The Accelerator Transmutation of Waste System
One of the greatest obstacles facing nuclear energy is the highly radioactive waste which is generated during power production. In order for nuclear power to realize its full potential as a major energy source for the United States, as well as the entire world, there must be a safe and effective way to deal with this waste. While mined geological disposal is the method chosen by the U.S., it has been consistently stalled by a pervasive public perception that it is not a safe disposal technology. One of the primary reasons for this is the long life of many of the radioisotopes generated from fission, with half-lives on the order of 100,000 to a million years. Another reason is the feeling that weapons grade material in the repository would be easily obtainable by terrorist groups. Therefore, science must come the rescue in the form of new, more effective technology aimed at reducing the amount of long-lived radioactive waste and eliminating nuclear weapons grade material.

One new technology currently being developed at Los Alamos National Laboratory is the Accelerator Transmutation of Waste (ATW) System.

Introduction to the ATW

One method for dealing with high-level and transuranic radioactive waste is to "burn" the waste in an ATW system.
An ATW is a subcritical nuclear facility which uses a high energy, high proton beam directed onto a liquid lead or solid tungsten target. The spallation reaction, driven by the proton beam (from a linear accelerator), will create a high neutron flux in the vicinity of the target. The neutrons will be thermalized in a surrounding target/blanket system containing actinides and the long-lived fission products Technetium-99 and Iodine-129. The actinides will fission and the LLFPs will transmute into stable or short-lived species. An on-line chemical separation facility will remove the stable and short-lived isotopes, as well as the fission products produced in the blanket. At equilibrium, the ATW will incinerate one LWR's yearly production of higher actinides and the LLFPs 99Tc and 129I per year of operation. At the same time, the ATW will produce 274 MWe for sale to the grid.

Although the ATW is now only in the development stage, it is a new technology which promises a steady supply of electricity while significantly reducing the amount of storage capacity required for this country's nuclear waste. This alone should warrant further investigation into the possibility of an accelerator driven waste transmuter.



 

This figure shows a simplified side-view of the ATW system.

Most of the information presented in this article was found in the paper "Comparison of Accelerator-Based with Reactor-Based Nuclear Waste Transmutation Schemes" in Progress in Nuclear Energy July 7, 1994 written by W.C. Sailor, C.A. Beard, F. Venneri, and J.W. Davidson.
This document will try to give the reader a brief, but comprehensive, overview of the ATW. While many more detailed aspects may be left out, the author is presenting only the key features of the ATW System. If a more knowledgeable ATW reader is not satisfied with the way a particular subject is presented, feel free to edit or change it. The writer of this topic can be contacted at tfcarter@nuc.berkeley.edu, where the T is for Thomas.
The full contents of this research outline can be found at http://neutrino.nuc.berkeley.edu/designs/atw/ATWreport.html

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