Part 1 of 2 Parts
With thousands of tons of spent nuclear fuel waste stashed around the U.S. in nuclear reactor cooling pools and no facility for permanent disposal of spent nuclear fuel, I keep returning to the subject of dealing with nuclear waste. A typical nuclear reactor only burns a fraction of the uranium in its fuel rods before the energy-generating nuclear fission reaction is naturally quenched. What remains in the fuel rods is a mixture of uranium fuel and other radioactive elements generated by the fission process. It is possible to utilize some of the elements in the spent nuclear fuel to power newer reactors but extracting that fuel in a way that does not add to fears of nuclear proliferation is difficult.
Researchers at Texas A&M University have developed a simple method of separating out different elements of spent nuclear fuel without risking nuclear proliferation. The new method is based on a chemical reaction which is described in the February issue of the journal Industrial & Engineering Chemistry Research. The chemical reaction causes the formation of crystals that contain all the elements in the spent nuclear fuel. The elements are distributed uniformly in the crystals. The simplicity of the new recycling approach will make the conversion of the laboratory process to an industrial process possible.
Johnathan Burns is a research scientist in the Texas A&M Engineering Experiment Station's Nuclear Engineering and Science Center. He said, “Our recycling strategy can be easily integrated into a chemical flow sheet for industrial-scale implementation. In other words, the reaction can be repeated multiple times to maximize fuel recovery yield and further reduce radioactive nuclear waste.”
Energy is produced in a commercial nuclear power reactor via thermonuclear fusion. A heavy nucleus such as uranium is bombarded by neutrons which destabilizes it and causes it to break apart into smaller and lighter elements. However, the uranium can also absorb neutron and change into heavier elements such as neptunium, plutonium and americium. Some of these go on to breakdown into lighter elements.
As the reactor generates energy, there is a buildup of these lighter elements produced by the fission process. About half of these fission products are what are referred to as “neuteon poisons.” This means that they absorb neutron like the nuclear fuel which progressively reduces the number of neutrons being generated in the reactor which results in the end of the fission process.
Spent nuclear fuel rods contain leftover uranium, lighter fission byproducts and neptunium, plutonium and americium. The elements left in spent nuclear fuel are consider to be nuclear waste. The ultimate fate of spent nuclear fuel is to be permanently buried in a permanent geological repository whenever one can be constructed in order to prevent the highly radioactive waste to leak into the environment.
Burns said, “Nuclear waste is a two-pronged problem. First, almost 95% of the starting material of the fuel is left unused, and second, the waste we produce contains long-lived, radioactive elements. Neptunium and americium, for example, can persist and radiate for up to hundreds of thousands of years."
Please read Part 2 next