The Environmental Radioactivity Comparison 2003/2004 was the eleventh in a series of similar exercises to have been conducted by NPL. A total of 48 participants took part in this exercise, 30 being from the UK measurement community and 18 from overseas organisations.

The timetable for the exercise was as follows:

Samples ready for dispatch	Feb-March 2004
Deadline for submission of results	21 May 2004
Report issued (click to download)	August 2004
Post-comparison workshop	September 2004

For this exercise, five sample types were available:

Type ABH
Samples consist of 100 g (nominal) of 2 M HNO₃ with 50 ppm of Sr and Y, containing a mixture of alpha- and beta-emitting radionuclides. The radionuclidic composition, and approximate activity concentrations, were as follows:

⁹⁰Sr (10 Bq/g), ⁹⁹Tc, ²³⁸Pu, ²³⁹Pu and ²⁴¹Am (each in the range of 2-4 Bq/g)

Type ABL
Samples consist of 500 g (nominal) of 2 M HNO₃ with 50 ppm of Sr and Y, containing the same radionuclides as ABH Type, but with ⁹⁰Sr at approximately 12 Bq/kg and each of the other radionuclides in the range 2-5 Bq/kg.

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

Tritium and ¹²⁹I (each approximately 500 Bq/kg)

Type BGH
Samples consist of 100 g (nominal) of 2 M HCl/0.1 M oxalic acid (and 0.0002 M HNO3) with 50 ppm of Cs, Co, Ce, Ru and Zr and 10 ppm of Rh and Nb, containing a mixture of eight beta/gamma-emitting radionuclides:

⁶⁰Co, ⁹⁵Zr/⁹⁵Nb, ¹⁰⁶Ru/¹⁰⁶Rh, ¹³⁴Cs, ¹³⁷Cs, ¹⁴⁴Ce, ¹⁵⁴Eu, ¹⁵⁵Eu (each in the range 1 - 9 Bq/g)

Type BGL
Samples consist of 500 g (nominal) of the same chemistry and the same radionuclides as BGH type. The activity concentration of each nuclide was in the range 2-11 Bq/g.

The Environmental Workshop took place at NPL on 27th September 2004. The following presentations were given during the workshop (available to download in pdf format):

• Source preparation – Sean Collins, NPL
• Selection and standardisation of the radionuclides – Arzu Arinc, NPL
• Presentation of the alpha/beta results – Arvic Harms, NPL
• Presentation of the beta/gamma results – Andy Pearce, NPL
• Presentation of the low energy beta results – Denise Woods, NPL
• The new NMS Ionising Radiation Metrology Programme – Steven Judge, NPL

Back to NPL Environmental Radioactivity Comparison Exercises