Spent nuclear fuel pool

Plutonium - nuclear fuel

Plutonium is a chemical element with symbol Pu and atomic number 94 which belongs to the actinide series of elements. Plutonium has 16 isotopes, all radioactive. The element is a silvery metal and has 5 different crystal structures.

Chemically plutonium is a very active material. You can form compounds with all nonmetals except the noble gases. The metal dissolves in acidic and reacts with water, but only moderately in comparison with the acid.

While you can find traces in nature, all isotopes of plutonium are of artificial origin.

Radioactivity plutonium

The more chemical interest isotope is plutonium-239. Is formed in nuclear reactors. Is fissionable but can also be higher neutron capture plutonium isotopes. Plutonium-239 is used as a nuclear fuel in the production of radioisotopes for Research & as nuclear fissionable agent.

Plutonium-238. Used in heat sources for space applications, heat and thermoelectric generators has been employed in cardiac pacemakers.

An important feature of many of the plutonium isotopes is exhibiting the phenomenon of spontaneous fission, in which the core can be broken spontaneously without being bombarded by no neutrons.

Origin of plutonium

The plutonium is produced when nuclear fuel is burned in conventional nuclear reactors. From irradiated nuclear reactor fuel is composed primarily uranium (at a rate of approximately 96%) and plutonium (with a somewhat less than 1% percent).

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

  • Management of open cycle. In the open cycle is considered that the spent fuel is a high-level radioactive waste from the time of his discharge from the reactor and stored permanently.
  • Management closed cycle. The closed loop consists of subjecting the spent fuel to a mechanical-chemical process known as reprocessing reelaboracióno permits separating uranium and plutonium products still contain transuranic fisióny. The uranium and recovered plutonium used to manufacture new products fuel and transuranic fisióny constituting the residue of high activity.

Role of plutonium in nuclear reactors

As to be generated into the plutonium fuel for nuclear reactors, the plutonium fissions also collaborating with uranium in the production of energy. During the process, other plutonium isotopes is also produced; some are neutron absorbers and others are fissile isotopes.

Irradiacióno Depending time of burnup or the ratio of these isotopes of plutonium in the fuel is reached. A burnt reduced the proportion of fissile isotopes is very high, while at high burn this proportion drops.

In commercial reactors, fuel elements remain in the reactor long time until the accumulation of products fisióny fissile material consumption nullify its contribution to reactor operation.

Management of separated plutonium in nuclear reactors

In the spent fuel are between 7 and 8 pounds per ton of unburned plutonium. This plutonium recovered from reprocessing, can be used to replace the uranium-235 in nuclear fuel manufacturing uranium oxide pellets and plutonium mixed oxide (MOX).

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

threat of plutonium Health

Plutonium is radioactive and toxic. But although sometimes described in the media as the most toxic substance known to humans there are substances that are much more. Naturally occurring radium is about 200 times more radiotoxic than plutonium, and some organic toxins such as botulinum toxin are billions of times more toxic than plutonium.

The main type of radiation emitted (alpha radiation) does not pass through a sheet of paper, that is, a thin layer of material can stop the radiation. You can not penetrate the skin.

What makes really dangerous plutonium is its radiotoxicity. The radiation emitted (alpha) when ingested or inhaled, can cause cancer pulmóno other cancers depending on where you are deposited in the body. In considerably larger amounts may cause acute poisoning radiacióny death if ingested or inhaled.

Plutonium has been used in explosives for a long time. In the atmospheric testing of nuclear weapons have released large amounts of plutonium which subsequently fall and settle on the floor.

It is unlikely that humans are exposed to plutonium, but sometimes occurs as a result of accidental releases during use, transport or pouring.

When you breathe, plutonium can remain in the lungs or move to the bones or other organs. Typically stays in the body for a long time and exposes the body tissues to radiation continuously. After a few years this could result in the development of cancer.

What's more, plutonium can affect the ability to resist disease and the radioactivity of plutonium can cause reproductive failure.

Environmental effects of plutonium

The plutonium is naturally present in very small amounts. However, plutonium has other routes of entry into the environment through leakage of nuclear reactors, weapons production plants, and research facilities. Especially in the testing of nuclear weapons.

Plutonium can enter surface water from accidental spills and leaks of radioactive waste. Soil can become contaminated with plutonium through nuclear fallout during nuclear weapons tests. Plutonium moves slowly down into the soil, into the groundwater.

Plants absorb low levels of plutonium, but these levels are not high enough to cause the plutonium biomagnification in the food chain, or accumulation in the bodies of animals.

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References

Yosoynuclear - Preguntas y respuestas sobre el plutonio

Lenntech - Plutonio - Pu

Last review: April 14, 2014