In these recipes, only natural products are used, so to speak, folk ...
Atomic energy is quite actively used for peaceful purposes, for example, in the operation of an X-ray apparatus, an accelerator installation, which made it possible to spread ionizing radiation in the national economy. Given that a person is exposed to it every day, it is necessary to find out what the consequences of dangerous contact might be and how to protect yourself.
Main characteristic
Ionizing radiation is a type of radiant energy that enters a specific environment, causing the ionization process in the body. This characteristic of ionizing radiation is suitable for X-rays, radioactive and high energies, and much more.
Ionizing radiation has a direct effect on the human body. Despite the fact that ionizing radiation can be used in medicine, it is extremely dangerous, as evidenced by its characteristics and properties.
The known varieties are radioactive irradiation, which appear due to the arbitrary splitting of the atomic nucleus, which causes the transformation of chemical and physical properties. Substances that can decay are considered radioactive.
They are artificial (seven hundred elements), natural (fifty elements) - thorium, uranium, radium. It should be noted that they have carcinogenic properties, the release of toxins as a result of exposure to humans can cause cancer, radiation sickness.
It should be noted the following types of ionizing radiation that affect the human body:
Alpha
They are considered positively charged ions of helium, which appear in the case of decay of nuclei of heavy elements. Protection against ionizing radiation is carried out using a piece of paper, cloth.
Beta
- a flow of negatively charged electrons that appear in the case of decay of radioactive elements: artificial, natural. The damaging factor is much higher than that of the previous species. For protection, you need a thicker screen, more durable. Such radiation includes positrons.
Gamma
- a hard electromagnetic oscillation that appears after the decay of the nuclei of radioactive substances. There is a high penetrating factor, it is the most dangerous of the three radiation listed for the human body. To shield the rays, you need to use special devices. This will require good and durable materials: water, lead and concrete.
X-ray
Ionizing radiation is formed in the process of working with a tube, complex installations. The characteristic resembles gamma rays. The difference lies in the origin, wavelength. There is a penetrating factor.
Neutron
Neutron radiation is a flux of uncharged neutrons that are part of the nuclei, except for hydrogen. As a result of irradiation, substances receive a portion of radioactivity. There is the largest penetrating factor. All these types of ionizing radiation are very dangerous.
Main sources of radiation
Sources of ionizing radiation are artificial, natural. Basically, the human body receives radiation from natural sources, these include:
- terrestrial radiation;
- internal irradiation.
As for the sources of terrestrial radiation, many of them are carcinogenic. These include:
- Uranus;
- potassium;
- thorium;
- polonium;
- lead;
- rubidium;
- radon.
The danger is that they are carcinogenic. Radon is a gas that has no smell, color or taste. It is seven and a half times heavier than air. Its decay products are much more dangerous than gas, so the impact on the human body is extremely tragic.
Artificial sources include:
- nuclear power;
- concentration factories;
- uranium mines;
- repositories with radioactive waste;
- X-ray machines;
- nuclear explosion;
- scientific laboratories;
- radionuclides that are actively used in modern medicine;
- lighting devices;
- computers and telephones;
- Appliances.
In the presence of these sources nearby, there is a factor of the absorbed dose of ionizing radiation, the unit of which depends on the duration of exposure to the human body.
The operation of sources of ionizing radiation occurs on a daily basis, for example: when you are working at a computer, watching TV or talking on a mobile phone or smartphone. All of these sources are carcinogenic to some extent, they can cause serious and fatal diseases.
The placement of sources of ionizing radiation includes a list of important, important work related to the development of a project for the location of irradiation facilities. All sources of radiation contain a specific unit of radiation, each of which has a specific effect on the human body. This includes the manipulations carried out for installation, the introduction of these installations into operation.
It should be noted that the disposal of sources of ionizing radiation is mandatory.
It is a process that helps to decommission generating sources. This procedure consists of technical, administrative measures that are aimed at ensuring the safety of personnel, the public, and there is also a protection factor environment... Carcinogenic sources and equipment are a huge hazard to the human body, so they must be disposed of.
Features of registration of radiation
Characterization of ionizing radiation shows that they are invisible, they have no smell and color, so they are difficult to notice.
For this, there are methods for registering ionizing radiation. As for the methods of detection, measurement, everything is carried out indirectly, some property is taken as a basis.
The following methods of detecting ionizing radiation are used:
- Physical: ionization, proportional counter, gas-discharge Geiger-Muller counter, ionization chamber, semiconductor counter.
- Calorimetric detection method: biological, clinical, photographic, hematological, cytogenetic.
- Luminescent: fluorescent and scintillation counters.
- Biophysical method: radiometry, calculation.
Dosimetry of ionizing radiation is carried out using instruments, they are able to determine the dose of radiation. The device includes three main parts - impulse counter, sensor, power supply. Dosimetry of radiation is possible thanks to a dosimeter, a radiometer.
Influences on the person
The effect of ionizing radiation on the human body is especially dangerous. The following consequences are possible:
- there is a factor of very deep biological change;
- there is a cumulative effect of a unit of absorbed radiation;
- the effect manifests itself over time, since a latent period is noted;
- all internal organs and systems have different sensitivity to a unit of absorbed radiation;
- radiation affects all offspring;
- the effect depends on the unit of absorbed radiation, radiation dose, duration.
Despite the use of radiation devices in medicine, their effect can be detrimental. The biological effect of ionizing radiation in the process of uniform irradiation of the body, in the calculation of 100% of the dose, the following occurs:
- bone marrow - a unit of absorbed radiation 12%;
- lungs - not less than 12%;
- bones - 3%;
- testes, ovaries- the absorbed dose of ionizing radiation is about 25%;
- thyroid gland- the unit of the absorbed dose is about 3%;
- mammary glands - approximately 15%;
- other tissues - the unit of the absorbed radiation dose is 30%.
As a result, various diseases up to oncology, paralysis and radiation sickness. It is extremely dangerous for children and pregnant women, as there is an abnormal development of organs and tissues. Toxins, radiation are sources of dangerous diseases.
Task (to warm up):
I'll tell you, my friends,
How to grow mushrooms:
Need to go to the field early in the morning
Move two pieces of uranium ...
Question: What is the total mass of pieces of uranium for a nuclear explosion to occur?
Answer(in order to see the answer - you need to select the text) : For uranium-235, the critical mass is about 500 kg. If we take a ball of such a mass, then the diameter of such a ball will be 17 cm.
Radiation, what is it?
Radiation (translated from English "radiation") is radiation that is applied not only to radioactivity, but also to a number of others physical phenomena, for example: solar radiation, thermal radiation, etc. Thus, in relation to radioactivity, it is necessary to use the phrase "ionizing radiation" adopted by the ICRP (International Commission on Radiation Protection) and radiation safety rules.
What is ionizing radiation?
Ionizing radiation - radiation (electromagnetic, corpuscular), which causes ionization (the formation of ions of both signs) of a substance (environment). The probability and number of ion pairs formed depends on the energy of the ionizing radiation.
Radioactivity, what is it?
Radioactivity - radiation from excited nuclei or spontaneous transformation of unstable atomic nuclei into nuclei of other elements, accompanied by the emission of particles or γ-quantum (s). The transformation of ordinary neutral atoms into an excited state occurs under the influence of external energies of various kinds. Further, the excited nucleus seeks to remove excess energy by radiation (emission of an alpha particle, electrons, protons, gamma quanta (photons), neutrons), until a stable state is reached. Many heavy nuclei (transuranium series in the periodic table - thorium, uranium, neptunium, plutonium, etc.) are initially in an unstable state. They are able to spontaneously disintegrate. This process is also accompanied by radiation. Such nuclei are called natural radionuclides.
This animation clearly shows the phenomenon of radioactivity.
The Wilson chamber (plastic box cooled to -30 ° C) is filled with isopropyl alcohol vapor. Julien Simon placed a 0.3-cm³ piece of radioactive uranium (uraninite mineral) in it. The mineral emits alpha particles and beta particles, as it contains U-235 and U-238. On the path of movement of α and beta particles are molecules of isopropyl alcohol.
Since the particles are charged (alpha - positive, beta - negative), they can take an electron from the alcohol molecule (alpha particle) or add electrons to the alcohol molecules of the beta particle). This, in turn, gives the molecules a charge, which then attracts uncharged molecules around them. When the molecules clump together, they produce noticeable white clouds, which is clearly visible in the animation. So we can easily trace the paths of the ejected particles.
α particles create straight, dense clouds, while beta particles create long ones.
Isotopes, what are they?
Isotopes are a variety of atoms of the same chemical element, having different mass numbers, but including the same electric charge atomic nuclei and, therefore, occupying periodic system elements of D.I. Mendeleev single place. For example: 131 55 Cs, 134 m 55 Cs, 134 55 Cs, 135 55 Cs, 136 55 Cs, 137 55 Cs. Those. charge largely determines the chemical properties of the element.
There are isotopes stable (stable) and unstable (radioactive isotopes) - spontaneously decaying. About 250 stable and about 50 natural radioactive isotopes are known. An example of a stable isotope is 206 Pb, which is the end product of the decay of the natural radionuclide 238 U, which in turn appeared on our Earth at the beginning of mantle formation and is not associated with technogenic pollution.
What types of ionizing radiation are there?
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 meet with them in Everyday life much less frequently. Each type of radiation has its own nuclear-physical characteristics and, as a consequence, different biological effects on the human body. Radioactive decay can be accompanied by one of the types of radiation or several at once.
Sources of radioactivity can be natural or artificial. Natural sources of ionizing radiation are radioactive elements found in earth crust and forming a natural background radiation together with cosmic radiation.
Artificial sources of radioactivity are usually formed in nuclear reactors or accelerators based on nuclear reactions. Sources of artificial ionizing radiation can also be a variety of electrical vacuum physical devices, charged particle accelerators, etc. For example: a TV picture tube, an X-ray tube, a kenotron, etc.
Alpha radiation (α radiation) - corpuscular ionizing radiation, consisting of alpha particles (helium nuclei). Formed during radioactive decay and nuclear transformations. Helium nuclei have a fairly large mass and energy up to 10 MeV (Megaelectron-Volt). 1 eV = 1.6 ∙ 10 -19 J. Having an insignificant range in the air (up to 50 cm), they pose a high danger to biological tissues if they contact the skin, mucous membranes of the eyes and respiratory tract, if they enter the body in the form of dust or gas ( radon-220 and 222). The toxicity of alpha radiation is due to the colossal high ionization density due to its high energy and mass.
Beta radiation (β-radiation) - corpuscular electron or positron ionizing radiation of the corresponding sign with a continuous energy spectrum. It is characterized by the maximum energy of the spectrum E β max, or the average energy of the spectrum. The range of electrons (beta particles) in the air reaches several meters (depending on the energy), in biological tissues the range of a beta particle is several centimeters. Beta radiation, like alpha radiation, is a hazard due to contact radiation (surface contamination), for example, if it gets inside the body, on mucous membranes and skin.
Gamma radiation (γ-radiation or gamma quanta) - short-wave electromagnetic (photon) radiation with a wavelength
X-rays - by their own physical properties similar to gamma radiation, but with a number of features. It appears in the X-ray tube due to the abrupt stop of electrons on the ceramic target-anode (the place where the electrons strike is made, as a rule, of copper or molybdenum) after acceleration in the tube (continuous spectrum - bremsstrahlung) and when electrons are knocked out of the internal electronic shells of the target atom (line spectrum). The energy of X-ray radiation is low - from fractions of a few eV to 250 keV. X-rays can be obtained using charged particle accelerators - synchrotron radiation with a continuous spectrum having an upper limit.
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?
Ionizing radiation source (IRS) - an object that includes a radioactive substance or technical device that creates or, in certain cases, is capable of creating ionizing radiation. Distinguish between closed and open sources of radiation.
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 as a result radioactive decay is reduced by half. This value 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 Becquerel (Bq) - named after the French physicist who discovered radioactivity in 1896), Henri Becquerel. One Bq is equal to 1 nuclear transformation per second. The power of the radioactive source is measured in Bq / s, respectively. The ratio of the activity of a radionuclide in a sample to the mass of a sample is called the specific activity of a radionuclide and is measured in Bq / kg (l).
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 proposed to measure the dose at a depth d equal to 10 mm to assess human exposure. The measured value of the dose at this depth is called the ambient dose equivalent, measured in sieverts (Sv). In fact, this is a calculated value, where the absorbed dose is multiplied by a weighting factor for a given type of radiation and a factor characterizing the sensitivity of various organs and tissues to a particular type of radiation.
The equivalent dose (or the often used term “dose”) is equal to the product of the absorbed dose and the quality factor of exposure to ionizing radiation (for example: the quality factor of exposure to gamma radiation is 1, and alpha radiation is 20).
The unit of measure for the equivalent dose is rem (biological equivalent of an X-ray) and its sub-multiples: millirem (mrem) microrem (microrem), etc., 1 rem = 0.01 J / kg. The unit of measurement of the equivalent dose in the SI system is sievert, Sv,
1 Sv = 1 J / kg = 100 rem.
1 mrem = 1 * 10 -3 rem; 1 μrem = 1 * 10 -6 rem;
Absorbed dose - the amount of energy of ionizing radiation that is absorbed in an elementary volume, referred to the mass of matter in this volume.
The unit of the absorbed dose is rad, 1 rad = 0.01 J / kg.
The SI unit of absorbed dose is gray, Gy, 1 Gy = 100 rad = 1 J / kg
The equivalent dose rate (or dose rate) is the ratio of the equivalent dose to the time interval of its measurement (exposure), unit of measure rem / hour, Sv / hour, μSv / s, etc.
What units are alpha and beta radiation measured in?
The amount of alpha and beta radiation is defined as the flux density of particles per unit area, per unit time - a-particles * min / cm 2, β-particles * min / cm 2.
What is radioactive around us?
Almost everything that surrounds us, even the person himself. Natural radioactivity is to some extent a natural human habitat, if it does not exceed natural levels. There are areas on the planet with an increased relative to the average level of the radiation background. However, in most cases, no significant deviations in the state of health of the population are observed, since this territory is their natural environment a habitat. An example of such a piece of land is, for example, the state of Kerala in India.
For a true assessment of the frightening figures that sometimes appear in print, one should distinguish:
- natural, natural radioactivity;
- technogenic, i.e. changes in the radioactivity of the environment under the influence of man (mining, emissions and discharges of industrial enterprises, emergencies and much more).
As a rule, it is almost impossible to eliminate elements of natural radioactivity. How can you get rid of 40 K, 226 Ra, 232 Th, 238 U, which are everywhere in the earth's crust and are found in almost everything that surrounds us, and even in ourselves?
Of all natural radionuclides, the decay products of natural uranium (U-238) - radium (Ra-226) and radioactive gas radon (Ra-222) - pose the greatest danger to human health. The main "suppliers" of radium-226 to the environment are enterprises engaged in the extraction and processing of various fossil materials: mining and processing of uranium ores; oil and gas; coal industry; production building materials; energy industry enterprises, etc.
Radium-226 is highly susceptible to leaching from uranium containing minerals. This property explains the presence of large amounts of radium in some types of groundwater (some of them enriched with radon gas are used in medical practice), in mine waters. Radium content range in groundwater varies from units to tens of thousands of Bq / l. Radium content in surface natural waters 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, so for the most part concentrates in cellars, basements, basement floors buildings, in mine workings, etc.
It is believed that up to 70% of the exposure of the population to radiation is associated with radon in residential buildings.
The main source of radon intake in residential buildings are (as the importance increases):
- tap water and gas;
- building materials (crushed stone, granite, marble, clay, slags, etc.);
- soil under buildings.
In more detail about radon and a device for measuring it: RADON AND TORON RADIOMETERS.
Professional radon radiometers cost unaffordable money, for household use - we recommend that you pay attention to a household radon and thoron radiometer made in Germany: Radon Scout Home.
What are "black sands" and how dangerous are they?
"Black sands" (the color varies from light yellow to red-brown, brown, there are varieties of white, greenish tint and black) are the mineral monazite - anhydrous phosphate of the elements of the thorium group, mainly cerium and lanthanum (Ce, La) PO 4 which are replaced by thorium. Monazite contains up to 50-60% of 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%. Occurs in pegmatites, sometimes in granites and gneisses. When destroyed rocks containing monazite, it is collected in placers, which are large deposits.
Placers of monazite sands existing on land, as a rule, do not significantly change the resulting radiation environment. But the deposits of monazite located near coastal strip Sea of Azov(within the Donetsk region), in the Urals (Krasnoufimsk) and other regions create a number of problems associated with the possibility of irradiation.
For example, because of the sea surf during the autumn-spring period on the coast, as a result of natural flotation, a significant amount of "black sand" is accumulated, characterized by high content thorium-232 (up to 15-20 thousand Bq / kg and more), which creates in local areas the levels of gamma radiation of the order of 3.0 and more μSv / hour. Naturally, it is unsafe to rest in such areas, so this sand is collected every year, warning signs are displayed, and some parts of the coast are closed.
Means for measuring radiation and radioactivity.
To measure the levels of radiation and the content of radionuclides in different objects are used special means measurements:
- 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 present a large number of dosimeters of various types to solve different tasks radiation monitoring and having ample opportunities.
For example, dosimeters that are most often used in professional activities:
- Dosimeter-radiometer MKS-AT1117M(search dosimeter-radiometer) - a professional radiometer is used to search for and identify sources of photon radiation. It has a digital indicator, the ability to set the threshold for the sound signaling device, which greatly facilitates the work when examining territories, checking scrap metal, etc. Remote detection unit. A NaI scintillation crystal is used as a detector. The dosimeter is a versatile solution to various tasks; it is completed with a dozen different detecting units with different technical characteristics. Measuring units allow you to measure alpha, beta, gamma, X-ray and neutron radiation.
Information about detecting units and their application:
|
Detection unit name |
Measured radiation |
Main feature (technical specification) |
Application area |
|
OBD for alpha radiation |
Measurement range 3.4 · 10 -3 - 3.4 · 10 3 Bq · cm -2 |
DB for measuring the flux density of alpha particles from the surface |
|
|
OBD for beta radiation |
Measurement range 1 - 5 · 10 5 part./ (min · cm 2) |
DB for measuring the flux density of beta particles from the surface |
|
|
OBD for gamma radiation |
Sensitivity 350 cps -1 / μSvh -1 measurement range 0.03 - 300 μSv / h |
The best option for the price, quality, specifications... It is widely used in the field of gamma radiation measurement. A good search block for detecting radiation sources. |
|
|
OBD for gamma radiation |
Measurement range 0.05 μSv / h - 10 Sv / h |
A detector unit with a very high upper threshold for measuring gamma radiation. |
|
|
OBD for gamma radiation |
Measurement range 1 mSv / h - 100 Sv / h Sensitivity 900 cps -1 / μSvh -1 |
An expensive detector with a high measuring range and excellent sensitivity. Used to locate radiation sources with strong radiation. |
|
|
X-ray OBD |
Energy range 5 - 160 keV |
X-ray detection unit. It is widely used in medicine and installations working with the release of low-energy X-rays. |
|
|
DB for neutron radiation |
measurement range 0.1 - 10 4 neutrons / (s cm 2) Sensitivity 1.5 (cps -1) / (neutron s -1 cm -2) |
||
|
OBD for alpha, beta, gamma and X-ray radiation |
Sensitivity 6.6 cps -1 / μSv h -1 |
A universal detector unit that allows you to measure alpha, beta, gamma and X-ray radiation. Low cost and poor sensitivity. I found wide reconciliation in the field of attestation of workplaces (AWP), where it is mainly required to measure a local object. |
2. Dosimeter-radiometer DKS-96- designed to measure gamma and X-ray radiation, alpha radiation, beta radiation, neutron radiation.
In many ways it is similar to a dosimeter-radiometer.
- measurement of dose and rate of ambient dose equivalent (hereinafter dose and dose rate) Н * (10) and Н * (10) of continuous and pulsed X-ray and gamma radiation;
- measurement of the flux density of alpha and beta radiation;
- measurement of the dose H * (10) of neutron radiation and the dose rate H * (10) of neutron radiation;
- measurement of the flux density of gamma radiation;
- 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 terrain 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 to provide express analysis of standardized samples of metal heats for the presence of radiation and contamination.
9. HPGe detector based gamma spectrometer Spectrometers based on coaxial detectors made of HPGe (highly pure germanium) are designed to register gamma radiation in the energy range from 40 keV to 3 MeV.
MKS-AT1315 beta and gamma radiation spectrometer
NaI PAK Lead Shielded Spectrometer
Portable NaI spectrometer MKS-AT6101
Wearable HPGe spectrometer Eco PAK
Portable HPGe spectrometer Eco PAK
Automotive NaI PAK spectrometer
Spectrometer MKS-AT6102
Eco PAK spectrometer with electromachine cooling
Handheld PPD spectrometer Eco PAK
Explore other measuring instruments to measure ionizing radiation, you can on our website:
- 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 technique;
- to increase the reliability of dosimetric control, it is necessary to carry out several measurements (but not less than 3), then calculate the arithmetic mean;
- when measuring the background of the dosimeter on the ground, select areas 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 by the "envelope" method. At first glance, it is difficult to understand what is happening in the photograph. A giant mushroom seemed to grow from under the floor, and ghostly people in helmets seemed to be working next to it ...
At first glance, it is difficult to understand what is happening in the photograph. A giant mushroom seemed to grow from under the floor, and ghostly people in helmets seemed to be working next to it ...
There is something inexplicably creepy about this scene, and for a reason. This is the largest accumulation of possibly the most toxic substance ever created by man. This is nuclear lava or corium.
During the days and weeks after the Chernobyl accident nuclear power plant On April 26, 1986, simply walking into a room with the same pile of radioactive material - it was somberly nicknamed "elephant's leg" - meant certain death in a few minutes. Even a decade later, when this photograph was taken, the film was probably behaving strangely due to radiation, which manifested itself in a characteristic grain structure. The person in the photo, Artur Korneev, most likely visited this room more often than anyone else, so he was exposed, perhaps, to the maximum dose of radiation.
Surprisingly, in all likelihood, he is still alive. The story of how the United States took possession of a unique photograph of a person in the presence of incredibly toxic material is shrouded in mystery in itself - as well as the reasons why someone would need to take a selfie next to a hump of molten radioactive lava.
The photo first came to America in the late 90s, when the new government of the newly independent Ukraine took control of the Chernobyl nuclear power plant and opened the Chernobyl Center for Problems nuclear safety, radioactive waste and radioecology. Soon, the Chernobyl Center invited other countries to cooperate in nuclear safety projects. The US Department of Energy has ordered assistance by sending an order to Pacific Northwest National Laboratories (PNNL), a crowded research facility in Richland, PA. Washington.
At the time, Tim Ledbetter was one of the newcomers to PNNL's IT department and was tasked with building the library digital photos for the Nuclear Safety Project of the Department of Energy, that is, for showing photographs to the American public (more precisely, for that tiny part of the public that then had access to the Internet). He asked the project participants to take photographs during their trips to Ukraine, hired a freelance photographer, and also asked for materials from Ukrainian colleagues at the Chernobyl Center. Among hundreds of photographs of clumsy handshakes of officials and people in lab coats, however, there are a dozen photographs of the ruins inside the fourth power unit, where a decade earlier, on April 26, 1986, an explosion occurred during a test of a turbine generator.
As radioactive smoke rose above the village, poisoning the surrounding land, rods liquefied from below, melting through the walls of the reactor and forming a substance called corium.
When radioactive smoke rose above the village, poisoning the surrounding land, rods liquefied from below, melting through the walls of the reactor and forming a substance called corium .
Corium has formed outside research laboratories at least five times, says Mitchell Farmer, a lead nuclear engineer at Argonne National Laboratory, another US Department of Energy facility near Chicago. A corium once formed at the Three Mile Island reactor in Pennsylvania in 1979, once in Chernobyl, and three times during the meltdown of the Fukushima reactor in 2011. In his laboratory, Farmer created modified versions of the corium to better understand how to avoid similar incidents in the future. The study of the substance showed, in particular, that watering with water after the formation of the corium in reality prevents the decay of some elements and the formation of more dangerous isotopes.
Of the five cases of corium formation, only in Chernobyl nuclear lava was able to escape from the reactor. Without a cooling system, the radioactive mass crawled through the power unit for a week after the accident, absorbing molten concrete and sand, which were mixed with molecules of uranium (fuel) and zirconium (coating). This poisonous lava flowed downward, eventually melting the floor of the building. When inspectors finally entered the power unit a few months after the accident, they found an 11-ton, three-meter-long landslide in the corner of the steam distribution corridor below. Then it was called "elephant's leg". Over the next years, the "elephant leg" was cooled and crushed. But even today, its remnants are still several degrees warmer than the environment, as the decay of radioactive elements continues.
Ledbetter cannot remember exactly where he obtained these photographs. He put together a photo library nearly 20 years ago, and the website where they are hosted is still in good shape; only small copies of images were lost. (Ledbetter, still at PNNL, was surprised to learn that the photos are still available online.) But he remembers for sure that he did not send anyone to photograph the "elephant's leg", so it was most likely sent by one of his Ukrainian colleagues.
The photo began to circulate on other sites, and in 2013 Kyle Hill came across it when he was writing an article about the "elephant's leg" for Nautilus magazine. He traced her origins back to the PNNL lab. A long-lost description of the photo was found on the site: "Artur Korneev, deputy director of the Shelter, is studying nuclear lava" elephant's leg ", Chernobyl. Photographer: unknown. Autumn 1996". Ledbetter confirmed that the description matched the photograph.
Arthur Korneev- an inspector from Kazakhstan, who was engaged in the education of employees, telling and protecting them from the "elephant's leg" since its formation after the explosion at the Chernobyl nuclear power plant in 1986, a gloomy joke lover. Most likely, the last to speak to him was the NY Times reporter in 2014 in Slavutich, a city specially built for evacuated personnel from Pripyat (Chernobyl).
The photo was probably taken with a slower shutter speed than other photos to allow the photographer to appear in the frame, which explains the effect of movement and why the headlamp looks like lightning. The graininess in the photo is probably caused by radiation.
For Korneev, this particular visit to the power unit was one of several hundred dangerous trips to the core since his first day of operation in the days following the explosion. His first assignment was to detect fuel deposits and help measure radiation levels (the "elephant's leg" initially "glowed" at more than 10,000 roentgens per hour, which kills a person at a distance of a meter in less than two minutes). Shortly thereafter, he led a clean-up operation, when whole chunks of nuclear fuel sometimes had to be removed from the path. More than 30 people died from acute radiation sickness during the cleaning of the power unit. Despite the incredible dose of radiation received, Korneev himself continued to return to the hastily constructed concrete sarcophagus again and again, often with journalists to shield them from danger.
In 2001, he took an Associated Press reporter to the core, where radiation levels were 800 roentgens per hour. In 2009, renowned fictional writer Marcel Theroux wrote an article for Travel + Leisure about his trip to the sarcophagus and about a crazy escort without a gas mask who mocked Teru’s fears and said it was "pure psychology." Although Theroux referred to him as Viktor Korneev, Arthur was in all likelihood the person, since he dropped the same black jokes a few years later with a journalist from the NY Times.
His current occupation is unknown. When the Times found Korneev a year and a half ago, he was helping build the vault for the sarcophagus, a $ 1.5 billion project due to be completed in 2017. It is planned that the vault will completely close the Vault and prevent isotope leakage. In his 60-something years, Korneev looked sickly, suffered from cataracts, and was banned from visiting the sarcophagus after repeated exposure in previous decades.
However, Korneev's sense of humor remained unchanged... He seems to have no regrets about his life's work: "Soviet radiation," he jokes, "is the best radiation in the world." .
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✪ More about radiation
✪ Penetrating power. Types of radioactive radiation
✪ Composition of radioactive radiation
✪ Influence of radioactive radiation on living organisms
✪ Rules of behavior and actions of the population in case of radiation accidents and radioactive contamination of localities
Subtitles
Hello. In this issue of TranslatorsCafe.com we will talk about ionizing radiation or radiation. We will consider the sources of radiation, methods of measuring it, the effect of radiation on living organisms. We will talk in more detail about such parameters of radiation as the absorbed dose rate, as well as about the equivalent and effective doses of ionizing radiation. Radiation has many uses, from generating electricity to treating cancer patients. In this video, we will discuss how radiation affects the tissues and cells of humans, animals and biomaterial, focusing on how quickly and how severely irradiated cells and tissues are damaged. Radiation is a natural phenomenon that manifests itself in the fact that electromagnetic waves or elementary particles with high kinetic energy move inside the medium. In this case, the medium can be either matter or vacuum. Radiation is around us, and our life is unthinkable without it, since the survival of humans and other animals is impossible without radiation. Without radiation, there will be no such natural phenomena as light and heat necessary for life on Earth. There would be no mobile phones or the Internet. In this video we will discuss a special type of radiation, ionizing radiation or radiation that surrounds us everywhere. Ionizing radiation has energy sufficient to detach electrons from atoms and molecules, that is, to ionize the irradiated substance. Ionizing radiation in the environment can arise due to either natural or artificial processes. Natural sources of radiation include solar and cosmic radiation, certain minerals such as granite, and radiation from certain radioactive materials such as uranium and even bananas containing the radioactive isotope of potassium. Radioactive raw materials are mined deep in the earth's interior and used in medicine and industry. Occasionally, radioactive materials are released into the environment as a result of industrial accidents and industries that use radioactive raw materials. Most often this happens due to non-compliance with safety rules for storing and working with radioactive materials or due to the absence of such rules. It is worth noting that, until recently, radioactive materials were not considered hazardous to health. On the contrary, they were used as medicinal preparations, and they were also appreciated for their beautiful glow. Uranium glass is an example of a radioactive material used for decorative purposes. This glass glows with a fluorescent green light due to the addition of uranium oxide to its composition. The percentage of uranium in this glass is relatively small and the amount of radiation emitted by it is small, therefore, uranium glass is considered relatively safe for health. They even made glasses, plates and other utensils from it. Uranium glass is prized for its unusual glow. The sun emits ultraviolet light, so uranium glass glows in sunlight as well, although this glow is much more pronounced under ultraviolet light bulbs. When emitted, photons with higher energy (ultraviolet) are absorbed and photons with lower energy (green) are emitted. As you have seen, these beads can be used to test dosimeters. You can buy a bag of beads on eBay.com for a couple of dollars. Let's look at some definitions first. There are many ways to measure radiation, depending on what exactly we want to know. For example, you can measure the total amount of radiation in a given location; you can find the amount of radiation that disrupts the work of biological tissues and cells; or the amount of radiation absorbed by the body or organism, and so on. Here we will look at two ways to measure radiation. The total amount of radiation in the environment, measured per unit of time, is called the total dose rate of ionizing radiation. The amount of radiation absorbed by the body per unit of time is called the absorbed dose rate. The absorbed dose rate is found using information on the total dose rate and on the parameters of an object, organism, or part of the body that is exposed to radiation. These parameters include mass, density and volume. The values of the absorbed and exposure dose are similar for materials and tissues that absorb radiation well. However, not all materials are such, therefore, the absorbed and exposure doses of radiation are often different, since the ability of an object or body to absorb radiation depends on the material of which they are made. For example, a sheet of lead absorbs gamma radiation much better than a sheet of aluminum of the same thickness. We know that a large dose of radiation, called an acute dose, is a health hazard, and the higher the dose, the higher the health risk. We also know that radiation affects different cells in the body in different ways. Cells that undergo frequent division, as well as non-specialized cells, suffer the most from radiation. For example, cells in the embryo, blood cells, and cells of the reproductive system are most susceptible to the negative effects of radiation. At the same time, skin, bones, and muscle tissue are less exposed to radiation. But the least radiation affects nerve cells... Therefore, in some cases, the overall destructive effect of radiation on cells that are less exposed to radiation is less, even if they are exposed to a greater amount of radiation than on cells that are more exposed to radiation. According to the theory of radiation hormesis, small doses of radiation, on the contrary, stimulate defense mechanisms in the body, and as a result, the body becomes stronger and less susceptible to disease. It should be noted that these studies are at an early stage, and it is not yet known whether it will be possible to obtain such results outside the laboratory. Now these experiments are carried out on animals and it is not known whether these processes occur in the human body. For ethical reasons, it is difficult to obtain approval for such research involving humans. The absorbed dose is the value of the ratio of the energy of ionizing radiation absorbed in a given volume of a substance to the mass of a substance in this volume. The absorbed dose is the main dosimetric quantity and is measured in joules per kilogram. This unit is called gray. Previously, the off-system unit was used rad. The absorbed dose depends not only on the radiation itself, but also on the material that absorbs it: the absorbed dose of soft X-ray radiation in the bone tissue can be four times the absorbed dose in the air. At the same time, in a vacuum, the absorbed dose is zero. Equivalent dose characterizing the biological effect of radiation human body ionizing radiation, measured in sieverts. To understand the difference between dose and dose rate, you can draw an analogy with a kettle, into which tap water is poured. The volume of water in the kettle is the dose, and the filling rate, which depends on the thickness of the stream of water, is the dose rate, that is, the increment in the radiation dose per unit time. The equivalent dose rate is measured in sieverts per unit of time, for example, microsieverts per hour or millisieverts per year. Radiation is generally invisible to the naked eye, therefore, special measuring devices are used to determine the presence of radiation. One of the widely used devices is a dosimeter based on a Geiger-Muller counter. The counter consists of a tube in which the number of radioactive particles is counted, and a display that displays the number of these particles in different units, most often as the amount of radiation over a certain period of time, for example, an hour. Geiger counter instruments often emit short beeps, such as clicks, each indicating that a new emitted particle or more particles have been counted. This sound can usually be turned off. Some dosimeters allow you to select the frequency of clicks. For example, you can configure the dosimeter to beep only after every twentieth particle counted or less often. In addition to Geiger counters, other sensors are used in dosimeters, for example, scintillation counters, which make it possible to better determine what type of radiation is on this moment prevails in the environment. Scintillation counters are good at detecting both alpha and beta and gamma radiation. These counters convert the radiation energy into light, which is then converted in a photomultiplier into an electrical signal, which is measured. During measurements, these counters work with a larger surface than Geiger counters, so the measurements are more efficient. Ionizing radiation has a very high energy, and therefore it ionizes the atoms and molecules of biological material. As a result, electrons are separated from them, which leads to a change in their structure. These changes are caused by ionization weakening or breaking the chemical bonds between particles. This damages and disrupts molecules inside cells and tissues. In some cases, ionization promotes the formation of new bonds. The disruption of cells depends on how much radiation has damaged their structure. In some cases, the violations do not affect the functioning of the cells. Sometimes the work of the cells is disrupted, but the damage is small and the body gradually restores the cells to a working state. Such violations are often found in the course of normal cell functioning, while the cells themselves return to normal. Therefore, if the radiation level is low and the disturbances are small, then it is quite possible to restore cells to their normal state. If the level of radiation is high, then irreversible changes occur in the cells. With irreversible changes, the cells either do not work as they should, or stop working altogether and die. Radiation damage to vital and irreplaceable cells and molecules, such as DNA and RNA molecules, proteins or enzymes, causes radiation sickness. Damage to cells can also cause mutations, which can lead to genetic diseases in the children of patients whose cells are affected. Mutations can also cause overly rapid cell division in patients' bodies - which in turn increases the likelihood of cancer. Today, our knowledge about the effect of radiation on the body and about the conditions under which this effect is aggravated is limited, since there is very little material at the disposal of researchers. Much of our knowledge is based on case studies of victims of the atomic bombings of Hiroshima and Nagasaki, as well as victims of the explosion at the Chernobyl nuclear power plant. It is also worth noting that some studies of the effect of radiation on the body, which were carried out in the 50s - 70s. last century, were unethical and even inhuman. In particular, this is research carried out by the military in the United States and the Soviet Union. Most of these experiments were carried out at proving grounds and in designated test areas. nuclear weapons, for example, at the test site in Nevada, USA, at the Soviet nuclear test site on Novaya Zemlya, and at the Semipalatinsk test site in the present territory of Kazakhstan. In some cases, experiments were carried out during military exercises, such as during the Totsk military exercises (USSR, in the present territory of Russia) and during the Desert Rock military exercises in Nevada, USA. During these exercises, researchers, if you can call them that, studied the effects of radiation on the human body after atomic explosions. From 1946 to the 1960s, experiments on the effect of radiation on the body were also carried out in some American hospitals without the knowledge and consent of patients. Thank you for the attention! If you enjoyed this video, please don't forget to subscribe to our channel!
The nature of ionizing radiation
The most significant types of ionizing radiation are:
- Shortwave electromagnetic radiation (flux of high energy photons):
- Particle Streams:
- beta particles (electrons and positrons);
- protons, muons and other elementary particles;
- Ions (fragments of fission arising from nuclear fission), including alpha particles.
Sources of ionizing radiation
- Spontaneous radioactive decay of radionuclides.
- Thermonuclear reactions, for example in the sun.
- Induced nuclear reactions as a result of hitting the nucleus of high-energy elementary particles or merging kernels.
Artificial sources of ionizing radiation:
- Artificial radionuclides.
- Elementary particle accelerators (generate streams of charged particles, as well as bremsstrahlung photon radiation).
- X-ray apparatus, as a kind of accelerators, generates bremsstrahlung X-ray radiation.
Induced radioactivity
Many stable atoms are converted into unstable isotopes as a result of irradiation and the corresponding induced nuclear reaction. As a result of such irradiation, the stable substance becomes radioactive, and the type of secondary ionizing radiation will differ from the initial irradiation. This effect is most clearly manifested after neutron irradiation.
Nuclear transformation chain
In the process of nuclear decay or fusion, new nuclides appear, which can also be unstable. The result is a chain of nuclear transformations. Each transformation has its own probability and its own set of ionizing radiation. As a result, the intensity and nature of the radiation from a radioactive source can vary significantly over time.
Measurement of ionizing radiation
Measurement methods
Historically, the first sensors for ionizing radiation were chemical photosensitive materials used in photography. Ionizing radiation illuminated a photographic plate placed in a light-tight envelope. However, they were quickly abandoned due to the length and cost of the process, the complexity of development and low information content.
As radiation sensors in everyday life and industry, dosimeters based on Geiger counters are most widely used. Geiger counter is a gas-discharge device in which ionization of a gas by radiation is converted into electricity between the electrodes. As a rule, such devices correctly register only gamma radiation. Some devices are supplied with a special filter converting beta radiation into gamma quanta due to bremsstrahlung. Geiger counters poorly select radiation in terms of energy, for this they use another type of gas-discharge counter, the so-called. proportional counter.
Scintillators are widely used in science. These devices convert the radiation energy into visible light due to absorption of radiation in a special substance. The flash of light is detected by a photomultiplier tube. Scintillators separate radiation well in terms of energy.
To study the fluxes of elementary particles, many other methods are used that make it possible to more fully investigate their properties, for example, a bubble chamber, a Wilson chamber.
Units
Interaction efficiency of ionizing radiation with a substance depends on the type of radiation, the energy of the particles and the cross section of the interaction of the irradiated substance. Important indicators of the interaction of ionizing radiation with matter:
- linear energy transfer (LET), which shows how much energy radiation transfers to a medium per unit path length at a unit density of matter.
- absorbed dose of radiation, showing what radiation energy is absorbed per unit mass of a substance.
Corpuscular ionizing radiation is also characterized by the kinetic energy of particles. To measure this parameter, the most common off-system unit electron-volt(Russian designation: eV, international: eV). Typically, a radioactive source generates particles with a specific energy spectrum. Radiation sensors also have uneven particle energy sensitivity.
Properties of ionizing radiation
According to the mechanism of interaction with matter, flows of charged particles and indirectly ionizing radiation (flows of neutral elementary particles - photons and neutrons) are emitted. According to the mechanism of formation - primary (born in the source) and secondary (formed as a result of the interaction of another type of radiation with matter) ionizing radiation.
The energy of particles of ionizing radiation ranges from several hundred electron volts (X-rays, beta radiation of some radionuclides) to 10 15 - 10 20 and higher electron volts (cosmic radiation protons for which no upper energy limit has been found).
The path length and penetrating power vary greatly - from micrometers in a condensed medium (alpha radiation from radionuclides, fission fragments) to many kilometers (high-energy muons of cosmic rays).
Impact on materials of construction
Long-term exposure to corpuscular radiation or ultrahigh-energy photon radiation can significantly change the properties of structural materials. Engineering discipline studies these changes. radiation materials science... The branch of physics dealing with the study of the behavior of solids under irradiation was named radiation physics solid ... The most significant types of radiation damage are:
- destruction crystal lattice due to knocking out atoms from nodes;
- ionization of dielectrics;
- The change chemical composition substances due to nuclear reactions.
Accounting for radiation damage to engineering structures is most relevant for nuclear reactors and semiconductor electronics designed to operate under radiation conditions.
Impact on semiconductors
Biological action of ionizing radiation
Different types of ionizing radiation have different destructive effects and different ways of acting on biological tissues. Accordingly, different biological efficiency of radiation corresponds to the same absorbed dose. Therefore, to describe the effect of radiation on living organisms, the concept of the relative biological effectiveness of radiation is introduced, which is measured using quality factor... For X-ray, gamma and beta radiation, the quality factor is taken as 1. For alpha radiation and nuclear fragments, the quality factor is 10 ... 20. Neutrons - 3 ... 20, depending on the energy. For charged particles, biological efficiency is directly related to the linear energy transfer of a given type of particle (the average energy loss by a particle per unit path length of a particle in a tissue).
Units
To take into account the biological effect of the absorbed dose, an equivalent absorbed dose of ionizing radiation was introduced, which is numerically equal to the product of the absorbed dose and the coefficient of biological effectiveness. In the SI system, the effective and equivalent absorbed dose is measured in sievert(Russian designation: Sv; international: Sv).
Previously, the unit of measure for equivalent dose was widely used rem(from b iological NS equivalent R an entgen for gamma radiation; Russian designation: rem; international: rem). Initially, the unit was defined as a dose of ionizing radiation producing the same biological effect as a dose of X-ray or gamma radiation, equal to 1 R. After the adoption of the SI system, rem was understood as a unit equal to 0.01 J / kg. 1 rem = 0.01 Sv = 100 erg / g.
In addition to biological effectiveness, it is necessary to take into account the penetrating power of radiation. For example, heavy nuclei of atoms and alpha particles have an extremely short path length in any dense substance, therefore, radioactive alpha sources are dangerous if they enter the body. On the contrary, gamma radiation has significant penetrating power.
Some radioactive isotopes are able to integrate into the metabolic process of a living organism, replacing inactive elements. This leads to the retention and accumulation of radioactive substances directly in living tissues, which significantly increases the risk of contact. For example, iodine-131, isotopes of strontium, plutonium, etc. are widely known. To characterize this phenomenon, the concept of the half-life of an isotope from the body is used.
Mechanisms of biological action
The direct action of ionizing radiation is a direct hit into the biological molecular structures of cells and into the liquid (water) environment of the body.
The main source of information on the stochastic effects of ionizing radiation exposure is data from observations of the health of people who survived atomic bombings or radiation accidents. Experts observed 87,500 atomic bomb survivors. The average dose of their irradiation was 240 millisievert... At the same time, the increase in oncological diseases in subsequent years was 9%. At doses less than 100 millisieverts, no one in the world has established a difference between the expected and observed incidence in reality.
Hygienic regulation of ionizing radiation
Rationing is carried out according to the sanitary rules and regulations SanPin 2.6.1.2523-09 "Standards of radiation safety (NRB-99/2009)". Dose limits for the effective dose are established for the following categories of persons:
- personnel - persons who work with man-made sources of radiation (group A) or who are under the working conditions in the area of their impact (group B);
- the entire population, including personnel, outside the scope and conditions in their production activities.
The main dose limits and permissible exposure levels for personnel in group B are equal to a quarter of the values for personnel in group A.
The effective dose for personnel should not exceed labor activity(50 years) 1000 mSv, and for the general population in a lifetime - 70 mSv. Planned increased exposure is allowed only for men over 30 years of age with their voluntary written consent after being informed about possible radiation doses and health risks.
51. Ionizing radiation. Types of ionizing radiation, main characteristics.
AI are divided into 2 types:
Corpuscular radiation
- 𝛼-radiation is a flux of helium nuclei emitted by matter during radioactive decay or nuclear reactions;
- 𝛽-radiation - the flow of electrons or positrons arising from radioactive decay;
Neutron radiation (In elastic interactions, the usual ionization of matter occurs. In inelastic interactions, secondary radiation arises, 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 source of γ-radiation, in X-ray tubes.
AI characteristics: energy (MeV); speed (km / s); mileage (in air, in living tissue); ionizing capacity (ion pairs per 1 cm of path in the air).
The lowest ionizing ability of α-radiation.
Charged particles result in 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.
Ionizing radiation (IR) is radiation, the interaction of which with the environment leads to the formation of charges of opposite signs. Ionizing radiation arises during radioactive decay, nuclear transformations, as well as during the interaction of charged particles, neutrons, photon (electromagnetic) radiation with matter.
Radiation dose- the quantity used to assess the effects of 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 [Pcm2 / (chmCi)], t is the exposure time, r is the distance from the source to the workplace [cm].
Dose rate(radiation intensity) - the increment of the corresponding dose under the influence of this radiation per unit. time.
Exposure dose rate [rh -1].
Absorbed dose shows the amount of AI energy absorbed by units. mass of the irradiated substance:
D absor. = D exp. K 1
where K 1 is a coefficient that takes into account the type of irradiated substance
Absorb. dose, Gray, [J / kg] = 1 Gray
Equivalent dose characterizes chronic irradiation with radiation of arbitrary composition
N = D Q [Sv] 1 Sv = 100 rem.
Q is a dimensionless weighting factor for a given type of radiation. For X-rays and -radiation Q = 1, for alpha-, beta-particles and neutrons Q = 20.
Effective equivalent dose har-et sensitivity decomp. organs and tissues to radiation.
Irradiation of inanimate objects - Absorb. dose
Irradiation of living objects - Equiv. dose
53. Effect of ionizing radiation(AI) on the body. External and internal exposure.
The biological effect of AI based on the ionization of living tissue, which leads to the rupture of molecular bonds and a change in the chemical structure of various compounds, which leads to a change in the DNA of cells and their subsequent death.
Violation of the vital processes of the body is expressed in such disorders as
Inhibition of the functions of hematopoietic organs,
Disruption of normal blood clotting and increased fragility of blood vessels,
Disorder of the gastrointestinal tract,
Decreased resistance to infection,
Exhaustion of the body.
External irradiation occurs when the source of radiation is located outside the human body and there is no way for them to get inside.
Internal irradiation origin when the source of AI is inside a person; while int. 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 ionizing radiation, occur at radiation doses throughout life
Radiation sickness - This is a disease that is characterized by symptoms arising from exposure to AI, such as a decrease in hematopoietic capacity, an upset of the gastrointestinal tract, and a decrease in immunity.
The degree of radiation sickness depends on the dose of radiation. 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.
Nonthreshold (stachastic) effects appear at doses of H<0,1 Зв/год, вероятность возникновения которых не зависит от дозы излучения.
Stachastic ef-there include:
Somatic changes
Immune changes
Genetic changes
Rationing principle - i.e. not exceeding the permissible limits of the individual. Radiation doses from all sources of AI.
Justification principle - i.e. the prohibition of all types of activities for the use of the sources of AI, 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 - maintaining at the lowest possible and achievable level, taking into account the economic. and social factors of the individual. radiation doses and the number of exposed persons when using an IR source.
SanPiN 2.6.1.2523-09 "Radiation Safety Standards".
In accordance with this document, 3 grams are allocated. persons:
group A - these are persons, nepos. working with man-made sources of AI
gr .B - these are the persons, the services of the work of the cat nah-sya in neposr. breeze from the source of AI, but active. of these persons not connected with the source.
gr .V - this is the rest of the population, incl. persons gr. A and B outside their production activities.
The main dose limit set. effective dose:
For persons group A: 20mSv per year on Wed. followed by. 5 years, but not more than 50 mSv in year.
For persons group B: 1mSv per year on Wed. followed by. 5 years, but not more than 5 mSv in year.
For persons group B: should not exceed ¼ values for personnel group A.
In case of an emergency caused by a radiation accident, there is a so-called. peak increased exposure, cat. is allowed only in cases where it is not possible to take measures to exclude harm to the body.
The use of such doses may be. justified only by saving lives and preventing accidents, only for men over 30 years old with a voluntary written agreement.
M / d AI protection:
Quantity protection
Time protection
Dist-em protection
Zoning
Remote control
Shielding
To protect againstγ - radiation: metallic screens made with high atomic weight (W, Fe), as well as from concrete, cast iron.
For protection against β-radiation: materials with low atomic mass (aluminum, plexiglase) are used.
For protection against α-radiation: use metals containing H2 (water, paraffin, etc.)
Screen thickness K = Ro / Pdop, Ro - power. dose measured per rad. location; Pdop is the maximum permissible dose.
Zoning - division of the territory into 3 zones: 1) shelter; 2) objects and premises in which people can be found; 3) DC zone. stay of people.
Dosimetric control based on the use of the trace. Methods: 1. Ionization 2. Phonographic 3. Chemical 4. Calorimetric 5. Scintillation.
Basic devices , used for dosimetric control:
X-ray meter (for measuring the power of the exposure dose)
Radiometer (for measuring the flux density of AI)
Individual. dosimeters (for measuring exposure or absorbed dose).
Ionizing radiation is a combination of various types of microparticles and physical fields that have the ability to ionize matter, that is, to form electrically charged particles in it - ions. There are several types of ionizing radiation: alpha, beta, gamma radiation, as well as neutron radiation.
Alpha radiation
In the formation of positively charged alpha particles, 2 protons and 2 neutrons, which are part of helium nuclei, take part. Alpha particles are formed during the decay of an atomic nucleus and can have an initial kinetic energy of 1.8 to 15 MeV. The characteristic features of alpha radiation are high ionizing and low penetrating powers. When the alpha particles move very quickly, their energy is lost, and this leads to the fact that it is not enough even to overcome thin plastic surfaces. In general, external exposure to alpha particles, if we do not take into account the high-energy alpha particles obtained with the help of an accelerator, does not pose 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 have strong ionization. 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 have a greater penetrating power than alpha rays - they can cause chemical reactions, luminescence, ionize gases, and have an effect on photographic plates. As a protection against the flux of charged beta particles (with an energy of no more than 1 MeV), it will be enough to use an ordinary aluminum plate 3-5 mm thick.
Photonic radiation: gamma radiation and X-rays
Photon radiation includes two types of radiation: X-rays (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, uncharged photons. Unlike alpha and beta rays, gamma particles are not deflected by magnetic and electric fields and have a significantly higher penetrating power. In certain quantities and for a certain duration of exposure, gamma radiation can cause radiation sickness and lead to the occurrence of various cancers. Only such heavy chemical elements as, for example, lead, depleted uranium and tungsten can prevent the spread of the flux of gamma particles.
Neutron radiation
Nuclear explosions, nuclear reactors, laboratory and industrial installations can be a source of neutron radiation. The 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 distinguished by a high penetrating ability with a weak 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 also solutions of heavy metal hydroxides.
How do ionizing radiation affect substances?
All types of ionizing radiation, to one degree or another, have an effect on 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 background radiation will not bring any particular 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 radiation exposure to the body.
