Sunday, December 27, 2009

Radiation protection : Justification of a practice.

1- Justification of a practice.

Practices are activities involving the deliberate use of radiation. Such uses are clearly defined and can be regulated. On the other hand, we can generally do nothing practical to reduce the normal levels of dose from natural radiation, although it is appropriate to intervene when people are exposed to high levels of radon in their homes or at work.

For workers, some control also needs to be exercised over exposures to radiation from ores and other materials, such as scales in oil and gas rigs, with elevated levels of naturally occurring radionuclides.

The use of radiation in medicine is mainly a matter of clinical judgement since medical exposures are intended to benefit patients. Setting limits on doses to patients would not be sensible: it might also limit the benefits. However, the principles of justification and optimization, discussed next, should apply in full, particularly as there is scope for reducing individual doses.

No practice involving exposure to radia­tion should be adopted unless it pro­duces at least sufficient benefit to the exposed individuals or to society to offset the radiation detriment it causes.

The first requirement in the system of radiological protection for practices emphasizes the obvious need to consider harmful costs in the light of the benefits. In most cases, radiation effects are just some of a number of possible harmful outcomes that make up part of the overall social and economic costs. If there are other ways to achieve the same end, with or without radiation, it is important to analyze the costs and benefits of the alternatives before making a final decision in favor of one or the other.
The issues that arise in the process of justification extend far beyond radiological pro­tection and may be illustrated by the arguments about the nuclear power program. The radiological consequences of the program include the discharge of radioactive substances to the environment and the doses received by workers in the nuclear power industry. In addition, a full analysis would deal with the potential for nuclear reactor accidents, as well as the creation of radioactive wastes. Account should also be taken of doses and accidents to uranium miners (who are often in countries other than those using the uranium).
An assessment should then be made of the consequences of doing without the energy provided by nuclear power or of using alternative methods to produce it - with coal for instance. Generating electric power from coal creates large volumes of waste and releases gases that worsen the greenhouse effect. Coal-fired power stations also discharge toxic substances and natural radioactive materials, coal miners suffer occupational diseases, and there is the potential for mining accidents. A complete analysis would also need to consider several strategic and economic factors: the diversity, security, availability, and reserves of various fuels; the construction and oper­ating costs of various types of power station; the expected demand for electricity; and the willingness of people to work in a particular industry

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