Validation of in situ and laboratory gamma spectrometry measurements for determination of 226Ra, 40K and 137Cs in soil

In situ and laboratory gamma spectrometry methods for determination of 226Ra, 40K and 137Cs in soil have been validated and compared. Minimum detectable activity, repeatability, and reproducibility were the main validation parameters. Results have shown that soil humidity lower the in situ measurement results in comparison to laboratory measurements. Measurement uncertainties were also estimated and compared for both techniques. Uncertainty due to soil humidity (55%) using the in situ measurement was the main contributor to the total uncertainty, while the uncertainty due to net counting (71%) using the laboratory measurements was the largest contributor to the total uncertainty value.

► In situ and in vivo γ-spectrometry for determination of 226Ra, 40K and 137Cs in soil have been compared.
► A good agreement between the results of the two techniques was obtained.
► Net count rate is a major contributor to the total uncertainty using laboratory γ-spectrometry.
► Soil humidity is a major contributor in the total uncertainty using in situ γ-spectrometry.