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The Atomic Nucleus
Published in Alan Cottrell, An Introduction to Metallurgy, 2019
Most radioactive changes lead to the emission of α-particles, β-particles (i.e. electrons, or positrons which are the positively charged anti-particles of electrons), and γ-rays (high-frequency electromagnetic waves). Typical α-particle emissions are P94239u→U92235+H24en+B510→L37i+H24e
Nuclear Energy Security
Published in Maria G. Burns, Managing Energy Security, 2019
Every atom comprises a nucleus, which in turn is made up of protons and neutrons. To generate nuclear energy a nuclear reaction is induced to change the number of protons and/or neutrons, and consequently change the nucleus of an atom. The energy launched by atomic nuclei reactions (also called radioactive processes) derives from nuclear fission or fusion. In nuclear fission a reaction or a radioactive decay process is induced in which an atomic nucleus is split in two to produce smaller nuclei. This process generates energy.In nuclear fusion a reaction is induced in which two atomic nuclei are united (fused) to produce a larger nucleus. Again, this process generates energy.
Nucleus and Radioactivity
Published in Franco Battaglia, Thomas F. George, Understanding Molecules, 2018
Franco Battaglia, Thomas F. George
Electromagnetic waves that are more energetic than visible light are classified as ionizing waves, whereas those less energetic than ultraviolet light are classified as non-ionizing waves. Health risks from exposure to radioactive materials is due mainly to the fact that the energy of emitted particles is much higher than the typical energies at play among the chemical bonds within the DNA molecules in the cells of our body, and may induce ionizing processes, i.e., electron emission and chemical bond alterations that can damage the cells up to the point of inducing cancer. The most dangerous ionizing radiation, due to its penetrating power, is indeed γ radiation, where a thick layer of lead is required for screening from such radiation. Other types of radiation become dangerous only if the emitters enter into the metabolic cycle.
Recent progress in radon-based monitoring as seismic and volcanic precursor: A critical review
Published in Critical Reviews in Environmental Science and Technology, 2020
Nury Morales-Simfors, Ramon A. Wyss, Jochen Bundschuh
Two types of analytical techniques have been developed for measuring radon activity in soil and water: (i) passive mode, in which radon enters to the device by natural diffusion and (ii) active mode, in which radon is pumped into a radon-detecting device. According to the measurement duration (time resolution), three types of sampling methods can be distinguished: (i) instantaneous or grab-sample technique (single-point samples collected over a short time frame), (ii) integrating technique (monthly or annual averages of radon concentrations) and (iii) continuous/active technique (accuracy time series concentrations) (Table 1). Radon measurement techniques are also classified based on three characteristics: (i) whether the technique measures radon or its daughter products, (ii) time resolution (i.e. accuracy and precision) and (iii) type of emission, either alpha, or beta particles or gamma radiation resulting from radioactive decay (Baskaran, 2016).
Natural radionuclides in electronic waste: an initial approach
Published in Environmental Technology, 2018
Arykerne Nascimento Casado da Silva, José Araújo dos Santos Júnior, Romilton dos Santos Amaral, José Wilson Vieira, Carlos Alberto Alves Barreto
The primordial radioisotopes exist in the Earth’s crust since the period of planet formation and almost all of them arise from of the three natural radioactive series known U-235, U-238, and Th-232. It is important to add K-40 due to its large occurrence of potassium in the soil. The radioactive emissions alpha, beta, and gamma occur from these elements and from their decayed products. The alpha emission has the characteristic of being more energetic than the other two, but it is heavier and has low penetrating power [7]. The raw material of the integrated circuits incorporates natural radioactive elements from soil and also trace amounts of artificial radioactive impurities from fallout, producing intermittent errors due to emission of alpha particles from elements such as 238U, 234U, 232Th, 190Pt, 144Nd, 152Gd, 148Sm, 187Re, 186Os, 174Hf, and 210Po [8,9].
Probabilistic analysis of groundwater and radionuclide transport model from near surface disposal facilities
Published in Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2018
K. Geetha Manjari, G. L. Sivakumar Babu
Radioactive wastes are one of the potential sources of radiation causing risk to the environment and also human health. The waste disposal facilities aim at isolation of these wastes from the environment. The design of a nuclear waste disposal facility depends mainly on the type of waste (non-hazardous/hazardous), its physical state (solid/liquid/gaseous) and the concentration of radioactivity (low-level waste (LLW)/intermediate-level waste (ILW)/high-level waste (HLW)) and they are generally constructed below the ground level. After proper conditioning and immobilisation of waste material, LLWs and ILWs are placed in the disposal modules called the Earth/Stone Lined trenches, RCC trenches, and Tile holes; and HLWs are disposed into deep geological repositories. As a part of the monitoring program, performance assessment models are also developed to predict the extent of safety achieved due to isolation of these wastes and estimate the amount of risk caused by the failure of these systems by taking into account various scenarios of release and pathways of intrusion. The major considerations in these models are the estimation of scales of safety temporally and spatially. It is imperative to consider uncertainty in the system in the form of inherent variability in the medium (soil properties/heterogeneity), measurement errors and modelling errors to estimate the potential impacts of radioactive disposal and also judge how probable it is that the radiation doses are exceeding the permissible limits. So as an integral part of performance assessment, the uncertainty propagation into the groundwater-radionuclide model, uncertainty quantification of the concentration and radiation dose, sensitivity analysis and reliability analysis are performed using the existing probabilistic methods.