Neutron Activation Research Articles

Actinide isotope analysis and trace element composition of bones of prehistoric animals and humans by inductively coupled plasma mass spectrometry (ICP-MS)

AbstractInductively coupled plasma mass spectrometry (ICP-MS) has been used for analysis of the bones of archanthropus, ancient bear, southern mammoths, dinosaurs, as well as soils collected in various parts of Uzbekistan. The concentrations of 64 elements have been detected including thorium and uranium for which isotope compositions were also analysed. The comparison of the ICP-MS data with the results we obtained earlier for some bones using instrumental neutron activation analysis (INAA) is presented. The concentrations of 234, 235, 238U are up to two orders of magnitude elevated compared to the soils (e.g.238U in south mammoth bone—130.1 mg/kg, and that of soil is only 1.6 mg/kg). The levels of 236U, and 239, 240, 242, 244Pu isotopes (possible neutron capture products of 235U and 238U) correspond to a count rate of blank samples. In addition, the isotope analysis confirms the uranium in the bones and surrounding soils is natural (the average determined for all samples uranium ratios 235U/238U = 0.0071 ± 0.0003 (2-sigma errors). The concentration of 230Th (which is the part of 234U and 238U decay chain) is also elevated in the bones compared to the surrounding soils, however, the concentrations of stable 232Th largely correspond to those of the soil. The excess uranium detected in bones is most probably due to the preferential accumulation from soil, and not to the paleo diet.

Improving instrumental neutron activation analysis detection limit using Monte Carlo simulation for lanthanides determination in Algerian phosphate

ABSTRACT Instrumental Neutron Activation Analysis (INAA) is one of the best methods to analyse Rare Earth Elements (REE) with a low detection limit in phosphate samples. Since most lanthanides emit gamma rays at the energy below 1000 keV, this energy range is affected by the Bremsstrahlung noise of beta emission produced by the 31P(n,γ)32P reaction, when the irradiation of the P2O5 composing the phosphate matrix (approximately 30%). This beta (β−) spectrum with a maximum energy of 1.71 MeV (average energy of 695 keV) affects the gamma spectrum and will reduce the detection limit significantly, other factors decrease the detection limit of lanthanides like neutron self-shielding and interference. In the present work, an analysis methodology based on optimising the measurement parameters of the INAA technique was implemented to improve the detection limits for the precise evaluation of lanthanide concentrations in Algerian phosphate deposits. The complete procedure was developed using a combination of a Monte Carlo simulation approach and experimental measurements. Two models were developed based on Monte Carlo simulation for the calibration of HPGe detector efficiency and the optimisation of type and filter thickness to reduce the beta spectrum (Bremsstrahlung) emitted by the 32P produced by neutron capture reaction 31P(n, γ) 32P. The developed model allowed a considerable improvement in the detection limit of the INAA technique and reduced the uncertainty in the lanthanide concentration. Finally, the methodology was applied to determine lanthanide elements in phosphate samples with good precision.

Core Optimization for Extending the Graphite Irradiation Lifespan in a Small Modular Thorium-Based Molten Salt Reactor

The lifespan of core graphite under neutron irradiation in a commercial molten salt reactor (MSR) has an important influence on its economy. Flattening the fast neutron flux (≥0.05 MeV) distribution in the core is the main method to extend the graphite irradiation lifespan. In this paper, the effects of the key parameters of MSRs on fast neutron flux distribution, including volume fraction (VF) of fuel salt, pitch of hexagonal fuel assembly, core zoning, and layout of control rod assemblies, were studied. The fast neutron flux distribution in a regular hexagon fuel assembly was first analyzed by varying VF and pitch. It was demonstrated that changing VF is more effective in reducing the fast neutron flux in both global and local graphite blocks. Flattening the fast neutron flux distribution of a commercial MSR core was then carried out by zoning the core into two regions under different VFs. Considering both the fast neutron flux distribution and burnup depth, an optimized core was obtained. The fast neutron flux distribution of the optimized core was further flattened by the rational arrangement of control rod channels. The calculation results show that the final optimized core could reduce the maximum fast neutron flux of the graphite blocks by about 30% and result in a more negative temperature reactivity coefficient, while slightly decreasing the burnup and maintaining a fully acceptable core temperature distribution.

Essential and toxic elements determination in Ampelodesma mauritanicum plant based on gamma-ray spectrometry

Due to the scarcity of data on both basic and toxic chemical elements in medicinal and fodder plants in Algeria, this study focused on evaluating the content of these elements in the Ampelodesma mauritanicum plant grown in the Ghardaia region of Southern Algeria. This plant is commonly used by Bedouins in traditional medicine and as fodder, and has applications in construction, decontamination, and water purification. Based on gamma-ray spectrometry for neutron activation analysis, the study identified and categorized a total of 25 mineral and trace elements into essential, non-essential, and potentially toxic groups. Essential elements exhibited varying concentrations, with potassium being the most abundant, followed by sodium, calcium, iron, zinc, chromium, cobalt, and selenium. The study also assessed potentially toxic elements, all found below the estimated permissible limits established by FAO/WHO. Quality control was ensured through the analysis of certified reference materials. The findings provide valuable insights into the elemental composition of Ampelodesma mauritanicum, offering significant implications for medicinal and nutritional applications while ensuring analytical accuracy and reliability.

Microstructural changes induced in advanced tungsten grades under high temperature neutron irradiation

Recent studies addressing the change of mechanical properties after high temperature irradiation of tungsten have reported substantial increase of the ductile to brittle transition temperature as well as increase of the hardness. In this work, we performed microstructural analysis by means of transmission electron microscopy (TEM) on various tungsten grades earlier exposed to high temperature neutron irradiation at 1200 °C up to 1 dpa. The latter corresponds to the expected irradiation temperature on the surface of a tungsten monoblock during the steady state operation in ITER. TEM was applied to five tungsten (W) materials including ITER specification pure W and precipitate strengthened W alloys. The analysis of TEM data coupled with its discussion led to a number of important conclusions regarding the damage induced at 1200 °C neutron irradiation such as: (i) weak effect of recrystallization on the accumulation of the lattice damage; (ii) promising results on the tolerance of damage accumulation in W-Y2O3 grade and (iii) internal oxidation of TiC particles which may contribute to the huge increase of the irradiation induced hardening.

Petrographic and geochemical analyses of pottery from Wadi Tanuf, Oman: Approaching pottery production in south‐eastern Arabia during the second and first millennia BCE

AbstractThis study describes the petrographic and geochemical characteristics of pottery collected from Mugharat al‐Kahf and WTN02 in Wadi Tanuf, north‐central Oman, to clarify interregional similarities and differences in pottery production techniques and examine the existence of interregional trade in pottery with respect to changes in mobile communities. Potsherds from these sites were characterised using thin‐section petrography and instrumental neutron activation analysis. Results revealed that several clay fabrics and tempers were used during the Wadi Suq period (2000–1600 BCE). A region‐wide similarity exists in pottery‐making techniques in terms of the tempering of specific minerals (Oman ophiolite) used in the Early Iron Age (1300–300 BCE). Geochemical results indicate differences in clay sources between the Wadi Suq period and the Early Iron Age in Wadi Tanuf and the unlikelihood of the interregional trade of domestic pottery.

Determination of moisture content in coal using pulsed fast thermal neutron activation technique

The quality of coal is greatly influenced by the residual moisture content, which in turn affects the Gross Calorific Value (GCV) by limiting the maximum energy that can be extracted from a given mass of coal. Various methods have been developed to measure this residual moisture, including gravimetric techniques, near-infrared spectroscopy, microwave, and infrared moisture meters. Amongst these, neutron-based techniques offer distinct advantages for bulk and rapid characterization, making them suitable for online monitoring. This article presents the use of a Pulsed Fast Thermal Neutron Activation technique to determine moisture content in various coal samples acquired from Indian coal mines. A 14.1 MeV D-T neutron source coupled with a Bismuth Germanate (BGO) detector and associated electronics have been used. The hydrogen content in the sample has been used as an indicator for the moisture and the technique has been calibrated with samples of known moisture content. The results obtained for the coal samples demonstrate a remarkable agreement with the findings of proximate analysis. A minimum quantity of 2% moisture by weight has been detected with a relative error of 0.4%.

Correlation between nutrients, rare earth elements and heavy metals in O. Sativa rice plant organs by instrumentation neutron activation analysis and proton induced x-ray emission techniques

The accumulation of halogens and metals from roots to stems, leaves and grains of Oryza sativa rice plant collected in Northern Senegal (St Louis region) at the same stages of growth but at different salinity soil levels was investigated by measuring their elemental concentration by invasive instrumental techniques of neutron activation analysis and proton induced x-ray emission. The normalized elemental concentration of Na, Cl, K, (Cs, Rb, Sr, Sb, Ba Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Br, Rb, Sb was correlated with one of rare earth elements, La, Ce, Sm, Yb, Nd, Eu, Tb, Tm, and Lu) and the one of the heavy metals Hf, Ta and Th and to assess their subsequent distribution within the Oryza sativa rice plant in a particular salinity environment. The exploration of the experimental data was performed by applying machine learning techniques with Python to find their elemental correlations. This study shows that the accumulation of iron is highly correlated with the amount of rare earth elements and heavy metals investigated. We observe an inverse correlation between Fe and Cl concentrations in the roots and stems of the Oryza sativa rice plant, in which higher levels of Fe in the roots relative to stems correspond to lower levels of Cl. We also remark that there is no accumulation of rare earth elements in the root tissues of the different Oryza sativa rice plants studied. Whereas, in the stem, leaf, and grain organs there is a strong correlation between metal contents and rare earth elements.

Measurements of neutron capture cross-sections for nuclides of interest in decommissioning: 45Sc, 63Cu, 64Zn, 109Ag, and 113In

ABSTRACT As nuclear facilities are dismantled in decommissioning, various and large amounts of waste are generated. Even more inconveniently, they are radioactive waste due to neutron activation. Thus, the neutron capture cross-sections of nuclides targeted for decommissioning are required to evaluate the radioactivity produced. The present study selected 45Sc, 63Cu, 64Zn, 109Ag and 113In among targeted nuclides, and performed the measurements of thermal-neutron capture cross-sections by an activation method at the Kyoto University Research Reactor. The thermal-neutron capture cross-sections were derived on the basis of Westcott’s convention. The present results were obtained as follows: 27.18 ± 0.28 barn for 45Sc(n,γ)46Sc, 4.34 ± 0.06 barn for 63Cu(n,γ)64Cu, 0.719 ± 0.011 barn for 64Zn(n,γ)65Zn, 4.05 ± 0.05 barn for 109Ag(n,γ)110mAg and 8.53 ± 0.27 barn for 113In(n,γ)114Inm1+m2 reactions. The results for 45Sc and 64Zn support evaluated cross-section data within the limits of uncertainties, while those for the other nuclides were slightly different from evaluated ones. The obtained results are useful not only for the evaluation of isotope production, but also for the consideration of those nuclides as flux monitors, as an alternative to Au and Co.

Capture enhanced neutron irradiation for the treatment of the Alzheimer Disease: Micro-nanodosimetric characterization of beta amyloid peptide samples

Alzheimer Disease (AD) is the most common cause of dementia. 46.8 million people live with AD worldwide, with numbers projected to almost double every 20 years. The etiological mechanisms underlying the neuropathological changes in AD remain unclear. The beta amyloid peptide Aβ is considered to be the main culprit of the pathological processes. NECTAR (NEutron Capture-enhanced Treatment of neurotoxic Amyloid aggRegates) project proposes an alternative and revolutionary strategy to address AD, investigating the safety, feasibility and effectiveness of a Capture-Enhanced Neutron Irradiation to structurally damage Aβ aggregates, by exploiting capture agent vectors containing B-10 and Gd-157.Among many others, one of the goals of the project is to perform calculations and measurements of microdosimetric and nanodosimetric quantities to characterize the effect of reaction products at local level and to link it to the fibrils depolymerization process. In this framework, a new low-pressure tissue-equivalent proportional counter (TEPC) was designed and developed. The system is a wall-free TEPC able to measure micro-nanometric dose deposition for different biological samples. It is characterized by two main features: i) a wall-less structure allows the charged particles produced by the sample to access the sensitive volume, where their effects are studied; ii) a trigger system enables the assessment of the number of ionizations induced in the sensitive volume related to a single primary particle for obtaining nandosimetric information.The prototype system was tested in the PGNAA (Prompt Gamma Neutron Activation Analysis) facility of the LENA reactor (Pavia) to directly study secondary particles from Aβ fibrils, loaded with Boron. Results of the micro-nanodosimetric characterization of high LET secondaries from Aβ-fibrils were compared to a reference Boron sample. For a 500 nm simulated site size, the presence of Boron in the Aβ sample greatly populates microdosimetric spectra at high lineal energy values. Instead, lower LET particles (photons, protons) from reactions on the other Aβ aggregate solution molecules populate the low lineal energy portion of the distribution.The nanodosimetric distributions highlights the presence of different field components on the nanodosimetric spectra: low LET particles (protons/electrons) produce small ionization clusters, while alpha and Lithium ions induce larger clusters, thus have a higher biological effect. The nanodosimetric measurements have been compared with Monte Carlo simulations performed with a track-structure code, showing a good agreement.This multi-level approach provides a deeper physical understanding of the mixed secondaries field coming from B-enriched target, as well as a reference for the biological effect on Aβ fibrils at nanometer level. These preliminary measurements represent the first microdosimetric and nanodosimetric characterization of the secondary mixed field directly emitted by a biological sample irradiated with neutrons.

A novel aloe vera mediated Bismuth–Magnesium–Copper nanocomposite for radiation shielding applications

In the current study, Bismuth-Magnesium-Copper nanocomposites (BMC NCs) are synthesized using versatile solution combustion synthesis using Alovera extract as a reducing agent. As obtained BMC NCs are characterized using standard techniques. Bragg’s reflections confirmed the formation of multi-phase BMC NCs with crystal sizes 18.11 nm and 21.12 nm. The surface morphology of BMC NCs confirmed the agglomeration of spherical-shaped nanoparticles. EDAX spectrum analyzed the presence of Bi, Mg, and Cu. The direct energy gap is found to be 3.08 eV. X-ray/gamma radiation shielding properties are then evaluated using a NaI(Tl) detector coupled with MCA. Shielding parameters are slightly higher than lead. Neutron shielding parameters are compared with conventional shielding materials. Scattering length is found to be 8.8 fm, and neutron absorption cross-section and neutron attenuation parameters of BMC NCs are found to be efficient when compared with lead, concrete, and steel. Bremsstrahlung radiation shielding parameters are computed at 1.511 MeV. Bremsstrahlung efficiency is comparable to lead, bremsstrahlung dose rate and specific bremsstrahlung constant are found to be more in comparison with lead. Thus, BMC NCs are highly efficient in shielding X/gamma ray and neutron radiations.

BNCT Pancreatic Cancer Treatment Strategy with glucose-conjugated boron drug

Multidisciplinary therapy centered on radical surgery for resectable pancreatic cancer is expected to prolong prognosis, but relies on CA19-9 biomarker levels to determine treatment strategy. Boron neutron capture therapy (BNCT) is a chemoradiotherapy using tumor hyperaccumulator boron drugs and neutron irradiation. The purpose of this study is to investigate novel boron drug agents for BNCT for pancreatic cancer. Bioinformatics was used to evaluate the uptake of current boron amino acid (BPA) drugs for BNCT into pancreatic cancer. The expression of the amino acid transporter LAT1, a BPA uptake transporter, was low in pancreatic cancer and even lower in high CA19-9 pancreatic cancer. In contrast, the glucose transporter was high in high CA19-9 pancreatic cancers and inversely correlated with LAT1 expression. Considering the low EPR effect in pancreatic cancer, we synthesized a small molecule Glucose-BSH, which is boron BSH bound to glucose, and confirmed its specific uptake in pancreatic cancer. uptake of Glucose-BSH was confirmed in an environment compatible with the tumor microenvironment. The therapeutic efficacy and safety of Glucose-BSH by therapeutic neutron irradiation were confirmed with BNCT. We report Glucose-BSH boron drug discovery study of a Precision Medicine BNCT with application to high CA19-9 pancreatic cancer.

Impact of neutron irradiation on the tensile properties of advanced EUROFER97 - type steels

Impact of neutron irradiation on the tensile properties of advanced EUROFER97 - type steels

Development and validation of a Bayesian unfolding program using OpenBUGS open-source software for Bonner spheres neutron spectrometry

This study presents the development of a novel unfolding program based on a Bayesian method for Bonner spheres spectrometry. The program incorporates a priori information on the neutron spectrum, employing a linear superposition of three non-negative parametric functions: thermal-Maxwellian distribution, an intermediate region represented by a straight line in lethargy space (1/E behavior), and the Watt fission distribution for the fast region. The effectiveness of the developed program was validated through its application to two reference cases from the EURADOS 2018 exercise (LINAC and Skyshine), followed by its implementation in characterizing the neutron field around an OB26 neutron irradiator at the Secondary Standards Dosimetry Laboratory (SSDL) of the Nuclear Research Center of Algiers (CRNA), Algeria. While validation results for the LINAC case were promising, achieving comparable neutron spectrum shape and integral quantities to the reference, challenges were encountered with the Skyshine case. However, these challenges were partially addressed through sensitivity analysis, resulting in slightly improved outcomes compared to the previous participation and to the reference. Application of the program to characterize the neutron field around the OB26 irradiator yielded satisfactory results when compared to reference data. A two-step sensitivity analysis further enhanced the outcomes, initially substituting the Watt fission distribution with the evaporation distribution, thereby improving spectrum shape and integral quantities. Subsequently, utilizing the obtained neutron spectra as prior information for unfolding codes MAXED and GRAVEL ensured stability and agreement with reference data and preliminary results.

Effect of 14.1 MeV Fusion Neutron Irradiation on YBCO Thin Films and Commercial REBCO Tapes

Effect of 14.1 MeV Fusion Neutron Irradiation on YBCO Thin Films and Commercial <i>RE</i>BCO Tapes

Effect of hydrogen, helium and dose rate on the evolution of dislocation loop in pure iron during in-situ irradiation

Simulating neutron irradiation with ion irradiation requires considering the comprehensive effects of hydrogen, helium and dose rate to fully understand the microstructure evolution of material in an irradiation environment. Here, the characterization and evolution of dislocation loops in pure iron were investigated under heavy ion irradiation with four different injected gas ion types (Fe+, Fe++H2+, Fe++He+ and Fe++H2++He+) and under dual-beam (Fe++He+) irradiation with four different dose rates using in-situ transmission electron microscopy at 723 K. Comparing to the single-beam (Fe+) irradiation, the additional injection of H or He, or co-injected H and He, mainly promoted the nucleation of dislocation loops at the early stage of irradiation and enhanced loop growth after that. Among them, the simultaneous irradiation of triple beams (Fe++H2++He+) were most pronounced. Moreover, triple-beam (Fe++H2++He+) irradiation resulted in the highest ratio of the rotation of loop habit-plane. Under dual-beam (Fe++He+) irradiation, the results demonstrated that as the dose rate increased, the loop density increased and the loop size decreased. Moreover, the fraction of <100> loops at low dose rate was noticeably greater than that at high dose rate. The results of the current work provide important references for a better understanding of the effectiveness of ion irradiation in simulating neutron irradiation.

Structure, mechanical, and neutron radiation shielding characteristics of mechanically milled nanostructured (100-x)Al-xGd2O3 metal composites

Metallic substances are favored for storing and transporting spent nuclear fuels (SNFs) due to their thermal stability, mechanical strength, and corrosion resistance. Adding gadolinium (Gd) significantly enhances neutron shielding, improving efficiency with reduced thickness and dimensions. In this study, Al-Gd2O3 metal nanocomposites were synthesized using powder-processed mechanical milling. The crystal structure features of (100-x)Al-x%Gd2O3 samples with varying percentages of Gd2O3 (5%, 10%, and 15 % by weight) were analyzed by X-ray diffraction. Microstructural properties were studied using scanning and transmission electron microscopy (SEM and TEM). The synthesized composites' neutron and γ- radiation shielding characteristics were investigated theoretically using the MCNP6.2 transport code. Analysis of the XRD data revealed prominent peak shifts with increased milling time, indicating reduced particle sizes. Differential scanning calorimetry (DSC) indicated Gd2O3-induced changes in temperature behavior, and the Vickers microhardness tests demonstrated enhanced mechanical strength with increasing gadolinium concentration. Improved neutron radiation shielding was observed with higher Gd2O3 content. Our study highlights the potential of Gd2O3-enriched metal matrix composites for advanced industrial applications.

Commissioning of the first hospital-based PET radiopharmaceutical cyclotron in Greece: Personnel dose assessment.

The role of positron emission tomography (PET) imaging with 2-fluoro-2-deoxy-D-glucose (FDG) is well established in the diagnosis and management of cancer patients. As the demand for PET imaging continues to rise, many hospitals are installing on-site self-shielded mini cyclotrons to produce their own radiopharmaceuticals, including FDG. In May 2021, the Dose-on-Demand Biomarker Generator (BG-75) was installed at the Metaxa Cancer Hospital in Greece, making it the first hospital-based PET radiopharmaceutical cyclotron in the country. During commissioning, the expected external exposure for personnel was established, and internal exposure was found to be negligible. Personnel dose was estimated with two methods: survey meter measurements in various locations combined with the time spent in each location, and direct measurement using electronic personal dosemeters. Gamma and neutron radiation readings outside the cyclotron vault were at background levels. Inside the cyclotron vault, the highest recorded readings by the target were 18 μSv/h for both gammas and neutrons; at one meter, the values were 5 μSv/h and 4 μSv/h, respectively. Based on these measurements, the annual expected whole-body dose per operator is 0.6 mSv, and the respective extremity dose is 16 mSv. The annual expected whole body and extremity dose for the radiochemist is 0.3 mSv and 25 mSv, respectively. The expected dose estimates for the medical physicists are also below 1 mSv. These doses are well below the regulatory limits and local As Low As Reasonably Achievable (ALARA) levels. With experience and a robust ALARA program, personnel exposure could be further reduced.&#xD.

Bioconcentration and translocation of elements from soil to vegetables and associated health risk

This study provides valuable insights into the bio-concentration and translocation of elements from soil to plants, addressing potential health risks associated by the neutron activation analysis. The results showed that arsenic (As) and Zinc (Zn) concentrations in the soil were higher than national regulations for heavy metals in agricultural soil in Vietnam but remained within permissible limits recommended by the World Health Organization (WHO). Different plant species show varying affinities for the accumulation of elements, indicating their potential use for specific remediation purposes. Rainbow beet (Beta vulgaris) were considered for phytoextraction of cesium (Cs), chromium (Cr), and aluminum (Al). Bioconcentration factors (BCF) for both root and shoot tissues for all elements were lower than unity (except manganese (Mn 1.04)). This suggests that green lollo rossa has the potential to accumulate Mn in its root system. The target hazard quotient ranged from 0.01 for antimony (Sb) to 0.26 for chromium (Cr). This study indicated that the vegetables investigated in the study area do not pose a risk to consumers for the analyzed potential toxic elements.

Evaluation of elemental pollution in soil samples from Klang industrial area

Rapid development in industries will contribute to the pollution of the soil. Studies of elemental pollution in the soil in the Klang industrial area were conducted to determine the concentration level in that area. Analysis of the content of elemental pollution in soil samples has used neutron activation analysis (NAA) techniques. The average concentration of major elements (Fe, Mg, Ti), heavy metals (As, Sb, Cr, Zn), uranium (U) and thorium (Th) in the soil of the Klang industrial area exceeded the average concentration in granitic igneous rocks. In comparison, the average concentration of rare earth elements (REEs) in soil samples in the study area is lower than the reference value of granitic igneous rocks. The elements of As, Zn and Cr showed a high concentration in the SL 11 area, where business activities, vehicle workshops and residential were located. The REEs show a high concentration in the SL 14 area compared to other sites. The geo-accumulation (Igeo) index was applied to identify the pollution status. The Igeo index for the elements of Mg and U can be categorised as unpolluted to moderately polluted. As and Sb can be categorised as unpolluted to moderately polluted, and as extremely polluted in the areas of SL 11 and SL 14. The element of Th can be categorised as unpolluted to moderately and strongly polluted. The Igeo index of REEs can be categorised as unpolluted in the soil of the Klang Industrial area.