Radiation Safety

measures taken when working with radioactive substances and other sources of ionizing radiation to reduce the total dose from all types of ionizing radiation to the maximum permissible dose.

A closed source of radiation by virtue of its design— hermetically sealed sources of radioactive radiation, X-ray machines, and accelerators—prevents radioactive substances from entering the environment. Only external irradiation acts on the body during exposure to closed sources. The dose of external irradiation may be reduced by spending the minimum possible amount of time in the radiation field, by placing the maximum possible distance between the source and object of irradiation, and by shielding either the source of radiation or the object irradiated.

Proximity to open sources of radiation poses the danger that radioactive substances may enter the body through the respiratory tract, alimentary canal, and skin; that is, the danger of internal irradiation arises. To reduce the dose of internal irradiation, measures are taken to decrease the amount of radioactive substances entering the body. Such measures include hermetically sealing equipment and places of work, installing filters in exhaust systems, rationally planning radiochemical laboratories, utilizing means of individual protection, and observing the rules of radiation hygiene.

The radiation safety service inspects all establishments where radioactive substances and other sources of ionizing radiation are used. It monitors compliance with radiation safety norms and health regulations and obtains information on the irradiation doses received by the personnel and by individuals living in the area. Depending on the nature of the job, the radiation safety service monitors the dose rate of all types of ionizing radiation (except ultraviolet) in places of work and adjacent areas, health protection zones, and the general work area. It also measures the contamination of places of work, of the personnel’s clothing and skin, and of environmental objects outside the work area. It inspects the collection and removal of solid and liquid radioactive wastes and measures the emission of radioactive substances into the atmosphere and the level of irradiation of the personnel and of individuals living in the area. Depending on the nature of the job, personnel monitoring also includes measurement of doses of external β-radiation, neutrons, and X- and γ-radiation and the monitoring of the level of radioactive substances in the body or individual organs.

Three categories—A, B, and C—of irradiated persons and the maximum permissible doses they may receive were established by the 1969 radiation safety norms, based on the possible genetic and somatic effects of ionizing radiation and the size of population groups. For persons in category A, which includes all those working in establishments where radioactive substances are used or radiation is present, 5 rem a year is the maximum permissible dose for the entire body and for the gonads and hematopoietic organs. For persons in category B, which includes individual local inhabitants, the annual maximum dose must not exceed 0.5 rem for the entire body and for the gonads and hematopoietic organs. For persons in category C, which includes the population as a whole, with an estimation of the genetic effects of irradiation, the genetically significant dose must not exceed 5 rem in 30 years. These maximum irradiation doses do not include the possible irradiation doses resulting from medical procedures or from natural background radiation. The radiation safety standards also regulate the level of radioactive substances in water and air. The radiation safety standards and health regulations enforced in the USSR in establishments where radioactive substances are used were developed in accordance with the recommendations of the International Radiation Protection Association.