HWBRIEF
The NRC granted a narrow exemption for excavation support walls at the proposed twin unit plant in Michigan, not the broader construction authorization Holtec is awaiting.
The US Nuclear Regulatory Commission has cleared Holtec to install permanent support-of-excavation and cutoff-wall systems at the Palisades site in Michigan for its proposed small modular reactor (SMR) twin-unit project, per a Federal Register notice issued 28 August 2026. The action, reported by World Nuclear News, authorizes Pioneer units 1 and 2 (a combined 680 MW Holtec is targeting) to install permanent diaphragm walls, soldier-pile soil-mix walls, and perimeter cutoff walls that stabilize the excavation before any reactor building begins. The walls will be "retired in place" once permanent structures go in, with the annulus backfilled to grade. Holtec must perform geologic mapping during excavation and account for the retired walls in later soil-structure interaction analyses.
The action is narrower than that: it authorizes only the SOE and cutoff-wall work, not the wider set of site-preparation activities the Limited Work Authorization (LWA) would unlock. Holtec applied for the LWA in December 2025 and the NRC docketed it in February. That decision is still pending.
Before granting the exemption, the NRC issued an Environmental Assessment and Finding of No Significant Impact for the authorized work, concluding no detrimental effects on environmental quality. The Palisades site, Holtec said in a statement, also hosts an 805 MW pressurized water reactor that closed in 2022 and that the company is separately working to restart, on a parallel licensing track.