Caesium-137

Caesium-137
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Name	Caesium-137
Mass number	137
Decay mode	Beta decay
Half life	30.17 years
Daughter	Barium-137m

Caesium-137 Caesium-137 is a radioactive isotope produced in nuclear fission processes associated with Manhattan Project, Chernobyl disaster, Three Mile Island accident, Fukushima Daiichi nuclear disaster, and Hanford Site operations; it has been central to discussions at International Atomic Energy Agency meetings, cited by United Nations Scientific Committee on the Effects of Atomic Radiation reports, and monitored by agencies such as the Environmental Protection Agency, Nuclear Regulatory Commission, World Health Organization, and European Commission.

Overview

Caesium-137 arises from fission in facilities and events including Oak Ridge National Laboratory, Sellafield, Kurchatov Institute, La Hague plant, Mayak Production Association releases, and atmospheric tests like those conducted by Nevada Test Site, Semipalatinsk Test Site, Bikini Atoll, Marshall Islands; it contributed to contamination mapped after Chernobyl disaster evacuations, influenced remediation at Pripyat (city), affected fisheries near Fukushima Daiichi nuclear disaster waters, and has been a focus in litigation involving Union Carbide-era claims and compensation schemes negotiated by bodies such as International Court of Justice-linked tribunals.

Nuclear Properties and Decay

The isotope decays by beta emission to an excited state of barium known as barium-137m, emitting gamma radiation characterized in standards maintained by National Institute of Standards and Technology, International Organization for Standardization, International Electrotechnical Commission, Bureau International des Poids et Mesures, and documented in databases used by laboratories at Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Argonne National Laboratory, Brookhaven National Laboratory; its half-life of about 30.17 years is used in decay calculations applied in protocols developed by American Nuclear Society, Health Physics Society, International Radiation Protection Association, Society for Radiological Protection, and in training at universities such as Massachusetts Institute of Technology, University of Cambridge, Imperial College London, Kyoto University.

Production and Sources

Primary production occurs in thermal neutron fission of Uranium-235, Plutonium-239, and Plutonium-241 in reactors including those at Davis-Besse Nuclear Power Station, Koeberg Nuclear Power Station, Kashiwazaki-Kariwa Nuclear Power Plant, Bruce Nuclear Generating Station and in weapons tests by states such as United States, Soviet Union, United Kingdom, France, China, India, Pakistan; reprocessing plants at Sellafield and La Hague concentrate isotopes, with waste managed under conventions like the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management and oversight by International Atomic Energy Agency.

Environmental Behavior and Radiological Impact

In terrestrial and aquatic environments Cs-137 binds to soil minerals and sediments, with mobility influenced by clay content, organic matter, and salinity studied by researchers at Woods Hole Oceanographic Institution, Scripps Institution of Oceanography, University of Tokyo, ETH Zurich; contamination mapping after Chernobyl disaster and Fukushima Daiichi nuclear disaster used remote sensing from satellites such as Landsat, Sentinel-2, Terra (satellite), and models developed by groups at European Centre for Medium-Range Weather Forecasts, Met Office, National Oceanic and Atmospheric Administration, and Japan Meteorological Agency to predict deposition and dose pathways evaluated against criteria from World Health Organization, International Commission on Radiological Protection, European Food Safety Authority, and national regulators like Food and Drug Administration.

Uses in Industry and Medicine

Caesium-137 has been employed in industrial radiography, teletherapy sources, and calibration standards, used historically in devices produced by companies such as Nordion (MDS Nordion), Amersham (GE Healthcare) legacy operations, and in moisture-density gauges deployed by firms like Troxler Electronic Laboratories; medical and research applications intersected with facilities at Johns Hopkins Hospital, Mayo Clinic, Memorial Sloan Kettering Cancer Center, Karolinska Institutet for dosimetry, while international standards bodies including International Atomic Energy Agency and International Organization for Standardization guided safe use and transport regulations enforced under instruments such as the International Maritime Dangerous Goods Code and agreements administered by International Civil Aviation Organization.

Safety, Regulation, and Decontamination

Regulatory frameworks addressing Cs-137 incidents involve agencies like Nuclear Regulatory Commission, Environmental Protection Agency, European Commission, Health Canada, Australian Radiation Protection and Nuclear Safety Agency and international guidance from International Atomic Energy Agency and World Health Organization; remediation techniques developed and deployed following events at Chernobyl disaster and Fukushima Daiichi nuclear disaster include soil removal, phytoremediation trials by teams at Rothamsted Research and Tokyo University of Agriculture and Technology, vitrification at facilities influenced by research at Oak Ridge National Laboratory, and electrokinetic and chemical stabilization methods validated in projects funded by European Commission framework programmes and coordinated by institutes such as Helmholtz Association, French Alternative Energies and Atomic Energy Commission, and National Institute for Environmental Studies (Japan). Category:Radioisotopes