Plutonium

Atomic Number: 94
Atomic Mass: 244

Introduction

Plutonium (chemical symbol Pu, atomic number 94) is one of the most famous—and infamous—elements in the world. Known for its role in nuclear power and weapons, plutonium has a long and complex history that spans from scientific discovery to global politics. It is a man-made element, created during nuclear reactions, and its radioactive properties make it both incredibly powerful and highly dangerous.

In this blog post, we will explore the discovery of plutonium, how it changed the course of history, and its modern-day uses, from generating energy to powering space missions.

The Discovery of Plutonium

Plutonium was discovered in 1940 by American scientists Glenn T. Seaborg, Edwin McMillan, Joseph Kennedy, and Arthur Wahl at the University of California, Berkeley. The discovery came during a period of intense research into nuclear physics, just before the United States entered World War II.

Here’s how it happened:

The scientists were bombarding uranium-238 with deuterons (a type of particle) in a cyclotron, a machine used to accelerate particles to high speeds. This created a new element, which they identified as plutonium-238.
Plutonium was named after the planet Pluto, continuing the tradition of naming elements after planets (uranium was named after Uranus, and neptunium after Neptune).

The discovery of plutonium would soon have major consequences for the world, as it became a critical component of the Manhattan Project, the United States’ secret effort to develop the first atomic bombs during World War II.

Properties of Plutonium

Plutonium is a heavy, silvery-gray metal that is highly radioactive. It has several isotopes, with plutonium-239 being the most important because of its ability to undergo nuclear fission. When plutonium atoms are split, they release a huge amount of energy, making it ideal for both nuclear power and nuclear weapons.

Here are some key properties of plutonium:

Radioactivity: Plutonium is highly radioactive, which means it gives off radiation as it decays. The radiation can be dangerous to living organisms, which is why plutonium must be handled with extreme care.
Fissile Material: Plutonium-239 is a fissile material, meaning it can sustain a nuclear chain reaction. This property makes it useful in nuclear reactors and bombs, where a small amount of plutonium can produce a massive explosion of energy.
Toxicity: In addition to its radioactivity, plutonium is highly toxic if ingested or inhaled. Even a tiny amount of plutonium dust can cause severe damage to internal organs.
Decay and Half-Life: The most common isotope, plutonium-239, has a half-life of 24,100 years, meaning it takes that long for half of the material to decay. This makes plutonium a long-term environmental hazard when used as nuclear waste.

The Role of Plutonium in History

Plutonium’s discovery had a profound impact on the world, particularly during the development of nuclear weapons in the 1940s.

1. The Manhattan Project and World War II

The discovery of plutonium was a key breakthrough in the Manhattan Project, the U.S. government’s secret program to build an atomic bomb during World War II. While the first atomic bomb dropped on Hiroshima in 1945 used uranium-235, the bomb dropped on Nagasaki, known as Fat Man, used plutonium-239.

The use of plutonium in atomic bombs marked a turning point in world history, as it demonstrated the devastating power of nuclear weapons. The bombings of Hiroshima and Nagasaki led to the end of World War II but also ushered in the nuclear arms race of the Cold War.

2. The Cold War and Nuclear Weapons

During the Cold War, both the United States and the Soviet Union stockpiled plutonium for use in nuclear weapons. Plutonium became a central element in the nuclear arms race, with both countries developing increasingly powerful bombs and delivery systems.

The sheer destructive power of plutonium-based nuclear weapons led to the establishment of international treaties and efforts to prevent the spread of nuclear materials. These include the Non-Proliferation Treaty (NPT) and arms control agreements that aim to reduce the number of nuclear weapons in the world.

Modern-Day Uses of Plutonium

Although plutonium is most famously associated with nuclear weapons, it has many other important uses, particularly in the field of nuclear energy and space exploration.

1. Nuclear Power

One of the key uses of plutonium today is in nuclear reactors that generate electricity. In nuclear power plants, plutonium-239 is used as a fuel in a process called nuclear fission, where plutonium atoms are split to release energy. This energy is then used to produce steam, which drives turbines to generate electricity.

Plutonium is often used in mixed oxide fuel (MOX), which is a blend of plutonium and uranium. MOX fuel helps make nuclear power plants more efficient by recycling plutonium that is produced as a byproduct of the fission process.

2. Space Exploration

Plutonium plays a vital role in space missions through its use in radioisotope thermoelectric generators (RTGs). RTGs convert the heat released by the radioactive decay of plutonium-238 into electricity, which powers spacecraft for long-duration missions.

Some of the most famous spacecraft powered by plutonium include NASA’s Voyager probes, which have been traveling through space since the 1970s, and the Curiosity and Perseverance rovers, which are currently exploring Mars. Without plutonium, these spacecraft would not have the reliable, long-lasting power needed to explore deep space or distant planets.

3. Nuclear Research and Medicine

Plutonium is also used in nuclear research, where scientists study its properties and behavior in nuclear reactions. This research is important for developing safer and more efficient nuclear reactors.

Additionally, plutonium-238 is used in some types of medical equipment to power devices like pacemakers, although this use has decreased in recent years due to the development of alternative technologies.

The Challenges of Using Plutonium

While plutonium has many important uses, it also presents significant challenges:

Nuclear Waste: One of the biggest challenges with plutonium is the radioactive waste it generates. Spent nuclear fuel from power plants contains plutonium, which remains radioactive for thousands of years. Safely storing and managing this waste is a major issue for the nuclear industry.
Nuclear Proliferation: Because plutonium can be used to make nuclear weapons, there is always a risk that it could be diverted for military purposes. International treaties and agreements work to prevent the spread of plutonium and other nuclear materials, but the risk of nuclear proliferation remains a global concern.
Environmental Impact: Accidents involving plutonium, such as the Chernobyl disaster in 1986 and the Fukushima disaster in 2011, have shown the devastating environmental impact of nuclear accidents. While these disasters did not primarily involve plutonium, the risk of contamination from plutonium remains a serious concern.

The Future of Plutonium

Looking ahead, plutonium will continue to be a key element in nuclear energy and space exploration, but its use must be carefully managed. Advances in nuclear technology, such as thorium reactors and fast breeder reactors, may help reduce the need for plutonium while offering safer and more sustainable ways to produce nuclear energy.

In addition, efforts to reduce nuclear weapons stockpiles and ensure the safe disposal of plutonium waste will remain crucial for global security and environmental protection.

Conclusion

Plutonium is an element that changed the course of history. From its role in the development of the first atomic bombs to its use in nuclear power and space exploration, plutonium has shaped the modern world in profound ways. While its potential for destruction is immense, plutonium also holds the promise of helping humanity achieve incredible technological advances, particularly in energy and space.

As we move forward, it is critical to balance the power of plutonium with the responsibility to use it safely and sustainably, ensuring that this powerful element benefits humanity without causing harm.

In the Living Periodic Table

In the element box, a sample of trinitite from the first plutonium bomb explosion. Trinitite is glass from the sand of the desert where the bomb exploded. And a radiation sample from a USSR 1980’s smoke detector that contains plutonium in a ceramic medium as the radiation source for an ionizing smoke detector. This is no longer used.