Research and analysis

Calculating A1, A2 and exemption values: methodology review

This report (HPA-CRCE-027) describes a review of methodologies to calculate A1 and A2, and exemption values.



The international regulations on the safe transport of radioactive material make use of radionuclide specific values to define radioactive material for the purposes of those regulations. These exemption values of activity concentration and activity per consignment were derived using a number of scenarios of radiation exposure of workers and members of the public. These regulations also list radionuclide specific values of activity, the A1 and A2 values, which are the activity limits for Type A packages in the case of special form and not-special form material, respectively.

In this project, the calculations by which these radionuclide specific values were derived, were reproduced. The report describes the methodologies for those calculations.

The methodology for calculating exemption values was taken from the European Commission report RP-65. The A1 and A2 values were calculated using a methodology known as the Q System which is described in the advisory material that accompanies the IAEA regulation.

The report also includes a discussion and review of the methodologies used in the calculation of the A1, A2 and exemption values and gives suggestions for possible modifications.