Which radiation has the greatest ionizing ability? Nuclear educational program: ionizing radiation. Question. What is activity

It just so happened that from the very beginning, nuclear energy was created in deep secrecy and secrecy, including from its own people. She remained in this state for many years. As for educating the population on the basics of nuclear ecology and health protection from ionizing radiation, nuclear scientists practically did not deal with these issues. After all, the less people understand about these matters, the easier it is to “turn them off” or deceive them.

And it is no coincidence that the population of our region, living next to the large atomic research center RIAR, has very little or no understanding of even basic issues related to ionizing radiation.

In order to improve the situation, we decided in this issue of the “Civil Initiative” newsletter to open a nuclear education program and publish information on at least the basic concepts related to ionizing radiation or, as they say in everyday life, radiation. We had to sort through a lot of relevant material to select the clearest and most simple explanations. In the end, we chose information from the journal "Physics", taking it as a basis and supplementing it from other sources, including from the appendix to the book "Atomic Mythology" by corresponding member of the Russian Academy of Sciences A.V. Yablokov.

Below are answers to questions that appear in letters from our readers and in conversations with residents of the region.

Question. What is a nuclide, radionuclide, isotope?

Answer. Nuclide is called an atomic nucleus, characterized, firstly, by a certain nucleon composition (the number of protons and neutrons) and, secondly, by a certain energy state. Nuclei that have the same nucleonic composition but different energy states are called nuclear isomers. Nuclei that retain their nucleonic composition and energy state for an indefinitely long time are called stable; otherwise we are talking about radioactive nuclides, about radionuclides. There can be two or more nuclear isomers, but only one of them is a stable nuclide.

Radionuclides are often called isotopes. This is not true: the concept isotopes a set of nuclides (both stable and radioactive) is determined that have the same number of protons (and are therefore chemically identical, since these nuclides naturally have the same atomic number and are species of the same element from the periodic table).

Question. What is radioactivity and radiation?

Answer. Radioactivity there is the property of some radionuclides to change over time their nucleonic composition and (or) energy state with the formation of new nuclides (stable or again radioactive) and the emission of IONIZING RADIATION with greater or lesser PENETRATION. These radiations are colloquially called radiation.

Question. What is activity?

Answer. Activity radionuclide source or drug is the number of radioactive transformations in it per unit time. The unit of activity is becquerel(Bq) - activity of a source in which (on average, in a statistical sense) 1 radioactive transformation occurs in 1 second. In practical radiation measurements the following are often used:
kilobecquerel (1 kBq = 10 3 Bq);
megabecquerel (1 MBq = 10 6 Bq);
gigabecquerel (1 GBq = 10 9 Bq).

The non-system unit of activity is still often used - curie(Ki). 1 Ci corresponds to the activity of 1 g of radium-226 in equilibrium with its daughter decay products. The title and semantic content are echoes of the history of nuclear physics, one of the pages of which was the isolation of radium from uranium ore by Marie and Pierre Curie and the study of its properties.

1 Ci = 3.7*10 10 Bq (37 GBq) is a very large activity (in everyday terms), so in practice they often use:
millicurie (1 mCi = 10 -3 Ci);
microcurie (1 µCi = 10 -6 Ci);
nanocurie (1 nCi = 10 -9 Ci).

Question. Are all radiations ionizing? Which ones are ionizing?

Answer. No, not all, but only those whose energy is capable of causing ionization. For example, electromagnetic radiation in the range of radio waves or visible light is not ionizing radiation. Nuclear radiation, characterized by significant energy of each individual particle, is a different matter.

To consider processes and phenomena related to nuclear technology and energy, as well as radiation safety and radioecology, the following types of nuclear ionizing radiation are essential:

1. Alpha (a) radiation. This is the emission of nuclear particles, each of which consists of 2 protons and 2 neutrons (helium nucleus). It occurs during the decay of atomic nuclei heavier than lead (for example, uranium, thorium, radium, plutonium), as well as in many nuclear reactions. The entry of an alpha emitter into the body can cause biological damage to its cells, because The alpha particle carries a large amount of energy and its ionizing ability is very high.

2. Beta (b) radiation. This is the emission of electrons and positrons moving at very high speeds. It occurs mainly as a result of radioactive decay. The ionizing ability is significantly lower than that of a-radiation. However, beta particles are dangerous when they get on the surface of the body or inside the body.

3. Gamma (g) radiation- the shortest wavelength electromagnetic radiation of high energy and has the greatest penetrating ability. Accordingly, protection from external gamma radiation poses the greatest challenges.

Question. What is the penetrating power of radiation?

Answer. Penetrating power of radiation determines the composition and thickness of the material that effectively absorbs it.

a-radiation is the least penetrating. It is effectively absorbed by a layer of air several centimeters thick, a layer of water about 0.1 mm thick, or, for example, a sheet of paper. b-radiation has a significantly greater penetrating ability; to stop it, you need, for example, a layer of aluminum several millimeters thick, and the range of beta particles in biological tissue reaches several centimeters. For g-radiation, all these barriers are almost transparent. To detain it, you need a very thick (tens of centimeters and even meters) layer of a substance with as high an atomic number as possible (for example, lead).

The above is illustrated by the figure. It is easy to see that for a -, b - and g - radiations a simple pattern is observed: the higher the ionizing ability of the radiation, the lower the penetrating ability. This is not at all accidental - when these radiations interact with matter, the main part of the energy is spent on ionization.

Question. What are “exposure dose”, “absorbed dose”, “equivalent dose”, “effective equivalent dose” and what are their units of measurement?

Answer. Exposure dose- a measure of gamma radiation energy determined by the ionization of air. Expressed in Roentgens (R) per unit of time: Roentgen per hour (R/h) or micro-Roentgen per hour (µR/h), etc.

1 Roentgen is equal to 1000 milliRoentgens or 1,000,000 microRoentgens.

Absorbed dose- the amount of energy of any type of ionizing radiation absorbed by a unit mass of the irradiated substance (the main dosimetric quantity). The unit of absorbed dose is 1 Gray (Gy).

Equivalent dose- absorbed dose for different types of radiation (i.e. multiplied by a coefficient for different types of ionizing radiation), causing the same biological effect (the main dosimetric value for assessing damage to human health from chronic exposure to radiation of arbitrary composition). The coefficient for beta, gamma, and x-ray radiation is 1, for alpha radiation it is 20.

According to the SI system, the equivalent dose is measured in Sieverts (abbreviated as Sv). The name of this unit of measurement is given in memory of Sievert, a Swedish radiologist. Previously, we more often used another unit of measurement - the rem (the biological equivalent of an x-ray). 1 Sv is equal to 100 rem.

The derivative of the equivalent dose is effective equivalent dose- Sievert per unit of time. For example, milliSievert/year (abbreviated mSv/year), microSievert/year (abbreviated μSv/year).

Question. In what units is radiation pollution measured?

Answer. Radiation contamination of an area is expressed in Curies per square kilometer or Becquerels per square kilometer. Radioactive contamination of liquids, products and other substances is expressed in Becquerels per liter or kilogram (Bq/l, Bq/kg).

For information: You can obtain more detailed information from our Center for the Promotion of Civic Initiatives, where relevant literature is available on these issues.

Content

Radioactive radiation (or ionizing radiation) is energy that is released by atoms in the form of particles or waves of an electromagnetic nature. Humans are exposed to such exposure through both natural and anthropogenic sources.

The beneficial properties of radiation have made it possible to successfully use it in industry, medicine, scientific experiments and research, agriculture and other fields. However, with the spread of this phenomenon, a threat to human health has arisen. A small dose of radioactive radiation can increase the risk of acquiring serious diseases.

The difference between radiation and radioactivity

Radiation, in a broad sense, means radiation, that is, the spread of energy in the form of waves or particles. Radioactive radiation is divided into three types:

alpha radiation – flux of helium-4 nuclei;
beta radiation – flow of electrons;
Gamma radiation is a stream of high-energy photons.

The characteristics of radioactive radiation are based on their energy, transmission properties and the type of emitted particles.

Alpha radiation, which is a stream of corpuscles with a positive charge, can be delayed by thick air or clothing. This species practically does not penetrate the skin, but when it enters the body, for example, through cuts, it is very dangerous and has a detrimental effect on internal organs.

Beta radiation has more energy - electrons move at high speeds and are small in size. Therefore, this type of radiation penetrates through thin clothing and skin deep into the tissue. Beta radiation can be shielded using an aluminum sheet a few millimeters thick or a thick wooden board.

Gamma radiation is high-energy radiation of an electromagnetic nature that has a strong penetrating ability. To protect against it, you need to use a thick layer of concrete or a plate of heavy metals such as platinum and lead.

The phenomenon of radioactivity was discovered in 1896. The discovery was made by the French physicist Becquerel. Radioactivity is the ability of objects, compounds, elements to emit ionizing radiation, that is, radiation. The reason for the phenomenon is the instability of the atomic nucleus, which releases energy during decay. There are three types of radioactivity:

natural – typical for heavy elements whose serial number is greater than 82;
artificial – initiated specifically with the help of nuclear reactions;
induced - characteristic of objects that themselves become a source of radiation if they are heavily irradiated.

Elements that are radioactive are called radionuclides. Each of them is characterized by:

half-life;
type of radiation emitted;
radiation energy;
and other properties.

Sources of radiation

The human body is regularly exposed to radioactive radiation. Approximately 80% of the amount received each year comes from cosmic rays. Air, water and soil contain 60 radioactive elements that are sources of natural radiation. The main natural source of radiation is considered to be the inert gas radon, released from the earth and rocks. Radionuclides also enter the human body through food. Some of the ionizing radiation to which people are exposed comes from man-made sources, ranging from nuclear power generators and nuclear reactors to radiation used for medical treatment and diagnostics. Today, common artificial sources of radiation are:

medical equipment (the main anthropogenic source of radiation);
radiochemical industry (extraction, enrichment of nuclear fuel, processing of nuclear waste and its recovery);
radionuclides used in agriculture and light industry;
accidents at radiochemical plants, nuclear explosions, radiation releases
Construction Materials.

Based on the method of penetration into the body, radiation exposure is divided into two types: internal and external. The latter is typical for radionuclides dispersed in the air (aerosol, dust). They get on your skin or clothing. In this case, radiation sources can be removed by washing them away. External radiation causes burns to the mucous membranes and skin. In the internal type, the radionuclide enters the bloodstream, for example by injection into a vein or through a wound, and is removed by excretion or therapy. Such radiation provokes malignant tumors.

The radioactive background significantly depends on the geographical location - in some regions the level of radiation can exceed the average by hundreds of times.

The effect of radiation on human health

Radioactive radiation, due to its ionizing effect, leads to the formation of free radicals in the human body - chemically active aggressive molecules that cause cell damage and death.

Cells of the gastrointestinal tract, reproductive and hematopoietic systems are especially sensitive to them. Radioactive radiation disrupts their work and causes nausea, vomiting, bowel dysfunction, and fever. By affecting the tissues of the eye, it can lead to radiation cataracts. The consequences of ionizing radiation also include damage such as vascular sclerosis, deterioration of immunity, and damage to the genetic apparatus.

The system of transmission of hereditary data has a fine organization. Free radicals and their derivatives can disrupt the structure of DNA, the carrier of genetic information. This leads to mutations that affect the health of subsequent generations.

The nature of the effects of radioactive radiation on the body is determined by a number of factors:

type of radiation;
radiation intensity;
individual characteristics of the body.

The effects of radioactive radiation may not appear immediately. Sometimes its consequences become noticeable after a significant period of time. Moreover, a large single dose of radiation is more dangerous than long-term exposure to small doses.

The amount of radiation absorbed is characterized by a value called Sievert (Sv).

Normal background radiation does not exceed 0.2 mSv/h, which corresponds to 20 microroentgens per hour. When X-raying a tooth, a person receives 0.1 mSv.

The lethal single dose is 6-7 Sv.

Application of ionizing radiation

Radioactive radiation is widely used in technology, medicine, science, military and nuclear industries and other areas of human activity. The phenomenon underlies devices such as smoke detectors, power generators, icing alarms, and air ionizers.

In medicine, radioactive radiation is used in radiation therapy to treat cancer. Ionizing radiation has made it possible to create radiopharmaceuticals. With their help, diagnostic examinations are carried out. Instruments for analyzing the composition of compounds and sterilization are built on the basis of ionizing radiation.

The discovery of radioactive radiation was, without exaggeration, revolutionary - the use of this phenomenon brought humanity to a new level of development. However, this also caused a threat to the environment and human health. In this regard, maintaining radiation safety is an important task of our time.

Gamma rays are characterized by the least ionizing and greatest penetrating ability. This is a high frequency electro-

Gamma rays are characterized by the lowest ionizing and highest penetrating ability. Gamma rays have significantly greater penetrating power than beta and alpha rays. The passage of gamma rays through matter cannot at all be characterized by their path length. The attenuation of the flux of gamma rays when passing through substances obeys an exponential law and is characterized by the attenuation coefficient μ>

Radioactive contamination occurs as a result of the fallout of radioactive substances (RS) from the cloud of a nuclear explosion. The main sources of radioactivity during nuclear explosions: fission products of substances that make up nuclear fuel (200 radioactive isotopes of 36 chemical elements); induced activity resulting from the impact of the neutron flux of a nuclear explosion on some chemical elements that make up the soil (sodium, silicon, etc.); some part of the nuclear fuel that does not participate in the fission reaction and enters the explosion products in the form of small particles. Radiation from radioactive substances consists of three types of rays: alpha, beta and gamma. Gamma rays have the greatest penetrating power (in the air they travel a distance of several hundred meters), beta particles have less penetrating power (several meters) and alpha particles have insignificant penetrating power (several centimeters). Therefore, the main danger to people in case of radioactive contamination of the area is gamma and beta radiation.

In addition, the effect of heat flow on the body depends on the spectral characteristics of the radiation. Infrared rays with a length of

A-, p-particles and -y-rays have ionizing ability. a particle has a lower speed compared to )