Low-level Gamma-ray Spectrometry Research Articles

Effect of Location and Shielding on Gamma Radiation Background in Low Level Gamma Ray Spectrometry

Effect of Location and Shielding on Gamma Radiation Background in Low Level Gamma Ray Spectrometry

Radionuclide metrology methods and analysis of the Joint Danube Survey 4 sediment samples

This low-level radionuclide metrology research work was carried out within the Joint Danube Survey 4 (JDS4), coordinated in 2018–2020 by the International Commission for the Protection of the Danube River (ICPDR). The gamma-emitting radionuclides of the sediment samples were analysed by low-level gamma-ray spectrometry. The activity concentration of 90Sr was determined by liquid scintillation counting (LSC) after isolating the radio-strontium using a new radiochemical separation method. The results of the radiometric analysis of 90Sr, 137Cs and naturally occurring radionuclides 40K, 210Pb, 226Ra, 228Ra in recent riverbed sediment are presented and discussed focused on public health.

Identification, isolation, and characterization of a novel type of Fukushima-derived microparticle

In the course of the Fukushima nuclear accident, radionuclides were released in various forms, including so-called radiocesium-bearing microparticles (CsMP). So far, four types of CsMP were described: Type A is smaller in size (< 10 μm), Types B, C, and D are larger (> 100 μm). In this work, we present a novel type of CsMP (proclaimed Type E). Three particles of Type E were extracted from a contaminated blade of grass that was sampled 1.5 km from the Fukushima Daiichi nuclear power plant in late 2011. They were located using autoradiography, isolated using an optical microscope and micromanipulator, and characterized using scanning electron microscopy, energy dispersive x-ray spectroscopy, and low-level gamma-ray spectrometry. Type E CsMPs are 10–20 μm in size and exhibit an unusually low and barely detectable 137Cs activity of only ≤ 10 mBq per particle. Their brittle and fragile character may indicate a high surface tension.

Towards using secondary gamma-rays from proton-induced radioactivation of titanium implants for off-line field verification

This experimental study investigates the radioactivation of titanium during proton therapy. Titanium is a commonly used material for implants. Because of its fixed position, the activation of those implants might be useful for post-irradiation field. Various titanium samples are irradiated at the West German Proton Therapy Centre Essen. The activities of the produced radionuclides are obtained with a low-level gamma-ray spectrometry system at the Dortmund Low Background Facility. Furthermore, an irradiated titanium sample is placed in a pre-clinic PET/CT scanner to investigate the potential of the implants for range verification. With the gamma-ray spectrometry technique a number of radionuclides are identified as candidates for range verification with delayed secondary gamma-rays. Furthermore, activation cross sections are calculated with the activities for the identified radionuclides. The depth distribution of the activity as obtained with the PET/CT scans has a characteristic rise towards the distal end similar to the depth dose curve.

Calibration and use of well-type germanium detectors for low-level gamma-ray spectrometry of sediments using a semi-empirical method

Gamma-ray spectrometry is a widely used technique to quantify the presence of numerous radionuclides in environmental samples. In this work, we describe a methodology for efficiency calibration of four well-type germanium detectors and their use for the determination of low-level activities of gamma emitters in sediment samples. An experimental efficiency calibration for each detector was built with three materials for 17 energies, ranging from 46.5 keV to 1460 keV. For efficiency transfer to different geometries and sample types, we used the effective solid angle approach (ET-Ω method). Final calibrations were calculated for all detectors, several counting geometries, and elemental composition of selected sample types. Calibrations were validated with six reference materials. This methodology allowed to reliably analyze nine gamma emitters (210Pb, 241Am, 234Th, 228Ac, 214Pb, 208Tl, 137Cs, 134Cs and 40K) in sediment samples. Using these calibrations, gamma emitter profiles of sediment cores from contrasting aquatic systems (lake, intertidal, marine and deep-sea areas) provided reliable profiles of 210Pb and artificial radionuclides useful for dating and stratigraphic interpretation. A protocol to implement this methodology is also presented.

Geographical origin of bivalve molluscs in coastal areas using natural radioactivity fingerprinting and multivariate statistical analyses: Andalusian coast as case of study.

The presence of natural and artificial radionuclides in the marine environment produces the accumulation of radionuclides in bivalve molluscs consumed by humans, and therefore it could result in a radiological hazard. In this study, the activity concentrations of 210Po, 40K, 210Pb and 234Th were determined in different types of bivalve molluscs sampled during the period of May 2014-June 2015, along coastal areas from the Andalusian region (South of Spain), through alpha-particle spectrometry and low-level gamma-ray spectrometry. The activity concentrations of 210Po; 40K; 210Pb and 234Th varied between 40 ± 2 and 515 ± 9 Bq kg-1 dry weight (d.w.); 121 ± 7 and 674 ± 34 Bq kg-1 d.w.; ND (lower than limit of detection) and 73 ± 10 Bq kg-1 d.w.; and ND and 126 ± 27 Bq kg-1 d.w., respectively. The committed effective dose to humans was calculated to range from 41 to 479 μSv year-1. Both activity concentrations and dose levels were comparable to previous studies from other countries. Finally, a multivariate statistical analysis of natural radioactivity content allowed the discrimination between bivalve molluscs from Atlantic and Mediterranean coasts.

Baseline activity concentration of 210Po and 210Pb and dose assessment in bivalve molluscs at the Andalusian coast

In this study, the activity concentrations of 210Po and 210Pb were determined in different types of bivalve molluscs sampled during the period of May 2014–June 2015 along the Andalusian littoral. Radioactivity concentrations of 210Po were determined through alpha-particle spectrometry using 209Po as an internal tracer. Radioactivity concentrations of 210Pb were determined through low-level gamma-ray spectrometry. The activity concentrations of 210Po and 210Pb varied between 40 ± 2 and 515 ± 9 Bq kg−1 dry weight (d.w.), and ND (lower than limit of detection) and 73 ± 10 Bq kg−1 d.w., respectively. The committed effective dose to humans was calculated to range from 39 to 477 μSv year−1. Radioactivity and dose levels were compared with previous studies from other countries.

A method for the complete analysis of NORM building materials by γ-ray spectrometry using HPGe detectors

A methodology including software tools for analysing NORM building materials and residues by low-level gamma-ray spectrometry has been developed. It comprises deconvolution of gamma-ray spectra using the software GALEA with focus on the natural radionuclides and Monte Carlo simulations for efficiency and true coincidence summing corrections. The methodology has been tested on a range of building materials and validated against reference materials.

Low-level gamma-ray spectrometry for the determination of 210Pb

A well High purity germanium (HPGe) gamma spectrometer with NaI(Tl) Compton anticoincidence shield recently installed at DTU Nutech and specially designed for low-level measurements was used for the 210Pb determination in environmental samples. The system is compared to standard stand-alone HPGe spectrometers. The choice between high efficiency well and planar detectors as well as optimum sample size depending on available sample quantity are discussed. Results show that the only comparative advantage of the well anticoincidence system is when just small sample sizes are available.

The Dortmund Low Background Facility — Low-background gamma ray spectrometry with an artificial overburden

The Dortmund Low Background Facility is an instrument for low-level gamma ray spectrometry with an artificial overburden of ten meters of water equivalent, an inner shielding, featuring a neutron absorber, and an active muon veto. An integral background count rate between 40keV and 2700keV of (2.528±0.004)counts/(kgmin) enables low-background gamma ray spectrometry with sensitivities in the range of some 10mBq/kg within a week of measurement time.

High-sensitivity HPGe gamma-spectrometry analysis of radionuclides in Martian meteorites

Analysis of cosmogenic radionuclides in Martian meteorites is a great radioanalytical challenge because of the high scientific value of these meteorites, and necessity to apply non-destructive methods of analysis, e.g., low-level gamma-ray spectrometry. The measured 54Mn, 22Na, and 26Al levels in two fragments of the Tissint meteorite, a recent fall (18 July 2011), were 0.9, 1.1 and 0.6 Bq/kg in average. The high 22Na/26Al activity ratio (1.89 ± 0.05) measured in the larger sample (908.7 g) indicates an unsaturated production of 26Al in the Tissint meteorite.

NORM in soil and sludge samples in Dukhan oil Field, Qatar state

Abstract: The main objective of this work is to measure the activity concentrations of Naturally Occurring radioactive Materials (NORM) produced as a buy products in oil production. The analyses of NORM give available information for guidelines concerning radiation protection. Recently NORM subjected to restricted regulation issued by high legal authority at Qatar state. Twenty five samples of soil from Dukhan onshore oil field and 10 sludge samples collected from 2 offshore fields at Qatar state. High resolution low-level gamma-ray spectrometry used to measure gamma emitters of NORM . The activity concentrations of natural radionuclide in 22 samples from Dukhan oil field, were with average worldwide values . Only three soil samples have high activity concentration of Ra-226 which is more than 185 Bq/kg the exempted level for NORM in the Quatrain regulation. The natural radionuclide activity concentrations of 10 sludge samples from offshore oil fields was greater than 1100Bq/kg the exempted values of NORM set by Quatrain regulation so the sludge need special treatments. The average hazards indices (H ex , D , and Ra eq ), for the 22 samples were below the word permissible values .This means that the human exposure to such material not impose any radiation risk. The average hazards indices (H ex , D , and Ra eq ),for 3 soil samples and sludge samples are higer than the published maximal permissible. Thus human exposure to such material impose radiation risk.

Activity measurement and effective dose modelling of natural radionuclides in building material

In this paper the assessment of natural radionuclides' activity concentration in building materials, calibration requirements and related indoor exposure dose models is presented. Particular attention is turned to specific improvements in low-level gamma-ray spectrometry to determine the activity concentration of necessary natural radionuclides in building materials with adequate measurement uncertainties. Different approaches for the modelling of the effective dose indoor due to external radiation resulted from natural radionuclides in building material and results of actual building material assessments are shown.

Estimation of &lt;SUP align="right"&gt;238&lt;/SUP&gt;U, &lt;SUP align="right"&gt;232&lt;/SUP&gt;Th and &lt;SUP align="right"&gt;40&lt;/SUP&gt;K concentrations in rock and soil samples around South Purulia Shear Zone, India

The first few measurements for low level gamma ray spectrometry for the delineation of U and Th along South Purulia Shear Zone (SPSZ) are reported. Estimation of 238U, 232Th and 40K concentrations in widely dispersed rock and soil samples around SPSZ has been undertaken using HPGe detector having relative efficiency of 50%. The maximum concentration among all the samples studied is observed in the sample close to the Beldih region, SPSZ. An attempt has been made to study the variation in the concentration of these rock and soil samples with respect to location from the shear zone. Central part of the shear zone is found to contain higher concentration of radionuclides than the samples from the periphery. This proves that intensity of shearing controls the activity of radionuclides in a sample, apart from alteration, metamorphism, weathering, etc. A comparison of radionuclide activities of soil samples in study area with other studies worldwide is reported.

LAFARA: a new underground laboratory in the French Pyrénées for ultra low-level gamma-ray spectrometry

We describe a new underground laboratory, namely LAFARA (for “LAboratoire de mesure des FAibles RAdioactivités”), that was recently created in the French Pyrénées. This laboratory is primarily designed to analyze environmental samples that display low radioactivity levels using gamma-ray spectrometry. Two high-purity germanium detectors were placed under 85 m of rock (ca. 215 m water equivalent) in the tunnel of Ferrières (Ariège, France). The background is thus reduced by a factor of ∼20 in comparison to above-ground laboratories. Both detectors are fully equipped so that the samples can be analyzed in an automatic mode without requiring permanent presence of a technician in the laboratory. Auto-samplers (twenty positions) and systems to fill liquid nitrogen automatically provide one month of autonomy to the spectrometers. The LAFARA facility allows us to develop new applications in the field of environmental sciences based on the use of natural radionuclides present at low levels in the environment. As an illustration, we present two of these applications: i) dating of marine sediments using the decay of 226Ra in sedimentary barite (BaSO4), ii) determination of 227Ac (231Pa) activities in marine sediment cores.

First fusion proton measurements in TEXTOR plasmas using activation technique

MeV particle loss measurements from fusion plasmas, in particular alpha particles, remain difficult in large fusion devices and further R&D is needed for ITER. This paper describes the first attempt to measure 3 MeV escaping fusion protons emitted from TEXTOR tokamak plasmas using activation technique. This technique was successfully demonstrated, initially, in 2006 on the JET tokamak. An ion camera equipped with a collimator and several types of activation detectors was installed inside the TEXTOR vacuum vessel to perform these measurements. After irradiation, the detectors were analyzed using ultra low level gamma-ray spectrometry at the HADES underground laboratory. 3 MeV escaping fusion protons were detected in larger number -~6 times more--compared to earlier measurements using this technique on JET. Another major progress was the reduction of the cooling time by a factor of 50, which made possible to detect radionuclides with half-life of less than 90 min.

Distribution of 60Co in steel samples from Hiroshima

This paper describes ultra low-level gamma-ray spectrometry measurements of the 60Co activity distribution inside one 52mm and one 41mm thick steel sample. The samples had been exposed to the Hiroshima atomic bomb and were from the Aioi bridge and the Yokogawa bridge. Both samples were measured in a recent study aiming to back up model calculation of Hiroshima dosimetry. The 60Co activity distributions found in this study support the assumptions made in the previous study.

Monitoring the leakage of 3.0 and 14.7 MeV protons from a fusion plasma

An experiment to study, separately, the leakage of protons of 3.0 and 14.7 MeV in the JET Tokamak, is presented. The activity of the activation products induced by the plasma in different samples that were placed inside the Tokamak was measured using ultra low-level gamma-ray spectrometry (ULGS). Stacking of some of the samples during activation allowed differentiating between the protons of 3.0 and 14.7 MeV that originated in two different reactions in the plasma. For the B 4C sample the ratio of the 3.0 and 14.7 MeV proton flux could be determined as 0.17(10) assuming normal incidence and 0.31(16) assuming 45° incidence. For LiF the result obtained was that, within the uncertainty, there was no contribution from the 3.0 MeV protons.

Natural radioactivity in winter wheat from organic and conventional agricultural systems

The distribution of natural radionuclides was studied in winter wheat plants collected from three sites in Belgium during 2004–2007. Activity concentrations of 40K, 226Ra, 228Ra and 228Th in organically and conventionally grown wheat, and in the corresponding soil samples, were determined using ultra low-level gamma-ray spectrometry. The observed soil-to-wheat concentration ratios were calculated for the different parts of the wheat plant (root, stem and grain) in the two agricultural systems (organic and conventional). There were large variations in radionuclide activity concentrations between the sites and fields, but no significant difference between conventionally and organically grown wheat plants was observed.

226Ra and 228Ra determination in mineral waters—Comparison of methods

A comparison of different radiochemical separation procedures and measurement techniques used to determine the activity concentration of (226)Ra and (228)Ra in water is made with respect to accuracy, detection limits and turn-around time. Radium-226 activity concentration was determined by the radon emanation technique, alpha-particle and gamma-ray spectrometry. To determine the (228)Ra activity concentration, four different techniques were used: low-level liquid scintillation counting, low-level proportional counting, alpha-particle and low-level gamma-ray spectrometry.