Control of radioactive wastes from generation through treatment, conditioning, storage and disposal. Concentrating a radionuclide in a smaller stream changes its location, not its radioactive decay law.
A liquid or gaseous outflow containing radionuclides. Its measured inventory and treatment history are distinct from whether release is authorised under the applicable discharge controls.
Removal of contamination from a surface or material. The cleaning residues and wash solutions become part of the waste inventory.
Prevention of an unintended self-sustaining nuclear fission chain reaction in waste management. neutron absorbers, fissile-isotope dilution and their long-term geochemical retention are relevant; a cross-section comparison is not a criticality assessment.
Storage that allows short-lived radioactive constituents to radioactive decay before subsequent handling or discharge. A clearance or discharge decision still requires the applicable measurement and acceptance criteria.
Temporary retention of radioactive gas so that nuclear radioactive decay lowers the radioactive activity released. A guaranteed minimum residence time, an average residence time and a tank filling time are different design quantities.
Separation or transformation of contaminants in liquid waste. evaporation, ion exchange and chemical precipitation concentrate radionuclides into residues that need further management.
Transfer of dissolved contaminants to separable solids by precipitation, coprecipitation or surface uptake. The resulting sludge requires separation and conditioning; residual dissolved radioactive activity must be measured.
Removal of water vapour to concentrate mainly nonvolatile contaminants. Entrainment and volatile radionuclides can contaminate the condensate; a smaller concentrate volume does not guarantee a clean distillate.
Operations producing a stable waste form and suitable package, for example immobilisation in cement, glass or ceramic. Treatment residues and secondary wastes must be included in the waste inventory.
A waste form together with its container and any associated internal barriers prepared for handling, storage or disposal.
Immobilisation of radioactive waste in a glass matrix. glass composition, durability, secondary phases and the complete package affect performance.
Interaction of waste glass with water through ion exchange, network dissolution and alteration-product formation. Dissolved-element release need not equal the total extent of glass alteration.
Formation of new solids during glass alteration. Such phases can retain selected elements or consume dissolved network constituents, changing the apparent release and reaction rate.
A glass-durability test with a finite initially specified leachant inventory. Dissolved products, pH and alteration layers evolve, so the test does not maintain the same conditions as continuous fresh-water flow.
Element release departing from bulk glass proportions. Selective ion exchange, retention in an alteration layer, sorption and secondary precipitation can all produce noncoincident normalised solution releases.
A low continuing rate after alteration products or solution chemistry have slowed the initial reaction. It need not be zero or represent thermodynamic equilibrium of the original glass.
A hydrated, compositionally modified interfacial layer formed during glass corrosion. Its porosity, transport properties and continuing reactions can affect the residual alteration rate.
The dilute-solution dissolution rate at specified temperature, pH and composition, before dissolved reaction products suppress the chemical driving force. It is not a maximum across all temperatures and pH values.
A continuously refreshed leach test used to measure dissolution under controlled dilute conditions. At steady state the elemental normalised rate is . Varying helps identify solution-affinity effects.
Dissolution releasing glass constituents in their bulk proportions. Element-normalised releases then coincide if precipitation, sorption and analytical losses do not selectively remove released constituents.
The solution-released mass of an element divided by its initial glass mass fraction and the exposed glass area: . It has units of glass-equivalent mass per area; it does not alone establish congruent dissolution.
The physical and chemical form in which radioactive waste is immobilised for handling, storage or disposal. Its durability is distinct from that of its container and surrounding engineered barriers.
A waste form designed using durable mineral structures as hosts. A natural analogue motivates a design but does not substitute for tests of the actual radioactive composition.
A titanate host represented by . strontium can replace calcium; other ions require suitable charge balance.
A tunnel-structured titanate host, represented by , used to incorporate large cations such as caesium with appropriate charge compensation in a crystal.
A family of mineral-analogue ceramic waste forms. Different titanate phases accept different waste ions by solid solution; phase assemblage is tailored to the waste inventory.
A multiphase Synroc formulation with zirconolite, hollandite, perovskite and titanium-oxide phases. The mineral hosts distribute different radionuclides rather than requiring one lattice to accept the entire inventory.
Material containing radionuclides for which no further use is foreseen and which is subject to radiological control under the applicable framework.
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