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Hostel for students :: Talks, lectures
Ionizing radiation and radiation safety
Ionizing radiation - a phenomenon associated with radioactivity. Radioactivity - spontaneous transformation of the atomic nuclei of one element into another, accompanied by the emission of ionizing radiation.
The following types of radioactive transformations, alpha-decay electrons, decay, K-capture, spontaneous fission and fusion reactions.
Degree, depth and shape of the radiation injuries of developing biological objects when exposed to ionizing radiation, primarily dependent on the absorbed radiation energy. To characterize this index uses the concept of absorbed dose, ie, the radiation energy absorbed by a unit mass of irradiated material.
Ionizing radiation - a unique phenomenon of the environment, the consequences of which impact on the body at first glance completely equivalent value of the absorbed energy.
If we take as a criterion of sensitivity to ionizing radiation morphological changes, the cells and tissues of the human order of increasing sensitivity can be arranged in the following order: the nervous tissue, cartilage and bone, muscle, connective tissue, thyroid gland, digestive gland, lungs, skin, mucous membranes, sweat glands, lymphoid tissue, bone marrow.
Important biological reaction of the human body to the action of ionizing radiation are divided into two groups:
1) acute injury;
2) long-term effects, which in turn are divided into somatic and genetic effects.
At doses more than 100 rem, acute radiation sickness, the severity of which depends on the radiation dose.
For long-term effects include a variety of somatic biological effects, among which the most important are leukemia, malignant tumors, and reduced life expectancy.
Regulation of radiation and radiation safety principles. Since January 1, 2000 exposure of humans to regulate RF radiation safety standards (NRB-96) Hygienic (GN) 2.6.1.054-96. Basic radiation dose limits and permissible levels set for the following categories of exposed individuals:
1) Personnel - persons working with man-made sources (group A) or under the terms of work in the field of exposure (group B);
2) population, including those of the staff outside the scope and conditions of their production activities.
For these categories of irradiated class provides three standards:
1) basic dose limits (maximum permissible dose - for category A, the dose limit - for category B);
2) acceptable levels;
3) reference levels established by the facility administration in coordination with the SSES level is too low.
Basic principles of radiation safety:
1) reduction of power sources to minimum;
2) reduction in the time to work with sources;
3) increase in the distance from the sources to the employees;
4) screening the radiation source material absorbing the ionizing radiation.
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