Hasil untuk "Radioactivity and radioactive substances"

Thales Zanin dos Santos de Oliveira, Cibele Bugno Zamboni, Bárbara Barroso Issa Cardozo et al.

Plastics are one of the most common and persistent pollutants in ocean waters and beaches worldwide, causing harmful effects on marine biota. The composition of these plastics mainly includes polyethylene (PE) and polystyrene (PS). The marine environment is impacted in various ways and, in extreme cases, diseases can emerge among seafood-consuming inhabitants due to contaminants (such as the toxic additives) in the plastic composition. Specifically, the objective of the present investigation is to analyze ions and metals in PE and PS samples exposed in the Jurujuba region (Baía de Guanabara, Rio de Janeiro, Brazil) for different periods using the Energy Dispersive X-Ray Fluorescence (EDXRF) analytical technique. This analysis will help identify toxic metals present in these polymer compositions as well as metals adsorbed on the plastic surface, contributing to defining measures to address this issue. Samples (in triplicate) were divided into three groups: I) Standard: sample available commercially; II) Control: sample exposed only to ultra-pure water, in the dark with a controlled temperature of 25 degrees Celsius; III) Exposed samples in Jurujuba (Baía de Guanabara). This study is part of a larger research project “Strengthening capacities in Marine and Coastal Environments using nuclear and isotopic techniques” (IAEA/ARCAL: RLA7025). These results emphases the toxicity of marine pollution and show that PE and PS polymers can act as carriers of pollutants between ecosystems.

Douglas Brandão Baroni, Sad Sandrini Borsoi, Yuri Sartore Almada Soares et al.

This study examines nuclear regulation in the United Kingdom, focusing on licensing processes for land facilities supporting nuclear-powered submarines. It highlights the importance of these submarines for defense and maritime security, along with the need for specialized infrastructure to operate them safely and effectively. The study analyzes the UK’s procedures and regulations for nuclear licensing, with emphasis on regulatory bodies such as the Office for Nuclear Regulation (ONR) and the Defence Nuclear Safety Regulator (DNSR). Results discuss the classification of nuclear facilities in the UK, including those dedicated to submarines and nuclear defense, as well as the applicable standards and guidelines for licensing these facilities. It is concluded that nuclear regulation in the UK is robust and transparent, providing a solid foundation for licensing facilities supporting nuclear-powered submarines. The adoption of these standards as a reference in Brazil could significantly contribute to establishing a solid and secure regulatory framework for such facilities.

Rodrigo Zanette, Liliane Basso Barichello, Claudio Zen Petersen

In this paper, a comparative analysis of numerical results of the neutron transport and diffusion theories for steady-state and transient multigroup problems is presented. The neutron transport equation is known as the one that best describes the behavior of the neutron population in a nuclear reactor. However, due to the difficulty of working with its complete form, other models are considered as approximations to this equation. One such approximation is the neutron diffusion equation, which uses the Fick's Law. It is well known, however, that the diffusion model may not work well under specific conditions. The objective of this work is to establish a quantitative comparison of numerical results obtained for the K dominant eigenvalue and for the scalar fluxes from the two theories and to analyze the influence of the model on the results.

B. J. P Jones, J. A. Formaggio

Superradiance emerges from collective spontaneous emission in optically pumped gases, and is characterized by photon emission enhancements of up to $\frac{1}{4}N^{2}$ in an $N$ atom system. The gain mechanism derives from correlations developed within the decay medium rather than from stimulated emission as in lasing, so analog of this process should be possible for fermionic final states. We introduce here the concept of superradiant neutrino emission from a radioactive Bose Einstein condensate, which can form the basis for a superradiant neutrino laser. A plausible experimental realization based on a condensate of electron-capture isotope $^{83}$Rb could exhibit effective radioactive decay rates accelerated from 86.2 days to minutes in viably sized rubidium condensates of $10^{6}$ atoms.

Yang Bai, Mrunal Korwar

Quark nuggets $^A_ZQ$, as Fermionic non-topological solitons, could have their mass per baryon smaller than ordinary nuclei and behave as exotic nuclei with different relations of atomic number and atomic mass number. Using both the degenerate Fermi gas model and the Friedberg-Lee shell model, we calculate the properties of quark nuggets made of up and down quarks. Similar to ordinary nuclei, quark nuggets could exhibit their own radioactivity, including gamma decay, beta decay, and (explosive) spontaneous fission, with the qualitative properties presented here. These quark nugget properties may provide guidance for searching for quark nuggets in situ from binary neutron star mergers.

A. Adel, Karim H. Mahmoud, Haitham A. Taha

We have conducted a comprehensive and systematic study of the proton radioactivity and $α$-decay half-lives of neutron-deficient nuclei. This investigation involved the utilization of various Proximity potentials and also considered the incorporation of thermal effects. For the half-life calculations, we employed both temperature-independent and temperature-dependent interaction potentials. We observed that proton radioactivity serves as the dominant mode of decay for nuclides situated very close to the proton drip-line. We explored a universal curve that examines the correlation between the decimal logarithm of experimental half-lives and the negative decimal logarithm of the penetrability for both proton radioactivity and $α$-decay.

S. Yu. Bazhin, E. N. Shleenkova, V. Yu. Bogatyreva et al.

Official data on radiation doses for flaw detectors do not take into account working conditions. In the reporting forms, there is no division between personnel performing flaw detection in stationary conditions and in situ, which roughly averages the values of effective doses towards underestimating the values for personnel working in site radiography. In this work, comparison of our own data on radiation doses of flaw detectors was performed. It has been shown that the difference in the mean and median values of effective doses reaches 10 times. When performing flaw detection in stationary conditions, the personnel are at a sufficient distance from the source of ionizing radiation and are well shielded by engineering protective equipment, so the exposure is fairly uniform. In such cases, one individual thermoluminescent dosimeter located at chest level is sufficient to estimate the effective dose. The average annual effective dose for personnel conducting flaw detection in stationary conditions is 0.87 mSv (median – 0.88 mSv, maximum value – 0.99 mSv). During individual radiation monitoring of personnel performing flaw detection in situ using portable roentgen flaw detectors, cases of neglect in the use of individual dosimeters were identified, which requires more stringent measures to comply with existing requirements for ensuring radiation safety and operating rules for individual dosimeters. The average annual effective dose for flaw detectors working with portable roentgen flaw detectors is 9.03 mSv (median – 8.85 mSv, maximum value – 12.37 mSv).

E. M. E. El Afifi, Muhammad S. Mansy, M. A. Hilal

Large amounts of TENORM waste (produced water, scale, and sludge) are created in oilfields around the world, presenting radiological risks to employees, the public, and the environment since activity concentrations of radioactive substances were above the exemption levels accredited by several authorities. Using the activity concentration of the radium-isotopes (226Ra and 228Ra) in the waste, we determined the 'fingerprint' as a radiochemical signature and some relevant 'radiological hazard parameters' in this review. The majority of the reported residues take the form of radio-contaminated (produced water, scale, and sludge) generated in Egypt's oilfields or elsewhere include radium isotope activity concentrations (226,228Ra) that exceed the international exemption limit. The activity concentrations of 226Ra(238U-series) in produced water, scale, and sludge waste were 0.04-1,480 Bq/L, 1.1-2,015,000 Bq/kg, and 1-120,800 Bq/kg, respectively, whereas 228Ra (232Th-series) was 0.34-250 Bq/L, 1.8-1,428,000 Bq/kg, and 10-122,830 Bq/kg, respectively. The radioactivities of radium isotopes were found to be above the exemption values recognized by WHO, IAEA, IOGP, EC, and ICRP in 95, 82, and 58% of produced water, scale, and sludge waste, respectively. The 226Ra(238U)/228Ra(232Th) ratio, from the other hand, was estimated to be utilised as a 'radiochemical fingerprint', or signature in the reported TENORM residues. The radium isotopes ratio in produced water, scale, and sludge waste in Egypt's oilfields is 0.41-4.45 (av. 1.98 ± 1.37, coefficient of variation, COV %: ∼69%), 0.2-21.4 (av. 4.3 ± 4.7, ∼109%), and 1.4-52.2 (av. 9.6 ± 15.3, ∼159%), respectively. For produced water, scale, and sludge waste, the 226Ra/228Ra ratios are 0.12-9.1 (av. 1.43 ± 1.72, ∼120%), 0.2-159 (av. 7.78 ± 23.5, ∼302%), and 0.8-223.5 (av. 14.1 ± 45.4, ∼322%) in global oilfields. The radiological hazard parameters (Ig, Ia, E◦, EG, and ELCR) owing to radium isotopes or 222Rn in most scale and sludge residues, as well as a small percentage of produced water, are all over the allowed safe limits. Substantial differences in the radium isotopes ratio in the reported waste can be attributed to thier geological, chemical, physical, and/or operational constraints. However, from the different perspectives of remediation and/or radiation protection programs, these values can be employed as a guidance for organizations investing in oil and gas production.

A. V. Titov, N. K. Shandala, Yu. S. Belskikh et al.

The article presents the results of a study of the current radiation situation at the uranium legacy site located in the territory of the Bambakai Valley (Transbaikal Territory), formed in the period from 1973 to 1989 due to the discharge of mine water. During the radiation survey, the method of pedestrian gamma survey was used to measure the ambient dose equivalent rate. Soil sampling was carried out to study the radionuclide specific activities in the soil. The activity of gamma-emitting radionuclides in the samples was measured with a stationary gamma spectrometer. The activities of 210Po and 210Pb were measured after their radiochemical extraction from samples. It was found that the values of ambient dose equivalent rate in the territory of the valley varied over the wide range from 0.1 to 1.4 µSv/h in the areas under manmade contamination. The estimated average value of the gamma background for this place is 0.14±0.02 µSv/h. The specific activities of 238U, 226Ra, 235U, 210Pb and 210Po in the surface 10-cm soil layer at the site are from 10-40 times higher than the background values. The most part of radionuclides in the soil is in the acid-soluble form. Effective doses of the workers involved in hay harvesting in the area of the fallow land do not exceed 1.5 µSv/year. Doses of terrestrial environmental media (grass, earthworms) are 100 and more times lower than the safe level of exposure to biota.

Kouji H. Harada, Sani Rachman Soleman, Jeremy Sea Meng Ang et al.

On 24 February 2022, Russian military forces invaded Ukraine. The fighting has already caused unimaginable conditions and millions of people were forced to flee their homes. For decades, conflicts have been linked to environmental pollution, exposure to radioactivity and heavy metals as well as infectious diseases. The invasion may cause specific environmental risks, like the release of radioactive substances from nuclear power plants and contaminated soils. Because international collaboration is one of the most effective ways to address environmental problems, it is critical to establish scientific bodies within a global framework to identify concrete actions and tangible measures to provide immediate assistance to citizens. This commentary discusses the above issues from lessons learned from the past wars and the way forward in the Russian invasion of Ukraine.

V. Yu. Golikov, A. V. Vodovatov

The aim of this study was to demonstrate how the severity of radiation damage in the case of bone marrow syndrome due to acute irradiation depends on the non-uniform irradiation of the body. We used the calculation method that involves the evaluation of organism mortality as a function of bone marrow cells colony survival vs dose for different radiation profiles. It was presumed that the probability of the death for the organism is the same for the same value of survival level of the bone marrow cells regardless of the dose distribution by mass of the organ. The dose of uniform irradiation that is equivalent to the dose for the L-th case of non-uniform irradiation is calculate based on the survival level of the total marrow cells. After that the probability of the death of the organism is estimated according to the dose response curve. Dose distribution in bone marrow of computational MIRD-5-type stylized model adult man for different geometries of exposure by point source of 137Cs was evaluated. Larger non-uniformity of the dose distribution in the bone marrow at the same dose in free air in the site of human location causes a greater probability of survival due to a greater proportion of bone marrow cells that have preserved the possibility of reproduction. The values of mean 50% lethal dose for cases of approximately uniform irradiation of the body surface (point source at a distance 10m) and sharply non-uniform irradiation (point source at a distance of 0.5 m) differ approximately by the factor of 1.7 – 2.5 depending on direction of irradiation. Additionally the values of conversion coefficients from the reading of an individual dosimeter to the value of an effective dose for various geometries of irradiation of emergency workers from the 137Cs point source were calculated. The average value of the conversion coefficient from personal dose to effective dose for the considered exposure situations is 0.7 Sv Cy-1 and the 90% confidence interval is 0.49 – 0.99 Sv Gy-1.

Diogo da Costa, Marcelino dos Anjos, Davi Oliveira et al.

Electronic devices are getting smaller each time and the technology, increasingly complex. Commonly found problems such as reflow soldering and open solder connections, which are mostly difficult to detect by conventional means like X-ray images or physical cut on the transverse section. Along with the challenge of finding these flaws, there are also some problems that may arise on the exposure of them using destructive analysis techniques, such as the fiscal transversal cut and chemical decapsulation. Both techniques may induce damage not relevant to where that flaw is located or remove evidence of a flaw or a damaged place. The high-resolution 3D x-ray computerized microtomography provides a powerful alternative solution and non-invasive to issues that involve the analysis of semiconductor devices. This research contemplates the study of semiconductor’s integrity (LED’s) based of X-ray computerized microtomography. The SkyScan 1272 Bruker commercial equipment was used for analysis of the P-N junction in a set with 10 LEDs, under non polarized conditions and upon electrical overstress effects on its contact terminals. The P-N junction had their dimensions analyzed on the three spatial directions (x, y and z) and studied on the effects that occur when a LED is damaged. The study methodology of integrity regarding computerized microtomography have shown consist outcomes that allowed the understanding of what occurs on the LED's structure and investigates matters that allows decisions to be made regarding its quality, and so, accomplishing the goals designated on this research.

Jun-Hao Cheng, Zhen Zhang, Xi-Jun Wu et al.

In the present work, we systematically study the proton radioactivity half-lives of 33 spherical nuclei based on the relationship between the Skyrme parameters and the macroscopic quantities of nuclear matter. Using the two-potential approach with the spherical Skyrme-Hartree-Fock model, the correlation between proton radioactivity half-life and macroscopic quantities was analyzed. Moreover, we obtained a new Skyrme parameter set by fitting the two most weighted macroscopic quantities. Compared with Skyrme parameters MSL0 and the theoretical model of proton radioactivity UDLP, the theoretical proton radioactivity half-life calculated by the new Skyrme parameter set can better reproduce the experimental data.

A. Malizia, A. Chierici, S. Biancotto et al.

Conventional and non-conventional emergencies are among the most important safety and security concerns of the new millennium. Nuclear power and research plants, high-energy particle accelerators, radioactive substances for industrial and medical uses are all considered credible sources of threats both in warfare and in terror scenarios. Estimates of potential radiation releases of radioactive contamination related to these threats are therefore essential in order to prepare and respond to such scenarios. The goal of this paper is to demonstrate that computational modeling codes to simulate transport of radioactivity are extremely valuable to assess expected radiation levels and to improve risk analysis during emergencies helping the emergency planner and the first responders in the first hours of an occurring emergency.

Bruna Saporito Teixeira, Gabriel de Souza Chierentin, Nelida Lucia del Mastro

The development of starch films containing natural antioxidants is one alternative of active packaging. Starch is a well-studied natural biopolymer that can be used for the development of biodegradable films because it presents a low cost, is easy to obtain and presents good ability to form films. Hibiscus sabdariffa, commonly known as hibiscus, roselle or red sorrel, is an annual herbaceous sub shrub that contains many types of biocompounds, including organic and phenolic acids. The aim of the present work was to determine the influence of electron beam irradiation on potato starch film containing hibiscus extract. The aqueous hibiscus solution was prepared by boiling for 3 min 1% w/ml dehydrated hibiscus flowers in 500 ml deionized water. The film forming solution was prepared by casting (5% potato starch, 3% glycerol as plasticizer and the hibiscus solution) and irradiated in a 1.5 MeV electron beam accelerator Dynamitron II (Radiation Dynamics Inc.), with doses of 0, 20, 40 and 60 kGy. After drying some mechanical properties were measured. The tensile strength of the control films and the irradiated ones was established. There were no significant differences among them. It looks like hibiscus antioxidants were able to prevent the expected starch radiation degradation process caused by radiation generated free radicals.

Noemi Aguiar Silva, Sonia Hatsue Tatumi, Alvaro de Farias Soares et al.

RESUMO Uma ametista é uma variedade geológica de quartzo (SiO2) e pode ser encontrada em abundância no Brasil. Sabe se o quartzo mostra uma luminescência intensa que é usada na remoção de sedimentos e é facilmente detectada na natureza, devido a essas características, foi escolhida para executar análises de termoluminescência (TL) e luminescência óptica estimulada (OSL) para avaliar suas personalizações. Uma caracterização morfológica foi realizada por meio da técnica de difração de raios X (DRX) e confirmou se uma amostra é um quartzo alfa puro.Os elementos totais e vestígios foram selecionados pela técnica de Fluorescência de Raios X de Reflexão Total (TXRF) e diversas impurezas foram encontradas como P (11148 mg / kg), S (27,1 mg / kg), K (10,35 mg / kg), Ca (47,84 mg / kg), Fe (13,69 mg / kg), Cu (2,383 mg / kg) e Zn (11,082 mg / kg), também algumas impurezas vestigiais, como Cr (0,746 mg / kg), O Mn (0,186 mg / kg) e o Ni (0,331 mg / kg) foram selecionados e podem ter papel importante na emissão luminescente. Uma amostra em pó foi irradiada com doses crescentes de beta beta, em um intervalo de 5 a 25 Gy e mostrou picos de TL a aproximadamente 110, 240 ° C. A resposta do OSL foi verificada com películas produzidas com ametista e teflon; como pelotas fornecer uma excelente resposta OSL.Os nossos resultados mostram que um ametista pode ser usado para osimetria OSL e TL.

Dragos Nichita, Dimiter Balabanski, Paul Constantin et al.

A very intense gamma beam of the Gamma Factory facility proposed at CERN can be used to generate radioactive ion beams (RIBs) with high production yields and study the structure of exotic neutron-rich nuclei. The radioactive nuclides are generated via photo-fission in several actinide targets and thermalized in high-purity cryogenic helium, filling a gas cell which is enclosing the targets. Electric fields are used to extract heavy ions and form RIBs which can be sent to various selection and measurement stations. Estimates for the production and extraction yields of exotic neutron-rich nuclei with such a setup are provided. A study of the impact of space charge, build-up inside the gas cell, on the extraction properties is presented and it is demonstrated that the beam needs to be chopped for achieving optimal extraction yields.

Tomasz Matulewicz

PET is an established medical diagnostic imaging method. Continuous improvements are aimed at refining image reconstruction, reducing the amount of radioactive tracer and combining with targeted therapy. TOF-PET provides the localization of the tracer through improved time resolution, nuclear physics may contribute to this goal via selection of radioactive nuclei emitting additional $γ$-rays. This additional radiation, when properly detected, localizes the decay of the tracer at the line of response determined by two detected 511 keV quanta. Selected candidates are presented. Some are particularly interesting, as they are strong candidates for theranostic applications.

Konstantinos Eleftheriadis, Alexandra Ioannidou

C. A. Bertulani, B. V. Carlson

Alternative methods to calculate neutron capture cross sections on radioactive nuclei are reported using the theory of Inclusive Non-Elastic Breakup (INEB) developed by Hussein and McVoy [1]. The statistical coupled-channels theory proposed in Ref. [2] is further extended in the realm of random matrices. The case of reactions with the projectile and the target being two-cluster nuclei is also analyzed and applications are made for scattering from a deuteron target [3]. An extension of the theory to a three-cluster projectile incident on a two-cluster target is also discussed. The theoretical developments described here should open new possibilities to obtain information on the neutron capture cross sections of radioactive nuclei using indirect methods.