The applicant for two small reactors in Michigan wants to build permanent retaining walls before the regulator decides whether it may build anything, and the environmental finding it needed arrived on Monday

Concrete that stays is not usually poured on spec.

The Nuclear Regulatory Commission published an environmental assessment and a finding of no significant impact on Tuesday, covering an exemption that SMR, LLC has requested on behalf of Palisades SMR, LLC. The exemption would let the company install support of excavation walls at the Palisades Energy Center in Covert, Michigan, before the Commission has issued a limited work authorisation. The walls would be permanent. They stay in the ground after construction finishes.

The proposed plant is a pair of SMR-300 units called Pioneer Units 1 and 2, to sit alongside the operating Palisades Nuclear Plant.

What the application actually asks for

SMR, LLC filed the first part of a phased construction permit application by letter dated 31 December 2025. The Commission accepted it for docketing on 13 February 2026.

That first part contains a request for a limited work authorisation, three separate exemption requests, and a full environmental report. The Commission is still writing the environmental impact statement for the project as a whole, and expects a draft to go out for public comment in the autumn.

This exemption is one of the three, and the applicant has asked for it to be decided on its own, ahead of the rest.

The regulation it seeks relief from is the one that says what may not be built before a work authorisation exists. Three wall types are proposed: reinforced concrete panel diaphragm walls, soldier pile soil mixed walls, and perimeter cutoff walls, with tieback anchors where the design needs them. The applicant says none of them supports the containment structures, the reactor auxiliary building or the intermediate building, and that none of them serves radiological health or safety. They are there, it says, so that people can work safely in the excavation.

The risk sits with the applicant

The Commission put that in terms, and the sentence is the one to keep.

Granting the exemption would not commit the Commission to issue either a work authorisation or a construction permit. Palisades SMR would carry out the work assuming the risk that its permit application is later refused.

The applicant's case for why the timing matters is a schedule argument rather than a safety one. Waiting until a work authorisation is issued, it says, would push back the below grade parts of the containment structures, the reactor auxiliary building and the intermediate building, adding time and construction cost. It says a delay would also put back 680 megawatts of what it describes as a reliable lower cost energy supply for Michigan, and that the cost of delaying commercial operation would be substantial. Those are the applicant's figures and the applicant's characterisations.

The finding, and how the staff reached it

The staff looked at thirteen categories and found no significant impact in any of them: land use, terrestrial and aquatic resources, threatened and endangered species, air quality, nonradiological health, nonradioactive waste, socioeconomics, surface water, groundwater, historic and cultural resources, radiological human health, and radiological waste management. A separate consultation under the National Historic Preservation Act returned a determination of no historic properties affected.

The reasoning on the no-action alternative is set out conditionally.

Denying the exemption would avoid the environmental impacts described in the assessment. It would avoid them, the staff wrote, unless the Commission later grants the work authorisation, in which case the same impacts are delayed rather than avoided and are incurred during that work instead. The staff added that a denial and the resulting delay to excavation could bring project costs and schedule delays. On that basis it concluded that no alternative both meets the need for the action and is environmentally preferable to it.

The exemption itself has not been granted. What Tuesday's notice does is finish the environmental step in front of that decision.