Ionizing radiations are such types of radiant energy that, getting into certain media or penetrating through them, produce ionization in them. Such properties are possessed by radioactive radiation, high-energy radiation, x-rays, etc.

The widespread use of atomic energy for peaceful purposes, various accelerators and X-ray apparatus for various purposes has led to the prevalence of ionizing radiation in the national economy and the huge, ever-increasing contingents of people working in this field.

Types of ionizing radiation and their properties

The most diverse types of ionizing radiation are the so-called radioactive radiation, which is formed as a result of spontaneous radioactive decay of atomic nuclei of elements with a change in the physical and chemical properties of the latter. Elements that have the ability to decay radioactively are called radioactive; they can be natural, such as uranium, radium, thorium, etc. (about 50 elements in total), and artificial, for which radioactive properties are obtained artificially (more than 700 elements).

In radioactive decay, there are three main types of ionizing radiation: alpha, beta and gamma.

An alpha particle is a positively charged helium ion formed during the decay of nuclei, as a rule, of heavy natural elements (radium, thorium, etc.). These rays do not penetrate deep into solid or liquid media, therefore, to protect against external influence, it is enough to protect yourself with any thin layer, even a piece of paper.

Beta radiation is a stream of electrons produced during the decay of the nuclei of both natural and artificial radioactive elements. Beta radiation has a greater penetrating power compared to alpha rays, therefore, denser and thicker screens are required to protect against them. A variety of beta radiation generated during the decay of some artificial radioactive elements are. positrons. They differ from electrons only in their positive charge, therefore, when exposed to a magnetic field, they are deflected in the opposite direction.

Gamma radiation, or energy quanta (photons), are hard electromagnetic oscillations generated during the decay of the nuclei of many radioactive elements. These rays have a much greater penetrating power. Therefore, for shielding from them, special devices are needed made of materials that can well retain these rays (lead, concrete, water). The ionizing effect of gamma radiation is mainly due to both the direct consumption of its own energy and the ionizing effect of electrons knocked out of the irradiated substance.

X-ray radiation is produced during the operation of X-ray tubes, as well as complex electronic installations (betatrons, etc.). In nature, X-rays are in many ways similar to gamma rays and differ from them in origin and sometimes in wavelength: X-rays, as a rule, have a longer wavelength and lower frequencies than gamma rays. Ionization due to the action of X-rays occurs to a greater extent due to the electrons knocked out by them and only slightly due to the direct expenditure of its own energy. These rays (especially hard ones) also have a significant penetrating power.

Neutron radiation is a stream of neutral, that is, uncharged particles of neutrons (n), which are an integral part of all nuclei, with the exception of the hydrogen atom. They do not have charges, therefore they themselves do not have an ionizing effect, however, a very significant ionizing effect occurs due to the interaction of neutrons with the nuclei of the irradiated substances. Substances irradiated by neutrons can acquire radioactive properties, that is, receive the so-called induced radioactivity. Neutron radiation is produced during the operation of elementary particle accelerators, nuclear reactors, etc. Neutron radiation has the highest penetrating power. Neutrons are delayed by substances containing hydrogen in their molecule (water, paraffin, etc.).

All types of ionizing radiation differ from each other in various charges, mass and energy. Differences also exist within each type of ionizing radiation, causing a greater or lesser penetrating and ionizing ability and their other features. The intensity of all types of radioactive exposure, as with other types of radiant energy, is inversely proportional to the square of the distance from the radiation source, that is, if the distance doubles or triples, the intensity of exposure decreases by 4 and 9 times, respectively.

Radioactive elements can be present as solids, liquids, and gases, therefore, in addition to their specific property of radiation, they have the corresponding properties of these three states; they can form aerosols, vapors, spread in the air, contaminate surrounding surfaces, including equipment, overalls, workers' skin, etc., penetrate the digestive tract and respiratory organs.

In everyday life, ionizing radiation is constantly encountered. We do not feel them, but we cannot deny their impact on animate and inanimate nature. Not so long ago, people learned to use them both for good and as weapons of mass destruction. With proper use, these radiations can change the life of mankind for the better.

Types of ionizing radiation

To understand the peculiarities of the influence on living and non-living organisms, you need to find out what they are. It is also important to know their nature.

Ionizing radiation is a special wave that can penetrate through substances and tissues, causing ionization of atoms. There are several types of it: alpha radiation, beta radiation, gamma radiation. All of them have a different charge and ability to act on living organisms.

Alpha radiation is the most charged of all types. It has tremendous energy, capable of causing radiation sickness even in small doses. But with direct irradiation, it penetrates only into the upper layers of human skin. Even a thin sheet of paper protects against alpha rays. At the same time, getting into the body with food or with inhalation, the sources of this radiation quickly become the cause of death.

Beta rays carry a slightly lower charge. They are able to penetrate deep into the body. With prolonged exposure, they cause death of a person. Smaller doses cause a change in the cellular structure. A thin sheet of aluminum can serve as protection. Radiation from within the body is also deadly.

The most dangerous is considered to be gamma radiation. It penetrates through the body. In large doses, it causes radiation burns, radiation sickness, and death. The only protection against it can be lead and a thick layer of concrete.

X-rays are considered to be a special kind of gamma radiation, which are generated in an X-ray tube.

Research History

For the first time, the world learned about ionizing radiation on December 28, 1895. It was on this day that Wilhelm K. Roentgen announced that he had discovered a special kind of rays that could pass through various materials and the human body. From that moment, many doctors and scientists began to actively work with this phenomenon.

For a long time, no one knew about its effect on the human body. Therefore, in history there are many cases of death from excessive exposure.

The Curies have studied in detail the sources and properties that ionizing radiation has. This made it possible to use it with maximum benefit, avoiding negative consequences.

Natural and artificial sources of radiation

Nature has created a variety of sources of ionizing radiation. First of all, it is the radiation of sunlight and space. Most of it is absorbed by the ozone layer, which is high above our planet. But some of them reach the surface of the Earth.

On the Earth itself, or rather in its depths, there are some substances that produce radiation. Among them are isotopes of uranium, strontium, radon, cesium and others.

Artificial sources of ionizing radiation are created by man for a variety of research and production. At the same time, the strength of radiation can be many times higher than natural indicators.

Even in conditions of protection and compliance with safety measures, people receive doses of radiation that are hazardous to health.

Units of measurement and doses

Ionizing radiation is usually correlated with its interaction with the human body. Therefore, all units of measurement are somehow related to the ability of a person to absorb and accumulate ionization energy.

In the SI system, doses of ionizing radiation are measured in units called grays (Gy). It shows the amount of energy per unit of irradiated substance. One Gy equals one J/kg. But for convenience, the off-system unit rad is more often used. It is equal to 100 Gr.

The radiation background on the ground is measured by exposure doses. One dose is equal to C/kg. This unit is used in the SI system. The off-system unit corresponding to it is called the roentgen (R). To obtain an absorbed dose of 1 rad, one must succumb to an exposure dose of about 1 R.

Since different types of ionizing radiation have a different charge of energy, its measurement is usually compared with biological influence. In the SI system, the unit of such an equivalent is the sievert (Sv). Its off-system counterpart is rem.

The stronger and longer the radiation, the more energy absorbed by the body, the more dangerous its influence. To find out the allowable time for a person to stay in radiation pollution, special devices are used - dosimeters that measure ionizing radiation. These are both devices for individual use, and large industrial installations.

Effect on the body

Contrary to popular belief, any ionizing radiation is not always dangerous and deadly. This can be seen in the example of ultraviolet rays. In small doses, they stimulate the generation of vitamin D in the human body, cell regeneration and an increase in melanin pigment, which gives a beautiful tan. But prolonged exposure causes severe burns and can cause skin cancer.

In recent years, the effect of ionizing radiation on the human body and its practical application has been actively studied.

In small doses, radiation does not cause any harm to the body. Up to 200 milliroentgens can reduce the number of white blood cells. The symptoms of such exposure will be nausea and dizziness. About 10% of people die after receiving such a dose.

Large doses cause digestive upset, hair loss, skin burns, changes in the cellular structure of the body, the development of cancer cells and death.

Radiation sickness

Prolonged action of ionizing radiation on the body and its receipt of a large dose of radiation can cause radiation sickness. More than half of the cases of this disease are fatal. The rest become the cause of a number of genetic and somatic diseases.

At the genetic level, mutations occur in germ cells. Their changes become evident in the next generations.

Somatic diseases are expressed by carcinogenesis, irreversible changes in various organs. Treatment of these diseases is long and rather difficult.

Treatment of radiation injuries

As a result of the pathogenic effects of radiation on the body, various lesions of human organs occur. Depending on the dose of radiation, different methods of therapy are carried out.

First of all, the patient is placed in a sterile ward to avoid the possibility of infection of open affected skin areas. Further, special procedures are carried out that contribute to the rapid removal of radionuclides from the body.

For severe lesions, a bone marrow transplant may be needed. From radiation, it loses the ability to reproduce red blood cells.

But in most cases, the treatment of mild lesions comes down to anesthesia of the affected areas, stimulating cell regeneration. Much attention is paid to rehabilitation.

Impact of ionizing radiation on aging and cancer

In connection with the influence of ionizing rays on the human body, scientists conducted various experiments proving the dependence of the processes of aging and carcinogenesis on the dose of radiation.

Groups of cell cultures were irradiated under laboratory conditions. As a result, it was possible to prove that even slight irradiation contributes to the acceleration of cell aging. Moreover, the older the culture, the more it is subject to this process.

Prolonged irradiation leads to cell death or abnormal and rapid division and growth. This fact indicates that ionizing radiation has a carcinogenic effect on the human body.

At the same time, the impact of waves on the affected cancer cells led to their complete death or to a stop in their division processes. This discovery helped develop a technique for treating human cancers.

Practical applications of radiation

For the first time, radiation began to be used in medical practice. With the help of X-rays, doctors managed to look inside the human body. At the same time, almost no harm was done to him.

Further, with the help of radiation, they began to treat cancer. In most cases, this method has a positive effect, despite the fact that the entire body is exposed to a strong effect of radiation, which entails a number of symptoms of radiation sickness.

In addition to medicine, ionizing rays are used in other industries. Surveyors using radiation can study the structural features of the earth's crust in its individual sections.

The ability of some fossils to release a large amount of energy, humanity has learned to use for its own purposes.

Nuclear power

Nuclear energy is the future of the entire population of the Earth. Nuclear power plants are sources of relatively inexpensive electricity. Provided that they are properly operated, such power plants are much safer than thermal power plants and hydroelectric power plants. From nuclear power plants, there is much less environmental pollution, both with excess heat and production waste.

At the same time, on the basis of atomic energy, scientists developed weapons of mass destruction. At the moment, there are so many atomic bombs on the planet that the launch of a small number of them can cause a nuclear winter, as a result of which almost all living organisms that inhabit it will die.

Means and methods of protection

The use of radiation in everyday life requires serious precautions. Protection against ionizing radiation is divided into four types: time, distance, number and shielding of sources.

Even in an environment with a strong radiation background, a person can stay for some time without harm to his health. It is this moment that determines the protection of time.

The greater the distance to the radiation source, the lower the dose of absorbed energy. Therefore, close contact with places where there is ionizing radiation should be avoided. This is guaranteed to protect against unwanted consequences.

If it is possible to use sources with minimal radiation, they are given preference in the first place. This is protection by quantity.

Shielding, on the other hand, means creating barriers through which harmful rays do not penetrate. An example of this is the lead screens in x-ray rooms.

household protection

In the event of a radiation disaster being declared, all windows and doors should be immediately closed, and try to stock up on water from closed sources. Food should only be canned. When moving in an open area, cover the body as much as possible with clothing, and the face with a respirator or wet gauze. Try not to bring outerwear and shoes into the house.

It is also necessary to prepare for a possible evacuation: collect documents, a supply of clothes, water and food for 2-3 days.

Ionizing radiation as an environmental factor

There are quite a lot of areas contaminated with radiation on planet Earth. The reason for this is both natural processes and man-made disasters. The most famous of them are the Chernobyl accident and the atomic bombs over the cities of Hiroshima and Nagasaki.

In such places, a person cannot be without harm to his own health. At the same time, it is not always possible to find out in advance about radiation pollution. Sometimes even a non-critical radiation background can cause a disaster.

The reason for this is the ability of living organisms to absorb and accumulate radiation. At the same time, they themselves turn into sources of ionizing radiation. The well-known "black" jokes about Chernobyl mushrooms are based precisely on this property.

In such cases, protection against ionizing radiation is reduced to the fact that all consumer products are subject to careful radiological examination. At the same time, there is always a chance to buy the famous "Chernobyl mushrooms" in spontaneous markets. Therefore, you should refrain from buying from unverified sellers.

The human body tends to accumulate dangerous substances, resulting in a gradual poisoning from the inside. It is not known when exactly the effects of these poisons will make themselves felt: in a day, a year or a generation.

"People's attitude to this or that danger is determined by how well it is familiar to them."

This material is a generalized answer to numerous questions that arise from users of devices for detecting and measuring radiation in the home.
The minimal use of the specific terminology of nuclear physics in the presentation of the material will help you to freely navigate this environmental problem, without succumbing to radiophobia, but also without excessive complacency.

The danger of RADIATION real and imaginary

"One of the first naturally occurring radioactive elements discovered was called 'radium'"
- translated from Latin - emitting rays, radiating.

Each person in the environment lies in wait for various phenomena that affect him. These include heat, cold, magnetic and ordinary storms, heavy rains, heavy snowfalls, strong winds, sounds, explosions, etc.

Due to the presence of the sense organs assigned to him by nature, he can quickly respond to these phenomena with the help of, for example, a sunshade, clothing, housing, medicines, screens, shelters, etc.

However, in nature there is a phenomenon to which a person, due to the lack of the necessary sense organs, cannot instantly react - this is radioactivity. Radioactivity is not a new phenomenon; radioactivity and its accompanying radiation (the so-called ionizing radiation) have always existed in the Universe. Radioactive materials are part of the Earth, and even a person is slightly radioactive, because. Every living tissue contains trace amounts of radioactive substances.

The most unpleasant property of radioactive (ionizing) radiation is its effect on the tissues of a living organism, therefore, appropriate measuring instruments are needed that would provide operational information for making useful decisions before a long time passes and undesirable or even fatal consequences appear. will not begin to feel immediately, but only after some time has passed. Therefore, information about the presence of radiation and its power must be obtained as early as possible.
But enough of the mysteries. Let's talk about what radiation and ionizing (i.e. radioactive) radiation are.

ionizing radiation

Any environment consists of the smallest neutral particles - atoms, which consist of positively charged nuclei and negatively charged electrons surrounding them. Each atom is like a miniature solar system: around a tiny nucleus, “planets” move in orbits - electrons.
atom nucleus consists of several elementary particles - protons and neutrons held by nuclear forces.

Protons particles with a positive charge equal in absolute value to the charge of electrons.

Neutrons neutral, uncharged particles. The number of electrons in an atom is exactly equal to the number of protons in the nucleus, so each atom is neutral as a whole. The mass of a proton is almost 2000 times the mass of an electron.

The number of neutral particles (neutrons) present in the nucleus can be different for the same number of protons. Such atoms, having nuclei with the same number of protons, but differing in the number of neutrons, are varieties of the same chemical element, called "isotopes" of this element. To distinguish them from each other, a number equal to the sum of all particles in the nucleus of a given isotope is assigned to the element symbol. So uranium-238 contains 92 protons and 146 neutrons; Uranium 235 also has 92 protons, but 143 neutrons. All isotopes of a chemical element form a group of "nuclides". Some nuclides are stable, i.e. do not undergo any transformations, while others emitting particles are unstable and turn into other nuclides. As an example, let's take an atom of uranium - 238. From time to time, a compact group of four particles escapes from it: two protons and two neutrons - "an alpha particle (alpha)". Uranium-238 is thus converted into an element whose nucleus contains 90 protons and 144 neutrons - thorium-234. But thorium-234 is also unstable: one of its neutrons turns into a proton, and thorium-234 turns into an element with 91 protons and 143 neutrons in its nucleus. This transformation also affects the electrons moving in their orbits (beta): one of them becomes, as it were, superfluous, without a pair (proton), so it leaves the atom. A chain of numerous transformations, accompanied by alpha or beta radiation, ends with a stable lead nuclide. Of course, there are many similar chains of spontaneous transformations (decays) of different nuclides. The half-life is the period of time during which the initial number of radioactive nuclei is on average halved.
With each act of decay, energy is released, which is transmitted in the form of radiation. Often an unstable nuclide is in an excited state, and the emission of a particle does not lead to a complete removal of the excitation; then he throws out a portion of energy in the form of gamma radiation (gamma quantum). As with X-rays (which differ from gamma rays only in frequency), no particles are emitted. The whole process of spontaneous decay of an unstable nuclide is called radioactive decay, and the nuclide itself is called a radionuclide.

Different types of radiation are accompanied by the release of different amounts of energy and have different penetrating power; therefore, they have a different effect on the tissues of a living organism. Alpha radiation is delayed, for example, by a sheet of paper and is practically unable to penetrate the outer layer of the skin. Therefore, it does not pose a danger until radioactive substances emitting alpha particles enter the body through an open wound, with food, water or inhaled air or steam, for example, in a bath; then they become extremely dangerous. A beta particle has a greater penetrating power: it passes into the tissues of the body to a depth of one or two centimeters or more, depending on the amount of energy. The penetrating power of gamma radiation, which propagates at the speed of light, is very high: it can only be stopped by a thick lead or concrete slab. Ionizing radiation is characterized by a number of measured physical quantities. These include energy quantities. At first glance, it may seem that they are enough to register and evaluate the effects of ionizing radiation on living organisms and humans. However, these energy values ​​do not reflect the physiological effects of ionizing radiation on the human body and other living tissues, they are subjective, and are different for different people. Therefore, average values ​​are used.

Sources of radiation are natural, present in nature, and not dependent on man.

It has been established that of all natural sources of radiation, radon, a heavy, tasteless, odorless and invisible gas, poses the greatest danger; with their child products.

Radon is released from the earth's crust everywhere, but its concentration in the outdoor air varies significantly for different parts of the globe. Paradoxical as it may seem at first glance, but a person receives the main radiation from radon while in a closed, unventilated room. Radon is concentrated in indoor air only when they are sufficiently isolated from the external environment. Seeping through the foundation and floor from the soil or, less often, being released from building materials, radon accumulates in the room. Sealing rooms for the purpose of insulation only exacerbates the matter, since it makes it even more difficult for the radioactive gas to escape from the room. The problem of radon is especially important for low-rise buildings with careful sealing of premises (in order to preserve heat) and the use of alumina as an additive to building materials (the so-called "Swedish problem"). The most common building materials - wood, brick and concrete - emit relatively little radon. Granite, pumice, products made from alumina raw materials, and phosphogypsum have much higher specific radioactivity.

Another, usually less important, source of indoor radon is water and natural gas used for cooking and home heating.

The concentration of radon in commonly used water is extremely low, but water from deep wells or artesian wells contains a lot of radon. However, the main danger does not come from drinking water, even with a high content of radon in it. Usually people consume most of the water in food and in the form of hot drinks, and when boiling water or cooking hot dishes, radon almost completely disappears. A much greater danger is the ingress of water vapor with a high content of radon into the lungs along with the inhaled air, which most often occurs in the bathroom or steam room (steam room).

In natural gas, radon penetrates underground. As a result of preliminary processing and during the storage of gas before it enters the consumer, most of the radon escapes, but the concentration of radon in the room can increase markedly if stoves and other gas heating appliances are not equipped with an exhaust hood. In the presence of supply and exhaust ventilation, which communicates with the outside air, the concentration of radon in these cases does not occur. This also applies to the house as a whole - focusing on the readings of radon detectors, you can set the ventilation mode of the premises, which completely eliminates the threat to health. However, given that the release of radon from the soil is seasonal, it is necessary to control the effectiveness of ventilation three to four times a year, not allowing the concentration of radon to exceed the norms.

Other sources of radiation, which unfortunately have a potential danger, are created by man himself. Sources of artificial radiation are artificial radionuclides, beams of neutrons and charged particles created with the help of nuclear reactors and accelerators. They are called man-made sources of ionizing radiation. It turned out that along with a dangerous character for a person, radiation can be put at the service of a person. Here is a far from complete list of areas of application of radiation: medicine, industry, agriculture, chemistry, science, etc. A calming factor is the controlled nature of all activities related to the production and use of artificial radiation.

Tests of nuclear weapons in the atmosphere, accidents at nuclear power plants and nuclear reactors and the results of their work, manifested in radioactive fallout and radioactive waste, stand apart in their impact on humans. However, only emergencies, such as the Chernobyl accident, can have an uncontrollable impact on a person.
The rest of the work is easily controlled at a professional level.

When radioactive fallout occurs in some areas of the Earth, radiation can enter the human body directly through agricultural products and food. Protecting yourself and your loved ones from this danger is very simple. When buying milk, vegetables, fruits, herbs, and any other products, it will not be superfluous to turn on the dosimeter and bring it to the purchased products. Radiation is not visible - but the device will instantly detect the presence of radioactive contamination. Such is our life in the third millennium - the dosimeter becomes an attribute of everyday life, like a handkerchief, toothbrush, soap.

IMPACT OF IONIZING RADIATION ON TISSUES OF THE BODY

Damage caused in a living organism by ionizing radiation will be the greater, the more energy it transfers to tissues; the amount of this energy is called a dose, by analogy with any substance entering the body and completely absorbed by it. The body can receive a dose of radiation regardless of whether the radionuclide is outside the body or inside it.

The amount of radiation energy absorbed by the irradiated tissues of the body, calculated per unit mass, is called the absorbed dose and is measured in Grays. But this value does not take into account the fact that with the same absorbed dose, alpha radiation is much more dangerous (twenty times) than beta or gamma radiation. The dose recalculated in this way is called the equivalent dose; It is measured in units called Sieverts.

It should also be taken into account that some parts of the body are more sensitive than others: for example, at the same equivalent dose of radiation, the occurrence of cancer in the lungs is more likely than in the thyroid gland, and irradiation of the gonads is especially dangerous due to the risk of genetic damage. Therefore, human exposure doses should be taken into account with different coefficients. Multiplying the equivalent doses by the corresponding coefficients and summing up over all organs and tissues, we obtain the effective equivalent dose, which reflects the total effect of irradiation on the body; it is also measured in Sieverts.

charged particles.

Alpha and beta particles penetrating into the tissues of the body lose energy due to electrical interactions with the electrons of those atoms near which they pass. (Gamma rays and X-rays transfer their energy to matter in several ways, which eventually also lead to electrical interactions.)

Electrical interactions.

In the order of ten trillionth of a second after the penetrating radiation reaches the corresponding atom in the tissue of the body, an electron is detached from this atom. The latter is negatively charged, so the rest of the initially neutral atom becomes positively charged. This process is called ionization. The detached electron can further ionize other atoms.

Physical and chemical changes.

Both a free electron and an ionized atom usually cannot remain in this state for long, and over the next ten billionths of a second, they participate in a complex chain of reactions that result in the formation of new molecules, including extremely reactive ones such as "free radicals".

chemical changes.

Over the next millionths of a second, the free radicals formed react both with each other and with other molecules and, through a chain of reactions not yet fully understood, can cause chemical modification of biologically important molecules necessary for the normal functioning of the cell.

biological effects.

Biochemical changes can occur both in a few seconds and decades after irradiation and cause immediate cell death or changes in them.

RADIOACTIVITY UNITS
Becquerel (Bq, Vq); Curie (Ki, Si)	1 Bq = 1 disintegration per second. 1 Ki \u003d 3.7 x 10 10 Bq	Radionuclide activity units. Represent the number of decays per unit time.
Gray (Gr, Gu); Glad (rad, rad)	1 Gy = 1 J/kg 1 rad = 0.01 Gy	units of absorbed dose. They represent the amount of ionizing radiation energy absorbed by a unit mass of a physical body, for example, by body tissues.
Sievert (Sv, Sv) Rem (ber, rem) - "X-ray biological equivalent"	1 Sv = 1 Gy = 1 J/kg (for beta and gamma) 1 µSv = 1/1000000 Sv 1 ber = 0.01 Sv = 10 mSv Dose equivalent units.	Units of equivalent dose. They are a unit of absorbed dose multiplied by a factor that takes into account the unequal danger of different types of ionizing radiation.
Gray per hour (Gy/h); Sievert per hour (Sv/h); Roentgen per hour (R/h)	1 Gy/h = 1 Sv/h = 100 R/h (for beta and gamma) 1 µSv/h = 1 µGy/h = 100 µR/h 1 µR/h = 1/1000000 R/h	Dose rate units. Represent the dose received by the body per unit of time.

For information, and not for intimidation, especially people who decide to devote themselves to working with ionizing radiation, you should know the maximum allowable doses. The units of measurement of radioactivity are given in Table 1. According to the conclusion of the International Commission on Radiation Protection for 1990, harmful effects can occur at equivalent doses of at least 1.5 Sv (150 rem) received during the year, and in cases of short-term exposure - at doses above 0.5 Sv (50 rem). When exposure exceeds a certain threshold, radiation sickness occurs. There are chronic and acute (with a single massive impact) forms of this disease. Acute radiation sickness is divided into four degrees of severity, ranging from a dose of 1-2 Sv (100-200 rem, 1st degree) to a dose of more than 6 Sv (600 rem, 4th degree). The fourth degree can be fatal.

Doses received under normal conditions are negligible compared to those indicated. The equivalent dose rate generated by natural radiation ranges from 0.05 to 0.2 µSv/h, i.e. from 0.44 to 1.75 mSv/year (44-175 mrem/year).
In medical diagnostic procedures - X-rays, etc. - a person receives about 1.4 mSv/year.

Since radioactive elements are present in brick and concrete in small doses, the dose increases by another 1.5 mSv/year. Finally, due to the emissions of modern coal-fired thermal power plants and air travel, a person receives up to 4 mSv / year. The total existing background can reach 10 mSv/year, but on average does not exceed 5 mSv/year (0.5 rem/year).

Such doses are completely harmless to humans. The dose limit in addition to the existing background for a limited part of the population in areas of increased radiation is set at 5 mSv / year (0.5 rem / year), i.e. with a 300-fold margin. For personnel working with sources of ionizing radiation, the maximum allowable dose is 50 mSv/year (5 rem/year), i.e. 28 μSv/h for a 36-hour work week.

According to the hygienic standards NRB-96 (1996), the permissible dose rates for external exposure of the whole body from man-made sources for the permanent residence of personnel members are 10 μGy/h, for residential premises and areas where members of the public are permanently located - 0 .1 µGy/h (0.1 µSv/h, 10 µR/h).

WHAT IS RADIATION MEASURED

A few words about registration and dosimetry of ionizing radiation. There are various methods of registration and dosimetry: ionization (associated with the passage of ionizing radiation in gases), semiconductor (in which the gas is replaced by a solid), scintillation, luminescent, photographic. These methods form the basis of the work dosimeters radiation. Among the gas-filled sensors of ionizing radiation, one can note ionization chambers, fission chambers, proportional counters and Geiger-Muller counters. The latter are relatively simple, the cheapest, and not critical to the working conditions, which led to their widespread use in professional dosimetric equipment designed to detect and evaluate beta and gamma radiation. When the sensor is a Geiger-Muller counter, any ionizing particle that enters the sensitive volume of the counter will cause self-discharge. Precisely falling into a sensitive volume! Therefore, alpha particles are not registered, because they can't get in there. Even when registering beta - particles, it is necessary to bring the detector closer to the object to make sure that there is no radiation, because. in the air, the energy of these particles may be weakened, they may not pass through the body of the device, they will not fall into the sensitive element and will not be detected.

Doctor of Physical and Mathematical Sciences, Professor of MEPhI N.M. Gavrilov
the article was written for the company "Kvarta-Rad"

ionizing called radiation, which, passing through the medium, causes ionization or excitation of the molecules of the medium. Ionizing radiation, like electromagnetic radiation, is not perceived by the human senses. Therefore, it is especially dangerous, since a person does not know that he is exposed to it. Ionizing radiation is otherwise called radiation.

Radiation is a stream of particles (alpha particles, beta particles, neutrons) or electromagnetic energy of very high frequencies (gamma or x-rays).

Pollution of the production environment with substances that are sources of ionizing radiation is called radioactive contamination.

Nuclear pollution is a form of physical (energy) pollution associated with the excess of the natural level of radioactive substances in the environment as a result of human activity.

Substances are made up of tiny particles of chemical elements - atoms. The atom is divisible and has a complex structure. At the center of an atom of a chemical element is a material particle called the atomic nucleus, around which electrons revolve. Most of the atoms of chemical elements have great stability, i.e., stability. However, in a number of elements known in nature, the nuclei spontaneously decay. Such elements are called radionuclides. The same element can have several radionuclides. In this case they are called radioisotopes chemical element. Spontaneous decay of radionuclides is accompanied by radioactive radiation.

Spontaneous decay of the nuclei of certain chemical elements (radionuclides) is called radioactivity.

Radioactive radiation can be of various types: streams of particles with high energy, an electromagnetic wave with a frequency of more than 1.5.10 17 Hz.

The emitted particles come in many forms, but the most commonly emitted are alpha particles (α-radiation) and beta particles (β-radiation). The alpha particle is heavy and has high energy; it is the nucleus of the helium atom. A beta particle is about 7336 times lighter than an alpha particle, but can also have high energy. Beta radiation is a stream of electrons or positrons.

Radioactive electromagnetic radiation (it is also called photon radiation), depending on the frequency of the wave, is X-ray (1.5.10 17 ... 5.10 19 Hz) and gamma radiation (more than 5.10 19 Hz). Natural radiation is only gamma radiation. X-ray radiation is artificial and occurs in cathode ray tubes at voltages of tens and hundreds of thousands of volts.

Radionuclides, emitting particles, turn into other radionuclides and chemical elements. Radionuclides decay at different rates. The decay rate of radionuclides is called activity. The unit of measure of activity is the number of decays per unit of time. One disintegration per second is called a becquerel (Bq). Often another unit is used to measure activity - curie (Ku), 1 Ku = 37.10 9 Bq. One of the first radionuclides studied in detail was radium-226. It was studied for the first time by the Curies, after whom the unit of measure of activity is named. The number of decays per second occurring in 1 g of radium-226 (activity) is 1 Ku.

The time it takes for half of a radionuclide to decay is called half-life(T 1/2). Each radionuclide has its own half-life. The range of T 1/2 for various radionuclides is very wide. It changes from seconds to billions of years. For example, the best known natural radionuclide, uranium-238, has a half-life of about 4.5 billion years.

During decay, the amount of the radionuclide decreases and its activity decreases. The pattern by which activity decreases obeys the law of radioactive decay:

where BUT 0 - initial activity, BUT- activity over a period of time t.

Types of ionizing radiation

Ionizing radiation occurs during the operation of devices based on radioactive isotopes, during the operation of vacuum devices, displays, etc.

Ionizing radiations are corpuscular(alpha, beta, neutron) and electromagnetic(gamma, x-ray) radiation, capable of creating charged atoms and ion molecules when interacting with matter.

alpha radiation is a stream of helium nuclei emitted by matter during radioactive decay of nuclei or during nuclear reactions.

The greater the energy of the particles, the greater the total ionization caused by it in the substance. The range of alpha particles emitted by a radioactive substance reaches 8-9 cm in air, and in living tissue - several tens of microns. Having a relatively large mass, alpha particles quickly lose their energy when interacting with matter, which determines their low penetrating ability and high specific ionization, amounting to several tens of thousands of pairs of ions per 1 cm of the path in air.

Beta radiation - the flow of electrons or positrons resulting from radioactive decay.

The maximum range in the air of beta particles is 1800 cm, and in living tissues - 2.5 cm. The ionizing ability of beta particles is lower (several tens of pairs per 1 cm of run), and the penetrating power is higher than that of alpha particles.

Neutrons, the flux of which forms neutron radiation, transform their energy in elastic and inelastic interactions with atomic nuclei.

With inelastic interactions, secondary radiation arises, which can consist of both charged particles and gamma quanta (gamma radiation): with elastic interactions, ordinary ionization of a substance is possible.

The penetrating power of neutrons largely depends on their energy and the composition of the matter of the atoms with which they interact.

Gamma radiation - electromagnetic (photon) radiation emitted during nuclear transformations or particle interactions.

Gamma radiation has a high penetrating power and a low ionizing effect.

x-ray radiation arises in the environment surrounding the source of beta radiation (in X-ray tubes, electron accelerators) and is a combination of bremsstrahlung and characteristic radiation. Bremsstrahlung is photon radiation with a continuous spectrum emitted when the kinetic energy of charged particles changes; characteristic radiation is a photon radiation with a discrete spectrum, emitted when the energy state of atoms changes.

Like gamma radiation, X-rays have a low ionizing power and a large penetration depth.

Sources of ionizing radiation

The type of radiation damage to a person depends on the nature of the sources of ionizing radiation.

The natural radiation background consists of cosmic radiation and radiation of naturally distributed radioactive substances.

In addition to natural exposure, a person is exposed to exposure from other sources, for example: in the production of x-rays of the skull - 0.8-6 R; spine - 1.6-14.7 R; lungs (fluorography) - 0.2-0.5 R; chest with fluoroscopy - 4.7-19.5 R; gastrointestinal tract with fluoroscopy - 12-82 R: teeth - 3-5 R.

A single irradiation of 25-50 rem leads to minor short-lived changes in the blood; at doses of 80-120 rem, signs of radiation sickness appear, but without a lethal outcome. Acute radiation sickness develops with a single irradiation of 200-300 rem, while a lethal outcome is possible in 50% of cases. Lethal outcome in 100% of cases occurs at doses of 550-700 rem. Currently, there are a number of anti-radiation drugs. weakening the effect of radiation.

Chronic radiation sickness can develop with continuous or repeated exposure to doses significantly lower than those that cause an acute form. The most characteristic signs of the chronic form of radiation sickness are changes in the blood, disorders of the nervous system, local skin lesions, damage to the lens of the eye, and a decrease in immunity.

The degree depends on whether the exposure is external or internal. Internal exposure is possible by inhalation, ingestion of radioisotopes and their penetration into the human body through the skin. Some substances are absorbed and accumulated in specific organs, resulting in high local doses of radiation. For example, iodine isotopes accumulating in the body can cause damage to the thyroid gland, rare earth elements can cause liver tumors, cesium and rubidium isotopes can cause soft tissue tumors.

Artificial sources of radiation

In addition to exposure from natural sources of radiation, which were and are always and everywhere, in the 20th century, additional sources of radiation associated with human activity appeared.

First of all, this is the use of X-rays and gamma radiation in medicine in the diagnosis and treatment of patients. , obtained with appropriate procedures, can be very large, especially in the treatment of malignant tumors with radiation therapy, when directly in the tumor zone they can reach 1000 rem or more. During x-ray examinations, the dose depends on the time of the examination and the organ that is being diagnosed, and can vary widely - from a few rem when taking a picture of a tooth to tens of rem when examining the gastrointestinal tract and lungs. Fluorographic images give the minimum dose, and preventive annual fluorographic examinations should by no means be abandoned. The average dose people receive from medical research is 0.15 rem per year.

In the second half of the 20th century, people began to actively use radiation for peaceful purposes. Various radioisotopes are used in scientific research, in the diagnosis of technical objects, in instrumentation, etc. And finally, nuclear power. Nuclear power plants are used at nuclear power plants (NPPs), icebreakers, ships, and submarines. Currently, more than 400 nuclear reactors with a total electrical capacity of over 300 million kW are operating at nuclear power plants alone. For the production and processing of nuclear fuel, a whole complex of enterprises united in nuclear fuel cycle(NFC).

The nuclear fuel cycle includes enterprises for the extraction of uranium (uranium mines), its enrichment (enrichment plants), the manufacture of fuel elements, nuclear power plants themselves, enterprises for the secondary processing of spent nuclear fuel (radiochemical plants), for the temporary storage and processing of nuclear fuel waste generated, and, finally, permanent disposal of radioactive waste (burial grounds). At all stages of the NFC, radioactive substances affect the operating personnel to a greater or lesser extent, at all stages, releases (normal or accidental) of radionuclides into the environment can occur and create an additional dose for the population, especially those living in the area of ​​the NFC enterprises.

Where do radionuclides come from during normal operation of nuclear power plants? The radiation inside a nuclear reactor is enormous. Fuel fission fragments, various elementary particles can penetrate protective shells, microcracks and enter the coolant and air. A number of technological operations in the production of electrical energy at nuclear power plants can lead to water and air pollution. Therefore, nuclear power plants are equipped with a water and gas purification system. Emissions to the atmosphere are carried out through a tall chimney.

During normal operation of nuclear power plants, emissions to the environment are small and have little impact on the population living in the vicinity.

The greatest danger from the point of view of radiation safety is posed by plants for the processing of spent nuclear fuel, which has a very high activity. These enterprises generate a large amount of liquid waste with high radioactivity, there is a danger of developing a spontaneous chain reaction (nuclear hazard).

The problem of dealing with radioactive waste, which is a very significant source of radioactive contamination of the biosphere, is very difficult.

However, complex and costly from radiation at NFC enterprises make it possible to ensure the protection of humans and the environment to very small values, significantly less than the existing technogenic background. Another situation occurs when there is a deviation from the normal mode of operation, and especially during accidents. Thus, the accident that occurred in 1986 (which can be attributed to global catastrophes - the largest accident at the nuclear fuel cycle enterprises in the entire history of the development of nuclear power) at the Chernobyl nuclear power plant led to the release of only 5% of all fuel into the environment. As a result, radionuclides with a total activity of 50 million Ci were released into the environment. This release led to the exposure of a large number of people, a large number of deaths, the contamination of very large areas, the need for mass relocation of people.

The accident at the Chernobyl nuclear power plant clearly showed that the nuclear method of generating energy is possible only if large-scale accidents at nuclear fuel cycle enterprises are ruled out in principle.

Ionizing radiation is a combination of various types of microparticles and physical fields that have the ability to ionize a substance, that is, to form electrically charged particles in it - ions. There are several types of ionizing radiation: alpha, beta, gamma, and neutron radiation.

alpha radiation

In the formation of positively charged alpha particles, 2 protons and 2 neutrons, which are part of the helium nuclei, take part. Alpha particles are formed during the decay of the nucleus of an atom and can have an initial kinetic energy from 1.8 to 15 MeV. Characteristic features of alpha radiation are high ionizing and low penetrating power. When moving, alpha particles lose their energy very quickly, and this causes the fact that it is not enough even to overcome thin plastic surfaces. In general, external irradiation with alpha particles, if we do not take into account high-energy alpha particles obtained using an accelerator, does not cause any harm to humans, but the penetration of particles into the body can be hazardous to health, since alpha radionuclides have a long half-life and are highly ionized. If ingested, alpha particles can often be even more dangerous than beta and gamma radiation.

beta radiation

Charged beta particles, whose speed is close to the speed of light, are formed as a result of beta decay. Beta rays are more penetrating than alpha rays - they can cause chemical reactions, luminescence, ionize gases, and have an effect on photographic plates. As a protection against the flow of charged beta particles (energy no more than 1 MeV), it will be enough to use an ordinary aluminum plate 3-5 mm thick.

Photon radiation: gamma radiation and x-rays

Photon radiation includes two types of radiation: x-ray (can be bremsstrahlung and characteristic) and gamma radiation.

The most common type of photon radiation is very high energy at ultrashort wavelength gamma particles, which are a stream of high energy, chargeless photons. Unlike alpha and beta rays, gamma particles are not deflected by magnetic and electric fields and have a much greater penetrating power. In certain quantities and for a certain duration of exposure, gamma radiation can cause radiation sickness and lead to various oncological diseases. Only such heavy chemical elements as, for example, lead, depleted uranium and tungsten can prevent the propagation of the flow of gamma particles.

neutron radiation

The source of neutron radiation can be nuclear explosions, nuclear reactors, laboratory and industrial installations. Neutrons themselves are electrically neutral, unstable (the half-life of a free neutron is about 10 minutes) particles, which, due to the fact that they have no charge, are characterized by high penetrating power with a low degree of interaction with matter. Neutron radiation is very dangerous, therefore, a number of special, mainly hydrogen-containing, materials are used to protect against it. Best of all, neutron radiation is absorbed by ordinary water, polyethylene, paraffin, and solutions of heavy metal hydroxides.

How do ionizing radiations affect substances?

All types of ionizing radiation to some extent affect various substances, but it is most pronounced in gamma particles and neutrons. So, with prolonged exposure, they can significantly change the properties of various materials, change the chemical composition of substances, ionize dielectrics and have a destructive effect on biological tissues. The natural radiation background will not bring much harm to a person, however, when handling artificial sources of ionizing radiation, one should be very careful and take all necessary measures to minimize the level of exposure to radiation on the body.