In human daily life, ionizing radiation occurs constantly. We don’t feel them, but we cannot deny their impact on living and inanimate nature. Not long ago, people learned to use them both for good and as weapons of mass destruction. When used correctly, these radiations can change the lives of humanity 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 substances and tissues, causing the ionization of atoms. There are several types of it: alpha radiation, beta radiation, gamma radiation. They all have different charges and abilities to act on living organisms.
Alpha radiation is the most charged of all types. It has enormous energy, capable of causing radiation sickness even in small doses. But with direct irradiation it penetrates only the upper layers of human skin. Even a thin sheet of paper protects from alpha rays. At the same time, when entering the body through food or inhalation, the sources of this radiation quickly become the cause of death.
Beta rays carry slightly less charge. They are able to penetrate deep into the body. With prolonged exposure they cause human death. Smaller doses cause changes in cellular structure. A thin sheet of aluminum can serve as protection. Radiation from inside the body is also deadly.
Gamma radiation is considered the most dangerous. 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.
A special type of gamma radiation is X-rays, which are generated in an X-ray tube.
History of research
The world first learned about ionizing radiation on December 28, 1895. It was on this day that Wilhelm C. Roentgen announced that he had discovered a special type of rays that could pass through various materials and the human body. From that moment on, 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 radiation.
The Curies studied in detail the sources and properties of ionizing radiation. This made it possible to use it with maximum benefit, avoiding negative consequences.
Natural and artificial sources of radiation
Nature has created various sources of ionizing radiation. First of all, this is radiation from the sun's rays and space. Most of it is absorbed by the ozone ball, which is located 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 several times higher than natural indicators.
Even in conditions of protection and compliance with safety measures, people receive radiation doses that are dangerous to their health.
Units of measurement and doses
Ionizing radiation is usually correlated with its interaction with the human body. Therefore, all units of measurement are in one way or another related to a person’s ability to absorb and accumulate ionization energy.
In the SI system, doses of ionizing radiation are measured in a unit called the gray (Gy). It shows the amount of energy per unit of irradiated substance. One Gy is equal to one J/kg. But for convenience, the non-system unit rad is more often used. It is equal to 100 Gy.
Background radiation in the area is measured by exposure doses. One dose is equal to C/kg. This unit is used in the SI system. The extra-system unit corresponding to it is called the roentgen (R). To receive an absorbed dose of 1 rad, you need to be exposed to an exposure dose of about 1 R.
Since different types of ionizing radiation have different energy levels, their measurement is usually compared with biological effects. In the SI system, the unit of such equivalent is the sievert (Sv). Its off-system analogue is the rem.
The stronger and longer the radiation, the more energy is absorbed by the body, the more dangerous its influence. To find out the permissible time for a person to remain in radiation contamination, special devices are used - dosimeters that measure ionizing radiation. These include both individual devices 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 to radiation causes severe burns and can cause skin cancer.
In recent years, the effects of ionizing radiation on the human body and its practical application have been actively studied.
In small doses, radiation does not cause any harm to the body. Up to 200 miliroentgen can reduce the number of white blood cells. Symptoms of such exposure will be nausea and dizziness. About 10% of people die after receiving this 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 exposure to ionizing radiation on the body and receiving a large dose of radiation can cause radiation sickness. More than half of cases of this disease lead to death. 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 subsequent generations.
Somatic diseases are expressed by carcinogenesis, irreversible changes in various organs. Treatment of these diseases is long and quite difficult.
Treatment of radiation injuries
As a result of the pathogenic effects of radiation on the body, various damage to human organs occurs. Depending on the radiation dose, different methods of therapy are carried out.
First of all, the patient is placed in a sterile room to avoid the possibility of infection of exposed skin areas. Next, special procedures are carried out to facilitate rapid removal of radionuclides from the body.
If the lesions are severe, a bone marrow transplant may be needed. From radiation, he loses the ability to reproduce red blood cells.
But in most cases, treatment of mild lesions comes down to anesthetizing the affected areas and stimulating cell regeneration. Much attention is paid to rehabilitation.
Effect of ionizing radiation on aging and cancer
In connection with the influence of ionizing rays on the human body, scientists have conducted various experiments proving the dependence of the aging process and carcinogenesis on the radiation dose.
Groups of cell cultures were exposed to irradiation in laboratory conditions. As a result, it was possible to prove that even minor radiation accelerates cell aging. Moreover, the older the culture, the more susceptible it is to this process.
Long-term 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 the waves on the affected cancer cells led to their complete death or stopping their division processes. This discovery helped develop a method for treating human cancer tumors.
Practical applications of radiation
For the first time, radiation began to be used in medical practice. Using X-rays, doctors were able to look inside the human body. At the same time, practically no harm was done to him.
Then they began to treat cancer with the help of radiation. In most cases, this method has a positive effect, despite the fact that the entire body is exposed to strong radiation, which entails a number of symptoms of radiation sickness.
In addition to medicine, ionizing rays are also used in other industries. Surveyors using radiation can study the structural features of the earth's crust in its individual areas.
Humanity has learned to use the ability of some fossils to release large amounts of energy for its own purposes.
Nuclear power
The future of the entire population of the Earth lies with atomic energy. Nuclear power plants provide sources of relatively inexpensive electricity. Provided they are operated correctly, such power plants are much safer than thermal power plants and hydroelectric power plants. Nuclear power plants produce much less environmental pollution from both excess heat and production waste.
At the same time, scientists developed weapons of mass destruction based on atomic energy. At the moment, there are so many atomic bombs on the planet that launching a small number of them could cause a nuclear winter, as a result of which almost all living organisms inhabiting 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, quantity and source shielding.
Even in an environment with a strong background radiation, a person can remain 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, you should avoid close contact with places where there is ionizing radiation. This is guaranteed to protect you from unwanted consequences.
If it is possible to use sources with minimal radiation, they are given preference first. This is defense in numbers.
Shielding means creating barriers through which harmful rays do not penetrate. An example of this is lead screens in x-ray rooms.
Household protection
If a radiation disaster is declared, you should immediately close all windows and doors and try to stock up on water from closed sources. Food should only be canned. When moving in open areas, cover your body with clothing as much as possible, and your 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 clothing, water and food for 2-3 days.
Ionizing radiation as an environmental factor
There are quite a lot of radiation-contaminated areas 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.
A person cannot stay in such places without harm to his own health. At the same time, it is not always possible to know in advance about radiation contamination. Sometimes even non-critical background radiation 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 “dark” jokes about Chernobyl mushrooms are based precisely on this property.
In such cases, protection from ionizing radiation comes down to the fact that all consumer products are subject to thorough radiological examination. At the same time, in spontaneous markets there is always a chance to buy the famous “Chernobyl mushrooms”. Therefore, you should refrain from purchasing from unverified sellers.
The human body tends to accumulate hazardous substances, resulting in gradual poisoning from the inside. It is not known exactly when the consequences of these poisons will make themselves felt: in a day, a year or a generation.
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 must be the total mass of the uranium pieces 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 approximately 500 kg; if you take a ball of such mass, then the diameter of such a ball will be 17 cm.
Radiation, what is it?
Radiation (translated from English as “radiation”) is radiation that is used not only in relation to radioactivity, but also for a number of other physical phenomena, for example: solar radiation, thermal radiation, etc. Thus, in relation to radioactivity, it is necessary to use the accepted ICRP (International Commission on Radiation Protection) and radiation safety regulations, the phrase “ionizing radiation”.
Ionizing radiation, what is it?
Ionizing radiation is radiation (electromagnetic, corpuscular) that causes ionization (formation of ions of both signs) of a substance (environment). The probability and number of ion pairs formed depends on the energy of ionizing radiation.
Radioactivity, what is it?
Radioactivity is the emission of excited nuclei or the spontaneous transformation of unstable atomic nuclei into the 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 energy of various kinds. Next, the excited nucleus seeks to remove excess energy by radiation (emission of alpha particles, electrons, protons, gamma quanta (photons), neutrons) until a stable state is achieved. Many heavy nuclei (transuranium series in the periodic table - thorium, uranium, neptunium, plutonium, etc.) are initially in an unstable state. They are capable of spontaneous decay. This process is also accompanied by radiation. Such nuclei are called natural radionuclides.
This animation clearly shows the phenomenon of radioactivity.
A cloud chamber (a 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 α particles and beta particles as it contains U-235 and U-238. In the path of movement of α and beta particles there are molecules of isopropyl alcohol.
Since the particles are charged (alpha is positive, beta is negative), they can remove an electron from an alcohol molecule (alpha particle) or add electrons to alcohol molecules (beta particles). This in turn gives the molecules a charge, which then attracts uncharged molecules around them. When the molecules gather together, they create noticeable white clouds, which is clearly visible in the animation. This way we can easily trace the paths of ejected particles.
α particles create straight, thick clouds, while beta particles create long ones.
Isotopes, what are they?
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 DI in the periodic table of elements. Mendeleev has a 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 an element.
There are stable isotopes (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 the formation of the mantle and is not associated with technogenic pollution.
What types of ionizing radiation exist?
The main types of ionizing radiation that are most often encountered are:
- alpha radiation;
- beta radiation;
- gamma radiation;
- X-ray radiation.
Of course, there are other types of radiation (neutron, positron, etc.), but we encounter them much less often in everyday life. Each type of radiation has its own nuclear physical characteristics and, as a result, different biological effects on the human body. Radioactive decay can be accompanied by one type of radiation or several at once.
Sources of radioactivity can be natural or artificial. Natural sources of ionizing radiation are radioactive elements located in the earth's crust and forming a natural radiation background together with cosmic radiation.
Artificial sources of radioactivity are usually produced in nuclear reactors or accelerators based on nuclear reactions. Sources of artificial ionizing radiation can also be a variety of electrovacuum physical devices, charged particle accelerators, etc. For example: a TV picture tube, an X-ray tube, a kenotron, etc.
Alpha radiation (α radiation) is corpuscular ionizing radiation consisting of alpha particles (helium nuclei). Formed during radioactive decay and nuclear transformations. Helium nuclei have quite 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 come into contact with 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 determined by the enormously high ionization density due to its high energy and mass.
Beta radiation (β radiation) is 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 energy); in biological tissues, the range of a beta particle is several centimeters. Beta radiation, like alpha radiation, is dangerous when exposed to contact radiation (surface contamination), for example, when it enters the body, mucous membranes and skin.
Gamma radiation (γ radiation or gamma quanta) is short-wave electromagnetic (photon) radiation with a wavelength
X-ray radiation is similar in its physical properties to gamma radiation, but has a number of features. It appears in an X-ray tube as a result of a sharp stop of electrons on a ceramic target anode (the place where electrons hit is usually made of copper or molybdenum) after acceleration in the tube (continuous spectrum - bremsstrahlung) and when electrons are knocked out of internal electronic shells of the target atom (line spectrum). The energy of X-ray radiation is low - from fractions of units of eV to 250 keV. X-ray radiation can be obtained using charged particle accelerators - synchrotron radiation with a continuous spectrum having an upper limit.
Passage of radiation and ionizing radiation through obstacles:
The sensitivity of the human body to the effects of radiation and ionizing radiation on it:
What is a radiation source?
A source of ionizing radiation (IRS) is an object that includes a radioactive substance or a technical device that creates or in certain cases is capable of creating ionizing radiation. There are closed and open radiation sources.
What are radionuclides?
Radionuclides are nuclei subject to spontaneous radioactive decay.
What is half-life?
Half-life is the period of time during which the number of nuclei of a given radionuclide is reduced by half as a result of radioactive decay. This quantity is used in the law of radioactive decay.
In what units is radioactivity measured?
The activity of a radionuclide in accordance with the SI measurement system is measured in Becquerels (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 a radioactive source is measured accordingly in Bq/s. The ratio of the activity of a radionuclide in a sample to the mass of the sample is called the specific activity of the radionuclide and is measured in Bq/kg (l).
In what units is ionizing radiation measured (X-ray and gamma)?
What do we see on the display of modern dosimeters that measure AI? The ICRP has proposed measuring dose at a depth d of 10 mm to assess human exposure. The measured 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 coefficient characterizing the sensitivity of various organs and tissues to a specific type of radiation.
The equivalent dose (or the often used concept of “dose”) is equal to the product of the absorbed dose and the quality factor of the impact of ionizing radiation (for example: the quality factor of the effect of gamma radiation is 1, and alpha radiation is 20).
The unit of measurement for the equivalent dose is the rem (biological equivalent of an x-ray) and its sub-multiple units: millirem (mrem), microrem (μrem), etc., 1 rem = 0.01 J/kg. The equivalent dose unit 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 is the amount of energy of ionizing radiation that is absorbed in an elementary volume, related to the mass of the substance in this volume.
The unit of absorbed dose is rad, 1 rad = 0.01 J/kg.
Unit of absorbed dose in the SI system – 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), the unit of measurement is rem/hour, Sv/hour, μSv/s, etc.
In what units are alpha and beta radiation measured?
The amount of alpha and beta radiation is determined as the flux density of particles per unit area, per unit time - a-particles * min/cm 2, β-particles * min/cm 2.
What is radioactive around us?
Almost everything that surrounds us, even the person himself. Natural radioactivity is to some extent the natural environment of humans, as long as it does not exceed natural levels. There are areas on the planet with elevated background radiation levels relative to the average. 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 territory is, for example, the state of Kerala in India.
For a true assessment, the frightening numbers that sometimes appear in print should be distinguished:
- natural, natural radioactivity;
- technogenic, i.e. changes in the radioactivity of the environment under human influence (mining, emissions and discharges from industrial enterprises, emergency situations and much more).
As a rule, it is almost impossible to eliminate elements of natural radioactivity. How can we get rid of 40 K, 226 Ra, 232 Th, 238 U, which are ubiquitous 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 quantities of radium in some types of groundwater (some of them, enriched with radon gas, are used in medical practice), and 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 surface natural 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 is mostly concentrated in cellars, basements, basements of buildings, in mine workings, etc.
It is believed that up to 70% of the effects of radiation on the population are due to radon in residential buildings.
The main sources of radon entering residential buildings are (as their importance increases):
- tap water and domestic gas;
- building materials (crushed stone, granite, marble, clay, slag, etc.);
- soil under buildings.
More information about radon and instruments for measuring it: RADON AND THORON RADIOMETERS.
Professional radon radiometers cost exorbitant amounts of money; for household use, we recommend that you pay attention to a household radon and thoron radiometer made in Germany: Radon Scout Home.
What are “black sands” and what danger do they pose?
“Black sands” (color varies from light yellow to red-brown, brown, there are varieties of white, greenish and black) are the mineral monazite - an anhydrous phosphate of elements of the thorium group, mainly cerium and lanthanum (Ce, La)PO 4 , which are replaced by thorium. Monazite contains up to 50-60% oxides of rare earth elements: yttrium oxide Y 2 O 3 up to 5%, thorium oxide ThO 2 up to 5-10%, sometimes up to 28%. Found 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 situation. But monazite deposits located near the coastal strip of the Azov Sea (within the Donetsk region), in the Urals (Krasnoufimsk) and other areas create a number of problems associated with the possibility of radiation exposure.
For example, due to the sea surf during the autumn-spring period on the coast, as a result of natural flotation, a significant amount of “black sand” is collected, characterized by a high content of thorium-232 (up to 15-20 thousand Bq/kg or more), which creates in local areas, gamma radiation levels are of the order of 3.0 or more μSv/hour. Naturally, it is unsafe to relax in such areas, so this sand is collected annually, warning signs are put up, and some sections of the coast are closed.
Instruments for measuring radiation and radioactivity.
To measure radiation levels and radionuclide content in different objects, special measuring instruments are used:
- to measure the exposure dose rate of gamma radiation, X-ray radiation, flux density of alpha and beta radiation, neutrons, dosimeters and search dosimeters-radiometers of various types are used;
- To determine the type of radionuclide and its content in environmental objects, AI spectrometers are used, which consist of a radiation detector, an analyzer and a personal computer with an appropriate program for processing the radiation spectrum.
Currently, there are a large number of dosimeters of various types to solve various problems of radiation monitoring and with wide capabilities.
Here is an example of dosimeters that are most often used in professional activities:
- Dosimeter-radiometer MKS-AT1117M(search dosimeter-radiometer) – a professional radiometer is used to search and identify sources of photon radiation. It has a digital indicator, the ability to set the alarm threshold, which greatly facilitates the work when inspecting territories, checking scrap metal, etc. The detection unit is remote. A NaI scintillation crystal is used as a detector. The dosimeter is a universal solution to various problems; it is equipped with a dozen different detection units with different technical characteristics. Measuring units allow you to measure alpha, beta, gamma, X-ray and neutron radiation.
Information about detection units and their application:
|
Name of detection block |
Measured radiation |
Main feature (technical characteristics) |
Application area |
|
DB for alpha radiation |
Measuring range 3.4·10 -3 - 3.4·10 3 Bq cm -2 |
DB for measuring the flux density of alpha particles from the surface |
|
|
DB for beta radiation |
Measuring range 1 - 5 10 5 part./(min cm 2) |
DB for measuring the flux density of beta particles from the surface |
|
|
DB for gamma radiation |
Sensitivity 350 imp s -1 / µSv h -1 measurement range 0.03 - 300 µSv/h |
The best option in terms of price, quality, technical characteristics. Widely used in the field of gamma radiation measurement. A good search detection unit for finding radiation sources. |
|
|
DB for gamma radiation |
Measuring range 0.05 µSv/h - 10 Sv/h |
A detection unit with a very high upper threshold for measuring gamma radiation. |
|
|
DB for gamma radiation |
Measuring range 1 mSv/h - 100 Sv/h Sensitivity 900 pulse s -1 / µSv h -1 |
An expensive detection unit with a high measurement range and excellent sensitivity. Used to find sources of radiation with strong radiation. |
|
|
DB for X-ray radiation |
Energy Range 5 - 160 keV |
Detection unit for X-ray radiation. Widely used in medicine and installations that produce low-energy X-ray radiation. |
|
|
DB for neutron radiation |
measurement range 0.1 - 10 4 neutron/(s cm 2) Sensitivity 1.5 (imp s -1)/(neutron s -1 cm -2) |
||
|
Database for alpha, beta, gamma and x-ray radiation |
Sensitivity 6.6 imp s -1 / µSv h -1 |
A universal detection unit that allows you to measure alpha, beta, gamma and x-ray radiation. It has low cost and poor sensitivity. I have found widespread agreement in the field of certification of workplaces (AWC), where it is mainly required to measure a local object. |
2. Dosimeter-radiometer DKS-96– designed for measuring gamma and x-ray radiation, alpha radiation, beta radiation, neutron radiation.
In many ways similar to a dosimeter-radiometer.
- measurement of dose and ambient dose equivalent rate (hereinafter referred to as dose and dose rate) H*(10) and H*(10) of continuous and pulsed X-ray and gamma radiation;
- measurement of alpha and beta radiation flux density;
- measurement of dose Н*(10) of neutron radiation and dose rate Н*(10) of neutron radiation;
- measurement of gamma radiation flux density;
- search, as well as localization of radioactive sources and sources of pollution;
- measurement of flux density and exposure dose rate of gamma radiation in liquid media;
- radiation analysis of the area taking into account geographic coordinates using GPS;
The two-channel scintillation beta-gamma spectrometer is designed for simultaneous and separate determination of:
- specific activity of 137 Cs, 40 K and 90 Sr in samples from various environments;
- specific effective activity of natural radionuclides 40 K, 226 Ra, 232 Th in building materials.
Allows for rapid analysis of standardized samples of metal melts for the presence of radiation and contamination.
9. Gamma spectrometer based on HPGe detector Spectrometers based on coaxial detectors made of HPGe (highly pure germanium) are designed to detect gamma radiation in the energy range from 40 keV to 3 MeV.
Beta and gamma radiation spectrometer MKS-AT1315
Spectrometer with lead protection NaI PAK
Portable NaI spectrometer MKS-AT6101
Wearable HPGe spectrometer Eco PAK
Portable HPGe spectrometer Eco PAK
NaI PAK spectrometer for automotive design
Spectrometer MKS-AT6102
Eco PAK spectrometer with electric machine cooling
Handheld PPD spectrometer Eco PAK
Explore other measurement tools for measuring ionizing radiation, you can visit our website:
- when carrying out dosimetric measurements, if they are meant to be carried out frequently in order to monitor the radiation situation, it is necessary to strictly observe the geometry and measurement methodology;
- to increase the reliability of dosimetric monitoring, it is necessary to carry out several measurements (but not less than 3), then calculate the arithmetic mean;
- when measuring the dosimeter background on the ground, areas are selected that are 40 m away from buildings and structures;
- measurements on the ground are carried out at two levels: at a height of 0.1 (search) and 1.0 m (measurement for the protocol - in this case, the sensor should be rotated in order to determine the maximum value on the display) from the ground surface;
- when measuring in residential and public premises, measurements are taken at a height of 1.0 m from the floor, preferably at five points using the “envelope” method. At first glance, it is difficult to understand what is happening in the photograph. It’s as if a giant mushroom has grown out of the floor, and ghostly people in helmets seem to be working next to it...
At first glance, it is difficult to understand what is happening in the photograph. It’s as if a giant mushroom has grown out of the floor, and ghostly people in helmets seem to be working next to it...
There's something inexplicably creepy about this scene, and for good reason. You are looking at the largest accumulation of what is probably the most toxic substance ever created by man. This is nuclear lava or corium.
In the days and weeks following the accident at the Chernobyl nuclear power plant on April 26, 1986, simply walking into a room containing the same pile of radioactive material - grimly nicknamed the "elephant's foot" - meant certain death within minutes. Even a decade later, when this photograph was taken, the film was likely behaving strangely due to radiation, resulting in a characteristic grainy structure. The man in the photograph, Artur Korneev, most likely visited this room more often than anyone else, so he was exposed to perhaps the maximum dose of radiation.
Surprisingly, in all likelihood he is still alive. The story of how the United States came into possession of a unique photograph of a man in the presence of an incredibly toxic material is itself shrouded in mystery - as is the reason why someone would take a selfie next to a hump of molten radioactive lava.
The photograph first came to America in the late 1990s, 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 ordered assistance by sending an order to the Pacific Northwest National Laboratories (PNNL), a busy research and development center in Richland, PC. Washington.
At the time, Tim Ledbetter was one of the new guys in PNNL's IT department, and he was tasked with creating a digital photo library for the Department of Energy's Nuclear Security Project, that is, to show the photos to the American public (or rather, that tiny part of the public that which then had access to the Internet). He asked project participants to take photographs during their trips to Ukraine, hired a freelance photographer, and also asked Ukrainian colleagues at the Chernobyl Center for materials. Among hundreds of photographs of awkward handshakes between 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 turbogenerator.
As radioactive smoke rose above the village, poisoning the surrounding land, the rods below liquefied, melting through the walls of the reactor and forming a substance called corium.
As radioactive smoke rose above the village, poisoning the surrounding land, the 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 senior nuclear engineer at Argonne National Laboratory, another U.S. Department of Energy facility near Chicago. Corium formed once at the Three Mile Island reactor in Pennsylvania in 1979, once at Chernobyl, and three times in the 2011 Fukushima reactor meltdown. In his laboratory, Farmer created modified versions of corium to better understand how to avoid similar incidents in the future. A study of the substance showed, in particular, that watering after the formation of corium actually prevents the decay of some elements and the formation of more dangerous isotopes.
Of the five cases of corium formation, only in Chernobyl was nuclear lava able to escape beyond 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 mixed with molecules of uranium (fuel) and zirconium (coating). This poisonous lava flowed downwards, eventually melting the floor of the building. When inspectors finally entered the power unit several months after the accident, they discovered an 11-ton, three-meter slide in the corner of the steam distribution corridor below. That's when it was called the "elephant's foot." Over the following years, the elephant's foot was cooled and crushed. But even today, its remains are still several degrees warmer than the surrounding environment, as the decay of radioactive elements continues.
Ledbetter cannot remember where exactly he obtained these photographs. He compiled the photo library almost 20 years ago, and the website that hosts them is still in good shape; only smaller copies of the images were lost. (Ledbetter, still working at PNNL, was surprised to learn that the photos were still available online.) But he definitely remembers that he didn’t send anyone to photograph the “elephant’s foot,” 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 while writing an article about the “elephant’s foot” for Nautilus magazine. He traced its origin to a PNNL laboratory. A long-lost description of the photograph was found on the site: "Arthur Korneev, deputy director of the Shelter facility, studying the elephant's foot nuclear lava, Chernobyl. Photographer: unknown. Autumn 1996." Ledbetter confirmed that the description matches the photo.
Arthur Korneev- an inspector from Kazakhstan who has been educating employees, telling and protecting them from the “elephant’s foot” since its formation after the Chernobyl explosion in 1986, and a lover of dark jokes. Most likely, the last time a NY Times reporter spoke to him was in 2014 in Slavutich, a city specially built for evacuated personnel from Pripyat (Chernobyl Nuclear Power Plant).
The photo was probably taken at a slower shutter speed than the other photos to allow the photographer to appear in the frame, which explains the movement effect and why the headlamp looks like lightning. The graininess of the photo is likely 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 work in the days following the explosion. His first assignment was to identify fuel deposits and help measure radiation levels (the elephant's foot initially glowed at more than 10,000 roentgens per hour, which would kill a person a meter away in less than two minutes). Shortly thereafter, he led a cleanup operation that sometimes required removing entire pieces of nuclear fuel from the path. More than 30 people died from acute radiation sickness during the cleanup of the power unit. Despite the incredible dose of radiation he received, Korneev himself continued to return to the hastily constructed concrete sarcophagus again and again, often with journalists to protect them from danger.
In 2001, he led an Associated Press reporter to the core, where radiation levels were 800 roentgens per hour. In 2009, the famous novelist 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 Theroux’s fears and said that it was “pure psychology.” Although Theroux referred to him as Viktor Korneev, in all likelihood the man was Arthur, since he made similar black jokes a few years later with a NY Times journalist.
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 Shelter and prevent the leakage of isotopes. At 60-something years old, Korneev looked frail, suffered from cataracts, and was banned from visiting the sarcophagus after being repeatedly exposed to radiation in previous decades.
However, Korneev's sense of humor remained unchanged. He doesn't seem to regret his life's work at all: “Soviet radiation,” he jokes, “is the best radiation in the world.” .
Ionizing radiation (hereinafter referred to as IR) is radiation whose interaction with matter leads to the ionization of atoms and molecules, i.e. this interaction leads to the excitation of the atom and the separation of individual electrons (negatively charged particles) from atomic shells. As a result, deprived of one or more electrons, the atom turns into a positively charged ion - primary ionization occurs. II includes electromagnetic radiation (gamma radiation) and flows of charged and neutral particles - corpuscular radiation (alpha radiation, beta radiation, and neutron radiation).
Alpha radiation refers to corpuscular radiation. This is a stream of heavy positively charged alpha particles (nuclei of helium atoms) resulting from the decay of atoms of heavy elements such as uranium, radium and thorium. Since the particles are heavy, the range of alpha particles in a substance (that is, the path along which they produce ionization) turns out to be very short: hundredths of a millimeter in biological media, 2.5-8 cm in air. Thus, a regular sheet of paper or the outer dead layer of skin can trap these particles.
However, substances that emit alpha particles are long-lived. As a result of such substances entering the body with food, air or through wounds, they are carried throughout the body by the bloodstream, deposited in organs responsible for metabolism and protection of the body (for example, the spleen or lymph nodes), thus causing internal irradiation of the body . The danger of such internal irradiation of the body is high, because these alpha particles create a very large number of ions (up to several thousand pairs of ions per 1 micron of path in tissues). Ionization, in turn, determines a number of features of those chemical reactions that occur in matter, in particular in living tissue (the formation of strong oxidizing agents, free hydrogen and oxygen, etc.).
Beta radiation(beta rays, or stream of beta particles) also refers to the corpuscular type of radiation. This is a stream of electrons (β- radiation, or, most often, just β-radiation) or positrons (β+ radiation) emitted during the radioactive beta decay of the nuclei of certain atoms. Electrons or positrons are produced in the nucleus when a neutron converts to a proton or a proton to a neutron, respectively.
Electrons are significantly smaller than alpha particles and can penetrate 10-15 centimeters deep into a substance (body) (cf. hundredths of a millimeter for alpha particles). When passing through matter, beta radiation interacts with the electrons and nuclei of its atoms, expending its energy on this and slowing down the movement until it stops completely. Due to these properties, to protect against beta radiation, it is enough to have an organic glass screen of appropriate thickness. The use of beta radiation in medicine for superficial, interstitial and intracavitary radiation therapy is based on these same properties.
Neutron radiation- another type of corpuscular type of radiation. Neutron radiation is a flow of neutrons (elementary particles that have no electrical charge). Neutrons do not have an ionizing effect, but a very significant ionizing effect occurs due to elastic and inelastic scattering on the nuclei of matter.
Substances irradiated by neutrons can acquire radioactive properties, that is, receive so-called induced radioactivity. Neutron radiation is generated during the operation of particle accelerators, in nuclear reactors, industrial and laboratory installations, during nuclear explosions, etc. Neutron radiation has the greatest penetrating ability. The best materials for protection against neutron radiation are hydrogen-containing materials.
Gamma rays and x-rays belong to electromagnetic radiation.
The fundamental difference between these two types of radiation lies in the mechanism of their occurrence. X-ray radiation is of extranuclear origin, gamma radiation is a product of nuclear decay.
X-ray radiation was discovered in 1895 by the physicist Roentgen. This is invisible radiation capable of penetrating, although to varying degrees, into all substances. It is electromagnetic radiation with a wavelength of the order of - from 10 -12 to 10 -7. The source of X-rays is an X-ray tube, some radionuclides (for example, beta emitters), accelerators and electron storage devices (synchrotron radiation).
The X-ray tube has two electrodes - the cathode and the anode (negative and positive electrodes, respectively). When the cathode is heated, electron emission occurs (the phenomenon of the emission of electrons by the surface of a solid or liquid). Electrons escaping from the cathode are accelerated by the electric field and strike the surface of the anode, where they are sharply decelerated, resulting in X-ray radiation. Like visible light, X-rays cause photographic film to turn black. This is one of its properties, fundamental for medicine - that it is penetrating radiation and, accordingly, the patient can be illuminated with its help, and because Tissues of different density absorb X-rays differently - we can diagnose many types of diseases of internal organs at a very early stage.
Gamma radiation is of intranuclear origin. It occurs during the decay of radioactive nuclei, the transition of nuclei from an excited state to the ground state, during the interaction of fast charged particles with matter, the annihilation of electron-positron pairs, etc.
The high penetrating power of gamma radiation is explained by its short wavelength. To weaken the flow of gamma radiation, substances with a significant mass number (lead, tungsten, uranium, etc.) and all kinds of high-density compositions (various concretes with metal fillers) are used.
Ionizing radiation
Ionizing radiation is electromagnetic radiation that is created during radioactive decay, nuclear transformations, inhibition of charged particles in matter and forms ions of different signs when interacting with the environment.
Sources of ionizing radiation. In production, sources of ionizing radiation can be radioactive isotopes (radionuclides) of natural or artificial origin used in technological processes, accelerator installations, X-ray machines, radio lamps.
Artificial radionuclides as a result of nuclear transformations in the fuel elements of nuclear reactors after special radiochemical separation are used in the country's economy. In industry, artificial radionuclides are used for flaw detection of metals, in studying the structure and wear of materials, in devices and devices that perform control and signaling functions, as a means of extinguishing static electricity, etc.
Natural radioactive elements are radionuclides formed from naturally occurring radioactive thorium, uranium and actinium.
Types of ionizing radiation. In solving production problems, there are types of ionizing radiation such as (corpuscular fluxes of alpha particles, electrons (beta particles), neutrons) and photons (bremsstrahlung, X-rays and gamma radiation).
Alpha radiation is a stream of helium nuclei emitted mainly by natural radionuclides during radioactive decay. The range of alpha particles in the air reaches 8-10 cm, in biological tissue several tens of micrometers. Since the range of alpha particles in matter is small, and the energy is very high, their ionization density per unit path length is very high.
Beta radiation is a stream of electrons or positrons during radioactive decay. The energy of beta radiation does not exceed several MeV. The range in air is from 0.5 to 2 m, in living tissues - 2-3 cm. Their ionizing ability is lower than alpha particles.
Neutrons are neutral particles having the mass of a hydrogen atom. When interacting with matter, they lose their energy in elastic (like the interaction of billiard balls) and inelastic collisions (a ball hitting a pillow).
Gamma radiation is photon radiation that occurs when the energy state of atomic nuclei changes, during nuclear transformations or during the annihilation of particles. Gamma radiation sources used in industry have energies ranging from 0.01 to 3 MeV. Gamma radiation has high penetrating power and low ionizing effect.
X-ray radiation - photon radiation, consisting of bremsstrahlung and (or) characteristic radiation, occurs in X-ray tubes, electron accelerators, with a photon energy of no more than 1 MeV. X-ray radiation, like gamma radiation, has a high penetrating ability and a low ionization density of the medium.
Ionizing radiation is characterized by a number of special characteristics. The amount of radionuclide is usually called activity. Activity is the number of spontaneous decays of a radionuclide per unit time.
The SI unit of activity is the becquerel (Bq).
1Bq = 1 decay/s.
The extrasystemic unit of activity is the previously used Curie (Ci) value. 1Ci = 3.7 * 10 10 Bq.
Radiation doses. When ionizing radiation passes through a substance, it is affected only by that part of the radiation energy that is transferred to the substance and is absorbed by it. The portion of energy transferred by radiation to a substance is called a dose. A quantitative characteristic of the interaction of ionizing radiation with a substance is the absorbed dose.
Absorbed dose D n is the ratio of the average energy? E transferred by ionizing radiation to a substance in an elementary volume to a unit mass? m of the substance in this volume
In the SI system, the unit of absorbed dose is the gray (Gy), named after the English physicist and radiobiologist L. Gray. 1 Gy corresponds to the absorption of an average of 1 J of ionizing radiation energy in a mass of matter equal to 1 kg; 1 Gy = 1 J/kg.
Dose equivalent H T,R - absorbed dose in an organ or tissue D n, multiplied by the corresponding weighting factor for a given radiation W R
Н T,R = W R * D n ,
The unit of measurement for equivalent dose is J/kg, which has a special name - sievert (Sv).
The values of WR for photons, electrons and muons of any energy are 1, and for b-particles and fragments of heavy nuclei - 20.
Biological effects of ionizing radiation. The biological effect of radiation on a living organism begins at the cellular level. A living organism consists of cells. The nucleus is considered the most sensitive vital part of the cell, and its main structural elements are chromosomes. The structure of chromosomes is based on the dioxyribonucleic acid (DNA) molecule, which contains the hereditary information of the organism. Genes are located on chromosomes in a strictly defined order, and each organism has a specific set of chromosomes in each cell. In humans, each cell contains 23 pairs of chromosomes. Ionizing radiation causes chromosome breakage, followed by the joining of broken ends into new combinations. This leads to a change in the gene apparatus and the formation of daughter cells that are different from the original ones. If persistent chromosomal damage occurs in germ cells, this leads to mutations, i.e., the appearance of offspring with different characteristics in irradiated individuals. Mutations are useful if they lead to an increase in the vitality of the organism, and harmful if they manifest themselves in the form of various congenital defects. Practice shows that when exposed to ionizing radiation, the likelihood of beneficial mutations occurring is low.
In addition to genetic effects that can affect subsequent generations (congenital deformities), so-called somatic (bodily) effects are also observed, which are dangerous not only for the given organism itself (somatic mutation), but also for its offspring. A somatic mutation extends only to a certain circle of cells formed by normal division from a primary cell that has undergone a mutation.
Somatic damage to the body by ionizing radiation is the result of the effect of radiation on a large complex - groups of cells that form certain tissues or organs. Radiation inhibits or even completely stops the process of cell division, in which their life actually manifests itself, and strong enough radiation ultimately kills cells. Somatic effects include local damage to the skin (radiation burn), eye cataracts (clouding of the lens), damage to the genitals (short-term or permanent sterilization), etc.
It has been established that there is no minimum level of radiation below which mutation does not occur. The total number of mutations caused by ionizing radiation is proportional to population size and average radiation dose. The manifestation of genetic effects depends little on the dose rate, but is determined by the total accumulated dose, regardless of whether it was received in 1 day or 50 years. It is believed that genetic effects do not have a dose threshold. Genetic effects are determined only by the effective collective dose of man-sievert (man-Sv), and detection of the effect in an individual is almost unpredictable.
Unlike genetic effects, which are caused by small doses of radiation, somatic effects always begin with a certain threshold dose: at lower doses, damage to the body does not occur. Another difference between somatic damage and genetic damage is that the body is able to overcome the effects of radiation over time, while cellular damage is irreversible.
The main legal standards in the field of radiation safety include the Federal Law “On Radiation Safety of the Population” No. 3-FZ dated 01/09/96, Federal Law “On the Sanitary-Epidemiological Welfare of the Population” No. 52-FZ dated 03/30/99. , Federal Law “On the Use of Atomic Energy” No. 170-FZ of November 21, 1995, as well as Radiation Safety Standards (NRB-99). The document belongs to the category of sanitary rules (SP 2.6.1.758 - 99), approved by the Chief State Sanitary Doctor of the Russian Federation on July 2, 1999 and put into effect on January 1, 2000.
Radiation safety standards include terms and definitions that must be used in solving radiation safety problems. They also establish three classes of standards: basic dose limits; permissible levels, which are derived from dose limits; limits of annual intake, volumetric permissible average annual intake, specific activities, permissible levels of contamination of working surfaces, etc.; control levels.
The regulation of ionizing radiation is determined by the nature of the impact of ionizing radiation on the human body. In this case, two types of effects related to diseases in medical practice are distinguished: deterministic threshold effects (radiation sickness, radiation burn, radiation cataract, fetal development abnormalities, etc.) and stochastic (probabilistic) non-threshold effects (malignant tumors, leukemia, hereditary diseases) .
Ensuring radiation safety is determined by the following basic principles:
1. The principle of rationing is not to exceed the permissible limits of individual exposure doses to citizens from all sources of ionizing radiation.
2. The principle of justification is the prohibition of all types of activities involving the use of sources of ionizing radiation, in which the benefit obtained for humans and society does not exceed the risk of possible harm caused in addition to the natural background radiation exposure.
3. The principle of optimization - maintaining at the lowest possible and achievable level, taking into account economic and social factors, individual radiation doses and the number of exposed persons when using any source of ionizing radiation.
Devices for monitoring ionizing radiation. All currently used instruments can be divided into three main groups: radiometers, dosimeters and spectrometers. Radiometers are designed to measure the flux density of ionizing radiation (alpha or beta), as well as neutrons. These instruments are widely used to measure contamination of work surfaces, equipment, skin and clothing of personnel. Dosimeters are designed to change the dose and dose rate received by personnel during external exposure, mainly to gamma radiation. Spectrometers are designed to identify contaminants based on their energy characteristics. Gamma, beta and alpha spectrometers are used in practice.
Ensuring safety when working with ionizing radiation. All work with radionuclides is divided into two types: work with sealed sources of ionizing radiation and work with open radioactive sources.
Sealed sources of ionizing radiation are any sources whose design prevents the entry of radioactive substances into the air of the working area. Open sources of ionizing radiation can pollute the air in the work area. Therefore, requirements for safe work with closed and open sources of ionizing radiation in production have been separately developed.
The main danger of closed sources of ionizing radiation is external exposure, determined by the type of radiation, the activity of the source, the radiation flux density and the radiation dose created by it and the absorbed dose. Basic principles of ensuring radiation safety:
Reducing the power of sources to minimum values (protection, quantity); reducing the time spent working with sources (time protection); increasing the distance from the source to workers (protection by distance) and shielding radiation sources with materials that absorb ionizing radiation (protection by screens).
Shielding is the most effective way to protect against radiation. Depending on the type of ionizing radiation, various materials are used to make screens, and their thickness is determined by the radiation power. The best screens for protection against X-ray and gamma radiation are lead, which allows you to achieve the desired effect in terms of attenuation factor with the smallest screen thickness. Cheaper screens are made from leaded glass, iron, concrete, barryte concrete, reinforced concrete and water.
Protection from open sources of ionizing radiation provides both protection from external exposure and protection of personnel from internal exposure associated with the possible penetration of radioactive substances into the body through the respiratory system, digestion or through the skin. Methods to protect personnel in this case are as follows.
1. Use of protection principles applied when working with radiation sources in a closed form.
2. Sealing of production equipment in order to isolate processes that may be sources of radioactive substances entering the external environment.
3. Planning activities. The layout of the premises assumes maximum isolation of work with radioactive substances from other rooms and areas that have a different functional purpose.
4. Use of sanitary and hygienic devices and equipment, use of special protective materials.
5. Use of personal protective equipment for personnel. All personal protective equipment used for working with open sources is divided into five types: overalls, safety shoes, respiratory protection, insulating suits, and additional protective equipment.
6. Compliance with personal hygiene rules. These rules provide for personal requirements for those working with sources of ionizing radiation: prohibition of smoking in the work area, thorough cleaning (decontamination) of the skin after completion of work, conducting dosimetric monitoring of contamination of work clothes, special footwear and skin. All these measures involve eliminating the possibility of radioactive substances entering the body.
Radiation safety services. The safety of working with sources of ionizing radiation at enterprises is controlled by specialized services - radiation safety services are staffed by persons who have undergone special training in secondary and higher educational institutions or specialized courses of the Ministry of Atomic Energy of the Russian Federation. These services are equipped with the necessary instruments and equipment that allow them to solve the tasks assigned to them.
The main tasks determined by national legislation on monitoring the radiation situation, depending on the nature of the work carried out, are as follows:
Monitoring the dose rate of X-ray and gamma radiation, fluxes of beta particles, nitrons, corpuscular radiation in workplaces, adjacent rooms and on the territory of the enterprise and the observed area;
Monitoring the content of radioactive gases and aerosols in the air of workers and other premises of the enterprise;
Control of individual exposure depending on the nature of the work: individual control of external exposure, control of the content of radioactive substances in the body or in a separate critical organ;
Control over the amount of radioactive substances released into the atmosphere;
Control over the content of radioactive substances in wastewater discharged directly into the sewer system;
Control over the collection, removal and neutralization of radioactive solid and liquid waste;
Monitoring the level of pollution of environmental objects outside the enterprise.
51. Ionizing radiation. Types of ionizing radiation, main characteristics.
AI are divided into 2 types:
Corpuscular radiation
- 𝛼-radiation is a stream of helium nuclei emitted by a substance during radioactive decay or during nuclear reactions;
- 𝛽-radiation – a flow of electrons or positrons arising during radioactive decay;
Neutron radiation (During elastic interactions, the usual ionization of matter occurs. With inelastic interactions, secondary radiation occurs, which can consist of both charged particles and -quanta).
2. Electromagnetic radiation
- 𝛾-radiation is electromagnetic (photon) radiation emitted during nuclear transformations or particle interactions;
X-ray radiation - occurs in the environment surrounding the radiation source, in X-ray tubes.
AI characteristics: energy (MeV); speed (km/s); mileage (in the air, in living tissue); ionizing ability (ion pairs per 1 cm of path in the air).
α-radiation has the lowest ionizing ability.
Charged particles lead to direct, strong ionization.
Activity (A) of a radioactive substance is the number of spontaneous nuclear transformations (dN) in this substance over a short period of time (dt):
1 Bq (becquerel) is equal to one nuclear transformation per second.
52. Ionizing radiation. Doses of ionizing radiation and their units of measurement.
Ionizing radiation (IR) is radiation whose interaction with the environment leads to the formation of charges of opposite signs. Ionizing radiation occurs during radioactive decay, nuclear transformations, as well as during the interaction of charged particles, neutrons, photon (electromagnetic) radiation with matter.
Radiation dose– quantity used to assess exposure to ionizing radiation.
Exposure dose(characterizes the radiation source by the ionization effect):
Exposure dose at the workplace when working with radioactive substances:
where A is the activity of the source [mCi], K is the gamma constant of the isotope [Рcm2/(hmCi)], t is the irradiation time, r is the distance from the source to the workplace [cm].
Dose rate(irradiation intensity) – the increment of the corresponding dose under the influence of a given radiation per unit. time.
Exposure dose rate [рh -1 ].
Absorbed dose shows how much energy the AI has absorbed per unit. mass of irradiated substance:
D absorb. = D exp. K 1
where K 1 is a coefficient taking into account the type of substance being irradiated
Absorption dose, Gray, [J/kg]=1 Gray
Equivalent dose characteristic of chronic exposure to radiation of arbitrary composition
N = D Q [Sv] 1 Sv = 100 rem.
Q – dimensionless weighing coefficient for a given type of radiation. For X-rays and -radiation Q=1, for alpha, beta particles and neutrons Q=20.
Effective equivalent dose sensitivity differ. organs and tissues to radiation.
Irradiation of inanimate objects – Absorption. dose
Irradiation of living objects - Equiv. dose
53. Effect of ionizing radiation(AI) on the body. External and internal irradiation.
Biological effect of AI is based on the ionization of living tissue, which leads to the breaking of molecular bonds and changes in the chemical structure of various compounds, which leads to changes in the DNA of cells and their subsequent death.
Disruption of the body's vital processes is expressed in such disorders as
Inhibition of the functions of hematopoietic organs,
Disruption of normal blood clotting and increased fragility of blood vessels,
Disorders of the gastrointestinal tract,
Decreased resistance to infections,
Exhaustion of the body.
External exposure occurs when the source of radiation is outside the human body and there are no ways for it to get inside.
Internal exposure origin when the source of AI is inside a person; at the same time internal irradiation is also dangerous due to the proximity of the source of radiation to organs and tissues.
Threshold effects (H > 0.1 Sv/year) depend on the dose of radiation, occur with radiation doses throughout life
Radiation sickness is a disease that is characterized by symptoms that occur when exposed to AI, such as a decrease in hematopoietic capacity, gastrointestinal upset, and decreased immunity.
The degree of radiation sickness depends on the radiation dose. The most severe is the 4th degree, which occurs when exposed to AI with a dose of more than 10 Gray. Chronic radiation injuries are usually caused by internal radiation.
Non-threshold (stachastic) effects appear at doses of H<0,1 Зв/год, вероятность возникновения которых не зависит от дозы излучения.
Stochastic effects include:
Somatic changes
Immune changes
Genetic changes
The principle of rationing – i.e. not exceeding permissible limits individual. Radiation doses from all sources of AI.
Principle of justification – i.e. prohibition of all types of activities using AI sources, in which the benefits obtained for humans and society do not exceed the risk of possible harm caused in addition to natural radiation. fact.
Optimization principle – maintenance at the lowest possible and achievable level, taking into account economics. and social individual factors radiation doses and the number of exposed persons when using an irradiation source.
SanPiN 2.6.1.2523-09 “Radiation Safety Standards”.
In accordance with this document, 3 grams are allocated. persons:
gr.A - these are faces, unimportant. working with man-made sources of AI
gr .B - these are persons whose working conditions are in the immediate vicinity. breeze from the AI source, but they work. data of persons not related to not connected with the source.
gr .IN – this is the rest of the population, incl. persons gr. A and B are outside their production activities.
Main oral dose limit. by effective dose:
For persons of group A: 20mSv per year on Wed. for sequential 5 years, but not more than 50 mSv in year.
For persons group B: 1mSv per year on Wed. for sequential 5 years, but not more than 5 mSv in year.
For persons group B: should not exceed ¼ of the values for personnel of group A.
In case of an emergency caused by a radiation accident, there is a so-called peak increased exposure, cat. is permitted only in cases where it is not possible to take measures to prevent harm to the body.
The use of such doses may justified only by saving lives and preventing accidents, additionally only for men over 30 years old with a voluntary written agreement.
M/s of protection against AI:
Number of protection
Time protection
Protection distance
Zoning
Remote control
Shielding
To protect againstγ -radiation: metallic screens made with high atomic weight (W, Fe), as well as from concrete and cast iron.
To protect against β-radiation: use materials with low atomic mass (aluminum, plexiglass).
To protect against alpha radiation: use metals containing H2 (water, paraffin, etc.)
Screen thickness K=Po/Рdop, Po – power. dose measured in rad. place; Rdop is the maximum permissible dose.
Zoning – dividing the territory into 3 zones: 1) shelter; 2) objects and premises in which people can live; 3) DC zone stay of people.
Dosimetric monitoring based on the use of the following. methods: 1. Ionization 2. Phonographic 3. Chemical 4. Calorimetric 5. Scintillation.
Basic instruments , used for dosimetry. control:
X-ray meter (for measuring powerful exposure dose)
Radiometer (for measuring AI flux density)
Individual. dosimeters (for measuring exposure or absorbed dose).
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