Nuclear power has been getting a hard time of late and outside observers would be well in their rights to assume that this once lauded energy source is dying out as recent events have shown that the dangers outweigh the benefits. Japan is trying to pursue other energy sources, many European countries are gradually decommissioning their reactors, and the US is also letting their nuclear industry slip into decline in favour of alternative energies.
But wait, maybe there is hope for the nuclear industry, after all we know it provides vast amounts of cheap energy, we just have to find a way to reduce the risks of radioactive leaks and reduce the amount of radioactive waste.
Enter the metal-organic-framework (MOF) ZIF-8.
MOFs are crystalline, porous materials in which a metal centre is bound to organic molecules by mild self-assembly chemical synthesis. A team of Sandia researchers discovered that MOFs can be used to capture and remove volatile radioactive gas from spent nuclear fuel. Chemist Tina Nenoff of Sandia's Surface and Interface Sciences Department, said that “this is one of the first attempts to use a MOF for iodine capture.”
Iodine is highly radioactive and has a huge half-life of 16 million years (which means that it takes 16 million years for the number of decaying isotopes to decrease by half), so the Sandia team decided to focus their research on removing that compound from the spent fuel. They studied various known materials to determine the most efficient mineral for trapping iodine. Their results indicated that zeolite, loaded with silver, worked best. "Silver attracts iodine to form silver iodide," Nenoff said. "The zeolite holds the silver in its pores and then reacts with iodine to trap silver iodide."
But silver is expensive, and therefore the team decided to engineer a material that would work like zeolite but without the need for silver. They explored how zeolite absorbs iodine and then set out to create the MOF ZIF-8. "We investigated the structural properties and how they work and translated that into new and improved materials," Nenoff said.
ZIF-8 can separate individual molecules of iodine from gaseous mixes of many different molecules. The MOF and trapped iodine can then be processed into glass waste for long term, secure storage.
The process could be applied to nuclear processing or as a method for cleaning up nuclear reactor accidents. Nuclear reprocessing separates the spent, radioactive components from used fuel rods in order to recover the pure fissile material and create fresh fuel for nuclear power plants. This process is common practice in countries such as France, Russia and India, but would be far more effective, and also cheaper with the new MOF technology.
Hopefully with the MOF ZIF-8 nuclear reactors can be made much cleaner and safer, the fears can be negated and we can continue producing this abundant form of clean energy, at least until better sources are more readily available.
By. James Burgess of Oilprice.com