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Source term evaluation model for high-level radioactive waste repository with decay chain build-up
Manish Chopra1, Faby Sunny1, R B Oza1
1a Radiation Safety Systems Division, Bhabha Atomic Research Centre , Mumbai , India.
Summary
A new model estimates radioactive waste leaching, incorporating decay chains for accurate impact assessments. This approach prevents underestimation of radiological risks in waste repositories.
Area of Science:
- Nuclear Engineering
- Environmental Science
- Radiochemistry
Background:
- High-level radioactive waste repositories pose long-term risks due to long-lived radionuclides.
- Radioactive decay chains can lead to the build-up of activity over time.
- Accurate source term modeling is crucial for radiological impact assessment.
Purpose of the Study:
- To develop a source term model for high-level radioactive waste repositories.
- To incorporate radioactive decay chain build-up into the model.
- To provide realistic estimates of radionuclide leaching and radiological impact.
Main Methods:
- Developed a source term model based on the two-component leach flux concept.
- Utilized Bateman decay chain build-up equations to model progeny ingrowth.
- Applied the model to various radionuclides within decay chains (4n to 4n+3 series).
Main Results:
- Estimated the activity of parent and daughter radionuclides leaching from the waste matrix.
- Considered scenarios with initial parent-only and parent-daughter presence.
- Demonstrated the importance of in situ daughter production for realistic source term evaluation.
Conclusions:
- Inclusion of decay chain build-up is essential for accurate radiological impact assessment.
- The developed model is a valuable tool for evaluating source terms in waste repositories.
- Realistic estimates require accounting for in situ production of daughter radionuclides.
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