A nuclear explosion represents light radiation. Nuclear explosion - the most terrible discovery of mankind

Question number 4. List the damaging factors nuclear explosion... Definition of the concept of "shock wave". Impact of the shock wave on people.

The damaging factors of a nuclear explosion include: shock wave, light radiation, penetrating radiation (ionizing radiation), radioactive contamination of the area, electromagnetic pulse and seismic (gravitational) waves.

Shock wave- the most powerful damaging factor of a nuclear explosion. About 50% of the entire explosion energy is spent on its formation during the explosions of medium and large caliber ammunition. It is a zone of sharp compression of air, spreading in all directions from the center of the explosion at supersonic speed. As the distance increases, the speed decreases rapidly and the wave weakens. The source of the shock wave is the high pressure in the center of the explosion, reaching billions of atmospheres. The greatest pressure occurs at the front boundary of the compression zone, which is commonly called the shock front.

The damaging effect of a shock wave is determined by excess pressure, that is, the difference between normal atmospheric pressure and the maximum pressure in the shock front. It is measured in kilopascals (kPa) or kilograms - force per 1 cm² (kgf / cm²).

The shockwave can injure unprotected people, cause concussion or death. Defeats can be direct or indirect.

Direct damage from a shock wave occurs as a result of the influence of excess pressure and the speed of air pressure, that is, a compression zone appears, followed by a vacuum zone. Due to the small size of the human body, the shock wave almost instantly covers it and subjects it to strong compression.

People can get indirect injuries as a result of blows from debris of destroyed buildings and structures, glass shards, stones, trees and other objects flying at high speed.

Impact on people, the shock wave causes injuries of varying severity:

Ø light lesions occur at an overpressure of 20–40 kPa (0.2–0.4 kgf / cm²). They are characterized by transient dysfunctions of the body (ringing in the ears, dizziness, headache), dislocations, bruises are possible;

Ø lesions of moderate severity occur at an overpressure of 40-60 kPa (0.4-0.6 kgf / cm²). In this case, there may be contusions, damage to the hearing organs, bleeding from the ears and nose, fractures and dislocations;

Ø severe injuries are possible at an overpressure of 60–100 kPa (0.6–1.0 kgf / cm²). They are characterized by severe contusions of the whole organism, loss of consciousness, multiple injuries, fractures, bleeding from the nose, ears; possible damage to internal organs and internal bleeding;

Ø extremely severe injuries occur at an overpressure of more than 100 kPa (1 kgf / cm²).

There are ruptures of internal organs, fractures, internal bleeding, concussion, prolonged loss of consciousness. Ruptures are observed in organs containing a large amount of blood (liver, spleen, kidneys) filled with fluid (cerebral ventricles, bladder and gall bladder). These injuries can be fatal.

Light emission is a stream of visible infrared and ultraviolet rays emanating from a luminous region consisting of nuclear explosion products and air heated to several thousand degrees. Its formation consumes 30-35% of the entire explosion energy of medium-caliber ammunition. The duration of the light emission depends on the power and type of explosion and can last up to ten seconds.

Infrared radiation has the greatest damaging effect. The main parameter characterizing light radiation is a light pulse, that is, the amount of light energy incident on 1 cm 2 (1 m 2) of the surface perpendicular to the direction of propagation of light radiation during the glow time. The light pulse is measured in calories per 1 cm 2 (cal / cm) or kilojoules per 1 m 2 (kJ / m 2) of the surface. The light radiation of a nuclear explosion, when directly exposed, causes burns. Secondary burns arising from the flames of burning buildings, structures, vegetation are possible.

Light radiation is absorbed by opaque materials and can cause massive fires in buildings and materials, as well as skin burns and eye damage.

Formation mechanism

Light radiation is thermal radiation emitted by products of a nuclear explosion heated to a high temperature (~ 10 7 K). Due to the high density of matter, the absorption capacity of the fireball is close to 1, so the spectrum of light radiation from a nuclear explosion is quite close to the spectrum of an absolutely black body. The spectrum is dominated by ultraviolet and X-ray radiation.

Protection of civilians

Light radiation is especially dangerous because it acts directly during the explosion and people do not have time for shelter in shelters.

Any opaque objects - walls of houses, automobiles and other equipment, steep slopes of ravines and hills - can protect from light radiation. Even tight clothing can protect - but in this case, it may catch fire.

In the event of a nuclear explosion, you should immediately take cover in any shadow from the outbreak or, if there is nowhere to hide, lie with your back up, with your feet to the explosion and cover your face with your hands - this will help to some extent reduce burns and injuries. You cannot look at the outbreak of a nuclear explosion and even turn your head towards it, as this can lead to severe damage to the organs of vision, up to complete blindness.

Defense of military equipment

Bombers designed to deliver nuclear strikes (tactical Su-24, strategic Tu-160) are partially or completely covered with white paint, which reflects a significant part of the radiation, to protect against light radiation. Armored vehicles provide complete protection of the crew from light radiation.

Shadows of Hiroshima

One of the most frightening evidence of the damaging effect of light radiation is the so-called shadows of Hiroshima (most often referred to in relation to people) - a shadow from a person or other obstacle on a background burnt out from radiation. People then quickly (usually within one day) died from burns, injuries and radiation damage, many were burned in fires and a firestorm that erupted after the explosion.

NUCLEAR WEAPON- nuclear weapons, the most powerful weapon of mass destruction, the action of which is based on the use of intranuclear energy released in a nuclear explosion. It is a nuclear weapon, a means of delivering it to the target (missile, torpedo, ... ... Veterinary encyclopedic dictionary

Nuclear explosion light radiation

Nuclear explosion light radiation represents electromagnetic radiation optical range, including ultraviolet, visible and infrared regions of the spectrum.

The source of light radiation is a luminous area. Light radiation propagates mainly in a straight line at a speed of 300 thousand m / sec. It accounts for approximately 35% of the energy of a nuclear explosion.

The main characteristic of light emission is a light pulse. A light pulse is the amount of energy incident during radiation per unit area of a fixed unshielded surface located perpendicular to the direction of radiation. In the SI system, the light pulse is measured in j / m2. The non-systemic unit of measurement is cal / cm2 (1 cal / cm2 = 4.2 104 J / m2). The value of the light pulse depends on the power of the nuclear explosion, the distance to the explosion, the shape of the luminous region, and the state of the atmosphere. It decreases with increasing distance from the center of the explosion. Smoky air, clouds located in the path of its propagation, fog, falling snow, rain cause significant attenuation of light radiation. Thus, thick fog can reduce the radius of the affected zones by 3 - 5 times.

The lifetime of the glowing area depends on the power of the nuclear explosion and is approximately equal for ammunition:

ultra-small caliber - tenths of a second;
small - 1-2 s;
medium - 2-5 s;
large - 5-10 s;
extra-large - 10 s.

The damaging effect of light radiation from a ground nuclear explosion is about 40% less than the damaging effect of light radiation from an airborne nuclear explosion.

The absorbed part of the energy of the light radiation is converted into heat, causing the irradiated object to heat up, which leads to carbonization or melting of materials. Assessment of the impact of light radiation on people is carried out according to four degrees of burns and thermal lesions of the skin.

1 degree - the appearance of painful redness and swelling of the skin;

2nd degree - the formation of bubbles;

3 degree - skin necrosis;

4 degree - skin charring.

Radii of fatal and light injuries of an open l / s from exposure to light radiation, km

Explosion power, thousand tons	Fatal defeats		Light damage (failure)
Explosion power, thousand tons	Outer	Interior	Outer	Interior

The personnel can get burns not only from direct exposure to light radiation, but also from indirect ones, for example, in case of fires that occur after a nuclear explosion. The degree of burns depends not only on the distance at which the personnel are from the center of the explosion, but also on the nature of the clothing, its color, density and thickness. For example, black cloth absorbs 99% of the incident light energy, while white cloth absorbs only 25%.

With direct observation of a nuclear explosion from a short distance, damage to the retina of the eyes, burns of the fundus may occur. At a considerable distance from the explosion site, light radiation causes temporary loss of vision, burns of the cornea and mucous membranes of the eyes.

Exposure to light radiation on the eyes causes temporary blindness - during the day for 1-5 minutes, at night for up to 30 minutes, and in more severe cases it can lead to loss of vision. Temporary blindness will be especially widespread at night and at dusk. Temporary blindness resolves quickly, leaves no consequences, and health care usually not required. With burns of the cornea and mucous membrane, lacrimation, severe photophobia and pain that pass after a few days are observed. For eye protection, special OPF or OP glasses should be used.

Distance from the epicenter of the explosion at which temporary blinding occurs personnel at night, km

Blinding duration, min	Explosion power, thousand tons
Blinding duration, min







30 and more

Note. The numerator shows the distance for an air explosion, in the denominator for a ground explosion

Fundus burns (when looking directly at the explosion) are possible at distances exceeding the radii of the skin burn zones. Temporary blindness usually occurs at night and at dusk and does not depend on the direction of gaze at the time of the explosion and will be massive. During the day, it appears only when looking at the explosion.

Observation through night vision devices eliminates glare, but it is possible through day vision devices; therefore, they should be covered with special curtains at night.

Surface ships and especially submarines are highly resistant to the effects of light radiation. However, when organizing protection, it is necessary to provide for the possibility of a fire from ignition of covers, wooden flooring, paint, etc. Great importance have preventive fire-prevention measures on ships and fleet facilities.

Folds of the terrain, deciduous forests, engineering structures significantly weaken the light radiation. In time, light radiation affects objects earlier than the shock wave. At equal distances of objects from the center of the explosion, the degree of exposure to light radiation on them in an air explosion is approximately 1.5 - 2 times greater than in a ground explosion. In underground and underwater explosions, light radiation as a damaging factor practical does not have. Timely adoption of protective measures reduces the possibility of damage to personnel by light radiation.

The action of light radiation lasts from tenths of a second in explosions of ultra-low power ammunition to tens of seconds in explosions with a power of more than 1 million tons. nuclear warhead large caliber will be reduced several times, which will significantly reduce or completely eliminate the defeat. Protective measures that prevent the occurrence of massive fires arising from the effect of light radiation on various combustible materials include such as clearing the areas where troops are located from flammable materials, coating combustible objects with clay, lime, the use of fire-resistant covers, tents that reflect light radiation well, curtains, etc.

First degree burns result in soreness, redness and swelling of the skin.

Second-degree burns are characterized by blistering.

Third-degree burns are characterized by skin necrosis with partial damage to the growth layer. Fourth degree burns are characterized by charring of the skin and subcutaneous tissue.

People with first and second degree burns usually recover, and with third degree burns

and fourth, with a significant part of the lesion of the skin, they can die.

The damage to the eyes by light radiation is possible of three types.

1. Temporary blindness, which can last 2 - 5 minutes during the day, and up to 30 minutes at night;

2.Fundus burns - occur when a person fixes his gaze on

point of explosion. This can happen even at such distances at which the light

radiation does not cause any burns. The lesion of the fundus is possible with a light pulse of 6 kJ / m2;

3. Burns of the cornea and eyelids (occur at the same distances as skin burns).

The degree of exposure to light radiation on the elements of the object depends on the properties of structural materials.

Protection against light radiation is easier than against other damaging factors

nuclear explosion, since any opaque barrier, any object that creates a shadow,

can be protected from light radiation.

Penetrating radiation is the flux of gamma rays and neutrons emitted into

environment from the nuclear explosion zone.

Depending on the energy of gamma rays and neutrons, they can propagate in

air in all directions at a distance of 2.5 - 3 km. Duration of penetrating radiation 10

15 seconds.

The damaging effect of penetrating radiation on people consists in the ionization of atoms and molecules of biological tissue by gamma radiation and neutrons, as a result of which the normal metabolism is disrupted and the nature of the vital activity of cells, individual organs and systems of the body changes, which leads to the occurrence of a specific disease - radiation sickness.

Depending on the dose absorbed by the biological tissues of the body, four degrees of radiation sickness are distinguished (Fig. 5.6.).

The absorbed dose is characterized by the amount of energy absorbed by the tissues of the human body. The unit of its measurement in the SI system is Gray (Gy), and the off-system unit is rad

(1 Gr = 100 rad = 1 J / kg).

The degree of radiation sickness

1 Degree 100 - 200 Rad 2 Degree 200 - 400 Rad 3 Degree 400 - 600 Rad 4 Degree More than 600 Rad

Rice. 5.6. The degree of radiation sickness, depending on the dose received

Radiation sickness of the first degree - the latent period lasts 2 - 3 weeks, after

which causes malaise, general weakness, nausea, dizziness, periodic fever. In the blood, the content of white blood cells (leukocytes) decreases. First-degree radiation sickness is curable.

Radiation sickness of the second degree - the latent period lasts about a week. The symptoms of the disease are more pronounced. With active treatment, cure occurs in 1.5 - 2

Radiation sickness of the third degree - the latent period is several hours. The disease is intense and difficult. If the outcome is favorable, recovery may

come in 6 - 8 months.

Radiation sickness of the fourth degree is the most dangerous. Without treatment, usually

ends in death within 2 weeks.

The severity of the lesion depends to a certain extent on the state of the body prior to irradiation and

its individual characteristics.

Induced activity can be formed in the elements of economic objects under the action of neutrons, which, during the subsequent operation of the object, will have a damaging effect on the service personnel.

Under the influence of large doses of neutron fluxes, the system loses its performance

radio electronics and automation.

Radioactive contamination of the terrain, the surface layer of the atmosphere and airspace occurs as a result of the passage of a radioactive cloud of a nuclear explosion or a gas aerosol cloud of a radiation accident.

The sources of radioactive contamination are:

in a nuclear explosion:

 fission products of nuclear - explosives (Pu-239, U-235, U-238);

radioactive isotopes (radionuclides) formed in soil and other materials

under the influence of neutrons - induced activity;

 unreacted part of the nuclear charge;

in case of a radiation accident:

spent nuclear fuel;

part of nuclear fuel.

In a ground-based nuclear explosion, the luminous region touches the surface of the earth and hundreds of

tons of soil instantly evaporate. The air currents rising behind the fireball pick up and raise a significant amount of dust. As a result, a powerful cloud is formed, consisting of a huge amount of radioactive and inactive particles, the sizes of which range from a few microns to several millimeters.

On the trail of a cloud of a nuclear explosion, depending on the degree of infection and danger

It is customary to mark four zones (A, B, C, D) on maps (diagrams), and a radiation accident - five zones (M, A, B, C, D) of contamination.

Each zone is characterized by the radiation dose rate Pdi and the radiation dose for the period of complete decay of the radioactive substance in a nuclear explosion, Dipr, or the radiation dose for the first year of exposure in radiation accidents, Dipgo (characteristics of the contamination zones on

the trail of the radioactive cloud are shown in Fig. 5.7).

In case of radioactive accidents
				140 mrad / h

Zone M

Zone A

Zone B

Zone D



In a ground nuclear explosion

Fig 5.7 Characteristics of contamination zones on the trail of a radioactive cloud

Zone M - "Radiation hazard" is applied in case of radiation accidents in red

color and only in peacetime.

Zone A - "Moderate contamination" is marked in blue.

Zone B - "Strong infection" is marked in green.

Zone B - "Dangerous contamination" is applied in brown.

Zone G - "Extremely Dangerous Infection" is applied in black

Damage to people while on the trail of a cloud is caused by ionizing radiation: alpha - particles (a stream of helium nuclei), beta - particles (a stream of electrons), gamma rays (a stream of photons, corpuscles of radiant energy), as well as neutrons.

The danger of injury to people in open areas on the trail of a radioactive cloud decreases over time.

Radioactive contamination, like penetrating radiation, can cause radiation sickness in people. The degree of radiation sickness depends on the amount of radiation dose received and the time during which a person is exposed to radiation. Distinguish between single, multiple and acute exposure of people. Irradiation received during the first four days is considered a single dose. Irradiation received for a time exceeding four days is multiple. Acute irradiation is the exposure of people to a single dose of 100 rad

Potential effects of human exposure depending on time and dose received

are given in table. 5.2.

Table 5.2.

Consequences of human exposure

Radiation dose	Irradiation signs
Radiation dose	Uniform
	Up to 4 days - no
	10-30 days - no	In 10% of those exposed to radiation, nausea, vomiting, a feeling of fatigue, without serious loss of performance.
	3 months - no	Mild signs of radiation sickness of the first degree.
	1 year - no	Radiation sickness of the second degree.
	Radiation sickness of the third degree. In the absence of treatment, mortality is up to 100%.
	Radiation sickness of the fourth degree. Mostly fatal
Over 1000	Lightning form of radiation sickness. The affected die in the first days after exposure.

At the initial stages of the existence of a shock wave, its front is a sphere centered at the point of explosion. After the front reaches the surface, a reflected wave is formed. Since the reflected wave propagates in the medium through which the direct wave has passed, the speed of its propagation turns out to be somewhat higher. As a result, at some distance from the epicenter, two waves merge near the surface, forming a front characterized by approximately twice the excess pressure.

So, when a 20-kiloton nuclear weapon explodes, the shock wave travels 1000 m in 2 seconds, 2000 m in 5 seconds, and 3000 m in 8 seconds. The leading edge of the wave is called the shock front. The degree of HC damage depends on the power and position of objects on it. The damaging effect of hydrocarbons is characterized by the magnitude of the excess pressure.

Since for an explosion of a given power, the distance at which such a front is formed depends on the height of the explosion, the height of the explosion can be selected to obtain the maximum values of the excess pressure over a certain area. If the purpose of the explosion is to destroy fortified military installations, the optimum explosion height is very low, which inevitably leads to the formation of a significant amount of radioactive fallout.

Light emission

Light radiation is a stream of radiant energy that includes the ultraviolet, visible and infrared regions of the spectrum. The source of light radiation is the luminous area of the explosion - heated to high temperatures and evaporated parts of the ammunition, surrounding soil and air. In an air explosion, the luminous area is a ball, in a ground explosion, it is a hemisphere.

The maximum surface temperature of the luminous region is usually 5700-7700 ° C. When the temperature drops to 1700 ° C, the glow stops. The light pulse lasts from fractions of a second to several tens of seconds, depending on the power and conditions of the explosion. Approximately, the duration of the glow in seconds is equal to the third root of the explosion power in kilotons. In this case, the radiation intensity can exceed 1000 W / cm2 (for comparison, the maximum intensity sunlight 0.14 W / cm2).

The result of the action of light radiation can be ignition and ignition of objects, melting, charring, high temperature stresses in materials.

When a person is exposed to light radiation, eye damage and burns of open areas of the body and temporary blindness occur, and damage to the areas of the body protected by clothing can also occur.

Burns arise from direct exposure to light radiation on exposed areas of the skin (primary burns), as well as from burning clothes, in fires (secondary burns). Depending on the severity of the lesion, burns are divided into four degrees: the first is redness, swelling and soreness of the skin; the second is the formation of bubbles; third - necrosis of the skin and tissues; the fourth is skin charring.

Penetrating radiation

Another striking factor nuclear weapons is penetrating radiation, which is a flux of high-energy neutrons and gamma-quanta generated both directly during the explosion and as a result of the decay of fission products. Along with neutrons and gamma quanta, during nuclear reactions alpha and beta particles are also formed, the influence of which can be ignored due to the fact that they are very effectively retained at distances of the order of several meters. Neutrons and gamma quanta continue to be released for a fairly long time after the explosion, affecting the radiation environment. The actually penetrating radiation usually includes neutrons and gamma quanta that appear within the first minute after the explosion. This definition is due to the fact that in a time of about one minute, the explosion cloud manages to rise to a height sufficient for the radiation flux on the surface to become practically invisible.

The intensity of the flow of penetrating radiation and the distance at which its action can cause significant damage depend on the power of the explosive device and its design. The dose of radiation received at a distance of about 3 km from the epicenter of a 1 Mt thermonuclear explosion is sufficient to cause serious biological changes in the human body. A nuclear explosive device can be specially designed in such a way as to increase the damage caused by penetrating radiation compared to the damage caused by other damaging factors (the so-called neutron weapon).

The processes occurring during an explosion at a significant altitude, where the air density is low, are somewhat different from those occurring during an explosion at low altitudes. First of all, due to the low air density, the absorption of the primary heat radiation occurs at much greater distances and the size of the explosion cloud can reach tens of kilometers. The processes of interaction of ionized particles of the cloud with magnetic field Earth. Ionized particles formed during the explosion also have a noticeable effect on the state of the ionosphere, making it difficult and sometimes impossible for the propagation of radio waves (this effect can be used to blind radar stations).

Damage to a person by penetrating radiation is determined by the total dose received by the body, the nature of the exposure and its duration. Depending on the duration of irradiation, the following total doses of gamma radiation are taken, which do not lead to a decrease in the combat effectiveness of personnel: single irradiation (pulsed or during the first 4 days) -50 rad; repeated irradiation (continuous or periodic) during the first 30 days. - 100 glad, within 3 months. - 200 glad, within 1 year - 300 glad.

Radioactive contamination

Radioactive contamination is the result of a significant amount of radioactive substances falling out of a cloud raised into the air. The three main sources of radioactive substances in the explosion zone are fission products of nuclear fuel, part of the nuclear charge that has not reacted, and radioactive isotopes formed in soil and other materials under the influence of neutrons (induced activity).

By settling on the surface of the earth in the direction of the cloud movement, the explosion products create a radioactive area called a radioactive trace. The density of contamination in the area of the explosion and along the trail of the movement of the radioactive cloud decreases with distance from the center of the explosion. The shape of the track can be very diverse, depending on the surrounding conditions.