The Environmental Radioactivity Comparison 2005 was the twelfth in a series of similar exercises to have been conducted by NPL. A total of 48 participants took part in this exercise, 28 being from the UK measurement community and 20 from overseas organisations.

The timetable for the exercise was as follows:

Samples ready for dispatch	September 2005
Deadline for submission of results	16 December 2005
Post-comparison workshop	February 2006
Report issued (click to download)	June 2006

For this exercise, five sample types were available:

Type ABH
Samples consist of 20 g (nominal) of 2 M HNO₃ with 10 ppm of Fe, Sr and Y, containing a mixture of alpha- and beta-emitting radionuclides. The radionuclidic composition, and approximate activity concentrations, were as follows:

⁵⁵Fe, ⁸⁹Sr, ⁹⁰Sr, ²³⁸U, ²³⁸Pu, and ²⁴¹Am (each in the range of 1-20 Bq/g)

Type ABL
Samples consist of 500 g (nominal) of 2 M HNO₃ with 10 ppm of Fe, Sr and Y, containing the same radionuclides as ABH Type, and each of the other radionuclides in the range 2-1-20 Bq/kg.

Type LB
Samples consist of 500 g (nominal) of 0.001 M NaOH with 50 ppm of C and S, containing a mixture of low energy beta-emitting radionuclides. The radionuclidic composition, and approximate activity concentrations, were as follows:

Tritium, ¹⁴C and ³⁵S (each in the range 100-500 Bq/kg)

Type GH
Samples consist of 100 g of 2 M HCl/0.1 M oxalic acid with 50 ppm of Ba, Co, Na, Nb, Sb, Y and Zr, containing a mixture of ten gamma-emitting radionuclides:

²²Na, ⁶⁰Co, ⁸⁸Y, ⁹⁵Zr, ⁹⁵Nb, ¹²⁵Sb, ¹³³Ba, ¹³⁴Cs, ¹³⁷Cs, ¹⁵²Eu (each in the range 1 - 20 Bq/g)

Type GL
Samples consist of 500 g of the same chemistry and the same radionuclides as GH type. The activity concentration of each nuclide was in the range 1-20 Bq/g.

The Environmental Workshop took place at NPL on 21st February 2006. The following presentations were given during the workshop (available to download in pdf format):

• Source preparation and validation  – Chris Gilligan, NPL
• Presentation of Alpha/Beta results – Arvic Harms, NPL
• Presentation of the Low energy Beta results – Chris Gilligan, NPL
• Presentation on primary standardisation – Lena Johansson, NPL
• Presentation of the Gamma results – Arvic Harms, NPL
• Presentation on measurement of ⁹⁵Nb/⁹⁵Zr, ⁸⁹Sr and ⁹⁰Sr – Arvic Harms, NPL

Back to NPL Environmental Radioactivity Comparison Exercises