Is Americium Flammable? (A comprehensive overview)

Is Americium Flammable?

Americium is not considered flammable. Americium is a solid at normal conditions, it melts at 2600 ºC. This element is a radioactive lanthanide with atomic number of 95 and chemical symbol Am. It is found in nature only in trace amounts in uranium ores. 

Americium is produced when plutonium (Pu) or uranium (U) are hit by neutrons by nuclear fission. It was discovered by the group of Glenn T. Seaborg in 1994 in the University of Chicago during the Manhattan project.

Americium fire hazards are not very well known in comparison to more common metals. It is known that solid americium does not catch on fire when heated to very high temperatures of up to 2000 ºC.

The most common americium isotope is the 241Am and the 243Am both of which are radioactive (half-life and specific activity listed in the table below).

Chemical symbolAm
Natural occurrenceOnly in trace amounts in uranium minerals
Main isotopes241Am and 243Am
Half-life of 241Am432 years
Half-life of 243Am7370 years
Specific activity of 241Am3.4 Ci/g
Specific activity of 243Am0.2 Ci/g
Melting point at 1 atm1176 ºC
Boiling point at 1 atm2600 ºC
Density at 20 ºC13.67 g/cm3
Main UsesIonization-type smoke detector.
AppearanceWhyte silvery solid.
SolubilityAcidic aqueous solutions. Insoluble in water.
Known substancesAmO2, Am2O3, AmCl3
Other propertiesDuctile, malleable, non-magnetic.
Unknown dataVapor pressure, flash point, autoignition temperature.

Americium Fire Hazards

In theory, americium can only cause fires unders very specific conditions. For instance if americium is in very finely divided particles (the smaller the particles the higher the surface area that can react with an oxidizing agent) it could be oxidized at a very fast rate, producing heat at a fast rate.

Americium powder is pretty much unknown though given its scarce abundance on Earth.

Can Americium Radioactivity Cause Fires?

Radioactive materials are capable of causing fires, by emitting high energy particles through decay. These high energy particles are capable of causing ionization of other elements leading to releases of high amounts of energy.

241Am and 243Am radiate alpha particles (also called alpha radiation) and decay into neptunium 237 ( 237Np) and neptunium 239 (239Np), respectively. Neptunium is also radioactive, so isotopes of this element also release radiation and change into isotopes of other elements.

Such processes release energy, this energy can increase the temperature of earby materials. For this heat to be enough to lead to burning of a nearby combustible material, a huge amount of americium would need to be releasing radiation in a concentrated location.

This process of radiation and decay of americium continues until bismuth is formed, this latter element is nor radioactive.

Americium Health Hazards

Many different factors determine how much harmamericium can cause to someone if they are exposed to it. These factors are:

  • The amount of americium as well as its conditions (which isotope, how old it is, how hot it is).
  • The time, if the exposition was short or long. The longer the higher the danger.
  • The manner in which contact happened. Was the element touched, ingested, inhaled, etc.
  • Sometimes, there may be multiple hazardous materials present.
  • Physiological conditions of the individue (age, diet, family traits, lifestyle, and state of health).

Americium Contamination

Americium contamination is possible to happen by different ways

  • By breathing air containing 241Am. 
  • By drinking water containing 241Am.
  • By eating food containing 241Am.

However, high levels of 241Am contamination of the air, water or soil are very unlikely to happen. If it does happen the responsible authority should inform the affected population.

Higher risk of 241Am exposure exists for people living near sites of nuclear power plants or in facilities that handle this element for industrial purposes. People that work in these installations are also under a considerable risk of contamination or of being exposed to some amount of radiation.

Moreover, people that work in the production or transportations of 241Am in smoke detectors may be exposed to higher levels of radioactivity from this element.

Americium Exposure Symptoms

Being exposed to radiation can lead to acute radiation syndrome, which usually causes dizziness, disorientation, hair loss, low blood pressure, headaches, fatigue, fever, skin burns, among others symptoms.

Overall, the magnitude of the symptoms will have a direct correlation with the level of radiation and how this contact took place.

How can Americium Radioactivity Harm Humans

When the americium nucleus goes through the process of radioactive decay, it releases gamma rays (the most energetic of the electromagnetic waves) and alpha particles (two protons and two neutrons bound together).

Gamma rays can travel long distances and can enter the human body with ease. In the case of americium the gamma rays that are released are not on an energy level that can cause serious damage to human health. Unless, the exposure is for a very long time or to a large quantity of the metal.

Unlike gamma rays, alpha particles have high energy but can only travel short distances and usually don’t penetrate human skin. However, if these particles are released within the body (in the case of ingestion or inhalation of americium) these alpha particles can cause serious damage to internal organs cells.

The main cause of adverse health effects from americium that is absorbed is its radiation. If americium enters the body, it is deposited on the surface of the bones and it can remain in there for a long time.

When in the bone americium continues to emit gamma rays and alpha particles to nearby tissues (usually bone cells). This process causes serious damage to the cells, especially the alpha particles.

If the cells are exposed to enough radiation, they will have their genetic material suffer mutations. This can lead to cancer (particularly bone cancer) and other health disorders.

Some studies on animals have been reported, indicating that large amounts of americium within the body causes organ damage (in the liver, lungs, kidneys and thyroid).

The expected amount of americium capable of causing this type of damage to humans would have to be somewhat relatively large.

How to Determine if Someone was Exposed to High Amounts of Americium

In order to test for americium exposure samples must be collected and send to specialized laboratories. It can also be requested to send the individual to be sent to such a specialized laboratory.

A regular health facility can be able to perform blood tests aiming to detect signs of large doses of radiation exposure.

If the americium was from a known testable source, this source can be analyzed for radiation measuring the radiation emitting from these sources. By this approach an estimative can be made of how much radioactive material the person has had contact with.

In the case of inhalation or if americium somehow entered the lungs, it is possible to measure the gamma rays emissions exiting the person’s body. In this manner, a reasonable estimation can be made as to how much americium the person has been exposed to.

However, equipment that are capable of doing such measures are only present in a limited number of locations. Also, it is worth pointing out that the amount of radiation emitted this way quickly falls, therefore this type of exam has to be performed as quickly as possible.

How Can Americium Leakages Happen?

The primary ways americium could be leaked into the environment are:

  • Nuclear reactors that use 241Pu and/or 238U.
  • A nuclear explosion.
  • Accidents in nuclear power plants.
  • Accidents in manufacturing of products containing americium.

Since americium has a half-life of hundreds of years the only way to feasibly remove it from the environment in an eventual leakage is by the proper cleaning procedures.

A curious fact is that 241Pu naturally decays into 241Am, which means that an eventual plutonium leakage can lead to americium contamination indirectly.


Relatively little information about the fire hazards of americium is known, since this is a very rare element.

Americium, as a radioactive metal, poses significant dangers to humans, plants and animals.

It is quite unlikely that the general population will be exposed to americium, given the low abundance of this element and the high safety standards that are implemented by the professionals that are involved in the handling of americium.

Frequently Asked Questions (FAQ): Is Americium Flammable?

Is americium a conductor of heat or electricity?

The thermal conductivity of 241Am is 10 W/m.K, for comparison, the thermal conductivity of regular steel is 45 W/m.K. Meaning americium is a poor heat conductor.

The electrical conductivity of americium is 0.7 x 106 S/m, while the electrical conductivity of steel is 10.1 S/m. Meaning americium has a low electrical conductivity.

What happens if you touch americium?

You will be exposed to radiation (gamma rays and alpha rays in this case). In the case of americium the emitted radiation is relatively moderate. Nonetheless, contact with a large amount of americium or for long periods of time will increasingly lead to high risk of both immediate and long term serious health problems.

What are three uses for americium?

The main use of americium is in ionization based smoke detectors. Thies element can also be used in rdiagraphy as a portable gamma ray source. Some researchers are investigating the possible use of americium in batteries in spatial stations.

Is americium still used in smoke detectors?

Yes, americium with a nuclear mass of 241 a.u. (241Am) is still used in smoke detectors. Some earlier models used 63Ni or 226Rd.

How much americium is in a smoke detector?

Around 0.000029 g.

Can americium make a nuke?

Theoretically yes, americium is somewhat similar to plutonium (239Pu) in the requirements to make a nuclear bomb. However, americium is far more rare than plutonium, in fact one usually needs plutonium to obtain americium.

How do americium based smoke detectors detect smoke?

The radiation emitted by 241Am can ionize molecules in the air. Once ionized these molecules can be detected by an electrical sensor. In the event that smoke reaches the smoke detector, the radiation from americium will no longer be able to ionize the molecules in the air. This lack of detection of ionized entities is what triggers the smoke detector.


Known properties of Americium:

Toxicology profile for americium provided by the Agency of Toxic Substances and Disease Registry (ATSDR):

Nobuo Shinohara, Yuichi Hatsukawa, Kentaro Hata, Nobuaki Kohno. Measurement of Fission Product Yields from Neutron-Induced Fission of Americium-241, Journal of Nuclear Science and Technology, 1999, 36:3, 232-241, doi: 10.1080/18811248.1999.9726203

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