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This study compares different approaches for the quantification of the massic activity of 36 Cl in graphite samples. All approaches consisted of a combustion step in combination with a trapping solution to collect the volatile elements. Two different resins were used to separate 36 Cl from the matrix (CL resin and PS resin). Liquid scintillation counting (LSC), scintillation counting (SC) and tandem inductively coupled plasma mass spectrometry (ICP-MS/MS) were used to quantify 36 Cl activity. The chemical yield in all approaches was determined by means of ion chromatography (IC). In addition, the methods were applied to a real activated graphite sample., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Measurement uncertainty is an important variable, to be accounted for when decisions have to be made based on measurement results. Measurement uncertainty is composed of two main components; one is related to the primary sampling, the other to the sample preparation and the subsequent analysis of the sample. The component related to the sample preparation and the analysis is commonly well evaluated in proficiency testing while there is generally no straightforward similar approach to evaluate sampling uncertainty. ISO 17025:2017 explicitly requires that testing laboratories performing sampling and analyses determine the uncertainty related to the primary sampling. In order to determine uncertainty arising in the primary sampling of 222 Rn in water destined for human consumption, three laboratories IRE (BE), DiSa (LU) and SCK CEN (BE) initiated a joined sampling and measurement campaign. The dual split sample method in combination with ANOVA was used to evaluate the primary sampling uncertainty (precision) of the different methods. The tests showed that sampling bias is very probably, but that with good laboratory practice the sampling uncertainty precision and respectively bias can be kept below 5%., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Uncertainty associated with nuclear counting analyses are attributed to two main components of uncertainty; one is related to sampling, the other to sample preparation and the subsequent nuclear counting. The ISO/IEC 17025 standard of 2017 require accredited laboratories carrying out their own sampling to estimate the uncertainty associated with sampling in the field. This study presents the results of a sampling campaign and analysis by gamma spectrometry to determine the sampling uncertainty related to the measurement of radionuclides in soil., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Damien Braekers reports financial support was provided by Federal Ministry of Economie SMEs Self-Employed and Energy., (Copyright © 2023. Published by Elsevier Ltd.)

Recycling and conventional reuse of lead materials and structures originating from controlled areas in nuclear facilities rely on historical knowledge and well selected characterization procedures. At the SCK•CEN, one of these procedures involves performing high-resolution gamma-ray spectrometry measurements on several cylindrical shaped test samples (50 mm diameter and approximately 5 mm thickness), obtained during the lead melting campaigns. The high density (11.3 g/cm³) of these samples is a challenge for radionuclide analysis by gamma-ray spectrometry since no such calibration sources nor reference materials are available. We used the efficiency transfer procedure, relying on regular standard sources available in our laboratory, to set up calibrations for this specific counting geometry. The method proves to be fit for purpose., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This work reports a new approach for the determination of 36 Cl in radioactive waste samples from nuclear decommissioning, wherein novel plastic scintillator (PS) materials were used for the concentration of 36 Cl prior to the detection with scintillation counting. Different plastic scintillator (PS) materials were tested for their selective absorption and detection of 36 Cl activity in solid samples. PS microspheres (PSm), cross-linked PSm (CPSm) and PS resin have been investigated. PS resin was identified as the most suitable material for 36 Cl analysis. Pyrolysis and subsequent trapping of the volatile elements in a bubbler was used. The trapping solution was finally loaded onto a cartridge of the PS resin. Scintillation counting and ion chromatography were used to determine the activity concentration and the chemical recovery, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In this study, calculation of decision threshold and detection limit expressed in counts for low-level radioactivity measurements were evaluated and compared to a Monte Carlo method for the case of paired Poisson-distributed observations, i.e. for discrete variables. The calculated characteristic limits obtained from Monte Carlo calculations were compared with analytical expressions given in literature. The results in this study show that the equations given by Currie are in good agreement with the results from the Monte Carlo calculations simulating nuclear counting applications with a low number of observed counts. An exception is observed for a background corresponding to zero counts. This study also shows that at a low number of counts, the specific boundary conditions of the interval that represents counts corresponding to the presence of the analyte (>or ≥), have an impact on the false positives and negatives rates as defined by the parameters α and β., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Calculation of the decision threshold and detection limit of a measurement, or measurement method, are crucial in order to decide if an analyte is present or not and with what confidence it can be quantified. That decision is important in view of possible actions if something would be detected. In this work, a method for calculating these limits using a Monte Carlo method is presented. In the Monte Carlo method any a priori distribution (e.g. normal distribution, rectangular distribution, triangular distribution) of an input quantity can be selected. Differences between the Monte Carlo calculated characteristic limits and the ones calculated according to ISO 11929:2010 is presented. Moreover, suggestions how to calculate the detection limit when it can not be calculated according to the ISO 11929:2010 are given., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A collimated source of 241 Am was scanned over the endcap of a 21 year old coaxial HPGe-detector that had spent about 75% of its life at room temperature (and the remaining time at 77 K). The detector response was recorded and used as a measure of the relative thickness of the top deadlayer. This thickness was not homogeneous and was thicker near to the outer surface of the crystal compared to the centre, which could be a result of increased diffusion of Li atoms during times the detector was kept at room temperature. The results were compared with two newer HPGe-detectors that proved to have homogeneous top deadlayers., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Some authors have raised doubt about the invariability of decay constants, which would invalidate the exponential-decay law and the foundation on which the common measurement system for radioactivity is based. Claims were made about a new interaction - the fifth force - by which neutrinos could affect decay constants, thus predicting changes in decay rates in correlation with the variations of the solar neutrino flux. Their argument is based on the observation of permille-sized annual modulations in particular decay rate measurements, as well as transient oscillations at frequencies near 11 year -1 and 12.7 year -1 which they speculatively associate with dynamics of the solar interior. In this work, 12 data sets of precise long-term decay rate measurements have been investigated for the presence of systematic modulations at frequencies between 0.08 and 20 year -1 . Besides small annual effects, no common oscillations could be observed among α, β - , β + or EC decaying nuclides. The amplitudes of fitted oscillations to residuals from exponential decay do not exceed 3 times their standard uncertainty, which varies from 0.00023 % to 0.023 %. This contradicts the assertion that 'neutrino-induced' beta decay provides information about the deep solar interior., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The implementation of the one-pass-through separation technique using two stacked chromatography columns of TEVA - TRU resins for the separation of 237 Np, 241 Am, thorium, plutonium and uranium from environmental and urine samples was investigated. The sequential separation technique proved to be successful and gave similar results to those obtained when using individual separations. The analysis time was considerably improved. The amount of chemical waste was also reduced by 50% and the use of HClO 4 was avoided. The technique of ICP-MS was also investigated as a complementary technique to alpha-spectrometry., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A method is presented for calculating the expected number of counts in peaks that have a large relative peak-area uncertainty and appear in measured gamma-ray spectra. The method was applied to calculations of the correction factors for peaks occurring in the spectra of radon daughters. It was shown that the factors used for correcting the calculated peak areas to their expected values decrease with an increasing relative peak-area uncertainty. The accuracy of taking the systematic influence inducing the correction factors into account is given by the dispersion of the correction factors corresponding to specific peaks. It was shown that the highest accuracy is obtained in the peak analyses with the GammaVision and Gamma-W software., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Deep geothermal energy is a local energy resource that is based on the heat generated by the Earth. As the heat is continuously regenerated, geothermal exploitation can be considered as a renewable and, depending on the techniques used, a sustainable energy production system. In September 2015, the Flemish Institute for Technological Research (VITO) started drilling an exploration well targeting a hot water reservoir at a depth of about 3km on the Balmatt site near Mol. Geothermal hot water contains naturally occurring gases, chemicals and radionuclides at variable concentrations. The actual concentrations and potentially related hazards strongly depend on local geological and hydrogeological conditions. This paper summarizes the radiological characterization of several rock samples obtained from different depths during the drilling, the formation water, the salt and the sediment fraction. The results of our analyses show low values for the activity concentration for uranium and thorium in the formation water and in the precipitate/sediment fraction. Also, the activity concentrations of 210 Pb and 210 Po are low in these samples and the activity concentration of 226 Ra is dominant. From the analysis of the rock samples, it was found that the layer above the reservoir has a higher uranium and thorium concentration than the layer of the reservoir, which on the other hand contains more radium than the layer above it., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The European Union published in 2013 a new Drinking Water Directive with stricter requirements for measuring natural radioactivity. In order to adhere to this, a method for sequential separation of 210Pb, 210Po, 238U and 234U in drinking water was applied using UTEVA® and Sr resins. Polonium-210, 238U and 234U were quantified using alpha-particle spectrometry and 210Pb using liquid scintillation counting. Radium-226 and 228Ra were determined using 3M Empore Radium RAD Disks, and their quantification was done using a Quantulus™ 1220 liquid scintillation counter.

We present a numerical fitting method for transmission data that outputs an equivalent sample composition. This output is used as input to a generalised efficiency transfer model based on the EFFTRAN software integrated in a LIMS. The procedural concept allows choosing between efficiency transfer with a predefined sample composition or with an experimentally determined composition based on a transmission measurement. The method can be used for simultaneous quantification of low-energy gamma emitters like (210)Pb, (241)Am, (234)Th in typical environmental samples., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

We developed a Microsoft(®) Access-based LIMS (Laboratory Information and Management Systems), γ-LIMS, for the management of our gamma-spectrometry laboratory, in which thousands of routine, but high-quality analyses are performed each year. This paper explains the main features of the γ-LIMS and puts special attention on the interfacing methods and solutions for using the Genie™2000 spectrometry software in conjunction with the EFFTRAN package, which serves for efficiency transfer calculations, coincidence summing corrections and a procedure for uncertainty estimation., (© 2013 Published by Elsevier Ltd.)

Any approach to efficiency calibration of HPGe detectors sensitive to low-energy gamma-rays and X-rays has to deal with true coincidence summing. We developed a method based on the integration of the EFFTRAN code into the commercial Genie2K™ gamma-ray spectrometry software. EFFTRAN's role is to compute true coincidence summing corrections and to obtain satisfactory results for detectors sensitive to X-rays. EFFTRAN had to be upgraded to include a full simulation of the emission of X-rays. In this manner, efficiency calibrations were successfully set up for BeGe and XtRa detectors., (© 2013 Published by Elsevier Ltd.)

The determination of isotope specific activities, and above all, the identification of radioisotopes is an important issue in the waste management of nuclear wastes whatever their origin. Systems based on the detection of the gamma rays emitted by the radionuclides allow the non-destructive assay (NDA) of relatively large volumes of waste. Different NDA systems are commercially available for this purpose. NDA of waste items is subject to the influence of many different physico-chemical characteristics of the sample, most of which are generally not known. In many cases, however, NDA is the only approach that allows measuring these large samples. The unconditional free release of wastes originating from nuclear activities for a great deal relies on NDA systems and procedures for decision-making on free release. The assay of waste of very low activity and even the decision if a radionuclide has been detected or not, is very often difficult. The poor measurement precision, caused by the bad counting statistics, combined with a generally unknown bias of the measurement complicate the interpretation of the results, and accurate measurements are seldom obtained in these cases. The aim of the present paper is to give an overview of the efforts made at SCK-CEN to come to a consistent system that allows performing free release measurements, involving a high throughput of large amount of materials, as expected from a dismantling project.

Detection efficiency calibration of gamma spectroscopy for waste assay systems is a difficult and time-consuming task. Commonly, reference waste packages are used for efficiency calibration but these are sometimes difficult to build, are expensive and have limited use since there is large variability of parameters which influence the assay. Numerical calibrations, however, are an interesting alternative and have begun to find more and more application in waste assay. A dedicated computer code, Solidang, has been developed to compute detection efficiencies for gamma waste assay. Solidang uses the effective solid angle approach to derive detection efficiency and aims at improving and facilitating the calibration of gamma waste assay systems and at serving as a tool to investigate the influence of the many system and sample parameters involved.

The non-destructive quantification of transuranic elements in nuclear waste management or in safeguards verifications is commonly performed by passive neutron assay techniques. To minimise the number of unknown sample-dependent parameters, Neutron Multiplicity Counting (NMC) is applied. We developed a new NMC-technique, called Time Interval Correlation Spectroscopy (TICS), which is based on the measurement of Rossi-alpha time interval distributions. Compared to other NMC-techniques, TICS offers several advantages.