Keeping nuclear power safe

Nuclear energy is clean, powerful, affordable, and zero-emission. A new study uses the Canadian Light Source (CLS) at the University of Saskatchewan to help ensure that waste from nuclear power plants remains safe and secure for thousands of years to come.
The project, led by Dan Kaplan and Dien Li, researchers at the Savannah River National Laboratory in South Carolina, looks at storing iodine, which is generated during uranium use, including in nuclear power generation.
Among the challenges of iodine management is its slow rate of decay—it has a half-life of 16 million years. Iodine is volatile and highly mobile in the environment, making containment critically important in nuclear waste management.
Currently, nuclear waste disposal sites use Ag-zeolite to sequester iodine from nuclear waste streams, which is then encased in concrete to prevent leaching.

>Read more on the Canadian Light Source website

Image: Samples of different formulations of cement that were tested for their ability to immobilize radioiodine.

The power of Metal-Organic Frameworks

Trapping nuclear waste at the molecular level

Nuclear power currently supplies just over 10% of the world’s electricity. However one factor hindering its wider implementation is the confinement of dangerous substances produced during the nuclear waste disposal process. One such bi-product of the disposal process is airborne radioactive iodine that, if ingested, poses a significant health risk to humans.  The need for a high capacity, stable iodine store that has a minimised system volume is apparent – and this collaborative research project may have found a solution.

Researchers have successfully used ultra-stable MOFs to confine large amounts of iodine to an exceptionally dense area. A number of complementary experimental techniques, including measurements taken at Diamond Light Source and ISIS Neutron and Muon Source, were coupled with theoretical modelling to understand the interaction of iodine within the MOF pores at the molecular level.

High resolution x-ray powder diffraction (PXRD) data were collected at Diamond’s I11 beamline. The stability and evolution of the MOF pore was monitored as the iodine was loaded into the structure. Comparison of the loaded and empty samples revealed the framework not only adsorbed but retained the iodine within its structure.

>Read more on the Diamond Light Source website

Illustration: Airborne radioactive iodine is one of the bi-products of the nuclear waste disposal process. A recent study involving Diamond Light Source and ISIS Neutron and Muon Source showed how MOFs can capture and store iodine which may have implications for the future confinement of these hazardous substances.

Long duration experiments reach 1,000th day

… it was on Diamond’s Long Duration Experimental (LDE) facility, on beamline I11

The experiment, led by Dr Claire Corkhill from the University of Sheffield, has used the world-leading capabilities of the beamline to investigate the hydration of cements used by the nuclear industry for the storage and disposal of waste.

“Understanding the rate at which hydration occurs in cement, a process that can take anywhere up to 50 years, is very important to help us predict the behaviours of cement in the long term,” explained Dr Corkhill.

“These cements are being used to safely lock away the radioactive elements in nuclear waste for timescales of more than 10,000 years, so it is extremely important that we can accurately predict the properties of these materials in the future. The unique facility at Diamond has allowed us to follow this reaction in situ, for 1000 days, and the data is already allowing us to identify particular phases that will safely lock away radioactive elements in 100 years’ time, something we would otherwise not have been able to determine.”

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