Common Examples of Radioactive Isotopes and Their Applications

The term radioactive isotopes, also known as radioisotopes, refers to unstable forms of elements that emit radiation during their decay processes to achieve a more stable state. This article will explore some of the most common examples of radioactive isotopes, including their unique properties and applications in various fields such as medicine, industry, and research.

Natural Radioactive Isotopes

Among the naturally occurring radioactive isotopes, Carbon-14 (C-14), Uranium-238 (U-238), and Uranium-235 (U-235) are among the most prevalent and widely studied. Each isotope plays a significant role in scientific research and practical applications.

Carbon-14 (C-14)

Carbon-14 is utilized in radiocarbon dating to determine the age of organic materials. It has a half-life of approximately 5,730 years and decays to nitrogen by emitting beta particles. This isotope is present in the air, caused by cosmic rays, and its abundance in living organisms can be used to estimate the age of organic remains.

Uranium-238 (U-238) and Uranium-235 (U-235)

Uranium-238 is a common isotope used in nuclear power generation and dating geological formations. It has a half-life of about 4.47 billion years, while Uranium-235 is fissile and can sustain a nuclear chain reaction, making it essential in nuclear reactors and atomic bombs.

Man-Made and Naturally Occurring Radioactive Isotopes

Man-made radioactive isotopes, although numerous, are not covered in this article. Instead, we will focus on some commonly encountered naturally occurring isotopes in everyday life, such as Radon-222 (Rn-222), Cesium-137 (Cs-137), Cobalt-60 (Co-60), Iodine-131 (I-131), and Strontium-90 (Sr-90).

Radon-222 (Rn-222)

Radon-222 is a colorless, odorless gas that poses health risks due to its radioactivity. As a decay product of uranium, it is commonly found in homes, contributing to indoor air pollution and potential health hazards.

Cesium-137 (Cs-137)

Cesium-137 is employed in medical applications, particularly in cancer treatment, and in industrial gauges. Its half-life of about 30.17 years makes it a valuable tool in various diagnostic and therapeutic procedures.

Cobalt-60 (Co-60)

Cobalt-60 is used in radiation therapy for cancer treatment and as a source of gamma rays for sterilization purposes. Its high-energy gamma rays make it an effective tool in both medical and industrial settings.

Iodine-131 (I-131)

Iodine-131 is commonly used in medical diagnostics and treatment, particularly for thyroid conditions. Due to its half-life of about 8 days, it is often used in short-term medical applications.

Strontium-90 (Sr-90)

Strontium-90 is a byproduct of nuclear fission and has applications in radioisotope thermoelectric generators. While its use in medicine is limited due to its radioactivity, it is still an important isotope in certain industrial applications.

Terrestrial Naturally Occurring Radioactive Material (TNORM)

Terrestrial naturally occurring radioactive material (TNORM) consists of radioactive material that naturally emanates from the Earth’s crust and mantle. Notable isotopes include U-238, Thorium-232, Potassium-40 (K-40), and decay products thereof. These isotopes form part of characteristic decay chain series and have significant applications in medicine and research.

Uranium and Thorium Decay Chain

The uranium and thorium decay chains are particularly important due to their long-half lives. Radon-222 contributes significantly to natural radiation exposure, often reaching levels over 1,000 microsieverts (μSv) per year.

Potassium-40 (K-40)

Potassium-40 (K-40) has a long half-life of 1.25 billion years, making it a persistent and widespread isotope in the Earth’s crust. It beta decays mostly to calcium-40 and constitutes 0.012% of natural potassium. Potassium, the seventh most abundant element in the Earth’s crust, averages 850 Bq/kg and is found in many foodstuffs, including bananas. Humans have about 65 Bq/kg of K-40, contributing to a small degree of radiation exposure.

Cosmogenic Radioactive Material

Cosmogenic radioactive material forms as a result of interactions between certain gases in the Earth’s atmosphere and cosmic rays. At lower altitudes, cosmogenic radionuclides contribute more to dose than cosmic rays themselves. At higher altitudes, the dose due to both increases, leading to higher radiation exposure for mountain dwellers and frequent flyers.

Conclusion

The study of radioactive isotopes is crucial for understanding various natural processes and developing practical applications in medicine, industry, and research. By harnessing the unique properties of these isotopes, scientists and engineers can create innovative solutions to address a wide range of challenges.