Chem Explorers

Powering the Future: Unleashing the Potential of Plutonium-238

Plutonium-238: A Comprehensive Guide to Understanding this Rare Element

Have you ever heard of plutonium-238? This rare radioactive element has many applications, from powering spacecraft to being used in pacemakers.

In this article, we will delve into the history of its discovery, its nuclear properties, and its uses in various fields.

Plutonium-238 Identification

To begin, let us start by identifying Plutonium-238. The CAS Registry Number for Plutonium-238 is 14137-23-4.

This number is used by scientists to identify specific substances among the millions that have been discovered. Plutonium-238 was first discovered in 1941 by Glenn Seaborg and his colleagues.

This element was created during the production of plutonium-239, which was being developed for the Manhattan Project. Plutonium-238 was found to be an alpha emitter, which means that it releases alpha particles, a type of radiation.

This discovery led to Plutonium-238 being used in various fields, such as in space exploration.

Plutonium-238 Nucleus

Now, let us dive into the nucleus of Plutonium-238. This element has 94 protons and 144 neutrons, giving it a symbol of Pu-238.

The protons are positively charged particles, while the neutrons are neutral particles. The number of protons determines the element’s identity, while the number of neutrons affects its stability.

Since the nucleus of Plutonium-238 is unstable, it undergoes radioactive decay. This process involves the release of particles and energy as the nucleus tries to reach a more stable state.

Plutonium-238 has a half-life of 87.7 years, which means that it takes that much time for half of the original amount to decay. This property makes it useful in certain applications, such as in spacecraft power sources.

Uses of Plutonium-238

One of the most significant applications of Plutonium-238 is in space exploration. It is used to power spacecraft that operate in environments where solar power is not feasible.

This element’s unique properties make it an excellent power source as it generates a lot of heat through radioactive decay. This heat is then converted into electricity, providing a reliable source of power for spacecraft.

Another application of Plutonium-238 is in medical devices. It is used in pacemakers, which are small devices that regulate the heartbeat of patients with heart problems.

Plutonium-238 is used to power these devices since it is a strong alpha emitter that can produce enough energy to operate the device for several years. This use of Plutonium-238 in medical devices has helped countless patients live a healthier life.

Plutonium-238 also has some applications in terrestrial power generation. It can be used to generate electricity in space constrained areas, such as small satellites.

Its high energy density and long half-life make it an excellent source of power for such applications.


In conclusion, Plutonium-238 is a rare radioactive element with unique properties that make it useful in various fields. Its identification number, 14137-23-4, helps scientists distinguish it from other elements.

Glenn Seaborg and his colleagues discovered Plutonium-238 during the development of plutonium-239 for the Manhattan Project. Its nucleus has 94 protons and 144 neutrons, making its symbol Pu-238.

Plutonium-238’s properties have made it a reliable power source for space exploration, medical devices, and terrestrial power generation. Its long half-life and high energy density make it a valuable source of energy for constrained areas.

Plutonium-238’s usefulness and versatility in different fields make it a fascinating element worthy of further research.

Plutonium-238 Production

Plutonium-238, also known as Pu-238, is a radioactive isotope of plutonium that has unique properties that make it highly valuable as a power source in space exploration and medical devices. It is produced by irradiating uranium-238 targets with neutrons in a nuclear reactor.

In this article, we will look at the different methods of Plutonium-238 production, as well as its isotopic separation.

Methods of Production

The most common way to produce Plutonium-238 is through the irradiation of uranium-238 targets in a nuclear reactor. Uranium-238 targets are usually in the form of pellets or wires and are placed in the reactor core.

The reactor core produces a high flux of neutrons that interact with the uranium-238, resulting in the creation of Plutonium-238 by neutron capture. Another method of Plutonium-238 production is through the bombardment of Californium-249 targets with alpha particles.

This method is known as the neutron-deficient synthesis route and results in the creation of various isotopes of plutonium, including Plutonium-238.

Isotopic Separation

Isotopic separation is the process of separating isotopes of an element, which is necessary for the production of highly purified Plutonium-238. The most common method of isotopic separation for Plutonium-238 is through electromagnetic separation.

Electromagnetic separation uses a strong magnetic field to separate the isotopes of plutonium based on their mass-to-charge ratio. A high-frequency alternating current is passed through a wire, creating a magnetic field that causes the heavier isotopes to bend more than the lighter ones.

This method results in highly purified samples of Plutonium-238 that can be used for various applications.

Plutonium-238 Properties

Physical Appearance

Plutonium-238 is a silver-white metal that tarnishes in air. It is relatively soft and ductile, which means it can be shaped into different forms without breaking.

It has a density of 19.8 g/cm, which makes it one of the densest elements. Due to its high radioactivity, it should only be handled with proper safety precautions.

Critical Mass and Diameter

The critical mass of Plutonium-238 is the smallest amount of the element needed to sustain a nuclear chain reaction. The critical mass of Pu-238 is much larger than the critical mass of plutonium-239, which is used in nuclear reactors and weapons.

The critical diameter of Plutonium-238 is also larger than that of plutonium-239, which means that it is less likely to undergo accidental criticality in normal operating conditions.

Decay Mode and Energy

Plutonium-238 undergoes alpha decay, which means that it emits alpha particles as it decays. An alpha particle is a helium nucleus consisting of two protons and two neutrons.

When Plutonium-238 undergoes alpha decay, it transforms into Uranium-234 and releases alpha particles with an energy of 5.593 MeV.

Branching Ratio and Daughter Nuclide

The branching ratio of Plutonium-238 is a measure of the probability that it will decay through a specific decay mode. Plutonium-238 has a 99.99% branching ratio for alpha decay, which means that almost all of its decay is through alpha particles.

The daughter nuclide of Plutonium-238 is Uranium-234, which is also a radioactive element. Uranium-234 undergoes further radioactive decay until it reaches a stable isotope.

Magnetic Dipole Moment and Spin Parity

The magnetic dipole moment of Plutonium-238 is a measure of its magnetic properties. It is a vector that points in the direction of the magnetic field that the element generates.

The magnetic dipole moment of Plutonium-238 is 0.64 N, which is relatively small compared to other elements. The spin parity of Plutonium-238 is the mathematical description of its intrinsic angular momentum.

The spin parity of Pu-238 is 0+, which means that it has positive parity and zero spin.

Binding Energy and Specific Activity

The binding energy of Plutonium-238 is a measure of the energy that holds its nucleus together. The binding energy of Pu-238 is relatively high, which contributes to its stability as a radioactive isotope.

The specific activity of Plutonium-238 is a measure of the radioactivity of a specific amount of the element. The specific activity of Pu-238 is 622 Ci/g, which means that a single gram of the element has a radioactivity of 622 curies.

In conclusion, Plutonium-238 is a valuable radioactive isotope that has unique properties that make it useful in various applications, such as in space exploration and medical devices. Its production method involves irradiating uranium-238 targets in a nuclear reactor and isotopic separation through electromagnetic separation.

Plutonium-238’s physical appearance, critical mass and diameter, decay mode and energy, branching ratio and daughter nuclide, magnetic dipole moment and spin parity, binding energy, and specific activity provide fascinating insights into the properties that make it such a valuable element in scientific research.

Plutonium-238 Half-Life

The half-life of Plutonium-238 is an essential and unique characteristic of this radioactive isotope. It is defined as the time it takes for half of the initial amount of Plutonium-238 to decay through radioactive decay.

In this article, we will cover the definition and calculation of Plutonium-238 half-life.

Definition and Calculation

Plutonium-238 has a half-life of 87.74 years. This means that if we start with a given amount of Plutonium-238, after 87.74 years, half of it will have decayed, and half will remain.

After another 87.74 years, half of what remained will have further decayed, leaving a quarter of the initial amount, and so on. The calculation of Plutonium-238 half-life involves the use of exponential decay.

This decay law can be expressed mathematically as:

N(t) = N e^(-t)

Where N(t) is the amount of Plutonium-238 remaining at time t, N is the initial amount of Plutonium-238, is the decay constant, and e is the natural logarithmic function. The Plutonium-238 half-life can be found by dividing the natural logarithm of 2 by the decay constant, .

Mathematically, this can be expressed as:

t_(1/2) = ln(2) /

For Plutonium-238, the decay constant is 7.88 x 10^-11 per second, which gives a half-life of 87.74 years when calculated using the above equation.

Plutonium-238 Radioactive Decay

Plutonium-238 undergoes radioactive decay, which is the process of its nucleus transforming into a more stable state by emitting high-energy particles or electromagnetic radiation. In this section, we will define the types of decay that Plutonium-238 undergoes, the decay equation, and the decay chain.

Definition and Types of Decay

Plutonium-238 undergoes alpha decay, which is a type of radioactive decay that involves the emission of alpha particles. An alpha particle is a helium nucleus consisting of two protons and two neutrons.

During alpha decay, Plutonium-238 releases an alpha particle, transforming into Uranium-234, a different isotope. This decay is described by the following equation:

^238_94Pu -> ^234_92U + ^4_2He

As seen in the equation, Plutonium-238 loses four units from the atomic mass, indicating the loss of two neutrons and two protons.

It also loses two units from the atomic number, indicating the loss of two protons. By losing protons, the element changes, transforming into a different isotope.

Decay Chain

The decay of Plutonium-238 leads to a decay chain that includes other radioactive isotopes. Plutonium-238 transforms into Uranium-234 through alpha decay.

Uranium-234 then undergoes further decay through alpha decay and beta decay, where it transforms into Thorium-230. This decays through alpha decay and beta decay again and eventually converts into stable Lead-206.

This series of decays is known as the Plutonium-238 decay chain. The full sequence of decays in the Plutonium-238 decay chain is as follows:

^238_94Pu -> ^234_92U + ^4_2He

^234_92U -> ^230_90Th + ^4_2He

^230_90Th -> ^226_88Ra + ^4_2He

^226_88Ra -> ^222_86Rn + ^4_2He

^222_86Rn -> ^218_84Po + ^4_2He

^218_84Po -> ^214_82Pb + ^4_2He

^214_82Pb -> ^210_80Hg + ^4_2He +

^210_80Hg -> ^206_82Pb + ^4_2He +

The Plutonium-238 decay chain provides a pathway by which radioactive materials decay and eventually become stable isotopes.

In conclusion, understanding Plutonium-238 decay and its half-life is crucial when researching this element’s behavior and applications. Plutonium-238 undergoes alpha decay, emitting an alpha particle to transform into Uranium-234, further decaying into Thorium-230, and eventually becoming Lead-206, following a decay chain.

The mathematical calculation of Plutonium-238 half-life is done by dividing the natural logarithm of 2 by its decay constant, and the isotope’s half-life is approximately 87.74 years.

Plutonium-238 Uses

Plutonium-238, with its unique properties and high energy output, has found significant applications in various fields. In this section, we will explore its uses in generating power through alpha particles and Radioisotope Thermoelectric Generators (RTGs), its role in powering space probes, and its important applications in medical research.

Alpha Particles and RTGs

Plutonium-238’s primary application lies in its alpha radiation, which consists of helium nuclei, or alpha particles. The high energy and penetrating nature of these particles make them highly valuable for power generation in devices like Radioisotope Thermoelectric Generators (RTGs).

RTGs convert the heat produced by the radioactive decay of Plutonium-238 into electricity. The alpha particles emitted by Plutonium-238 collide with the surrounding materials, generating heat.

Thermocouples within the RTG then convert this heat into electrical energy. RTGs are particularly useful in situations where solar power is not feasible, such as in deep space missions or in environments with limited or no sunlight, like certain planetary surfaces.

For example, the Mars rovers, Spirit, Opportunity, and Curiosity, were all powered by RTGs using Plutonium-238. These power sources provide a reliable and long-lasting energy supply, allowing spacecraft to operate for extended periods and explore distant regions of space.

Space Probes

The power generated by Plutonium-238, via RTGs, has been instrumental in powering numerous space probes and missions. These missions often require long durations and travel to distant regions of our solar system, where the intensity of sunlight diminishes significantly.

Without reliable power sources, these missions would be severely limited. The New Horizons mission, which provided our first detailed images of Pluto and its moons, relied on Plutonium-238 to power its instruments and data transmission systems.

The Voyager spacecraft, which have achieved historic milestones by exploring the outer reaches of our solar system, also used Plutonium-238-powered RTGs for their sustained operations over the course of several decades.

Medical Uses and Research

In addition to its applications in outer space, Plutonium-238 holds importance in medical research and treatments. While Plutonium-238 itself is not used directly in medical procedures due to its high radioactivity, its properties are utilized in the development of medical devices, particularly in radiation-based treatments.

One area of medical research involves utilizing the potential of alpha particle-emitting isotopes, similar to Plutonium-238, in alpha particle therapy. This form of targeted radiation therapy involves delivering high-energy alpha particles directly to cancer cells, maximizing their destructive potential while reducing damage to surrounding healthy tissues.

Moreover, Plutonium-238’s role as a power source in pacemakers has revolutionized cardiac care. By harnessing the energy produced by the alpha radiation of Plutonium-238, pacemakers can provide life-saving electrical stimulation to regulate a patient’s heartbeat for prolonged periods without the need for battery replacement.

Plutonium-238 Contamination and Health Risks

While Plutonium-238 has significant applications, it is important to acknowledge its potential health hazards due to its high radioactivity and alpha radiation emissions. Alpha radiation carries a unique set of dangers.

Though it does not penetrate deeply into materials and can be shielded by even a sheet of paper, when alpha emitters are inhaled or ingested, they release their energy directly into organs and tissues, increasing the risk of damage. Plutonium-238 can enter the body through inhalation or ingestion, targeting soft tissues and organs.

Its absorption in the body depends on various factors such as solubility, particle size, and chemical form. Once inhaled, Plutonium-238 can enter the bloodstream and distribute throughout the body.

Its continued alpha particle emissions can damage surrounding tissues, leading to long-term health risks, including cancer and other radiation-related diseases. Given the potential risks associated with Plutonium-238, strict safety protocols are essential for handling and storage.

Containment measures, protective clothing, and respiratory equipment are necessary precautions to minimize exposure and ensure the safety of workers involved in the production, handling, and disposal of Plutonium-238.

Importance in Space Research

The importance of Plutonium-238 in space research cannot be overstated. Its high energy output, long half-life, and ability to thrive in harsh space environments have made it a critical power source for numerous missions and probes.

Without Plutonium-238, many space exploration endeavors would be severely limited, unable to operate in regions with low sunlight or for extended durations. Furthermore, Plutonium-238’s reliability and longevity have been instrumental in ensuring the success and longevity of space missions.

By providing a long-lasting power supply, it enables spacecraft to continue collecting valuable data and conducting scientific observations over extended periods, contributing to our understanding of the cosmos and the exploration of distant worlds. In conclusion, Plutonium-238 has a wide range of uses and applications, spanning from power generation through alpha particles and RTGs, to powering space probes and enabling deep space exploration, and contributing to advances in medical research and treatments.

Nonetheless, the potential health risks associated with Plutonium-238 and its use require careful handling and precautions to ensure the safety of workers and the public. Despite these risks, the benefits and contributions of Plutonium-238 in powering space missions and advancing scientific research are significant and undeniable.

In conclusion, Plutonium-238 plays a crucial role in various fields, including space exploration, medical research, and power generation. Its alpha radiation and long-lasting energy output make it valuable for powering space probes through RTGs, enabling missions in distant regions with limited sunlight.

Plutonium-238’s applications in medical devices and research show promise in targeted therapies and cardiac care. However, its high radioactivity requires stringent safety measures.

Plutonium-238’s significance in powering space missions and advancing scientific endeavors cannot be overstated, highlighting its importance in expanding our knowledge of the universe and improving healthcare practices.



How is Plutonium-238 used in space exploration? Plutonium-238 is used to generate power through Radioisotope Thermoelectric Generators (RTGs) for space probes, enabling long-duration missions in environments with limited sunlight.

2. What are the medical applications of Plutonium-238?

Plutonium-238 is not used directly in medical procedures, but its properties are utilized in practices such as targeted radiation therapy and long-lasting power sources for devices like pacemakers. 3.

What are the health risks associated with Plutonium-238? Plutonium-238 poses health risks due to its high radioactivity and emission of alpha particles.

Inhalation or ingestion can lead to long-term damage to soft tissues and organs. 4.

How is Plutonium-238 safely handled? Strict safety protocols, including containment measures, protective clothing, and respiratory equipment, are necessary for handling and storage to minimize the risk of exposure.

5. Why is Plutonium-238 crucial for space missions?

Plutonium-238 provides reliable and long-lasting power, allowing spacecraft to operate in regions with limited sunlight and for extended durations, contributing to successful exploration and data collection. Final thought: Plutonium-238’s unique properties and applications have opened new doors in space exploration and medical research.

By harnessing its energy, we continue to make groundbreaking discoveries while pushing the boundaries of scientific knowledge.

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