Hydrodynamically hazardous object (HDO)- a structure or natural formation that creates a difference in water levels before and after it.
A dam break is the initial phase of a hydrodynamic accident and is a process of formation of a hole and an uncontrolled flow of water from the reservoir from the upstream (upstream - part of the river above the retaining structure (dam, lock) through the hole to the downstream (downstream - part of the river below the retaining structure) . Proran - a narrow channel in the body (embankment) of the dam, spit, shoal or straightened section of the river, formed as a result of erosion of the bend in the flood.
Types of accidents at hydrodynamically hazardous facilities
Hydrodynamic accidents– accidents at hydrodynamic facilities, which may result in catastrophic flooding.
Coastal flooding settlements and economic facilities located on them can occur as a result of the destruction of hydraulic structures (dams, dams, dams) located upstream of the river, or the system of irrigation facilities in irrigated areas.
Flooding is the coverage of the area with water. The term "flooding" here and in the following refers to the flooding of the area during the destruction of hydraulic structures.
There are four zones of catastrophic flooding in the flooded area:
First zone directly adjacent to the hydraulic structure and extends for 6-12 km. From him. The wave height here can reach several meters. A turbulent flow of water with a current speed of 30 km / h or more is characteristic. The wave passage time is 30 min.
Second zone- zone rapid flow(15-20 km/h). The length of this zone can be 15-25 km. Wave travel time is 50-60 km.
Third zone- Middle current zone (10-15 km/h) length up to 30-50 km. The wave passage time is 2-3 hours.
Fourth zone- zone of weak flow (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.
Zone of catastrophic flooding- flood zone, within which there were massive losses of people, farm animals and plants, significantly damaged or destroyed material values primarily buildings and other structures.
There are more than 30,000 reservoirs and several hundred storage facilities for industrial waste and waste in our country. There are 60 large reservoirs with a capacity of more than 1 billion m3. Hydraulic structures operated at 200 reservoirs and 56 waste storage facilities are potentially hazardous facilities.
Hydrodynamically dangerous objects called 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, dams, basins and surge tanks, hydroelectric facilities, small hydroelectric power stations and structures that are part of the engineering protection of cities and agricultural land. Hydrodynamic structures of the pressure front divided into permanent and temporary.
Permanent structures are called hydraulic structures used to perform any technological tasks (for the production of electricity, land reclamation, etc.).
Temporary structures include structures used during the construction and repair of permanent hydraulic structures.
In addition, hydraulic structures are divided into major and minor.
The main ones are structures of the pressure front, the breakthrough of which will entail disruption of the normal life of the population of nearby settlements, destruction, damage to residential buildings or facilities National economy. There are about 40 of these structures in Russia.
The secondary ones are 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 flooding of the area.
Causes of hydrodynamic accidents and their consequences
Causes of accidents accompanied by a breakthrough hydraulic structures of the pressure front and flooding of coastal areas, most often there are: destruction of the foundation of the structure and insufficiency of spillways; the impact of the forces of nature (earthquake, hurricane, collapse, landslide); structural defects, violation of the rules of operation and the impact of floods.
Out of 300 dam accidents (accompanied by dam failure) in various countries over 175 years, in 35% of cases the cause of the accident was the excess of the calculated maximum discharge flow (overflow of water over the crest of the dam).
AFFECTING FACTORS during hydrodynamic accidents several. In addition to the damaging factors characteristic of other floods (drowning, hypothermia), in case of 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.
The damaging effect of a breakthrough wave It manifests itself in the form of a direct impact on people and the structure of a mass of water moving at high speed, and the fragments of destroyed buildings and structures and other objects moved by it.
Breakthrough wave can be destroyed a large number of buildings and other structures. The degree of destruction will depend on their strength as well as on the height and speed of the wave.
In a catastrophic flood a threat to the life and health of people, in addition to the impact of a breakthrough wave, is being in cold water, neuropsychic overstrain, as well as flooding (destruction) of systems that ensure the life and activity of the population.
Emergencies in the flood zone are often accompanied by secondary damaging factors fires due to breaks and short circuits in electrical cables and wires, landslides and landslides 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 settlements near the flood zone and areas of temporary placement of victims, especially in the summer.
Consequences of accidents at hydrodynamically hazardous facilities may be difficult to predict. Being located, as a rule, within or upstream of large settlements 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 deaths of people, a long cessation of navigation, agricultural and fishery industries.
Losses of the population located in the zone of action of the breakthrough wave can reach 90% at night, and 60% during the day. Of the total population affected, the number of deaths can be 75% at night, 40% during the day.
The greatest danger is destruction of hydraulic structures pressure front - dams and dams of large reservoirs.
When they are destroyed, there is a rapid (catastrophic) flooding of large areas and the destruction of significant material values.
In June 1993, the dam of the Kisilevsky reservoir broke on the river. Kakve and severe flooding in Serov Sverdlovsk region. The emergency was triggered by a catastrophic flood resulting from heavy rains and the final phase of the spring flood.
With a sharp rise in water in the river. How 60 km2 in its floodplain, residential areas of the city of Serov and nine other settlements were flooded. 6.5 thousand were affected by the flood, 12 of them died. 1772 houses fell into the flood zone, of which 1250 became uninhabitable. Many industrial and agricultural facilities were damaged.
The consequences of catastrophic flooding can be exacerbated by accidents at potentially dangerous facilities that fall into its zone.
In areas of catastrophic flooding, water supply systems, sewerage systems, drain communications, places for collecting garbage and other waste can be destroyed (eroded). As a result, sewage, garbage and waste pollute the flood zones and spread downstream. Increasing risk of occurrence and spread infectious diseases. This is also facilitated by the accumulation of the population in a limited area with a significant deterioration in the material and living conditions of life.
Measures to reduce the consequences of accidents at hydrodynamically hazardous facilities
The safety of the population in case of catastrophic flooding is ensured by the early implementation of measures aimed at preventing it or limiting its scale. These measures: right choice location of the dam and settlements; limiting the construction of residential buildings and economic facilities in places exposed to a possible breakthrough wave; embankment of settlements and agricultural lands; creation of reliable drainage systems; carrying out bank protection works to prevent landslides and collapses; installation of waterproofing and special fortifications on buildings and structures; planting low-stemmed forests (from poplar, alder and birch) that can reduce the speed of the breakthrough wave.
In the event of a danger of a breakthrough of artificial dams, the following measures are taken to regulate the flow of water; planned discharge of water from the reservoir during the spring flood, timely discharge of water.
If there is a danger of a breakthrough of a natural reservoir, measures are taken to strengthen the walls of the dams.
In order to protect the population during catastrophic flooding, to prevent or minimize the extent of its damage, a set of organizational, engineering, technical and special measures is carried out.
Basic measures to protect the population
Timely notification of the population about the threat of catastrophic flooding and taking the necessary measures to protect it;
Independent exit of the population from the zone of possible catastrophic flooding before the breakthrough wave approaches;
Organized evacuation of the population to safe areas before the breakthrough wave approaches;
Shelter of the population on non-flooded parts of buildings and structures, as well as on elevated areas of the terrain;
Organization and conduct of rescue operations in the flood zone;
Providing qualified and specialized assistance to victims;
Carrying out urgent work to ensure the life of the population.
Rules for safe behavior in case of hydrodynamic accidents
Cities and other communities downstream of dams are potentially at risk of flooding. Therefore, people living in them should know the rules of safe behavior and the procedure for actions in case of hydrodynamic accidents.
Rule of thumb: Plan ahead for several possible evacuation routes to high ground. Prepare valuables and necessary things in case of evacuation.
After receiving a message about the danger of the collapse of the dam, immediately move to the nearest elevated area and stay there until rescuers arrive or the water subsides.
When driving through flooded areas, use caution and report damage or damage to power lines, sewer lines, and water lines to the appropriate utility company.
Do not eat food that has been in the water, and do not use untested water to drink. Wells with drinking water can be used after preliminary drainage (complete water purification).
Before entering the building, make sure that there is no danger of its further destruction.
When entering the premises, do not use matches or other open flames as a light source, but use battery lights. Do not use power sources until the electrical network has been checked. Open all doors and windows to dry out the building, remove debris, and allow floors and walls to dry.
From the history of hydrodynamic accidents
The St. Francis Dam in California has forever entered the analogues of engineering geology as a tragic example of human carelessness. It was built 70 km from Los Angeles in the San Francisco Canyon in order to accumulate water for its subsequent distribution through the Los Angeles water supply.
Filling the reservoir began in 1872, but the water reached maximum level only March 5, 1928. By that time, the seepage of water through the platinum was already causing concern among local residents, but the necessary measures were not taken.
Finally, on March 12, 1928, water broke through the thickness of the soil, and under its pressure the dam collapsed. There were no survivors of the catastrophes. It was a terrible sight.
Water rushed through the canyon like a wall about 40 m high. After 5 minutes, it demolished the power plant, which was 25 km away. downstream. All living things, all buildings were destroyed.
Then the water rushed into the valley. Here its height has decreased, and the destructive force has somewhat weakened, but remains quite dangerous.
Few in the upper part of the valley managed to stay alive. These were people who accidentally, accidentally escaped on trees or on debris floating in the stream.
By the time the flood has reached the coastal plain, it is 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. During this flood, more than 600 people died.
The collapse of the St. Francis dam was an example of how not to build hydraulic structures
hydrodynamic accident- this is an emergency event associated with the incapacitation (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 facility located on or near the water surface, intended for:
use of the kinetic energy of water movement in order to convert it into other types of energy;
cooling of exhaust vapors from TPPs and NPPs;
land reclamation;
coastal water protection;
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 the action of forces of nature (earthquakes, hurricanes, erosion of dams) or human impact, as well as due to design 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), limiting the flow, creating reservoirs and the difference in water levels along the riverbed.
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, formed as a result of its erosion.
The flow of water rushing into the hole forms a breakthrough wave, which has a significant height of the crest and speed of movement, and which has great destructive power. A breakthrough wave is formed by the simultaneous superposition of two processes: the fall of the reservoir waters from the upstream to the downstream, generating a wave, and a sharp increase in the volume of water at the point of fall, which causes water to flow 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 breach, the difference in water levels in the upstream and downstream, the hydrological and topographical conditions of the riverbed and its floodplain.
Wave advance speed The breakthrough is usually in the range of 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 , which consists in the rapid flooding of the breakthrough wave of the lower-lying terrain and the occurrence of a flood.
catastrophic flooding characterized by:
the maximum possible height and speed of the breakthrough wave;
the estimated time of arrival of the crest and the front of the breakthrough wave at the corresponding target;
the boundaries of the zone of possible flooding;
the maximum depth of flooding of a particular area of the terrain;
duration of flooding.
With the destruction of hydraulic structures, a part of the area adjacent to the river is flooded, which is called zone of possible flooding .
Depending on the impact hydroflow , formed during a hydraulic accident, in the territory of possible flooding, a zone of catastrophic flooding should be allocated, within which a breakthrough wave propagates, causing massive loss of people, destruction of buildings and structures, and destruction of other material assets.
The time during which the flooded areas can be 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, hydrodynamic accidents. Most of these accidents occur at potentially hazardous facilities.
Causes and sources of man-made accidents and disasters
The modern world is characterized by an increase in the scale of the consequences man-made accidents and disasters (whether aviation, rail or sea) 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 accident takes the lives of hundreds of people. Indeed, the dangers of technogenic origin have already become in terms of damage commensurate with negative natural phenomena for humans. There are many examples of this. So, 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, only in oil refining, according to experts, about 1500 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 dollars.
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 set of circumstances, taking into account the real reliability of mechanisms, devices, materials and a person, one destruction of an object is possible for 10000 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 annually one of them can statistically be a source of an accident. This circumstance is one of the reasons for the problems discussed. An object designed according to technical means and regulatory requirements, which is sufficiently reliable in conditions of small replication, loses statistical reliability during mass reproduction.
The increase in the 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 power supply of human society continues to grow continuously. The objects saturated with energy and using dangerous substances are more and more concentrated. In the name of economic indicators, their unit capacity is increasing. Pressure is increasing in various industrial apparatuses and transport communications, the network of which is becoming more and more extensive. In the energy sector alone, about 10 billion tons of standard fuel 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 commensurate with the arsenal of nuclear weapons accumulated in the world over the entire history of its existence.
The growth 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 understandable the widespread concern for the safety of chemical plants in the first place.
When clarifying the causes and sources of man-made accidents, including chemical ones, first of all, it is 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 inconsistency of the designs of industrial (or transport) control systems with the anatomical and physiological capabilities of a person. In such situations, people who directly control 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 appearance of a failure, and most single failures are Markov events, that is, they do not depend on the system's history and are easily localized in such a common way in the chemical industry as blocking. In practice, this means that a single failure simply leads to a stop in production. Accumulation of single failures leads to an accident.
Here is how this process is described by V.A. 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. Defects or deviations themselves do not yet pose a threat, but at a critical moment they will play a fatal role. during the Bhopal period (in Bhopal, India, ed.), for example, the accidents at this phase turned off the refrigeration devices on the tank with methyl isocyanate, depressurized the communication connecting this tank with the absorber of toxic gases, turned off the torch designed to burn them in emergency situations Before the accident at Chernobyl, several emergency protections were also turned off, and the reactor core was deprived of the mandatory minimum of rods that absorb neutrons.The accumulation of such deviations from the norm at this phase is either due to the unobservable operation of structural elements and materials due to the lack of necessary diagnostic tools, or, which happens much more often, with the fact that personnel get used to such deviations - 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, the restoration of the normal state of instruments and equipment is delayed, the process continues in dangerous conditions.
In the next phase, some kind of initiating event occurs, usually unexpected and rare. In Bhopal, this is a small amount of water that entered a container with methyl isocyanate through a permeable valve, causing an exothermic reaction, which was accompanied by a rapid rise in temperature and pressure of the metal isocyanate. In Chernobyl, this is the introduction of positive reactivity into the reactor core: an 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 actual accident 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, the assertion is true that in any complex system there will always be at least one non-Markovian failure that causes many subsequent ones. An avalanche-like process of failure growth is the development of an emergency situation into an accident with loss of control over the system and its transition to an affected 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 their processing, leads to the elimination of the identified non-Markovian failure. However, it can always be argued that this new system will contain a new potentially unobservable failure.
It is known that a chemical enterprise, as a source of increased danger, can be in two stable states - normal and affected. The transition from one stable state to another occurs through an unstable state, which is usually called an emergency.
The state of an enterprise, like any complex system, can be described by an n-dimensional vector in the phase space. The coordinates of such a vector are the parameters of technological processes. Usually, it is possible to indicate the lower and upper limits of the parameters within which the process proceeds stably. Going out of parameters is a sign of an emergency, 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 is considered localized. Otherwise, the object goes into a new stable state - the affected one, 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 environment. That is, a new n-dimensional state vector of the object arises, the coordinates of which are damaging factors: shock wave, thermal radiation, chemical contamination, etc. The possibilities of managing this vector are, as a rule, limited and require the involvement of significant regional forces and resources. Actually, this vector is the source of damage, the feature of which is almost complete uncontrollability in real time, and with increasing time from the moment of occurrence of an emergency to the transition to the affected state, the uncertainty increases non-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 the 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 warning systems), structural flaws in materials and the degree of their compliance with requirements, wear, corrosion and aging of structures - all this is the subject of research when determining 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 human error. At present, the proportion of accidents occurring as a result of incorrect actions of service personnel has noticeably increased 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, in conditions of time pressure. With psychological overload, some experts allow incorrect actions that lead to irreparable consequences.
World experience shows that in order to prevent emergencies, a set of legislative, economic and technical measures is needed, which in essence would represent an informal risk management system. The basis of such a system is a legislative initiative but the establishment of an acceptable risk level 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 providing the required level of safety are technical devices and measures.
A necessary element of such a system is the institution of state certification of hazardous industries in terms of safety, and the certificate is the main document for determining the amount of an enterprise's contribution to the insurance fund. The greater the risk. The more and contribution to the insurance fund. Compensation for damages due to accidents is carried out only through this fund. It could also be a source of funding for major industry programs to reduce the level of risk.
Potentially dangerous objects. Assessment of sources of technogenic danger.
An analysis of man-made emergencies 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 disasters at industrial facilities.
To facilitate the work on the definition and implementation of measures to prevent the occurrence of emergencies, reduce the severity of their consequences and create conditions for their elimination, it is important to systematize objects according to the feature that most affects the occurrence of emergencies at these objects. This sign is the danger that in the event of a production accident at this facility: the release of harmful substances into the environment (RV, SDYAV, BOV), explosion, fire, catastrophic flooding.
An object of economy or other purpose, in the event of an accident on which the death of cradles, farm animals and plants may occur, a threat to human health may occur, or damage to the national economy and the environment will be called a potentially dangerous object.
According to their potential danger, objects of the economy are divided into four groups:
chemically hazardous objects (CHOO);
radiation hazardous facilities (ROO);
fire and explosive objects (air defense);
hydrodynamically dangerous objects (HDOO).
Currently, there are more than 2,000 large enterprises in Russia alone, representing a danger of a regional or even global nature. Basically, these are chemically hazardous objects.
Chemically hazardous objects (CHOO) - this is an object, in the event of an accident at which or the destruction of which people, agricultural animals and plants can be injured, 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 the event of an accident at CSO - 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.
If a city, district, region has chemical hazardous facilities, then this administrative-territorial unit (ATE) can also be classified as chemically hazardous. Criteria characterizing the degree of such danger are defined in the following regulatory documents.
For objects - this is the number, for ATE - the proportion (%) of the population that may be in the zone of possible infection.
According to the scale of distribution of damaging factors, accidents at chemical facilities are divided into:
local (private) - if it does not go beyond the border of its sanitary protection zone;
local - also covers separate areas of nearby residential development;
regional - when vast territories of a city, district, region with a high population density fall into it;
global - complete destruction of a large chemical object.
Typical CHO using the most common SDYAV - 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 (ROO) - any object, incl. a nuclear reactor, a plant using nuclear fuel or processing nuclear material, as well as a place for storing nuclear material and a vehicle transporting nuclear material or a source of ionizing radiation, in the event of an accident or destruction of which exposure or radioactive contamination of people, farm animals can occur and plants, as well as the natural environment.
Typical ROOs include:
Atom stations;
enterprises for the processing of spent nuclear fuel and disposal of radioactive waste;
enterprises for the manufacture of nuclear fuel;
research and design organizations with nuclear installations and stands;
transport nuclear power plants;
military installations.
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 ROO. And this, in turn, depends on the power of the nuclear installation. The greatest danger is presented 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-explosive object (P BOO ) - this is an object where products and substances are produced, stored, used or transported, which acquire the ability to ignite (explosion) under certain conditions (accidents, initiation).
According to their potential danger, these objects are divided into 5 categories:
BUT- objects of oil, gas, oil refining, chemical, petrochemical industries, warehouses of oil products;
B- production of coal dust, wood flour, powdered sugar, synth. rubber
AT- sawmills, woodworking, carpentry, etc. workshops, oil storages;
G- metallurgical production, thermal shops, boiler rooms;
D- objects of processing and cold storage of non-combustible materials.
Especially dangerous objects of categories A, B and C.
Fires and explosions lead to the destruction of buildings and structures due to the combustion or deformation of their elements, equipment, the occurrence of an air shock wave (during an explosion), the formation of clouds of fuel assemblies and hot water, toxic substances, the explosion of pipelines and vessels with superheated liquid.
Hydrodynamic hazardous facility (HDOO) - this is a hydraulic structure or a 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 vast flood zones are formed.
Typical GDOO:
Dams;
Pressure basins of HPPs and TPPs;
retaining walls;
Water intakes.
Criteria of potential danger of ECE:
HPP and TPP facilities (in terms of electric power):
1st class - power 1.5 million kW. and more;
2-4 class -/- up to 1.5 million kW.
Constructions of reclamation systems with an area of irrigation or drainage (thousand hectares):
1st class -> 300;
2 class -100-300;
Grade 3 - 50-100;
4th grade -< 50.
Identification, i.e. establishment of the degree of danger of objects includes:
primary (initial) determination of the degree of danger of an object of the economy, based on an analysis of possible types of damage caused to humans and the environment;
allocation of priority objects for further analysis.
When carrying out identification two categories of hazards are taken into account
hazards arising during the 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 the initial determination of the degree of danger of an object is implemented using a table that characterizes 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.
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 in order to accumulate water for its subsequent distribution through the Los Angeles water supply.
The 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 thickness of 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 the 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 the destructive force weakened somewhat, but remained quite dangerous. Few in the upper part of the valley managed to stay alive.
They were people who accidentally escaped on 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 man. 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, dams, dams) located upstream of the river, or the system of irrigation facilities in irrigated areas.
Flooding is the covering of an area with water. The term "flooding" here and in the following refers to the flooding of the area during the destruction of hydraulic structures.
There are four zones of catastrophic flooding in the flooded area:
First zone directly adjoins the hydraulic structure and extends for 6-12 km from it. The wave height here can reach several meters. A turbulent flow of water with a current speed of 30 km / h or more is characteristic. Wave passage time - 30 min.
Second zone- fast current zone (15-20 km/h). The length of this zone can be 15-25 km. The wave passage time is 50-60 min.
Third zone- Middle current zone (10-15 km/h) up to 30-50 km long. The wave passage time is 2-3 hours.
Fourth zone- zone of weak flow (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.
Zone of catastrophic flooding- a flood zone, within which mass losses of people, farm animals and plants occurred, material assets were significantly damaged or destroyed, primarily buildings and other structures.
There are more than 30,000 reservoirs and several hundred storage facilities for industrial waste and waste in our country. There are 60 large reservoirs with a capacity of more than 1 billion m 3 . The distribution of hydrodynamically dangerous objects by regions 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, dams, water intakes and water intake structures, pressure basins and surge tanks, hydroelectric facilities, small hydroelectric power plants and structures that are part of the engineering protection of cities and agricultural land.
Hydrodynamic structures of the pressure front are divided into permanent and temporary.
Permanent called hydraulic structures used to perform any technological tasks (for the production of electricity, land reclamation, etc.).
The temporary ones are structures used during the construction and repair of permanent hydraulic structures.
In addition, hydraulic structures are divided into primary and secondary.
The main ones are structures of the pressure front, 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 are 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 base of structures and insufficiency of spillways;
- the impact of the forces of nature (earthquake, hurricane, collapse, landslide);
- structural defects, violation of the rules of operation and the impact of floods (Table 14).
The percentage of accidents for groups of dams of various types is presented in Table. fifteen.
Out of 300 dam accidents (accompanied by dam failure) in various countries over 175 years, in 35% of cases the cause of the accident was the excess of the calculated maximum discharge flow (overflow of water over the crest of the dam).
AFFECTING FACTORS during hydrodynamic accidents several. In addition to the damaging factors characteristic of other floods (drowning, hypothermia), in case of 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.
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 moved by it.
breakout wave a large number of buildings and other structures can be destroyed. The degree of destruction will depend on their strength, as well as on the height and speed of the wave.
In a catastrophic flood a threat to the life and health of people, in addition to the impact of a breakthrough wave, is exposure to cold water, neuropsychic overstrain, as well as flooding (destruction) of systems that ensure the vital activity of the population.
The consequences of such a flood may be exacerbated by accidents at potentially hazardous facilities falling within its zone. In areas of catastrophic flooding, water supply systems, sewerage systems, drain communications, places for collecting garbage and other waste can be destroyed (eroded). As a result, sewage, garbage and waste pollute the flood zones and spread downstream. The risk of the emergence and spread of infectious diseases is increasing. This is also facilitated by the accumulation of the population in a limited area with a significant deterioration in the material and living conditions of life.
CONSEQUENCES OF ACCIDENTS on hydrodynamically dangerous objects can be difficult to predict. Being located, as a rule, within or upstream of large settlements 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 deaths of people, a long cessation of navigation, agricultural and fishery industries.
Population loss, located in the zone of action of the breakthrough wave, can reach 90% at night, and 60% during the day. Of the total number of victims, the number of deaths can 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, there is a rapid (catastrophic) flooding of large areas and the destruction of significant material values.
In June 1993, there was a breakthrough of the dam of the Kiselev reservoir on the river. Kakve and severe flooding in Serov, Sverdlovsk region. The emergency 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. Kakve flooded 60 km 2 in its floodplain, residential areas of the city of Serov and nine other settlements. 6.5 thousand people suffered from the flood, 12 of them died. 1772 houses fell into the flood zone, of which 1250 became uninhabitable. Many industrial and agricultural facilities were damaged.
Hydrodynamic accidents are breaks of dams (locks, dams, dams, etc.), when breakthrough waves and catastrophic floods are formed, when a breakthrough flood is formed, resulting in sedimentation over large areas or washout of fertile, useful to man soils. These are accidents at hydraulic structures associated with the fact that water is spreading at high speed and there is a threat of an uncontrollable man-made emergency.
The most severe consequences of a hydrotechnical accident
The most severe consequences are necessarily accompanied by all hydrodynamic accidents - unexpected events closely associated with significant destruction of a hydraulic structure (lock, dam) and uncontrolled, without any control, movement of huge masses of water, causing flooding of large areas and damage to objects.
Floods turn out to be catastrophic, since after the accident there is a rapid flooding of the surrounding area by a breakthrough wave. The scale and degree of accidents completely depend on the technical condition and parameters of the hydroelectric complex, the volume of water in the reservoir, the degree and nature of the destruction of the dam, the characteristics of the catastrophic flood and the breakthrough wave, the time of day of the incident, the season, the terrain and many other factors. In such cases, the evacuation of the population is widely used, as in case of floods and floods.
Dam failure forecast
The situation is aggravated by the fact that there is an illegal construction of periodically flooded areas of hydroelectric facilities. This creates a prerequisite for the formation of emergency situations in such zones, especially in the event of an accident associated with hydrodynamics or floods. Forecasting a dam break is a thankless task, it is very difficult to predict, and most often a disaster occurs suddenly. Because of this reason, emergency, unplanned evacuations are relevant. As soon as a signal is received that hydrodynamic accidents have occurred, evacuation immediately begins. The breakthrough wave reaches 25 km/h on the plain and 100 km/h in the highlands and foothills. There is little time to leave the danger zone. Therefore, evacuation is successful if there is a local automated instant warning system.
Objects subject to safety declaration
The list of such objects is determined in our country by the Ministry of Emergency Situations of Russia and Rokhtekhnadzor. It includes industrial facilities with hazardous industries, all kinds of hydraulic structures, sludge collectors and tailings, where hydrodynamic accidents are possible. The Law on Industrial Safety defines the maximum doses of hazardous substances, which are the basis for the development of a declaration. It should be noted that this list is determined by Rokhtekhnadzor and the Ministry of Emergency Situations according to data received from the main departments for emergency situations and civil defense.
Hydrodynamic accidents, examples
Similar accidents happen all over the world from time to time. They, as already mentioned, cannot be foreseen. Let's give examples.
On 10/09/1963, such a disaster occurred at the Vaiont dam in Italy. An array of mountains with a volume of 0.24 km 3 collapsed into a small reservoir with a volume of only 0.169 km 3 , which was marked by overflow of more than 50 million m 3 of water through the dam. The result was a shaft of water 90 meters high. He destroyed several small settlements and two thousand people in just 15 minutes. And everything happened because of the raising of the local groundwater horizon, the cause of which was the construction of the dam.
08/07/1994 in Bashkiria, in the Beloretsky district, the dam of the Tirlyansky reservoir broke through. There was an abnormal discharge of water - 8.6 million m 3. Four small settlements were flooded, 85 good residential buildings were completely destroyed, 200 were partially destroyed. 29 people died, 786 were left homeless.
On August 18, 2002, due to a severe flood on the Elbe River near the city of Wittenberg, Germany, seven protective dams collapsed. A huge amount of water poured into the city, evacuated to urgently 40,000 people, 19 dead, 26 missing.
03/11/2005 in the south-west of Pakistan, Balochistan province, there were powerful showers. Because of them, there was a breakthrough of the hydroelectric dam 150 meters long near the town of Pasni. Several villages were flooded, 135 people died.
On October 5, 2007, in Thanh Hoa Province of Vietnam, on the Chu River, a sharp rise in the water level occurred, the dam of the Kyadat hydroelectric power station under construction was broken. Five thousand houses were in the flood zone, 35 people died. These are the most famous hydrodynamic accidents, examples known to all.
The tragedy at the Sayano-Shushenskaya HPP
Unfortunately, in our country not so long ago there was a very large catastrophe. Hydrodynamic accidents in Russia did not end with Bashkiria.
On August 17, 2009, the world's largest accident occurred at the Sayano-Shushenskaya HPP. She was supposed to close a series of accidents that occurred at hydroelectric power plants when the rotors of the units come out of their mines. A superficial, biased investigation of this catastrophe gives no guarantees on this score. Indeed, in order to establish the reasons for what happened to the hydroelectric generator, it is not enough to determine why and in what way the studs securing the iron cover of its turbine were destroyed. It is necessary to find the reasons for the exit of the rotor of the unit from its mine. And why so suddenly there was an overflow and flooding of the volume of the machine room and other underlying station premises, which led to the death of personnel.
Everyone agrees only that the unit was pushed out by the pressure of the water at which it worked that morning. When the hydraulic unit entered the zone not recommended for operation, the studs of the turbine cover itself broke. Further, the water began its effect on the rotor with the turbine cover and the cross, they began to move upward. That is, the unit could not be squeezed out under the influence of water pressure. The conclusion of experts is not consistent with physical laws. The results of the calculations confirm that the second hydraulic unit left the shaft on its own, when the impeller rotated not in the turbine mode, but in the motor mode, in the mode of the propeller.
Causes of the accident
This effect, when the rotors of hydraulic units rise, was studied back in the middle of the 20th century. Such hydrodynamic accidents have happened more than once in Russia; the accident at the Sayano-Shushenskaya HPP differs only in the death of the service personnel and in its scale. The reason for all this is the very rapid filling of the station premises with water. According to the conclusion of the commission, the suction pipe from the turbine at the time of the accident and further, with its development, was absolutely clean. The cause of the disaster is hidden behind the fatigue of the metal of the studs. But fatigue could not accumulate. The fastening of the cover is such that the studs are not responsible for its radial displacement relative to the turbine stator. Fitted pins are important. 
Moreover, they interfere with a displacement of only 8 microns, and not 160 microns, as expected. This is not in the materials of the investigation. From the photographs of the kinks of the studs, it can be seen that they are torn off "with meat", and not by the fatigue mechanism. The consequences of hydrodynamic accidents, the causes of the death of service personnel were not studied. Accidents, when the rotors of the units leave their mines, were at the following facilities: Kakhovskaya HPP, Grand Rapids HPP, Canada, Pamir-1, Sayano-Shushenskaya. The latter was to complete this list. However, there are no guarantees now. The causes of hydrodynamic accidents are not eliminated, so the likelihood of their recurrence remains.
How to act in case of an accident
A person must know how to act in case of an accident at hydrodynamic objects. The main thing here is that all residents of flood zones are well trained, aware of the possible dangers and prepared to act during flooding and when it threatens. When an alarm is received, the population must immediately evacuate. From the house you need to take documents, things of the very first necessity, valuables, a supply of clean drinking water and food for 2-3 days. In the house, apartment, it is necessary to close the doors tightly, turn off the gas and electricity, block the ventilation openings. If sudden flooding occurs, then in order to save yourself from the unexpected blow of a breakthrough wave, you need to take an elevated place. 
If there are no suitable buildings nearby, you need to use any obstacle that can help with moving water: large stones, road embankment, trees. Hold on to a stone, a tree, or another protruding object, otherwise the water currents and the air wave can drag along various solid objects, injuring them. Hydrodynamic accidents are very dangerous, and every effort must be made to escape. When a breakout wave approaches, dive deep at the very base of the wave. And try to get to unflooded territories.
Hydrodynamic accidents - what to do after
After the water subsides, people rush to return to their apartments. You need to remember some precautions. Especially beware of sagging or broken electrical wires. If you notice damage to sewer, gas or water mains, you must immediately report to emergency organizations and services. Products that have been in water should not be used for food. 
Drinking water must be tested, and wells must be drained, polluted water pumped out of them. You can enter the building after checking it for damage if it does not pose a danger to people. It is necessary to ventilate all rooms for several minutes by opening windows and doors. Candles or matches should not be used as a light source - there may be gas in the air. It is best to use electric lights. Until experts check the power grid, you can not use it.
Accident in St. Francis, California
The St. Francis Dam has entered the annals of engineering geology as an example of human carelessness. Filling the reservoir began in 1972, but the water reached its maximum on March 5, 1928. It has been leaking for a long time, but no action has been taken. And on March 12, water broke through the entire thickness of the soil, the dam collapsed under its pressure. Not a single witness survived. If you are researching hydrodynamic accidents, examples are no longer needed. The man himself created the catastrophe, as a result of which more than 600 people died, only a few from the upper half of the valley managed to stay alive. This collapse of the dam is an example of how not to build hydraulic structures.
Fundamentals of life safety
Nowadays, still in school curriculum a lot of time is devoted to this issue. In the senior classes there is a subject "OBZh". Hydrodynamic accidents are fairly well covered there. If a lot depends on the causes associated with human activity, then a catastrophe must be prevented. Their reasons can be: structural defects, design errors, violations during operation, water overflow through the dam, insufficient spillway, acts of sabotage, attacks by weapons on hydraulic structures. The most important thing is that the owners of hydraulic structures need to organize their safe operation. This will significantly increase the reliability of these objects.