The Radioactive Material (Road Transport) (Great Britain) Regulations 1996

Regulation 2(1)

SCHEDULE 1 Determination of A₁ and A₂ values

1.  Values of A₁ and A₂ for individual radionuclides are those given in Table I of Schedule 36.

2.  For individual radionuclides whose identities are known, but which are not listed in Table I of Schedule 36, the determination of the values of A₁ and A₂ shall require the approval of the Secretary of State or, for international transport, multilateral approval. Alternatively, the values of A₁ and A₂ in Table II of Schedule 36 may be used without obtaining competent authority approval.

3.  In the calculations of A₁ and A₂ for a radionuclide not in Table I of Schedule 36, a single radioactive decay chain in which the radionuclides are present in their naturally occurring proportions and in which no daughter nuclide has a half-life either longer than 10 days or longer than that of the parent nuclide shall be considered as a single radionuclide, and the activity to be taken into account and the A₁ or A₂ value to be applied shall be those corresponding to the parent nuclide of that chain. In the case of radioactive decay chains in which any daughter nuclide has a half-life either longer than 10 days or greater than that of the parent nuclide, the parent and such daughter nuclides shall be considered as mixtures of different nuclides.

4.  An A value for a mixture of radionuclides whose identities and respective activities are known may be determined as follows:

(a) for special form radioactive material:

(b) for other forms of radioactive material:

where

• f(i) is the fraction of activity of nuclide in the mixture and A₁(i) and A₂(i) are the respective A₁ and A₂ values for nuclide i.

5.  When the identity of each radionuclide is known but the individual activities of some of the radionuclides are not known, the radionuclides may be grouped and the lowest A₁ or A₂ value, as appropriate, for the radionuclides in each group may be used in applying the formulae in paragraph 4 above. Groups may be based on the total alpha activity and the total beta/gamma activity when these are known, using the lowest A₁ or A₂ values for the alpha emitters or beta/gamma emitters, respectively.

6.  For individual radionuclides or for mixtures of radionuclides for which relevant data are not available, the values shown in Table II of Schedule 36 shall be used.