The Energy Institute - The University of Texas at Austin

Nuclear reactors today are safe, reliable, with a life-cycle carbon footprint at most 10% – 15% of comparable generators of electrical energy (primarily from the carbon footprint associated with construction and materials). As such, it would seem an ideal approach to electrical energy generation in a carbon-constrained environment.

However, the question of what to do with spent fuel remains unsolved in the United States. At present, local storage is the only option, through pools and eventually into dry casks. The Department of Energy is liable under the law for receipt of spent fuel. Its inability to accept spent fuel increases its liability, with an extrapolation to astronomical proportions if no solution is soon found.

The solution currently under law is to transfer spent fuel from existing nuclear reactor sites to a retrievable repository, current Yucca Mountain in the state of Nevada. This path seems ever more improbable, given recent statements from the current U.S. Administration, and the ardent opposition from the State of Nevada. Further, such a process is itself inherently unwise. Spent fuel contains a great deal of energy, and to simply bury it underground risks losing a valuable energy resource, something that the U.S. can ill afford.

Briefly put, spent fuel contains three categories of materials: transuranics produced through the reactor burn cycle (Am, Np, Pu, Cm); fission products produced through the reactor burn cycle (Sr and I); and uranium 238 and about a percent of uranium 235 that was not consumed through the reactor burn cycle. The first component is fissionable, and could be formulated into a fuel for current light water reactors, and eventually for fast spectrum reactors. The second component has a high heat load and toxicity, but concomitantly, a relatively short half life (30 – 40 years). The third component has a significantly higher fissionable uranium 235 than found naturally (0.7%), and could add to potential fuel for light water reactors.

While it is true that the transuranics are fissionable, and therefore suffer from proliferation concerns, conversion into a weapon would be a formidable task, and an unlikely scenario even assuming an adversary could somehow gain control of the material.

Separation of spent fuel into these components would appear to be a natural approach. Leaving aside the Am from the transuranic materials would enable conversion to reactor fuel that could be done in a glove box. The fission products could be buried in concrete, left for a hundred years, and then disposed of with no radiation or heat load issues because of their relatively short half life. What is left over, and required to sequester in an underground environment would amount to about one percent of the heat load and toxicity of spent fuel. It could easily be placed in an underground salt repository (e.g. WIPP) where it would remain encapsulated for eternity.

This scenario appears enticing, but flies in the face of current U.S. policy and capability. Thirty years ago, President Carter ended the U.S. reprocessing program. In the subsequent three decades, there has been no funding available for radio-chemistry, leading to an absence of capability for separations chemistry. The combination of the two have created an impossible situation for the U.S., in contradistinction to other countries (e.g. France, Japan, and the United Kingdom) who have continued their reprocessing programs, not to mention those who have proliferated nuclear weapons through reprocessing, unperturbed by U.S. reprocessing policy.

If nuclear energy is to have resurgence in the U.S., its reprocessing policy must change. A major initiative in separations chemistry is required, with a concomitant support structure for radio-chemistry. Universities should be encouraged to start up major programs in radio-chemistry, and support and equipment provided to train a new generation of researchers while there are still a few “grey heads” to lead and advise.

The U.S. abhorrence of reprocessing has yielded little value, and harmed our nuclear energy posture. It should be revisited in the context of a major national program for recycling spent fuel.

Together, these two initiatives could address the self-imposed nuclear reactor spent fuel crisis in the U.S., and remove the last obstacle to a renaissance in nuclear fission energy.