Closed source of radiation in its design (sealed sources of radioactive radiation, x-ray units, accelerators, etc.) excludes the ingress of radioactive substances (RS) into the environment. When working with sealed sources, only external radiation affects the body. Reducing the dose of external exposure is ensured by the minimum necessary time of work in the radiation field, the maximum possible distance from the source to the irradiated object, and shielding of either the radiation source or the irradiated object. When working with open sources, there is a danger of RS getting through the respiratory organs, the digestive tract and through the skin into the body, i.e., there is a danger of internal exposure. To reduce the dose of internal exposure, measures are taken to reduce the amount of radioactive substances entering the body, including sealing technological equipment and workplaces, installing filters on exhaust ventilation systems, rational planning of radiochemical laboratories, using personal protective equipment and observing the rules of radiation hygiene.
In all institutions where work is carried out with the use of radioactive substances and other sources of ionizing radiation, the radiation safety service (RSS) carries out radiation monitoring, the purpose of which is to monitor compliance with radiation safety standards (RSSt), compliance with sanitary rules and obtain information on personnel exposure doses and individuals from the population in the territory of the observed zone (see dose of ionizing radiation). The SRV, depending on the nature of the work, controls: the dose rate of all types of ionizing radiation (except ultraviolet) at workplaces, in adjacent premises, in the sanitary protection zone and on the territory of the monitored zone; the level of radioactive contamination of working premises, clothing and skin of personnel, environmental objects outside the institution; for the collection and removal of solid and liquid radioactive waste for the release of radioactive substances into the atmosphere; over the level of exposure of personnel and individuals from the population in the territory of the observed zone. Depending on the nature of the work, individual control includes measuring doses of external β -radiation, neutrons, X-ray and γ - radiation, as well as monitoring the content of RS in the body or in a separate organ.
Based on the possible genetic and somatic consequences of the action of ionizing radiation on the body (see. The biological effect of ionizing radiation) and taking into account the size of certain population groups, the radiation safety standards of 1969 (NRB-69) established the following categories of exposed persons and traffic rules for them: category "A » (staff) - 5 rem per year for the whole organism, gonads and hematopoietic organs; category "B" (individuals from the population) - the annual dose limit should not exceed 0.5 rem for the whole body, gonads and hematopoietic organs; category "B" (general population), with an assessment of the genetic consequences of exposure - a genetically significant dose should not exceed 5 rem for 30 years. These radiation dose limits do not include possible radiation doses due to medical procedures and natural background radiation. NRB also regulate the content of RS in water, in the atmospheric air and in the air of working premises. Norms R. b. and sanitary rules for working with radioactive substances in force in the USSR were developed in accordance with the recommendations of the International Commission on Radiation Protection (ICRP).
