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By Joyce Nicolai
The transport of radioactive material has long relied on two important values known as A1 and A2. (Example in IATA DGR Table 10.3.4 and IMDG Code 2.7.2.2.1)
While these figures may not be familiar to everyone involved in dangerous goods transport, they are fundamental to how radioactive materials are classified, packaged and moved through the transport system.
Following more than a decade of international research and review, the International Atomic Energy Agency (IAEA) has completed a comprehensive review of these values as part of its ongoing work to update the Regulations for the Safe Transport of Radioactive Material (SSR-6). The proposed changes represent one of the most significant revisions to radioactive material transport requirements in many years and could influence industry practices for decades to come.
Understanding A1 and A2 Values
A1 and A2 values establish activity limits that determine which transport provisions apply to radioactive material consignments.
A1 values apply to special form radioactive material, such as sealed, non dispersible sources.
A2 values apply to all other forms of radioactive material.
Together with factors such as the radionuclide involved, its physical and chemical form, and the total activity being transported, these values help determine whether a consignment may qualify as:
- An exempt consignment.
- An excepted package with reduced regulatory requirements.
- A Type A package.
- A Type B package requiring a higher level of protection and regulatory control.
It is important to note that exempt consignments and excepted packages are not the same.
An exempt consignment falls outside most transport requirements because the activity or activity concentration is below the applicable exemption thresholds.
An excepted package remains a regulated shipment of radioactive material but benefits from reduced regulatory requirements because of its very low activity or limited hazard.
Why Were the Values Reviewed?
The existing A1 and A2 values were originally developed using scientific calculations known as the Q system. Since those calculations were first established, significant advances have occurred in radiation protection science, radioactive material knowledge, and transport accident assessment methodologies.
To ensure the transport framework continues to reflect current scientific understanding, the IAEA established an international working group to undertake a comprehensive review. The project took approximately ten years and involved experts from multiple countries and technical disciplines.
The review considered:
- New information about radiation effects and exposure.
- Improved methods for assessing transport accidents.
- Advances in scientific understanding of radioactive materials.
- Better knowledge of radioactive decay products.
- Additional radionuclides not previously included in the original calculations.
The outcome is a modernised set of A1 and A2 values designed to better reflect current scientific knowledge and transport safety principles.
How Significant Are the Changes?
The review resulted in proposed changes to a substantial proportion of the published values.
Approximately two thirds of A1 values and almost half of A2 values have been identified for revision.
Some radionuclides have experienced only modest adjustments, while others have seen significant increases or decreases. In some cases, the revised values differ by several multiples of the existing limits.
One example is Americium 241. Under the proposed revisions, the A1 value could increase from 10 TBq to 40 TBq, while the A2 value could increase from 0.001 TBq to 0.002 TBq.
This example highlights the scale of the review and demonstrates that the practical impact will vary considerably depending on the radionuclides involved.
What Could This Mean for Industry?
The revised A1 and A2 values have the potential to affect organisations that manufacture, use, test, package, or transport radioactive material.
Because these values determine when a source may be transported in Type A packaging and when Type B packaging is required, any reduction in a value could result in consignments moving into a more restrictive transport category.
Where this occurs, businesses may face:
- Increased packaging costs.
- Additional regulatory approvals.
- More restrictive carrier acceptance criteria.
- Reduced routing options.
Organisations that regularly transport radioactive gauges, medical isotopes, or industrial sources should review their transport arrangements once the revised values are adopted by national regulators.
Where a shipment exceeds a revised A2 limit, there are generally two available pathways.
Option One: Transition to Special Form Material
A replacement source may be obtained that has been designed and certified as special form radioactive material.
This allows the higher A1 limit to be applied and may enable continued use of Type A packaging.
Option Two: Use Type B Packaging
The existing normal form source may continue to be transported under Type B requirements.
While this approach remains compliant, it often involves higher costs, additional approvals, and operational limitations.
As some A2 values decrease, more organisations may find themselves relying on special form certificates to maintain operational efficiency.
Implications for Freight Forwarders
Freight forwarders play an important role in ensuring radioactive material consignments comply with applicable transport regulations before acceptance for carriage.
As revised values are adopted, forwarders can expect to see:
- Increased reliance on special form certificates.
- Additional documentation verification requirements.
- Greater scrutiny during acceptance processes.
- More customer enquiries regarding packaging changes and compliance obligations.
Procedures for consignment acceptance, approval certificate verification, compliance checks, staff training, and electronic systems may need to be reviewed and updated to reflect the revised limits.
Although day to day handling practices are unlikely to change significantly, ensuring that consignments continue to meet all applicable regulatory requirements before entering the transport chain will remain critical.
What Happens Next?
The revised A1 and A2 values are currently progressing through the IAEA regulatory development process and have not yet been fully implemented within national transport legislation.
Once the revised values are formally published by the IAEA, national regulators will need to determine how and when they will be adopted within their own regulatory frameworks. The changes will also flow into the various modal transport regulations that rely on the IAEA transport standards.
Historically, the air transport sector has often been among the first to adopt these changes, with the IATA Dangerous Goods Regulations typically incorporating updates relatively quickly following their acceptance within the international regulatory framework.
For dangerous goods professionals, trainers, consignors and freight forwarders, now is an appropriate time to become familiar with the proposed changes and begin assessing potential operational impacts.
The practical effect will vary depending on the radionuclides involved and the activities being transported. However, the revised A1 and A2 values are expected to influence radioactive material transport requirements for many years to come.
Final Reflection
Changes to radioactive material transport requirements often attract attention because of their technical complexity. However, the real significance of the revised A1 and A2 values lies in how they influence practical decisions around packaging, approvals, transport planning, and compliance management.
Understanding these developments early will allow organisations to assess their exposure, plan for future regulatory adoption, and maintain confidence in the safe transport of radioactive material as international standards continue to evolve.