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Minnesota granite could be a replacement for Yucca Mountain repository

The Minnesota sites are especially effective for nuclear-waste storage because of low water content and our lack of seismic activity.

Granite is a tough, impermeable combination of silicon and feldspar.

The fact that the Obama administration has abandoned the national project to store nuclear waste in a facility at Yucca Mountain in Nevada presents Minnesota with a large business opportunity in its granite deposits.

Minnesota is situated on the southern edge of the Canadian Shield, where basement rock is close to the surface. Shields  have relatively few layers of sedimentary rocks like shale from which came most of the earth’s oil and gas deposits. To our west, the basement rock dips down to form the Williston Basin, which includes the western Dakotas, eastern Montana, and Saskatchewan. Basins have room for deep sedimentary layers that can contain reservoirs of fossil fuels.

As if to compensate for our lack of oil riches, nature provided Minnesota with substantial and useful mineral deposits, especially the world-class iron ore reservoir on the Iron Range. Most of that ore is gone, having supplied the steel that framed many of America’s buildings and machines.

But in a band meandering from southwest to northeast, adjacent to the ancient Archean granite of Minnesota’s Iron Range, lie large deposits of the precious platinum group metals (PGMs) together with nickel, copper, gold and silver. Many of these minerals contain sulfur compounds, and their exploitation is awaiting more analysis of potential mining hazard to adjacent ground waters.

Potential multibillion-dollar industry

Minnesota is well endowed with another mineral, not precious, but widely used for buildings, bridges, paving and countertops: granite, a tough, impermeable combination of silicon and feldspar. There is another potential use for granite: encapsulating nuclear waste. Thanks to some rigid and in my opinion technically ignorant Nevada politicians, and our nation’s annual need to store thousands of tons of spent nuclear fuel, our granite could become a multibillion-dollar industry in northern Minnesota.

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One tenth of a cent per kilowatt hour (kwh) generated by our 100 nuclear power reactors is placed in a fund to provide geologic storage of the fuel waste generated by those reactors. This waste material is currently stored in water pools and in steel and concrete casks at our reactor sites, awaiting transfer to geologic storage.

The storage fund now exceeds $25 billion, half of it already spent to build the long-planned storage facility in Nevada’s Yucca Mountain Ridge. Pressure from Nevada officials caused President Obama to cancel the project and begin its dismantling.

Sandia National Laboratories was commissioned to study America’s geology for an alternative site. Sandia’s report notes that granite’s properties as a chemically and physically stable rock, with low permeability, would “strongly inhibit” radiation from reaching the outside environment if waste canisters leaked. The National Academy of Sciences has also concluded that “geologic disposal remains the only scientifically and technically credible long-term solution available to meet safety needs.”

Three sites in northern Minnesota

Three of the most promising U.S. granite sites identified in the Sandia report are in northern Minnesota. The Minnesota sites are especially effective because of low water content and our lack of seismic activity.

The other good site is in Vermont’s granite, but Vermont officials have already vetoed the idea, stating that “it should be placed in the middle of nowhere.” Meaning Minnesota.

The concerns in Nevada and Vermont are apparently the result of radiation fear. The average U.S. resident receives approximately 300 annual millirems (mrems) of radiation from natural sources like radon, cosmic rays, airline flights, and eating foods like bananas and nuts, which contain potassium. This radiation has occurred since humans have been on earth, and it doesn’t hurt us, or humans would not exist. Persons who work in industries with higher radiation risk are allowed 5 rems/year, or 15 times the normal dose.

The individual-protection standard for geologic storage facilities sets an overall additional dose limit of 15 millirems per year for residents living in the vicinity of a national nuclear repository during and up to 10,000 years after the repository closes. 15 mrems is about equal to the dose received from two round-trip domestic airline flights. After 10,000 years through the period of geologic stability (out to 1 million years) the individual-protection standard is set at 100mrem/yr, a very safe level.

Opening a Yucca Mountain replacement facility in northern Minnesota is a multibillion-dollar business opportunity  with no significant risks to Minnesota’s people and environment. It’s an opportunity worth our consideration.

Rolf Westgard is a professional member, Geological Society of America. He frequently teaches in the University of Minnesota Lifelong Learning program. 

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