Xcel seeks change in Prairie Island nuclear waste storage

Two giant concrete silos sit behind a placid river and fall trees.
The Prairie Island Nuclear Generating plant looms in the distance beyond a lock and dam on the Mississippi River near Red Wing, Minn., in October 2019.
Evan Frost | MPR News 2019

Xcel Energy is asking state regulators for permission to change how it stores radioactive waste at its Prairie Island nuclear plant in Red Wing, Minn.

The Minneapolis-based utility says it’s not seeking to store more spent nuclear fuel at the plant than the amount it was authorized in 2009. But Xcel wants flexibility to use a different type of storage cask as long as the design is approved by the federal Nuclear Regulatory Commission.

Changing the storage technology likely would cut costs and make it easier to transport the waste to a future storage site outside of Minnesota, said Pam Gorman Prochaska, Xcel's director of nuclear regulatory policy.

“That's really the motivating factor behind this change request,” she said. “It's saving our customers money, and it's the ability to move the fuel off site sooner.”

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Xcel’s request comes amid ongoing debate over what to do with growing stockpiles of spent fuel at the nation’s nuclear reactors, which can remain radioactive for thousands of years.

The federal government's past efforts to establish a permanent storage site at Yucca Mountain, Nev., stalled in the face of local opposition. The Biden administration recently announced plans to look for interim storage sites in communities that agree to accept it.

Meanwhile, a private company recently received approval from the Nuclear Regulatory Commission for an interim storage site in Texas, but it’s facing opposition from political leaders. A second interim storage site in southeast New Mexico is also seeking NRC approval.

Xcel has said its two nuclear plants in Minnesota, at Prairie Island and Monticello, are key to achieving its goal of producing carbon-free electricity by 2050. Unlike fossil fuel-fired power plants, nuclear reactors do not produce direct carbon dioxide emissions, which exacerbate climate change.

Xcel plans to continue operating the Prairie Island nuclear reactors through the end of their current licenses, which expire in 2033 and 2034. The utility says it hasn't yet decided whether to seek an extension.

Monticello nuclear plant
Xcel Energy's Monticello Nuclear Generating Plant in June 2012.
Jennifer Simonson | MPR News 2012

Change of design

In 2009, the Public Utilities Commission authorized Xcel to more than double the amount of waste it stores at Prairie Island to 64 casks. Currently, 47 casks at the plant have been loaded with spent fuel, Prochaska said.

The casks used to store waste at Prairie Island are a bolted metal cask known as TN-40, chosen in 1989. Prairie Island is the last plant still using that design, Prochaska said.

Most plants in the U.S. — including Monticello — are using a system of welded steel canisters that slide into a concrete bunker, she said. 

Xcel says switching to a different cask design could allow the spent fuel to be transported to an off-site storage facility sooner. 

The two interim storage sites in Texas and New Mexico could accept the canisters, but are not authorized to accept TN-40 casks, Prochaska said.

Local impacts

The Minnesota Department of Commerce decided that Xcel’s request warranted a supplemental environmental review, because it represents new information and raises environmental justice concerns related to the nearby Prairie Island Indian Community.

Heather Westra, a consultant for Prairie Island’s tribal council, which has objected in the past to storing nuclear waste at the plant, said the tribe doesn’t have specific safety concerns about Xcel’s request to switch cask designs, but is hoping that the change will speed up the movement of waste off Prairie Island.

“Whether you put an additional 20 TN-40 casks or 20 type-to-be-determined, the material is still there,” she said. “And so the larger problem still exists that the material is there, and it's not going anywhere.”

Like other host communities, the tribe receives very little benefit from having a nuclear plant right next door, just 700 yards from the nearest homes, Westra said.

“This situation was not one of the tribe’s creation, but it's nevertheless something that the tribe is burdened with,” she said.


The public has until Jan. 3 to comment on the scope of the supplemental environmental impact statement on Xcel’s request.

Prochaska said a draft environmental impact statement will be completed early next year, and will be followed by additional public hearings before the Minnesota Public Utilities Commission decides on the request.

Xcel also is seeking to extend the Monticello plant’s license until 2040, and is requesting authorization from the Public Utilities Commission to increase the amount of spent fuel stored there. That process could take two years, Prochaska said.