A total mass of 225 kg wet sediment was sampled by box corer (20 cm × 20 cm) on 26 August 2012, at 82 m depth in the Baltic Sea (59° 34.91’ N, 23° 37.61’ E). The sediment sample was first air-dried to 108 kg and subsequently freeze-dried yielding 60 kg of dry sediment. The sample was then ground into powder using a micronisation technique. The powder was then homogenised by mixing in a nitrogen atmosphere, then bottled and sealed in polyethylene flasks (50 ± 1) g units and coded as IAEA-465. A total of 960 bottles were produced. All bottles were sterilised at 28 kGy (60Co) in an irradiation facility.
| Radionuclide | Certified value⁽ᵃ⁾ [Bq kg⁻¹] | Expanded Uncertainty⁽ᵇ⁾ [Bq kg⁻¹] | Half-life[¹] |
40K | 1072 | 84 | 1.2504(30)x109 years |
137Cs | 89.7 | 4.1 | 30.05(8) years |
210Pb‡, | 163 | 17 | 22.23(12) years |
210Po† | 164 | 18 | 138.3763(17) days |
226Ra | 51.6 | 5.2 | 1600(7) years |
228Ra# | 64.4 | 5.5 | 5.75(4) years |
228Th+ | 64.4 | 5.9 | 1.9126(9) years |
232Th | 64.4 | 5.4 | 14.02(6)x109 years |
234U | 86.2 | 6.8 | 2.455(6)x105 years |
235U | 3.89 | 0.31 | 704(1)x106 years |
238U | 86.4 | 6.9 | 4.468(5)x109 years |
238Pu | 0.07 | 0.01 | 87.74(3) years |
239/240Pu | 2.17 | 0.16 | - |
241Am | 0.99 | 0.15 | 432.6(6) years |
(a) Certified values are calculated from the accepted data sets, obtained by a different laboratory using a method of choice following ISO Guide 35 [2].
(b) The uncertainty is expressed as an expanded uncertainty using a coverage factor k = 2 estimated in accordance with the JCGM 100:2008 [3] and ISO Guide 35 [2].
References:
[Ref. 1] BNM – CEA/LABORATOIRE NATIONAL HENRI BECQUEREL, Table de Radionucleides,
http://www.nucleide.org/DDEP_WG/DDEPdata.htm (date accessed 2021-09-16)
[Ref. 2] INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Reference materials — Guidance for characterization and assessment of homogeneity and stability, ISO Guide 35: 2017, ISO, Geneva (2017).
[Ref. 3] JOINT COMMITTEE FOR GUIDES IN METROLOGY (JCGM), Evaluation of Measurement data - Guide to the Expression of Uncertainty in Measurement, JCGM 100:2008 (GUM 1995 with minor corrections), (2008). https://www.bipm.org/documents/20126/2071204/JCGM_100_2008_E.pdf/cb0ef43f-baa5-11cf-3f85-4dcd86f77bd6 (date accessed 2021-09-17)
