Updated A1 and A2 values for the revised IAEA Regulations for Safe Transport of Radioactive Material 20xx Edition

Closed 20 Oct 2023

Opened 15 Sep 2023

Results updated 8 Nov 2023

Consultation period: 15 September 2023 – 20 October 2023

Consultation outcome: 
There were no submissions made during the consultation period for this IAEA draft document.


ARPANSA is engaging in public consultation on the updated A1 and A2 values for the revised IAEA Regulations of Transport of Radioactive Material 20xx Edition.


The A1 and A2 values tabulated in the IAEA transport regulations SSR-6 (Rev.1) have been determined to limit the contents of packages so thatthe radiological consequences following failure of the package after an accident are deemed to be acceptable, within the principles of radiological protection, following failure of the package after an accident” (para. 402.1 in SSG-26) where the package has lost its safety and radiation protection functions. These values were derived from the “Q system” (where “Q” stands for “Quantity”) radiological model, based on 5 different exposure scenarios and described in the advisory material SSG-26, using reference doses of 50 mSv (effective dose), 500 mSv (equivalent dose to the skin) and 150 mSv (equivalent dose to the lens of the eye). It is considered that exposures below these limits would not lead to significant health detriment, either deterministic or stochastic in the event of an accident.

A1 and A2 values are also often used to indicate the package standard performances required in the different transport conditions defined in SSR-6, as they represent equivalent radiological consequences for whatever radionuclide is involved.

The current Q system is originated from the radiotoxicity classification system used in the 1961, 1964 and 1967 editions of the Regulations, and the “A1/A2 system” derived in the 1973 edition. The Q system was first introduced in the 1985 edition No. SSR-6, using a similar method to the “A1/A2 system”, taking into account the latest changes in ICRP recommendations (ICRP 26) at that time. The A1 and A2 values were then updated with the 1996 edition of the Regulations No. ST-1 to use the then new ICRP 60 recommendations and the latest data from ICRP at that time. Since then, they have remained unchanged in the subsequent editions of the Transport Regulations.

ICRP has published updated and more complete data that supersede the previous data sets. New methods of calculation are also available. Further, there was a need in some countries to have A1/A2 values for additional radionuclides. But simple calculations of additional A1/A2 values or recalculation of existing values only using Appendix I of SSG-26 led to inconsistencies, and several organizations identified that information required to do such calculation/recalculation or to interpret the basic radionuclide values are not available.

Updated A1 and A2 values are presented in the document below.

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The objectives of the review of A1 and A2 values are to ensure that:

  • Updated ICRP dose coefficients and current international standards and data source along with new methods of calculation are used for calculation of A1 and A2 values.
  • Address the issues identified related to justification of the limits of Q values including treatment of progenies in a consistent manner.
  • Scientific basis is considered to analyse the impact of changes in ‘A’ values.

Is a Commonwealth regulatory impact statement required?

No. This is early engagement to obtain feedback from Australian stakeholders on the impact of the updated A1 and A2 values as they relate to the safe transport of radioactive material.

How to make a comment 

You can provide your feedback by either completing the online survey available by clicking on the Submit your feedback link under the Have your say section of this page. 

Comments are requested in relation to:  

  • Relevance and usefulness: Are the stated objectives appropriate and are they met by the draft text? 
  • Scope and completeness: Is the scope appropriate and is it adequately covered by the draft text?  
  • Quality and clarity: Does the guidance in the draft text represent the current consensus among specialists in the field and is this guidance expressed clearly and coherently?  
  • Safety and business impacy: Does the draft text appropriately address nuclear safety and any business impacts resulting from the proposed changes?

Comments of an editorial nature will be considered; however, it should be noted that the draft text will be comprehensively edited. Any comments should be made in English, should refer to the relevant paragraph number in the draft text being reviewed, and should propose alternative text where appropriate.  

Why your views matter

Your voice matters. 

Your feedback can provide valuable insight and shape decision-making that impacts nuclear and radiation regulations, standards and codes.

What happens next

Once the consulting period is complete, the results of the the consultation will be collated and published on this page.