Spent nuclear fuel pool

Plutonium: uses of its isotopes and properties

Plutonium: uses of its isotopes and properties

Plutonium is a chemical element that is used as a nuclear fuel in the manufacture of nuclear weapons. Although traces can be found in nature, all plutonium isotopes are of artificial origin.

The first time that significant amounts of plutonium were produced was during World War II within the Manhattan Project. The purpose of this project was to manufacture enough material to use nuclear energy to develop a nuclear bomb.

Plutonium on the periodic table

Plutonium (with the symbol Pu) is element 93 of the periodic table, that is, its atomic number is 94.

It is a chemical element that belongs to the series of actinide elements. Plutonium has 16 isotopes, all of them radioactive. Physically, plutonium is a silvery metal and has 5 different crystal structures.

Chemically it is a very active material that can form compounds with all non-metallic elements, except noble gases. Metal dissolves in acids and reacts with water, although moderately compared to acids.

Atomic mass

244 u

Ordinary state



19816 kg / m3

Melting point

912.5 K (639 ° C)

Boiling point

3505 K (3232 ° C)

Plutonium-239 and other isotopes

Plutonium-239 is a fissile isotope of plutonium that is composed of 145 protons and 54 neutrons. It is the isotope that is used mainly for the manufacture of nuclear weapons but it is also used as a nuclear fuel in power reactors and in research projects.

Another important isotope is plutonium-238 which is used in heat sources for space applications, thermoelectric heat generators and has been used in cardiac pacemakers.

Where is plutonium obtained from?

Plutonium is made by burning nuclear fuel in conventional nuclear reactors. The irradiated fuel from nuclear reactors consists mainly of uranium (with a percentage of approximately 96%) and plutonium (with a percentage somewhat less than 1%).

Spent fuel can be managed in two different ways in the long term:

  • Open cycle management. In the open cycle, spent fuel is considered a highly active radioactive waste from the moment it is discharged from the reactor and is permanently stored.

  • Closed loop management. The closed cycle consists of subjecting the spent fuel to a mechanical-chemical process, known as reprocessing or reprocessing, which allows the uranium and plutonium that still contain fission and transuranic products to be separated. The recovered uranium and plutonium are used to make new fuel.

Uses of plutonium, what is it for?

The main uses of plutonium are as follows:

  • Nuclear fuel for nuclear power plants.

  • Thermoelectric Radiosiope Generators . A thermoelectric generator is a device that converts heat into electricity. This large-scale technology is impractical but useful in certain applications such as artificial pacemakers, space probes, and spacecraft. Plutonium-238 is used in this application because the radiation it emits does not pose a threat to human health.

  • Manufacture of atomic bombs. The isotope used for this purpose is plutonium-239. It is used because it will undergo nuclear fission. Very few isotopes will undergo nuclear fission.

Management of recovered plutonium in nuclear reactors

As plutonium is generated inside the fuel of nuclear reactors, it also fission, helping uranium to produce energy.

Between 7 and 8 kilograms per ton of unburned plutonium remain in spent fuel. This plutonium, recovered in reprocessing, can be used to replace uranium-235 in nuclear fuel, making pellets of mixed uranium oxide and plutonium oxide (MOX fuel).

MOX fuel can replace enriched uranium fuel in light water nuclear reactors.

Health Effects of Plutonium

Plutonium is a toxic and radioactive chemical element. The main type of radiation it emits is alpha radiation that cannot pass through the skin.

The danger of plutonium is given by its radiotoxicity. Ingested or inhaled alpha particles can be the cause of lung cancer or other types of cancer. In large quantities, they can be the cause of acute radiation poisoning or even death.

Once plutonium has entered the body, it remains for a long time.

The probability that people are exposed to plutonium is very low. If this happens, it is usually due to your manipulation.

Publication Date: April 14, 2014
Last Revision: November 15, 2021