The Environmental Radioactivity Comparison 2002/2003 was the tenth in a series of similar exercises to have been conducted by NPL. A total of 34 participants took part in this exercise, 28 being from the UK measurement community and 6 from overseas organisations.

The timetable for the exercise was as follows:

Samples ready for dispatch	December 2002
Deadline for submission of results	28 February 2003
Report issued	Mid-April 2003
Post-comparison workshop	8 May 2003

For this exercise, six sample types were available:

Type (1)
Samples consist of 100 g (nominal) of dilute nitric acid containing a mixture of alpha- and beta-emitting radionuclides. The radionuclidic composition, and approximate activity concentrations, were as follows:

⁹⁰Sr (20 Bq/g), ²¹⁰Pb, ²²⁶Ra, ²³⁸Pu, ²³⁹Pu and ²⁴¹Am (each approximately 2 Bq/g)

Type (2)
Samples consist of 500 g (nominal) of dilute nitric acid containing the same radionuclides as Type (1), but with ⁹⁰Sr at approximately 25 Bq/kg and each of the other radionuclides at approximately 2.5 Bq/kg.

Type (3)
Samples consist of 100 g (nominal) of carbonates/sulphates in aqueous solution containing a mixture of low energy beta-emitting radionuclides. The radionuclidic composition, and approximate activity concentrations, were as follows:

Tritium, ¹⁴C and ³⁵S (each approximately 20 Bq/g)

Type (4)
Samples consist of 500 g (nominal) of aqueous solution containing the same radionuclides as Type (3), but with each of the radionuclides at approximately 25 Bq/kg.

Type (5)
Samples consist of 100 g (nominal) of dilute hydrochloric acid (plus very weak oxalic acid) containing a mixture of nine beta/gamma-emitting radionuclides:

²²Na, ⁵⁷Co, ⁶⁰Co, ⁹⁵Zr/⁹⁵Nb, ¹⁰⁶Ru/¹⁰⁶Rh, ¹³⁴Cs, ¹³⁷Cs, ¹⁵⁴Eu, ¹⁵⁵Eu (each approximately 2 Bq/g)

Type (6)
Samples consist of 500 g (nominal) of dilute hydrochloric acid (plus very weak oxalic acid) containing the same radionuclides as Type (5). The activity concentration of each nuclide was approximately 2.5 Bq/kg.

The Environmental Workshop took place at NPL on 8th May 2003. The following presentations were given during the workshop (available to download in pdf format):

• Selection of radionuclides / Source preparation and validation – Julian Dean, NPL
• Limits of detection – Simon Jerome, NPL
• International Comparisons- Equivalence and Traceability – Mike Woods, IRMC
• Uncertainties – Mike Woods, IRMC
• Accreditation and the value of intercomparisons – Julie Eccles, UKAS
• How to influence the next research programme at NPL (2004-2007) – Steven Judge, NPL

Back to NPL Environmental Radioactivity Comparison Exercises