding of No Significant Impact (FONSI), concluding that granting the exemption would not have any adverse impact on environmental quality. The regulator also determined that the installation and in-place abandonment of the excavation support walls would not negatively affect the safety design or siting of Units Pioneer 1 and 2.

During excavation, Holtec will conduct geological mapping and data collection, notify the NRC in a timely manner when excavation surfaces are open for inspection, and fully account for the effects of the in-place abandoned support walls in soil-structure interaction analyses.

The SMR-300 developed by Holtec is a pressurized water reactor with a single-unit electrical output of approximately 300 megawatts, or it can provide 1,050 megawatts of thermal power for industrial process heating. Holtec stated that this approval reflects the rigorous and risk-informed approach the company has taken in advancing the Palisades project and marks a key step toward deploying 680 megawatts of clean, reliable energy through Units Pioneer 1 and 2.

In addition, the Palisades site also houses a single-unit pressurized water reactor with an installed capacity of 805 megawatts, which was shut down in 2022, and Holtec is currently making every effort to advance the restart and grid reconnection of this older unit.