Plutonium

Author: Dr Kelvin Klemm

( Article Type: Explanation )

Plutonium is a heavy metal not found in nature because it undergoes radioactive decay over a period of time, and millions of years ago all the plutonium in the Earth’s crust had already disappeared due to the steady radioactive decay.

It is possible to make plutonium by bombarding uranium with neutrons in a nuclear reactor. Of commercial importance is the fact that plutonium is produced as a natural consequence of uranium being used as fuel in a conventional nuclear reactor, of which there are hundreds in the World. Plutonium and uranium have a significant property in common where, when hit just the right way by a neutron, they undergo splitting or fission. This means that plutonium can be used as a nuclear reactor fuel. As a uranium-fuelled nuclear reactor burns up its fuel, it produces some plutonium as a natural consequence of the nuclear chain reaction. This plutonium can be extracted and used as fuel in a plutonium reactor. A major problem is that the plutonium produced is all mixed in with unused uranium, and also with all the radioactive by-products of the nuclear process, so it is extremely difficult to separate it from the highly radioactive spent fuel. Only a very few countries possess the technology to do this.

Another issue that has made pplutonium rather notorious is that it is also toxic like any other heavy metal, including lead (this has nothing to do with its radioactivity). As far as the radioactivity is concerned, it is not very dangerous, but if plutonium dust becomes inhaled into one’s lungs it can induce cancer, because a dust particle can sit for some time against the lung tissue emitting short-range radiation. It is therefore a potential carcinogenic hazard for plutonium workers if it is not handled correctly. plutonium has been incorrectly labelled as the ‘most toxic substance known to man’; this is far from the truth.

Another issue that has brought plutonium to public attention is the plutonium shipments from France to Japan that pass the Cape. This plutonium is taken to Japan to fuel Japanese plutonium reactors. The cycle is that Japan sends some of its spent uranium fuel to France where France extracts the Japanese plutonium and then sends it back to Japan. In many quarters, considerable public fear was created relating to the possibility of the ship having an accident and so releasing some of the plutonium.

Plutonium and uranium are the only two atoms that will fission for the purposes of the production of commercial nuclear power.