Measurements of the radiation gamma background on the territory of the school.

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Map of the results of measurements of the radiation gamma background on the territory

SOSH No. ......................................... Mr. Novozybkov

1 Characteristics of the territory

1.1. Address, location of the school:

………………………………………………………………………………………………………..

Name of the district, rural settlement, settlement, street, number.

1.2. School affiliation: ……………………………………………………………………….

City or district department of education

1.3. Date of construction………………………….....................................................................................................

(year, construction and material from which the school is built number of storeys).

1.4. The measurements were carried out with a DKG-03D Grach device, the passport measurement error was 20%.

1.5. Gamma background measurement conditions: ………………………………………………………………..

Date, time of measurement, weather conditions.

2. Results of measurement of gamma background.

points	Place of measurement gamma background	Value, µSv/h	Note description of gamma background measurement location

(When an increased gamma background is detected, a description of the site is carried out and its position is noted on the territory map).

1. Instrument readings:

The average value of the gamma background in the house is …….. µSv/h, the range is from …… to …… µSv/h.

On the territory of the yard – …….. µSv/h.

The highest value of gamma background power is……………. µSv/h

………………………………………………………………………………………………

Responsible for conducting the survey:

_____________________________________________________________________

(full name and position)

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Memo on the measurement of radiation gamma background

General Information :

Two important concepts need to be understood correctly:

1. radiation background of the territory – it is a historically formed set of all types of ionizing radiation in a particular territory, formed from natural and artificial sources;

2. radiation gamma background – the level of human exposure to only gamma radiation from natural and artificial sources in a particular area.

Thus, from the above concepts it follows that the "radiation background of the territory" is understood as all types of ionizing radiation (radiation) that affect a person. In the case of applying the concept of "radiation gamma background" – mean only gamma radiation.

Devices, units of measurement of radiation gamma background.

For measuring radiation gamma backgroundin a specific area apply devices - dosimeters.

Modern dosimetric instruments measureambient dose equivalent rate.Units Sievert per hour (abbreviated as Sv/h) or derivatives of microSievert per hour (µSv/h is one million times less than Sievert); milliSievert per hour (mSv/h is 1000 times smaller than the Sievert). The measured quantity, the ambient dose equivalent rate, makes it possible to assess the effect of gamma radiation on the human body without complex mathematical calculations.

In obsolete instruments, the gamma background is measured in units of " X-ray per hour (abbreviated as R/h) or derivatives of micro-Roentgen per hour (µR/h); milliroentgen per hour (µR/h). Measured value - mgamma dose rateradiation is now obsolete, as it describes the effect of gamma radiation in the air, and not on a person.

For gamma radiation, the ratio between the Roentgen and Sievert units is approximately 100:1, i.e. 100 Roentgen = 1 Sievert; 100 mR/h = 1mSv/h; 50 µR/h=0.5 µSv/h orµSv/h

The natural (natural) values ​​of the gamma background in most of our planet are in the range of 0.08 - 0.20 μSv / h or 8 - 20 μR / h. On Earth, there are territories with increased 2 or more times the gamma background.

Why measure gamma background?

A special place is currently occupied by the problem of radiation safety, which determines the prospects for the development of nuclear energy and radiation technologies. The population perceives the problems of radiation hazard and radiation risks ambiguously. These concepts are not comparable. Assessment of risks of various nature, including the risk due to ionizing radiation, is an important aspect of creating optimal living conditions.

For most settlements in Russia, the average value of the natural (natural) gamma background in open areas at a height 1 meter from the earth's surface is 5 - 20 μR / h or 0.05 - 0.2 μSv / h. There are a few more indoors. On Earth, there are territories with an increased gamma background by 2 or more times. This is due to the structure and chemical composition of the Earth's crust.

If the territory of human habitation has been exposed to radioactive contamination as a result of a radiation accident or other man-made incidents, then the value of the gamma background will be higher than the natural level characteristic of this territory. Thus, it is necessary to measure the gamma background in order to identify its increase, develop and implement measures aimed at ensuring the radiation safety of the population. Such events are carried out by specialists of the radiation safety service of the Ministry of Emergency Situations and Civil Defense of the Russian Federation or centers of hygiene and epidemiology.

Sequence of actions when measuring gamma background

1. Before measuring the gamma background, you should carefully read the operating instructions for the dosimeter.

2. Perform an external inspection of the dosimeter. Set the power switch to the "off" position, open the battery cover and install a battery or more. Close the battery cover.

3. Turn on the dosimeter, if necessary, select the operating mode of the device for measuring gamma background. Some dosimeters provide for monitoring the health of the electronic scaling circuit and the dosimeter timer, for which it is necessary to test the device in accordance with the description in the instructions.

4. When working correctly, the dosimeter will start measuring. Measurements can be accompanied by sound signals.

5. After a certain time, the gamma background values ​​will appear on the instrument panel.With a natural, unchanged background of gamma radiation, the readings of the device can range from 0.10 to 0.25 μSv / h (10-25 μR / h) depending on the model of the device, the error and the place of measurement (street or indoors).

6. Measurement of gamma background is carried out at a height 1 meter from the ground or floor

6. In the case of radioactive contamination, the instrument readings will be several times larger.

7. There may be cases when the dosimeter shows unusually high values ​​of the gamma background, exceeding the natural levels by several times. In such cases it is necessary:

Step aside for 10-20 steps and make sure that the reading of the device returns to normal.

Make sure that the dosimeter is working properly (most devices of this kind have a special self-diagnosis mode).

Short circuits, water, battery leaks, strong external electromagnetic fields, shock can partially or completely disrupt the normal operation of the electrical circuit of the dosimeter.

If possible, duplicate measurements using another dosimeter, preferably of a different type.

8. If you are sure that you have found a source or site of radioactive contamination, in no case should you try to get rid of it yourself (throw it away, bury it or hide it).

Remember! In various regions of our country, there are territories that have been exposed to radioactive contamination as a result of a radiation accident or any human actions (removal of industrial waste or radioactive substances to unidentified places).

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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 factor 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.

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Gamma radiation is a rather serious danger to the human body, and to all living things in general.

These are electromagnetic waves with a very small length and high propagation speed.

Why are they so dangerous, and how can you protect yourself from their effects?

About gamma radiation

Everyone knows that the atoms of all substances contain a nucleus and electrons that revolve around it. As a rule, the core is a fairly stable formation that is difficult to damage.

At the same time, there are substances whose nuclei are unstable, and with some influence on them, the radiation of their components occurs. Such a process is called radioactive, it has certain components, named after the first letters of the Greek alphabet:

• gamma radiation.

It should be noted that the radiation process is divided into two types, depending on what exactly is released as a result.

Kinds:

1. A stream of rays with particle release - alpha, beta and neutron;
2. Radiation energy - X-ray and gamma.

Gamma radiation is a flow of energy in the form of photons. The process of separation of atoms under the influence of radiation is accompanied by the formation of new substances. In this case, the atoms of the newly formed product have a rather unstable state. Gradually, when elementary particles interact, the balance is restored. As a result, excess energy is released in the form of gamma.

The penetrating power of such a stream of rays is very high. It is able to penetrate through the skin, tissues, clothing. More difficult will be the penetration through the metal. To delay such rays, a fairly thick wall of steel or concrete is needed. However, the wavelength of γ-radiation is very small and is less than 2·10 −10 m, and its frequency is in the range of 3*1019 - 3*1021 Hz.

Gamma particles are photons with fairly high energy. The researchers claim that the energy of gamma radiation can exceed 10 5 eV. In this case, the boundary between x-rays and γ-rays is far from being sharp.

Sources:

• Various processes in outer space,
• The decay of particles in the process of experiments and research,
• The transition of the nucleus of an element from a state of high energy to a state of rest or with less energy,
• The process of deceleration of charged particles in a medium or their movement in a magnetic field.

Gamma radiation was discovered by the French physicist Paul Villard in 1900, while studying radiation from radium.

Why is gamma radiation dangerous?

Gamma radiation is more dangerous than alpha and beta.

Mechanism of action:

• Gamma rays are able to penetrate through the skin into living cells, resulting in their damage and further destruction.
• Damaged molecules provoke the ionization of new identical particles.
• As a result, there is a change in the structure of matter. In this case, the affected particles begin to decompose and turn into toxic substances.
• As a result, new cells are formed, but they already have a certain defect and therefore cannot fully work.

Gamma radiation is dangerous because such interaction of a person with the rays is not felt by him in any way. The fact is that each organ and system of the human body reacts differently to γ-rays. First of all, cells that can divide rapidly suffer.

Systems:

• lymphatic,
• cardiac,
• digestive,
• hematopoietic,
• Sexual.

There is also a negative effect at the genetic level. In addition, such radiation tends to accumulate in the human body. At the same time, at first, it practically does not appear.

Where is gamma radiation used?

Despite the negative impact, scientists have found positive aspects. Currently, such rays are used in various spheres of life.

Gamma radiation - application:

• In geological studies, they are used to determine the length of wells.
• Sterilization of various medical instruments.
• Used to control the internal state of various things.
• Accurate modeling of the path of spacecraft.
• In crop production, it is used to develop new varieties of plants from those that mutate under the influence of rays.

The radiation of gamma particles has found its application in medicine. It is used in the treatment of cancer patients. This method is called "radiation therapy" and is based on the effect of rays on rapidly dividing cells. As a result, with proper use, it becomes possible to reduce the development of pathological tumor cells. However, this method, as a rule, is used when others are already powerless.

Separately, it is worth mentioning its effect on the human brain.

Modern research has shown that the brain constantly emits electrical impulses. Scientists believe that gamma radiation occurs when a person has to work with different information at the same time. At the same time, a small number of such waves leads to a decrease in memory ability.

How to protect yourself from gamma radiation

What kind of protection exists, and what can be done to protect oneself from these harmful rays?

In the modern world, a person is surrounded by various radiations from all sides. However, gamma particles from space have minimal impact. But what is around is a much greater danger. This is especially true for people working at various nuclear power plants. In this case, protection against gamma radiation consists in the application of some measures.

Measures:

• Do not stay for a long time in places with such radiation. The longer a person is under the influence of these rays, the more damage will occur in the body.
• You should not be where the sources of radiation are located.
• Protective clothing must be used. It consists of rubber, plastic with lead fillers and its compounds.

It should be noted that the attenuation coefficient of gamma radiation depends on what material the protective barrier is made of. For example, lead is considered the best metal due to its ability to absorb radiation in large quantities. However, it melts at fairly low temperatures, so in some conditions a more expensive metal such as tungsten or tantalum is used.

Another way to protect yourself is to measure the power of gamma radiation in watts. In addition, power is also measured in sieverts and roentgens.

The norm of gamma radiation should not exceed 0.5 microsievert per hour. However, it is better if this indicator is not higher than 0.2 microsievert per hour.

To measure gamma radiation, a special device is used - a dosimeter. There are quite a few such devices. Often used is such an apparatus as "gamma radiation dosimeter dkg 07d thrush". It is designed for prompt and high-quality measurement of gamma and X-ray radiation.

Such a device has two independent channels that can measure DER and Dose Equivalent. The DER of gamma radiation is the equivalent dosage power, that is, the amount of energy that a substance absorbs per unit time, taking into account the effect the rays have on the human body. For this indicator, there are also certain norms that must be taken into account.

Radiation can negatively affect the human body, but even it has found application in some areas of life.

Video: Gamma radiation

• - prepare the dosimeter for operation according to the description attached to the device;
• - place the detector at the place of measurement (when measuring on the ground, the detector is placed at a height of 1m);
• - take the readings of the device and record them in the table.

Measurement of the level of radioactive contamination of the body of animals, machinery, clothing and equipment:

• - select a site for measurements at a distance of 15-20 m from livestock buildings;
• - using the DP-5 device, determine the background on the selected site (D f);
• - measure the dose rate of gamma radiation created by radioactive substances on the surface of the animal's body (D meas) by placing the detector of the DP-5 device at a distance of 1-1.5 cm from the surface of the animal's body (the screen is in the "G" position);
• - when establishing radioactive contamination of the skin of animals, examine the entire surface of the body, paying special attention to the places of the most likely contamination (limbs, tail, back);
• - contamination of machinery and equipment is checked first of all in those places with which people come into contact during work. Clothing and protective equipment are examined in expanded form, the places of greatest pollution are found;
• - calculate the radiation dose created by the surface of the measured object according to the formula:

D about \u003d D meas. ? D f / K,

Where, D about - the radiation dose created by the surface of the examined object, mR / h; D mes - radiation dose created by the surface of the object together with the background, mR/h; Df - gamma background, mR/h; K - coefficient taking into account the screening effect of the object (for the surface of the body of animals it is 1.2; for vehicles and agricultural machinery - 1.5; for personal protective equipment, food packaging and pantries - 1.0).

The amount of radioactive contamination obtained in this way is compared with the permissible norm and a conclusion is made about the need for decontamination.

The presence of radioactive substances inside the animal body is determined by two measurements: with the closed and open detector window of the DP-5 radiometer. If the readings of the device with the detector window closed and open are the same, the examined surface is not contaminated with radioactive substances. Gamma radiation passes through the surface under study from the other side (or from the internal tissues of the body). If the readings are higher when the detector window is open than when it is closed, the surface of the body is contaminated with radioactive substances.

The purpose of the input operational radiation control is to prevent the production of raw materials, the use of which can lead to an excess of the permissible levels of cesium-137 and strontium-90 in food products, established by sanitary rules and regulations.

The objects of input control are live cattle and all types of raw meat. The procedure for conducting operational radiation monitoring of meat raw materials and livestock is established taking into account the radiation situation that has developed in the territory of their origin and is carried out in the form of continuous and selective monitoring.

Continuous operational radiological control is carried out in the study of meat raw materials and livestock produced in territories that have undergone radioactive contamination or are suspected of radioactive contamination. Selective control is carried out in the study of meat raw materials and livestock produced in territories that have not been exposed to radioactive contamination and are not suspected of radioactive contamination in order to confirm the radiation safety and homogeneity of batches of meat raw materials and livestock (in this case, the sample is up to 30% of the volume of the controlled batch).

When meat raw materials or livestock with radionuclide content above control levels (CL) are detected, they proceed to continuous operational or complete laboratory radiological control.

Radiation monitoring of meat raw materials and livestock is carried out by evaluating the compliance of the results of measuring the specific activity of cesium-137 in the controlled object with the "Control levels", not exceeding which allows guaranteeing the compliance of the controlled products with the requirements of radiation safety without measuring strontium-90:

(Q/H) Cs-137 + (Q/H) Sr-90 ? 1, where

Q - specific activity of cesium-137 and strontium-90 in the controlled object;

H - standards for the specific activity of cesium-137 and strontium-90, established by the current rules and regulations for meat raw materials.

If the measured values ​​of the specific activity of cesium-137 exceed the values ​​of CU, then:

to obtain a final conclusion, raw meat is sent to state laboratories, where a complete radiological examination is carried out by radiochemical and spectrometric methods;

animals are returned for additional fattening with the use of "clean feed" and (or) drugs that reduce the transfer of radionuclides into the animal's body.

For all types of meat raw materials and livestock produced in “clean” territories affected by radioactive contamination and subject to radiation control at meat processing enterprises and farms, four values ​​of control levels have been introduced:

KU 1 = 100 Bq/kg- for farm animals and raw meat with bone tissue;

KU 2 = 150 Bq/kg- for meat raw materials, without bone tissue and offal;

KU 3 = 160 Bq/kg- for cattle raised in the territory of the Bryansk region, the most affected by the Chernobyl accident (after slaughter, these animals' bone tissue is subject to mandatory laboratory control for the content of strontium-90).

KU 4 = 180 Bq/kg- for commercial and other species of animals.

The assessment of the compliance of the results of measurements of the specific activity of cesium-137 with the requirements of radiation safety is carried out according to the criterion of not exceeding the value of the permissible limit.

The result of measuring the specific activity Q of the radionuclide cesium-137 is the measured value of Q meas. and error interval?Q.

If it turns out that Q meas.< ?Q, то принимается, что Q изм. = 0, и область возможных значений Q характеризуется соотношением Q ? ?Q.

The raw material meets the requirements of radiation safety, if, according to the criterion of not exceeding the value of the permissible limit, it satisfies the requirement: (Q ± ?Q) ? KU. Such raw materials enter production without restriction.

The raw material does not meet the requirements of radiation safety if (Q + ?Q) > KU. Raw materials can be recognized as not meeting the requirements of radiation safety according to the criterion of not exceeding the CL, if? Q ? KU/2. In this case, tests should be carried out in a radiation monitoring laboratory in accordance with the requirements of MUK 2.6.717-98 for food products.

Measuring. To determine the specific activity of cesium-137 in raw meat and animals, it is allowed to use devices that meet the requirements for radiation monitoring equipment included in the State Register and the equipment list of state veterinary laboratories.

A necessary condition for the suitability of measuring instruments for operational monitoring of the specific activity of cesium-137 are:

• - the possibility of measuring the specific activity of cesium-137 in raw meat or in animals without preparing counting samples;
• - ensuring the value of the measurement error of the sample "zero activity" no more than? Q ? KU/3 for a measurement time of 100 seconds at an equivalent dose rate of gamma radiation at the measurement site up to 0.2 μSv/h.

The specificity of the measured objects of control causes special requirements for the choice of measurement geometry and safety.

Measurement of carcasses, half-carcasses, quarters or meat blocks formed from the muscle tissues of one animal is carried out by direct contact of the detector with the measured object without sampling. To exclude contamination of the detector, it is placed in a protective polyethylene case. The use of the same cover is allowed when measuring only one batch of raw materials. When measuring cuts, offals and poultry, are the objects to be measured placed in pallets, boxes or other types of containers to create meat blocks deep? 30 cm. Accordingly, when measuring the carcasses of pigs or small ruminants, the measured objects should be placed in the form of feet with a total depth of "meat"? 30 cm. In the same way, the required depth is provided when measuring cattle quarters.

When measuring live cattle, half carcasses and hind quarters, the detector is placed in the region of the posterior femoral muscle group at the level of the knee joint between the femur and tibia; when measuring forequarters, the detector is placed in the region of the shoulder blade; when measuring carcasses, half carcasses and hindquarters, the detector is placed in the region of the gluteal muscle group to the left or right of the spine, between the spine, femur and sacrum.