Radiation: Natural background, safe dose, types of radiation, units of measurement. Everything you need to know about radiation Radiation sources and units

The action of ionizing radiation is a complex process. The effect of irradiation depends on the magnitude of the absorbed dose, its power, the type of radiation, and the volume of irradiation of tissues and organs. For its quantitative assessment, special units have been introduced, which are divided into non-systemic and units in the SI system. Currently, SI units are predominantly used. Table 10 below lists the units of measurement of radiological quantities and compares the units of the SI system and non-SI units.

Table 10

To describe the effect of ionizing radiation on a substance, the following concepts and units of measurement are used:
Radionuclide activity in the source (A). The activity is equal to the ratio of the number of spontaneous nuclear transformations in this source over a small time interval (dN) to the value of this interval (dt):

The SI unit of activity is the Becquerel (Bq).
The off-system unit is the Curie (Ci).

The number of radioactive nuclei N(t) of a given isotope decreases with time according to the law:

N(t) = N 0 exp(-tln2/T 1/2) = N 0 exp(-0.693t /T 1/2)

where N 0 is the number of radioactive nuclei at time t \u003d 0, T 1/2 is the half-life - the time during which half of the radioactive nuclei decay.
The mass m of a radionuclide with activity A can be calculated using the formula:

m = 2.4 10 -24 × M×T 1/2×A,

where M is the mass number of the radionuclide, A is the activity in Becquerels, T 1/2 is the half-life in seconds. The weight is given in grams.
Exposure dose (X). As a quantitative measure of X-ray and -radiation, it is customary to use in non-systemic units the exposure dose determined by the charge of secondary particles (dQ) formed in the mass of a substance (dm) with full deceleration of all charged particles:

The unit of exposure dose is Roentgen (R). X-ray is the exposure dose of X-ray and
- radiation, which creates in 1 cc of air at a temperature of 0 ° C and a pressure of 760 mm Hg. the total charge of ions of the same sign in one electrostatic unit of the amount of electricity. Exposure dose 1 R
corresponds to 2.08 10 9 pairs of ions (2.08 10 9 = 1/(4.8 10 -10)). If we take the average energy of formation of 1 pair of ions in air equal to 33.85 eV, then at an exposure dose of 1 R, an energy equal to:
(2.08 10 9) 33.85 (1.6 10 -12) = 0.113 erg,
and one gram of air:
0.113/air = 0.113/0.001293 = 87.3 erg.
The absorption of ionizing radiation energy is the primary process that gives rise to a sequence of physicochemical transformations in the irradiated tissue, leading to the observed radiation effect. Therefore, it is natural to compare the observed effect with the amount of absorbed energy or absorbed dose.
Absorbed dose (D)- the main dosimetric value. It is equal to the ratio of the average energy dE, transferred by ionizing radiation to a substance in an elementary volume, to the mass dm of the substance in this volume:

The unit of absorbed dose is Gray (Gy). The non-systemic unit Rad was defined as the absorbed dose of any ionizing radiation, equal to 100 erg per 1 gram of irradiated substance.
Equivalent dose (N). To assess the possible damage to human health under conditions of chronic exposure in the field of radiation safety, the concept of an equivalent dose H is introduced, which is equal to the product of the absorbed dose D r , created by exposure - r and averaged over the analyzed organ or throughout the body, by the weight factor w r (also called the coefficient radiation quality)
(table 11).

The unit of equivalent dose is Joule per kilogram. It has a special name Sievert (Sv).

Table 11

The effect of irradiation is uneven. To assess the damage to human health due to the different nature of the effect of irradiation on different organs (under conditions of uniform irradiation of the whole body), the concept of an effective equivalent dose E eff is introduced, which is used in assessing possible stochastic effects - malignant neoplasms.
Effective dose equal to the sum of weighted equivalent doses in all organs and tissues:

where w t is the tissue weight factor (Table 12) and H t is the equivalent absorbed dose in
fabrics - t. The unit of effective equivalent dose is Sievert.

Table 12

Collective effective equivalent dose. To assess the damage to the health of personnel and the public from stochastic effects caused by the action of ionizing radiation, the collective effective equivalent dose S is used, defined as:

where N(E) is the number of persons who received an individual effective equivalent dose E. The unit of S is the man-Sievert
(man-Sv).
Radionuclides- radioactive atoms with a given mass number and atomic number, and for isomeric atoms - with a given specific energy state of the atomic nucleus. Radionuclides
(and non-radioactive nuclides) of an element are otherwise called its isotopes.
In addition to the above values, to compare the degree of radiation damage to a substance when it is exposed to various ionizing particles with different energies, the value of linear energy transfer (LET) is also used, which is determined by the relation:

where is the average energy locally transferred to the medium by the ionizing particle due to collisions on the elementary path dl.
Threshold energy usually refers to the energy of an electron. If in the act of collision the primary charged particle forms an -electron with an energy greater than , then this energy is not included in the value of dE, and -electrons with energy are more considered as independent primary particles.
The choice of threshold energy is arbitrary and depends on specific conditions.
It follows from the definition that linear energy transfer is some analogue of the stopping power of matter. However, there is a difference between these values. It consists in the following:
1. LET does not include the energy converted into photons, i.e. radiation losses.
2. At a given threshold, the LET does not include the kinetic energy of particles exceeding .
The values ​​of LET and stopping power are the same if the bremsstrahlung losses can be neglected and

Table 13

By the magnitude of the linear energy transfer, you can determine the weight factor of this type of radiation (Table 14)

Table 14

Maximum allowable radiation doses

In relation to exposure, the population is divided into 3 categories.
Category A exposed persons or personnel (professional workers) - persons who permanently or temporarily work directly with sources of ionizing radiation.
Category B exposed persons or a limited part of the population - persons who do not work directly with sources of ionizing radiation, but due to the conditions of residence or placement of jobs may be exposed to ionizing radiation.
Category B exposed persons or population - the population of a country, republic, territory or region.
For category A, maximum allowable doses are introduced - the highest values ​​of an individual equivalent dose for a calendar year, at which uniform exposure for 50 years cannot cause adverse changes in the state of health detected by modern methods. For category B, a dose limit is determined.
There are three groups of critical organs:
Group 1 - the whole body, gonads and red bone marrow.
Group 2 - muscles, thyroid gland, adipose tissue, liver, kidneys, spleen, gastrointestinal tract, lungs, eye lenses and other organs, with the exception of those that belong to groups 1 and 3.
Group 3 - skin, bone tissue, hands, forearms, shins and feet.
Dose exposure limits for different categories of persons are given in Table 15.

Table 15

In addition to the main dose limits, derivative standards and reference levels are used to assess the effect of radiation. The standards are calculated taking into account the non-exceeding of the dose limits of the SDA (maximum permissible dose) and PD (dose limit). The calculation of the allowable content of a radionuclide in the body is carried out taking into account its radiotoxicity and non-exceeding of the SDA in the critical organ. The reference levels should provide exposure levels as low as can be achieved while respecting the basic dose limits.
For category A (personnel) are established:
- the maximum allowable annual intake of the radionuclide MAP through the respiratory system;
- allowable radionuclide content in the critical organ DS A;
- permissible radiation dose rate DMD A;
- allowable particle flux density DPP A;
- allowable volumetric activity (concentration) of the radionuclide in the air of the working area of ​​DC A;
- permissible contamination of the skin, overalls and working surfaces DZ A.
For category B (a limited part of the population), the following are established:
- the limit of the annual intake of the GWP of the radionuclide through the respiratory or digestive organs;
- permissible volumetric activity (concentration) of radionuclide DK B in atmospheric air and water;
- admissible dose rate DMD B;
- allowable particle flux density DPP B;
- permissible contamination of skin, clothing and surfaces with DZ B.
Numerical values ​​of admissible levels are contained in full in
"Norms of Radiation Safety".

One word radiation terrifies someone! We note right away that it is everywhere, there is even the concept of a natural background radiation and this is part of our life! Radiation arose long before our appearance, and to a certain level of it, a person adapted.

How is radiation measured?

Radionuclide activity measured in Curies (Ci, Si) and Becquerels (Bq, Bq). The amount of a radioactive substance is usually determined not by mass units (grams, kilograms, etc.), but by the activity of this substance.

1 Bq = 1 disintegration per second
1Ci \u003d 3.7 x 10 10 Bq

Absorbed dose(the amount of energy of ionizing radiation absorbed by a unit mass of any physical object, for example, body tissues). Gray (Gr / Gy) and Rad (rad / rad).

1 Gy = 1 J/kg
1 rad = 0.01Gy

Dose rate(dose received per unit of time). Gray per hour (Gy/h); Sievert per hour (Sv/h); Roentgen per hour (R/h).

1 Gy/h = 1 Sv/h = 100 R/h (beta and gamma)
1 µSv/h = 1 µGy/h = 100 µR/h
1 µR/h = 1/1000000 R/h

Dose equivalent(A unit of absorbed dose multiplied by a coefficient that takes into account the unequal danger of different types of ionizing radiation.) Sievert (Sv, Sv) and Rem (ber, rem) - "the biological equivalent of X-rays."

1 Sv = 1Gy = 1J/kg (beta and gamma)
1 µSv = 1/1000000 Sv
1 ber = 0.01 Sv = 10mSv

Unit conversion:

1 Zivet (Sv, sv)= 1000 millisieverts (mSv, mSv) = 1,000,000 microsieverts (uSv, µSv) = 100 rem = 100,000 millirems.

Safe background radiation?

The safest radiation for humans is considered a level not exceeding 0.2 microsievert per hour (or 20 microroentgen per hour), this is the case when "radiation background is normal". Less safe level, not exceeding 0.5 µSv/h.

Not a small role for human health is played not only by force, but also by the time of exposure. Thus, radiation of lower strength, which exerts its influence for a longer time, can be more dangerous than strong, but short-term radiation.

accumulation of radiation.

There is also such a thing as accumulated dose of radiation. Over the course of a lifetime, a person can accumulate 100 - 700 mSv, this is considered normal. (in areas with a high radioactive background: for example, in mountainous areas, the level of accumulated radiation will be kept in the upper limits). If a person accumulates about 3-4 mSv/year this dose is considered average and safe for humans.

It should also be noted that in addition to the natural background, other phenomena can also influence a person's life. So, for example, "forced exposure": X-ray of the lungs, fluorography - gives up to 3 mSv. A snapshot at the dentist - 0.2 mSv. Airport scanners 0.001 mSv per scan. Airplane flight - 0.005-0.020 millisieverts per hour, the dose received depends on the flight time, altitude, and the passenger's seat, so the radiation dose at the window is the largest. Also, a dose of radiation can be obtained at home from seemingly safe ones. It also contributes to the irradiation of people, accumulating in poorly ventilated rooms.

Types of radioactive radiation and their brief description:

Alpha -has a small penetrating ability (you can literally defend yourself with a piece of paper), but the consequences for irradiated, living tissues are the most terrible and destructive. It has a low speed compared to other ionizing radiations, equal to20,000 km/s,as well as the smallest impact distance. The greatest danger is direct contact and ingestion of the human body.

Neutron - consists of neutron fluxes. Main sources; atomic explosions, nuclear reactors. Deals serious damage. From high penetrating power, neutron radiation, it may be protected by materials with a high hydrogen content (having hydrogen atoms in their chemical formula). Usually water, paraffin, polyethylene are used. Speed ​​\u003d 40,000 km / s.

Beta - appears in the process of decay of the nuclei of atoms of radioactive elements. It passes through clothing and partially living tissues without problems. Passing through denser substances (such as metal) enters into active interaction with them, as a result, the main part of the energy is lost, being transferred to the elements of the substance. So a metal sheet of just a few millimeters can completely stop beta radiation. can reach 300,000 km/s.

Gamma - emitted during transitions between excited states of atomic nuclei. It pierces clothes, living tissues, it is a little more difficult to pass through dense substances. The protection will be a significant thickness of steel or concrete. At the same time, the effect of gamma is much weaker (about 100 times) than beta and tens of thousands of times alpha radiation. Travels long distances at speed 300,000 km/s.

X-ray - similar to gamma, but it has less penetration due to the longer wavelength.

© SURVIVE.RU

Post Views: 19 918

The radioactivity of a substance is characterized by the number of decays per unit time. The greater the number of decays per unit time, the higher the activity of the substance. The rate of radioactive decay is determined by the value of the half-life (T), i.e., the period of time during which the activity of a radioactive element is reduced by half. For each isotope, the rate of radioactive decay, as will be shown below, is a very important indicator for the hygienic assessment of working conditions and the choice of special protective measures.

To measure radioactivity, a unit is adopted - decay per second, as well as an off-system unit - curie (k), i.e., the activity of such an amount of radioactive substance in which 3.7 10 10 decays occur in 1 second. In practice, units derived from the curie are used: millicurie (mk), microcurie (mkk). The concentration of radioactive substances in air and water is measured in curie per 1 l - k / l.

Gamma activity is expressed in milligram equivalents of radium. It is the gamma equivalent of a radioactive preparation, whose γ-radiation under identical conditions creates the same dose rate as γ-radiation of 1 mg of radium of the State Standard of Radium of the USSR with a platinum filter 0.5 mm thick. A point source of 1 mg of radium in equilibrium with decay products after filtration through a platinum filter 0.5 mm thick of platinum produces a dose rate of 8.4 r per hour at a distance of 1 cm in air.

Roentgen (p) is taken as the unit dose of X-rays and γ-rays. One roentgen is a dose that in 1 cm 2 of air at 0 ° and a pressure of 760 mm Hg. Art. forms ions with a total charge of one electrostatic unit of the amount of electricity of each sign. In practice, x-ray derivatives are used: 1 p \u003d 10 3 mr (milliroentgen) \u003d 10 6 mcr (micro-roentgen). To characterize the distribution of dose over time, the concept of dose rate is introduced: r/h, r/min, r/s, mr/h, mr/min, mr/s, etc.

Previously, the unit of absorbed dose and radiation dose (for all types of radiation) used the physical equivalent of the roentgen (fair). Pair - the dose of any ionizing radiation at which the energy absorbed in 1 g of a substance is equal to the energy loss for ionization created in it by a dose of 1 r of x-rays or y-rays; 1 fair for air is equal to 84 erg/g, for biological tissues - 93 erg/g.

With the same absorbed dose, the biological effect of different types of radiation is not the same; it can be expressed by the following quantities (relative biological effectiveness - obe):

Thus, the biological effect of exposure to a-radiation is 10 times greater, thermal neutrons - 3 times, fast neutrons and protons - 10 times greater than the effect of exposure to y- and X-rays.

Various biological effects mainly depend on the density of ionization created in the tissues by one or another ionizing radiation. At the suggestion of the International Congress of Radiologists in 1953, the unit rad was adopted as the unit of absorbed dose of ionizing radiation energy per unit mass of the irradiated substance. For all types of ionizing radiation, rad corresponds to an absorbed energy of 100 ergs per 1 g of any substance. To take into account the biological effect of various types of radiation, another unit was introduced - the biological equivalent of a rad - rem. For 1 rem, such an absorbed dose of any type of ionizing radiation is taken, which causes the same biological effect as 1 rad of x-rays or y-rays.

The term "relative biological efficiency" is usually used in the comparative assessment of the effects of radiation in radiobiology. Since the value of OBE depends on a number of reasons - radiation energy, criteria for biological action, etc., when solving problems of radiation safety, the so-called quality factors - QC are used, which are quantities that show the dependence of the biological effect of chronic irradiation of the body on the transfer of energy per unit the path length of a particle or quantum. To determine the absorbed dose in rem (Drem), it is necessary to multiply the dose in rad (Drad) by the quality factor and the distribution factor (CR), which takes into account the effect of the inhomogeneous distribution of radioactive isotopes.

Dber \u003d Drad · KK · KR.

Contamination of working surfaces and equipment, hands, overalls and other items with α- and β-emitters is expressed in the number of particles emitted from an area of ​​1 cm 2 per 1 minute.

Radioactivity: becquerel, curie ratio, microsievert - dangerous / safe

The unit of radioactivity (radiation) Becquerel (symbol Bq, Bq, becquerel) is the number of nuclear decays in a sample per second. Not in kilogram, meter and liter, but in an arbitrary sample.

The radioactivity of water, products, soil is measured in becquerels per 1 liter, kilogram, cubic meter.

For food, radioactivity should be measured in Bq/kg.

How many becquerels are in one curie, or what is one curie equal to?

The old unit of measure is Curie (Ci, Curie, Ci).
1 Ci = 37 GBq (gigabecquerel)

Physically, one Curie is the same radioactivity as one gram of the radium-226 isotope. The radionuclide 226Ra is the most stable isotope of radium, with a half-life of about 1600 years.

Radium-226 arises from the decay of uranium-238, uranium-235, thorium-232. Of course, all this radioactive set is available in the amount of about a hundred tons in each nuclear reactor of a nuclear power plant.

From radioactive radium-226, radioactive radon-222 is formed through alpha decay, with a half-life of 3.8235 days.

Radon-222 alpha decays (firing off a helium-4 nucleus) to form the nuclide polonium-218 with a half-life of 3.10 minutes, and so on.

How many becquerels are dangerous to health?

For a thermal power of a nuclear reactor of 1 megawatt, the required radioactivity is approximately 3 × 10**16 becquerels (3 times 10 to the 16th power).

Since only one particle or quantum does not always occur in one nuclear decay, in my engineering and metrological opinion, practical “measurements” of radioactivity in becquerels in terms of cesium or iodine radionuclides do not make much sense - it just turns out to be some indicative value.

A chemical-radiological study of samples, which results in the concentration of the isotopic composition of milk, is an accurate measurement, and becquerels, and even converted to cesium ... It's like paying for milk at the supermarket checkout at a price in dollars for a dairy cow.

The second side of the question: "what is dangerous to health." Considering that, according to official UN/WHO data, on the eve of the quarter-century anniversary, as a result of the Chernobyl nuclear disaster, 57 people were officially nuclearly affected (i.e. died from radiation sickness), the conclusion suggests itself that “safe for health” means that you won’t die immediately from the received dose of radiation, you will die later. And a statistician will not write that he died from radiation.

Therefore, nuclear propagandists came up with the “radioactive banana equivalent” – the amount of radiation introduced into the body when eating one banana. The fact is that radionuclides are found everywhere, including in normal natural food (if anyone can find one). For example, food contains the “natural” radioisotope potassium-40. In a gram of natural potassium (in a natural mixture of potassium isotopes) there are 32 decays of potassium-40 per second, which is 32 becquerels, or 865 picocuries.

The natural radioactivity of bananas is 130 Bq/kg, eating 1 kilogram of bananas a person receives a radiation dose of 0.66 microsieverts. This, of course, is very conditional. Bananas are considered to be one of the most naturally radioactive foods. However, people have been eating them for tens of thousands of years, humanity has not developed a taboo on eating them.

All natural products contain some amount of radionuclides. With food, a person receives an oral dose of radiation of 0.35 millisieverts per 1 year.

What do the units of measurement of radiation mean - Sievert, rem, roentgen

What do the units of measurement Sievert (Sievert, Sv, Sv), rem, rem, roentgen (roentgen) mean? Radioactivity is the transformation of some atoms into others, with the emission of radiation.

Since 1979, "biological" radiation has been measured in Sieverts.
About the conversion of Roentgen to Sievert, how many Roentgen per hour to Microsievert per hour - in the article Dangerous level of radiation and safe radioactivity: Sievert / Roentgen ratio

In fact, Sieverts are Grays (absorbed physical radiation), recalculated with “quality factors” (average coefficient of relative biological effectiveness, RBE), depending on the composition of ionizing radiation, that is, radiation.

One Gray (Gray, Gy, Gy) is a unit of measure for the absorbed dose of ionizing radiation.
The absorbed dose of radiation by one kilogram of mass is equal to one gray when this one kilogram of matter received one joule of energy.
Gy = J / kg.

The conversion of physical Grays into biological Sieverts is done with the RBE coefficients:
γ-radiation (X-rays), β-radiation (electron flux), muons: 1
α-radiation (helium nuclei): 10-20
Neutrons (thermal, slow, resonant), with energies up to 10 keV: 3-5
Neutrons with energy (velocity) greater than 10 keV: 10-20
Protons (hydrogen nuclei-1): 5-10
Heavy cores: 20
(1)

It is clear that the average coefficient of relative biological effectiveness does not reflect the “medical effect” on the body. It is one thing to irradiate the head with the brain, and another thing is the toe of the left foot.

Think of a bubble chamber - the passage of particles (not absorption!) leaves a trail in the chamber. Consequently, in a biological object - destruction along the way. A neutron passed right through the human brain - destroyed the brain a little. Similarly with the ovaries, eggs, etc.

Fatal destruction or not? This is where it will go and how the cell will react.

If radioactive elements settled in the body, and not just in the body - but in a certain organ, then decaying (and generating new radioactive elements) inside the organ, the destruction is much more targeted.

Inside the irradiated person (even from the outside, even from the inside), nuclear reactions begin. In a sense, nuclear chain reactions begin inside a person. This is what is called radiation contamination or induced radiation.
(See also On the radioactivity of food, water, and becquerels.)

From here a simple conclusion: the danger of radiation for a person in Sieverts is the probability and accuracy is very approximate. Especially when ratios are used...

How much? Yes, someone knows him ... A living example, an illustration - the situation with strontium in Europe. In the same place - how far the radioactive cloud flies from the accident at the nuclear power plant.

What is rem, one Sievert is how much rem

REM stands for Roentgen Equivalent Man.

This unit of measurement was used in antiquity, when dosimeters were mass-produced.

The radiation dose of one rem of gamma radiation is exactly equal to one roentgen. In principle, it is similar to the ratio of modern units of measurement of the “biological” radiation dose Sievert and the “physical” radiation dose Gray.

Correspondence table, ratios of microroentgen per hour (mcr/h) and microsievert per hour (mcSv/h)

Approximate ratio of microsievert and microroentgen, but there is no exact ratio

If the radiation is only gamma radiation, i.e. x-rays, then
1 Sv == 1 Gy ≈ 115 R (usually cured at this radiation dose)
1 µSv == 1 µGy ≈ 115 µR (70 mSv is considered a lifetime dose to civilians)
1 micro-Sievert/hour == 1 micro-Gray/hour ≈ 115 micro-roentgen/hour

However, this is a very approximate ratio of sieverts and roentgens. The fact is that in roentgens (officially, so to speak), it was the radiation doses of X-rays (gamma radiation) that were previously measured, and real radiation also consists of alpha, beta and neutron radiation. And their impact on the body is different, with increasing coefficients.

In sieverts, the dose of radiation began to be calculated somewhere from the 90s of the last century.
It is clear that interest in radiation is by no means academic, but in connection with man-made disasters and uncertainty about the veracity of state and corporate information.

About Fukushima nuclear reactors

Emergency nuclear reactors in Japan, according to media rumors:
FUKUSHIMA-DAIICHI-1 439 MW
FUKUSHIMA-DAIICHI-2 760 MW
FUKUSHIMA-DAIICHI-3 760 MW
FUKUSHIMA-DAINI-1 1067 MW
FUKUSHIMA-DAINI-2 1067 MW
FUKUSHIMA-DAINI-4 1067 MW

Total emergency (?) 5160 megawatts. How much potential energy of nuclear fuel and radiation is in emergency reactors so far (?) is unknown. Notorious for the nuclear disaster at the Chernobyl nuclear power plant, the RBMK-1000 nuclear reactor had a capacity of 1000 megawatts. In other words, all of Japan's neighbors - Korea, China, Russia - have five potential Chernobyls in the form of Fukushima?

I will say this: if radiation smells like ozone, nails and hair glow in the dark, then as a combat/working unit, a person will function for several more hours or days, depending on the I-IV degree of acute radiation sickness (ARS). It is with such criteria that radiology operates, and not at all:
healthy lifestyle, do not get sick
successful development and education of the child
the opportunity to produce healthy, cheerful offspring and have grandchildren-great-grandchildren
and in general to be beautiful, successful, live happily ever after ...

What radiation is acceptable and what is not is a philosophical question. For someone to start the disease from a latent state, it is enough to go out naked for 5 minutes, and after a bath, someone can wallow in the snow for 10 minutes with pleasure.

It's one thing to eat a gram of uranium-235, it's another thing to inject a gram of a solution of cesium-137 salt into the blood, the third thing is to pass 10 tons of pure uranium-238 in a sealed container, even from window glass.

I live with radiation of 5-15 microrents per hour for almost half a century, and nothing. I saw that they also live near radon sources, with a radiation of 35 mcr / h. Didn't notice much happier. But I also did not meet the living-rotting luminous local residents near radon either. Rumors “about increased oncology” - met.

But if I bring the radiometer (to which the erroneous name “dosimeter” was glued) to a sample with cesium-137 (appetizing butter mushroom), and the radiation meter shows 35 μR / h, and then I take the radiometer away 5 meters, and there the reading will be 10 mc/h, then... I'll throw this sample away, despite the fact that the radiation level is 35 mc/h (0.35 µSievert per hour - quite acceptable as background radioactivity)

Because a gram of this sample is most likely fonite 1000 times more than the area surrounding me - the solid angles of the sample's radiation and the dimensions of the device's sensor, consider the distance yourself. 🙂

If I ate this fungus, then my body would absorb some of the compounds of radioactive cesium and would irradiate my delicate body from the inside for decades. It would seem a microdose, but the radiation is constantly and point-blank on my cells. And it is still unknown for what. Although what is unknown here is quite known.

Therefore, radiation figures are very conditional figures from the point of view of health. If the radioactivity of the water is higher than the natural background, do not drink it. Suddenly, in the water, instead of indigestible radon, there will be a salt of a radionuclide with a long half-life, and the body will assimilate “this radiation” and place it somewhere in fat reserves. And then this radionuclide will irradiate the entire shortened life, so to speak - "your own radiation - always with you."

Since heavy radionuclides are released during reactor accidents, heavy radionuclides are carried in the air for decades, in very low concentrations, but they can fall out in a very concentrated way, and even more concentratedly get into the human body with food. Textbook examples: lard, mushrooms, milk.

So if, after a nuclear disaster, the radiation background increased a couple of times in the city or village N, located 3 thousand kilometers from the disaster site, and then almost returned to normal ... Personally, I would slowly move to another place. But how do you know if the radioactive cloud has passed there too? The ball is round ... But I love wild mushrooms.

Vadim Shulman, metrology engineer
(the article uses my own knowledge and experience, as well as figures from Wikipedia - with all the ensuing consequences)

In contact with

More than 50 units of measurement are used to quantify radiation. If you study some of them, you can better understand what radiation is and what effect it has on our body. Even if you are convinced that you will never understand these roentgens, rems and rads, still spend some time trying to understand their meaning.

X-ray (r). This unit is named after V. Roentgen, who discovered a new type of rays. It was originally used to express the exposure dose of x-ray or gamma radiation from x-ray machines. However, this unit is rarely used, as it determines the number of charged ions in the air. To measure the radiation energy, in most cases, units rem and rad are used.

Baer. Baer is an abbreviation for the term "X-ray biological equivalent". This unit is used to measure the degree of biological damage caused by ionizing radiation. Rem takes into account the relative biological efficiency of energy absorbed by living tissue. One rem is approximately equal to one roentgen (1 p = 0.88 rem) and produces the same biological effect.

Glad. Glad- short for the English term "radiation absorbed dose" (dose of absorbed radiation). This unit is used to measure the radiation energy absorbed by the body. There are many units of measurement for energy, including the calorie, erg, joule, and watt-second. Historically, the erg was first used to measure the energy of radioactive radiation. A rad is equal to 100 ergs absorbed by one gram of tissue. For beta, gamma, and X-rays, one rad is approximately equal to one rem. For alpha radiation, a rad is equivalent to 10-20 rems.

RBE (Relative biological effectiveness).

OBE, or relative biological effectiveness, characterizes the various degrees of exposure to ionizing radiation on our body. Alpha radiation, for example, has RBE is 10-20 times higher than beta radiation. This factor depends on many factors, such as whether the exposure is external or internal.

LD (Lethal Dose)

LD, or lethal dose, is the dose that determines the percentage of mortality after radiation exposure. For example, LD50 is the dose after which 50% of those exposed die. LD30\50 means that as a result of exposure, 50% will die within 30 days. For humans, this dose is in the range of 400-500 rem. This lethal dose calculation is based on the assumption that the population consists of healthy adult males. In fact, it is necessary to take into account the age composition of the population and existing differences in health status. Therefore, the actual lethal dose for a certain group of the population may be much lower.

To measure small doses, derivative units are used with the appropriate prefixes milli- or micro-. Milli means one thousandth and micro means one millionth of the unit used. For example, a millirem (mrem) is a thousandth of a rem, and a microrem (mkrem) is a millionth of a rem. Radiation dose is measured in roentgens, rads and rems. If we are interested in radiation power, we take the radiation dose per unit of time (second, minute, hour, day, year).

Curie (Ki). Curie- a unit of direct measurement of radioactivity, that is, the activity of a given amount of a certain substance. The unit is named after Marie and Pierre Curie, who discovered radium. Source activity is measured by counting the number of radioactive decays per unit time. One curie is equal to 37 billion decays per second. By measuring the activity of different substances, we can determine which one is more radioactive. One gram of radium-226 has an activity equal to one curie, and a gram of promethium-145 has an activity equal to 940 curies, that is, promethium-145 is almost 1000 times more active than radium.

In addition to the prefixes milli- and micro-, the prefixes nano- (one billionth) and pico- (one trillionth) are used. One picocurie corresponds to two disintegrations per minute. All these prefixes are taken from the metric system of measures. From it, you can also take the prefixes kilo- (one thousand) and mega- (one million), if you need to measure huge doses of radiation.
The international scientific community has proposed the use of more convenient units of measurement - gray and becquerel.

Gray (Gr) equals 100 rads. Perhaps in the future gray will be used instead of rad.

Becquerel (Bq)- a unit named after the French physicist Becquerel, who discovered radioactivity. A becquerel corresponds to one radioactive decay per second and is many times smaller than a curie. This unit was used in Europe for about ten years.

Sievert (Sv) is the unit of the new international standard. One sievert is equal to 100 rems. However, rem, rad, and curie will be used more frequently in this book.
The National Committees for Radiation Protection (NCRP) of most European countries, as well as Belarus and Russia, have set a permissible exposure rate for the population of no more than 1 millisievert per year. At the same time, the influence of the natural background and X-ray examinations was not taken into account. However, there is a lot of evidence that there is no safe level of radiation exposure at all (the so-called "no-threshold concept").