Comparison of different approaches of soil sampling uncertainty determination.

The ISO/IEC 17025 standard requires that all significant contributions have to be propagated to the measurement uncertainty, including also sampling uncertainties. We evaluated soil sampling uncertainties for gamma-ray spectrometry by using in-house and split-sample methods. By in-house method, the sampling uncertainty was determined by comparing standard deviations of measurement results and average analytical uncertainty. With split-sample method, it was calculated using between-sample and between-analysis variances. If analytical uncertainty is reliably determined, the in-house method is recommended because fewer measurements are needed.

Measurement uncertainty arising from sampling of environmental samples.

In 2017, a new revision of the ISO/IEC 17025 standard was issued. One of the important changes is that the uncertainty arising from sampling has to be evaluated. Based on this new requirement, we evaluated the contribution of the sampling procedure to the total uncertainty budget of the high-resolution gamma-ray spectrometry of environmental soil, tap water and aerosol filter samples. We performed statistical analyses of measurements of sets of samples taken from the same target in the same general time period. The determination of sampling uncertainty was based on the evaluation of the standard deviation of the set of measurement results and the combined uncertainty budget of sample preparation and analysis. When the spatial and temporal heterogeneities are low, the sampling uncertainty is estimated to be around 5% (k = 1) for soil samples and 30-40% (k = 1) for air samples. For single tap water samples collected consecutively, sampling uncertainty does not have a significant contribution to the complete uncertainty budget.

Negative correlation between the number of sunspots and the occurrence of 7Be and 22Na in the surface air and their contribution to radiation doses.

This article presents yearly mean concentrations of cosmogenic radionuclides 7Be and 22Na occurring in dry and wet depositions (fallout) and aerosols. Time dependencies negatively correlated with the yearly mean number of sunspots. Activity concentrations of 7Be and 22Na in aerosols in the surface air had a correlation of near-unity. 7Be in aerosols exhibited a smoother time dependence than 22Na, implying that the production of 22Na is more sensitive to the solar activity than the production of 7Be. The effect of the measured doses on the general population through internal and external exposure to radiation from cosmogenic radionuclides was small.

Evaluation of the radon interference on the performance of the portable monitoring air pump for radioactive aerosols (MARE).

A compact portable aerosol sampling and measurement device was developed at Jozef Stefan Institute (JSI). A CeBr3 scintillation detector is positioned centrally within a concertinaed filter assembly. It provides continuous and via network communications on-line monitoring of low levels of airborne radioactive particulates. The evaluation of the response of the device to the natural background at controlled conditions with elevated radon concentrations, performed at the National Institute of Ionizing Radiation Metrology of ENEA, is presented.

Compact radioactive aerosol monitoring device for early warning networks.

In the frame of the European metrological research project MetroERM, a compact portable aerosol sampling and measurement device was developed at Jozef Stefan Institute. The system incorporates a CeBr3 scintillation detector positioned centrally within a concertinaed filter assembly and an improved high flow rate air pump. It provides continuous on-line low level airborne radioactive particulate monitoring for field station use via 3G network communications. The calibration of the device was performed at National Physical Laboratory (NPL) with filters, spiked with a certified mixed nuclide solution. Additionally first tests were performed in an environment with an elevated radon concentration.

Precise measurement of the half-life of 6¹Cu.

The decay characteristics of (61)Cu allow for a precise determination of its half-life. In order to search for a possible influence of the chemical environment on the decay rate, the half-life of (61)Cu in nickel and nickel-oxide was measured with high precision. The results show a small difference in the half-life that can be explained by the differences in electron density at the site of the nucleus. A discussion about the validity of the adopted value of the total angular momentum of the 656 keV state in (61)Ni is presented.