Radiation- invisible, inaudible, tasteless, colorless and odorless, and therefore terrible. Word " radiation"Causes paranoia, horror, or an incomprehensible state that strongly resembles anxiety. With direct exposure to radiation, radiation sickness can develop (at this moment, anxiety develops into panic, because no one knows what it is and how to deal with it). It turns out that radiation is lethal ... but not always, sometimes even useful.
So what is it? What do they eat her with, this radiation, how to survive a meeting with her and where to call if she accidentally pesters on the street?
Radioactivity- instability of the nuclei of some atoms, manifested in their ability to spontaneous transformations (decay), accompanied by the emission of ionizing radiation or radiation. Further we will talk only about the radiation that is associated with radioactivity.
Radiation, or ionizing radiation- these are particles and gamma quanta, the energy of which is large enough to create ions of different signs when exposed to matter. Radiation cannot be caused by chemical reactions.
There are several types of radiation.
Ultraviolet radiation and laser radiation in our consideration are not radiation.
Charged particles interact very strongly with a substance, therefore, on the one hand, even one alpha particle, when it enters a living organism, can destroy or damage a lot of cells, but, on the other hand, for the same reason, sufficient protection against alpha and beta - radiation is any, even a very thin layer of a solid or liquid substance - for example, ordinary clothing (if, of course, the radiation source is outside).
Distinguish radioactivity and radiation... Sources of radiation - radioactive substances or nuclear-technical installations (reactors, accelerators, X-ray equipment, etc.) - can exist for a long time, and radiation exists only until it is absorbed in any substance.
Exposure to radiation on a person is called radiation. The basis of this effect is the transfer of radiation energy to the cells of the body.
Irradiation can cause metabolic disorders, infectious complications, leukemia and malignant tumors, radiation infertility, radiation cataracts, radiation burns, radiation sickness... The effects of radiation have a stronger effect on dividing cells, and therefore radiation is much more dangerous for children than for adults.
As for the frequently mentioned genetic(i.e. inherited) mutations as a result of human exposure, they have never been detected. Even 78,000 children of those Japanese who survived the atomic bombings of Hiroshima and Nagasaki did not have any increase in the number of cases of hereditary diseases ( the book "Life after Chernobyl" by Swedish scientists S. Kullander and B. Larson).
It should be remembered that much more REAL damage to human health is caused by emissions from chemical and steel industries, not to mention the fact that science still does not know the mechanism of malignant degeneration of tissues from external influences.
The human body reacts to radiation, not to its source.
Those sources of radiation, which are radioactive substances, can enter the body with food and water (through the intestines), through the lungs (during respiration) and, to a small extent, through the skin, as well as during medical radioisotope diagnostics. In this case, they speak of internal learning.
In addition, a person may be exposed to external radiation from a radiation source that is outside his body.
Internal exposure is much more dangerous than external exposure.
Radiation is created by radioactive substances or specially designed equipment. The very same radiation, acting on the body, does not form radioactive substances in it, and does not turn it into a new source of radiation. Thus, a person does not become radioactive after an X-ray or fluorographic examination. By the way, an X-ray image (film) also does not carry radioactivity.
An exception is a situation in which radioactive drugs are deliberately introduced into the body (for example, during a radioisotope examination of the thyroid gland), and the person becomes a source of radiation for a short time. However, drugs of this kind are specially selected so that they quickly lose their radioactivity due to decay, and the intensity of radiation quickly decreases.
Of course you can " to stain»Body or clothing with radioactive liquid, powder or dust. Then some of this radioactive "dirt" - along with ordinary dirt - can be transferred by contact to another person. Unlike disease, which is transmitted from person to person and reproduces its harmful power (and can even lead to an epidemic), the transmission of dirt leads to its rapid dilution to safe limits.
Measure radioactivity
serves activity... Measured in Becquerell (Bq), which corresponds to 1 decay per second... The activity content of a substance is often estimated per unit of substance weight (Bq / kg) or volume (Bq / m3).
There is also such a unit of activity as Curie (Key). This is a huge amount: 1 Ki = 37000000000 (37 * 10 ^ 9) Bq.
The activity of a radioactive source characterizes its power. So, in the source of activity 1 Curie happens 37,000,000,000 decays per second.
As mentioned above, during these decays, the source emits ionizing radiation. The measure of the ionization effect of this radiation on matter is exposure dose... Often measured in X-rays (R). Since 1 Roentgen is a rather large value, in practice it is more convenient to use the millionth ( mkR) or thousandth ( mR) by X-ray fractions.
Action of common household dosimeters based on the measurement of ionization for a certain time, that is, the exposure dose rate. Unit of measurement of exposure dose rate - microRentai / hour
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The dose rate multiplied by the time is called dose... Dose rate and dose are related in the same way as vehicle speed and distance traveled by this vehicle (path).
To assess the impact on the human body, the concepts are used equivalent dose and equivalent dose rate... Measured, respectively, in Sievertach (Sv) and Sievertach / hour (Sv / hour). In everyday life, we can assume that 1 Sievert = 100 Roentgen... It is necessary to indicate which organ, part or all of the body received a given dose.
It can be shown that the above-mentioned point source with an activity of 1 Curie (for definiteness, we consider a cesium-137 source) at a distance of 1 meter from itself creates an exposure dose rate of approximately 0.3 Roentgen / hour, and at a distance of 10 meters - approximately 0.003 Roentgen / hour. Decrease in dose rate with increasing distance always occurs from the source and is due to the laws of radiation propagation.
Now the typical mistake of the mass media is absolutely clear when they report: “ Today, on such and such a street, a radioactive source of 10 thousand roentgens was discovered at a rate of 20».
First, the dose is measured in X-rays, and the source is characterized by its activity. A source of so many X-rays is the same as a bag of potatoes weighing so many minutes.
Therefore, in any case, we can only talk about the dose rate from the source. And not just the dose rate, but with an indication of the distance from the source this dose rate was measured.
Further, the following considerations can be made. 10 thousand roentgens / hour is a fairly large value. With a dosimeter in hand, it can hardly be measured, since when approaching the source, the dosimeter will first show both 100 Roentgens / hour and 1000 Roentgens / hour! It is very difficult to assume that the dosimetrist will continue to approach the source. Since dosimeters measure the dose rate in micro-Roentgen / hour, it can be assumed that in this case, too, we are talking about 10 thousand micro-Roentgen / hour = 10 milliRentgen / hour = 0.01 Roentgen / hour. Such sources, although they do not pose a mortal danger, come across on the street less often than hundred-ruble bills, and this can be a topic for an information message. Moreover, the reference to "norm 20" can be understood as a conditional upper limit of the usual dosimeter readings in a city, i.e. 20 micro-roentgen / hour.
Therefore, the correct message, apparently, should look like this: “Today, a radioactive source was found on such and such a street, close to which the dosimeter shows 10 thousand micro-roentgens per hour, while the average value of the radiation background in our city does not exceed 20 micro-roentgens per hour ".
There are more than 100 chemical elements in the periodic table. Almost every one of them is represented by a mixture of stable and radioactive atoms who call isotopes of this item. About 2000 isotopes are known, of which about 300 are stable.
For example, the first element of the periodic table - hydrogen - has the following isotopes:
hydrogen H-1 (stable)
deuterium H-2 (stable)
tritium H-3 (radioactive, half-life 12 years)
Radioactive isotopes are commonly referred to as radionuclides .
The number of radioactive nuclei of one type is constantly decreasing in time due to their decay.
The decay rate is usually characterized by the half-life: this is the time during which the number of radioactive nuclei of a certain type will decrease by 2 times.
Totally wrong is the following interpretation of the concept of "half-life": " if a radioactive substance has a half-life of 1 hour, this means that after 1 hour its first half will disintegrate, and after another 1 hour - the second half, and this substance will completely disappear (disintegrate)«.
For a radionuclide with a half-life of 1 hour, this means that after 1 hour its amount will become 2 times less than the initial one, after 2 hours - 4 times, after 3 hours - 8 times, etc., but never completely disappear. The radiation emitted by this substance will also decrease in the same proportion. Therefore, it is possible to predict the radiation situation for the future, if you know what and in what amount of radioactive substances create radiation in a given place at a given time.
Everyone has it radionuclide- mine half life, it can be both fractions of a second and billions of years. It is important that the half-life of a given radionuclide is constant, and it is impossible to change it.
Nuclei formed during radioactive decay, in turn, can also be radioactive. For example, radioactive radon-222 owes its origin to radioactive uranium-238.
Sometimes there are statements that radioactive waste in storage facilities will completely decay in 300 years. This is not true. It's just that this time will be about 10 half-lives of cesium-137, one of the most widespread technogenic radionuclides, and in 300 years its radioactivity in waste will decrease by almost 1000 times, but, unfortunately, it will not disappear.
The impact on a person of certain radiation sources will help to evaluate the following diagram (according to A.G. Zelenkov, 1990).
By origin, radioactivity is divided into natural (natural) and man-made.
a) Natural radioactivity
Natural radioactivity has existed for billions of years and is present literally everywhere. Ionizing radiation existed on Earth long before the birth of life on it and were present in space before the Earth itself. Radioactive materials have been incorporated into the Earth since its very birth. Any person is slightly radioactive: in the tissues of the human body, one of the main sources of natural radiation is potassium-40 and rubidium-87, and there is no way to get rid of them.
Let us take into account that a modern person spends up to 80% of his time indoors - at home or at work, where he receives the main dose of radiation: although buildings protect from external radiation, the building materials from which they are built contain natural radioactivity. Radon and its decay products make a significant contribution to human exposure.
b) Radon
The main source of this radioactive inert gas is the earth's crust. Penetrating through cracks and cracks in the foundation, floor and walls, radon is retained in the premises. Another source of indoor radon is the building materials themselves (concrete, brick, etc.) containing natural radionuclides, which are the source of radon. Radon can also enter houses with water (especially if it is supplied from artesian wells), when natural gas is burned, etc.
Radon is 7.5 times heavier than air. As a result, the concentration of radon in the upper floors of multi-storey buildings is usually lower than on the ground floor.
A person receives the main part of the radiation dose from radon while in a closed, unventilated room; regular ventilation can reduce the radon concentration by several times.
With prolonged intake of radon and its products into the human body, the risk of lung cancer increases manifold.
The following diagram will help you compare the radiation power of different radon sources.
c) Technogenic radioactivity
Technogenic radioactivity arises from human activity.
Deliberate economic activity, in the course of which there is a redistribution and concentration of natural radionuclides, leads to noticeable changes in the natural radiation background. This includes the extraction and combustion of coal, oil, gas, and other combustible minerals, the use of phosphate fertilizers, the extraction and processing of ores.
For example, studies of oil fields in Russia show a significant excess of permissible radioactivity standards, an increase in radiation levels in the area of wells caused by the deposition of radium-226, thorium-232 and potassium-40 salts on equipment and adjacent soil. Working and spent pipes are especially contaminated, which often have to be classified as radioactive waste.
A form of transport such as civil aviation exposes its passengers to increased exposure to cosmic radiation.
And, of course, nuclear weapons tests, nuclear power plants and industry make their own contribution.
Of course, accidental (uncontrolled) spread of radioactive sources is also possible: accidents, losses, theft, spraying, etc. Fortunately, such situations are VERY RARE. Moreover, their danger should not be exaggerated.
For comparison, the contribution of Chernobyl to the total collective radiation dose that Russians and Ukrainians living in contaminated areas will receive in the next 50 years will be only 2%, while 60% of the dose will be determined by natural radioactivity.
According to MosNPO "Radon", more than 70 percent of all cases of radioactive contamination detected in Moscow are in residential areas with intensive new construction and green areas of the capital. It was in the latter, in the 50s and 60s, that household waste dumps were located, where low-level radioactive industrial wastes, which were then considered relatively safe, were also disposed.
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A switch with a toggle switch glowing in the dark, the tip of which is painted with a permanent light composition based on radium salts. Dose rate for measurements "point-blank" - about 2 milliRentgen / hour |
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The only part of the computer, in relation to which we can talk about radiation, are only monitors on cathode ray tubes(CRT); other types of displays (liquid crystal, plasma, etc.) are not affected.
Monitors, along with conventional CRT TVs, can be considered a faint source of X-ray radiation that occurs on the inner glass surface of a CRT screen. However, due to the large thickness of the same glass, it also absorbs a significant part of the radiation. Until now, no effect of X-ray radiation of monitors on CRTs on health has been found, nevertheless, all modern CRTs are produced with a conditionally safe level of X-ray radiation.
Currently, the Swedish national standards for monitors are generally recognized by all manufacturers. "MPR II", "TCO-92", -95, -99... These standards, in particular, regulate the electric and magnetic fields from monitors.
The term "low radiation" is not a standard, but just a declaration by the manufacturer that he has done something known to him to reduce the radiation. The less common term "low emission" has a similar meaning.
The norms in force in Russia are set out in the document "Hygienic requirements for personal electronic computers and work organization" (SanPiN SanPiN 2.2.2 / 2.4.1340-03), the full text is at emissions from video monitors - here.
When fulfilling orders for radiation monitoring of offices of a number of organizations in Moscow, LRK-1 employees carried out a dosimetric examination of about 50 CRT monitors of different brands, with a screen diagonal from 14 to 21 inches. In all cases, the dose rate at a distance of 5 cm from the monitors did not exceed 30 μR / h, i.e. with a threefold margin, it was within the permissible norm (100 μR / hour).
There are populated areas on Earth with an increased background radiation. These are, for example, the high-mountainous cities of Bogota, Lhasa, Quito, where the level of cosmic radiation is about 5 times higher than at sea level.
These are also sandy zones with a high concentration of minerals containing phosphates with admixtures of uranium and thorium - in India (Kerala state) and Brazil (Espiritu Santo state). We can mention the section of water outlet with a high concentration of radium in Iran (Romser city). Although in some of these areas the absorbed dose rate is 1000 times higher than the average over the Earth's surface, the population survey did not reveal any shifts in the structure of morbidity and mortality.
In addition, even for a specific area, there is no "normal background" as a constant characteristic, it cannot be obtained as a result of a small number of measurements.
In any place, even for undeveloped territories, where "no man has stepped foot", the radiation background changes from point to point, as well as at each specific point over time. These background fluctuations can be quite significant. In the populated areas, the factors of the activities of enterprises, the work of transport, etc. are additionally superimposed. For example, at aerodromes, due to the high-quality concrete pavement with crushed granite, the background, as a rule, is higher than in the surrounding area.
Measurements of the radiation background in the city of Moscow allow you to indicate the TYPICAL background value in the street (open area) - 8 - 12 μR / hour, in room - 15 - 20 microR / hour.
With regard to radioactivity, there are many norms - literally everything is standardized. In all cases, a distinction is made between the population and the personnel, i.e. persons whose work is related to radioactivity (workers of nuclear power plants, nuclear industry, etc.). Outside of their production, personnel belong to the population. For personnel and production facilities, their own standards are established.
Further, we will talk only about the norms for the population - that part of them that is directly related to ordinary life, relying on the Federal Law “On radiation safety of the population” No. 3-FZ dated 05.12.96 and “Radiation safety standards (NRB-99). Sanitary Rules SP 2.6.1.1292-03 ".
The main task of radiation monitoring (measurements of radiation or radioactivity) is to determine whether the radiation parameters of the object under study (dose rate in the room, content of radionuclides in building materials, etc.) comply with the established standards.
a) air, food and water
For inhaled air, water and food, the content of both technogenic and natural radioactive substances is standardized.
In addition to NRB-99, the "Hygienic Requirements for the Quality and Safety of Food Raw Materials and Food Products (SanPiN 2.3.2.560-96)" are applied.
b) building materials
The content of radioactive substances from the families of uranium and thorium is normalized, as well as potassium-40 (in accordance with NRB-99).
Specific effective activity (Aeff) of natural radionuclides in building materials used for newly built residential and public buildings (class 1),
Aeff = ARa + 1.31ATh + 0.085 Ak should not exceed 370 Bq / kg,
where АRa and АTh are the specific activities of radium-226 and thorium-232, which are in equilibrium with the rest of the uranium and thorium families, and Ak is the specific activity of K-40 (Bq / kg).
Also, GOST 30108-94 “Building materials and products. Determination of the specific effective activity of natural radionuclides "and GOST R 50801-95" Wood raw materials, timber, semi-finished products and products from wood and wood materials. Permissible specific activity of radionuclides, sampling and methods for measuring the specific activity of radionuclides ”.
Note that according to GOST 30108-94, the value of Aeff m is taken as the result of determining the specific effective activity in the controlled material and establishing the material class:
Aeff m = Aeff + DAeff, where DAeff is the error in determining Aeff.
c) premises
The total content of radon and thoron in indoor air is normalized:
for new buildings - no more than 100 Bq / m3, for already operated - no more than 200 Bq / m3.
In the city of Moscow, MGSN 2.02-97 "Permissible levels of ionizing radiation and radon in building sites" are applied.
d) medical diagnostics
No dose limits are set for patients, but there is a requirement for minimum sufficient exposure levels to obtain diagnostic information.
e) computer technology
The exposure dose rate of X-ray radiation at a distance of 5 cm from any point of the video monitor or personal computer should not exceed 100 μR / hour. The norm is contained in the document "Hygienic requirements for personal computers and work organization" (SanPiN 2.2.2 / 2.4.1340-03).
They are protected from the source of radiation by time, distance and substance.
Concerning main source irradiation in rooms - radon and products of its decay, then regular ventilation makes it possible to significantly reduce their contribution to the dose load.
In addition, when it comes to building or finishing your own home, which will probably last more than one generation, you should try to buy radiation-safe building materials - since their assortment is now extremely rich.
Alcohol taken shortly before exposure can reduce the effects of exposure to some extent. However, its protective effect is inferior to modern anti-radiation drugs.
Is always think. But in everyday life, it is extremely unlikely that you will encounter a radiation source that poses an immediate threat to health. For example, in Moscow and the Moscow region, less than 50 such cases are recorded per year, and in most cases - thanks to the constant systematic work of professional dosimetrists (employees of MosNPO "Radon" and TsGSEN of Moscow) in places where radiation sources and local radioactive contamination are most likely to be detected (landfills , pits, scrap metal warehouses).
Nevertheless, it is in everyday life that sometimes one should remember about radioactivity. It's useful to do this:
It should be noted, however, that radiation is far from the main cause for constant concern. According to the scale of the relative hazard of various types of anthropogenic impact on humans developed in the United States, radiation is at 26 -th place, and the first two places are heavy metals and chemical toxicants.
What is radiation?
The term "radiation" comes from lat. radius is a beam, and in the broadest sense covers all types of radiation in general. Visible light and radio waves are also, strictly speaking, radiation, but it is customary to mean by radiation only ionizing radiation, that is, those whose interaction with matter leads to the formation of ions in it.
There are several types of ionizing radiation:
- alpha radiation - is a flux of helium nuclei
- beta radiation - a flow of electrons or positrons
- gamma radiation - electromagnetic radiation with a frequency of the order of 10 ^ 20 Hz.
- X-ray radiation - also electromagnetic radiation with a frequency of the order of 10 ^ 18 Hz.
- neutron radiation - neutron flux.
What is alpha radiation?
These are heavy positively charged particles, consisting of two protons and two neutrons, tightly bound together. In nature, alpha particles arise from the decay of atoms of heavy elements such as uranium, radium and thorium. In air, alpha radiation travels no more than five centimeters and, as a rule, is completely blocked by a sheet of paper or the outer dead skin layer. However, if an alpha-emitting substance is ingested through food or inhaled air, it irradiates internal organs and becomes potentially harmful.
What is beta radiation?
Electrons or positrons, which are much smaller than alpha particles and can penetrate several centimeters deep into the body. You can protect yourself from it with a thin sheet of metal, window glass and even ordinary clothing. Getting on unprotected areas of the body, beta radiation affects, as a rule, the upper layers of the skin. If a substance that emits beta particles gets into the body, it will irradiate the internal tissues.
What is neutron radiation?
Flux of neutrons, neutrally charged particles. Neutron radiation is generated in the process of fission of an atomic nucleus and has a high penetrating ability. Neutrons can be stopped with a thick concrete, water or paraffin barrier. Fortunately, in peaceful life, nowhere, except in the immediate vicinity of nuclear reactors, neutron radiation practically does not exist.
What is gamma radiation?
An electromagnetic wave that carries energy. In air, it can travel long distances, gradually losing energy as a result of collisions with atoms of the medium. Intense gamma rays, if left unprotected, can damage not only skin but also internal tissues.
What kind of radiation is used for fluoroscopy?
X-ray radiation is electromagnetic radiation with a frequency of the order of 10 ^ 18 Hz.
It arises from the interaction of electrons moving at high speeds with matter. When electrons collide with atoms of any substance, they quickly lose their kinetic energy. In this case, most of it turns into heat, and a small fraction, usually less than 1%, is converted into X-ray energy.
X-rays and gamma rays are often referred to as “hard” and “soft”. This is a relative characteristic of its energy and the associated penetrating ability of radiation: "hard" - high energy and penetrating ability, "soft" - less. X-rays are soft, gamma rays are hard.
Is there a place without radiation at all?
Hardly ever. Radiation is an ancient environmental factor. There are many natural sources of radiation: natural radionuclides found in the earth's crust, building materials, air, food and water, as well as cosmic rays. On average, they determine more than 80% of the annual effective dose received by the population, mainly due to internal irradiation.
What is radioactivity?
Radioactivity is the property of atoms of any element to spontaneously transform into atoms of other elements. This process is accompanied by ionizing radiation, i.e. radiation.
How is radiation measured?
Given that "radiation" itself is not a measurable quantity, there are different units for measuring different types of radiation, as well as pollution.
The concepts of absorbed, exposure, equivalent and effective dose, as well as the concept of equivalent dose rate and background are used separately.
In addition, for each radionuclide (radioactive isotope of an element) the activity of the radionuclide, the specific activity of the radionuclide and the half-life are measured.
What is absorbed dose and how is it measured?
Dose, absorbed dose (from Greek - fraction, portion) - determines the amount of energy of ionizing radiation absorbed by the irradiated substance. It characterizes the physical effect of radiation in any environment, including biological tissue, and is often calculated per unit mass of this substance.
It is measured in units of energy that is released in the substance (absorbed by the substance) when ionizing radiation passes through it.
Units are happy, gray.
Rad (rad - abbreviation for radiation absorbed dose) is a non-systemic unit of absorbed dose. Corresponds to a radiation energy of 100 erg absorbed by a substance weighing 1 gram
1 rad = 100 erg / g = 0.01 J / kg = 0.01 Gy = 2.388 x 10-6 cal / g
With an exposure dose of 1 X-ray, the absorbed dose in the air will be 0.85 rad (85 erg / g).
Gray (Gr.) Is the SI unit of absorbed dose. Corresponds to the radiation energy of 1 J, absorbed by 1 kg of matter.
1 Gr. = 1 J / kg = 104 erg / g = 100 rad.
What is exposure dose and how is it measured?
The exposure dose is determined by the ionization of the air, that is, by the total charge of the ions formed in the air when ionizing radiation passes through it.
Units of measurement are roentgen, pendant per kilogram.
Roentgen (R) is a non-systemic unit of exposure dose. This is such an amount of gamma or X-ray radiation, which in 1 cm3 of dry air (having a weight of 0.001293 g under normal conditions) forms 2.082 x 109 pairs of ions. When recalculated for 1 g of air, this will be 1.610 x 1012 ion pairs or 85 erg / g of dry air. Thus, the physical energy equivalent of an X-ray is 85 erg / g for air.
1 C / kg is the SI unit of the exposure dose. This is such an amount of gamma or X-ray radiation, which in 1 kg of dry air forms 6.24 x 1018 pairs of ions, which carry a charge of 1 coulomb of each sign. The physical equivalent of 1 C / kg is 33 J / kg (for air).
The ratios between X-ray and C / kg are as follows:
1 P = 2.58 x 10-4 C / kg - exactly.
1 C / kg = 3.88 x 103 R - approx.
What is an equivalent dose and how is it measured?
The equivalent dose is equal to the absorbed dose calculated for a person taking into account the coefficients that take into account the different ability of different types of radiation to damage the tissues of the body.
For example, for X-ray, gamma, beta radiation, this coefficient (it is called the radiation quality factor) is equal to 1, and for alpha radiation - 20. That is, with the same absorbed dose, alpha radiation will cause 20 times more harm to the body than, for example, gamma radiation.
Units of measure are rem and sievert.
Rem is the biological equivalent of Rad (formerly X-ray). Non-systemic unit of equivalent dose measurement. In general:
1 rem = 1 rad * K = 100 erg / g * K = 0.01 Gy * K = 0.01 J / kg * K = 0.01 Sievert,
where K is the radiation quality factor, see definition of equivalent dose
For X-rays, gamma, beta radiation, electrons and positrons, 1 rem corresponds to an absorbed dose of 1 rad.
1 rem = 1 rad = 100 erg / g = 0.01 Gy = 0.01 J / kg = 0.01 Sievert
Considering that at an exposure dose of 1 X-ray, air absorbs approximately 85 erg / g (physical equivalent of an X-ray), and biological tissue approximately 94 erg / g (biological equivalent of an X-ray), it can be assumed with a minimum error that an exposure dose of 1 X-ray for a biological tissue corresponds to an absorbed dose of 1 rad and an equivalent dose of 1 rem (for X-rays, gamma, beta radiation, electrons and positrons), that is, roughly speaking - 1 X-ray, 1 rad and 1 rem are one and the same.
Sievert (Sv) is the SI unit of equivalent and effective equivalent doses. 1 Sv is equal to the equivalent dose at which the product of the absorbed dose in Grays (in biological tissue) by the coefficient K will be equal to 1 J / kg. In other words, this is such an absorbed dose at which 1 J of energy is released in 1 kg of a substance.
In general:
1 Sv = 1 Gy * K = 1 J / kg * K = 100 rad * K = 100 rem * K
At K = 1 (for X-ray, gamma, beta radiation, electrons and positrons) 1 Sv corresponds to an absorbed dose of 1 Gy:
1 Sv = 1 Gy = 1 J / kg = 100 rad = 100 rem.
The effective equivalent dose is equal to the equivalent dose, calculated taking into account the different sensitivity of various organs of the body to radiation. An effective dose takes into account not only that different types of radiation have different biological effectiveness, but also the fact that some parts of the human body (organs, tissues) are more sensitive to radiation than others. For example, at the same equivalent dose, lung cancer is more likely than thyroid cancer. Thus, the effective dose reflects the total effect of human exposure in terms of long-term consequences.
To calculate the effective dose, the equivalent dose received by a specific organ or tissue is multiplied by the appropriate factor.
For the whole organism, this coefficient is 1, and for some organs it has the following meanings:
bone marrow (red) - 0.12
thyroid gland - 0.05
lungs, stomach, large intestine - 0.12
gonads (ovaries, testes) - 0.20
skin - 0.01
To estimate the total effective equivalent dose received by a person, the indicated doses for all organs are calculated and summed.
The unit of measurement is the same as for the equivalent dose - "rem", "sievert"
What is equivalent dose rate and how is it measured?
The dose received per unit of time is called the dose rate. The higher the dose rate, the faster the radiation dose grows.
For the equivalent dose in SI, the unit of the dose rate is sievert per second (Sv / s), the off-system unit is rem per second (rem / s). In practice, their derivatives are most often used (μSv / h, mrem / h, etc.)
What is background, natural background, and how are they measured?
Background is another name for the exposure dose rate of ionizing radiation at a given location.
Natural background - the power of the exposure dose of ionizing radiation in a given place, created only by natural sources of radiation.
The units of measurement, respectively, are rem and sievert.
Often the background and natural background are measured in X-rays (micro-roentgen, etc.), roughly equating X-rays and rem (see the question on the equivalent dose).
What is radionuclide activity and how is it measured?
The amount of radioactive substance is measured not only by units of mass (gram, milligram, etc.), but also by activity, which is equal to the number of nuclear transformations (decays) per unit time. The more nuclear transformations the atoms of a given substance undergo per second, the higher its activity and the greater danger it can pose to humans.
The unit of activity in SI is decay per second (dec / s). This unit is called becquerel (Bq). 1 Bq equals 1 dec / s.
The most common non-systemic unit of activity is curie (Ki). 1 Ci is equal to 3.7 * 10 in 10 Bq, which corresponds to the activity of 1 g of radium.
What is the specific surface activity of a radionuclide?
This is the activity of a radionuclide per unit area. It is usually used to characterize the radioactive contamination of an area (density of radioactive contamination).
Units of measurement - Bq / m2, Bq / km2, Ci / m2, Ci / km2.
What is half-life and how is it measured?
The half-life (T1 / 2, also denoted by the Greek letter "lambda", half-life) is the time during which half of the radioactive atoms decay and their number decreases by 2 times. The value is strictly constant for each radionuclide. The half-lives of all radionuclides are different - from fractions of a second (short-lived radionuclides) to billions of years (long-lived).
This does not mean that after a time equal to two T1 / 2, the radionuclide will decay completely. Through T1 / 2, the radionuclide will be halved, after 2 * T1 / 2 - four times, etc. Theoretically, the radionuclide will never completely decay.
In the modern world, it so happened that we are surrounded by many harmful and dangerous things and phenomena, most of which are the work of the person himself. In this article we will talk about radiation, namely: what is radiation.
The concept of "radiation" comes from the Latin word "radiatio" - radiation. Radiation is ionizing radiation that spreads in the form of a stream of quanta or elementary particles.
This radiation is called ionizing because radiation, penetrating through any tissues, ionizes their particles and molecules, which leads to the formation of free radicals, which lead to mass death of tissue cells. The impact of radiation on the human body is destructive and is called radiation.
In small doses, radioactive radiation is not dangerous if doses hazardous to health are not exceeded. If the exposure standards are exceeded, the result can be the development of many diseases (up to cancer). The consequences of minor exposures are difficult to track, as diseases can develop for many years or even decades. If the exposure was strong, then this leads to radiation sickness, and to the death of a person, such types of radiation are possible only in case of man-made disasters.
Distinguish between internal and external exposure. Internal exposure can occur through the consumption of irradiated foods, inhalation of radioactive dust, or through the skin and mucous membranes.
For an ordinary person, it is enough to know the magnitude of the dose and the dose rate of radiation.
The first indicator is characterized by:
The dose rate is measured in R / hour, mSv / s, that is, it shows the strength of the radiation flux during a certain time of its exposure.
You can measure the level of radiation using special devices - dosimeters.
The normal background radiation is considered to be 0.10-0.16 μSv per hour. Radiation levels up to 30mkSv / hour are considered safe. If the radiation level exceeds this threshold, then the time spent in the affected area is reduced in proportion to the dose (for example, at 60 μSv / hour, the exposure time is no more than half an hour).
Depending on the source of internal radiation, you can use:
Now you know what radiation is dangerous. Be alert to signs indicating infestation zones and stay away from these zones.
In recent years, we can hear more and more often about the radioactive threat to all mankind. Unfortunately, this is really so, and, as the experience of the Chernobyl accident and the nuclear bomb in Japanese cities has shown, radiation can turn from a faithful assistant into a fierce enemy. And in order to know what radiation is and how to protect oneself from its negative effects, we will try to analyze all the available information.
Every person has come across the concept of "radiation" at least once in his life. But what radiation is and how dangerous it is, few people know. To understand this issue in more detail, it is necessary to carefully study all types of radiation effects on humans and nature. Radiation is a process of radiation of a stream of elementary particles of an electromagnetic field. The effect of radiation on human life and health is usually called radiation. In the process of this phenomenon, radiation multiplies in the cells of the body and thereby destroys it. Radiation exposure is especially dangerous for young children, whose bodies are not sufficiently formed and not matured. Damage to a person by such a phenomenon can cause the most serious diseases: infertility, cataracts, infectious diseases and tumors (both malignant and benign). In any case, radiation does not benefit a person's life, but only destroys it. But do not forget that you can protect yourself and purchase a radiation dosimeter, with which you will always know about the radioactive level of the environment.
In fact, the body reacts to radiation, not its source. Radioactive substances enter the human body through the air (during the respiratory process), as well as through the consumption of food and water, which were initially irradiated by a stream of radiation rays. The most dangerous radiation exposure is probably internal. It is carried out with the aim of treating certain diseases when using radioisotopes in medical diagnostics.
In order to answer the question of what radiation is as clear as possible, you should consider its varieties. By the nature and effect on a person, several types of radiation are distinguished:
Alpha-, Beta- and Gamma-emitting particles are considered to be extremely dangerous. They can cause genetic diseases, malignant tumors and even death. By the way, the nuclear power plant radiation emitted into the environment, according to the assurances of experts, is not dangerous, although it combines almost all types of radioactive contamination. Sometimes antiques and antiques are treated with radiation in order to avoid rapid damage to the cultural heritage. However, radiation quickly reacts with living cells, and subsequently destroys them. Therefore, it is worthwhile to be wary of antiquities. Clothes serve as elementary protection against the penetration of external radiation. Don't count on complete radiation protection on a hot sunny day. In addition, radiation sources may not give themselves out for a long time and show activity at the moment when you are near.
Radiation levels can be measured with a dosimeter in both industrial and domestic environments. For those who live near nuclear power plants, or people who are simply concerned about their safety, this device will be simply irreplaceable. The main purpose of a device such as a radiation dosimeter is to measure the dose rate of radiation. This indicator can be checked not only in relation to a person and a room. Sometimes you have to pay attention to some objects that can pose a danger to humans. Children's toys, food and building materials - each of the items can be endowed with a certain dose of radiation. For those residents who live near the Chernobyl nuclear power plant, where a terrible disaster occurred in 1986, it is simply necessary to buy a dosimeter in order to always be on the alert and know what dose of radiation is present in the environment at a particular moment. Fans of extreme entertainment, hiking in places far from civilization should provide themselves with items for their own safety in advance. It is impossible to clear the ground, building materials or food from radiation. Therefore, it is better to avoid adverse effects on your body.
Perhaps many people think so. However, this is not quite true. A certain level of radiation comes only from a monitor, and even then, only from an electrobeam. At the present time, manufacturers do not produce such equipment, which has been excellently replaced by LCD and plasma screens. But in many houses old ray TVs and monitors are still functioning. They are a rather weak source of X-ray radiation. Due to the thickness of the glass, this very radiation remains on it and does not harm human health. So don't worry too much.
It can be said with utmost precision that natural radiation is a very unstable parameter. Depending on the geographic location and the specific time period, this indicator can vary within a wide range. For example, the radiation indicator on Moscow streets ranges from 8 to 12 microroentgens per hour. But on mountain peaks it will be 5 times higher, since there the protective capabilities of the atmosphere are much lower than in settlements that are closer to the level of the world ocean. It should be noted that in places of accumulation of dust and sand saturated with a high content of uranium or thorium, the level of radiation background will be significantly increased. To determine the background radiation indicator at home, you should purchase a dosimeter-radiometer and take appropriate measurements indoors or outdoors.
Recently, more and more often you can hear discussions on the topic of what radiation is and how to deal with it. And in the course of discussions such a term as radiation protection comes up. It is customary to understand radiation protection as a set of specific measures to protect living organisms from the effects of ionizing radiation, as well as to search for ways to reduce the damaging effect of ionizing radiation.
There are several types of radiation protection:
To protect against different types of radiation, you can use some household items:
For a person who finds himself within the radius of the radiation contamination zone, the most important issue at this moment will be his own protection. Therefore, everyone who has become an unwitting prisoner of the spread of radiation levels should definitely leave their location and leave as far as possible. The faster a person does this, the less likely it is to receive a certain and unwanted dose of radioactive substances. If it is not possible to leave your home, then it is worth resorting to other security measures:
It is dangerous to drink radioactive water, since its total radiation is high enough and can have a negative effect on the human body. The easiest way to clean it is to run it through a charcoal filter. Of course, the shelf life of the filter cassette is drastically reduced. Therefore, you should change the cassette as often as possible. Another untested way is boiling. The radon removal guarantee will not be 100% in any of the cases.
It is well known that in the course of discussions on the topic of what radiation is, the question arises of how to protect yourself from it, what to eat and what vitamins to use. There is a certain list of products that are most dangerous for consumption. The greatest amount of radionuclides accumulates in fish, mushrooms and meat. Therefore, it is worth limiting yourself in the use of these foods. Vegetables must be thoroughly washed, boiled and the top peel cut off. The best foods for consumption during the period of radioactive radiation are sunflower seeds, offal - kidneys, heart, and eggs. You need to eat as much iodine-containing products as possible. Therefore, everyone should buy iodized salt and seafood.
Some people believe that red wine will protect against radionuclides. There is some truth in this. When you consume 200 ml of this drink per day, the body becomes less vulnerable to radiation. But the accumulated radionuclides cannot be removed with wine, so the total radiation still remains. However, some substances contained in a wine drink can block the harmful effects of radiation elements. However, in order to avoid problems, it is necessary to remove harmful substances from the body with the help of medicines.
You can try to remove some of the radionuclides that have entered the body with the help of sorbent preparations. The simplest means that can weaken the effects of radiation include activated charcoal, which must be taken 2 tablets before meals. Such medications as Enterosgel and Atoxil are endowed with a similar property. They block harmful elements, enveloping them, and remove them from the body using the urinary system. At the same time, harmful radioactive elements, even if they remain in the body in an insignificant amount, will not be able to have a significant effect on human health.
In the fight against the elimination of radionuclides, not only medications purchased at the pharmacy can help, but also some types of herbs, which will cost several times cheaper. For example, lungwort, lure and ginseng root can be classified as radioactive plants. In addition, to reduce the level of concentration of radionuclides, it is recommended to use an extract of Eleutherococcus in the amount of half a teaspoon after breakfast, washed down with this tincture with warm tea.
When exposed to the human body, radiation does not create radioactive substances in it. It follows from this that a person by himself cannot be a source of radiation. However, things that have been touched by a dangerous dose of radiation are unsafe for health. It is believed that it is better not to store X-rays at home either. But they won't actually harm anyone. The only thing to remember is that X-rays should not be taken too often, otherwise it can lead to health problems, since the dose of radioactive radiation is still there.
Radioactivity is called the instability of the nuclei of some atoms, which manifests itself in their ability to spontaneously transform (according to scientific - decay), which is accompanied by the release of ionizing radiation (radiation). The energy of such radiation is large enough, therefore, it is capable of acting on matter, creating new ions of different signs. It is impossible to cause radiation by means of chemical reactions, it is a completely physical process.
There are several types of radiation:
The most dangerous for humans is Alpha, Beta and Gamma radiation, which can lead to serious diseases, genetic disorders and even death. The degree to which radiation affects human health depends on the type of radiation, time and frequency. Thus, the consequences of radiation, which can lead to fatal cases, occur both during a single stay at the strongest radiation source (natural or artificial), and when storing weakly radioactive items at home (antiques, precious stones treated with radiation, items made of radioactive plastic) ... Charged particles are very active and interact strongly with matter, so even one alpha particle can be enough to destroy a living organism or damage a huge number of cells. However, for the same reason, any layer of solid or liquid substance, for example, ordinary clothing, is a sufficient means of protection against radiation of this type.
According to www.site specialists, ultraviolet radiation or laser radiation cannot be considered radioactive. What is the difference between radiation and radioactivity?
Sources of radiation are nuclear technical installations (particle accelerators, reactors, X-ray equipment) and radioactive substances. They can exist for a considerable time, without manifesting themselves in any way, and you may not even suspect that you are near the object of the strongest radioactivity.
Units of measurement of radioactivity
Radioactivity is measured in Becquerels (BC), which corresponds to one decay per second. The content of radioactivity in a substance is also often estimated per unit of weight - Bq / kg, or volume - Bq / m3. Sometimes there is such a unit as Curie (Ki). This is a huge amount, equal to 37 billion Bq. When a substance decays, the source emits ionizing radiation, the measure of which is the exposure dose. It is measured in Roentgens (R). 1 The X-ray value is quite large, therefore, in practice, the millionth (μR) or thousandth (mR) fraction of the X-ray is used.
Household dosimeters measure ionization over a certain time, that is, not the exposure dose itself, but its power. The unit of measurement is micro-roentgen per hour. It is this indicator that is most important for a person, since it allows one to assess the danger of a particular source of radiation.
Radiation and human health
The impact of radiation on the human body is called radiation. During this process, radiation energy is transferred to the cells, destroying them. Irradiation can cause all kinds of diseases: infectious complications, metabolic disorders, malignant tumors and leukemia, infertility, cataracts and much more. Radiation is especially acute for dividing cells, so it is especially dangerous for children.
The body reacts to the radiation itself, not to its source. Radioactive substances can enter the body through the intestines (with food and water), through the lungs (during breathing) and even through the skin during medical diagnostics with radioisotopes. In this case, internal irradiation takes place. In addition, external radiation exerts a significant effect of radiation on the human body, i.e. the radiation source is outside the body. The most dangerous, of course, is internal exposure.
How to remove radiation from the body? This question, of course, worries many. Unfortunately, there are no particularly effective and fast ways to remove radionuclides from the human body. Certain foods and vitamins help cleanse the body of small doses of radiation. But if the exposure is serious, then one can only hope for a miracle. Therefore, it is better not to risk it. And if there is even the slightest danger of being exposed to radiation, it is necessary to quickly remove your feet from the dangerous place and call specialists.
Is the computer a source of radiation?
This question, in the age of the spread of computer technology, worries many. The only part of a computer that can theoretically be radioactive is a monitor, and even then, only an electrobeam one. Modern displays, liquid crystal and plasma, do not possess radioactive properties.
CRT monitors, like televisions, are a weak X-ray source of radiation. It appears on the inner surface of the glass of the screen, however, due to the considerable thickness of the same glass, it absorbs most of the radiation. So far, no health effects of CRT monitors have been found. However, with the widespread use of liquid crystal displays, this issue is losing its former relevance.
Can a person become a source of radiation?
Radiation, acting on the body, does not form radioactive substances in it, i.e. a person does not turn himself into a source of radiation. By the way, X-rays, contrary to popular belief, are also safe for health. Thus, unlike a disease, radiation damage from person to person cannot be transmitted, but radioactive objects carrying a charge can be dangerous.
Radiation measurement
You can measure the radiation level with a dosimeter. Household appliances are simply irreplaceable for those who want to protect themselves as much as possible from the deadly effects of radiation. The main purpose of a household dosimeter is to measure the dose rate of radiation in the place where a person is, to examine certain items (cargo, building materials, money, food, children's toys, etc.), which is simply necessary for those who often visit areas of radiation contamination. caused by the accident at the Chernobyl nuclear power plant (and such foci are present in almost all regions of the European territory of Russia). The dosimeter will also help those who are in an unfamiliar area, far from civilization: on a hike, picking mushrooms and berries, on a hunt. It is imperative to examine the site of the proposed construction (or purchase) of a house, summer cottage, vegetable garden or land plot for radiation safety, otherwise, instead of benefit, such a purchase will only bring deadly diseases.
It is almost impossible to clean food, earth or objects from radiation, so the only way to protect yourself and your family is to stay away from them. Namely, a household dosimeter will help identify potentially hazardous sources.
Radioactivity rates
There are a large number of regulations regarding radioactivity, i.e. try to normalize practically everything. It is another matter that dishonest sellers, in pursuit of big profits, do not comply, and sometimes openly violate the norms established by law. The main norms established in Russia are spelled out in the Federal Law No. 3-ФЗ dated 05.12.1996 "On radiation safety of the population" and in the Sanitary Rules 2.6.1.1292-03 "Standards of radiation safety".
For inhaled air, water and foodstuffs, the content of both man-made (obtained as a result of human activity) and natural radioactive substances is regulated, which must not exceed the norms established by SanPiN 2.3.2.560-96.
In building materials the content of radioactive substances of the thorium and uranium family, as well as potassium-40 is normalized, their specific effective activity is calculated using special formulas. Requirements for building materials are also specified in GOST.
Indoors the total content of thoron and radon in the air is regulated: for new buildings it should be no more than 100 Bq (100 Bq / m 3), and for those already in use - less than 200 Bq / m 3. In Moscow, additional standards MGSN2.02-97 are also applied, which regulate the maximum permissible levels of ionizing radiation and the content of radon in building sites.
For medical diagnostics dose limits are not specified, however, requirements are put forward for minimum sufficient exposure levels in order to obtain high-quality diagnostic information.
In computer technology regulates the emission limit for electro-beam (CRT) monitors. The dose rate of X-ray examination at any point at a distance of 5 cm from the video monitor or personal computer should not exceed 100 μR per hour.
It is possible to check whether the manufacturers comply with the statutory norms only on their own, using a miniature household dosimeter. It is very easy to use it, just press one button and compare the readings on the device's liquid crystal display with the recommended ones. If the norm is significantly exceeded, then this item poses a threat to life and health, and it should be reported to the Ministry of Emergencies so that it is destroyed. Protect yourself and your family from radiation!
