In 2011, the U.S. cancelled funding for the Yucca Mountain Nuclear Waste Repository in Nevada. This meant that U.S. utilities and the U.S. federal government were left without a long term storage site for spent nuclear fuel which take thousand of years to decay. It is estimated that such a facility will not be available until 2050 at the earliest.
A University of Nebraska–Lincoln (UNL) engineering faculty research team recently received a three-year eight hundred thousand dollar grant from the U.S. Department of Energy to develop a new barrier material that would make the deep geological disposal and storage of spent nuclear fuel much safer.
Jongwan Eun is an assistant professor of civil and environmental engineering at UNL. He said “Long-term degradation of these types of spent fuel can require they be stored more than 10,000 years. That’s a surprising time period. And with concerns about the materials that have been used for years, we have to meet this environmental challenge.”
Eun went on to say, “They are piling spent fuel next to the power plants. There is pressure to develop a permanent solution for radioactive waste sequestration, and the DOE is spending research money to investigate the fuel cycle — generating the material, operating and disposal. Our project is developing a new material for disposal safely and looks to meet the environmental challenge, as well.”
Eun is collaboration with Seunghee Kim who is an assistant professor of civil and environmental engineering; Yong-Rak Kim who is a professor of civil and environmental engineering at Texas A&M University; and Sandia National Laboratories. Seunghee Kim said, “We have been working on other energy issues for years, so it was only natural that we look at the issue of geological storage of spent nuclear fuel.”
The current protocols for disposal of spent nuclear fuel have not changed in decades. This includes the way in which disposal sites are supposed to be constructed. Construction of a repository typically requires tunneling deep into the Earth to build a bunker that will be used to house metal drums filled with spent nuclear fuel. Some of the spent fuel is heated by radioactivity to a temperature of about four hundred degrees Fahrenheit. These temperatures can create cracks in the materials such as bentonite currently used to store nuclear waste.
The Nebraska researchers are investigating the addtion of an inorganic microfiber, such as glass, to the bentonite to create a less-permeable and more-durable and heat-resistant material to store the spent fuel. Eun said, “For other infrastructure projects — like the construction of large buildings or paving roads — we mix inorganic fibers into concrete or soils and give the material mechanical and engineering properties. This is a new idea for a spent-fuel waste disposal facility.”
As of December of 2019, the U.S. had fifty-eight nuclear power plants operating in twenty nine states including the Cooper Nuclear Station near Brownville, Nebraska. In October of 2016, the Omaha Public Power District shut down the Fort Calhoun Nuclear Station north of Omaha, Nebraska. That facility won’t be fully decommissioned until 2058 at the earliest.
In the U.S., spent fuel from nuclear power plants is supposed to be stored thousands of feet underground. One of the major concers about storing nuclear waste underground in Nebraska is that the possibility of leaching of radioactive spent fuel into the massive aquifer that lies under the state. Seunghee Kim said, “We want to make sure we put something strong and durable between this fuel and Nebraska’s groundwater system. We want to make sure that it will be OK and protect all of us in the future.”