In June 2007, 300 kg of moss-soil material was collected from an abandoned red marble mine in Gerecse Mountain in the north-west part of Hungary, by staff of the Radioanalytical Laboratory of the Food and Feed Safety Division (Hungary) in cooperation with the IAEA Terrestrial Environment Laboratory. The collected moss-soil material consists of decomposition products of moss, rock minerals from erosion/weathering processes and any washed-in soil from the neighbouring highland areas (including forest humus particles). The sampling area was undisturbed for over 40 years and therefore represents the nuclear history (before 2007), and the geochemical environment of the region.
The issue date of this Certified Reference Material is May 2011. Based on the stability testing of this material, the revised expiry date is May 2031. The IAEA is monitoring the long-term stability of the material and customers will be informed in case of any observed change.
Certified values for activity concentration
(based on dry mass)
| Radionuclide | Certified value(a) [Bq kg-1] | Uncertainty(b) [Bq kg-1] | Half-life |
| 137Cs | 328 | 8 | 30.05(8) y |
| 210Pb | 306 | 15 | 22.23(12) y |
| 210Po(c) | 311 | 16 | 138.3763(17) d |
| 212Pb(d) | 37.3 | 1.5 | - |
| 226Ra | 25.1 | 2.0 | 1600(7) y |
| 228Ac(d) | 37.3 | 2.0 | - |
| 234U | 21.8 | 0.8 | 2.455(6) × 105 y |
| 238U | 22.2 | 0.8 | 4.468(5) × 109 y |
(a) Certified values are calculated from the accepted data sets, each being obtained by a different laboratory following ISO Guide 35, and have been recalculated to the new reference date.
(b) The uncertainty is expressed as a combined standard uncertainty using a coverage factor k = 1 estimated in accordance with the JCGM 100:2008 and ISO Guide 35.
(c) The 210Po activity concentration is recalculated according to the transient equilibrium with 210Pb, using the 1.017 ratio derived from their half-lives using Bateman equations.
(d) Decay calculated with the half-life of 232Th.
Information values for activity concentration
(based on dry mass)
| Radionuclide | Information value(a) [Bq kg-1] | Uncertainty(b) [Bq kg-1] | Half-life |
| 40K | 550 | 18 | 1.2504(30)×109 y |
| 90Sr | 3.8 | 0.2 | 28.8(7) y |
| 232Th | 37.3 | 2.0 | 14.02(6)×109 y |
| 241Am | 2.3 | 0.2 | 432.6(6) y |
| 238Pu | 0.15 | 0.02 | 87.74(3) y |
| 239+240Pu(c) | 5.3 | 0.2 | - |
| 241Pu | 4.6 | 0.6 | 14.33(4) y |
(a) Information values are calculated from the accepted data sets, each being obtained by a different method of determination following ISO Guide 35, and have been recalculated to the new reference date.
(b) The uncertainty is expressed as a combined standard uncertainty using a coverage factor k = 1 estimated in accordance with the JCGM 100:2008 and ISO Guide 35.
(c) The ratio of 239Pu/240Pu is not determined, therefore the exact decay correction cannot be calculated. Due to their long half-lives (24100 and 6561 years respectively), no visible changes are expected during the next ten years, confirmed by conservative calculation using the shorter half-life.
Reference date for all specified radionuclide decay corrections: 01 March 2021
