The Home of American Intellectual Conservatism — First Principles

March 18, 2018

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Nuclear Power and the Energy Crisis
P. E. Hodgson - 10/22/08

Nuclear Radiations

One of the main differences between nuclear and other power stations is the presence of nuclear radiation. The fission fragments produced when the uranium nuclei split are highly radioactive and emit alpha-particles and beta and gamma rays until finally a stable nucleus is formed. There are many different nuclei among the fission fragments, and the rates of emission vary from a small faction of a second to many thousands of years. These decay rates are characterized by a half-life, which is the time taken by the radioactivity of a sample of a particular type of nucleus to decay to half its initial value.

When it passes through the human body, nuclear radiation can break up the complicated molecules inside the cells, releasing reactive radicals that can cause more damage. If the level of radiation is small, few cells are affected; they are soon replaced and no harm is done. If, however, the radiation level is high, serious damage will be caused, and cancers may develop during the following years. In the case of massive whole-body irradiation, death can also take place. It is vital, of course, to specify just what we mean by low and high levels of irradiation, and this will be done later.

The three types of nuclear radiation have different effects on the human body. Alpha-particles are helium nuclei and, since they are doubly charged, they lose energy rapidly and ionize strongly and are very destructive. Their short range means that they are harmful only if the radioactive material is inside the body. The beta rays are energetic electrons, and the gamma rays are short-wavelength electromagnetic radiation. They can both penetrate far inside the human body.

Nuclear radiation can easily be detected by very sensitive instruments that can record the passage of a single particle, so it is possible to detect the presence of extremely small amounts of radioactive substances. This enables us to learn how they move through the atmosphere, the oceans, and our own bodies. This property has proved to be extremely useful in medical research.

When considering the effects of nuclear radiation on people, it is necessary to take account of the different sensitivities of the different organs of the body. This is done by defining the rem, which is the dose given by gamma radiation that transfers a hundred ergs of energy to each gram of biological tissue, and for other types of radiation it is the amount that does the same biological damage. A new unit, the Sievert, has now been defined as 100 rem.

Nuclear radiation is often feared because it is unfamiliar and can cause great damage to living organisms without our being aware that anything untoward is happening. The damage only appears afterwards, sometimes very long afterwards, when it is too late to do anything about it. Our senses warn us of many dangers, such as excessive heat and some poisonous gases, and we can take avoiding action. Nuclear radiation is not alone in being invisible; many poisonous gases such as carbon monoxide have no smell, and we don’t know that a wire is live until we touch it and receive an electric shock.

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