# The Ionising Radiations Regulations 2017, Part 4: Table of quantities of radioactive material defining high-activity sealed sources


For radionuclides not listed in the table below, the relevant quantity value is the same as the D-value defined in section 2 Table 1 of the IAEA publication: Dangerous quantities of radioactive material (D-values), (EPR-D-VALUES 2006)
1 The activity given is that of the alpha-emitting radionuclide.
Radionuclide
Quantity (Bq)
Co-60
3 × 1010
Se-75
2 × 1011
Sr-90 (Y-90)
1 × 1012
Cs-137
1 × 1011
Pm-147
4 × 1013
Gd-153
1 × 1012
Tm-170
2 × 1013
Yb-169
3 × 1011
Ir-192
8 × 1010
Ra-226
4 × 1010
Pu-238
6 × 1010
Pu-239/Be-91
6 × 1010
Am-241
6 × 1010
Am-241/Be-91
6 × 1010
Cm-244
5 × 1010
Cf-252
2 × 1010

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Source: https://www.legislation.gov.uk/uksi/2017/1075/schedule/7/part/4 (the official version)
Page: https://openlegislation.uk/ionising-radiations-regulations-2017/schedule-7/part-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.