We maintain the UK primary standards of radioactivity
We disseminate these standards to users of ionising radiation in fields such as nuclear medicine, environmental radioactivity monitoring and nuclear decommissioning. NPL also provides products and services to enable organisations to comply with legislation and good practice related to ionising radiation.
Primary and secondary standards
This service covers the provision of both primary and secondary standards of a range of alpha-, beta- and/or gamma-emitting radionuclides. Also provided under this service are standardised low-level radionuclide mixtures which are used for the annual environmental proficiency test exercises.
Please download the Environmental Solutions Product List.
Please download information on the NPL Mixed Nuclide Solution.
Gamma-ray emitting radionuclides
These are determined directly by primary counting methods or by means of the NPL ionisation chamber or other secondary standard instruments, previously calibrated using primary standards. Many nuclides are available and further details can be provided on request.
Pure beta-particle emitting radionuclides
The following are examples of radionuclides that can be standardised: 3H, 14C, 32P, 35S, 89Sr, 90Sr + 90Y, 99Tc, 147Pm and 204Tl. A standard of organically bound tritium is also available on request.
Alpha-particle emitting radionuclides
Examples are 208Po, 209Po, 229Th, 232U, 237Np, 238U, 239Pu, 241Am, 242Pu, 243Am, 244Cm, of which some are standardised by primary counting techniques.
Environmental radioactivity proficiency test exercises
NPL runs an annual environmental radioactivity proficiency test exercise of standardised environmental-level radionuclide mixtures in support of user measurements and Quality Assurance. Each exercise includes a follow-up workshop at NPL, the cost of which is included in the participation fee.