Worldwide Open Proficiency Test: Determination of ... - Nucleus - IAEA

To confirm the assigned target values and to test the homogeneity of the test items, two
bottles from each water sample were analyzed at the IAEA Terrestrial Environment
Laboratory. The measurement results obtained by the laboratory were in good agreement with
the assigned target values and demonstrated that the homogeneity of the water samples was fit
for the purpose of this proficiency test.
2.3.3. Preparation and characterization of sample 01 (IAEA-447 Moss-soil)
The IAEA-447 moss-soil reference material was collected in 2007 from an abandoned red
marble mine in “Gerecse Mountain” located on north-west part of Hungary by the Reference
Radiological Laboratory of the Ministry of Agriculture and Rural Development in Hungary in
cooperation with the Reference Materials Group of the IAEA Terrestrial Environment
Laboratory.
The mosses were naturally grown on large flat red marble stones surfaces which were
extensively covered with mosses, Figure 3. Both natural and artificial radionuclides from the
fall-out have been accumulated during the last 40 years. Hence, the collected mosses with the
eroded soil adhered to it, were representing an accumulated history or a memory record of the
radionuclides fall out of the last 4 decades.
Three hundred kg of the collected bulk material was first air dried in an oven, then milled and
homogenised in one lot in a clean atmosphere. The used homogenizer was a rolling-drum type
of 300 litres capacity.
Bottling of IAEA-447 was done under normal laboratory conditions; 1100 secure bottles were
filled in one day taking all precautions to avoid segregation. The bottles were labelled
arranged into big plastic boxes and sterilized using gamma ray irradiation with a total dose of
25 kGy using a Co-60 source.
The secure bottle size was 450 ml with wide secure-sealed cover to preserve the integrity of
the reference material in the bottle. The amount of the material in each bottle was 150 g.
Figure 3: The sampling field where the moss-soil was collected
Final Darft, page 7