Radioactive substances (PW) can penetrate the body in three ways: with inhaled air, through the gastrointestinal tract (with food and water), through the skin. A person gets irradiation not only outside, but through the internal organs. The RV penetrates the molecules of internal organs, especially bone tissue and muscles. Concentrating in them, the RV continue to irradiate and damage the body from the inside.
Radiation risk is the likelihood of a person or his offspring of any harmful effect as a result of irradiation.
Ionizing radiation when exposed to the human body can cause adverse effects of two types:
Deterministic (radiation disease, radiation dermatitis, radiation cataract, radiation infertility, anomalies in the development of the fetus, etc.). The existence of a dose threshold is assumed, below which the effect is absent, and above which the severity of the effect depends on the dose;
Stochastic probabilistic unhealthy harmful biological effects (malignant tumors, leukemia, hereditary diseases) who have no dose threshold of occurrence. The severity of their manifestation does not depend on the dose. The period of the occurrence of these effects in the irradiated person ranges from 2 to 50 years and more.
The biological effect of ionizing radiation is associated with the formation of new, non-characteristic compounds that violate the activities of both individual functions and entire organism systems. Partially comes the processes of restoration of the structures of the body. The total recovery result depends on the intensity of these processes. With increasing radiation power, the significance of recovery processes is reduced.
There are genetic (hereditary) and somatic (bodily) harmful effects.
Genetic effects are associated with a change in the gene apparatus under the action of ionizing radiation. The consequences of this are mutations (the appearance of offspring in irradiated people with other signs, often with congenital deformities).
Genetic effects have a long hidden period (dozens of years after irradiation). Such a danger exists even with very weak irradiation, which, although it does not destroy the cells, but can change hereditary properties.
Somatic effects always begin with a certain threshold dose. With doses of smaller than thresholds, the body damage does not occur. Somatic effects include local damage to the skin (radiation burn), eye cataract (lens), damage to the genital organs (short-term or constant sterilization). The body is able to overcome many somatic effects of irradiation.
The degree of radiation lesion largely depends on the size of the irradiated surface, on whether the body or only part of it was exposed to irradiation. The biological effect decreases with its reduction.
Long-term irradiation with small doses (chronic) in the working environment can lead to the development of chronic radiation disease. The most characteristic features of chronic radiation sickness are changes in blood formula, local lesions of the skin, lesions of the lens, pneumosclerosis, decrease in immunity. The ability to cause long-term consequences is one of the insidious properties of ionizing radiation.
Ionizing radiation is radiation, the interaction of which with a substance leads to the formation of different sign ions in this substance. Ionizing radiation consists of charged and uncharged particles to which photons also include. The energy of particles of ionizing radiation is measured in an introductory units of electron-volt, eV. 1EV \u003d 1.6 10 -19 J.
There are corpuscular and photonic ionizing radiation.
Vaccular ionizing radiation- the flow of elementary particles with a mass of rest different from zero formed during radioactive decay, nuclear transformations or accelerators generated. It includes: α- and β-particles, neutrons (N), protons (P), etc.
α-radiation is a flow of particles that are the kernels of the helium atom and possessing two units of charge. The energy of α-particles emitted by various radionuclides lies within 2-8 MeV. In this case, all the kernels of this radionuclide emit α-particles with one and the same energy.
β-radiation is a flow of electrons or positrons. When the cores of the β-active radionuclide are decayed, in contrast to α-decay, the various cores of this radionuclide emit β-particles of different energy, therefore the energy spectrum of β-particles is continuous. The average energy of the β spectrum is approximately 0.3 E TAX.The maximum energy of β-particles at currently known radionuclides can reach 3.0-3.5 MeV.
Neutrons (neutron radiation) are neutral elementary particles. Since neutrons do not have an electric charge, when passing through the substance, they interact only with the nuclei of atoms. As a result of these processes, either charged particles (recoil cores, protons, neutrons), or G-radiation, causing ionization, are formed. By the nature of the interaction with the medium depending on the level of neutron energy, they are conditionally divided into 4 groups:
1) thermal neutrons 0.0-0.5 keV;
2) intermediate neutrons 0.5-200 keV;
3) Quick neutrons 200 keV - 20 MeV;
4) relativistic neutrons over 20 MeV.
Photon radiation- the flow of electromagnetic oscillations that apply to vacuum at a constant speed of 300,000 km / s. It includes G-radiation, characteristic, brake and X-ray
radiation.
Possessing the same nature, these types of electromagnetic radiation differ in the conditions of education, as well as properties: wavelength and energy.
Thus, G-radiation is emitted under nuclear transformations or with particle annihilation.
Characteristic radiation - photon radiation with a discrete spectrum emitted by changing the energy state of an atom due to the restructuring of internal electron shells.
The braking radiation is associated with a change in the kinetic energy of charged particles, has a continuous spectrum and occurs in the medium surrounding the β-radiation source, in X-ray tubes, in electrons accelerators, etc.
X-ray radiation is a set of brake and characteristic emissions, the photon energy range of which is 1 keV - 1 MeV.
Radiations are characterized by their ionizing and penetrating ability.
Ionizing ability The radiation is determined by specific ionization, i.e., the number of pairs of ions, created by a particle in a unit of mass volume of the medium or on a single path length. Radiation of various species have different ionizing ability.
Penetrating ability The radiation is determined by the magnitude of the mileage. The mileage is called the path traveled by a particle in the substance until its complete stop, due to one or another type of interaction.
α-particles have the greatest ionizing ability and the smallest penetrating ability. Their specific ionization varies from 25 to 60 thousand pairs of ions for 1 cm path in the air. The length of the mileage of these particles in the air is several centimeters, and in a soft biological tissue - several dozen microns.
β-radiation has a significant smaller ionizing ability and a large penetrating ability. The average value of the specific ionization in the air is about 100 pairs of ions per 1 cm path, and the maximum mileage reaches several meters at high energies.
The smallest ionizing ability and the greatest penetrating ability possess photon radiation. In all the processes of interaction of electromagnetic radiation, with a part of energy, the secondary electron is converted into the kinetic energy of secondary electrons, which, passing through the substance, produce ionization. The passage of photon radiation through the substance at all can not be characterized by the concept of run. The weakening of the flow of electromagnetic radiation in the substance obeys the exponential law and is characterized by the attenuation coefficient of p., Which depends on the energy of the radiation and the properties of the substance. But whatever the thickness of the substance layer cannot be completely absorbed by the photon radiation stream, and it is only possible to weaken its intensity into any time.
In this significant difference between the nature of the weakening of photonic radiation from the weakening of the charged particles, for which there is a minimum thickness of the substance-absorber (mileage), where the absorption of the flow of charged particles occurs.
The biological effect of ionizing radiation. Under the influence of ionizing radiation on the human body in tissues, complex physical and biological processes may occur. As a result of ionization of living tissue, molecular bonds take place and changing the chemical structure of various compounds, which in turn leads to cell death.
An even more substantial role in the formation of biological consequences is played by water radiolization products, which is 60-70% of the mass of biological tissue. Under the action of ionizing radiation on water, free N · and · ·, and in the presence of oxygen, also free hydroperoxide radical (but · 2) and hydrogen peroxide (H 2 O 2), which are strong oxidizing agents. Radiolization products come into chemical reactions with tissue molecules, forming compounds that are not characteristic of a healthy organism. This leads to a violation of individual functions or systems, as well as the vital activity of the body as a whole.
The intensity of chemical reactions induced by free radicals increases, and many hundreds and thousands of molecules not affected by irradiation are involved in them. This is the specificity of the action of ionizing radiation to biological objects, that is, the effect produced by the radiation is due not so much by the amount of energy absorbed in the irradiated object, as the form in which this energy is transmitted. No other type of energy (thermal, electrical, etc.), absorbed by the biological object in the same quantity, does not lead to such changes that ionizing radiation cause.
Ionizing radiation when exposed to a person's body can cause two types of effects that are clinical medicine related to diseases: deterministic threshold effects (radiation disease, radiation burn, radiation cataract, radiation infertility, anomalies in the development of the fetus, etc.) and stochastic (probabilistic) unhealthy Effects (malignant tumors, leukemia, hereditary diseases).
Violations of biological processes can be either reversible when the normal operation of the cells of the irradiated tissue is completely restored, or irreversible, leading to the defeat of individual organs or the whole organism and occurrence radiation disease.
There are two forms of radiation sickness - sharp and chronic.
Acute formarises as a result of irradiation with large doses in a short period of time. With doses of the order of thousands, the defeat of the body can be instant ("death under the beam"). Acute radiation disease may occur in the body of large quantities of radionuclides.
Acute lesions are developing with a single uniform gamma irradiation of the entire body and the absorbed dose above 0.5 grams. At a dose of 0.25 ... 0.5 gras, temporary changes in the blood may be observed, which are rapidly normalized. In the dose interval of 0.5 ... 1.5 grams there is a sense of fatigue, less than 10% of irradiated vomiting, moderate changes in the blood can occur. At a dose of 1.5 ... 2.0 grams, a light form of acute radiation disease is observed, which is manifested by prolonged lymphopoint (decrease in the number of lymphocytes - immunocompetent cells), in 30 ... 50% of cases - vomiting in the first day after irradiation. Deadly outcomes are not registered.
The radiation sickness of medium severity occurs at a dose of 2.5 ... 4.0 gr. Almost everyone irradiated in the first day is nauseous, vomiting, the content of leukocytes in the blood is sharply reduced, subcutaneous hemorrhages appear, in 20% of cases, death occurs, death occurs after 2 ... 6 weeks after irradiation. At a dose of 4.0 ... 6.0 grams, a severe form of radiation disease is developing, leading in 50% of cases to death during the first month. With doses exceeding 6.0 grams, an extremely severe form of radiation disease is developing, which almost 100% of cases ends with death due to hemorrhage or infectious diseases. These data refer to cases when there is no treatment. Currently, there are a number of anti-collaborate funds, which, with complex treatment, make it possible to exclude the fatal outcome at doses of about 10 grams.
Chronic radiation disease can develop with continuous or repeating radiation in doses, significantly lower than those that cause acute form. The most characteristic signs of chronic radiation disease are changes in the blood, a number of symptoms from the nervous system, local lesions of the skin, lesions of the lens, pneumosclerosis (with inhalation of Plutonium-239), a decrease in the immunoreactivity of the body.
The degree of radiation exposure depends on whether irradiation is external or internal (when the radioactive isotope is inserted into the body). Internal exposure is possible when inhaling, swallowing radioisotopes and penetration into the body through the skin. Some substances are absorbed and accumulated in specific organs, which leads to high local radiation doses. Calcium, radium, strontium and others accumulate in the bones, iodine isotopes cause damage to the thyroid gland, rare-earth elements are predominantly the liver tumor. Cesium, rubidium isotopes are evenly distributed, causing the inhibition of blood formation, atrophy of the seeds, soft tumors tumors. With internal irradiation, alpha-emitting isotopes polonium and plutonium are most dangerous.
The ability to cause remote effects - leukemia, malignant neoplasms, early aging is one of the insidious properties of ionizing radiation.
To resolve radiation safety issues, the effects observed at the "small doses" are of interest - the order of several centysizivers per hour and below, which are actually found in the practical use of atomic energy.
It is very important here that, according to modern ideas, the output of adverse effects in the range of "small doses", found under normal conditions, is little depends on the dose rate. This means that the effect is determined primarily by the total accumulated dose, regardless of whether it was obtained for 1 day, for 1 s or over 50 years. Thus, estimating chronic irradiation effects should be borne in mind that these effects accumulate in the body for a long time.
Dosimetric values \u200b\u200band units of their measurement. The actions of ionizing radiation on the substance manifests itself in the ionization and excitation of atoms and molecules that are part of the substance. The quantitative measure of this impact is the absorbed dose D P.- average energy transmitted by the radiation unit of mass of the substance. Unit of absorbed dose - Gray (GR). 1 grade \u003d 1 j / kg. In practice, an extra-system unit is also applied - 1 rad \u003d 100 erg / g \u003d 1 10 -2 j / kg \u003d 0.01 g.
The absorbed radiation dose depends on the properties of the radiation and the absorbing medium.
For charged particles (α, β, protons) of small energies, rapid neutrons and some other radiation, when the main processes of their interaction with the substance are direct ionization and excitation, the absorbed dose serves as an unambiguous characteristic of ionizing radiation by its effect on Wednesday. This is due to the fact that between the parameters characterizing these types of radiation (flow, flow density, etc.) and the parameter characterizing the ionization ability of radiation in the medium absorbed dose, adequate direct dependencies can be installed.
For X-ray and G-radiation, such dependencies are not observed, since these types of radiation are indirectly ionizing. Consequently, the absorbed dose cannot serve as the characteristic of these radiation on their impact on the environment.
Until recently, the so-called exposure dose is used as a characteristic of X-ray and G-radiations on the effect of ionization. The exposure dose expresses the energy of photonic radiation, converted into the kinetic energy of secondary electrons producing ionization in a unit of mass of atmospheric air.
Behind the unit of exposure dose of X-ray and G-radiations take a pendant per kilogram (CL / kg). This is such a dose of X-ray or G-radiation, when exposed to which 1 kg of dry atmospheric air under normal conditions, ions are formed, carrying 1 cell electricity of each sign.
In practice, an extra system unit of an exposure dose is still widely used. 1 X-ray (P) - an exposure dose of X-ray and G-radiation, at which 0.001293 g (1 cm 3 of air under normal conditions) are formed by charges carrying a charge into one electrostatic unit of the amount of electricity of each sign or 1 p \u003d 2.58 10 -4 CL / kg. With an exposure dose of 1 p, 2.08 10 9 pairs of ions in 0.001293 g of atmospheric air will be formed.
Studies of biological effects caused by various ionizing radiation have shown that tissue damage is associated not only with the amount of absorbed energy, but also with its spatial distribution characterized by a linear ionization density. The higher the linear density of ionization, or, otherwise, the linear transmission of the particle energy in the medium per unit of the path length (LPE), the greater the degree of biological damage. To take into account this effect, the concept of an equivalent dose is introduced.
Dose is equivalent to H T, R -absorbed dose in organ or fabric D T, R , multiplier to the appropriate weighing coefficient for this radiation W R.:
H T, R=W R d T, R
The unit of measuring equivalent dose is J. kg -1, having a special name Ziver (SV).
Values W R.for photons, electrons and muons of any energies is 1, for α-particles, fragments of division, heavy nuclei - 20. Weighing coefficients for certain types of radiation when calculating an equivalent dose:
· Photons of any energies ............................................................ .1
· Electrons and muons (less than 10 keV) ............................................. .1
· Neutron with an energy of less than 10 keV ........................................................... ... 5
from 10 keV up to 100 keV ...... .... ...................................................... 10
from 100 keV to 2 MeV ...............................................................................20
from 2 MeV to 20 MeV .................................................................10
more than 20 MeV ........................................................................... 5
· Protons, except for protons of return,
energy more than 2 MeV .......................................................... 5
· Alpha particles,
shardings of division, heavy nuclei ................................................ .20
Dose effective- The value used as a measure of the risk of the emergence of the distant consequences of the exposure of the entire body of a person and its individual bodies, taking into account their radio sensitivity, it represents the amount of equivalent doses in the body N τton the appropriate weighing coefficient for this organ or fabric W T:
where N τt -equivalent dose in fabric T. during τ .
The unit of measure of an effective dose - J × kg -1, called ziver (SV).
Values W T.for certain types of fabrics and organs are shown below:
Type of fabric, organ W 1.
Gonads ................................................. .................................................. ............. 0,2
Bone marrow, (red), lungs, stomach .................................... 0.12
Liver, breast gland, thyroid gland. .............................. ... 0.05
Leather ....................................................................................... 0,01
The absorbed, exposure and equivalent doses, classified as a unit of time, are called the power of the corresponding doses.
Spontaneous (spontaneous) disintegration of radioactive nuclei should be a law:
N \u003d n 0ex (-λt),
where N 0- the number of nuclei in this volume of the substance at the time T \u003d 0; N.- number of nuclei in the same volume by the time T ; λ - constant decay.
The constant λ makes sense of the probability of the decay of the core for 1 s; It is equal to the proportion of nuclei, decaying for 1 s. The constant decay does not depend on the total number of nuclei and has a completely definite value for each radioactive nuclide.
The equation above shows that over time, the number of radioactive substance nuclei decreases according to the exponential law.
Due to the fact that the half-life of a significant number of radioactive isotopes is measured by clocks and days (the so-called short-lived isotopes), it needs to be known to evaluate the radiation hazard in time in the event of an emergency emission into the environment of the radioactive substance, the choice of deactivation method, as well as when processing Radioactive waste and subsequent burial.
The types of doses relate to a separate person, that is, they are individual.
Having arising the individual effective equivalent doses obtained by a group of people, we will come to a collective efficient equivalent dose that is measured in human-sovereigns (people).
You should enter another definition.
Many radionuclides disintegrate very slowly and remain in the distant future.
Collective effective equivalent dose that generations of people will receive from a radioactive source for all the time of its existence, called expected (full) collective effective equivalent dose.
The activity of the drug -this is a measure of the number of radioactive substance.
The activity is determined by the number of disintegrating atoms per unit of time, that is, the decay speed of the radionuclide cores.
The unit of activity measurement is one nuclear transformation per second. In the system of SI, it was named beckel (BK).
For an incidental unit of activity, Curie (CI) was adopted - the activity of such a number of radionuclide, in which 3.7 × 10 10 decay acts per second occurs. In practice, the ki derivatives are widely used: Millikuri - 1 mki \u003d 1 × 10 -3 ki; Microcures - 1 mkc \u003d 1 × 10 -6 ki.
Measurement of ionizing radiation. It must be remembered that there are no universal methods and devices applicable to any conditions. Each method and device have their own scope. Unaccepting these comments can lead to gross mistakes.
Radio system uses radiometers, dosimeters and spectrometers.
Radiometers- These are devices designed to determine the number of radioactive substances (radionuclides) or radiation stream. For example, gas-discharge counters (Geiger Muller).
Dosimeters- These are devices for measuring the power of the exposure or absorbed dose.
Spectrometersserve to register and analyze the energy spectrum and identification on this basis radiating radionuclides.
Rationing.Radiation security issues are regulated by the Federal Law "On Radiation Safety of the Population", radiation safety standards (NRB-99) and other rules and provisions. The law "On the radiation safety of the population" states: "The radiation security of the population is the state of the protection of the present and future generations of people from the impact of ionizing radiation harmful to their health" (Article 1).
"Citizens of the Russian Federation, foreign citizens and stateless persons living in the Russian Federation have the right to radiation safety. This right is provided by the complex of measures to prevent radiation impact on the human system of ionizing radiation above established norms, rules and standards, by citizens and organizations carrying out activities using ionizing radiation sources, radiation safety requirements "(Article 22).
The hygienic regulation of ionizing radiation is determined by the Radiation Safety Rate NRB-99 (Sanitary Rules of the SP 2.6.1.758-99). The main doses of irradiation limits and permissible levels are set for the following categories.
irradiated persons:
· Personnel working with technogenic sources (Group A) or under work in the field of their impact (group B);
· All population, including persons from personnel, beyond the sphere and conditions of their production activities.
1. ionizing radiation, their types, nature and basic properties.
2. ionizing radiation, their features, basic qualities, units of measurement. (2 in 1)
For better perception of the subsequent material, it is necessary to
thread some concepts.
1. The kernels of all atoms of one element have the same charge, that is,
zat the same number of positively charged protons and various
the number of particles without charge - neutrons.
2. The positive charge of the core due to the number of protons, equalized
summates with a negative charge of electrons. Therefore, an atom electrically
neutral.
3. Atoms of the same element with the same charge, but different
the number of neutrons is called isotopes.
4. The isotopes of one and the same element have the same chemical, but
personal physical properties.
5. Isotopes (or nuclides) in their sustainability are divided into stable and
disintegrating, i.e. Radioactive.
6. Radioactivity - spontaneous transformation of nuclei of atoms of one
cops to other, accompanied by the emission of ionizing radiation
7. Radioactive isotopes are disintegrated at a certain speed, measured
my half-life, i.e., time when the initial number
nuclear decreases twice. Hence, radioactive isotopes are divided into
short-lived (half-life is calculated from the fraction of a second to
how many days) and long-lived (with a half-life from several
syatsy to billions of years).
8. Radioactive decay can not be stopped, is accelerated or slowed down
kim or way.
9. The speed of nuclear transformations is characterized by activity, i.e. Number
disintegration per unit time. The unit of activity is Becquer
(BC) - One conversion per second. Introduced Activity Unit -
curie (CI), 3.7 x 1010 times big than Becquer.
Distinguish the following types of radioactive transformations: corpus
large and wave.
The corpuscular attributes:
1. Alpha decay. Characterized for natural radioactive elements with
large sequence numbers and is a stream of helium nuclei,
carrier double positive charge. Empty of alpha particles
no energy with the kernels of the same species occurs in the presence of various
energy levels. In this case, the excited kernels arise, which
some turning to the main state, they emit gamma quanta. When intelligent
moisy of alpha particles with a substance of their energy is spent on the excitement
the ionization of atoms of the medium.
Alpha particles are inherent in the greatest degree of ionization -
60000 pairs of ions on the way in 1 cm air. First the trajectory of particles
gII, collision with nuclei), which increases the ionization density at the end
path particles.
Possessing a relatively large mass and charge, alpha particles
have a slight penetrating ability. So, for alpha particles
with the energy of 4 MeV, the length of the run in the air is 2.5 cm, and biological
fabric 0.03mm. Alpha decay leads to a decrease in the ordinal
measure of a substance for two units and a mass number for four units.
Example: ----- +
Alpha particles are treated as internal irradiators. Per-
shield: Papile paper, clothing, aluminum foil.
2. Electronic beta decay. Characterized both for natural and for
artificial radioactive elements. The kernel emits the electron and
with this nucleus of the new element with a constant mass number and with
big sequence number.
Example: ----- + ē
When the kernel eats an electron, it is accompanied by the emission of neutrino
(1/2000 Mass of the coach of the electron).
In the emission of beta particles of the nucleus of atoms can be in an excited
condition. The transition of them to the unexcitable state is accompanied by
kinga gamma quanta. Length of the beta particle in the air at 4 MeV 17
see 60 pairs of ions are formed.
3. Positron beta decay. Observed in some artificial
dioactive isotopes. The mass of the nucleus is practically not changed, but
the number is reduced by one.
4. K-capture of the orbital electron core. The kernel captures the electron with
shells, while the neutron flies out of the kernel and the characteristics occurs
x-ray radiation.
5. The corpuscular radiations also include neutron. Neutron non.
having charge elementary particles with a mass equal to 1. depending
from their energy distinguish slow (cold, thermal and laid-iron)
resonant, intermediate, fast, very fast and super-fast
neutron. Neutron radiation is the shortest way: after 30-40
kund neutron disintegrates to electron and proton. Penetrating ability
neutron flux is comparable to such for gamma radiation. When penetrated
the neutron radiation in the tissue to the depth of 4-6 cm is formed by
denic radioactivity: stable elements become radioactive.
6. Spontaneous division of nuclei. This process is observed at radioactive
elements with a large atomic number when capturing their nuclei of a slow
electrons. The same nuclei form various pairs of fragments with
council number of neutrons. When dividing the nuclei, energy is highlighted.
If neutrons are again used for subsequent division of other nuclei,
the reaction will be chain.
In radiotherapy of tumors, pi-mesons are used - elementary
styles with a negative charge and mass, 300 times higher than the mass
throne. Pi mezons interact with atom nuclei only at the end of the run, where
they destroy the kernel of the irradiated fabric.
Wave types of transformations.
1. Gamma rays. This is the flow of electromagnetic waves in length from 0.1 to 0.001
nm. The speed of their propagation is close to the speed of light. Penetrating
high ability: they can penetrate not only through the body of human
ka, but through more dense environments. In the air, the magnitude of the gamma
rays reaches a few hundred meters. The energy of gamma quantum is almost
10,000 times higher than the energy of the visible light quantum.
2. X-rays. Electromagnetic radiation, artificially
in x-ray tubes. When filing high voltage on
cathode, electrons fly out from it, which at a high speed of moving
be torn to anticatics and hit its surface made of
hang metal. There is a brake x-ray radiation,
high penetrating ability.
Features of radiation radiation
1. No source of radioactive radiation is defined by any
gan feelings.
2. Radioactive radiation is a universal factor for various sciences.
3. Radioactive radiation is a global factor. In the case of nuclear
pollution of the territory of one country The effect of radiation is also obtained.
4. Under the action of radioactive radiation in the body, specific
reactions.
Qualities inherent in radioactive elements
and ionizing radiation
1. Changes in physical properties.
2. The ability to ionization of the environment.
3. Penetrating ability.
4. The half-life period.
5. half-life.
6. The presence of a critical organ, i.e. Fabrics, organ or body parts, irradiation
which can bring the greatest damage to human health or his
offspring.
3. Stages of the action of ionizing radiation on the human body.
The effect of ionizing radiation on the body
Direct direct disorders in cells and tissues occurring
following the emission, insignificant. So, for example, under the action of irradiation,
the death of the experimental animal, the temperature in its body is
easy only one hundredth of degrees. However, under the action of
dioactive radiation in the body arise very serious varieties
violations that should be considered in stages.
1. Physico-chemical stage
The phenomena that occur at this stage are called primary or
launched. They determines the entire further course of radiation development.
lesions.
First, ionizing radiation interact with water, knocking out of
her electrons molecules. Molecular ions carrying positives are formed
and negative charges. There is a so-called radioliz of water.
H2O - ē → H2O +
H2O + ē → H2-
H2O molecule can be destroyed: H and he
Hydroxis can be recombine: it
It forms hydrogen peroxide H2O2
In the interaction of H2O2 and it is formed but2 (hydroperoxide) and H2O
Ionized and excited atoms and molecules for 10 seconds
dy interact with each other and with various molecular systems,
giving the beginning to chemically active centers (free radicals, ions, ion
radicals, etc.). In the same period, bonding breaks in molecules as for
the score of direct interaction with the ionizing agent and for
the invoice of the ins- and intermolecular transmission of excitation energy.
2. Biochemical stage
The permeability of membranes increases, they begin diffundund
electrolytes, water, enzymes in organelles.
Arising from the interaction of radical radiation radiation
interact with dissolved molecules of various compounds, giving
the beginning of the second cardical products.
Further development of radiation damage to molecular structures
it comes down to changes in proteins, lipids, carbohydrates and enzymes.
In proteins occur:
Configuration changes in the protein structure.
Aggregation of molecules due to the formation of disulfide ties
The gap of peptide or carbon ties leading to protein destruction
Reducing the level of methionine-donator sulfhydryl groups, trypto-
fana, which leads to a sharp slowdown of protein synthesis
Reducing the content of sulfhydryl groups due to their inactivation
Damage to the synthesis of nucleic acids
In lipids:
Fatty acids are formed that do not have specific
cops for their destruction (action peroxidase is insignificant)
Antioxidants are oppressed
In carbohydrates:
Polysaccharides break up to simple sugars
Irradiation of simple sugars leads to their oxidation and decay to the organization
nichetic acids and formaldehyde
Heparin loses its anticoagulant properties
Hyaluronic acid loses the ability to connect with a protein
The level of glycogen is reduced
Anaobic glycolysis processes are violated
The content of glycogen in muscles and liver decreases.
In the enzyme system disrupts oxidative phosphorylation and
the activity of a number of enzymes changes, the reactions of chemically active
substances with different biological structures in which
both destruction and the formation of new, not characteristic of irradiation
organism, connections.
Subsequent stages of development of radiation damage are associated with violation
metabolism in biological systems with changes in relevant
4. Biological stage or fate of the irradiated cell
So, the effect of radiation is associated with changes occurring,
in both cell organelles and relationships between them.
The most sensitive to irradiation of organism cells
mammals are core and mitochondria. Damage to these structures
they occur at small doses and in the earliest time. In the kernels of the radio
energy processes are oppressed by energy processes, the function is disturbed
membranes. Proteins are formed, lost their normal biological act
tivty. More pronounced radiosensitivity than the kernels possess
torhondria. These changes are manifested in the form of swelling mitochondria,
the fluctuations of their membranes, sharp inhibition of oxidative phosphorylation.
Radio sensitivity of cells largely depends on speed
exchange processes occurring in them. Cells for which are characteristic of
consistent biosynthetic processes, high levels of oxidized
phosphorylation and significant growth rate, possess more
juice with radiosensitivity than cells staying in the stationary phase.
The most biologically significant in an irradiated cell is
dNA: DNA chains breaks, chemical modification of purine and
pyrimidine bases, their separation from the DNA chain, the destruction of phosphoether
bonds in the macromolecule, damage to the DNA membrane complex, destroy
relations of DNA protein and many other disorders.
In all dividing cells, immediately after irradiation temporarily stops
mitotic activity ("Mitoz radiation block"). Violation of meta
bolic processes in the cell leads to an increase in the severity of molecu
large damage in the cell. This phenomenon was called biological
strengthening of primary radiation damage. However, along with
this, the cage develops and reparation processes, consequences of which
it is a complete or partial restoration of structures and functions.
The most sensitive to ionizing radiation are:
lymphatic fabric, bone marrow of flat bones, sex glands, less than
superior: connecting, muscular, cartilage, bone and nervous fabric.
Cell death can occur both in the reproductive phase directly
it is also associated with the division process and in any phase of the cell cycle.
More sensitive to the ionizing radiation of newborns (WVI-
do high mitotic cell activity), old men (deteriorates
cells to recovery) and pregnant women. The sensitivity of K.
ionizing radiation and when introducing some chemical compounds
(so-called radio networks).
Biological effect depends:
From the type of irradiation
From the absorbed dose
From dose distribution in time
From the specifics of the irradiated organ
The most dangerous irradiation of the crypt of the small intestine, the seeds,
brain of flat bones, abdominal areas and irradiation of the whole organism.
Unicellular organisms are about 200 times less sensitive to
the action of radiation than multicellular.
4. Natural and man-made sources of ionizing radiation.
Sources of ionizing radiation are natural and art
origin.
Natural radiation is due to:
1. cosmic radiation (protons, alpha particles, lithium cores, beryllium,
carbon, oxygen, nitrogen are primary cosmic radiation.
The atmosphere of the Earth absorbs primary cosmic radiation, then
secondary radiation presented by protons, neutrons,
electrons, mesons and photons).
2. The radiation of the radioactive elements of the Earth (uranium, thorium, actinium,
diy, Radon, Toron), water, air, building materials of residential buildings,
radon and radioactive carbon (C-14) present in the inhale
3. The radiation of the radioactive elements contained in the animal world
and human body (K-40, uranium -238, thorium -232 and radium -228 and 226).
Note: Starting with polonium (№84), all elements are radio
tive and capable of spontaneous division of nuclei when capturing their kernel
mi slow neutrons (natural radioactivity). However, natural
radioactivity is also found in some light elements (isotopes
rubidia, Samaria, Lantana, Rhenium).
5. Dettered and stochastic clinical effects that occur in a person when exposed to ionizing radiation.
The most important biological responses of the human body for action
ionizing radiation is divided into two types of biological effects
1. Deterministic (causally determined) biological effects
you, for which there is a threshold dose of action. Below a disease threshold
does not appear, but when a certain threshold is reached, diseases occur
no, directly proportionally dependent on the dose: radial burns, radial
dermatitis, radiation cataract, radiation fever, radiation infertility, ano
malia of fetal development, acute and chronic radiation disease.
2. Stochastic (probabilistic) biological effects do not have
ha actions. May occur at any dose. The effect is characterized for them.
small doses and even one cell (the cell becomes cancer if it is irradiated
in mitosis): leukemia, oncological diseases, hereditary diseases.
By time of occurrence, all effects are divided into:
1. Immediate - may arise within a week, month. This is acute
and chronic radiation disease, skin burns, ray cataract ...
2. Remotsed - Individuals arising during life: Oncological
diseases, leukemia.
3. arising after an indefinite time: genetic consequences -
meaning of hereditary structures: genomic mutations - multiple changes
haploid number chromosome, chromosomal mutations or chromosomal
aberration - structural and numerical changes in chromosomes, spokes (gene
mutations: changes in the molecular structure of genes.
Corpuscular radiation - fast neutrons and alpha particles, called
chromosomal restructuring more often than electromagnetic radiation .__
6. Radioxicity and radioogenetics.
Radiotoxicity
As a result of radiation disorders of metabolic processes in the body
radioxins accumulate - these are chemical compounds that play
a certain role in the pathogenesis of radial lesions.
Radioxicity depends on a number of factors:
1. The type of radioactive transformations: alpha radiation is 20 times toxic than
ta radiation.
2. The average energy of the decay act: Energy R-32 C-14.
3. Radioactive decay schemes: isotope is more toxic if it comes
new radioactive substance.
4. Track paths: Arrival through the gastrointestinal tract in 300
once it is more toxic than the receipt through intact skin.
5. Stay time in the body: more toxicity with significant
half-life and low half-lived speed.
6. Distributions by organs and tissues and specifics of the irradiated organ:
osteotropic, hepatotropic and uniformly distributed isotopes.
7. The duration of the receipt of isotopes into the body: random pumped
radioactive substance can be completed safely, with chronic
the accumulation of the hazardous amount of radiation is possible
tel.
7. Acute radiation disease. Prevention.
Melnichenko - p. 172
8. Chronic radiation disease. Prevention.
Melnichenko p. 173
9. The use of sources of ionizing radiation in medicine (the concept of closed and open sources of radiation).
Sources of ionizing radiation are divided into closed and
indoor. Depending on this classification, differently interpreted and
ways to protect against emission data.
Closed sources
Their device eliminates radioactive substances in the surrounding
wednesday under conditions of use and wear. It can be needles, sealed
in steel containers, tele-gamma installations for irradiation, ampoules, beads,
sources of continuous radiation and generating radiation periodically.
Radiation from closed sources is only external.
Protection Principles when working with closed sources
1. Protection by quantity (reduction of dose power in the workplace -
less dose, the less irradiation. However, the technology of manipulation is not
always reduces dose power to minimal value).
2. Time protection (reduce contact time with ionizing radiation
we can achieve workout without emitter).
3. distance (remote control).
4. Screens (Luggage and Transport Container Screens
native preparations in a non-working position, for equipment, movement
- Shirms in X-ray cabinets, parts of building structures
to protect the territories - walls, doors, individual means of protection -
t-shields from org.teklla, candidated gloves).
Alpha and beta radiation is delayed by hydrogen-containing
(plastics) and aluminum, gamma radiation is weakened by materials
with high density - lead, steel, cast iron.
To absorb neutrons, the screen should have three layers:
1. Layer - for slowing neutrons - materials with a large number of atoms
mOU Hydrogen - Water, Paraffin, Plastics and Concrete
2. Layer - to absorb slow and thermal neutrons - Bor, cadmium
3. Layer - for the absorption of gamma radiation - lead.
To evaluate the protective properties of a material, its ability
to delay the ionizing radiation use the half-layer layer
attenuation denoting the thickness of the layer of this material after passing
the yield of the intensity of gamma radiation decreases twice.
Open sources of radioactive radiation
Open source is the source of radiation, when using which
it is possible to enter radioactive substances into the environment. For
this is not excluded not only external, but also internal irradiation of personnel
(gases, aerosols, solid and liquid radioactive substances, radioactive
isotopes).
All work with open isotopes are divided into three classes. Class
bot is established depending on the radioactive radioactivity group
heotope (a, b, in, g) and the actual amount of its number (activity) on the working
place.
10. Ways to protect a person from ionizing radiation. Radiation security of the population of the Russian Federation. Radiation safety standards (NRB-2009).
Ways to protect against open sources of ionizing radiation
1. Organizational measures: the allocation of three classes of work depending on
sTI from danger.
2. Planning activities. For the first class of danger - specially
insulated housings, where strangers are not allowed. For second
the class is allocated only the floor or part of the building. Third-class works
can be carried out in a conventional laboratory with the presence of an exhaust cabinet.
3. Sealing equipment.
4. The use of non-conforming materials for tables and walls,
device of rational ventilation.
5. Individual means of protection: Clothes, shoes, insulating suits,
protection of respiratory organs.
6. Compliance with radiation asepsis: bathrobes, gloves, personal hygiene.
7. Radiation and medical control.
To ensure human safety in all conditions of impact on
his ionizing radiation of artificial or natural origin
radiation safety rates apply.
The following categories of irradiated faces are established in the rules:
Personnel (group A - persons constantly working with sources of ionics
ziruppy radiation and group b - limited part of the population, which foreign
gda can be exposed to ionizing radiation - cleaners,
fixtures, etc.)
The whole population, including persons from personnel, beyond the sphere and conditions of their
water activities.
The main doses limits for group B personnel are equal to ¼ values \u200b\u200bfor
staff of group A. Effective dose for staff should not exceed
period of labor activities (50 years) 1000 mSv, and for the period
life (70 years) - 70 mW.
The planned exposure of the staff of the group A above the established
cases when eliminating or preventing an accident can be allowed
only in case of the need to save people or prevent their inconsistencies
. Allowed for men over 30 years old when they are voluntary writing
mr. consent, informing about possible doses of irradiation and risk for
rova. In emergency situations, irradiation should not be more than 50 msv .__
11. Possible causes of emergency situations on radiation and dangerous facilities.
Classification of radiation accidents
Accidents associated with the violation of the normal operation of the ROO are divided into design and projections.
The project accident is an accident for which the project identifies the source events and end states, in connection with which the security systems are provided.
Project accident - is invoked not taken into account for project accidents, initial events and leads to severe consequences. At the same time, the yield of radioactive products in quantities leading to radioactive contamination of the adjacent territory, the possible irradiation of the population above established norms. In severe cases, thermal and nuclear explosions may occur.
Depending on the boundaries of the zones of radioactive substances and radiation consequences, potential accidents at nuclear power plants are divided into six types: local, local, territorial, regional, federal, transboundary.
If, with a regional accident, the number of people who received the dose of irradiation above the levels set for normal operation may exceed 500 people, or the number of people who can have violated the conditions of life, will exceed 1,000 people, or material damage will exceed 5 million minimum payment sizes Labor, such an accident will be federal.
With transboundary accidents, the radiation consequences of the accident overlook the territory of the Russian Federation, or this accident occurred abroad and affects the territory of the Russian Federation.
12. Sanitary and hygienic measures in emergency situations on radiation and dangerous facilities.
Events, methods and means of protecting the population from radiation impact under the radiation accident include:
detection of the fact of the radiation accident and notification of it;
identifying the radiation situation in the accident area;
organization of radiation control;
establishing and maintaining radiation safety regime;
when necessary at the early stage of the accident of the iodine prevention of the population, emergency personnel and participants in the elimination of the consequences of the accident;
ensuring the population, personnel, participants in the elimination of the consequences of the accident with the necessary means of individual protection and the use of these funds;
the shelter of the population in shelters and anti-radiation covers;
sanitary treatment;
deactivation of an emergency object, other objects, technical means, etc.;
evacuation or discontinuation of the population from zones in which the level of pollution or dose of irradiation exceeds permissible for the residence of the population.
The identification of the radiation situation is carried out to determine the scale of the accident, the establishment of the size of the radioactive contamination zones, the dose rate and the level of radioactive contamination in the zones of optimal routes of movement of people, transport, as well as the determination of possible routes for the evacuation of the population and farm animals.
Radiation control under the conditions of the radiation accident is carried out in order to comply with the permissible time of people's stay in the accident area, controlling doses of irradiation and levels of radioactive pollution.
Radiation safety regime is ensured by the establishment of a special order of access to the accident area, zoning the area of \u200b\u200bthe accident; Conducting emergency rescue work, the implementation of radiation control in zones and at the exit to the "clean" zone and others.
The use of personal protective equipment is to apply insulating skin protection tools (protective kits), as well as tools for protecting the respiratory and vision organs (lifting gauze bandages, various types of respirators, filtering and insulating gas masks, safety glasses, etc.). They protect a person mainly from internal irradiation.
To protect the thyroid gland of adults and children from the effects of radioactive isotopes, iodine at an early stage of the accident is carried out by iodine prevention. It lies in the reception of a stable iodine, mainly a potassium iodide, which is taken in tablets in the following doses: children from two years and older, as well as adults at 0.125 g, to two years to 0.04 g., Reception inside after meals together with Kisel, tea, water 1 time per day for 7 days. The iodine water-alcohol solution (5% iodine tincture) is shown to children from two years and older, as well as adults for 3-5 drops on a glass of milk or water for 7 days. Children under two years are given 1-2 drops per 100 ml of milk or nutrient mixture for 7 days.
The maximum protective effect (reduced dose of irradiation is approximately 100 times) is achieved with a preliminary and simultaneous receipt of the radioactive iodine to receive its stable analog. The protective effect of the drug is significantly reduced at its reception more than two hours after the start of irradiation. However, in this case, effective protection against irradiation occurs during repeated receipts of radioactive iodine.
The protection against external irradiation can only be ensured by protective structures that should be equipped with iodine radionuclide filters. Temporary coverage of the population before evacuation can provide practically any sealed premises.
A person is exposed to ionizing radiation everywhere. For this, it is not necessary to fall into the epicenter of the nuclear explosion, it is enough to be under the scorching sun or carry out an x-ray study of the lungs.
The ionizing radiation is the flow of radiation energy formed in the reaction of the decay of radioactive substances. Isotopes that can increase the radiation fund are in the earth's crust, in the air, a man of radionuclides can fall into the body through the gastrointestinal tract, the respiratory system and skin.
Minimum rates of radiation background do not pose a threat to humans. A different thing is, if the ionizing radiation exceeds the permissible norms. The body will not instantly respond to harmful rays, but after years, pathological changes will appear, which can lead to deposits, up to death.
What is ionizing radiation?
The release of harmful radiation is obtained after the chemical decay of radioactive elements. The most common are gamma, beta and alpha-luchi. Finding into the body, radiation devoid affecting a person. All biochemical processes are broken, being influenced by ionization.
Radiation types:
- The layers of the alpha type have increased ionization, but a meager penetrating ability. Alpha radiation hits the skin of a person, embedded at a distance of less than one millimeter. It is a bunch of elevated helium nuclei.
- Electrons or positrons are moving in beta-rays, they are able to overcome the distance to several meters in the air flow. If a person appears near the source, the beta radiation will penetrate deeper than alpha, but the ionizing abilities of this species are much less.
- One of the highest frequency electromagnetic emissions is a type of gamma-, which has an increased penetration ability, but a very small ionizing effect.
- It is characterized by short electromagnetic waves, which occur when the beta rays with substance occurs.
- Neutron - high-dimensional beams rays consisting of uncharged particles.
Where does the radiation come from?
Air, water and food products can be sources of ionizing radiation. Malicious rays are found in nature or are created artificially for medical or industrial purposes. In the environment there is always radiation:
- it comes from the space and is most of the total percentage of radiation;
- radiation isotopes are freely in the usual natural conditions, are contained in rocks;
- radionuclides are in the body with food or air.
Artificial radiation was created under developing science, scientists were able to open the uniqueness of X-rays, with the help of which the exact diagnosis of many dangerous pathologies is possible, including infectious diseases.
On an industrial scale, ionizing radiation is used in diagnostic purposes. People working at similar enterprises, despite all security measures applied by sanitary requirements, are in harmful and hazardous working conditions adversely affecting health.
What happens to a person with ionizing radiation?
The destructive effect of ionizing radiation on the human body is explained by the ability of radioactive ions to react with cell components. It is well known that a person is eighty percent consists of water. During irradiation, water decomposes in cells as a result of chemical reactions, hydrogen peroxide and hydrate oxide is formed.
In the future, there is oxidation in organic compounds of the body, as a result of which the cells begin to collapse. After pathological interaction, a person violates metabolism at the cellular level. The consequences can be reversible when contact with radiation was insignificant, and irreversible during long-term exposure.
The effect on the body can manifest itself in the form of radiation sickness when all organs are amazed, radioactive rays can cause gene mutations, which are inherited in the form of ugliness or severe diseases. There are often cases of rebirth of healthy cells into cancer, followed by the growth of malignant tumors.
The consequences may not appear immediately after interaction with ionizing radiation, but after dozens of years. The duration of asymptomatic flow directly depends on the degree and time during which the person received radioactive irradiation.
Biological changes at rays
The effect of ionizing radiation implies significant changes in the body, depending on the extensity of the area of \u200b\u200bthe skin subjected to the introduction of radiation energy, the time during which the radiation remains active, as well as the state of organs and systems.
To designate the power of radiation for a certain period of time, the unit of measurement is considered to be happy. Depending on the magnitude of the missed rays, the following states may develop in humans:
- up to 25 is happy - overall health does not change, a person feels good;
- 26 - 49 Run - the state is generally satisfactory, with such a dosage, blood begins to change its composition;
- 50 - 99 Rad - the victim begins to feel overeating, fatigue, poor mood, pathological changes appear in the blood;
- 100-199 Rad - irradiated is in poor condition, most often a person cannot work due to deteriorating health;
- 200 - 399 Rad - a large dose of radiation, which develops multiple complications, and sometimes leads to a fatal outcome;
- 400 - 499 Rad - half of people who came to the zone with such radiation values \u200b\u200bare dying from rescued pathologies;
- exposure of more than 600 glad does not give a chance for a prosperous outcome, mortal illness takes away the lives of all victims;
- one-time receipt of the radiation dose, which thousands of times more permissible digits - die all directly during the catastrophe.
The age of man plays a big role: the most susceptible to the negative influence of ionizing energy children and young people who have not reached the twenty-five-year-old age. Getting large doses of radiation during pregnancy can be compared with irradiation in early childhood.
The pathology of the brain arise only, starting from the middle of the first trimester, from the eighth week to twenty-sixth inclusive. The risk of cancer formations in the fetus increases significantly with an unfavorable radiation background.
What threatens to enter the influence of ionizing rays?
One-time or regular radiation falling into the body has a property to accumulate and subsequent reactions after a certain period of time from several months to decades:
- the inability to conceive a child, this complication develops both in women and the male half, making them sterile;
- the development of autoimmune diseases of unexplained etiology, in particular sclerosis;
- radiation cataract leading to loss of vision;
- the appearance of cancerous tumor is one of the most frequent pathologies with the modification of tissues;
- immune diseases that violate the usual work of all organs and systems;
- a man who is exposed to radiation lives much less;
- the development of mutating genes that will cause serious defects in development, as well as the emergence of abnormal deformities during the development of the fetus.
Remote manifestations can develop directly at the irradiated individual or to inherit and occur at subsequent generations. Directly in the patient, through which the rays passed, there are changes in which the tissues are atrophy and are compacted with the advent of multiple character nodules.
This symptom can affect skin, light, blood vessels, kidneys, liver cells, cartilage and connective tissue. Cell groups become inelastic, roast and lose the ability to perform their purpose in the human body with radiation disease.
Radiation sickness
One of the most terrible complications, the different stages of the development of which are capable of leading the death of the victim. The disease may have an acute course of lump-sum irradiation or a chronic process with constant finding in the radiation zone. Pathology is characterized by a resistant change in all organs and cells and the accumulation of pathological energy in the patient's body.
There is a notch of the following symptoms:
- general intoxication of the body with vomiting, diarrhea and elevated body temperature;
- from the side of the cardiovascular system, the development of hypotension is noted;
- man quickly gets tired, possibly the occurrence of collapse;
- with large doses of exposure, the skin blues and covered with blue stains in areas that lack the supply of oxygen, the muscle tone is reduced;
- the second wave of symptoms is the total loss of hair, deterioration of well-being, consciousness remains slowed, there is a common nervousness, aphony of muscle tissue, disorders in the brain, capable of lumbness of consciousness and brain swelling.
How to protect yourself from irradiation?
The determination of effective protection against harmful rays is the basis of the prevention of human defeat in order to avoid the emergence of negative consequences. To escape from irradiation you need:
- Reduce the exposure time of the decay elements of isotopes: a person should not be in the danger zone for a long period. For example, if a person works in harmful production, the worker's stay at the energy flow should be reduced to a minimum.
- Increase the distance from the source, it is possible when using multiple tools and automation tools that allow you to perform work at a considerable distance from external sources with ionizing energy.
- Reduce the area on which rays will fall, it is necessary using protective equipment: suits, respirators.
Ionizing radiation, their nature and the impact on the human body
Radiation and its varieties
Ionizing radiation
Sources of radiation danger
Device of ionizing radiation sources
Ways of penetration of radiation in the human body
Measures of ionizing impact
Mechanism of action of ionizing radiation
The effects of irradiation
Radiation sickness
Ensuring security when working with ionizing radiation
Radiation and its varieties
Radiation is all types of electromagnetic radiation: light, radio wave, sun energy and a lot of other radiation around us.
Sources of penetrating radiation that create a natural irradiation background are galactic and solar radiation, the presence of radioactive elements in the soil, air and materials used in economic activity, as well as isotopes, mainly potassium, in the tissues of a living organism. One of the most significant natural sources of radiation is radon - gas that does not have taste and smell.
Of interest is not any radiation, but an ionizing, which, passing through the tissues and cells of living organisms, is able to transmit their energy to them, breaking chemical bonds inside the molecules and causing serious changes in their structure. Ionizing radiation occurs during radioactive decay, nuclear transformations, inhibition of charged particles in the substance and forms when interacting with the Ion environments of different characters.
Ionizing radiation
All ionizing radiation are divided into photon and corpuscular.
Photon ionizing radiation include:
a) Y-radiation emitted when the decay of radioactive isotopes or annihilation of particles. Gamma radiation by nature is short-wave electromagnetic radiation, i.e. The stream of high-energy quanta electromagnetic energy, the wavelength of which is significantly less than interatomic distances, i.e. y.< 10 см. Не имея массы, Y-кванты двигаются со скоростью света, не теряя её в окружающей среде. Они могут лишь поглощаться ею или отклоняться в сторону, порождая пары ионов: частица- античастица, причём последнее наиболее значительно при поглощении Y- квантов в среде. Таким образом, Y- кванты при прохождении через вещество передают энергию электронам и, следовательно, вызывают ионизацию среды. Благодаря отсутствию массы, Y- кванты обладают большой проникающей способностью (до 4- 5 км в воздушной среде);
b) X-ray radiation that occurs with a decrease in the kinetic energy of charged particles and / or with a change in the energy state of an atom electrons.
The corpuscular ionizing radiation consists of a flow of charged particles (alpha, beta particles, protons, electrons), the kinetic energy of which is sufficient to ionize atoms in a collision. Neutrons and other elementary particles directly do not produce ionization, but in the process of interaction with the medium, charged particles are released (electrons, protons) capable of ionizing atoms and molecules of the medium through which they pass:
a) Neutrons are the only uncharged particles formed under certain fission reactions of the nuclei of uranium atoms or plutonium. Since these particles are electronic, they deeply penetrate into any substance, including live fabrics. A distinctive feature of neutron radiation is its ability to convert the atoms of stable elements into their radioactive isotopes, i.e. Create induced radiation, which dramatically increases the risk of neutron radiation. The penetrating ability of neutrons is comparable to Y radiation. Depending on the level of wearable energy, neutrons are conditionally distinguished by neutrons (having energy from 0.2 to 20 ME B) and thermal (from 0.25 to 0.5 ME B). This difference is taken into account when conducting protective events. Fast neutrons slow down, losing ionization energy, substances with low atomic weight (so-called hydrogen-containing: paraffin, water, plastics, etc.). Thermal neutrons are absorbed by materials containing boron and cadmium (boric steel, boroel, boric graphite, cadmium alloy with lead).
Alpha -, beta particles and gamma - quanta possess the energy of just a few megaelectrone, and cannot be created by induced radiation;
b) beta particles - electrons emitted during the radioactive decay of nuclear elements with intermediate ionizing and penetrating ability (mileage in the air to 10-20 m).
c) Alpha particles are positively charged kernels of helium atoms, and in the outer space and atoms of other elements emitted during the radioactive decay of the isotopes of heavy elements - uranium or radium. They have a small penetrating ability (mileage in the air - no more than 10 cm), even human skin is an irresistible obstacle. They are dangerous only when entering the body, since they are able to knock electrons from the shell of a neutral atom of any substance, including the human body, and turn it into a positively charged ion with all the ensuing the consequences of which will be mentioned below. So, alpha particle with energy 5 MeV forms 150,000 pairs of ions.
Characteristics of the penetrating capacity of various types of ionizing radiation
The quantitative content of radioactive material in the human body or substance is determined by the term "radioactive source activity" (radioactivity). For the unit of radioactivity in the SI system, Becquer (BC) is adopted, corresponding to one decay in 1 seconds. Sometimes in practice the old activity unit is used - Curie (CI). This activity of such a number of substance in which the decay of 37 billion atoms occurs for 1C. For translation, dependence is used: 1 BC \u003d 2.7 x 10 ki or 1 ki \u003d 3.7 x 10 BC.
Each radionuclide has a constant, inherent half-life (the time required for the losses of the agent of half of activity). For example, uranium-235 is 4,470, while iodine-131 is only 8 days.
Sources of radiation danger
1. The main cause of danger is a radiation accident. Radiation accident - loss of control of the source of ionizing radiation (III) caused by the malfunction of equipment, incorrect actions of personnel, natural disasters or other reasons that could lead or led to the irradiation of people above established norms or radioactive environmental pollution. In case of accidents caused by the destruction of the reactor housing or the melting of the active zone are thrown:
1) fragments of the active zone;
2) fuel (waste) in the form of highly active dust, which can be in the air in the form of aerosols for a long time, then after passing the main cloud, fall out in the form of raindrops (snow) precipitation, and when entering the body, cause a painful cough, sometimes in gravity Asthma attack;
3) lava consisting of silicon dioxide, as well as molten as a result of contact with hot fuel concrete. The dose rate near these Love reaches 8000 p / h and even a five-minute stay next is destructive for humans. In the first period, after falling out of precipitation, the RV is the greatest danger of the iodine-131, which is the source of alpha and beta radiation. Periods of half-life from the thyroid gland are: biological - 120 days, effective - 7.6. This requires the fastest iodine prevention of the entire population in the accident zone.
2. Enterprises for the development of deposits and uranium enrichment. Uranium has atomic weight 92 and three natural isotopes: uranium-238 (99.3%), uranium-235 (0.69%) and uranium-234 (0.01%). All isotopes are alpha emitters with minor radioactivity (2800kg of uranium in activity are equivalent to 1 g radium-226). The half-life of uranium-235 \u003d 7.13 x 10 years. Artificial isotopes uranium-233 and uranium-227 have a half-life of 1.3 and 1.9 min. Uranium - soft metal, in appearance similar to steel. The content of uranium in some natural materials reaches 60%, but in most uranium ores it does not exceed 0.05-0.5%. In the process of production, upon receipt of 1 ton of radioactive material, up to 10-15 thousand tons of waste is formed, and when processing from 10 to 100 thousand tons. From waste (containing a slight amount of uranium, radium, thorium and other radioactive decay products) is allocated radioactive gas - radon-222, which, when inhaling, causes irradiation of the tissues of lungs. When improving ore, radioactive waste can get into nearby rivers and lakes. When enriching the uranium concentrate, there is some leakage of gaseous hexafluoride uranium from a condensation and evaporative installation to the atmosphere. Some uranium alloys, chips obtained by the fuel elements obtained in the production of the fuel elements can be ignited during transport or storage, as a result, significant amounts of burnt uranium waste can be thrown into the environment.
3. Nuclear terrorism. Cases of theft of nuclear materials suitable for the manufacture of nuclear ammunition even with handicraft, as well as threats to the conclusion of nuclear enterprises, ships with nuclear facilities and nuclear power plants in order to obtain a ransom. The danger of nuclear terrorism exists on the household level.
4. Tests of nuclear weapons. Recently, miniaturization of nuclear charges for testing has been reached.
Device of ionizing radiation sources
On the II device there are two types - closed and open.
Closed sources are placed in sealed containers and are danger only in the absence of proper control over their exploitation and storage. Military units, transmitting written off devices in prudent educational institutions, contribute their contribution. Listented, destruction as unnecessary, theft with subsequent migration. For example, in Bratsk at the building construction plant, the III, enclosed in the lead shell, was kept in a safe along with precious metals. And when the robbers hacked the safe, they decided that this massive lead brave was also precious. They stole it, and then honestly divided, sawing in half a lead "shirt" and sharpened in it an ampoule with a radioactive isotope.
Work with open IIIs can lead to tragic consequences with ignorance or violation of the relevant instructions on the rules for handling data sources. Therefore, before starting any work using III, it is necessary to carefully examine all job descriptions and safety regulations and strictly fulfill their requirements. These claims are set forth in the "Sanitary Rules for Radioactive Waste Management (SPO-85)". Radon company on requests produces individual control of persons, territories, objects, checks, dosage and repair of instruments. Work in the field of appeal of III, radiation protection, production, production, transportation, storage, use, maintenance, disposal, disposal is made only on the basis of a license.
Ways of penetration of radiation in the human body
In order to correctly understand the mechanism of radiation lesions, it is necessary to have a clear idea of \u200b\u200bthe existence of two paths, for which radiation penetrates into the body's tissue and affects them.
The first way is external irradiation from the source located outside the body (in the surrounding space). This irradiation can be associated with X-ray and gamma rays, as well as some high-energy beta particles capable of penetrating into surface layers of the skin.
The second way is the internal irradiation caused by the ingress of radioactive substances into the body in the following ways:
In the first days after the radiation accident, the radioactive isotopes of iodine entering the body with food and water are most dangerous. Very much of them in milk, which is especially dangerous for children. Radioactive iodine accumulates mainly in the thyroid gland, the mass of which is only 20 g. The concentration of radionuclides in this authority can be 200 times higher than in other parts of the human body;
Through damage and cuts on the skin;
Absorption through healthy skin with long-term exposure of radioactive substances (PB). In the presence of organic solvents (ether, benzene, toluene, alcohol), the permeability of the skin for RV increases. Moreover, some RV, which entered the body through the skin, fall into the bloodstream and, depending on their chemical properties, are absorbed and accumulated in critical organs, which leads to high local doses of radiation. For example, the growing bones of the limbs are well absorbed by radioactive calcium, strontium, radium, kidney - uranium. Other chemical elements, such as sodium and potassium, will spread all over the body more or less evenly, as they are contained in all cells of the body. In this case, the presence of sodium-24 in the blood means that the body was further subjected to neutron irradiation (that is, the chain reaction in the reactor at the time of irradiation was not interrupted). Treat the patient subjected to neutron irradiation is especially difficult, therefore it is necessary to determine the influence of the body's bio-elements (p, si etc.);
Through lungs when breathing. The ingress of solid radioactive substances into lungs depends on the degree of dispersion of these particles. From the tests carried out above animals, it is established that dust particles of less than 0.1 microns behave as well as the gases molecules. When inhaling, they fall with air into the lungs, and when exhaling, along with air are removed. In the lungs, only a minor part of solid particles can remain. Large particles of more than 5 microns are delayed with a nasal cavity. Inert radioactive gases (argon, xenon, krypton, etc.), which have fallen through the light into the blood, are not compounds that are part of the tissue, and over time are removed from the body. Do not delay in the body for a long time and radionuclides, the same type with elements included in the composition of tissues and a person used with food (sodium, chlorine, potassium, etc.). Over time, they are completely removed from the body. Some radionuclides (for example, deposited in bone tissues, uranium, plutonium, strontium, yttrium, zirconium) enter the chemical bond with bone elements and are difficult to derive from the body. When conducting a medical examination of residents of areas affected by the accident at the Chernobyl NPP, in the All-Union Hematology Center of AMN, it was found that with the overall irradiation of the body, the dose of 50 is glad of its separate cells turned out to be irradiated with a dose of 1,000 and more glad. Currently, for various critical authorities, standards have been developed that determine the maximum permissible content of each radionuclide in them. These norms are set forth in section 8 "numerical values \u200b\u200bof permissible levels" NRB radiation safety standards - 76/87.
Internal exposure is more dangerous, and its consequences are more severe for the following reasons:
The dose of radiation, determined by the time of stay of the radionuclide in the body (Radium-226 or Plutonium-239 throughout the life);
Almost infinitely little distance to ionized tissue (the so-called, contact irradiation);
Alpha particles are involved in irradiation, the most active and therefore the most dangerous;
Radioactive substances are propagated by uniformly throughout the body, but selectively concentrated in separate (critical) organs, reinforcing local irradiation;
It is impossible to use any protection measures used with external irradiation: evacuation, personal protective equipment (PPE), etc.
Measures of ionizing impact
Measure of ionizing exposure to external radiation is exposure dose Defined for air ionization. For a unit of exposure dose (DE), the X-ray (P) is considered - the amount of radiation in which in 1 cc. Air at a temperature of 0 C and a pressure of 1 atm, 2.08 x 10 pairs of ions are formed. According to the leading documents of the international company on radiological units (worship) of the RD - 50-454-84 after January 1, 1990, it is not recommended to use such values \u200b\u200bas an exposure dose and its capacity in our country (it is assumed that the exposure dose is absorbed in the dose air). Most of the dosimetric equipment in the Russian Federation has a calibration in X-ray, X-ray / clock, and from these units are not yet refused.
The measure of the ionizing effect of internal irradiation is absorbed dose. For the unit of absorbed dose adopted happy. This is the dose of radiation, transmitted by the mass of the irradiated substance in 1 kg and the measurable energy in the Joules of any ionizing radiation. 1 Rad \u003d 10 J / kg. In the system system of the absorbed dose is Gray (GR), equal to energy in 1 J / kg.
1 grade \u003d 100 happy.
1 Rad \u003d 10 gr.
To transfer the amount of ionizing energy in the space (exposure dose) into the organism absorbed by soft tissues, the proportionality coefficient K \u003d 0.877 is used, i.e.:
1 X-ray \u003d 0.877 Rad.
Due to the fact that various types of radiation have different efficiency (with equal energy costs, various impacts are made to ionization), the concept of an "equivalent dose" is introduced. The unit of its measurement is BER. 1 BER is the dose of radiation of any kind, the impact of which on the body is equivalent to the action of 1 glasses of radiation gamma. Therefore, when evaluating the overall effect of radiation radiation radiation on living organisms in total irradiation with all types of radiation, the quality coefficient (q), equal to the neutron radiation (neutron, is about 10 times more efficient in the radiation lesion plan) and 20 for alpha radiation. In the system, the unit of an equivalent dose is the ziver (ZV) equal to 1 grade x Q.
Along with the amount of energy, the type of irradiation, material and mass of the body is an important factor is the so-called biological half-life Radioisotope is the duration of the time required for the removal (with then, saliva, urine, kaloma, etc.) from the body of half of the radioactive substance. After 1-2 hours after the RV hit the body, they are found in its discharge. The combination of the physical period of a half-life with biological gives the concept of "effective half-life" - the most important in determining the resulting irradiation, which is subject to the body, especially critical organs.
Along with the concept of "activity" there is the concept of "induced activity" (artificial radioactivity). It occurs when absorbed slow neutrons (nuclear explosion or nuclear reaction products), nuclei of neradoactive substances atoms and turning them into radioactive potassium-28 and sodium-24, which are mostly generated in the ground.
Thus, the degree, depth and form of radiation lesions developing in biological objects (including in humans) when exposed to radiation, depend on the magnitude of the absorbed radiation energy (dose).
Mechanism of action of ionizing radiation
The principal feature of the action of ionizing radiation is its ability to penetrate into biological tissues, cells, subcellular structures, and, causing one-time ionization of atoms, due to chemical reactions to damage them. An ionized can be any molecule, and all the structural and functional destruction in somatic cells, genetic mutations, the impact on the embryo, the disease and death of a person.
The mechanism of such an effect consists in absorbing the energy of ionization by the body and the breaking of the chemical bonds of its molecules to form highly active compounds, the so-called free radicals.
The human body is 75% consists of water, therefore, a crucial importance in this case will have an indirect effect of radiation through the ionization of water molecule and subsequent reactions with free radicals. When the ionization of the water molecules, a positive ion of N O and an electron is formed, which, having lost energy, can form a negative ion n O. Both of these ions are unstable and disintegrate to a pair of stable ions, which are recombined (restored) to form a water molecule and two free radicals. and N, differing exceptionally high chemical activity. Directly or through a chain of secondary transformations, such as the formation of a peroxide radical (hydrate water oxide), and then hydrogen peroxide N O and other active oxidizing agents of the group it and H, interacting with protein molecules, they lead to the destruction of the tissue mainly due to energetically occurring processes Oxidation. In this case, one active molecule with high energy involves thousands of living matter molecules into the reaction. In the body, oxidative reactions begin to prevail over restorative. There is a payroll for the aerobic method of bioenergy - the saturation of the body with free oxygen.
The effect of ionizing radiation per person is not limited to a change in the structure of water molecules. The structure of atoms changes, of which our body consists. As a result, the core destruction, cellular organelle and the rupture of the outer membrane occur. Since the main function of growing cells is the ability to divide, it leads to death. For mature nonsense cells, destruction causes the loss of those or other specialized functions (the production of certain products, recognition of alien cells, transport functions, etc.). There is a radiation-induced cell death, which, unlike the physiological death of irreversible, since the implementation of the genetic program of terminal differentiation in this case is carried out against the background of multiple changes in the normal flow of biochemical processes after irradiation.
In addition, the additional intake of ionization energy into the body violates the balance of energy processes occurring in it. After all, the presence of energy in organic substances depends primarily not on their elementary composition, but on the structure, location and nature of the bonds of atoms, i.e. those elements that are easiest to be energy exposed to energy.
The effects of irradiation
One of the earliest manifestations of irradiation is the mass death of lymphoid tissue cells. Figuratively speaking, these cells are the first to hit radiation. The death of lymphoids weakens one of the main livelihood systems of the body - the immune system, since lymphocytes - such cells that are able to respond to the appearance of foreign antigens to the body of strictly specific antibodies to them.
As a result of the effect of radiation radiation energy in small doses in cells, changes in genetic material (mutations), threatening their viability, occur. As a result, degradation (damage) of chromatin DNA (ruptures of molecules, damage) occurs, which are partially or completely blocked or perverted genome function. There is a violation of DNA reparation - the ability to restore and heal the damage to the cells with increasing body temperature, the effects of chemicals, etc.
Genetic mutations in the genital cells affect the life and development of future generations. This case is characteristic, for example, if a person has been influenced by small doses of radiation during the exposition for medical purposes. There is a concept - upon receipt of a dose of 1 bars by the previous generation, it gives additionally in the offspring of 0.02% of genetic anomalies, i.e. 250 babies per million. These facts and perennial studies of these phenomena led scientists to the conclusion that there are no safe doses of radiation.
The effect of ionizing radiation on genital cell genes can cause harmful mutations, which will be transmitted from generation to generation, increasing the "mutational cargo" of humanity. Dangerous for life are conditions that increase the "genetic load" twice. Such a double dose is, according to the conclusions of the UN Scientific Committee on Atomic Radiation, the dose of 30 is happy with acute irradiation and 10 is glad during chronic (during the reproductive period). With increasing dose, not the severity increases, but the frequency of possible manifestation.
Mutational changes occur in plant organisms. In the forests underwent radioactive precipitation under Chernobyl, as a result of mutation, new absurd plants arose. Rust-red coniferous forests appeared. Located near the reactor, the wheat field two years after the accident, scientists have discovered about a thousand different mutations.
Influence on the embryo and the fruit due to the irradiation of the mother during the pregnancy period. The radio sensitivity of the cell changes at different stages of the division process (mitosis). The most sensitive cell at the end of peace and the beginning of the first month of division. Especially sensitive to the irradiation of the zygota is the embryonic cell, which is formed after the merger of the sperm with the egg. At the same time, the development of the embryo during this period and the influence of radiation, including X-ray, irradiation can be divided into three stages.
1st stage - after conception until the ninth day. It has just formed embryo under the influence of radiation dies. Death in most cases remain unnoticed.
The 2nd stage - from the ninth day on the sixth week after conception. This is the period of formation of internal organs and limbs. At the same time, under the influence of the radiation dose of 10 Bar, the whole range of defects appears - the whole range of defects - the splitting of the neba, stop the development of the limbs, violation of the formation of the brain, etc. At the same time, a delay in the body's growth is possible, which is expressed in reducing body size at birth. The result of the irradiation of the mother during this period of pregnancy can also be the death of a newborn at the time of birth or some time after them. However, the birth of a living child with rude defects is probably the biggest misfortune, much worse than the death of the embryo.
3rd stage - pregnancy after six weeks. Doses of radiation received by the mother cause a resistant lag of the body in growth. The irradiated mother of the child at birth has dimensions less than the norm and remains below the average height of life. Possible pathological changes in the nervous, endocrine systems, etc. Many radiologists suggest that the high probability of birth of an infallible child serves as the basis for interrupting pregnancy, if the dose obtained by the embryo during the first six weeks after conception exceeds 10 is happy. Such a dose entered the legislative acts of some Scandinavian countries. For comparison, with the rhythm of the stomach, the main areas of the bone marrow, the stomach, the chest receive the radiation dose of 30-40 is happy.
Sometimes a practical problem arises: a woman passes a series of radiography sessions, including stomach shots and pelvis organs, and subsequently it is found that it is pregnant. The situation is aggravated if the irradiation occurred in the first weeks after conception, when pregnancy can remain unnoticed. The only solution to this problem is not to expose to a woman by irradiation at the specified period. This can be achieved if the woman of reproductive age will undergo a stomach radiography or abdominal cavity only during the first ten days after the start of the menstrual period, when there is no doubt about the absence of pregnancy. In medical practice, this is called the rule of "ten days." With an emergency situation, X-ray procedures cannot be transferred for weeks or months, but by the side of the woman will be prudent to tell the doctor before conducting radiography about its possible pregnancy.
According to the degree of sensitivity to the ionizing radiation of the cell and the tissue of the human body of the unequal.
Particularly sensitive organs include sementers. Dose at 10-30 glad can reduce spermatogenesis during the year.
High sensitivity to irradiation has an immune system.
In the nervous system, the retina was the most sensitive, since the irradiation of vision was observed during irradiation. Disorders of the taste sensitivity occurred at radiation therapy of the chest, and the repeated irradiation doses of 30-500 P reduced the tactile sensitivity.
Changes in somatic cells can contribute to the occurrence of cancer. The cancer tumor occurs in the body at the moment when the somatic cell, coming out from under the control of the body, starts to share quickly. The root cause of this is caused by multiple or severely irradiation of mutation in genes, leading to the fact that cancer cells lose the ability even if there is a violation of the equilibrium to die physiological, and more accurately programmed death. They become as if immortal, constantly sharing, increasing in the amount and dildis only from the lack of nutrients. So the tumor growth occurs. The leukemia (blood cancer) is especially rapidly developing, a disease associated with an excessive appearance in the bone marrow, and then in the blood of defective white cells - leukocytes. True, recently it turned out that the relationship between radiation and cancer is more complicated than previously supposed. Thus, in the special report of the Japanese-American Association of scientists, it is said that only some types of cancer: lactic tumors and thyroid glasses, as well as leukemia - develop as a result of radiation damage. Moreover, Hiroshima and Nagasaki's experience showed that the cancer of the thyroid gland is observed when irradiated at 50 and more glad. The breast cancer, from which about 50% of the diseaseds die, is observed in women, repeatedly subjected to radiographic surveys.
Characteristic for radiation lesions is that radial injuries are accompanied by severe functional disorders, require complex and long (more than three months) treatment. The viability of irradiated tissues is significantly reduced. In addition, after many years and decades after receiving the injury, complications arise. So, there were cases of benign tumors 19 years after irradiation, and the development of radiation cancer of the skin and breasts in women in 25-27 years. Often, injuries are found against or after the effects of additional factors of non-radiation nature (diabetes, atherosclerosis, purulent infection, thermal or chemical injuries in the irradiation zone).
It is also necessary to take into account that people who survived the radiation accident are experiencing additional stress for several months and even years after it. Such stress may include a biological mechanism, which leads to malignant diseases. Thus, in Hiroshima and Nagasaki, a large outbreak of thyroid cancer diseases were observed 10 years after atomic bombing.
Studies conducted by radiologists on the basis of the data of the Chernobyl accident indicate a decrease in the impact of the effects of irradiation. So, it was established that irradiation in 15 BEER can cause violations in the activities of the immune system. Already upon obtaining a dose of 25 BER, the liquidators of the accident showed a decrease in lymphocytes in the blood - antibodies to bacterial antigens, and at 40 BER increases the likelihood of infectious complications. When exposed to continuous irradiation with a dose of 15 to 50 BER, cases of neurological disorders caused by changes in the structures of the brain were often noted. Moreover, these phenomena were observed in the remote time after exposure.
Radiation sickness
Depending on the dose and irradiation time, three degrees of the disease are observed: acute, subacted and chronic. In the foci of lesion (upon receipt of high doses), as a rule, an acute radiation disease (ALD) occurs.
Distinguish four degrees of Alb:
Light (100 - 200 happy). The initial period is the primary reaction as at the ALDa of all other degrees - is characterized by the attacks of nausea. Headache, vomiting, general ailment, a slight increase in body temperature, in most cases anorexia (lack of appetite, up to disgust for food), infectious complications are possible. The primary reaction occurs after 15 - 20 minutes after irradiation. Its manifestations are gradually disappearing in a few hours or days, and may generally be absent. Then there comes a hidden period, the so-called period of imaginary well-being, the duration of which is determined by the dose of irradiation and the general condition of the body (up to 20 days). During this time, the erythrocytes exhaust their lifetime, ceasing to supply oxygen cells of the body. Alb Light degree of cure. Negative consequences are possible - blood leukocytosis, leakage of the skin, reduced performance in 25% amazed after 1.5 - 2 hours after irradiation. There is a high hemoglobin content in the blood for 1 year from the moment of irradiation. Dates of recovery - up to three months. In this case, the personal installation and social motivation of the victim, as well as its rational employment, have great importance;
The average (200 - 400 is glad). Short seizures of nausea passing 2-3 days after irradiation. The hidden period is 10-15 days (may be absent), during which the leukocytes produced by lymph nodes die and stop showing the infection in the body. Platelets cease to roll blood. All this is the result of the fact that the bone marrow killed by radiation, lymph nodes and spleen do not produce new erythrocytes, leukocytes and platelets to replace it. Emerging skin edema, bubbles. Such a condition of the body that received the name "bone marrow syndrome" leads 20% of the death affected by death, which occurs as a result of the lesion of the tissues of blood-forming organs. Treatment is to insulate patients from the external environment, the introduction of antibiotics and blood transfusion. Young and older men are more susceptible to the Middle Degree Alsea, rather than men of middle age and women. Loss of ability to work occurs in 80% affected by 0.5 - 1 hour after irradiation and after recovery for a long time remains reduced. It is possible to develop the cataracts of the eyes and local defects of the limbs;
Heavy (400 - 600 glad). Symptoms characteristic of intestinal and gastric disorders: weakness, drowsiness, loss of appetite, nausea, vomiting, long diarrhea. Hidden period can last 1 - 5 days. After a few days, signs of dehydration of the body arise: body weight loss, exhaustion and complete exhausting. These phenomena are the result of the ignition of the lines of the intestinal walls, suction nutrients from the incoming food. Their cells under the influence of radiation are sterilized and lose the ability to share. There are foci of caming of the stomach walls, and the bacteria comes from the intestine to the bloodstream. Primary radiation ulcers appear, purulent infection from radiation burns. Loss of disability after 0.5-1 hours after irradiation is observed in 100% of victims. In 70% of the affected death occurs in a month of dehydration of the body and stomach poisoning (gastrointestinal syndrome), as well as from radiation burns with gamma irradiation;
Extremely heavy (more than 600 glad). In a matter of minutes after irradiation, severe nausea and vomiting arise. Diarrhea is 4-6 times a day, in the first 24 hours - a violation of consciousness, skin edema, strong headaches. These symptoms are accompanied by disorientation, loss of coordination of movements, difficulty in swallowing, stool disorder, convulsive seizures and ultimately death comes. The immediate cause of death is an increase in the amount of fluid in the brain due to its exit of small vessels, which leads to an increase in intracranial pressure. Such a state was called the "Syndrome of the Central Nervous System" syndrome.
It should be noted that the absorbed dose, causing the defeat of individual parts of the body and death, exceeds the deadly dose for the whole body. Deadly doses for individual parts of the body are as follows: The head - 2000 is happy, the lower part of the abdomen - 3000 is glad, the upper part of the abdomen - 5000 is happy, the chest - 10,000 is glad, limbs - 20,000 happy.
The level of effectiveness of the Treatment of Alb, which was achieved today is considered limit, as it is based on a passive strategy - the hope of independent recovery of cells in the radio sensitive tissues (mainly bone marrow and lymphatic nodes), to support other organism systems, transfusion of platelet mass to prevent hemorrhage, erythrocyte - To prevent oxygen starvation. After that, it remains only to wait for all cellular update systems and eliminate the disastrous effects of radiation irradiation. The outcome of the disease is determined by the end of 2-3 months. At the same time, there may be: complete clinical recovery of the victim; recovery in which its ability to work to one way or another will be limited; An unfavorable outcome with the progression of the disease or the development of complications leading to death.
The transplant of a healthy bone marrow prevents the immunological conflict, which in an irradiated body is especially dangerous, since it depletes the already undermined forces of immunity. Russian scientists - radiologists offer a new way of treating patients with radiation disease. If you pick up from an irradiated part of the bone marrow, then the processes of earlier recovery begins in the hematopoietic system, than with the natural development of events. The extracted part of the bone marrow is placed in artificial conditions, and then after a certain period are returned to the same organism. Immunological conflict (rejection) does not occur.
Currently, scientists have been carried out, and the first results obtained on the use of pharmaceutical radio protector, allowing a person to transfer radiation doses exceeding the lethal roughly twice. This is cysteine, cystamine, cystophos and a number of other substances containing sulfidhydrile groups (SH) at the end of the long molecule. These substances, as if "grovers", remove the resulting free radicals, which are largely responsible for strengthening oxidative processes in the body. However, a large disadvantage of these protector is the need to introduce it to the body intravenously, since the sulfidegidrile group, added to them to reduce toxicity, is destroyed in an acidic stomach environment and the protector loses protective properties.
Ionizing radiation has a negative impact on fats and lipids (leaf-like substances) contained in the body. Exposure disrupts the process of emulsifying and promoting fats in the area of \u200b\u200bthe cryptal division of the intestinal mucous membrane. As a result, droplets of non-emulsified and roughly emulsified fat, digested by the body fall into the clearance of blood vessels.
An increase in oxidation of fatty acids in the liver leads in insulin deficiency to elevated liver ketiones, i.e. Excess free fatty acids in the blood lowers insulin activity. And this in turn leads to a widely distributed disease of diabetes mellitus.
The most characteristic diseases associated with irradiation are malignant neoplasms (thyroid glands, respiratory organs, skin, hematopoietic organs), metabolic disorders and immunity, respiratory diseases, complications of pregnancy, congenital anomalies, mental disorders.
The restoration of the body after irradiation is a complex process, and it occurs unevenly. If the recovery of red blood cells and lymphocytes in the blood starts after 7 to 9 months, then the restoration of leukocytes - after 4 years. The duration of this process is influenced not only by radiation, but also psychogenic, socio-household, professional and other factors of the repretionary period, which can be combined into one concept of "quality of life" as the most exciting and fully expressing the nature of human interaction with biological factors of the environment, social and economic conditions.
Ensuring security when working with ionizing radiation
When organizing work, the following basic principles for ensuring radiation safety are used: the choice or reduction of the power of sources to minimum values; reducing the time of operation with sources; an increase in the distance from the source to the working; Shielding of radiation sources by materials absorbing or weakening ionizing radiation.
In rooms where work with radioactive substances and radioisotope devices is carried out, there are control over the intensity of various types of radiation. These premises must be isolated from other rooms and are equipped with a supply-exhaust ventilation. Other collective means of protection against ionizing radiation in accordance with GOST 12.4.120 are stationary and mobile protective screens, special containers for transporting and storing radiation sources, as well as for collecting and storing radioactive waste, protective safes and boxes.
Stationary and mobile protective screens are designed to reduce the level of radiation in the workplace to a permissible value. The protection against alpha radiation is achieved by the use of plexiglas with a thickness of several millimeters. To protect against beta radiation, the screens are made of aluminum or plexiglas. From neutron radiation protects water, paraffin, beryllium, graphite, boron connections, concrete. Lead and concrete are protected from X-ray and gamma radiation. For viewing windows use lead glass.
When working with radionuclides, we should use overalls. In case of contamination of the working room with radioactive isotopes over a cotton overalls, you should wear a film clothing: a bathrobe, costume, apron, pants, wrappers.
Film clothing is made of plastics or rubber fabrics, easily purified from radioactive contamination. In the case of the use of film clothing, it is necessary to provide the possibility of supplying air to the suit.
Overalls include respirators, pneumoslets and other personal protective equipment. To protect your eyes, apply glasses with glasses containing tungsten phosphate or lead. When using individual protective equipment, it is necessary to strictly observe the sequence of their wear and removal, and dosimetry control.
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