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Material Balance Evaluation

Working Group

Terms of Reference


To provide the safeguards community with reference and expert advice on Material Balance Evaluation (MBE) in bulk handling facilities, including the determination of the related uncertainties as well as their interpretation.
Since bulk handling facilities are handling significant amounts of Nuclear Material in different forms, the application of safeguards in these facilities requires a robust methodology for in-process inventory verification and MBE within each Material Balance Area. Sharing best practices and knowledge within the safeguards community (in particular operators and inspectorates) will be the main goal of the WG.
This WG shall also contribute to international reference through guidelines and ESARDA publications and will provide a basis for relevant education and training.


To achieve the above objectives, the Working Group will:
1. Make an inventory of and analyse the existing methodologies and regulations for MBE;
2. Identify statistical assumptions for MBE;
3. Identify and review measurement uncertainty tools (instrumentation) and methodologies;
4. Review methodologies for calculation of global/cumulated uncertainties for MBE;
5. Propose examples of calculation tools and suggest developments;
6. Identify best practices to improve the MBE accuracy;
7. Identify best practices for the monitoring of the MBE by operators & inspectorates;
8. Study Near Real Time Accountancy (NRTA) concepts. Compare this approach with classical MBE, their advantages and shortcomings. Evaluate best practice for implementation;
9. Consider NRTA to investigate detection and interpretation of discrepancies thanks to machine learning algorithms.


To address the above tasks, the Working Group will:
1. Identify and cooperate with the appropriate ESARDA Working Groups (such as DA and NDA) and other international actors involved in MBE;
2. Maintain contacts with or awareness of other international initiatives in the area of MBE or associated topics such as International Target Values (IAEA Working Group);
3. Focus on technical and cost efficiencies and suggest the optimum;
4. Promote Safeguards by design, to enhance MBE and, in particular, through NRTA.

MBE Useful Links

MBE CIRCA BC Document Repository (credentials required)