Radionuclides in water *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Cesium-137 is an anthropogenic radionuclide, with a 30 year half-life, produced during nuclear fission (i.e., the splitting of a nucleus into at least two other nuclei) of various isotopes of uranium, plutonium, and thorium. Cesium-137 decays by β decay that is shortly followed by the emission of a γ ray from its short lived decay product, barium-137m (the “m” indicates it is a metastable nuclear isomer that decays very quickly). Two other isotopes of cesium, cesium-135 and cesium-134, are often considered less of a health concern because of their decay characteristics. For example, cesium-135, a β emitter, with a half-life of 2.3 million years has very low specific activity (i.e., number of decays per unit mass or volume). Cesium-134, a β emitter, has a half-life of 2.1 years so does not persist in the environment as long as cesium-137. However, determining cesium-137/cesium-134 ratios may help to identify the source and age of cesium in water.
Cervical Cancer
Pat Price, Karol Sikora in Treatment of Cancer, 2020
There is an ongoing debate about the optimal schedule for intrauterine brachytherapy.51 Low dose rate (LDR) systems with cesium-137 were radiobiologically ideal, as they allowed ongoing repair of radiation damage to normal tissues. However, these machines are no longer manufactured and are being replaced by high dose rate (HDR) systems delivering rates in excess of 1 Gy/min, and the most common radioactive source is iridium-192. The short treatment time allows more geometrical stability of the applicator during treatment and more rapid patient throughput, but there is considerably less time for repair of radiation damage. Therefore, such treatments are fractionated over several days, and the dose is adjusted for this difference in dose rate. Pulsed dose rate brachytherapy (PDR) uses an HDR source but delivers multiple small fractions over 2 days for a single insertion to reproduce LDR radiobiology.52 In order to be able to compare outcomes for these different dose rates and fractionation regimens, it is now standard to report 2 Gy equivalent (EQD2) total doses.
Tissue Preparation for Liquid Scintillation and Gamma Counting — the Counting Processes
Lelio G. Colombetti in Principles of Radiopharmacology, 2019
Each radionuclide decays with a distinctive gamma energy spectrum. Shown in Figure 18 is the energy spectrum of cesium-137, frequently used as a standard for gamma counters. It is a monoenergetic gamma emitter with a mean energy peak at 662 keV. In the energy range are shown Compton radiation and a back-scatter peak arising from escaped photons reflecting back with reduced energy from the surfaces (shielding) surrounding the detector. The high peak of low energy is the barium X-ray peak. The proportionate nature of the various energy conversion processes from the emission of the gamma photons, the nature of the photon absorption processes, to the production of an electrical pulse is such that the gamma-emitting radionuclide may be both identified and quantitated through an analysis of the energy spectrum. The efficiency of detection decreases with increasing photon energy. Photon detection decreases with increasing photon energy. Photon detection due to the photoelectric effect predominates at low photon energies (below 400 keV) and photon detection by Compton effect predominates at higher photon energies (around 1 MeV). Between these energies, both effects occur with about equal frequency. Photon detection by pair production is usually not as good, but the gamma annihilation energy can be detected. The crystal used in most gamma counters is designed to detect efficiently both the photoelectric and Compton effects.
A review of the impact on the ecosystem after ionizing irradiation: wildlife population
Published in International Journal of Radiation Biology, 2022
Georgetta Cannon, Juliann G. Kiang
Twenty-one years later after the Chernobyl power plant explosion, various isotopes of plutonium, strontium-90, americium-241, and cesium-137 were still detected at high levels causing adverse biological effects across the nearby areas (Voitsekhovych et al. 2007). Wildlife continued to be exposed to substantial radiation doses after humans were evacuated from these areas. The half-life of cesium-137 is approximately 30 years and it decays by β emission to a metastable isomer of barium-137. The half-life of barium-137 isomer is 2 minutes. Subsequently, the metastable isomer emits γ radiation and becomes ground state barium (Baum et al. 2002). Food or water contaminated with cesium-137 that are ingested lead to internal β and γ radiation doses in addition to external radiation doses. The half-life of cesium-134 is about 2 years. Cesium-134 emits β particles. The half-life of strontium-90 is approximately 29 years. Strontium-90 emits pure β radiation. Most of the plutonium isotopes emit α particles, which are ionizing and harmful, but have a short penetration distance. The half-life of plutonium-241 is approximately 14 years. It emits β radiation to become americium-241. The half-life of americium-241 is 432 years, and it emits α particles to become neptunium-237, with a by-product of γ emissions (Baum et al. 2002). This is the composition of radiation released and retained in the soil, water and air across the Chernobyl landscape. In addition to external radiation exposure, ingestion of contaminated food and water by wildlife occurred from the beginning of the disaster and continues to the present.
Consequences of a large-scale nuclear accident and guidelines for evacuation: a cost-effectiveness analysis
Published in International Journal of Radiation Biology, 2020
Moshe Yanovskiy, Ori Nissim Levi, Yair Y. Shaki, Yehoshua Socol
Radiation contamination decreases with time due to radioactive decay. In case of NPP accident, many radionuclides are released. The longest-living relevant radionuclide—cesium-137 (Cs-137)—has a half-life of 30 years; thus, its radioactivity decreases rather slowly: 50% of the initial level after 30 years, 25% of the initial level after 60 years and so on. However, many short-living isotopes are also released, so the initial radiation level decreases rather rapidly during the first year. There is also another mechanism of radiation rate decrease—the migration of radionuclides from the contaminated surface due to rain, wind, road traffic etc. The data for Chernobyl and Fukushima is fairly consistent (Balonov 2016; IRSN 2016; Zoriy et al. 2016; WNA 2018b) and shown in Figure 1. As a result, radiation dose absorbed in 10 years is only twice higher than the first-year dose, and the lifetime dose is approximately equal to three first-year doses (UNSCEAR 2013, p. 209). Although this fact is well known, it is not always considered in the radiation-protection context. One year after the accident and onwards the dose-rate R(t) can be approximately described by R(t) = R(0)/(1 + 0.75 × t) where t – time in years. This approximation is illustrated in Figure 1. Table 1 summarizes doses absorbed during different periods of time after the accident relative to the dose absorbed during the first 12 months.
Evaluation of sodium orthovanadate as a radioprotective agent under total-body irradiation and partial-body irradiation conditions in mice
Published in International Journal of Radiation Biology, 2021
Yuichi Nishiyama, Akinori Morita, Bing Wang, Takuma Sakai, Dwi Ramadhani, Hidetoshi Satoh, Kaoru Tanaka, Megumi Sasatani, Shintaro Ochi, Masahide Tominaga, Hitoshi Ikushima, Junji Ueno, Mitsuru Nenoi, Shin Aoki
Radiation GI death mostly occurs around day 10 of post-irradiation, and the day 10 has been widely accepted as a good end-point for acute GI syndrome in abdominally irradiated mice (Mason et al. 1989). Hematopoietic (Figure 3) and histological (Figures 1, 5, and 6) assays provided a clear evidence that our PBI technique using X-rays of maximum energy 150 keV induced lethal GI injury without causing severe HP syndrome in ICR mice, but some of them died later than the typical end-point (10 days) (Figure 2(A)). Although cesium-137 (137Cs) is a 662 keV gamma-ray source and has been standardly used for inducing radiation GI syndrome, our PBI model was constructed using an X-ray generator due to the laboratory equipment constraints. With almost the same PBI technique as using 137Cs, our previous study demonstrated GI death around 10 days of post-irradiation in ICR mice (Morita et al. 2018). The end-point may vary depending on various factors including photon energy (Poirier et al. 2020).
Related Knowledge Centers
- Beta Decay
- Caesium
- Chemical Compound
- Nuclear Fission
- Radioactive Decay
- Nuclear Fission Product
- Spontaneous Fission
- Nuclear Fallout
- Salt
- Half-Life