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Nuclear Reactor

What Does Nuclear Reactor Mean?

A nuclear reactor is a device used to create and control a nuclear chain reaction for the purpose of producing power.

This power is commonly used for the propulsion of ships or for electricity generation.

Safeopedia Explains Nuclear Reactor

Some nuclear reactors are also used for research purposes and to create medical isotopes for radiodiagnostics and radiotherapy. The radioactive material used in nuclear reactors emits ionizing radiation, which is recognized as having a deleterious effect on human health. As such, nuclear reactors are subject to a number of occupational health and safety regulations and standards that are designed to protect workers from harmful levels of exposure to radiation. The standards for levels of acceptable exposure have been reduced many times over previous decades as scientists have learned more about the negative health effects of radiation.

The major standards regulating occupational exposure to radiation in nuclear reactors are issued by the United Nations’ International Atomic Energy Agency and by the International Commission on Radiological Protection (ICRP)—a scientific agency operating out of Canada—as well as the jointly developed International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources (BSS). These groups of standards are used to provide common scientific grounding for the harmonization of exposure standards.

The BSS was first jointly developed in 1996 by numerous intergovernmental organizations, including the International Atomic Energy Agency, the International Labour Organization (ILO), and the European Commission. The BSS provides single year dose (exposure) limits for radiation that can only be exceeded in the case of an emergency, such as those necessary to save a life or prevent a nuclear catastrophe. The BSS’s emergency standards stipulate that efforts should be taken in emergency situations to keep exposure below twice the maximum single year dose except where life is immediately in danger, in which case efforts should be taken to keep exposure below 10 times the maximum single year dose. Further, all workers who enter emergency situations in which they may be exposed to above the maximum single year dose limit are required to be volunteers.

The ICRP’s first radiation exposure standards were issued in 1934 at 300 milliSieverts per year (mSv/yr). (Sieverts are a unit of radiation effect). By 1956, the exposure limit for workers had been reduced to 50 mSv/yr and 1 mSv/yr for the public. The current worker limits are 20 mSv/yr averaged over five years, with no exposure greater than 50 mSv in any single year. These current exposure limits do not necessarily provide workers with sufficient exposure protection, as the majority of scientific evidence currently indicates that there is no safe level of radiation exposure. Because of this fact, engineering controls, process controls, and personal protective equipment are used throughout nuclear reactors in most jurisdictions for the purposes of eliminating worker exposure to radiation to the greatest extent practicable.


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