Release of 3H and 14C during sampling and speciation in activated concrete

Characterisation of contaminated and activated decommissioning waste require sampling of the studied material for the analysis of different radionuclides. The volatility of 3H and 14C can lead to the loss of the analytes in sampling of solid materials since most often at least some heat is involved in the sampling technique. Especially 3H can be lost in cases when it is present as tritiated water (HTO) due to the evaporation of water even at low temperatures. Therefore, in this study, the 3H and 14C speciations are discussed. Consequently, a drilling sampling technique was developed in order to capture the released 3H and 14C in absorption solutions and measured using liquid scintillation counting. The sampling technique was tested on an activated concrete core. The collected samples were analysed for 3H and 14C (activity concentration and speciation) using a thermal oxidation technique. The results showed that a significant amount of 3H was released during sampling even though the majority of 3H was strongly bound in the activated concrete. The studied activated concrete did not contain measurable amount of 14C and therefore speciation studies were not possible.

Simultaneous determination of gross alpha/beta activities in water by liquid scintillation counting and its applications in the environmental monitoring

Based on the standards of ISO11704-2018 and ASTM D7283-17, a method for simultaneous determination of gross alpha and gross beta activity concentrations in water by liquid scintillation counting (LSC) was established, which can be applied to various types of water samples in routine monitoring, such as drinking water, groundwater, geothermal water, seawater, and radioactive wastewater. The sample’s pH value and concentrated volume must be controlled to avoid quenching as much as possible. The validation tests show that the deviations of gross alpha and gross beta activities can satisfy quality control requirements in a wide range of activity ratios. For the actual samples, the measurement results of the LSC method are in good agreement with those of the thick source method. Moreover, the LSC method performs better in detection limit and a simpler pretreatment process than the thick source method.

Gross alpha and gross beta activities measurements in groundwaters using liquid scintillation counting (LSC)

In this work Authors describe the methodology of gross alpha and gross beta activities determination in water samples. The chosen method is dedicated to LSC and is based on ISO 11704:2018 and it is suitable for ground waters with low and medium salinity, especially drinking or tap waters as well as medicinal waters (with healing properties, using in health resorts). Authors describe the proper sampling, laboratory preparation including radon removal and measurements conditions. The local and European law regulations showing the limits of radioactivity of drinking waters and medicinal waters are presented. This work presents also selected data of gross alpha and gross beta activities from selected research: the highest levels is measured in Jordanian (gross alpha) and in Brazil (gross beta) and it is respectively 3.58 Bq/L and 5.22 Bq/L.

LIQUID SCINTILLATION COUNTING (LSC)—PAST, PRESENT, AND FUTURE

ABSTRACT Radiocarbon (14C) dating by liquid scintillation (LS) spectroscopy (also known as LS counting or LSC) provides an alternate method of 14C analysis where accelerator mass spectrometry (AMS) analysis is less desirable. The past, present, and future applications of the method are discussed.

Purification of Labeled Oligonucleotides by Size-Exclusion Chromatography

When labeled oligonucleotides are to be used in enzymatic reactions such as primer extension, virtually all of the unincorporated label must be removed from the oligonucleotide. For this purpose, chromatographic methods or gel electrophoresis are superior to differential precipitation of the oligonucleotide with ethanol or cetylpyridinium bromide (CPB). This protocol describes a method to separate labeled oligonucleotides from unincorporated label that takes advantage of differences in mobility between oligonucleotides and mononucleotides during size-exclusion chromatography. Although size-exclusion chromatography can, in principle, be used to purify either radiolabeled or nonradiolabeled oligonucleotides, this protocol is geared toward purifying radiolabeled oligonucleotides, whose elution from the column is monitored using a minimonitor and whose separation from unincorporated nucleotides is monitored by liquid scintillation counting.

Radium interference during radon measurements in water: comparison of one- and two-phase liquid scintillation counting

Assessment of radiation exposure to drinking, surface, and groundwater and of the associated health risks calls for accurate and precise 226Ra and 222Rn measurements. One method that fits the bill is liquid scintillation counting (LSC), which allows measurements in one-phase (homogenous) or two-phase samples. The aim of our study was to compare the measurement efficiency with both variations in Niška Banja spa water, known for its elevated 222Rn content to get a better insight into the stability and behaviour of the samples and 226Ra interference in samples spiked with 226Ra with 222Rn measurement. 226Ra interference was more evident in homogenous, one-phase and much lower in two-phase samples. However, one-phase samples offer more accurate indirect 226Ra measurements. Water-immiscible cocktails (in two-phase samples) have shown a limited capacity for receiving 222Rn generated by Ra decay from the aqueous to organic phase when 222Rn/226Ra equilibrium is reached. We have also learned that samples with naturally high 222Rn content should not be spiked with 226Ra activities higher than the ones found in native samples and that calibration of two-phase samples can be rather challenging if measurements span over longer time. Further research would require much lower 226Ra activities for spiking to provide more practical answers to questions arising from the demonstrated phenomena.