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Gamma Spectrometry
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
In γ-spectrometry it is essential to depress unwanted detection of radiation particles coming from, for example, the presence of background radiation (such as 40K in construction material and organic structures, 222Rn daughters in air, 238U and 232Th daughters in ambient construction materials) or from incompletely registered events from cosmic radiation. Therefore, many detector systems need to be set up so that they are partly or completely shielded from these ambient radiation sources. Although many nuclear medicine applications involve the examination of substantially stronger γ-sources compared with, for example, environmental radioactivity – leading to the background radiation contribution being less important or even negligible – applications such as contamination controls and whole-body counting of staff members can still be considerably affected by the presence of ambient background radiation. Measurements of samples that are not intentionally radiolabelled or doped with radionuclides (such as swipe samples from working surfaces), must also be made in shielded environments. The background shield of the γ-spectrometer often consists of a lead-brick cave, where both source and detector are enclosed. Detection set-ups for such low-activity samples should also be done in a different locale than the one used for γ-spectrometry of radiochemical purity and other high-activity sources (> 1 MBq) in order to avoid so-called crosstalk and perturbation from the presence of radiolabelled substances.
Spatial distribution modeling of radiometric analysis and radiation dose estimations in drinking water and soil samples from Siirt city in Türkiye
Published in Human and Ecological Risk Assessment: An International Journal, 2023
Nevzat Damla, Ahmet Altun, Cafer Mert Yesilkanat, Halim Taskin, Ayhan Kara, Umit Isık
It is well known from previous studies that humans are subjected to radiation from many sources (Garba et al. 2019; Omeje et al. 2018: Alomari et al. 2019; Rani et al. 2021; Saleh et al. 2015; UNSCEAR 2000, Saleh et al. 2013). Some of these sources are natural radioactive materials and their decay products formed within the atmosphere and on Earth as well as the radionuclides produced for various applications. Background radiation could reach high values when the environment is contaminated by artificial activities, whose sources of radiation are medical, industrial sources and nuclear activities, and natural activities, which contain both cosmic radiation and environmental radioactivity. Deposit materials may come from the surface soil through processes, such as rock decomposition and soil formation. They can also seep into the groundwater system, pollute it, and give rise to contamination distant from the source (Mohammed and Mazunga 2013). This highlights the importance of environmental protection measures and how important it is to limit the human impact on our planet.
Predictability of a short-term emergency assessment system of the marine environmental radioactivity
Published in Journal of Nuclear Science and Technology, 2020
Hideyuki Kawamura, Yuki Kamidaira, Takuya Kobayashi
This study focuses on Cs-137, which is an important radionuclide for assessing the marine environmental radioactivity in a nuclear severe accident. SEA-GEARN accounts for the interactions among three radionuclide phases in the ocean: a dissolved phase in seawater, an adsorbed phase in large particulate matter, and an adsorbed phase in sea-bottom sediment [5]. In this study, it is assumed that Cs-137 only disperses as a dissolved phase in seawater because the majority of Cs-137 in the ocean remains as this phase. The Cs-137 oceanic dispersion is then calculated by considering the advection and diffusion processes that are caused by ocean currents and radiological decay with a half-life of approximately 30 years.