The gray barrel that sits in the basement of Clemson’s Olin Hall might resemble a large water heater, but it’s actually a rare scientific instrument called a high-temperature melt calorimeter. The coveted instrument, which is one of five in the country, will help on-campus researchers create a more sustainable material to store nuclear waste.
That material could save millions of taxpayer dollars.
“The calorimeter is a significant instrument not only for Clemson but for the entire state,” said Rajendra Bordia, chair of the materials science and engineering department. “Its capabilities will allow us to conduct cutting-edge research that creates new knowledge and helps us develop the clean-energy solutions that will benefit generations to come.”
One of the researchers using the calorimeter is Kyle Brinkman, a mineral sciences and engineering professor. In 2014, he was awarded an $800,000 grant from the Department of Energy to develop a crystalline ceramic material to contain nuclear waste.
Brinkman and a team of researchers are creating the material from naturally occurring minerals, which can endure for millions of years. The researchers are currently testing minerals that can withstand cesium – a radioactive isotope that produces most of the gamma rays emitted from high-level nuclear waste.
High-level nuclear waste is spent fuel from nuclear reactors after producing electricity, according to the U.S. Nuclear Regulatory Commission. High-level waste must be stored underground for thousands of years, because it emits large quantities of deadly radiation. During storage, nuclear waste decays and emits gamma rays, which can break down containers over thousands of years and potentially cause radiation leaks.
Currently, high-level waste is contained by glass. “Glass is a proven material for incorporating high-level waste. However, over millions of years, it is believed that ceramics would be even better,” Brinkman said.
To create the crystalline ceramic material, Brinkman and researchers have used computer simulations to observe and document how certain minerals react to conditions similar to radiation. But they needed something more accurate.
In 2014, Brinkman applied for and received a $325,00 grant from the Department of Energy. In 2015, Clemson provided the remaining fund, and Brinkman purchased the instrument for $400,000. The calorimeter was installed in May.
Now, researchers are able to physically record temperatures. They pour metal oxide (ceramic) powder into the calorimeter, where it decomposes and releases heat. The temperatures are then recorded as a line graph on a nearby computer.
“The calorimeter determines the formation energies of the materials being tested,” said Brinkman. “Minerals are very stable materials existing for hundreds of millions of years in the earth’s crust. Measurements of our synthetic materials formation energies as a function of composition helps us design new, stable materials.”
The process to develop the crystalline ceramic material could take between 10 and 20 years, according to Brinkman. So far, only one mineral – hollandite – shows promise. The mineral, which is found and transported from the Italian Alps, “has tunnels appropriate to incorporate and immobilize cesium ions,” Brinkman added.
If developed, the new material could save millions of dollars once it’s created.
For now, the Department of Energy stores high-level nuclear waste at 121 facilities, including Oconee Nuclear Station. High-level nuclear waste is stored in pools of water reinforced by concrete and steel so that it can “cool” for at least five years.
The waste is then relocated to a dry cask – a concrete cylinder reinforced by a steel lining – and later melted into glass, a process called vitrification. After, the glass is stored in the Department of Energy’s Waste Isolation Plant, a geological repository in New Mexico.
Low-level nuclear waste, which is radioactive clothing and equipment, is stored in concrete and steel containers until the radiation completely decays. The waste is then disposed of at one of the four specialty facilities in the U.S.
The U.S. has spent about $4.5 billion to store nuclear waste. That cost is going to reach more than $20 billion by 2021, according to the Department of Energy.
Brinkman is focused on the pores of the material, changing their size and arrangement to see what designs are most stable. The correct design could allow for the disposal of both types of waste and eliminate the need to separate the two.
“In economic terms, if one can increase the waste loading of a material, there will be less needed to store the existing waste. This will certainty translate into cost savings,” Brinkman said.
While Brinkman and his team of researchers complete their efforts, others will be able to use the calorimeter to produce ceramic materials for other industries.
“Calorimetry is a versatile technique for studying the energetics of formation, solid solution mixing, phase transition and order and disorder in ceramics,” said Brinkman. “Ceramics play an essential role in a number of energy conversion systems.”
Those systems include materials for next generation fuels and power plants, solid oxide fuel cells, Li-air batteries, oxygen separation and permeation membranes for oxygen production, partial oxidation of methane and clean coal production.
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