Radioactive substances legislation - scope: guidance

Guidance on radioactive substances activities in Scotland that are out of scope of the Environmental Authorisations (Scotland) Regulations 2018 (EASR).

Technical considerations

Discounting of ‘normal’ background

The ‘out of scope’ levels and the exemption levels are based on the calculated values after removing background. It is the responsibility of the authorised person[7] to either:

  • Use the total assessed value of any substance, or
  • Be able to demonstrate how the background has been calculated and why that is appropriate.

Separate processes, giving rise to separate solid waste streams, can be treated on their own for the purposes of the above paragraphs. A ‘separate process’ can be defined as one in which optimisation can be achieved without compromising any optimisation steps for another process.

A substance or article is not regarded as radioactive material or radioactive waste unless the concentration of any artificial radionuclide is above the levels ‘found normally in such a substance’[8].

The purpose of this provision is to remove materials and wastes containing radionuclides which are not amenable to controls because of their ubiquitous presence in the earth, its waters or atmosphere from the need for regulation. The concept applies to artificial radionuclides found in naturally occurring materials. For instance, due to historical atmospheric weapons tests and the Chernobyl accident, certain fission products are in global circulation. Obviously, such radioactivity is not amenable to control. Neither is the radioactivity in rainwater arising from the presence of these artificial radionuclides in the atmosphere.

Practical considerations of assessment also need to be taken into account. Authorised persons are expected to use good practice to determine the radiochemical assay of the waste, but where the difference between the level ‘found normally in such a substance’ and the increment due to additional contamination genuinely cannot be separated or reasonably measured, then the entire material can be considered as ‘out of scope’.

‘Head of chain’ calculations

For the purposes of calculating the total activity in wastes, the head of the chain may be taken to already include all radionuclides in a decay chain (in the case of radionuclides followed by the term ‘sec’), or all the listed radionuclides (in the case of the term ‘+’).

‘sec’ where it appears after a radionuclide means that, for the purpose of calculations, all radionuclides in the decay chain in secular equilibrium have been taken into account for the purposes of radiological impact assessment.

‘+’ where it appears after a radionuclide means that, for the purpose of calculations, the radionuclide includes such of its daughter radionuclides in the decay chain that are relevant for the purposes of radiological impact assessment; these radionuclides are listed in Table 4 for out of scope material.

Technical considerations

Calculations using ‘head of chain’ values can be applied to:

  • Calculations of ‘out of scope’ levels for industrial activities in Table 2.
  • Calculations of ‘out of scope’ levels for practices in Table 3.
Table 4: Radionuclides in secular equilibrium
Parent radionuclide Daughter radionuclides
Fe-52+ Mn-52m
Zn-69m+ Zn-69
Sr-90+ Y-90
Sr-91+ Y-91m
Zr-95+ Nb-95m
Zr-97+ Nb-97m, Nb-97
Nb-97+ Nb-97m
Mo-99+ Tc-99m
Mo-101+ Tc-101
Ru-103+ Rh-103m
Ru-105+ Rh-105m
Ru-106+ Rh-106
Pd-103+ Rh-103m
Pd-109+ Ag-109m
Ag-108m+ Ag-108
Ag-110m+ Ag-110
Cd-109+ Ag-109m
Cd-115+ In-115m
Cd-115m+ In-115m
In-114m+ In-114
Sn-113+ In-113m
Sb-125+ Te-125m
Te-127m+ Te-127
Te-129m+ Te-129
Te-131m+ Te-131
Te-132+ I-132
Te-133+ I-133, Xe-133m, Xe-133
Te-133m+ Te-133, I-133, Xe-133m, Xe-133
I-131+ Xe-131m
Cs-137+ Ba-137m
Ce-144+ Pr-144, Pr-144m
Pb-210+ Bi-210, Po-210
Pb-212+ Bi-212, Tl-208
Bi-212+ Tl-208
Ra-223+ Rn-219,
Po-215, Pb-211, Bi-211, Tl-207  
Ra-224+ Rn-220,
Po-216, Pb-212, Bi-212, Tl-208  
Ra-226+ Rn-222, Po-218, Pb-214, Bi-214, Po-214
Ra-228+ Ac-228
Ac-227+ Th-227, Fr-223, Ra-223, Rn-219, Po-215, Pb-211, Bi-211, Tl207, Po-211
Th-226+ Ra-222, Rn-218, Po-214
Th-228+ Ra-224,
Rn-220, Po-216, Pb-212, Bi-212, Tl-208  
Th-229+ Ra-225,
Ac-225, Fr-221, At-217, Bi-213, Tl-209,Pb-209  
Th-232+ Ra-228, Ac-228, Th-228, Ra-224, Rn-220, Po-216, Pb-212, Bi212, Tl-208
Th-232sec Ra-228, Ac-228, Th-228, Ra-224, Rn-220, Po-216, Pb-212, Bi212, Po-212, Tl-208
Th-234+ Pa-234m, Pa-234
U-230+ Th-226, Ra-222, Rn-218, Po-214
U-232+ Th-228, Ra-224, Rn-220, Po-216, Pb-212, Bi-212, Tl-208
U-235+ Th-231
U-235sec Th-231, Pa-231, Ac-227, Th-227, Fr-223, Ra-223, Rn-219, Po215, Pb-211, Bi-211, Tl-207, Po-211
U-238+ Th-234, Pa-234m, Pa-234
U-238sec Th-234, Pa-234m, Pa-234, U-234, Th-230, Ra-226, Rn-222, Po218, Pb-214, Bi-214, Po-214, Pb-210, Bi-210, Po-210
U-240+ Np-240m, Np-240
Np-237+ Pa-233
Pu-244+ U-240, Np-240m, Np-240
Am-242m+ Np-238
Am-243+ Np-239
Cm-247+ Pu-243
Cf-253+ Cm-249
Es-254+ Bk-250
Es-254m+ Fm-254



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