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Groups of critical bodies of organism
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GROUPS OF CRITICAL BODIES OF ORGANISM
BY RADIO-SENSITIVITY.
LAW OF BERGANIE.
Law French scientist Berganie is so: radio sensitivity of fabrics is directly proportional to its ability to division and inversely proportional to degree of its differentiation. Thus, than more intensively in a fabric or body there are processes of duplication of cells and the less a fabric is differented, the more sensitively it is to radiation.
According to this law all bodies share on 3 groups of critical bodies:
1 - all body, gonades, bodies of blood formation (red bone brain);
2 - all other bodies and fabrics,
3 - skin, bones.
HYGIENIC NORMATIVES of RADIATION
For protection working and the population from radiation are established the following norms, on influence on 1 group of critical bodies are established the maximal permissible doses (MPD) of radiation at external irradiation:
Category A - the persons professionally contacting to radiation –
MPD 2 BER / year (0, 2 Zivert / year) or 40 miliBER in week.
Category B -people who are taking place (living or working) near the sources of radiation – MPD - 0, 2 BER/ year (0, 02 Zv / year).
Category C - all other population - MPD - 0, 1 BER/ year ( (0, 01 Zv / year).
HYGIENE OF WORK WITH RADIATION
Principles of radiation safety at work
with the closed sources of radiation.
CLOSED SOURCE - allocates in environment only electromagnetic radiation - x-ray or gamma - radiation. Basis of protective measures – laws of transmission radiation:
а) The doze of external irradiation is proportional to intensity and time of action;
b) Intensity of radiation is inversely proportional to a distance;
c) Intensity of radiation decreases depending on thickness of screens.
From here - 4 principles protection from radiation:
1) protection by amount of doze (MPD),
2) by distance,
3) by time,
4) by screens.
There are 5 kinds of screens for protection from radiation:
- Protective containers for storage radioisotopes;
- Screens for the equipment;
- Mobile screens;
- Screens in building designs (walls, ceilings, doors, floors);
- Screens in individual means of protection - lead gloves, aprons, etc.
Principles of radiating safety at work
with open sources of radiation.
OPEN SOURCE - allocates in environment not only x-ray and gamma - radiation, but also streams of radioactive particles (alpha, betta - particles and neutrons).
Main principles of protection:
- Use principles of protection at work with the closed sources;
- Hermetic sealing, automatization of the equipment, isolating suits, special boxes and exhaust devices for work with isotopes;
- Special not adsorbing coverings of surfaces, often cleaning surfaces of radioactive pollution;
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- The special equipment of ventilation (exhaust ventilation is equipped with filters), water drains (in special sediment bowls), sufficient water supply;
- Special lay-out of premises with the protective screens; a lay-out of a site of radiological department - distance radiological laboratories from residential buildings, other hospital branches, depending from it class (there is 4 classes of radiological laboratories by annual amount used radioactive substances);
- Careful radiating and medical control personnel;
- Observance personal hygiene and requirements to overalls.
Radiation ecology.
Natural radiating background (NRB)
Natural radiating background - a natural level of radio-activity in the given district, basically dependent on natural factors. On the average NRB makes about 100 miliBER / year, but can test significant fluctuations in view of the natural and anthropogen reasons. In Crimea it is 6-30 miliRoentgen / hour (it is more - in the mountain part of Crimea - radioactivity of the granite masses, containing uranium).
Structure of NRB:
- Space radiation (25-40 %) – it varies in connection with fluctuations of solar activity and interplanetary EMF, on the average the person on the Earth receives by it 28 mBER/year;
- Natural radio-activity of ground (granite - uranium), of air, of water;
- Food stuffs - about 25 % NRB
Thus, in NRB the external irradiation makes 75 %, internal (more dangerous) -25 %.
Additional anthropogen sources of increase NRB for the population:
- Regions of the atomic power station and consequences of it failures and nuclear explosions;
- Diagnostic x-ray procedures (at roentgenoscopia the patient receives 1 BER at once); (it is important to reduce unnecessary diagnostic x-ray procedures).
- TV-sets – at see color TV for 4 hours in day person receives 50 mBER per year. (It is especially important for children).
Dynamics (changes) NRB.
It is investigated since 50th years. First rise of it was in 50th years (reason -mass tests of the nuclear weapon), than - decrease to 70th years (convention about interdiction nuclear tests in 3 air, water – now it is permissible only uderground explosions), growth since 70th years (development atomic power stations).
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