Nuclear Waste Treatment
Zeocan Zeolite has an extremely high cation exchange capacity (CEC) and a particular affinity for heavy metal cations such as Strontium 90, Cesium 134/137 and other radioactive isotopes in solution. Zeolite acts as a molecular sieve and simply binds them into its 3D crystalline framework. As a silicate, zeolite reacts readily with cement and glass binding systems to safely contain and entrap radioactive waste in a cementituous matrix. Zeolites are resistant to nuclear degradation and are less expensive than traditional organic ion-exchange resins. Zeolites are used in abundance to remove radioactive elements from low-level waste streams from nuclear plants.
Significant properties of zeolite for nuclear waste treatment include the following: 1) High Cation Exchange Capacity (CEC) 2) Selectivity for Cesium and Strontium 3) Radiation Stability 4) Resistance to Mechanical Attrition 5) Cost Effective
Reactive Permeable Barriers (RPB) for Sorption of Radioactive Waste
A remediation effort using a permeable zeolite RPB to capture dissolved radioactive waste can be incorporated by two methods. Both methods offer the same high cation exchange capacity and low installation cost: 1) Selectively contain the contaminants that are percolating from shallow land burial sites of low-level radioactive waste by having the contaminant pass through an underground zeolite wall. The zeolite will hold the radioactive waste into its matrix while allowing clean water to pass through it. 2) Impede (slow down) the migration of radioactive leachate for a period of time to allow exchange or natural decay of radioactive ions. Fine mesh zeolite can be combined as a mixture with clay and other materials.
Two of the most spectacular radiation clean-up efforts using zeolite were after the accidents at the nuclear reactors at Three Mile Island and Chernobyl, Ukraine. Pollutants were removed with zeolite. The long half-life ions, typically cesium and strontium, were filtered out very efficiently, keeping these pollutants out of the food chain.