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 the chemical and steel industries, not to mention the fact that the mechanism of malignant degeneration of tissues from external influences is still unknown to science.
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
.
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 to which organ, part or the whole body the given dose fell.
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.
To compare the radiation power of different radon sources, the following diagram will help.
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 only 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.
Radiation is associated by many with unavoidable diseases that are difficult to treat. And this is partly true. The most terrible and deadly weapon is called nuclear. Therefore, it is not without reason that radiation is considered one of the greatest disasters on earth. What is radiation and what are its consequences? Let's consider these issues in this article.
Radioactivity is the nuclei of some atoms that are unstable. As a result of this property, the decay of the nucleus occurs, which is due to ionizing radiation. This radiation is called radiation. It possesses high energy power. consists in changing the composition of cells.
There are several types of radiation, depending on the level of its effect on
The last two types are neutrons and We meet with this type of radiation radiation in everyday life. It is the safest for the human body.
Therefore, speaking about what radiation is, it is necessary to take into account the level of its radiation and the harm caused to living organisms.
Radioactive particles have tremendous energetic power. They enter the body and collide with its molecules and atoms. As a result of this process, their destruction occurs. A feature of the human body is that it mostly consists of water. Therefore, the molecules of this particular substance are exposed to radioactive particles. As a result, there are compounds that are very harmful to the human body. They become part of all chemical processes in a living organism. All this leads to the destruction and destruction of cells.
Knowing what radiation is, you also need to know what harm it causes to the body.
Human exposure to radiation falls into three main categories.
The main harm is done to the genetic background. That is, as a result of infection, a change and destruction of sex cells and their structure occurs. This is reflected in the offspring. A lot of children are born with deviations and deformities. This mainly occurs in those areas that are prone to radiation contamination, that is, they are located next to other enterprises of this level.
The second type of diseases that arise under the influence of radiation is hereditary diseases at the genetic level, which appear after a while.
The third type is immune diseases. The body under the influence of radioactive radiation becomes susceptible to viruses and diseases. That is, immunity decreases.
The escape from radiation is distance. The permissible level of radiation for a person is 20 microroentgens. In this case, it has no effect on the human body.
Knowing what radiation is, you can, to a certain extent, protect yourself from its effects.
Task (to warm up):
I'll tell you, my friends,
How to grow mushrooms:
Need to go to the field early in the morning
Move two pieces of uranium ...
Question: What is the total mass of pieces of uranium for a nuclear explosion to occur?
Answer(in order to see the answer - you need to select the text) : For uranium-235, the critical mass is about 500 kg. If we take a ball of such a mass, then the diameter of such a ball will be 17 cm.
Radiation (translated from English "radiation") is radiation that is applied not only to radioactivity, but also to a number of other physical phenomena, for example: solar radiation, thermal radiation, etc. (International Commission on Radiation Protection) and radiation safety rules, the phrase "ionizing radiation".
Ionizing radiation - radiation (electromagnetic, corpuscular), which causes ionization (the formation of ions of both signs) of a substance (environment). The probability and number of ion pairs formed depends on the energy of the ionizing radiation.
Radioactivity - radiation from excited nuclei or spontaneous transformation of unstable atomic nuclei into nuclei of other elements, accompanied by the emission of particles or γ-quantum (s). The transformation of ordinary neutral atoms into an excited state occurs under the influence of external energies of various kinds. Further, the excited nucleus seeks to remove excess energy by radiation (emission of an alpha particle, electrons, protons, gamma quanta (photons), neutrons), until a stable state is reached. Many heavy nuclei (transuranium series in the periodic table - thorium, uranium, neptunium, plutonium, etc.) are initially in an unstable state. They are able to spontaneously disintegrate. This process is also accompanied by radiation. Such nuclei are called natural radionuclides.
This animation clearly shows the phenomenon of radioactivity.
The Wilson chamber (plastic box cooled to -30 ° C) is filled with isopropyl alcohol vapor. Julien Simon placed a 0.3-cm³ piece of radioactive uranium (uraninite mineral) in it. The mineral emits alpha particles and beta particles, as it contains U-235 and U-238. On the path of movement of α and beta particles are molecules of isopropyl alcohol.
Since the particles are charged (alpha - positive, beta - negative), they can take an electron from the alcohol molecule (alpha particle) or add electrons to the alcohol molecules of the beta particle). This, in turn, gives the molecules a charge, which then attracts uncharged molecules around them. When the molecules clump together, they produce noticeable white clouds, which is clearly visible in the animation. So we can easily trace the paths of the ejected particles.
α particles create straight, dense clouds, while beta particles create long ones.
Isotopes are a variety of atoms of the same chemical element, having different mass numbers, but including the same electric charge of atomic nuclei and, therefore, occupying D.I. Mendeleev single place. For example: 131 55 Cs, 134 m 55 Cs, 134 55 Cs, 135 55 Cs, 136 55 Cs, 137 55 Cs. Those. charge largely determines the chemical properties of the element.
There are isotopes stable (stable) and unstable (radioactive isotopes) - spontaneously decaying. About 250 stable and about 50 natural radioactive isotopes are known. An example of a stable isotope is 206 Pb, which is the end product of the decay of the natural radionuclide 238 U, which in turn appeared on our Earth at the beginning of mantle formation and is not associated with technogenic pollution.
The main types of ionizing radiation that are most often encountered are:
Of course, there are other types of radiation (neutron, positron, etc.), but we meet with them in everyday life much less often. Each type of radiation has its own nuclear-physical characteristics and, as a consequence, different biological effects on the human body. Radioactive decay can be accompanied by one of the types of radiation or several at once.
Sources of radioactivity can be natural or artificial. Natural sources of ionizing radiation are radioactive elements found in the earth's crust and forming a natural background radiation along with cosmic radiation.
Artificial sources of radioactivity are usually formed in nuclear reactors or accelerators based on nuclear reactions. Sources of artificial ionizing radiation can also be a variety of electrical vacuum physical devices, charged particle accelerators, etc. For example: a TV picture tube, an X-ray tube, a kenotron, etc.
Alpha radiation (α radiation) - corpuscular ionizing radiation, consisting of alpha particles (helium nuclei). Formed during radioactive decay and nuclear transformations. Helium nuclei have a fairly large mass and energy up to 10 MeV (Megaelectron-Volt). 1 eV = 1.6 ∙ 10 -19 J. Having an insignificant range in the air (up to 50 cm), they pose a high danger to biological tissues if they contact the skin, mucous membranes of the eyes and respiratory tract, if they enter the body in the form of dust or gas ( radon-220 and 222). The toxicity of alpha radiation is due to the colossal high ionization density due to its high energy and mass.
Beta radiation (β-radiation) - corpuscular electron or positron ionizing radiation of the corresponding sign with a continuous energy spectrum. It is characterized by the maximum energy of the spectrum E β max, or the average energy of the spectrum. The range of electrons (beta particles) in the air reaches several meters (depending on the energy), in biological tissues the range of a beta particle is several centimeters. Beta radiation, like alpha radiation, is a hazard due to contact radiation (surface contamination), for example, if it gets inside the body, on mucous membranes and skin.
Gamma radiation (γ-radiation or gamma quanta) - short-wave electromagnetic (photon) radiation with a wavelength
X-ray radiation is similar in physical properties to gamma radiation, but it has a number of peculiarities. It appears in the X-ray tube due to the abrupt stop of electrons on the ceramic target-anode (the place where the electrons strike is made, as a rule, of copper or molybdenum) after acceleration in the tube (continuous spectrum - bremsstrahlung) and when electrons are knocked out of the internal electronic shells of the target atom (line spectrum). The energy of X-ray radiation is low - from fractions of a few eV to 250 keV. X-rays can be obtained using charged particle accelerators - synchrotron radiation with a continuous spectrum having an upper limit.
Ionizing radiation source (IRS) - an object that includes a radioactive substance or technical device that creates or, in certain cases, is capable of creating ionizing radiation. Distinguish between closed and open sources of radiation.
Radionuclides are nuclei subject to spontaneous radioactive decay.
Half-life is the period of time during which the number of nuclei of a given radionuclide as a result of radioactive decay is halved. This value is used in the law of radioactive decay.
The activity of a radionuclide in accordance with the SI measurement system is measured in Becquerel (Bq) - named after the French physicist who discovered radioactivity in 1896), Henri Becquerel. One Bq is equal to 1 nuclear transformation per second. The power of the radioactive source is measured in Bq / s, respectively. The ratio of the activity of a radionuclide in a sample to the mass of a sample is called the specific activity of a radionuclide and is measured in Bq / kg (l).
What do we see on the display of modern dosimeters that measure AI? The ICRP proposed to measure the dose at a depth d equal to 10 mm to assess human exposure. The measured value of the dose at this depth is called the ambient dose equivalent, measured in sieverts (Sv). In fact, this is a calculated value, where the absorbed dose is multiplied by a weighting factor for a given type of radiation and a factor characterizing the sensitivity of various organs and tissues to a particular type of radiation.
The equivalent dose (or the often used term "dose") is equal to the product of the absorbed dose and the quality factor of exposure to ionizing radiation (for example: the quality factor of exposure to gamma radiation is 1, and alpha radiation is 20).
The unit of measure for the equivalent dose is rem (biological equivalent of an X-ray) and its sub-multiples: millirem (mrem) microrem (microrem), etc., 1 rem = 0.01 J / kg. The unit of measurement of the equivalent dose in the SI system is sievert, Sv,
1 Sv = 1 J / kg = 100 rem.
1 mrem = 1 * 10 -3 rem; 1 μrem = 1 * 10 -6 rem;
Absorbed dose - the amount of energy of ionizing radiation that is absorbed in an elementary volume, referred to the mass of matter in this volume.
The unit of the absorbed dose is rad, 1 rad = 0.01 J / kg.
The SI unit of absorbed dose is gray, Gy, 1 Gy = 100 rad = 1 J / kg
The equivalent dose rate (or dose rate) is the ratio of the equivalent dose to the time interval of its measurement (exposure), unit of measure rem / hour, Sv / hour, μSv / s, etc.
The amount of alpha and beta radiation is defined as the flux density of particles per unit area, per unit time - a-particles * min / cm 2, β-particles * min / cm 2.
Almost everything that surrounds us, even the person himself. Natural radioactivity is to some extent a natural human habitat, if it does not exceed natural levels. There are areas on the planet with an increased relative to the average level of the radiation background. However, in most cases, no significant deviations in the health status of the population are observed, since this territory is their natural habitat. An example of such a piece of land is, for example, the state of Kerala in India.
For a true assessment of the frightening figures that sometimes appear in print, one should distinguish:
As a rule, it is almost impossible to eliminate elements of natural radioactivity. How can you get rid of 40 K, 226 Ra, 232 Th, 238 U, which are everywhere in the earth's crust and are found in almost everything that surrounds us, and even in ourselves?
Of all natural radionuclides, the decay products of natural uranium (U-238) - radium (Ra-226) and radioactive gas radon (Ra-222) - pose the greatest danger to human health. The main "suppliers" of radium-226 to the environment are enterprises engaged in the extraction and processing of various fossil materials: mining and processing of uranium ores; oil and gas; coal industry; production of building materials; energy industry enterprises, etc.
Radium-226 is highly susceptible to leaching from uranium containing minerals. This property explains the presence of large amounts of radium in some types of groundwater (some of them enriched with radon gas are used in medical practice), in mine waters. The range of radium content in groundwater varies from a few to tens of thousands of Bq / L. The radium content in natural surface waters is much lower and can range from 0.001 to 1–2 Bq / L.
A significant component of natural radioactivity is the decay product of radium-226 - radon-222.
Radon is an inert, radioactive gas, colorless and odorless with a half-life of 3.82 days. Alpha emitter. It is 7.5 times heavier than air, therefore it mostly concentrates in cellars, basements, basements of buildings, in mine workings, etc.
It is believed that up to 70% of the exposure of the population to radiation is associated with radon in residential buildings.
The main source of radon intake in residential buildings are (as the importance increases):
In more detail about radon and a device for measuring it: RADON AND TORON RADIOMETERS.
Professional radon radiometers cost unaffordable money, for household use - we recommend that you pay attention to a household radon and thoron radiometer made in Germany: Radon Scout Home.
"Black sands" (the color varies from light yellow to red-brown, brown, there are varieties of white, greenish tint and black) are the mineral monazite - anhydrous phosphate of the elements of the thorium group, mainly cerium and lanthanum (Ce, La) PO 4 which are replaced by thorium. Monazite contains up to 50-60% of rare-earth oxides: yttrium oxide Y 2 O 3 up to 5%, thorium oxide ThO 2 up to 5-10%, sometimes up to 28%. Occurs in pegmatites, sometimes in granites and gneisses. When rocks containing monazite are destroyed, it is collected in placers, which are large deposits.
Placers of monazite sands existing on land, as a rule, do not significantly change the resulting radiation environment. But the deposits of monazite located near the coastal strip of the Sea of Azov (within the Donetsk region), in the Urals (Krasnoufimsk) and other regions create a number of problems associated with the possibility of irradiation.
For example, because of the sea surf during the autumn-spring period on the coast, as a result of natural flotation, a significant amount of "black sand" is accumulated, characterized by a high content of thorium-232 (up to 15-20 thousand Bq / kg and more), which creates in local areas, the levels of gamma radiation are of the order of 3.0 and more μSv / hour. Naturally, it is unsafe to rest in such areas, so this sand is collected every year, warning signs are displayed, and some parts of the coast are closed.
To measure the radiation levels and the content of radionuclides in different objects, special measuring instruments are used:
Currently, there are a large number of dosimeters of various types for solving various problems of radiation monitoring and having wide capabilities.
For example, dosimeters that are most often used in professional activities:
Information about detecting units and their application:
|
Detection unit name |
Measured radiation |
Main feature (technical specification) |
Application area |
|
OBD for alpha radiation |
Measurement range 3.4 · 10 -3 - 3.4 · 10 3 Bq · cm -2 |
DB for measuring the flux density of alpha particles from the surface |
|
|
OBD for beta radiation |
Measurement range 1 - 5 · 10 5 part./ (min · cm 2) |
DB for measuring the flux density of beta particles from the surface |
|
|
OBD for gamma radiation |
Sensitivity 350 cps -1 / μSvh -1 measurement range 0.03 - 300 μSv / h |
The best option for price, quality, specifications. It is widely used in the field of gamma radiation measurement. A good search block for detecting radiation sources. |
|
|
OBD for gamma radiation |
Measurement range 0.05 μSv / h - 10 Sv / h |
A detector unit with a very high upper threshold for measuring gamma radiation. |
|
|
OBD for gamma radiation |
Measurement range 1 mSv / h - 100 Sv / h Sensitivity 900 cps -1 / μSvh -1 |
An expensive detector with a high measuring range and excellent sensitivity. Used to locate radiation sources with strong radiation. |
|
|
X-ray OBD |
Energy range 5 - 160 keV |
X-ray detection unit. It is widely used in medicine and installations working with the release of low-energy X-rays. |
|
|
DB for neutron radiation |
measurement range 0.1 - 10 4 neutrons / (s cm 2) Sensitivity 1.5 (cps -1) / (neutron s -1 cm -2) |
||
|
OBD for alpha, beta, gamma and X-ray radiation |
Sensitivity 6.6 cps -1 / μSv h -1 |
A universal detector unit that allows you to measure alpha, beta, gamma and X-ray radiation. Low cost and poor sensitivity. I found wide reconciliation in the field of attestation of workplaces (AWP), where it is mainly required to measure a local object. |
2. Dosimeter-radiometer DKS-96- designed to measure gamma and X-ray radiation, alpha radiation, beta radiation, neutron radiation.
In many ways it is similar to a dosimeter-radiometer.
The two-channel scintillation beta-gamma spectrometer is designed for simultaneous and separate determination of:
Allows to provide express analysis of standardized samples of metal heats for the presence of radiation and contamination.
9. HPGe detector based gamma spectrometer Spectrometers based on coaxial detectors made of HPGe (highly pure germanium) are designed to register gamma radiation in the energy range from 40 keV to 3 MeV.
MKS-AT1315 beta and gamma radiation spectrometer
NaI PAK Lead Shielded Spectrometer
Portable NaI spectrometer MKS-AT6101
Wearable HPGe spectrometer Eco PAK
Portable HPGe spectrometer Eco PAK
Automotive NaI PAK spectrometer
Spectrometer MKS-AT6102
Eco PAK spectrometer with electromachine cooling
Handheld PPD spectrometer Eco PAK
Explore other measuring instruments to measure ionizing radiation, you can on our website:
At first glance, it is difficult to understand what is happening in the photograph. A giant mushroom seemed to grow from under the floor, and ghostly people in helmets seemed to be working next to it ...
There is something inexplicably creepy about this scene, and for a reason. This is the largest accumulation of possibly the most toxic substance ever created by man. This is nuclear lava or corium.
In the days and weeks after the Chernobyl nuclear power plant disaster on April 26, 1986, simply walking into a room with the same pile of radioactive material - she was somberly nicknamed "elephant's leg" - meant certain death in a few minutes. Even a decade later, when this photograph was taken, the film was probably behaving strangely due to radiation, which manifested itself in a characteristic grain structure. The person in the photo, Artur Korneev, most likely visited this room more often than anyone else, so he was exposed, perhaps, to the maximum dose of radiation.
Surprisingly, in all likelihood, he is still alive. The story of how the United States took possession of a unique photograph of a person in the presence of incredibly toxic material is shrouded in mystery in itself - as well as the reasons why someone would need to take a selfie next to a hump of molten radioactive lava.
The photograph first came to America in the late 90s, when the new government of newly independent Ukraine took control of the Chernobyl nuclear power plant and opened the Chernobyl Center for Nuclear Safety, Radioactive Waste and Radioecology. Soon, the Chernobyl Center invited other countries to cooperate in nuclear safety projects. The US Department of Energy has ordered assistance by sending an order to Pacific Northwest National Laboratories (PNNL), a crowded research facility in Richland, PA. Washington.
At the time, Tim Ledbetter was one of the newcomers to PNNL's IT department, and was tasked with creating a digital photo library for the DOE Nuclear Security Project, that is, to show the photographs to the American public (more precisely, for that tiny part of the public, which then had access to the Internet). He asked the project participants to take photographs during their trips to Ukraine, hired a freelance photographer, and also asked for materials from Ukrainian colleagues at the Chernobyl Center. Among hundreds of photographs of clumsy handshakes of officials and people in lab coats, however, there are a dozen photographs of the ruins inside the fourth power unit, where a decade earlier, on April 26, 1986, an explosion occurred during a test of a turbine generator.
As radioactive smoke rose above the village, poisoning the surrounding land, rods liquefied from below, melting through the walls of the reactor and forming a substance called corium.
When radioactive smoke rose above the village, poisoning the surrounding land, rods liquefied from below, melting through the walls of the reactor and forming a substance called corium .
Corium has formed outside research laboratories at least five times, says Mitchell Farmer, a lead nuclear engineer at Argonne National Laboratory, another US Department of Energy facility near Chicago. A corium once formed at the Three Mile Island reactor in Pennsylvania in 1979, once in Chernobyl, and three times during the meltdown of the Fukushima reactor in 2011. In his laboratory, Farmer created modified versions of the corium to better understand how to avoid similar incidents in the future. The study of the substance showed, in particular, that watering with water after the formation of the corium in reality prevents the decay of some elements and the formation of more dangerous isotopes.
Of the five cases of corium formation, only in Chernobyl nuclear lava was able to escape from the reactor. Without a cooling system, the radioactive mass crawled through the power unit for a week after the accident, absorbing molten concrete and sand, which were mixed with molecules of uranium (fuel) and zirconium (coating). This poisonous lava flowed downward, eventually melting the floor of the building. When inspectors finally entered the power unit a few months after the accident, they found an 11-ton, three-meter-long landslide in the corner of the steam distribution corridor below. Then it was called "elephant's leg". Over the next years, the "elephant leg" was cooled and crushed. But even today, its remnants are still several degrees warmer than the environment, as the decay of radioactive elements continues.
Ledbetter cannot remember exactly where he obtained these photographs. He put together a photo library nearly 20 years ago, and the website where they are hosted is still in good shape; only small copies of images were lost. (Ledbetter, still at PNNL, was surprised to learn that the photos are still available online.) But he remembers for sure that he did not send anyone to photograph the "elephant's leg", so it was most likely sent by one of his Ukrainian colleagues.
The photo began to circulate on other sites, and in 2013 Kyle Hill came across it when he was writing an article about the "elephant's leg" for Nautilus magazine. He traced her origins back to the PNNL lab. A long-lost description of the photo was found on the site: "Artur Korneev, deputy director of the Shelter, is studying nuclear lava" elephant's leg ", Chernobyl. Photographer: unknown. Autumn 1996". Ledbetter confirmed that the description matched the photograph.
Arthur Korneev- an inspector from Kazakhstan, who was engaged in the education of employees, telling and protecting them from the "elephant's leg" since its formation after the explosion at the Chernobyl nuclear power plant in 1986, a gloomy joke lover. Most likely, the last to speak to him was the NY Times reporter in 2014 in Slavutich, a city specially built for evacuated personnel from Pripyat (Chernobyl).
The photo was probably taken with a slower shutter speed than other photos to allow the photographer to appear in the frame, which explains the effect of movement and why the headlamp looks like lightning. The graininess in the photo is probably caused by radiation.
For Korneev, this particular visit to the power unit was one of several hundred dangerous trips to the core since his first day of operation in the days following the explosion. His first assignment was to detect fuel deposits and help measure radiation levels (the "elephant's leg" initially "glowed" at more than 10,000 roentgens per hour, which kills a person at a distance of a meter in less than two minutes). Shortly thereafter, he led a clean-up operation, when whole chunks of nuclear fuel sometimes had to be removed from the path. More than 30 people died from acute radiation sickness during the cleaning of the power unit. Despite the incredible dose of radiation received, Korneev himself continued to return to the hastily constructed concrete sarcophagus again and again, often with journalists to shield them from danger.
In 2001, he took an Associated Press reporter to the core, where radiation levels were 800 roentgens per hour. In 2009, renowned fictional writer Marcel Theroux wrote an article for Travel + Leisure about his trip to the sarcophagus and about a crazy escort without a gas mask who mocked Teru’s fears and said it was "pure psychology." Although Theroux referred to him as Viktor Korneev, Arthur was in all likelihood the person, since he dropped the same black jokes a few years later with a journalist from the NY Times.
His current occupation is unknown. When the Times found Korneev a year and a half ago, he was helping build the vault for the sarcophagus, a $ 1.5 billion project due to be completed in 2017. It is planned that the vault will completely close the Vault and prevent isotope leakage. In his 60-something years, Korneev looked sickly, suffered from cataracts, and was banned from visiting the sarcophagus after repeated exposure in previous decades.
However, Korneev's sense of humor remained unchanged... He seems to have no regrets about his life's work: "Soviet radiation," he jokes, "is the best radiation in the world." .
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 in 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 1, and for alpha radiation - 20. That is, with the same absorbed dose, alpha radiation will cause the body 20 times more harm 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 in units of mass (gram, milligram, etc.), but also in 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.
Radiation appears before us in the form
"An invisible, insidious and deadly enemy, lurking at every turn."
You cannot see it, you cannot touch it, it is invisible ..
This causes a certain awe and horror in people, especially in the absence of understanding what exactly it is ..
A clearer idea of what radiation is,
you will have about the household danger of radiation and radioactivity by reading this article ..
RADIOACTIVITY, RADIATION AND RADIATION BACKGROUND:
1. WHAT IS RADIOACTIVITY AND RADIATION.
Radioactivity is the 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, is 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.
2. WHAT IS RADIATION?
There are several types of radiation:
- Alpha particles: relatively heavy, positively charged particles, which are helium nuclei.
“Beta particles are just electrons.
- Gamma radiation has the same electromagnetic nature as visible light, but it has a much higher penetrating power.
- Neutrons are electrically neutral particles that arise mainly in the immediate vicinity of an operating nuclear reactor, where access, of course, is regulated.
X-rays are similar to gamma rays but have lower energy. By the way, our Sun is one of the natural sources of X-ray radiation, but the earth's atmosphere provides reliable protection from it.
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, any, even a very thin layer of a solid or liquid substance is sufficient protection against alpha and beta radiation - for example, ordinary clothing (if, of course, the radiation source is outside).
* A distinction should be made between radioactivity and radiation.
Sources of radiation - radioactive substances or nuclear technical installations
(reactors, accelerators, X-ray equipment, etc.) - can exist for a considerable time,
and radiation exists only up to the moment of its absorption in any substance.
3. WHAT CAN HUMAN EXPOSURE TO RADIATION?
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 often mentioned genetic (i.e. inherited) mutations as a result of human exposure, they have never been found.
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 the chemical and steel industries, not to mention the fact that the mechanism of malignant degeneration of tissues from external influences is still unknown to science.
4. HOW CAN RADIATION GET INTO THE BODY?
The human body reacts to radiation, not to its source. 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.
5. IS RADIATION TRANSMITTED AS A DISEASE?
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 "stain" your 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.
The transfer of dirt leads to its rapid dilution to safe limits, in contrast to the disease, which, being transmitted from person to person, reproduces its harmful power (and can even lead to an epidemic)
6. IN WHAT UNITS IS THE RADIOACTIVITY MEASURED?
Activity is a measure of radioactivity.
It is measured in Becquerels (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 (Ki).
This is a huge value: 1 Ci = 37,000,000,000 Bq.
The activity of a radioactive source characterizes its power. So, in a source with an activity of 1 Curie, 37,000,000,000 decays per second occur.
As mentioned above, during these decays, the source emits ionizing radiation.
The exposure dose is a measure of the ionization effect of this radiation on a substance.
It is often measured in X-rays (R).
Since 1 Roentgen is a rather large value, in practice it is more convenient to use the millionth (μR) or thousandth (mR) parts of the Roentgen.
The action of common household dosimeters is based on the measurement of ionization over a certain time, that is, the exposure dose rate.
The unit of measurement of the exposure dose rate is micro-roentgen / hour.
The dose rate times the time is called the 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 of equivalent dose and equivalent dose rate are used. Measured, respectively, in Sieverts (Sv) and Sieverts / hour.
In everyday life, we can assume that 1 Sievert = 100 Roentgens.
It is necessary to indicate to which organ, part or the whole body the given dose fell.
It can be shown that the above-mentioned point source with activity 1 Curie,
(for definiteness, we consider a cesium-137 source), at a distance of 1 meter from ourselves it creates an exposure dose rate of approximately 0.3 Roentgen / hour, and at a distance of 10 meters - approximately 0.003 Roentgen / hour.
A decrease in the dose rate with an increase in the distance from the source always occurs and is due to the laws of radiation propagation.
Now the typical error of the mass media is absolutely clear: "Today, a radioactive source of 10 thousand roentgens at a rate of 20 was discovered on such and such a street."
* Firstly, the dose is measured in X-rays, and the characteristic of the source is 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.
* Second, 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-roentgens / hour, it can be assumed that
that in this case we are talking about 10 thousand microRentgen / 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 100r-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 readings of a dosimeter in a city, i.e. 20 micro-roentgen / hour.
By the way, there is no such norm.
Therefore, the correct message should apparently look like this:
“Today, a radioactive source has been found on such and such a street, close to which the dosimeter shows 10 thousand microroentgens per hour, while the average value of the background radiation in our city does not exceed 20 microroentgens per hour.”
7. WHAT ARE ISOTOPES?
There are more than 100 chemical elements in the periodic table.
Almost each of them is represented by a mixture of stable and radioactive atoms, which are called isotopes of this element.
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.
8. WHAT IS A HALF-TIME PERIOD?
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.
The following interpretation of the concept of "half-life" is absolutely erroneous:
"If a radioactive substance has a half-life of 1 hour, this means that after 1 hour its first half will decay, and after another 1 hour, the second half, and this substance will completely disappear (decay)."
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.
Each radionuclide has its own half-life, it can be either fractions of a second or billions of years. It is important that the half-life of a given radionuclide is constant and cannot be changed.
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.
BY ORIGIN, RADIOACTIVITY IS DIVIDED INTO NATURAL (natural) AND MAN-GENERAL:
9. WHAT IS RADIOACTIVE AROUND US?
(Human exposure to certain radiation sources will help to assess diagram 1 - see the figure below)
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.
b) RADON (makes a significant contribution to human exposure, both itself and its decay products)
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.
Diagram 2 will help you compare the radiation power of different radon sources.
(see figure below - Comparative power of different sources of radon)
c) MAN-GENERAL 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, testing of nuclear weapons (NW), atomic energy and industrial enterprises make their contribution.
* Of course, accidental (uncontrolled) spread of radioactive sources is also possible: accidents, losses, theft, spraying, etc.
Such situations, fortunately, 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.
10. RADIATION SITUATION IN RUSSIA?
The radiation situation in different regions of Russia is covered in the state annual document "On the state of the natural environment in the Russian Federation".
Information on the radiation situation in individual regions is also available. 
11 .. HOW DO FREQUENTLY COMMUNICATED RADIOACTIVE OBJECTS LIKE?
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.
The situation is similar in St. Petersburg.
In addition, individual objects shown in the figures can be carriers of radioactivity. attached to the article (see description under the pictures), namely:
Radioactive switch (toggle switch):
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. The dose rate for measurements "point-blank" is about 2 milliRentgen / hour.
Aviation clock ASF with radioactive dial:
Watch with dial and hands, manufactured before 1962, fluorescent thanks to radioactive paint. The dose rate near the clock is about 300 micro-roentgen / hour.
- Radioactive pipes from scrap metal:
Cuts of stainless steel spent pipes used in technological processes at the nuclear industry, but somehow ended up in scrap metal. The dose rate can be quite significant.
- Portable container with a radiation source inside:
A portable lead container that may contain a miniature metal capsule containing a radioactive source (for example, cesium-137 or cobalt-60). The dose rate from a source without a container can be very high.
12 .. IS THE COMPUTER A SOURCE OF RADIATION?
The only parts of the computer that can be considered radiation are only cathode ray tube (CRT) monitors;
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, with regard to monitors, the Swedish national standards "MPR II", "TCO-92", -95, -99 are generally recognized for all manufacturers. 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 only to him to reduce the radiation. The less common term "low emission" has a similar meaning.
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 / hour,
those. with a threefold margin, it was within the permissible norm (100 μR / hour).
13. WHAT IS NORMAL RADIATION BACKGROUND or NORMAL RADIATION LEVEL?
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 location, 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's foot has stepped",
the background radiation changes from point to point, as well as at each specific point with 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 make it possible to indicate
TYPICAL VALUES OF THE BACKGROUND ON THE STREET (open area) - 8 - 12 microR / hour,
INDOOR - 15 - 20 microR / hour.
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)
14 .. WHAT ARE THE STANDARDS OF RADIOACTIVITY?
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. by 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 "Standards of radiation safety (NRB-99). 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, 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 constructed 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).
* GOST 30108-94 also applies:
"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
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.
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 EQUIPMENT
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 electronic computers and work organization" (SanPiN 2.2.2 / 2.4.1340-03).
15. HOW TO PROTECT FROM RADIATION? DOES ALCOHOL HELP FROM RADIATION?
They are protected from the source of radiation by time, distance and substance.
- Time - due to the fact that the shorter the time spent near the radiation source, the lower the radiation dose received from it.
- Distance - due to the fact that the radiation decreases with distance from the compact source (in proportion to the square of the distance).
If at a distance of 1 meter from the radiation source the dosimeter records 1000 μR / hour,
then already at a distance of 5 meters the readings will drop to approximately 40 μR / hour.
- Substance - it is necessary to strive so that between you and the radiation source there is as much substance as possible: the more it is and the denser it is, the greater part of the radiation it will absorb.
* Regarding the main source of indoor radiation - radon and its decay products,
This regular ventilation can significantly reduce its dose load.
* In addition, if we are talking about the construction or decoration of your own home, which will probably last more than one generation, you should try to buy radiation-safe building materials - since their range 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.
* There are also folk recipes that help fight and cleanse the body of radiation.
you will find out from them today)
16. WHEN TO THINK ABOUT RADIATION?
In everyday, peaceful life, it is extremely unlikely that you will encounter a source of radiation that poses an immediate threat to health.
in places where radiation sources and local radioactive contamination are most likely to be detected - (dumps, pits, scrap metal yards).
Nevertheless, it is in everyday life that radioactivity should be remembered.
It's useful to do this:
When buying an apartment, house, land,
- when planning construction and finishing works,
- when choosing and purchasing building and finishing materials for an apartment or house,
as well as materials for the improvement of the territory around the house (soil of bulk lawns, bulk coverings for tennis courts, paving slabs and paving stones, etc.).
- in addition, we must always remember about the probability of BP
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 in 26th place, and the first two places are occupied by heavy metals and chemical toxins.
MEANS AND METHODS OF MEASURING RADIATION
After the Chernobyl accident, the topic of radiation has ceased to be of interest only to a narrow circle of specialists.
Many people have become more worried about the danger it can carry. Now it is no longer possible to be completely sure of the purity of foodstuffs that are sold in markets and shops, as well as the safety of water in natural sources.
This measuring device has ceased to be exotic and has become one of the household devices that helps to determine the safety of being in a particular place, as well as the "norm" (in this area) of the acquired building materials, things, products, etc.
so let's figure it out
1. WHAT THE DOSIMETER MEASURES AND WHAT DOES NOT MEASURE.
The dosimeter measures the dose rate of ionizing radiation directly in the place where it is located.
The main purpose of a household dosimeter is to measure the dose rate in the place where this dosimeter is located (in the hands of a person, on the ground, etc.) and thereby check suspicious objects for radioactivity.
However, you will most likely only be able to notice quite serious increases in the dose rate.
Therefore, an individual dosimeter will help first of all those who often visit areas contaminated as a result of the Chernobyl accident (as a rule, all these places are well known).
In addition, such a device can be useful in an unfamiliar area remote from civilization (for example, when picking berries and mushrooms in rather "wild" places), when choosing a place for building a house, for preliminary checking of imported soil for landscape improvement.
We repeat, however, that in these cases it will be useful only with very significant radioactive contamination, which are rare.
Not very strong, but, nevertheless, unsafe contamination with a household dosimeter is very difficult to detect. This requires completely different methods that only specialists can use.
With regard to the possibility of checking the compliance of the radiation parameters with the established standards using a household dosimeter, the following can be said.
Dose indicators (dose rate in rooms, dose rate on the ground) for individual points can be checked. However, it is very difficult for a household dosimeter to inspect the entire room and make sure that a local source of radioactivity has not been missed.
It is almost useless to try to measure the radioactivity of food or building materials with a household dosimeter.
The dosimeter is capable of detecting only VERY HIGHLY contaminated products or building materials, the content of radioactivity in which is ten times higher than the permissible standards.
Let us remind that for products and building materials it is not the dose rate that is normalized, but the content of radionuclides, and the dosimeter, in principle, does not allow measuring this parameter.
Here, again, other methods and the work of specialists are needed.
2. HOW TO USE THE DOSIMETER CORRECTLY?
Use the dosimeter in accordance with the instructions supplied with it.
It is also necessary to take into account that during any measurements of radiation there is a natural background radiation.
Therefore, first, the dosimeter measures the background level characteristic of a given area of the terrain (at a sufficient distance from the alleged source of radiation), after which measurements are performed in the presence of the alleged source of radiation.
The presence of a stable excess over the background level may indicate the detection of radioactivity.
The fact that the readings of the dosimeter in the apartment are 1.5 - 2 times higher than on the street is not unusual.
In addition, it should be borne in mind that when measuring at the "background level" in the same place, the device can show, for example, 8, 15 and 10 μR / h.
Therefore, to obtain a reliable result, it is recommended to take several measurements and then calculate the arithmetic mean. In our example, the average will be (8 + 15 + 10) / 3 = 11 μR / hour.
3. WHAT ARE DOSIMETERS?
* On sale you can find both household and professional dosimeters.
The latter have a number of fundamental advantages. However, these devices are very expensive (ten or more times more expensive than a household dosimeter), and situations where these advantages can be realized are extremely rare in everyday life. Therefore, you need to purchase a household dosimeter.
Special mention should be made of radiometers for measuring radon activity: although they are only in professional design, their use in everyday life can be justified.
* The vast majority of dosimeters are direct reading, i.e. with their help, you can get the result immediately after measurement.
There are also indirect-reading dosimeters that do not have any power supply and indication devices, extremely compact (often in the form of a key fob).
Their purpose is individual dosimetric control at radiation-hazardous facilities and in medicine.
Since such a dosimeter can be recharged or read out only with the help of special stationary equipment, it cannot be used to make operational decisions.
* Dosimeters are non-threshold and threshold. The latter make it possible to detect only the excess of the standardized radiation level established by the manufacturer on the "yes-no" principle and due to this they are simple and reliable in operation, cost about 1.5 - 2 times cheaper than non-threshold ones.
As a rule, thresholdless dosimeters can also be operated in the threshold mode.
4. HOUSEHOLD DOSIMETERS MAINLY DIFFER IN THE FOLLOWING PARAMETERS:
- types of registered radiation - only gamma, or gamma and beta;
- type of detection unit - gas-discharge counter (also known as Geiger counter) or scintillation crystal / plastic; the number of gas-discharge meters varies from 1 to 4;
- placement of the detecting unit - external or built-in;
- the presence of a digital and / or sound indicator;
- time of one measurement - from 3 to 40 seconds;
- the presence of certain modes of measurement and self-diagnostics;
- dimensions and weight;
- price, depending on the combination of the above parameters.
5. WHAT TO DO IF THE DOSIMETER "SCALE" OR ITS RELEASE IS UNUSUALLY LARGE?
- Make sure that when you move the dosimeter away from the place where it "rolls over", the readings of the device return to normal.
- Make sure that the dosimeter is in good working order (most devices of this kind have a special self-diagnosis mode).
- The normal operation of the electrical circuit of the dosimeter can be partially or completely disturbed by short circuits, battery leaks, strong external electromagnetic fields. If possible, it is advisable to duplicate measurements with another dosimeter, preferably a different type.
If you are sure that you have found a source or site of radioactive contamination, IN NO EVENT should you try to get rid of it yourself (throw it away, bury it or hide it).
You should somehow designate the place of your find, and be sure to report it to the services, whose duties include the detection, identification and disposal of orphan radioactive sources.
6. WHERE TO CALL IF A HIGH LEVEL OF RADIATION IS DETECTED?
Main Directorate of the Ministry of Emergency Situations of the Russian Federation in the Republic of Sakha (Yakutia), operational duty officer: tel: / 4112 / 42-49-97
- Office of the Federal Service for Supervision of Consumer Rights Protection and Human Wellbeing in the Republic of Sakha (Yakutia) tel: / 4112 / 35-16-45, fax: / 4112 / 35-09-55
-Territorial bodies of the Ministry of Nature Protection of the Republic of Sakha (Yakutia)
(find out the phone numbers in advance for such cases in your region)
7. WHEN IS IT WORTH TO CONTACT A SPECIALIST TO MEASURE RADIATION?
Approaches like "Radioactivity is very simple!" or "Do-it-yourself dosimetry" do not justify themselves. In most cases, a layman cannot correctly interpret the number displayed on the dosimeter display as a result of the measurement. Accordingly, he cannot independently make a decision on the radiation safety of a suspicious object, next to which this measurement was carried out.
An exception is the situation when the dosimeter showed a very large number. Everything is clear here: move farther away, check the dosimeter readings far from the place of the abnormal reading and, if the readings have become normal, then, without returning to the "bad place", quickly notify the appropriate services.
Specialists (in appropriately accredited laboratories) must be contacted in cases where an OFFICIAL conclusion is required on the compliance of a particular product with the current radiation safety standards.
Such conclusions are mandatory for products that can concentrate radioactivity from the place of growth: berries and dried mushrooms, honey, medicinal herbs. At the same time, for commercial batches of products, radiation monitoring will cost the seller only a fraction of a percent of the batch cost.
When buying a land plot or apartment, it does not hurt to make sure that their natural radioactivity complies with the current standards, as well as that there is no man-made radiation pollution.
If you still decide to buy yourself an individual household dosimeter, take this issue seriously. 
(Laboratory of radiation monitoring LRK-1 MEPhI)
