Inventory data can change for 3 main reasons:
- The amount of radioactive waste may change. Radioactive waste accumulates as Australia produces more of it and decays as it ages.
- Sources of the data may change. For example, ARWA may report data volunteered by waste holders or use other information sources (such as the Joint Convention).
- Data that waste holders provide may change. This is usually either due to waste holders:
- changing assumptions made about their waste and waste generation
- further characterising their waste
- improving their waste characterisation processes.
Radioactive waste generation and decay
As radioactive materials decay over time, their radioactivity decreases. This can lead to reclassifying some waste volumes, for example from LLW to exempt waste (EW). Fluctuations in the demand for medical isotopes, industrial activities and research projects can also lead to changes in how much waste is generated.
Changing assumptions about radioactive waste
Waste holders may change how they estimate their radioactive waste, including assumptions about their future activities. We discuss changing assumptions in more detail in Waste holder insights.
Waste characterisation
Waste characterisation is a critical part of managing radioactive waste. The characterisation process measures, identifies and quantifies radioactive waste’s properties, including:
- radiological – radionuclides, their activity levels and decay characteristics
- chemical – includes identifying hazardous materials and any other contaminants
- physical – dimensions and density.
Sometimes calculations and models supplement the characterisation process, particularly if measurement data isn’t available.
Understanding this information supports safety, compliance and environmental protection.
Waste characterisation might happen when:
- limited information is available on a waste stream and the waste holder wants to understand the waste better and manage it more effectively.
- new waste is produced and the waste holder needs to measure and classify it
- radioactive waste has decayed and the waste holder wants to update their understanding of the waste in its current state.
We recommend that waste holders characterise their radioactive waste throughout the waste life cycle, from generation to storage and treatment or conditioning. Accurate waste characterisation helps ARWA to plan for safe radioactive waste disposal in the future.