Reducing spent nuclear fuel

A group of scientists as students are developing nuclear fuel cycles that will recycle and dispose of North America’s growing inventory of high-level radioactive material.

The group - formed from scientists and students from Big Ten universities, the University of Chicago and the U.S. Department of Energy's Argonne National Laboratory - will base its studies in the Center for Advanced Nuclear Fuel-Cycles (CANF), a new initiative housed at Argonne. Co-directors at Argonne and the University of Wisconsin-Madison will lead the centre.

Nuclear fuel used in current reactors has enormous available energy. As the fuel is used to produce electricity, only a fraction of this available energy is consumed, generating a small quantity of high-level radioactive waste within the solid fuel.

Currently, most spent nuclear fuel is stored temporarily in secure, specially designed pools at commercial reactors around the country, or in leak-tight steel casks housed in above-ground concrete vaults. When space is full, the fuel could end up at a commercial temporary-storage facility in Utah, or perhaps at the proposed Yucca Mountain high-level waste repository.

But these storage options are short-term approaches to dealing with the back-end of the nuclear fuel cycle, says Michael Corradini, a UW-Madison professor of engineering physics and the centre’s co-director. "We hope to develop a 'sustainable' fuel cycle-that is, an efficient, cost-effective way to reuse current spent nuclear fuel and minimise its by-products," he says. "Advanced nuclear fuel cycles can be recycled as a source of available energy as demand for uranium increases."

Some countries, including Japan and France, currently reprocess their spent nuclear fuel using a process known as PUREX (plutonium and uranium recovery by extraction). The CANF team will seek to improve upon these separation and recycling processes. "The major difference is that we are looking for ways to successfully extract specific radioactive species for separate uses and separate disposal," says Corradini.

The researchers will tackle the problem in a number of ways. One initiative will use sophisticated computer models to perform comprehensive simulations to predict key physics processes. The group will collaborate with the U.S. Department of Energy Office of Science to apply those tools to the nuclear fuel cycle. In addition, scientists will develop flexible fuel forms, unique materials and advanced chemical separation processes, enabling them to establish a fuel supply system that minimises waste and the risk of proliferation.

A reduced proliferation risk is just one of the benefits of advanced nuclear fuel cycles, says Phillip Finck, deputy associate laboratory director at Argonne and the centre’s co-director. "They can significantly shorten the needed isolation time and reduce the amount of high-level waste housed in any repository," he says. "Ultimately, this should reduce the cost of the Yucca Mountain repository and may preclude the need for additional waste repositories."