Canadian inter-laboratory organically bound tritium (OBT) analysis exercise
Journal of Environmental Radioactivity
|September 16, 2015
Summary
Measuring organically bound tritium (OBT) in environmental samples is crucial for CANDU reactor safety. An inter-laboratory study found current OBT analysis methods generally acceptable, but a standardized methodology is needed.
Area of Science:
- Nuclear Science and Engineering
- Environmental Monitoring
- Analytical Chemistry
Background:
- Tritium emissions from CANDU reactors are a significant safety concern.
- Standardized methods for measuring organically bound tritium (OBT) in environmental samples are lacking.
- The Fukushima accident highlighted the need for data-driven risk assessments.
Purpose of the Study:
- To evaluate current OBT analysis methods used by CANDU Owners Group (COG) members.
- To assess the variability and uncertainty in OBT measurements in environmental samples.
- To identify areas for improvement in OBT analysis methodology.
Main Methods:
- An inter-laboratory comparison study was conducted.
- Three dried environmental samples (fish, Swiss chard, potato) were analyzed for OBT.
- Standard OBT analysis techniques including combustion, distillation, and counting were employed.
Main Results:
- Variations in measured OBT activity concentrations between laboratories were less than 20%.
- Total uncertainty in OBT measurements ranged from 11% to 17%.
- Current OBT analysis methods for combustion, distillation, and counting are generally acceptable for dried samples.
Conclusions:
- Existing OBT analysis methods are largely suitable for dried environmental samples.
- A complete, consensus OBT analysis methodology is required, encompassing all steps from sample preparation to counting.
- Further studies with low-level tritium samples are recommended to fully validate current methods.
