The Home of American Intellectual Conservatism — First Principles

November 17, 2018

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

Radioactive isotopes have many medical applications. If, for example, we want to know how salt is taken up by the body, we can feed a patient with some salt that contains a very small amount of a radioactive isotope of sodium. This emits radiation that can be detected by a counter outside the body, and so we can follow the progress of the sodium as it is absorbed. The amount of radiosodium needed is so small that it does no harm to the patient. In this way radioisotopes provide a valuable diagnostic tool. Radioisotopes can also be used for treatment. For example, it is known that iodine tends to concentrate in the thyroid gland. If therefore we want to treat cancer of the thyroid we can feed the patient with radioiodine, and it will go to the thyroid gland and irradiate the tumor, without appreciably affecting the rest of the body.

The powerful nuclear accelerators that are used to explore the structure of the nucleus and to produce new unstable particles can also be used to irradiate tumors. The radiation emitted by radium and other natural sources has the disadvantage that it is relatively low in energy and so can penetrate only a small distance into the body. In addition, the radiation comes out in all directions equally. If we want to treat a tumor deep inside the body we need a way of irradiating the tumor that minimizes the irradiation of the surrounding healthy tissue. The only way to do this is to have a collimated beam of radiation of sufficient energy to penetrate the body, and such beams are produced by accelerators. During the treatment, the patient is rotated so that the beam always passes through the tumor but irradiates a particular part of the surrounding healthy tissue for only a small part of the time. This is a difficult technique, but with great care it can be used successfully. Many nuclear accelerators such as that at Faure in South Africa are used partly for medical treatment and partly for nuclear research.

Sometimes it is difficult to know whether the benefits of radiation outweigh the hazards. Thus X-rays can detect cancers early enough for effective treatment, and yet they can also themselves cause cancers. A detailed study of stomach tumors showed that for young people the dangers outweigh the benefits, whereas for older people the opposite is the case.

There is widespread public anxiety about the effects of nuclear radiation, particularly concerning the genetic effects and the cases of leukemia in children near nuclear installations. The children of the survivors of the atomic bombing of Hiroshima and Nagasaki, who all received massive doses of radiation, have been studied in detail by Professor S. Kondo, who personally visited Nagasaki soon after the bombing and saw the devastation. He has studied the effects of the bombing for forty years and has recorded the indicators of genetic damage for 20,000 children of atomic bomb survivors exposed to an average dose of 400 mS. The numbers of the genetic indicators such as chromosome abnormalities, mutations of blood proteins, childhood leukemia, congenital defects, stillbirths, and childhood deaths showed no differences between the children of the atomic bomb survivors and a control group. There is thus no evidence of genetic damage due to the atomic bombs.

To estimate the biological damage due to a particular dose of radiation we must know the relation between the two quantities. The difficulty is that the doses that cause measurable damage are hundreds of thousands of times larger than the extra doses received by people living around nuclear installations. It is often assumed that there is a linear relation between the two, so that the probability of contracting cancer is proportional to the dose. As it seems the safest assumption to make, it is widely adopted in setting safety standards. There is, however, no direct evidence for this, and indeed there is much contrary evidence. [3] This is not unreasonable, since the body has an innate capacity to repair damage, and it is only when the defenses of the body are overwhelmed by a massive dose that harm occurs. Thus a dose received over a long period is less harmful than if it were received all at once.

A direct result of the linear dose assumption is the setting of unreasonably strict limits on permitted radiation exposure in many industries, thus greatly increasing costs. This leads to reluctance to accept vital radiodiagnostic and radiotherapeutic irradiations, and restricts the use of radiation in industry and research. Adherence to these exposure limits led to large-scale evacuation from the region around Chernobyl, causing much unnecessary distress and suffering.

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