ionizing called radiation, which, passing through the medium, causes ionization or excitation of the molecules of the medium. Ionizing radiation, like electromagnetic radiation, is not perceived by the human senses. Therefore, it is especially dangerous, since a person does not know that he is exposed to it. Ionizing radiation is otherwise called radiation.
Radiation is a stream of particles (alpha particles, beta particles, neutrons) or electromagnetic energy of very high frequencies (gamma or x-rays).
Pollution of the production environment with substances that are sources of ionizing radiation is called radioactive contamination.
Nuclear pollution is a form of physical (energy) pollution associated with the excess of the natural level of radioactive substances in the environment as a result of human activities.
Substances are made up of tiny particles of chemical elements - atoms. The atom is divisible and has a complex structure. At the center of an atom of a chemical element is a material particle called the atomic nucleus, around which electrons revolve. Most of the atoms of chemical elements have great stability, i.e., stability. However, in a number of elements known in nature, the nuclei spontaneously decay. Such elements are called radionuclides. The same element can have several radionuclides. In this case they are called radioisotopes chemical element. Spontaneous decay of radionuclides is accompanied by radioactive radiation.
Spontaneous decay of the nuclei of certain chemical elements (radionuclides) is called radioactivity.
Radioactive radiation can be of various types: streams of particles with high energy, an electromagnetic wave with a frequency of more than 1.5.10 17 Hz.
The emitted particles come in many forms, but the most commonly emitted are alpha particles (α-radiation) and beta particles (β-radiation). The alpha particle is heavy and has high energy; it is the nucleus of the helium atom. A beta particle is about 7336 times lighter than an alpha particle, but can also have high energy. Beta radiation is a stream of electrons or positrons.
Radioactive electromagnetic radiation (it is also called photon radiation), depending on the frequency of the wave, is X-ray (1.5.10 17 ... 5.10 19 Hz) and gamma radiation (more than 5.10 19 Hz). Natural radiation is only gamma radiation. X-ray radiation is artificial and occurs in cathode ray tubes at voltages of tens and hundreds of thousands of volts.
Radionuclides, emitting particles, turn into other radionuclides and chemical elements. Radionuclides decay at different rates. The decay rate of radionuclides is called activity. The unit of measure of activity is the number of decays per unit of time. One disintegration per second is called a becquerel (Bq). Often another unit is used to measure activity - curie (Ku), 1 Ku = 37.10 9 Bq. One of the first radionuclides studied in detail was radium-226. It was studied for the first time by the Curies, after whom the unit of measure of activity is named. The number of decays per second occurring in 1 g of radium-226 (activity) is 1 Ku.
The time it takes for half of a radionuclide to decay is called half-life(T 1/2). Each radionuclide has its own half-life. The range of T 1/2 for various radionuclides is very wide. It changes from seconds to billions of years. For example, the best known natural radionuclide, uranium-238, has a half-life of about 4.5 billion years.
During decay, the amount of the radionuclide decreases and its activity decreases. The pattern by which activity decreases obeys the law of radioactive decay:
where BUT 0 - initial activity, BUT- activity over a period of time t.
Types of ionizing radiation
Ionizing radiation occurs during the operation of devices based on radioactive isotopes, during the operation of vacuum devices, displays, etc.
Ionizing radiations are corpuscular(alpha, beta, neutron) and electromagnetic(gamma, x-ray) radiation, capable of creating charged atoms and ion molecules when interacting with matter.
alpha radiation is a stream of helium nuclei emitted by matter during radioactive decay of nuclei or during nuclear reactions.
The greater the energy of the particles, the greater the total ionization caused by it in the substance. The range of alpha particles emitted by a radioactive substance reaches 8-9 cm in air, and in living tissue - several tens of microns. Having a relatively large mass, alpha particles quickly lose their energy when interacting with matter, which determines their low penetrating ability and high specific ionization, amounting to several tens of thousands of pairs of ions per 1 cm of the path in air.
Beta radiation - the flow of electrons or positrons resulting from radioactive decay.
The maximum range in the air of beta particles is 1800 cm, and in living tissues - 2.5 cm. The ionizing ability of beta particles is lower (several tens of pairs per 1 cm of range), and the penetrating power is higher than that of alpha particles.
Neutrons, the flux of which forms neutron radiation, transform their energy in elastic and inelastic interactions with atomic nuclei.
With inelastic interactions, secondary radiation arises, which can consist of both charged particles and gamma quanta (gamma radiation): with elastic interactions, ordinary ionization of a substance is possible.
The penetrating power of neutrons largely depends on their energy and the composition of the matter of the atoms with which they interact.
Gamma radiation - electromagnetic (photon) radiation emitted during nuclear transformations or particle interactions.
Gamma radiation has a high penetrating power and a low ionizing effect.
x-ray radiation arises in the environment surrounding the source of beta radiation (in X-ray tubes, electron accelerators) and is a combination of bremsstrahlung and characteristic radiation. Bremsstrahlung is photon radiation with a continuous spectrum emitted when the kinetic energy of charged particles changes; characteristic radiation is photon radiation with a discrete spectrum, emitted when the energy state of atoms changes.
Like gamma radiation, X-rays have a low ionizing power and a large penetration depth.
Sources of ionizing radiation
The type of radiation damage to a person depends on the nature of the sources of ionizing radiation.
The natural radiation background consists of cosmic radiation and radiation of naturally distributed radioactive substances.
In addition to natural exposure, a person is exposed to exposure from other sources, for example: in the production of x-rays of the skull - 0.8-6 R; spine - 1.6-14.7 R; lungs (fluorography) - 0.2-0.5 R; chest with fluoroscopy - 4.7-19.5 R; gastrointestinal tract with fluoroscopy - 12-82 R; teeth - 3-5 R.
A single irradiation of 25-50 rem leads to minor short-lived changes in the blood; at doses of 80-120 rem, signs of radiation sickness appear, but without a lethal outcome. Acute radiation sickness develops with a single irradiation of 200-300 rem, while a lethal outcome is possible in 50% of cases. Lethal outcome in 100% of cases occurs at doses of 550-700 rem. Currently, there are a number of anti-radiation drugs. weakening the effect of radiation.
Chronic radiation sickness can develop with continuous or repeated exposure to doses significantly lower than those that cause an acute form. The most characteristic signs of the chronic form of radiation sickness are changes in the blood, disorders of the nervous system, local skin lesions, damage to the lens of the eye, and a decrease in immunity.
The degree depends on whether the exposure is external or internal. Internal exposure is possible by inhalation, ingestion of radioisotopes and their penetration into the human body through the skin. Some substances are absorbed and accumulated in specific organs, resulting in high local doses of radiation. For example, iodine isotopes accumulating in the body can cause damage to the thyroid gland, rare earth elements can cause liver tumors, cesium and rubidium isotopes can cause soft tissue tumors.
Artificial sources of radiation
In addition to exposure from natural sources of radiation, which were and are always and everywhere, in the 20th century, additional sources of radiation associated with human activity appeared.
First of all, this is the use of X-rays and gamma radiation in medicine in the diagnosis and treatment of patients. , obtained with appropriate procedures, can be very large, especially in the treatment of malignant tumors with radiation therapy, when directly in the tumor zone they can reach 1000 rem or more. During x-ray examinations, the dose depends on the time of the examination and the organ that is being diagnosed, and can vary widely - from a few rem when taking a picture of a tooth to tens of rem when examining the gastrointestinal tract and lungs. Fluorographic images give the minimum dose, and preventive annual fluorographic examinations should by no means be abandoned. The average dose people receive from medical research is 0.15 rem per year.
In the second half of the 20th century, people began to actively use radiation for peaceful purposes. Various radioisotopes are used in scientific research, in the diagnostics of technical objects, in instrumentation, etc. And finally, nuclear power. Nuclear power plants are used at nuclear power plants (NPPs), icebreakers, ships, and submarines. Currently, more than 400 nuclear reactors with a total electrical capacity of over 300 million kW are operating at nuclear power plants alone. For the production and processing of nuclear fuel, a whole complex of enterprises united in nuclear fuel cycle(NFC).
The nuclear fuel cycle includes enterprises for the extraction of uranium (uranium mines), its enrichment (enrichment plants), the manufacture of fuel elements, nuclear power plants themselves, enterprises for the secondary processing of spent nuclear fuel (radiochemical plants), for the temporary storage and processing of nuclear fuel waste generated, and, finally, permanent disposal of radioactive waste (burial grounds). At all stages of the NFC, radioactive substances affect the operating personnel to a greater or lesser extent, at all stages, releases (normal or accidental) of radionuclides into the environment can occur and create an additional dose for the population, especially those living in the area of the NFC enterprises.
Where do radionuclides come from during normal operation of nuclear power plants? The radiation inside a nuclear reactor is enormous. Fuel fission fragments, various elementary particles can penetrate protective shells, microcracks and enter the coolant and air. A number of technological operations in the production of electrical energy at nuclear power plants can lead to water and air pollution. Therefore, nuclear power plants are equipped with a water and gas cleaning system. Emissions to the atmosphere are carried out through a tall chimney.
During normal operation of nuclear power plants, emissions to the environment are small and have little impact on the population living in the vicinity.
The greatest danger from the point of view of radiation safety is posed by plants for the processing of spent nuclear fuel, which has a very high activity. These enterprises generate a large amount of liquid waste with high radioactivity, there is a danger of developing a spontaneous chain reaction (nuclear hazard).
The problem of dealing with radioactive waste, which is a very significant source of radioactive contamination of the biosphere, is very difficult.
However, complex and costly from radiation at NFC enterprises make it possible to ensure the protection of humans and the environment to very small values, significantly less than the existing technogenic background. Another situation occurs when there is a deviation from the normal mode of operation, and especially during accidents. Thus, the accident that occurred in 1986 (which can be attributed to global catastrophes - the largest accident at the nuclear fuel cycle enterprises in the entire history of the development of nuclear power) at the Chernobyl nuclear power plant led to the release of only 5% of all fuel into the environment. As a result, radionuclides with a total activity of 50 million Ci were released into the environment. This release led to the exposure of a large number of people, a large number of deaths, the contamination of very large areas, the need for mass relocation of people.
The accident at the Chernobyl nuclear power plant clearly showed that the nuclear method of generating energy is possible only if large-scale accidents at nuclear fuel cycle enterprises are ruled out in principle.
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 stream of electrons or positrons arising from radioactive decay;
Neutron radiation (With 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 interaction of particles;
X-ray radiation - occurs in the environment surrounding the radiation source, in x-ray tubes.
AI characteristics: energy (MeV); speed (km/s); mileage (in air, in living tissue); ionizing capacity (pair of ions per 1 cm path in air).
The lowest ionizing ability of α-radiation.
Charged particles lead to direct, strong ionization.
Activity (A) of a radioactive substance is the number of spontaneous nuclear transformations (dN) in this substance in 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 units of their measurement.
Ionizing radiation (IR) is radiation, the interaction of which with the medium 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 is the value 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 [Rcm2/(hmCi)], t is the exposure 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 this radiation per unit. time.
Exposure dose rate [rh -1 ].
Absorbed dose shows how much AI energy is absorbed by the unit. masses of the irradiated in-va:
D absorption = D exp. K 1
where K 1 - coefficient taking into account the type of irradiated substance
Absorption dose, Gray, [J/kg]=1Gy
Dose equivalent characterized by chronic exposure to radiation of arbitrary composition
H = D Q [Sv] 1 Sv = 100 rem.
Q is a dimensionless weighting factor for a given type of radiation. For X-ray and -radiation Q=1, for alpha-, beta-particles and neutrons Q=20.
Effective equivalent dose character sensitivity decomp. organs and tissues to radiation.
Irradiation of inanimate objects - Absorb. dose
Irradiation of living objects - Equiv. dose
53. The effect of ionizing radiation(AI) on the body. External and internal exposure.
The biological effect of AI is based on the ionization of living tissue, which leads to the breaking 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 the hematopoietic organs,
Violation of normal blood clotting and increased fragility of blood vessels,
Disorder of the gastrointestinal tract,
Decreased resistance to infections
Depletion of the body.
External exposure occurs when the source of radiation is outside the human body and there are no ways for them to get inside.
Internal exposure origin when the source of AI is inside a person; while the internal Irradiation is also dangerous due to the proximity of the IR source to organs and tissues.
threshold effects (Н > 0.1 Sv/year) depend on the IR dose, occur with lifetime exposure doses
Radiation sickness is a disease that is characterized by symptoms that occur when exposed to AI, such as a decrease in hematopoietic ability, gastrointestinal upset, and a decrease in 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 exposure.
Non-threshold (stochastic) 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. non-exceeding of permissible limits individual. Radiation doses from all AI sources.
Justification principle – i.e. prohibition of all types of activity on the use of AI sources, in which the benefit received for a person and society does 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 the economic. and social individual factors. exposure doses and the number of exposed persons when using an AI source.
SanPiN 2.6.1.2523-09 "Radiation safety standards".
In accordance with this document, 3 gr. persons:
gr.A - these are faces, for sure. working with man-made sources of AI
gr .B - these are persons, conditions for the work of the cat nah-Xia in the immediate. breeze from the AI source, but deyat. these persons immediately. is not connected with the source.
gr .AT is the rest of the population, incl. persons gr. A and B outside of their production activities.
The main dose limit is set. by effective dose:
For persons gr.A: 20mSv per year on Wed. for the next 5 years, but not more than 50 mSv in year.
For persons group B: 1mSv per year on Wed. for the next 5 years, but not more than 5 mSv in year.
For persons group B: should not exceed ¼ of the 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 those cases when it is not possible to take measures excluding harm to the body.
The use of such doses can be justified only by saving lives and preventing accidents, additional only for men over 30 years of age with a voluntary written agreement.
AI protection m/s:
Qty protection
time protection
Distance protection
Zoning
Remote control
Shielding
For protection againstγ -radiation: metallic screens made with a large atomic weight (W, Fe), as well as from concrete, cast iron.
For protection against β-radiation: materials with a low atomic mass (aluminum, plexiglass) are used.
For protection against α-radiation: use metals containing H2 (water, paraffin, etc.)
Screen thickness К=Ро/Рdop, Ро – power. dose, measured per rad. place; Rdop - maximum allowable dose.
Zoning - division of the territory into 3 zones: 1) shelter; 2) objects and premises in which people can find; 3) zone post. stay of people.
Dosimetric control based on isp-ii trace. methods: 1. Ionization 2. Phonographic 3. Chemical 4. Calorimetric 5. Scintillation.
Basic appliances , used for dosimetric. control:
X-ray meter (for measuring powerful exp. doses)
Radiometer (to measure AI flux density)
Individual. dosimeters (for measuring exposure or absorbed dose).
Nuclear energy is quite actively used for peaceful purposes, for example, in the operation of an X-ray machine, an accelerator, which made it possible to spread ionizing radiation in the national economy. Given that a person is exposed to it on a daily basis, it is necessary to find out what the consequences of dangerous contact can be and how to protect yourself.
Main characteristic
Ionizing radiation is a kind of radiant energy that enters a specific environment, causing the process of ionization in the body. A similar 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.
Known varieties are radioactive irradiations, 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, toxins are released as a result of exposure to humans can cause cancer, radiation sickness.
It is necessary to note the following types of ionizing radiation that affect the human body:
Alpha
They are considered positively charged helium ions, which appear in the case of the decay of the nuclei of heavy elements. Protection from ionizing radiation is carried out using a paper sheet, cloth.
Beta
- a stream of negatively charged electrons that appear in the event of the decay of radioactive elements: artificial, natural. The damaging factor is much higher than that of the previous species. As protection, you need a thick screen, more durable. These radiations include positrons.
Gamma
- a hard electromagnetic oscillation that appears after the decay of the nuclei of radioactive substances. There is a high penetrating factor, which is the most dangerous radiation of the three 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 stream of uncharged neutrons, which are part of 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, 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;
- enrichment factories;
- uranium mines;
- burial grounds 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 daily, for example: when you work at a computer, watch a TV show or talk on a mobile phone, smartphone. All of these sources are to some extent carcinogenic, they can cause severe and fatal diseases.
The placement of sources of ionizing radiation includes a list of important, responsible work related to the development of a project for the location of irradiating installations. All radiation sources contain a certain unit of radiation, each of which has a certain effect on the human body. This includes manipulations carried out for installation, commissioning of these installations.
It should be pointed out 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 factor in protecting the environment. Carcinogenic sources and equipment are a huge danger to the human body, so they must be disposed of.
Features of registration of radiation
The characteristic 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 the basis.
The following methods for 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.
- Fluorescent: Fluorescent and scintillation counters.
- Biophysical method: radiometry, calculated.
Dosimetry of ionizing radiation is carried out with the help of devices that are able to determine the dose of radiation. The device includes three main parts - pulse counter, sensor, power supply. Radiation dosimetry is possible thanks to a dosimeter, a radiometer.
Influences on a 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, 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 effects 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, is the following:
- bone marrow - a unit of absorbed radiation 12%;
- lungs - at least 12%;
- bones - 3%;
- testicles, ovaries– the absorbed dose of ionizing radiation is about 25%;
- thyroid gland– unit of absorbed dose is about 3%;
- mammary glands - approximately 15%;
- other tissues - the unit of absorbed radiation dose is 30%.
As a result, various diseases can occur 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 - sources of dangerous diseases.
- Ionizing radiation is a type of energy released by atoms in the form of electromagnetic waves or particles.
- People are exposed to natural sources of ionizing radiation such as soil, water, plants, and man-made sources such as X-rays and medical devices.
- Ionizing radiation has numerous beneficial uses, including in medicine, industry, agriculture, and scientific research.
- As the use of ionizing radiation increases, so does the potential for health hazards if it is used or restricted inappropriately.
- Acute health effects such as skin burn or acute radiation syndrome can occur when the radiation dose exceeds certain levels.
- Low doses of ionizing radiation may increase the risk of longer term effects such as cancer.
What is ionizing radiation?
Ionizing radiation is a form of energy released by atoms in the form of electromagnetic waves (gamma or x-rays) or particles (neutrons, beta or alpha). The spontaneous decay of atoms is called radioactivity, and the excess energy that results from this is a form of ionizing radiation. Unstable elements formed during decay and emitting ionizing radiation are called radionuclides.
All radionuclides are uniquely identified by the type of radiation they emit, the energy of the radiation, and their half-life.
Activity, used as a measure of the amount of radionuclide present, is expressed in units called becquerels (Bq): one becquerel is one decay per second. The half-life is the time required for the activity of a radionuclide to decay to half its original value. The half-life of a radioactive element is the time it takes for half of its atoms to decay. It can range from fractions of a second to millions of years (for example, the half-life of iodine-131 is 8 days, and the half-life of carbon-14 is 5730 years).
Radiation sources
People are exposed to natural and artificial radiation every day. Natural radiation comes from numerous sources, including over 60 naturally occurring radioactive substances in soil, water and air. Radon, a naturally occurring gas, is formed from rocks and soil and is the main source of natural radiation. Every day people inhale and absorb radionuclides from air, food and water.
Humans are also exposed to natural radiation from cosmic rays, especially at high altitudes. On average, 80% of the annual dose that a person receives from background radiation is from naturally occurring terrestrial and space sources of radiation. The levels of such radiation vary in different rheographic zones, and in some areas the level can be 200 times higher than the global average.
Humans are also exposed to radiation from man-made sources, from nuclear power generation to the medical use of radiation diagnosis or treatment. Today, the most common artificial sources of ionizing radiation are medical devices, such as x-ray machines, and other medical devices.
Exposure to ionizing radiation
Exposure to radiation can be internal or external and can occur in a variety of ways.
Internal impact Ionizing radiation occurs when radionuclides are inhaled, ingested, or otherwise enter the circulation (eg, by injection, injury). Internal exposure stops when the radionuclide is excreted from the body, either spontaneously (with feces) or as a result of treatment.
External radioactive contamination can occur when radioactive material in the air (dust, liquid, aerosols) is deposited on the skin or clothing. Such radioactive material can often be removed from the body by simple washing.
Exposure to ionizing radiation may also occur as a result of external radiation from a suitable external source (eg, such as exposure to radiation emitted by medical x-ray equipment). External exposure stops when the radiation source is closed, or when a person goes outside the radiation field.
Exposure to ionizing radiation can be classified into three types of exposure.
The first case is planned exposure, which is due to the deliberate use and operation of radiation sources for specific purposes, for example, in the case of medical use of radiation for the diagnosis or treatment of patients, or use of radiation in industry or for scientific research purposes.
The second case is existing sources of exposure, where radiation exposure already exists and for which appropriate control measures need to be taken, such as exposure to radon in homes or workplaces, or exposure to natural background radiation in environmental conditions.
The last case is exposure to emergencies caused by unexpected events requiring prompt action, such as nuclear incidents or malicious acts.
Health effects of ionizing radiation
Radiation damage to tissues and/or organs depends on the received radiation dose or absorbed dose, which is expressed in grays (Gy). The effective dose is used to measure ionizing radiation in terms of its potential to cause harm. Sievert (Sv) is a unit of effective dose, which takes into account the type of radiation and the sensitivity of tissues and organs.
Sievert (Sv) is a unit of weighted dose of radiation, also called effective dose. It makes it possible to measure ionizing radiation in terms of the potential for harm. Sv takes into account the type of radiation and the sensitivity of organs and tissues.
Sv is a very large unit, so it is more practical to use smaller units such as millisievert (mSv) or microsievert (µSv). One mSv contains 1000 µSv, and 1000 mSv equals 1 Sv. In addition to the amount of radiation (dose), it is often useful to show the release rate of that dose, such as µSv/hour or mSv/year.
Above certain thresholds, exposure may impair tissue and/or organ function and may cause acute reactions such as reddening of the skin, hair loss, radiation burns, or acute radiation syndrome. These reactions are stronger at higher doses and higher dose rates. For example, the threshold dose for acute radiation syndrome is approximately 1 Sv (1000 mSv).
If the dose is low and/or a long period of time is applied (low dose rate), the resulting risk is significantly reduced, since in this case the likelihood of repair of damaged tissues increases. However, there is a risk of long-term consequences, such as cancer that may take years or even decades to appear. Effects of this type do not always appear, but their probability is proportional to the radiation dose. This risk is higher in the case of children and adolescents, as they are much more sensitive to the effects of radiation than adults.
Epidemiological studies in exposed populations, such as atomic bomb survivors or radiotherapy patients, have shown a significant increase in the likelihood of cancer at doses above 100 mSv. In some cases, more recent epidemiological studies in humans exposed as children for medical purposes (Childhood CT) suggest that the likelihood of cancer may be increased even at lower doses (in the range of 50-100 mSv) .
Prenatal exposure to ionizing radiation can cause fetal brain damage at high doses in excess of 100 mSv between 8 and 15 weeks of gestation and 200 mSv between 16 and 25 weeks of gestation. Human studies have shown that there is no radiation-related risk to fetal brain development before 8 weeks or after 25 weeks of gestation. Epidemiological studies suggest that the risk of developing fetal cancer after exposure to radiation is similar to the risk after exposure to radiation in early childhood.
WHO activities
WHO has developed a radiation program to protect patients, workers, and the public from the health hazards of radiation in planned, existing, and emergency exposures. This program, which focuses on public health aspects, covers activities related to exposure risk assessment, management and communication.
Under its core function of “norm-setting, enforcement and monitoring”, WHO is collaborating with 7 other international organizations to revise and update international standards for basic radiation safety (BRS). WHO adopted new international PRSs in 2012 and is currently working to support the implementation of PRSs in its Member States.
In everyday life, ionizing radiation is constantly encountered. We do not feel them, but we cannot deny their impact on animate and inanimate nature. Not so long ago, people learned to use them both for good and as weapons of mass destruction. With proper use, these radiations can change the life of mankind for the better.
Types of ionizing radiation
To understand the peculiarities of the influence on living and non-living organisms, you need to find out what they are. It is also important to know their nature.
Ionizing radiation is a special wave that can penetrate through substances and tissues, causing ionization of atoms. There are several types of it: alpha radiation, beta radiation, gamma radiation. All of them have a different charge and ability to act on living organisms.
Alpha radiation is the most charged of all types. It has tremendous energy, capable of causing radiation sickness even in small doses. But with direct irradiation, it penetrates only into the upper layers of human skin. Even a thin sheet of paper protects against alpha rays. At the same time, getting into the body with food or with inhalation, the sources of this radiation quickly become the cause of death.
Beta rays carry a slightly lower charge. They are able to penetrate deep into the body. With prolonged exposure, they cause death of a person. Smaller doses cause a change in the cellular structure. A thin sheet of aluminum can serve as protection. Radiation from within the body is also deadly.
The most dangerous is considered to be gamma radiation. It penetrates through the body. In large doses, it causes radiation burns, radiation sickness, and death. The only protection against it can be lead and a thick layer of concrete.
X-rays are considered to be a special kind of gamma radiation, which are generated in an X-ray tube.
Research History
For the first time, the world learned about ionizing radiation on December 28, 1895. It was on this day that Wilhelm K. Roentgen announced that he had discovered a special kind of rays that could pass through various materials and the human body. From that moment, many doctors and scientists began to actively work with this phenomenon.
For a long time, no one knew about its effect on the human body. Therefore, in history there are many cases of death from excessive exposure.
The Curies have studied in detail the sources and properties that ionizing radiation has. This made it possible to use it with maximum benefit, avoiding negative consequences.
Natural and artificial sources of radiation
Nature has created a variety of sources of ionizing radiation. First of all, it is the radiation of sunlight and space. Most of it is absorbed by the ozone layer, which is high above our planet. But some of them reach the surface of the Earth.
On the Earth itself, or rather in its depths, there are some substances that produce radiation. Among them are isotopes of uranium, strontium, radon, cesium and others.
Artificial sources of ionizing radiation are created by man for a variety of research and production. At the same time, the strength of radiation can be many times higher than natural indicators.
Even in conditions of protection and compliance with safety measures, people receive doses of radiation that are hazardous to health.
Units of measurement and doses
Ionizing radiation is usually correlated with its interaction with the human body. Therefore, all units of measurement are somehow related to the ability of a person to absorb and accumulate ionization energy.
In the SI system, doses of ionizing radiation are measured in units called grays (Gy). It shows the amount of energy per unit of irradiated substance. One Gy equals one J/kg. But for convenience, the off-system unit rad is more often used. It is equal to 100 Gr.
The radiation background on the ground is measured by exposure doses. One dose is equal to C/kg. This unit is used in the SI system. The off-system unit corresponding to it is called the roentgen (R). To obtain an absorbed dose of 1 rad, one must succumb to an exposure dose of about 1 R.
Since different types of ionizing radiation have a different charge of energy, its measurement is usually compared with biological influence. In the SI system, the unit of such an equivalent is the sievert (Sv). Its off-system counterpart is rem.
The stronger and longer the radiation, the more energy absorbed by the body, the more dangerous its influence. To find out the permissible time for a person to stay in radiation pollution, special devices are used - dosimeters that measure ionizing radiation. These are both devices for individual use, and large industrial installations.
Effect on the body
Contrary to popular belief, any ionizing radiation is not always dangerous and deadly. This can be seen in the example of ultraviolet rays. In small doses, they stimulate the generation of vitamin D in the human body, cell regeneration and an increase in melanin pigment, which gives a beautiful tan. But prolonged exposure causes severe burns and can cause skin cancer.
In recent years, the effect of ionizing radiation on the human body and its practical application has been actively studied.
In small doses, radiation does not cause any harm to the body. Up to 200 milliroentgens can reduce the number of white blood cells. The symptoms of such exposure will be nausea and dizziness. About 10% of people die after receiving such a dose.
Large doses cause digestive upset, hair loss, skin burns, changes in the cellular structure of the body, the development of cancer cells and death.
Radiation sickness
Prolonged action of ionizing radiation on the body and its receipt of a large dose of radiation can cause radiation sickness. More than half of the cases of this disease are fatal. The rest become the cause of a number of genetic and somatic diseases.
At the genetic level, mutations occur in germ cells. Their changes become evident in the next generations.
Somatic diseases are expressed by carcinogenesis, irreversible changes in various organs. Treatment of these diseases is long and rather difficult.
Treatment of radiation injuries
As a result of the pathogenic effects of radiation on the body, various lesions of human organs occur. Depending on the dose of radiation, different methods of therapy are carried out.
First of all, the patient is placed in a sterile ward to avoid the possibility of infection of open affected skin areas. Further, special procedures are carried out that contribute to the rapid removal of radionuclides from the body.
For severe lesions, a bone marrow transplant may be needed. From radiation, it loses the ability to reproduce red blood cells.
But in most cases, the treatment of mild lesions comes down to anesthesia of the affected areas, stimulating cell regeneration. Much attention is paid to rehabilitation.
Impact of ionizing radiation on aging and cancer
In connection with the influence of ionizing rays on the human body, scientists conducted various experiments proving the dependence of the processes of aging and carcinogenesis on the dose of radiation.
Groups of cell cultures were irradiated under laboratory conditions. As a result, it was possible to prove that even slight irradiation contributes to the acceleration of cell aging. Moreover, the older the culture, the more it is subject to this process.
Prolonged irradiation leads to cell death or abnormal and rapid division and growth. This fact indicates that ionizing radiation has a carcinogenic effect on the human body.
At the same time, the impact of waves on the affected cancer cells led to their complete death or to a stop in their division processes. This discovery helped develop a technique for treating human cancers.
Practical applications of radiation
For the first time, radiation began to be used in medical practice. With the help of X-rays, doctors managed to look inside the human body. At the same time, almost no harm was done to him.
Further, with the help of radiation, they began to treat cancer. In most cases, this method has a positive effect, despite the fact that the entire body is exposed to a strong effect of radiation, which entails a number of symptoms of radiation sickness.
In addition to medicine, ionizing rays are used in other industries. Surveyors using radiation can study the structural features of the earth's crust in its individual sections.
The ability of some fossils to release a large amount of energy, humanity has learned to use for its own purposes.
Nuclear power
Nuclear energy is the future of the entire population of the Earth. Nuclear power plants are sources of relatively inexpensive electricity. Provided that they are properly operated, such power plants are much safer than thermal power plants and hydroelectric power plants. From nuclear power plants, there is much less environmental pollution, both with excess heat and production waste.
At the same time, on the basis of atomic energy, scientists developed weapons of mass destruction. At the moment, there are so many atomic bombs on the planet that the launch of a small number of them can cause a nuclear winter, as a result of which almost all living organisms that inhabit it will die.
Means and methods of protection
The use of radiation in everyday life requires serious precautions. Protection against ionizing radiation is divided into four types: time, distance, number and shielding of sources.
Even in an environment with a strong radiation background, a person can stay for some time without harm to his health. It is this moment that determines the protection of time.
The greater the distance to the radiation source, the lower the dose of absorbed energy. Therefore, close contact with places where there is ionizing radiation should be avoided. This is guaranteed to protect against unwanted consequences.
If it is possible to use sources with minimal radiation, they are given preference in the first place. This is protection by quantity.
Shielding, on the other hand, means creating barriers through which harmful rays do not penetrate. An example of this is the lead screens in x-ray rooms.
household protection
In the event of a radiation disaster being declared, all windows and doors should be immediately closed, and try to stock up on water from sealed sources. Food should only be canned. When moving in an open area, cover the body as much as possible with clothing, and the face with a respirator or wet gauze. Try not to bring outerwear and shoes into the house.
It is also necessary to prepare for a possible evacuation: collect documents, a supply of clothes, water and food for 2-3 days.
Ionizing radiation as an environmental factor
There are quite a lot of areas contaminated with radiation on planet Earth. The reason for this is both natural processes and man-made disasters. The most famous of them are the Chernobyl accident and the atomic bombs over the cities of Hiroshima and Nagasaki.
In such places, a person cannot be without harm to his own health. At the same time, it is not always possible to find out in advance about radiation pollution. Sometimes even a non-critical radiation background can cause a disaster.
The reason for this is the ability of living organisms to absorb and accumulate radiation. At the same time, they themselves turn into sources of ionizing radiation. The well-known "black" jokes about Chernobyl mushrooms are based precisely on this property.
In such cases, protection against ionizing radiation is reduced to the fact that all consumer products are subject to careful radiological examination. At the same time, there is always a chance to buy the famous "Chernobyl mushrooms" in spontaneous markets. Therefore, you should refrain from buying from unverified sellers.
The human body tends to accumulate dangerous substances, resulting in a gradual poisoning from the inside. It is not known when exactly the effects of these poisons will make themselves felt: in a day, a year or a generation.
