Nukleonika Feed

Humanity's uranium-238 inventory: A significant and enduring gamma-radiation liability

Fri, 02 May 2025 00:00:00 GMT

Uranium-238 (U-238), accounting for 99.3% of naturally occurring uranium, primarily utilized for nuclear energy production, is also used in civilian and military applications, leading to vast, geographically dispersed stocks across different byproduct streams. While traditional risk assessments focus on chemical toxicity and alpha radiation, the gamma risks from the U-238 decay chain remain overlooked. Using dose-progression modeling and secular equilibrium analysis, this work quantifies the timeline and magnitude of U-238-induced gamma hazards from depleted uranium (DU), spent fuel (SF), and mill tailings. Findings show that gamma emissions from U-238 inventories exceed radiological safety thresholds well before secular equilibrium, necessitating revised risk assessments and improved, durable containment strategies. By highlighting this underexplored health and environmental issue in nuclear science, the study emphasizes the persistent challenge of managing Humanity's U-238 inventory, which represents a significant and enduring gamma liability across all timescales. Notably, only about 8% of this inventory is managed under robust long-term plans, while the remaining 92%, comprising DU and U-238 in mill tailings, remains inadequately prepared for the future. Addressing the gamma hazards of U-238's decay chain requires a paradigm shift in how this radionuclide is managed. Key priorities for action are identified.

Deuterium isotope effects in mechanistic studies of biotransformations of l-tyrosine and p-hydroxyphenylpyruvic acid catalyzed by the enzyme l-phenylalanine dehydrogenase

Fri, 02 May 2025 00:00:00 GMT

The mechanisms of the reversible oxidative deamination of l-tyrosine to p-hydroxyphenylpyruvic acid and reductive amination of phenylpyruvic acid to l-phenylalanine, both catalyzed by the enzyme l-phenylalanine dehydrogenase (PheDH, EC 1.4.1.20), were investigated using the kinetic isotope effect (KIE) and solvent isotope effect (SIE) methods. The values of deuterium kinetic effects in the 2-position of l-tyrosine and KIE in the (3S)-position of phenylpyruvic acid and solvent isotope effects for both reactions were determined using the non-competitive spectrophotometric method. Some mechanistic details of these biotransformations were discussed.

Effects of irradiating the beam dump with the main electron beam of the superconducting linear accelerator PolFEL

Fri, 02 May 2025 00:00:00 GMT

The transport of both primary and secondary radiation in the beam dump was conducted using Monte Carlo analysis. The radiation leakage level through the shielding walls of the bunker of the superconducting, linear electron accelerator PolFEL during beam operation, as well as the radiation dose generated by radioactivity, and the activity level of the beam dump and soil after beam operation were examined. The analysis encompassed three main electron beams with energies of 72 MeV, 187 MeV, and 280 MeV, corresponding to the need to deposit in the beam dump 900.0 W, 935.1 W, and 1400.1 W of electron beam power, respectively. It was determined that 99.86%, 99.83%, and 99.81% of the primary electron beam power was deposited in the designed beam dump. It was determined that the radiation leakage level through the lateral walls of the bunker, outside which nonexposed workers may stay, should be <1.8 · 10−4 μSv/h, 0.008(5) μSv/h, and 0.10(2) μSv/h, respectively. It was calculated that the radiation dose rate generated by radioactivity allows staying on the shielding plates above the beam dump no earlier than about a day after the end of the 30 days exposure period of the beam dump. The maximum activity level for the soil activity level at the most exposed location should be <0.008 Bq, 3.37(15) Bq, and 29.8(9) Bq for indicated above electron beam energies, respectively.

Monte-Carlo simulations of a neutron source based on a linear electron accelerator

Tue, 18 Feb 2025 00:00:00 GMT

Neutron beams are employed in a multitude of applications, including neutron activation analysis, neutron radiography and tomography, nuclear waste assays, reactor start-up sources, studies of material response, geological analysis, calibration standards and cancer therapy. The global demand for access to neutron beams is increasing, necessitating the development of relatively simple, efficient and easy-to-use neutron sources to address the more complex challenges of scientific research and industrial application. One relatively readily available method is to use a linear electron accelerator to produce beams of fast neutrons. The neutron generator, comprising of an electron linear accelerator and a tungsten X-ray converter, is capable of producing a maximum neutron flux of 1.53·1010 n/s to 1.45·1013 n/s at electron energies of 10–50 MeV, with an average electron beam current of 120 μA, corresponding to an intensity of 7.5·1014 e/s. The results of the neutron generator modelling conducted with the FLUKA Monte-Carlo code are presented in this article for an equivalent incident beam power of 1.2–6.0 kW. The optimal tungsten converter thickness is proposed as a means of achieving the maximum neutron flux in all directions.

Toward precision dosimetry: Harnessing the versatility of radiochromic films in radiation measurements

Tue, 18 Feb 2025 00:00:00 GMT

This paper presents the findings of a study on dose rate distribution in air and water phantoms, recorded using Gafchromic films. Low energy accelerator with X-ray tube (NALR), a system developed at the National Centre for Nuclear Research (NCBJ), generated by the dose rates. The primary objective of this research was to employ the X-ray tube as a source of X-ray radiation and assess dosimetry techniques using radiochromic films for radiological protection purposes. Gafchromic MD-55-V2 and EBT films were utilized for measurements. Two-dimensional measurements with Gafchromic dosimetry films were compared against ionization chambers AP 2.0 (in water) and PTW-23342 (in air) to validate radiation dose rate distributions. Furthermore, the film response over different days post-exposure highlights the importance of scanning radiochromic films on the first day after exposure.

Spectroscopic techniques in the investigation of extraordinary medieval Polish coins: Revealing the presence of hidden cores

Tue, 18 Feb 2025 00:00:00 GMT

Cross denars, frequently found in Polish hoards, were traditionally thought to be Ag coins with some Cu content. This study investigates the possibility of a hidden Cu core beneath the Ag or Ag–Cu surface of these coins. It raises questions about whether they were counterfeits or intentionally designed for mass production. Unlike Roman denarii, which revealed their cores when broken, the examination of cross denars without damage is challenging. Optical microscopy and microanalysis revealed differences in the composition of early medieval Polish coins, challenging the belief that cross denars were homogeneous Ag–Cu alloys. Detailed spectroscopic analyses, including energy-dispersive X-ray fluorescence (ED-XRF), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), micro X-ray fluorescence (μXRF), and microparticle-induced X-ray emission (μ-PIXE) measurements, were conducted. These analyses of two cross denars uncovered one composed of an Ag–Cu alloy and another manufactured by plating a Cu–Zn core with an Ag sheet. This suggests the need for further research in the history and technology of minting in Poland in the Early Middle Ages. It also prompts a reconsideration of the applicability of noninvasive X-ray techniques for archaeological examinations.

Application of improved matrix dilution method in quantitative analysis of Ni-Co-Mn ternary precursor

Wed, 20 Nov 2024 00:00:00 GMT

When using energy-dispersive X-ray fluorescence (EDXRF) to analyze Ni-Co-Mn (NCM) samples, if the standard sample's concentration greatly differs from the unknown sample's concentration, the traditional matrix dilution method requires repeated dilution and measurement. This makes the process time-consuming and labor-intensive. This study proposes an improved matrix dilution method to reduce sample preparation and analysis. This method first establishes a functional relationship model between the dilution factor and the characteristic X-ray intensity. Then the characteristic X-ray intensity of the analyzed element can be calculated by this model, avoiding unnecessary dilution and measurement steps. To verify the effectiveness of this method, the dilution factors and characteristic X-ray intensities of the test samples were fitted using the established functional relationship. The fitting results showed that the fitting coefficients of determination of the Mn, Co, and Ni were all 0.999. Quantitative analysis was performed on the characteristic X-ray intensity fitting values and measured values of the test samples. The results showed that the quantitative results of the two were consistent. The average error of the three elements for both methods was 1.1% and 0.7%, respectively. It shows that through the established functional relationship, the characteristic X-ray intensity can be effectively calculated by the dilution factor. This method can be applied to samples with identical elements and proportions of target elements, but with different concentrations, using the same set of standard samples.

New chamber stapes prosthesis: Effect of ionizing radiation on material and functional properties

Wed, 20 Nov 2024 00:00:00 GMT

New chamber stapes prosthesis (ChSP) is a middle-ear prosthesis intended for use in ear surgery for restoring the patient's middle ear function. As the prosthesis is an implantable medical device, it must be sterilized before use. However, possible alterations in the material and the functional properties following the sterilization process can influence the safety aspects while using the prosthesis. The purpose of this paper was to determine the effects of ionizing radiation (IR) on the physicochemical and biological properties of the new chamber prosthesis by utilizing EPR spectroscopy, mechanical testing, and cytotoxicity studies. Our research shows that the radiation treatment increases the hardness and the elastic modulus of the polymer, decreases the stiffness of the prosthesis membrane, and does not cause chemical changes in the polymers that may result in cytotoxicity. Furthermore, new ChSPs were successfully tested in preclinical in vitro tests. The test results justify the undertaking of further work, including in vivo biocompatibility tests and clinical trials, which would eventually lead to the increased use of the prosthesis in clinical practice.

Hall probe calibration in high-precision magnetic field mapping system of superconducting cyclotron

Wed, 20 Nov 2024 00:00:00 GMT

IntroductionSuperconducting cyclotron can generate high-energy proton beams and are mainly used for radiation therapy of tumors and cancers. In the superconducting cyclotron SC200, the maximum magnetic induction intensity can typically reach up to 4.6 T, and the magnetic field accuracy is 1e-4. Hall probes are commonly used tools for measuring high-intensity magnetic fields. ObjectiveThrough comprehensive consideration, this study selects the SENIS Low-Noise Teslameter 3MH5 and Hall probe C to measure the magnetic field. When the magnetic field exceeds the range of 2 T, the measurement accuracy of the Hall probe is less than 1e-4, and the Hall probe needs to be calibrated to improve its measurement accuracy. MethodsThe Hall probes are calibrated using Swiss METROLAB PT2025 nuclear magnetic resonance (NMR) Tesla instrument and 1062 probe. Based on the calibration principle, a calibration system platform was built, test data were collected, and calibration curves were obtained. At the same time, the calibration data were analyzed through cross-validation experiments using the cubic polynomial fitting method. ResultsThe results indicate that the test deviation range is from −0.1 g to 0.1 g, and the measurement accuracy can reach 1e-4. ConclusionIn summary, the Hall probe can accurately measure the magnetic field distribution of the superconducting cyclotron. It can provide accurate and important data for the calculation and analysis of particle beam dynamics.

Beyond one million years: The intrinsic radiation hazard of high-level nuclear wastes

Wed, 20 Nov 2024 00:00:00 GMT

This paper highlights the absence of quantitative estimates regarding the intrinsic radiation hazard of high-level nuclear wastes, namely, spent fuel (SF) and vitrified high-level wastes (VHLW), for periods exceeding one million years. Using available data, conducting scoping calculations of radiation doses, and comparing the results to radiation protection guidelines and natural background radiation, this paper shows that high-level wastes cannot be safely handled or left unprotected essentially indefinitely. By quantitatively evaluating the dose rates of unshielded SF and VHLW, this study identifies critical new insights, such as the roles of the Np-237 decay chain; the eventual, long-term dominance of the U-238 decay chain; and the interplay of three actinide decay chains, including the significant role of Bi-214. These findings fill a gap in the literature and emphasize the need for more detailed investigations in this as-yet-unexplored research area, which has a direct bearing on technical and societal decision-making for both waste disposal safety and the choice of the back end of the nuclear fuel cycle.

Electron source model responsible for low power beam losses of 1 W/m along the entire PolFEL superconducting electron linear accelerator

Wed, 20 Nov 2024 00:00:00 GMT

The National Centre for Nuclear Research is planning to build a facility based on a free-electron laser (FEL) photon source. It is the first center to build this kind of facility in Eastern Europe. The laser radiation source relies on a superconducting linear electron accelerator. Ultimately, electrons are to be accelerated to energies of 72 MeV, 187 MeV and 280 MeV. To safely operate such kind of accelerator, the design of a shielding bunker is required, capable of attenuating the secondary radiation generated by electrons lost from the beam. This paper proposes a model for the energy and spatial distribution of such electrons. The proposed model will be used in subsequent calculations of the distribution of secondary radiation emitted by both the beamline and some devices essential for the operation of the PolFEL accelerator, such as superconducting niobium accelerating cavities, titanium liquid helium tanks filled with liquid helium, surrounded by μ-metal steel cryomodules containing a steel tube filled with liquid nitrogen, mirrors reflecting the resulting laser beams based on copper blocks, and electron beam deflecting electromagnets made of iron and copper. It was calculated that to reproduce a complex beam loss of 1 W/m, the total lost electron flux as a source of secondary radiation should be 1.7991 × 1013 e/s for 72 MeV, 1.1537 × 1013 e/s for 187 MeV and 1.1012 × 1013 e/s for 280 MeV. Preliminary Monte Carlo calculations of the designed source were performed, obtaining the energy and spatial distributions of the lost electrons.

Determination of uranium concentration in blood samples of women with breast cancer in Babylon Province of Iraq using CR-39 nuclear track detector

Sat, 29 Jun 2024 00:00:00 GMT

The incidence and prevalence of breast cancer in Iraq are alarming. Breast cancer is one of the most common cancers among Iraqi women, and its rates have been steadily increasing over the years. The exact reasons for the high incidence are not yet fully understood, but it is believed to be influenced by a combination of genetic, environmental, and lifestyle factors. The research objectives of this study revolve around two main goals. Firstly, the study aims to establish baseline values for the amount of uranium present in blood samples. Secondly, the study aims to assess the potential relationship between uranium levels in blood and the development of cancer. The investigation includes 16 blood samples from women diagnosed with breast cancer and 20 blood samples from women without breast cancer. The nuclear fission track analysis method using CR-39 solid-state nuclear track detectors will be employed to analyze the uranium contents in women’s cancer blood (CB) samples. The methodology adopted for this study involved utilizing the SPSS program to conduct a comprehensive statistical analysis. The results of the study indicate that there is a variation in uranium concentration among both the patient women and healthy women. The uranium concentration among patient women ranged from 3.259 ppb to 1.918 ppb, while among healthy women, it varied from 2.105 ppb to 0.59 ppb. These findings suggest that there may be a correlation between the presence of certain health issues and higher uranium levels.

Detection of low-dose irradiation of dry fruits by termoluminescence

Sat, 29 Jun 2024 00:00:00 GMT

The aim of the study was to investigate whether it is possible to detect low-dose irradiation in dried fruits using the thermoluminescence (TL) method. Selected dried fruits: strawberries, cherries, black currants, two types of raisins, mulberries, apricots, figs, dates and plums were irradiated with doses of 0.1 kGy, 0.3 kGy and 0.5 kGy.

Virtual radioactive source system for exercises modeling high doses

Sat, 29 Jun 2024 00:00:00 GMT

This article presents the possibilities of working in a virtual high-dose rate field following a procedure developed at the Nuclear Security Department of the Centre for Energy Research (EK NSD) in Budapest. Real-life simulation of a radiation survey and a radiation risk assessment as well as searching for lost radioactive sources, monitoring surface contamination (SC), in addition to localizing and overseeing materials out of regulatory control (e.g., at a radiological crime scene) are only possible under inactive conditions or in low-dose rate environments in accordance with the as low as resonably achievable (ALARA) principle. A virtual radioactive source system (VRSS) developed at the Nuclear Security Department (NSD) makes it possible to simulate “measured” values very accurately, even in a high-dose rate environment, but without exposing trainees to radiation hazards.

A study on “position-energy” response correction method based on monolithic crystal coupled SiPM array

Sat, 29 Jun 2024 00:00:00 GMT

The intrinsic characteristics of the monolithic crystal detector are spatially inconsistent, which leads to the position dependence of the detector on the energy response of the γ-ray as well as the peak shift of the response spectrum of the detector, that is, the “position-energy” shift. The “position-energy” shift will cause the energy resolution of the detector to deteriorate and affect the energy linearity of the detector. Thus, a crucial challenge in enhancing the position consistency of detector energy response, improving energy resolution, and ensuring accurate isotope identification is the reduction or elimination of this “position-energy” offset. The “position-energy” response correction method is proposed in this paper to improve the position consistency of detector energy response. Firstly, Monte Carlo simulation is used to model monolithic LaBr3(Ce) crystal detectors of different sizes. Secondly, the effective detection region of the detector model is evenly divided into 25 blocks, then the spectral peak position of each incident region is extracted, and the spectral peak correction function matrix of 25 incident regions and the center position is established. Finally, 25 incident regional peaks are modified according to the modified function matrix, so that the spectral peaks in each region are consistent with the peaks in the center, and the modified spectral responses of the detector are obtained. The simulation results show that this method can effectively solve the “position-energy” migration problem of monolithic crystal detectors of different sizes and improve the peak consistency of each detector region. The energy resolution of the 662 keV characteristic peak of the Cs-137 point source can be improved from 4.5% to 3.9%, and the linear deviation of energy can be reduced from 2.1% to 1.2%.

The influence of method precision on assessing radiological hazards for patients using radium water in balneotherapy

Tue, 25 Jun 2024 00:00:00 GMT

The influence of uncertainty on the method adopted for the determination of radioactive radium concentration in water was analyzed due to the assessment of the radiation hazards of balneotherapy. For the calculation, we considered the influence of the bath in radioactive water containing only 226Ra. 226Ra concentration was determined with two γ-spectrometers armed with HPGe detectors with different relative efficiencies. Both spectrometers were energy-efficiency calibrated with a calibration source and based on numerical simulations. Different methods for qualitative γ-spectrum analysis were adopted. The emanation method and the liquid scintillation method were also used. The uncertainty of humans hazard assessment linearly depends on the adopted radiometric method precision. For effective dose calculation, two models were adopted: the model of external exposure proposed by ICRP Publication 144 and the Reference Men model proposed by ICRP Publication 23, respectively.

Influence of the type of fuel used on the content of gamma radionuclides in the soot from the smoke ducts of the home furnaces

Tue, 25 Jun 2024 00:00:00 GMT

This paper presents the results of the measurements of gamma radioactive isotopes in soot samples from 15 different chimneys of household furnaces fired with various types of solid fuel. Soot samples were collected by the chimney sweep during the mandatory periodic cleaning of the chimneys. The γ-spectrometry technique using the high-purity germanium (HPGe) detector was employed for radiometry of the above-mentioned soot. It was found that the determined activity of gamma isotopes in soot is at a level similar to that in fly ash from power plants around the world. Artificial 137Cs was detected only in the soot from the combustion of biofuel or mixed fuel. The results obtained were chemometrically analyzed to find the relationship between the fuel used and the gamma isotope content in the soot. The analysis of 137Cs, 40K, 228Th, and 226Ra is sufficient to differentiate between the soot obtained and tested, and it varied with the fuel type burned (fossil fuels/biofuels).

Degradation of hydroxychloroquine in aqueous solutions under electron beam treatment

Tue, 25 Jun 2024 00:00:00 GMT

Hydroxychloroquine (HCQ), a 4-amino quinoline derivative, has antimalarial and anti-inflammatory activity and was most recently proposed in the treatment of SARS-COVID-19. Its pharmacokinetics and toxic side effects necessitate the monitoring of its presence in the environment and its removal from wastewater. In this study, HCQ was removed from an aqueous solution with a removal efficiency of between 80% and 90% under electron beam (EB) irradiation. The degradation of HCQ was propagated by reactions involving both the hydroxyl radical and aqueous electron. The degradation was observed to follow a pseudo-first-order kinetic reaction. The applied radiation dose, pH, and initial HCQ concentration were influential in the degradation efficiency under EB irradiation. Acidic and alkaline pH favored the removal of HCQ under EB irradiation. Even though the initial HCQ was successfully degraded, it was not completely mineralized. The TOC and chemical oxygen demand (COD) remained at a relatively stable level following EB irradiation of the aqueous solutions. This is attributed to the formation of other organic compounds that were not degraded under the investigated experimental conditions.

Radiation-induced cross-linking polymerization: Recent developments for coating and composite applications

Tue, 25 Jun 2024 00:00:00 GMT

Radiation-initiated cross-linking polymerization of multifunctional monomers is an attractive method used for drying solvent-free liquid coatings, inks, and adhesive as well as for fabricating high-performance composite materials. The method offers a number of advantages compared with thermal curing processes. Free radical and cationic polymerization have been investigated in detail over the past years. A high degree of control over curing kinetics and material properties can be exerted by adjusting the composition of matrix precursors and/or by acting on the process parameters (overall dose, dose rate, dose increment, initial temperature). Several pending issues that require deeper investigations are as follows: (i) the fast polymerization of multifunctional monomers generates micro-heterogeneous networks requiring detailed characterization and quantification by microscopic, thermal, and spectroscopic analyses; (ii) the adhesion and surface properties of radiation-cured coatings are quite sensitive to processing parameters; and (iii) significant enhancement of the toughness is needed to qualify potential matrices based on simple difunctional monomers for high-performance composites. Recent results show that the bulk and surface properties of radiation-cured materials can be improved by advanced formulation of matrix precursors and by a parametric study of the processing factors.

Conversion of fast neutrons for neutron radiography with TPX2 detector

Tue, 25 Jun 2024 00:00:00 GMT

The Timepix2-based hybrid-pixel detector with a 500 μm thick silicon sensor was employed for fast-neutrons registration to be applied in neutron radiography of metallic printed circuit heat exchanger (PCHE). Two energies of neutrons were experimentally tested. The detection of 3.55 MeV neutrons from the deuteron–deuteron (DD) reaction was compared to 15.7 MeV neutrons from the deuteron–tritium (DT) neutron generator. In order to distinguish the signal induced by the registered neutrons from the accelerator background, filtration of the recorded particle spectral tracks was applied. The benefit of applying hydrogen-based converter layer for 3.55 MeV neutrons was observable. On the other hand, in the case of 15.7 MeV neutrons, the direct registration by interaction with the sensor Si significantly dominates the conversion.