IAEA-RGTh-1 , Thorium Ore

Inorganic , Ores

Both, IAEA-RGU-1 and IAEA-RGTh-1 reference materials were prepared on behalf of the International Atomic Energy Agency by the Canada Centre for Mineral and Energy Technology by dilution of a uranium ore BL-5 (7.09% U) and a thorium ore OKA-2 (2.89% Th, 219 μg U/g) with floated silica powder of similar grain size distribution, respectively. No evidence for between-bottles inhomogeneity was detected after mixing and bottling. BL-5 has been certified for uranium, 226Ra and 210Pb confirming that it is in radioactive equilibrium. The agreement between radiometric and chemical measurements of thorium and uranium in OKA-2 shows both series to be in radioactive equilibrium.

Analyte Value Unit 95% C.I. N R/I/C
232Th 3250? Bq/kg 3160 - 3340 155 R
235U 3.6? Bq/kg 3.3 - 3.9 145 R
238U 78? Bq/kg 72 - 84 145 R
40K 6.3? Bq/kg 3.1 - 9.5 45 I
K 200 mg/kg 100 - 300 45 I
Th 800 mg/kg 784 - 816 155 R
U 6.3 mg/kg 5.9 - 6.7 145 R
(Value) Concentration calculated as a mean of the accepted laboratory means
(N) Number of accepted laboratory means which are used to calculate the recommended or 
    information values and their respective confidence intervals
(R/I/C) Classification assigned to the property value for analyte (Recommended/Information/Certified)
(?) Natural radionuclide activity concentrations derived from the elemental concentrations on basis of isotopic abundance and half-life data

The values listed above were established on the basis of a gravimetric dilution of materials with known uranium, thorium and potassium composition. The details concerning the criteria for qualification as a recommended or information value can be found in the respective report (attached).

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