Feasibility Study: Gamma Spectrometry of High Activity Waste drums

Scope:

The future “CIGEO” facility, managed by the French Nuclear Waste Agency, is designed for long-life medium and high activity waste final disposal.
Once built, nuclear waste from all of French industry will be shipped to this facility.
Some drums will go through a full characterization process, for various quality and safety checks.
Around 150 types of drums containing about 200 different radionuclides are expected.

Need to precisely assess the footprint required for spectrometry measurements.
- Large concrete walls are mandatory for radiological protection, making civil work a significant cost for the future facility.
- Space optimization and forecast is key in this project.
Measurement range: from Intermediate Level Waste (ILW) to High Level Waste (HLW), up to 10¹⁵ Bq at ¹³⁷Cs, without detector saturation.
- Ensure that the waste activity level remains in the range allowed by the license of the storage facility.
- Declare the activity to the National Agency of Radioactive Waste for costs and scenario forecasts.
Final study report to be delivered within two months.

From the list of around 150 types of drums, 12 “bounding” geometries have been defined, taking into account variety in terms of:
- Composition and density.
- Shielding.
- Internal volume and shape.
Parametric studies using MCNP calculation code have been performed.
- For each bounding geometry, one calculation is performed per emitter radionuclide.
- Automation of the calculations allowed about 600 calculations to be performed in less than one month.
- Studying up to four measurement configurations in one model made efficient use of the allowed calculation time.
- This approach allowed a large flexibility in the analysis.
A specific Excel sheet has been delivered for analysis of results which allows the customer to “build” the detector response of the desired drum, with clear display of the results.
The measurement configuration has been optimized for the most penalizing drum to be measured using advanced MCNP calculation techniques to allow convergence with highly collimated detectors.

Complexity problem reduction achieved by the CANBERRA M&E Team for planning and cost optimization.
Definition of an adaptive measurement system with guarantee of measurement ability for every expected drum.
Excel sheet reports can be re-used by the customer for further analysis in the next stages of the project without additional cost.
Civil work cost assessment can be performed based on reliable information.
On Time Delivery of the final report in spite of the tight schedule thanks to responsiveness of the CANBERRA M&E Experts from various countries.