Nuclear Waste Clean-up Breakthrough
Climate crisis. While alternative energy options grow, the nuclear option is also back on the table. In spite of the complexities of permitting, hazards of nuclear energy and challenges that the investment and construction timelines pose in the race for solutions, humanity's growing energy hunger may require reliance on this well-established greenhouse-gas-emissions-free technology.
One problem looms above all others, though, every time the nuclear question is raised. What about nuclear waste? A recent study by Professor Mercouri G. Kanatzidis at Northwestern University may promise some answers.Kanatzidis' team is the first to elucidate the potential of metal sulfides for treatment of nuclear wastes. Nuclear reactors use water for cooling. This results in large quantities of contaminated water which is difficult to handle, transport and store. Unfortunately, the radioactive contaminant, strontium, floats in a sea of sodium ions. 1 million sodium ions for each strontium ion. Existing treatment methods, such as metal oxides and polymer resins, confuse the two ions and must pull out the sodium with the strontium. The result? You guessed it: a still large quantity of waste.
Kanatzidis uses a metal sulfide he calls KMS-1. KMS-1 prefers the heavier and more highly charged strontium ion to the sodium ion. Therefore, it selectively binds strontium for removal from the liquid waste. Another bonus: the KMS-1 works in both acid and basic solutions, and across the whole range in between.
Questions remain for further research. The lab studies to date use a simplified strontium, sodium and calcium solution instead of real nuclear waste. Testing on actual nuclear waste streams and verification that the complexes formed are stable in those solutions is needed before questions of scale-up and economic viability are addressed. However, if this science offers a tool to the existing nuclear industry or helps to balance climate versus economics and growth equation, it could be a boon.
What is really interesting about the potential of this science? What is interesting is the via: from the European environmental protection agency. The nuclear card does indeed remain on the table.
The studies and results are described in a paper in the March 2008 Proceedings of the National Academy of Sciences entitled "Layered Metal Sulfides: Exceptionally Selective Agents for Radioactive Strontium Removal."