Hydrodynamically hazardous objects. Hydrodynamic facilities and their purpose Which hydrodynamic structures are considered dangerous?
Hydrodynamically hazardous objects (HDOO) are hydraulic structures or natural formations that create a difference in water levels before and after this object.
Hydraulic structure- a national economic facility located on or near the water surface, intended:
- to use the kinetic energy of water movement for the purpose of converting into other types of energy;
- cooling of exhaust steam from thermal power plants and nuclear power plants;
- land reclamation;
- protection of coastal water areas;
- water intake for irrigation and water supply;
- drainage;
- fish protection;
- water level regulation;
- ensuring the activities of river and sea ports, shipbuilding and ship repair enterprises, shipping;
- underwater production, storage and transportation (pipelines) of minerals (oil and gas).
The main hydraulic structures include dams, reservoirs, and dams.
Dams- hydraulic structures (artificial dams) or natural formations (natural dams) that limit flow, create reservoirs and differences in water levels along the river bed.
Reservoir- a body of water in which water accumulates and is stored. Reservoirs can be long-term (as a rule, formed by hydraulic structures; temporary and permanent) and short-term (due to the action of natural forces; landslides, mudflows, avalanches, landslides, earthquakes, etc.).
Dam- the simplest dam, usually in the form of an embankment.
A hydrodynamic accident is an emergency event associated with the failure (destruction) of a hydraulic structure or part of it and the uncontrolled movement of large masses of water, causing destruction and flooding of vast areas.
Destruction (breakthrough) of hydraulic structures occurs as a result of natural forces (earthquakes, hurricanes, dam erosion) or human influence, as well as due to structural defects or design errors.
Damage in the body of the dam (break) resulting from its erosion is especially dangerous.
The flow of water rushing into the hole forms a breakthrough wave, which has a significant crest height and movement speed and has great destructive power.
The speed of the breakthrough wave is usually in the range from 3 to 25 km/h, and its height is 2–50 m.
The main consequence of a dam break during hydrodynamic accidents is catastrophic flooding of the area, which consists of rapid flooding of the underlying area by a break wave and the occurrence of flooding.
Catastrophic flooding is characterized by:
- the maximum possible height and speed of the breakthrough wave;
- the estimated time of arrival of the crest and front of the breakthrough wave at the corresponding target;
- boundaries of the possible flood zone;
- the maximum depth of flooding of a specific area of the area;
- duration of flooding of the territory.
When hydraulic structures are destroyed, part of the area adjacent to the river is flooded, which is called the possible flood zone.
Depending on the consequences of the impact of the hydraulic flow generated during a hydraulic accident, a zone of catastrophic flooding should be identified in the territory of possible flooding, within which a breakthrough wave propagates, causing massive losses of people, destruction of buildings and structures, and destruction of other material assets.
The time during which flooded areas can remain under water ranges from 4 hours to several days.
The main means of protecting the population from catastrophic flooding is their evacuation.
Evacuation of the population from populated areas located in a zone of possible catastrophic flooding within a 4-hour reach of a wave of a dam breaking of hydraulic structures is carried out in advance when a general evacuation is announced, and beyond these limits - in the event of an immediate threat of flooding. The population evacuated from zones of possible catastrophic flooding is resettled in non-flooded areas.
Rescue of people and property during catastrophic flooding includes searching for them in a flooded area, loading them onto boats or helicopters and evacuating them to safe places. If necessary, victims are provided with first aid. Only after this they begin to rescue and evacuate animals, material assets and equipment. The procedure for rescue operations depends on whether the catastrophic flooding occurred suddenly or whether appropriate measures were taken in advance to protect the population and material assets.
Reconnaissance units operating on high-speed boats and helicopters first of all determine the places of greatest concentration of people. Scouts rescue small groups of people on their own. Motor ships, barges, longboats, cutters, boats, and rafts are used to transport people.
When searching for people in flooded areas, boat crews periodically sound signals.
After the completion of the main work to evacuate the population, patrolling in flood zones does not stop. Helicopters and boats continue the search.
To ensure the embarkation and disembarkation of people, temporary berths are built, and the watercraft are equipped with gangways. Other devices are also being prepared for removing people from semi-submerged buildings, structures, trees and other objects. Rescuers must have hooks, ropes, lifebuoys and other necessary equipment and devices, and personnel directly involved in rescuing people on the water must wear life jackets.
In areas of probable catastrophic flooding, managers of enterprises and housing authorities, as well as the population, must be familiarized with the boundaries of possible flooding zones and its duration, with signals and methods of warning about the threat of flooding or flooding, as well as places where people should evacuate.
Chemically hazardous objects
Chemically hazardous facilities (CHF) are facilities that, in the event of an accident or destruction of which, can cause injury to people, farm animals and plants, or chemical contamination of the natural environment with hazardous chemicals in concentrations or quantities exceeding the natural level of their content in the environment.
The main damaging factor in an accident at a chemical waste facility is chemical contamination of the surface layer of the atmosphere; At the same time, contamination of water sources, soil, and vegetation is possible. These accidents are often accompanied by fires and explosions.
Emergency situations with the release (threat of release) of hazardous chemicals are possible during the production, transportation, storage, processing, as well as during the deliberate destruction (damage) of chemical technology facilities, warehouses, powerful refrigerators and water treatment facilities, gas pipelines (product pipelines) and vehicles servicing these facilities and industries.
The most dangerous accidents occur at enterprises that produce, use or store toxic substances and explosive materials. These include factories and combines of the chemical, petrochemical, and oil refining industries. A particular danger is posed by accidents on railway transport, accompanied by a spill of transported highly toxic substances (STS).
ADAS are toxic chemicals that are widely circulated in industry, agriculture and transport and can, when leaked from destroyed (damaged) technological tanks, storage facilities and equipment, lead to air contamination and cause mass casualties of people, farm animals and plants.
Among the numerous toxic substances used in industrial production and the economy, chlorine and ammonia are the most widespread.
Chlorine is a yellow-green gas with a pungent odor. It is used in cotton mills for bleaching fabrics, in paper production, rubber production, and in water supply stations for water disinfection. When spilled from faulty containers, chlorine “smoke.” Chlorine is heavier than air, so it accumulates in low-lying areas and penetrates into the lower floors and basements of buildings. Chlorine is highly irritating to the respiratory system, eyes and skin. Signs of chlorine poisoning are sharp chest pain, dry cough, vomiting, pain in the eyes, lacrimation.
Ammonia is a colorless gas with a pungent odor of “ammonia.” It is used in facilities where refrigeration units are used (meat processing plants, vegetable warehouses, fish canning factories), as well as in the production of fertilizers and other chemical products. Ammonia is lighter than air. Acute ammonia poisoning causes damage to the respiratory tract and eyes. Signs of ammonia poisoning include runny nose, cough, choking, watery eyes, and rapid heartbeat.
In addition to chlorine and ammonia, hydrocyanic acid, phosgene, carbon monoxide, mercury and other toxic substances are also used in production.
Hydrocyanic acid is a colorless, highly mobile liquid with the smell of bitter almonds. Hydrocyanic acid is widely used in chemical plants and factories producing plastics, plexiglass and artificial fiber. It is also used as a means of controlling agricultural pests. Hydrocyanic acid mixes easily with water and many organic solvents. Mixtures of hydrocyanic acid vapor with air can explode. Signs of hydrocyanic acid poisoning are a metallic taste in the mouth, weakness, dizziness, anxiety, dilated pupils, slow pulse, convulsions.
Phosgene- colorless, very poisonous gas. It is distinguished by the sweetish smell of rotten fruit, rotten leaves or wet hay. Phosgene is heavier than air. It is used in industry in the production of various solvents, dyes, medicines and other substances. In case of phosgene poisoning, as a rule, four characteristic periods are observed. The first period is contact with a contaminated atmosphere, characterized by some irritation of the respiratory tract, a feeling of an unpleasant taste in the mouth, slight salivation, and cough. The second period is observed after leaving the contaminated atmosphere, when all these signs quickly pass and the victim feels healthy. This is a period of latent action of phosgene, during which, despite external well-being, lung damage develops within 2–12 hours (depending on the severity of intoxication). The third period is characterized by rapid breathing, fever, and headache. An intensifying cough appears with copious discharge of liquid, foamy sputum (sometimes with blood), pain in the throat and chest is felt, the heartbeat quickens, the nails and lips turn blue, and then the face and limbs. The fourth period is characterized by the fact that as a result of the development of the lesion, pulmonary edema occurs, which reaches a maximum at the end of the first day and lasts for 1–2 days. If during this period the affected person does not die, then from 3–4 days his gradual recovery begins.
Carbon monoxide is a colorless gas, odorless in its pure form, slightly lighter than air, poorly soluble in water. Widely used in industry for the production of various hydrocarbons, alcohols, aldehydes, ketones and carboxylic acids. Carbon monoxide (as a by-product when using oil, coal and biomass) is formed during incomplete oxidation of carbon, under conditions of insufficient air access. Signs of carbon monoxide poisoning are headache, dizziness, impaired coordination of movements and reflex sphere, a number of changes in mental activity reminiscent of alcohol intoxication (euphoria, loss of self-control, etc.). Redness of the affected skin is characteristic. Later, convulsions develop, consciousness is lost, and if emergency measures are not taken, the person may die due to respiratory and cardiac arrest.
Mercury is a liquid silvery-white metal that is used in the manufacture of fluorescent and mercury lamps, measuring instruments (thermometers, barometers, pressure gauges), in the production of amalgams, products that prevent wood decay, in laboratory and medical practice. Symptoms of mercury poisoning appear after 8–24 hours and are expressed in general weakness, headache, pain when swallowing, and fever. Somewhat later, sore gums, abdominal pain, stomach upsets, and sometimes pneumonia are observed. Possible death. Chronic intoxication (poisoning) develops gradually and occurs for a long time without obvious signs of disease. Then increased fatigue, weakness, drowsiness, apathy, emotional instability, headaches, and dizziness appear. At the same time, trembling of the hands, tongue, eyelids, and in severe cases, the legs and the whole body develops.
Accidents at enterprises producing or using toxic substances may be accompanied by the release of these substances into the atmosphere. When toxic substances enter the atmosphere in a gaseous or vaporous state, they form zones of chemical contamination, the area of which sometimes reaches several tens of kilometers or more.
To determine the presence of toxic substances in the air, on the ground and on various objects, chemical reconnaissance devices (VPKhR, UG-2, VIKHK, ISKhK, etc.) are used. A description of the composition and operating principle of these devices is given in Chapter 2.
In the event of an accident at a chemical plant and the appearance of toxic substances in the air and on the ground, the civil defense signal “Attention everyone!” is given. - sirens, intermittent beeps of enterprises and special vehicles, and messages from local authorities or civil defense are broadcast on radio and television.
The main measures to protect personnel and the public in case of accidents at chemical waste facilities are:
- use of personal protective equipment and isolation shelters;
- the use of antidotes and skin treatments;
- compliance with behavior (protection) regimes in the contaminated area;
- evacuation of people from the contaminated zone resulting from the accident;
- sanitary treatment of people, decontamination of clothing, territory, structures, transport, equipment and property.
Personnel and the public working and living near the chemical waste facility must know the properties, distinctive features and potential dangers of the toxic substances used at this facility, methods of individual protection against damage to the toxic substances, be able to act in the event of an accident, and provide first aid to those affected.
Workers and employees, upon hearing the warning signal, immediately put on personal protective equipment, primarily gas masks. Everyone at their workplace must do everything possible to reduce the disastrous consequences of the accident: ensure the correct shutdown of energy sources, stop units, devices, shut off gas, steam and water communications in accordance with the conditions of the technological process and safety regulations. Then the personnel take refuge in prepared shelters or leave the infection zone. When a decision to evacuate is announced, workers and employees are required to report to the prefabricated evacuation points of the facility.
Workers included in the emergency rescue units of the civil defense, upon receiving a signal about an accident, arrive at the assembly point of the unit and participate in localizing and eliminating the source of chemical damage.
Residents, when receiving information about an accident and the danger of chemical contamination, must wear personal respiratory protection (Fig. 3.18), and in their absence, use simple respiratory protection (handkerchiefs, paper napkins, pieces of cloth moistened with water) and skin (raincoats) , capes) and take refuge in the nearest shelter or leave the area of possible chemical contamination.
Rice. 3.18. Personal respiratory protection:
1 -
respirator R-2; 2
- “Petal” type respirator; 3
- gas mask; 4
- anti-dust fabric mask PTM-1; 5
- cotton-gauze bandage
If it is impossible to leave your home (if the cloud has already covered your area of residence or is moving at such a speed that you cannot escape from it), you should seal your home premises. To do this, you need to tightly close doors, windows, ventilation and chimneys. Curtain the entrance doors with blankets or thick fabric. Seal the cracks in doors and windows with paper, tape, adhesive tape or plug them with wet rags.
When leaving your home, you should close the windows and vents, turn off electric heating devices and gas (turn off the fire in the stoves), and take what you need from warm clothes and food.
You need to leave the zone of chemical contamination in a direction perpendicular to the direction of the wind. You should move quickly through the contaminated area, but do not run, do not raise dust or touch surrounding objects, and avoid crossing tunnels, ravines, and hollows where the concentration of toxic substances is higher. Respiratory and skin protection should be used throughout the entire travel route. After leaving the infected area, you need to take off your outer clothing, wash your eyes and exposed areas of the body with water, and rinse your mouth. If you suspect poisoning with toxic substances, avoid any physical activity, drink plenty of fluids and consult a medical professional.
When providing assistance to victims, the first step is to protect the respiratory system from further exposure to toxic substances. To do this, put a gas mask or a cotton-gauze bandage on the victim, having previously moistened it in case of chlorine poisoning with water or a 2% solution of baking soda, and in case of ammonia poisoning - with a 5% solution of citric acid, and evacuate him from the contaminated area.
In case of ammonia poisoning, rinse the skin, eyes, nose, mouth with plenty of water. Place 2-3 drops of a 30% solution of albucid into your eyes, and olive oil into your nose. It is prohibited to perform artificial respiration.
In case of chlorine poisoning, rinse the skin, mouth, and nose generously with a 2% solution of baking soda. If breathing stops, give artificial respiration.
In case of hydrocyanic acid poisoning, if it enters the stomach, immediately induce vomiting. Rinse your stomach with clean water or a 2% solution of baking soda. If breathing stops, give artificial respiration.
No specific therapeutic or prophylactic agents have been found against phosgene. Phosgene poisoning requires fresh air, rest and warmth. Under no circumstances should you perform artificial respiration.
In case of carbon monoxide poisoning, inhale ammonia, apply a cold compress to the head and chest, if possible, inhale humidified oxygen, and if breathing stops, perform artificial respiration.
In case of mercury poisoning, it is necessary to immediately rinse the stomach thoroughly through the mouth with water with 20–30 g of activated carbon or protein water, then give milk, an egg yolk beaten with water, and then a laxative. In case of acute, especially inhalation, poisoning, after leaving the affected area, it is necessary to give the victim complete rest and then hospitalize.
In order to eliminate the possibility of further harm to the population in an accident with the release of toxic chemicals, a whole range of work is being carried out to decontaminate the area, clothing, shoes, and household items.
Most often, three methods of degassing are used: mechanical, physical and chemical. Mechanical methods involve removing toxic chemicals from the area, objects, or isolating the contaminated layer. For example, the top contaminated layer of soil is cut off and taken to specially designated burial places, or it is covered with sand, earth, gravel, or crushed stone. Physical methods consist of treating contaminated objects and materials with hot air and water steam. The essence chemical methods degassing is the complete destruction of toxic chemicals by decomposing them and converting them into other non-toxic compounds using special solutions.
Decontamination of clothing, shoes, and household items is carried out in a variety of ways (ventilation, boiling, steam treatment) depending on the nature of the contamination and the properties of the material from which they are made.
Related information.
>>OBZD: Hydrodynamic accidents
Chapter 5.
From the history of hydrodynamic accidents
The St. Francis Dam in California will forever go down in geological engineering as a tragic example of human carelessness. It was built 70 km from Los Angeles in the San Francisco Canyon with the purpose of storing water for its subsequent distribution through the Los Angeles water supply.
Filling of the reservoir began in 1927, but the water reached its maximum level only on March 5, 1928. By that time, the seepage of water through the dam was already causing concern among local residents, but the necessary measures were not taken. Finally, on March 12, 1928, water broke through the soil, and under its pressure the dam collapsed. Witnesses disasters there were no survivors. It was a terrible sight. The water rushed through the canyon like a wall about 40 m high. After 5 minutes, it demolished a power plant located 25 km downstream. All living things, all buildings were destroyed. Then the water rushed into the valley. Here its height decreased and its destructive power weakened somewhat, but remained quite dangerous. Few in the upper valley managed to survive. These were people who accidentally escaped in trees or on debris floating in the stream.
By the time the flood reached the coastal plain, it was a muddy wave 3 km wide, rolling at the speed of a fast-walking person. Behind the wave, the valley was flooded for 80 km. More than 600 people died during this flood.
The collapse of the St. Francis Dam became an example of how not to build hydraulic structures.
5.1. Types of accidents at hydrodynamically hazardous facilities
FROM THE HISTORY OF HYDRODYNAMIC ACCIDENTS
St. Francis Dam in California forever entered the analogues of engineering geology as a tragic example of human carelessness. It was built 70 km from Los Angeles with the purpose of storing water for its subsequent distribution through the Los Angeles water supply.
Filling of the reservoir began in 1927, but the water reached its maximum level only on March 5, 1928. By that time, the seepage of water through the dam was already causing concern among local residents, but the necessary measures were not taken. Finally, on March 12, 1928, water broke through the soil, and under its pressure the dam collapsed. It was a terrible sight. The water rushed through the canyon like a wall about 40 m high. After 5 minutes, it demolished a power plant located 25 km downstream. All living things, all buildings were destroyed. Then the water rushed into the valley. Here its height decreased and its destructive power weakened somewhat, but remained quite dangerous. Few in the upper valley managed to survive.
These were people who accidentally escaped in trees or on debris floating in the stream.
By the time the flood reached the coastal plain, it was a muddy wave 3 km wide, rolling at the speed of a fast-walking person. Behind the wave, the valley was flooded for 80 km. More than 600 people died during this flood.
Types of accidents at hydrodynamically hazardous facilities
Hydrodynamic accident - an accident at a hydraulic structure associated with the spread of water at high speed and creating a threat of a man-made emergency.
Such an accident could result in catastrophic flooding.. Flooding of coastal areas with settlements and other objects located on them can occur as a result of the destruction of hydraulic structures (dams, dikes, cofferdams) located upstream of the river, or the system of irrigation structures in irrigated areas.
Flooding is the covering of an area with water. The term “flooding” hereinafter refers to the flooding of an area due to the destruction of hydraulic structures.
In the flooded area, four zones of catastrophic flooding are distinguished:
First zone directly adjacent to the hydraulic structure and extends 6-12 km from it. The wave height here can reach several meters. Characterized by a rapid flow of water with a flow speed of 30 km/h or more. Wave travel time - 30 minutes.
Second zone- fast current zone (15-20 km/h). The length of this zone can be 15-25 km. The wave travel time is 50-60 minutes.
Third zone- middle flow zone (10-15 km/h) with a length of up to 30-50 km. The wave travel time is 2-3 hours.
Fourth zone- zone of weak current (spill). The current speed here can reach 6-10 km/h. The length of the zone, depending on the terrain, can be 35-70 km.
Catastrophic flood zone- a flood zone within which massive losses of people, farm animals and plants occurred, material assets, primarily buildings and other structures, were significantly damaged or destroyed.
In our country there are more than 30 thousand reservoirs and several hundred reservoirs for industrial wastewater and waste. There are 60 large reservoirs with a capacity of more than 1 billion m3. The distribution of hydrodynamically hazardous objects by region of Russia (in%) is shown in the diagram.
Hydrodynamically dangerous objects are structures or natural formations that create a difference in water levels before (upstream) and after (downstream) them. These include hydraulic structures of the pressure front: dams, dams, dikes, water intakes and water intake structures, pressure basins and equalization reservoirs, waterworks, small hydroelectric power stations and structures that are part of the engineering protection of cities and agricultural lands.
Hydrodynamic structures of the pressure front are divided into permanent and temporary.
Permanent are called hydraulic structures used to perform any technological tasks (for electricity production, land reclamation, etc.).
Temporary include structures used during the construction and repair of permanent hydraulic structures.
In addition, hydraulic structures are divided into primary and secondary.
The main ones include pressure front structures, the breakthrough of which will entail disruption of the normal life of the population of nearby settlements, destruction, damage to residential buildings or economic facilities.
The secondary ones include hydraulic structures of the pressure front, the destruction or damage of which will not entail significant consequences.
The main damaging factors of hydrodynamic accidents associated with the destruction of hydraulic structures are a breakthrough wave and catastrophic flooding of the area.
Causes of hydrodynamic accidents and their consequences
The causes of accidents accompanied by a breakthrough of hydraulic structures of the pressure front and flooding of coastal areas are most often:
Destruction of the foundations of structures and insufficient spillways;
- impact of natural forces (earthquake, hurricane, collapse, landslide);
- structural defects, violation of operating rules and the impact of floods (Table 14).
The percentage of accidents for groups of dams of various types is presented in Table. 15.
Of the 300 dam failures (accompanied by their failure) in various countries over 175 years, in 35% of cases the cause of the accident was exceeding the calculated maximum discharge flow (water overflowing the dam crest).
DAMAGING FACTORS in case of hydrodynamic accidents, several. In addition to the damaging factors characteristic of other floods (drowning, hypothermia), in accidents at hydrodynamically dangerous objects, damage is caused mainly as a result of the action of a breakthrough wave. This wave is formed in the downstream as a result of the rapid fall of water from the upstream.
Damaging effect of a breakthrough wave manifests itself in the form of a direct impact on people and structures of a mass of water moving at high speed, and the fragments of destroyed buildings and structures and other objects it moves.
Breakthrough wave a large number of buildings and other structures may be destroyed. The degree of destruction will depend on their strength, as well as the height and speed of the wave.
In case of catastrophic flooding A threat to the life and health of people, in addition to the impact of a breakthrough wave, is posed by exposure to cold water, neuropsychic stress, as well as flooding (destruction) of systems that support the life of the population.
The consequences of such flooding may be aggravated by accidents at potentially hazardous facilities falling within its zone. In areas of catastrophic flooding, water supply systems, sewerage systems, drainage communications, garbage collection sites and other waste may be destroyed (eroded). As a result, sewage, garbage and waste pollute flood zones and spread downstream. The danger of the emergence and spread of infectious diseases is increasing. This is also facilitated by the accumulation of population in a limited area with a significant deterioration in material and living conditions.
CONSEQUENCES OF ACCIDENTS at hydrodynamically hazardous objects may be difficult to predict. Being located, as a rule, within or upstream of large populated areas and being objects of increased risk, if destroyed, they can lead to catastrophic flooding of vast territories, a significant number of cities and villages, economic facilities, mass loss of life, long-term cessation of shipping, agricultural and fishing industries.
Population losses, located in the zone of the breakthrough wave, can reach 90% at night, and 60% during the day. Of the total number of victims, the number of deaths may be 75% at night, 40% during the day.
Greatest danger represent the destruction of hydraulic structures of the pressure front - dams and dams of large reservoirs. When they are destroyed, rapid (catastrophic) flooding of large areas occurs and significant material assets are destroyed.
In June 1993, the Kiselyovskoe reservoir dam on the river broke. Kakve and severe flooding in the city of Serov, Sverdlovsk region. The emergency situation arose as a result of a catastrophic flood resulting from heavy rains in the final phase of the spring flood.
With a sharp rise in water in the river. Kakwe flooded 60 km 2 in its floodplain, residential areas in the city of Serov and nine other settlements. The flood affected 6.5 thousand people, of which 12 died. 1,772 houses fell into the flood zone, of which 1,250 became uninhabitable. Many industrial and agricultural facilities were damaged.
Hydrodynamic accident- this is an emergency event associated with the failure (destruction) of a hydraulic structure or part of it and the uncontrolled movement of large masses of water, causing destruction and flooding of vast areas.
Hydraulic structure- a national economic object located on or near the water surface, intended for:
using the kinetic energy of water movement for the purpose of converting into other types of energy;
cooling of exhaust steam from thermal power plants and nuclear power plants;
land reclamation;
protection of coastal water areas;
water intake for irrigation and water supply;
drainage;
fish protection;
water level regulation;
ensuring the activities of river and sea ports, shipbuilding and ship repair enterprises, shipping;
underwater production, storage and transportation (pipelines) of minerals (oil and gas).
Destruction (breakthrough) of hydraulic structures occurs as a result of natural forces (earthquakes, hurricanes, dam erosion) or human influence, as well as due to structural defects or design errors.
To the main hydraulic structures include: dams, water-like catchment structures, dams,
Dams - hydraulic structures (artificial dams) or natural formations (natural dams) that limit flow, create reservoirs and differences in water levels along the river bed.
Reservoirs can be long-term (as a rule, formed by hydraulic structures; temporary and permanent) and short-term (due to the action of natural forces; landslides, mudflows, avalanches, landslides, earthquakes, etc.).
Proran - damage in the body of the dam resulting from its erosion.
The flow of water rushing into the hole forms a breakthrough wave, which has a significant crest height and movement speed and has great destructive power. A breakthrough wave is formed by the simultaneous superposition of two processes: the fall of reservoir water from the upper to the lower pool, generating a wave, and a sharp increase in the volume of water at the place of the fall, which causes the flow of water from this place to others where the water level is lower.
The height of the breakthrough wave and the speed of its propagation depend on the size of the hole, the difference in water levels in the upper and lower pools, the hydrological and topographic conditions of the river bed and its floodplain.
Wave propagation speed The breakthrough is usually in the range from 3 to 25 km/h, and the height is 2-50 m.
The main consequence of a dam break during hydrodynamic accidents is catastrophic flooding of the area , which consists in rapid flooding by a wave of breakthrough of the lower-lying area and the occurrence of flooding.
Catastrophic flooding characterized by:
the maximum possible height and speed of the breakthrough wave;
the estimated time of arrival of the crest and front of the breakthrough wave at the corresponding target;
boundaries of the possible flood zone;
the maximum depth of flooding of a specific area of the area;
duration of flooding of the territory.
When hydraulic structures are destroyed, part of the area adjacent to the river, called possible flood zone .
Depending on the consequences of exposure hydroflow formed during a hydraulic accident, in the territory of possible flooding, a zone of catastrophic flooding should be identified, within which a breakthrough wave propagates, causing massive losses of people, destruction of buildings and structures, and destruction of other material assets.
The time during which flooded areas can remain under water ranges from 4 hours to several days.
In terms of the scale of distribution, the complexity of the situation and the severity of the consequences, the most catastrophic are fires, explosions, accidents with the release (threat of release) of highly toxic, radioactive and biologically hazardous substances, and hydrodynamic accidents. Mostly such accidents occur at potentially hazardous facilities.
Causes and sources of man-made accidents and disasters
The modern world is characterized by an increasing scale of consequences man-made accidents and disasters (whether aviation, rail or maritime) while reducing the likelihood of their implementation. For example, if in the 40s of our century dozens of people died in dozens of aviation accidents, now a single disaster claims the lives of hundreds of people. Indeed, dangers of man-made origin have already become, in terms of damage, commensurate with natural phenomena negative for humans. There are many examples of this. Thus, atmospheric influences - tornadoes occur up to 700 times a year. About 2% of them cause damage, associated with the death of an average of 120 people and the loss of about 70 million dollars. At the same time, in oil refining alone, according to experts, about 1,500 accidents and disasters occur annually, 4% of which are accompanied by the loss of 100-150 human lives and material damage up to $100 million.
Many modern potentially hazardous industries are designed in such a way that the probability of a major accident at them is estimated at about 10" 4. This means that due to an unfavorable combination of circumstances, taking into account the real reliability of mechanisms, instruments, materials and people, one destruction of the object is possible per 10,000 object-years . If the object is unique, then with a very high probability no major accident will occur on it during this time. If there are 1000 such objects, then every decade you can expect the destruction of one of them. And finally, if the number of such objects is close to 10,000, then every year one of them can statistically be the source of an accident. This circumstance lies one of the reasons for the problems discussed. An object designed according to technical means and regulatory requirements, sufficiently reliable in conditions of small replication, loses statistical reliability in mass reproduction.
The increasing scale of the consequences of ongoing man-made accidents and disasters is the result of the peculiarities of scientific and technological progress at the present stage. The energy availability of human society continues to grow continuously. Objects that are energy-saturated and use hazardous substances are becoming more and more concentrated. In the name of economic indicators, their unit capacity is increasing. Pressure is increasing in a variety of industrial apparatus and transport communications, the network of which is becoming more and more ramified. In the energy sector alone, about 10 billion tons of fuel equivalent are produced, transported, stored and used annually in the world. In terms of energy equivalent, this mass of fuel, capable of burning and exploding, has become comparable to the arsenal of nuclear weapons accumulated in the world over the entire history of its existence.
The increase in the scale and concentration of production leads to the accumulation of potential dangers. This can be judged by the specific (either per capita or per unit area) values of lethal doses for humans contained in various industries in Western Europe. So, for arsenic this value is about 0.5 billion doses, for barium - about 5 billion, and for chlorine - 10 trillion doses. These figures make clear the universally expressed concern about ensuring the safety of chemical plants in the first place.
When identifying the causes and sources of man-made accidents, including chemical ones, it is first necessary to assess the technological content, quantitative and qualitative characteristics of damaged facilities or vehicles. At the same time, it is necessary to determine the design ergonomic deviations that caused accidents due to the mismatch of the designs of industrial (or transport) control systems with the anatomical and physiological capabilities of a person. In such situations, people who directly manage technical means, together with other participants in production, become victims of pre-planned circumstances.
The probability of an accident (risk) as a quantitative measure of the realization of danger is entirely determined by the reliability and observability (blockability) of production.
The primary cause of an emergency is the occurrence of a failure, and most single failures are Markov events, that is, they do not depend on the history of the system and are easily localized in such a common way in the chemical industry as blocking. In practice, this means that a single failure simply stops production. The accumulation of single failures leads to an accident.
This is how V.A. describes this process. Legasov in his work “Problems of safe development of the technosphere”:
“Usually an accident is preceded by a phase of accumulation of any defects in the equipment or deviations from normal process procedures. The duration of this phase can be measured in minutes or days. In themselves, defects or deviations do not pose a threat, but at a critical moment they will play a fatal role. During during the Bhopal disaster (in Bhopal, India, ed.), for example, during this phase of the accident, the refrigeration devices on the container with methyl isocyanate were turned off, the communication linking this container with the poisonous gas absorber was depressurized, and the torch intended for burning them in emergency situations was turned off Before the accident at Chernobyl, several emergency protections were also turned off, and the reactor core was deprived of the mandatory minimum of neutron-absorbing rods. The accumulation of such deviations from the norm during this phase is associated either with the unobservability of the operation of structural elements and materials due to the lack of necessary diagnostic tools, or, which happens much more often, because the staff gets used to this kind of deviation - after all, they are quite frequent and in the vast majority of cases do not lead to accidents. Therefore, the sense of danger is dulled, restoration of the normal state of instruments and equipment is postponed, and the process continues in dangerous conditions.
In the next phase, some initiating event occurs, usually unexpected and rare. In Bhopal, this was a small amount of water entering a container with methyl isocyanate through a permeable valve, which caused an exothermic reaction, which was accompanied by a rapid rise in temperature and pressure of the metal isocyanate. In Chernobyl, this was the introduction of positive reactivity into the reactor core: instantaneous overheating of the fuel elements and coolant followed. In such situations, the operator has neither the time nor the means to act effectively.
The accident itself occurs in the third phase as a result of the rapid development of events. In Bhopal, this is the opening of a check valve and the release of poisonous gas into the atmosphere. In Chernobyl - the destruction of structures and buildings by a steam explosion, enhanced by side chemical processes, and the removal of accumulated radioactive gases and part of the dispersed fuel outside the fourth block. This last phase would not have been possible without the accumulation of errors in the first stage."
Apparently, it is true that in any complex system there will always be at least one non-Markovian failure that causes many subsequent ones. The avalanche-like process of increasing failures is the development of an emergency situation into an accident with loss of control over the system and its transition to a damaged state. At this stage, the system is no longer manageable and cannot be restored on its own. The reason for this situation is the limited observability of the system. An increase in observability, that is, the number of controlled parameters and methods for processing them, leads to the exclusion of identified non-Markov failure. However, it can always be argued that this new system will also contain a new, potentially unobservable failure.
It is known that a chemical plant, as a source of increased danger, can be in two stable states - normal and damaged. The transition from one stable state to another occurs through an unstable state, which is usually called an emergency situation.
The state of an enterprise, like any complex system, can be described by an n-dimensional vector in phase space. The coordinates of such a vector are the parameters of technological processes. Usually it is possible to indicate the lower and upper boundaries of the parameters within which the process proceeds steadily. If the parameters go beyond the boundaries, this is a sign of an emergency situation, that is, stability lotteries. Now only a special emergency protection system can return the process to its previous boundaries. If this happens, then the emergency situation is considered localized. Otherwise, the object goes into a new stable state - stricken, which is characterized by a complete loss of control and management. From this moment on, the object itself becomes a source of damaging factors for the environment. That is, a new n-dimensional vector of the object’s state appears, the coordinates of which are the damaging factors: shock wave, thermal radiation, chemical contamination, etc. The ability to control this vector is, as a rule, limited and requires the involvement of significant regional forces and resources. Actually, this vector is the source of damage, the peculiarity of which is almost complete uncontrollability in real time, and with increasing time from the moment the emergency situation occurs to the transition to the affected state, the uncertainty does not increase linearly. In general, the maximum amount of damage is determined by the amount of energy and matter stored in technological processes at the time of the accident.
Extensive statistics of accidents and catastrophes and the study of processes associated with these phenomena make it possible to fairly reliably predict the “scenario” and the maximum possible consequences of accidents.
The condition and operational efficiency of technical means (emergency prevention systems), structural deficiencies of materials and the degree of their compliance with requirements, wear, corrosion and aging of structures - all this is the subject of research when identifying the possible causes of accidents and disasters. However, the human factor is no less important. Analysis of statistical data shows that over 60% of accidents occur due to personnel errors. Currently, the proportion of accidents occurring as a result of improper actions of maintenance personnel has increased significantly in the world. Most often this happens due to a lack of professionalism, as well as the inability to make optimal decisions in a difficult environment, under time pressure. When psychologically overloaded, some specialists commit incorrect actions that lead to irreparable consequences.
World experience shows that in order to prevent emergency situations, a set of legislative, economic and technical measures is needed, which would essentially represent an informal risk management system. The basis of such a system is the legislative initiative to establish an acceptable level of risk for today. The implementation mechanism is an effective tax and insurance policy that provides economic incentives to reduce the risk level of a particular enterprise. The means that ensure the required level of safety are technical devices and measures.
A necessary element of such a system is the institute of state certification of hazardous industries in terms of safety level, and the certificate is the main document for determining the amount of the enterprise's contribution to the insurance fund. The greater the risk. The higher the contribution to the insurance fund. Compensation for losses due to accidents is carried out only through this fund. It could also be a source of financing for large industry programs to reduce risk.
Potentially dangerous objects. Assessment of sources of technogenic hazard.
An analysis of man-made emergency situations shows that a significant proportion of them, especially those that lead to injury to people and large material losses, arise as a result of accidents and catastrophes at industrial facilities.
To facilitate the work of identifying and implementing measures to prevent the occurrence of emergency situations, reduce the severity of their consequences and create conditions for their elimination, it is important to systematize objects according to the characteristics that most influence the occurrence of emergencies at these objects. This sign is a danger that in the event of an industrial accident at a given facility: release of harmful substances into the environment (RV, SDYAV, BOV), explosion, fire, catastrophic flooding.
An economic or other object, in the event of an accident, the death of cradles, farm animals and plants may occur, a threat to human health, or damage to the national economy and the environment may be caused, is called a potentially dangerous object.
According to their potential danger, economic objects are divided into four groups:
chemically hazardous facilities (CHF);
radiation hazardous objects (RHO);
fire and explosive objects (AF);
hydrodynamically hazardous objects (HDOO).
Currently, there are more than 2 thousand large enterprises alone that pose a threat of a regional or even global nature in Russia. These are mainly chemically hazardous objects.
Chemically hazardous objects (CHF) - this is an object, in the event of an accident or destruction of which, damage to people, agricultural animals and plants, or chemical contamination of the natural environment with dangerous chemicals in concentrations or quantities exceeding the natural level of their content in the environment can occur.
The main damaging factor in case of an accident at a chemical waste facility - chemical contamination of the ground layer of the atmosphere; At the same time, contamination of water sources, soil, and vegetation is possible. These accidents are often accompanied by fires and explosions.
If there are chemical hazardous substances in a city, district, or region, then this administrative-territorial unit (ATE) can also be classified as chemically hazardous. The criteria characterizing the degree of such danger are defined in the following regulatory documents.
For objects, this is the quantity; for ATE, this is the proportion (%) of the population that may be in the area of possible infection.
Based on the scale of distribution of damaging factors, accidents at chemical waste facilities are divided into:
local (private) - if it does not go beyond the border of its sanitary protection zone;
local - also covers individual areas of nearby residential buildings;
regional - when it includes vast territories of a city, district, region with a high population density;
global - complete destruction of a large chemical facility.
Typical chemical waste products using the most common chemical substances - chlorine and ammonia:
water treatment plants;
refrigeration units;
enterprises of the chemical, petrochemical defense industry;
railway tanks with SDYAV, product pipelines, gas pipelines.
Radiation hazardous objects (RHO) - any object, incl. a nuclear reactor, a plant using nuclear fuel or processing nuclear material, as well as a storage place for nuclear material and a vehicle transporting nuclear material or a source of ionizing radiation, in the event of an accident or destruction of which radiation or radioactive contamination of people and farm animals may occur and plants, as well as the natural environment.
Typical ROOs include:
Atom stations;
enterprises for reprocessing spent nuclear fuel and disposal of radioactive waste;
nuclear fuel manufacturing enterprises;
research and design organizations with nuclear installations and stands;
transport nuclear power plants;
military facilities.
Potential danger of ROO is determined by the amount of radioactive substances that can enter the environment as a result of an accident at the waste disposal facility. And this, in turn, depends on the power of the nuclear installation. The greatest danger is posed by nuclear power plants and research institutes with nuclear installations and stands. Accidents on them are classified both according to the possible scale of consequences: local, local, general, regional, global, and according to operating standards (design, design with the greatest consequences, beyond design).
Fire and explosive object (P BOO ) - This is an object where products and substances are produced, stored, used or transported that, under certain conditions (accidents, initiation), acquire the ability to ignite (explode).
Based on their potential danger, these objects are divided into 5 categories:
A- objects of the oil, gas, oil refining, chemical, petrochemical industries, petroleum product warehouses;
B- production of coal dust, wood flour, powdered sugar, synthet. rubber;
IN- sawmills, woodworking, carpentry, etc. workshops, oil warehouses;
G- metallurgical production, heat treatment shops, boiler houses;
D- facilities for processing and storing cold fireproof materials.
Particularly dangerous objects categories A, B and C.
Fires and explosions lead to the destruction of buildings and structures due to combustion or deformation of their elements and equipment, the occurrence of an air shock wave (during an explosion), the formation of clouds of fuel and hot water, toxic substances, and the explosion of pipelines and vessels with superheated liquid.
Hydrodynamic hazardous object (HDOO) - this is a hydraulic structure or natural formation that creates a difference in water levels before and after this object.
Hydraulically dangerous objects include: natural dams and hydraulic structures of the pressure front. When they break through, a breakthrough wave appears, which has great destructive power and extensive flood zones are formed.
Typical GDOO:
Dams;
Pressure basins of hydroelectric power stations and thermal power plants;
Retaining walls;
Water intakes.
Criteria for potential danger of preschool educational institutions:
Hydroelectric power station and thermal power station structures (according to electrical capacity):
Class 1 - power 1.5 million kW. and more;
2-4 class -/- up to 1.5 million kW.
Constructions of reclamation systems for irrigation or drainage area (thousand hectares):
1st class - > 300;
2nd class -100-300;
3rd class - 50-100;
4th grade -< 50.
Identification, i.e. Establishing the degree of danger of objects includes:
primary (initial) determination of the degree of danger of an economic object, based on an analysis of possible types of damage caused to humans and the environment;
identifying priority objects for subsequent analysis.
When performing identification two categories of hazards are taken into account
hazards arising during normal operation of the facility;
dangers of an emergency nature, incl. emergency situations in which there is a significant increase in the level of risk.
The procedure for initially determining the degree of danger of an object is implemented using a compiled table characterizing the possible damage from the operation of the object, as well as information on the amount of harmful substances and materials that are produced, processed, stored at the facility or transported.
Hydraulic structures are engineered or natural structures for water resources or to combat the destructive effects of water.
Hydraulic structures are created for the purpose of:
Using kinetic water energy (HES);
Hydroelectric power plant(HPP) - a power plant that uses the energy of water flow as an energy source. Hydroelectric power plants are usually built on rivers by constructing dams and reservoirs.
Land reclamation;
Melioration(lat. melioratio- improvement) - a set of organizational, economic and technical measures to increase the efficiency of use of land and water resources to obtain high and sustainable crop yields.
Protection of coastal areas from floods (dams);
A dam is a protective hydraulic structure that protects an area from the elements of water: floods, waves.
For water supply to cities and irrigation of fields;
Regulation of water level during floods;
Ensuring the activities of sea and river ports (canals, locks).
According to their purpose, hydraulic structures are divided into: water intake structures (dams, dams); water-discharging structures (canals);
water intake structures are designed to collect water (rivers, lakes) in order to use it for the needs of hydropower, water supply or field irrigation.
water-discharging the structures are designed to discharge excess (flood) water from reservoirs, as well as to pass water into the downstream of hydroelectric power stations (HPP). The pool is a part of the reservoir: the upstream is located upstream of the dam (sluice), the downstream is below the water pump structure.
1. Upper pool 2. lower
Special structures are designed to raise or lower ships from one water level to another (locks, ship lifts, etc..).
All these objects are certainly necessary in modern conditions for the development of the national economy, but they are potentially dangerous for humans and the environment.
Hydrodynamic accident- this is an emergency situation associated with the failure (destruction) of a hydraulic structure or part of it and the uncontrolled movement of large masses of water, causing destruction and flooding of large areas.
Causes of hydrodynamic accidents:
Natural phenomena or natural disasters (earthquakes, landslides, dams destroyed by flood waters, soil erosion, hurricanes, etc.);
Technogenic factors (destruction of structure structures, errors in design and operation, wear and aging of equipment, violation of water collection regime, etc.)
Wartime World Cup: modern means of destruction (SW) and terrorist attacks.
The main damaging factor of a hydrodynamic accident is breakthrough wave, which is formed in the downstream as a result of the upstream. The damaging effect of a breakthrough wave manifests itself in the form of a direct impact on people and structures of a mass of water moving at high speed, and the fragments of destroyed buildings and structures and other objects it moves.
Characteristic of flooding in the event of destruction of hydraulic structures is the significant speed of propagation (3-25 km/h), height (10-20 m) and impact force (5-10 t/cm2) of the breakthrough wave, as well as the speed of flooding of the entire territory.
In case of flooding, a threat to the life and health of people, in addition to the effect of the breakthrough wave, is posed by staying in cold water, neuropsychic stress, as well as flooding (destruction) of systems that ensure the life of the population.
Emergencies in the flood zone are often accompanied by secondary damaging factors: fires as a result of breaks and short circuits of electrical cables and wires, landslides and collapses as a result of soil erosion, infectious diseases due to contamination of drinking water and a sharp deterioration in the sanitary and epidemiological condition in populated areas near the flood zone. and areas where victims are temporarily accommodated, especially in the summer.
The consequences of a catastrophic flood can be aggravated by accidents at potentially hazardous facilities that fall within its zone.
In areas of catastrophic flooding, water supply systems, sewerage systems, drainage communications, and waste collection sites may be destroyed (eroded). As a result, sewage and debris pollute flood zones and spread downstream. The risk of the emergence and spread of infectious diseases is growing.
